KR101423520B1 - 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 with improved light efficiency.
A feature of the present invention is to position a reflective polarizing film in front of the LED assembly and to form a composite variable pattern in which a dot pattern, a bar pattern and a line pattern are mixed on the lower surface of the light guide plate.
Thus, the light efficiency is improved, and the polarization characteristic of the specific linearly polarized light incident into the light guide plate through the reflective polarizing film can be maintained.
Therefore, by allowing light having uniform polarization characteristics to be emitted from the light guide plate, it is possible to provide all the light emitted from the backlight unit to the liquid crystal panel without light loss, thereby realizing higher brightness.
Further, in order to realize a lightweight, thin and narrow bezel, it is possible to prevent visibility degradation and occurrence of dark areas in the area between the LEDs, even if the number of LEDs is reduced or the number of optical sheets is reduced.

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, some of the light emitted from the backlight unit 20 is absorbed and reflected by the first polarizer 19a and is lost, which corresponds to 50% of the light emitted from the backlight unit 20 .

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 by minimizing optical loss and improving the light efficiency of a liquid crystal display device. The purpose.

It is a third object of the present invention to provide a liquid crystal display device having a light weight, a thin shape and a narrow bezel. However, the present invention provides a liquid crystal display device having a reduced visibility, The fourth purpose is what you want to do.

In order to achieve the above-mentioned object, the present invention provides a liquid crystal display comprising: a reflection plate; A dot pattern is formed in a first area of the lower surface adjacent to the first light incidence surface in the longitudinal direction and a line is formed in a third area spaced apart from the first area by a predetermined distance, ) Shape, and a bar-shaped pattern is formed in a second area between the first area and the third area; A first LED assembly arranged along the first light incidence surface of the light guide plate; A first reflective polarizer film positioned between the first light incidence surface and the first LED assembly; An optical sheet that is seated on the light guide plate; And a liquid crystal panel mounted on the optical sheet.

Here, the first reflective polarizing film may be a multilayer thin film structure having a polarizer embedded in a laminated structure of dielectric thin films having different refractive indexes, or a wire grid reflective polarizing film including a fine metal pattern arranged in one direction And the bar-shaped pattern and the line-shaped pattern are formed along the longitudinal direction of the light guide plate.

The dot-shaped pattern has a length of 20 to 200 탆. The line-shaped pattern is formed to have a length transverse to the longitudinal direction of the light guide plate. The bar-shaped pattern has a length And the width of the first and second regions is the same as the width of the third region.

The width of the first region is narrower than the width of the second region, the width of the second region is narrower than the width of the third region, and the dot- The bar-shaped pattern formed in the second region is formed at a high density per unit area from the first region to the third region, and the third region is formed at a high density per unit area from the first light incidence surface to the second region, The line-shaped pattern formed in the region is formed at a high density per unit area from the second region toward the opposite side of the first light incidence surface.

And a fourth region in which a first pattern in which the dot-shaped pattern is gradually elongated is formed between the first region and the second region, and between the second region and the third region, Wherein the first pattern adjacent to the second region has the same length as the bar-shaped pattern formed in the second region, and the second pattern adjacent to the second region has the same length as the bar- The pattern has the same length as the line-shaped pattern formed in the third area.

And a fourth region formed by mixing the dot-shaped pattern and the bar-shaped pattern between the first region and the second region, and between the second region and the third region, And a second LED assembly arranged along a second light incidence surface in the longitudinal direction opposite to the first light incidence surface, wherein the second light incidence surface and the second light incidence surface are aligned with each other, A second reflective polarizing film is interposed between the second LED assemblies.

The dot-shaped pattern is formed in a fifth area of the lower surface adjacent to the second light incidence surface, the bar-shaped pattern is formed in a fourth area between the third area and the fifth area, And a sixth region formed by mixing the dot-shaped pattern and the bar-shaped pattern between the first region and the second region, and between the second region and the third region, the bar- And an eighth region formed by mixing the dot-shaped pattern and the bar-shaped pattern between the third region and the fourth region, And a ninth region in which the bar-shaped pattern and the line-shaped pattern are mixed between the fourth region and the fifth region.

As described above, according to the present invention, a reflective polarizing film is positioned in front of an LED assembly, and a composite variable pattern in which a dot pattern, a bar pattern, and a line pattern are mixed is formed on the lower surface of the light guide plate. Thereby, it is possible to maintain the polarization characteristic of the specific linearly polarized light incident into the light guide plate through the reflective polarizing film.

Therefore, by emitting light having uniform polarization characteristics from the light guide plate, it is possible to provide all the light emitted from the backlight unit to the liquid crystal panel without loss of light, thereby realizing a higher luminance.

Also, in order to realize a lightweight, thin and narrow bezel, it is possible to prevent visibility degradation and generation of dark areas in the area between LEDs, even if the number of LEDs is reduced or the number of optical sheets is reduced.

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.
FIG. 3A is a rear perspective view schematically showing a light guide plate according to a first embodiment of the present invention. FIG.
FIG. 3B is a plan view schematically showing a lower surface of the light guide plate according to the first embodiment of the present invention. FIG.
Figures 4A-4B schematically illustrate the polarization characteristics of a particular linearly polarized light according to the shape of the pattern.
5A to 5B are photographs showing dark areas and visibility in a region between LEDs according to a pattern formed on the lower surface of the light guide plate.
Fig. 6 is a cross-sectional view schematically showing a partial cross section of Fig. 2 modularized; Fig.
7 is a plan view schematically showing a lower surface of a light guide plate according to a second embodiment of the present invention.
8A to 8B are plan views schematically showing a lower surface of a light guide plate according to a third embodiment of the present invention.
9 is a plan view schematically showing a lower surface of a light guide plate according to a fourth 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 device according to an embodiment of the present invention.

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.

First, the liquid crystal panel 110 plays a key role in image display and includes first and second substrates 112 and 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 with each other on the inner surface of the first substrate 112, which is usually referred to as a lower substrate or an array substrate, although not clearly shown in the figure, And a thin film transistor (TFT) is provided at each of the intersections, and is connected in a one-to-one correspondence with the transparent pixel electrodes formed in the respective pixels.

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 gate and a data printed circuit board 117 are connected to each other via a connection member 116 such as a flexible circuit board along at least one edge of the liquid crystal panel 110, (150).

Although not clearly shown in the drawing, an alignment film for determining the initial alignment direction of the liquid crystal is interposed at the boundary between the two substrates 112 and 114 of the liquid crystal panel 110 and the liquid crystal layer, and a liquid crystal layer A seal pattern is formed along edges of both the substrates 112 and 114 to prevent leakage of the substrate.

At this time, first and second polarizers (not shown) are attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

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 210 arranged in the 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 220 and the light guide plate 220.

The LED assembly 129 is a light source of the backlight unit 120 and is disposed on one side of the light guide plate 220 so as to face the light incident surface of the light guide plate 220. 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 therebetween.

A bar-shaped reflective polarizing film 210 is positioned in front of the LED 129a of the LED assembly 129. The reflective polarizing film 210 reflects only a specific linearly polarized light among the light emitted from the LED 129a And the remaining light is reflected and reproduced, thereby further improving the light efficiency of the liquid crystal display device of the present invention.

At this time, the reflective polarizing film 210 is formed to have the same polarization axis as the polarizing axis of the first polarizing plate 119a (see FIG. 6) located below the liquid crystal panel 110, through which the reflective polarizing film 210 is transmitted The light incident to the inside of the light guide plate 220 is emitted to the outside of the light guide plate 220 and provided to the liquid crystal panel 110 so that all the light is transmitted through the first polarizer plate 119a (110).

That is, only the light having the same polarization axis as the polarization axis of the first polarizing plate 119a (see FIG. 6) is reflected by the first polarizing plate 119a (see FIG. 6) 6), and the remaining light is absorbed and reflected to cause a light loss. The liquid crystal display of the present invention has a first polarizing plate 119a (FIG. 6A) in front of the LED 129a of the LED assembly 129, (See FIG. 6) from the backlight unit 120, only the light having the same polarization axis as the polarization axis of the first polarizing plate 119a (see FIG. 6) is caused to emit by placing the reflective polarizing film 210 having the same polarization axis as that of the first polarizing plate 119a.

Accordingly, the transmittance of the first polarizer 119a (see FIG. 6) is improved, thereby increasing the amount of light supplied to the liquid crystal panel 110, thereby achieving high brightness.

The light guide plate 220 through which the specific linearly polarized light transmitted through the reflective polarizing film 210 enters enters the liquid crystal panel 110 by spreading the light guide plate 220 evenly over the wide area of the light guide plate 220, To provide a surface light source.

The light guide plate 220 may include patterns 221, 223, and 225 of a specific shape on the lower surface to supply a uniform surface light source.

Here, the pattern included in the light guide plate 220 of the present invention includes a dot pattern 221 (hereinafter referred to as a dot pattern) and a bar pattern 223 (hereinafter referred to as a bar) And a line-shaped pattern 225 (hereinafter referred to as a line pattern) are mixed with each other.

Accordingly, the liquid crystal display device of the present invention can maintain the polarization characteristic of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210, and can realize a lightweight, Even if the number of the optical sheets 121 is reduced or the number of the optical sheets 121 is reduced, it is possible to prevent visibility deterioration and generation of dark portions in the area between the LEDs 129a.

Let me take a closer look at this later.

The reflection plate 125 is disposed on the back surface of the light guide plate 220 and reflects light passing through the back surface of the light guide plate 220 toward the liquid crystal panel 110 to improve the brightness of light.

The optical sheet 121 on the light guide plate 220 includes a diffusion sheet and at least one light condensing sheet and diffuses or condenses the light passing through the light guide plate 220 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, the liquid crystal display of the present invention is a composite liquid crystal display device in which a dot pattern 221, a bar pattern 223, and a line pattern 225 are mixed on the lower surface (see FIG. 3) of the light guide plate 220 It is possible to maintain the polarization characteristic of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210. In order to realize a light weight and a thinner and narrow bezel, Even if the number of optical sheets 121 is reduced or the number of optical sheets 121 is reduced, it is possible to prevent visibility deterioration and generation of dark portions in the area between the LEDs 129a.

FIG. 3A is a rear perspective view schematically illustrating a light guide plate according to a first embodiment of the present invention, and FIG. 3B is a plan view schematically illustrating a lower surface of the light guide plate according to the first embodiment of the present invention.

4A to 4B are diagrams schematically showing the polarization characteristics of a specific linearly polarized light according to the pattern shape.

3A and 3B, the light guide plate 220 may be formed of a plastic material such as polymethylmethacrylate (PMMA), which is an acrylic transparent resin, which is one of transparent materials capable of transmitting light, (PMMA), which is excellent in transparency, weatherability, and colorability, and which induces diffusion of light when light is transmitted, is the most widely used.

The light guide plate 220 includes a light incident surface 220a corresponding to the LED assembly 129 and a light incident surface 220b corresponding to the light incident surface 220a and a light incident surface 220a and a light incident surface 220b, A lower surface 220d facing the surface 220c and the reflection plate 125 in FIG. 2, and opposite sides 220e and 220f facing each other.

The lower surface 220d of the light guide plate 220 is provided with a plurality of variable variable patterns 221, 223 and 225 on the lower surface 220d of the light guide plate 220. The lower surface 220d of the light guide plate 220 includes a light- ) Are divided into three areas S1, S2, and S3.

That is, the dot pattern 221 is formed in the first area S1 near the light incidence surface 220a of the lower surface 220d of the light guide plate 220, and the bar pattern 223 And a line pattern 225 is formed in a third region S3 near the light-incident surface 220b.

At this time, the bar pattern 223 and the line pattern 225 formed in the second and third regions S2 and S3 are formed in a direction parallel to the longitudinal direction of the LED assembly 129, The LED assembly 129 is arranged along the light incidence surface 123a of the light guide plate 123 so that the length of the light guide plate 220 on the lower surface 220d of the light guide plate 220 Direction.

The line pattern 225 is formed to have a length transverse to the longitudinal direction of the light guide plate 220 and the bar pattern 223 is formed to have a length of 20 to 200 μm, The dot pattern 221 has a longer length than the dot pattern 221 and has a smaller length than the line pattern 225. [

In this case, in the first embodiment of the present invention, the dot pattern 221, the bar pattern 223, and the line pattern 225 are all formed in a negative shape, and the bar pattern 223 and the line pattern The composite variable patterns 221, 223, and 225 according to the first embodiment of the present invention are configured to include the light guide plate 220 and the light guide plate 220, An elliptical pattern, a polygon pattern, a hologram pattern, and the like may be used in order to guide the light incident to the inside.

The composite variable patterns 221, 223, and 225 are formed on the lower surface 220d of the light guide plate 220 by a printing method, a laser processing imprinting method, or an injection method.

The light guide plate 220 according to the first embodiment of the present invention is defined by dividing the lower surface 220d into first to third areas S1, S2 and S3 and the first to third areas S1 and S2 Polarized light of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210 by forming the dot pattern 221, the bar pattern 223 and the line pattern 225 on the light guide plate 220, Characteristics can be maintained.

That is, the light emitted from the LED 129a of the LED assembly 129 is incident on the light guide plate 220 only by the reflective polarizing film 210 located in front of the LED assembly 129. However, When only the dot pattern 221 is formed on the lower surface 220d of the light guide plate 220, the polarization characteristic of the specific linearly polarized light is changed by the dot pattern 221. [

As shown in FIG. 4A, when the polarization characteristic of the specific linearly polarized light is totally reflected on an inclined plane that is flat compared to the curved surface with respect to the main incident angle, or when it is totally reflected by the regular pattern, that is, the bar pattern 223, As shown in FIG. 4B, when the light having a specific wavelength is totally scanned by the dot pattern 221 having a curved surface, the polarization characteristic is changed by the dot pattern 221.

Table 1 below shows the results of simulation showing the polarization characteristics of light having a specific wavelength according to a pattern.

Reflector  Reflector by scattering Reflector Light guide plate pattern form Dot Bar Line Dot Bar Line The first polarizer plate transmittance 66% 68% 70% 73% 77% 80% Polarization degree 45% 48% 51% 59% 64% 68%

Referring to Table 1, it can be seen that the bar pattern 223 and the first polarizing plate (119a in FIG. 6) of the line pattern 225 are higher in transmittance than the dot pattern 221, In other words, it can be seen that the bar pattern 223 and the line pattern 225 have higher polarity characteristics than the dot pattern 221 having a curved surface, which is formed as a flat inclined surface.

Therefore, the light guide plate 220 of the present invention is formed by forming a composite variable pattern in which the dot pattern 221, the bar pattern 223, and the line pattern 225 are mixed, thereby forming the lower surface 220d of the light guide plate 220, The specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210 can maintain the polarization characteristic as compared with the case where only the dot pattern 221 is formed.

Thus, by emitting light having a uniform polarization characteristic from the light guide plate 220, it is possible to provide all the light emitted from the backlight unit (120 in FIG. 2) to the liquid crystal panel (110 in FIG. 2) , High brightness can be realized.

The liquid crystal display according to the first exemplary embodiment of the present invention is not only lightweight, thin, and narrow-bezel, but also has low visibility due to the line pattern 225, Can be prevented.

That is, when only the line pattern 225 is formed on the lower surface 220d of the light guide plate 220, the LED 129a of the LED assembly 129 may be reduced in number to realize a lightweight, thin, narrow bezel, When the number of the optical sheets 121 is reduced, dark portions are generated in the light entering portion of the light guide plate 220 where the light emitted from the LED 129a does not overlap and mix in the region between adjacent LEDs 129a, The visibility by the line pattern 225 is poor.

5A and 5B are diagrams illustrating a method of reducing the number of LEDs of an LED assembly to realize a lightweight and thin and neural bezel and reducing the number of optical sheets to reduce the visibility of the dark areas in the area between the LEDs according to the pattern formed on the lower surface of the light guide plate This is the picture shown.

FIG. 5A is a liquid crystal display device having a dot pattern formed on the lower surface of the light guide plate, FIG. 5B is a liquid crystal display device having a line pattern formed on the lower surface of the light guide plate, It can be seen that dark portions are generated in which light emitted from the LEDs is not superimposed and mixed in the region between the LEDs. In addition, it can be confirmed that visibility is poor due to the appearance of line patterns.

Accordingly, the light guide plate 220 of the present invention forms a composite variable pattern in which the dot pattern 221, the bar pattern 223, and the line pattern 225 are mixed to form a lightweight, thin and narrow bezel , It is possible to prevent the visibility of the line pattern 225 from deteriorating or the occurrence of dark portions in the region between the LEDs 129a.

The dot pattern 221, the bar pattern 223, and the line pattern 225 are formed so as to be mixed with each other, thereby increasing the degree of freedom in pattern design.

At this time, it is preferable that the interval P between the line patterns 225 is 0.6 mm or less.

Table 2 below shows the results of simulation in which the luminance of the light guide plate was measured in accordance with the interval between the line patterns, and the luminance of the photographs and the photographs showing the visibility of the line pattern were measured by a graph.

Spacing between line patterns 0.6mm 0.7mm 0.8mm 0.9mm

The light guide plate 220 of the present invention can improve the visibility by the line pattern 225 when the distance P between the line patterns 225 is 0.6 mm or less. A width w1 and w2 including a first area S1 in which a line pattern 221 is formed and a second area S2 in which a bar pattern 223 is formed are formed in a third area S3 The width w1 of the first area S1 is formed to be narrower than the width of the second area S2 and the width of the second area S2 is equal to the width w3 of the third area S3 The regions S3 in which the line patterns 225 are formed are wider than the regions S1 and S2 in which the dot patterns 221 and the bar patterns 223 are formed .

Thus, the light output efficiency of the light guide plate 220 can be further improved.

That is, in the light guide plate having only the dot pattern 221, the light output efficiency of the light guide plate formed with only the bar pattern 223 is 100% when the light output efficiency of the general light guide plate is 99% The light output efficiency of the light guide plate having only the line pattern 225 is 101.5%, and the light output efficiency of the light guide plate having the line pattern 225 is the highest.

Therefore, in the light guide plate 220 according to the first embodiment of the present invention, the region S3 in which the line pattern 225 is formed is divided into the regions S1 and S2 in which the dot pattern 221 and the bar pattern 223 are formed, The light output efficiency of the light guide plate 220 is further improved.

The light guide plate 220 according to the first embodiment of the present invention can maintain the polarization characteristic of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210, Is formed in a wider area S3 than the areas S1 and S2 where the dot pattern 221 and the bar pattern 223 are formed, the light output efficiency of the light guide plate 220 can be further improved Effect can be realized.

Fig. 6 is a cross-sectional view schematically showing a part of the section of Fig. 2 modularized.

An LED assembly 129 composed of a reflective plate 125, a light guide plate 220, a PCB 129b on which the LED 129a and the LED 129a are mounted, and an optical sheet (not shown) on the light guide plate 220, 121 are stacked to form a backlight unit (120 of FIG. 2).

A liquid crystal panel 110 in which a liquid crystal layer (not shown) is interposed between the first and second substrates 112 and 114 and the backlight unit 120 (FIG. 2) Polarizers 119a and 119b for selectively transmitting only specific light are attached to the outer surfaces of the two substrates 112 and 114, respectively.

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

The light emitted from the LED 129a is reflected by the reflective polarizing film 210 between the LED 129a and the light incident surface 220a of the light guide plate 220, .

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

The reflective polarizing film 210 transmits a part of the incident light and reflects the remaining light. The reflected light is reproduced as scattered light. Some of the reproduced scattered light transmits again through the reflective 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 emitted from the LED 129a is transmitted through the reflective polarizing film 210 and enters the light guide plate 220 through the light entrance surface 220a of the light guide plate 220. However, A second polarized light is reflected by the reflective polarizing film 210 and then reproduced as scattered light.

The first polarized light of the light reproduced by the scattered light is again transmitted through the reflective polarizing film 210 and the second polarized light is reproduced by the scattered light again to improve the light efficiency.

At this time, the reflective polarizing film 210 has the same polarization axis as the first polarizing plate 119a attached to the lower portion of the liquid crystal panel 110, so that the first polarized light 119a transmitted through the reflective polarizing film 210 is incident on the light guide plate 220, and is emitted from the planar light source toward the liquid crystal panel 110 by total internal reflection in the light guide plate 220. At this time, all the planar light sources emitted from the light guide plate 220 are made of the first polarized light, The first polarizer 119a located under the panel 110 is directly transmitted.

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.

In particular, the backlight unit 120 of FIG. 2 defines the lower surface 220d of the light guide plate 220 divided into first to third areas S1, S2, and S3, A dot pattern 221 is formed in the first area S1 and a bar pattern 223 is formed in the second area S2 and a third area S3 close to the receiving light surface (220b in FIG. 3B) The polarizing characteristic of the specific linearly polarized light incident into the light guide plate 220 through the reflective polarizing film 210 can be maintained.

Thus, by emitting light having uniform polarization characteristics from the light guide plate 220, it is possible to provide all the light emitted from the backlight unit (120 in FIG. 2) to the liquid crystal panel 110 without loss of light, Can be implemented.

Further, to reduce the number of the LEDs 129a or to reduce the number of the optical sheets 121 in order to realize a lightweight, thin and narrow bezel, it is possible to prevent visibility deterioration and dark portions in the area between the LEDs 129a .

The third area S3 in which the line pattern 225 is formed is wider than the first area S2 and the second area S2 in which the dot pattern 221 and the bar pattern 223 are formed, The light output efficiency of the light source 220 can be further improved.

7 is a plan view schematically showing a lower surface of a light guide plate according to a second embodiment of the present invention.

The composite variable patterns 221, 223, and 225 formed on the lower surface 220d of the light guide plate 220 include the LED assembly 129 and the light incident surface 220a with the reflective polarizing film 210 attached thereto ) To the incident light surface 220b so that the density of the pattern formed in each region is formed at a high density per unit area.

That is, the density of the complex variable patterns 221, 223, and 225 is densely formed toward the light receiving surface 220b of the light guide plate 220 from the light incident surface 220a of the light guide plate 220 where the LED assembly 129 is located .

The dot pattern 221 formed on the first area S1 of the lower surface 220d of the light guide plate 220 is formed so that the interval between the dot patterns 221 becomes narrower as the dot pattern 221 becomes closer to the second area S2 Lt; / RTI >

The bar pattern 223 formed in the second area S2 is formed so that the interval between the bar patterns 223 becomes narrower toward the third area S3. The line patterns 225 are formed in such a manner that the distance between the line patterns 225 becomes narrower or closer to each other as they are closer to the light-receiving surface 220b.

When the LED assembly 129 as the light source is located only on the light incidence surface 220a of the light guide plate 220 as in the second embodiment of the present invention, the light incidence surface 220a of the light guiding plate 220, The amount of light emitted toward the liquid crystal panel 110 in FIG. 6 is greater than the amount of light emitted toward the liquid crystal panel 110 in FIG. 6 from the side of the light-incoming surface 220b of the light guide plate 220, 6 to 110), it becomes difficult to provide a uniform surface light source.

At this time, as the complex variable patterns 221, 223, and 225 formed on the lower surface 220d of the light guide plate 220 are denser, more light incident into the light guide plate 220 is directed toward the liquid crystal panel 110 .

Accordingly, the composite variable patterns 221, 223, and 225 formed on the lower surface 220d of the light guide plate 220 are disposed on the lower surface 220d of the light guide plate 220 in the first to third regions S1, S2, And is formed at a high density per unit area from the light incidence surface 220a toward the light incidence surface 220b so that light is emitted from the light incidence surface 220a side of the light guide plate 220 toward the liquid crystal panel 110 And the amount of light emitted toward the liquid crystal panel (110 in Fig. 6) from the side of the light-incoming surface 220b of the light guide plate 220 is the same.

Accordingly, light of a uniform brightness can be emitted from the light guide plate 220, and a uniform planar light source can be incident on the liquid crystal panel (110 of FIG. 6).

The light guide plate 220 according to the second embodiment of the present invention is formed by forming the composite variable patterns 221, 223 and 225 on the lower surface 220d of the light guide plate 220, It is possible to maintain the polarization characteristic of the specific linearly polarized light incident into the light guide plate 220.

Thus, by emitting light having uniform polarization characteristics from the light guide plate 220, it is possible to provide all the light emitted from the backlight unit (120 in FIG. 2) to the liquid crystal panel (110 in FIG. 6) , High brightness can be realized.

Also, even if the number of the LEDs 129a is reduced or the number of the optical sheets 121 (121 in FIG. 6) is reduced in order to realize a lightweight, thin and narrow bezel, the visibility deteriorates and dark portions are generated in the region between the LEDs 129a Can be prevented.

The composite variable patterns 221, 223, and 225 are formed at a high density per unit area from the light incidence surface 220a to the light incident surface 220b so that light having a uniform brightness can be emitted from the light guide plate 220, A uniform planar light source can be made incident on the liquid crystal panel (110 of FIG. 6).

8A to 8B are plan views schematically showing a lower surface of a light guide plate according to a third embodiment of the present invention.

As shown in the figure, the lower surface 220d of the light guide plate 220 includes the LED assembly 129 and the first to fifth light guide plates 220a, 220b, 220c, 220d, 220d, The dot pattern 221 is formed in the first region S1 near the light incidence surface 220a and the dot pattern 221 is formed in the second region S2 in the vicinity of the light incidence surface 220a. a line pattern 225 is formed in the third area S3 near the bar pattern 223 and the receiving light surface 220b.

8A, a fourth region S4 is further formed between the first and second regions S1 and S2 where the dot pattern 221 and the bar pattern 223 are formed, A first pattern 227a is formed in the fourth region S4 so that the dot pattern 221 is gradually elongated. The first pattern 227a adjacent to the second region S2 includes a bar pattern 223, And are formed to have the same length.

A fifth area S5 is further formed between the second area S2 and the third area S3 in which the bar pattern 223 and the line pattern 225 are formed. A second pattern 227b having a shape in which a bar pattern 223 is gradually elongated is formed in the first area 227a and a second pattern 227b adjacent to the third area S3 is formed in the same length as the line pattern 225 .

8B, the dot pattern 221 formed in the first region S1 and the bar pattern 223 formed in the second region S2 are mixed with each other in the fourth region S4 And a bar pattern 223 formed in the second region S2 and a line pattern 225 formed in the third region S3 are formed in the fifth region S5 It is possible.

At this time, the dot pattern 221 formed in the first region S1, the bar pattern 223 formed in the second region S2, and the line pattern 225 formed in the third region S3 The LED assembly 129 may be formed at a high density per unit area from the light incident surface 220a of the light guide plate 220 to the light incident surface 220b of the light guide plate 220. [

The first pattern 227a formed in the fourth region S4 and the second pattern 227b formed in the fifth region S5 are also directed from the light incoming surface 220a of the light guide plate 220 to the incoming light surface 220b The higher density per unit area can be obtained.

9 is a plan view schematically showing a lower surface of a light guide plate according to a fourth embodiment of the present invention.

The first and second LED assemblies 230a and 230b including the PCB 129b having the LED 129a and the LED 129a mounted on both sides of the light guide plate 220 in the longitudinal direction of the light guide plate 220, The first and second reflective polarizing films 210a and 230b may be disposed between the first and second LED assemblies 230a and 230b and the first and second light incidence planes 220a and 220b of the light guide plate 220. [ , 210b are attached.

At this time, the lower surface 220d of the light guide plate 220 is divided into the first to fifth regions 220a to 220d from the first light incidence surface 220a where the first and second LED assemblies 230a and 230b are located to the second light incidence surface 220b The first area S1 adjacent to the first light incidence surface 220a and the fifth area S5 adjacent to the second light incidence surface 220b may be defined by dots S1, S2, S3, S4, A pattern 221 is formed and a bar pattern 223 is formed in a second region S2 adjacent to the first region S1 and a fourth region S4 adjacent to the fifth region S5 do.

A line pattern 225 is formed in the third region S3.

At this time, the dot pattern 221 formed in the first and fifth regions S1 and S5, the bar pattern 223 formed in the second and fourth regions S2 and S4, and the fifth region S5 The line pattern 225 may be formed at a high density per unit area from the first and second light incidence surfaces 220a and 220b toward the center of the light guide plate 220. [

A first pattern 227a (FIG. 8A) in which the dot pattern 221 is gradually elongated is formed between the first and second regions S1 and S2 where the dot pattern 221 and the bar pattern 223 are formed, (Not shown) including a bar pattern 223 and a line pattern 225 formed between the second area S2 and the third area S3, (not shown) including a second pattern (227b in Fig. 8A) in which the bar pattern 223 is gradually elongated.

It is also possible to further include an eighth area (not shown) including a first pattern (227a in Fig. 8A) in which the dot pattern 221 gradually becomes longer between the fifth area S5 and the fourth area S4 And a ninth region (not shown) including a second pattern (227b in FIG. 8A) in which a bar pattern 223 is gradually elongated between a fourth region S4 and a third region S3 Time).

At this time, the dot pattern 221 and the bar pattern 223 may be mixed with each other in the sixth region (not shown) and the eighth region (not shown), and a seventh region (not shown) A bar pattern 223 and a line pattern 225 may be mixed with each other in a region (not shown).

As described above, the liquid crystal display of the present invention improves the light efficiency by positioning the reflective polarizing films 210a and 210b in front of the LED assemblies 230a and 230b, thereby realizing high brightness.

By forming a composite variable pattern in which the dot pattern 221, the bar pattern 223 and the line pattern 225 are mixed on the lower surface 220d of the light guide plate 220, the reflective polarizing films 210a and 210b The polarization characteristic of the specific linearly polarized light incident into the light guide plate 220 can be maintained.

Thus, by emitting light having uniform polarization characteristics from the light guide plate 220, it is possible to provide all the light emitted from the backlight unit (120 in FIG. 2) to the liquid crystal panel (110 in FIG. 6) , A higher brightness can be realized.

Also, even if the number of the LEDs 129a is reduced or the number of the optical sheets 121 (121 in FIG. 6) is reduced in order to realize a lightweight, thin and narrow bezel, the visibility deteriorates and dark portions are generated in the region between the LEDs 129a Can be prevented.

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
125: reflector
129: LED assembly (129a, LED, 129b: PCB)
130: Guide panel
140: Top cover
150: cover bottom (151: horizontal plane, 153: side)
210: reflective polarizing film
220: a light guide plate 220a: an incoming light surface 220d: a lower surface 221: a dot pattern 223: a bar pattern 225: a line pattern)

Claims (13)

A reflector;
A dot-shaped pattern is formed on a first area of the lower surface adjacent to the first light incidence surface in the longitudinal direction, and a third area spaced from the first area by a predetermined distance, Wherein a line-shaped pattern having a first length corresponding to the length of the light-entering surface is formed, and a second region between the first region and the third region has a second length smaller than the first length, a light guide plate having a bar-shaped pattern formed therein;
A first LED assembly arranged along the first light incidence surface of the light guide plate;
A first reflective polarizer film positioned between the first light incidence surface and the first LED assembly;
An optical sheet that is seated on the light guide plate;
And a liquid crystal panel
And the liquid crystal display device.
The method according to claim 1,
The first reflective polarizing film may be 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 liquid crystal reflective film selected from a wire grid reflective polarizing film including fine metal patterns arranged in parallel in one direction Display device.
The method according to claim 1,
Wherein the bar-shaped pattern and the line-shaped pattern are formed along a longitudinal direction of the light guide plate.
The method according to claim 1,
Wherein the dot-shaped pattern has a length of 20 to 200 mu m, and the bar-shaped pattern has a longer length than the dot-shaped pattern.
The method according to claim 1,
The width of the first and second regions being equal to the width of the third region.
The method according to claim 1,
Wherein a width of the first region is narrower than a width of the second region, and a width of the second region is narrower than a width of the third region.
The method according to claim 1,
Wherein the dot-shaped pattern formed in the first area is formed at a high density per unit area from the first light incidence surface to the second area, and the bar-shaped pattern formed in the second area is divided into three areas And the line-shaped pattern formed in the third region is formed at a high density per unit area from the second region toward the opposite side of the first light-incident surface.
The method according to claim 1,
Shaped pattern is formed between the first region and the second region, and a fourth region in which a first pattern in which the dot-shaped pattern is gradually elongated is formed is formed between the first region and the second region, And a fifth region which is gradually elongated.
9. The method of claim 8,
The first pattern adjacent to the second region has the same length as the bar-shaped pattern formed on the second region, and the second pattern adjacent to the third region has the same pattern as the line-shaped pattern formed on the third region And the length of the liquid crystal display panel.
The method according to claim 1,
And a fourth region formed by mixing the dot-shaped pattern and the bar-shaped pattern between the first region and the second region, and between the second region and the third region, the bar-shaped pattern And a fifth region in which the line-shaped pattern is mixed.
The method according to claim 1,
And a second LED assembly arranged along a second light incidence plane in a longitudinal direction opposite to the first light incidence plane, wherein a second reflective polarizing film is interposed between the second light incidence plane and the second LED assembly, .
12. The method of claim 11,
Shaped pattern is formed in a fifth area of the lower surface adjacent to the second light incidence surface and a bar pattern is formed in a fourth area between the third area and the fifth area, .
13. The method of claim 12,
And a sixth region formed by mixing the dot-shaped pattern and the bar-shaped pattern between the first region and the second region, and between the second region and the third region, the bar- And an eighth region formed by mixing the dot-shaped pattern and the bar-shaped pattern between the third region and the fourth region, And a ninth region in which the bar-shaped pattern and the line-shaped pattern are mixed between the fourth region and the fifth region.

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