KR20110056708A - Back light unit and liquid crystal display using the same - Google Patents

Abstract

PURPOSE: A backlight unit and a liquid crystal display using the same are provided to implement accurate local dimming and design for the slim size of the liquid crystal display. CONSTITUTION: A backlight unit comprises: a first light guide plate(210); a first light source which faces the one side of the first light guide plate; a second light source which faces the other side of the first light guide plate; a second light plate(220) which is arranged below the first light guide plate; a third light source(202c) which faces the one side of the second light guide plate; and a fourth light source which faces the other side of the third light guide plate.

Description

BACK LIGHT UNIT AND LIQUID CRYSTAL DISPLAY USING THE SAME}

The present invention relates to a backlight unit capable of local dimming and a liquid crystal display using the same.

BACKGROUND ART Liquid crystal display devices have tended to be gradually widened due to their light weight, thinness, and low power consumption. The liquid crystal display device is used as a portable computer such as a notebook PC, office automation equipment, audio / video equipment, indoor and outdoor advertising display devices, and the like. The transmissive liquid crystal display device, which occupies most of the liquid crystal display device, displays an image by controlling an electric field applied to the liquid crystal layer to modulate the light incident from the backlight unit.

The image quality of the liquid crystal display device depends on the contrast characteristics. Only the method of modulating the light transmittance of the liquid crystal layer by controlling the data voltage applied to the liquid crystal layer of the liquid crystal display panel has a limitation in improving the contrast characteristic. In order to improve the contrast characteristic, a backlight dimming control method for adjusting the brightness of the backlight unit according to an image has been developed, thereby dramatically improving the contrast characteristic. The backlight dimming control method may reduce power consumption by adaptively adjusting the brightness of the backlight unit according to the input image. The backlight dimming method includes a global dimming method for adjusting the luminance of the entire display surface and a local dimming method for locally adjusting the luminance of the display surface. The global dimming method can improve the dynamic contrast measured between the previous frame and the next frame. The local dimming method locally improves the brightness of the display surface within one frame period, thereby improving static contrast, which is difficult to improve with the global dimming method.

The backlight unit is divided into a direct type and an edge type. The direct type backlight unit evenly disposes light emitting diodes (LEDs) under the LCD panel and displays LEDs individually on and off to implement local dimming. Can be. However, the direct type backlight unit requires a large number of LEDs and requires a LED driving circuit for each LED package in order to individually control each LED, thereby increasing the manufacturing cost. In addition, the direct type backlight unit needs to make the distance between the LED packages and the diffuser plate sufficiently long to make the point light source appear as a surface light source, so the thickness of the direct backlight unit is difficult to implement a slimmer.

The edge type backlight unit arranges LEDs only at the edges of the liquid crystal display panel and converts the point light source into a surface light source using a light guide plate to diffuse the light to the entire screen. Compared to the direct backlight unit, the terrain backlight unit has a lower manufacturing cost because the required number of LEDs and LED driving circuits are smaller. In addition, since the edge type backlight unit is thinner and lighter than the direct type backlight unit, the edge type backlight unit is suitable for slimming and lightening the liquid crystal display device. However, the edge-type backlight unit has a disadvantage in that local dimming is difficult because light incident from the LEDs in the LGP interferes with and diffuses in the LGP.

For example, as shown in FIG. 1, only the first and second target blocks 13a and 13d appear bright in an edge type backlight in which LEDs 11u, 11b, 11l, and 11r are disposed at upper, lower, left, and right edges of the light guide plate 12. In order to do this, the upper end LED 11u and the left end LED 11l at positions orthogonal to the target blocks 13a and 13d are turned on. In this case, the light generated from the upper end LED 11u is totally reflected in the light guide plate 12 to propagate to the lower end of the light guide plate 12, and the light generated from the left end LED is totally reflected in the light guide plate 12 to guide the light. It propagates to the right end of (12). Therefore, unwanted blocks 13b and 13c are also bright in addition to the first and second target blocks 13a and 13d, and the target blocks 13a and 13b are diffused due to light diffusion in the light guide plate 12 as shown in FIG. 13d) and its broad portion 14, including its surroundings, are bright, making it difficult to achieve precise local dimming.

Accordingly, an aspect of the present invention is to provide a backlight unit and a liquid crystal display device using the same to enable slim and light weight design and to implement accurate local dimming.

The backlight unit of the present invention includes a first light guide plate; A first light source facing one side of the first light guide plate; A second light source facing the other side of the first light guide plate; A second light guide plate having a size smaller than that of the first light guide plate and disposed below the first light guide plate; A third light source facing one side of the second light guide plate; And a fourth light source facing the other side of the third light guide plate.

The liquid crystal display device of the present invention includes a liquid crystal display panel and the backlight unit.

According to the present invention, the backlight unit and the liquid crystal display device can be made slim and light by using a backlight unit having a stepped light guide plate, and precise local dimming can be realized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like numbers refer to like elements throughout. In the following description, when it is determined that a detailed description of known functions or configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Component names used in the following description are selected in consideration of ease of specification, and may be different from actual product names.

Referring to FIG. 3, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal display panel 100, a source driver 102 for driving data lines DL of the liquid crystal display panel 100, and a liquid crystal display panel. Irradiating light to the gate driver 103 for driving the gate lines GL of the 100, the timing controller 101 controlling the source driver 102 and the gate driver 103, and the liquid crystal display panel 100. The backlight unit 200 includes a light source driver 105 for driving the light sources of the backlight unit 200, and a local dimming controller 104 for controlling local dimming.

In the liquid crystal display panel 100, a liquid crystal layer is formed between two glass substrates. A plurality of data lines DL and a plurality of gate lines GL cross on the lower glass substrate of the liquid crystal display panel 100. The liquid crystal cells are arranged in a matrix form on the liquid crystal display panel 100 by the cross structure of the data lines DL and the gate lines GL. The lower glass substrate of the liquid crystal display panel 100 includes data lines DL, gate lines GL, a thin film transistor (TFT), a pixel electrode of a liquid crystal cell connected to a TFT, And a storage capacitor and the like are formed.

A black matrix, a color filter, and a common electrode are formed on the upper glass substrate of the liquid crystal display panel 100. The common electrode is formed on the upper glass substrate in a vertical electric field driving method such as twisted nematic (TN) mode and vertical alignment (VA) mode, and a horizontal electric field such as IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. The driving method is formed on the lower glass substrate together with the pixel electrode. A polarizing plate is attached to each of the upper glass substrate and the lower glass substrate of the liquid crystal display panel 100, and an alignment layer for setting the pretilt angle of the liquid crystal is formed on an inner surface of the liquid crystal display panel 100 in contact with the liquid crystal.

The pixel array of the liquid crystal display panel 100 and the light emitting surface of the backlight unit 200 opposite thereto are virtually divided into a plurality of blocks for local dimming. Each of the blocks includes i × j (i and j are positive integers of two or more) pixels and a backlight emitting surface that irradiates the pixels with light. Each pixel includes subpixels of three primary colors or more, and the subpixel includes a liquid crystal cell Clc.

The timing controller 101 receives timing signals Vsync, Hsync, DE, and DCLK from an external system board, and supplies digital video data RGB to the source driver 102. The timing signals Vsync, Hsync, DE, and DCLK include a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE, a dot clock signal DCLK, and the like. The timing controller 101 includes timing control signals DDC for controlling the operation timing of the source driver 102 and the gate driver 103 based on the timing signals Vsync, Hsync, DE, and DCLK from an external system board. , GDC). The system board or the timing controller 101 inserts an interpolation frame between the frames of the input video signal input at a frame frequency of 60 Hz, multiplies the source timing control signal DDC and the gate timing control signal GDC to 60 × N. (N is a positive integer of 2 or more) The operation of the source driver 102 and the gate driver 103 can be controlled at a frame frequency of Hz.

The timing controller 101 supplies digital video data RGB of an input image input from an external system board to the local dimming controller 104 and modulates the digital video data R modulated by the local dimming controller 104. 'G'B') is supplied to the source driver 102.

The source driver 102 latches the digital video data R'G'B 'under the control of the timing controller 101. The source driver 102 converts the digital video data R'G'B 'into positive / negative analog data voltages using the positive / negative gamma compensation voltages and supplies them to the data lines DL. .

The gate driver 103 includes a shift register, a level shifter for converting an output signal of the shift register into a swing width suitable for driving a TFT of a liquid crystal cell, an output buffer, and the like. The gate driver 103 is configured of a plurality of gate drive integrated circuits to sequentially output gate pulses (or scan pulses) having a pulse width of approximately one horizontal period. The gate pulses are sequentially supplied to the gate lines GL in synchronization with the data voltages supplied to the data lines DL.

The backlight unit 200 is disposed under the liquid crystal display panel 100. The backlight unit 200 uniformly irradiates light to the liquid crystal display panel 100 including a plurality of light sources individually controlled for each block by the light source driver 105. The backlight unit 200 is implemented as an edge type backlight unit capable of local dimming. The backlight unit 200 includes a light guide plate structure as shown in FIGS. 4 to 14 and light sources disposed on side surfaces of the light guide plate. The light sources of the backlight unit 200 include a plurality of light emitting diodes (LEDs).

The light source driver 105 individually controls the light sources of the backlight unit 200 for each block by pulse width modulation (PWM) in which the duty ratio is changed according to the dimming value BLdim input from the local dimming controller 104. . The pulse width modulated signal PWM controls a ratio of turning on and off the light sources, and the duty ratio% is determined according to the dimming value BLdim output from the local dimming control unit 104. The micro control unit (MCU) of the light source driver 105 turns on the light sources of the backlight unit 200 block by block in a SPI (Serial Peripheral Interface) method.

The local dimming controller 104 analyzes the digital video data RGB input from the timing controller 101 for each block to calculate a representative value for each block of the blocks. The representative value for each block may be calculated as an average value or average picture level (APL) of the input image. The average value of the input image is the average value of the highest values among the RGB values of the pixel, and the average image level APL is the average value of the luminance values Y of the pixels. The local dimming controller 104 maps a representative value for each block to a preset dimming curve, outputs a block-specific dimming value BLdim of the backlight unit 200, and digital video data RGB input from the timing controller 101. By modulating the pixel data to compensate pixel data to be displayed on the liquid crystal display panel 100. The local dimming control unit 104 codes the block-specific dimming value BLdim into data in an SPI format and supplies the block-based dimming value BLdim to the micro control unit MCU of the light source driver 105.

4 to 7 show a backlight unit according to a first embodiment of the present invention.

4 to 7, the backlight unit of the present invention is disposed on both sides of the first LGP 210, the second LGP 220 disposed below the first LGP 210, and the first LGP 210. First and second LED arrays 202a and 202b and third and fourth light source arrays 202c and 202d disposed on both sides of the second LGP 220.

The first and second light guide plates 210 and 220 include transparent resins such as polycarbonate (PC), polymethacrylimide (PMMA), cyclo-olefine-polymer (COP), and the like.

The first LED array 202a is disposed at the upper side of the first LGP 210, and the second LED array 202b is disposed at the lower side of the first LGP 210. As illustrated in FIG. 6, the first LED array 202a illuminates the upper side surface of the first LGP 210 to light up the first blocks BL1 at the uppermost stage during local dimming. As shown in FIG. 6, the second LED array 202b illuminates the lower side surface of the first LGP 210 to light the fourth blocks BL4 at the lowermost end during local dimming.

The horizontal length of the second light guide plate 220 (the length in the x-axis direction in FIG. 6) is substantially the same as that of the first light guide plate 210, and the vertical length of the second light guide plate 220 (the y-axis direction in FIG. 6). Length) is smaller than that of the first LGP 210. The second LGP 220 is disposed below the first LGP 210 to overlap the center portion of the first LGP 210. The third LED array 202c is disposed under the first light guide plate 210 so as to face the upper side surface of the second light guide plate 220. As shown in FIG. 6, the third LED array 202c illuminates the upper side surfaces of the second LGP 220 to light up the second blocks BL2 disposed at the upper end of the central block rows during local dimming. The fourth LED array 202d illuminates the lower side surface of the second LGP 220 to light up the third blocks BL3 disposed at the lower end of the central block lamp during local dimming.

The backlight unit of the present invention includes a plurality of optical sheets 230 disposed between the liquid crystal display panel 100 and the first LGP 210, and a cover bottom disposed below the LGPs 210 and 220. Not included).

The optical sheets 230 include one or more prism sheets and one or more diffusion sheets to diffuse light incident from the diffuser plate and to propagate light at an angle substantially perpendicular to the light incident surface of the liquid crystal display panel. Refraction The optical sheets 230 may include a dual brightness enhancement film (DBEF).

The cover bottom is disposed under the light guide plates 210 and 220 to support the entire backlight unit 200 from below and protect the backlight unit from shock or vibration from the outside.

The present invention drives the first and second LED arrays 202a and 202b to selectively light the first and fourth blocks according to the input image, and drives the third and fourth LED arrays 202c and 202d. Local dimming is implemented by selectively lighting the second and third blocks according to the input image. 7 is a diagram illustrating a result of a local dimming experiment of the backlight unit 200 of FIGS. 4 to 6. As can be seen in Figure 7, the present invention can implement precise local dimming by selectively lighting only the target block using the edge type backlight unit 200.

8 is a cross-sectional view of a backlight unit according to a second embodiment of the present invention.

In the backlight unit illustrated in FIG. 8, the first LGP 210 is divided into a plurality of upper LGPs 211 to 213, and the second LGP 220 is a plurality of lower LGPs, compared to the backlight unit of the first embodiment. Only those separated by 221 and 222 are different, and the other configurations are substantially the same.

The first LED array 202a is disposed on an upper side surface of the first upper light guide plate 211. As illustrated in FIG. 6, the first LED array 202a illuminates the side surface of the first upper light guide plate 211 to light up the first blocks BL1 at the uppermost stage during local dimming. The second LED array 202b is disposed on the lower side surface of the second upper light guide plate 212. As shown in FIG. 6, the second LED array 202b illuminates the lower side surface of the second upper light guide plate 212 to light up the fourth blocks BL4 at the lowermost end during local dimming. The third upper LGP 213 is disposed between the first and second upper LGPs 211 and 212 and overlaps the lower LGPs 221 and 222. The third upper light guide plate 213 transmits light from the lower light guide plates 221 and 222 toward the optical sheets 230 and the liquid crystal display panel 100.

The horizontal length (length in the x-axis direction in FIG. 6) of each of the lower light guide plates 221 and 222 is substantially the same as that of the upper light guide plates 211 to 213, and the vertical length of the lower light guide plates 221 and 222. The sum (the length in the y-axis direction in FIG. 6) is smaller than the longitudinal length sum of the upper light guide plates 213. The first and second lower LGPs 221 and 222 are disposed under the third upper LGP 213. The third LED array 202c faces the upper side of the first lower light guide plate 221. As shown in FIG. 6, the third LED array 202c illuminates the upper side of the first lower LGP 221 to light the second blocks BL2 at the time of local dimming. The fourth LED array 202d faces the bottom side of the second lower light guide plate 222. The fourth LED array 202d illuminates the lower side surface of the second light guide plate 220 to light up the third blocks BL3 at the time of local dimming.

Reflectors may be coated on the divided surfaces 214 of the upper LGPs 211 to 213 and the divided surfaces 223 of the lower LGPs 221 and 222. The reflector reflects the light that can diffuse to the neighboring block to increase the brightness of the block that is lit when the local dimming and block the diffusion of light between the blocks.

9 is a cross-sectional view of a backlight unit according to a third embodiment of the present invention.

In the backlight unit illustrated in FIG. 9, a plurality of first block division patterns 215 are formed on the first LGP 210 and a plurality of second LGPs are formed on the second LGP 220 as compared with the backlight unit of the first embodiment. Only the two block division pattern 224 is formed, and the other configurations are substantially the same.

The first block dividing patterns 215 may be formed in an intaglio, embossed, or intaglio pattern on the top surface 210u, the bottom surface 210b, or the top surface 210u and the bottom surface 210b of the first LGP 210. The first block dividing patterns 215 may have a cross section of a triangle (or prism), a hemispherical shape (or lenticular), a rectangle (or a ractangle). The first block dividing patterns 215 are positioned at the boundary between the blocks and the upper light guide plate illustrated in FIG. 8 to block the diffusion of light between the blocks and to improve the straightness of the light.

The second block division patterns 224 may be formed in an intaglio, embossed, or intaglio pattern on the top surface 220u, the bottom surface 220b, or the top surface 220u and the bottom surface 220b of the second light guide plate 220. The second block dividing patterns 224 have a cross section of a triangular (or prism), hemispherical (or lenticular), rectangular (or ractangle) or the like. The second block dividing patterns 215 are positioned at the boundary between the blocks and the lower light guide plates shown in FIG. 8 to block the diffusion of light between the blocks and to improve the straightness of the light.

On the lower surface 210b of the first LGP 210 (or upper LGPs) that do not overlap with the second LGP (or lower LGPs), fine patterns are formed to increase the uniformity of the light incident on the LCD panel 100. Is formed.

Each of the first light guide plate 210 or the upper light guide plates and the second light guide plate 220 or the lower light guide plates may be manufactured in the form of a flat plate or a wedge plate. Each of the first LGP 210 or the upper LGPs and the second LGP 220 or the lower LGPs has a thickness H between 0.5 mm and 4 mm, as shown in FIG. 10. The block division patterns 224 have a depth (or height) between 10 μm and 300 μm. The fine patterns formed on the lower surfaces 210b and 220b of the light guide plates 210 and 220 have a depth (or height) between 5 μm and 200 μm. The depth (or height) of the fine patterns is smaller than that of the block division patterns 224.

11 is a cross-sectional view of a backlight unit according to a fourth embodiment of the present invention. In the following embodiments, the same reference numerals are used to designate substantially the same elements as the above-described embodiments, and a detailed description thereof will be omitted.

Referring to FIG. 11, the backlight unit of the present invention may include the integrated light guide plate 300, the first and second light source arrays 202a and 202b disposed on both sides of the integrated light guide plate 300, and a lower portion of the integrated light guide plate 300. Third and fourth light source arrays 202c and 202d are disposed on both sides.

The integrated light guide plate 300 includes a transparent resin such as polycarbonate (PC), polymethacrylimide (PMMA), cyclo-olefine-polymer (COP), or the like. A method of manufacturing the integrated light guide plate 300 will be described later with reference to FIG. 12.

The integrated LGP 300 has a structure in which the aforementioned first LGP 210 or upper LGPs and the second LGP 220 or lower LGPs are bonded to each other. The upper portion of the integrated light guide plate 300 has a larger area than the lower portion. The lower portion of the integrated light guide plate 300 protrudes downward from the center portion of the light guide plate 300.

As illustrated in FIG. 6, the first LED array 202a illuminates an upper side of the integrated light guide plate 300 to light up the first blocks BL1 at the uppermost stage when local dimming. As shown in FIG. 6, the second LED array 202b illuminates the other upper surface of the integrated light guide plate 300 to light up the fourth blocks BL4 at the lowermost end during local dimming.

As shown in FIG. 6, the third LED array 202c illuminates the lower one side of the integrated light guide plate 300 to light up the second blocks BL2 at the time of local dimming. The fourth LED array 202d illuminates the other bottom surface of the integrated light guide plate 300 to light up the third blocks BL3 during local dimming.

12 illustrates a method of manufacturing the integrated light guide plate 300.

Referring to FIG. 12, the light guide plate manufacturing method of the present invention manufactures a pattern mold 401 having an intaglio pattern. The intaglio pattern of the pattern mold 401 has an inverted form of the lower protrusion of the integrated light guide plate 300.

In the light guide plate manufacturing method of the present invention, a liquid light guide plate resin 301 is applied to the pattern mold 401. The light guide plate resin includes a photoinitiator and a light binder. Subsequently, in the method of manufacturing a light guide plate of the present invention, after pressing the transparent plate member 501 on the light guide plate resin 301 applied to the pattern mold 401, light of ultraviolet or infrared wavelengths is transmitted to the light guide plate resin through the transparent plate member 501. Irradiation induces curing of the light guide plate resin 301. Finally, the light guide plate manufacturing method of the present invention separates the pattern mold 401 and the transparent plate member 501 from the integrated light guide plate 300.

13 is a cross-sectional view of a backlight unit according to a fifth embodiment of the present invention.

The backlight unit illustrated in FIG. 13 differs from the backlight unit of the fourth exemplary embodiment in that the integrated light guide plate 300 is divided into a plurality of light guide plates 301 to 304, and the other configurations are substantially the same. Each of the dividing surfaces 305 of the light guide plates 301 to 304 may be coated with a reflector.

14 is a cross-sectional view of a backlight unit according to a sixth embodiment of the present invention.

The backlight unit illustrated in FIG. 14 differs from the backlight unit of the fourth exemplary embodiment in that the plurality of block division patterns 306 are formed in the integrated light guide plate 300, and the other configurations are substantially the same.

The block division patterns 306 are formed in an intaglio, an intaglio, or an intaglio pattern on the top surface 300u, the bottom surface 300b, or the top surface 300u and the bottom surface 300b of the integrated light guide plate 300. The block division patterns 306 have a cross section such as a triangular (or prism), hemispherical (or lenticular), square (or ractangle) or the like. The block division patterns 306 are positioned at the boundary between the blocks and the light guide plates shown in FIG. 13 to block the diffusion of light between the blocks and to improve the straightness of the light.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 and 2 are views showing optical interference and diffusion effects of an existing edge type backlight unit.

3 is a block diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a perspective view illustrating a light guide plate and a light source of the backlight unit according to the first embodiment of the present invention.

5 is a cross-sectional view of the backlight unit according to the first embodiment of the present invention.

6 is a plan view of the backlight unit according to the first embodiment of the present invention as viewed from above.

FIG. 7 is a diagram illustrating a result of an experiment of a local dimming operation of a backlight unit according to a first exemplary embodiment of the present invention.

8 is a cross-sectional view of a backlight unit according to a second embodiment of the present invention.

9 is a cross-sectional view of a backlight unit according to a third embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating in detail the light guide plate illustrated in FIGS. 4 to 9.

11 is a cross-sectional view of a backlight unit according to a fourth embodiment of the present invention.

FIG. 12 is a view illustrating a method of manufacturing the light guide plate shown in FIG. 11.

13 is a cross-sectional view of a backlight unit according to a fifth embodiment of the present invention.

14 is a cross-sectional view of a backlight unit according to a sixth embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: liquid crystal display panel 202a ~ 202d: LED array

210 ~ 213, 220 ~ 222, 300: Light guide plate

Claims (10)

A first light guide plate; A first light source facing one side of the first light guide plate; A second light source facing the other side of the first light guide plate; A second light guide plate having a size smaller than that of the first light guide plate and disposed below the first light guide plate; A third light source facing one side of the second light guide plate; And And a fourth light source facing the other side of the third light guide plate. The method of claim 1, The second light guide plate overlaps with the center portion of the first light guide plate. The method of claim 1, And the first light guide plate is divided into a plurality of small light guide plates. The method according to claim 1 or 3, And the second light guide plate is divided into a plurality of small light guide plates. The method according to claim 1 or 3, Fine patterns are formed on lower surfaces of each of the first and second LGPs to increase surface uniformity of light. Block division patterns are formed on at least one of an upper surface and a lower surface of each of the first and second light guide plates, The block division patterns may be formed of any one of an intaglio pattern, an embossed pattern, and an embossed pattern deeper or higher than the fine patterns. The method of claim 1, And the first and second light guide plates are integrated. A liquid crystal display panel; And An edge type backlight unit disposed under the liquid crystal display panel and radiating light to the liquid crystal display panel in units of blocks divided by a local dimming method; The edge type backlight unit, A first light guide plate; A first light source facing one side of the first light guide plate; A second light source facing the other side of the first light guide plate; A second light guide plate having a size smaller than that of the first light guide plate and disposed below the first light guide plate; A third light source facing one side of the second light guide plate; And And a fourth light source facing the other side of the third light guide plate. The method of claim 7, wherein And the second light guide plate overlaps with a center portion of the first light guide plate. The method of claim 7, wherein And the first and second light guide plates are integrated. The method of claim 7, wherein A light source driver for driving the light sources in units of blocks; And dimming value of each block by selecting an input image, controlling the light source driver based on the dimming value of each block, and compensating pixel data to be input to the liquid crystal display panel.

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