KR20070051471A - Liquid crystal display apparatus employing polymer dispersed liquid crystal mode - Google Patents

Abstract

The liquid crystal display of the present invention includes a display panel and a backlight assembly. The display panel includes a polymer dispersed liquid crystal (PDLC or PNLC) layer. The backlight assembly is disposed on the rear surface of the dispersion liquid crystal layer to supply at least a part of light in a direction inclined with respect to the vertical direction of the incident surface of the dispersion liquid crystal layer. In addition, the liquid crystal display device has a reflection-refraction member disposed between the backlight assembly and the polymer dispersed liquid crystal layer to reflect external light such as sunlight, so that the backlight assembly receives direct sunlight vertically emitted from the backlight light source toward the display panel. Minimize and maximize the reflection efficiency by external light. As a result, the liquid crystal display may display an image of excellent quality with respect to the reflected light and the transmitted light under the front viewing angle.

Description

Liquid crystal display device employing polymer dispersed liquid crystal mode {LIQUID CRYSTAL DISPLAY APPARATUS EMPLOYING POLYMER DISPERSED LIQUID CRYSTAL MODE}

1 is a cross-sectional view of a liquid crystal layer of a conventional liquid crystal display device showing an active region where an electric field is formed and an inactive region where an electric field is not formed.

2 is a cross-sectional view of the liquid crystal layer for explaining the display mode under the front viewing angle corresponding to the active region.

3 is a cross-sectional view of the liquid crystal layer for explaining the display mode under the side viewing angle corresponding to the inactive region.

4 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along the line II ′ of FIG. 4.

6 is a cross-sectional view illustrating the display panel of FIG. 5.

FIG. 7 is a perspective view illustrating the light guide plate of FIG. 4.

FIG. 8 is a cross-sectional view taken along the line II-II 'of FIG. 7.

9 is an exploded perspective view illustrating a liquid crystal display according to another exemplary embodiment of the present invention.

10A to 10E are vertical stage views showing various types of light path changing units.

<Description of the symbols for the main parts of the drawings>

180: display panel 210: lamp unit

220: Light guide plate 240: Reflective plate

250: second storage container 300: first storage container

400: top chassis 670: light path changing unit

100: display panel assembly 200, 600: backlight assembly

500, 1000: LCD

The present invention relates to a liquid crystal display device, and more particularly, a polymer dispersed liquid crystal (PDLC or Polymer Networked Liquid Crystal; PNLC, hereinafter referred to as PDLC) mode is applied to improve the front viewing angle of the PDLC mode. It relates to a liquid crystal display device.

Recently, due to the development of the information and communication industry, the demand for flat panel display technology is increasing due to the need for thin, light weight, and low power consumption, which emphasizes the demand for high resolution and large screen and portability.

At present, the representative display device is CRT (Cathod Ray Tube), which is a very excellent device for image display means with a contrast ratio of 30: 1 or more and a lifetime of 10,000 hours or more, but it is bulky, heavy and completely flat because it includes a vacuum tube. There is no way to make it. In addition, CRTs that require high voltage do not meet the recent trend of integration of electronic circuits because the phosphors are emitted with an electron beam to display an image.

Flat panel display devices such as EL (Electro-Luminescence), FED (Field Emission Display), P (Plasma Display Panel), LCD (Liquid Crystal Display), etc. have the potential to fundamentally solve these problems of CRT. Attention has been researched and developed. However, a light emitting display device such as EL, FED, PDP, etc., has a disadvantage of low luminous efficiency and high voltage. In contrast, LCDs are light-receiving display devices and operate with low voltage and low power consumption, and are very different from other display devices. However, LCDs are low in brightness, have a viewing angle dependence, and when a large LCD is manufactured, an alignment layer is formed on a wide substrate and liquid crystals are uniformly distributed and sealed, which makes it very difficult to manufacture. In addition, in the case of making a large screen, the number of electrodes increases, so the duty ratio of the voltage waveform applied to each electrode decreases, thereby giving an unnatural feeling in moving image display in a slow response LCD.

Recently, as a solution to some of these problems, development of a polymer dispersed liquid crystal (PDLC) display device in which a low molecular liquid crystal is impregnated into a porous film has been made.

The PDLC has a thin film structure in which a polymer matrix or a crosslinked polymer matrix is impregnated with a nematic liquid crystal having positive dielectric anisotropy between the indium tin oxide (ITO) substrates. In this structure, low-molecular liquid crystals are randomly oriented on the outer wall of the polymer matrix in an electromagnetic field, which causes light scattering to become opaque.However, when a voltage is applied, the liquid crystals are arranged along the electric field to transmit light. do. Therefore, there is no need for an alignment layer and a polarizing plate used in a twisted nematic (TN) type LCD, which simplifies the process and increases the intensity of transmitted light, as well as an improved viewing angle.

However, the following problems are recognized in the display device using the PDLC.

1 is a cross-sectional view of a liquid crystal layer of a conventional liquid crystal display device showing an active region in which an electric field is formed and an inactive region in which an electric field is not formed.

Referring to FIG. 1, the polymer dispersed liquid crystal 10 includes a polymer 2 and a low molecular liquid crystal 4 dispersed in the polymer 2. The liquid crystal molecules 4 of the inactive regions A and C to which the electric field is not applied are not aligned and thus scatter the incident light. On the other hand, the liquid crystal molecules 4 of the active region B to which the electric field is applied are aligned in a line along the direction of the electric field to transmit incident light. Accordingly, the inactive regions A and C emit scattered light and the active region B emits transmitted light.

2 is a cross-sectional view of the liquid crystal layer for explaining the display mode? Under the front viewing angle corresponding to the active region.

Referring to FIG. 2, when light is incident perpendicularly to the liquid crystal layer, linear light is emitted from the active region B, and scattered light is emitted from the inactive regions A and C. Referring to FIG. The observer perceives both linear light and scattered light, but recognizes linear light having a large amount of transmission as a white region. However, the difference in luminance between the scattered light and the transmitted light is not so obvious that it is somewhat unreasonable to express high quality gradation.

3 is a cross-sectional view of the liquid crystal layer for explaining the display mode under the side viewing angle corresponding to the inactive region.

Referring to FIG. 3, unlike FIG. 2, the observer's field of view is located on a side surface corresponding to the inactive region C. FIG. In this case, the observer does not recognize the linear light emitted from the active region B, so that the observer recognizes the active region B as a black state. On the other hand, since the scattered light emitted from the inactive areas A and C is recognized as a white state, an image having excellent gray scale expression can be recognized as a whole. However, due to the bias of the viewing angle due to the recognition of a clear image only under the side viewing angle, it may be a problem in terms of practicality or compatibility as a product.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a liquid crystal display device employing a polymer dispersed liquid crystal (PDLC) mode and having an improved front viewing angle.

A liquid crystal display according to an aspect of the present invention includes a display panel and a backlight assembly.

The display panel includes a polymer dispersed liquid crystal (PDLC) layer. The backlight assembly is disposed on the rear surface of the display panel to supply at least a part of light in a direction inclined with respect to the vertical direction of the incident surface of the display panel.

The display panel includes a first substrate disposed below the liquid crystal layer and a second substrate disposed above the liquid crystal layer, wherein the first substrate and the second substrate selectively apply an electric field to the liquid crystal layer when power is applied. Generated to allow the liquid crystal layer having the electric field to transmit light. The liquid crystal layer region in which the electric field is formed exhibits a black state under a front viewing angle.

The backlight assembly includes a light source for generating light and a light guide plate for guiding the light in a display panel direction. In the light guide plate, a light path changing pattern is formed on a surface of the light guide plate to change the path of the light exiting the light guide plate. The optical path change pattern may have various shapes, for example, a triangular prism shape.

A liquid crystal display according to another aspect of the present invention includes a light path changing unit between the PDLC layer and the backlight assembly.

The optical path changing unit may have any configuration as long as the optical path changing unit can serve to change the path of the light to provide light inclined toward the display panel.

Examples of possible light path changing units include a prism sheet, a microlens sheet having a microlens formed on its surface, a lens sheet having a lens function, a slit sheet capable of changing the optical path by diffraction, and an optical path that can be changed by refraction Refractive sheets, and the like. In particular, in the case of the refractive sheet, in order to effectively change the optical path, it is preferable to use a refractive sheet which is not constant in thickness or is inclined.

The liquid crystal display may further include a reflection-refraction sheet for reflecting external light between the backlight assembly and the display panel and for changing an optical path of the internal light supplied from the backlight assembly. The reflection-refraction sheet has a reflection surface on which a mirror surface is formed and a back surface on which a refractive pattern for refracting an optical path of internal light is formed. The reflection-refractive sheet may preferably be an inverted prism sheet. Alternatively, the first substrate of the liquid crystal display may further include a reflection-refraction pattern layer that performs the function of the reflection-refraction sheet on the surface or inside. As a result, the liquid crystal display may efficiently use not only internal light but external light such as sunlight.

The liquid crystal display devices may additionally include a polarizing plate for improving contrast. Two polarizers are used, and each polarizer has a polarization direction orthogonal to each other.

The liquid crystal display device of the present invention not only includes the advantages of the PDLC mode itself such as the simplification of the manufacturing process by adopting the PDLC liquid crystal mode, but also can display an image of excellent quality using the reflected light and the transmitted light under the front viewing angle.

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

4 is an exploded perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the liquid crystal display 500 includes a display panel assembly 100 displaying an image using light and a backlight assembly 200 generating the light and providing the light to the display panel assembly 100. do. In addition, the liquid crystal display 500 may include a first accommodating container 300 and a top chassis 500 accommodating the backlight assembly 200.

The display panel assembly 100 includes a display panel 180 for displaying the image, a plurality of data side and gate side tape carrier packages (TCP) 120 and 125, and a data side and gate side printed circuit board 130 and 135. ).

The display panel 180 may include a polymer dispersed liquid crystal (PDLC) layer (not shown), a first substrate 140 disposed below the liquid crystal layer, and a second substrate disposed above the liquid crystal layer. 120). The first substrate 140 and the second substrate 120 function as a kind of liquid crystal capacitor together with the liquid crystal layer injected between the first substrate 140 and the second substrate 120. Accordingly, when power is applied to the first substrate 140 and the second substrate 120, an electric field may be generated in the liquid crystal layer to transmit light through the liquid crystal layer. Although not illustrated, the first substrate 140 may include a switching element to selectively form an electric field in the liquid crystal layer.

The backlight assembly 200 includes a lamp unit 210 that generates the light, a light guide plate 220, a reflector plate 240, and a second storage container 250.

The lamp unit 210 is located on one side of the light guide plate 220 and generates the light in response to a power supplied from the outside. The lamp unit 210 is configured to provide the light guide plate 220 with the lamp 211 generating the light in response to a power supplied from the outside and the light incident from the lamp 211 and the lamp 211 to the light guide plate 220. Lamp reflector 212.

The light guide plate 220 is disposed under the display panel 180 and on the side of the lamp unit 210. The light guide plate 220 guides the light so that the light emitted from the lamp unit 210 is directed toward the display panel 180.

The light guide plate 220 is formed with a light path changing pattern (not shown) on the emission surface.

The reflective plate 240 is disposed under the light guide plate 220. The reflection plate 240 reflects the light incident from the light guide plate 220 back to the light guide plate 220 to improve light utilization efficiency.

The second receiving container 250 is provided under the reflecting plate 240. The second accommodating container 250 sequentially accommodates the reflecting plate 240, the light guide plate 220, and the lamp unit 210. The second accommodating container 250 is made of a hard metal material and quickly discharges heat generated from the lamp unit 210 to the outside.

The first storage container 300 is positioned between the display panel 180 and the backlight assembly 200. The first accommodating container 300 is made of synthetic resin, and includes a bottom surface of which a portion is opened and a side wall extending from the bottom surface. The first accommodating container 300 is coupled to the second accommodating container 250 to fix the lamp unit 210, the light guide plate 220, and the reflecting plate 240 to the second accommodating container 250. do.

The top chassis 400 is provided on the display panel 180. The top chassis 400 covers the display panel 180 so that the display area where an image is displayed is opened, and is coupled to the first and second storage containers 300 and 250. The top chassis 400 guides the position of the display panel 180 and fixes the display panel 180 to the first storage container 300.

FIG. 5 is a cross-sectional view taken along the line II ′ of FIG. 4. 6 is a cross-sectional view illustrating the display panel of FIG. 5. However, in FIG. 5, the first storage container 300 is omitted.

5 to 6, the display panel 180 includes a first substrate 140, a polymer dispersed liquid crystal layer 150, and a second substrate 160.

The first substrate 140 is divided into a plurality of pixel regions, and includes a first base substrate 141, a thin film transistor (TFT) layer 142, a pixel electrode layer 143, and a reflection-refraction pattern layer 144. do.

The first base substrate 141 may be a transparent substrate, for example, an indium tin oxide (ITO) substrate. The thin film transistor layer 142 is formed on the first base substrate, and includes one thin film transistor TFT in each pixel area. A plurality of data side TCPs 120 are attached to the source side of the first substrate 140. A plurality of gate side TCPs 125 are attached to the gate side of the first substrate 140. The data side and gate side TCPs 120 and 125 apply a driving signal for driving the display panel 180 and a timing signal for controlling the driving timing to the display panel 180.

The data side and gate side TCPs 120 and 125 are connected to the data side and gate side printed circuit boards 130 and 135, respectively. The data side and gate side printed circuit boards 130 and 135 generate the driving signal and the timing signal and apply them to the data side and gate side TCPs 120 and 125, respectively.

The pixel electrode layer 143 includes pixel electrodes in each pixel area.

The reflection-refraction pattern layer 144 reflects an external light source so that the reflection-refraction pattern layer 144 may be used as a light source of the liquid crystal display, and is formed on a portion of the pixel electrode layer 143. Alternatively, the reflection-refraction pattern layer 144 may be formed on the entire surface of the pixel electrode or on one layer inside the first substrate. This enables a transflective liquid crystal display device.

The reflection-refraction pattern layer 144 has a flat reflective surface on its surface and a pattern having irregularities on its rear surface to reflect light incident from the outside, and internal light incident on the rear surface can change its path. And a reflection and transmission function capable of efficiently using external light. The reflection-refraction pattern layer 144 may be an inverted prism sheet having an inverted triangular cross-section so that the reflection-refraction pattern layer 144 has a function opposite to that of the conventional light-converging prism sheet. The reflection-refraction pattern layer 144 is different from the diffusion sheet that scatters light in all directions, and may include a prism sheet having various shapes as long as the light emitted from the light source can be inclined to the PDLC layer 150. The shape and prism shape are not particularly limited.

The PDLC layer 150 includes a polymer dispersed liquid crystal. The polymer dispersed liquid crystal includes a polymer material and nematic liquid crystal molecules dispersed in the polymer material. The polymer dispersed liquid crystal (PDLC) has a form in which a liquid crystal is dispersed in a droplet state in a polymer matrix. The PDLC scatters light at the interface between the liquid crystal molecules and the polymer matrix due to the difference in refractive index between the two materials. However, the liquid crystal molecules are aligned in a specific direction under an electric field, and when the polymer material having the same refractive index as that of the liquid crystal is used as the matrix, the PDLC can transmit light without scattering. The PDLC device exhibits light scattering under an electric field and light transmitting characteristics under an electric field.

The second substrate 160 includes a second base substrate (not shown), a color filter layer (not shown) formed on the second base substrate, and a common electrode layer formed on the color filter layer and corresponding to the pixel electrodes. do. The color filter layer has a red (R), green (G), or blue (B) color filter corresponding to the pixel electrodes, respectively.

FIG. 7 is a perspective view illustrating the light guide plate of FIG. 4. FIG. 8 is a cross-sectional view taken along the line II-II 'of FIG. 7.

7 and 8, light path changing patterns 225 are formed on a surface of the light guide plate 220. The optical path change pattern 225 has a triangular prism shape extending in one direction. The optical path change patterns 225 are repeatedly formed to be parallel to each other, and are formed continuously to each other. In the present embodiment, the light path changing pattern 225 has a right triangular pillar shape. The pattern shape of the light path changing pattern 225 formed on the light guide plate 220 may have various shapes in addition to the light path changing pattern 225 as long as the light path may be changed to emit light inclined to the display panel 180. Dot patterns 227 for scattering light are formed on the bottom surface of the light guide plate. The dot patterns 227 may increase light efficiency by allowing more light to be emitted from the light guide plate 220.

In the present exemplary embodiment, the light path changing patterns 225 are formed on the entire exit surface of the light guide plate 220. Alternatively, the light path changing patterns 225 may be selectively formed only on a part of the exit surfaces of the light guide plate 220. May be

Although not shown, the light path change patterns 225 formed on the surface of the light guide plate 220 may have a curved shape such as a circular shape or a continuous spiral shape as a whole.

Since the liquid crystal display device 500 obliquely enters the light into the display panel assembly 100, the active region to which the electric field is applied under the front viewing angle displays an image of a black state. Therefore, an inactive area (not applied to the field) that emits scattered light under the front viewing angle displays a white image, and thus, accurate gradation can be expressed under the front viewing angle, thereby further improving display quality. 9 is an exploded perspective view illustrating a liquid crystal display according to another exemplary embodiment of the present invention. The liquid crystal display of FIG. 9 is substantially the same as the liquid crystal display of FIG. 4 except for a backlight assembly as compared to the liquid crystal display of FIG. 4. Therefore, the same reference numerals are used for elements having the same structure and function as in FIG. 4, and detailed description thereof will be omitted.

Referring to FIG. 9, the liquid crystal display 1000 may include a display panel assembly 100 displaying an image using light and a backlight assembly 600 generating the light and providing the light to the display panel assembly 100. do. In addition, the liquid crystal display 1000 may include a first accommodating container 300 and a top chassis 400 accommodating the backlight assembly 600.

The backlight assembly 600 includes a lamp unit 610 that generates the light, a light guide plate 620, a reflector plate 640, and a second storage container 650. In addition, the backlight assembly 600 is disposed between the light guide plate 620 and the display panel assembly 100 and changes the path of the light emitted from the light guide plate 620 to incline the inclined light to the display panel assembly 100. Light path changing unit 670.

In this embodiment, the surface of the light guide plate 620 is flat. Alternatively, a specific pattern may be formed on the surface of the light guide plate 620.

Hereinafter, various embodiments of the light path changing unit 670 will be described.

10A-10E are vertical cross-sectional views of light path changing units.

10A is a vertical sectional view of the prism sheet to the light path changing unit.

The prism sheet 675 is formed with a pattern 677 having a triangular prism shape on its surface. The prism sheet 675 may not only collect light in the direction of the display panel 180 but also may provide optically various light paths according to the shape of the pattern.

10B is a vertical sectional view showing the microlens sheet as the light path changing unit.

The micro lens sheet 680 has microlenses 682 formed on a surface thereof. In this embodiment, the micro lenses 682 have an arcuate shape of irregular size. The micro lens 682 re-emits the light emitted to the light guide plate 620 through various paths due to the high refractive index of the micro lens. The microlenses 682 may be made of the same material as the sheet material or may be formed on the sheet as a separate material.

10C is a vertical sectional view showing the lens sheet as the light path changing unit.

The lens sheet 685 is made of a material having a high refractive index as a whole, and the whole sheet functions as one refractive lens. In this embodiment, the lens sheet 685 functions as a kind of lens as a whole, and the lens sheet 685 includes a convex lens or a concave lens.

10D is a vertical sectional view of the slit sheet as the light path changing unit.

The slit sheet 690 has a plurality of slits 692 formed at regular intervals. As the light emitted from the light guide plate 620 passes through the slit 692, the optical path is changed by diffraction. Depending on the aspect of the optical path required, the spacing and size of the slits can be appropriately adjusted from an optical point of view.

10E is a vertical cross-sectional view showing the refractive sheet as the light path changing unit.

The refractive sheet 695 is made of a material having a high refractive index n> 1 (refractive index of air: 1) and the refractive sheet has an inclined shape. The refractive sheet 695 changes a light path by forming a surface inclined relatively to a direction of a desired light path.

The light path changing units 670 include means for changing the light path in common. Means for changing the light path may be formed in some areas.

Although various forms of the optical path changing unit have been described above, those skilled in the art will appreciate that the optical path changing unit is not limited by the above embodiments.

Although not shown, in the liquid crystal display devices 500 and 1000 described in the above embodiments, an inverted prism sheet may be disposed as a reflection-refraction member to change a path of light between the backlight assembly and the display panel. Conventional prism sheet focuses the scattered light and emits light aligned in a certain direction, but the inverted prism sheet of the present invention can effectively adjust the incident angle of light by forming a reverse prism pattern, and furthermore, the surface of the reverse prism has an external light such as sunlight. The reflection efficiency can be maximized. The reflection-refraction member may be configured to reflect at least a portion of the internal light perpendicularly incident from the backlight assembly, and to reflect at least a portion of the external light incident from the outside to the surface of the reflection-refraction member, and to penetrate the surface. At least some external light performs a function of reflecting at the refractive pattern surface. The surface of the reflection-refraction member may be coated with at least a portion of a metal material having a high reflectance such as silver or aluminum to enhance the reflection function.

The liquid crystal display device 500 or 1000 may further include a first polarizer disposed between the backlight assembly and the reflective-refractive member and a second polarizer disposed on the display panel. The second polarizing plate has a polarization direction that crosses the polarization direction of the first polarizing plate.

Since the liquid crystal display according to the present invention employs a polymer dispersed liquid crystal (PDLC) mode, the manufacturing process related to the alignment layer and the polarizing plate is omitted, thereby simplifying the manufacturing process of the entire liquid crystal display.

In addition, since the PDLC display panel is applied to the liquid crystal display, the overall luminance and viewing angle may be improved.

Furthermore, the liquid crystal display device applies an inclined light from the backlight assembly to the display panel and forms a reflection and refraction pattern or a reflection-refraction member between the PDLC layer and the light source to provide an image of excellent quality with respect to the reflection and transmission light under the front viewing angle. I can display it.

Although described above with reference to the embodiments according to the present invention, those skilled in the art various modifications and changes to the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (20)

A display panel including a polymer dispersed liquid crystal layer; And And a backlight assembly disposed on a rear surface of the polymer liquid crystal layer to supply at least a part of light in a direction inclined with respect to the vertical direction of the incident surface of the polymer dispersed liquid crystal layer. The liquid crystal display of claim 1, wherein the liquid crystal display further comprises a reflection-refraction member for reflecting external light between the backlight assembly and the polymer dispersed liquid crystal layer and for internal light provided from the backlight assembly to be refracted. Display. The method of claim 2, wherein the reflection-refraction member has a flat surface and a back surface on which a refractive pattern is formed, thereby refracting and transmitting at least a portion of the internal light vertically incident from the backlight assembly and at least a portion of the external light incident from the outside to the surface. And an inverted prism sheet that reflects at the surface of the reflection-refraction member and reflects at least a part of external light passing through the surface in the refractive pattern plane. The liquid crystal display of claim 3, wherein a silver or aluminum pattern is formed on at least a portion of the reflection-refraction member to enhance reflection. The display panel of claim 1, wherein the display panel includes a first substrate disposed below the liquid crystal layer and a second substrate disposed above the liquid crystal layer. The first substrate and the second substrate when the power is applied to selectively generate an electric field in the liquid crystal layer, characterized in that the liquid crystal layer formed with the electric field to transmit light. 6. The liquid crystal display device according to claim 5, wherein the liquid crystal layer region in which the electric field is formed displays a black state under a front viewing angle. The method of claim 5, wherein the first substrate is divided into a plurality of pixel areas, A first base substrate; A thin film transistor layer formed on the first base substrate and including thin film transistors corresponding to the plurality of pixel regions, respectively; And And pixel electrodes formed on the thin film transistors of the pixel areas. The method of claim 7, wherein the first substrate further comprises a reflection-refraction pattern layer reflecting external light on one surface of the pixel electrode surface or a lower part of the pixel electrode and refracting internal light provided from a backlight assembly. A liquid crystal display device. The method of claim 5, wherein the second substrate, A second base substrate; A color filter layer formed on the second base substrate to implement colors of the liquid crystal display; And And a common electrode layer formed on the color filter layer and corresponding to the pixel electrodes. The method of claim 1, wherein the backlight assembly, A light source for generating light; And And a light guide plate disposed under the display panel and on the side of the light source, and configured to guide the light to direct the light emitted from the light source toward the display panel. The liquid crystal display of claim 10, wherein the light guide plate includes a plurality of light path changing patterns formed on at least a part of the exit surface to change the direction of the light. The liquid crystal display of claim 11, wherein the light path changing pattern has a triangular prism shape extending in one direction, and the light path changing patterns are continuously formed to be parallel to each other. The liquid crystal display of claim 12, wherein the light path change pattern has a right triangle pillar shape. The liquid crystal display of claim 1, wherein the liquid crystal display comprises an optical path changing unit between the backlight assembly and the display panel. 15. The liquid crystal display device according to claim 14, wherein the light path changing unit comprises a prism sheet having a triangular prism shape formed on at least part of its surface. The liquid crystal display of claim 14, wherein the light path changing unit comprises a microlens sheet having a microlens formed on at least part of the surface thereof. 15. The liquid crystal display device according to claim 14, wherein the light path changing unit comprises a lens sheet having a lens shape. The liquid crystal display of claim 14, wherein the optical path changing unit comprises a slit sheet having a plurality of slits formed at predetermined intervals. 15. The liquid crystal display device according to claim 14, wherein the optical path changing unit includes a refractive sheet for changing the optical path, and the refractive sheet has at least one inclined area. 3. The liquid crystal display of claim 2, wherein the liquid crystal display further comprises a first polarizer disposed between the backlight assembly and the reflective-refractive member, and a second polarizer disposed on the display panel, wherein the second polarizer is the first polarizer. And a polarization direction intersecting with the polarization direction of the liquid crystal display device.

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