GB2092366A - Color cathode ray tube - Google Patents
Color cathode ray tube Download PDFInfo
- Publication number
- GB2092366A GB2092366A GB8201972A GB8201972A GB2092366A GB 2092366 A GB2092366 A GB 2092366A GB 8201972 A GB8201972 A GB 8201972A GB 8201972 A GB8201972 A GB 8201972A GB 2092366 A GB2092366 A GB 2092366A
- Authority
- GB
- United Kingdom
- Prior art keywords
- glass
- phosphor
- face plate
- emission
- green
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
- H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
- H01J29/18—Luminescent screens
- H01J29/24—Supports for luminescent material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
- H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
- H01J29/18—Luminescent screens
- H01J29/30—Luminescent screens with luminescent material discontinuously arranged, e.g. in dots, in lines
- H01J29/32—Luminescent screens with luminescent material discontinuously arranged, e.g. in dots, in lines with adjacent dots or lines of different luminescent material, e.g. for colour television
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
- H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
- H01J29/18—Luminescent screens
- H01J29/185—Luminescent screens measures against halo-phenomena
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/86—Vessels; Containers; Vacuum locks
- H01J29/863—Vessels or containers characterised by the material thereof
Landscapes
- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
- Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
- Luminescent Compositions (AREA)
Abstract
A color cathode ray tube in which a neodymium oxide component is included either in the face plate glass or in a plate disposed in front of the face plate, the phosphor screen, having plural color phosphors formed on the inner surface of said face plate glass, includes a green phosphor having an emission peak in the wavelength region between 530 nm and 545 nm, the peak having a half-width value of 70-90 nm. The arrangement optimises image contrast and brightness characteristics. <IMAGE>
Description
SPECIFICATION
Color cathode ray tube
BACKGROUND OF THE INVENTION
Field of the invention
The present invention relates to a phosphor screen of a color cathode ray tube.
Description of the prior art
It has been proposed to reduce a transmittance of a face plate glass on a phosphor screen as an effective manner for improving image contrast of a phosphor screen of a color cathode ray tube.
Referring to Figure 1, the principle will be illustrated in detail.
Figure 1 is a sectional model of the phosphor screen of the color cathode ray tube, wherein the reference numeral (1) designates a face plate glass on an inner surface of which, three color phosphors (2) of red (R), green (G) and blue (B) are formed.
The following equations are given: El=Eo-Rp-Tf2 .. (1)
F1=FoTf . (II) (Il) wherein Eo represents an intensity of exterior incident light to the face plate glass (1) of the color cathode ray tube having the structure; E1 represents an intensity of reflective light reflected on the phosphor screen to emit out of the face plate glass (1); Tf represents a light transmittance of the face plate glass (1); Rp represents reflectance of the red (R), green (G), blue (B) three color phosphors (2); Fo represents an intensity of light emission of the three color phosphors and F1 represents an output of light emitted from the phosphor screen and passed through the face plate glass (I).A contrast c is defined by the equation: C = E1 + F1 . (Ill)
E1 Thus, the following equation is given by substituting (I) and (II) in (III).
Fo C = 1 + EoRp.Tf (lav) In precise calculation, it is necessary to apply factors caused by effects of reflection of exterior light on the surface of the face plate glass, multiple reflections in the face plate glass (1) and halation caused by scattered electrons. Thus, the effects are neglected because the effects are negligible.
In order to improve the contrast of images of the cathode ray tube, the light transmittance (Tf) of the face plate glass (1) must be reduced as clearly considered by the equation (IV).
The glass used as the face plate glass (1) of the cathode ray tube has been classified into a clear glass having a transmittance of 75% or more; a grey glass having a transmittance of 60 - 75% and a tint glass having a transmittance of 60% or less.
Figure 2 show typical spectral transmittance curves of (a) a clear glass, (b) a grey glass and (c) a tint glass and also emission spectra of the three color phosphors of red (R), green (G), blue (B).
On the other hand, as it is clearly found from Figure 2 and the equation (II), the output of light emitted from the phosphor screen as brightness of the phosphor screen decreases depending upon a decrease of the transmittance (Tf) of the face plate glass (1). This is opposite to the contrast. In view of the transmittance (Tf) of the face plate glass (1), both of the contrast characteristic of images and the brightness characteristic are not easily improved. The kind of the face plate glass (1) has been selected depending upon the weight of the contrast or the brightness characteristic.
It has been defined to give selective photo-absorption forthe face plate glass (1) in the region of small light emission energy as the wavelength region in roots of the emission spectra of the three color phosphors on the phosphor screen instead of the face plate glass having flat transmittance in visible wavelength region as shown in Figure 2 in order to overcome the difficulty for improving both the brightness and the contrast and to improve both the brightness characteristic and the contrast characteristic.
Figure 3 shows a spectral transmittance curve of the face plate glass (1) proposed for the aforementioned purposes. The face plate glass is formed by incorporating neodymium oxide (Nd2O3) (at 1.0 wt.%) in a glass formulation similar to those of the conventional clear glass (hereinafter referring to as Nd-containing glass).
The Nd-containing glass has main sharp absorption peak in 560-615 nm and sub-absorption peaks in 490 540 nm which is resulted by the specific characteristics of Nd203. The absorption peaks are quite sharp and accordingly, even though lighttransmittances in the other wavelength except the absorption peaks are remarkably high as those of the conventional clear glass, an average light transmittance in the all visible wavelength region is similar to those of the grey glass thereby contributing to the improvement of the contrast.
Figure 4 shows spectral transmittance curve (d) of the Nd-containing glass and emission spectra of the three color phosphors of red (R), green (G), blue (B) of the color cathode ray tube.
As it is clearly found by the relation of the positions of the emission spectra of the three color phosphors and the positions of the peaks of light absorption of the spectral transmittance curve (d) of the Nd-containing glass, the light emission energy of the phosphors of red (R) and blue (b) may be absorbed at a degree similar to that of the conventional clear glass, whereas the light emission energy of the green (G) phosphor gives relatively low peak emission spectral distribution whereby the light emission energy is highly absorbed by the specific absorption peaks of Nd203 to remarkably reduce the photo-output of the green (G) emission on the phosphor screen, i.e. the brightness of the green (G) emission on the phosphor screen in comparison with those of the clear glass.In order to overcome the disadvantage of the reduction of the brightness of the green (G) emission in the use of the Nd-containing glass, it is considered to use a rare earth green (G) phosphor such as Gd202S : Tb which has sharp linear emission spectrum at 540 - 560 nm and has not adsorption in the wavelength of the absorption of Nod203 However, this rare earth green (G) phosphor is remarkably expensive and the brightness of the emission of the phosphor as the emission factor of the phosphor is not satisfactory.
Summary of the invention
It is an object of the present invention to overcome the disadvantages of characteristics of a phosphor screen caused by using a Nd-containing glass as a face plate glass of a color cathode ray tube.
It is another object of the present invention to provide a color cathode ray tube which effectively impart the optimum brightness and chromaticity characteristics of an emission color when a green (G) rare earth phosphor having a band emission spectrum which is low cost and higher brightness in the case of the
Nd-containing glass.
The foregoing and other objects of the present invention have been attained by providing a color cathode ray tube which comprises a face plate glass containing neodymium oxide component; and a phosphor screen having plural color phosphors which is formed on the inner surface of said face plate glass wherein a green phosphor having 70 to 90 nm of emission spectral energy half-value width and a peak of an emission spectrum in the wavelength between 530 nm and 545 nm as the green phosphor of said phosphor screen.
Brief description of the drawings
Figure 1 is a sectional model of a phosphor screen of a color cathode ray tube;
Figure 2 shows typical spectral transmittance curves of various glasses;
Figure 3 shows a spectral transmittion curve of Nd-containing glass;
Figure 4 shows the relation of spectral transmittance of the Nd-containing glass and emission spectra of three color phosphor;
Figure 5 shows a spectral transmission of the Nd-containing glass and emission spectra of various band emission spectral green (G) phosphors having various peak wavelength;
Figure 6 shows the relation of positions of peak wavelengths of emission energy of the band emission spectral green (G) phosphor and a brightness of the phosphor screen and a region for color reproduction;;
Figure 7 shows chromaticity points of output of light emitted from the phosphor which is passed through a face plate glass made of the Nd-containing glass;
Figure 8 is a sectional model of a phosphor screen of a color cathode ray tube equipped with a front glass plate;
Figure 9 show spectral transmittance curves of the face plate glass and the front glass plate;
Figure 10 shows a spectral transmittance curve of the front glass plate made of the Nd-containing glass;
Figure 11 shows a spectral transmittance curve of the front glass plate made of the Nd-containing glass and emission spectra of various band emission spectral green (G) phosphors having various peak wavelengths; ;
Figure 12 shows the relation of positions of peak wavelengths of emission energy of the band emission spectral green (G) phosphor and brightness of the phosphor screen and region for color reproduction; and
Figure 13 shows chromaticity points of output of light emitted from the phosphor which is passed through the front glass plate made of the Nd-containing glass.
Detailed description of the preferred embodiments
Referring to Figures 5 to 7, one embodiment of the present invention will be illustrated.
Figure 5 shows a spectral transmittance curve (d) of the Nd-containing glass and light emission spectra of band type emission spectral green (G) phosphors having peaks of energy intensity at various positions of the green (G) wavelength region. The band type emission spectral green (G) phosphor can be sulfide green (G) phosphors having various energy half-value width. In Figure 5, the phosphor having about 76 nm of energy half-value width is used. Figures 6 and 7 show the variations of the output of light transmitted through a face plate glass made of the Nd-containing glass of the emission spectra of various band type emission spectral green (G) phosphors, that is the brightness of the phosphor screen for green (G) emission and the chromaticity points of the transmitted light.
In Figure 6, the reference (M) shows the relation of the position of peak of emission energy intensity of the band type emission spectral green (G) phosphor and the output of light given by transmitting emission energy in the all visible wavelength region through the face plate glass made of the Nd-containing glass, that is, the brightness of the phosphor screen for green (G) emission. It has the maximum value of the brightness at about 545 nm.
Figure 7 shows chromaticity points of the output light emitted from the red (R), green (G), blue (B) three color phosphors which is given by transmitting through the face plate glass made of the Nd-containing glass on a CIE chromaticity diagram wherein the reference (r) designates a chromaticity point for the conventional rare earth red (r) phosphor; the reference (b) designates the chromaticity point for the conventional sulfide type blue (B) phosphor and the reference (g) designates the chromaticity point of the output light emitted from the band type emission spectral green (G) phosphor. The chromaticity points are shifted to the arrow direction depending upon the shift of the positions of the peaks of the emission spectra to the shorter wavelength direction as shown in Figure 5.The triangular region surrounded by the three chromaticity points (g), (b), (r) ((b) and (r) are fixed) is a range for color reproduction of the phosphor screen of the color cathode ray tube. The characteristic of the phosphor screen is superior depending upon an increase of the area of the triangular region.
In Figure 6 the reference (L) shows the area of the triangular region (g), (b), (r) formed by shifting the chromaticity point (g) in the shift of the positions of the peaks of the emission spectrum of the band type emission spectral green (G) phosphor under the fixed chromaticity points (r), (b), that is, the variation of the region for color reproduction. The maximum value is at 530 nm in the region for color reproduction.
When the band type emission spectral green (G) phosphor is used in the color cathode ray tube having a face plate glass made of the Nd-containing glass, the position of the peak of emission energy intensity of the band type emission spectral green (G) phosphor are preferably set in the wavelength between 545 nm for the maximum brightness and 530 nm for the maximum region for color reproduction. If the position of the peak is out of the range, either the brightness characteristic or the color reproduction characteristic is remarkably deteriorated.
In the embodiment, the band type emission spectral green (G) phosphor having about 70 nm of the energy half-value width is used. According to many experiments for the phosphors having various energy half-value widths, the band type emission spectral green (G) phosphors having each energy half-value width of 70 - 90 nm can be used to attain the same effect when the position of peak of the energy intensity is between 530 nm and 545 nm.
In accordance with the present invention, a phosphor screen for satisfactory brightness characteristic and chromaticity characteristic can be obtained and the contrast characteristic is improved by using an economical band type emission spectral green (G) phosphor without using the rare earth green (G) phosphor which is expensive and causes a trouble for brightness characteristic in a color cathode ray tube using the Nd-containing glass. The cathode ray tube having superior commercial value can be provided.
The other embodiment of the present invention will be illustrated. In the embodiment, a front glass plate (3) is placed front of the face plate glass (1) as shown in Figure 8. The front glass plate (3) has substantially constant transmittance in the visible wavelength.
The following equations are given:
E2 = EoRpTf2.Tg2 . (V) F2 = Eo.Tf.Tg (VI) wherein Tg represents a transmittance of the front glass plate; Eo represents an intensity of exterior incident light; E2 represents an intensity of reflective light on the phosphor screen to emit through the face plate glass (1) and the front glass plate (3); Tf, Rp and Fo respectively represent the transmittance of the face plate glass (1), the reflectivity of the red (R), green (G), blue (B) three color phosphors (2) and an intensity of emission of the phosphors and F2 repesents output of light on the phosphor screen passed through the face plate glass.
The contrast C2 iS defined by the equation: C - E2 + F2 . (veil)
E2 Thus, the following equation is given by substituting (V) and (VI) in (VII).
C2 = 1 + Eo-Rp-Tf-Tg .. (Vlil) In comparison with the equation (IV) and (VIII), it is clearly understood to improve the contrast of the phosphor screen by the placement of the front glass plate (3).
Figure 9(a) shows one of spectral transmittance curve of a clear glass having a transmittance of about 85% used as a face plate glass. When a front glass plate (3) having a spectral transmittance curve (b) and a transmittance of about 82% is placed front of the face plate glass, the total transmittance TfxTg for the phosphor screen is about 70% to improve the contrast of the phosphor screen. (Figure 3 show light emission spectra of red (R), green (G), blue (B) three color phosphors of the color cathode ray tube together with the spectral transmittance curves.)
It is found in the equation (VII) when the transmittance Tg of the front glass plate is decreased the contrast is improved.
On the other hand, as it is clear from Figure 9 and the equation (VI), the output of light i.e., the brightness of the phosphor screen is decreased when the transmittance Tg of the front glass plate (3) is decreased. This is opposite to the contrast. In view of the transmittance (Tg) of the front glass plate (3), both of the contrast characteristic and the brightness characteristic are not easily improved.
It has been proposed to give selective photo-absorption for the front glass plate (3) in the region of small light emission region in roots of the emission spectra of the three color phosphors on the phosphor screen instead of the front glass plate having flat transmittion in visible wavelength region as shown in Figure 9 in order to overcome the difficulty for improving the brightness and the contrast and to improve both of the brightness characteristics and the contrast characteristic.
Figure 10 shows a spectral transmittance curve of the front glass plate (3) proposed for the aforementioned purpose. The front glass plate is formed by incorporating neodymium oxide (Nd203) at 1.0 wt.% in a glass formulation similar to those of the conventional clear glass.
When the front glass plate made of the Nd-containing glass is used, the brightness of the phosphor screen for green (G) emission is remarkably reduced by the two specific absorption band of Nd203 as described before.
In accordance with this embodiment, it provides a color cathode ray tube which comprises a face plate glass for a vacuum tube; a phosphor screen having plural color phosphors which is formed on the inner surface of said face plate glass; a front glass plate containing neodymium oxide component placed front of the face plate glass, wherein a green phosphor having 70 to 90 nm of emission spectral energy half-value width and a peak of an emission spectrum in the wavelength between 530 and 545 nm as the green phosphor of said phosphor screen.
Figure 11 shows a spectral transmittance curve (d) of the Nd-containing glass and light emission spectra of band type emission spectral green (G) phosphors having peaks of energy intensity at various positions of the green (G) wavelength region.
Figures 12 and 13 show variation of the output of light transmitted through the front glass plate made of the Nd-containing glass of the emission spectra of various band type emission spectral green (G) phosphors, that is the brightness of the phosphor screen for green (G) emission and the chromaticity points of the transmitted light.
In Figure 12, the reference (M) shows the relation of the position of peak of emission energy intensity of the band type emission spectral green (G) phosphor and the output of light given by transmitting emission energy in all visible wavelength region through the front glass plate made of the Nd-containing glass, that is, the brightness of the phosphor screen for green (G) emission. It has the maximum value of the brightness at about 545 nm.
Figure 13 shows chromaticity points ofthe output light emitted from the red (R), green (G), blue (B) three color phosphors which is given by transmitting through the front glass plate made of the Nd-containing glass on a CIE chromaticity diagram wherein the reference (r) designates a chromaticity point for the commercial rare earth red (R) phosphor; the reference (b) designates the chromaticity point for the conventional sulfide type blue (B) phosphor and the reference (g) designates the chromaticity point of the output light emitted from the band type emission spectral green (G) phosphor.The chromaticity points are shifted to the arrow direction depending upon the shift of the positions of the peaks of the emission spectra to the shorter wavelength direction as shown in Figure 1 The triangular region surrounded by the three chromaticity points (g), (b), (r) ((b) and (r) are fixed) is a range for color reproduction of the phosphor screen of the color cathode ray tube. The characteristic of the phosphor screen is superior depending upon an increase of the area of the triangular region.
In Figure 12, the reference (L) shows the area of the triangular region (g), (b), (r) formed by shifting the chromaticity point (g) of in the shift of the positions of the peaks of the emission spectrum of the band type emission spectral green (G) phosphor under the fixed chromaticity points (r), (b), that is, the variation of the region for color reproduction. The maximum value is at 530 nm in the region for color reproduction. When the band type emission spectral green (G) phosphor is used in the color cathode ray tube having a front glass plate made of the Nd-containing glass, the position of the peak of emission energy intensity of the band type emission spectral green (G) phosphor are preferably set in the wavelength between 545 nm for the maximum brightness and 530 nm for the maximum region for clor reproduction. If the position of the peak is out of the range, either the brightness characteristic or the color reproduction characteristic is remarkably deteriorated.
The same effect is found in the case of the use of the band type emission spectral green (G) phosphors having 70 - 90 nm of an energy half-value width when the position of peak of the energy intensity is between 530 nm and 545 nm.
In accordance with the embodiment, the same effect as that of the first embodiment is attained.
Claims (3)
1. A color cathode ray tube which comprises a face plate glass containing neodymium oxide component; and a phosphor screen having plural color phosphors which is formed on the inner surface of said face plate glass wherein a green phosphor having 70 to 90 nm of emission spectral energy half-value width and a peak of an emission spectrum in the wavelength between 530 nm and 545 nm as the green phosphor of said phosphor screen.
2. A color cathode ray tube which comprises a face plate glass for a vacuum tube; a phosphor screen having plural color phosphors which is formed on the inner surface of said face plate glass; and a front glass plate containing neodymium oxide component placed front of the face plate glass wherein a green phosphor having 70 to 90 nm of emission spectral energy half-value width and a peak of an emission spectrum in the wavelength between 530 nm and 545 nm as the green phosphor of said phosphor screen.
3. A cathode ray tube substantially as herein particularly described with reference to and as illustrated in
Figures 5 to 13 of the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1336681A JPS57126052A (en) | 1981-01-29 | 1981-01-29 | Cathode-ray tube |
| JP2072881A JPS57134848A (en) | 1981-02-12 | 1981-02-12 | Cathode-ray tube |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2092366A true GB2092366A (en) | 1982-08-11 |
| GB2092366B GB2092366B (en) | 1984-09-26 |
Family
ID=26349145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8201972A Expired GB2092366B (en) | 1981-01-29 | 1982-01-25 | Color cathode ray tube |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR860000969B1 (en) |
| DE (1) | DE3202565C2 (en) |
| GB (1) | GB2092366B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3245336A1 (en) * | 1982-12-08 | 1984-06-14 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Cathode-ray tube with a fluorescent layer |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL6504105A (en) * | 1965-04-01 | 1966-10-03 | ||
| DE1286539B (en) * | 1967-06-19 | 1969-01-09 | Jenaer Glaswerk Schott & Gen | Screen for color television tubes |
| NL174003C (en) * | 1973-03-08 | 1984-04-02 | Philips Nv | CATHODE JET TUBE FOR MONOCHROME DISPLAY OF IMAGES. |
| DE2448322A1 (en) * | 1974-10-10 | 1976-04-22 | Licentia Gmbh | CRT with green emitting screen phosphor - uses mixture of phosphors with green and yellow emission in specified ratio |
| JPS5814374B2 (en) * | 1979-03-20 | 1983-03-18 | 株式会社保谷硝子 | Green contrast filter for CRT display device |
| JPS56112050A (en) * | 1980-02-07 | 1981-09-04 | Kasei Optonix Co Ltd | Cathode ray tube |
| US4405881A (en) * | 1980-05-29 | 1983-09-20 | Mitsubishi Denki Kabushiki Kaisha | Color cathode ray tube including Nd2 O3 and Cr2 O3 in face glass |
-
1982
- 1982-01-09 KR KR8200067A patent/KR860000969B1/en active
- 1982-01-25 GB GB8201972A patent/GB2092366B/en not_active Expired
- 1982-01-27 DE DE3202565A patent/DE3202565C2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| KR830009638A (en) | 1983-12-22 |
| DE3202565C2 (en) | 1985-12-12 |
| KR860000969B1 (en) | 1986-07-23 |
| DE3202565A1 (en) | 1982-09-02 |
| GB2092366B (en) | 1984-09-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 746 | Register noted 'licences of right' (sect. 46/1977) |
Effective date: 20000126 |
|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20010125 |