KR20130023978A

KR20130023978A - Liquid crystal display device

Info

Publication number: KR20130023978A
Application number: KR1020110087111A
Authority: KR
Inventors: 김선웅; 김영웅; 김보라
Original assignee: 엘지디스플레이 주식회사
Priority date: 2011-08-30
Filing date: 2011-08-30
Publication date: 2013-03-08

Abstract

PURPOSE: A liquid crystal display is provided to prevent the color shift of LEDs by using the LEDs and a fluorescent material film. CONSTITUTION: An LED assembly(129) includes LEDs(Light Emitting Diodes)(129a) and a PCB(Printed Circuit Board)(129b). A fluorescent material film(300) is formed on a light guide plate(123). An optical sheet(121) is formed on the fluorescent material film. A liquid crystal panel(110) is formed on the optical sheet. The fluorescent material film changes the light of the LEDs into white light.

Description

[0001] Liquid crystal display device [0002]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device using LED as a light source.

Liquid crystal display devices (LCDs), which are used for TVs and monitors due to their high contrast ratio and are advantageous for displaying moving images, are characterized by optical anisotropy and polarization of liquid crystals. The principle of image implementation by

Such a liquid crystal display is an essential component of a liquid crystal panel bonded through a liquid crystal layer between two side-by-side substrates, and realizes a difference in transmittance by changing an arrangement direction of liquid crystal molecules with an electric field in the liquid crystal panel. do.

However, since the liquid crystal panel does not have its own light emitting element, a separate light source is required to display the difference in transmittance as an image. To this end, a backlight unit having a light source is disposed on the back of the liquid crystal panel.

The backlight unit uses a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp, and a light emitting diode (LED) as a light source.

Among them, LEDs are particularly widely used as light sources for displays with features such as small size, low power consumption, and high reliability.

Meanwhile, a general backlight unit is classified into a direct type method and an edge type method according to the arrangement of lamps. In the edge type method, one or a pair of light sources is provided with one or two or two pairs of light guide plates. The light source has a structure in which both sides of the light guide plate are disposed, and the direct type has a structure in which several light sources are disposed below the liquid crystal panel.

Here, the direct type has a limitation in thinning, and is mainly used in a liquid crystal display device in which brightness is more important than the thickness of the screen, and the edge type which is lighter and thinner than the direct type is such as a notebook PC or a monitor PC. It is mainly used in liquid crystal displays where thickness is important.

1 is a cross-sectional view of a liquid crystal display including a backlight unit of a general edge type using an LED as a light source.

As shown in the figure, a liquid crystal display device including a general edge type backlight unit 20 includes a liquid crystal panel 10, a backlight unit 20, a support main 30, a cover bottom 50, 40).

The liquid crystal panel 10 is a part that plays a key role in image expression and is composed of first and second substrates 12 and 14 bonded to each other with a liquid crystal layer interposed therebetween.

The backlight unit 20 is provided behind the liquid crystal panel 10.

The backlight unit 20 is arranged along the length direction of at least one edge of the support main 30, and includes a plurality of LEDs 29a and a PCB 29b on which the LEDs 29a are mounted. A white or silver reflecting plate 25 mounted on the bottom 50, a light guide plate 23 mounted on the reflecting plate 25, and an optical sheet 21 positioned above the reflecting plate 25.

The liquid crystal panel 10 and the backlight unit 20 have a top cover 40 surrounding the top edge of the liquid crystal panel 10 and a back surface of the backlight unit 20 in a state where the edges are surrounded by the support main 30 having a rectangular frame shape. Cover cover 50 to cover each is coupled in front and rear are integrated through the support main 30 as a medium.

In addition, reference numerals 19a and 19b denote polarizers attached to the front and rear surfaces of the liquid crystal panel 10 to control the polarization direction of light, respectively.

Meanwhile, the LED 29a has a structure in which a phosphor (not shown) is coated on an LED chip (not shown) that emits light, and the light emitted from the LED chip (not shown) excites the phosphor (not shown). By emitting light to the outside of the LED 29a, the phosphor (not shown) plays a very important role in the LED 29a.

However, until now, in order to apply a phosphor (not shown), a method of mixing a phosphor (not shown) with silicon (not shown) and then applying a phosphor (not shown) by a dispensing method is most widely used. However, at this time, the phosphor (not shown) mixed with silicon (not shown) is a specific LED (29a) in the process of applying a phosphor (not shown) through the dispensing method to each LED (29a) by the precipitation phenomenon The problem that the amount of the phosphor (not shown) is applied in small or large amounts occurs.

That is, it is very difficult to control the amount of phosphor (not shown) applied by the LED 29a.

Therefore, the color variation of the plurality of LEDs 29a is caused by the change in the amount of phosphors (not shown).

In addition, since the phosphor 29 (not shown) is located close to the LED chip (not shown), the LED 29a deteriorates the phosphor (not shown) by heat generated when driving the LED chip (not shown). It may cause a problem of reducing the efficiency of (not shown), or deepen the degradation of the LED (29a). Therefore, the lifetime and luminous efficiency of the LED 29a are reduced.

The problem of the LED 29a causes a problem of deterioration of display quality due to uneven brightness of the liquid crystal display device using the LED 29a as a light source of the backlight unit 20.

The present invention has been made to solve the above problems, and a first object of the present invention is to provide an improved backlight unit.

In addition, a second object of the present invention is to provide a plurality of LEDs that do not generate color deviation, and a third object of the present invention is to prevent a problem of deterioration of display quality due to uneven brightness of the liquid crystal display device.

In order to achieve the above-mentioned object, the present invention provides a liquid crystal display comprising: a light guide plate; An LED assembly arranged along a light incident surface of the light guide plate, the LED assembly including a plurality of LEDs emitting light toward the light incident surface, and a PCB on which the plurality of LEDs are mounted; A phosphor film seated on the light guide plate and surrounded by phosphors by first and second base films and sidewalls; An optical sheet positioned on the phosphor film; It includes a liquid crystal panel mounted on the plurality of optical sheets, and provides a liquid crystal display device for implementing the light emitted from the plurality of LEDs to white light.

In this case, the sidewall of the phosphor film has a thickness of 1 ~ 5mm, the first and second base film is a transparent acrylic resin, PMMA (polymethylmethacrylate), thermoplastic resin PET (polyethylene terephthalate), silicon oxide It is made of one selected from an inorganic material such as (SiO 2) or titanium oxide (TiO 2) or an aluminum (Al) material having a thickness of 20 nm or less.

The second base film positioned between the phosphor and the optical sheet has a haze characteristic, and the optical sheet includes a diffusion sheet, first and second light collecting sheets, and a reflective polarizing sheet.

In addition, the plurality of LEDs are blue LED, the phosphor of the phosphor film is a yellow phosphor or a mixture of red (R) and green (G) phosphor, the plurality of LEDs are UVLED, the phosphor of the phosphor film It is red (R), green (G), and blue (B) tricolor phosphor.

A light guide plate is further provided below the optical sheet.

As described above, according to the present invention, only blue light or UV is emitted from the plurality of LEDs of the backlight unit, and a phosphor film including phosphors is placed on the light guide plate, whereby blue light or UV emitted from the plurality of LEDs is emitted. By implementing white light in the process of passing through the phosphor film, through this, there is an effect that can prevent the color deviation of a plurality of LEDs, there is an effect that can implement the white light with excellent optical characteristics, the life of the LED And it is effective to improve the luminous efficiency.

Therefore, there is an effect that the problem of deterioration of display quality due to uneven brightness of the liquid crystal display device can be prevented from occurring.

1 is a cross-sectional view of a liquid crystal display including a backlight unit of a general edge type method using an LED as a light source.
2 is an exploded perspective view of a liquid crystal display device according to an embodiment of the present invention.
3 is an exploded perspective view of the liquid crystal panel of FIG. 2;
4 is an exploded perspective view of the backlight unit of FIG. 2;
5 is a cross-sectional view schematically showing a phosphor film according to an embodiment of the present invention.
Figure 6 is a schematic cross-sectional view showing a traveling path of light emitted from the LED according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

2 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is an exploded perspective view of the liquid crystal panel of FIG. 2.

As shown, the liquid crystal display comprises a liquid crystal panel 110, a backlight unit 120, a support main 130, a cover bottom 150, and a top cover 140.

First, the liquid crystal panel 110 will be described in more detail with reference to FIG. 3, which is an exploded perspective view of the liquid crystal panel 110. A plurality of data lines 218 are provided on one surface of the first substrate 112 called a lower substrate or an array substrate. ) And the gate line 216 cross each other to define the pixel P.

Thin film transistors T are provided at the intersections of these two lines to correspond one-to-one with the transparent pixel electrodes 220 provided in the pixel regions P. FIG.

In addition, the second substrate 114 facing the first substrate 112 with the liquid crystal layer 250 therebetween is called an upper substrate or a color filter substrate, and one surface of the first substrate 112 A grid-like black matrix 222 covering the pixel region P to expose only the pixel electrode 220 while covering non-display elements such as the data line 218, the gate line 216, and the thin film transistor T is formed. It is composed.

In addition, transparent common electrodes covering R (red), G (green), and B (blue) color filters 224 and all of them are sequentially arranged in order to correspond to the pixel areas P in the lattice. 226.

First and second polarizing plates 119a and 119b for selectively transmitting only specific light are attached to outer surfaces of the first second substrates 112 and 114, respectively.

Along the at least one edge of the liquid crystal panel 110, the gate and the data printed circuit board 117 are connected to each other via a connecting member 116 such as a flexible printed circuit board. It is flipped to the back surface of 150, and is in close contact.

Although not clearly shown in the drawings, the upper and lower alignment layers for determining the initial molecular alignment direction of the liquid crystal are interposed between the two substrates 112 and 114 and the liquid crystal layer 250. A seal pattern (not shown) is formed along the edges of both substrates 112 and 114 to prevent leakage of the liquid crystal layer 250 that is filled between the substrates 112 and 114.

Accordingly, the liquid crystal panel 110 is turned on by the thin film transistor T selected for each gate line 216 by the on / off signal of the thin film transistor T transferred to the gate line 216. When the image signal of the data line 218 is transmitted to the pixel electrode 220, the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode 220 and the common electrode 226. Indicates a difference.

In the liquid crystal display device according to the present invention, a backlight unit 120 is provided for supplying light from the rear surface of the liquid crystal display panel 110 so that the difference in transmittance of the liquid crystal panel 110 is externally expressed.

The backlight unit 120 includes an LED assembly 129 arranged along at least one edge length direction of the support main 130, a reflecting plate 125, a light guide plate 123 mounted on the reflecting plate 125, and an upper portion thereof. It includes a phosphor film 300 and the optical sheet 121 which is interposed with. The backlight unit 120 will be described in more detail later.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the top cover 140, the support main 130, and the cover bottom 150. The top cover 140 is the top and side surfaces of the liquid crystal panel 110. A rectangular frame having a cross section bent in a shape of “a” so as to cover an edge thereof is configured to open an entire surface of the top cover 140 to display an image implemented in the liquid crystal panel 110.

In addition, the cover bottom 150 on which the liquid crystal panel 110 and the backlight unit 120 are seated, and which is the basis for assembling the entire apparatus of the liquid crystal display device, has a horizontal surface surrounding the rear surface of the backlight unit 120 and a side at which edges thereof are vertically bent. Is done.

A support main 130 having a rectangular frame shape seated on the cover bottom 150 and surrounding the edges of the liquid crystal panel 110 and the backlight unit 120 is combined with the top cover 140 and the cover bottom 150.

The cover main body 130 may be referred to as a guide panel or a main support or a mold frame. The cover main body 130 may be referred to as a bottom cover or a bottom cover, I will.

On the other hand, the liquid crystal display of the present invention can prevent the luminance unevenness caused by the LED assembly 129 which is the light source of the backlight unit 120, the luminous efficiency of the LED assembly 129 is improved.

This is because the color deviation of the plurality of LEDs 129a mounted on the LED assembly 129 may be prevented. This will be described in more detail with reference to FIG. 4 below.

4 is an exploded perspective view of the backlight unit of FIG. 2.

As shown, the backlight unit 120 includes a white or silver reflecting plate 125 seated on the cover bottom (150 of FIG. 2), and an LED assembly 129 which is a light source arranged along the longitudinal direction of one edge thereof. The light guide plate 123 mounted on the reflector plate 125 and the phosphor film 300 and the optical sheet 121 mounted on the light guide plate 123 are formed.

The LED assembly 129 is a light source of the backlight unit 120 and is disposed at one side of the light guide plate 123 so as to face the light incident surface of the light guide plate 123. The LED assembly 129 includes a plurality of LEDs 129a, And a PCB 129b on which a plurality of LEDs 129a are mounted with a predetermined spacing.

In this case, the plurality of LEDs 129a may be UV LEDs or blue LEDs that emit ultraviolet light or blue light having a single wavelength of 240 to 470 nm.

The light guide plate 123 to which light emitted from the plurality of LEDs 129a is incident is uniformly spread over a wide area of the light guide plate 123 while the light incident from the LED 129a propagates through the light guide plate 123 by several total reflections. It spreads to provide a surface light source to the liquid crystal panel (110 of FIG. 2).

The light guide plate 123 is a planar shape made of a plastic material such as polymethylmethacrylate (PMMA), which is one of transparent materials capable of transmitting light, or polycarbonate (PC). (flat type) The light guide plate 123 is excellent in transparency, weather resistance, and colorability to induce light diffusion when light is transmitted.

In addition, the light guide plate 123 may include a pattern having a specific shape on the rear surface to supply a uniform surface light source. The pattern may be formed in various shapes such as an elliptical pattern, a polygon pattern, a hologram pattern, and the like in order to guide light incident into the light guide plate 123. The pattern is formed on the lower surface of the light guide plate 123 by a printing method or an injection method.

The reflecting plate 125 is positioned on the rear surface of the light guide plate 123 to improve the luminance of the light by reflecting the light passing through the rear surface of the light guide plate 123 toward the liquid crystal panel (110 of FIG. 2).

The optical sheet 121 on the upper part of the light guide plate 123 diffuses or condenses the light passing through the light guide plate 123 to inject a more uniform surface light source into the liquid crystal panel 110 (see FIG. 2). The first light collecting sheet 121b having the lenticular pattern, the second light collecting sheet 121c having the prism pattern, and the reflective polarizing sheet 121d are formed.

Here, each of the first and second light collecting sheets 121b and 121c is arranged adjacent to each other in a band shape so that a plurality of patterns having a shape of repeating hills and valleys are arranged in a row to protrude from the support layer. The sheets 121b and 121c are arranged so that the arrangement of each pattern is perpendicular to each other.

Therefore, the first and second light collecting sheets 121b and 121c collect the light having high luminance through the liquid crystal panel 110 of FIG. 2 positioned on the first and second light collecting sheets 121b and 121c.

The reflective polarizing sheet 121d may improve light efficiency by reproducing linearly polarized light that has not passed through the first polarizing plate 119a of FIG. 3.

That is, the reflective polarizing sheet 121d transmits some of the incident light and reflects the remaining light. The reflected light is scattered by the diffusion sheet 121a and the first and second light collecting sheets 121b and 121c. When the light is reproduced, some of the reproduced scattered light passes through the reflective polarizing sheet 121d again and the remaining light is reflected again, so that the reproduction of the light is continuously repeated. As a result, light loss can be minimized.

In particular, the liquid crystal display of the present invention is characterized in that the phosphor film 300 is interposed between the light guide plate 123 and the optical sheet 121, and therefore, the backlight unit 120 of the present invention has excellent white light. Will be implemented.

The phosphor film 300 includes a phosphor 310 (see FIG. 5), and the light passing through the light guide plate 123 excites the phosphor 310 (see FIG. 5) of the phosphor film 300 to form the phosphor 310 (FIG. 5). 5) to mix with the light emitted to produce white light.

That is, the plurality of LEDs 129a of the LED assembly 129 of the present invention emits blue light or UV, and blue light or UV is incident into the light guide plate 123 to pass through the light guide plate 123 with a uniform surface light source. do.

In this case, the surface light source passing through the light guide plate 123 is blue light or UV.

The blue light or UV passes through the phosphor film 300 positioned on the light guide plate 123 and is finally realized as white light.

Here, when the plurality of LEDs 129a are blue LEDs, the phosphor 310 of the phosphor film 300 is a yellow phosphor, and the yellow phosphor is cerium (Ce) having a wavelength of 530 to 570 nm as the main wavelength. It is preferable to use YAG: Ce (T3Al5O12: Ce) series phosphors which are doped yttrium (Y) aluminum (Al) garnets.

Alternatively, the red (R) phosphor and the green (G) phosphor may be mixed and used. The red (R) phosphor is composed of YOX (Y 2 O 3) composed of a compound of yttrium oxide (Y 2 O 3) and europium (EU) having a wavelength of 611 nm. The phosphor is a EU-based phosphor, and the green phosphor is a LAP (LaPo4: Ce, Tb) phosphor that is a compound of phosphoric acid (Po4), lanthanum (La), and terbium (Tb) having a wavelength of 544 nm. It is preferable. In addition, when the plurality of LEDs 129a are UVLEDs, the phosphors 310 (see FIG. 5) of the phosphor film 300 are red (R), green (G), and blue (B) tricolor phosphors. The white light may be realized by adjusting the mixing ratio of the green, green and blue phosphors.

In this case, the red (R) phosphor and the green (G) phosphor may preferably use the above-described phosphor, and the blue (B) phosphor may have barium (Ba), magnesium (Mg), and aluminum oxide having a wavelength of 450 nm. It is preferable to use a BAM blue (BaMgAl 10 O 17: EU) series phosphor which is a compound of the series and the compound of europium (EU).

Here, the dominant wavelength is referred to as the wavelength of the phosphor that generates the highest luminance in each of red (R), green (G), and blue (B).

As described above, only blue light or UV is emitted from the plurality of LEDs 129a, and the phosphor film 300 including the phosphor 310 (see FIG. 5) is positioned on the light guide plate 123 so that the plurality of LEDs ( Blue light or UV emitted from 129a is implemented to allow white light to pass through the phosphor film 300, thereby realizing white light having excellent optical characteristics.

This is because the color deviation of the plurality of LEDs 129a mounted on the PCB 129b can be prevented from occurring.

That is, the conventional LED (29a of FIG. 1) is used to apply a phosphor (not shown) on top of the LED chip (not shown) by mixing silicon (not shown) and phosphor (not shown) and then dispensing (dispensing). Therefore, it is difficult to control the amount of phosphor (not shown) applied to each LED (29a in FIG. 1) due to the precipitation phenomenon of the phosphor (not shown), and thus the phosphor (not shown) of each LED (29a in FIG. 1). There is a problem that the color deviation occurs because the amount of.

However, the LED 129a of the present invention includes a phosphor film 300 separately from the LED 129a, thereby realizing white light, and then dispensing after mixing silicon (not shown) and phosphor (not shown). By not having to apply a phosphor (not shown) through, it is possible to prevent the above problems from occurring due to the precipitation phenomenon of the phosphor (not shown).

In addition, in the backlight unit 120 of the present invention, since the LED chip (not shown) of the LED 129a and the phosphor 310 (see FIG. 5) are positioned at a predetermined interval, the lifespan and luminous efficiency of the LED 129a are increased. Is improved.

That is, when the phosphor 310 (see FIG. 5) and the LED chip (not shown) provided in the LED 129a are located close to each other, the heat generated from the LED chip (not shown) when the LED 129a is driven. There is a problem that the phosphor 310 (see FIG. 5) deteriorates. When the phosphor 310 (see FIG. 5) is deteriorated, the efficiency itself of the phosphor 310 (see FIG. 5) is lowered, and the entire degradation of the LED 129a is caused.

In contrast, the backlight unit 120 of the present invention is provided with a plurality of LEDs 129a and phosphors 310 (refer to FIG. 5) separately, and thus generated from an LED chip (not shown) by driving the LEDs 129a. It is possible to prevent the phosphor 310 (see FIG. 5) from being deteriorated by heat, thereby preventing the LED 129a itself from being deteriorated. Therefore, the lifespan and luminous efficiency of the LED 129a are finally improved.

5 is a cross-sectional view schematically showing a phosphor film according to an embodiment of the present invention.

As illustrated, the phosphor film 300 positioned on the light guide plate 123 of FIG. 4 has a structure in which the phosphor 310 is positioned between the first and second base films 320a and 320b.

In more detail, in the phosphor film 300, the phosphor 310 is positioned between the first and second base films 320a and 320b, and sidewalls are formed along edges of the first and second base films 320a and 320b. 320c is formed.

Here, the first and second base films 320a and 320b are made of a transparent acrylic resin, polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), which is a thermoplastic resin, and the first and second base films 320a. , 320b) may be made of an inorganic material such as silicon oxide (SiO 2) or titanium oxide (TiO 2) or an aluminum (Al) material having a thickness of 20 nm or less.

In this case, the second base film 320b positioned above the phosphor 310 may have a haze characteristic.

That is, the second base film 320b includes a light diffusing component such as a bead (not shown), or a fine pattern (not shown) is formed on the upper surface without including the bead (not shown). Can be configured.

Therefore, the white light implemented through the phosphor 310 may be partially prevented from passing through the phosphor film 300 toward the optical sheet 121 (see FIG. 4).

Here, the diffusion sheet (121a of FIG. 4) may be deleted from the optical sheet (121 of FIG. 4) positioned on the phosphor film 300 according to the haze characteristic of the second base film 320b.

The sidewall 320c is preferably made of the same material as the first and second base films 320a and 320b, and the thickness d of the sidewall 320c is preferably formed to have a thickness of 1 to 5 mm. Do.

In this case, when the thickness d of the sidewall 320c is less than or equal to 1 mm, the backlight unit (120 of FIG. 4) may be contaminated by out-gassing of the phosphor 310, and the thickness of the sidewall 320c may be If d) is 5 mm or more, the bezel area of the liquid crystal display may be widened.

The phosphor film 300 is formed by filling the phosphor 310 between the first and second base films 320a and 320b and the sidewalls 320c, or after coating the phosphor 310 on a separate film, the first And a lamination process of pressing the films coated with the second base films 320a and 320b and the phosphor 310 with a laminator.

6 is a cross-sectional view schematically showing a traveling path of light emitted from an LED according to an embodiment of the present invention.

As illustrated, the LED assembly 129 and the light guide plate provided on the reflecting plate 125, the light guide plate 123, and one side surface of the light guide plate 123 and include a plurality of LEDs 129a and PCB 129b. 123, the phosphor film 300 and the optical sheet 121 are stacked to form a backlight unit (120 of FIG. 4).

In addition, a liquid crystal panel 110 including a liquid crystal layer (not shown) is disposed between the backlight unit 120 and the first and second substrates 112 and 114 and an upper portion thereof. On each of the outer surfaces of the two substrates 112 and 114, polarizing plates 119a and 119b for selectively transmitting only specific light are attached.

Here, the optical sheet 121 includes a diffusion sheet 121a, first and second light collecting sheets 121b and 121c, and a reflective polarizing sheet 121d.

Blue light or UV light is emitted from the plurality of LEDs 129a of the LED assembly 129, and the emitted light F1 and F2 are incident into the light guide plate 123 through the light incident surface of the light guide plate 123.

In addition, the light F1 and F2 incident into the light guide plate 123 are uniformly spread in a wide area of the light guide plate 123 while traveling in the light guide plate 123 by a plurality of total reflections in the light guide plate 123. Emitted towards.

The light F1 and F2 emitted toward the phosphor film 300 are mixed with the light emitted by the phosphor (310 of FIG. 5) in the course of passing through the phosphor film 300, thereby realizing white light W1 and W2. Done.

That is, when the LED 129a is a blue LED, the blue light emitted from the LED 129a is a phosphor in which the yellow phosphor of the phosphor film 300 or the red (R) phosphor and the green (G) phosphor are mixed (310 in FIG. 5). In the process of passing through), the blue light passes through the yellow phosphor or the phosphor mixed with the red (R) phosphor and the green (G) phosphor (310 in FIG. 5), thereby allowing the yellow phosphor or the red (R) phosphor and the green (G) phosphor. Is mixed with the yellow light emitted by the mixed phosphor 310 (in FIG. 5), thereby realizing the white light W1 and W2.

When the LED 129a is a UVLED, the UV emitted from the LED 129a passes through the red (R), green (G), and blue (B) tricolor phosphors (310 in FIG. 5) of the phosphor film 300. In the process, UV is transmitted through the tri-color phosphor (310 in FIG. 5) and mixed with the light emitted by the tri-color phosphor (310 in FIG. 5) to implement the white light (W1, W2).

The white light W1 and W2 realized by transmitting the phosphor film 300 are emitted toward the optical sheet 121 to pass through the diffusion sheet 121a and the first and second light collecting sheets 121b and 121c. After being processed into, it is incident on the reflective polarizing sheet 121d, where only a part of the white light W1 and W2 incident on the reflective polarizing sheet 121d passes through the reflective polarizing sheet 121d and enters the liquid crystal panel 110. do.

Through this, the liquid crystal panel 110 may display an image of high brightness.

The remaining white light W2 that does not pass through the reflective polarizing sheet 121d is reflected toward the first and second light collecting sheets 121b and 121c.

The reflected white light W2 is regenerated by the white light W1 and W2 scattered by the diffusion sheet 121a and the first and second light collecting sheets 121b and 121c, and thus the regenerated scattered white light W1 and W2. Some of the white light W1 passes through the reflective polarizing sheet 121d and the other white light W2 is reflected again, so that the regeneration of the white light W1 and W2 is constantly repeated.

Therefore, the backlight unit (120 of FIG. 4) of the present invention continuously repeats the reproduction of the light (W1, W2) through the reflective polarizing sheet 121d, thereby minimizing the light loss, thereby realizing improved light efficiency compared to the conventional Done.

Particularly, the backlight unit (120 of FIG. 4) of the present invention allows only blue light or UV to be emitted from the plurality of LEDs 129a and includes a phosphor film 310 of FIG. 5 on the light guide plate 123. The position of the light emitting device 300 is positioned so that the white light W1 and W2 are realized while the blue light or UV emitted from the plurality of LEDs 129a passes through the phosphor film 300, thereby reducing the color deviation of the plurality of LEDs 129a. It can be prevented from occurring, it is possible to implement the white light (W1, W2) excellent in the light characteristics, and improve the lifetime and luminous efficiency of the LED (129a).

Therefore, it is possible to prevent the problem of deterioration of display quality due to uneven brightness of the liquid crystal display device.

Meanwhile, in the above description and the accompanying drawings, a side light method in which the LED assembly 129 is positioned on one side of the light guide plate 123 has been described. However, a plurality of LED assemblies 129 are disposed above the reflector plate 125. A direct type in which the dogs are arranged side by side is also possible, and in this case, the light guide plate 123 may be omitted.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

110: liquid crystal panel (112: first substrate, 114: second substrate)
119a and 119b: first and second polarizing plates
121: optical sheet (121a: diffusion sheet, 121b, 121c: first and second light collecting sheet, 121d: reflective polarizing sheet)
123: light guide plate, 125: reflecting plate
129: LED assembly (129a: LED, 129b: PCB)
300: phosphor film

Claims

A light guide plate;
An LED assembly arranged along a light incident surface of the light guide plate, the LED assembly including a plurality of LEDs emitting light toward the light incident surface, and a PCB on which the plurality of LEDs are mounted;
A phosphor film seated on the light guide plate and surrounded by phosphors by first and second base films and sidewalls;
An optical sheet positioned on the phosphor film;
And a liquid crystal panel
Includes, wherein the phosphor film is a liquid crystal display device for implementing the light emitted from the plurality of LED to white light.

The method of claim 1,
The sidewall of the phosphor film has a thickness of 1 ~ 5mm.

The method of claim 1,
The first and second base films are inorganic materials including transparent acrylic resin, polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), silicon oxide (SiO 2) or titanium oxide (TiO 2) or less than 20 nm. Liquid crystal display device consisting of a selected one of the aluminum (Al) material consisting of a thickness of.

The method of claim 1,
The second base film positioned between the phosphor and the optical sheet has a haze characteristic.

The method of claim 1,
The optical sheet includes a diffusion sheet, first and second light collecting sheets and a reflective polarizing sheet.

The method of claim 1,
The plurality of LEDs are blue LEDs, and the phosphors of the phosphor film are yellow phosphors or a mixture of red and green phosphors.

The method of claim 1,
The plurality of LEDs are UVLEDs, and the phosphors of the phosphor film are red (R), green (G), and blue (B) tricolor phosphors.

The method of claim 1,
And a light guide plate under the optical sheet.