Method for controlling backlight of display device and display device

Abstract

To improve the video quality of a display device.SOLUTION: The display device determines a request luminance value from each of a plurality of pixels to a backlight block, on the basis of a weight determined from a relationship between the position of each of a plurality of pixels in a plurality of display area blocks including a display area block facing a backlight block and adjacent display area blocks of the opposing display area blocks and the position of the backlight block. The display device determines the maximum value of request luminance value to the backlight block to be the luminance value of the backlight block.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to controlling the backlight of a display device. [Background technology]

[0002] In order to reduce the power consumption of the backlight of an LCD display device and improve the contrast ratio, local dimming technology is used, in which the light-emitting surface of the backlight is divided into multiple blocks and the light intensity of each block is individually increased or decreased depending on the brightness within the video frame.

[0003] For example, when a white window is displayed on an all-black background, local dimming technology increases the lighting level (brightness) of the backlight area (block) facing the area where white is displayed, and reduces the light emission level of the backlight area (block) in the background (black) part.

[0004] This control reduces the power consumption of the backlight compared to when the entire backlight area is always lit at 100%, and further increases the difference in brightness between areas with low and high backlight emission, thereby increasing the contrast ratio within the same plane and improving display quality. Examples of local dimming technology are disclosed in Patent Document 1 and Patent Document 2, for example. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2012 / 0139974 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-156355 Summary of the Invention [Problem to be solved by the invention]

[0006] Because the backlight luminance distribution changes within the screen, the luminance difference between backlight blocks becomes particularly noticeable, which can lead to degradation of image quality. Furthermore, when using a backlight with significant light leakage from the block to its surroundings, the luminance of a single block will be lower when only that block is lit than when all blocks are lit. In other words, when there is significant light leakage, the luminance of only one block is significantly reduced, so the luminance of the light source (e.g., LED) for that block must be significantly increased. [Means for solving the problem]

[0007] One aspect of the present disclosure is a method for controlling a backlight in a display device including a display panel and a backlight. The backlight includes multiple backlight blocks. The display panel includes display area blocks facing each of the multiple backlight blocks. The method performs the following processing for each of the multiple backlight blocks. The processing determines a required luminance value from each of the multiple pixels to the backlight block based on a weight determined from the relationship between the position of each of multiple pixels in multiple display area blocks, including a display area block facing the backlight block and a display area block adjacent to the facing display area block, and the position of the backlight block, and the luminance of each of the multiple pixels. Furthermore, the maximum of the required luminance values ​​to the backlight block is determined as the luminance value of the backlight block. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, the image quality of a display device can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 illustrates an example of the configuration of a display device according to an embodiment of the present specification. [Figure 2] 2 shows a schematic diagram of an example of the functional configuration of a video signal processing circuit. [Figure 3]1 shows an example of the overall flow of a method for determining a backlight luminance distribution according to an embodiment of the present specification. [Figure 4A] 1 shows a backlight block associated with one display area block. [Figure 4B] The following shows an example of the relationship between the white area (high gradation area consisting of pixels with a brightness value of 1) within the target display area block and the required brightness value for each backlight block. [Figure 4C] 10 shows another example of the relationship between the white area in the target display area block and the required luminance value for each backlight block. [Figure 4D] 10 shows another example of the relationship between the white area in the target display area block and the required luminance value for each backlight block. [Figure 4E] 10 shows another example of the relationship between the white area in the target display area block and the required luminance value for each backlight block. [Figure 5A] The horizontal weights left_X(m), center_X(m), and right_X(m) are shown when the number of pixels in the horizontal direction of the display area block is 7. [Figure 5B] An example of how to calculate the maximum values ​​max_left_row(n), max_center_row(n), and max_right_row(n) will be shown below. [Figure 5C] The vertical weights up_Y(n), center_Y(n), and down_Y(n) are shown when the number of pixels in the vertical direction of the display area block is 7. [Figure 5D] An example of the distribution of required luminance values ​​from the display area block to the backlight block is shown below. [Figure 6] An example of requested luminance values ​​from a plurality of display area blocks to one backlight block is shown below. [Figure 7] An example is shown in which the backlight is configured with a row of backlight blocks in the horizontal direction (left and right direction in FIG. 7). [Figure 8] An example is shown in which the backlight is configured with a row of backlight blocks in the vertical direction (up and down direction in FIG. 8). [Figure 9] 1 shows an example of pixel luminance distribution in one display area block and required luminance values ​​for each associated backlight block. [Figure 10] 10 shows another example of the luminance value distribution of the display area block. [Figure 11] 10 shows another example of the luminance value distribution of the display area block. [Figure 12] 10 shows another example of the luminance value distribution of the display area block. [Figure 13] 10 shows another example of the luminance value distribution of the display area block. [Figure 14] 10 shows another example of the luminance value distribution of the display area block. [Figure 15] 10 shows another example of the luminance value distribution of the display area block. [Figure 16] 10 shows another example of the luminance value distribution of the display area block. [Figure 17] 10 shows another example of the luminance value distribution of the display area block. [Figure 18] 10 shows another example of the luminance value distribution of the display area block. [Figure 19] 10 shows another example of the luminance value distribution of the display area block. [Figure 20] 10 shows another example of the luminance value distribution of the display area block. [Figure 21] 1 shows the change in luminance value of the backlight block corresponding to the continuous change in the position of the lit pixels in the display area. [Figure 22] 10 shows a plurality of display area blocks and backlight blocks facing them according to a second embodiment. [Figure 23] The values ​​for each backlight block obtained by averaging the luminance of the internal backlight blocks shown in FIG. 22 are shown. [Figure 24] 10 shows an example of how to calculate the required luminance value from the internal display area block. [Figure 25] 10 shows a flowchart of a process for determining a required luminance value for each backlight block from an internal display area block. [Figure 26] 1 illustrates an example of the configuration of a display device according to an embodiment of the present specification. [Figure 27] 1 shows a schematic diagram of a backlight configuration. [Figure 28] 10 shows the required luminance distribution from the first display area facing the first backlight area. [Figure 29] 10 shows the required luminance distribution from the second display area facing the second backlight area. [Figure 30] The required luminance values ​​from the first display area to the second backlight area are shown. [Figure 31] The required luminance value from the second display area to the first backlight area is shown. [Figure 32] The final luminance distribution of the backlight block is shown. [Figure 33] 10 shows an example of data communicated between video signal processing circuits. [Figure 34] 10 shows examples of waveforms of a clock signal SCK, a data signal SDA, and a control signal CS. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that this embodiment is merely an example for realizing the present disclosure and does not limit the technical scope of the present disclosure. The same reference numerals are used to designate common components in each drawing. For clarity of explanation, the dimensions and shapes of the illustrated objects may be exaggerated.

[0011] A display device according to one embodiment of the present specification includes a display panel that displays an image by controlling transmitted light, and a backlight disposed on the rear side of the display panel. The light-emitting area of ​​the backlight is divided into multiple backlight blocks. The display device determines a required luminance value for the backlight block from each of multiple pixels in multiple display area blocks, including a display area block facing the backlight block and at least one adjacent display area block to the facing display area block. The required luminance value is based on a weight determined from the relationship between the pixel position and the backlight block position, and the luminance of the pixel. The display device determines the luminance value of the backlight block to be the maximum of the required luminance values ​​for the backlight block. This configuration improves the image quality of a display device that controls the luminance for each backlight block.

[0012] <Embodiment 1> FIG. 1 shows an example of the configuration of a display device according to an embodiment of the present specification. The display device displays an image by controlling the amount of light transmitted from a backlight. FIG. 1 shows an example of the configuration of a liquid crystal display device 1 as an example of a display device. The liquid crystal display device 1 includes a signal processing board 10, a power supply source 13, a video signal supply source 14, a liquid crystal display panel 20, a display driver 21, a scan driver 22, a backlight 30, a backlight drive board 31, and a backlight power supply source 32. The signal processing board 10 includes a power generation circuit 11 and a video signal processing circuit 12. For example, the signal processing board 10, the display driver 21, the scan driver 22, and the backlight drive board 31 are included in a control device of the liquid crystal display device 1.

[0013] The liquid crystal display panel 20 is disposed in front of (on the viewing side of) the backlight 30, and displays video frames (images) sequentially input from outside by controlling the amount of light transmitted from the backlight 30. The power supply generation circuit 11 includes, for example, a DC-DC converter, and generates power for operating other circuits and supplies power to them. The video signal processing circuit 12 performs processing related to video display, such as generating signals for displaying images on the liquid crystal display panel 20 and signals for controlling the backlight 30. The power supply source 13 supplies power to the power supply generation circuit 11. The video signal supply source 14 supplies video signals to the video signal processing circuit 12.

[0014] The power supply generating circuit 11 generates power for driving ICs such as the video signal processing circuit 12, the display driver 21, and the scan driver 22. The display driver 21 and the scan driver 22 are configured to operate using the power supplied from the power supply generating circuit 11 and to perform their respective processes.

[0015] The display driver 21 generates a data signal from the video signal transmitted from the video signal processing circuit 12 and supplies the data signal to the liquid crystal display panel 20. The scan driver 22 sequentially selects scan lines of the liquid crystal display panel 20 in accordance with a timing signal transmitted from the video signal processing circuit 12. The video signal processing circuit 12 also transmits a timing signal to the display driver 21, and the display driver 21 generates a data signal from the received video signal in accordance with the timing signal and supplies the data signal to the liquid crystal display panel 20.

[0016] The video signal processing circuit 12 uses power supplied from the power generation circuit 11 to convert data arrays for transmitting externally input video signals to the display driver 21, and to generate and transmit timing signals for operating the drivers 21 and 22. The video signal processing circuit 12 further generates drive control signals for driving and controlling the backlight 30, and transmits them to the backlight drive board 31.

[0017] Here, the drive control of the backlight 30 in the video signal processing circuit 12 can be performed, for example, by controlling the duty value (percentage in the time direction) using a PWM method, or by controlling the current value (percentage of the maximum current value) applied to the light source. In this embodiment, the PWM method is used to control a backlight that uses an LED as a light source. The drive control signal for the backlight is sometimes called a PWM signal.

[0018] The backlight 30 is a planar light source device disposed on the rear side of the liquid crystal display panel 20, and emits light necessary for the liquid crystal display panel 20 to display an image. The backlight drive board 31 includes a backlight drive circuit, and controls the lighting (brightness) of the backlight 30 in response to a drive control signal transmitted from the video signal processing circuit 12. The backlight drive board 31 is powered by a power supply source 32 for the backlight.

[0019] As shown in Figure 1, the liquid crystal display device 1 employs local dimming technology, dividing the backlight 30 into X blocks (regions) along the X axis and Y blocks along the Y axis. The liquid crystal display device 1 can individually control the brightness (lighting level) of each of the (X x Y) blocks. To reduce power consumption and improve the contrast ratio, the liquid crystal display device 1 individually controls the lighting level of each block depending on the brightness of the video frame.

[0020] The video signal processing circuit 12 generates a drive control signal for controlling the brightness of each block of the backlight 30 and transmits it to the backlight drive board 31. The backlight drive board 31 drives and controls the light sources (e.g., LEDs) of the backlight 30 so that the blocks emit light at the brightness values ​​(lighting levels) of the blocks indicated by the drive control signals from the video signal processing circuit 12.

[0021] The video signal processing circuit 12 generates timing signals for the display driver 21 and the scan driver 22 in accordance with the timing signals of the input video signal, and sequentially transmits signals for each video frame (frame signals) in the video signal to the display driver 21. The frame signals indicate, for example, the gradation levels of red (R), green (G), and blue (B) of each pixel in the video frame.

[0022] The video signal processing circuit 12 further analyzes the video frame and, based on the analysis results, generates and transmits a drive control signal to the backlight 30 that illuminates the liquid crystal display panel 20 from behind. As described above, the liquid crystal display device 1 employs local dimming technology. The video signal processing circuit 12 determines the brightness value (lighting level) of each block of the backlight 30 based on the analysis results of the video frame.

[0023] The control of the backlight 30 by the video signal processing circuit 12 will be described in detail below. Fig. 2 schematically shows an example of the functional configuration of the video signal processing circuit 12. The video signal processing circuit 12 includes a display control drive signal generation unit 231, a backlight luminance control unit 200, and a backlight drive control signal generation unit 221. The backlight luminance control unit 200 includes a gradation-luminance conversion unit 201, a block luminance value calculation unit 202, and a block luminance value arrangement unit 203.

[0024] The display control drive signal generation unit 231 generates signals to be sent to the display drive driver 21 and the scan driver 22 from the video signal received from the video signal supply source 14. The display control drive signal generation unit 231 sends signals of RGB gradation levels of each pixel indicated by the video frame together with timing signals to the display drive driver 21, and sends the timing signals to the scan driver 22. The display area of ​​the liquid crystal display panel 20 displays an image according to the video frame.

[0025] The gradation-to-luminance converter 201, block luminance value calculator 202, and block luminance value array unit 203 are circuits for determining the luminance value (lighting level) of each block of the backlight 30 based on a video frame. The gradation-to-luminance converter 201 converts the gradation level of a pixel indicated by a video frame into a luminance value (relative luminance value). The luminance value of a pixel referenced to determine the luminance of the backlight is the maximum luminance value of the red, blue, and green elements (also called sub-pixels) that make up that pixel.

[0026] The block brightness value calculation unit 202 determines the brightness value of each block of the backlight 30 based on the brightness values ​​of the pixels in the video frame. Each block of the backlight 30 faces a different part of the display area of ​​the liquid crystal display panel 20. The part of the display area facing the block of the backlight 30 is called a display area block. A display area block includes multiple pixels. To distinguish it from the display area block, the block of the backlight is called a backlight block.

[0027] The block luminance value calculation unit 202 determines the luminance value of the backlight block based on the luminance values ​​of pixels in the display area block facing the backlight block, as well as the luminance values ​​of pixels in display area blocks surrounding the facing display area block. Hereinafter, the luminance values ​​of the pixels and the luminance value of the backlight block are each relative luminance values ​​ranging from 0 to 1. The method by which the block luminance value calculation unit 202 determines the luminance value of the backlight block will be described in detail later.

[0028] The block luminance value arrangement unit 203 generates an array of luminance values ​​for each backlight block calculated by the block luminance value calculation unit 202. The array associates the backlight blocks with their luminance values. The block luminance value arrangement unit 203 transmits the generated array of luminance values ​​to the backlight drive control signal generation unit 221.

[0029] The backlight drive control signal generation unit 221 acquires the determined luminance value for each backlight block from the backlight luminance control unit 200, and generates a drive control signal according to each luminance value. The backlight drive control signal generation unit 221 transmits the drive control signal for each backlight block to the backlight drive board 31.

[0030] An example of a method for determining the luminance value of each backlight block by the backlight luminance control unit 200 is described below. The backlight luminance control unit 200 determines the luminance value of each backlight block based on the luminance values ​​of the pixels of the liquid crystal display panel 20 shown in the video frame. Specifically, the backlight luminance control unit 200 determines the luminance value of each backlight block based on the display area block to which the backlight block faces and the positions of pixels in the display area blocks adjacent to the facing display area block, as well as the luminance values ​​of those pixels.

[0031] 3 shows an example of the overall flow of a method for determining a backlight luminance distribution according to an embodiment of the present specification. In the example described below, the backlight luminance control unit 200 determines a required luminance value (required illumination amount) for each associated backlight block from each display area block (S11). The backlight luminance control unit 200 determines a required luminance value for each associated backlight block based on the pixel luminance distribution (pixel luminance value and position) of the display area block.

[0032] Next, the backlight luminance control unit 200 determines the luminance value of each backlight block based on the luminance value required for each backlight block (S12). In the example described below, the maximum value of all the luminance values ​​required for the backlight block is determined as the luminance value of that backlight block.

[0033] An overview of step S11, which determines a required luminance value for an associated backlight block based on the luminance distribution of the display area block, will be described with reference to Figures 4A to 4E. In this example, a backlight block facing the display area block and a backlight block adjacent to the opposing backlight block are associated with one display area block. The adjacent backlight blocks include backlight blocks adjacent in the horizontal direction (X-axis direction or row direction) and vertical direction (Y-axis direction or column direction) as well as backlight blocks adjacent in diagonal directions. The horizontally and vertically adjacent backlight blocks are examples of backlight blocks that share a boundary line with the opposing backlight block.

[0034] In other examples, only some of the adjacent backlight blocks may be associated with the display area block, or backlight blocks that are farther away than the adjacent backlight blocks may be associated with the display area block. In the examples described below, the backlight blocks and display area blocks are rectangular in shape and arranged in a matrix. Furthermore, pixels are represented by rectangles and arranged in a matrix within the display area. These shapes and layouts are determined by design and are not limited to the examples described below.

[0035] 4A shows a backlight block 401 associated with one display area block. In FIG. 4A, only one backlight block is indicated by the reference numeral 401, for example. The backlight block 401 is shown as a rectangle, and the numbers in the rectangle indicate the coordinates (x, y) of the relative position of the backlight block 401. The backlight block 401 with the coordinates (2, 2) is the backlight block facing the target display area block. In this example, the surrounding blocks are the eight backlight blocks 401 adjacent to the backlight block (2, 2).

[0036] 4B shows an example of the relationship between a white area (high gradation area consisting of pixels with a brightness value of 1) 411 in the target display area block and the required brightness value for each backlight block 401. In the target display area block, the parts other than the white area 411 are black (brightness value 0).

[0037] 4B, the white area 411 is located at the center of the backlight block (2,2). The brightness value of the backlight block (2,2) is 1.0, the same as that of the white area 411. The brightness values ​​of the surrounding backlight block 401 are determined to be close to uniform.

[0038] The required brightness value for adjacent backlight blocks (1,2), (2,1), (2,3), and (3,2) on the top, bottom, left, and right is the same and is smaller (e.g., 0.5) than the required brightness value for the central backlight block (2,2). The required brightness value for adjacent backlight blocks (1,1), (1,3), (3,1), and (3,3) on the diagonal sides is the same and is smaller (e.g., 0.25) than the required brightness values ​​for adjacent backlight blocks on the top, bottom, left, and right.

[0039] 4C shows another example of the relationship between a white region 411 in a target display area block and the required brightness values ​​for each backlight block 401. The white region 411 is located in the upper center of a display area block that has the same shape and plane as the backlight block (2,2). Compared to the example in FIG. 4B, the brightness values ​​of the backlight blocks (1,1), (1,2), and (1,3) are large, and the brightness values ​​of the backlight blocks (3,1), (3,2), and (3,3) are small.

[0040] When the white area 411 is located in the center of the bottom side of the display area block, the opposite control is performed: compared to the example of Fig. 4B, the brightness values ​​of the backlight blocks (1,1), (1,2), and (1,3) are small, and the brightness values ​​of the backlight blocks (3,1), (3,2), and (3,3) are large.

[0041] 4D shows another example of the relationship between a white region 411 in a target display area block and the required brightness values ​​for each backlight block 401. The white region 411 is located in the center left of the display area block. Compared to the example in FIG. 4B, the brightness values ​​of backlight blocks (1,1), (2,1), and (3,1) are large, and the brightness values ​​of backlight blocks (1,3), (2,3), and (3,3) are small.

[0042] When the white area 411 is located in the center of the right side of the display area block, the opposite control is performed: compared to the example of Fig. 4B, the brightness values ​​of the backlight blocks (1,1), (2,1), and (3,1) are small, and the brightness values ​​of the backlight blocks (1,3), (2,3), and (3,3) are large.

[0043] 4E shows another example of the relationship between a white region 411 in a target display area block and the required brightness values ​​for each backlight block 401. The white region 411 is located in the upper right corner of the display area block. Compared to the example in FIG. 4B, the brightness values ​​of backlight blocks (1,2), (1,3), and (2,3) are large, and the brightness values ​​of backlight blocks (1,1), (2,1), (3,1), (3,2), and (3,3) are small.

[0044] Similarly, when the white area 411 is located at the bottom right, top left, or bottom left, the backlight luminance control unit 200 increases the luminance of the backlight block closer to the white area 411 and decreases the luminance of the backlight block farther away.

[0045] Below, an example of a method (S11) for determining a required luminance value for a backlight block from the luminance distribution of a display area block will be specifically described. The method described below is just one example, and other methods for determining the luminance value of a backlight block may be used. In the example described below, similar to the above example, required luminance values ​​from a target display area block are determined for a backlight block facing the target display area block and eight surrounding adjacent backlight blocks.

[0046] First, the backlight luminance control unit 200 calculates horizontal weighting coefficients (simply called weights) to be assigned to the pixels of the display area block. The calculated weights are weights for the required luminance values ​​for the left, center, and right backlight blocks.

[0047] The left weight left_X(m), center weight center_X(m), and right weight right_X(m) can be calculated using the following formulas. left_X(m) ={(H_pixnumber-1)-X(m)} / (H_pixnumber-1) center_X(m)=1.0 right_X(m)=X(m) / (H_pixnumber-1)

[0048] X(m) represents the X coordinate (horizontal coordinate) of a pixel in the display area block. H_pixnumber represents the number of pixels in the horizontal direction (X axis direction) in the display area block.

[0049] 5A shows horizontal weights left_X(m), center_X(m), and right_X(m) when the number of horizontal pixels in the display area block is 7. The X coordinate m is an integer ranging from 0 to 6.

[0050] left_X(m) is the weight for backlight blocks (1,1), (2,1), and (3,1) in FIG. 4A. left_X(m) decreases from left to right. center_X(m) is the weight for backlight blocks (1,2), (2,2), and (3,2) in FIG. 4A. center_X(m) is constant at 1.0. right_X(m) is the weight for backlight blocks (1,3), (2,3), and (3,3). right_X(m) decreases from right to left. In this way, the horizontal weight can be expressed as a decreasing function of the distance between the pixel and the backlight block.

[0051] Next, the backlight luminance control unit 200 calculates the product of each pixel luminance value in the display area block and the three weights. Furthermore, the backlight luminance control unit 200 determines the maximum value of the products of the pixel luminance value and each of the three weights for each pixel row (pixels arranged in the X-axis direction).

[0052] The maximum value of the product of left_X(m) and pixel brightness value L(m) in pixel row n is represented as max_left_row(n). The maximum value of the product of center_X(m) and pixel brightness value L(m) in pixel row n is represented as max_center_row(n). The maximum value of the product of right_X(m) and pixel brightness value L(m) in pixel row n is represented as max_right_row(n). n is an integer between 0 and the number of pixel rows in the display area block minus 1.

[0053] max_left_row(n), max_center_row(n), and max_right_row(n) can be calculated using the following formulas.

[0054] max_left_row(n)=MAX{L(m)×left_X(m)} max_row_line(n) =MAX{L(m)×center_X(m)} max_right_row(n)=MAX{L(m)×right_X(m)}

[0055] 5B shows an example of how to calculate the maximum values ​​max_left_row(n), max_center_row(n), and max_right_row(n). In an example of pixel luminance distribution in the display area block 451, only one pixel (1,1) emits light with a luminance value of 1.0, and the luminance values ​​of the other pixels are 0. max_left_row(n), max_center_row(n), and max_right_row(n) are calculated from the pixel luminance distribution in this display area block 451 and the horizontal weights shown in FIG. 5A.

[0056] 5B, the maximum values ​​of pixel rows other than pixel row row(1) are 0. The maximum values ​​max_left_row(n), max_center_row(n), and max_right_row(n) of pixel row row(1) are each a value obtained by multiplying the weight at an X coordinate of 1 by the brightness value 1.

[0057] Next, the backlight luminance control unit 200 calculates vertical weights to be assigned to the pixels of the display area block. The calculated weights are weights for the required luminance values ​​for the upper, middle, and lower backlight blocks.

[0058] The upper weight up_Y(n), the center weight center_Y(n), and the lower weight down_Y(n) can be calculated by the following equations. up_Y(n) ={(V_pixnumber-1)-Y(n)} / (V_pixnumber-1) center_Y(n)=1.0 down_Y(n)=Y(n) / (V_pixnumber-1)

[0059] Y(n) represents the Y coordinate (vertical coordinate) of a pixel in the display area block. V_pixnumber represents the number of pixels in the vertical direction (Y axis direction) in the display area block.

[0060] 5C shows the vertical weights up_Y(n), center_Y(n), and down_Y(n) when the number of pixels in the vertical direction of the display area block is 7. The Y coordinate n is an integer ranging from 0 to 6.

[0061] up_Y(n) is the weight for backlight blocks (1,1), (1,2), and (1,3) in FIG. 4A. up_Y(n) decreases from top to bottom. center_Y(n) is the weight for backlight blocks (2,1), (2,2), and (2,3) in FIG. 4A. center_Y(n) is constant at 1.0. down_Y(n) is the weight for backlight blocks (3,1), (3,2), and (3,3). down_Y(n) decreases from bottom to top. In this way, the vertical weight can be expressed as a decreasing function of the distance between the pixel and the backlight block.

[0062] Next, the backlight luminance control unit 200 calculates the product of the maximum values ​​of each pixel row, max_left_row(n), max_center_row(n), max_right_row(n), and the vertical weight. Furthermore, the backlight luminance control unit 200 determines the maximum values ​​for each of nine different combinations of horizontal and vertical values. The nine combinations of directions correspond to the nine positions of the backlight block shown in FIG. 4A. These maximum values ​​form the distribution of required luminance values ​​from the display area block to the associated backlight block.

[0063] 5D shows an example of a distribution of required luminance values ​​from the display area block to the backlight block. The distribution of required luminance values ​​consists of nine sections: max_left_up, max_center_up, max_right_up, max_left_center, max_center_center, max_right_center, max_left_down, max_center_down, and max_right_down. These correspond to the backlight blocks (1,1), (1,2), (1,3), (2,1), (2,2), (2,3), (3,1), (3,2), and (3,3) shown in FIG. 4A.

[0064] The required luminance values ​​can be calculated according to the following formulas. max_left_up =MAX{max_left_row(n)×up_Y(n)} max_left_center =MAX{max_left_row(n)×center_Y(n)} max_left_down =MAX{max_left_row(n)×down_Y(n)}

[0065] max_center_up =MAX{max_center_row(n)×up_Y(n)} max_center_center =MAX{max_center_row(n)×center_Y(n)} max_center_down =MAX{max_center_row(n)×down_Y(n)}

[0066] max_right_up =MAX{max_right_row(n)×up_Y(n)} max_right_center =MAX{max_right_row(n)×center_Y(n)} max_right_down =MAX{max_right_row(n)×down_Y(n)}

[0067] Figure 5D further illustrates the required luminance distribution for the example described with reference to Figures 5A to 5C, with the values ​​calculated as follows:

[0068] max_left_up =MAX{0×1.0,0.83×0.83,0×0.67,0×0.50, 0×0.33,0×0.17,0×0.0} =0.83×0.83=0.69

[0069] max_left_center =MAX{0×1.0,0.83×1.0,0×1.0,0×1.0, 0×1.0,0×1.0,0×1.0} =0.83×1.0=0.83

[0070] max_left_down =MAX{0×0.0,0.83×0.17,0×0.33,0×0.50, 0×0.67,0×0.83,0×1.0} =0.83×0.17=0.14

[0071] max_center_up =MAX{0×1.0,1×0.83,0×0.67,0×0.50, 0×0.33,0×0.17,0×0.0} =1×0.83=0.83

[0072] max_center_center =MAX {0×1.0,1×1.0,0×1.0,0×1.0, 0×1.0,0×1.0,0×1.0} =1×1.0=1.0

[0073] max_center_down =MAX{0×0.0,1×0.17,0×0.33,0×0.50, 0×0.67,0×0.83,0×1.0} =1×0.17=0.17

[0074] max_right_up =MAX{0×1.0,0.17×0.83,0×0.67,0×0.50, 0×0.33,0×0.17,0×0.0} =0.17×0.83=0.14

[0075] max_right_center =MAX{0×1.0,0.17×1.0,0×1.0,0×1.0, 0×1.0,0×1.0,0×1.0} =0.17×1.0=0.17

[0076] max_right_down =MAX{0×0.0,0.17×0.17,0×0.33,0×0.50, 0×0.67,0×0.83,0×1.0} =0.17×0.17=0.03

[0077] As described above, the backlight luminance control unit 200 calculates the luminance value required from the display area block to each associated backlight block. For each pixel in the display area block, the weight for each backlight block is expressed as the product of the horizontal weight and vertical weight according to the pixel's position. The maximum value of the product of the pixel's luminance value and the weight for the backlight block is the luminance value required for the display area block to that backlight block. For example, the weight for the opposing backlight block is 1. Therefore, the luminance value required for the backlight block opposing the display area block matches the maximum luminance value within the display area block.

[0078] In the above example, the weight of each pixel is calculated based on the pixel's position, and the required brightness value from the display area block to the backlight block is determined from the calculated weight and the pixel's brightness value. This significantly reduces the memory required compared to a configuration in which weights for each associated backlight block are stored in advance.

[0079] Note that weights may be set in advance for each backlight block of all pixels. The method for calculating the maximum required luminance value for the backlight block in the display area block is not limited to the above example. For example, the maximum value for a vertical pixel row may be determined and then multiplied by a horizontal weight.

[0080] Next, an example of a method (S12) for determining the luminance value of a backlight block based on the luminance values ​​requested from multiple display area blocks to the backlight block will be described. The backlight luminance control unit 200 determines the maximum value of all the luminance values ​​requested to the backlight block as the luminance value of the backlight block.

[0081] Figure 6 shows an example of requested brightness values ​​from multiple display area blocks to one backlight block. Display area block (2,2) faces the target backlight block. Note that display area block (x,y) indicates the display area block with relative coordinates (x,y).

[0082] The required brightness value from the display area block (1,1) to the target backlight block is max_right_down=0.08. The required brightness value from the display area block (1,2) to the target backlight block is max_center_down=0.6. The required brightness value from the display area block (1,3) to the target backlight block is max_left_down=0.05.

[0083] The required brightness value from the display area block (2,1) to the target backlight block is max_right_center=0.7. The required brightness value from the display area block (2,2) to the target backlight block is max_center_center=0.5. The required brightness value from the display area block (2,3) to the target backlight block is max_left_center=0.4.

[0084] The required brightness value from the display area block (3,1) to the target backlight block is max_right_up=0.1. The required brightness value from the display area block (3,2) to the target backlight block is max_center_up=0.1. The required brightness value from the display area block (3,3) to the target backlight block is max_left_up=0.81.

[0085] The backlight luminance control unit 200 determines the maximum value of the requested luminance values ​​as the luminance value of the target backlight block. In this example, the maximum value is max_left_up=0.81.

[0086] In the example configuration shown in Fig. 6, the backlight blocks are arranged in a matrix. Each backlight block is associated with the display area block facing it and the display area blocks adjacent to it in the horizontal, vertical, and diagonal directions. In other example configurations, each backlight block may be associated with only a portion of the peripheral display area blocks.

[0087] FIG. 7 shows an example in which the backlight 30 is configured with a row of backlight blocks in the horizontal direction (left-right direction in FIG. 7). The backlight blocks are associated with the opposing display area blocks and the horizontally adjacent display area blocks. In FIG. 7, only the display area blocks (2,1), (2,2), and (2,3) exist; no other display area blocks exist. Therefore, the required brightness values ​​of all other display area blocks are 0. The brightness value of the target backlight block in the example of FIG. 7 can be determined using the calculation method described with reference to FIGS. 5A to 6.

[0088] In the example of FIG. 7, the required brightness value from the display area block (2,1) to the target backlight block is max_right_center=0.7. The required brightness value from the display area block (2,2) to the target backlight block is max_center_center=0.5. The required brightness value from the display area block (2,3) to the target backlight block is max_left_center=0.4. The maximum value of these values ​​is max_right_center=0.7, and the brightness value of the target backlight block is determined to be 0.7.

[0089] FIG. 8 shows an example in which the backlight 30 is configured with a single row of backlight blocks in the vertical direction (the up-down direction in FIG. 8). Each backlight block is associated with an opposing display area block and a vertically adjacent display area block. In FIG. 8, only display area blocks (1,2), (2,2), and (3,2) exist; no other display area blocks exist. Therefore, the required brightness values ​​of all other display area blocks are 0. The brightness value of the target backlight block in the example of FIG. 8 can be determined using the calculation method described with reference to FIGS. 5A to 6.

[0090] In the example of FIG. 8, the required brightness value from the display area block (1,2) to the target backlight block is max_center_down=0.6. The required brightness value from the display area block (2,2) to the target backlight block is max_center_center=0.5. The required brightness value from the display area block (3,2) to the target backlight block is max_center_up=0.1. The maximum value of these values ​​is max_center_down=0.6, and the brightness value of the target backlight block is determined to be 0.6.

[0091] An example of the brightness values ​​required from one display area block to its associated backlight blocks is described below. Figure 9 shows an example of the pixel brightness distribution of one display area block 451 and the brightness values ​​required for each of the associated backlight blocks 401. The display area block 451 is associated with a central opposing backlight block and eight surrounding backlight blocks.

[0092] 9, display area block 451 faces the central backlight block. In display area block 451, the luminance value of the pixel in the upper left corner is 1.0, and the luminance values ​​of all other pixels are 0. Corresponding to this luminance value distribution, the luminance value required for the upper left backlight block is large, and the luminance value required for the lower right backlight block is small.

[0093] 10 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the pixel at the center left edge is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the backlight block on the left is large, and the brightness value required for the backlight block on the right is small.

[0094] 11 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the pixel in the lower left corner is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the lower left backlight block is large, and the brightness value required for the upper right backlight block is small.

[0095] 12 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the pixel at the top center is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the upper backlight block is large, and the brightness value required for the lower backlight block is small.

[0096] 13 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the central pixel is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the central backlight block is large, and the brightness values ​​required for the surrounding backlight blocks are small.

[0097] 14 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the pixel at the bottom center is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the lower backlight block is large, and the brightness value required for the upper backlight block is small. 15 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the pixel in the upper right corner is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the upper right backlight block is large, and the brightness value required for the lower left backlight block is small.

[0098] 16 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the pixel at the center right edge is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the backlight block on the right is large, and the brightness value required for the backlight block on the left is small.

[0099] 17 shows another example of the brightness value distribution of the display area block 451. In the display area block 451, the brightness value of the pixel in the lower right corner is 1.0, and the brightness values ​​of all other pixels are 0. Corresponding to this brightness value distribution, the brightness value required for the lower right backlight block is large, and the brightness value required for the upper left backlight block is small.

[0100] 18 shows another example of the brightness value distribution of the display area block 451. The brightness value of the pixel one pixel inward in the horizontal and vertical directions from the upper left corner is 1.0, and the brightness values ​​of all other pixels are 0. Compared to the example of the brightness distribution shown in FIG. 9, there is one pixel with a brightness value of 1.0 located below and to the right. This position of the pixel with a brightness value of 1.0 is reflected in the brightness value required for each backlight block 401.

[0101] That is, compared to the backlight brightness value distribution in Fig. 9, the brightness value required for the upper backlight block is smaller and the brightness value required for the lower backlight block is larger. Also, the brightness value required for the left backlight block is smaller and the brightness value required for the right backlight block is larger.

[0102] 19 shows another example of the brightness value distribution of the display area block 451. The brightness value of two pixels is 1.0, and the brightness value of the other pixel is 0. As described above, of the requested values ​​from each of the two pixels to each of the backlight blocks, which are determined based on the pixel positions and brightness values, the maximum value is the requested brightness value to the backlight block.

[0103] The brightness value distribution of the display area block in Fig. 19 adds a brightness value of 1.0 to the upper right pixel in addition to the brightness value distribution in Fig. 14. The required brightness value from this pixel is reflected in the required brightness values ​​for the top three blocks and the backlight block 401 in the center right.

[0104] 20 shows another example of the brightness value distribution of the display area block 451. The brightness value of the pixel one pixel inward in the horizontal and vertical directions from the upper right corner is 0.5, and the brightness values ​​of all other pixels are 0. Compared to the example of the brightness distribution shown in FIG. 15, there is one pixel with half the brightness value located below and to the left. This brightness value and position of the pixel are reflected in the brightness value requested for each backlight block 401.

[0105] That is, the required luminance values ​​for the lower and left backlight blocks are larger than in the backlight luminance value distribution in Fig. 15. Also, the required luminance values ​​for the backlight blocks from the center to the right and above are smaller.

[0106] Figure 21 shows the change in brightness value of a backlight block corresponding to a continuous change in the position of lit pixels in the display area. Figure 21 shows an example in which a pixel with a brightness value of 1.0 moves from left to right within one display area block. In each state, only one pixel is lit, and the brightness values ​​of the other pixels are 0. Figure 21 also shows the brightness distribution of the backlight block 401 corresponding to each brightness distribution of the display area block 451.

[0107] As a result of calculating the required brightness value for the backlight block 401 as described above, as the position of a high gradation within the display area block 451 moves, the illumination level (brightness) of the backlight block 401 surrounding the backlight block 401 facing the high gradation position changes continuously. In the example shown in Fig. 21, one display area block 451 is made up of 7x7 pixels, and the illumination level of the backlight block 401 changes in seven stages. In actual implementation, the display area block 451 may be made up of a larger number of pixels.

[0108] For example, let's consider a 12.3-inch WHD resolution and a configuration in which the backlight is divided into 96 x 36 = 3456 parts. The number of pixels that make up one display area block (pixels facing the backlight block) is approximately 20 x 20 = 400. Therefore, the amount of illumination can be changed in 20 steps, which is a sufficiently fine change that allows for continuous brightness changes.

[0109] Figure 21 explains the change in the illumination level of consecutive backlight blocks, focusing on the horizontal movement of lit pixels, but changes in the illumination level of consecutive backlight blocks also appear in other directions, specifically the vertical or diagonal directions.

[0110] As shown in FIG. 21 , the illumination level of an adjacent backlight block 401 that is closer to a high-brightness pixel increases, while the illumination level of an adjacent backlight block 401 that is further away decreases. This operation can prevent abrupt changes in the brightness of the backlight block 401. For example, in a configuration in which the brightness of a backlight block is determined solely based on high-brightness pixel information in an opposing display area block, or in a configuration in which the brightness of a surrounding backlight block is determined without depending on the pixel position within the display area block, when a lit pixel crosses the boundary between backlight blocks, the brightness of the backlight block changes abruptly, causing image quality degradation. The configuration disclosed in this specification can prevent this image quality degradation.

[0111] The configuration of the backlight 30 will now be described. For example, a direct-type backlight may include a light source array arranged in the backlight plane so as to face the liquid crystal display panel 20, and a diffusion plate between the light source array and the liquid crystal display panel 20. A typical example of a light source is an LED. A plurality of LEDs may be arranged in a backlight block 401. The number of LEDs in one backlight block 401 is arbitrary. An optimal number of LEDs are arranged in optimal positions based on the luminance efficiency and luminance distribution of the LEDs.

[0112] The backlight 30 may be an edge type including a light guide plate and a light source disposed on a side surface, instead of the direct type as described above. The backlight 30 may be composed of backlight blocks arranged in a matrix, for example, or may be composed of backlight blocks arranged in a horizontal or vertical row.

[0113] <Embodiment 2> Another example of a method for determining a required luminance value for a backlight block based on the luminance value and position of a pixel is described below. In the method described below, one backlight block is divided to define multiple internal backlight blocks. The portion of the display area facing each internal backlight block is defined as an internal display area block. One display area block is the portion of the display area facing the backlight block and is made up of multiple internal display area blocks.

[0114] The backlight luminance control unit 200 determines the luminance value of an internal display area block from the luminance values ​​of the pixels in the internal display area block. The backlight luminance control unit 200 determines the required luminance value for each associated internal backlight block based on the luminance value of the internal display area block. The backlight luminance control unit 200 determines the luminance value of a backlight block based on the required luminance value for that internal backlight block.

[0115] A specific example will be described below. Fig. 22 shows a plurality of display area blocks 451 and the backlight block 401 facing them. Nine display area blocks 451 arranged in a matrix are shown, and one of them is shown as an example with reference numeral 45. 1 For ease of illustration, adjacent display area blocks 451 are separated by spaces, but in reality they are contiguous.

[0116] 22, the display area block 451 is divided into four internal display area blocks 471. Some of the display area blocks 471 are shown as dashed rectangles, and one internal display area block is indicated by the reference numeral 471 as an example.

[0117] FIG. 22 further shows nine backlight blocks 401 facing each of the plurality of display area blocks 451. One backlight block is designated by the reference numeral 401 as an example. For ease of explanation, adjacent backlight blocks 401 are separated by spaces, but in reality, they are adjacent to each other. The backlight block 401 is divided into four internal backlight blocks. Some of the internal backlight blocks are designated by reference numerals. Specifically, internal backlight blocks IB1 to IB9 each face an internal display area block 471 surrounded by a dashed line.

[0118] In the example shown in Figure 22, only one pixel is lit with a brightness value of 1.0, and the other pixels are not lit (brightness value 0). Internal backlight block IB5 is the internal backlight block facing the lit pixel. The brightness values ​​(required brightness values) of internal backlight blocks IB1 to IB9 are represented by numbers within the rectangles. Specifically, the brightness value of internal backlight block IB5 is 1.0, the brightness values ​​of internal backlight blocks IB2, IB4, IB6, and IB8 adjacent to it on the left, right, top, and bottom are 0.5, and the brightness values ​​of internal backlight blocks IB1, IB3, IB7, and IB9 adjacent to it diagonally are 0.25.

[0119] In this example, the backlight brightness control unit 200 determines the brightness value required for the associated internal backlight block regardless of the pixel position within the internal display area block 471. The weights of the brightness values ​​required from the internal display area block to the internal backlight block are set in advance. In the example shown in Fig. 22, the weight of the opposing internal backlight block is 1.0, the weights of the internal backlight blocks adjacent above, below, left, and right are 0.5, and the weight of the diagonally adjacent internal backlight block is 0.25.

[0120] The backlight luminance control unit 200 selects the maximum luminance value in the internal display area block and multiplies the maximum luminance value by a predetermined weight to determine the required luminance value for each related internal backlight block. Therefore, the required luminance values ​​for each of the internal backlight blocks IB1 to IB9 are as shown in FIG. 22.

[0121] Next, the backlight luminance control unit 200 calculates the average value of the required luminance values ​​of the internal backlight blocks for each backlight block 401. Fig. 23 shows a value 481 for each of the backlight blocks B1 to B9 obtained by averaging the luminance of the internal backlight blocks shown in Fig. 22.

[0122] Backlight block B5 is composed of internal backlight blocks IB5, IB6, IB8, and IB9. Internal backlight block IB1 is included in backlight block B1. Internal backlight blocks IB2 and IB3 are included in backlight block B2. Internal backlight blocks IB4 and IB7 are included in backlight block B4. For example, the value of backlight block B5 is (1 + 0.5 + 0.5 + 0.25) / 4 = 0.56.

[0123] Next, as shown in Fig. 24, backlight luminance control unit 200 normalizes the value 481 of each backlight block. Specifically, backlight luminance control unit 200 normalizes the value of each backlight block so that the luminance value of the internal display area block matches the luminance value of the opposing backlight block (becomes 1 in Fig. 24). Normalized values ​​482 of backlight blocks B1 to B9 are as shown in Fig. 24.

[0124] 24, a required luminance value 484 for each of the backlight blocks B1 to B9 from the internal display area block is determined by multiplying a preset coefficient 483 by the normalized value 482. The required luminance value (weight) for each of the peripheral backlight blocks can be calculated more appropriately using the coefficient.

[0125] The above control increases the brightness of backlight blocks closer to the high-gradation pixels in the video frame and decreases the brightness of backlight blocks further away. Specifically, as shown in Figure 24, the brightness of backlight blocks B1, B2, and B4 is high, while the brightness of backlight blocks B6, B8, and B9 is low. In this way, this control can increase the contrast within the same plane. Furthermore, the circuit scale can be reduced compared to methods that acquire high-gradation position information on a pixel-by-pixel basis.

[0126] 25 shows a flowchart of the above process for determining the required brightness value for each backlight block from the internal display area block. As described above, the backlight brightness control unit 200 determines the required brightness value for the associated internal backlight block based on the brightness value of the internal display area block (S31). In the above example, the backlight brightness control unit 200 determines the required brightness value for the internal backlight block as the product of the maximum brightness value in the internal display area block and a preset coefficient for each associated internal backlight block.

[0127] Next, the backlight luminance control unit 200 calculates the average value of the required luminance values ​​of the internal backlight blocks for each backlight block including the relevant internal backlight block (S32).

[0128] Next, the backlight luminance control unit 200 normalizes the values ​​of the backlight blocks facing the internal display area block so that the average value of the backlight blocks facing the internal display area block matches the maximum luminance value of the internal display area block (S33).

[0129] Next, the backlight luminance control unit 200 corrects the normalized value by a predetermined coefficient and determines the required luminance value for each of the internal display area blocks to the backlight block (S34). In the above example, the backlight luminance control unit 200 multiplies the normalized value by a predetermined coefficient to calculate the required luminance value for each of the backlight blocks.

[0130] <Embodiment 3> FIG. 26 shows an example of the configuration of a display device according to an embodiment of the present specification. Differences from the example configuration shown in FIG. 1 will be mainly described below. The liquid crystal display device 1 includes video signal supply sources 14A and 14B and display drivers 21A and 21B. The signal processing board 10 includes video signal processing circuits 12A and 12B. The video signal processing circuit 12A is a first processing circuit, and the video signal processing circuit 12B is a second processing circuit. This configuration can be adopted when the display area has a high resolution that exceeds the resolution that can be driven by a single IC, and multiple ICs are used to drive the display area divided into vertical, horizontal, etc.

[0131] The liquid crystal display panel 20 includes a first display region 250A and a second display region 250B adjacent to each other. The video signal processing circuit 12A performs processes related to video display, such as generating signals for displaying an image in the first display region 250A and signals for controlling the backlight 30. The video signal processing circuit 12B performs processes related to video display, such as generating signals for displaying an image in the second display region 250B and signals for controlling the backlight 30. The video signal supply source 14A supplies video signals to the video signal processing circuit 12A, and the video signal supply source 14B supplies video signals to the video signal processing circuit 12B.

[0132] The display driver 21A generates a data signal from the video signal transmitted from the video signal processing circuit 12A and supplies the data signal to the first display area 250A. B is The video signal processing circuit 12A generates a data signal from the video signal transmitted from the video signal processing circuit 12B and supplies the data signal to the second display region 250B. Teta The display driver 21A generates a data signal from the received video signal in accordance with the timing signal and supplies the data signal to the first display region 250A. B is , for the display driver 21B Teta The display driver 21B generates a data signal from the received video signal in accordance with the timing signal and supplies the data signal to the second display region 250B.

[0133] The video signal processing circuit 12A uses power supplied from the power generation circuit 11 to convert data arrays for transmitting externally input video signals to the display driver 21A, and to generate and transmit timing signals for operating the drivers 21A and 22. The video signal processing circuit 12A further generates drive control signals for driving and controlling the backlight 30, and transmits them to the backlight drive board 31.

[0134] The video signal processing circuit 12B uses power supplied from the power generation circuit 11 to convert data arrays for transmitting externally input video signals to the display driver 21B, and to generate and transmit timing signals for operating the drivers 21B and 22. The video signal processing circuit 12B further generates drive control signals for driving and controlling the backlight 30, and transmits them to the backlight drive board 31.

[0135] The backlight drive board 31 includes a backlight drive circuit, and controls the lighting (brightness) of the backlight 30 in response to drive control signals transmitted from the video signal processing circuits 12A and 12B.

[0136] The video signal processing circuits 12A and 12B each generate a drive control signal for controlling the brightness of each block of the backlight 30 and transmit the signal to the backlight drive board 31. The backlight drive board 31 drives and controls the light source of the backlight 30 so that the block emits light at the brightness value indicated by the drive control signal from the video signal processing circuits 12A and 12B.

[0137] The video signal processing circuit 12A generates timing signals for the display drive driver 21A and the scan driver 22 in accordance with the timing signals of the input video signal, and sequentially transmits signals for each video frame (frame signal) in the video signal to the display drive driver 21A. The video signal processing circuit 12B generates timing signals for the display drive driver 21B and the scan driver 22 in accordance with the timing signals of the input video signal, and sequentially transmits signals for each video frame (frame signal) in the video signal to the display drive driver 21B.

[0138] Video signal processing circuit 12A analyzes the video frame and, based on the analysis results, generates and transmits a drive control signal to backlight 30 that illuminates first display region 250A from behind. Video signal processing circuit 12B analyzes the video frame and, based on the analysis results, generates and transmits a drive control signal to backlight 30 that illuminates second display region 250B from behind.

[0139] FIG. 27 schematically shows the configuration of the backlight 30. The backlight 30 is composed of a first backlight region (BL region) 350A on the left side and a second backlight region 350B on the right side. The first backlight region 350A is located directly below the first display region 250A. The first backlight region 350A faces the first display region 250A on the backside of the first display region 250A and irradiates light onto the first display region 250A. The second backlight region 350B is located directly below the second display region 250B. The second backlight region 350B faces the second display region 250B on the backside of the second display region 250B and irradiates light onto the second display region 250B.

[0140] The first backlight area 350A is composed of nine backlight blocks (first backlight block group) B1L to B9L. Here, the case of nine backlight blocks will be described, but the number is not limited to nine and may be N×M (N and M are natural numbers) blocks. The second backlight area 350B is composed of nine backlight blocks (second backlight block group) B1R to B9R. Backlight blocks B3L, B6L, and B9L are adjacent to the second backlight area 350B. Backlight blocks B1R, B4R, and B7R are adjacent to the first backlight area 350A.

[0141] The video signal processing circuit 12A transmits information on the required luminance values ​​from the display area blocks in the first display area 250A to the backlight blocks of the second backlight area 350B to the video signal processing circuit 12B. The video signal processing circuit 12B controls the luminance of the second backlight area 350B based on the required luminance values ​​from the display blocks of the second display area 250B and the required luminance values ​​from the display area blocks of the first display area 250A received from the video signal processing circuit 12A.

[0142] The video signal processing circuit 12B transmits information on the required luminance values ​​from the display area blocks in the second display area 250B to the backlight blocks of the first backlight area 350A to the video signal processing circuit 12A. The video signal processing circuit 12A controls the luminance of the first backlight area 350A based on the required luminance values ​​from the display blocks of the first display area 250A and the required luminance values ​​from the display area blocks of the second display area 250B received from the video signal processing circuit 12B.

[0143] The required luminance values ​​from the display area blocks to the backlight blocks can be determined as described in the other embodiments above. Each of the video signal processing circuits 12A and 12B can suppress unnatural luminance changes at the boundary between the two display areas 250A and 250B by reflecting the required luminance values ​​from the display areas that it is not responsible for in the luminance control of the backlight area that it is responsible for.

[0144] The following describes an example in which video signal processing circuits 12A and 12B communicate information about the required brightness values ​​from the display blocks, and the required brightness value of one display area is reflected in the brightness control of the other backlight area. As described above, the brightness value of each backlight block is determined based on the required brightness values ​​from the display area blocks facing that backlight block and the eight surrounding adjacent backlight blocks. Furthermore, the required brightness value from the display block is determined according to the pixel position with the maximum brightness within the display block.

[0145] 28 shows the required luminance distribution from the first display region 250A facing the first backlight region 350A. In this example, only the display region block D6L facing the backlight block B6L includes the luminance to be emitted. In the display region block D6L, only one pixel has a maximum luminance value of 1, and the other pixels have a luminance value of 0.

[0146] The required luminance distribution 355A from the display area block D6L indicates the backlight blocks to which required luminance values ​​are assigned and the required luminance values ​​expressed in 12-bit resolution (maximum value 4095). The required luminance values ​​are assigned to the backlight block B6L and its surrounding backlight blocks. Specifically, these are backlight blocks B2L, B3L, B1R, B5L, B6L, B4R, B8L, B9L, and B7R.

[0147] 29 shows the required luminance distribution from the second display region 250B facing the second backlight region 350B. In this example, only the display region block D1R facing the backlight block B1R includes the luminance to be emitted. In the display region block D1R, only one pixel has a maximum luminance value of 1, and the other pixels have a luminance value of 0.

[0148] The required luminance distribution 355B from the display area block D1R shows the backlight blocks to which the required luminance values ​​are assigned and the required luminance values ​​expressed in 12-bit resolution. The required luminance values ​​are assigned to the backlight block B1R and its surrounding backlight blocks. Specifically, these are the backlight blocks B3L, B1R, B2R, B6L, B4R, and B5R.

[0149] 30 shows the required brightness values ​​for the first display region 250A to the second backlight region 350B. The first display region 250A is composed of display region blocks D1L to D9L. The display region blocks D1L to D9L correspond to the backlight blocks B1L to B9L, respectively. The required brightness values ​​from the display region blocks D3L, D6L, and D9L adjacent to the second display region 250B are provided to the second backlight region 350B.

[0150] As explained with reference to Fig. 28, only display area block D6L includes pixels that emit light. Therefore, the brightness value required from display area block D3L to backlight blocks B1R and B4R is 0. Also, the brightness value required from display area block D9L to backlight blocks B4R and B7R is 0. The brightness values ​​required from display area block D6L to backlight blocks B1R, B4R, and B7R are 1147, 3399, and 2252, respectively.

[0151] 31 shows the brightness values ​​required from the second display region 250B to the first backlight region 350A. The second display region 250B is composed of display region blocks D1R to D9R. The display region blocks D1R to D9R correspond to the backlight blocks B1R to B9R, respectively. The brightness values ​​required from the display region blocks D3L, D6L, and D9L adjacent to the first display region 250A are provided to the second backlight region 350B.

[0152] As explained with reference to Fig. 29, only the display area block D1R includes pixels that emit light. Therefore, the required luminance value from the display area block D4R to the backlight blocks B3L, B6L, and B9L is 0. Also, the required luminance value from the display area block D7R to the backlight blocks B6L and B9L is 0. The required luminance values ​​from the display area block D1R to the backlight blocks B3L and B6L are 2048 and 1351, respectively.

[0153] 32 shows the final brightness distribution of the backlight blocks. The video signal processing circuits 12A and 12B determine the brightness value of each backlight block to a value corresponding to the maximum required brightness value. In the first backlight region 350A, the backlight block B3L has a brightness value corresponding to the required brightness value from the adjacent second display region 250B. In the second backlight region 350B, the backlight blocks B4R and B7R have brightness values ​​corresponding to the required brightness value from the adjacent first display region 250A.

[0154] In this way, by obtaining information on the required brightness value of the display block from the other video signal processing circuit, the video signal processing circuit can more appropriately control the brightness value of the backlight block to be controlled, thereby suppressing brightness changes at the boundary between the two display areas.

[0155] 33 shows an example of data communicated between video signal processing circuits 12A and 12B. Video signal processing circuit 12A uses clock signal SCK1 and control signal CS1 to transmit data signal SDA1 indicating a required luminance value to video signal processing circuit 12B. Video signal processing circuit 12B uses clock signal SCK2 and control signal CS2 to transmit data signal SDA2 indicating the required luminance value to video signal processing circuit 12A. Note that some signal lines may be shared between video signal processing circuits 12A and 12B to reduce the number of signal transmission lines.

[0156] Figure 34 shows example waveforms of the clock signal SCK, data signal SDA, and control signal CS. The data signal SDA indicates the address of the original display block backlight block that provides the requested brightness value, and the requested brightness value. In the example of Figure 34, the address is 6, the requested brightness value is 3399, and they are transmitted in 16 bits. The video signal processing circuit may, for example, sequentially transmit the address of the requesting display area block and two or three requested brightness values.

[0157] In the above example, the display area and backlight area are divided into two, and two video signal processing circuits control each of the divided areas. In another example, the number of divisions of the display area and backlight area and the number of video signal processing circuits may be three or more. Information on required brightness values ​​is communicated between the video signal processing circuits controlling adjacent display areas and backlight areas.

[0158] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. Those skilled in the art can easily modify, add, or convert each element of the above embodiments within the scope of the present disclosure. It is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. [Explanation of symbols]

[0159] 1 liquid crystal display device, 12 video signal processing circuit, 20 liquid crystal display panel, 30 backlight, 200 backlight brightness control unit, 250A, 250B display area, 350A, 350B backlight area, 401 backlight block, 451, D1L-D9L, D1R-D9R display area block, 471 internal display area block, B1-B9, B1L-B9L, B1R-B9R backlight block, IB1-IB9 internal backlight block

Claims

1. 1. A method for controlling a backlight in a display device including a display panel and a backlight, comprising: the backlight includes a plurality of backlight blocks; the display panel includes display area blocks facing the plurality of backlight blocks, The method includes, for each of the plurality of backlight blocks: determining a required luminance value from each of the plurality of pixels to the backlight block based on a weight determined from a relationship between a position of each of the plurality of pixels in a plurality of display area blocks including a display area block facing the backlight block and an adjacent display area block of the facing display area block, and a position of the backlight block, and based on the luminance of each of the plurality of pixels; determining a maximum value of the requested luminance values ​​for the backlight block as the luminance value of the backlight block; the display area block includes a first display area block and a plurality of second display area blocks surrounding the first display area block and adjacent to the first display area block; In each of the plurality of second display area blocks, a weight for a pixel adjacent to the first display area block is the same as a weight for a pixel in the first display area block. method.

2. 10. The method of claim 1, The weight may be expressed as a decreasing function of the distance between the pixel and the backlight block. method.

3. 10. The method of claim 1, the plurality of display area blocks includes all display area blocks that share a boundary line with the opposing display area block; method.

4. 4. The method of claim 3, The plurality of backlight blocks are arranged in a matrix, the plurality of display area blocks include a display area block adjacent to the opposing display area block in the row direction, the column direction, and the diagonal direction; method.

5. 10. The method of claim 1, The method comprises: determining a maximum value of requested luminance values ​​for the backlight block of all pixels in the plurality of display area blocks including the opposing display area block and the adjacent display area block of the opposing display area block as a luminance value of the backlight block; method.

6. 10. The method of claim 1, For each of the display area blocks, determining a required luminance value from the display area block for each of a backlight block facing the display area block and a backlight block adjacent to the facing backlight block; a required luminance value from the display area block to the opposite backlight block is determined from a maximum luminance value of pixels in the display area block; a required luminance value for a backlight block different from the opposing backlight block is a maximum required luminance value determined by a weight according to a pixel position in the display area block and a luminance value of the pixel; The luminance value of each of the backlight blocks is the maximum required luminance value among the required luminance values ​​from each of the display area blocks. method.

7. A display device, A display panel; a backlight disposed on the rear side of the display panel and including a plurality of backlight blocks; a control device for controlling the luminance values ​​of the plurality of backlight blocks and the transmitted light of the light from the backlight through the display panel; Including, The control device, for each of the plurality of backlight blocks, determining a required luminance value from each of the plurality of pixels to the backlight block based on a weight determined from a relationship between a position of each of the plurality of pixels in a plurality of display area blocks including a display area block facing the backlight block and an adjacent display area block of the facing display area block, and a position of the backlight block, and based on the luminance of each of the plurality of pixels; determining a maximum value of the requested luminance values ​​for the backlight block as the luminance value of the backlight block; the display area block includes a first display area block and a plurality of second display area blocks surrounding the first display area block and adjacent to the first display area block; In each of the plurality of second display area blocks, a weight for a pixel adjacent to the first display area block is the same as a weight for a pixel in the first display area block. Display device.

8. The display device according to claim 7, The control device a first processing circuit that controls a first display area of ​​the display panel and a first backlight block group facing the first display area; a second processing circuit that controls a second display area of ​​the display panel and a second backlight block group facing the second display area; Including, the first processing circuit acquires, from the second processing circuit, required luminance values ​​from the display area blocks in the second display area, and controls the first backlight block group based on the acquired required luminance values ​​and the required luminance values ​​from the display area blocks in the first display area; the second processing circuit acquires, from the first processing circuit, required luminance values ​​from the display area blocks in the first display area, and controls the second backlight block group based on the acquired required luminance values ​​and the required luminance values ​​from the display area blocks in the second display area; The control of the first backlight block group and the control of the second backlight block group are each determining a required luminance value from each of the plurality of pixels to the backlight block based on a weight determined from a relationship between a position of each of the plurality of pixels in a plurality of display area blocks including a display area block facing the backlight block and an adjacent display area block of the facing display area block, and a position of the backlight block, and based on the luminance of each of the plurality of pixels; determining a maximum value of the requested luminance values ​​for the backlight block as the luminance value of the backlight block; each of the first display area and the second display area includes a first display area block and a plurality of second display area blocks that surround the first display area block and are adjacent to the first display area block; In the plurality of second display area blocks, weights for pixels adjacent to the first display area block are the same as weights for pixels of the first display area block. Display device.

Images