CN101142694A - Phosphor mixture, light-emitting device, image display and lighting unit - Google Patents

Abstract

A light-emitting device having a high luminance and emitting a light more similar to the natural light and having a little color shift due to the variation of the emitted light amount. The device comprises a light source which emits light when a drive current is applied and at least one wavelength conversion material emitting a light of a wavelength different from that of the light emitted from the light source when it absorbs at least a part of the light from the light source. The expressions (D), (E) are satisfied where x1 (17.5) is the chromaticity coordinate value x of the light emitted at a drive current density of 17.5 A/cm<2>, y1(17.5) is the chromaticity coordinate value y thereof, x1 (70) is the chromaticity coordinate value x of the light emitted at a drive current density of 70 A/cm<2>, and y1 (70) is the chromaticity coordinate value y thereof. -0.006 = x1(17.5) -x1(70) =0.006 (D) -0.006 = y1(17.5) -y1(70) =0.006 (E).

Description

Light emitting device, white light emitting device, lighting device, and image display device

Technical Field

The present invention relates to a light emitting device, a white light emitting device, and an illumination device and an image display device using the same. In particular, the present invention relates to a light emitting device and a white light emitting device each including a light source such as a Light Emitting Diode (LED) or a Laser Diode (LD) and a wavelength conversion material such as a phosphor which absorbs light emitted from the light source and emits light having a wavelength different from that of the light, and an illumination device and an image display device each using the light emitting device.

Background

Conventionally, a light-emitting device for emitting white light, which is configured by combining a semiconductor light-emitting element such as a gallium nitride (GaN) -based light-emitting diode (LED) and a phosphor as a wavelength conversion material, is known to consume less power and have a long life.

However, it is pointed out that this light-emitting device has a low light amount in the red region (600 nm or more) and a low light amount in the blue-green region (480 nm to 510 nm), and thus has low color rendering properties. In addition, in the light emitting device, when a current flowing through the light emitting device is increased in order to obtain a high light amount, a temperature quenching phenomenon in which the temperature of the phosphor is increased by heat generation of the light emitting device and the fluorescence intensity of the phosphor is decreased is remarkable. Therefore, when this light-emitting device is used, the color mixture balance between the blue light emitted from the blue LED and the yellow light emitted from the phosphor is shifted, and the emission color of the white light-emitting device may be significantly different. Further, there is a problem that the average color rendering index Ra of the light-emitting device is low, and fluctuation of emission color when the light-emitting device is used becomes large, and it is sometimes difficult to obtain a stable emission color, and therefore further improvement is required.

In order to improve the problem of low color rendering of a light-emitting device, patent document 1 discloses the following: by using (Ca) _1-a-b Sr _a Eu _b )S:Eu ²⁺ Is a red phosphor represented by (Y) _1-a-b Gd _a Ce _b ) ₃ (Al _1-c Ga _c ) ₅ O ₁₂ A light-emitting device which emits white combined light is obtained by increasing the emission color of a green phosphor and a red component, and exciting the phosphors with a blue LED.

Non-patent document 1 discloses the use of SrGa ₂ S ₄ :Eu ²⁺ Patent document 2 discloses a white light emitting device using (Sr, ca, ba) (Al, ga) as a green phosphor and ZnCdS: ag, cl as a red phosphor ₂ S ₄ :Eu ²⁺ As the green phosphor, (Ca, sr) S: eu is used ²⁺ White light emission as red phosphorProvided is a device.

In particular, in a white light emitting device, a cold cathode tube or the like has been conventionally used as a light source for lighting, a backlight for a liquid crystal display, or the like. However, in recent years, a white light emitting device combining a light emitting element emitting blue light and a wavelength conversion material absorbing blue light and emitting yellow light has been developed as a light source instead of a cold cathode tube. In this white light emitting device, for example, an InGaN-based Light Emitting Diode (LED) is used as a light emitting element that emits blue light, and yttrium aluminate to which cerium is added is used as a wavelength conversion material that emits yellow light. However, since the spectrum of light emitted by the conventional white light emitting device is essentially lacking in a blue-green light component and a red light component, the conventional white light emitting device has low color rendering properties and low color reproducibility.

In order to solve this problem, it has been proposed to improve the color rendering property and the color reproducibility by adjusting the composition of yttrium aluminate (wavelength conversion material emitting yellow light) to emit yellow-green light and adding a substance which absorbs blue light to emit red light to yttrium aluminate to compensate for the deficiency of the red component in light emitted from a white light emitting device.

In addition, non-patent document 1 proposes a white light emitting device using a green phosphor SrGa as described above ₂ S ₄ :Eu ²⁺ And a red phosphor ZnCdS Ag Cl as a wavelength conversion material.

Further, white light emitting devices in which a light emitting element and a wavelength conversion material are combined have also been proposed in non-patent document 2, patent document 3, and the like.

In addition, regarding the image display device, a color display using an LED (light emitting diode) has been conventionally used as a large-sized display used in an advertisement board and an advertisement tower (patent document 4). In addition, it has also been proposed to use an LED for a projector type color display that projects and displays an image on a projection surface (patent document 5). In such an image display device such as a color display, LEDs are used as pixels, and when an image is displayed, light of a color corresponding to a pixel such as a red pixel, a blue pixel, or a green pixel is emitted from each LED.

As such an LED used for an image display device, an InGaN-based LED is generally used for blue and green pixels, and an InAlGaP-based LED is generally used for red pixels.

Patent document 1: japanese patent laid-open publication No. 2003-243715

Patent document 2: JP 2002-531956A

Patent document 3: japanese unexamined patent publication No. 2004-71726

Patent document 4: JP-A7-288341

Patent document 5: japanese patent laid-open publication No. 2004-184852

Non-patent document 1: soc, vol.150 (2003), pp.H57-H60

Non-patent document 2: bandongzhi display month 2003-4 month number pp.20-26 (2003)

However, according to the conventional technique described in patent document 1, although the color rendering properties of the white light emitting device are improved by the combination of these phosphors, there is still a problem that: the combined fluorescent bodies are all substances which obviously show a temperature extinction phenomenon, and when the current value flowing in the white light emitting device is increased, the luminous flux emitted by the light emitting device is reduced, and meanwhile, the luminous color is greatly deviated.

The red phosphor used is a sulfide-based red phosphor having low moisture resistance, and therefore, it is easily deteriorated and its synthesis is difficult, so that its production cost is high, and a white light-emitting device obtained by using the red phosphor also has problems of low durability and high price. Further, since the green phosphor used is yellowish in emission color, it has a problem that the emission in the blue-green region is insufficient and the color rendering property is poor.

Further, the prior art described in non-patent document 1 and patent document 2 has the following problems: sufficient luminous flux and color rendering properties cannot be obtained by the combination of these phosphors, the sulfide is easily aged when the white light emitting device is used, and since these phosphors are substances that remarkably exhibit temperature quenching, a large deviation in emission color occurs when the current to the white light emitting device is increased.

Disclosure of Invention

In order to solve the above-described problems of the prior art, a first object of the present invention is to provide a light-emitting device having high luminance and color rendering properties and little color difference in emission color. That is, the present invention provides a light-emitting device having high luminance, a light emission color closer to natural light, and less fluctuation of the light emission color with increase and decrease in the amount of emitted light, and an image display device and an illumination device using the light-emitting device as a light source.

In order to solve the above-described problems of the prior art, a second object of the present invention is to provide a light-emitting device having high luminous efficiency and color rendering property and little color difference of emitted light. That is, the present invention provides a light-emitting device having high luminance, a light emission color closer to natural light, and a small color difference of the light emission color occurring as the amount of emitted light increases, and an illumination device and an image forming apparatus using the light-emitting device as a light source.

Further, conventional white light emitting devices represented by the white light emitting devices described in non-patent documents 1 and 2 and patent document 3 have not yet sufficiently high color rendering properties.

The present invention has been made in view of the above problems, and a third object of the present invention is to provide a white light emitting device having a light source such as a light emitting element and a wavelength conversion material, and an illumination device using the white light emitting device, in which the color rendering property is improved as compared with a conventional white light emitting device.

In conventional image display devices such as LED-type color displays, the rate of decrease in emission intensity with temperature increase of LEDs (InAlGaP-based LEDs and the like) used as red pixels is higher than the rate of decrease in emission intensity with temperature increase of LEDs (InGaN-based LEDs and the like) used for non-red pixels such as green and blue pixels. Therefore, the conventional LED type image display device has a problem that when the temperature changes or when the LED generates heat with the lapse of time after lighting, the color tone of the displayed image changes, and color difference occurs.

For example, according to "journal of display, no. 4/2003, PP.42 to 46", the ratio I (B, 100)/I (B, 25) of the emission intensity I (B, 100) of an InGaN-based blue LED at 100 ℃ to the emission intensity I (B, 25) at 25 ℃ is about 95. In addition, the ratio I (G, 100)/I (G, 25) of the emission intensity I (G, 100) at 100 ℃ to the emission intensity I (G, 25) at 25 ℃ of the InGaN-based green LED was about 70. In contrast, the ratio I (R, 100)/I (R, 25) of the emission intensity I (R, 100) of the AlInGaP-based red LED at 100 ℃ to the emission intensity I (R, 25) at 25 ℃ is about 45. As described above, in the conventional image display device such as the LED type color display, the emission intensity of the red pixel using the red LED is greatly reduced as compared with the non-red pixel, and the color tone of the image display device is changed, thereby causing color difference.

In order to prevent such a change in color tone, a technique has been developed (see non-patent document 5) in which the change in color tone is corrected by measuring the light emission color and the temperature of the LED and performing feedback control. However, since a sensor or a feedback circuit for measuring temperature is complicated and requires a large cost, it is difficult to reduce the price of an image display device such as a color display.

The present invention has been made in view of the above problems, and a fourth object of the present invention is to provide an image display device with less color difference due to temperature change.

The present inventors have intensively studied to solve the above problems, and as a result, have found the following findings, and have completed the present invention.

First, the present inventors have conducted extensive studies to solve the above problems, and as a result, they have found that a light-emitting device having high luminance, high color rendering properties, and little color difference due to a change in light amount can be obtained by using a phosphor mixture in which the ratio of luminance obtained by excitation with blue light at two different specific temperatures is within a predetermined range and the difference in chromaticity coordinate values at the specific temperatures is within a predetermined range.

Secondly, the inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have found that a light-emitting device satisfying all of the following three characteristics is the above-mentioned preferable light-emitting device.

The light-emitting device has a light-emitting efficiency of 32lm/W or more.

2, the average color rendering index Ra is 85 or more.

No. 3, two different drive Current values 17.5A/cm ² And 70A/cm ² The difference in chromaticity coordinate values below is within the following ranges (F) and (G).

-0.01≤x ₁ (17.5)-x ₁ (70)≤0.01(F)

-0.01≤y ₁ (17.5)-y ₁ (70)≤0.01(G)

The present inventors have found that a light-emitting device having high luminous efficiency, high color rendering properties, and little color difference due to a change in light amount can be obtained by satisfying these conditions, and have reached the present invention.

Third, the present inventors have conducted extensive studies to solve the above problems, and as a result, have found that the color rendering properties of a white light emitting device can be improved by flattening the emission spectrum shape of white light emitted from the white light emitting device in the range of 500nm to 650nm as compared with the conventional one, thereby completing the present invention.

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that a color display with less color variation and less color difference can be provided by using a red pixel element, which is a red pixel, in place of an InAlGaP-based LED and is formed by combining a light emitting element and a high-performance phosphor (wavelength conversion material) that absorbs light emitted from the light emitting element and emits red light, so that the temperature dependence of the emission intensity of the three-color pixels of red, blue, and green can be made uniform, and have completed the present invention. As the high-performance phosphor, a phosphor having a high quantum yield with little decrease in luminous efficiency due to temperature rise is preferable, and a phosphor having little deterioration due to use as a phosphor is more preferable.

That is, the gist of the present invention is a light-emitting device including a light source that emits light when a drive current is passed therethrough and at least one wavelength conversion material that absorbs at least a part of the light emitted from the light source and emits light having a wavelength different from that of the light emitted from the light source, wherein the light-emitting device is characterized in that the wavelength of the light is set to 17.5A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (A) is denoted as x ₁ (17.5) the chromaticity coordinate value y is denoted as y ₁ (17.5) and will be at 70A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (2) is denoted as x ₁ (70) And recording the chromaticity coordinate value y as y ₁ (70) When x is above ₁ (17.5)、 y ₁ (17.5)、x ₁ (70) And y ₁ (70) Satisfying the following formulae (D) and (E) (claim 1).

-0.006≤x ₁ (17.5)-x ₁ (70)≤0.006(D)

-0.006≤y ₁ (17.5)-y ₁ (70)≤0.006(E)

Another gist of the present invention resides in a light-emitting device including a light source that emits light when a drive current is passed therethrough, and at least one wavelength conversion material that absorbs at least a part of the light emitted from the light source and emits light having a wavelength different from that of the light, wherein the light-emitting device has an efficiency of 32lm/W or more, an average color rendering index Ra of 85 or more, and a color rendering index of 17.5A/cm when the light-emitting device is to be used as a light-emitting device ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (2) is denoted as x ₁ (17.5) y is denoted by y ₁ (17.5) and will be at 70A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (2) is denoted as x ₁ (70) And y is denoted as y ₁ (70) The difference [ x ] between the chromaticity coordinate values x and y ₁ (17.5)-x ₁ (70)]And [ y ₁ (17.5)-y ₁ (70)]Satisfy the requirements ofThe following formulae (F) and (G) (claim 2).

-0.01≤x ₁ (17.5)-x ₁ (70)≤0.01(F)

-0.01≤y ₁ (17.5)-y ₁ (70)≤0.01(G)

At this time, the special color rendering index R ₉ Preferably 64 or more (claim 3).

It is preferable that a mixture of two or more phosphors is used as the wavelength conversion material, and the phosphor mixture used is such that BR (25) represents the luminance of fluorescence excited by blue light having a peak wavelength of 455nm at 25 ℃ and x represents the chromaticity coordinate value x ₂ (25) And the chromaticity coordinate value y is recorded as y ₂ (25) Further, the luminance of fluorescence obtained by exciting the phosphor mixture at 125 ℃ with blue light having a peak wavelength of 455nm is represented by BR (125), and chromaticity coordinate value x is represented by x ₂ (125) And the chromaticity coordinate value y is recorded as y ₂ (125) When, BR (25), x ₂ (25)、y ₂ (25) And BR (125), x ₂ (125)、y ₂ (125) Satisfying the following formulae (A), (B) and (C) (claim 4).

0.85≤BR(125)/BR(25)≤1.15(A)

-0.03≤x ₂ (25)-x ₂ (125)≤0.03(B)

-0.03≤y ₂ (25)-y ₂ (125)≤0.03(C)

The wavelength conversion material preferably contains at least one green phosphor having a peak of fluorescence intensity in a wavelength range of 500nm to 550nm (claim 5).

Further, it is preferable that the wavelength conversion material further contains at least one red phosphor having a peak of fluorescence intensity in a wavelength range of 610nm to 680nm (claim 6).

Another gist of the present invention is a lighting device including the above-described light-emitting device (claim 7).

Another gist of the present invention is an image display device including the light-emitting device (claim 8).

Another gist of the present invention resides in a white light emitting device including a light source and at least one wavelength conversion material that absorbs at least a part of light emitted from the light source and emits light having a wavelength different from that of the light, the white light emitting device emitting white light including light emitted from the wavelength conversion material, wherein a maximum emission intensity in a predetermined wavelength range of 500nm to 650nm in an emission spectrum of the white light is 150% or less of a minimum emission intensity in the predetermined wavelength range (claim 9).

In this case, it is preferable that the luminance of the wavelength conversion material at 100 ℃ is 80% or more of the luminance of the wavelength conversion material at 25 ℃ (claim 10).

In the white light emitting device, it is preferable that the wavelength conversion material has an absorbance of 50% or more with respect to light having an emission peak wavelength of the light source, and that the wavelength conversion material has an internal quantum efficiency of 40% or more (claim 11).

Another other gist of the present invention resides in a lighting device characterized by having the above white light emitting device (claim 12).

Another gist of the present invention resides in an image display device including a red pixel and at least one non-red pixel, wherein the red pixel includes a red light-emitting device including a red pixel light-emitting element and a red phosphor having a phosphor temperature dependence coefficient of 85 or more, the non-red pixel includes a blue pixel and/or a green pixel, the blue pixel includes a blue pixel light-emitting element, the green pixel includes a green pixel light-emitting element and a green phosphor having a phosphor temperature dependence coefficient of 85 or more, and when an emission intensity of the red pixel at 25 ℃ is denoted as I (R, 25) and an emission intensity at 100 ℃ is denoted as I (R, 100), and an emission intensity of the non-red pixel at 25 ℃ is denoted as I (N, 25) and an emission intensity at 100 ℃ is denoted as I (N, 100), a ratio of I (N, 100)/I (N, 25) to I (R, 100)/I (R, 25) is 90% or more.

According to the present invention, at least one of the following effects can be obtained.

First, by using the phosphor mixture having the characteristics satisfying the predetermined relational expression with respect to the luminance and chromaticity coordinate values of the present invention, it is possible to obtain a light-emitting device having high luminance and color rendering properties and less color difference due to increase or decrease in the amount of light, and to provide an image display device and an illumination device using the light-emitting device as a light source, which are excellent in color reproducibility in the light-emitting color range and have sufficient brightness.

Second, the present invention can provide a light-emitting device having high luminance, emitting light close to natural light, and having little color difference in emission color according to increase or decrease in the amount of emitted light, and an illumination device and an image display device using the light-emitting device as a light source.

Thirdly, according to the present invention, a white light emitting device excellent in color rendering properties and an illumination device using the white light emitting device can be obtained.

Fourth, according to the image display apparatus of the present invention, color difference caused by temperature change can be reduced.

Drawings

Fig. 1 is a view relating to a first light-emitting device of the present invention, which is a schematic sectional view illustrating an example of a light-emitting device composed of a phosphor mixture of the present invention as a wavelength conversion material and a semiconductor light-emitting element.

Fig. 2 is a view of a first light-emitting device according to the present invention, and is a schematic cross-sectional view illustrating an embodiment of a surface-emitting illumination device to which the light-emitting device shown in fig. 1 is mounted.

Fig. 3 is a diagram of a second light-emitting device according to the present invention, and is a cross-sectional view schematically illustrating a main portion of the light-emitting device as a first embodiment of the second light-emitting device according to the present invention.

Fig. 4 is a diagram of a second light-emitting device according to the present invention, and is a cross-sectional view schematically illustrating a main portion of a light-emitting device that is a second embodiment of the second light-emitting device according to the present invention.

Fig. 5 is a view of a second light-emitting device according to the present invention, and is a schematic cross-sectional view illustrating an embodiment of a surface-emission lighting device to which the light-emitting device shown in fig. 3 is mounted.

Fig. 6 is a schematic sectional view of a white light emitting device as one embodiment of the white light emitting device of the present invention.

Fig. 7 is a schematic sectional view of a white light emitting device as one embodiment of the white light emitting device of the present invention.

Fig. 8 is a schematic sectional view of a white light emitting device as one embodiment of the white light emitting device of the present invention.

Fig. 9 is a schematic cross-sectional view of a surface-emission lighting device as one embodiment of the white light-emitting device of the present invention.

Fig. 10 is a schematic sectional view of a display device using a white light emitting device as one embodiment of the white light emitting device of the present invention.

Fig. 11 is a schematic cross-sectional view illustrating a main part structure of a color display as one embodiment of an image display device of the present invention.

Fig. 12 is a diagram illustrating an embodiment of an image display device according to the present invention, and is a cross-sectional view schematically illustrating a main portion of a red light-emitting device.

Fig. 13 is a diagram illustrating an embodiment of an image display device according to the present invention, and is a cross-sectional view schematically illustrating an essential part of a green light-emitting device used as a green pixel which is one of non-red pixels according to the present embodiment.

Fig. 14 is a diagram illustrating an embodiment of an image display device according to the present invention, and is a cross-sectional view schematically illustrating an essential part of a blue light-emitting device used as a blue pixel which is one of non-red pixels according to the present embodiment.

Fig. 15 is a diagram schematically illustrating essential parts of a projector-type color display as one embodiment of an image display device of the present invention.

Fig. 16 is an exploded sectional view schematically illustrating a main part of the image display device according to the first embodiment of the image display device as an application example.

Fig. 17 is an exploded cross-sectional view schematically illustrating a main part of an image display device according to a second embodiment of an image display device as an application example.

Fig. 18 is an exploded cross-sectional view schematically illustrating a main part of an image display device according to a third embodiment of an image display device as an application example.

FIG. 19 illustrates the phosphor mixture of example 1-1 and yttrium aluminum garnet-based phosphor (Y, gd) installed in a pseudo-white light emitting device as a conventional product ₃ Al ₅ O ₁₂ Ce, and the temperature dependence of the fluorescence luminance. In the figure, the solid line represents the phosphor mixture of example 1-1, and the broken line represents the yttrium aluminum garnet phosphor.

FIG. 20 is a diagram illustrating an emission spectrum of the light-emitting device of example 2-1.

Fig. 21 is a diagram illustrating an emission spectrum of the light-emitting device of example 2-2.

FIG. 22 is a view showing an emission spectrum of the light-emitting device of comparative example 2-1.

FIG. 23 is an emission spectrum of light emitted from the surface-mounted white light-emitting device measured in example 3-1.

FIG. 24 is an emission spectrum of light emitted from the surface-mounted white light-emitting device measured in example 3-2.

FIG. 25 is an emission spectrum of light emitted from a surface-mounted white light-emitting device measured in comparative example 3-1.

FIG. 26 shows the emission spectrum of the red-light emitting device measured in example 4-1.

FIG. 27 shows the emission spectrum of the green light-emitting device measured in example 4-1.

FIG. 28 is an emission spectrum of a blue light-emitting device measured in example 4-1.

FIG. 29 shows emission spectra of a red light-emitting device, a green light-emitting device, and a blue light-emitting device constituting a full-color display device measured in example 4-2.

FIG. 30 is a graph showing the luminance maintenance ratios of the phosphors measured in example 5-1 and comparative example 5-1.

FIG. 31 is a graph showing the luminance maintenance ratios of the phosphors measured in example 5-2 and comparative example 5-2.

Description of the symbols

1 light emitting device

2 mounting lead wire

3 inner lead

4 semiconductor light emitting element

5 fluorescent material-containing resin part

6 conductive connecting wire

7 molded part

8-surface luminous lighting device

9 diffusion plate

10 support shell

101 110 light emitting device

102 112 frame

103 113 blue LED

104 114 fluorescent light-emitting part

105 115 silver paste

109 plane light-emitting lighting device

109A support case

109B diffuser plate

201 white light emitting device

202 light emitting element

203 204 wavelength converting material

205 block

205A recess

206 207 conductive terminal

208 connecting line

209 209a,209b adhesives

210 Beam

211 plane luminous lighting device

212 supporting housing

213 diffuser plate

221 display device

222 light guide plate

223 reflective film

224 diffuser plate

225 imaging unit

301 red pixel

302 green pixel (non-red pixel)

303 blue pixels (non-red pixels)

311 Red light emitting device

312 322, 332 boxes

313 red pixel light emitting element

314 Red phosphor

315 316, 325, 326, 335, 336 conductive terminal

317 327, 337 connecting wire

318 328 Binder

321 green light emitting device

323 light emitting element for green pixel

324 green phosphor

331 blue light emitting device

333 blue pixel light emitting element

338 403 moulded article

400 507 Unit pixel

401 501 substrate

402 hood component

502 light distribution lens

503 superposition lens

504 transmission type LCD

505 projection lens

506 Screen

601 601', 601' display device

602 light source

603R,603G phosphor portion

603B light transmission part

604 frame

605 polarizer

606 grating

607 polarization analyzer

631 transparent substrate

632 black matrix (black matrix)

661 663 transparent electrode

662 liquid crystal layer

Detailed Description

[ I. description about the first light-emitting device ]

The first light-emitting device of the present invention is explained below. However, the description of the constituent elements described below is a representative example of the embodiment of the first light-emitting device of the present invention, and the first light-emitting device of the present invention is not limited to these contents.

A first light-emitting device of the present invention is a light-emitting device having a light source and at least one wavelength converting material that absorbs at least a part of light emitted from the light source and emits light having a wavelength different therefrom.

Here, as the light source, any light source may be used as long as it emits light while a driving current is passed. For example, a semiconductor light emitting element which emits visible light, such as a semiconductor light emitting element such as an LED or an LD, can be used.

In addition, as for the wavelength converting material used in the first light emitting device of the present invention, any wavelength converting material may be used as long as it absorbs at least a part of the light emitted from the light source and emits light having a wavelength different therefrom. Generally, a phosphor mixture containing at least two phosphors is used as the wavelength converting material.

The first light-emitting device of the present invention has a wavelength conversion material that absorbs visible light emitted from a light source such as a semiconductor light-emitting element and emits visible light of a longer wavelength, and has high luminance, high color rendering properties, and little color difference with increase or decrease in light amount. Therefore, the first light-emitting device of the present invention having such characteristics can be suitably used for an image display device such as a color liquid crystal display, an illumination device such as a surface light-emitting device, and the like.

[ I-1. Characteristics of the first light-emitting device ]

The first light-emitting device of the present invention is to be at 17.5A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (2) is denoted as x ₁ (17.5) and will be at 70A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (2) is denoted as x ₁ (70) A light-emitting device satisfying the following formula (D).

-0.006≤x ₁ (17.5)-x ₁ (70)≤0.006(D)

In addition, the first light-emitting device of the present invention is to be set at 17.5A/cm ² The chromaticity coordinate value y of the emitted light obtained by the driving current density of (A) is denoted as y ₁ (17.5) and will be at 70A/cm ² The chromaticity coordinate value y of the emitted light obtained by the driving current density of (A) is denoted as y ₁ (70) A light-emitting device satisfying the following formula (E).

-0.006≤y ₁ (17.5)-y ₁ (70)≤0.006(E)

That is, it is preferably at 70A/cm ² The chromaticity coordinate value x and chromaticity coordinate value y of emitted light obtained from the driving current density of (2) are respectively set at 17.5A/cm ² Driving current density of (2) to obtain a chromaticity of the emitted lightThe difference between the standard value x and the chromaticity coordinate value y, i.e. the difference [ x ] of the chromaticity coordinate value ₁ (17.5)-x ₁ (70)]And [ y ₁ (17.5)-y ₁ (70)]Both differences are within ± 0.006. When the deviation of the chromaticity coordinate value of the emitted light caused by the change of the driving current density is larger than ± 0.006, the color difference becomes large and the emitted light color may be unstable when the amount of the emitted light is controlled by changing the driving current density.

The amount of shift between the chromaticity coordinate value x and the chromaticity coordinate value y is preferably as small as possible, and the amount of shift [ x ] is more preferably as small as possible ₁ (17.5)-x ₁ (70)]And [ y ₁ (17.5)-y ₁ (70)]At least one of them is within. + -. 0.005, more preferably at least one is within. + -. 0.004, still more preferably at least one is within. + -. 0.003. In addition, the offset amount [ x ] is preferable ₁ (17.5)-x ₁ (70)]And [ y ₁ (17.5)-y ₁ (70)]Both are within. + -. 0.006, more preferably within. + -. 0.005, still more preferably within. + -. 0.004, and still more preferably within. + -. 0.003.

[ I-2 ] example of specific configuration of first light-emitting device ]

Next, a first light-emitting device of the present invention will be described with reference to the drawings. Fig. 1 is a schematic sectional view illustrating one embodiment of a first light emitting device composed of a phosphor as a wavelength conversion material and a semiconductor light emitting element as a light source; fig. 2 is a schematic cross-sectional view illustrating an embodiment of a surface-emission lighting device mounted with the first light-emitting device shown in fig. 1. In fig. 1 and 2, 1 denotes a first light emitting device, 2 denotes a mounting lead, 3 denotes an inner lead, 4 denotes a semiconductor light emitting element, 5 denotes a phosphor-containing resin portion, 6 denotes an electrically conductive connection wire, 7 denotes a molding member, 8 denotes a surface-emission lighting device, 9 denotes a diffusion plate, and 10 denotes a support case.

As shown in fig. 1, the first light-emitting device 1 of the present invention is formed in a normal bullet shape, and the upper portion of a semiconductor light-emitting element 4 made of a GaN-based blue light-emitting diode or the like is covered with a phosphor-containing resin portion 5, and thereby fixed in an upper cup to which a lead 2 is attached. The phosphor-containing resin portion 5 is formed by mixing and dispersing a wavelength conversion material such as a phosphor mixture in a binder such as an epoxy resin or an acrylic resin and pouring the mixture into a cup. On the other hand, the semiconductor light emitting element 4 and the mounting lead 2 are electrically connected by a mounting member such as silver paste, the semiconductor light emitting element 4 and the inner lead 3 are electrically connected by an electrically conductive connecting wire 6, and the whole of these members is covered and protected by a molding member 7 formed of epoxy resin or the like.

Fig. 2 illustrates a surface-emitting illumination device 8 in which the light-emitting device 1 is mounted, and as shown in fig. 2, a large number of light-emitting devices 1 are provided on the bottom surface of a square support case 10 provided on the inner surface of the illumination device so as to be opaque to light such as a white smooth surface, a power supply and a circuit (not shown) for driving the light-emitting devices 1 are provided on the outer side thereof, and a diffuser plate 9 such as a milky acrylic plate is fixed to a cover portion corresponding to the support case 10 so as to make the light emission uniform.

Then, the surface-emission lighting device 8 is driven to emit blue light or the like by applying a voltage to the semiconductor light emitting element 4 of the light emitting device 1, and the phosphor mixture as a wavelength conversion material in the phosphor-containing resin portion 5 absorbs a part of the emitted light to emit light of a longer wavelength, and on the other hand, the emitted light of a longer wavelength is mixed with blue light or the like which is not absorbed by the phosphor, thereby obtaining light emission with high color rendering property, and the light is transmitted through the diffuser plate 9 and emitted from the upper part of the drawing, and illumination light which is uniform and bright in the plane of the diffuser plate 9 of the support case 10 is obtained.

Also, the first light-emitting device of the present invention can be mounted as a light source of an image display device such as a color liquid crystal display.

[ I-3. Constituent elements of first light-emitting device ]

Here, the light source and the wavelength conversion material used in the first light-emitting device of the present invention are explained. However, the first light-emitting device of the present invention may have components other than the light source and the wavelength conversion material.

[ I-3-1. Light Source of first light-emitting device ]

The light source is not particularly limited as long as it emits light when a driving current is applied, but a light source having an emission peak wavelength in the ultraviolet to visible light region is preferably used. The light emission peak wavelength of the light source is usually 370nm or more, preferably 380nm or more, and usually 500mn or less, preferably 480nm or less. When the amount is larger than the upper limit of the range or smaller than the lower limit of the range, it is difficult to obtain a light-emitting device having high luminous efficiency.

As an excitation light source having an emission peak wavelength in this range, a semiconductor light emitting element, a lamp, an electron beam, plasma, an electroluminescence element, or the like can be used, but a semiconductor light emitting element such as a Light Emitting Diode (LED) or a Laser Diode (LD) is particularly preferably used.

Examples of materials for a semiconductor light emitting element having an emission peak wavelength in the ultraviolet to visible light region include various semiconductors such as Boron Nitride (BN), silicon carbide (SiC), znSe, gaN, inGaN, inAlGaN, alGaN, BAlGaN, and BInAlGaN. Further, these elements may contain Si, zn, or the like as impurity elements as light emission centers. Wherein In _X Al _Y Ga _1-X-Y Nitride semiconductors containing Al and Ga represented by N (0 < X < 1, 0 < Y < 1, and X + Y < 1 In the formula) or nitride semiconductors containing In and Ga (hereinafter, sometimes referred to as "(In, al, ga) N-based compound semiconductors") can efficiently emit short-wavelength light from the ultraviolet region to the visible light, and can stably emit light even when the temperature and/or the driving current at the time of use change, and therefore, are suitable as materials for light-emitting layers.

Further, as a preferable structure of the semiconductor light emitting element, a homostructure, a heterostructure, or a double heterostructure having an MIS junction, a PIN junction, a pn junction, or the like can be given. For the semiconductor light emitting element, the light emitting wavelength can be selected according to the material of the semiconductor layer and/or the mixed crystal ratio thereof. In addition, the power can be increased by forming the active layer into a single quantum well structure or a multiple quantum well structure formed on the thin film that generates the quantum effect.

Among these, (In, al, ga) N-based LEDs or LDs using (In, al, ga) N-based compound semiconductors are preferable. This is because (In, al, ga) N LEDs and the like have much higher emission power and external quantum efficiency than SiC LEDs and the like that emit light In this region, and can obtain very bright light emission at very low power by combining with the wavelength conversion material such as the above phosphor. For example, for a current load of 20mA, the (In, al, ga) N system generally has 100 times or more light emission intensity of the SiC system, and can emit light stably with respect to changes In temperature and driving current during use, as compared with the GaAs system. In the (In, al, ga) N type LED and the like, al is preferably contained _X’ Ga _Y’ N-emitting layer, gaN-emitting layer, or In _X’ Ga _Y’ And an LED with an N light-emitting layer. In the GaN-based LED, in is contained In _X Ga _Y The LED having an N-type light-emitting layer is particularly preferable because it has very high emission intensity, and In is particularly preferable In (In, al, ga) N-type LD _X Ga _Y An LD having a multiple quantum well structure of an N layer and a GaN layer is particularly preferable because it has very strong emission intensity.

In the above, the value of X + Y is usually in the range of 0.8 to 1.2. Among the (In, al, ga) N-based LEDs, those In which Zn and/or Si is doped In the light-emitting layer or undoped LEDs are preferable In terms of adjusting the light-emitting characteristics.

The (In, al, ga) N-based LED comprises the light-emitting layer, p-layer, N-layer, electrode and substrate as essential components, and has Al layers with light-emitting layers inserted In N-type and p-type _X Ga _Y N layer, gaN layer or In _X Ga _Y An LED having a heterostructure between N layers or the like is preferable because it has high light emission efficiency, and an LED having a heterostructure made into a quantum well structure is more preferable because it has higher light emission efficiency. As the substrate, materials such as sapphire, spinel, siC, si, znO, gaAs, gaN, and the like are preferably used, and sapphire, znO, gaN, and the like are particularly preferably used.

The shape and size of the semiconductor light emitting element are not particularly limited, and a semiconductor light emitting element having a square face perpendicular to the flow direction of the drive current can be used, and one side of the square is usually 100 μm or more, preferably 200 μm or more. For example, "ES-CEBL912" manufactured by EPISTAR, and "C460MB" manufactured by Cree may be used.

In addition, one semiconductor light emitting element may be used alone, or two or more semiconductor light emitting elements may be used in combination. In addition, only one type of semiconductor light emitting element may be used, or two or more types of semiconductor light emitting elements may be used in combination.

The driving current density of the light source is a driving current per unit area on a surface perpendicular to a flowing direction of the driving current, and can be obtained by dividing a value of the driving current flowing through the light source by an area of the surface perpendicular to the flowing direction of the driving current. When two or more semiconductor light emitting elements are used in parallel, the driving current density of the light source can be obtained by dividing the value of the driving current flowing through the light source by the sum of the areas of the surfaces perpendicular to the flowing direction of the driving current.

In addition, the light source can be made to have a structure capable of effectively dissipating heat by providing a heat sink, improving a housing, or the like, as required.

[ I-3-2. Wavelength converting Material for first light-emitting device ]

The wavelength conversion material used in the first light-emitting device of the present invention may be any wavelength conversion material that absorbs at least a part of light emitted from the light source and emits light having a wavelength different from the absorbed light. Which wavelength converting material is used is arbitrary according to the use of the first light emitting device or the like. However, the phosphor mixture according to the present invention described below is generally used as a wavelength conversion material.

The phosphor mixture according to the present invention is a phosphor mixture containing at least two kinds of phosphors, and the luminance of a fluorescent light obtained by exciting the phosphor mixture at 25 ℃ with blue light having a peak wavelength of 455nm is represented by BR (25), and the chromaticity coordinate value x is represented by x ₂ (25) And the chromaticity coordinate value y is recorded as y ₂ (25)， The luminance of fluorescence obtained by excitation at 125 ℃ with blue light having a peak wavelength of 455nm is represented by BR (125), and the chromaticity coordinate value x is represented by x ₂ (125) And the chromaticity coordinate value y is recorded as y ₂ (125) In this case, the phosphor mixture satisfies the following formulae (A), (B) and (C).

0.85≤BR(125)/BR(25)≤1.15(A)

-0.03≤x ₂ (25)-x ₂ (125)≤0.03(B)

-0.03≤y ₂ (25)-y ₂ (125)≤0.03(C)

That is, the ratio [ BR (125)/BR (25) ] of the luminance of fluorescence [ BR (125) ] obtained by excitation of the phosphor mixture of the present invention at 125 ℃ with blue light having a peak wavelength of 455nm and the luminance [ BR (25) ] of fluorescence obtained by excitation at 25 ℃ with the blue light satisfies the above formula (A). When the ratio is less than 0.85 or more than 1.15, if the value of the current flowing through the blue LED is increased or decreased in order to change the amount of light obtained from the white light emitting device or the like, the change in the emission color obtained from the white light emitting device or the like using the phosphor mixture may be large, and a stable emission color may not be obtained.

This is because, when the amount of current flowing through the blue LED is increased or decreased to increase or decrease the amount of blue light, the temperature of the fluorescent material disposed in the vicinity of the blue LED changes as the amount of heat generated by the blue LED increases or decreases, and the intensity of fluorescence emitted from the fluorescent material greatly deviates from the intensity of fluorescence expected from the amount of blue LED. That is, when the amount of current supplied to the blue LED is increased or decreased in order to increase or decrease the light amount of the white light emitting device, the color mixture balance between the emission intensity of the blue LED and the fluorescence intensity of the fluorescent material emitted from the fluorescent material is lost, and the emission color of the white light emitting device to be obtained is largely changed.

Therefore, the ratio of the luminance [ BR (125)/BR (25) ] of the phosphor mixture according to the present invention is usually 0.85 or more, preferably 0.9 or more, and usually 1.15 or less, preferably 1.1 or less, and more preferably 1.05 or less. In order to obtain such a ratio of luminance, a phosphor having a small degree of temperature quenching phenomenon is preferably selected as the phosphor constituting the phosphor mixture. The temperature quenching phenomenon is a phenomenon in which the fluorescence intensity decreases as the temperature of the phosphor increases.

The phosphor mixture of the present invention has a peak wavelength of 455nm at 25 ℃The chromaticity coordinate value x of the fluorescence obtained by excitation with blue light is denoted as x ₂ (25) And recording the chromaticity coordinate value y as y ₂ (25) And the chromaticity coordinate value x of fluorescence obtained by excitation with blue light having a peak wavelength of 455nm at 125 ℃ is denoted as x ₂ (125) And recording the chromaticity coordinate value y as y ₂ (125) The difference [ x ] of chromaticity coordinate values x ₂ (25)-x ₂ (125)]Difference [ y ] from chromaticity coordinate value y ₂ (25)-y ₂ (125)]X is-0.03. Ltoreq. X each represented by the formula (B) ₂ (25)-x ₂ (125) 0.03 or less and-0.03 or less y represented by the formula (C) ₂ (25)-y ₂ (125) Less than or equal to 0.03. When the difference between the chromaticity coordinate value x and the chromaticity coordinate value y is less than-0.03 or more than 0.03, there is a possibility that a significant color difference occurs as the amount of light of a white light emitting device using the phosphor mixture increases or decreases.

The difference [ x ] of the chromaticity coordinate value x ₂ (25)-x ₂ (125)]Difference [ y ] from chromaticity coordinate value y ₂ (25)-y ₂ (125)]This is caused by a large difference in the degree of temperature extinction between two or more phosphors contained in the phosphor mixture. That is, in a mixture containing two or more phosphors having different emission colors, when the degree of temperature extinction of the phosphors is different, for example, when the decrease in fluorescence intensity with an increase in temperature of one phosphor is small and the decrease in fluorescence intensity with an increase in temperature of the other phosphor is large, and when these different emission intensities are added, the emission color changes with an increase in temperature, and different emission colors are formed.

Therefore, the difference [ x ] of chromaticity coordinate value x caused by the temperature change of the phosphor mixture ₂ (25)-x ₂ (125)]Difference [ y ] from chromaticity coordinate value y ₂ (25)-y ₂ (125)]The smaller the average, the more desirable the difference is, that is, the closer to zero, the smaller the average, the more desirable the difference is, usually, 0.03 or more, preferably, 0.02 or more, and more preferably, 0.015 or more, and usually, 0.03 or less, preferably, 0.02 or less, and more preferably, 0.015 or less.

In order to obtain a phosphor mixture having a small difference in chromaticity coordinate value x and a small difference in coordinate value y due to such a temperature change, it is preferable that the rates of change in fluorescence intensity due to such temperature extinction of a plurality of phosphors having different fluorescence colors constituting the mixture are substantially uniform. When phosphors having substantially equal rates of change in fluorescence intensity due to temperature quenching are combined, the mixed color such as white obtained by adding the fluorescence intensities of the phosphors is substantially the same, and color difference in emission color due to temperature change accompanying light amount change of the light-emitting device can be reduced regardless of temperature change.

In the description of the first light-emitting device of the present invention, a fluorescence spectrophotometer having a cooling mechanism using a peltier element and a heating mechanism using a heating element and equipped with a high-precision double monochromator subjected to sensitivity correction and/or wavelength correction is used for measuring the luminance, chromaticity coordinate value x, and chromaticity coordinate value y obtained by exciting a phosphor mixture with blue light having a peak wavelength of 455 nm. In this way, the cooling-heating mechanism is controlled to hold the surface temperature of the phosphor at 25 ℃ or 125 ℃ for a sufficient time in advance until the radiation thermometer can confirm that the surface temperature of the phosphor is constant, and then the luminance and chromaticity coordinate values are measured. In order to minimize the influence of blue light as excitation light, the half-peak width of the excitation light is reduced to 20nm or less, and the luminance Y, the chromaticity coordinate value x, and the chromaticity coordinate value Y are calculated using tristimulus values defined in JIS Z8724, using only a fluorescence spectrum of 470nm or more, and not using a fluorescence spectrum of less than 470 nm.

[ I-3-2-1. Green phosphor ]

In order to obtain a light-emitting device having particularly high color rendering properties even in a light-emitting device with little color difference, the wavelength converting material such as the phosphor mixture used in the first light-emitting device of the present invention preferably contains at least one green-based phosphor having a peak of fluorescence intensity in a wavelength range of 500nm to 550 nm. By using a green phosphor having a peak of fluorescence intensity in such a wavelength range, a light-emitting device having high color reproducibility in a green color region such as cyan, green, and yellow-green can be obtained, and by using the light-emitting device, a backlight for a display, an image display device (display), or an illumination device having excellent color reproducibility in the green color region can be obtained. When the peak of the fluorescence intensity of the green phosphor is less than 500nm or more than 550nm, the color reproducibility in the green region is lowered when the phosphor is used in combination with a blue LED, which is not preferable.

The green phosphor having a peak of fluorescence intensity in a wavelength range of 500nm to 550nm, which may be contained as the wavelength converting material according to the present invention, is not particularly limited as long as it preferably satisfies the above formulae (a) to (C) after being prepared into a wavelength converting material such as a phosphor mixture, but is preferably an oxide, a nitride, or an oxynitride because of its good thermal stability. For example, MSi can be mentioned ₂ N ₂ O ₂ Eu, M-Si-Al-O-N: ce, M-Si-Al-O-N: eu (wherein M represents one or more alkaline earth metals), preferably SrSi ₂ N ₂ O ₂ Eu, ca-Si-Al-O-N, ce, ca-Si-Al-O-N, eu, etc. In addition, as another example, a phosphor containing at least Ce as an emission center ion in a matrix crystal represented by the following formula (1) or (2) is preferable because the luminance is high, the fluorescence intensity in a green region is high, and the temperature extinction is small.

M ¹ _a M ² _b M ³ _c O _d (1)

Here, M ¹ Represents a divalent metal element, M ² Represents a trivalent metal element, M ³ To representTetravalent metal elements, a, b, c and d are numbers in the following ranges.

2.7≤a≤3.3

1.8≤b≤2.2

2.7≤c≤3.3

11.0≤d≤13.0

M ⁴ _e M ⁵ _f O _g (2)

Here, M ⁴ Represents a divalent metal element, M ⁵ Represents a trivalent metal element, and e, f and g are numbers in the following ranges.

0.9≤e≤1.1

1.8≤f≤2.2

3.6≤g≤4.4

The general formula (1) will be described in more detail below.

A preferred green phosphor for use in the present invention is a phosphor containing at least Ce as an emission center ion in a matrix crystal represented by the following general formula (1) wherein M is ¹ Represents a divalent metal element, M ² Represents a trivalent metal element, M ³ Represents a tetravalent metal element.

M ¹ _a M ² _b M ³ _c O _d (1)

M in the above general formula (1) ¹ The metal element representing divalent is preferably at least one divalent metal element selected from the group consisting of Mg, ca, zn, sr, cd, and Ba, more preferably at least one divalent metal element selected from the group consisting of Mg, ca, and Zn, and particularly preferably Ca, from the viewpoint of light emission efficiency and the like. In this case, ca may be a single system or a complex system with Mg. M ¹ Preferably, the elements are selected substantially from the preferred elements listed herein, but other divalent metal elements may be contained within a range not impairing the performance.

Further, M in the general formula (1) ² The trivalent metal element is preferably M, as described above, from the viewpoint of luminous efficiency ² Is at least one trivalent metal element selected from the group consisting of Al, sc, ga, Y, in, la, gd and Lu, more preferably at least one trivalent metal element selected from the group consisting of Al, sc, Y and Lu, and particularly preferably Sc. In this case, sc may be a single system or a complex system with Y or Lu. M is a group of ² Preferably, the element is substantially selected from the preferable elements listed here, but other trivalent metal elements may be contained within a range not impairing the performance.

M in the general formula (1) ³ The tetravalent metal element preferably contains at least Si, and usually, M is preferred in view of light emission efficiency ³ The tetravalent metal element is represented by Si in an amount of 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 90 mol% or more. As M ³ The tetravalent metallic element other than Si in (a) is preferably at least one tetravalent metallic element selected from the group consisting of Ti, ge, zr, sn and Hf, more preferably at least one tetravalent metallic element selected from the group consisting of Ti, zr, sn and Hf, particularly preferably Sn. M is particularly preferred ³ Is Si. M ³ It is preferable to substantially select from the preferable elements mentioned here, but other tetravalent metallic elements may be contained within a range not impairing the performance.

Here, the phrase "in a range where performance is not impaired" means that M is relative to M ¹ 、 M ² And M ³ Each metal element contains other elements usually 10 mol% or less, preferably 5 mol% or less, and more preferably 1 mol% or less.

In the general formula (1), a, b, c and d are numbers in the following ranges.

2.7≤a≤3.3

1.8≤b≤2.2

2.7≤c≤3.3

11.0≤d≤13.0

The green phosphor preferably used in the present invention contains at least Ce as a constituent in the matrix crystal represented by the above general formula (1)Is a luminescence center ion element, and the luminescence center ion element is substituted at M ¹ 、M ² 、 M ³ The values of a to d vary within the above range because of the positions of the crystal lattices of any metal element, the gaps between the crystal lattices, and the like, but the crystal structure of the present phosphor is a garnet crystal structure, and generally a body-centered cubic lattice crystal structure of a =3, b =2, c =3, and d =12 is adopted.

The luminescence center ion element contained in the compound matrix having the crystal structure contains at least Ce, and may further contain at least one divalent to tetravalent element selected from the group consisting of Cr, mn, fe, co, ni, cu, pr, nd, sm, eu, tb, dy, ho, er, tm, and Yb in order to fine-tune the luminescence characteristics. In particular, the alloy may contain one or more divalent to tetravalent elements selected from the group consisting of Mn, fe, co, ni, cu, pr, sm, eu, tb, dy and Yb, and may contain divalent Mn, divalent to trivalent Eu, trivalent Tb or trivalent Pr.

The addition amount of Ce as a luminescence center ion (activator) is preferably appropriately adjusted. When the amount of Ce added is too small, the amount of ions emitting light is too small, and the emission intensity is low, while when the amount of Ce added is too large, the concentration quenching becomes large, and the emission intensity is lowered. From the viewpoint of emission intensity, the concentration of Ce is as follows: the concentration thereof is preferably in the range of 0.0001 to 0.3, more preferably in the range of 0.001 to 0.1, and further preferably in the range of 0.005 to 0.05 in terms of a molar ratio relative to 1 mole of the parent crystal represented by the above general formula (1).

The phosphor having at least Ce as an emission center ion in the host crystal represented by the general formula (1) is excited by light of 420 to 480 nm. The emission spectrum has a peak at 500 to 510nm and has a wavelength component of 450 to 650 nm.

Next, the general formula (2) will be described in more detail.

The green phosphor of the present invention preferably contains at least Ce as an emission center ion in a matrix crystal represented by the following general formula (2), wherein M is ⁴ Represents a divalent metal element, M ⁵ Represents a trivalent metal element.

M ⁴ _e M ⁵ _f O _g (2)

Further, M in the above general formula (2) ⁴ The metal element representing divalent is preferably at least one divalent metal element selected from the group consisting of Mg, ca, zn, sr, cd and Ba, more preferably at least one divalent metal element selected from the group consisting of Mg, sr, ca and Zn, further preferably Sr or Ca, and particularly preferably Ca, from the viewpoint of luminous efficiency and the like. In this case, ca may be a single system or a complex system with Mg. M is a group of ⁴ Preferably, the divalent metal element is substantially selected from the preferable elements listed here, but other divalent metal elements may be contained within a range not impairing the performance.

Further, M in the general formula (2) ⁵ The trivalent metal element is preferably at least one trivalent metal element selected from the group consisting of Al, sc, ga, Y, in, la, gd, and Lu, more preferably at least one trivalent metal element selected from the group consisting of Al, sc, Y, and Lu, and particularly preferably Sc, from the viewpoint of light emission efficiency and the like. In this case, sc may be a single system or a complex system with Y or Lu. M ⁵ Preferably, the trivalent metal element is selected from the preferable elements listed here, but may be contained in a range not impairing the performance.

Here, the phrase "in a range where performance is not impaired" means that M is contained in the above-mentioned compound ⁴ And M ⁵ Each metal element contains other elements usually 10 mol% or less, preferably 5 mol% or less, and more preferably 1 mol% or less.

In the general formula (2), the element ratios represented by e, f and g are preferably numbers in the following ranges, respectively, in terms of light emission characteristics.

0.9≤e≤1.1

1.8≤f≤2.2

3.6≤g≤4.4

The green phosphor preferably used in the present invention contains at least Ce as an emission center ion element in the matrix crystal represented by the above general formula (2), and the emission center ion element is substituted with M ⁴ 、M ⁵ Since the position of the lattice of any one of the metal elements, the gap between the lattices, or the like, the value of e to g varies within the above range, but e =1, f =2, and g =4 are preferable.

The luminescence center ion element contained in the compound matrix having the crystal structure may contain at least Ce, and may further contain at least one divalent to tetravalent element selected from the group consisting of Cr, mn, fe, co, ni, cu, pr, nd, sm, eu, tb, dy, ho, er, tm, and Yb, in particular, may contain at least one divalent to tetravalent element selected from the group consisting of Mn, fe, co, ni, cu, pr, sm, eu, tb, dy, and Yb, and it is preferable to add divalent Mn, divalent to trivalent Eu, trivalent Tb, or trivalent Pr.

The addition amount of Ce as a luminescence center ion (activator) is preferably appropriately adjusted. When the amount of Ce added is too small, the amount of ions emitting light is too small, and the emission intensity is low, while when the amount of Ce added is too large, the concentration quenching becomes large, and the emission intensity is lowered. From the viewpoint of emission intensity, the concentration of Ce is as follows: the concentration thereof is preferably in the range of 0.0001 to 0.3, more preferably in the range of 0.001 to 0.1, and further preferably in the range of 0.005 to 0.05 in terms of a molar ratio relative to 1 mole of the parent crystal represented by the above general formula (2).

Among the phosphors having a host crystal represented by the general formula (2) containing at least Ce as an emission center ion, ca is particularly preferable ₃ Sc ₂ Si ₃ O ₁₂ Ce, ca with Mg added ₃ Sc ₂ Si ₃ O ₁₂ :Ce。

Among these, a phosphor to which Mg is added is preferable, and particularly a phosphor having a Mg concentration of 0.001 or more, preferably 0.01 or more, and 0.5 or less, preferably 0.3 or less, with respect to 1 mol of the host crystal is preferable. As such a phosphor, there may be mentionedTo cite, for example, ca _2.97 Ce _0.03 Sc _1.97 Mg _0.03 Si ₃ O ₁₂ 、Ca _2.97 Ce _0.03 Sc _1.94 Mg _0.06 Si ₃ O ₁₂ 、 Ca _2.94 Ce _0.03 Sc _1.94 Mg _0.06 Si ₃ O ₁₂ 、Ca _2.94 Ce _0.06 Sc _1.97 Mg _0.03 Si ₃ O ₁₂ 、 Ca _2.94 Ce _0.06 Sc _1.94 Mg _0.06 Si ₃ O ₁₂ 、Ca _2.94 Ce _0.06 Sc _1.9 Mg _0.1 Si ₃ O ₁₂ 、 Ca _2.9 Ce _0.1 Sc _1.97 Mg _0.03 Si ₃ O ₁₂ 、Ca _2.9 Ce _0.1 Sc _1.94 Mg _0.06 Si ₃ O ₁₂ And so on.

In addition, among the phosphors having a host crystal represented by the general formula (2) containing at least Ce as an emission center ion, ce is particularly preferable _0.01 Ca _0.99 Sc ₂ O ₄ 、Ce _0.007 Ca _0.993 Sc ₂ O ₄ 、 Ce _0.013 Ca _0.987 Sc ₂ O ₄ . Ce with a part of Ca substituted by Sr _0.01 Ca _0.94 Sr _0.05 Sc ₂ O ₄ 、 Ce _0.01 Ca _0.89 Sr _0.1 Sc ₂ O ₄ 、Ce _0.01 Ca _0.84 Sr _0.15 Sc ₂ O ₄ Are also examples of preferred phosphors. In addition, since the color purity of green can be improved by adding Sr, the above phosphor is preferably used for an image display device.

These phosphors are preferred because their emission peak wavelength is a relatively long wavelength and their luminance is high.

These phosphors may be used alone, or two or more of them may be used in any combination and ratio.

[ I-3-2-2. Red phosphor ]

In the first light-emitting device of the present invention, in order to obtain a light-emitting device having particularly high color rendering properties even in a light-emitting device having little color difference, it is preferable that the wavelength conversion material such as a phosphor mixture used in the light-emitting device contains at least one red phosphor having a peak of fluorescence intensity in a wavelength range of 610nm to 680 nm. By using a red phosphor having a peak of fluorescence intensity in such a wavelength range, a light-emitting device having high color reproducibility in a red color region such as orange, red, and deep red can be obtained, and by using the light-emitting device, a backlight for a display, an image display device (display), or an illumination device having excellent color reproducibility in the red color region can be obtained. When the peak of the fluorescence intensity of the red phosphor is less than 610nm, the color reproducibility in the red color range is reduced when the phosphor is used in combination with a blue LED, and when the peak of the fluorescence intensity of the red phosphor is more than 680nm, the color rendering property is increased, but the luminance tends to be reduced.

The red phosphor having a peak of fluorescence intensity in a wavelength range of 610nm to 680nm, which may be contained in the wavelength converting material according to the present invention, is not particularly limited as long as it preferably satisfies the above formulae (a) to (C) after being prepared as a wavelength converting material such as a phosphor mixture, but is preferable because an oxide, a nitride, or an oxynitride has good thermal stability. For example, MSi can be mentioned ₇ N ₁₀ :Eu、M ₂ Si ₅ N ₈ Eu (wherein M represents one or two or more alkaline earth metals), preferably BaSi ₇ N ₁₀ :Eu、(Ca，Ba，Sr) ₂ Si ₅ N ₈ Eu, etc. Another example is a phosphor represented by the following general formula (3), which is preferably used because the wavelength conversion material such as the phosphor mixture contains the phosphor, and thus the luminance is high, the fluorescence intensity in the red region is high, and the temperature extinction is small.

M _a A _b D _c E _d X _e (3)

In the general formula (3), M is one or more elements selected from the group consisting of Mn, ce, pr, nd, sm, eu, tb, dy, ho, er, tm, and Yb, a represents one or more elements selected from the group consisting of divalent metal elements other than M elements, D represents one or more elements selected from the group consisting of tetravalent metal elements, E represents one or more elements selected from the group consisting of trivalent metal elements, and X represents one or more elements selected from the group consisting of O, N, F.

In the general formula (3), a, b, c, d and e are numbers in the following ranges, respectively.

0.00001≤a≤0.1

a+b＝1

0.5≤c≤4

0.5≤d≤8

0.8×(2/3+4/3×c+d)≤e

e≤1.2×(2/3+4/3×c+d)

In the general formula (3), M is one or more elements selected from the group consisting of Mn, ce, pr, nd, sm, eu, tb, dy, ho, er, tm, and Yb, and among them, one or more elements selected from the group consisting of Mn, ce, sm, eu, tb, dy, er, and Yb are preferable, and Eu is more preferably contained.

In the general formula (3), a is one or two or more elements selected from the group consisting of divalent metal elements other than M element, and among them, one or two or more elements selected from the group consisting of Mg, ca, sr and Ba are preferable, and Ca is more preferable.

In the general formula (3), D is one or two or more elements selected from the group consisting of tetravalent metallic elements, and among them, one or two or more elements selected from the group consisting of Si, ge, sn, ti, zr, and Hf are preferable, and Si is more preferable.

In the general formula (3), E is one or two or more elements selected from the group consisting of trivalent metal elements, and among them, one or two or more elements selected from the group consisting of B, al, ga, in, sc, Y, la, gd, and Lu are preferable, and Al is more preferable.

In the general formula (3), X is one or two or more elements selected from the group consisting of O, N and F, and among them, N or N and O are preferable. When X is N or O, the ratio of O to (O + N) in the phosphor is preferably 0 < { (the number of atoms of O)/(the number of atoms of O + the number of atoms of N) } or less than 0.5. When the value is too large beyond this range, the light emission intensity may be reduced. From the viewpoint of emission intensity, the value is more preferably 0.3 or less, and when the value is 0.1 or less, the phosphor is a red phosphor having an emission peak wavelength at an emission wavelength of 640nm to 660nm and good color purity, and therefore the value is more preferably 0.1 or less. Further, by controlling this value to 0.1 to 0.3, the emission peak wavelength can be adjusted to 600nm to 640nm, and a light-emitting device with high luminance is obtained because the human visual acuity is close to a high wavelength region, which is preferable from other points of view.

In the general formula (3), a represents the content of the element M as the center of luminescence, and the atomic number ratio a { where a = (the atomic number of M)/(the atomic number of M + the atomic number of a) } of M to (M + a) in the phosphor is controlled to be 0.00001 to 0.1. When the value a is less than 0.00001, the number of M as the light emission center is small, and the light emission luminance may be lowered. When the value of a is larger than 0.1, the interference between M ions causes concentration quenching, and the luminance may decrease. Where M is Eu, the value a is preferably 0.002 to 0.03, from the viewpoint of high emission luminance.

In the general formula (3), c is the content of D element such as Si, and is an amount of 0.5. Ltoreq. C.ltoreq.4. Preferably 0.5. Ltoreq. C.ltoreq.1.8, more preferably c =1. When c is less than 0.5 and more than 4, the luminance may be lowered. When c is in the range of 0.5. Ltoreq. C.ltoreq.1.8, the emission luminance is high, and when c =1, the emission luminance is particularly high.

In the general formula (3), d is the content of E element such as Al, and is an amount of 0.5. Ltoreq. D.ltoreq.8. Preferably 0.5. Ltoreq. D.ltoreq.1.8, more preferably d =1. When the value of d is less than 0.5 or more than 8, the emission luminance may decrease. When d is in the range of 0.5. Ltoreq. D.ltoreq.1.8, the emission luminance is high, and when d =1, the emission luminance is particularly high.

In the general formula (3), e is the content of X element such as N, and is an amount of 0.8X (2/3+4/3 xct + d) to 1.2X (2/3+4/3 xc + d). More preferably e =3. When the value of e is outside the above range, the emission luminance may decrease.

Of the above compositions, preferred compositions having high emission luminance are those in which at least M element contains Eu, A element contains Ca, D element contains Si, E element contains Al, and X element contains N. Among them, it is preferable that the M element is Eu, the A element is Ca, the D element is Si, the E element is Al, and the X element is N or a mixture of N and O.

The phosphor is excited by light having a wavelength of at most 580nm or less, and particularly, excitation by light having a wavelength of 400 to 550nm is most effective. The luminescence spectrum has a peak at 580 nm-720 nm.

Further, the red phosphor is preferable because the thermal stability of the crystal close to the closest packing structure is good. Further, the nitrogen atom contained in the red phosphor is preferably a nitrogen atom having a 3-position, because it is excellent in thermal stability. The content of 3-coordinated nitrogen atoms in the nitrogen atoms contained in the red phosphor is preferably 20% or more, more preferably 40% or more, and particularly preferably 60% or more. Here, M ₂ Si ₅ N ₈ Eu (wherein M represents one or two or more alkaline earth metals) has a nitrogen atom 3-coordinated content of 50%, and the phosphor represented by the above formula (3) is, for example, (Ca, sr) AlSiN ₃ Eu, wherein the content of 3 coordinated nitrogen atoms is 66%.

These phosphors may be used alone, or two or more of them may be used in any combination and ratio.

The particle size of the phosphor is usually 150 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. When the particle diameter exceeds this range, the fluctuation of the emission color is large in the case of producing a white light emitting device, and it is difficult to uniformly disperse the phosphor when the phosphor and the binder (sealant) are mixed. The lower limit of the particle size is usually 1 μm or more, preferably 5 μm or more. When the particle diameter is less than this range, the luminous efficiency may be lowered. In addition, the particle size distribution of the phosphor is preferably narrow.

In addition, when the green phosphor and the red phosphor are used in combination, the content of the phosphor is related to the balance between the light emission efficiencies of the green phosphor and the red phosphor and how much the red phosphor absorbs the light emitted from the green phosphor, but the green phosphor is preferably contained in an amount of usually 65% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, and particularly preferably 85% by weight or more, based on the total weight of the green phosphor and the red phosphor. When the weight percentage of the green phosphor is less than this range, a white light-emitting device having high luminance and high color rendering properties and exhibiting preferable white color cannot be obtained, and a white light-emitting device having strong red color may be formed. In order to produce a white light emitting device, the weight percentage of the green phosphor is usually 99% or less, preferably 98% or less, and more preferably 97% or less.

In addition, it is preferable that the absorption efficiency of the red-based phosphor at the emission wavelength emitted from the semiconductor light-emitting element is higher than the absorption efficiency of the red-based phosphor at the emission peak wavelength of the green-based phosphor, and in this case, the probability that the light emitted from the semiconductor light-emitting element is absorbed by the red-based phosphor to excite the red-based phosphor to emit light is higher than the probability that the light emitted from the green-based phosphor is absorbed by the red-based phosphor to excite the red-based phosphor to emit light, and a light-emitting element with higher emission efficiency can be obtained.

[ I-3-2-3. Luminous efficiency of phosphor ]

The phosphor constituting the wavelength conversion material such as the phosphor mixture according to the present invention has an emission efficiency of preferably 20% or more, more preferably 30% or more, and further preferably 40% or more, and the higher the emission efficiency, the better. If the emission efficiency of the phosphor is less than 20%, a light-emitting device with high luminance cannot be obtained. The luminous efficiency is defined as the ratio of the quantum number of light emitted from the phosphor to the quantum number of light irradiated to the phosphor.

Next, a method of calculating the light emission efficiency of the phosphor defined in the first light-emitting device of the present invention from the product of the quantum absorption efficiency α q and the internal quantum efficiency η i will be described.

A phosphor sample (for example, in powder form or the like) as an object of measurement is first filled in a test dish, the surface is made smooth enough to ensure measurement accuracy, and then it is mounted on a light-collecting device such as an integrating sphere. The light condensing means such as an integrating sphere is used in order to allow the total calculation of the light quanta reflected by the sample and the light quanta released by photoexcitation from the sample, that is, in order to eliminate the light quanta which fly outside the measurement system without calculation.

A light-emitting source for exciting a phosphor is attached to the integrating sphere or the like. The light emission source is, for example, a Xe lamp or the like, and the emission peak wavelength is adjusted to, for example, 455nm using a filter, a monochromator, or the like. The sample to be measured is irradiated with light from the light source adjusted to have a peak wavelength of 455nm, and the emission spectrum thereof is measured using a spectroscopic measuring apparatus (e.g., an MCPD2000 manufactured by Otsuka Denshi Co., ltd.). In this measurement spectrum, in addition to a light quantum emitted from the sample due to photoluminescence caused by light emitted from the excitation light source (hereinafter, simply referred to as excitation light), a contribution of the light quantum of the excitation light reflected by the sample is superimposed on the measurement spectrum.

The absorption efficiency α q is a value obtained by dividing the number Nabs of optical photons of excitation light absorbed by the sample by the number N of all optical photons of excitation light.

First, the total number of optical quanta N of the latter excitation light is calculated as follows. That is, a reflecting plate such as a substance having a reflectance R of substantially 100% with respect to excitation light, for example, "Spectralon" (having a reflectance of 98% with respect to excitation light of 450 nm) manufactured by Labsphere, is attached to the spectrophotometer as a measurement object, and the reflection spectrum Iref (λ) is measured. Here, a value obtained from the reflection spectrum Iref (λ) by the following (formula I) is proportional to N.

(formula I)

Here, the integration interval may be substantially performed only in an interval in which Iref (λ) has a significant value.

The photon number Nabs of the excitation light absorbed by the former sample is proportional to the amount obtained by the following (formula II).

(formula II)

Here, I (λ) is a reflection spectrum after the target sample for which the absorption efficiency α q is to be calculated is mounted. The integration range of (formula II) is the same as the integration range specified in (formula I). By thus defining the integration range, the second term of (formula II) corresponds to the number of light quanta generated by the reflection of the excitation light by the target sample, that is, to the number of light quanta other than the light quanta generated by photoluminescence caused by the excitation light among all the light quanta generated by the target sample. The actual spectral measurements are usually obtained in the form of digital data divided with some finite bandwidth related to λ, so the integrals of (formula I) and (formula II) can be calculated based on the finite sum of the bandwidths.

For the above reasons, α q = Nabs/N = (formula II)/(formula I).

Next, a method of calculating the internal quantum efficiency η i will be described. η i is the value obtained by dividing the number of photons NPL generated by photoluminescence by the number of photons Nabs absorbed by the sample.

Here, NPL is proportional to the amount obtained in the following (formula III).

Integral multiple of ^ I (lambda) d lambda (formula III)

In this case, the integration interval defines a wavelength region that the light quantum generated by the sample by photoluminescence has. This is to remove the effect of the light quanta reflected by the sample from I (λ). Specifically, the lower integral limit of (formula III) is taken at the upper end of the integral of (formula I), and the upper end is a range suitable for including a spectrum formed by photoluminescence.

For the above reasons, η i = (formula III)/(formula II) is obtained.

When integrating from the spectrum as numerical data, the same is true as in the case of calculating α q.

The product of the quantum absorption efficiency α q and the internal quantum efficiency η i obtained as described above is used to calculate the luminous efficiency defined in the present invention.

The phosphor used in the present invention can be synthesized by a general solid-phase reaction method. For example, the phosphor used in the present invention can be produced by pulverizing and mixing a raw material compound as a metal element source constituting the phosphor by the method of formula (i) or the wet method to prepare a pulverized mixture, and then subjecting the resultant pulverized mixture to a heat treatment to cause a reaction.

In the case where the phosphor used in the present invention is a nitride or oxynitride phosphor, for example, an alloy containing at least two or more metal elements constituting the phosphor, preferably an alloy containing all the metal elements constituting the phosphor, is prepared, and the obtained alloy is subjected to heat treatment under pressure in an atmosphere containing nitrogen, whereby the phosphor used in the present invention can be produced. The phosphor used in the present invention can be produced by, for example, preparing an alloy containing a part of the metal elements constituting the phosphor, subjecting the obtained alloy to a heat treatment under pressure in an atmosphere containing nitrogen, mixing the alloy with a raw material compound as a source of another metal element constituting the phosphor, and subjecting the mixture to a heat treatment. The phosphor produced from the alloy thus obtained has a low content of impurities and a high luminance.

[ II ] description about the second light-emitting device ]

The following describes in detail an embodiment of the second light-emitting device of the present invention, but the description of the constituent elements described below is an example (representative example) of the embodiment of the second light-emitting device of the present invention, and the present invention is not limited to these contents within the scope not exceeding the gist of the present invention.

The second light-emitting device of the present invention is a light-emitting device comprising a light source and at least one wavelength conversion material (usually a phosphor) which absorbs at least a part of light emitted from the light source and emits light having a wavelength different from that of the absorbed light, and the light-emitting device has an efficiency of 32lm/W or more, an average color rendering index Ra of 85 or more, and when the average color rendering index Ra is 17.5A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (A) is denoted as x ₁ (17.5) the chromaticity coordinate value y is denoted as y ₁ (17.5) and will be at 70A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (A) is denoted as x ₁ (70) And the chromaticity coordinate value y is recorded as y ₁ (70) When the chromaticity coordinate value x is different from the chromaticity coordinate value y [ x ] ₁ (17.5)-x ₁ (70)]And [ y ₁ (17.5)-y ₁ (70)]Satisfying the following formulae (F) and (G).

-0.01≤x ₁ (17.5)-x ₁ (70)≤0.01(F)

-0.01≤y ₁ (17.5)-y ₁ (70)≤0.01(G)

Here, the efficiency of the light-emitting device is the efficiency of the light-emitting device defined in jis z8113 "lighting terminology", and is a value obtained by dividing the total luminous flux emitted by a light source by the power consumption of the light source, and the unit thereof is "lm/W". In the present invention, the specific measurement method is based on JISZ8724 "method for measuring color — light source color".

Conventionally, a light-emitting device having a light-emitting efficiency of 30lm/W or less has been known, but in the case of a large power consumption for illumination applications and the like, a high light-emitting efficiency of the light-emitting device is desired in order to reduce a heat generation amount, and the inventors of the present invention have made intensive studies to realize a conventionally unavailable high-efficiency light-emitting device having a light-emitting efficiency of 32lm/W or more.

In the second light emitting device of the present invention, the average color rendering index Ra and the specific color rendering index R ₉ The measurement was performed based on JISZ8726 "color rendering evaluation method by light source". Color rendering index according toThe JISZ9112 "fluorescent lamp is classified into a general type and a high color rendering type according to the distinction of light source color and color rendering property". The second light-emitting device of the present invention has at least an average color rendering index Ra of 85 or more, and a specific color rendering index R when materials and structures of the light-emitting devices are selected ₉ In (3), the minimum value of the warm white color development AA is 64 or more, and even the required value 88 of the daylight color development AAA is satisfied.

The light source used in the second light emitting device of the present invention is not particularly limited as long as it emits light when a driving current is passed through it, and the same light source as that used in the first light emitting device may be used.

While a white light emitting device combining a GaN-based blue LED to which In is added and a Ce-activated yttrium aluminum garnet-based yellow phosphor has been widely used, it has a disadvantage of low color rendering properties as described above. In order to solve the problem, a light emitting device which emits a desired color by using a light source and at least one or more kinds of phosphors in combination as described in the following <1> to <3> has been proposed.

<1> a combination of an ultraviolet LED light-emitting device having a wavelength of 330nm to 420nm, a blue phosphor which is excited by the wavelength and emits fluorescence having a light-emitting peak at a wavelength of 420nm to 480nm, a green phosphor which emits fluorescence having a light-emitting peak at a wavelength of 500nm to 550nm, and a red phosphor having a light-emitting peak at a wavelength of 550nm to 700 nm. In the light emitting device for forming white light with the above configuration, when ultraviolet rays emitted from the LED are irradiated onto the phosphor, the phosphor emits red, green, and blue light, and these three light are mixed to obtain white light.

<2> a combination of a blue LED having a wavelength of 420 to 500nm and a yellow or red light-emitting phosphor which is excited by the wavelength and emits fluorescence having a light-emitting peak at a wavelength of 550 to 600 nm. In the light emitting device having the above configuration, when the blue light emitted from the LED is irradiated onto the phosphor, the phosphor emits red and yellow light, and these lights are mixed with the blue light of the LED itself to obtain white or reddish bulb light.

<3> a combination of a blue LED having a wavelength of 420 to 500nm, a green phosphor which is excited by the wavelength and emits fluorescence having a peak at a wavelength of 500 to 550nm, and a red light-emitting phosphor which emits fluorescence having a peak at a wavelength of 610 to 680 nm. In the light emitting device for forming white light with this configuration, the phosphor emits red and green light when the blue light emitted from the LED is irradiated on the phosphor, and these lights are mixed with the blue light of the LED itself to obtain white light.

In the second light-emitting device of the present invention, the above-described light-emitting element can be used<1>～<3>Either of them, and in either case, the second light-emitting device of the present invention is characterized in that when it is to be set at 17.5A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (2) is denoted as x ₁ (17.5) the chromaticity coordinate value y is denoted as y ₁ (17.5), and will be at 70A/cm ² The chromaticity coordinate value x of the emitted light obtained from the drive current density of (A) is denoted as x ₁ (70) And the chromaticity coordinate value y is recorded as y ₁ (70) When the above-mentioned compounds satisfy the following formulae (F) and (G).

-0.01≤x ₁ (17.5)-x ₁ (70)≤0.01(F)

-0.01≤y ₁ (17.5)-y ₁ (70)≤0.01(G)

That is, to 70A/cm ² The chromaticity coordinate value x and the chromaticity coordinate value y of the emitted light obtained at the drive current density of (2) are respectively relative to 17.5A/cm ² The difference [ x ] between chromaticity coordinate values corresponding to the shift amount between chromaticity coordinate value x and chromaticity coordinate value y of emitted light obtained at the driving current density of [ 1 ] ₁ (17.5)-x ₁ (70)]And [ y ₁ (17.5)-y ₁ (70)]Within + -0.01. In the case where the shift amount of the chromaticity coordinate value of the light emission accompanying the change of the driving current density is larger than ± 0.01, when the driving current density is changed in order to control the light emission amount, the color difference becomes large and the light emission color becomes unstable.

The smaller the shift amount of the chromaticity coordinate value x and the shift amount of the chromaticity coordinate value y, the more preferable.

I.e. the offset [ x ] ₁ (17.5)-x ₁ (70)]Usually-0.005 or more, preferably-0.004 or more, more preferably-0.003 or more, and usually 0.005 or less, preferably 0.004 or less, more preferably 0.003 or less. In addition, offset amount [ y ₁ (17.5)-y ₁ (70)]And is also usually at least-0.005,preferably-0.004 or more, more preferably-0.003 or more, and usually 0.005 or less, preferably 0.004 or less, more preferably 0.003 or less.

The wavelength conversion material such as a phosphor used for realizing the second light-emitting device of the present invention is not particularly limited. However, the phosphor mixture according to the present invention described in the first light-emitting device is preferably used.

That is, in the second light-emitting device of the present invention, it is preferable that a mixture of two or more kinds of phosphors is used as the wavelength conversion material, and the luminance of fluorescence obtained by exciting the phosphor mixture at 25 ℃ with blue light having a peak wavelength of 455nm is represented by BR (25) and the chromaticity coordinate value x is represented by x ₂ (25) And the chromaticity coordinate value y is recorded as y ₂ (25) The luminance of fluorescence obtained by excitation with blue light having a peak wavelength of 455nm at 125 ℃ is represented by BR (125), and the chromaticity coordinate value x is represented by x ₂ (125) And the chromaticity coordinate value y is recorded as y ₂ (125) When the above-mentioned compounds satisfy the following formulae (A), (B) and (C).

0.85≤BR(125)/BR(25)≤1.15(A)

-0.03≤x ₂ (25)-x ₂ (125)≤0.03(B)

-0.03≤y ₂ (25)-y ₂ (125)≤0.03(C)

In the case where the ratio [ BR (125)/BR (25) ] of the luminance of fluorescence [ BR (125) ] obtained by excitation with blue light having a peak wavelength of 455nm at 125 ℃ to the luminance [ BR (25) ] of fluorescence obtained by excitation with the blue light at 25 ℃ is less than 0.85 or more than 1.15, a white light-emitting device or the like using such a phosphor mixture may not obtain a stable emission color because the change in the emission color obtained when the current value flowing through the blue LED is increased or decreased to change the amount of light obtained from the device.

This is because, in this case, when the amount of current flowing through the blue LED is increased or decreased to increase or decrease the amount of light of the blue light, the temperature of the fluorescent material provided in the vicinity of the blue LED fluctuates in accordance with the increase or decrease in the amount of heat generated by the blue LED, and the intensity of fluorescence emitted from the fluorescent material greatly deviates from the intensity of fluorescence expected from the amount of light of the blue LED. That is, when the amount of current supplied to the blue LED is increased or decreased in order to increase or decrease the light amount of the white light emitting device, the color mixture balance between the emission intensity of the blue LED and the fluorescence intensity of the fluorescent material emitted from the fluorescent material is lost, and the emission color of the white light emitting device to be obtained is largely changed.

Therefore, the ratio of the luminance [ BR (125)/BR (25) ] is usually 0.85 or more, preferably 0.9 or more, and is usually 1.15 or less, preferably 1.1 or less, more preferably 1.05 or less. In order to obtain such a ratio of luminance, it is preferable that the phosphor constituting the phosphor mixture is selected from phosphors having a small degree of temperature quenching phenomenon, which is a phenomenon in which the fluorescence intensity decreases as the temperature of the phosphor increases.

Further, the phosphor mixture according to the present invention is characterized in that x represents a chromaticity coordinate value x of fluorescence obtained by excitation with blue light having a peak wavelength of 455nm at 25 ℃ ₂ (25) And the chromaticity coordinate value y is recorded as y ₂ (25) And the chromaticity coordinate value x of the fluorescence obtained by excitation with the same blue light at 125 ℃ is denoted as x ₂ (125) And the chromaticity coordinate value y is recorded as y ₂ (125) The difference [ x ] of chromaticity coordinate values x ₂ (25)-x ₂ (125)]Difference [ y ] from chromaticity coordinate value y ₂ (25)-y ₂ (125)]In the case of less than-0.03 or more than 0.03, there is a possibility that a significant color difference occurs as the amount of light of the white light emitting device using the phosphor mixture increases and decreases.

The difference [ x ] of the chromaticity coordinate value x ₂ (25)-x ₂ (125)]Difference [ y ] of the chromaticity coordinate value y ₂ (25)-y ₂ (125)]This is caused by a large difference in the degree of temperature quenching between two or more phosphors contained in the phosphor mixture. That is, in a mixture containing two or more phosphors having different emission colors, when the degree of temperature quenching of the phosphors is different, for example, when the decrease in fluorescence intensity of one phosphor with an increase in temperature is small and the decrease in fluorescence intensity of the other phosphor with an increase in temperature is large, and when these different emission intensities are added, the emission color changes with an increase in temperature, and color difference occurs.

Therefore, the difference [ x ] of chromaticity coordinate value x caused by the temperature change of the phosphor mixture ₂ (25)-x ₂ (125)]Difference [ y ] from chromaticity coordinate value y ₂ (25)-y ₂ (125)]The smaller the average is, the more preferable the difference is usually-0.03 or more, preferably-0.02 or more, more preferably-0.015 or more, and usually 0.03 or less, preferably 0.02 or less, more preferably 0.015 or less.

In order to obtain a phosphor mixture having a small difference in chromaticity coordinate value x and a small difference in coordinate value y due to such a temperature change, it is preferable that the rates of change in fluorescence intensity due to such temperature extinction of a plurality of phosphors constituting a mixture having different fluorescence colors are substantially uniform. When phosphors having substantially equal rates of change in fluorescence intensity due to temperature quenching are combined, the mixed color such as white obtained by adding the fluorescence intensities of the phosphors is substantially the same, and fluctuation in emission color due to temperature variation with light amount variation of the light-emitting device can be reduced regardless of temperature variation.

In the description of the second light-emitting device of the present invention, when the luminance, chromaticity coordinate value x, and chromaticity coordinate value y obtained by exciting the phosphor mixture with blue light having a peak wavelength of 455nm are measured, for example, a fluorescence spectrophotometer is used which has a cooling mechanism using a peltier element and a heating mechanism using a heating element, and is equipped with a high-precision double monochromator subjected to sensitivity correction and/or wavelength correction. In this way, the cooling-heating mechanism is controlled to hold the surface temperature of the phosphor at 25 ℃ or 125 ℃ for a sufficient time in advance until the radiation thermometer can confirm that the surface temperature is constant, and then the luminance and chromaticity coordinate values are measured. In order to minimize the influence of blue light as excitation light, the half-peak width of the excitation light is reduced to 20nm or less, and the luminance Y, chromaticity coordinate value x, and chromaticity coordinate value Y are calculated using the tristimulus values specified in JIS Z8724, using only the fluorescence spectrum of 470nm or more, and not using the fluorescence spectrum of less than 470 nm.

[ Green phosphor ]

As the green phosphor having a peak of fluorescence intensity in a wavelength range of 500nm to 550nm, which at least one kind of green phosphor that can be contained in the wavelength conversion material according to the second light-emitting device of the present invention can be used the green phosphor used in the first light-emitting device of the present invention described above.

[ Red-based phosphor ]

In the second light-emitting device of the present invention, in order to obtain a light-emitting device having particularly high color rendering properties even in a light-emitting device having little color difference, it is preferable that the wavelength conversion material such as a phosphor mixture used in the light-emitting device contains at least one red phosphor having a peak of fluorescence intensity in a wavelength range of 610nm to 680 nm. By using a red phosphor having a peak of fluorescence intensity in such a wavelength range, a light-emitting device having high color reproducibility in a red color region such as orange, red, and deep red can be obtained, and by using the light-emitting device, a backlight for a display, an image display device (display), or an illumination device having excellent color reproducibility in the red color region can be obtained. When the peak of the fluorescence intensity of the red phosphor is less than 610nm, the color reproducibility in the red color range is lowered when used in combination with a blue LED, and when the peak of the fluorescence intensity of the red phosphor is more than 680nm, the color rendering property is increased, but the luminance tends to be lowered.

The red-based phosphor having a peak of fluorescence intensity in a wavelength range of 610nm to 680nm, which at least one of the red-based phosphors that may be contained in the wavelength conversion material according to the present invention, may be the red-based phosphor used in the first light-emitting device according to the present invention.

[ luminous efficiency of phosphor ]

The emission efficiency of the phosphor constituting the wavelength conversion material such as the phosphor mixture according to the present invention is the same as that of the phosphor used in the first light-emitting device according to the present invention.

[ embodiment ]

The second light-emitting device of the present invention is configured using, for example, a phosphor mixture containing at least two kinds of phosphors as a wavelength conversion material and a semiconductor light-emitting device (for example, a semiconductor light-emitting device such as an LED or an LD) that emits visible light, and realizes a light-emitting device that absorbs visible light emitted by the semiconductor light-emitting device and emits visible light of a longer wavelength, and that has high luminance, high color rendering properties, and little color difference with increase and decrease in light amount. Therefore, the second light-emitting device of the present invention having such characteristics is suitable as a light source of a backlight for a display such as a color liquid crystal display or an illumination device such as surface light emission.

The embodiment of the second light-emitting device of the present invention will be described in more detail with reference to the drawings, but the second light-emitting device of the present invention is not limited to the embodiment described below, and can be implemented by any change without departing from the gist of the present invention.

(1) First embodiment

Fig. 3 is a diagram schematically illustrating essential parts of a light-emitting device as a first embodiment of a second light-emitting device according to the present invention.

The light emitting device 101 of the present embodiment is mainly configured by a frame 102, a blue LED (blue light emitting part) 103 as a light source, and a fluorescent light emitting part 104 that absorbs a part of light emitted from the blue LED103 and emits light having a wavelength different from that of the absorbed light.

The frame 102 is a resin base portion for holding the blue LED103 and the luminescent light emitting portion 104. A recess (groove) 102A having a trapezoidal cross section and opening upward in the drawing is formed on the upper surface of the frame 102. Thus, the frame 102 is formed in a cup shape, so that the light emitted from the light-emitting device 101 can have directivity, and the emitted light can be effectively utilized.

Further, since the inner surface of the concave portion 102A of the frame 102 is plated with a metal such as silver to increase the reflectance thereof with respect to all light in the visible light range, light incident on the inner surface of the concave portion 102A of the frame 102 can be emitted in a predetermined direction from the light emitting device 101.

A blue LED103 as a light source is provided at the bottom of the recess 102A of the frame 102. The blue LED103 emits blue light by supplying power. A part of the blue light emitted from the blue LED103 is absorbed as excitation light by a light-emitting substance (wavelength conversion material; here, a fluorescent substance) in the luminescent light-emitting portion 104, and the other part is emitted in a predetermined direction from the light-emitting device 101.

As described above, the blue LED103 is provided on the bottom of the recess 102A of the frame 102, and here, the frame 102 and the blue LED103 are bonded by the silver paste (substance in which silver particles are mixed in the binder) 105, whereby the blue LED103 is provided on the frame 102. In addition, the silver paste 105 also functions to efficiently dissipate heat generated by the blue LED103 to the frame 102.

A gold bonding wire 106 for supplying power to the blue LED103 is attached to the frame 102, and the blue LED103 is connected to an electrode (not shown) provided on the upper surface of the blue LED103 by the bonding wire 106 by a wire bonding method. The connection line 106 is energized, so that the blue LED103 is energized, and the blue LED103 emits blue light. In addition, one or several connection lines 106 are mounted in conjunction with the structure of the blue LED 103.

The concave portion 102A of the frame 102 is provided with a fluorescent light-emitting portion 104 that absorbs a part of light emitted from the blue LED103 and emits light having a wavelength different from that of the absorbed light. The luminescent light emitting section 104 is formed of a phosphor and a transparent resin. The phosphor is a substance (wavelength conversion material) that is excited by blue light emitted from the blue LED103 and emits light having a longer wavelength than the blue light. The phosphor constituting the fluorescent light-emitting portion 104 may be one kind or a mixture of several kinds of phosphors, and may be selected so that the sum of the light emitted from the blue LED103 and the light emitted from the fluorescent light-emitting portion 104 attains a desired color, but in the second light-emitting device of the present invention, a phosphor mixture satisfying the above-described formulae (a) to (C) is preferably used. The color may be not only white but also yellow, orange, pink, purple, cyan, and the like. Further, an intermediate color between these colors and white may be used. The transparent resin is an adhesive for the luminescent light emitting part 104, and here, an epoxy resin, which is a synthetic resin that can transmit in the entire visible light range, is used.

The mold 108 protects the blue LED103, the fluorescent light emitting portion 104, the connecting wire 106, and the like from the outside, and has a function of a lens for controlling light distribution characteristics. The molding portion 108 mainly uses a resin such as an epoxy resin.

(2) Second embodiment

Fig. 4 is a diagram schematically illustrating essential parts of a light-emitting device as a second embodiment of a second light-emitting device according to the present invention.

The light emitting device 110 of the present embodiment is mainly configured by a frame 112, a blue LED (blue light emitting part) 113 as a light source, and a fluorescent light emitting part 114 that absorbs a part of light emitted from the blue LED113 and emits light having a wavelength different from that of the absorbed light.

The frame 112 is a resin base portion for holding the blue LED113 and the fluorescent light emitting portion 114. A recess (groove) 112A having a trapezoidal cross section and opened in the upper side in the drawing is formed on the upper surface of the frame 112. Thus, the frame 112 is formed into a cup shape, so that the light emitted from the light emitting device 110 can have directivity, and the emitted light can be effectively utilized.

Further, an electrode, not shown, for supplying power from the outside of the light emitting device 110 to the electrode is provided on the bottom of the recess 112A, and power can be supplied from the electrode to the blue LED 113.

The inner surface of the recess 112A of the frame 112 is formed of a material having a high reflectance with respect to all light in the visible light range. Thus, light applied to the inner surface of concave portion 112A of frame 112 can be emitted in a predetermined direction from light emitting device 110. The electrodes are plated with a metal, and the metal plated has a high reflectance to all visible light.

The bottom of the recess 112A of the frame 112 is provided with a blue LED113 as a light source. The blue LED113 is an LED that emits blue light by power supply. A part of the blue light emitted from the blue LED113 is absorbed as excitation light by a light-emitting substance (here, a fluorescent substance) in the fluorescent light-emitting portion 114, and the other part is emitted in a predetermined direction from the light-emitting device 110.

The blue LED113 provided at the bottom of the recess 112A of the frame 112 is bonded to the frame 112 with a silver paste (a substance in which silver particles are mixed in a binder) 115, and the blue LED113 is thereby provided to the frame 112. In addition, the silver paste 115 also functions to efficiently dissipate heat generated from the blue LED113 to the bezel 112.

Gold connection wires 116 for supplying power to the blue LEDs 113 are attached to the frame 112, and the blue LEDs 113 are connected to electrodes (not shown) provided at the bottom of the recess 112A of the frame 112 by the connection wires 116 by a wire bonding method. The connection line 116 is energized, so that the blue LED113 is energized, and the blue LED113 emits blue light. In addition, one or several connection lines 116 are mounted in conjunction with the structure of the blue LED113.

The concave portion 112A of the frame 112 is provided with a fluorescent light emitting portion 114 that absorbs a part of the light emitted from the blue LED113 and emits light having a wavelength different from that of the absorbed light. The luminescent light emitting section 114 is formed of a phosphor and a transparent resin. The phosphor is a substance (wavelength conversion material) that is excited by the blue light emitted from the blue LED113 and emits light having a longer wavelength than the blue light. The phosphor constituting the fluorescent light-emitting portion 114 may be one kind or a mixture of several kinds of phosphors, and may be selected so that the sum of the light emitted from the blue LED113 and the light emitted from the fluorescent light-emitting portion 114 can achieve a desired color, but in the second light-emitting device of the present invention, a phosphor mixture satisfying the above-described formulas (a) to (C) is preferably used. The color may be not only white but also yellow, orange, pink, purple, cyan, and the like. Further, an intermediate color between these colors and white may be used. In addition, the transparent resin is a binder of the fluorescent light emitting section 114, and here, an epoxy resin or a silicone resin, which is a synthetic resin capable of transmitting in the entire visible light range, is used.

Fig. 5 shows a surface-emitting illumination device 109 to which the light-emitting device 101 shown in fig. 3 is attached, and as shown in fig. 5, a large number of light-emitting devices 101 are provided on the bottom surface of a square support case 109A having a light-tight inner surface such as a white smooth surface, and a power supply, a circuit, and the like (not shown) for driving the light-emitting devices 101 are provided on the outer side thereof, and a diffusion plate 109B such as a white acrylic plate is fixed at a position corresponding to the lid portion of the support case 109A to make the light emission uniform.

When the surface-emission lighting device 109 is driven to emit blue light or the like by applying a voltage to the blue LED103 of the light emitting device 101, the phosphor mixture as a wavelength conversion material in the luminescent light emitting section 104 absorbs a part of the light emission and emits light of a longer wavelength, and on the other hand, the light of the longer wavelength is mixed with blue light or the like not absorbed by the phosphor to obtain light emission with high color rendering property, and the light is transmitted through the diffusion plate 109B and emitted above the drawing surface, thereby obtaining uniform and bright illumination light in the diffusion plate 109B surface of the support case 109A.

Similarly, the second light-emitting device of the present invention can be mounted as a backlight as a light source of a display such as a color liquid crystal display.

[ III ] description about a white light emitting device ]

The white light emitting device of the present invention is not limited to the following embodiments, and may be arbitrarily changed in practice within a range not departing from the gist of the present invention.

The white light emitting device (white light emitting element) of the present embodiment has a light source (light emitting element or the like) that generates light (hereinafter referred to as "primary light" for convenience), at least one wavelength conversion material that absorbs at least a part of the light emitted from the light source and emits light of a wavelength different from that of the primary light (hereinafter referred to as "secondary light" for convenience), and emits white light including the secondary light emitted from the wavelength conversion material. Here, the white light may be obtained as combined light such as combined light of primary light and secondary light, combined light of two or more types of secondary light, or the like.

In the white light emitting device of the present embodiment, the maximum emission intensity of the white light in the wavelength range of 500nm to 650nm (hereinafter, this wavelength range is referred to as "predetermined wavelength range" for convenience) is 150% or less of the minimum emission intensity in the predetermined wavelength range.

[ III-1. White light ]

[ III-1-1. Aspect of flatness of luminescence spectrum ]

White light emitting devices are mainly used for illumination, and it is desired that colors of an object can be faithfully reproduced (i.e., white light emitted has high color rendering properties). To achieve this, it is preferable that the white light emitting device emits white light containing all visible light components included in natural light. In particular, a predetermined wavelength range of 500nm to 650nm in the emission spectrum is a wavelength range in which visibility is high and which contains a main light component from blue-green to red, and the flatness of the emission spectrum, which is a visible light component uniformly contained in this wavelength range, is associated with good color rendering properties.

In particular, white lighting with daylight color around a correlated color temperature of 5000K and daylight color around a correlated color temperature of 6500K are lighting hues that account for most of white lighting used at home and abroad, and the emission spectrum of a full radiator at these correlated color temperatures is substantially flat in the above-mentioned prescribed wavelength range. Therefore, it is also preferable that the white light emitted from the white light emitting device of the present embodiment has a flat spectrum in the predetermined wavelength range as described above when the white light emitting device is used as an illumination device.

Further, the visibility of light having a wavelength range of more than 650nm is particularly low, and the efficiency of the entire white light emitting device may be lowered when light having such a wavelength range is generated. Therefore, the white light emitted by the white light emitting device of the present embodiment preferably has a small emission intensity of light components in a wavelength range having a wavelength longer than 650nm, that is, a wavelength range having a wavelength longer than a value in a predetermined wavelength range.

On the other hand, light in a wavelength range of less than 500nm is preferably flat, as in the case of light in a predetermined wavelength range. However, a primary light source such as a light emitting element available at present generally has a small emission half-value width. Therefore, in the wavelength range of less than 500nm, the white light emitted by the white light emitting device of the present embodiment has to be in a state where the intensity of light at a specific wavelength is low and the amount of light in the wavelength range close to the specific wavelength is small. However, since the visibility of light in the blue to violet region having a wavelength of less than 500nm is low as in the case of light having a wavelength of more than 650nm, the characteristics such as color rendering properties do not significantly deteriorate even if the emission spectrum of the light component in the wavelength region having a wavelength of less than 500nm, that is, in the wavelength region having a wavelength of less than a predetermined wavelength range is uneven.

The degree of flatness of the emission spectrum in the above-described predetermined wavelength range can be represented by an index I (ratio) obtained as follows.

The minimum luminescence intensity I (min) and the maximum luminescence intensity I (max) of the luminescence spectrum in the specified wavelength range are determined, the ratio of which in percent is I (ratio). The I (ratio) can be calculated by the following formula (I).

I(ratio)＝{I(max)/I(min)}×100(i)

I (ratio) is a value of 100% or more by definition, and in the white light emitted from the white light emitting device of the present embodiment, I (ratio) is usually 150% or less, preferably 140% or less, more preferably 135% or less, and further preferably 130% or less. That is, the maximum emission intensity of the emission spectrum of the white light in the predetermined wavelength range may be set to be within the above range with respect to the minimum emission intensity. The closer to 100% the I (ratio), the flatter the emission spectrum, and therefore, the smaller the I (ratio), the more preferable.

[ III-1-2. Correlated color temperature of white light ]

The correlated color temperature of the white light emitted by the white light emitting device of the present embodiment may be any value as long as the effect of the present invention is not significantly affected, but is preferably a light emission color based on the daytime white color (symbol N) or the daytime light color (symbol D) in JIS standard (Z9112) regarding the light source color of conventional fluorescent lamps. The correlated color temperature of the daylight color is 4600K to 5400K, and the correlated color temperature of the daylight color is 5700K to 7100K. The range of correlated color temperature is more preferably 4800K to 5200K in daytime white and 6000K to 6800K in daylight color, and more preferably daylight white is as close to 5000K and daylight color is as close to 6500K as possible. The correlated color temperature is determined based on JIS Z8725, and it is preferable to adjust the emission color so that the distance from the black body radiation locus is small.

[ III-1-3. Color of white light ]

The color of the white light emitted by the white light emitting device of the present embodiment can be arbitrarily set according to the use and the like. In the specification, white refers to white defined in color classification according to JIS Z8110. The color of the white light can be measured by a colorimeter, a radiance meter, or the like.

In the relation to the CIE chromaticity diagram, the color of the white light may be based on the general white light having the CIE chromaticity coordinate (x, y) of (0.33), and may be, for example, a color in an area surrounded by color coordinates (x, y) of (0.28,0.25), (0.25,0.28), (0.34,0.40), and (0.40,0.34).

[ III-1-4. Luminous efficiency of white light ]

In the white light emitting device of the present embodiment, the emission efficiency of white light is usually 20lm/W or more, preferably 30lm/W or more, and more preferably 40lm/W or more. Although the necessary brightness can be obtained by using a large number of elements smaller than the lower limit of the range, this consumes a large amount of energy and is not preferable. The luminous efficiency of the white light emitting device can be measured by dividing the luminous flux of white light measured by, for example, an integrating sphere by the power supply.

[ III-1-5. Color rendering of white light ]

The white light emitting device of the present embodiment can improve the color rendering of white light. Although there is no particular limitation on the specific value, the color rendering index R is defined in JIS-Z8726 ₁ ～R ₈ The average value Ra of (a) is usually 80 or more, preferably 85 or more, and more preferably 90 or more.

[ III-2. Constitution ]

Fig. 6 is a schematic cross-sectional view of the white light emitting device of the present embodiment, showing the structure of the light emitting device. The white light emitting device shown in fig. 6 is an example of the white light emitting device of the present invention, and the white light emitting device of the present invention is not limited to the following embodiments.

As shown in fig. 6, the white light emitting device 201 of the present embodiment includes a light emitting element 202 as a light source that emits primary light, and at least one kind of wavelength conversion material 203, 204 that absorbs the primary light and emits secondary light. In addition, in general, the white light emitting device 201 has a frame 205 as a base for holding the light emitting element 202 and the wavelength converting materials 203, 204.

The white light emitting device 201 of the present embodiment emits white light having a flat emission spectrum in a predetermined wavelength range, and has a correlated color temperature, a color, an intensity, and a light emission efficiency in the above ranges.

[ III-2-1. Frame ]

The frame 205 is a base portion for holding the light emitting element 202 and the wavelength conversion materials 203 and 204, and may have any shape, material, or the like.

As a specific example of the shape of the frame 205, a plate shape, a cup shape, or the like may be appropriately formed according to the use. In the illustrated shape, the cup-shaped frame is preferable because the emission direction of white light can be made directional and light emitted from the white light emitting device can be effectively used.

Specific examples of the material of the frame 205 include inorganic materials such as metals, alloys, glasses, and carbon; and organic materials such as synthetic resins.

However, it is preferable to increase the reflectance of the frame 205 to which light (for example, primary light and/or secondary light) emitted from the light emitting element 202 and/or the wavelength conversion materials 203, 204 is irradiated, with respect to the irradiated light, and it is more preferable to increase the reflectance thereof with respect to light in the entire visible region. Therefore, at least the surface to which light is irradiated is preferably formed of a material having a high reflectance. Specific examples thereof include forming the entire frame 205 or the surface of the frame 205 with a material (injection molding resin or the like) containing a substance having a high reflectance such as glass fiber, alumina powder, titanium oxide powder, or the like.

The specific method of increasing the reflectance of the surface of the frame 205 is arbitrary, and the reflectance of light may be increased by plating or vapor deposition treatment with a metal or alloy having a high reflectance such as silver, platinum, or aluminum, in addition to the above-described selection of the material of the frame 205 itself.

The portion for increasing the reflectance may be the entire frame 205 or a part thereof, and it is generally preferable to increase the reflectance of the entire surface of the portion to which light emitted from the light emitting element 202 and/or the wavelength conversion materials 203 and 204 is irradiated.

In addition, an electrode, a terminal, and the like for supplying power to the light-emitting element 202 are usually provided in the frame 205.

In the present embodiment, conductive terminals 206 and 207 for supplying power to the light emitting element 202 are formed at the bottom of the recess 205A of the cup-shaped frame 205, and the conductive terminals 206 and 207 are connected to an external power supply (not shown).

[ III-2-2. Light-emitting element ]

The light emitting element 202 emits primary light as excitation light of the wavelength conversion materials 203 and 204, and functions as a light source. In addition, a part of the primary light also serves as a component of the white light emitted by the white light emitting device 201, and in this case, a synthesized light obtained by synthesizing the primary light and the secondary light is emitted from the white light emitting device 201 as white light. That is, a part of the primary light emitted from the light emitting element 202 is absorbed by the wavelength converting materials 203, 204 as excitation light, and the other part is emitted from the white light emitting device 201. It should be noted that the white light does not necessarily include the primary light, and for example, the white light emitting device 201 of the present embodiment may emit the white light in the form of a composite light of two or more secondary lights.

The type of the light emitting element 202 is arbitrary, and an appropriate type can be selected according to the use or the configuration of the white light emitting device 201. Examples of the light-emitting element 202 include a light-emitting diode (i.e., LED), an end-face emission type or surface-emission type laser diode (i.e., LD), and an electroluminescence element. Among them, low-priced LEDs are generally preferred.

The emission wavelength of the primary light emitted by the light emitting element 202 is also arbitrary, and a light emitting element that emits a primary light of an appropriate emission wavelength can be used in accordance with the white light emitted by the white light emitting device 201. In general, a light-emitting element which emits near ultraviolet to blue light as primary light is preferably used. Specific wavelength ranges of the primary light are usually 370nm or more, preferably 380nm or more, and usually 500nm or less, preferably 480nm or less. When the wavelength of the primary light is longer than the upper limit of the range, it is difficult to obtain a light-emitting device having high emission efficiency, and when the primary light is light having an emission wavelength of 480nm or more, which is longer than the wavelength of blue-green light, it is extremely difficult to efficiently convert the primary light into blue light, so that there is a possibility that a light-emitting device containing no blue light is formed, and a white light-emitting device cannot be obtained. Further, when the wavelength of the primary light is less than the lower limit, it is extremely difficult to obtain a light-emitting device having high emission efficiency.

Specific examples of the light-emitting element 202 include an LED using an InGaN-based, gaAlN-based, inGaAlN-based, znSeS-based semiconductor or the like which is crystal-grown on a substrate of silicon carbide, sapphire, gallium nitride or the like by a method such as MOCVD or the like. Among them, an LED containing (In, ga) N as a main component is preferably used.

One light-emitting element 202 may be used alone, or two or more light-emitting elements 202 may be used in combination. In addition, only one kind of light-emitting element 202 may be used, or two or more kinds may be used in combination.

When the light emitting element 202 is mounted on the frame 205, a specific method is arbitrary, and for example, mounting using solder is possible. The type of solder is arbitrary, and AuSn, agSn, or the like can be used, for example. In addition, when solder is used, it is also possible to realize that power can be supplied from the electrodes formed in the frame 205, the terminals 206, 207, and the like through the solder. In particular, when a large-current LED or a laser diode, which is important in heat dissipation, is used as the light emitting element 202, the solder exhibits excellent heat dissipation, and therefore, it is effective to provide the light emitting element 202 with the solder.

When the light emitting element 202 is mounted on the frame 205 by means other than solder, for example, an adhesive such as epoxy resin, imide resin, or acrylic resin can be used. In this case, by using a paste-like substance obtained by mixing a conductive filler such as silver particles or carbon particles with a binder, it is possible to supply power to the light-emitting element 202 by applying current to the binder, as in the case of using solder. Further, mixing these conductive fillers is preferable because heat dissipation can be improved.

Further, a method of supplying power to the light emitting element 202 is also arbitrary, and power supply may be performed by connecting the light emitting element 202 and the electrodes or terminals 206 and 207 by a wire connection method in addition to the above-described energization of the solder or the adhesive. The connecting wire used here is not limited, and the material, size, and the like thereof are arbitrary. For example, as a material of the connection line, a metal such as gold or aluminum may be used, and the thickness thereof is usually set to 20 μm to 40 μm, but the connection line is not limited thereto.

As another method of supplying power to the light-emitting element, power is supplied to the light-emitting element 202 by flip chip (flip chip) mounting using bumps (bump).

In this embodiment, an LED is used as the light emitting element 202, and the light emitting element 202 is provided at the bottom of the recess 205A of the frame 205. The light emitting element 202 is directly connected to the conductive terminal 206, and is connected to the conductive terminal 207 via a connection line 208 by a wire connection method, whereby power supply is realized.

However, a light source other than the light emitting element described above may be used.

[ III-2-3. Wavelength converting Material ]

The wavelength converting materials 203, 204 absorb at least a portion of the primary light emitted by the light emitting element 202 and in turn emit secondary light of a different wavelength than the absorbed primary light. Accordingly, by appropriately selecting the wavelength conversion materials 203 and 204, white light can be obtained as combined light of the primary light and the secondary light or combined light of two or more types of secondary light.

As the wavelength conversion materials 203, 204, known wavelength conversion materials can be appropriately selected and used according to the use of the white light emitting device 201 without significantly impairing the effects of the present invention. The light emission of the wavelength conversion materials 203 and 204 is not limited, and light emission can be performed by any mechanism such as fluorescence or phosphorescence. It is to be noted that, within a range not exceeding the gist of the present invention, one kind of wavelength conversion material 203, 204 may be used alone, but from the viewpoint of reducing I (ratio) as described above, it is preferable to use two or more kinds of wavelength conversion materials 203, 204 having different emission wavelengths. Further, when two or more wavelength converting materials 203, 204 are used, the combination and ratio thereof are arbitrary.

The wavelength conversion materials 203 and 204 are not limited in the wavelength of light (typically, primary light) absorbed as excitation light or the wavelength of light (i.e., secondary light) emitted therefrom, and may be any wavelength without significantly impairing the effects of the present invention. Preferred wavelength ranges for these lights are as follows: the wavelength range of the excitation light of the wavelength conversion materials 203, 204 is generally 350nm or more, preferably 400nm or more, more preferably 430nm or more, and is generally 600nm or less, preferably 570nm or less, more preferably 550nm or less. On the other hand, the wavelength of light emitted from the wavelength converting material is usually 400nm or more, preferably 450nm or more, more preferably 500nm or more, and is usually 750nm or less, preferably 700nm or less, more preferably 670nm or less.

When two kinds of wavelength conversion materials 203 and 204 are used, it is preferable to use the first wavelength conversion material and the second wavelength conversion material which satisfy the following characteristics in combination.

The first wavelength conversion material is preferably a wavelength conversion material that absorbs light having a wavelength of usually 350nm or more, preferably 400nm or more, more preferably 430nm or more, and usually 520nm or less, preferably 500nm or less, more preferably 480nm or less as excitation light.

The first wavelength conversion material preferably emits light having a wavelength of usually 400nm or more, preferably 450nm or more, more preferably 500nm or more, and usually 600nm or less, preferably 570nm or less, more preferably 550nm or less.

On the other hand, the second wavelength conversion material is preferably a wavelength conversion material that absorbs light having a wavelength of usually 400nm or more, preferably 450nm or more, more preferably 500nm or more, and usually 600nm or less, preferably 570nm or less, more preferably 550nm or less as excitation light.

The second wavelength conversion material preferably emits light having a wavelength of usually 550nm or more, preferably 580nm or more, more preferably 600nm or more, and usually 750nm or less, preferably 700nm or less, more preferably 670nm or less.

By using a wavelength conversion material that absorbs excitation light in the above wavelength range and emits light in the above wavelength range, a light-emitting device that emits light in the entire visible light range, in particular, a light-emitting device that can emit light in the entire wavelength range of 500nm to 650nm, can be obtained. In addition, when the wavelength conversion material is one, it is also allowable as long as the gist of the present invention can be satisfied.

In addition, when the white light emitting device 201 of the present embodiment is configured, by using an appropriate material for the wavelength conversion materials 203 and 204, the white light emitting device 201 having more excellent characteristics can be obtained. Examples of the properties that the wavelength conversion materials 203 and 204 should have include a small change in emission intensity due to an increase in temperature, a high internal quantum efficiency, and a large absorbance.

Little change in emission intensity due to temperature rise

The wavelength conversion materials 203 and 204 preferably have a small change in emission intensity due to a temperature increase. That is, it is preferable that the temperature dependence of the emission intensity is small. When a substance having a large temperature dependence is used as the wavelength conversion materials 203 and 204, the intensity of the secondary light changes under different temperature conditions, the balance between the intensities of the primary light and the secondary light changes, and the color tone of the white light may change. As a specific example thereof, a device that generates heat with light emission such as an LED is used as the light emitting element 202, and in this case, when the light emission is continued, the temperature of the white light emitting device 201 increases with time due to the heat generation of the light emitting element 202, and at the same time, the intensity of the secondary light emitted from the wavelength converting materials 203, 204 changes, and the color tone of the white light may change immediately after the light emission and when the light emission is continued. However, by using the wavelength converting materials 203, 204 having small temperature dependency, the above-described change in color tone can be suppressed.

The change in the light emission intensity due to the temperature rise can be represented by the ratio TR (%) of the luminance at 100 ℃ to the luminance at 25 ℃ (hereinafter referred to as "luminance maintenance ratio" for convenience). Specifically, the luminance maintenance ratio TR is usually 80% or more, preferably 90% or more, and more preferably 95% or more.

In addition, TR can be measured as follows.

First, using a temperature characteristic evaluation apparatus for ocean electron production, about 100mg of a measurement sample powder (wavelength conversion material) was filled in a powder container (ホルダ one) having a diameter of 8mm, and then placed in the apparatus. Thereafter, the luminance in the state of irradiation with excitation light of 460nm (light split by a diffraction grating spectroscope from a 150W xenon lamp) was measured in the atmosphere using a color luminance meter BM5A manufactured by TOPCON while keeping the temperature at 25 ℃ and 100 ℃ respectively. Then, the ratio of the luminance at 100 ℃ to the luminance at 25 ℃ was calculated as a luminance maintenance ratio TR (%).

In this connection, the wavelength conversion materials 203 and 204 preferably have a low sulfur content. Since sulfur may be a cause of thermal deterioration of the wavelength conversion materials 203 and 204, a white light emitting device having good characteristics can be obtained by using the wavelength conversion materials 203 and 204 containing less sulfur, preferably containing no sulfur. Specifically, the wavelength conversion materials 203 and 204 preferably do not contain a substance containing a sulfur-containing compound as a matrix, that is, preferably do not contain a sulfide, oxysulfide, sulfate, or the like.

High internal quantum efficiency

The wavelength conversion materials 203, 204 preferably have internal quantum efficiencies of usually 40% or more, preferably 50% or more. A material having an internal quantum efficiency less than the lower limit of the range is not preferable because it lowers the light emission efficiency of the white light emitting device. Among them, the wavelength conversion materials 203 and 204 which emit light having a wavelength of 500nm to 600nm generate light in a region having particularly high visibility as secondary light, and therefore, the internal quantum efficiency is more preferably higher, and specifically, the internal quantum efficiency is more preferably 60% or more.

High absorbance

The absorbance of the wavelength conversion materials 203, 204 is usually 50%, preferably 60% or more, more preferably 70% or more, and still more preferably 75% or more. When the absorbance is less than the lower limit of the range, there is a possibility that the light emission efficiency of the white light emitting device cannot be sufficiently high.

The internal quantum efficiency and the absorbance described above are internal quantum efficiency and absorbance with respect to light of the emission wavelength of the light emitting element 202, specifically, internal quantum efficiency and absorbance when excited by light of the emission peak wavelength of light emitted by the light emitting element 202 (hereinafter, simply referred to as "light of the emission peak wavelength of the light emitting element 202" for convenience), and can be calculated as follows.

First, light having a light emission peak wavelength of a light emitting element is incident on a white diffusion plate having a reflectance of 0.97, reflected by the white diffusion plate, and the light reflected by the white diffusion plate is collected by an integrating sphere, and the light collected by the integrating sphere is captured by a multi-channel photodetector, and the reflected light intensity RW of the light having the light emission peak wavelength of the light emitting element reflected by the white diffusion plate is measured.

Next, light having the emission peak wavelength of the light emitting element is incident on the wavelength conversion material, light reflected by the wavelength conversion material and light emitted after wavelength conversion after being absorbed by the wavelength conversion material are collected by an integrating sphere, and the light collected by the integrating sphere is captured by a multi-channel photodetector in the same manner as the measurement of the reflected light intensity RW. After measurement with a multichannel photodetector, the reflected light intensity RP of the light emitting element at the emission peak wavelength reflected by the wavelength conversion material is measured.

Then, the absorption light intensity AP absorbed by the wavelength conversion material is calculated from the following formula (ii), and the wavelength of the light having the absorption light intensity AP multiplied by the emission peak wavelength of the light-emitting element is converted to a value PA corresponding to the number of quantum of the absorption light.

Absorbed light intensity AP = { (reflected light intensity RW)/0.97 } - (reflected light intensity RP) (ii)

The reflected light intensity RW is similarly multiplied by the wavelength and converted into a value RWA corresponding to the number of reflected light quanta.

Then, the product of the intensity and the wavelength of light in a wavelength range (i.e., a wavelength range of light emitted from the wavelength conversion material) in which the reflected light is not contained in the wavelength component of the observed light is added to the light having the emission peak wavelength of the light-emitting element captured in the measurement of the reflected light intensity RP and collected by the integrating sphere, and the sum is converted into a value PP corresponding to the number of emitted light quanta.

Finally, the internal quantum efficiency is calculated from "internal quantum efficiency = (value PP corresponding to the number of emitted light quanta)/(value PA corresponding to the number of absorbed light quanta)".

The absorbance was calculated from "absorbance = (value PA corresponding to the number of absorbed light quanta)/{ (value RWA corresponding to the number of reflected light quanta)/0.97 }".

In addition, the above-described high internal quantum efficiency and high absorbance are preferable, and both of these characteristics are more preferable.

As the wavelength converting materials 203, 204 satisfying the above characteristics, ca, for example, can be used ₃ Sc ₂ Si ₃ O ₁₂ :Ce、Ca ₃ (Sc，Mg) ₂ Si ₃ O ₁₂ :Ce、CaSc ₂ O ₄ Green emitting material of Ce, etc. and CaAlSiN ₃ :Eu ²⁺ 、(Sr，Ca)AlSiN ₃ :Eu ²⁺ 、SrAlSiN ₃ P:Eu ²⁺ And the like, but is not limited to these materials as long as the above conditions are satisfied.

Next, specific examples of the first wavelength conversion material and the second wavelength conversion material described above can be given as examples of preferable wavelength conversion materials 203 and 204 used in the white light emitting device of the present embodiment. However, the wavelength conversion materials 203, 204 are not limited to the materials exemplified below.

(example of first wavelength converting Material)

As a first example of the first wavelength conversion material, the green phosphor used in the first light-emitting device of the present invention can be given.

(other examples of the first wavelength converting Material)

Other examples of the first wavelength converting material include (Ba, ca, sr) MgAl ₁₀ O ₁₇ :Eu、(Ba，Mg，Ca，Sr) ₅ (PO) ₄ Cl:Eu、(Ba，Ca，Sr) ₃ MgSi ₂ O ₈ Eu, etc. having a light emission peak at 400nm to 500 nm; (Ba, ca, sr) MgAl ₁₀ O ₁₇ :Eu，Mn、(Ba，Ca，Sr)Al ₂ O ₄ :Eu、(Ba，Ca，Sr)Al ₂ O ₄ :Eu，Mn、 (Ca，Sr)Al ₂ O ₄ Eu, formula Ca _x Si _12-(m+n) Al _(m+n) O _n N _16-n Eu (wherein, 0.3 < x < 1.5, O.6 < m < 3, 0. Ltoreq. N < 1.5) and Eu-activated α sialon (silon) and the like have a luminescence peak at 500 to 600nm, but are not limited thereto. In addition, a plurality of the above phosphors can be used.

(examples of second wavelength converting Material)

As a first example of the second wavelength conversion material, a red phosphor used in the first light-emitting device of the present invention can be given.

(other examples of second wavelength converting Material)

As another example of the second wavelength conversion material, there is no particular limitation as long as light emitted therefrom is synthesized with primary light emitted from the light emitting element or secondary light emitted from the first wavelength conversion material to form white light, and for example, the compound represented by the general formula Ca can be used _x Si _12-(m+n) Al _(m+n) O _n N _16-n Eu (wherein, 0.3 < x < 1.5, 0.6 < m < 3, 0. Ltoreq. N < 1.5) activated by Eu, and Ca ₂ Si ₅ N ₈ :Eu、 Sr ₂ Si ₅ N ₈ :Eu、(Ca，Sr) ₂ Si ₅ N ₈ :Eu、CaSi ₇ N ₁₀ Eu, a fluorescent europium complex, and the like. In addition, a plurality of the above phosphors can be used.

In the case of using the first wavelength conversion material and the second wavelength conversion material in combination, the ratio of the amounts of the two materials used is arbitrary without significantly impairing the effect of the present invention, but the volume ratio of the second wavelength conversion material to the first wavelength conversion material is preferably usually 0.05 or more, preferably 0.1 or more, more preferably 0.2 or more, and usually 1 or less, preferably 0.8 or less, more preferably 0.5 or less. When the ratio is too large or too small, it is difficult to obtain ideal white light.

In addition, the wavelength converting materials 203, 204 are generally used in a granular form. In this case, the particle diameter of the particles of the wavelength conversion materials 203 and 204 is arbitrary, but is usually 150 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. When the particle diameter is larger than this range, the fluctuation of the emission color of the white light-emitting device 1 becomes large, and at the same time, when the wavelength converting material 202 and the adhesive (sealant) are mixed, it may be difficult to uniformly apply the wavelength converting materials 203, 204. The lower limit of the particle size is usually 1 μm or more, preferably 5 μm or more. When the particle diameter is smaller than this range, the luminous efficiency may be lowered.

In addition, the existence state of the wavelength converting materials 203, 204 is arbitrary without significantly impairing the effects of the white light emitting device of the present invention. For example, it may be held to frame 205 using adhesive 209 or secured to frame 205 without using adhesive 209.

The binder 209 is typically used to aggregate and adhere the powdered or granular wavelength converting material 203, 204 to the frame 205. The adhesive 209 used in the white light emitting device 201 of the present embodiment is not limited, and any known adhesive may be used.

In the case where the white light emitting device 201 is configured to be transmissive, that is, in the case where the primary light and the secondary light are emitted to the outside of the white light emitting device 201 through the adhesive 209, it is desirable to select an adhesive that allows each component of the light emitted from the white light emitting device 201 to pass through as the adhesive 209.

For example, in the case of the binder 209, an inorganic material such as glass may be used in addition to a resin. Specific examples thereof include organic synthetic resins such as epoxy resins and silicone resins, and silicone gels; inorganic materials such as glass.

In the case of using a resin as the binder 209, the viscosity of the resin is arbitrary, and it is preferable to use the binder 209 having an appropriate viscosity in accordance with the particle diameter and specific gravity of the wavelength conversion materials 203 and 204 to be used, particularly the specific gravity per unit surface area. For example, when an epoxy resin is used for the adhesive 209, it is preferable that the wavelength conversion materials 203 and 204 have a particle diameter of 2 to 5 μm and a specific gravity of 2 to 5, since particles of the wavelength conversion materials 203 and 204 can be dispersed well if an epoxy resin having a viscosity of 1Pas to 10Pas is used.

The binder 209 may be used alone, or two or more thereof may be used in any combination and ratio.

In addition, other components may also be present in the wavelength converting materials 203, 204 at the same time. The other components are not particularly limited, and known additives can be used as desired.

Specifically, for example, when controlling the light distribution characteristics and/or color mixing of the white light emitting device 201, it is preferable to use a diffusing agent such as alumina or yttria as the other component.

For example, when the wavelength conversion materials 203 and 204 are packed in a high density, a binder such as calcium pyrophosphate or barium calcium borate is preferably used as another component.

In addition, the wavelength conversion material can be held in the frame without using the adhesive 209. For example, the wavelength conversion material may be fired to form a fired body, and the fired body may be directly attached to the frame. For example, the wavelength conversion material may be mounted on the frame after being formed into glass, or a single crystal of the wavelength conversion material may be processed to be mounted on the frame.

In addition, when the binder 209 is used, the other components described above may be dispersed in the binder 209, but when the binder 209 is not used, other components such as an additive may be coexistent in the wavelength converting material.

In the present embodiment, the wavelength converting material 203 belonging to the first wavelength converting material and the wavelength converting material 204 belonging to the second wavelength converting material described above are used as the wavelength converting materials 203, 204, and these wavelength converting materials 203, 204 are held in the recessed portions 205A of the frame 205 in a state of being dispersed in the adhesive 209.

The wavelength conversion materials 203 and 204 used in the present embodiment are those which exhibit a small change in emission intensity due to a temperature rise, have high internal quantum efficiency, and have high absorbance. In addition, the adhesive 209 may transmit the primary light emitted by the light emitting element 202 and the secondary light emitted by the wavelength converting materials 203, 204, and thus, may emit white light in the form of combined light of the primary light and the secondary light.

[ III-2-4. Production method ]

The method of manufacturing the white light emitting device 201 is not limited, and may be any method, for example, a method of dispersing the wavelength conversion materials 203 and 204, and the binder 209 and other components used as appropriate in a dispersion medium, preparing a slurry, applying the prepared slurry to the frame 205 on which the light emitting element 202 is mounted, and then drying the slurry, thereby forming the white light emitting device 201. In addition, the light-emitting element 202 may be attached to the frame 205 at the time of or after the application of the paste.

The wavelength conversion materials 203 and 204, a binder 209 used as appropriate, and other components such as additives are mixed in a dispersion medium to prepare a slurry. In addition, depending on the kind of the binder 209, the paste may be referred to as paste, particles, or the like instead, and in the description of the white light emitting device of the present invention, the term paste includes these terms.

The dispersion medium used for preparing the slurry is not limited, and any known dispersion medium can be used. Specific examples thereof include chain hydrocarbons such as n-hexane, n-heptane, SOLVESSO and the like; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as trichloroethylene and perchloroethylene; alcohols such as methanol, ethanol, isopropanol, and n-butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate and n-butyl acetate; ethers such as cellosolve, butyl cellosolve, and cellosolve acetate; water, an aqueous solvent such as an aqueous solution, and the like.

The prepared slurry is then applied to a substrate such as frame 205. The coating method is arbitrary, and for example, a coater, casting, or the like can be used.

After the coating, the dispersion medium is dried, and the wavelength conversion materials 203 and 204 are fixed to the frame 205. The drying method is arbitrary, and for example, natural drying, heat drying, vacuum drying, baking, ultraviolet irradiation, electron beam irradiation, or the like can be used. Among them, drying at a temperature of several tens to a hundred and several tens of ℃ is preferable because the inexpensive equipment can easily and reliably remove the dispersion medium.

When the wavelength conversion materials 203 and 204 are highly densified for the purpose of manufacturing a reflective white light emitting device (described later), it is preferable to mix a binder as another component in the slurry. In addition, when the slurry mixed with the binder is applied, a coating method such as screen printing or inkjet printing is preferably used. This is because the coating of the slurry (coating りわけ) and the like can be easily performed. Of course, when a binder is used, it may be coated by a common coating method.

In addition, there is a method in which the slurry is not used. For example, the white light emitting device 201 can also be manufactured by mixing the wavelength conversion materials 203 and 204 with the binder 209 and other components used as appropriate, kneading and molding the mixture, and attaching the wavelength conversion materials 203 and 204 to the frame 205. In addition, in the case of molding, for example, molding can be performed by performing press molding, extrusion molding (T-die extrusion, hollow extrusion, blow molding, melt spinning, profile extrusion, and the like), injection molding, or the like.

When the adhesive 209 is a thermosetting adhesive such as an epoxy resin or a silicone resin, the white light emitting device 201 can also be manufactured by mixing and molding the adhesive 209 before curing, the wavelength conversion materials 203 and 204, and other components used as appropriate, and then curing the adhesive 209 by heating to attach the wavelength conversion materials 203 and 204 to the frame 205. In the case where the adhesive 209 is a UV (ultraviolet) curable adhesive, the adhesive 209 is cured by irradiation with UV light instead of heating in the above-described method, and the wavelength conversion materials 203 and 204 are attached to the frame 205, whereby the white light emitting device 201 can be manufactured.

The wavelength conversion materials 203 and 204 may be produced in a series of steps during the production of the white light emitting device 201, or components containing the wavelength conversion materials 203 and 204 may be prepared separately in advance and then mounted on the frame 205 or the like to complete the white light emitting device 201.

[ III-3. Effect ]

Since the white light emitting device 201 of the present embodiment is configured as described above, when used, power is supplied to the light emitting element 202, and then the light emitting element 202 emits light. The light emitting element 202 emits primary light when power is supplied thereto. A part of the primary light is absorbed by the wavelength converting materials 203, 204 dispersed in the adhesive 209, whereby the wavelength converting materials 203, 204 each emit fluorescence as secondary light. In this manner, the primary light not absorbed by the wavelength converting materials 203, 204 and the secondary light emitted by the wavelength converting materials 203, 204 transmit through the adhesive 209, and white light is emitted from the white light emitting device 201 as combined light of the primary light and the secondary light.

The white light emitting device 201 of the present embodiment emits white light having a flat emission spectrum in the predetermined wavelength range described above, and therefore has excellent color rendering properties.

In addition, since the wavelength conversion materials 203 and 204 having small temperature dependence of emission intensity are used in the white light emitting device 201 of the present embodiment, it is possible to suppress the conventional phenomenon in which the color tone of white light changes with time after lighting.

In the white light emitting device 201 of the present embodiment, the wavelength conversion materials 203 and 204 having high internal quantum efficiency and high absorbance with respect to light having the same wavelength as the primary light emitted from the light emitting element 202 are used, so that the intensity ratio of the white light emitted from the white light emitting device 201 can be increased, and the light emitting efficiency of the white light emitting device 201 can be improved.

In the present embodiment, white light is exemplified by white light containing a primary light component, but white light containing no primary light can also provide similar advantages.

[ III-4. Other ]

While one embodiment of the white light emitting device of the present invention has been described above, the white light emitting device of the present invention is not limited to the above-described embodiment, and may be arbitrarily changed in implementation as long as the gist of the present invention is not exceeded.

For example, the white light emitting device 201 may also be made reflective. As a specific example thereof, as shown in fig. 7, a structure may be adopted in which primary light emitted from the light emitting element 202 is reflected on the surface of the frame 205 or the like and emitted to the outside. In fig. 7, the same reference numerals as in fig. 6 denote the same meanings as in fig. 6.

In the configuration of fig. 7, the light emitting element 202 is disposed away from the frame 205 by the beam 210, and the wavelength converting materials 203, 204 are applied and formed on the surface of the recess 205A of the frame 205 in a state of being dispersed in the adhesive 209.

In addition, conductive terminals 206, 207 are provided on the beam 210 so as to be able to supply power to the light emitting element 202. The white light emitting device 201 of fig. 7 is configured in the same manner as in the above-described embodiment.

In this case, a part of the primary light emitted from the light emitting element 202 is reflected on the surface of the frame 205 or the like and emitted to the outside of the white light emitting device 201 as a component of white light, and the other part is absorbed by the wavelength converting materials 203 and 204. Then, the wavelength conversion materials 203 and 204 fixed to the surface of the concave portion 205A absorb the primary light and are excited to emit the secondary light. Thereby, the white light emitting device 201 can emit white light as combined light of the primary light and the secondary light.

Even when the white light emitting device 201 is configured as a reflection type, by providing white light so as to have a flat emission spectrum in the above-described predetermined wavelength range, the color rendering property of the white light can be improved, and by using the wavelength conversion materials 203, 204 having small temperature dependency of emission intensity, it is possible to suppress the change in color tone of the white light with time after lighting, and further, by using the wavelength conversion materials 203, 204 having high internal quantum efficiency and high absorbance with respect to light having the same wavelength as the primary light emitted from the light emitting element 202, it is possible to improve the intensity of the white light, and further, to improve the emission efficiency of the white light emitting device 201.

For example, in addition to being used after mixing the wavelength conversion materials 203 and 204 as in the above-described embodiment, the wavelength conversion materials 203 and 204 may be disposed in different locations or members depending on the properties, types, and the like of the wavelength conversion materials.

As a specific example, as shown in fig. 8, the wavelength conversion material 203 may be dispersed in the adhesive 209A in a part of the concave portion 205A of the frame 205, and the wavelength conversion material 204 may be dispersed in the adhesive 209B in the remaining part of the concave portion 205A. In fig. 8, the same reference numerals as in 6,7 denote the same parts as in 6,7. The adhesive 209A and the adhesive 209B may be the same or different.

In the configuration of fig. 8, a part of the primary light emitted from the light emitting element 202 is emitted to the outside of the white light emitting device 201 as a component of white light, and the other part is absorbed by the wavelength converting materials 203 and 204. Then, the wavelength converting material 203 dispersed in the binder 209A and the wavelength converting material 204 dispersed in the binder 209B are excited by the primary light to emit the secondary light, respectively, whereby the white light emitting device 201 can emit white light in the form of combined light of the primary light and the secondary light.

Even when the white light emitting device 201 is disposed in different portions or members depending on the nature, kind, and the like of the wavelength conversion materials 203, 204 as shown in fig. 8, the color rendering property of the white light can be improved by providing the white light so as to have a flat emission spectrum in the above-described predetermined wavelength range, and the use of the wavelength conversion materials 203, 204 having small temperature dependence of the emission intensity can suppress the change in the color tone of the white light with time after lighting, and further, the use of the wavelength conversion materials 203, 204 having high internal quantum efficiency and high absorbance with respect to light having the same wavelength as the primary light emitted from the light emitting element 202 can improve the intensity of the white light, thereby improving the emission efficiency of the white light emitting device 201.

In addition, the white light emitting device 201 of fig. 8 may be further modified in that different concave portions 205A are provided in the frame 205 depending on the wavelength converting materials 203, 204, and the wavelength converting materials 203, 204 are disposed in the different concave portions 205A depending on the nature, kind, and the like of the wavelength converting materials 203, 204.

[ III-5. Lighting device ]

The white light emitting device 201 described above may be used for a lighting device. The lighting device is not limited to the above-described white light emitting device 201, and in general, the configuration of the lighting device is appropriately combined with other components such as a light distribution element such as a lens, a protective cover, an antireflection film, a field-of-view expanding film, a luminance enhancement film, a lens sheet, and a heat dissipation plate.

As an example, the surface-emission lighting device 211 shown in fig. 9 can be configured using, for example, a white light emitting device 201. In the surface-emission lighting device 211, a large number of the white light-emitting devices 201 are arranged in parallel in the support case 212, the support case 212 is a housing having an upper surface opened, and the white light-emitting devices 201 emit white light toward the opening portion 212A of the support case 212. Here, the white light emitting device 201 is a white light emitting device obtained by covering the same white light emitting device as that described in the above embodiment with a mold member. Power can be supplied to each white light emitting device 201 from a power supply or a circuit (not shown). Further, a diffusion plate 213 such as an acrylic resin plate is provided in the opening portion 212A of the support case 212, and the primary light and the secondary light emitted from the white light emitting device 201 are diffused in the diffusion plate 213, so that uniform white light without imbalance is emitted from the diffusion plate 213 to the outside.

By configuring the lighting device using the white light emitting device 201 as described above, advantages similar to those of the white light emitting device 201, such as improvement in color rendering properties, suppression of change in color tone of white light with time after lighting, improvement in intensity of white light, and improvement in light emission efficiency of the white light emitting device 201, can be obtained.

The surface-emission lighting device 211 described with reference to fig. 9 is an example of the lighting device of the present invention, and the lighting device of the present invention may be arbitrarily changed in implementation as long as it does not exceed the gist of the present invention.

[ III-6. Display device ]

The white light emitting device 201 described above can be used in a display device (image display device). The display device is not limited to the above-described white light emitting device 201 if it is provided, and generally, an imaging unit for forming an image, other components similar to the lighting device, and the like are appropriately combined in the configuration of the display device.

For example, the display device 221 shown in fig. 10 can be configured using a white light emitting device 201. The display device 221 has a white light emitting device 201, a light guide plate 222, a reflective film 223, a diffusion plate 224, and an imaging unit 225.

The white light emitting device 201 is formed similarly to the above-described light emitting device, and thus can be used as a backlight unit for illuminating the imaging unit 225 from the back side.

The light guide plate 222 is a member for guiding white light emitted from the white light emitting device 201 to the imaging unit 225, and any known light guide plate may be used, and a light guide plate using a mirror, a prism, a lens, an optical fiber, or the like is commonly used. When the light guide plate 222 is used, the white light emitting device 201 can be disposed at an arbitrary position with respect to the imaging unit 225, and the degree of freedom in designing the display device 221 can be increased.

In this embodiment, a display device using a prism as a light guide plate is manufactured.

The reflective film 223 is a member that reflects white light emitted from the white light emitting device 201, and is provided on the back surface of the light guide plate 222. Accordingly, the white light emitted from the white light emitting device 201 provided in the lateral direction of the light guide plate 222 in the figure is reflected by the reflective film 223 and can be guided to the shaping unit 225 through the diffusion plate 224 provided in the upper part in the figure.

The diffuser 224 diffuses light emitted from the white light emitting device 201, and light emitted from the white light emitting device 201 is diffused inside the diffuser 224 to form uniform white light without imbalance and is emitted to the imaging unit 225.

The diffuser plate 224 may have any shape, material, size, and the like, and for example, a sheet having irregularities on both the front and back sides and a structure in which fine particles of synthetic resin, glass, or the like are dispersed in a binder such as synthetic resin may be used. In this embodiment, the diffusion plate 224 in which fine particles are dispersed in a binder is used for the display device.

In addition, the imaging unit 225 is a member that irradiates the back surface side (lower side in the drawing) of the white light emitted from the white light emitting device 201 and forms an image on the surface side (upper side in the drawing). If an image can be formed and at least a part of the white light irradiated can be transmitted, the imaging unit is not limited to any other type, and any known member having any shape, size, material, or the like can be used.

Specific examples of the imaging unit 225 include a liquid crystal unit used in a liquid crystal display or the like, a marker used in an interior illumination marker or the like.

For example, as an example of the liquid crystal cell, there is a liquid crystal cell having a structure in which a color filter, a transparent electrode, an orientation film, a liquid crystal, an orientation film, and a liquid crystal layer in which transparent electrodes are stacked in this order are held in a container such as a glass dish having polarizing films attached to both front and rear sides thereof. In this case, in the liquid crystal cell, the white light emitting device 201 described above irradiates the liquid crystal cell with white light (backlight) from the back surface side by controlling the molecular arrangement of the liquid crystal by the electrode applied to the transparent electrode to form an image, whereby the image formed in the liquid crystal cell can be clearly displayed on the front surface side of the liquid crystal cell.

The position where the display device displays the image formed on the imaging unit may be on the front surface side of the imaging unit, and the image may be displayed by projecting the image on a certain projection surface in addition to directly displaying the image on the front surface side of the imaging unit. Examples of such a display device include a liquid crystal projector.

In addition, for example, in the case of using a marker as an imaging unit, the white light emitting device 201 described above irradiates the marker with white light from the back side, whereby an image formed on the marker can be clearly displayed on the front side of the marker.

The image formed by the imaging unit 225 may be any image, and may be a character or an image.

In this embodiment, a liquid crystal cell that displays a direct image on the surface is used as the imaging unit 225.

When the display device is configured as described above, white light is emitted from the white light emitting device 201, and the imaging unit 225 is irradiated from the back side, whereby an image formed in the imaging unit 225 can be clearly reflected on the front surface of the imaging unit 225.

In this case, when the display device 221 is configured by using the white light emitting device 201 as described above, it is possible to improve the color reproducibility of the displayed image by improving the color rendering property, and also to obtain the same advantages as those of the white light emitting device 201, such as suppressing the change in the color tone of the white light with the lapse of time after lighting, improving the intensity of the white light, and improving the light emission efficiency of the white light emitting device 201.

The display device 221 described with reference to fig. 10 is an example of the display device of the present invention, and the display device of the present invention may be arbitrarily changed in implementation as long as the gist of the present invention is not exceeded.

[ IV. description of the image display apparatus ]

The image display device of the present invention will be described in detail below with reference to embodiments, but the image display device of the present invention is not limited to the embodiments described below, and may be changed as desired in practice without departing from the gist of the present invention.

Fig. 11 is a schematic cross-sectional view illustrating a main part structure of a color display as one embodiment of an image display device of the present invention.

As shown in fig. 11, the color display of the present embodiment has a red pixel (hereinafter referred to as a "red pixel" for convenience) 301 and at least one non-red pixel 302, 303.

Here, the non-red pixels 302 and 303 are not limited, and any light source that emits light of a color other than red may be used as the non-red pixels 302 and 303, and in general, in the color display 301, a green pixel (hereinafter referred to as "green pixel" for convenience) 302 and a blue pixel (hereinafter referred to as "blue pixel" for convenience) 303 are used as the non-red pixels 302 and 303, and these red, green, and blue pixels are combined to synthesize any color.

In the present embodiment, the red pixel 301 has a red light-emitting device (red light-emitting element) 311, and the red light-emitting device 311 has a red pixel light-emitting element 313 and a red phosphor 314 having a phosphor temperature-dependent coefficient of 85 or more.

[ IV-1. Red pixels ]

Fig. 12 is a sectional view schematically illustrating a main part of the red light emitting device 311 according to the present embodiment. However, the configuration of the red light emitting device is not limited to the configuration shown in fig. 12.

The red pixel 301 according to this embodiment has a red light-emitting device 311, and the red light-emitting device 311 has a red pixel light-emitting element 313 and a red phosphor 314 as a wavelength conversion material, and the red phosphor 314 is excited by light emitted from the red pixel light-emitting element 313 to emit red light from the red phosphor 314, and the red light is emitted from the red pixel 301 as red light. A part of the light emitted from the red pixel light-emitting element 313 may be emitted to the outside of the color display as a component of red light emitted from the red pixel 301 together with red light emitted from the red phosphor 314 without being absorbed as excitation light by the red phosphor 314.

The peak wavelength of red light emitted by the red pixel 301 can be set arbitrarily according to the use state, purpose, and the like of the color display, but is usually 580nm or more, preferably 600nm or more, and is usually 680nm or less, preferably 660nm or less.

The red light-emitting device 311 included in the red pixel 301 generally has a frame 312 as a base for holding the red pixel light-emitting element 313 and the red phosphor 314.

[ IV-1-1. Frame ]

The frame 312 is a base portion for holding the red pixel light-emitting element 313 and the red phosphor 314, and the shape, material, and the like thereof are arbitrary.

As a specific example of the shape of the frame 312, a plate shape, a cup shape, or the like may be appropriately formed according to the application. In the illustrated shape, a cup-shaped frame is preferable because the emission direction of white light can be made directional and light emitted from the red light-emitting device 311 can be effectively used.

Specific examples of the material of the frame 312 include inorganic materials such as metals, alloys, glasses, and carbon; organic materials such as synthetic resins, and the like.

However, it is preferable to increase the reflectance of the frame 312 to light emitted from the red pixel light-emitting element 313 and/or the red phosphor 314, and particularly, to light in the entire visible light range. Therefore, at least the surface to which light is irradiated is preferably formed of a material having a high reflectance. Specific examples thereof include forming the entire frame 312 or the surface of the frame 312 with a material (injection molding resin or the like) containing a substance having a high reflectance such as glass fiber, alumina powder, titanium dioxide powder or the like.

The specific method of increasing the reflectance of the surface of the frame 312 is arbitrary, and the reflectance of light may be increased by plating or vapor deposition treatment with a metal or alloy having a high reflectance such as silver, platinum, or aluminum, in addition to the above-described selection of the material of the frame 312 itself.

The portion for increasing the reflectance may be the entire frame 312 or a part thereof, and it is generally preferable to increase the reflectance of the entire surface of the portion to which light emitted from the red pixel light-emitting element 313 and/or the red phosphor 314 is irradiated.

In addition, in block 312, an electrode, a terminal, and the like for supplying power to the light-emitting element 313 for red pixels are usually provided.

In this embodiment, conductive terminals 315 and 316 for supplying power to the light emitting element 313 for red pixel are formed at the bottom of the concave portion 312A of the frame 312 formed in a cup shape, and the conductive terminals 315 and 316 are connected to an external power supply (not shown).

[ IV-1-2. Light-emitting element for red pixel ]

The red pixel light-emitting element 313 emits excitation light of the red phosphor 314.

The red pixel light-emitting element 313 may be of any type, and examples thereof include a light-emitting diode (i.e., "LED"), an end-emission type or surface-emission type laser diode (i.e., "LD"), and an electroluminescent element. Among them, low-priced LEDs are generally preferred.

The emission wavelength of light emitted from the red pixel light-emitting element 313 is also arbitrary, and a light-emitting element that emits light of an appropriate emission wavelength can be used as the red pixel in accordance with red light emitted from the red light-emitting device 311. In general, a light-emitting element which emits light of near ultraviolet to blue-green as excitation light is preferably used. Specific wavelength ranges of light emitted from the red pixel light-emitting element 313 are usually 370nm or more, preferably 380nm or more, and usually 500nm or less, preferably 480nm or less. Outside this range, it is difficult to manufacture a high-efficiency LED.

Specific examples of the red pixel light-emitting element 313 include light-emitting elements in which a light-emitting layer made of an InGaN-based, gaAlN-based, inGaAlN-based, or ZnSeS-based semiconductor is formed on a substrate made of silicon carbide, sapphire, gallium nitride, or the like by MOCVD or the like. Examples of the semiconductor structure include a homostructure, a heterostructure, and a double heterostructure having an MIS junction, a PIN junction, a PN junction, and the like. In addition, the semiconductor active layer may be formed in a single quantum well structure or a multiple quantum well structure formed on a thin film which produces a quantum effect. The active layer may be doped with toner impurities such as Si and Ge and/or acceptor impurities such as Zn and Mg. Among them, an (In, ga) N-based light-emitting element containing (In, ga) N as a main component is preferably used. Particularly preferred is an (In, ga) N-based LED.

One of the red pixel light-emitting elements 313 may be used alone, or two or more of the red pixel light-emitting elements 313 may be used in combination. In addition, only one kind of the red pixel light-emitting element 313 may be used, or two or more kinds may be used in combination.

When the red pixel light-emitting element 313 is mounted on the frame 312, a specific method is arbitrary, and for example, mounting using solder is possible. The type of solder is arbitrary, and AuSn, agSn, or the like can be used, for example. In addition, when solder is used, it is also possible to realize that power can be supplied from the electrodes formed in the frame 312, the terminals 315, 316, and the like by the solder. In particular, when a large-current LED or a laser diode, which is important in heat dissipation, is used as the red pixel light-emitting element 313, the solder exhibits excellent heat dissipation, and therefore, it is effective to provide the red pixel light-emitting element 313 using the solder.

When the red pixel light-emitting element 313 is mounted on the frame 312 by a substance other than solder, for example, an adhesive such as an epoxy resin, an imide resin, or an acrylic resin can be used. In this case, by using a substance in which a conductive filler such as silver particles or carbon particles is mixed with a binder to form a paste, power can be supplied to the red pixel light-emitting element 313 by applying current to the binder, as in the case of using solder. Further, mixing these conductive fillers is preferable because heat dissipation can be improved.

Further, the method of supplying power to the red pixel light-emitting element 313 is also arbitrary, and power supply may be performed by connecting the red pixel light-emitting element 313 and the electrodes or terminals 315 and 316 by a wire connection method, in addition to the above-described energization of the solder or the adhesive. The connecting wire used here is not limited, and the material, size, and the like thereof are arbitrary. For example, as a material of the connection line, a metal such as gold or aluminum may be used, and the thickness thereof is usually set to 20 μm to 40 μm, but the connection line is not limited thereto.

As another method of supplying power to the red pixel light-emitting element 313, a method of supplying power to the red pixel light-emitting element 313 by flip chip mounting using bumps is given.

In this embodiment, an (In, ga) N-based LED that emits light of near ultraviolet to blue-green is used as the light emitting element 313 for red pixel, and the light emitting element 313 for red pixel is provided at the bottom of the concave portion 312A of the frame 312. The red pixel light-emitting element 313 is directly connected to the conductive terminal 315, and is connected to the conductive terminal 316 via a connection line 317 by a wire bonding method, whereby power is supplied.

[ IV-1-3. Red phosphor ]

The red phosphor 314 absorbs light emitted from the red pixel light-emitting element 313 and emits red light. Therefore, the red phosphor 314 functions as a wavelength conversion material that converts the wavelength of light emitted from the red pixel light-emitting element 313 to form red light.

In the present embodiment, as the red phosphor 314, a red phosphor having a phosphor temperature dependence coefficient TR of usually 85 or more, preferably 90 or more, and more preferably 95 or more is used.

The phosphor temperature dependence coefficient TR represents a ratio of the luminance at 100 ℃ to the luminance at 25 ℃ of the phosphor in percentage units. Therefore, the phosphor temperature dependence coefficient TR in the above range indicates that the change in emission intensity of the red phosphor 314 due to the temperature increase is small. That is, the temperature dependence of the emission intensity of the red phosphor 314 is small.

In a conventional color display, red pixels having a large temperature dependence such as red light emitting LEDs are used. However, in this case, the intensity of red light emitted from the red pixel greatly changes due to temperature conditions as compared with light emitted from a non-red pixel, and the balance of the intensities of light emitted from the pixels changes, thereby changing the color tone of an image displayed on the color display. In contrast, in the present embodiment, the red pixel includes a red light-emitting device 311, and the red light-emitting device 311 includes a red pixel light-emitting element 313 and a red phosphor 314; meanwhile, by using the red phosphor 314 having a large phosphor temperature dependence coefficient TR, the color tone change described above can be suppressed, and color difference of the color display due to the temperature change can be prevented.

The temperature-dependent coefficient TR of the phosphor can be measured, for example, as follows.

First, using a temperature characteristic evaluation apparatus for ocean electron production, about 100mg of a measurement sample powder (phosphor) was charged into a powder container (ホルダ one) having a diameter of 8mm, and then placed in the apparatus. Thereafter, the luminance in the state of irradiation with 460nm excitation light (light split by a diffraction grating beam splitter for light from a 150W xenon lamp) was measured in the atmosphere using a color luminance meter BM5A manufactured by TOPCON while keeping the temperature at 25 ℃ and 100 ℃ respectively. Then, the ratio of the luminance at 100 ℃ to the luminance at 25 ℃ was calculated as the temperature dependence coefficient TR (%) of the phosphor.

In this connection, the red phosphor 314 preferably contains no sulfur as a constituent of the matrix compound. Since sulfur may cause thermal deterioration of the red phosphor 314, the use of a red phosphor containing no sulfur, for example, a red phosphor 314 other than sulfide or sulfate, can reduce the temperature dependence of the red phosphor 314.

The red phosphor 314 used in the present embodiment is preferably a red phosphor that efficiently absorbs light emitted from the red pixel light-emitting element 313, and more preferably a red phosphor having high emission efficiency.

Specifically, the internal quantum efficiency of the red phosphor 314 is preferably 40% or more, preferably 50% or more, and more preferably 60% or more. If the lower limit of the range is less than the lower limit of the range, a display having high luminous efficiency may not be obtained.

The absorbance of the red phosphor 314 is usually 50%, preferably 60% or more, more preferably 70% or more, and still more preferably 75% or more. If the absorbance is less than the lower limit of the range, a display having high luminous efficiency may not be obtained.

The internal quantum efficiency and the absorbance described above are internal quantum efficiency and absorbance for light having an emission wavelength of the red pixel light-emitting element 313, specifically, internal quantum efficiency and absorbance when excited by light having an emission peak wavelength of light emitted from the red pixel light-emitting element 313 (hereinafter, for convenience, simply referred to as "light having an emission peak wavelength of the red pixel light-emitting element"), and the internal quantum efficiency and the absorbance can be calculated as follows.

First, light having the emission peak wavelength of the light emitting element for red pixels is incident on a white diffusion plate having a reflectance of 0.97, reflected by the white diffusion plate, and the light reflected by the white diffusion plate is collected by an integrating sphere, and the light collected by the integrating sphere is captured by a multi-channel photodetector, and the reflected light intensity RW of the light having the emission peak wavelength of the light emitting element for red pixels reflected by the white diffusion plate is measured.

Next, light having an emission peak wavelength of the light emitting element for the red pixel is incident on the red phosphor, light reflected by the red phosphor and light emitted by wavelength conversion after absorption by the red phosphor are collected by an integrating sphere, and the light collected by the integrating sphere is captured by a multi-channel photodetector in the same manner as the measurement of the reflected light intensity RW. After measurement with the multi-channel photodetector, the reflected light intensity RP of the light having the emission peak wavelength of the red pixel light-emitting element reflected by the red phosphor is measured.

Then, the absorption light intensity AP absorbed by the red phosphor is calculated from the following formula (iii), and the wavelength of light having the emission peak wavelength of the red pixel light-emitting element is multiplied by the absorption light intensity AP, and converted into a value PA corresponding to the number of light quanta of the absorption light.

Absorbed light intensity AP = { (reflected light intensity RW)/0.97 } - (reflected light intensity RP) (iii)

The reflected light intensity RW is similarly multiplied by the wavelength and converted into a value RWA corresponding to the number of reflected light quanta.

Then, the light having the emission peak wavelength of the red pixel light-emitting element captured in the measurement of the reflected light intensity RP is incident on the red phosphor and collected by the integrating sphere, and the product of the intensity and the wavelength of light in a wavelength range not including the reflected light (i.e., the wavelength range of the light emitted by the red phosphor) in the wavelength component of the observed light is added to the light, and converted into a value PP corresponding to the number of emitted light quanta.

Finally, the internal quantum efficiency is calculated from "internal quantum efficiency = (value PP corresponding to the number of emitted light quanta)/(value PA corresponding to the number of absorbed light quanta)".

The absorbance was calculated from "absorbance = (value PA corresponding to the number of photons of absorbed light)/{ (value RWA corresponding to the number of photons of reflected light)/0.97 }".

The red phosphor 314 preferably has both the above-described characteristic of high internal quantum efficiency and the characteristic of high light absorption.

In addition, any red phosphor 314 may be used without departing from the gist of the present invention. One kind of the red phosphor 314 may be used alone, or two or more kinds may be used in any combination and ratio.

In the xy chromaticity diagram, the chromaticity x of the light emitted from the red phosphor 314 is preferably usually 0.50 or more, preferably 0.60 or more, and more preferably 0.63 or more. In addition, y is usually 0.2 or more, preferably 0.3 or more, and usually 0.35 or less.

(examples of Red phosphor)

As the red phosphor 314 usable in the image display device of the present invention, for example, the red phosphor used in the first light-emitting device of the present invention can be used, but is not limited thereto.

(other examples of Red phosphor)

Other examples of the red phosphor 314 include those represented by the general formula Ca _x Si _12-(m+n) Al _(m+n) O _n N _16-n Eu (wherein, x is more than 0.3 and less than 1.5, m is more than 0.6 and less than 3, and n is more than 0 and less than 1.5) activated by Eu, and Ca ₂ Si ₅ N ₈ :Eu、CaSi ₇ N ₁₀ :Eu、CaSiN ₂ Eu, a fluorescent europium complex, etc. In addition, a plurality of the above phosphors can be used.

Among these, MSiAlN is a particularly preferable example from the viewpoint of satisfactorily combining the temperature dependence coefficient, absorbance, internal quantum efficiency and the like of the phosphor described above ₃ :Eu ²⁺ (where M is at least one metal selected from Ca and Sr).

The red phosphor 314 is usually used in a granular form. In this case, the particle size of the red phosphor 314 is arbitrary, but the particle size is usually 150 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. If the ratio is more than this range, the variation in the emission color of the red light-emitting device 311 may be large, and it may be difficult to uniformly coat the red phosphor 14 when the red phosphor 14 and a binder (sealant) are mixed. The lower limit of the particle size is usually 1 μm or more, preferably 5 μm or more. If the amount is less than this range, the luminous efficiency may be lowered.

The state of existence of the red phosphor 314 is arbitrary without significantly impairing the effect of the image display device of the present invention. For example, it may be held to frame 312 using adhesive 318 or it may be secured to frame 312 without using adhesive 318.

The binder 318 is generally used to gather and adhere the red phosphor 314 in powder or granular form to the frame 312. The adhesive 318 used in the present embodiment is not limited, and a known adhesive can be used arbitrarily.

However, when the red light emitting device 311 is configured to be transmissive, that is, when red light is emitted to the outside of the red light emitting device 311 through the adhesive 318, it is desirable to select an adhesive that can transmit each component of red light as the adhesive 318.

For example, the binder 318 may be an inorganic material such as glass, in addition to a resin. Specific examples thereof include organic synthetic resins such as epoxy resins and silicone resins, and silicone gels; inorganic materials such as glass.

When a resin is used as the binder 318, the viscosity of the resin is arbitrary, and it is preferable to use the binder 318 having an appropriate viscosity according to the particle diameter and specific gravity of the red phosphor 314 to be used, particularly the specific gravity per unit surface area. For example, when an epoxy resin is used for the binder 318, it is preferable that the red phosphor 314 has a particle size of 2 to 5 μm and a specific gravity of 2 to 5, since particles of the red phosphor 314 can be dispersed well if an epoxy resin having a viscosity of 1Pas to 10Pas is used.

The binder 318 may be used alone, or two or more thereof may be used in any combination and ratio.

In addition, other components may be present in the red phosphor 314 at the same time. The other components are not particularly limited, and known additives may be optionally used.

Specifically, for example, when the light distribution characteristics and/or the color mixture of the red light emitting device 311 are controlled, a diffusing agent such as alumina or yttria is preferably used as another component.

For example, when the red phosphor 314 is packed in a high density, a binder such as calcium pyrophosphate or barium calcium borate is preferably used as another component.

In addition, the red phosphor may be held by the frame 312 without using the adhesive 318. For example, the red phosphor may be fired to produce a fired body, and the fired body may be directly attached to the frame 312. For example, a glass made of a red phosphor may be attached to the frame, or a single crystal of a red phosphor may be processed to attach the red phosphor to the frame 312.

In addition, when the binder 318 is used, the other components described above may be dispersed in the binder 318, but when the binder 318 is not used, other components such as additives may be present in the wavelength converting material.

In the present embodiment, caSiAlN is used as the red phosphor 314 ₃ :Eu ²⁺ The red phosphors 314 are shown, and these red phosphors 314 are held in the recesses 312A of the frame 312 in a state of being dispersed in the binder 318.

The temperature dependence coefficient, absorbance, and internal quantum efficiency of the phosphor 314 used in the present embodiment are in the above-described preferred ranges. The binder 318 can transmit excitation light emitted from the red pixel light-emitting element 313 and red light emitted from the red phosphor 314.

[ IV-1-4. Method for producing Red light-emitting device ]

The method for manufacturing the red light-emitting device 311 is not limited, and any method may be used, for example, the red light-emitting device 311 can be formed by dispersing the red phosphor 314, the binder 318 used as appropriate, and other components in a dispersion medium, preparing a slurry, applying the prepared slurry to the frame 312 on which the red pixel light-emitting element 313 is mounted, and then drying the slurry. In addition, the red pixel light-emitting element 313 may be attached to the frame 312 during or after the application of the paste.

The red phosphor 314, a binder 318 used as appropriate, and other components such as additives are mixed in a dispersion medium to prepare a slurry. In addition, depending on the type of the binder 318, the slurry may be referred to as a paste, a pellet, or the like instead, and in the present embodiment, the term slurry includes these terms.

The dispersion medium used for preparing the slurry is not limited, and any known dispersion medium can be used. Specific examples thereof include chain hydrocarbons such as n-hexane, n-heptane, SOLVESSO and the like; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as trichloroethylene and perchloroethylene; alcohols such as methanol, ethanol, isopropanol, and n-butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate and n-butyl acetate; ethers such as cellosolve, butyl cellosolve, and cellosolve acetate; water, an optional aqueous solvent, and the like.

The prepared slurry is then applied to a substrate, such as a frame 312. The coating method is arbitrary, and for example, a coater, casting, or the like can be used.

After the application, the dispersion medium is dried, and the red phosphor 314 is fixed to the frame 312. The drying method is arbitrary, and for example, natural drying, heat drying, vacuum drying, baking, ultraviolet irradiation, electron beam irradiation, or the like can be used. Among them, drying at a temperature of several tens to a hundred and several tens of ℃ is preferable because the dispersion medium can be easily and reliably removed by an inexpensive apparatus.

When the density of the red phosphor 314 is increased for the purpose of manufacturing a reflective red light-emitting device, it is preferable to mix a binder as another component in the slurry. In addition, when the slurry mixed with the binder is applied, a coating method such as screen printing or inkjet printing is preferably used. This is because the coating of the slurry (coating りわしけ) and the like can be easily performed. Of course, when a binder is used, it may be coated by a common coating method.

In addition, there is a method in which the slurry is not used. For example, the red light emitting device 311 can be manufactured by mixing the red phosphor 314 with a binder 318 and other components used as appropriate, kneading and molding the mixture, and attaching the red phosphor 314 to the frame 312. In addition, in the case of molding, for example, molding can be performed by press molding, extrusion molding (T-die extrusion, hollow extrusion, blow molding, melt spinning, profile extrusion, and the like), injection molding, or the like.

When binder 318 is a thermosetting binder such as epoxy resin or silicone resin, binder 318 before curing, red phosphor 314, and other components used as appropriate are mixed and molded, and then binder 318 is cured by heating to attach red phosphor 314 to frame 312, whereby red light-emitting device 311 can also be manufactured. When the adhesive 318 is a UV curable adhesive, the adhesive 318 is cured by irradiation with UV light instead of heating in the above-described method, and the red phosphor 314 is attached to the frame 312, whereby the red light emitting device 311 can be manufactured.

The red phosphor 314 may be produced in a series of steps during the production of the red light-emitting device 311, or a member containing the red phosphor 314 may be prepared separately in advance and then mounted on the frame 312 or the like to complete the red light-emitting device 311.

[ IV-2. Green pixels ]

Fig. 13 is a sectional view schematically illustrating a main portion of a green light-emitting device (green light-emitting element) 321 of a green pixel 302 serving as one of non-red pixels according to the present embodiment.

The green pixel 302 used in this embodiment is not limited, and any light source that emits green light may be used without significantly impairing the effects of the image display device of the present invention. Therefore, a conventionally used green light-emitting LED may be used as the green pixel 302 according to the present embodiment, but as in the case of the red light source 301, it is preferable that the green pixel has a green light-emitting device 321 in a configuration thereof, in order to reduce temperature dependency and suppress a change in color tone due to a temperature change, and that the green light-emitting device 321 has a green pixel light-emitting element 323 and a green phosphor 324 as a wavelength conversion material.

In the present embodiment, as shown in fig. 13, the green pixel 302 has a green light-emitting device 321, the green light-emitting device 321 has a green pixel light-emitting element 323 and a green phosphor 324, and the green phosphor 324 is excited by light emitted from the green pixel light-emitting element 323 to emit green light from the green phosphor 324, and the green light is emitted from the green pixel 302 as green light. As in the case of the red light-emitting device 311, a part of the light emitted from the green pixel light-emitting element 323 is not absorbed by the green phosphor 324 as excitation light, and a component of green light emitted from the green pixel 302 may be emitted to the outside of the color display together with the green light emitted from the green phosphor 324.

The peak wavelength of the green light emitted by the green pixel 302 may be arbitrarily set according to the use state, purpose, and the like of the color display, but is usually 490nm or more, preferably 500nm or more, and usually 570nm or less, preferably 550nm or less.

The green light-emitting device 321 included in the green pixel 302 also has a frame 322 as a base for holding the green pixel light-emitting element 323 and the green phosphor 324.

[ IV-2-1. Frame ]

The frame 322 used for the green light-emitting device 321 is the same as the frame 312 used for the red light-emitting device 311.

In this embodiment, conductive terminals 325 and 326 for supplying power to the light emitting element 323 for the green pixel are formed at the bottom of the recess 322A of the cup-shaped frame 322, and the conductive terminals 325 and 326 are connected to an external power supply (not shown).

[ IV-2-2. Light-emitting element for Green Pixel ]

The green pixel light-emitting element 323 emits excitation light of the green phosphor 324.

The type of the green pixel light-emitting element 323 is not limited, and any light-emitting element that emits excitation light of the green phosphor 324 can be used, and for example, the same example as the example described as the red pixel light-emitting element 313 can be used. The method of mounting the green pixel light-emitting element 323 in the frame 322 is also the same as that described for the red pixel light-emitting element 313.

In this embodiment, an (In, ga) N-based LED that emits light of near ultraviolet to blue-green is used as the green pixel light-emitting element 323, and the green pixel light-emitting element 323 is provided at the bottom of the concave portion 322A of the frame 322. The green pixel light-emitting element 323 is directly connected to the conductive terminal 325, and is connected to the conductive terminal 326 via the connection line 327 by a wire bonding method, whereby power is supplied.

[2-3. Green phosphor ]

The green phosphor 324 absorbs light emitted from the green pixel light emitting element 323 and emits green light. Therefore, the green phosphor 324 functions as a wavelength conversion material that converts the wavelength of light emitted from the green pixel light-emitting element 323 to green light.

In the present embodiment, as the green phosphor 324, similarly to the red phosphor 314, a green phosphor having a phosphor temperature dependence coefficient TR of usually 85 or more, preferably 90 or more, and more preferably 95 or more is preferably used. This reduces the temperature dependence of the emission intensity of the green phosphor 324, suppresses the change in color tone of the image displayed on the color display, and prevents the color display from being color-shifted due to a temperature change.

The phosphor temperature-dependent coefficient TR of the green phosphor 324 can be measured in the same manner as in the case of the red phosphor 314.

In addition, in this connection, it is preferable that the green phosphor 324 contains no sulfur as a constituent component of the host compound, as in the case of the red phosphor 314.

The green phosphor 324 used in the present embodiment is preferably a green phosphor that efficiently absorbs light emitted from the green pixel light-emitting element 323, and more preferably a green phosphor having high emission efficiency.

Specifically, the green phosphor 324 preferably has an internal quantum efficiency of usually 40% or more, preferably 50% or more, and more preferably 60% or more. If the internal quantum efficiency is less than the lower limit of the range, a display having high luminous efficiency may not be obtained.

The absorbance of the green phosphor 324 is usually 50%, preferably 60% or more, more preferably 70% or more, and still more preferably 75% or more. If the absorbance is less than the lower limit of the range, a display having high luminous efficiency may not be obtained.

The above-mentioned internal quantum efficiency and absorbance are the internal quantum efficiency and absorbance with respect to light of the emission wavelength of the green pixel light-emitting element 323, specifically, the internal quantum efficiency and absorbance when excited by light of the emission peak wavelength of light emitted from the green pixel light-emitting element 323 (hereinafter simply referred to as "light of the emission peak wavelength of the green pixel light-emitting element" for convenience), and these can be measured in the same manner as the red phosphor 314, in which the green pixel light-emitting element 323 is used instead of the red pixel light-emitting element 313, and the green phosphor 324 is used instead of the red phosphor 314.

Any material may be used for the green phosphor 324 without departing from the gist of the present invention. One kind of the green phosphor 324 may be used alone, or two or more kinds may be used in any combination and ratio.

In the xy chromaticity diagram, the chromaticity x of the light emitted from the green phosphor 324 is preferably usually 0.18 to 0.4. Y is usually 0.45 or more, preferably 0.5 or more, and more preferably 0.55 or more.

(example of Green phosphor)

The green phosphor 324 used in the image display device of the present invention may be, for example, the green phosphor used in the first light-emitting device of the present invention, but is not limited thereto.

(other examples of Green phosphor)

Other examples of the green phosphor include (Ba, ca, sr) MgAl ₁₀ O ₁₇ :Eu、 (Ba，Mg，Ca，Sr) ₅ (PO) ₄ Cl:Eu、(Ba，Ca，Sr) ₃ MgSi ₂ O ₈ Eu, etc. having a luminescence peak at 400nm to 500 nm; (Ba, ca, sr) MgAl ₁₀ O ₁₇ :Eu，Mn、(Ba，Ca，Sr)Al ₂ O ₄ :Eu、 (Ba，Ca，Sr)Al ₂ O ₄ :Eu，Mn、(Ca，Sr)Al ₂ O ₄ Eu, formula Ca _x Si _12-(m+n) Al _(m+n) O _n N _16-n Eu (wherein, 0.3 < x < 1.5, 0.6 < m < 3, and 0. Ltoreq. N < 1.5) and having a luminescence peak at 500nm to 600 nm. In addition, a plurality of the above phosphors can be used.

Among these, from the viewpoint of satisfactorily combining the temperature dependence coefficient, absorbance, internal quantum efficiency, and the like of the phosphor, ca is particularly preferable as an example _2.97 Ce _0.03 Sc ₂ Si ₃ O ₁₂ And the like.

The green phosphor 324 is also generally used in a granular form as in the red phosphor 314, and the particle diameter of the granules is the same as that of the red phosphor 314.

The green phosphor 324 may be present in any state without significantly impairing the effect of the image display device of the present invention, and may be attached to the frame with the binder 328, or may be directly attached to the frame after firing the green phosphor to produce a fired body, or may be attached to the frame after producing glass with the green phosphor, or may be attached to the frame after processing a single crystal of the green phosphor, as in the case of the red phosphor 314.

As with the red phosphor 314, the green phosphor 324 may contain other components.

The green light-emitting device 321 is also manufactured in the same manner as the red light-emitting device 311.

In the present embodiment, the green phosphor 324 used is as described above Ca _2.97 Ce _0.03 Sc ₂ Si ₃ O ₁₂ The green phosphors 324 are held in the recesses 322A of the frame 322 in a state of being dispersed in the binder 328.

The green phosphor 324 used in the present embodiment has a phosphor temperature dependence coefficient, an absorbance, and an internal quantum efficiency within the above-described preferred ranges. The binder 328 can transmit the excitation light emitted from the green pixel light-emitting element 323 and the green light emitted from the green phosphor 324.

[ IV-3. Blue pixels ]

Fig. 14 is a cross-sectional view schematically illustrating an essential part of a blue light-emitting device (blue light-emitting element) 331 of a blue pixel 303 serving as one of non-red pixels according to the present embodiment.

The blue pixel 303 used in this embodiment is not limited, and any light source that emits blue light may be used without significantly impairing the effect of the image display device of the present invention.

In this embodiment, as shown in fig. 14, the blue pixel 303 includes a blue light emitting device 331, the blue light emitting device 331 includes a blue pixel light emitting element 333, and blue light emitted from the blue pixel light emitting element 333 is emitted from the blue pixel 303 as blue light itself.

The peak wavelength of the blue light emitted by the blue pixel 303 can be arbitrarily set according to the use state, purpose, and the like of the color display, but is generally 420nm or more, preferably 440nm or more, and generally 480nm or less, preferably 460nm or less.

The blue light-emitting device 331 included in the blue pixel 303 also generally includes a frame 332 as a base portion for holding the light-emitting element 333 for the blue pixel.

[ IV-3-1. Frame ]

The frame 332 used for the blue light-emitting device 331 is the same as the frame 312 used for the red light-emitting device 311.

In this embodiment, conductive terminals 335 and 336 for supplying power to the blue pixel light emitting element 333 are formed at the bottom of the recessed portion 332A of the cup-shaped frame 332, and the conductive terminals 335 and 336 are connected to an external power supply (not shown).

[ IV-3-2. Light-emitting element for blue pixels ]

The blue pixel light-emitting element 333 emits blue light emitted by the blue pixel 303.

The kind of the blue pixel light-emitting element 333 is not limited, and any light-emitting element that emits blue light can be used, and for example, the same example as the example described as the red pixel light-emitting element 313 can be used. The method for mounting the blue pixel light-emitting element 333 to the frame 332 is also the same as that described for the red pixel light-emitting element 313.

In this embodiment, an (In, ga) N-based LED that emits blue light is used as the blue pixel light-emitting element 333, and the blue pixel light-emitting element 333 is provided at the bottom of the recess 332A of the frame 332. The blue pixel light-emitting element 333 is directly connected to the conductive terminal 335, and is connected to the conductive terminal 336 via a connection wire 337 by a wire connection method, thereby supplying power. Further, the mold 338 is filled with the same adhesive as the adhesives 318 and 328 in the recess 332A, and blue light emitted from the blue pixel light-emitting element 333 is emitted to the outside through the mold 338. Further, the molding 338 preferably contains, for example, tiO ₂ 、BaSO ₄ And the like.

[ IV-4. Relationship between pixels ]

When the emission intensities of the red pixel 301 and the non-red pixels 302 and 303 at 25 ℃ are denoted as I (R, 25) and I (N, 25), respectively, and the emission intensities of the red pixel 301 and the non-red pixels 302 and 303 at 100 ℃ are denoted as I (R, 100) and I (N, 100), respectively, the ratios of I (N, 100)/I (N, 25) to I (R, 100)/I (R, 25) are as follows: this ratio is generally 90% or more, preferably 92% or more, and more preferably 95% or more for any combination of the red pixel 1 and the non-red pixels 302, 303.

Therefore, in the above-described embodiment, when the emission intensities at 25 ℃ of the green pixel 302 and the blue pixel 303 are denoted as I (G, 25) and I (B, 25), respectively, and the emission intensities at 100 ℃ of the green pixel 302 and the blue pixel 303 are denoted as I (G, 100) and I (B, 100), respectively, it is preferable that the ratios of I (G, 100)/I (G, 25) and I (B, 100)/I (B, 25) to I (R, 100)/I (R, 25) are all within the above-described ranges.

This provides an advantage of reducing the change in color tone (color difference) of the element due to a change in temperature.

[ IV-5. Other structures ]

The specific configuration of an image display device such as a color display may be arbitrary if the image display device has the red pixels 301, the green pixels 302, and the blue pixels 303 described above.

For example, as shown in fig. 11, a red light-emitting device 311, a green light-emitting device 321, and a blue light-emitting device 331 each functioning as a red pixel 301, a green pixel 302, and a blue pixel 303 are mounted on a substrate 401, and the red pixel 301, the green pixel 302, and the blue pixel 303 collectively constitute a unit pixel 400 of a color display.

A printed board on which a conductor layer (not shown) is printed is used as the substrate 401. In general, a laminate substrate in which a substrate having a conductor layer formed on the surface of a ceramic substrate called a green sheet is laminated on a printed substrate, a substrate in which a conductor layer is printed on an insulating substrate singly, or the like can be used.

The conductive terminals 315, 316, 325, 326, 335, and 336 of the red light emitting device 311, the green light emitting device 321, and the blue light emitting device 331 are electrically connected to the conductor layer on the surface of the substrate 401.

Further, the time and amount of power supplied to each of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 can be controlled by a control unit (not shown) provided in the color display, whereby the degree of light emission of any one of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 can be controlled.

The red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 are all surrounded by a cover member 402 made of resin, ceramic, or the like. Also, as with frames 312, 322, 332, etc., the inside surface of cover member 402 is preferably made reflective to visible light.

Further, the mold 403 made of resin or the like is injected into the cover member 402, so that the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 can be protected by the mold 403. In addition, a diffusing agent may be dispersed in the mold 403 to uniformly mix red light, green light, and blue light emitted from the red light-emitting devices 311, the green light-emitting devices 321, and the blue light-emitting devices 331.

The color display of the present embodiment includes a large number of unit pixels 400 configured as described above.

[ IV-6. Effect ]

Since the color display of the present embodiment is configured as described above, when displaying an image, the control unit controls the amount of power supplied to each of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 so that light of a desired color can be emitted from the unit pixel 400 at a predetermined position. As a result, red light, green light, and blue light corresponding to a desired image are emitted from the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 included in the unit pixel 400 of the color display, and a desired image can be formed. Accordingly, the observer can see an image formed on the color display by observing the unit pixels 400.

In this case, since the red light-emitting device 311 including the red pixel light-emitting element 313 and the red phosphor 314 having a phosphor temperature-dependent coefficient of 85 or more is used as the red pixel 301, it is possible to suppress a change in color tone of light emitted from the color display due to a temperature change, and to reduce color difference of an image formed on the color display.

In addition, since the ratio of I (N, 100)/I (N, 25) to I (R, 100)/I (R, 25) is increased to be within the above range, there is an advantage that the change in hue (color difference) of the element due to the temperature change can be reduced.

Further, since the (In, ga) N-based light-emitting element is used as the light-emitting element 313 for red pixels, a light-emitting device having high efficiency and small temperature dependence can be obtained.

Further, since the green pixel 302 and the blue pixel 303, which are non-red pixels, have a configuration including an (In, ga) N-based light emitting element, there is an advantage that full color display is possible. In addition, at least one of the non-red pixels may have an (In, ga) N-based light-emitting element, but the above-described advantages can be more reliably obtained when all of the non-red pixels have an (In, ga) N-based light-emitting element.

Further, the blue pixel 303 and the green pixel 302 are provided as non-red pixels, the blue pixel 303 is provided with the blue pixel light emitting element 333, and the green pixel 302 is provided with the green pixel light emitting element 323 and the green phosphor 324 having a phosphor temperature dependence coefficient of 85 or more, so that there is an advantage that a change in color tone (color difference) due to a temperature change of the element can be reduced.

[ IV-7. Others ]

Although one embodiment of the image display device of the present invention has been described above, the image display device of the present invention is not limited to the above-described embodiment, and may be arbitrarily changed in implementation without departing from the scope of the invention.

For example, the image display device of the present invention can be used for a projector type image display device in which light is irradiated from the pixels 301, 302, 303, 400 to a projection surface such as a screen to form an image on the projection surface, in addition to imaging by the pixels 301, 302, 303, 400 themselves.

A projector type color display shown in fig. 15 can be given as a specific example thereof. In fig. 15, the same reference numerals as in fig. 11 to 14 denote the same parts as in fig. 11 to 14. In fig. 15, the dot-dash line and the block arrow indicate light.

In the color display shown in fig. 15, a red light-emitting device 311, a green light-emitting device 321, and a blue light-emitting device 331 similar to those of the above-described embodiments are mounted on a substrate 501 as a red pixel 301, a green pixel 302, and a blue pixel 303, respectively. The substrate 501 is a printed substrate similar to the substrate 401, and the conductive terminals 315, 316, 325, 326, 335, and 336 of the red light emitting device 311, the green light emitting device 321, and the blue light emitting device 331 are electrically connected to a conductive layer (not shown) on the surface of the substrate 501.

Further, the same as the color display of the above embodiment is true in that a control unit (not shown) provided in the color display controls the power supply time and the power supply amount to each of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331, thereby controlling how much light is emitted by any one of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331.

In addition, the front faces of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 are each provided with a light distribution lens 502 as a condensing optical system, correspondingly, and at the further distal ends thereof, a common superimposing lens 503 of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 is provided.

Further, a transmissive LCD504 as a light modulation element, a projection lens 505, and a screen 506 as a projection surface (display surface) are provided at a distal end of the superimposing lens 503, and the projection lens 505 is used to enlarge and project an image formed on the transmissive LDE504 on the screen 506.

In addition, in this color display, the red light emitting device 311, the green light emitting device 321, the blue light emitting device 331, the light distribution lens 502, and the superimposing lens 503 are provided in large numbers in the form of a unit pixel 507.

Therefore, when an image is displayed using this projector type color display, the control unit controls the amount of power supplied to each of the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 so that light of a desired color can be emitted from the unit pixel 507 at a predetermined position. As a result, red light, green light, and blue light corresponding to an image to be formed are emitted from the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 included in the unit pixel 507 of the color display.

The light emitted from the red light emitting device 311, the green light emitting device 321, and the blue light emitting device 331 is extracted by the corresponding light distribution lens 502, and is superimposed on the light modulation element 304 through the superimposing lens 503. Then, the light emitted from the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 is superimposed, and an image is displayed on the transmissive LCD504, and the image is projected on the screen 506 surface in an enlarged manner by the projection lens 505.

According to the image display device of the present invention, the projector type image display device can obtain the same advantages as those of the above embodiments, in addition to the reduction of the color difference of the formed image.

Instead of molding the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 separately from each other, the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 are molded integrally and separately and then arranged regularly, so that the light-emitting devices 311, 321, and 331 forming each pixel can be used as the respective pixels to form the image display device.

Further, the image display device may be configured as a device that combines light emitting devices such as the red light emitting device 311, the green light emitting device 321, and the blue light emitting device 331, for example, which are regularly arranged, and forms a white light source by combining all lights, or a device that controls an image by a mechanism that controls transmittance by liquid crystal or the like and red and non-red color filters.

The image display device may be configured as a device that displays an image by forming and projecting an image of each color using a liquid crystal panel or a mirror deflection type optical modulator (trade name: デヅタルマイクロミラ - デバィス) using, for example, the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331 as their light sources.

The image display device may be configured as a device for displaying character information in color by the light emitting devices 311, 321, and 331 of the respective colors arranged in a matrix.

According to the image display device of the present invention, these various forms of image display devices can obtain the same advantages as described above, in addition to reducing the color difference of the formed image.

In addition, the components described in the above embodiments and the like may be used in any combination.

Further, the frames 312, 322, 332 of the red light-emitting device 311, the green light-emitting device 321, the blue light-emitting device 331, and the like may be integrated with appropriate substrates 401, 501.

The red pixel 301, the green pixel 302, and the blue pixel 303 may each independently include a component other than the red light-emitting device 311, the green light-emitting device 321, and the blue light-emitting device 331.

The red light emitting device 311, the green light emitting device 321, the blue light emitting device 331, and the like may be reflective light emitting devices, and for example, the excitation light may be reflected on the surfaces of the frames 312, 322, and 332 and emitted to the outside.

The present invention can be implemented by combining the components and structures not described above without significantly impairing the effects of the image display device of the present invention.

[ V. description of application example of the image display apparatus described above ]

When attention is paid to the temperature dependence of the phosphor, the image display device of the following embodiment can be realized by applying the above-described image display device.

An image display device according to this application example is an image display device having a light source that emits light having an emission peak in a wavelength range of usually 370nm or more, preferably 380nm or more, more preferably 390nm or more and usually 700nm or less, preferably 500nm or less, more preferably 480nm or less, and a phosphor portion that contains a wavelength conversion material such as a phosphor that absorbs light emitted from the light source and emits visible light and has a luminance maintenance rate at 150 ℃ of 70% or more.

In recent years, flat display devices such as liquid crystal display devices and plasma display devices have rapidly spread. Flat display devices are characterized by being thinner and lighter in weight than conventional CRT (cold cathode tube) displays, and most image display devices are flat in the field of large display devices in particular. Among them, liquid crystal display devices are common.

In addition, in the field of medium-sized display devices, flat-type liquid crystal display devices have been rapidly popularized, and in the flat-type liquid crystal display devices, in particular, have been widely popularized.

However, since the conventional liquid crystal display device limits the passing angle of the backlight, the viewing angle of the light passing therethrough is greatly limited, and the problem of the viewing angle, that is, the lowering or inversion of the black-and-white contrast occurs due to the viewing angle. In order to solve the problem of the visible angle, for example, a pixel division method in which separate pixels have different voltage-transmittance characteristics, a method using an optical compensation plate, or the like is proposed. However, these methods increase the manufacturing cost and the component cost, and prevent the liquid crystal display device from being widely used.

In addition, in order to realize color display, a micro color filter in which color filters are arranged in each pixel of red, green, blue, or the like is used in a conventional image display device. However, the micro color filter is expensive, so that it also hinders the popularization of the liquid crystal display device.

On the other hand, self-luminous display devices typified by CRT displays, plasma display devices, and electroluminescent displays do not have such a problem of a visible angle as occurs in liquid crystal display devices. However, since the CRT display is heavy and large, a large installation place is required. In addition, since a high voltage is required for driving the plasma display device, a special circuit is required, and the plasma display device is expensive. Further, since the plasma display device generates plasma, the size of each pixel cannot be made too small, and it is difficult to achieve high definition particularly for a medium-sized image display device. In addition, electroluminescent displays have problems with environmental resistance and lifetime. Especially for environmental properties, displays are required which can also operate at temperatures of typically 70 ℃ to 80 ℃.

Accordingly, a fluorescent self-luminous liquid crystal display device has been proposed in which a luminance is adjusted by adjusting the amount of transmitted light using an electro-optical element using a liquid crystal having excellent durability and durability, phosphor portions of 3 primary colors are provided in a shape corresponding to each pixel, and a phosphor in the phosphor portions is excited by a backlight having a main light emitting region in a wavelength region of 380nm to 420nm to emit light (japanese unexamined patent application publication nos. 8 to 62602 and 2004 to 348096).

However, when the phosphors described in JP-A-8-62602 and JP-A-2004-348096 are used, the emission intensity in the red region is extremely weak, and therefore, the color reproduction region of the image display device is narrow. When the phosphor is excited by near-ultraviolet light having a main light emitting region in a wavelength region of 380 to 420nm, the resin in the phosphor portion is aged and colored.

On the other hand, U.S. Pat. No. 6844903, japanese patent application laid-open No. H10-207395 and Japanese patent application laid-open No. H8-63119 disclose a technique in which excitation of a phosphor is performed by visible light instead of near ultraviolet light as in Japanese patent application laid-open Nos. H8-62602 and 2004-348096.

However, when a phosphor is excited by visible light as described in U.S. Pat. No. 6844903 and Japanese patent application laid-open No. Hei 10-207395, the temperature dependence of the emission luminance of the phosphor used is large, and the color of light emitted from the phosphor fluctuates, and as a result, the color of the image to be displayed deviates from the color to be emitted depending on the temperature condition.

The present application example can solve the above problems, and according to the present application example, an image display device using a phosphor with reduced temperature dependence of the luminance of light emission can be realized.

Next, the image display device according to the present application example will be described in detail.

The image display device of this application example has a light source that emits light having a light emission peak in a wavelength range of 390nm to 700 nm. The image display device of the present application example includes a phosphor section including a phosphor having a luminance maintenance rate of 70% or more at 150 ℃ (hereinafter referred to as "luminance maintenance phosphor" for convenience) as a phosphor that absorbs light emitted from a light source and emits visible light. In addition, the phosphor (including the luminance maintaining phosphor) is a wavelength conversion material.

[ V-1. Luminance-maintaining phosphor ]

The luminance-maintaining phosphor is not limited, and when the phosphor is excited by excitation light having the same intensity as the luminance maintenance ratio at 150 ℃, any phosphor can be used as long as it can emit visible light if the ratio of the light emission luminance at 150 ℃ to the intensity of the light emission luminance at room temperature (25 ℃) is generally 70% or more, preferably 75% or more, and more preferably 80% or more.

One kind of the luminance-maintaining phosphor may be used alone, or two or more kinds may be used in combination. Further, in the case where two or more kinds of luminance maintaining phosphors are used in combination, the luminance maintaining phosphors may be contained in the same phosphor section, or may be contained in different phosphor sections.

As the luminance maintaining phosphor, for example, the red phosphor or the green phosphor used in the first light emitting device of the present invention can be used, but not limited thereto. Further, as the above-mentioned luminance maintaining phosphor, caAlSiN, for example, can be suitably used ₃ Eu or Ca ₃ Sc ₂ Si ₃ O ₁₂ :Ce。

[CaAlSiN ₃ :Eu]

First, caAlSiN suitable for use as a luminance maintaining phosphor in the image display device of the present application example ₃ Eu will be described.

CaAlSiN ₃ Eu is a phosphor emitting red fluorescence.

CaAlSiN ₃ The wavelength range of excitation light that can be used for excitation of Eu is 350nm to 500nm.

In addition, caAlSiN ₃ The wavelength range of the luminescence peak of the fluorescence emitted by Eu is 550 nm-700 nm.

In addition, caAlSiN at room temperature (25 ℃ C.) ₃ Eu has an internal quantum efficiency of usually 50% or more. Here, the internal quantum efficiency is a parameter represented by the following formula (iv).

Internal quantum efficiency (%) =

{ (Total PhotoQuantum number of luminescence)/(Total PhotoQuantum number of absorption) } × 100 (iv)

In addition, caAlSiN ₃ The temperature dependence of the emission luminance of Eu is low. In particular, even temperatureWhen the temperature changes and returns to the original temperature state, the light can be emitted at the same luminance as before the temperature change. For example, when the temperature is increased from room temperature to 150 ℃, the amount of change in the emission luminance is small, and the luminance after heating is performedWhen the temperature is again cooled to room temperature, the emission luminance is not lowered as compared with that before heating. CaAlSiN, if specific properties are mentioned ₃ Eu has a luminance maintenance ratio at 150 ℃ that is preferable for a luminance maintenance phosphor. Therefore, caAlSiN ₃ Eu is suitable for use in the image display device of the present application example.

[Ca ₃ Sc ₂ Si ₃ O ₁₂ :Ce]

Next, ca suitable as a luminance maintaining phosphor in the image display device of the present application example ₃ Sc ₂ Si ₃ O ₁₂ Ce.

Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce is a phosphor emitting green fluorescence.

Ca ₃ Sc ₂ Si ₃ O ₁₂ The wavelength range of the excitation light that can be used for the excitation of Ce is 350nm to 500nm.

In addition, ca ₃ Sc ₂ Si ₃ O ₁₂ The wavelength range of the luminescence peak of fluorescence emitted by Ce is 470 nm-550 nm.

Further, ca at room temperature (25 ℃ C.) ₃ Sc ₂ Si ₃ O ₁₂ The internal quantum efficiency of Ce is usually 60% or more.

The Ca ₃ Sc ₂ Si ₃ O ₁₂ That is, ce has low temperature dependence of emission luminance. More specifically, even if the temperature condition changes, the luminance is not likely to change, and when the temperature changes and returns to the original temperature state, the light can be emitted at the same luminance as before the temperature change. For example, with CaAlSiN ₃ Eu likewise, in the case of heating from room temperature to 150 ℃The amount of change in the emission luminance is small, and when the substrate is cooled again to room temperature after heating, the emission luminance is not reduced as compared with that before heating. Ca if specific properties are mentioned ₃ Sc ₂ Si ₃ O ₁₂ Ce has a luminance maintenance ratio at 150 ℃ which is preferable for the phosphor. Therefore, ca ₃ Sc ₂ Si ₃ O ₁₂ Ce is also suitable for the image display device of the present application example.

[ V-2. Embodiment ]

The present application example will be described in detail below with reference to embodiments, but the present application example is not limited to the following embodiments.

[ V-2-1. First embodiment ]

Fig. 16 is an exploded sectional view schematically illustrating a main part of the image display device according to the first embodiment of the present application example. For example, the image display device shown in fig. 16 is an image display device when an observer views an image displayed by the image display device from the right side in the figure.

As shown in fig. 16, the image display device 601 of the present embodiment includes a light source 602, a phosphor portion (first phosphor portion) 603R and a phosphor portion (second phosphor portion) 603G each including a phosphor that absorbs light emitted from the light source 602 and emits visible light, and a light transmission portion 603B that transmits light emitted from the light source 602 to the front.

The components are explained below.

[ V-2-1-1. Frame ]

The frame 604 is a base portion for holding components such as the light source 602 constituting the image display device 601, and its shape is arbitrary.

The material of the frame 604 is also arbitrary, and for example, an inorganic material such as metal, alloy, glass, or carbon; organic materials such as synthetic resins, and the like.

However, from the viewpoint of improving the light emission efficiency of image display device 601 by effectively using the light emitted from light source 602, it is preferable to increase the reflectance of the surface of frame 604 to which the light emitted from light source 602 is applied to the incident light. Therefore, at least the surface to which light is irradiated is formed of a material having a high reflectance. Specific examples thereof include forming the entire frame 604 or the surface of the frame 604 with a material (injection molding resin or the like) containing a substance having a high reflectance such as glass fiber, alumina powder, titanium dioxide powder, or the like.

The specific method of increasing the reflectance of the surface of the frame 604 is arbitrary, and the reflectance of light may be increased by plating or vapor deposition treatment with a metal and/or alloy having a high reflectance such as silver, platinum, or aluminum, in addition to the above-described selection of the material of the frame 604 itself.

The portion for increasing the reflectance may be the entire frame 604 or a part thereof, and it is generally preferable to increase the reflectance of the entire surface of the portion irradiated with light emitted from the light source 602.

In addition, electrodes, terminals, and the like for supplying power to the light source 602 are typically provided at block 604. In this case, the electrodes and/or terminals may be connected to the light source 602 by any method, and the light source 602 may be connected to the electrodes and/or terminals by a wire connection method, for example, to supply power. The connecting wire used is not limited, and the material, size, and the like thereof are arbitrary. For example, a metal such as gold or aluminum may be used as a material of the connection line, and the thickness of the connection line may be controlled to be generally 20 μm to 40 μm, but the connection line is not limited thereto.

Another method for supplying power to the light source 602 is to supply power to the light source 602 by flip chip mounting using bumps.

In the case of supplying power to the light source 602, solder may be used. This is because the solder has excellent heat dissipation properties, and therefore, when a large-current light emitting diode (i.e., "LED") or a laser diode (i.e., "LD") or the like, which is important for heat dissipation properties, is used as the light source 602, the heat dissipation properties of the image display device 601 can be improved by using the solder. The type of solder is arbitrary, and AuSn, agSn, or the like can be used, for example.

In addition, solder may be used to simply provide the light source 602 to the frame 604, in addition to connecting electrodes or terminals in a path for power supply.

When the light source 602 is mounted on the frame 604 by a substance other than solder, an adhesive such as epoxy resin, imide resin, or acrylic resin may be used. In this case, a paste-like substance formed by mixing a conductive filler such as silver particles or carbon particles with a binder can supply power to the light source 602 by applying current to the binder, as in the case of using solder. Further, mixing these conductive fillers is preferable because heat dissipation can be improved.

In this embodiment, a flat frame 604 having a high surface reflectance is used, and a terminal (not shown) for supplying power to the light source 602 is provided on the surface.

Power is supplied to the terminal from a power source (not shown).

[ V-2-1-2. Light Source ]

The light source 602 emits excitation light that excites phosphors contained in the phosphor portions 603r, 603g. In the present embodiment, light emitted from the light source 602 is emitted to the outside of the image display device 601 through the light transmission section 603B so as to be visible to the observer of the image display device 601. That is, the light emitted from the light source 602 is the light itself emitted by the pixel.

The light emitted from the light source 602 is such that the light can excite the phosphor CaAlSiN ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ The visible light region of Ce may have a light emission wavelength.

Specifically, the light emitted from the light source 602 has a light emission peak in a wavelength range of usually 390nm or more, preferably 440nm or more, and usually 700nm or less, preferably 500nm or less. This is because, when the liquid crystal grating is used as the image display device 601 at a lower limit of the range, the liquid crystal substance itself may be destroyed by the light (in this case, ultraviolet rays) emitted from the light source 602. On the other hand, if the wavelength is out of the upper limit of the above range, the emission efficiency of the phosphor is lowered, and the luminance of the pixel may be lowered or the color reproduction range may be narrowed, which is not preferable.

In addition, when the light source 602 has two or more emission peaks, the emission peak is within the above rangeIt is sufficient to have at least one peak. That is, in the above wavelength range, caAlSiN has a property of exciting ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ The peak of the phosphor of at least one of Ce may be included.

The light source 602 may use any element that emits light in the above-described wavelength range for exciting the phosphors contained in the phosphor portions 603r,603g by electric energy. Examples of the light source 602 include lamps such as a halogen lamp, a mercury lamp, a hydrogen discharge tube, a neon lamp, a xenon lamp, a low-pressure sodium lamp, and a fluorescent lamp (a cold cathode tube, a hot cathode tube, or the like); inorganic semiconductor LEDs and other LEDs; electroluminescent light sources such as organic EL devices. Among them, an LED and a fluorescent lamp are generally preferable.

In particular, a fluorescent lamp in which a phosphor emits light by ultraviolet light generated by low-pressure discharge of mercury is particularly preferable because a variety of wavelength spectra can be obtained by selecting a phosphor, and thus the fluorescent lamp has a large degree of freedom, consumes less power, and has a small volume. In addition, as the fluorescent lamp, a cold cathode tube or a hot cathode tube conventionally used can be used, and when white light is used, other color light is mixed in blue, green, and red light emitting regions, and therefore, it is preferable to extract only a blue region in the white light by using a color filter or the like. Among them, it is particularly preferable to use a fluorescent lamp coated with only a blue phosphor, which is effective for reducing power consumption.

On the other hand, in the case of LEDs, blue or white inorganic semiconductor LEDs having high luminance have recently been available, and therefore, these light sources may be used. In particular, the blue light emitting inorganic semiconductor LED can selectively emit light in a wavelength region which is preferable in this application example, and therefore, the blue light emitting inorganic semiconductor LED is suitably used.

The light sources 602 such as LEDs and fluorescent lamps are preferably arranged in an array. That is, the light sources 602 are preferably arranged in rows and columns as a whole, and each can individually specify an area on which an image can be formed. Thus, the phosphor portions 603r,603g and the light transmission portion 603B can be arranged in an array, and a full-color image suitable for the image display device 601 can be formed.

In addition, in the case where light is irradiated from the light source 602 to the phosphor portions 603r,603g or the light transmissive portion 603B, light may also be directly incident to the phosphor portions 603r,603g or the light transmissive portion 603B, and a reflection plate may be further provided, which is emitted first and then incident to the phosphor portions 603r,603g or the light transmissive portion 603B. Further, by using the frame 604 having a high reflectance and providing a reflecting plate on the back surface (the side opposite to the observer) of the light source 602, the utilization efficiency of the light emitted from the light source 602 can be improved.

In addition, there is no limitation on the size of the light source 602.

When the light source 602 is provided in the frame 604, the method of providing the light source is not limited, and any known method may be used. Therefore, as described above, the light source 602 may be disposed to the frame 604 using, for example, solder or the like.

In this embodiment, an LED (light emitting element) that emits blue light as the light source 602 is provided in each of the phosphor portions 603r,603g and the light transmission portion 603B, and CaA1SiN contained in the phosphor portions 603r,603g is excited by the light emitted from the light source 602 ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce and the like. Further, a part of the light emitted from the light source 602 is transmitted through the light transmitting section 603B, and is seen as light of a blue pixel by an observer. When power is supplied to the light source 602, power is supplied by electrically connecting terminals on the frame 604 to electrodes of the light source 602 using a circuit, a connecting wire, or the like connected to each other. The amount of power supplied to each of the light sources 602 is controlled by a control unit, not shown, in accordance with an image to be displayed.

[ V-2-1-3. Phosphor portion and light transmission portion ]

The phosphor portions 603r,603g are portions containing phosphors that absorb excitation light emitted from the light source 602 and in turn emit visible light for forming an image displayed by the image display apparatus 601. In this application example, at least one of the phosphor portions 603R and 603G contains a luminance maintaining phosphor (e.g., caAlSiN ₃ :Eu、Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce) as a phosphor. Further, the phosphor portions 603r,603g are generally provided one by one for the pixels, and the pixels that realize the image display apparatus 601 generate light to emit it.

Further, similarly to the phosphor portions 603r,603g, the light transmitting portion 603B is provided for each pixel, and is a portion which transmits light of the light source 602 forward so as to use the light as a part of the light of the pixel. The light transmitting portion 603B is generally provided similarly to the phosphor portions 603r,603g except that it does not contain a phosphor.

Therefore, in this embodiment, the observer sees the fluorescence emitted from the phosphor portions 603r and 603g and the light emitted from the light source 602 emitted after passing through the light transmission portion 603B, and recognizes an image.

(i. Phosphor section)

In this embodiment, the phosphor portion 603R is formed to emit red fluorescence corresponding to a red pixel, and contains CaAlSiN ₃ Eu is used as the luminance maintaining phosphor.

On the other hand, the phosphor portion 603G is formed to emit green fluorescence corresponding to a green pixel, and contains Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce is used as a luminance-maintaining phosphor.

By incorporating the fluorescent portion with the CaAlSiN fluorescent material having low temperature dependence of the emission luminance ₃ Eu and/or Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce, which can suppress the temperature dependency of the image display device 601 itself and prevent the color of the image displayed under different temperature conditions from the target colorA deviation occurs.

In addition, the CaAlSiN may be used in combination ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ A phosphor other than the Ce phosphor is maintained in luminance, and the phosphor parts 603R and 603G contain appropriate phosphors for use (hereinafter referred to as "common phosphors" for convenience).

The phosphor used in combination is not limited, and is arbitrary as long as the effect of the present application example is not significantly impaired. Depending on the application, the emission color of the combined phosphors is not limited to a specific color, and for example, when a full-color display is manufactured, it is preferable to use blue, green, and red emitters having high color purity. The appropriate color can be expressed by more than one method, and it is simple to use the emission peak wavelength of the emission or the CIE chromaticity coordinates. In the case where the light wavelength conversion mechanism is a monochrome display or a multicolor display, it is preferable to include a phosphor that emits violet, blue-violet, yellow-green, yellow, or orange light. Further, when two or more kinds of phosphors are mixed and used in the phosphor portion 603r,603g in combination with a common phosphor, light emission with high color purity or light emission with an intermediate color or white color can be performed.

The emission peak wavelength of the light emitted from the composite phosphor is, for example, a specific wavelength range of the fluorescence emitted from the composite phosphor emitting red fluorescence, and the emission peak wavelength is usually 370nm or more, preferably 380nm or more, and usually 500nm or less, preferably 480nm or less.

For example, when a specific wavelength range of fluorescence emitted from a combined phosphor emitting green fluorescence is mentioned, the emission peak wavelength is usually 490nm or more, preferably 500nm or more, and usually 570nm or less, preferably 550nm or less.

Further, for example, in the specific wavelength range of the fluorescence emitted from the combined fluorescent material emitting blue fluorescence, the emission peak wavelength is usually 420nm or more, preferably 440nm or more, and usually 480nm or less, preferably 470nm or less.

The composition of the fluorescent material for alignment is not particularly limited, but is preferably Y as a crystal mother material ₂ O ₃ 、Zn ₂ SiO ₄ Metal oxides typified by Ca, etc ₅ (PO ₄ ) ₃ Phosphates represented by Cl or the like and sulfides represented by ZnS, srS, caS or the like are combined with ions of rare earth metals such as Ce, pr, nd, pm, sm, eu, gd, tb, dy, ho, er, tm, yb or the like, or Ag, or Yb, Ions of metals such as Al, mn, sb, etc. as an activator or co-activator.

Preferred examples of the crystal matrix include ZnS and Y ₂ O ₂ S、 (Y，Gd) ₃ Al ₅ O ₁₂ 、YAlO ₃ 、BaAl ₂ Si ₂ O ₈ 、Y ₃ Al ₅ O ₁₂ 、Y ₂ SiO ₅ 、Zn ₂ SiO ₄ 、Y ₂ O ₃ 、 BaMgAl ₁₀ O ₁₇ 、BaAl ₁₂ O ₁₉ 、(Ba，Sr，Mg)O·αAl ₂ O ₃ 、(Y，Gd)BO ₃ 、Y ₂ O ₃ 、 (Zn，Cd)S、SrGa ₂ S ₄ 、SrS、SnO ₂ 、Ca ₁₀ (PO ₄ ) ₆ (F，Cl) ₂ 、(Ba，Sr)(Mg，Mn)Al ₁₀ O ₁₇ 、 (Sr，Ca，Ba，Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ 、(La，Ce)PO ₄ 、CeMgAl ₁₁ O ₁₉ 、GdMgB ₅ O ₁₀ 、Sr ₂ P ₂ O ₇ 、 Sr ₄ Al ₁₄ O ₂₅ 、(Ba，Sr，Ca)(Mg，Zn，Mn)Al ₁₀ O ₁₇ And the like.

The above-mentioned crystal matrix and the activator or co-activator are not particularly limited in terms of the element composition, and it is preferable that a part of the elements is replaced with the same group element, and the phosphor obtained absorbs light emitted from the light source 602 and emits visible light. Examples of usable phosphors are given below. However, the phosphor used in the image display device 601 of the present embodiment is not limited to the following example.

Red phosphor used in combination:

in the present embodiment, examples of the red phosphor for red light emission that can be used in combination include (Mg, ca, sr, ba) ₂ Si ₅ N ₈ Europium-activated alkaline earth silicon nitride phosphors expressed by Eu, which are composed of fractured particles having red fracture surfaces and emit light in a red region; with (Y, la, gd, lu) ₂ O ₂ A europium-activated rare earth oxysulfide (oxysulfide, オキシカルュゲナイト) phosphor represented by Eu, which is composed of a growing particle having a substantially spherical shape as a regular crystal growth shape and emits light in a red region; and so on.

In addition, the phosphor described in japanese unexamined patent application publication No. 2004-300247, which is an oxynitride and/or oxysulfide phosphor containing at least one element selected from the group consisting of Ti, zr, hf, nb, ta, W and Mo, and which contains an oxynitride having an α sialon structure in which a part or all of the Al element is substituted by Ga element, can also be used as a combined phosphor in the present embodiment. These phosphors contain oxynitride and/or oxysulfide.

Further, as a phosphor for red color, Y may be used ₂ O ₂ S:Eu ³⁺ 、 (BaMg) ₂ SiO ₄ :Eu ³⁺ 、(BaCaMg) ₅ (PO ₄ ) ₃ Cl:Eu ³⁺ 、YVO ₄ :Eu ³⁺ 、CaS:Eu ³⁺ 、 YAlO ₃ :Eu ³⁺ 、Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ :Eu ³⁺ 、LiY ₉ (SiO ₄ ) ₆ O ₂ :Eu ³⁺ 、(Y，Gd) ₃ Al ₅ O ₁₂ :Ce ³⁺ 、 (Ca，Sr) ₂ Si ₅ N ₈ :Eu、CaSiN ₂ :Eu、(Sr，Ca，Ba，Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ :Eu，Mn、 (Ba ₃ Mg)Si ₂ O ₈ Eu, mn, etc.

Green phosphor used in combination:

examples of the green-emitting phosphor suitable for use in the present embodiment include green-emitting phosphors composed of fractured particles having fracture surfaces and emitting light in the green region, and green-emitting phosphors composed of (Mg, ca, sr, ba) Si ₂ O ₂ N ₂ Europium-activated alkaline earth silicon oxynitride-based phosphor expressed by Eu, and a phosphor (Ba, ca, sr) composed of fractured particles having fracture surfaces and emitting light in the green region ₂ SiO ₄ Eu represents an europium-activated alkaline earth magnesium silicate phosphor.

Further, baMgAl can be used as a green phosphor for general use ₁₀ O ₁₇ :Eu ²⁺ ，Mn ²⁺ 、 Sr ₄ Al ₁₄ O ₂₅ :Eu ²⁺ 、(SrBa)Al ₂ Si ₂ O ₈ :Eu ²⁺ 、(BaMg) ₂ SiO ₄ :Eu ²⁺ 、Y ₂ SiO ₅ :Ce ³⁺ ， Tb ³⁺ 、Sr ₂ P ₂ O ₇ -Sr ₂ B ₂ O ₅ :Eu ²⁺ 、(BaCaMg) ₁₀ (PO ₄ ) ₆ Cl:Eu ²⁺ 、 Sr ₂ Si ₃ O ₈ -2SrCl ₂ :Eu ²⁺ 、Zr ₂ SiO ₄ ，MgA _l1 1O ₁₉ :Ce ³⁺ ，Tb ³⁺ 、Ba ₂ SiO ₄ :Eu ²⁺ 、 Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ :Tb ³⁺ 、Y ₃ Al ₅ O ₁₂ :Tb ³⁺ 、La ₃ Ga ₅ SiO ₁₄ :Tb ³⁺ 、SrGa ₂ S ₄ :Eu ²⁺ ， Tb ³⁺ ，Sm ²⁺ 、Y ₃ (Al，Ga) ₅ O ₁₂ :Ce、SrSi ₂ O ₂ N ₂ :Eu、BaMgAl ₁₀ O ₁₇ :Eu，Mn、 SrAl ₂ O ₄ Eu, etc.

The above-mentioned phosphors for use in combination may be used singly, or two or more kinds may be used in combination and ratio as desired.

However, in the case of using the combined phosphors, the ratio of the amount of the luminance maintaining phosphor to the amount of the entire phosphors is preferably large, and it is more preferable that the entire phosphors are luminance maintaining phosphors, from the viewpoint of reliably obtaining the effects of the present application example.

Further, in order to protect the phosphors from external force, moisture, or the like from the external environment, a binder is generally used for the phosphor portions 603r and 603g. Specifically, the phosphor portions 603r,603g are formed by using a molded body in which a phosphor is dispersed in a binder.

The binder used in the present embodiment is not limited, and any binder may be used without significantly impairing the effects of the present application example, but it is generally preferable to use a colorless and transparent material so as to sufficiently transmit fluorescence and excitation light.

In addition, one kind of the binder may be used alone, or two or more kinds may be used in any combination and ratio.

Among them, generally, a non-aromatic epoxy resin is preferably used. This is because the non-aromatic epoxy resin is excellent in high light resistance and transparency. Particularly, a non-aromatic epoxy resin which can control the inorganic chlorine content to 1ppm or less and the organic chlorine content to 5ppm or less is preferable. Particularly, a non-aromatic epoxy resin produced by distillation and containing no chlorine component at all is more preferable. In the present embodiment, ppm represents a proportion based on weight.

Specific examples of the preferable non-aromatic epoxy resin include alicyclic epoxy resins represented by 3,4 epoxy cyclohexylmethyl-3 ',4' epoxy cyclohexylcarboxylic acid ester; epoxy resins mainly composed of alicyclic epoxy resins and composed of epichlorohydrin and cyclohexane derivatives such as hexahydrophthalic acid diglycidyl ester and hydrogenated bisphenol a diglycidyl ether; liquid or solid epoxy resins composed of bisphenol a diglycidyl ether; and nitrogen-containing epoxy resins such as triglycidyl isocyanurate.

When a non-aromatic epoxy resin is used as the binder, the following curing agent, catalyst aid, and curing accelerator may be appropriately mixed.

The curing agent is used to cure the non-aromatic epoxy resin. The curing agent may be preferably an acid anhydride. Since the material in the binder is required to have light resistance, anhydrides of non-aromatic polycarboxylic acids which do not have a carbon-carbon double bond chemically are preferable. Specific examples thereof include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, and hydrogenated methyl nadic anhydride. Among them, methylhexahydrophthalic anhydride is preferred because of its good balance between curing reactivity and moisture resistance.

The curing agent may be used alone or in combination of two or more kinds at any ratio.

The amount of the curing agent is not limited, and is usually 50 parts by weight or more, preferably 80 parts by weight or more, and usually 150 parts by weight or less, preferably 130 parts by weight or less, based on 100 parts by weight of the non-aromatic epoxy resin.

The catalyst aid is used to impart flexibility to a cured product of a non-aromatic epoxy resin (including the phosphor portions 603R,603G and the light transmitting portion 603B. The same applies hereinafter) and to improve the peel adhesion. Among the catalyst assistants, alcohol-polyol is a preferred catalyst assistant because it can also function as a compatibilizing agent for the curing accelerator. Since the materials in the binder are required to have light resistance, among the alcohol-polyols, it is preferable to use a non-aromatic alcohol-polyol having any one of a linear type, a branched type, an alicyclic type and an ether group-containing type, which have no carbon-carbon double bond in the chemical structure and have 2 to 12 carbon atoms. Specifically, propanol, isopropanol, methylcyclohexanol, ethylene glycol, glycerin, trimethylolpropane, ethylene glycol monomethyl ether, and the like can be mentioned. Among them, low molecular weight diols such as ethylene glycol are preferable.

In addition, the catalyst promoter may be used alone, or two or more thereof may be used in any combination and ratio.

Further, as described above, the alcohol-polyol can also function as a compatibilizer for the curing accelerator, and therefore, it is influenced by the chemical structure and the amount of the curing accelerator added.

The amount of the catalyst promoter to be used is not limited, but is usually not less than 1 part by weight, preferably not less than 5 parts by weight, and usually not more than 30 parts by weight, preferably not more than 15 parts by weight, based on 100 parts by weight of the non-aromatic epoxy resin.

In addition, the curing accelerator is used to accelerate curing of the non-aromatic epoxy resin. Examples of the solidification accelerator include:

[ 1 ] tertiary amines or imidazoles and/or their organic carboxylic acid salts,

[ 2 ] phosphines and/or their quaternary salts,

[ 3 ] a metal salt of an organic carboxylic acid,

[ 4 ] a metal-organic chelate compound,

And [ 5 ] aromatic sulfonium salts.

The curing accelerator may be used alone, or two or more of them may be used in any combination and ratio.

The curing accelerators mentioned above are described below.

[ 1 ] tertiary amines or imidazoles and/or their organic carboxylic acid salts:

examples of the tertiary amine or imidazole and/or organic carboxylic acid salt thereof include 2,4,6-tris (diaminomethyl) phenol, 2-ethyl-4-methylimidazole, 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as "DBU" for convenience), octanoate salts thereof, and the like. Among them, DBU octoate is preferable because the light transmittance of a cured product of a non-aromatic epoxy resin can be improved.

In the case of using a tertiary amine, an imidazole and/or an organic carboxylate thereof as the curing accelerator, the amount of the curing accelerator is not limited, but is usually 0.01 parts by weight or more, preferably 0.1 parts by weight or more, and usually 1 part by weight or less, preferably 0.5 parts by weight or less, based on 100 parts by weight of the non-aromatic epoxy resin, from the viewpoint of moisture resistance of the image display device 601.

[ 2 ] phosphines and/or their quaternary salts:

examples of the phosphine and/or quaternary salt thereof include triphenylphosphine, tributylphosphine, benzyltriphenylphosphonium bromide, benzyltributylphosphonium bromide, and the like. Among them, benzyltriphenylphosphonium bromide is preferable because the light transmittance of a cured product of a non-aromatic epoxy resin can be improved.

In the case of using a phosphine and/or a quaternary salt thereof as the curing accelerator, the amount of the curing accelerator is not limited, but is usually not less than 0.01 part by weight, preferably not less than 0.1 part by weight, and usually not more than 1 part by weight, preferably not more than 0.5 part by weight based on 100 parts by weight of the non-aromatic epoxy resin from the viewpoint of moisture resistance characteristics of the image display device 1.

[ 3 ] organic carboxylic acid metal salt:

examples of the organic carboxylic acid metal salt include zinc octylate, zinc laurate, zinc stearate, and tin octylate which do not have a carbon-carbon double bond having poor light resistance. In addition, the solubility of the metal salt of an organic carboxylic acid in the non-aromatic epoxy resin decreases in proportion to the increase in the number of carbon atoms of the organic carboxylic acid component. However, zinc octoate has the largest range in terms of the addition amount, and it is liquid, so no time is required for dispersion and dissolution. Therefore, zinc octoate is particularly preferable among the organic carboxylic acid metal salts from the viewpoint of curability.

In the case of using the metal salt of an organic carboxylic acid as the curing accelerator, the amount of the curing accelerator is not limited, and is usually 1 part by weight or more, and usually 10 parts by weight or less, and preferably 5 parts by weight or less, based on 100 parts by weight of the non-aromatic epoxy resin, from the viewpoint of improving the light transmittance of the cured product of the non-aromatic epoxy resin.

[ 4 ] metal-organic chelate compounds:

examples of the metal-organic chelate compound include zinc acetylacetonate, zinc benzoylacetonate, zinc dibenzoylmethane, and zinc ethylacetoacetate, which are composed of zinc and a β -diketone and do not affect transparency. Among them, when a zinc chelate compound is used, excellent light resistance and heat resistance can be imparted to the non-aromatic epoxy resin. Further, since the zinc chelate compound has an action of selectively and gently accelerating the curing of the non-aromatic epoxy resin, the low-stress adhesion can be achieved even when the low-molecular-weight monomer such as the alicyclic epoxy resin is mainly used.

In addition, among the zinc chelates, zinc (2) [ Zn (C) is preferably bis (acetylacetone) hydrate [ containing acetylacetone as a chelating agent component ], from the viewpoint of ease of handling and the like ₅ H ₇ O ₂ ) ₂ (H ₂ O)]。

In the case of using a metal-organic chelate compound as the curing accelerator, the amount of the curing accelerator is not limited, and is usually not less than 1 part by weight, but usually not more than 10 parts by weight, preferably not more than 5 parts by weight based on 100 parts by weight of the non-aromatic epoxy resin from the viewpoint of solubility in the non-aromatic epoxy resin.

[ 5 ] aromatic sulfonium salt:

the aromatic sulfonium salt is generally used in a case where the non-aromatic epoxy resin contains no acid anhydride as a curing agent and has a single composition.

When an aromatic sulfonium salt is used, the aromatic sulfonium salt is decomposed by heat and/or ultraviolet light of 360nm or less to generate cations, whereby a non-aromatic epoxy resin cation-polymerized cured product can be obtained. The cured product obtained is crosslinked with ether, and therefore is more stable than a cured product obtained by curing with a curing agent in both physical and chemical aspects.

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluoroantimonate and triphenylsulfonium hexafluorophosphate. Among them, triphenylsulfonium hexafluoroantimonate is preferable because the curing speed is high and sufficient curing can be carried out by adding a small amount.

In the case of using the aromatic sulfonium salt as the curing accelerator, the amount of the curing accelerator is not limited, and the curing accelerator is usually 0.01 parts by weight or more, preferably 0.05 parts by weight or more, and usually 0.5 parts by weight or less, preferably 0.3 parts by weight or less, based on 100 parts by weight of the non-aromatic epoxy resin, from the viewpoint of preventing discoloration of a cured product of the non-aromatic epoxy resin due to chain polymerization heat generation.

Further, a binder other than the above-mentioned non-aromatic epoxy resin may be used. Examples of the binder include polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose polystyrene, a styrene-maleic anhydride copolymer, a styrene-acrylonitrile copolymer, polyvinyl chloride, cellulose acetate butyrate, cellulose propionate, poly α -naphthyl methacrylate, polyvinyl naphthalene, poly n-butyl methacrylate, a tetrafluoroethylene-hexafluoropropylene copolymer, polycyclohexyl methacrylate, poly (4-methylpentene), epoxy, polysulfone, polyether ketone, polyacrylate, polyimide, polyetherimide, cyclic olefin polymer, polysiloxane, benzocyclobutane polymer, water glass, silicon oxide, titanium dioxide, and epoxy resin.

In addition, in the phosphor portion 603r,603g, the proportion of the binder in the phosphor portion 603r,603g is arbitrary without significantly impairing the effect of the present application example, but is usually 5% by weight or more, preferably 10% by weight or more, and is usually 95% by weight or less, preferably 90% by weight or less.

Further, in connection with this, in the phosphor portion 603R,603G, fluorescence is presentPhosphor (i.e., caAlSiN) ₃ :Eu、Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce, a combined phosphor, etc.) and a binder in a proportion of usually 5% by weight or more, preferably 10% by weight or more, and usually 95% by weight or less, preferably 90% by weight or less, based on the total weight of the phosphor and the binder. When the ratio of the binder is less than the lower limit of the range, the luminance may be reduced, and when the ratio of the binder is more than the upper limit, the phosphor portions 603r,603g may become brittle, and the mechanical strength may not be ensured. When two or more kinds of phosphors are used for one phosphor portion, the total amount of the phosphors used is preferably within the above range.

The phosphor portions 603r,603g may contain a binder and an additive other than a phosphor. As the additive, in addition to the above-mentioned curing agent, catalyst promoter, and curing accelerator, for example, a diffusing agent may be contained to further increase the visibility. Specific examples of the diffusing agent include barium titanate, titanium dioxide, alumina, and silica. In addition, for example, for the purpose of cutting off wavelengths other than those required, organic and/or inorganic coloring dyes and/or coloring pigments may also be contained as additive materials. These additives may be used singly or in combination of two or more kinds at any combination and ratio.

Further, the phosphor portion 603r,603g can be manufactured by any known method. For example, a mixture (coating liquid) containing a binder, a phosphor, and a solvent may be formed into a mosaic shape, an array shape, or a stripe shape on the transparent substrate 631 at intervals corresponding to pixels by a screen printing method to fabricate phosphor portions 603r,603g.

Further, between the phosphor portions 603r,603g, a black matrix layer 632 may be formed to absorb external light. The black matrix layer 632 may be formed on a transparent substrate 631 such as glass by a process of forming a light absorbing film made of carbon black using the principle of photosensitivity of a photosensitive resin, or may be formed by laminating a mixture containing a resin, carbon black and a solvent thereon by a screen printing method.

In addition, the shape of the phosphor portions 603r,603g is arbitrary. For example, in the case where the image display device 601 performs multicolor display, phosphors that emit light of a predetermined color are arranged in a light emitting region of the phosphor parts 603r,603g and the like in accordance with the pixel shape, and the shapes of the phosphor parts 603r,603g include a segment shape and a matrix shape necessary for information display, and among the matrix shapes, a stripe structure, a delta structure, and the like are preferable. In the case of monochrome display, the phosphor portions 603r and 603g can be formed by uniformly applying phosphors in addition to the above-described shapes.

In addition, the size of the phosphor portion 603r,603g is also arbitrary. For example, the thickness is arbitrary without significantly impairing the effects of the present application example, but it can be preferably used when it is controlled to 1cm or less in general. In addition, for a flat panel display which is required to be thin and light, the thickness is more preferably controlled to 2mm or less. Considering the balance with the emission rate of the emitted light, the thickness is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and is usually 1000 μm or less, preferably 500 μm or less, more preferably 200 μm or less.

(ii. Light transmission part)

In the present embodiment, the light transmission portion 603B is a member that allows light emitted from the light source 602 to transmit forward corresponding to a blue pixel. Thus, the light source 602 of the image display device 601 emits visible light of blue light, and therefore the visible light emitted from the light source 602 is used as light emitted from the pixel.

The light transmission section 603B is not limited in its structure and may be constructed arbitrarily, and is generally constructed similarly to the phosphor sections 603r and 603g except that it does not contain a phosphor. Therefore, the light transmitting section 603B does not need to contain a phosphor that emits fluorescence of the same color as that of light corresponding to the visible light.

That is, when visible light emitted from the light source 602 is emitted to the outside of the image display apparatus 601, it is not necessary to use fluorescence in all pixels. However, in order to efficiently emit or scatter the visible light emitted from the light source 602 to the outside or to cut off light having a wavelength other than that required, it is preferable that the visible light emitted from the light source 602 is transmitted through the light transmitting portion 603B containing an additive in the adhesive.

The light transmitting portion 603B may contain a dye or a pigment for adjusting color.

In the present embodiment, the red fluorescent portion 603R uses a luminance-maintaining phosphor CaAlSiN ₃ Eu is used as the red phosphor, a non-aromatic epoxy resin is used as a binder, and the red phosphor is dispersed in the binder and formed on the transparent substrate 631. Further, a plurality of phosphor portions 603R are provided corresponding to red pixels.

In the present embodiment, the green fluorescent section 603G uses a luminance-maintaining phosphor Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce is a green phosphor, a non-aromatic epoxy resin is used as a binder, the green phosphor is dispersed in the binder and formed on the transparent substrate 631, and a plurality of such phosphor sections 603G are provided corresponding to the pixels of green.

In the present embodiment, the light transmitting sections 603B are formed by using a non-aromatic epoxy resin as a binder and dispersing a dispersant in the binder, and a plurality of such light transmitting sections 603B are provided on the transparent substrate 631 corresponding to the blue pixels.

In addition, the transparent substrate 631 provided with the phosphor portions 603r,603g and the light transmission portion 603B is provided at a position opposed to the light source 602. Accordingly, the phosphor portion 603R receives light emitted from the light source 602 and emits red light, the phosphor portion 603G receives light emitted from the light source 602 and emits green light, and the light transmission portion 603B diffuses blue light emitted from the light source 602 with a diffusing agent and transmits the blue light forward. Further, the phosphor portions 603r,603g and the light transmission portion 603B are separated from each other by a black matrix layer 632.

[ V-2-1-4. Effect ]

Since the image display device 601 of the present embodiment is configured as described above, the light source 602 emits light at a predetermined intensity when in use. At this time, light whose intensity is adjusted for each pixel (i.e., the phosphor portions 603r and 603g and the light transmission portion 603B) is emitted from each light source 602 in accordance with an image to be displayed by the image display device 601 under the control of a control portion (not shown). Light emitted from the light source 602 is incident on the corresponding phosphor portions 603r,603g and light transmission portion 603B, respectively.

Among the phosphor portions 603R, a red phosphor (CaAlSiN) dispersed in the phosphor portions 603R ₃ Eu) absorbs incident light and emits red fluorescence. In the phosphor portion 3G, green phosphor (Ca) is dispersed in the phosphor portion 603G ₃ Sc ₂ Si ₃ O ₁₂ Ce) absorbs incident light and emits green fluorescence. In the light transmission section 603B, the diffusing agent dispersed in the light transmission section 603B diffuses incident light, and the incident blue light is transmitted forward by combining with the light distribution characteristics of the fluorescent light emitted from the fluorescent sections 603R and 603G.

At this time, since the amount of light incident on each pixel is adjusted by the control unit in accordance with an image to be formed, the amount of light of fluorescence (visible light) emitted from each of the phosphor portions 603r and 603g is also adjusted for each pixel, and a desired image is formed.

The red and green fluorescent lights thus generated and the blue light emitted from the light source 602 by being transmitted through the light transmission section 603B are emitted to the outside (right side in the figure) of the image display apparatus 601 through the transparent substrate 631. The viewer sees the light emitted from the surface of the transparent substrate 631, and recognizes an image.

In this case, caAlSiN as a luminance maintaining phosphor was used for each of the phosphors 603R and 603G ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce, so that the image display device 601 itself can be suppressed from being exposed to lightTemperature dependence of light luminance, thereby preventing different temperature barsThe color of the image displayed under the device deviates from the target color, and is very useful for practical application.

[ V-2-2. Second embodiment ]

Fig. 17 is an exploded sectional view schematically illustrating a main part of an image display device according to a second embodiment of the present application example. Note that the image display device shown in fig. 17 is an image display device when an observer views an image displayed by the image display device from the right side in the figure. In fig. 17, the same reference numerals as in fig. 16 denote the same parts as in fig. 16.

As shown in fig. 17, an image display device 601' of the present embodiment has the same configuration as the image display device 601 of the first embodiment, except that the intensity of light emitted from the light source 602 is adjusted by the grating 606. That is, the light source device includes a light source 602, a phosphor portion (first phosphor portion) 603R and a phosphor portion (second phosphor portion) 603G each including a phosphor that absorbs light emitted from the light source 602 and emits visible light, and a light transmission portion 603B that transmits light emitted from the light source 602 to the front. The image display device 601' further includes a frame 604, a polarizer 605, a grating 606, and an analyzer 607.

The components are explained below.

[ V-2-2-1. Box ]

Block 604 is the same as described in the first embodiment.

[ V-2-2-2. Light Source ]

As the light source 602, the same light source as that described in the first embodiment can be used.

In addition, in the image display device of the present embodiment using the grating 606 in addition to the configuration described in the first embodiment, the light source 602 that emits uniform planar light is useful when the flat panel display is configured by the image display device 601'. In this case, the light source 602 includes not only the element forming the light source 602, which is itself formed of one or more planar light emitting elements, but also an analog planar light emitting element that converts light obtained from one or more elements of an arbitrary shape into planar light by an appropriate method such as light guiding, diffusion, reflection, or the like. In addition, an element combining these units can also be used as the light source 602.

Examples of the light source 602 capable of planar light emission include an inorganic EL element, an organic EL element, a compact flat fluorescent lamp, and a surface-emitting LED using an inorganic semiconductor, as a planar light-emitting element capable of planar light emission.

On the other hand, if an analog planar light emitting element is exemplified, for example, it is exemplifiedAn element in which a light-emitting element and a conversion mechanism for converting light obtained from the light-emitting element into planar light are combined. In this case, any light source described above as an example of the light source 602 can be used as the light-emitting element. As the conversion mechanism, for example, a light guide plate such as a quartz plate, a glass plate, or an acrylic resin plate; reflecting mechanisms such as Al sheets and various metal vapor-deposited films; and use of TiO ₂ A pattern of the system compound, a light diffusion sheet, a light diffusion prism, or other light diffusion means, alone or in combination, preferably several light diffusion means. In particular, a conversion mechanism that converts light into planar light by surface-emitting the light source 602 using a light guide plate, a reflection plate, a diffusion plate, or the like is suitable for the present embodiment. Further, a switching mechanism used for, for example, liquid crystal display devices can be preferably used.

In addition, as in the first embodiment, the size of the light source 602 is not limited, and when the surface light emitting element and/or the pseudo surface light emitting element is used as the light source 602, it is preferably formed to have a thickness of usually 5cm or less, preferably 5mm or less, from the viewpoint of the practicality of the flat panel display.

In this embodiment, a surface light emitting element which emits surface blue light is used as the light source 602, and CaAlSiN contained in the phosphor portions 603r and 603g is excited by the light emitted from the light source 602 ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce and the like. In addition, the first and second substrates are,a part of the light emitted from the light source 602 is transmitted through the light transmitting portion 603B and is seen by the observer as light of a blue pixel. When power is supplied to the light source 602, the terminals on the frame 604 and the electrodes of the light source 602 are electrically connected using an interconnection circuit, a connection wire, or the like, and power is supplied to the light source 602.

[ V-2-2-3. Polarizer ]

A polarizer 605 is preferably provided in front of the light source 602 (right side in the figure), specifically, between the light source 602 and the grating 606. The polarizer 605 selects and transmits only light having a predetermined polarization plane among light emitted from the light source 602. In this embodiment, the polarizer 605 is disposed between the light source 602 and the grating 606.

[ V-2-2-4. Grating ]

In this embodiment, the grating 606 transmits the irradiated light after adjusting the light amount. Specifically, the amount of light irradiated to the backlight by each pixel is adjusted to be transmitted to the front corresponding to the displayed image. In the present embodiment, the grating 606 adjusts the light amount of light emitted from the light source 602 to the phosphor portions 603r,603g and the light transmitting portion 603B for each pixel, and transmits the light to the front.

Specifically, when the image display device 601' is configured as a multicolor or full-color display, the above-described phosphors are arranged in 2 or more types of regions (i.e., phosphor portions 603r, 603g) independently determined as the light wavelength conversion means. In this embodiment, the light amount of light irradiated to the phosphor portions 603r,603g and the light transmission portion 603B is adjusted by the grating 606, and the light amount of light emitted from the phosphor portions 603r,603g and the light transmission portion 603B is adjusted, whereby a desired image can be displayed on the image display device 601' by multicolor light emission.

Further, depending on the type of the grating 606, some gratings can adjust the light amount only for light in a specific wavelength region. Therefore, as the grating 606, a grating capable of switching light by adjusting the light amount of light in the wavelength region of light emitted from the light source 602 is used. In addition, according to the configuration of the image display apparatus 601', the light amount of the fluorescent light emitted from the phosphor portions 603r and 603g, not the light emitted from the light source 602, can be adjusted by the grating 606, and in this case, a grating that can adjust the light amount of the light to perform switching of the light even in the light wavelength region of the fluorescent light emitted from the phosphor portions 603r and 603g is used. The peak wavelength of light emitted from the light source 602 or the fluorescence emitted from the phosphors in the phosphor sections 603r,603g is usually 380nm or more, preferably 420nm or more, and usually 780nm or less, preferably 500nm or less, and therefore the grating 606 is preferably capable of adjusting the light amount of light in this wavelength region.

In addition, the mechanism of the grating 606 is generally composed of an aggregate of several pixels. However, the number and size of pixels and the arrangement thereof vary depending on the screen size, display mode, application, and the like, and are not particularly limited to a constant value. There is no limitation on the size of the pixels of the grating 606, which is arbitrary without significantly impairing the effect of the present application example.

For example, in general display applications, the size of one pixel is preferably 500 μm or less. Further, as a preferable pixel size, a currently available practical liquid crystal display has a pixel number of 640 × 3 × 480, and a size of one pixel of a single color is more preferably about 100 × 300 μm.

The number and size of the gratings 606 themselves are not limited, and may be any number without significantly impairing the effect of the present application example. For example, the grating 606 is generally useful with a thickness of 5cm or less, and is preferably 1cm or less in view of reduction in thickness and weight.

In the case where the image display device 601' is a flat display device, it is preferable to use a grating 606 for changing the light transmittance of a pixel to an arbitrary value by electrical control in order to enable gradation display (alignment intensity level). The higher the absolute value of the light transmittance, the higher the contrast of the change thereof, and the higher the speed response.

Examples of the grating 606 satisfying these requirements include a transmissive liquid crystal grating using a TFT (Thin Film Transistor), STN (Super-Twisted crystalline crystal), ferroelectric, antiferroelectric, guest-host grating (ゲストホスト) of dichroic dye, polymer Dispersed PDN (Polymer Dispersed Network) system, or the like; electroluminescent compounds and chemiluminescent compounds represented by tungsten oxide, iridium oxide, prussian, viologen derivatives, tetrathiafulvalene (TTF) -polystyrene, rare earth metal-phthalocyanine complexes, polythiophene, polyaniline, and the like. Among them, the liquid crystal grating has characteristics of thinness, lightness, less power consumption, durability in practical use, and capability of increasing the density of segments, and thus is very suitable for use. Among them, a liquid crystal grating using a TFT active matrix drive or a PDN method is particularly preferable. The reason for this is that the active matrix using twisted nematic liquid crystal is because of the high-speed response of moving images and the characteristic that crosstalk does not occur, and the PDN method is because the polarizer 605 or the analyzer 607 is not required, and the light emitted from the light source 602 and the phosphor portions 603r and 603g is attenuated little and can emit light with high luminance.

The image display apparatus 601 'is generally provided with a control unit (not shown) for controlling the raster 606 to adjust the light amount of each pixel in accordance with the image displayed by the image display apparatus 601'. The grating 606 adjusts the amount of visible light emitted from each pixel in accordance with the control of the control unit, thereby causing a desired image to be displayed on the image display device 601'.

The image display apparatus 601' can form a control circuit of the control section more easily by adjusting the luminance of the pixels by the raster 606. For example, as described in the first embodiment, when an LED is used as the light source 602 and the luminance of a pixel is adjusted by controlling the light emission intensity of the LED or the like, the current-luminance characteristics of the LED change with time, and a control circuit for controlling a displayed image may become complicated. On the other hand, as in this embodiment, when a grating 606 for adjusting the amount of light emitted from the light source 602 is provided and the luminance of the pixel is adjusted by the grating 606, the grating such as a liquid crystal grating is mostly voltage-controlled, and thus the luminance can be adjusted by a simple control circuit.

In this embodiment, a liquid crystal grating in which a back electrode 661, a liquid crystal layer 662, and a front electrode 663 are stacked in this order is used as the grating 606, and the grating 606 is disposed in front of (to the right in the figure) the polarizer 605. The rear surface electrode 661 and the front surface electrode 663 are formed of transparent electrodes that do not absorb light used in the image display device 601'. Then, the liquid crystal grating controls the molecular arrangement of the liquid crystal in the liquid crystal layer 662 by the voltage applied to the back electrode 661 and the front electrode 663, and the respective light amounts of the light irradiated to the back surface side are adjusted for each of the pixels (i.e., each of the phosphor portions 603r,603g and the light transmission portion 603B) by the molecular arrangement.

[ V-2-2-5. Polarization analyzer ]

An analyzer 607 for receiving the light whose light quantity is adjusted when the grating 606 is transmitted is provided in front of the grating 606 as appropriate. The analyzer 607 transmits only light having a specific polarization plane in the grating 606, thereby adjusting the light emission intensity.

In the present embodiment, an analyzer 607 is provided in front of the grating 606, specifically, between the grating 606, the phosphor portions 603r,603g, and the light transmission portion 603B.

[ V-2-2-6. Fluorescent substance part and light transmission part ]

The phosphor portions 603r,603g are portions containing phosphors that absorb excitation light emitted by the light source 602 and emit visible light that forms an image displayed by the image display device 601', as in the first embodiment. In this embodiment, at least one of the phosphor portions 603r and 603g contains at least one of luminance maintaining phosphors as a phosphor. In addition, phosphor portions 603r,603g are generally provided one by one corresponding to the pixels of the grating 606 to realize that the pixels of the image display apparatus 601' generate light.

The light transmission portion 603B is provided for each pixel of the grating 606 as in the case of the phosphor portions 603r and 603g, and is a portion which transmits the light of the light source 602 forward and serves as a part of the light of the pixel, as in the first embodiment. The light transmitting section 603B is generally provided in the same manner as the phosphor sections 603r,603g, except that it does not contain a phosphor.

Therefore, in this embodiment, the observer sees the fluorescence emitted from the phosphor portions 603r and 603g and the light emitted from the light source 602 emitted through the light transmission portion 603B, and recognizes an image.

In the case of the image display apparatus 601' using the grating 606 as in this embodiment, for example, in addition to the configuration of the first embodiment, the phosphor portion 603r,603g may be formed by forming a mixture (coating liquid) containing a binder, a phosphor, and a solvent into a mosaic shape, an array shape, or a stripe shape on the transparent substrate 631 at intervals corresponding to the pixels of the grating 606 by a screen printing method.

In the case of the image display device 601 'using the grating 606 as described in this embodiment, for example, when the image display device 601' is displayed in a multi-color mode, phosphors that emit light of a predetermined color are provided in a light emitting region such as the phosphor portions 603r and 603g in accordance with the shape of the pixels of the grating mechanism.

In the present embodiment, the red fluorescent portion 603R uses a luminance-maintaining fluorescent material CaAlSiN ₃ Eu is used as the red phosphor, a non-aromatic epoxy resin is used as a binder, and the red phosphor is dispersed in the binder and formed on the transparent substrate 631. In addition, several phosphor portions 603R are provided corresponding to red pixels.

In the present embodiment, the green fluorescent section 603G uses a luminance-maintaining phosphor Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce is a green phosphor, a non-aromatic epoxy resin is used as a binder, and the green phosphor is dispersed in the binder and formed on the transparent substrate 631. Several such phosphor portions 603G are provided for the green pixels.

In the present embodiment, the light transmission sections 603B are formed by using a non-aromatic epoxy resin as a binder and dispersing a diffusing agent in the binder, and several of these light transmission sections 603B are provided on the transparent substrate 631 so as to correspond to the blue pixels.

Further, a transparent substrate 631 provided with the phosphor portions 603r,603g and the light transmission portion 603B is provided in a position in front of (rightward in the drawing) the analyzer 607 so as to face the grating 606. Accordingly, the phosphor portion 603R emits red light when receiving light whose light amount is adjusted by the grating 606 from the light source 602, the phosphor portion 603G emits green light when receiving light whose light amount is adjusted by the grating 606 from the light source 602, and the light transmission portion 603B transmits blue light whose light amount is adjusted by the grating 606 from the light source 602 forward while diffusing the blue light with the diffusing agent. Further, the phosphor portions 603r,603g and the light transmission portion 603B are separated from each other by a black matrix layer 632.

[ V-2-2-7. Effect ]

Since the image display device 601' of the present embodiment is configured as described above, the light source 602 emits light at a predetermined intensity when used. Light emitted from the light source 602 is incident on the grating 606 after having its polarization plane aligned by the polarizer 605.

Under the control of a control unit (not shown), the light amount of light incident from the back side is adjusted for each pixel in accordance with an image to be displayed by the raster 606 so as to be transmitted to the front. Specifically, by controlling the voltages applied to the transparent voltages 661 and 663, the orientation of the liquid crystal in the region corresponding to each pixel is adjusted, thereby adjusting how much intensity of light is transmitted through each pixel, and the light received on the back surface is transmitted forward.

The light passing through the grating 606 is incident on the corresponding phosphor portions 603r,603g and light transmission portions 603B via the analyzer 607, respectively.

Among the phosphor portions 603R, a red phosphor (CaAlSiN) dispersed in the phosphor portions 603R ₃ Eu) absorbs incident light and emits red fluorescence. In the phosphor portion 603G, a green phosphor (Ca) is dispersed in the phosphor portion 603G ₃ Sc ₂ Si ₃ O ₁₂ Ce) absorbs incident light and emits green fluorescence. In the light transmitting section 603B, the diffusing agent dispersed in the light transmitting section 603B diffuses incident light, and transmits the incident blue light forward by combining with the light distribution characteristics of the fluorescent light emitted from the fluorescent sections 603R and 603G.

At this time, the amount of incident light is adjusted for each pixel by the grating 606 in accordance with an image to be formed, and thus the amount of fluorescence (visible light) emitted from each of the phosphor portions 603r,603g is also adjusted for each pixel, whereby a desired image is formed.

The thus generated red and green fluorescent lights and the blue light emitted from the light source 602 by transmitting the light transmitting section 603B are emitted to the outside (right side in the figure) of the image display apparatus 601' through the transparent substrate 631. The observer sees the light emitted from the surface of the transparent substrate 631, and recognizes an image.

In this case, caAlSiN as a luminance maintaining phosphor was used for each of the phosphors 603R and 603G ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce, the temperature dependency of the light emission luminance of the image display device 601' itself can be suppressed, and thus, the color of the image displayed under different temperature conditions can be prevented from being deviated from the target color, which is very useful for practical use.

In addition, unlike the conventional image display device using a liquid crystal barrier, the image display device 601' of the present embodiment can prevent a decrease in luminance or a change in color of a pixel due to a viewing angle.

[ V-2-3. Embodiment 3 ]

[ V-2-3-1. Constitution ]

Fig. 18 is an exploded sectional view schematically illustrating a main part of an image display device according to a third embodiment of the present application example. Note that the image display device shown in fig. 18 is an image display device when an observer views an image displayed by the image display device from the right side in the figure. In fig. 18, the same reference numerals as in fig. 16 and 17 denote the same parts as in fig. 16 and 17.

As shown in fig. 18, an image display device 601 ″ of the present embodiment is the same as the image display device 601' described in the second embodiment except that the arrangement order of the components is the order of the substrate 604, the light source 602, the phosphor portions 603r and 603g, the light transmitting portion 603B, the polarizer 605, the grating 606, and the analyzer 607 from the back side, and a black matrix (not shown) is provided between the pixels of the grating 606.

Black regions, called black matrices, are preferably present between the pixels of the grating 606 to improve contrast. The black matrix has a function of making a space between pixels black so that an image is easily seen. As for the material of the black matrix, for example, chromium, carbon, or resin in which carbon or other black substance is dispersed may be used, but not limited thereto. In this embodiment, the black matrix (not shown) is provided on the grating so that the observer can see the light transmitted through the grating 606.

In the image display device 601 ″ of the present embodiment, since the arrangement order of the components is changed as described above, the light amount of light emitted from the phosphor portions 603r and 603g and light transmitted through the light transmission portion 603B is adjusted for each pixel by the grating 606, and is transmitted forward. That is, in the red and green pixels, light emitted from the light source 602 is made incident on the phosphor sections 603r and 603g, and the light amount of light emitted from the phosphors in the phosphor sections 603r and 603g is adjusted for each pixel by the raster 606, and is transmitted forward. In the blue pixel, the light emitted from the light source 602 is scattered by the diffusing agent in the light transmission section 603B and transmitted through the light transmission section 603B, and the light amount of the light transmitted through the light transmission section 603B is adjusted for each pixel by the grating 606 and transmitted forward. In this manner, a desired image can be displayed on the image display device 601 by multicolor light emission using the red, green, and blue lights whose light amounts are adjusted by the grating 606.

Therefore, while the grating 606 is used in the second embodiment to adjust the light amount in the wavelength range of the light emitted from the light source 602, the grating used in the present embodiment is also used to adjust the light amount in the wavelength range of the light emitted from the phosphor portions 603r, 603g. Specifically, the grating 606 of the present embodiment controls the molecular arrangement of liquid crystal in the liquid crystal layer 662 by the voltage applied to the back electrode 661 and the front electrode 663, and adjusts the amount of light irradiated to the back surface side for each pixel by the molecular arrangement.

In this embodiment, caAlSiN is used for the phosphor portion 603R as in the second embodiment ₃ Eu as the red phosphor, a non-aromatic epoxy resin as a binder, and Ca as the green fluorescent part 603G ₃ Sc ₂ Si ₃ O ₁₂ Ce is used as a green phosphor and a non-aromatic epoxy resin is used as a binder.

[ V-2-3-2. Effect ]

Since the image display device 601 ″ of the present embodiment is configured as described above, the light source 602 emits light at a predetermined intensity when in use. Light emitted from the light source 602 is incident to the corresponding phosphor portions 603r,603g and light transmission portion 603B, respectively.

Among the phosphor portions 603R, a red phosphor (CaAlSiN) dispersed in the phosphor portions 603R ₃ Eu) absorbs incident light and emits red fluorescence. In the phosphor section 603G, green phosphor (Ca) dispersed in the phosphor section 603G ₃ Sc ₂ Si ₃ O ₁₂ Ce) absorbs incident light and emits green fluorescence. In the light transmission section 603B, the diffusing agent dispersed in the light transmission section 603B diffuses incident light, and the incident blue light is transmitted forward by combining with the light distribution characteristics of the fluorescent light emitted from the fluorescent sections 603R and 603G.

The red, green, and blue fluorescent lights thus emitted are made uniform in polarization by the polarizer 605, and then incident on the grating 606.

Under the control of a control unit (not shown), the light amount of red light, green light, and blue light incident from the back side is adjusted for each pixel according to the image to be displayed by the raster 606 so as to be transmitted to the front. Specifically, by controlling the voltages applied to the transparent voltages 661 and 663, the alignment properties of the liquid crystal at the portions corresponding to the respective pixels are adjusted, thereby adjusting how much intensity of light is transmitted for each pixel, and the light received by the back surface is transmitted forward.

The light passing through the grating 606 is irradiated to the analyzer 607. At this time, the amounts of the fluorescence emitted from the phosphor portions 603r,603g and the light transmitted through the light transmitting portion 603B are adjusted for each pixel via the grating 606, so that the light irradiated to the analyzer 607 forms a desired image. Then, the observer sees light emitted from the surface of the analyzer 607, and recognizes an image.

In this case, caAlSiN as a luminance maintaining phosphor was used for each of the phosphors 603R and 603G ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ Ce, the temperature dependency of the light emission luminance of the image display device 601 ″ itself can be suppressed, and thus, the color of an image displayed under different temperature conditions can be prevented from being deviated from the target color, which is very useful for practical use.

In addition, unlike the conventional image display device using a liquid crystal grating, the image display device 601 ″ of the present embodiment can eliminate the influence of the residual light characteristics of the phosphors in the phosphor portions 603r and 603g. The fluorescent material may emit fluorescence for a predetermined time after the irradiation of light is stopped, and the time during which the fluorescent material emits fluorescence after the irradiation of light is stopped is referred to as a residual light characteristic. Since different phosphors have different residual light characteristics, a certain specific color tends to be emphasized in an image displayed by a conventional image display device, and the residual light characteristics cause an increase in cost and complication in control. However, the image display apparatus 601 ″ according to the present embodiment can eliminate the influence of the residual light characteristics described above, and prevent the specific color of the image from being emphasized.

In addition, like the second embodiment, the control circuit of the control unit can be more easily manufactured in this embodiment.

[ V-3. Other ]

The embodiments of the present application example have been described above, but the present application example is not limited to the above-described embodiments, and can be arbitrarily changed in implementation as long as the gist of the present application example is not exceeded.

For example, although the above-described embodiment has been described with respect to the case where images are displayed using three types of light, red, green, and blue, images may be displayed using light other than red, green, and blue, or images may be displayed using two or more types of light.

In addition, for example, in a part of the pixels, the light emitted from the light source 602 may be directly used as the light of the pixels.

In addition, in addition to the transmissive phosphor portions 603r,603g, a reflection type configuration may be employed in which light emitted from the light source 602 is reflected at the phosphor portions 603r, 603g. Specifically, for example, in the configuration of the first embodiment, the image display apparatus 601 may be configured such that the light source 2 is disposed in front of the phosphor portions 603r, 603g.

In addition, any CaAlSiN-free compound may be used ₃ Eu or Ca ₃ Sc ₂ Si ₃ O ₁₂ A phosphor portion of a luminance maintaining phosphor such as Ce is used as the phosphor portion.

In addition, caAlSiN may also be used as the luminance maintaining phosphor ₃ Eu and Ca ₃ Sc ₂ Si ₃ O ₁₂ A phosphor having a luminance maintenance other than Ce.

Further, the above-described light source 602, phosphor portions 603r,603g, frame 604, polarizer 605, grating 606, analyzer 607, and the like may be used in any combination within a range not exceeding the gist of the present application example.

Further, the image display devices 601, 601',601 ″ may be combined with other components.

The first light-emitting device, the second light-emitting device, the white light-emitting device, and the image display device may be implemented in any combination.

In addition, the first light-emitting device, the second light-emitting device, the white light-emitting device, and the image display device described above may contain the following phosphor as a wavelength conversion material within a range in which the effects thereof are not impaired.

Specifically, the following substances can be used as the phosphor, but these are merely examples, and the phosphor is not limited to these. Note that, in the following examples, a phosphor having a structure that is partially different is appropriately omitted. For example "Y ₂ SiO ₅ :Ce ³⁺ ”、“Y ₂ SiO ₅ :Tb ³⁺ "and" Y ₂ SiO ₅ :Ce ³⁺ ，Tb ³⁺ Generalized representation of "Y ₂ SiO ₅ :Ce ³⁺ ，Tb ³⁺ ”，“La ₂ O ₂ S:Eu”、 “Y ₂ O ₂ S: eu "and" (La, Y) ₂ O ₂ Eu, is summarized as (La, Y) ₂ O ₂ And S is Eu'. The omitted parts are indicated by comma (,) spaces.

Red phosphor:

examples of the red phosphor include (Mg, ca, sr, ba) ₂ Si ₅ N ₈ Europium-activated alkaline earth silicon nitride-based phosphor expressed by Eu, which is composed of fractured particles having a red fracture surface and emits light in a red region; with (Y, la, gd, lu) ₂ O ₂ A europium-activated rare earth oxysulfide phosphor expressed by Eu, which is composed of growing particles having a substantially spherical shape as a regular crystal growth shape and emits light in a red region; and the like.

The phosphor described in japanese unexamined patent application publication No. 2004-300247, which is a phosphor containing an oxynitride and/or oxysulfide of at least one element selected from the group consisting of Ti, zr, hf, nb, ta, W and Mo, and the oxynitride contained in the phosphor has an α sialon structure in which a part or all of the Al element is substituted by Ga element, can also be used as the phosphor of the present embodiment. Note that these are phosphors containing oxynitride and/or oxysulfide.

Further, (La, Y) may be used as another red phosphor ₂ O ₂ S is a phosphor of Eu-activated oxysulfide such as Eu, Y (V, P) O ₄ :Eu、Y ₂ O ₃ Eu, etc. Eu, activated oxide phosphor, (Ba, sr, ca, mg) ₂ SiO ₄ :Eu，Mn、(Ba，Mg) ₂ SiO ₄ Eu, mn, and the like, eu, mn-activated silicate phosphor, (Ca, sr) S, eu, and the like, eu-activated sulfide phosphor, and YAlO ₃ Eu-activated aluminate phosphor such as Eu, liY ₉ (SiO ₄ ) ₆ O ₂ :Eu、Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ :Eu、(Sr，Ba，Ca) ₃ SiO ₅ :Eu、 Sr ₂ BaSiO ₅ Eu, etc. Eu activated silicate phosphor, (Y, gd) ₃ Al ₅ O ₁₂ :Ce、 (Tb，Gd) ₃ Al ₅ O ₁₂ Ce activated aluminate phosphor, (Ca, sr, ba) such as Ce ₂ Si ₅ N ₈ :Eu、 (Mg，Ca，Sr，Ba)SiN ₂ :Eu、(Mg，Ca，Sr，Ba)AlSiN ₃ Eu, and the like, activated nitride phosphor, (Mg, ca, sr, ba) AlSiN ₃ Ce activated nitride phosphor, (Sr, ca, ba, mg) such as Ce ₁₀ (PO ₄ ) ₆ C _l2 Eu, mn, etc. Eu, mn activated halophosphoric acid (ハロリン acid) salt fluorescenceBulk, (Ba) ₃ Mg)Si ₂ O ₈ :Eu，Mn、(Ba，Sr，Ca，Mg) ₃ (Zn，Mg)Si ₂ O ₈ Eu, mn and other Eu, mn-activated silicate phosphors, 3.5 MgO.0.5 MgF ₂ ·GeO ₂ Mn-activated germane salt phosphor such as Mn, eu-activated oxynitrides phosphor such as Eu-activated alpha sialon, and (Gd, Y, lu, la) ₂ O ₃ Eu, bi and the like Eu, bi activated oxide phosphor, (Gd, Y, lu, la) ₂ O ₂ S is Eu, bi or the like activated oxysulfide phosphor, (Gd, Y, lu, la) VO ₄ Eu, bi and the like Eu, bi activated vanadate phosphor SrY ₂ S ₄ Eu, ce, etcEu, ce activated sulfide phosphor, and CaLa ₂ S ₄ Ce activated sulfide phosphor, (Ba, sr, ca) MgP, such as Ce ₂ O ₇ :Eu，Mn、(Sr，Ca，Ba，Mg，Zn) ₂ P ₂ O ₇ Eu, mn, and the like Eu, mn activated phosphate phosphor, (Y, lu) ₂ WO ₆ Eu, mo, etc. Eu, mo activated tungstate phosphor, (Ba, sr, ca) _x Si _y N _z Eu, ce (wherein x, y, and z are integers of 1 or more), and the like, eu, ce activated nitride phosphor, (Ca, sr, ba, mg) ₁₀ (PO ₄ ) ₆ (F, cl, br, OH) Eu, mn, and other Eu, mn activating halophosphate phosphors, ((Y, lu, gd, tb) _1-x Sc _x Ce _y ) ₂ (Ca，Mg) _1-r (Mg，Zn) _2+r Si _z-q Ge _q O _12+δ And Ce-activated silicate phosphors.

As the red phosphor, a red organic phosphor formed of a rare earth element ion complex having an anion of a β -diketonate, a β -diketone, an aromatic carboxylic acid, a bronsted acid or the like as a ligand, a perylene pigment (for example, dibenzo { [ f, f '] -4,4',7,7 '-tetraphenyl } diindeno [1,2,3-cd:1',2',3' -lm ] perylene), an anthraquinone pigment, a lake pigment, an azo pigment, a quinacridone pigment, an anthracene pigment, an isoindoline pigment, a phthalocyanine pigment, a triphenylmethane base dye, a indanthrone pigment, an indophenol pigment, a cyanine pigment, a dioxazine pigment, or the like can be used.

Green phosphor:

examples of the green phosphor include (Mg, ca, sr, ba) Si which is composed of a fractured particle having a fracture surface and emits light in a green region ₂ O ₂ N ₂ Europium-activated alkaline earth silicon oxynitride-based phosphor expressed by Eu, and (Ba, ca, sr, mg) which is composed of fractured particles having fracture surfaces and emits light in the green region ₂ SiO ₄ Europium-activated alkaline earth silicate phosphors represented by Eu.

In addition, as the green phosphor, sr may also be used ₄ Al ₁₄ O ₂₅ :Eu、(Ba，Sr，Ca)Al ₂ O ₄ Eu-activated aluminate phosphor, (Sr, ba) Al ₂ Si ₂ O ₈ :Eu、(Ba，Mg) ₂ SiO ₄ :Eu、 (Ba，Sr，Ca，Mg) ₂ SiO ₄ :Eu、(Ba，Sr，Ca) ₂ (Mg，Zn)Si ₂ O ₇ Eu, Y, or the like, as Eu-activated silicate phosphor ₂ SiO ₅ Ce, tb activated silicate phosphors such as Ce, tb, etc., sr ₂ P ₂ O ₇ -Sr ₂ B ₂ O ₅ Eu-activated borate phosphate phosphor, sr ₂ Si ₃ O ₈ -2SrCl ₂ Eu, and the like Eu-activated halosilicic acid (ハロ silicon)Acid) salt phosphor, zn ₂ SiO ₄ Mn-activated silicate phosphor such as Mn, ceMgAl ₁₁ O ₁₉ :Tb、 Y ₃ Al ₅ O ₁₂ Tb-activated aluminate phosphor such as Tb and Ca ₂ Y ₈ (SiO ₄ ) ₆ O ₂ :Tb、La ₃ Ga ₅ SiO ₁₄ Tb activated silicate phosphor such as Tb and (Sr, ba, ca) Ga ₂ S ₄ Eu, tb, sm and other Eu, tb, sm activated thiogallate (チオガレ - ト) phosphor, Y ₃ (Al，Ga) ₅ O ₁₂ :Ce、 (Y，Ga，Tb，La，Sm，Pr，Lu) ₃ (Al，Ga) ₅ O ₁₂ Ce-activated aluminate phosphor such as Ce, ca ₃ Sc ₂ Si ₃ O ₁₂ :Ce、Ca ₃ (Sc，Mg，Na，Li) ₂ Si ₃ O ₁₂ Ce-activated silicate phosphor such as Ce, caSc ₂ O ₄ Ce-activated oxide phosphor such as Ce, srSi ₂ O ₂ N ₂ :Eu、(Sr，Ba，Ca)Si ₂ O ₂ N ₂ Eu-activated oxonitride phosphor such as Eu, eu-activated beta-sialon, eu-activated alpha-sialon, or the like, baMgAl ₁₀ O ₁₇ Eu, mn, etc. activated aluminate phosphor, srAl ₂ O ₄ Eu, etc. activated aluminate phosphor, (La, gd, Y) ₂ O ₂ Tb (Tb) activated oxysulfide phosphor and LaPO ₄ Ce, tb activated phosphate phosphors such as Ce, tb, etc., znS Cu, al, znS Cu, au, al sulfide phosphors, etc., (Y, ga, lu, sc, la) BO phosphors ₃ :Ce，Tb、Na ₂ Gd ₂ B ₂ O ₇ :Ce，Tb、 (Ba，Sr) ₂ (Ca，Mg，Zn)B ₂ O ₆ Ce, tb activated borate phosphor such as K, ce, tb, etc., ca ₈ Mg(SiO ₄ ) ₄ Cl ₂ Eu, mn, and the like Eu, mn-activated halosilicate phosphors, (Sr, ca, ba) (Al, ga, in) ₂ S ₄ Eu-activated sulphoaluminate phosphor or thiogallate (チオガレ - ト) phosphor, (Ca, sr) ₈ (Mg，Zn)(SiO ₄ ) ₄ Cl ₂ Eu, mn and the like, and Mn-activated halosilicate phosphors.

As the green phosphor, a fluorescent dye such as a pyridine-phthalimide condensation derivative, a benzoxazinone-based, quinazolinone-based, coumarin-based, quinophthalone-based, or naphthalimide-based fluorescent dye, or an organic phosphor such as a terbium complex can be used.

Blue phosphor:

the blue phosphor may be BaMgAl ₁₀ O ₁₇ Europium-activated barium magnesium aluminate phosphor expressed by Eu, which is composed of growing particles having a regular crystal growth shape and having a substantially hexagonal shape and emits light in a blue region; with (Ca, sr, ba) ₅ (PO ₄ ) ₃ Eu, which is composed of growing particles having a substantially spherical shape as a regular crystal growth shape and emits light in the blue region; with (Ca, sr, ba) ₂ B ₅ O ₉ Eu, which is composed of growth particles having a regular crystal growth shape and a substantially cubic shape, and emits light in the blue region; with (Sr, ca, ba) Al ₂ O ₄ Eu or (Sr, ca, ba) ₄ Al ₁₄ O ₂₅ Europium-activated alkaline earth aluminate phosphor represented by Eu,which is composed ofA fracture particle structure of fracture surface for emitting light in a blue-green region; and the like.

In addition, as the blue phosphor, sr may be used ₂ P ₂ O ₇ Sn-activated phosphate phosphor such as Sn, sr ₄ Al ₁₄ O ₂₅ :Eu、BaMgAl ₁₀ O ₁₇ :Eu、BaAl ₈ O ₁₃ Eu-activated aluminate phosphor such as Eu, srGa ₂ S ₄ :Ce、CaGa ₂ S ₄ Ce activated thiogallate phosphor (Ba, sr, ca) MgAl ₁₀ O ₁₇ :Eu、BaMgAl ₁₀ O ₁₇ Eu, tb, sm and other Eu activated aluminate phosphor, (Ba, sr, ca) MgAl ₁₀ O ₁₇ Eu, mn, and the like Eu, mn-activated aluminate phosphor, (Sr, ca, ba, mg) ₁₀ (PO ₄ ) ₆ Cl ₂ :Eu、(Ba，Sr，Ca) ₅ (PO ₄ ) ₃ (Cl, F, br, OH) Eu, mn, sb, and other Eu-activated halophosphate phosphors, baAl ₂ Si ₂ O ₈ :Eu、(Sr，Ba) ₃ MgSi ₂ O ₈ Eu-activated silicate phosphor, sr and Eu ₂ P ₂ O ₇ Eu-activated phosphate phosphor such as Eu, znS: ag, sulfide phosphor such as Al, Y ₂ SiO ₅ Ce-activated silicate phosphor such as Ce, caWO ₄ Tungstate phosphor, (Ba, sr, ca) BPO ₅ :Eu，Mn、(Sr，Ca) ₁₀ (PO ₄ ) ₆ ·nB ₂ O ₃ :Eu、 2SrO·0.84P ₂ O ₅ ·0.16B ₂ O ₃ Eu, mn, and other activated borate phosphate phosphors, sr ₂ Si ₃ O ₈ ·2SrCl ₂ Eu, and the like, as an active Eu halogen silicate phosphor.

As the blue phosphor, for example, an organic phosphor such as a fluorescent dye of naphthalimide type, benzoxazole type, styrene type, coumarin type, pyrazoline (ピラリゾン) type, triazole type compound, thulium complex, or the like can be used.

The phosphor may be used alone in 1 type, or two or more types may be used in any combination and ratio.

[ examples ] A method for producing a compound

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the examples described below, and may be arbitrarily changed in practice within a range not exceeding the gist of the present invention.

[ I. examples relating to the first light-emitting device ]

[ example 1-1]

The mixture was mixed to obtain a phosphor mixture in which the weight percentage of the first phosphor was 94% and the weight percentage of the second phosphor was 6%. The first phosphor used herein was an oxide phosphor having an emission efficiency of 46% when excited by light having a wavelength of 455nm, containing 0.06 mol (0.02 mol based on 1 mol of Ca in the chemical composition formula) of Ce as an activator and containing Ca ₃ Sc ₂ Si ₃ O ₁₂ Has a luminescence peak wavelength at 505 nm. The second phosphor used was a nitride phosphor containing 0.008 mol, whose emission efficiency when excited by light having a wavelength of 455nm was 54%Eu as activator and CaAlSiN ₃ Has a luminescence peak wavelength at 650 nm.

The luminance and chromaticity coordinate value x obtained by excitation with blue light having a peak wavelength of 455nm were measured at 160 ℃ or less while the temperature of the phosphor mixture was kept constant in stages. The measurement result of luminance is shown in fig. 19. The results are as follows: brightness at 25 ℃ [ BR (25) ]Brightness at 125 ℃ when 1 is assumed [ BR (125)]Is 0.92, the ratio of the luminance [ BR (125)/BR (25) ]]Is 0.92. Further, a chromaticity coordinate value x [ x ] at 25 DEG C ₂ (25)]Is 0.404, and a chromaticity coordinate value x [ x ] at 125 deg.C ₂ (25)]0.418, the difference [ x ] of the chromaticity coordinate values x ₂ (25)-x ₂ (25)]It was 0.014. In addition, when the luminance and chromaticity coordinate value x is measured, the fluorescence spectrum of less than 470nm emitted from the phosphor mixture is not taken into account, and only the fluorescence spectrum of 470nm or more is used for calculation so as not to be excited by 455nm wavelengthThe influence of light.

Further, a cannonball type white light emitting device was produced in the following order. First, an LED (C460 MB, produced by Cree) emitting light at a wavelength of 460nm was mounted on a cup of a bullet type LED frame using a conductive mounting member silver paste. Next, the electrodes and inner leads of the LED were soldered using Au wires. Then, a mixture of a phosphor and a resin (hereinafter referred to as a phosphor paste) obtained by sufficiently mixing the above phosphor mixture at a ratio of 1g to 10g of an epoxy resin was poured into a cup portion of a frame on which an LED was mounted. This was held at 120 ℃ for one hour to cure the epoxy resin. Next, the frame with the LED and the phosphor mounted thereon obtained above was inserted into a shell-shaped mold into which an epoxy resin was poured, and was held at 120 ℃ for one hour. After the resin was cured, the resin was taken out from the mold, and a shell-type white light emitting device was obtained.

At room temperature (about 24 ℃), and the current density is 17.5A/cm under the condition of current 10 mA-40 mA ² ～ 70A/cm ² The white light emitting device thus obtained was driven in the range of (1), and the entire light emitted from the white light emitting device was received by an integrating sphere and guided to a spectroscope via an optical fiber to measure the emission spectrum. The data of the luminescence spectrum are values of luminescence intensity recorded per 5nm in a range from 380nm to 780 nm. As a result, the white light emitting device was driven at a current of 10mA and had chromaticity coordinate values x and y of 0.288 and 0.308, respectively, and driven at a current of 40mA and chromaticity coordinate values x and y of 0.291 and 0.309, respectively. This indicates that the drive current for the blue LED is in the range of 10mA to 40mA, that is, 17.5A/cm ² ～70A/cm ² Variation of current density within a range, difference of chromaticity coordinate values [ x ] ₁ (17.5)-x ₁ (70)]、[y ₁ (17.5)-y ₁ (70)]Minimum, 0.003, 0.001 respectively, drivenThe color difference due to the change in the amount of emitted light caused by the increase or decrease in the current is very small.

When the average color rendering index Ra of the white light-emitting device was calculated by the method specified in JIS Z8726, the white light-emitting device exhibited good color rendering properties, and Ra was 90. Compared with the existing pseudo-white light emitting device combining the blue LED and the yttrium aluminum garnet phosphor, the white light emitting device has obviously high average color rendering index and shows good light emission.

In order to compare with the first light-emitting device of the present invention, the emission intensity of a pseudo-white light-emitting device obtained by combining a conventional blue LED and an yttrium aluminum garnet phosphor was measured, and the chromaticity coordinate value thereof was determined. The results are as follows: chromaticity coordinate values x and y of 0.321 and 0.314 respectively under the current 10mA drive, chromaticity coordinate values x and y of 0.314 and 0.306 respectively under the current 40mA drive, and a drive current in the range of 10mA to 40mA of the blue LED, namely 17.5A/cm ² ～70A/cm ² Variation of current density within a range, difference of chromaticity coordinate values [ x ] ₁ (17.5)-x ₁ (70)]、[y ₁ (17.5)-y ₁ (70)]Large, i.e., -0.007 and-0.008, the color difference due to the change in the amount of emitted light with the increase and decrease in the drive current is very large as compared with the first light-emitting device of the present invention.

Further, the luminance and chromaticity coordinate value x obtained by excitation with blue light having a peak wavelength of 455nm were measured while heating the yttrium aluminum garnet-based phosphor to 160 ℃. The luminance results are shown in FIG. 19. As a result, assuming that the luminance at 25 ℃ [ BR (25) ] is 1, the luminance at 125 ℃ [ BR (125) ] is 0.68, the ratio of the luminance [ BR (125)/BR (25) ] is 0.68, and the temperature extinction is large. Accordingly, temperature extinction of the yttrium aluminum garnet phosphor is one of the causes of a large color difference due to a change in the amount of emitted light with an increase or decrease in the drive current of the white light emitting device. Also, the conventional product has a low average color rendering index Ra of 79.

As is clear from the above results, the image display device having stable color reproducibility with less color difference due to a change in the amount of emitted light caused by an increase or decrease in the drive current and the illumination device having high color rendering property and less color difference due to a change in the ambient temperature and the amount of emitted light can be obtained by using the first light-emitting device of the present invention as compared with conventional products.

[ II. examples relating to second light-emitting devices ]

The second light-emitting device of the present invention will be described in more detail below with reference to examples and comparative examples.

Next, a light-emitting device having the same configuration as that of the light-emitting device of the first embodiment of the second light-emitting device of the present invention was produced, and the light-emitting efficiency and color rendering property thereof were evaluated. Note that, in the following examples and comparative examples, for convenience, the components corresponding to fig. 3 are indicated by parentheses.

[ example 2-1]

A frame (102) having a cup-shaped recess (102A) is prepared, and a blue LED (103) as a light source emitting light at a wavelength of 450 to 470nm is die-bonded (ダィボンディング) to the bottom of the recess (102A) using silver paste (105) as an adhesive. In this case, silver paste (105) used for die bonding is uniformly applied in consideration of heat dissipation of heat generated by the blue LED (103). After heating at 150 ℃ for two hours to cure the silver paste, the blue LED (103) was connected to the electrode of the frame (102) with a connecting wire. A gold wire having a diameter of 25 μm was used as the connection wire (106).

As the blue LED (103), "ES-CEBL912" manufactured by EPISTAR was used.

As the luminescent material of the luminescent material (104), ca, which emits light having a wavelength of about 470nm to 690nm, is used _2.94 Ce _0.06 Sc _1.94 Mg _0.06 Si ₃ O ₁₂ A phosphor represented by the general formula (referred to as phosphor A) and Sr for emitting light having a wavelength of about 520 to 760nm _0.8 Ca _0.192 Eu _0.008 AlSiN ₃ (referred to as phosphor B).

The ratio of the phosphors A and B in the phosphor mixture of the luminescent light emitting section (104) is 90: 10 (weight ratio). Further, a phosphor paste was prepared with the ratio of the weight of the phosphor mixture to the weight of the epoxy resin set to 25: 75.

The phosphor paste is injected into the recess (102A) of the frame (102) and heated to be cured.

Next, the frame as a whole is cast with epoxy resin. A cup-shaped mold is used for forming the molded portion.

The light emitting device (101) is caused to emit light (drive current 20mA, drive current density 17.5A/cm) by supplying power to the blue LED (103) ² At a temperature of 20 ℃). At this time, the light emission spectrum of the light emitted from the light emitting device (101) was measured with an integrating sphere, and the total luminous flux, chromaticity, and color rendering properties were examined by changing the drive current of the blue LED (103) to 80mA and the drive current density to 70A/cm ² The change in chromaticity. The results are shown in Table 1. In addition, the color rendering properties are represented by R calculated according to JIS Z8726 ₁ ～R ₁₅ And R ₁ ～R ₈ The average value Ra of (A) was evaluated.

In Table 1, chromaticity (x/y) represents color coordinates.

[ TABLE 1]

Total luminous flux	2.4lm
		Luminous efficiency	34lm/W
x	0.301
		y	0.312
Ra	88
		R 1	94
R 2	94
		R 3	90
R 4	79
		R 5	88
R 6	91
		R 7	83
R 8	82
		R 9	76
R 10	89
		R 11	83
R 12	63
		R 13	97
R 14	95
		R 15	90

Chromatic aberration
		x 1 (17.5)-x 1 (70)	0.004
y 1 (17.5)-y 1 (70)	0.005

In addition, fig. 20 shows an emission spectrum of the present light-emitting device.

In addition, the temperature characteristics of the mixture of the phosphor a and the phosphor B used were as follows:

BR(125)/BR(25)＝0.998

|x ₂ (25)-x ₂ (125)|＝0.012

|y ₂ (25)-y ₂ (125)|＝0.000。

[ examples 2-2]

A light-emitting device was produced in the same manner as in example 2-1 except that the mixing ratio of the phosphor A and the phosphor B was changed to 91: 9, and the characteristics thereof were evaluated in the same manner, and the results are shown in Table 2. And fig. 21 shows a light emission spectrum of the present light-emitting device.

In addition, the temperature characteristics of the mixture of the phosphor a and the phosphor B used were as follows:

BR(125)/BR(25)＝0.998

|x ₂ (25)-x ₂ (125)|＝0.012

|y ₂ (25)-y ₂ (125)|＝0.000。

[ TABLE 2]

Total luminous flux	2.6lm
		Luminous efficiency	37lm/W
x	0.294
		y	0.319
Ra	86
		R 1	90
R 2	97
		R 3	89
R 4	75
		R 5	86
R 6	94
		R 7	82
R 8	76
		R 9	50
R 10	96
		R 11	78
R 12	60
		R 13	95
R 14	94
		R 15	84

Color difference Chromatic aberration
		x 1 (17.5)-x 1 (70)	0.006
y 1 (17.5)-y 1 (70)	0.009

Comparative example 2-1

A light-emitting device was fabricated in the same manner as in example 2-1 except that "C460MB" manufactured by Cree was used as the blue LED (103), and a phosphor represented by YAG: ce that emits light having a wavelength of about 480 to 720nm was used as the phosphor of the luminescent light-emitting section (104), and the characteristics thereof were evaluated in the same manner, and the results are shown in Table 3. In addition, fig. 22 shows the light emission spectrum of the present light-emitting device.

[ TABLE 3 ]

Total luminous flux	2.6lm
		Luminous efficiency	37lm /W
x	0.280
		y	0.310
Ra	74
		R 1	86
R 2	90
		R 3	73
R 4	51
		R 5	78
R 6	93
		R 7	65
R 8	59
		R 9	22
R 10	81
		R 11	53
R 12	59
		R 13	93
R 14	85
		R 15	74

Chromatic aberration
		x 1 (17.5)-x 1 (70)	0.002
y 1 (17.5)-y 1 (70)	0.051

[ III ] embodiments relating to a white light-emitting device ]

In the following embodiments, the LED means a light emitting diode.

[ example 3-1]

A surface-mounted white light emitting device was produced in the following procedure, and the evaluation thereof was performed.

First, an LED (ES-CEBL 912X10X, produced by Epistar corporation) emitting light at a wavelength of 460nm was soldered to a terminal of a cup (recess) of a frame for a surface-mount LED using a silver paste (conductive mounting member).

Next, the electrodes of the LED were connected to the terminals of the frame using Au wires (conductive connection wires) 20 μm thick.

Ca is used in combination as a wavelength conversion material _2.97 Ce _0.03 Sc ₂ Si ₃ O ₁₂ First fluorescence of the representationBody and Ca _0.992 AlSiEu _0.008 N _2.85 O _0.15 The second phosphor shown. The mixing ratio (weight ratio) of the first phosphor to the second phosphor = 93: 7. These phosphors absorb light (primary light) emitted from the LED and emit light having a wavelength of 470nm to 690nm and light having a wavelength of 540nm to 760nm, respectively.

The wavelength converting material was mixed sufficiently at a ratio of 1g to 10g of silicone resin as a binder, and then the mixture of the phosphor and the silicone resin was injected into the cup portion of the frame to which the LED was soldered. The resultant was held at 150 ℃ for two hours, and the silicone resin was cured, thereby forming a phosphor-containing resin portion in the cup portion, and obtaining a surface-mount white light emitting device.

The surface-mounted white light-emitting device obtained above was driven to emit white light, the emission spectrum of the white light was measured, and the color rendering index R was calculated from the emission spectrum in accordance with JIS-Z8726 ₁ ～ R ₈ The average value Ra thereof is calculated. Among them, the surface-mounted white light emitting device was driven at 20mA at room temperature (about 24 ℃ C.).

Further, the entire light emitted from the surface-mounted white light emitting device was received by an integrating sphere, and then introduced into a spectroscope through an optical fiber, and the emission spectrum of the light emitted from the surface-mounted white light emitting device was measured. The measured luminescence spectrum is shown in FIG. 23.

Further, the internal quantum efficiency and absorbance of the light emitted from the LED by each wavelength conversion material used were measured from the emission spectra of the white light and the entire light, and the luminance maintenance ratio TR (%) of the luminance at 100 ℃ to the luminance at 25 ℃, the flatness [ T (ratio) ] of the white light emitted from the white light emitting device in the predetermined wavelength range, and the correlated color temperature were measured. These properties are shown in Table 4.

[ examples 3-2]

Except that the kind of wavelength converting material is changed to Ca _2.97 Ce _0.03 Sc _1.94 Mg _0.06 Si ₃ O ₁₂ Except for this, a surface-mounted white light-emitting device was produced in the same manner as in example 3-1, and the emission spectra of the white light and all the lights emitted from the surface-mounted white light-emitting device were measured to measure the characteristics in the same manner as in example 3-1, and the characteristics are shown in table 4. In addition, the emission spectrum of the entire light emitted from the surface-mounted white light emitting device is shown in fig. 24.

Comparative example 3-1

Except that the kind of wavelength conversion material is changed to (Y, gd, ce) ₃ Al ₅ O ₁₂ A surface-mounted white light-emitting device was produced in the same manner as in example 3-1 except that the emission spectra of the white light and the entire light emitted from the surface-mounted white light-emitting device were measured, and the characteristics were measured in the same manner as in example 3-1,the properties are shown in Table 4. In addition, the emission spectrum of the entire light emitted from the surface-mounted white light emitting device is shown in fig. 25.

[ Table 4]

	First phosphor			Second phosphor			White light emitting device
												Internal volume Sub-efficiency	Absorbance of the solution	Brightness dimension Retention rate (TR)	Internal volume Sub-efficiency	Absorbance of the solution	Luminance dimension Retention rate (TR)	Degree of flatness [T(rati o)]	Correlated color Temperature of	Color developing finger Number of Mean value (Ra)	Luminous efficiency Rate of formation	Spectrogram
	Examples 3-1	66％	74％	93％	56％	77％	110％	139％	6500K	94	45 lm/W												FIG. 23 shows a schematic view of a display panel
Examples 3-2												69.％	60％	93％	53％	73％	110％	113％	5900K	93	35 lm/W	FIG. 24
	Comparative example 3-1	62％	82％	78％	Is composed of	Is composed of	Is free of	307％	5700K	76	57 lm/W												FIG. 25

As is clear from table 4, by flattening the emission spectrum in the predetermined wavelength range of 500nm to 650nm and setting the degree of flatness [ T (ratio) ] to 150% or less, the color rendering property of white light emitted from the white light emitting device can be improved.

Further, the luminance maintenance ratios of the wavelength conversion materials used in examples 3-1 and 3-2 were as high as 80% or more, and therefore, the white light emitting devices fabricated in examples 3-1 and 3-2 had little possibility of the intensity of white light generated by the heat generation of the LEDs after lighting decreasing with time.

In addition, the wavelength conversion materials used in examples 3-1 and 3-2 have an absorbance of light at the emission wavelength of the LED of 70% or more and an internal quantum efficiency of 40% or more, so that the intensity of light emitted from the white light emitting device is higher than that of comparative example 3-1, and the white light emitting device has excellent emission efficiency.

The white light-emitting device of comparative example 3-1 had higher luminous efficiency than the white light-emitting devices of examples 3-1 and 3-2, but had poor color rendering properties and the wavelength conversion material used had a low luminance maintenance rate, and therefore, the color tone was likely to change due to a change in temperature.

[ IV. examples relating to image display devices ]

[ example 4-1]

The light emitting device constituting the red pixel is composed of an (In, ga) N-based blue LED and a red phosphor. Ca is used as red phosphor _0.992 AlSiEu _0.008 N ₃ The red phosphor is shown. The red phosphor absorbs light emitted from the (In, ga) N-based blue LED and emits light having a wavelength of 540nm to 760 nm.

The red phosphor was synthesized by mixing silicon nitride, aluminum nitride, calcium nitride powder, and europium nitride at a predetermined ratio, and heating the mixture in a graphite resistance heating electric furnace at a pressure of 1MPa and a temperature of 1800 ℃ for two hours in a nitrogen atmosphere.

As a result of measuring the emission intensity of the red phosphor at a changed temperature in the same manner as the method of measuring the temperature dependence coefficient TR of the phosphor described in the above embodiment, the emission intensity did not decrease with an increase in temperature, and the ratio of the emission intensity at 100 ℃ to the emission intensity at 25 ℃ (the temperature dependence coefficient TR of the phosphor) was 109%.

Using this red phosphor, a red light-emitting solid-state light-emitting device similar to that shown in fig. 12 was produced in the following order. Note that, in the following description, symbols shown in parentheses "[ ]" are symbols indicating the corresponding portions in fig. 12.

First, an LED (C460-MB 290-S0100; MB grade, optical power 9mW to 10 mW) [ 313 ] which is produced by Cree Co., ltd.) emitting light at a wavelength of 460nm was soldered to a terminal [ 315 ] of a cup [ 312A ] of a frame [ 312 ] for a surface-mounted LED by using a silver paste (conductive mounting member).

Next, the electrode (not shown) of the LED [ 313 ] and the terminal [ 316 ] of the frame [ 312 ] are connected by using a 20 μm thick Au wire (conductive connection wire) [ 317 ].

The above red phosphor [ 314 ] is sufficiently mixed with 5g of silicone resin (binder) [ 318 ], in a ratio of 1g to 5g, and the mixture of the phosphor and the silicone resin is injected into the cup portion [ 312A ] of the frame [ 312 ] to which the LED [ 313 ] is soldered.

The resultant was held at 150 ℃ for two hours, and the silicone resin [ 318 ] was cured to form a phosphor-containing resin portion, thereby obtaining a surface-mounted red light-emitting device [ 311 ].

The emission spectrum of the surface-mounted red light-emitting device [ 311 ] obtained as above was measured. Wherein the surface-mounted red light-emitting device [ 311 ] is driven at 20mA at room temperature (about 24 ℃ C.). Specifically, the entire light emitted from the surface-mounted red light-emitting device [ 311 ] was received by an integrating sphere, and then introduced into a spectroscope through an optical fiber, and the emission spectrum and the entire luminous flux were measured.

The emission spectrum of the red light-emitting device [ 311 ] is shown in FIG. 26.

Further, in the measurement results of the emission spectra, CIE chromaticity coordinate values x and y were calculated based on the numerical values of the emission intensities in the wavelength range of 380nm to 780nm, and as a result, x =0.68 and y =0.31.

Further, the internal quantum efficiency of the red phosphor was calculated based on the measurement result of the emission spectrum, and the result was 56%.

In addition, the same treatment as in the case of the red light emitting device [ 311 ] was carried out using a blue LED and a green phosphor Ca _2.97 Ce _0.03 Sc ₂ Si ₃ O ₁₂ Producing green light emission constituting green pixel Provided is a device.

The green phosphor was produced in the following order. Adding CaCO ₃ 、Sc ₂ O ₃ 、SiO ₂ 、 CeO ₂ The green phosphor was obtained by charging a predetermined amount of ethanol into an agate mortar, thoroughly mixing the mixture, drying the mixture, wrapping the dried mixture in a platinum foil, and heating the foil at 1500 ℃ for three hours under a nitrogen atmosphere containing 4 wt% of hydrogen. The obtained green phosphor was washed, pulverized and classified.

The emission spectrum of the green light-emitting device obtained above was measured in the same manner as the red light-emitting device. The emission spectrum of the green light-emitting device is shown in fig. 27.

Further, in the measurement results of the emission spectra, CIE chromaticity coordinate values x and y were calculated based on the numerical values of the emission intensities in the wavelength range of 380nm to 780nm, and as a result, x =0.29 and y =0.50.

The emission intensity of the green phosphor was measured while changing the temperature, and as a result, the ratio of the emission intensity at 100 ℃ to the emission intensity at 25 ℃ (phosphor temperature dependence coefficient TR) was 93%.

Further, tiO fine white powder was used as a diffusing agent ₂ A blue light-emitting device was produced in the same manner as the red light-emitting device [ 311 ] except that the red phosphor was replaced. The emission spectrum of the obtained blue light-emitting device was measured in the same manner as the red light-emitting device. The emission spectrum of the blue light-emitting device is shown in fig. 28.

The red, green and blue pixels manufactured as described above are arranged on a plane, and a wiring and a lighting control circuit are formed, whereby a full-color display device (display) can be manufactured. In addition, it is assumed that the full-color display device manufactured in this way can reduce color difference due to temperature change by manufacturing red pixels and green pixels using a phosphor having a high temperature dependence coefficient TR of the phosphor.

[ example 4-2]

A full-color display device was produced In the same manner as In example 4-1, except that an (In, ga) N-based green light-emitting element and a diffusing agent were used In combination In place of the green light-emitting device constituting the green pixel In example 4-1.

The emission spectra of the three colors of light of the display device were measured, and the results are shown in FIG. 29.

In the full-color display device manufactured in this way, since the red pixel and the green pixel are manufactured using the phosphor having a high phosphor temperature dependence coefficient TR, it is estimated that the color difference due to the temperature change can be reduced.

[ V. examples relating to application examples of the above-described image display apparatus ]

[ phosphor for Green ]

[ example 5-1]

The luminance of an oxide phosphor, which contains 0.06 mol (0.02 mol relative to 1 mol Ca in the chemical composition formula) of Ce as an activator and has Ca, excited with blue light having a peak wavelength of 455nm was measured by raising the temperature to a predetermined temperature (temperature raising rate: 10 ℃/min) in stages within 160 ℃, and keeping the temperature constant at a predetermined temperature (20 seconds) ₃ Sc ₂ Si ₃ O ₁₂ Has a luminescence peak wavelength at 505 nm. The relative luminance (luminance maintenance ratio, with the luminance at 25 ℃ being 100%) at each temperature is shown in fig. 30. The graph shown by a quadrangle in FIG. 30 shows the results of example 5-1.

In the measurement of luminance, the fluorescence spectrum of less than 470nm emitted from the phosphor mixture was not taken into account, and only the fluorescence spectrum of 470nm or more was used for calculation so as not to be affected by the excitation light having a wavelength of 455 nm.

Comparative example 5-1

The luminance maintenance ratio of the phosphor was measured in the same manner as in example 5-1, except that YAG: ce was used as the phosphor. The results of the relative luminance (luminance maintenance ratio, luminance at 25 ℃ is 100%) at each temperature are shown in FIG. 30.

The curve shown by a circle in FIG. 30 shows the result of comparative example 5-1.

[ phosphor for Red ]

[ examples 5-2]

Except that 0.8 mol% (0.008 mol relative to 1 mol Ca in the chemical composition formula) Eu with CaAlSiN is used ₃ The same operation as in example 5-1 was carried out except for the phosphor having the chemical composition of (1), and the luminance maintenance ratio of the phosphor was measured. The relative luminance (luminance maintenance ratio, 100% luminance at 25 ℃) at each temperature is shown in FIG. 31. The graph shown by a quadrangle in FIG. 31 shows the results of example 5-2.

Comparative examples 5 and 2

Except that 0.8 mol% (0.008 mol relative to 1 mol Ca in the chemical composition formula) Eu and Ca is used ₂ Si ₅ N ₈ The luminance maintenance ratio of the phosphor was measured in the same manner as in example 5-1 except for the phosphor having the chemical composition of (1). Relative luminance at each temperature (luminance maintenance ratio, at 25 ℃ C.)Luminance of (c) 100%) is shown in fig. 31. The curve shown by a circle in FIG. 31 shows the result of comparative example 5-2.

[ conclusion ]

As is clear from FIG. 30, phosphor Ca of example 5-1 ₃ Sc ₂ Si ₃ O ₁₂ Has a smaller temperature dependence than that of the phosphor YAG: ce of comparative example 5-1. As is clear from FIG. 31, the phosphor CaAlSiN of example 5-2 ₃ Temperature dependence of (2) phosphor Ca in comparison with comparative example 5-2 ₂ Si ₅ N ₈ Has a small temperature dependence. That is, the luminance maintenance ratio of the luminance at 150 ℃ to the luminance at 25 ℃ is high. Therefore, it is presumed that in a display device using these luminance maintaining phosphors, the color fluctuation of light emitted from the phosphors with respect to temperature is small, and it is possible to prevent the color of an image displayed under different temperature conditions from being deviated from a target color.

Industrial applicability

The present invention can be used in any industrial field, and is particularly suitable for use in indoor and outdoor lighting using light emitting elements such as LEDs, image forming apparatuses such as full-color displays, and the like.

The present invention has been described in detail with reference to the specific embodiments, but it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.

In addition, the present application is based on Japanese patent application filed on 18 th 3 th 2005 (Japanese patent application No. 2005-080033), japanese patent application filed on 28 th 3 th 2005 (Japanese patent application No. 2005-092976), japanese patent application filed on 31 th 3 th 2005 (Japanese patent application No. 2005-103148), japanese patent application filed on 24 th 5 th 2005 (Japanese patent application No. 2005-151175) and Japanese patent application filed on 17 th 6 th 2005 (Japanese patent application No. 2005-178377), and the entire contents of these are supported by reference.

Claims (13)

1. A light-emitting device comprising a light source for emitting light when a drive current is passed therethrough, and at least one wavelength conversion material for absorbing at least a part of the light emitted from the light source and emitting light having a wavelength different from that of the light, wherein the light-emitting device is characterized in that the emission intensity is 17.5A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (2) is denoted as x ₁ (17.5) the chromaticity coordinate value y is denoted as y ₁ (17.5) and will be at 70A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (A) is denoted as x ₁ (70) And the chromaticity coordinate value y is recorded as y ₁ (70) When x is above ₁ (17.5)、y ₁ (17.5)、x ₁ (70) And y ₁ (70) Satisfies the following formulae (D) and (E),

-0.006≤x ₁ (17.5)-x ₁ (70)≤0.006 (D)

-0.006≤y ₁ (17.5)-y ₁ (70)≤0.006 (E)。

2. a light emitting device comprises a light source for emitting light when a drive current is applied, and a light emitting element for absorbing at least a part of the light emitted from the light source and emitting light having a wavelength equal to or higher than that of the light emitted from the light sourceAt least one wavelength conversion material of light with different wavelengths, wherein the efficiency of the light emitting device is 32lm/W or more, the average color rendering index Ra is 85 or more, and when the average color rendering index Ra is 17.5A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (A) is denoted as x ₁ (17.5) y is denoted by y ₁ (17.5) and will be at 70A/cm ² The chromaticity coordinate value x of the emitted light obtained by the driving current density of (A) is denoted as x ₁ (70) And y is denoted as y ₁ (70) The difference [ x ] between the chromaticity coordinate values x and y ₁ (17.5)-x ₁ (70)]And [ y ₁ (17.5)-y ₁ (70)]Satisfying the following formulae (F) and (G),

-0.01≤x ₁ (17.5)-x ₁ (70)≤0.01 (F)

-0.01≤y ₁ (17.5)-y ₁ (70)≤0.01 (G)。

3. the light-emitting device according to claim 2, wherein the light-emitting device has a specific color rendering index R ₉ Is 64 or more.

4. The light-emitting device according to any one of claims 1 to 3, wherein a phosphor mixture of two or more kinds of phosphors is used as the wavelength conversion material, and the luminance of fluorescence obtained by excitation with blue light having a peak wavelength of 455nm at 25 ℃ is represented by BR (25) and chromaticity coordinate value x is represented by x for the phosphor mixture used ₂ (25) And recording the chromaticity coordinate value y as y ₂ (25) The luminance of fluorescence obtained by excitation with blue light having a peak wavelength of 455nm at 125 ℃ is represented by BR (125), and the chromaticity coordinate value x is represented by x ₂ (125) And the chromaticity coordinate value y is recorded as y ₂ (125) When, atBR (25), x ₂ (25)、y ₂ (25) And BR (125), x ₂ (125)、y ₂ (125) Satisfying the following formulae (A), (B) and (C),

0.85≤BR(125)/BR(25)≤1.15 (A)

-0.03≤x ₂ (25)-x ₂ (125)≤0.03 (B)

-0.03≤y ₂ (25)-y ₂ (125)≤0.03 (C)。

5. the light-emitting device according to any one of claims 1 to 4, wherein the wavelength conversion material contains at least one green phosphor having a peak of fluorescence intensity in a wavelength range of 500nm to 550 nm.

6. A light-emitting device according to any one of claims 1 to 5, wherein the wavelength conversion material contains at least one red-based phosphor having a peak of fluorescence intensity in a wavelength range of 610nm to 680 nm.

7. A lighting device comprising the light-emitting device according to any one of claims 1 to 6.

8. An image display device comprising the light-emitting device according to any one of claims 1 to 6.

9. A white light emitting device comprising a light source and at least one wavelength conversion material which absorbs at least a part of light emitted from the light source and emits light having a wavelength different from that of the light, the white light emitting device emitting white light containing the light emitted from the wavelength conversion material, wherein the white light emitting device is characterized in that the maximum emission intensity in a predetermined wavelength range of 500nm to 650nm in the emission spectrum of the white light is 150% or less of the minimum emission intensity in the predetermined wavelength range.

10. The white light emitting device of claim 9, wherein the luminance of the wavelength conversion material at 100 ℃ is 80% or more of the luminance of the wavelength conversion material at 25 ℃.

11. The white light emitting device according to claim 9 or 10, wherein an absorbance of the wavelength conversion material to light of an emission peak wavelength of the light source is 50% or more, and an internal quantum efficiency of the wavelength conversion material is 40% or more.

12. A lighting device comprising the white light emitting device according to any one of claims 9 to 11.

13. An image display device having pixels of red and at least one pixel of non-red color,

the red pixel has a red light-emitting device having a light-emitting element for a red pixel and a red phosphor having a phosphor temperature dependence coefficient of 85 or more,

the non-red pixels include a blue pixel having a light-emitting element for a blue pixel and/or a green pixel having a light-emitting element for a green pixel and a green phosphor having a phosphor temperature-dependent coefficient of 85 or more,

When the emission intensity of the red pixel at 25 ℃ is denoted as I (R, 25), the emission intensity at 100 ℃ is denoted as I (R, 100), the emission intensity of the non-red pixel at 25 ℃ is denoted as I (N, 25), and the emission intensity at 100 ℃ is denoted as I (N, 100), the ratio of I (N, 100)/I (N, 25) to I (R, 100)/I (R, 25) is 90% or more.

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