KR20110074363A - Backlight 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 reduce the image degradation by the increase of a number of blocks by forming matrix-type blocks by arranging pattern areas of each wave guide channel and non-pattern areas. CONSTITUTION: A second light guide plate is arranged in the lower part of a first light guide plate(201). A first light source unit(23) comprises a plurality of first light sources. The first light sources arranged in one or more side of the first light guide plate supplies light to the first light guide plate. A second light source unit(25) comprises a plurality of second light sources. The second light source unit placed on the side of the second light guide plate supplies light to the second light guide plate.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY USING THE SAME}

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 (MPRT) performance and local dimming performance. It relates to a liquid crystal display device used.

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, and a thin film transistor (TFT) as a switching element. ), An active matrix driving method for displaying a video using the

When displaying a moving image through the liquid crystal display, the MPRT performance may be degraded due to the retention characteristics of the liquid crystal, resulting in motion blur that may appear blurred or blurred. In order to improve MPRT performance, a scanning backlight driving technique has been proposed. The scanning backlight driving technique sequentially flashes the light sources of the backlight unit along the scanning direction of the display line as shown in FIGS. 1 and 2 to provide an effect similar to the impulsive driving of the CRT, thereby blurring motion of the liquid crystal display. To improve.

However, since the scanning backlight driving technology must control light emitted to the liquid crystal display panel in units of scanning blocks, the position of the light sources in the backlight unit is limited. According to the arrangement position of the light source, the backlight unit is roughly classified into a direct type and an edge type. Since the direct type backlight unit has a structure in which a plurality of optical sheets and a diffusion plate are stacked below the liquid crystal display panel and a plurality of light sources are disposed below the diffusion panel, it is easy to implement a scanning backlight. On the other hand, the edge type backlight unit has a structure in which a light source is disposed to face the side 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 has a structure in which a light source irradiates light on one side of the light guide plate, and the light guide plate converts the light into planar light. It is difficult to control, which makes the implementation of the scanning backlight difficult. 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. Only the method of modulating the light transmittance of the liquid crystal layer by controlling the data voltage applied to the liquid crystal layer has a limitation in improving this contrast characteristic. In order to improve contrast characteristics, various backlight dimming control methods for adjusting the brightness of the backlight unit according to an image have been tried.

The backlight dimming control method may reduce 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 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 ratio measured between the previous frame and the next frame. The local dimming method can improve static contrast, which is difficult to improve with the global dimming method by locally controlling the luminance of the display surface within one frame period. However, the conventional local dimming method not only causes a difference in luminance and flicker between a plurality of blocks partitioned in the display surface, but also requires a large number of circuit elements in the local dimming circuit. In addition, the local dimming method has a problem that is implemented only in the liquid crystal display device using a direct type backlight unit. However, the direct type backlight unit has a problem that it is difficult to reduce the thickness of the backlight unit because it must be provided with a diffusion plate disposed at regular intervals from the light source in order to diffuse the light incident from the lamp to uniform the brightness of the display surface. Recently, due to the thinning trend of liquid crystal display devices, the distance between the diffuser plate and the light sources is narrowing, but since the light from the light source is not sufficiently diffused, the luminance uniformity of the display image due to the bright line visible in the display image, etc. There is a problem falling. Therefore, there is a need for a technique for implementing local dimming in an edge type backlight unit.

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 MPRT performance without optical interference due to a difference in timing of light sources.

Another object of the present invention is to provide a backlight unit and a liquid crystal display using the same, which can improve a moving image realization characteristic by improving the performance of local dimming to increase dynamic contrast ratio.

In order to achieve the above object, the backlight unit according to an embodiment of the present invention comprises a first light guide plate; A second light guide plate disposed under the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and having a plurality of first light sources to supply 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 is configured to propagate light emitted from the first light sources. A plurality of first waveguide channels formed by a direction, and a first pattern region and a first non-pattern region are alternately disposed on a bottom surface of each of the first waveguide channels, and have a relationship with adjacent first waveguide channels. Also, the first pattern region and the first non-pattern region are disposed alternately, and 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. A second non-pattern region is formed on each bottom surface of the second waveguide channels so as to overlap the first pattern region of the first waveguide channel, and the first waveguide channel has a first pattern region. A second pattern region is formed to overlap the unpatterned region, and the second pattern region is alternately disposed with the second patternless region, and the first pattern regions and the first patternless region formed on the first light guide plate. And a plurality of blocks formed by the second pattern regions and the second non-pattern regions formed in the second light guide plate.

In the above configuration, the first waveguide channel and the second waveguide channel are configured to overlap vertically or cross vertically.

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

In addition, at least one of a plurality of micro-engraved patterns and micro-embossed patterns is formed in the first and second pattern regions, and the micro-engraved patterns or the micro-embossed patterns may be the first light sources or the second light sources. The farther they are from, the denser the formed.

Liquid crystal display device according to an embodiment of the present invention comprises 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 the lighting of the light supplied from the backlight unit; And a light source driving circuit configured to supply or block the light in response to the PWM signal, wherein the backlight unit has the characteristics as described above.

According to another embodiment of the present invention, a liquid crystal display device 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 characteristics as described above.

According to another embodiment of the present invention, a liquid crystal display device 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 characteristics as described above.

In the backlight unit and the liquid crystal display according to the exemplary embodiment of the present invention, the first waveguide channels of the first light guide plate and the second waveguide channels of the second light guide plate are disposed up and down so as to overlap each other, and the pattern region of each waveguide channel Since the non-patterned regions are alternately arranged to form blocks in the form of matrix, image degradation due to the increase in the number of blocks is reduced, and local dimming performance is improved, thereby improving the dynamic contrast ratio. In addition, according to the above-described configuration, since the scanning implementation characteristic is improved and the MPRT characteristic is improved, the effect of improving the moving image implementation characteristic is obtained.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 3 to 10B. Like reference numerals denote 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. 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 a partial 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 data driving circuit 12 for driving the liquid crystal display panel 10 and the data lines DL of the liquid crystal display panel 10. A gate controller 13 driving the gate lines GL of the liquid crystal display panel 10, a timing controller 11 controlling the data driver circuit 12 and the gate driver circuit 13, and a liquid crystal display panel. A backlight unit for irradiating light to the light source 10, 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 upper light source unit of the backlight unit ( 25 and the second light source driving circuit 22 for driving the second lower light source unit 26 and the light source control circuit for controlling the first and second light source driving circuits 21 and 22 according to the light source flashing timing. (14) is provided. 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. As illustrated in FIG. 4, a plurality of data lines 12a through 12d and a plurality of gate lines 13a through 13d are crossed on the lower glass substrate of the liquid crystal display panel 10. The liquid crystal cells Clc are arranged in a matrix form on the liquid crystal display panel 10 due to the cross structure of the data lines DL and the gate lines GL. In addition, a thin film transistor TFT, a pixel electrode 1 of a liquid crystal cell Clc connected to the thin film transistor TFT, a storage capacitor Cst, and the like are formed on a lower glass substrate of the liquid crystal display panel 10. The liquid crystal cells Clc are connected to the TFT and are driven by an electric field between the pixel electrodes 1 and the common electrode 2. The data lines DL are formed side by side in a relatively short vertical axis direction (hereinafter, referred to as the “y axis direction”), and the gate lines GL may be formed as a relatively long horizontal axis direction (hereinafter referred to as the “x axis direction”, x> y). Are formed side by side. The liquid crystal display panel 10 scans data in the x-axis direction by the operation of the panel driving circuit.

A black matrix, a color filter, and the like are formed on the upper glass substrate of the liquid crystal display panel 10. The common electrode 2 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 has an in plane switching (IPS) mode and a fringe field switching (FFS) mode. In the same horizontal electric field driving method, the pixel electrode 1 is formed on the lower glass substrate. A polarizing plate is attached to each of the upper glass substrate and the lower glass substrate of the liquid crystal display panel 10, and an alignment layer for setting the pre-tilt angle of the liquid crystal is formed.

The data driver circuit 12 includes a plurality of data drive integrated circuits. The data drive integrated circuit stores a shift line for sampling a clock signal, a register for temporarily storing digital video data (RGB), a line of data in response to a clock signal from the shift register, and stores the stored data for one line. A latch for outputting at the same time, 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 the latch, and an analog converted by a positive / negative gamma voltage And 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 uses the positive / negative gamma compensation voltage to latch the latched digital video data RGB. The polarity is converted into an analog data voltage and then supplied to the data lines DL.

The gate driving 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 driving a TFT of a liquid crystal cell, an output buffer, and the like. The gate driving circuit 13 sequentially outputs scan pulses (or gate pulses) and supplies them to the gate lines GL under the control of the timing controller 11, thereby providing a vertical line in the y-axis direction to which data is applied. Select one line along the axial direction.

The timing controller 11 rearranges the digital video data RGB input from an external system board to match 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 includes timing control signals for controlling the operation timing of the data driving circuit 12 and the gate driving circuit 13 based on the timing signals Vsync, Hsync, DE, and DCLK from the system board. DDC, GDC). The timing controller 11 performs data timing 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 × N (N is a positive integer of 2 or more) Hz. The control signal DDC and the gate timing control signal GDC are multiplied to operate the data driving circuit 12 and the gate driving circuit 13 at a frame frequency of 60 × N (N is a positive integer of 2 or more) Hz. Can be controlled. The 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 for irradiating light from both side surfaces of the first light guide plate 201, and The first lower light source unit 24 and the second lower light source unit 26, the first light guide plate 201, and the liquid crystal display panel 10 that irradiate light from both sides of the second upper light source unit 25 and the second light guide plate 202, respectively. It is implemented in an edge type including a plurality of optical sheets stacked between).

The light source units 23, 24, 25, and 26 may be implemented as a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL), and more preferably, a light emitting diode (LED). Light Emitting Diode (LED). In the exemplary embodiment of the present invention, the light source units 23, 24, 25, and 26 are disposed on both side surfaces of the first and second light guide plates 201 and 202, but may be disposed only on one side. The light sources 23, 24, 25, and 26 are sequentially driven in the backlight scanning block unit 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 at least one prism sheet and at least one diffusion sheet to diffuse light incident from the first and second light guide plates 201 and 202 and to be substantially perpendicular to the light incident surface of the liquid crystal display panel 10. Refract the path of light at an angle of The optical sheets may comprise a dual brightness enhancement film (DBEF).

The light source control circuit 14 may be configured to sequentially drive the light source units 23, 24, 25, and 26 in the backlight scanning block unit along the data scanning direction (x-axis direction) of the liquid crystal display panel 10. , 25, 26) is 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 built in the timing controller 11.

The light source driving circuits 21 and 22 sequentially drive the light source units 23, 24, 25, and 26 to be synchronized with data scanning of the liquid crystal display panel 10 under the control of the light source control circuit 14. The lighting time ON / OFF of the light source parts 23, 24, 25, 26 is determined according to the PWM signal from the light source control circuit 14. The lighting time ON of the light source units 23, 24, 25, and 26 is longer as the duty ratio of the PWM signal is higher, and shorter as the duty ratio of the PWM signal is 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 exemplary embodiment of the present invention will be described with reference to FIG. 5. 5 is a schematic view of a liquid crystal display according to a second exemplary embodiment of the present invention. In the description of the second embodiment, the same components as in the first embodiment will be denoted by the same reference numerals as in the first embodiment, and the descriptions of the same components as the first embodiment will be omitted for simplicity. .

Referring to FIG. 5, the liquid crystal display according to the second exemplary embodiment of the present invention may include a liquid crystal display panel 10, a data driving circuit 12 for driving data lines DL of the liquid crystal display panel 10, The gate driving circuit 13 for driving the gate lines GL of the liquid crystal display panel 10, the timing controller 11 controlling the data driving circuit 12 and the gate driving circuit 13, and the liquid crystal display panel ( 10, the first light source driving circuit 21 for driving the backlight unit irradiating light to the first light source unit 23 and the first lower light source unit 24 of the backlight unit, and the second upper light source unit 25 of the backlight unit. ) And a second light source driving circuit 22 for driving the second lower light source unit 26, and an image for analyzing the input image and controlling the first and second light source driving circuits 21 and 22 according to the analysis result. An analysis circuit 16 is provided.

Since the configuration of 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, 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 configured to cover any block corresponding to the bright portion of the display image displayed on the liquid crystal display panel 10 according to the local dimming signal LDIM from the image analysis circuit 16. While the current supplied to the light sources of the first upper light source unit 23 and the first lower light source unit 24 is adjusted to be high, it is responsible for other blocks corresponding to the dark portions of the display image displayed on the liquid crystal display panel 10. The current supplied to the other light sources of the first upper light source unit 23 and the first lower light source unit 24 is adjusted to be 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 configured to cover any blocks corresponding to bright portions of the display image displayed on the liquid crystal display panel 10 according to the local dimming signal LDIM from the image analysis circuit 16. While 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 high, the second block is responsible for other blocks corresponding to the dark portions of the display image displayed on the liquid crystal display panel 10. The current supplied to the other light sources of the second 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 with 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 in units of block size. The image analysis circuit 16 generates a local dimming signal LDIM for adjusting the supply current of the light source units 23, 24, 25, and 26 in proportion to the luminance analyzed by the block size, so that the first and second light sources are generated. The driving circuits 21 and 22 are controlled. The image analysis circuit 16 synchronizes the timing control unit 11 with the input timing signals Vsync, Hsync, DE, and DCLK, thereby converting the driving timing of the light source units 23, 24, 25, and 26 into digital video data. Synchronize with the display timing of (RGB). The image analysis circuit 16 may be mounted on an external system board or embedded in the timing controller 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 for irradiating light from both side surfaces of the first light guide plate 201, and The first lower light source unit 24 and the second lower light source unit 26, the first light guide plate 202, and the liquid crystal display panel 10 that emit light from both sides of the second upper light source unit 25 and the second light guide plate 202, respectively. It is implemented in an edge type including a plurality of optical sheets stacked between).

The light source units 23, 24, 25, and 26 may be implemented as CCFLs or EEFLs, and may be implemented as LEDs. In addition, in the embodiment of the present invention, the light source units 23, 24, 25, and 26 are described as being disposed on both side surfaces of the first and second light guide plates 201 and 202, but may be disposed only on one side.

6A through 9, a backlight unit including light source units 22, 23, 24, and 25 and first and second light guide plates 201 and 202 will be described in more detail. 6A is a plan view illustrating an arrangement relationship between the first LGP 201 and the first and second upper light source units 23 and 25 in the backlight unit according to an exemplary embodiment of the present invention. FIG. 7 is a plan view illustrating an arrangement relationship between the first and second lower light source units 24 and 26. FIG. 7 illustrates the first light guide plate 201 and the first and second upper light source units 23 and 23 in the backlight unit according to the embodiment of the present invention. 25 is an exploded perspective view showing an arrangement relationship between the second light guide plate 202 and the first and second lower light source parts 24 and 26. FIG. 8 is a view illustrating an arrangement relationship of the light guide plate according to the embodiment of the present invention. 9 illustrates a block formed by a pattern region, and FIG. 9 conceptually illustrates a direction in which light emitted from the light source units 23, 24, 25, and 26 travels in a light guide plate in a backlight unit according to an exemplary embodiment of the present invention. Drawing.

6A to 7, the first LGP 201 includes a first upper light source unit 23 having a plurality of first upper light sources 23a, 23b, 23c, 23d, 23e, and 23f and a plurality of first light sources. 2 is arranged between the second upper light source section 25 with the upper light sources 25a, 25b, 25c, 25d, 25e, 25f. In the exemplary embodiment of the present invention, the first upper light sources 23a to 23f and the second upper light sources 25a to 25f are disposed to face each other on both sides of the first LGP 201, but the light source unit may be disposed in the first light source plate 201. It may be formed only on one side of the light guide plate 201.

The first light guide plate 201 has the first waveguide channels g1 corresponding to the number of the first or second upper light sources by the first upper light sources 23a to 23f and the second upper light sources 25a to 25f that face each other. g6) is formed. On the bottom of each of the first waveguide channels g1 to g6, a pattern region 201a in which fine intaglio patterns (or positive patterns) are formed and a patternless region 201b in which no pattern is formed are formed. In each of the first waveguide channels g1 ˜ g6 of the first light guide plate 201, the pattern region 201a and the unpatterned region 201b are alternately arranged, and are alternately positioned in relation to adjacent waveguide channels. do. Accordingly, blocks B11 to B46 as shown in FIG. 8 are formed by the intersection of the pattern region 201a and the patternless region 201b.

The fine engraved patterns (or embossed patterns) formed in the pattern region 201a of the first light guide plate 201 are used to form the optical paths and the liquid crystal display panel through the light paths in the first waveguide channels g1 to g6. Reflect toward (10). When these fine intaglio patterns (or embossed patterns) are denserly formed away from the first upper light sources 23a to 23f and the second upper light sources 25a to 25f, the luminance at a position far from these light sources is increased. If the degradation is compensated for, the luminance can be adjusted to be uniform. The fine engraved patterns (or the embossed 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 LGP 202 is disposed below the first LGP 201 and includes a first lower light source 24 having a plurality of first lower light sources 24a, 24b, 24c, 24d, 24e, and 24f. The second lower light source unit 26 includes a plurality of second lower light sources 26a, 26b, 26c, 26d, 26e, and 26f. In the exemplary embodiment of the present invention, the first lower light sources 24a to 24f and the second lower light sources 26a to 26f are disposed to face each other on both sides of the second light guide plate 202. It may be formed only on one side of the light guide plate 202.

The second light guide plate 202 has the second waveguide channels g1 by the number of the first or second lower light sources by the first lower light sources 24a to 24f and the second lower light sources 26a to 26f that face each other. '~ g6' is formed and disposed to correspond to the first waveguide channels g1 to g6. The bottom of each of the second waveguide channels g1 ′ to g6 ′ is formed with a pattern region 202a on which fine negative patterns (or positive patterns) and a patternless region 202b on which no pattern is formed. In each of the waveguide channels of the second light guide plate 202, the pattern region 202a and the non-pattern region 202b are alternately arranged, and are alternately positioned in relation to adjacent waveguide channels. In addition, the pattern region 202a of the second LGP 202 corresponds to the patternless region 201a of the first LGP 201, and the patternless region 202b of the second LGP 202 is the first LGP. It is disposed so as to correspond to the pattern region 201b of 201. Accordingly, the same blocks B11 to B46 as in the first LGP 201 are formed in the second LGP 202 by the intersection of the pattern region 201a and the patternless region 201b.

As described above, the first waveguide channels g1 ˜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 disposed to overlap each other. The pattern regions 201a and 202a and the patternless regions 202a and 202b are alternately arranged to form blocks B11 to B46 having a matrix shape as illustrated in FIG. 8.

As a result, the vertical region of the first LGP 201 and the second LGP 202 and the arrangement of the pattern regions 201a and 202a and the patternless regions 201b and 202b are alternately arranged so that the pattern region ( 201a and 202a are not continuous.

FIG. 9 is a view conceptually illustrating a direction in which light emitted from a light source unit travels in a light guide plate in the backlight unit according to an exemplary embodiment of the present invention. Referring to FIG. 9, when the light source 23a of the first upper light source unit 23 is turned on, the light emitted from the light source 23a is patterned on the bottom surface of the waveguide channel corresponding to the light source 23a. In FIG. 5, the light is scattered by the fine intaglio patterns (or the embossed patterns) and proceeds toward the liquid crystal display panel 10. Light propagates through the waveguide channel so that 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 a fine intaglio pattern in the unpatterned region 202b, which is the first region of the lower waveguide channel corresponding to the light source 24a. Since no (or embossed patterns) are formed, light travels through the waveguide channel to reach the second region, the pattern region 202a. However, since fine intaglio patterns (or embossed patterns) are formed in the pattern region 202a, light is scattered by the light emitting patterns, and the light is emitted toward the liquid crystal display panel 10.

Since the light emitted from the light sources of the second upper light source unit 25 and the second lower light source unit 26 is not emitted or emitted as described above according to the on / off state of each light source, as shown in FIG. 8. It is possible to control the on / off state of the formed blocks (B11 ~ B46) to obtain the effect of local dimming.

10A and 10B illustrate a driving state of a liquid crystal display device which may be represented according to an exemplary embodiment of the present invention. FIG. 10A illustrates an on / off state of a screen displayed by driving a scanning backlight. FIG. 10B illustrates local dimming. It is a figure which shows the on-off state of the screen displayed by driving. As the number of blocks that can be controlled through FIGS. 10A and 10B increases, image degradation due to an increase in the number of blocks decreases, local dimming performance is improved, and 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.

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. For example, in the embodiment of the present invention, the light source parts are disposed on both sides of the first light guide plate and the second light guide plate, but the light source parts may be provided only on one side of the first light guide plate and the second light guide plate. In addition, in the exemplary embodiment of the present invention, the first upper light source part corresponding to the first light guide plate and the second lower light source part corresponding to the second light guide plate are described as being disposed up and down, but the present invention provides the first upper light source part and the first lower light source part. The upper and lower light sources may not be limited to overlap each other, and the first upper light source unit and the first lower light source unit may be disposed on different side surfaces 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 illustrate a typical scanning backlight driving technique.

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

4 is an equivalent circuit diagram of a part of a pixel array of the liquid crystal display panel illustrated in FIG. 3.

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

6A is a plan view illustrating an arrangement relationship between a first light guide plate and a first and second upper light source units in a backlight unit according to an exemplary embodiment of the present invention.

6B is a plan view illustrating an arrangement relationship between a second light guide plate and first and second lower light source units in a backlight unit according to an exemplary embodiment of the present invention.

FIG. 7 is an exploded perspective view illustrating an arrangement relationship between a first light guide plate and first and second upper light source units and an arrangement relationship between a second light guide plate and a first and second lower light source units in a backlight unit according to an exemplary embodiment of the present invention;

8 illustrates a block formed by a pattern region and a patternless region of a light guide plate according to an exemplary embodiment of the present invention.

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

10A is a diagram illustrating an on-off state of a screen displayed by driving a scanning backlight.

10B is a diagram illustrating an on-off state of a screen displayed by local dimming driving.

<Description of Symbols for Main Parts of Drawings>

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 unit 24: first lower light source unit

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

201: First LGP 201a, 202a: Pattern Area

201b and 202b: Patternless region 202: Second light guide plate

g1 to g6: First waveguide channel g1 'to g6': Second waveguide channel

Claims (12)

A first light guide plate; A second light guide plate disposed under the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and having a plurality of first light sources to supply 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 to supply light to the second light guide plate; The first LGP includes a plurality of first waveguide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern region and a first non-pattern region are formed on a bottom surface of each of the first waveguide channels. Are alternately arranged so that the first pattern region and the first non-pattern region are alternately positioned even with respect to the adjacent first waveguide channels, 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 first pattern region of the first waveguide channel is formed on a bottom surface of each of the second waveguide channels. A second pattern-free region is formed to overlap with the second pattern-free region, and a second pattern region is formed to overlap with the first pattern-free region of the first waveguide channel, and the second pattern region is alternately disposed with the second pattern-free region, A plurality of blocks are formed by the first pattern regions and the first non-pattern regions formed on the first light guide plate, and the second pattern regions and the second non-pattern regions formed on the second light guide plate. The backlight unit characterized by the above-mentioned. The method of claim 1, And the first waveguide channel and the second waveguide channel overlap vertically or cross vertically. The method of 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 of claim 1, And at least one of a plurality of fine engraved patterns and fine embossed patterns are formed in the first and second pattern regions. The method of claim 4, wherein The fine engraved patterns or fine embossed patterns are denserly formed away from the first light sources or the second light sources. A liquid crystal display panel; A panel driver 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 the lighting of the light supplied from the backlight unit; And A light source driving circuit configured to supply or block the light in response to the PWM signal, The backlight unit, A first light guide plate; A second light guide plate disposed under the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and having a plurality of first light sources to supply 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 converging light to the second light guide plate; The first LGP includes a plurality of first waveguide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern region and a first non-pattern region are formed on a bottom surface of each of the first waveguide channels. Are alternately arranged so that the first pattern region and the first non-pattern region are alternately positioned even with respect to the adjacent first waveguide channels, 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 first pattern region of the first waveguide channel is formed on a bottom surface of each of the second waveguide channels. A second pattern-free region is formed to overlap with the second pattern-free region, and a second pattern region is formed to overlap with the first pattern-free region of the first waveguide channel, and the second pattern region is alternately disposed with the second pattern-free region, A plurality of blocks are formed by the first pattern regions and the first non-pattern regions formed on the first light guide plate, and the second pattern regions and the second non-pattern regions formed on the second light guide plate. A 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 An image analysis circuit for analyzing the input image and controlling the light source control circuit according to the analysis result; The backlight unit, A first light guide plate; A second light guide plate disposed under the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and having a plurality of first light sources to supply 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 converging light to the second light guide plate; The first LGP includes a plurality of first waveguide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern region and a first non-pattern region are formed on a bottom surface of each of the first waveguide channels. Are alternately arranged so that the first pattern region and the first non-pattern region are alternately positioned even with respect to the adjacent first waveguide channels, 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 first pattern region of the first waveguide channel is formed on a bottom surface of each of the second waveguide channels. A second pattern-free region is formed to overlap with the second pattern-free region, and a second pattern region is formed to overlap with the first pattern-free region of the first waveguide channel, and the second pattern region is alternately disposed with the second pattern-free region, A plurality of blocks are formed by the first pattern regions and the first non-pattern regions formed on the first light guide plate, and the second pattern regions and the second non-pattern regions formed on the second light guide plate. A liquid crystal display device. A liquid crystal display panel; And It includes a backlight unit for supplying light to be irradiated to the liquid crystal display panel, The backlight unit, A first light guide plate; A second light guide plate disposed under the first light guide plate; A first light source unit disposed on at least one side of the first light guide plate and having a plurality of first light sources to supply 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 converging light to the second light guide plate; The first LGP includes a plurality of first waveguide channels formed by a traveling direction of light emitted from the first light sources, and a first pattern region and a first non-pattern region are formed on a bottom surface of each of the first waveguide channels. Are alternately arranged so that the first pattern region and the first non-pattern region are alternately positioned even with respect to the adjacent first waveguide channels, 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 first pattern region of the first waveguide channel is formed on a bottom surface of each of the second waveguide channels. A second pattern-free region is formed to overlap with the second pattern-free region, and a second pattern region is formed to overlap with the first pattern-free region of the first waveguide channel, and the second pattern region is alternately disposed with the second pattern-free region, A plurality of blocks are formed by the first pattern regions and the first non-pattern regions formed on the first light guide plate, and the second pattern regions and the second non-pattern regions formed on the second light guide plate. A liquid crystal display device. The method according to any one of claims 6 to 8, And the first waveguide channel and the second waveguide channel overlap vertically or cross vertically. 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. The method according to any one of claims 6 to 8, And at least one of a plurality of fine engraved patterns and fine embossed patterns are formed in the first and second pattern regions. The method according to any one of claims 6 and 7, The fine engraved patterns or the fine embossed patterns are densely formed away from the first light sources or the second light sources.

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