JP2009199926A - Liquid crystal display device, and light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device having high contrast. <P>SOLUTION: The liquid crystal display device includes a liquid crystal panel 6, a backlight 4 disposed on the back of the liquid crystal panel 6 while having a light source 3 on at least one side of a light guide plate 2, a light source driver 5 to drive the light source 3 of the backlight 4, and a processing circuit 8 which processes a video signal and outputs light source control information to the light source driver 5. The light guide plate 2 is divided into a plurality of blocks 2a-2j having light sources 3. The light source driver 5 lights or puts out the light source 3 which each block 2a-2j has, based on the light source control information. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a light guide plate, and more particularly to a liquid crystal display device having an edge light type backlight and a light guide plate used in the liquid crystal display device.

Conventionally, the liquid crystal display device has a problem of low contrast. Therefore, as disclosed in Patent Document 1, recently, in order to increase the contrast, only the backlight immediately below the area brightly displayed on the liquid crystal panel is turned on, and the backlights of other parts are not turned on. A technique of local dimming (partial luminance control) that performs area control has been developed.
JP 2007-183608 A

  In local dimming, a plurality of light-emitting diodes arranged on the side surface of the light guide plate are partially lit, so that the light guide plate is partially lit. There is a problem to do. Therefore, a factor that can further increase the contrast remains.

  The present invention provides a high-contrast liquid crystal display device and a light guide plate used in the liquid crystal display device.

  A liquid crystal display device according to the present invention includes a liquid crystal panel, a backlight disposed on the back surface of the liquid crystal panel and having a light source on at least one side of a light guide plate, a light source driver for driving the light source of the backlight, and an image A processing circuit for processing a signal and outputting light source control information to the light source driver, wherein the light guide plate is divided into a plurality of blocks having a light source, and based on the light source control information, the light source driver Is configured to switch on and off the light source of each block. Thereby, the contrast of the liquid crystal display device can be increased.

  The liquid crystal display device according to the present invention includes a liquid crystal panel, a backlight disposed on the back surface of the liquid crystal panel and having a light source on at least one side surface of the light guide plate, and a light source driver that drives the light source of the backlight. A processing circuit for processing a video signal and outputting light source control information to the light source driver, wherein the light guide plate is partitioned into a plurality of blocks having a light source, so that light does not leak into adjacent blocks. A groove is formed in the light source, and the light source driver is configured to switch on and off the light source of each block based on the light source control information. Thereby, the contrast of the liquid crystal display device can be increased.

  Dots are formed on the bottom surface of the light guide plate by printing, and a reflective film is formed on the side surface of each block of the light guide plate.

  Alternatively, the bottom surface of the light guide plate described above is formed with ridges by a molding method or the like.

  It is preferable that a light source is disposed on each of two opposite sides of the light guide plate, and the light guide plate is divided into 2 × n pieces so that each block has a light source.

  Or it is preferable that the above-mentioned light-guide plate is divided | segmented into strip shape so that it may have a light source in the side which each block opposes.

  A light source is arranged on each of two opposing side surfaces of the light guide plate, and the light guide plate is divided into 2 × n pieces so that each block has a light source, so that light does not leak to adjacent blocks. It is preferable that a groove is formed on the bottom surface.

  Alternatively, it is preferable that the above-described light guide plate is formed in a strip shape so as to have a light source on a side surface facing each block, and a groove portion is formed on the bottom surface so that light does not leak into an adjacent block.

  Here, it is preferable that the light source is composed of a light emitting diode or the like having high parallelism. Light hardly leaks to adjacent blocks, and the contrast of the liquid crystal display device can be further increased.

  The light guide plate according to the present invention is used in a liquid crystal display device configured to perform area control so that only the backlight immediately below the area brightly displayed on the liquid crystal panel is turned on and the other parts of the backlight are not turned on. The light guide plate is divided into a plurality of blocks so that each block has a light source of a backlight. As a result, light does not leak into adjacent blocks, and the contrast of the liquid crystal display device can be increased.

  In addition, the light guide plate according to the present invention is a liquid crystal display device configured to perform area control so that only the backlight immediately below the area that is brightly displayed on the liquid crystal panel is turned on and the backlight of other parts is not turned on. The light guide plate used is divided into a plurality of blocks so that each block has a light source of a backlight, and a groove is formed on the bottom surface so that light does not leak into adjacent blocks. As a result, light does not leak into adjacent blocks, and the contrast of the liquid crystal display device can be increased.

  According to the present invention, it is possible to provide a liquid crystal display device with high contrast and a light guide plate used in the liquid crystal display device.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

<Embodiment 1>
A liquid crystal display device and a light guide plate according to a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the liquid crystal display device 1 includes a backlight 4 in which a light source 3 is disposed on at least one side of a light guide plate 2, a light source driver 5 that drives the light source 3 of the backlight 4, and a liquid crystal panel. 6, a liquid crystal driver 7 that drives the liquid crystal panel 6, and a processing circuit 8 that processes video signals and outputs information to the light source driver 5 and the liquid crystal driver 7.

  The light guide plate 2 is a flat rectangular (panel-like) transparent structure, and can be made of a transparent resin having a high light transmittance. As such a transparent resin, for example, a methacrylic resin, an acrylic resin, a polycarbonate resin, a polyester resin, a cyclic polyolefin resin, and the like can be widely used. On the upper surface of the light guide plate 2, an emission surface for emitting light is formed, and a bottom surface is formed opposite to the emission surface. Of the side surfaces of the light guide plate 2, the side surface on which the light source 3 is disposed is the incident end surface. Further, both side faces intersecting with the incident end face are reflection end faces.

  On the bottom surface of the light guide plate 2, ridges are in contact with each other by a molding method or laser processing and are arranged in parallel to the incident end surface. By gradually adjusting the size of the ridges, it is possible to adjust the light amount distribution of the light emitted from the emission surface. The ridges include trapezoidal ridges and may be substantially the same or equivalent to the ridges formed on the conventional light guide plate. The cross-sectional shape of these ridges may be a desired shape such as a triangle, a wedge, another polygon, a wave, or a semi-ellipse.

  Here, the ridges may be arranged with the pitch narrowed away from the light source 3, or the height of the ridges may gradually increase as the distance from the light source 3 increases. Moreover, you may comprise so that a shape may change gradually as it leaves | separates from the light source 3. FIG. The “configuration with gradually different shapes” includes, for example, when the length of the upper base and / or the lower base of the trapezoid is gradually different when the cross section includes a trapezoidal protrusion.

  A plurality of light sources 3 are arranged on the opposite incident end faces of the light guide plate 2. In the present embodiment, as shown in FIG. 1, a light emitting diode (LED) having high parallelism is used as the light source 3, and a plurality of light sources 3 are arranged at equal intervals on the incident end surface. It is arranged so as to face the light source 3.

  As shown in FIG. 2, the light guide plate 2 is divided into 2 × n (n is a natural number of 1 or more, and in this embodiment, n = 5 is 10) so that each block 2a to 2j has a light source 3. The blocks 2a to 2j are arranged so as to be in contact with each other. For this reason, in the light guide plate 2, the light emitted from the light source 3 enters the light guide plate 2 from the incident end surface of the light guide plate 2, diffuses and exits from the output surface in the same manner as a conventional light guide plate. The light incident on 2a to 2j is totally reflected on the side surface where the blocks are abutted against each other and does not leak out to other blocks.

  Incidentally, a reflection sheet (not shown) may be disposed below the bottom surface of the light guide plate 2. The reflection sheet is a sheet-like reflector provided to improve the luminance by reflecting light emitted from the bottom surface side of the light guide plate 2 to the emission surface side of the light guide plate 2.

  Further, a diffusion sheet (not shown) and a light control sheet (not shown) may be disposed above the light exit surface of the light guide plate 2. By disposing a diffusion sheet between the light guide plate 2 and the light control sheet, the emitted light from the backlight 4 can be made uniform and the quality can be improved. Moreover, the front luminance can be further increased by selecting an appropriate diffusion sheet.

  The backlight 4 having such a configuration is disposed on the back surface of the liquid crystal panel 6 and is configured to be capable of local dimming (partial luminance control) with respect to the backlight 4. That is, the processing circuit 8 analyzes the area brightly displayed on the liquid crystal panel 6 from the luminance information of the video signal, and provides information (light source control information) for controlling the light source 3 so that only the block corresponding to the area is turned on. Input to the light source driver 5. For example, the section information of each block 2 a to 2 j of the light guide plate 2 is stored in the processing circuit 8. The liquid crystal panel 6 is virtually partitioned in advance into regions corresponding to the blocks 2 a to 2 j of the light guide plate 2, and the partition information is stored in the processing circuit 8.

Processing circuit 8 identifies the pixel bright from the magnitude of the voltage of the video signal (e.g., a bright portion 400 cd / ^{m 2,} a dark portion 10 cd / ^{m 2} or so) is displayed. Then, the processing circuit 8 determines the area of the liquid crystal panel 6 to which the pixel belongs, and outputs information for controlling the light source 3 to the light source driver 5 so that only the block immediately below the area is lit. That is, based on the light source control information, the light source driver 5 is configured to switch on and off the light source 3 included in each of the blocks 2a to 2j.

  On the other hand, the processing circuit 8 outputs luminance information and chromaticity information of the video signal to the liquid crystal driver 7, and the liquid crystal driver 7 opens and closes the liquid crystal molecules of the liquid crystal panel 6. As the liquid crystal panel 6, a usual liquid crystal panel can be used.

  In the liquid crystal display device 1 having such a configuration, since the light guide plate 2 is divided into the blocks 2a to 2j, the light emitted from the light source 3 is totally reflected on the side surface where the blocks are abutted. Therefore, light hardly leaks to other blocks other than the lighted block, and the contrast can be increased. Of course, since the light sources of the blocks other than the blocks to be lit are not lit, low power consumption can be realized.

<Embodiment 2>
Embodiment 2 of the liquid crystal display device and light guide plate according to the present invention will be described with reference to FIG.

  The liquid crystal display device according to the present embodiment has substantially the same configuration as the liquid crystal display device according to the first embodiment, but the light guide plate is divided differently. Therefore, only the division form of the light guide plate will be described.

  The light guide plate 12 shown in FIG. 3 is divided into strips so that each of the blocks 12a, 12b, 12c,... For this reason, the liquid crystal display device of this embodiment can hardly increase the contrast because the light hardly leaks to other blocks other than the lighted block.

  Incidentally, in the illustrated example, the blocks are arranged apart from each other, but the blocks are arranged so as to contact each other.

<Embodiment 3>
Embodiment 3 of the liquid crystal display device and light guide plate according to the present invention will be described with reference to FIG.

  The liquid crystal display device of the present embodiment is also configured substantially the same as the liquid crystal display device of the first embodiment, but the configuration of the light guide plate is different. Therefore, only the configuration of the light guide plate will be described.

  The light guide plate 22 shown in FIG. 4 is partitioned into strips so as to have the light source 3 on the side face of each of the blocks 22a, 22b, 22c, and 22d, so that the light does not leak into adjacent blocks. Grooves 9 (the depth is more than half the thickness of the light guide plate and the shape is a wedge shape, a rectangular shape, an arc shape, etc.) are formed on the bottom surface along the partitioned lines. That is, the light guide plate 22 of the present embodiment is not divided into blocks. Even if the light guide plate 22 having such a configuration is used, light hardly leaks to other blocks other than the lighted block, and the contrast can be increased.

  In addition, although the light guide plate 22 of this embodiment was partitioned in strip shape so that it may have the light source 3 in the side surface which opposes, it is not this limitation. That is, it may be divided into 2 × n so that each block has the light source 3.

  In the light guide plates of Embodiments 1 to 3, the ridge is formed only on the bottom surface, but the ridge may also be formed on the exit surface. In this case, ridges are formed on the exit surface so as to be orthogonal to the ridges on the bottom surface.

  Although the light guide plate of the said Embodiments 1-3 formed the protruding item | line by the shaping | molding method or the laser processing, it is not this limitation. A configuration in which dots are formed by printing on the bottom surface of the light guide plate and a reflective film is formed on a side surface other than the incident end surface in each block of the light guide plate may be employed.

It is the figure which showed schematically the structure of the liquid crystal display device of this invention. It is the top view which showed roughly the light-guide plate of Embodiment 1 of this invention. It is the perspective view which showed schematically the light-guide plate of Embodiment 2 of this invention. It is the side view which showed roughly the light-guide plate of Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2a-2j Block 2 Light guide plate 3 Light source 4 Backlight 5 Light source driver 6 Liquid crystal panel 7 Liquid crystal driver 8 Processing circuit 9 Groove part 12 Light guide plates 12a, 12b, 12c Block 22 Light guide plates 22a, 22b, 22c, 22d block

Claims (11)

LCD panel,
A backlight disposed on the back of the liquid crystal panel and having a light source on at least one side of the light guide plate;
A light source driver for driving the light source of the backlight;
A processing circuit for processing a video signal and outputting light source control information to the light source driver;
The light guide plate is divided into a plurality of blocks having a light source,
Based on the light source control information, the light source driver is a liquid crystal display device that switches on / off of the light source of each block. LCD panel,
A backlight disposed on the back of the liquid crystal panel and having a light source on at least one side of the light guide plate;
A light source driver for driving the light source of the backlight;
A processing circuit for processing a video signal and outputting light source control information to the light source driver;
The light guide plate is partitioned into a plurality of blocks having a light source, and a groove is formed on the bottom surface so that light does not leak into adjacent blocks.
Based on the light source control information, the light source driver is a liquid crystal display device that switches on / off of the light source of each block.   2. The liquid crystal display device according to claim 1, wherein dots are formed by printing on a bottom surface of the light guide plate, and a reflective film is formed on a side surface of each block of the light guide plate.   The liquid crystal display device according to claim 1, wherein the bottom surface of the light guide plate has a ridge formed by a molding method or the like.   The light source is disposed on each of two opposite sides of the light guide plate, and the light guide plate is divided into 2 × n pieces so that each block has a light source. The liquid crystal display device according to claim 3 or claim 4.   5. The liquid crystal display device according to claim 1, wherein the light guide plate is divided into strips so as to have a light source on a side surface where each block faces. 6.   A light source is disposed on each of two opposite sides of the light guide plate, and the light guide plate is divided into 2 × n pieces so that each block has a light source, and on the bottom surface so that light does not leak into adjacent blocks. The liquid crystal display device according to claim 2, wherein a groove is formed.   The light guide plate is partitioned in a strip shape so as to have a light source on a side surface facing each block, and a groove is formed on a bottom surface so that light does not leak into an adjacent block. The liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 1, wherein the light source includes a light emitting diode having high parallelism. A light guide plate used in a liquid crystal display device configured to perform area control so that only the backlight immediately below the area displayed brightly on the liquid crystal panel is turned on and the other parts of the backlight are not turned on,
A light guide plate that is divided into a plurality of blocks such that each block has a light source of a backlight. A light guide plate used in a liquid crystal display device configured to perform area control so that only the backlight immediately below the area displayed brightly on the liquid crystal panel is turned on and the other parts of the backlight are not turned on,
A light guide plate that is partitioned into a plurality of blocks so that each block has a light source of a backlight, and a groove is formed on the bottom surface so that light does not leak into adjacent blocks.

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