JP2009288793A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display video to be displayed with necessary luminance without any flicker even when the video abruptly varies in lightness. <P>SOLUTION: A liquid crystal display includes: a liquid crystal panel; a plurality of light source each of which is disposed in each of a plurality of light source areas; a light emitting means which uses the plurality of light sources to illuminate the liquid crystal panel; a light emission control means of controlling the light emission of the plurality of light sources; a virtual lighting value calculating means of calculating light source lighting values for each virtual light source area including virtual areas obtained by virtually dividing the light emitting means to a size different from that of the light source areas, and including the light source areas; a lighting value calculating means of calculating lighting values of the light sources for each light source area using the virtual calculated values calculated by the virtual lighting value calculating means; and a lighting control part which causes the light sources to turn on a light according to the calculated lighting value calculated by the lighting value calculating means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device that controls light emission of a light emitting means such as a backlight that illuminates a liquid crystal panel or the like.

  Currently, liquid crystal display devices are used as image display means in televisions, personal computers, mobile phones and the like. In the liquid crystal display device, since the liquid crystal panel itself does not emit light, a backlight is disposed on the back side of the liquid crystal panel, and the liquid crystal panel is illuminated from the back side with the backlight to display an image.

  In a conventional liquid crystal display device equipped with a backlight, from the viewpoint of reducing power consumption, etc., each light source constituting the backlight and the display screen are divided into a plurality of areas corresponding to each other, and each display screen area (screen area) is divided. In addition, a liquid crystal display device that performs area control for controlling each light source is known.

  With regard to this type of liquid crystal display device, for example, Patent Document 1 discloses the following liquid crystal display device. This liquid crystal display device calculates the maximum brightness of each screen area based on the input video signal, and causes the light source to emit light for each light source area in which the light source is arranged according to the calculated maximum brightness, The luminance information supplied to the liquid crystal panel is corrected.

JP 2004-191490 A

  By the way, in a liquid crystal display device that performs area control, the luminance value of the liquid crystal panel should be inherent by correlating the lighting value for turning on each light source and the transmittance of each liquid crystal element constituting the liquid crystal panel. Control is performed to obtain a desired luminance value.

  However, as described above, even if the lighting value for turning on each light source is correlated with the transmittance of each liquid crystal element constituting the liquid crystal panel, the image to be displayed includes an image including a sharp change in brightness ( Hereinafter, in the case of “abrupt brightness change video”, particularly in the case of a video showing only a small light in the dark, the video may not be displayed with the required brightness.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a liquid crystal display device that can display at a required luminance even when an image to be displayed is a rapidly changing brightness image. And

  In order to solve the above-described problems, a liquid crystal display device according to the present invention includes a liquid crystal panel, a light emitting unit that illuminates the liquid crystal panel using the plurality of light sources, and the light source. For each region, a virtual light source region indicating a region including the light source region and a plurality of virtual regions arranged around the light source region among regions obtained by virtually dividing the light source region of the light emitting unit. A virtual lighting value calculation means for calculating a virtual calculation value for controlling lighting of the light source arranged in the light source region based on a maximum luminance value included in the region of the liquid crystal panel corresponding to According to the lighting value calculation means for calculating the lighting value of the light source for each light source region using the virtual calculation value calculated by the value calculation means, and the calculated lighting value calculated by the lighting value calculation means It characterized by having a a lighting control unit for lighting the light source.

  As described above in detail, according to the present invention, it is possible to obtain a liquid crystal display device capable of displaying with a necessary luminance even if an image to be displayed is a rapidly changing image.

FIG. 1 is an exploded perspective view showing a configuration of a liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a perspective view showing the configuration of the light emitting region and the light source. FIG. 3 is a block diagram showing the configuration of the backlight control unit together with the backlight and the liquid crystal panel. 4A is a diagram illustrating a configuration in which the backlight is divided by the division unit t1, and FIG. 4B is a diagram illustrating a configuration in which the backlight is divided by the virtual division unit t2. FIG. 5 is a diagram illustrating an example of the virtual light source region. FIG. 6 is an enlarged view of the virtual light source region of FIG. FIG. 7 is a diagram illustrating an example of adjacent virtual light source regions.

  Embodiments of the present invention will be described below. In addition, the same code | symbol is used for the same element and the overlapping description is abbreviate | omitted.

  The configuration of the liquid crystal display device 100 according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view showing a configuration of a liquid crystal display device 100 according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a configuration of a light source region and a light source.

  The liquid crystal display device 100 is used for a liquid crystal television or the like, and includes a backlight 140 and a liquid crystal panel 150 as shown in FIG.

  The backlight 140 includes a light emitting unit (light emitting unit) 141 and a pair of diffusion plates 142 and 144 sandwiching a prism sheet 143 disposed on the front surface of the light emitting unit 141, and functions as a light emitting unit. .

  The light emitting unit 141 has a panel shape, and has a matrix structure in which a plurality of light source regions 145 are regularly arranged in M rows and N columns. In FIG. 1, a light emitting unit 141 including a light source region 145 of 5 rows and 8 columns is shown as an example.

  As shown in FIG. 2, the light source region 145 is surrounded on all sides by a partition wall 146 extending in the overlapping direction with the diffusion plate 142 and the like.

  In each light source region 145, a light source 148 including three LEDs 161, 162, and 163 of the three primary colors RGB is arranged. The light source 148 includes a red LED 161, a green LED 162, and a blue LED 163, and emits light toward the front surface (the liquid crystal panel 150) while mixing three colors of red, green, and blue. The back side of the liquid crystal panel 150 is illuminated by the emitted light from each light source region 145, and the transmission of the emitted light through the liquid crystal panel 150 is adjusted to display an image.

  The liquid crystal display device 100 is of a direct type in which the backlight 140 emits light from the entire surface by a plurality of light sources 148 arranged in each light source region 145 and the liquid crystal panel 150 is illuminated from the back.

  The liquid crystal panel 150 includes a pair of polarizing plates 155 and 157 and a liquid crystal 156 sandwiched between the polarizing plates 155 and 157.

  Next, the configuration of the backlight control unit 200 will be described with reference to FIG. Here, FIG. 3 is a block diagram showing the configuration of the backlight control unit 200 together with the backlight 140 and the liquid crystal panel 150.

  The backlight control unit 200 is provided in the liquid crystal display device 100 together with the backlight 140 and the liquid crystal panel 150, and has a function as a light emission control device that controls light emission of a plurality of light sources 148 constituting the backlight 140. .

  The backlight control unit 200 includes a frame memory 101, an input signal correction processing unit 102, a lighting value calculation unit 103, a virtual lighting value calculation unit 104, a lighting control unit 105, and a liquid crystal control unit 106. Yes.

  The backlight control unit 200 inputs a video signal Vg for displaying a video on the liquid crystal panel 150.

  The video signal Vg is input to the frame memory 101 and the virtual lighting value calculation unit 104. The frame memory 101 stores the video signal Vg for each frame. The input signal correction processing unit 102 corrects the video signal Vgt read from the frame memory 101 according to a later-described calculated lighting value Ld calculated by the lighting value calculation unit 103 and outputs the corrected signal to the liquid crystal control unit 106. At this time, the input signal correction processing unit 102 corrects the video signal Vgt while taking the correlation between the video signal Vgt read from the frame memory 101 and the calculated lighting value Ld. The liquid crystal control unit 106 controls the transmittance of the liquid crystal panel 150 according to the corrected video signal Vgt. In this case, the backlight control unit 200 adapts the display timing of the image by the liquid crystal panel 150 and the lighting timing of the light source 148.

  The virtual lighting value calculation unit 104 calculates a lighting value (virtual calculation value) Ld0 of the light source 148 for each virtual light source region 120 to be described later according to the input video signal Vg, and outputs it to the lighting value calculation unit 103. Then, the lighting value calculation unit 103 calculates the lighting value of each light source 148 using the virtual calculation value Ld0, and outputs the lighting value to the lighting control unit 105 as the calculated lighting value Ld. The lighting control unit 105 lights the light source 148 in each light source region 145 according to the calculated lighting value Ld to cause the backlight 140 to emit light.

  Next, the operation content of the backlight control unit 200 having the above configuration will be described with reference to FIGS. 4 to 6 focusing on the operation content of the virtual lighting value calculation unit 104.

  In the present embodiment, the virtual light source region is a region including the virtual region 121 and the light source region 145 obtained by dividing the backlight 140 regularly in the vertical and horizontal directions with a size smaller than the light source region 145 as one unit. It has been established. As shown in FIGS. 4A, 5, and 6, the backlight 140 is an area obtained when the backlight 140 is divided (separated) regularly and vertically by a certain length t <b> 1. Is a light source region 145. In this embodiment, the length t1 when the backlight 140 is divided into a plurality of light source regions 145 is used as a division unit. The lighting value calculation unit 103 calculates the lighting value of the light source 148 for each light source region 145.

  On the other hand, as shown in FIGS. 4B, 5 and 6, the virtual lighting value calculation unit 104 virtually determines a division unit t2 (virtual division unit) smaller in size than the division unit t1, Assuming the case where the backlight 140 is regularly divided horizontally and vertically by the virtual division unit t2, the lighting value of the light source 148 is calculated for each virtual light source region 120 including the virtual region 121 obtained by such virtual division. . By dividing the backlight 140 vertically and horizontally by the virtual division unit t <b> 2, the backlight 140 is virtually divided into areas smaller than the light source area 145.

  The light source region 145 physically exists actually, but the virtual region 121 is virtually determined and does not actually exist. When the backlight 140 is divided by the division unit t2, for example, the coordinates of the liquid crystal element for displaying one pixel provided in the liquid crystal panel 150 can be divided as marks.

  Then, when the backlight 140 is divided by the division unit t2, as shown in FIGS. 5 and 6, a virtual region 121 in which a plurality of virtual regions 121 are arranged around a light source region (target region 123) that is a target for lighting value calculation. A light source region 120 can be assumed.

  As shown in FIG. 5, when considering the target area 123, a lighting value for causing the light source 148 to emit light with a necessary luminance is usually calculated from the value of the video signal corresponding to the target area 123. Although this calculation method is not particularly specified, a luminance value that is maximum in a portion corresponding to the target region 123 in the video signal Vg is calculated, and a lighting value is calculated based on the maximum luminance value. For example, the average luminance value in the portion corresponding to the target region 123 in Vg is calculated, and the lighting value is calculated based on the average luminance value.

  On the other hand, the virtual lighting value calculation unit 104 targets the virtual light source region 120 including the virtual region 121 that is virtually formed by finely dividing the backlight 140 by a division unit t2 smaller than the division unit t1 of the light source region 145. Thus, the lighting value can be calculated in consideration of the virtual region 121 arranged around the target region 123.

  Thus, the virtual lighting value calculation unit 104 can calculate the lighting value by reflecting the luminance information in the virtual region 121 of the video signal Vg, and can calculate the lighting value so that the light source 148 can be brightened. To produce an effect. An example of this point is as follows.

  Here, it is assumed that there is an image including a small rectangular 255 gradation display portion (hereinafter, this portion is referred to as a “small rectangular portion”) having an area ratio of several percent in the dark. For example, in the case of an image showing that only a small light is lit in the dark, such as an image of a midnight seaside where only the light of a small fishing boat is reflected in white. This image is also a sudden change in brightness because the brightness of the image changes abruptly at the small rectangular part.

  It is assumed that the lighting value is calculated for the light source region 145 for such an image as in the related art. Then, it is assumed that the edge portion of the small rectangular portion is located at a position just near the peripheral portion of the light source region 145. Then, the portion immediately adjacent to the edge portion of the image is a black display image, so that it is determined that there is no image signal in the light source region 145 corresponding to the adjacent portion, and the light source 148 does not need to be turned on. A lighting value is calculated. For this reason, the light source 148 is not turned on.

  Since the amount of light emitted from the light source 148 is limited, when displaying an image in which only a specific part (small rectangular part in the above case) is particularly bright, a light source region 145 corresponding to the specific part is displayed. A desired brightness may not be obtained only by lighting. Therefore, such a shortage of light quantity must be compensated by lighting the light source 148 arranged in the peripheral light source region 145. However, when the lighting value is calculated for the light source region 145, the surrounding light source 148 is not turned on, so that the shortage of light quantity cannot be compensated. For this reason, in the video including the small rectangular portion described above, the brightness at the edge portion is insufficient, so that the brightness of the edge portion in the small rectangular portion is lowered and darkened.

  Therefore, in the present embodiment, the virtual lighting value calculation unit 104 is provided, and the lighting value is calculated for the virtual light source region 120 including the virtual region 121, so that the region to be considered when calculating the lighting value is actually calculated. The area is larger than the divided area. By doing so, it becomes possible to supplement the lack of brightness such as the edge portion and express the brightness of the video display with the original brightness.

  For example, as shown in FIG. 7, it is assumed that the target areas 123 and 124 adjacent to each other are considered and the target area 123 is the aforementioned small rectangular portion. The virtual areas 121 and 125 of the target areas 123 and 124 are hatched portions and dot portions, respectively, in FIG. When the brightness of the target area 123 is particularly bright, the amount of light may be insufficient just by turning on the light source 148 of the light source area 145 corresponding to the target area 123.

  However, when the virtual region 125 is provided around the target region 124 adjacent to the target region 123, the brightness of the target region 123 can be reflected when the virtual lighting value calculation unit 104 calculates the lighting value. That is, the luminance information of the virtual region 125 can be reflected in the calculation of the lighting value for the target region 124, and the fact that the portion of the target region 123 in the virtual region 125 is particularly bright can be reflected. . In this way, the light source 148 corresponding to the target area 124 can be turned on, and the shortage of light amount can be resolved.

  In the above embodiment, it is assumed that the division unit t1 of the light source region 145 is twice the virtual division unit t2, but the division unit t1 is larger than twice the virtual division unit t2 (for example, 3 times).

  The above description is the description of the embodiment of the present invention, and does not limit the apparatus and method of the present invention, and various modifications can be easily implemented. In addition, an apparatus or method configured by appropriately combining components, functions, features, or method steps in each embodiment is also included in the present invention.

  DESCRIPTION OF SYMBOLS 100 ... Liquid crystal display device, 101 ... Frame memory, 102 ... Input signal correction process part, 103 ... Lighting value calculation part, 104 ... Virtual lighting value calculation part, 105 ... Lighting control part, 106 ... Lighting control part, 120 ... Virtual light source Area 121, 125 ... Virtual area, 123, 124 ... Target area, 140 ... Back light, 141 ... Light emitting part, 145 ... Light source area, 148 ... Light source, 150 ... Liquid crystal panel, 200 ... Back light control part.

Claims (5)

LCD panel,
A light source disposed in each of a plurality of light source regions, and a light emitting means for illuminating the liquid crystal panel using the plurality of light sources;
For each light source region, a virtual region that includes the light source region and a plurality of virtual regions arranged around the light source region among regions obtained by virtually dividing the light source region of the light emitting unit. A virtual lighting value calculation means for calculating a virtual calculation value for controlling lighting of the light source arranged in the light source area based on a maximum luminance value included in the area of the liquid crystal panel corresponding to the light source area;
Lighting value calculation means for calculating a lighting value of the light source for each light source region using the virtual calculation value calculated by the virtual lighting value calculation means;
A liquid crystal display device comprising: a lighting control unit that lights the light source according to the calculated lighting value calculated by the lighting value calculation means. The light source region in which the light source is arranged in the light emitting means is a rectangular region,
The virtual light source area used in the calculation of the virtual calculated value by the virtual lighting value calculating means includes all the virtual areas arranged adjacent to and obliquely adjacent to the light source area;
The liquid crystal display device according to claim 1. The virtual area included in the virtual light source area used in the calculation of the virtual calculated value by the virtual lighting value calculating means is virtually divided into the light emitting means for each size smaller than the light source area;
The liquid crystal display device according to claim 1 or 2. The virtual area included in the virtual light source area used in the calculation of the virtual calculated value by the virtual lighting value calculating means is obtained by virtually dividing the light emitting means by a size equal to or less than ½ of the light source area. thing,
The liquid crystal display device according to claim 3. Video signal storage means for storing the input video signal in units of frames;
Correction means for correcting the video signal stored in the video signal storage means according to the calculated lighting value calculated by the lighting value calculation means;
A liquid crystal control unit for controlling the liquid crystal panel according to the corrected video signal corrected by the correcting means;
The liquid crystal display device according to claim 1, further comprising:

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