KR20140088934A - Liquid crystal display device - Google Patents

Abstract

The present invention relates to a liquid crystal display device and, more particularly, to a liquid crystal display device including a backlight unit having improved optical efficiency. A first feature of the present invention is to interpose a reflective polarization film between an LED and an incident surface of a light guide plate and emit light such that the LED has asymmetric distribution. A second feature of the present invention is to form a reflective polarization pattern on a rear surface of a light guide plate. Accordingly, the liquid crystal display device according to the present invention can improve optical efficiency, and thus can provide a liquid crystal panel with a larger amount of light to realize high luminance and reduce power consumption of the liquid crystal display device. Further, the present invention can reduce material costs of the reflective polarization film and reduce process costs as compared with a case in which the reflective polarization film is located under a first polarization plate or interposed between an LED and a light guide plate.

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 including a backlight unit with improved light efficiency.

2. Description of the Related Art In recent years, the display field has rapidly developed in line with the information age. In response to this trend, a flat panel display device (FPD) having a thinness, light weight, A plasma display panel (PDP), an electroluminescence display device (ELD), and a field emission display device (FED) : CRT).

In particular, the liquid crystal display device is superior in moving picture display and is most actively used in the fields of notebook computers, monitors, and TVs due to its high contrast ratio. The liquid crystal display device is an element that does not have a self- .

Accordingly, a backlight unit having a light source is provided on the back surface of the liquid crystal panel, and light is emitted toward the front surface of the liquid crystal panel, thereby realizing an image of brightness that can be recognized only through the backlight unit.

Meanwhile, a general backlight unit is divided into a side light type and a direct type type according to the arrangement structure of the light sources. In the sidelight type, one or a pair of light sources are disposed on one side of the light guide plate Or two or two light sources are disposed on both side portions of the light guide plate, and the direct type system has a structure in which several light sources are disposed under the optical sheet.

Here, the sidelight method is advantageous in that it is easier to manufacture than the direct-type method, and is thinner than the direct-type type, has a light weight, and has low power consumption.

1 is a cross-sectional view of a liquid crystal display device using a general sidelight 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 top cover 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 interposed therebetween, which plays a key role in image display. A printed circuit board (not shown) is connected to each of the two adjacent edges of the liquid crystal panel 10 through a connection member (not shown).

At this time, polarizing plates 19a and 19b for selectively transmitting only specific light are attached to the outer surfaces of the first and second substrates 12 and 14 of the liquid crystal panel 10, respectively.

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 edge of the guide panel 30, a white or silver reflective plate 25 seated on the cover bottom 50, 25, and an optical sheet 21 interposed therebetween.

Here, the LED assembly 29 includes a plurality of LEDs 29a and a PCB 29b on which a plurality of LEDs 29a are mounted.

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

The light emitted from the LED assembly 29 is incident on the light guide plate 23 and then refracted in the direction of the liquid crystal panel 10 and processed to a high quality of uniform luminance while passing through the optical sheet 21, So that the liquid crystal panel 10 displays an image on the outside.

On the other hand, in such a liquid crystal display device, a part of the light emitted from the backlight unit 20 is absorbed and reflected by the first polarizer 19a and is lost. This corresponds to 50% of the light emitted from the backlight unit 20 do.

In addition, since the liquid crystal layer is absorbed and reflected during the process of passing through the liquid crystal layer (not shown) including the first and second substrates 12 and 14 and a part thereof is lost again, the liquid crystal display panel has a weak point in terms of brightness.

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a liquid crystal display device having a high luminance, which is intended to solve the above problems, and to minimize light loss due to a polarizing plate to improve a light efficiency of the liquid crystal display device. As a second object.

A third object of the present invention is to maintain the polarization characteristics incident on the inside of the light guide plate, and the fourth object is to reduce the process cost.

In order to achieve the above-mentioned object, the present invention provides a liquid crystal display comprising: a light guide plate; An LED disposed along the light incident surface of the light guide plate and having an asymmetric distribution so as to have different directivity angles in a direction perpendicular to a longitudinal direction of the light incident surface; A reflective polarizing film positioned between the light incidence surface and the LED assembly; A liquid crystal panel positioned above the light guide plate; And first and second polarizers attached to both sides of the liquid crystal panel.

At this time, the directivity angle with respect to the direction perpendicular to the longitudinal direction of the light incidence surface is 120 degrees, the directivity angle with respect to the direction parallel to the longitudinal direction of the light incidence surface is 30 degrees, And a curtain film for covering a part thereof.

In addition, a collimation lens having a prism pattern in which an obtuse angle and a valley are repeated in a direction perpendicular to the longitudinal direction of the light incidence surface is attached to an emission surface of the LED, and the reflective polarizing film has a refractive index A multilayer thin film structure in which a polarizer is embedded in a laminated structure of other dielectric thin films, or a wire grid including fine metal patterns arranged side by side in one direction.

The reflective polarizing film has the same polarization axis as that of the first polarizing plate attached to the lower portion of the liquid crystal panel.

The present invention also provides a light emitting device comprising: a reflection plate; A light guide plate which is seated on the reflection plate and has a reflection polarizing pattern formed on a rear surface facing the reflection plate; An LED assembly arranged along the light incident surface of the light guide plate; A liquid crystal panel positioned above the light guide plate; And first and second polarizers attached to both sides of the liquid crystal panel.

At this time, the polarized light of the reflective polarizing pattern may include 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 material such as aluminum (Al), silver (Ag), chromium (Cr) , And gold (Au) are arranged in one direction, and the wire grid polarizer is attached to the back surface of the wire grid polarizer, and the back surface includes a pattern for guiding light, A polarizer having a certain polarization axis is contained in a laminated structure of a dielectric thin film having different refractive indexes or a fine linear metal pattern made of one selected from aluminum (Al), silver (Ag) and chromium (Cr) A wire grid polarizer arranged side by side in one direction is formed in a film form and attached to the pattern.

At this time, the pattern is formed of a selected one of a prism pattern, an elliptical pattern, a polygon pattern, and a hologram pattern, And has the same polarization axis as the first polarizing plate.

As described above, according to the present invention, a reflective polarizing film is interposed between the LED and the light incident surface of the light guide plate to emit light with an asymmetric distribution of the LED, or a reflective polarizing pattern is formed on the back surface of the light guide plate, The device has an effect of improving the light efficiency, thereby enabling a larger amount of light to be supplied to the liquid crystal panel, thereby realizing high brightness.

Further, there is an effect that the power consumption of the liquid crystal display device can be reduced.

Further, the material cost of the reflective polarizing film can be reduced as compared with the case where the reflective polarizing film is located below the first polarizing plate or interposed between the LED and the light guide plate, thereby reducing the processing cost.

1 is a sectional view of a liquid crystal display device using a general sidelight type backlight unit.
2 is an exploded perspective view of a liquid crystal display device according to an embodiment of the present invention.
3 is a partially exploded perspective view of the liquid crystal panel of Fig.
4A to 4B are perspective views schematically showing an LED according to a first embodiment of the present invention;
5A is a simulation result showing the distribution of light emitted from an ordinary LED.
5B is a simulation result showing the distribution of light emitted from the LED according to the first embodiment of the present invention.
6A to 6B are simulation results showing the traveling path of light incident into the light guide plate.
7 is a simulation result of comparing the polarized light transmittance of light emitted from the light guide plate according to the light distribution of the LED and general LED according to the first embodiment of the present invention.
8 is an exploded perspective view of a liquid crystal display device according to a second embodiment of the present invention.
9A to 9B are cross-sectional views schematically showing a light guide plate according to a second embodiment of the present invention.
FIG. 10 is a cross-sectional view schematically showing a part of FIG. 8 modularized; FIG.

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

- First Embodiment -

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

As shown, the liquid crystal display device includes a liquid crystal panel 110, a backlight unit 120, a guide panel 130, a cover bottom 150, and a top cover 140.

3, which is a partially exploded perspective view of the liquid crystal panel 110, a plurality of data lines 218 and a plurality of gate lines 216 are vertically and horizontally crossed on one surface of an array substrate 112, And defines an area P.

A thin film transistor T is provided at the intersection of these two wirings 216 and 218 and connected in a one-to-one correspondence with the transparent pixel electrode 224 provided in each pixel region P.

A data line 218 and a gate line 216 of the array substrate 112 and a non-display element such as a thin film transistor T are formed on one surface of the color filter substrate 214 facing the liquid crystal layer 250 with the liquid crystal layer 250 therebetween. Shaped black matrix 232 that covers the pixel region P so as to expose only the pixel electrode 224 while covering the pixel region 224.

A color filter layer 234 of red (R), green (G), and blue (B), and a transparent common electrode 234 covering all of the color filter layers 234 are sequentially arranged in a manner corresponding to each pixel region P in the lattice. (236).

On the outer surfaces of the array substrate 112 and the color filter substrate 114, first and second polarizers 119a and 119b selectively transmitting only specific light are attached.

Although not clearly shown in the figure, the upper and lower alignment films for determining the initial alignment direction of the liquid crystal are interposed at the boundary between the array substrate 112 and the color filter substrate 114 and the liquid crystal layer 150, 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 filled between the array substrate 112 and the color filter substrate 114.

At this time, the array substrate 112 has a size larger than that of the color filter substrate 114, and one side edge of the array substrate 112 is exposed to the outside when the color filter substrate 114 is adhered to the array substrate 112. Here, A plurality of connected data pads 222 and a plurality of gate pads (not shown) connected to the plurality of gate lines 216 are located.

The plurality of data pads 222 and gate pads (not shown) are connected to an external printed circuit board 117 via a connection member 116 such as a tape carrier package (TCP) The circuit board 117 is provided with a timing controller, a gamma voltage generator, and the like that processes various signal information input from an external device such as a computer and supplies signal voltages necessary for image display.

The printed circuit board 117 is brought into close contact with the back surface of the cover panel 150 or the side of the guide panel 130 during the modularization process.

A backlight unit 120 for supplying light to the back surface of the liquid crystal panel 110 is provided so that a difference in transmittance represented by the liquid crystal panel 110 is externally manifested.

The backlight unit 120 includes an LED assembly 129 and a reflective polarizing film 310 arranged in a longitudinal direction of at least one edge of the guide panel 130, a white or silver reflective plate 125, And an optical sheet 121 interposed between the light guide plate 123 and the light guide plate 123.

The LED assembly 129 is a light source of the backlight unit 120 and is disposed on one side of the light guide plate 123 so as to face the light incident side of the light guide plate 123. The LED assembly 129 includes a plurality of LEDs 320, And a PCB 128 on which a plurality of LEDs 320 are mounted at a predetermined interval.

A bar-shaped reflective polarizing film 310 is positioned in front of the LED 320 of the LED assembly 129. The reflective polarizing film 310 reflects only a specific linearly polarized light among the light emitted from the LED 320 And the remaining light is reflected and reproduced.

The reflective polarizing film 310 is formed to have the same polarization axis as the polarizing axis of the first polarizing plate 119a positioned below the liquid crystal panel 110. The reflective polarizing film 310 transmits the reflective polarizing film 310 to the light guide plate 123 The light is incident on the liquid crystal panel 110 through the first polarizing plate 119a without light loss in the process of being emitted to the outside of the light guide plate 123 and provided to the liquid crystal panel 110. [

That is, the light emitted from the backlight unit 120 is transmitted through the first polarizing plate 119a only by the first polarizing plate 119a having the same polarization axis as the polarization axis of the first polarizing plate 119a, The liquid crystal display device according to the present invention is configured such that the reflective polarizing film 310 having the same polarization axis as that of the first polarizing plate 119a is disposed in front of the LED 320 of the LED assembly 129 , So that only the light having the same polarization axis as the polarization axis of the first polarizing plate 119a is emitted from the backlight unit 120.

Accordingly, the transmittance of the first polarizer 119a is improved, thereby increasing the amount of light supplied to the liquid crystal panel 110, thereby achieving high brightness.

Here, the characteristic feature of the present invention is that a plurality of LEDs 320 mounted on the PCB 128 of the LED assembly 129 emits light so that the light has an asymmetric distribution.

That is, the LED 320 according to the first embodiment of the present invention emits light so that the light emitted from the LED 320 has a directivity angle of 120 degrees in the up and down direction, but has an asymmetric distribution so as to have a directivity angle of 30 degrees in the right and left directions. It emits light.

Therefore, the overall distribution shape of the light emitted from the LED 320 is emitted with the distribution of the linear light source in a direction perpendicular to the longitudinal direction of the light entrance surface of the light guide plate 123.

The light emitted by the asymmetrical distribution of the luminous source emitted from the LED 320 does not change the polarization characteristic inside the light guide plate 123, thereby minimizing the optical loss.

Accordingly, all the light emitted from the backlight unit 120 can be provided to the liquid crystal panel 110 without light loss, so that the liquid crystal display device can realize high brightness.

Let's take a closer look at this later.

The light guide plate 123 on which the specific linearly polarized light transmitted through the reflective polarizing film 310 is incident is a prism having a specific linear polarization maintained in a polarized state and being guided in the light guide plate 123 by total reflection several times, And spreads evenly over a wide area to provide a surface light source to the liquid crystal panel 110. [

The light guide plate 123 may include a pattern of a specific shape on the lower 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 reflection plate 125 is disposed on the back surface of the light guide plate 123 and reflects light passing through the back surface of the light guide plate 123 toward the liquid crystal panel 110 to improve the brightness of light.

The optical sheet 121 on the light guide plate 123 includes a diffusion sheet and at least one light condensing sheet and diffuses or condenses the light that has passed through the light guide plate 123 to provide a more uniform surface light source to the liquid crystal panel 110 Let it enter.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the top cover 140, the guide panel 130 and the cover bottom 150. The top cover 140 is disposed on the top edge of the liquid crystal panel 110, So as to cover the side surface.

Here, the top cover 140 has a rectangular frame shape bent in a "?" Shape so as to cover the top and side edges of the liquid crystal panel 110, As shown in Fig.

The cover bottom 150 on which the liquid crystal panel 110 and the backlight unit 120 are mounted and is a basis for assembling the entire structure of the liquid crystal display device is composed of a horizontal plane 151 and an edge portion 153 whose edges are vertically bent .

A rectangular guide panel 130 mounted on the cover bottom 150 and covering the edges of the liquid crystal panel 110 and the backlight unit 120 includes a top cover 140 and a cover bottom 150, .

Here, the top cover 140 may be referred to as a case top or a top case, and the guide panel 130 may be referred to as a support main or 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 liquid crystal display of the above-described structure can eliminate the top cover 140 and the cover bottom 150 in order to realize a lightweight and thin liquid crystal display device which is recently required. The liquid crystal display device can be made light and thin by eliminating the top cover 140 and the cover bottom 150, and the process can be simplified.

In addition, the elimination of the cover cover 140 and the cover valve 150, which are made of a metal material, can reduce the process cost.

As described above, in the liquid crystal display of the present invention, the reflective polarizing film 310 is interposed between the LED 320 and the light incident surface of the light guide plate 123, and the LED 320 emits light having an asymmetrical distribution, 123, the polarization characteristic can be maintained constant, and the optical loss can be minimized.

Accordingly, a larger amount of light can be supplied to the liquid crystal panel 110, thereby realizing high brightness.

4A to 4C are perspective views schematically showing an LED according to a first embodiment of the present invention. FIG. 5A is a simulation result showing a distribution of light emitted from a general LED. FIG. And the distribution of light emitted from the LED according to the present invention.

6A to 6B are simulation results showing a traveling path of light incident into the light guide plate.

First, as shown in FIG. 4A, the LED 320 according to the first embodiment of the present invention is formed with a barrier 323 in front of the light emitting portion.

The LED 320 is formed of a rear surface opposite to the emitting surface 321 and side surfaces connecting the emitting surface 321 and the back surface with respect to the emitting surface 321 through which light is emitted toward the light incident surface of the light guide plate 123 .

In this case, if the LED 320 is defined as an upper side and a lower side and a left side and a right side perpendicular to the upper side and the lower side with respect to a virtual line corresponding to the longitudinal direction of the light entrance surface of the light guide plate 123, 321, respectively.

A collimation lens 325 may be attached to the exit surface 321 of the LED 320 and the collimation lens 325 may reflect the light emitted from the LED 320 A prism pattern in which mountains and valleys are repeated in a direction perpendicular or horizontal to the direction of travel is arranged in rows.

A micro refraction pattern film 327 may be attached to the exit surface 321 of the LED 320 as shown in FIG. And the reflection patterns are arranged in rows in a direction perpendicular to the traveling direction of the light emitted from the light source. The LED 320 according to the first embodiment of the present invention emits light having a directional angle of 120 degrees on the upper and lower sides, but has an asymmetric distribution in directions perpendicular to each other so as to have a directivity angle of 30 degrees or less toward the left and right sides The light is emitted.

In other words, a general LED has a lambertian distribution with good symmetry as shown in FIG. 5A by emitting light with a directional angle of 120 degrees up and down and left and right. However, the LED 320 according to the first embodiment of the present invention, A curtain film 323 covering a part of the emission surface 321 is formed on the left and right sides of the emission surface 321 of the LED 320 or a collimation lens 325 is attached to the emission surface 321, As shown in FIG. 5B, the light is emitted so as to have an asymmetric distribution in the upper and lower sides, the left and right sides, that is, directions perpendicular to each other, as in the form of the linear light source in the upward and downward directions.

Therefore, in the liquid crystal display device according to the first embodiment of the present invention, the light emitted from the LED 320 maintains the polarization characteristic in the light guide plate 123, thereby minimizing the light loss. Accordingly, a larger amount of light can be provided to the liquid crystal panel (110 in FIG. 2), and high brightness can be realized.

In more detail, even if the light emitted from a general LED is emitted as a lambertian distribution and is polarized to a specific linear polarization by the reflective polarizing film in the process of transmitting the reflective polarizing film, the light progresses randomly inside the light guide plate The polarization state of the light changes.

That is, the polarization characteristic of the specific linearly polarized light can be kept constant without changing the polarization characteristic when the light is totally reflected in a state of being shaped with respect to the principal incident angle. As shown in FIG. 6A, Polarized light propagates randomly in the light guide plate.

As described above, since the polarization characteristics of light are changed inside the light guide plate, light whose polarization characteristic is changed out of the light emitted from the light guide plate is absorbed or reflected by the first polarizer and is lost.

On the contrary, the LED 320 according to the first embodiment of the present invention emits light having an asymmetric distribution of the linear light source, so that light emitted from the LED 320 is emitted into the light guide plate 123 As the light advances while maintaining straightness, the light incident into the light guide plate 123 is kept constant without changing the polarization characteristics.

Therefore, in the liquid crystal display device according to the first embodiment of the present invention, all the light incident into the light guide plate 123 is emitted to the outside of the light guide plate 123 while maintaining the polarization characteristic, 119a), it is possible to provide a larger amount of light to the liquid crystal panel (110 in Fig. 2), thereby realizing high brightness.

7 is a simulation result in which the polarized light transmittance of light emitted from the light guide plate is compared with the LED according to the first embodiment of the present invention and the light distribution of a typical LED.

Here, the vertical axis of the graph represents the amount of light incident on the light guide plate (123 in FIG. 6B), and the horizontal axis represents the symmetry of the light emitted from the LED (320 in FIG.

Referring to the graph, it can be seen that the polarized light transmittance of the light emitted from the light guide plate (123 in FIG. 6B) changes according to the degree of symmetry of the light emitted from the LED (320 in FIG. 4A) In the case of emitting light with a cyan distribution, only a specific linearly polarized light of about 0.8 is emitted from the light guide plate when the light amount of the specific linearly polarized light incident into the light guide plate is 1.

This is because even if the light emitted from the LED is transmitted through the reflective polarizing film and incident into the light guide plate in a specific linearly polarized state, the polarization characteristic is changed inside the light guide plate and the specific linearly polarized light emitted from the light guide plate is substantially reduced.

Here, as the specific linear polarized light incident on the light guide plate is the same as the polarization axis of the first polarizer, all of the specific linear polarized light emitted from the light guide plate is transmitted to the liquid crystal panel through the first polarizer plate without being absorbed or reflected by the first polarizer plate , The amount of light actually supplied to the liquid crystal panel is reduced as the specific linearly polarized light emitted from the light guide plate is reduced.

On the other hand, when the light from the LED (320 in FIG. 4A) emits light with an asymmetric distribution of the linear light source as in the first embodiment of the present invention, the specific linearly polarized light incident into the light guide plate (123 in FIG. 6B) 6b.

This is because the polarization characteristic of the specific linearly polarized light entered into the light guide plate 123 (123 of FIG. 6B) is kept constant without changing, and the light guide plate 123 (123 of FIG. 6B) as the specific linearly polarized light incident into the light guide plate 123 .

The liquid crystal display according to the first embodiment of the present invention includes a reflective polarizing film (310 in FIG. 2) interposed between the LED (320 in FIG. 4A) and the light guide plate (123 in FIG. 6B) (320 of FIG. 6A) emits light having an asymmetric distribution, so that only the specific linearly polarized light enters into the light guide plate (123 of FIG. 6B) and the specific linearly polarized light incident into the light guide plate It is possible to prevent the occurrence of optical loss due to the first polarizing plate (119a in Fig. 3) by improving the transmittance of the first polarizing plate (119a in Fig. 3).

Accordingly, a larger amount of light can be supplied to the liquid crystal panel (110 in FIG. 2), thereby realizing high brightness and reducing power consumption of the liquid crystal display device.

In addition, the liquid crystal display device according to the first embodiment of the present invention can reduce the processing cost as compared with the case where the reflective polarizing film (310 of FIG. 2) is positioned below the first polarizing plate (119a of FIG. 3).

The liquid crystal display of the first embodiment of the present invention includes light emitted through the laser light source in addition to the LED 320 as the light source of the backlight unit (120 in FIG. 2) ).

The light emitted through the laser light source is provided with a separate screen (323 in FIG. 4A), a collimation lens (325 in FIG. 4B), and a micro refraction pattern film (327 in FIG. 4C) The light is emitted so as to have an asymmetric distribution in up, down, left, and right directions so as to have a directivity angle of 30 degrees to the left and right sides, or to emit light having an orientation angle of 30 degrees or less to the upper and lower sides, As shown in FIG.

- Second Embodiment -

In order to avoid redundant explanations, the same reference numerals are assigned to the same parts as those of the first embodiment described above with reference to FIG. 2, and only the characteristic contents described above will be described.

8 is an exploded perspective view of a liquid crystal display device according to a second embodiment of the present invention.

As shown in the figure, the liquid crystal display includes a liquid crystal panel 110, a backlight unit 120, a top cover 140 for modularizing the liquid crystal panel 110 and the backlight unit 120, a guide panel 130, (150).

That is, the LED assembly 129 composed of the reflection plate 125, the light guide plate 220, the PCB 129b on which the LED 129a and the LED 129a are mounted, and the optical sheets 121 on the light guide plate 220 So that the backlight unit 120 is formed.

A liquid crystal panel 110 in which a liquid crystal layer (not shown) is interposed between the first and second substrates 112 and 114 is disposed on the backlight unit 120 and the first and second substrates 112 and 114 are attached with first and second polarizing plates (119a and 119b in FIG. 3) selectively transmitting only specific light.

The backlight unit 120 and the liquid crystal panel 110 are surrounded by a guide panel 130. A cover bottom 150 including a horizontal surface 151 and a side surface 153 is coupled to the back surface of the backlight unit 120 and the liquid crystal panel 110, And a top cover 140 covering the top edge and the side surface of the top cover 140 are coupled to the guide panel 130 and the cover bottom 150.

Here, the top cover 140 may be referred to as a case top or a top case, and the guide panel 130 may be referred to as a support main or 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 liquid crystal display of the above-described structure can eliminate the top cover 140 and the cover bottom 150 in order to realize a lightweight and thin liquid crystal display device which is recently required. The liquid crystal display device can be made light and thin by eliminating the top cover 140 and the cover bottom 150, and the process can be simplified.

In addition, the elimination of the cover cover 140 and the cover valve 150, which are made of a metal material, can reduce the process cost.

Here, the characteristic configuration of the second embodiment of the present invention is that the reflective polarizing pattern 210 is formed on the back surface 221 (see Fig. 9A) of the light guide plate 220. [

Therefore, when the light emitted from the LED 129a is incident into the light guide plate 220, the light guide plate 220 guides light emitted from the LED 129a through the light guide plate 220 by total reflection several times, To provide a planar light source to the liquid crystal panel 110 and at the same time to polarize the light reflected by the reflective polarizing pattern 210 into specific linear polarized light.

At this time, the reflective polarizing pattern 210 is formed to have the same polarization axis as the polarization axis of the first polarizing plate (119) of the lower polarizing plate (eh 3) located below the liquid crystal panel 110, (119a in FIG. 3) and is provided to the liquid crystal panel 110 in the process of being emitted to the outside of the light guide plate 220 and provided to the liquid crystal panel 110 without any light loss.

That is, only the light having the same polarization axis as that of the first polarizing plate 119a (119a in Fig. 3) is incident on the first polarizing plate 119a (Fig. 3) by the first polarizing plate 119a The liquid crystal display device according to the second embodiment of the present invention is configured such that light incident into the light guide plate 220 is incident on the back surface 221 of the light guide plate 220 Polarized light having the same polarization axis as the polarization axis of the first polarizing plate 119a (see FIG. 3) by the reflective polarizing pattern 210 formed on the light guide plate 220 (see FIG. 9A)

As a result, the transmittance of the first polarizer 119a (119a in FIG. 3) is improved, thereby increasing the amount of light supplied to the liquid crystal panel 110, thereby realizing high brightness.

The liquid crystal display according to the second embodiment of the present invention allows the specific linearly polarized light having the same polarization axis as the polarization axis of the first polarizing plate 119a (119a in Fig. 3) to be emitted from the light guide plate 220, 119a can be increased to minimize the optical loss due to the first polarizing plate (119a in Fig. 3).

Accordingly, a larger amount of light can be supplied to the liquid crystal panel 110, thereby realizing high brightness and reducing power consumption of the liquid crystal display device.

In the liquid crystal display device according to the second embodiment of the present invention, the reflective polarizing pattern 210 is formed on the back surface 221 (see FIG. 9A) of the light guide plate 220 so that the reflective polarizing film is positioned below the first polarizing plate Or the material cost of the reflective polarizing film can be reduced as compared with the case where it is interposed between the LED and the light guide plate, thereby reducing the processing cost.

9A to 9B are cross-sectional views schematically showing a light guide plate according to a second embodiment of the present invention.

9A, a reflective polarized light pattern 210 is formed on the back surface 221 of the light guide plate 220. The reflective polarized light pattern 210 includes a laminated structure of dielectric thin films having different refractive indexes, Or a fine linear metal pattern such as aluminum (Al), silver (Ag), chromium (Cr), platinum (Pt), gold (Au) or the like having high reflection efficiency is arranged side by side The wire grid polarizer arranged in the form of a film can be attached to the back surface 221 of the light guide plate 220.

9B, a plurality of oblique-shaped prism patterns 223 are formed on the back surface 221 of the light guide plate 220 such that the obtuse-angled prism patterns 223 are repeated in the transverse cross- A bar shape along the longitudinal direction of the light incidence surface of the light guide plate 220 or a line shape along the longitudinal direction of the light incidence surface of the light guide plate 220.

An elliptical pattern, a polygon pattern, and a hologram pattern, in addition to the prism patterns 223.

At this time, a polarizer having a certain polarization axis is contained in the laminated structure of the dielectric thin films exhibiting different refractive indexes in the oblique prism patterns 223, or aluminum (Al), silver (Ag) A reflective polarizing pattern 210 made of a wire grid polarizer film in which fine linear metal patterns such as chromium (Cr), platinum (Pt), and gold (Au) are aligned in one direction can be attached.

10 is a cross-sectional view schematically showing a part of FIG. 8 modularized.

The light emitted from the LED 129a is incident into the light guide plate 220 through the light incident surface of the light guide plate 220. The light incident into the light guide plate 220 passes through the light guide plate 220 several times The light is polarized to a specific linear polarization by the reflective polarizing pattern 210 formed on the back surface 221 of the light guide plate 220 and emitted toward the liquid crystal panel 110 in the process of being realized as a planar light source by total reflection.

At this time, the reflective polarizing pattern 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 all the planar light sources emitted from the light guide plate 220, The first polarizing plate 119a positioned on the first polarizing plate 119a is transmitted as it is.

Therefore, among the planar light sources emitted from the light guide plate 220, no light is lost by the first polarizer 119a, and high brightness can be realized.

The liquid crystal display device including the light guide plate 220 according to the second embodiment of the present invention allows the specific linearly polarized light having the same polarization axis as the polarization axis of the first polarizer plate 119a (119a) to be emitted from the light guide plate 220 , The transmittance of the first polarizing plate (119a of FIG. 3) can be increased to minimize the optical loss due to the first polarizing plate (119a of FIG. 3).

Accordingly, a larger amount of light can be supplied to the liquid crystal panel (110 of FIG. 8), thereby realizing high brightness and reducing the power consumption of the liquid crystal display device.

The liquid crystal display device according to the second embodiment of the present invention may be configured such that a reflective polarizing pattern 210 is formed on the back surface 221 of the light guide plate 220 so that the reflective polarizing film is positioned below the first polarizing plate, The material cost of the reflective polarizing film can be reduced and the process cost can be reduced.

Further, the optical loss can be further minimized as compared with the case where the reflective polarizing film is interposed between the LED and the light guide plate.

That is, when the reflective polarizing film is interposed between the LED and the light guide plate, even if the light emitted from the LED is transmitted through the reflective polarizing film and incident into the light guide plate in a specific linearly polarized state, the polarization characteristic changes inside the light guide plate, The specific linearly polarized light emitted from the light source is reduced.

Here, as the specific linear polarized light incident on the light guide plate is the same as the polarization axis of the first polarizer, all of the specific linear polarized light emitted from the light guide plate is transmitted to the liquid crystal panel through the first polarizer plate without being absorbed or reflected by the first polarizer plate , The amount of light actually supplied to the liquid crystal panel is reduced as the specific linearly polarized light emitted from the light guide plate is reduced.

In contrast, in the liquid crystal display device according to the second embodiment of the present invention, the light incident into the light guide plate 220 is reflected by the reflective polarizing pattern 210 formed on the back surface 221 of the light guide plate 220, It is possible to prevent the polarization characteristic from being changed inside the light guide plate 220. [

The following table (1) is a simulation for measuring the transmittance and screen quality of the first polarizing plate (119a in FIG. 3) located below the liquid crystal panel (110 in FIG. 8) of the liquid crystal display device according to the second embodiment of the present invention Results.

Transmittance Screen quality Sample 1 60%

Sample 2 90%

Here, Sample 1 is a liquid crystal display device in which a reflective polarizing film is interposed between an LED and a light guide plate. In Sample 2, a reflective polarizing pattern 210 is formed on the back surface 221 of the light guide plate 220 according to the second embodiment of the present invention. Is a liquid crystal display device formed.

Referring to Table 1, it can be seen that the transmittance of the first polarizer (119a in FIG. 3) located below the liquid crystal panel (110 of FIG. 8) of Sample 2 is much higher than that of Sample 1.

This is because, when a reflective polarizing film is interposed between the LED and the light guide plate, the polarization characteristic of the specific linearly polarized light incident into the light guide plate is changed, and the light with the specific linear polarization and the polarization property changed substantially from the light guide plate .

Therefore, the light whose polarization characteristic is changed is reflected or absorbed by the first polarizing plate, so that the transmittance of the first polarizing plate is only 60%.

In contrast, in the liquid crystal display according to the second embodiment of the present invention, light incident into the light guide plate 220 is polarized into specific linearly polarized light having the same polarization axis as the polarization axis of the first polarizer (119a in FIG. 3) Only a uniform linearly polarized light is emitted from the light guide plate 220 and most of light emitted from the light guide plate 220 is transmitted through the first polarizing plate 119a in FIG.

Accordingly, light loss due to the first polarizer 119a (119a in FIG. 3) can be minimized, thereby allowing a larger amount of light to be supplied to the liquid crystal panel (110 in FIG. 8) The power consumption of the display device can be reduced.

As described above, the liquid crystal display device according to the second embodiment of the present invention includes a reflective polarizing pattern 210 formed on the back surface 221 of the light guide plate 220, so that the light from the light guide plate 220 to the first polarizing plate 119a), the light transmittance of the first polarizing plate 119a (119a in Fig. 3) can be increased to minimize the optical loss caused by the first polarizing plate 119a (Fig. 3).

Accordingly, a larger amount of light can be supplied to the liquid crystal panel (110 of FIG. 8), thereby realizing high brightness and reducing the power consumption of the liquid crystal display device.

The liquid crystal display device according to the second embodiment of the present invention may be configured such that a reflective polarizing pattern 210 is formed on the back surface 221 of the light guide plate 220 so that the reflective polarizing film is positioned below the first polarizing plate, The material cost of the reflective polarizing film can be reduced and the process cost can be reduced.

Further, the optical loss can be further minimized as compared with the case where the reflective polarizing film is interposed between the LED and the light guide plate.

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
121: Optical sheet
123: light guide plate
125: reflector
129: LED assembly (220, LED, 128: PCB)
130: Guide panel
140: Top cover
150: cover bottom (151: horizontal plane, 153: side)
210: reflective polarizing film

Claims (11)

A light guide plate;
An LED disposed along the light incident surface of the light guide plate and having an asymmetric distribution so as to have different directivity angles in a direction perpendicular to a longitudinal direction of the light incident surface;
A reflective polarizing film positioned between the light incidence surface and the LED assembly;
A liquid crystal panel positioned above the light guide plate;
The first and second polarizers, which are attached to both sides of the liquid crystal panel,
And the liquid crystal display device.
The method according to claim 1,
Wherein the directing angle with respect to a direction perpendicular to the longitudinal direction of the light incidence surface is 120 degrees and the directivity angle with respect to a direction parallel to the longitudinal direction of the light incidence surface is 30 degrees.
The method according to claim 1,
Wherein the LED has a curtain film covering a part of both sides of the emitting surface.
The method according to claim 1,
Wherein a collimation lens having a prism pattern in which a peak and a valley are repeated in a direction perpendicular to a longitudinal direction of the light incidence surface is attached to an emission surface of the LED.
The method according to claim 1,
Wherein the reflective polarizing film comprises a wire grid comprising a multilayer thin film structure in which a polarizer is embedded in a laminated structure of dielectric thin films having different refractive indexes or a fine metal pattern arranged side by side in one direction.
The method according to claim 1,
Wherein the reflective polarizing film has the same polarization axis as that of the first polarizing plate attached to the lower portion of the liquid crystal panel.
A reflector;
A light guide plate which is seated on the reflection plate and has a reflection polarizing pattern formed on a rear surface facing the reflection plate;
An LED assembly arranged along the light incident surface of the light guide plate;
A liquid crystal panel positioned above the light guide plate;
The first and second polarizers, which are attached to both sides of the liquid crystal panel,
And the liquid crystal display device.
8. The method of claim 7,
The reflective polarizing pattern may include a polarizer having a certain polarization axis in a laminated structure of a dielectric thin film having different refractive indexes or may be formed of a metal such as aluminum (Al), silver (Ag), chromium (Cr), platinum (Au) are arranged side by side in one direction, and the wire grid polarizer is attached to the back surface of the wire grid polarizer in the form of a film.
8. The method of claim 7,
A polarizer having a certain polarization axis is contained in a laminated structure of a dielectric thin film having different refractive indexes, and the reflective polarizing pattern includes aluminum (Al), silver (Ag ), And chromium (Cr) are aligned in one direction, and the wire grid polarizer is attached to the pattern.
10. The method of claim 9,
Wherein the pattern comprises a selected one of a prism pattern, an elliptical pattern, a polygon pattern, and a hologram pattern.
8. The method of claim 7,
Wherein the reflective polarizing pattern has the same polarization axis as that of the first polarizing plate attached to the lower portion of the liquid crystal panel.

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