KR101710084B1

KR101710084B1 - Liquid crystal display device

Info

Publication number: KR101710084B1
Application number: KR1020150169498A
Authority: KR
Inventors: 권지희; 김창수; 이태경
Original assignee: 엘지디스플레이 주식회사
Priority date: 2015-11-30
Filing date: 2015-11-30
Publication date: 2017-02-24

Abstract

The present invention relates to a liquid crystal display device including an edge type backlight unit, and more particularly, to a lightweight liquid crystal display device. According to the present invention, a reflection plate is positioned on the bottom surface of a cover bottom and a plurality of optical sheets are spaced apart from the reflection plate at a predetermined distance so as to define a guide region of light emitted from an LED assembly, so that the light emitted from an LED fixed on one side surface of the cover bottom is implemented as a high-brightness surface light source. Accordingly, a liquid crystal display device including an edge type backlight unit, where light loss incurred by a light guide plate is prevented and the weight is reduced, can be provided and process costs can be reduced. In addition, a reflective polarizing film is positioned in front of a plurality of LEDs of the LED assembly, so that light efficiency is improved through the reflective polarizing film while a more uniform surface light source is provided to a liquid crystal panel. As a high color reproduction sheet is further included, a color reproduction ratio can be improved.

Description

[0001] Liquid crystal display device [0002]

The present invention relates to a liquid crystal display device including an edge type backlight unit, and more particularly to a lightweight liquid crystal display device.

A liquid crystal display device (LCD), which is advantageous for moving picture display and has a large contrast ratio and is actively used in TVs and monitors, exhibits optical anisotropy and polarization properties of a liquid crystal, And the like.

Such a liquid crystal display device has a liquid crystal panel in which a liquid crystal panel is interposed between two adjacent substrates through a liquid crystal layer as an essential component and changes the alignment direction of the liquid crystal molecules in an electric field in the liquid crystal panel to realize a difference in transmittance 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 having a light source is disposed on the back surface of the liquid crystal panel.

In general, an ordinary backlight unit is divided into an edge type and a direct type according to the arrangement structure of the lamp. The edge type has a structure in which one or a pair of lamps are disposed on one side of the light guide plate, Two or two pairs of lamps are disposed on both side portions of the light guide plate, and the direct type lamp has a structure in which several lamps are disposed under the optical sheet.

Here, the edge type is easier to manufacture than the direct type, and is advantageous in that it is thin, light in weight, and low in power consumption as compared with the direct type.

1 is a cross-sectional view of a liquid crystal display device using a general edge type backlight unit.

As shown in the figure, a typical liquid crystal display device includes a liquid crystal panel 10, a backlight unit 20, a guide panel 30, a cover bottom 50, and a case top 40.

The liquid crystal panel 10 is constituted by first and second substrates 12 and 14 which are in contact with each other with a liquid crystal layer therebetween.

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

The backlight unit 20 includes an LED assembly 29 arranged along the longitudinal direction of at least one side edge of the guide panel 30, a white or silver reflective plate 25 seated on the cover bottom 50, ) And a plurality of optical sheets 21 interposed therebetween.

The LED assembly 29 is formed on one side of the light guide plate 23 and includes a plurality of LEDs 29a emitting white light and an LED PCB 29b mounted on the LEDs 29a ).

The light guide plate 23 on which the light emitted from the plurality of LEDs 29a is incident diffuses evenly into the wide area of the light guide plate 23 while the light incident from the LED 29a travels in the light guide plate 23 by total reflection several times And provides a surface light source to the liquid crystal panel 10. [

The liquid crystal panel 10 and the backlight unit 20 have a case top 40 which surrounds the top edge of the liquid crystal panel 10 with the edges thereof being surrounded by a guide panel 30 having a rectangular shape, The cover bottoms 50 are integrally joined to each other through the guide panel 30.

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

On the other hand, the light emitted from the plurality of LEDs 29a is lost in the process of traveling through the light guide plate 23 by total reflection.

Reflection, refraction, transmission, or the like occurs at the boundary surface when the light is emitted from the light guide plate 23 into the air in the process of emitting light to the liquid crystal panel 10 through the light guide plate 23.

Even in this case, the light can not transmit 100% through the light guide plate 23, and a part thereof is lost.

Therefore, the liquid crystal display device using such an edge type backlight unit 20 is advantageous in that it is easier to manufacture than the direct type, thinner, lighter in weight and lower in power consumption than the direct type, and has a low luminous efficiency.

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a liquid crystal display device having improved light efficiency, light weight, and low power consumption.

A second object of the present invention is to provide a more uniform planar light source with a liquid crystal panel, and a third object is to improve the color reproduction rate.

In order to achieve the above object, the present invention provides a liquid crystal display comprising: a liquid crystal panel; An optical sheet positioned under the liquid crystal panel; An LED assembly disposed on a lower side of the optical sheet, the LED assembly including a plurality of LEDs and a PCB on which the plurality of LEDs are mounted; A bar-shaped reflective polarizing film positioned in front of the LED assembly; And a bottom surface positioned between the side where the LED assembly is located and the space between the optical sheet and the optical sheet, and the bottom surface is located closer to the optical sheet than the side where the LED assembly is located, And the light emitted from the plurality of LEDs realizes a surface light source through a guide region which is a spaced-apart space between the optical sheet and the bottom surface.

Here, the bar-shaped reflection type polarizing film is fixed in position by a sheet holder, and the sheet holder includes a support portion which is seated on the bottom surface, and a support portion which is protruded from the support portion, A first and a second guide, and a color reproduction sheet is positioned on the rear side of the bar-shaped reflection type polarizing film.

The bar-shaped reflection type polarizing film and the high color reproduction sheet are fixed in position by a sheet holder, and the sheet holder is supported on the bottom surface. Wherein the high color reproduction sheet is a selected one of a nano organic film (NOF) or a light absorption sheet (LAS).

When the LED includes a blue LED chip and a green phosphor, the nano organic film includes a nano red phosphor. In the case where the LED includes a blue LED chip, a yellow phosphor, and a red phosphor, And a light absorbing agent that absorbs light in a wavelength band between red light and green light.

As described above, according to the present invention, by defining the guide area of the light emitted from the LED assembly by positioning the reflection plate on the bottom surface of the cover bottom and positioning the plurality of optical sheets at a predetermined distance from the reflection plate, The light emitted from the LED fixed to the light guide plate is realized as a high-brightness surface light source, thereby preventing light loss caused by the light guide plate from being generated. Further, the liquid crystal display including the edge type backlight unit It is possible to provide a device, and the process cost can also be reduced.

In addition, by placing the reflective polarizing film in front of the LEDs of the LED assembly, it is possible to improve the light efficiency through the reflective polarizing film and to provide a more uniform surface light source to the liquid crystal panel.

In addition, by further including a high color reproduction sheet, the color reproduction rate can be improved.

1 is a sectional view of a liquid crystal display device using a general edge type backlight unit.
2 is a cross-sectional view schematically showing a liquid crystal display device according to a first embodiment of the present invention.
3 is a perspective view schematically illustrating a liquid crystal display device according to a second embodiment of the present invention.
FIG. 4 is a simulation result of the measurement of a light fraction of a liquid crystal display according to a second embodiment of the present invention. FIG.
FIG. 5 is a cross-sectional view schematically showing a modularized state of the liquid crystal display of FIG. 3;
6 is a cross-sectional view schematically showing a liquid crystal display device according to a third embodiment of the present invention.
7 is a simulation result of measuring a spectrum of light emitted from an LED depending on whether or not the nano organic film exists.
8 is a simulation result of measuring the spectrum of light emitted from the LED depending on whether or not the light-absorbing sheet is present.

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

- First Embodiment -

2 is a cross-sectional view schematically showing a liquid crystal display device according to a first embodiment of the present invention.

As shown in the drawing, a backlight unit (not shown) including a reflective plate 127, a reflective polarizing film 123, a plurality of optical sheets 121, and an LED assembly 129 composed of a plurality of LEDs 129a and a PCB 129b The liquid crystal panel 110 including the first and second substrates 120 and 120 and the first and second substrates 112 and 114 is surrounded by the guide panel 130. The cover bottom 150 is coupled to the backside of the liquid crystal panel 110, A case top 140 covering the top edge and the side surface of the cover top 130 is coupled to the guide panel 130 and the cover bottom 150.

Reference numerals 119a and 119b denote polarizers attached to the back and front surfaces of the liquid crystal panel 110 to control the polarization direction of light, respectively.

The cover bottom 150 includes a bottom surface 151 on which the reflection plate 127 is mounted and a side surface 153 vertically upwardly bent at an edge of the cover bottom 150. The LED assembly 129 is disposed on one side of the cover bottom 150 The position is fixed through an adhesive material (not shown) such as a double-sided tape.

The reflection type polarizing film 123 is disposed on the side surface 153 of the cover bottom 150 so that the reflection type polarizing film 123 reflects the light emitted from the plurality of LEDs 129a of the LED assembly 129 Only linearly polarized light is allowed to pass through, and the remaining light is reflected and reproduced.

A plurality of optical sheets 121 are seated on the reflective polarizing film 123.

The reflective polarizing film 123 is spaced apart from the reflective plate 127 that is seated on the bottom surface 151 of the cover bottom 150 so that the cover bottom 150 is separated from the bottom surface 151 And the side surface 153 of the LED assembly 129 to guide light emitted from the plurality of LEDs 129a of the LED assembly 129. [

Accordingly, when light is emitted from the plurality of LEDs 129a, the emitted light is totally reflected several times in the guide area A, and is uniformly spread in the guide area A of the cover bottom 150, .

At this time, the bottom surface 151 of the cover bottom 150 preferably has a different distance from the reflective polarizing film 123 depending on the position of the LED assembly 129, The bottom surface 151 of the cover bottom 150 of the edge portion is positioned away from the reflective polarizer film 123 and the bottom surface 151 of the cover bottom 150 of the other edge portion facing the one edge is a reflective polarizer So that it is positioned close to the film 123.

As a result, the light emitted from the LED 129a spreads more evenly into the guide area A, thereby realizing a planar light source having a uniform brightness.

As described above, the liquid crystal display according to the first embodiment of the present invention is configured such that the reflection plate 127 is positioned on the bottom surface 151 of the cover bottom 150 and the reflection type polarizing film 123 is reflected from the reflection plate 127 The light emitted from the LED 129a fixed to one side of the cover bottom 150 can be detected by defining the guide area A of the light emitted from the LEDs 129a of the LED assembly 129, As a planar light source of high brightness.

That is, the backlight unit 120 according to the first embodiment of the present invention allows the plane light source implemented through the guide area A to pass through the reflective polarizing film 123 and the plurality of optical sheets 121 as they are, The problem that a part of light is lost at the boundary surface when the planar light source realized from the conventional light guide plate (23 in FIG. 1) goes out into the air can be solved.

In particular, by eliminating the light guide plate (23 in FIG. 1), it is possible to provide a liquid crystal display device including the edge type backlight unit 120 which can be made lighter, and the process cost can also be reduced.

- Second Embodiment -

FIG. 3 is a perspective view schematically showing a liquid crystal display device according to a second embodiment of the present invention, and FIG. 4 is a simulation result of measurement of a light blurring of the liquid crystal display device according to the second embodiment of the present invention.

3, the liquid crystal display includes a liquid crystal panel 110, a backlight unit 120, a guide panel 130 for modularizing the liquid crystal panel 110 and the backlight unit 120, a cover bottom 150, , And a case top (140).

The liquid crystal panel 110 is a part that plays a key role in image display and includes a first substrate 112 and a second substrate 114 which are bonded to each other with a liquid crystal layer interposed therebetween, .

At this time, a plurality of gate lines and data lines intersect to define the pixels on the inner surface of the first substrate 112, which is usually referred to as a lower substrate or an array substrate, although not shown in the drawing, A thin film transistor (TFT) is provided at each intersection and is connected in one-to-one correspondence with the transparent pixel electrode formed in each pixel.

On the inner surface of the second substrate 114 called an upper substrate or a color filter substrate, color filters of red (R), green (G), and blue (B) And a black matrix for covering non-display elements such as a gate line, a data line, and a thin film transistor. In addition, a transparent common electrode covering these elements is provided.

A polarizing plate (not shown) for selectively transmitting only specific light is attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

A printed circuit board 117 is connected to at least one edge of the liquid crystal panel 110 via a connection member 116 such as a flexible circuit board or a tape carrier package (TCP) And is properly brought into close contact with the side surface of the panel 130 or the back surface of the cover bottom 150.

When the thin film transistor selected for each gate line is turned on by the on / off signal of the gate driving circuit, the liquid crystal panel 110 transmits the signal voltage of the data driving circuit to the corresponding pixel electrode through the data line. The arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode to show a difference in transmittance.

And a backlight unit 120 for supplying light from the rear surface of the liquid crystal panel 110 so that a difference in transmittance represented by the liquid crystal panel 110 is externally displayed.

The backlight unit 120 includes an LED assembly 129, a bar-shaped reflective polarizing film 210, a white or silver reflective plate 127, and a plurality Of the optical sheet 121.

The LED assembly 129 is located on one side of the reflection plate 127 and includes a plurality of LEDs 129a and a PCB 129b on which a plurality of LEDs 129a are mounted with a predetermined interval.

The reflection plate 127 guides the light generated from the LED 129a and reflects the light toward the liquid crystal panel 110 to improve the brightness.

A plurality of optical sheets 121 spaced apart from each other by a predetermined distance above the reflection plate 127 include a diffusion sheet and at least one light collecting sheet and the like. The divergent light from the LED 129a through the diffusion sheet and the light collecting sheet And is incident on the liquid crystal panel 110 as a more uniform surface light source.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the case top 140, the guide panel 130 and the cover bottom 150. The case top 140 is disposed on the upper surface and the side surface of the liquid crystal panel 110, The top cover 140 is opened so that an image formed on the liquid crystal panel 110 is displayed.

The cover bottom 150, which is a basis for assembling the entire structure of the liquid crystal display device, has a rectangular plate shape with a vertically curved edge portion and has a bottom surface 151 adhered to the back surface of the backlight unit 120, And a side surface 153 whose edge is vertically bent upward.

At this time, the LED assembly 129 is made to have adhesiveness such as double-sided tape or the like on one side of the cover bottom 150 so that the light emitted from the plurality of LEDs 129a is directed from one side of the cover bottom 150 to the other side opposite to the side The location is fixed through the material (not shown).

A reflection plate 127 is mounted on the bottom surface 151 of the cover bottom 150 and a plurality of optical sheets 121 are positioned on the side surface 153 of the cover bottom 150.

The plurality of optical sheets 121 are spaced apart from the reflector 127 by a predetermined distance so that the cover bottom 150 can receive the light emitted from the LED assembly 129 through the bottom surface 151 and the side surface 153. [ A guide area A for guiding the guide area A is defined.

That is, the light emitted from the plurality of LEDs 129a fixed to one side of the cover bottom 150 is separated from the reflection plate 127 formed on the bottom surface 151 of the cover bottom 150 and the reflection plate 127 And spread evenly in the guide region (A) through the plurality of optical sheets (121) positioned in the interspace. Therefore, it is processed into a high-brightness surface light source, and is provided as a uniform surface light source to the liquid crystal panel 110.

At this time, the bottom surface 151 of the cover bottom 150 may have a different distance from the plurality of optical sheets 121 depending on the position where the LED assembly 129 is fixed, thereby realizing a more uniform surface light source.

That is, the bottom surface 151 of the cover bottom 150 close to the LED assembly 129 fixed to one side of the cover bottom 150 is located far from the plurality of optical sheets 121, The closer to the optical sheets 121, the closer to the optical sheet 121 is.

As a result, the distance between the optical sheets 121 and the bottom surface 151 of the cover bottom 150 becomes narrower from one edge of the LED assembly 129 to the other opposite edge.

At this time, in the liquid crystal display device, the light is emitted most from one edge of the cover bottom 150 where the LED assembly 129 is located, and the brightness is highest. In the liquid crystal display device according to the second embodiment of the present invention, The bottom surface 151 of the cover bottom 150 close to the LED assembly 129 is located far from the plurality of optical sheets 121 and is closer to the plurality of optical sheets 121 So that a large amount of light is emitted from the other edge of the cover bottom 150 located far away from the LED assembly 129 so that the edge of the cover bottom 150 away from the edge of the LED assembly 129 close to the LED assembly 129 and away from the LED assembly 129 So that uniform light can be emitted from all of the other edge portions.

Accordingly, the liquid crystal panel 110 is provided as a uniform surface light source.

In particular, in the liquid crystal display device according to the second embodiment of the present invention, a bar-shaped reflective polarizing film 210 is positioned in front of the LED assembly 129, 129a of the liquid crystal display device according to the second embodiment of the present invention, the light efficiency of the liquid crystal display device according to the second embodiment of the present invention is further improved.

At this time, the position of the reflective polarizing film 210 is fixed to the front of the plurality of LEDs 129a of the LED assembly 129 by the sheet holder 220.

The seat holder 220 includes a support 221 that is seated on the reflector 127 and a first and a second guides 223a and 223b that are protruded from the support 221 and spaced apart from each other at a predetermined distance, As shown in Fig.

The reflection type polarizing film 210 is inserted into the spacing region between the first and second guides 223a and 223b of the guide portion, and both sides thereof are supported and guided.

The sheet holder 220 is provided with at least two or more reflective polarizing films 210 along the longitudinal direction of the bar-shaped reflective polarizing film 210, (129a).

A rectangular panel-shaped guide panel 130 covering the edges of the liquid crystal panel 110 and the backlight unit 120 is mounted on the top cover 140 and the cover 120, And is combined with the bottoms 150 to modularize the liquid crystal panel 110 and the backlight unit 120.

In this case, the case top 140 may be referred to as a top cover or a top case, and the guide panel 130 may be referred to as a support main or a main support or a mold frame. The cover bottom 150 may be referred to as a bottom cover or a bottom cover I will.

At this time, the backlight unit 120 having the above-described structure is generally called an edge type, and a plurality of LEDs 129a may be arranged in a multiple layer on the PCB 129b according to the purpose. Further, it is also possible to provide a plurality of LED assemblies 129 each in a corresponding manner so as to interpose the cover bottoms 150 along opposite side edges facing each other.

As described above, the liquid crystal display according to the second embodiment of the present invention is configured such that the reflection plate 127 is positioned on the bottom surface 151 of the cover bottom 150, and a plurality of optical sheets 121 are arranged on the bottom surface 151 of the cover bottom 150 from the reflection plate 127 The light emitted from the LED 129a fixed on one side of the cover bottom 150 can be realized as a high brightness surface light source by defining the guide area A of the light emitted from the LED assembly 129 .

That is, the backlight unit 120 according to the second embodiment of the present invention allows the planar light source realized through the guide area A to pass through the plurality of optical sheets 121 as it is, When the planar light source implemented by the light source is moved into the air, the problem that some light is lost at the interface can be solved.

In particular, it is possible to provide a liquid crystal display device including the edge type backlight unit 120 which is lightweight by not requiring the light guide plate (23 in FIG. 1), and also the process cost can be reduced.

The reflection type polarizing film 210 is disposed in front of the plurality of LEDs 129a of the LED assembly 129 so that the light efficiency is improved through the reflective polarizing film 210 and the liquid crystal panel 110 Thereby providing a more uniform planar light source.

In other words, it can be confirmed that a uniform light amount is measured over the entire screen by confirming the simulation result of measuring the light fraction of the liquid crystal display device according to the second embodiment of the present invention shown in FIG.

Particularly, it can be confirmed that a certain amount of light is concentrated at the center of the screen. If the light amount is concentrated at the central portion of the screen as described above, the user feels a brighter image to be realized in the screen, .

5 is a cross-sectional view schematically showing a modularized state of the liquid crystal display device of FIG.

As shown, a backlight unit (not shown) including a reflective plate 127, a reflective polarizing film 210, a plurality of optical sheets 121, and an LED assembly 129 comprising a plurality of LEDs 129a and a PCB 129b The liquid crystal panel 110 including the first and second substrates 120 and 120 and the first and second substrates 112 and 114 is surrounded by the guide panel 130 and has a bottom surface 151 and a side surface 153 And a case top 140 covering a top edge and a side surface of the liquid crystal panel 110 are coupled to the guide panel 130 and the cover bottom 150.

The cover bottom 150 includes a bottom surface 151 on which the reflection plate 127 is mounted and a side surface 153 vertically upwardly bent at an edge of the cover bottom 150. The LED assembly 129 is mounted on the cover bottom 150 (Not shown) such as a double-sided tape on its side.

A plurality of optical sheets 121 are positioned on the side surface 153 of the cover bottom 150. That is, a plurality of optical sheets 121 are placed on the bottom surface 151 of the cover bottom 150, 121 are spaced apart by a predetermined distance.

The cover bottom 150 defines a guide area A for guiding light emitted from the plurality of LEDs 129a of the LED assembly 129 through the bottom surface 151 and the side surface 153. [

At this time, the bottom surface 151 of the cover bottom 150 is formed to have a different distance from the plurality of optical sheets 121 according to the position of the LED assembly 129, The light is uniformly spread into the guide area A of the cover bottom 150 without being incident on the sheet 121, thereby realizing a planar light source having uniform luminance.

In particular, in the liquid crystal display device according to the second embodiment of the present invention, a bar-shaped reflective polarizing film 210 is positioned in front of the LED assembly 129, (Not shown).

Here, the reflective polarizing film 210 may be formed by incorporating a polarizer having a certain polarization axis in a laminated structure of dielectric thin films having different refractive indexes, or may be formed of a reflective film such as aluminum (Al), silver (Ag) And a wire grid polarizer in which fine linear metal patterns such as chromium (Cr) are arranged side by side in one direction.

The light efficiency is improved through the reflective polarizing film 210 having such a configuration. That is, the reflection type polarizing film 210 transmits a part of the incident light and reflects the remaining light. The reflected light is reproduced as scattered light, and a part of the scattered light is reflected again by the reflection type polarizing film 210, And the remaining light is reflected again.

Therefore, the reproduction of light is continuously repeated, and as a result, the light efficiency is improved.

That is, the first polarized light of the light emitted from the LED 129a is transmitted through the reflective polarizing film 210 and enters the guide area A, while the second polarized light perpendicular to the first polarized light is incident on the reflective polarizing film 210 And is reproduced as scattered light.

Of the light reproduced by the scattered light, the first polarized light is again transmitted through the reflective polarizing film 210, and the second polarized light is again reproduced as scattered light, so that the light efficiency is improved.

At this time, the reflection type polarizing film 210 has the same polarization axis as that of the first polarizing plate 119a attached to the lower portion of the liquid crystal panel 110, so that the first polarized light transmitted through the reflection type polarizing film 210 is guided A of the liquid crystal panel 110. The planar light sources emitted from the guide area A at this time are all made of the first polarized light and are emitted to the lower part of the liquid crystal panel 110 The first polarizing plate 119a positioned thereon is transmitted as it is.

Therefore, among the surface light sources emitted from the guide area A, there is no light lost by the first polarizing plate 119a, and high brightness can be realized.

- Third Embodiment -

FIG. 6 is a cross-sectional view schematically showing a liquid crystal display device according to a third embodiment of the present invention. FIG. 7 is a simulation result of a spectrum of light emitted from an LED depending on whether a nano- And the spectrum of the light emitted from the LED, which varies depending on whether or not the light-absorbing sheet is present, is measured.

As shown in FIG. 6, includes a reflective plate 127, a reflective polarizing film 210, a plurality of optical sheets 121, and an LED assembly 129 composed of a plurality of LEDs 129a and a PCB 129b The liquid crystal panel 110 including the backlight unit 120 and the first and second substrates 112 and 114 is surrounded by the guide panel 130 and has a bottom surface 151 and a side surface 153, And a case top 140 covering a top edge and a side surface of the liquid crystal panel 110 are coupled to the guide panel 130 and the cover bottom 150.

The cover bottom 150 defines a guide area A for guiding the light emitted from the plurality of LEDs 129a of the LED assembly 129 through the bottom surface 151 and the side surface 153. [

A bar-shaped reflective polarizing film 210 is positioned in front of the LED assembly 129, and the reflective polarizing film 210 is fixed in position by the sheet holder 220.

The reflective polarizing film 210 transmits only the specific linearly polarized light among the light emitted from the plurality of LEDs 129a of the LED assembly 129, and reflects and reflects the remaining linearly polarized light.

Particularly, in the liquid crystal display device according to the third embodiment of the present invention, the outer side of the reflection type polarizing film 210, that is, one side of the reflection type polarizing film 210 faces the plurality of LEDs 129a of the LED assembly 129, , And a bar-shaped high color reproduction sheet 230 is positioned outside (i.e., behind) the other side of the reflective polarizing film 210.

The high color reproduction sheet 230 is fixed in position by the sheet holder 220 fixing the position of the reflective polarizing film 210. To this end, the sheet holder 220 includes a support portion 221 And first and second guide portions protruding from the support portion 221. [

The first and second guide portions 223a, 223b, and 223c are protruded from the support portion 221 so as to face each other with a predetermined distance therebetween. The first and second guide portions 223a And 223b define a first guide portion, and neighboring second and third guides 223b and 223c define a second guide portion.

The reflection type polarizing film 210 is inserted into a spaced-apart region between the first and second guides 223a and 223b of the first guide portion to support both sides thereof. The color reproduction sheet 230 is attached to the second and third guides 223b, and 223c, and both sides thereof are supported.

Here, the high color reproduction sheet 230 may be made of a selected one of a nano organic film (NOF) and a light absorption sheet (LAS).

The nano organic film includes a nano red phosphor when a plurality of LEDs 129a of the LED assembly 129 are composed of a blue LED chip and an LED including a green phosphor. The nano organic film including a nano red phosphor is a blue LED chip And the green phosphor, the blue light absorbs a lot of green light.

7, light having a blue peak wavelength and a green peak wavelength is emitted from the LED 129a including the blue LED chip A and the green phosphor in the graph, but the light having the blue peak wavelength and the green peak wavelength is emitted toward the front of the LED 129a When a nano organic film containing a nano red phosphor is placed, the half-width of the green peak wavelength of B on the graph is shifted by the nano red phosphor among the light transmitted through the nano organic film, and the short wavelength is shifted.

This is because the nano red phosphor absorbs the green light to a greater extent than the blue light and absorbs the green light, thereby reducing the half width of the green light and shifting the short wavelength, thereby emitting red light with improved color purity.

As a result, the light emitted from the plurality of LEDs 129a is emitted as blue light, green light having a smaller half width, and red light having improved color purity in the process of transmitting the nano organic film.

Therefore, blue light, green light and red light having improved color purity are incident on the guide area A, and blue light, green light and red light having improved color purity are mixed in the guide area A in the guide area A, The improved white light is emitted to the surface light source.

Therefore, the liquid crystal display device according to the third embodiment of the present invention realizes white light having excellent optical characteristics. Particularly, even when the LED 129a including the blue LED chip having a low color reproduction rate is used as the light source of the backlight unit 120, the color reproduction rate is improved, so that the color reproduction rate is improved while realizing high brightness.

Thus, the color reproduction rate of NTSC can be more satisfied. Therefore, it is possible to provide a high quality screen to the user.

Here, when the plurality of LEDs 129a are made of a blue LED chip, the nano organic film can realize red light and green light having improved color purity including nano red phosphor and nano green phosphor.

The light absorbing sheet is a sheet containing a light absorber, and absorbs light in a wavelength band between red light and green light, thereby improving the color reproduction rate of the liquid crystal display device.

The light absorbing sheet absorbs and separates overlapping wavelength regions of the green light and the red light among the light emitted from the LED 129a including the blue LED chip and the yellow phosphor + the red phosphor, thereby realizing the green light and the red light having improved color purity.

That is, referring to FIG. 8, the light emitted from the LED 129a has a blue peak wavelength, and an overlapping region exists between the red and green wavelength bands.

However, the light-absorbing sheet has a strong absorption peak at the wavelength band between red and green. Accordingly, when the light absorbing sheet is positioned in front of the LED 129a, the overlapping region between the red and green wavelength ranges is removed, thereby realizing green light and red light with improved color purity.

As described above, the liquid crystal display according to the third embodiment of the present invention is configured such that the reflection plate 127 is positioned on the bottom surface 151 of the cover bottom 150, and a plurality of optical sheets 121 The LED 129a is fixed at one side 153 of the cover bottom 150 by defining the guide region A of the light emitted from the plurality of LEDs 129a of the LED assembly 129 The emitted light is realized as a high-brightness surface light source.

That is, the backlight unit 120 according to the third embodiment of the present invention allows the planar light source realized through the guide area A to pass through the plurality of optical sheets 121 as it is, When the planar light source implemented by the light source is moved into the air, the problem that some light is lost at the interface can be solved.

Further, by further including the high color reproduction sheet 230, the color reproduction rate of white light incident from the backlight unit 120 to the liquid crystal panel 110 can be improved, thereby satisfying the color reproduction rate of NTSC more satisfactorily . Therefore, it is possible to provide a high quality screen to the user.

In the meantime, in the present invention, a plurality of LEDs 129a are mounted on the PCB 129b at a predetermined interval and the LEDs 129 are mounted on the PCB 129b at a predetermined interval And an LED assembly mounted apart from the LED chip and covering a plurality of LED chips with a bar lens corresponding to the longitudinal direction of the PCB.

The liquid crystal display device using the LED assembly including the bar lens as a light source may support the bar lens through the reflective polarizing film 210 and / or the sheet holder 220 fixing the color reproduction sheet 230.

That is, when the LED assembly including the bar lens is driven for a long time, the bar lens may be detached from the PCB 129b due to thermal expansion. At this time, the reflective polarizing film 210 and / or the color reproduction sheet 230 may be fixed So that the sheet holder 220 supports the bar lens.

For this purpose, it is preferable that the sheet holder 220 is placed in close contact with the bar lens.

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

110: liquid crystal panel (112, 114: first and second substrates)
119a and 119b: first and second polarizing plates
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit (120), a backlight unit (121), an optical sheet (127), a reflector (129)
130: Guide panel
140: Case Top
150: cover bottom 151 (bottom surface, 153: side surface)
210: reflective polarizing film
220: Seat holder
A: Guide Area

Claims

A liquid crystal panel;
An optical sheet positioned under the liquid crystal panel;
An LED assembly disposed on a lower side of the optical sheet, the LED assembly including a plurality of LEDs and a PCB on which the plurality of LEDs are mounted;
A bar-shaped reflective polarizing film positioned in front of the LED assembly;
A high color reproduction sheet positioned on the rear side of the bar-shaped reflection type polarizing film;
And a bottom surface positioned between the side where the LED assembly is located and the space between the optical sheet and the optical sheet, and the bottom surface is located closer to the optical sheet than the side where the LED assembly is located, And a cover tab;
A support member that is seated on the bottom surface, and first to third guides that protrude from the support member and are spaced apart from each other by a predetermined distance,
/ RTI >
The reflection type polarizing film is inserted in a state in which the upper end of the reflection type polarizing film is exposed in a spaced-apart area between the first and second guides, and the high color reproduction sheet is inserted in the spacing region between the second and third guides, The upper end of the sheet is inserted in an exposed state,
At least two or more of the sheet holders are provided along the longitudinal direction of the reflective polarizing film,
Wherein the light emitted from the plurality of LEDs implements a surface light source through a guide region that is a spaced-apart space between the optical sheet and the bottom surface.

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The method according to claim 1,
Wherein the high color reproduction sheet is a selected one of a nano organic film (NOF) or a light absorption sheet (LAS).

6. The method of claim 5,
Wherein the nano organic film comprises a nano red phosphor when the LED comprises a blue LED chip and a green phosphor.

6. The method of claim 5,
Wherein the light absorbing sheet comprises a light absorbing material that absorbs light in a wavelength band between red light and green light when the LED comprises a blue LED chip, a yellow phosphor, and a red phosphor.