KR101635216B1 - Backlight unit and liquid crystal display using the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a backlight unit capable of improving video response time performance and local dimming performance, and a liquid crystal display using the same. A backlight unit according to an embodiment of the present invention includes a first light pipe; A second light guide plate disposed below the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and including a plurality of first light sources for supplying light to the first light guide plate; And a second light source unit disposed on at least one side of the second light guide plate and having a plurality of second light sources for supplying light to the second light guide plate, wherein the first light guide plate includes a light guide plate Wherein a first pattern region and a first patterned region are alternately arranged on a bottom surface of each of the first waveguide channels and a relationship with a remaining adjacent first waveguide channels Wherein the second light guide plate includes a plurality of second wave guide channels formed by a traveling direction of light emitted from the second light sources, A second patterned region is formed on the bottom surface of each of the second waveguide channels so as to overlap the first patterned region of the first waveguide channel, To overlap with the pattern region is characterized in that the second pattern region is formed.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY USING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a liquid crystal display using the same, and more particularly, to a backlight unit capable of improving moving picture response time (hereinafter referred to as MPRT) performance and local dimming performance, To a liquid crystal display device using the same.

BACKGROUND ART [0002] Liquid crystal display devices are becoming increasingly widespread due to features such as light weight, thinness, and low power consumption driving. This liquid crystal display device is used as a portable computer such as a notebook PC, an office automation device, an audio / video device, and an indoor / outdoor advertisement display device. A transmissive liquid crystal display device that occupies most of the liquid crystal display device displays an image by controlling an electric field applied to the liquid crystal layer and modulating light incident from the backlight unit, and a thin film transistor (hereinafter referred to as "TFT & ) Is used to display a moving picture using an active matrix driving method.

When a moving image is displayed through a liquid crystal display device, MPRT performance may be degraded due to the retention characteristic of the liquid crystal, so that a blurred image may appear that is blurry and blurred. In order to improve MPRT performance, a scanning backlight driving technique has been proposed. 1 and 2, the scanning backlight driving technique sequentially flashes the light sources of the backlight unit along the scanning direction of the display line to provide an effect similar to the impulsive driving of the CRT, .

However, since the scanning backlight driving technique must be able to control the light emitted to the liquid crystal display panel in the unit of the scanning block, the position of the light sources in the backlight unit is limited. The backlight unit is roughly classified into a direct type and an edge type depending on the arrangement position of the light source. The direct-type backlight unit has a structure in which a plurality of optical sheets and a diffusion plate are stacked below a liquid crystal display panel and a plurality of light sources are disposed under a diffusion plate, so that a scanning backlight is easily implemented. On the other hand, the edge type backlight unit has a structure in which a light source is disposed so as to face the side face of the light guide plate, and a plurality of optical sheets are disposed between the liquid crystal display panel and the light guide plate. The edge type backlight unit is structured such that the light source irradiates light to one side of the light guide plate and the light guide plate converts the light into plane light. Therefore, the light emitted to the liquid crystal display panel, It is difficult to implement the scanning backlight. Therefore, there is a need for a scanning backlight that can be implemented in an edge type backlight.

On the other hand, the image quality of the liquid crystal display device depends on the contrast characteristics. The method of modulating the light transmittance of the liquid crystal layer by controlling the data voltage applied to the liquid crystal layer limits the improvement of the contrast characteristic. In order to improve the contrast characteristic, various backlight dimming control methods for adjusting the brightness of the backlight unit according to an image have been attempted.

The backlight dimming control method may reduce the power consumption by adjusting the brightness of the backlight unit according to the input image. The backlight dimming method includes a global dimming method for adjusting the brightness of the entire display surface and a local dimming method for locally adjusting the brightness of the display surface.

The global dimming method can improve the dynamic contrast ratio measured between the previous frame and the next frame. The local dimming method can improve the static contrast that is difficult to improve by the global dimming method by locally controlling the brightness of the display surface within one frame period. However, the conventional local dimming method not only induces luminance difference and flicker between a plurality of blocks partitioned in the display plane, but also requires a lot of circuit elements in the local dimming circuit, so that the circuit configuration is complicated and the algorithm is complicated. Further, the local dimming method is disadvantageous in that it is implemented only in a liquid crystal display device using a direct-type backlight unit. However, since the direct-type backlight unit must include a diffusion plate disposed at a certain distance from the light source in order to diffuse the light incident from the lamp to uniformize the brightness of the display surface, it is difficult to reduce the thickness of the backlight unit. In recent years, due to the trend of thinning of the liquid crystal display apparatus, although the interval between the diffusion plate and the light sources is narrowed, the light from the light source is not sufficiently diffused, so that the luminance uniformity of the display image There is a falling problem. Thus, a need has arisen for a technique for implementing local dimming in an edge type backlight unit.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a backlight unit and a liquid crystal display using the same, which can improve the MPRT performance without optical interference due to the difference in the light-off timing of the light sources.

It is another object of the present invention to provide a backlight unit capable of improving moving picture characteristics by improving the performance of local dimming and increasing a dynamic contrast ratio and a liquid crystal display using the same.

According to an aspect of the present invention, there is provided a backlight unit comprising: a first light pipe; A second light guide plate disposed below the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and including a plurality of first light sources for supplying light to the first light guide plate; And a second light source unit disposed on at least one side of the second light guide plate and having a plurality of second light sources for supplying light to the second light guide plate, wherein the first light guide plate includes a light guide plate Wherein a first pattern region and a first patterned region are alternately arranged on a bottom surface of each of the first waveguide channels and a relationship with a remaining adjacent first waveguide channels Wherein the second light guide plate includes a plurality of second wave guide channels formed by a traveling direction of light emitted from the second light sources, A second patterned region is formed on the bottom surface of each of the second waveguide channels so as to overlap the first patterned region of the first waveguide channel, A second pattern area is formed to overlap with the non-pattern area, the second pattern area is alternately disposed with the second pattern area, and the first pattern areas and the first pattern area And a plurality of blocks are formed by the second pattern regions and the second patternless regions formed on the second light guide plate.

In the above configuration, the first waveguide channel and the second waveguide channel are vertically overlapped or crossed vertically.

Also, the number of the first waveguide channels is equal to the number of the first light sources, and the number of the second waveguide channels is equal to the number of the second light sources.

In addition, at least one of the plurality of fine engraved patterns and the fine embossed patterns may be formed in the first and second pattern regions, and the fine engraved patterns or the fine embossed patterns may be formed on the first or second light source It is preferable that the distance from the center to the center is dense.

A liquid crystal display according to an embodiment of the present invention includes a liquid crystal display panel; A panel driving circuit for driving data lines and gate lines of the liquid crystal display panel; A timing controller for controlling the panel driving circuit; A backlight unit for supplying light to be irradiated to the liquid crystal display panel; A light source control circuit for generating a PWM signal for controlling lighting of light supplied from the backlight unit; And a light source driving circuit for supplying or cutting off the light in response to the PWM signal. The backlight unit has the above-described characteristics.

A liquid crystal display according to another embodiment of the present invention includes a liquid crystal display panel; A panel driving circuit for driving data lines and gate lines of the liquid crystal display panel; A timing controller for controlling the panel driving circuit; A backlight unit for supplying light to be irradiated to the liquid crystal display panel; A light source control circuit for controlling light supplied from the backlight unit; And an image analysis circuit for analyzing the input image and controlling the light source control circuit according to the analysis result, wherein the backlight unit has the above-described characteristics.

A liquid crystal display according to another embodiment of the present invention includes a liquid crystal display panel; And a backlight unit for supplying light to be irradiated to the liquid crystal display panel, wherein the backlight unit has the above-described characteristics.

According to the backlight unit and the liquid crystal display device according to the embodiment of the present invention, the first waveguide channels of the first light pipe and the second waveguide channels of the second light pipe are vertically arranged to overlap with each other, Since the matrix-shaped blocks are formed by alternately arranging the non-patterned areas, the image degradation phenomenon with an increase in the number of blocks is reduced, and the local dimming performance is improved and the dynamic contrast ratio is improved. In addition, according to the above-described configuration, since the scanning implementation characteristic is improved and the MPRT characteristic is improved, an effect of improving moving image implementation characteristic can be obtained.

Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 3 to 10B. Like reference numerals refer to like elements throughout the specification.

First, a liquid crystal display according to a first embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a block diagram schematically showing a liquid crystal display according to a first embodiment of the present invention, and FIG. 4 is a circuit diagram showing equivalently a part of a pixel array of the liquid crystal display panel shown in FIG.

3 and 4, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal display panel 10, a data driving circuit 12 for driving data lines DL of a liquid crystal display panel 10, A gate driving circuit 13 for driving the gate lines GL of the liquid crystal display panel 10, a timing controller 11 for controlling the data driving circuit 12 and the gate driving circuit 13, A first light source driving circuit 21 for driving the first upper light source unit 23 and the first lower light source unit 24 of the backlight unit, a second light source driving unit 21 for driving the second upper light source unit A second light source driving circuit 22 for driving the second light source driving circuit 25 and the second lower light source unit 26 and a light source control circuit 22 for controlling the first and second light source driving circuits 21 and 22 in accordance with the light source flashing timing, (14). The data driving circuit 12 and the gate driving circuit 13 constitute a panel driving circuit.

The liquid crystal display panel 10 includes two glass substrates and a liquid crystal layer formed therebetween. A plurality of data lines 12a to 12d (DL) and a plurality of gate lines 13a to 13d (GL) are crossed on the lower glass substrate of the liquid crystal display panel 10 as shown in FIG. The liquid crystal cells Clc are arranged in a matrix form in the liquid crystal display panel 10 by the intersection structure of the data lines DL and the gate lines GL. A thin film transistor (TFT), a pixel electrode 1 of a liquid crystal cell Clc connected to a thin film transistor (TFT), a storage capacitor Cst, and the like are formed on the lower glass substrate of the liquid crystal display panel 10. The liquid crystal cells Clc are connected to the TFT and driven by the electric field between the pixel electrodes 1 and the common electrode 2. [ The data lines DL are formed in a relatively short vertical axis direction (hereinafter, referred to as a "y-axis direction") and the gate lines GL are formed in a relatively long horizontal axis direction ). The liquid crystal display panel 10 scans the data in the x-axis direction by the operation of the panel driving circuit.

On the upper glass substrate of the liquid crystal display panel 10, a black matrix, a color filter, and the like are formed. The common electrode 2 is formed on an upper glass substrate in a vertical electric field driving mode such as a TN (Twisted Nematic) mode and a VA (Vertical Alignment) mode. The common electrode 2 is formed of an IPS (In Plane Switching) mode, an FFS (Fringe Field Switching) Is formed on the lower glass substrate together with the pixel electrode 1 in the same horizontal electric field driving system. On the upper glass substrate and the lower glass substrate of the liquid crystal display panel 10, a polarizing plate is attached and an alignment film for setting a pre-tilt angle of the liquid crystal is formed.

The data driving circuit 12 includes a plurality of data drive ICs. The data drive IC includes a shift register for sampling the clock signal, a register for temporarily storing the digital video data (RGB), a data register for storing the data for one line in response to the clock signal from the shift register, A digital / analog converter for selecting a positive / negative gamma voltage under reference to a gamma reference voltage corresponding to a digital data value from a latch and latch for outputting simultaneously, an analog / digital converter converted by a positive / negative gamma voltage, A multiplexer for selecting a data line DL to which data is supplied, and an output buffer connected between the multiplexer and the data line DL. The data driving circuit 12 latches the digital video data RGB under the control of the timing controller 11 and outputs the latched digital video data RGB to the positive polarity / Polarity analog data voltage, and supplies it to the data lines DL.

The gate drive circuit 13 includes a plurality of gate drive integrated circuits. The gate drive integrated circuit includes a shift register, a level shifter for converting an output signal of the shift register into a swing width suitable for TFT driving of the liquid crystal cell, and an output buffer. The gate drive circuit 13 sequentially outputs a scan pulse (or a gate pulse) under the control of the timing controller 11 and supplies the scan pulse (or the gate pulse) to the gate lines GL so that a vertical line in the y- Select one line along the axial direction.

The timing controller 11 rearranges digital video data (RGB) input from an external system board in accordance with the resolution of the liquid crystal display panel 10, and supplies the digital video data RGB to the data driving circuit 12.

The timing controller 11 generates timing control signals for controlling the operation timings of the data driving circuit 12 and the gate driving circuit 13 based on the timing signals Vsync, Hsync, DE, DCLK from the system board DDC, GDC). The timing controller 11 controls the timing controller 11 so that the digital video data RGB input at a frame frequency of 60 Hz can be displayed on the liquid crystal display panel 10 at a frame frequency of 60 x N (N is a positive integer of 2 or more) The operations of the data driving circuit 12 and the gate driving circuit 13 are performed at a frame frequency of 60 x N (where N is a positive integer equal to or greater than 2) Hz by multiplying the control signal DDC and the gate timing control signal GDC Can be controlled. The operation of multiplying the frame frequency may be performed in an external system circuit.

The backlight unit includes a first light guide plate 201 and a second light guide plate 202 disposed under the first light guide plate 201. A first upper light source unit 23 emits light from both sides of the first light guide plate 201, A first lower light source unit 24 and a second lower light source unit 26 that emit light from both sides of the second upper light source unit 25 and the second light guide plate 202 and a first light guide plate 201 and a liquid crystal display panel 10 And a plurality of optical sheets stacked between the optical sheets.

The light sources 23, 24, 25 and 26 may be implemented with a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL), more preferably a light emitting diode Light Emitting Diode (LED). Although the light source units 23, 24, 25, and 26 are disposed on both sides of the first and second light guide plates 201 and 202 in the exemplary embodiment of the present invention, they may be disposed on only one side. The light sources 23, 24, 25, and 26 are sequentially driven in units of backlight scanning blocks along the x-axis direction in accordance with the data scanning direction of the liquid crystal display panel 10.

The first and second light guide plates 201 and 202 constituting the backlight unit will be described later.

The optical sheets include one or more prism sheets and one or more diffusion sheets to diffuse light incident from the first and second light guide plates 201 and 202 and to diffuse the light incident from the light incident surface of the liquid crystal display panel 10 substantially vertically Refracts the path of the light at an angle of incidence. The optical sheets may include a dual brightness enhancement film (DBEF).

The light source control circuit 14 controls the light source units 23 and 24 such that the light source units 23, 24, 25 and 26 are sequentially driven in units of the backlight scanning blocks along the data scanning direction (x axis direction) of the liquid crystal display panel 10 25, and 26 are controlled by pulse width modulation (PWM). The light source control circuit 14 may analyze the input digital video data RGB and adjust the duty ratio of the PWM signal according to the analysis result. The light source control circuit 14 may be incorporated in the timing controller 11. [

The light source driving circuits 21 and 22 sequentially drive the light source units 23, 24, 25 and 26 in synchronization with the data scanning of the liquid crystal display panel 10 under the control of the light source control circuit 14. [ The turn-on time (ON / OFF) of the light source units 23, 24, 25 and 26 is determined in accordance with the PWM signal from the light source control circuit 14. [ The lighting time (ON) of the light source units 23, 24, 25, and 26 becomes longer as the duty ratio of the PWM signal becomes higher, and becomes shorter as the duty ratio of the PWM signal becomes lower. That is, the lighting time (ON) of the light sources 23, 24, 25, and 26 is proportional to the duty ratio of the PWM signal.

Next, a liquid crystal display according to a second embodiment of the present invention will be described with reference to FIG. 5 is a view schematically showing a liquid crystal display device according to a second embodiment of the present invention. In the description of the second embodiment, the same reference numerals as those of the first embodiment are assigned to the same constituent elements as those of the first embodiment, and a description of the same constituent elements as those of the first embodiment will be omitted for the sake of simplicity .

5, a liquid crystal display according to a second embodiment of the present invention includes a liquid crystal display panel 10, a data driving circuit 12 for driving data lines DL of the liquid crystal display panel 10, A gate drive circuit 13 for driving the gate lines GL of the liquid crystal display panel 10, a timing controller 11 for controlling the data drive circuit 12 and the gate drive circuit 13, a liquid crystal display panel A first light source driving circuit 21 for driving the first upper light source unit 23 and the first lower light source unit 24 of the backlight unit and a second light source driving circuit 21 for driving the second upper light source unit 25 And a second light source driving circuit 22 for driving the second lower light source unit 26. The second light source driving circuit 22 analyzes the input image and controls the first and second light source driving circuits 21 and 22 And an analysis circuit 16.

The liquid crystal display panel 10, the data driving circuit 12, the gate driving circuit 13, and the timing controller 11 are the same as those in the first embodiment, and a description thereof will be omitted.

The first light source driving circuit 21 adjusts the current intensity separately supplied to the first upper light source unit 23 and the first lower light source unit 24 under the control of the image analysis circuit 16. [ That is, the first light source driving circuit 21 is provided with a first light source driving circuit 21, which corresponds to a bright portion of the display image displayed on the liquid crystal display panel 10 in accordance with the local dimming signal LDIM from the image analysis circuit 16 1, which controls other blocks corresponding to the dark portions of the display image displayed on the liquid crystal display panel 10 while adjusting the current supplied to the light sources of the first and second lower light sources 23 and 24, The current supplied to the first light source unit 23 and the light sources of the first lower light source unit 24 is relatively low.

The second light source driving circuit 22 adjusts the current intensity separately supplied to the second upper light source unit 25 and the second lower light source unit 26 under the control of the image analysis circuit 16. [ That is, the second light source driving circuit 22 is provided with a plurality of pixels (not shown) corresponding to the bright portions of the display image displayed on the liquid crystal display panel 10 in accordance with the local dimming signal LDIM from the image analysis circuit 16 The current supplied to the light sources of the second upper light source unit 25 and the second lower light source unit 26 is adjusted to be higher while the current supplied to the light sources of the second lower light source unit 26 The current supplied to the other light sources of the two upper light source unit 25 and the second lower light source unit 26 is adjusted to be relatively low.

The image analysis circuit 16 analyzes the digital video data (RGB) input from the system board, maps the input image to the blocks B11 to B46 shown in FIG. 8, and uses an image analysis technique such as histogram analysis The luminance of the input image is analyzed by the block size unit. The image analysis circuit 16 generates a local dimming signal LDIM for adjusting the supply current of the light sources 23, 24, 25 and 26 in proportion to the luminance analyzed in the block size, And controls the drive circuits 21 and 22. The image analysis circuit 16 synchronizes the timing of driving the light sources 23, 24, 25, and 26 with the timing control unit 11 by the input timing signals Vsync, Hsync, DE, DCLK, (RGB). The image analysis circuit 16 may be mounted on an external system board or embedded in the timing control section 11. [

The backlight unit includes a first light guide plate 201 and a second light guide plate 202 disposed under the first light guide plate 201. A first upper light source unit 23 emits light from both sides of the first light guide plate 201, A first lower light source unit 24 and a second lower light source unit 26 that emit light from both sides of the second upper light source unit 25 and the second light guide plate 202 and a first light guide plate 202 and a liquid crystal display panel 10 And a plurality of optical sheets stacked between the optical sheets.

The light sources 23, 24, 25, and 26 may be implemented as CCFL or EEFL, and may be implemented as an LED. Although the light source units 23, 24, 25, and 26 are disposed on both sides of the first and second light guide plates 201 and 202 in the embodiment of the present invention, they may be disposed on only one side.

The backlight unit including the light source units 22, 23, 24, and 25 and the first and second light guide plates 201 and 202 will be described in more detail with reference to FIGS. 6A to 9. 6A is a plan view showing the arrangement relationship between the first light guide plate 201 and the first and second upper light sources 23 and 25 in the backlight unit according to the embodiment of the present invention. 7 is a plan view showing the arrangement relationship of the first and second lower light source portions 24 and 26. FIG 7 is a plan view showing the arrangement of the first light guide plate 201 and the first and second upper light source portions 23 and 24 in the backlight unit according to the embodiment of the present invention, 25 and the arrangement relationship of the second light guide plate 202 and the first and second lower light source portions 24 and 26, and FIG. 8 is an exploded perspective view showing the arrangement relationship of the pattern region of the light guide plate and the second light guide plate 24 according to the embodiment of the present invention. FIG. 9 is a schematic view showing a direction in which light emitted from the light source units 23, 24, 25, and 26 in the backlight unit according to the embodiment of the present invention travels in the light guide plate FIG.

6A to 7, the first light guide plate 201 includes a first upper light source unit 23 having a plurality of first upper light sources 23a, 23b, 23c, 23d, 23e, and 23f, 25b, 25c, 25d, 25e, and 25f of the first upper light source unit 25 and the second upper light source unit 25 having the second upper light sources 25a, 25b, 25c, 25d, 25e, The first upper light sources 23a through 23f and the second upper light sources 25a through 25f are disposed to be opposed to each other on both sides of the first light guide plate 201 in the embodiment of the present invention, Or may be formed only on one side of the light guide plate 201.

The first upper light sources 23a to 23f and the second upper light sources 25a to 25f are provided on the first light guide plate 201 with the first waveguide channels g1 to g6 are formed. A pattern region 201a in which fine engraved patterns (or positive patterns) are formed and an unpatterned region 201b in which no pattern is formed are formed on the bottom surfaces of the first waveguide channels g1 to g6. The pattern region 201a and the non-pattern region 201b are alternately arranged in each of the first waveguide channels g1 to g6 of the first light guide plate 201 and arranged alternately in relation to the adjacent waveguide channels do. Therefore, the blocks B11 to B46 shown in Fig. 8 are formed by the intersection of the pattern region 201a and the non-pattern region 201b.

The minute intaglio patterns (or the relief patterns) formed in the pattern area 201a of the first light guide plate 201 can be formed by the optical paths of the light in the first waveguides channels g1 to g6, (10). When these fine engraved patterns (or relief patterns) are densely formed far from the first upper light sources 23a to 23f and the second upper light sources 25a to 25f, the luminance at distant positions from these light sources If the degradation is compensated, the brightness can be adjusted to be uniform. The fine engraved patterns (or the relief patterns) may have a prism shape, a lens shape, a square shape, and the like, and the shape thereof is not particularly limited.

The second light guide plate 202 is disposed below the first light guide plate 201 and includes a first lower light source unit 24 having a plurality of first lower light sources 24a, 24b, 24c, 24d, 24e, 24f, 26b, 26c, 26d, 26e, 26f of the first lower light source unit 26. The second lower light source unit 26 includes a plurality of second lower light sources 26a, 26b, 26c, 26d, The first lower light sources 24a to 24f and the second lower light sources 26a to 26f are arranged to face each other on both sides of the second light guide plate 202 in the embodiment of the present invention, Or may be formed only on one side of the light guide plate 202.

The second light guide plate 202 is provided with first and second lower light sources 24a to 24f and second lower light sources 26a to 26f opposed to each other by the number of the first or second lower light sources, 'to g6') and are arranged to correspond to the first waveguides g1 to g6. A pattern region 202a in which fine engraved patterns (or mutual patterns) are formed and an unpatterned region 202b in which no pattern is formed are formed on the bottom surfaces of the second waveguides g1 'to g6'. The pattern area 202a and the non-pattern area 202b in the respective guiding channels of the second light guide plate 202 are arranged alternately and arranged alternately in relation to the adjacent guiding channels. The pattern area 202a of the second light guide plate 202 corresponds to the non-pattern area 201a of the first light guide plate 201 and the non-pattern area 202b of the second light guide plate 202 corresponds to the first light guide plate 201 corresponding to the pattern region 201b. Accordingly, in the second light guide plate 202, the blocks B11 to B46 as in the first light guide plate 201 are formed by the intersection of the pattern region 201a and the non-pattern region 201b.

As described above, the first waveguide channels g1 to g6 of the first light guide plate 201 and the second waveguide channels g1 'to g6' of the second light guide plate 202 are vertically arranged to overlap with each other , The pattern regions 201a and 202a and the non-pattern regions 202a and 202b are alternately arranged so as to form the same matrix type blocks B11 to B46 as shown in FIG.

As a result, the vertical alignment of the first light guide plate 201 and the second light guide plate 202 and the arrangement of the pattern areas 201a and 202a and the non-pattern areas 201b and 202b are alternately arranged, 201a, and 202a are not continuous.

9 is a view conceptually showing a direction in which light emitted from a light source unit proceeds in a light guide plate in a backlight unit according to an embodiment of the present invention. 9, when the light source 23a of the first upper light source part 23 is turned on, the light emitted from the light source 23a passes through the pattern area 201a formed on the bottom surface of the waveguide channel corresponding to the light source 23a, (Or positive patterns) are not formed in the non-pattern area 201b because the fine patterns are scattered by the fine three-dimensional patterns (or the positive patterns) and proceed to the liquid crystal display panel 10 side The light proceeds through the waveguide channel and the light is not output.

When the light source 24a of the first lower light source unit 24 is turned on, the light emitted from the light source 24a is incident on the minute patterned area 202b, which is the first area of the lower waveguide channel corresponding to the light source 24a, (Or embossed patterns) are not formed, light travels through the waveguide channel and reaches the pattern region 202a, which is the second region. However, since the fine depressed patterns (or the relief patterns) are formed in the pattern area 202a, the light is scattered and emitted toward the liquid crystal display panel 10. [

Light emitted from the light sources of the second upper light source unit 25 and the second lower light source unit 26 does not emit or emit light as described above according to the on / off states of the respective light sources, The on / off state of the formed blocks B11 to B46 can be controlled, and the effect of local dimming can be obtained.

10A and 10B illustrate driving states of a liquid crystal display device which can be represented according to an embodiment of the present invention. FIG. 10A is a diagram showing on / off states of a screen displayed by scanning backlight driving, FIG. Off state of a screen displayed by driving. Fig. The number of controllable blocks increases as shown in FIGS. 10A and 10B, so that the image degradation phenomenon with an increase in the number of blocks is reduced, and the local dimming performance is improved and the dynamic contrast ratio is improved. In addition, since the scanning implementation characteristic is improved and the MPRT characteristic is improved, the moving image implementation characteristic can be improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. For example, in the embodiment of the present invention, the light source unit is disposed on both sides of the first light guide plate and the second light guide plate. However, the light source unit may be provided so as to correspond to each light guide plate only on one side of the first light guide plate and the second light guide plate. In addition, in the embodiment of the present invention, the first upper light source unit corresponding to the first light guide plate and the second lower light source unit corresponding to the second light guide plate are arranged vertically, but the present invention can be applied to the first upper light source unit, And the first upper light source unit and the first lower light source unit may be disposed on different sides of the light guide plate. 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 diagrams showing a general scanning backlight driving technique.

3 is a view schematically showing a configuration of a liquid crystal display device according to a first embodiment of the present invention.

4 is a circuit diagram showing equivalently a part of the pixel array of the liquid crystal display panel shown in Fig.

5 is a view schematically showing a configuration of a liquid crystal display device according to a second embodiment of the present invention.

6A is a plan view showing the arrangement relationship of the first light guide plate and the first and second upper light sources in the backlight unit according to the embodiment of the present invention.

FIG. 6B is a plan view showing the arrangement relationship between the second light guide plate and the first and second lower light sources in the backlight unit according to the embodiment of the present invention; FIG.

7 is an exploded perspective view showing the arrangement relationship of the first light guide plate and the first and second upper light source portions and the arrangement relationship of the second light guide plate and the first and second lower light source portions in the backlight unit according to the embodiment of the present invention.

8 is a view showing a block formed by a pattern region and an unpatterned region of a light guide plate according to an embodiment of the present invention.

9 is a view conceptually showing a direction in which light emitted from a light source unit proceeds in a light guide plate in a backlight unit according to an embodiment of the present invention.

10A is a diagram showing the on-off state of a screen displayed by scanning backlight driving;

10B is a diagram showing the on-off state of the screen displayed by the local dimming drive.

Description of the Related Art

10: liquid crystal display panel 11: timing controller

12: data driving circuit 13: gate driving circuit

14: light source control circuit 16: image analysis circuit

21: first light source driving circuit 22: second light source driving circuit

23: first upper light source part 24: first lower light source part

25: second upper light source part 26: second lower light source part

201: first light guide plate 201a, 202a: pattern area

201b, 202b: patternless area 202: second light guide plate

g1 to g6: first waveguide channels g1 'to g6': second waveguide channel g2 '

Claims (12)

A first light pipe; A second light guide plate disposed below the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and including a plurality of first light sources for supplying light to the first light guide plate; And And a second light source unit disposed on at least one side of the second light guide plate and including a plurality of second light sources for supplying light to the second light guide plate, The first light guide plate includes a plurality of first wave guide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern area and a first patterned area are formed on the bottom surfaces of the first wave guide channels, And the first pattern region and the first patterned region are alternately arranged in relation to the adjacent first first waveguide channels, Wherein the second light guide plate includes a plurality of second waveguide channels formed by a traveling direction of light emitted from the second light sources, and a second pattern region and a second patterned region are formed on the bottom surfaces of the second waveguide channels, And the second pattern region and the second pattern-free region are alternately arranged in relation to the adjacent second second waveguide channels, Wherein the second pattern region is disposed so as to overlap the first patterned region of the first waveguide channel and the second patterned region overlaps the first pattern region of the first waveguide channel, A plurality of blocks in the form of a matrix are formed by the first pattern areas and the first pattern areas formed on the first light guide plate and the second pattern areas and the second pattern area formed on the second light guide plate Is formed. The method according to claim 1, Wherein the first waveguide channel and the second waveguide channel are vertically overlapped or intersected vertically. The method according to claim 1, Wherein the number of the first waveguide channels is equal to the number of the first light sources, and the number of the second waveguide channels is equal to the number of the second light sources. The method according to claim 1, Wherein at least one of a plurality of fine engraved patterns and fine relief patterns are formed in the first and second pattern regions. 5. The method of claim 4, Wherein the fine engraved patterns or fine bump patterns are densely formed from the first light sources or the second light sources. A liquid crystal display panel; A panel driving circuit for driving data lines and gate lines of the liquid crystal display panel; A timing controller for controlling the panel driving circuit; A backlight unit for supplying light to be irradiated to the liquid crystal display panel; A light source control circuit for generating a PWM signal for controlling lighting of light supplied from the backlight unit; And And a light source driving circuit for supplying or cutting off the light in response to the PWM signal, The backlight unit includes: A first light pipe; A second light guide plate disposed below the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and including a plurality of first light sources for supplying light to the first light guide plate; And And a second light source unit disposed on at least one side of the second light guide plate and including a plurality of second light sources for supplying light to the second light guide plate, The first light guide plate includes a plurality of first wave guide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern area and a first patterned area are formed on the bottom surfaces of the first wave guide channels, And the first pattern region and the first patterned region are alternately arranged in relation to the adjacent first first waveguide channels, Wherein the second light guide plate includes a plurality of second waveguide channels formed by a traveling direction of light emitted from the second light sources, and a second pattern region and a second patterned region are formed on the bottom surfaces of the second waveguide channels, And the second pattern region and the second pattern-free region are alternately arranged in relation to the adjacent second second waveguide channels, Wherein the second pattern region is disposed so as to overlap the first patterned region of the first waveguide channel and the second patterned region overlaps the first pattern region of the first waveguide channel, A plurality of blocks in the form of a matrix are formed by the first pattern areas and the first pattern areas formed on the first light guide plate and the second pattern areas and the second pattern area formed on the second light guide plate And the liquid crystal display device. A liquid crystal display panel; A panel driving circuit for driving data lines and gate lines of the liquid crystal display panel; A timing controller for controlling the panel driving circuit; A backlight unit for supplying light to be irradiated to the liquid crystal display panel; A light source control circuit for controlling light supplied from the backlight unit; And And an image analysis circuit for analyzing an input image and controlling the light source control circuit according to the analysis result, The backlight unit includes: A first light pipe; A second light guide plate disposed below the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and including a plurality of first light sources for supplying light to the first light guide plate; And And a second light source unit disposed on at least one side of the second light guide plate and including a plurality of second light sources for supplying light to the second light guide plate, The first light guide plate includes a plurality of first wave guide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern area and a first patterned area are formed on the bottom surfaces of the first wave guide channels, And the first pattern region and the first patterned region are alternately arranged in relation to the adjacent first first waveguide channels, Wherein the second light guide plate includes a plurality of second waveguide channels formed by a traveling direction of light emitted from the second light sources, and a second pattern region and a second patterned region are formed on the bottom surfaces of the second waveguide channels, And the second pattern region and the second pattern-free region are alternately arranged in relation to the adjacent second second waveguide channels, Wherein the second pattern region is disposed so as to overlap the first patterned region of the first waveguide channel and the second patterned region overlaps the first pattern region of the first waveguide channel, A plurality of blocks in the form of a matrix are formed by the first pattern areas and the first pattern areas formed on the first light guide plate and the second pattern areas and the second pattern area formed on the second light guide plate And the liquid crystal display device. A liquid crystal display panel; And And a backlight unit for supplying light to be irradiated to the liquid crystal display panel, The backlight unit includes: A first light pipe; A second light guide plate disposed below the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and including a plurality of first light sources for supplying light to the first light guide plate; And And a second light source unit disposed on at least one side of the second light guide plate and including a plurality of second light sources for supplying light to the second light guide plate, The first light guide plate includes a plurality of first wave guide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern area and a first patterned area are formed on the bottom surfaces of the first wave guide channels, And the first pattern region and the first patterned region are alternately arranged in relation to the adjacent first first waveguide channels, Wherein the second light guide plate includes a plurality of second waveguide channels formed by a traveling direction of light emitted from the second light sources, and a second pattern region and a second patterned region are formed on the bottom surfaces of the second waveguide channels, And the second pattern region and the second pattern-free region are alternately arranged in relation to the adjacent second second waveguide channels, Wherein the second pattern region is disposed so as to overlap the first patterned region of the first waveguide channel and the second patterned region overlaps the first pattern region of the first waveguide channel, A plurality of blocks in the form of a matrix are formed by the first pattern areas and the first pattern areas formed on the first light guide plate and the second pattern areas and the second pattern area formed on the second light guide plate And the liquid crystal display device. 9. The method according to any one of claims 6 to 8, Wherein the first waveguide channel and the second waveguide channel are vertically overlapped or intersected vertically. 9. The method according to any one of claims 6 to 8, Wherein the number of the first waveguide channels is equal to the number of the first light sources and the number of the second waveguide channels is equal to the number of the second light sources. 9. The method according to any one of claims 6 to 8, Wherein at least one of a plurality of fine engraved patterns and fine relief patterns are formed in the first and second pattern regions. 12. The method of claim 11, Wherein the fine engraved patterns or the fine bump patterns are densely formed as being distant from the first light sources or the second light sources.

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