Display device and control method of backlight of display device

Abstract

To reduce consumption power and improve display quality of a display device by a simple configuration.SOLUTION: A display device determines a tentative luminance value of each of multiple backlight blocks on the basis of video data, determines a correction coefficient of a focused backlight block selected from multiple backlight blocks, determines a correction luminance value of the focused backlight block on the basis of a tentative luminance value and the correction coefficient of the focused backlight block, and controls the focused backlight block following the correction luminance value. A control device calculates statistical values of tentative luminance values of multiple reference backlight blocks including a backlight block adjacent to the focused backlight block, calculates a relative value of a statistical value for a tentative luminance value of the focused backlight block, and determines a correction coefficient of the focused backlight block on the basis of the relative value and a preset function.SELECTED DRAWING: Figure 3

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 also increases the difference in brightness between areas with low and high backlight emission, thereby increasing the contrast ratio within the same surface and improving display quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 8,207,953 [Patent Document 2] U.S. Patent No. 10,192,495 [Patent Document 3] U.S. Patent Application Publication No. 2009 / 0002308 Summary of the Invention [Problem to be solved by the invention]

[0006] Local dimming technology changes the light intensity of each block according to the video data. For example, one method stores the brightness distribution information when each block is lit individually, and determines the brightness of each block based on the video data and the brightness distribution of all blocks. This allows for good image quality.

[0007] However, this method requires a very large memory area to store the luminance distribution information for each block, and also requires a large circuit scale to calculate the light emission luminance for displaying the image for each block from the image data and luminance distribution information. [Means for solving the problem]

[0008] A display device according to one aspect of the present disclosure includes a backlight including a plurality of backlight blocks, a display panel that performs display using light from the backlight, and a control device. The control device acquires video data, determines a provisional brightness value for each of the plurality of backlight blocks based on the video data, determines a correction coefficient for a target backlight block selected from the plurality of backlight blocks, determines a correction brightness value for the target backlight block based on the provisional brightness value of the target backlight block and the correction coefficient, and controls the target backlight block in accordance with the correction brightness value. In determining the correction coefficient for the target backlight block, the control device calculates a statistical value of provisional brightness values ​​of a plurality of reference backlight blocks including backlight blocks adjacent to the target backlight block, calculates a relative value of the statistical value with respect to the provisional brightness value of the target backlight block, and determines the correction coefficient for the target backlight block based on the relative value and a preset function.

[0009] One aspect of the present disclosure is a method for controlling the backlight of a display device, the method including: acquiring video data; determining a provisional brightness value for each of the plurality of backlight blocks based on the video data; determining a correction coefficient for a target backlight block selected from the plurality of backlight blocks; determining the correction brightness value for the target backlight block based on the provisional brightness value of the target backlight block and the correction coefficient; and controlling the target backlight block according to the correction brightness value. The determination of the correction coefficient for the target backlight block includes calculating a statistical value of provisional brightness values ​​of a plurality of reference backlight blocks, including backlight blocks adjacent to the target backlight block, calculating a relative value of the statistical value relative to the provisional brightness value of the target backlight block, and determining the correction coefficient for the target backlight block based on the relative value and a preset function. [Effects of the Invention]

[0010] According to one aspect of the present disclosure, it is possible to improve display quality and power consumption with a simple configuration. [Brief explanation of the drawings]

[0011] [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] 10 is a flowchart illustrating an example of a process for determining a correction luminance value for each backlight block for an input video frame. [Figure 4] 1 shows a backlight block of interest and its reference backlight block. [Figure 5] An example of a function for calculating the correction coefficient is shown below. [Figure 6A] 10 shows the provisional luminance value of the target backlight and the provisional luminance value of its reference backlight block. [Figure 6B]10 shows the provisional luminance value of the target backlight and the provisional luminance value of its reference backlight block. [Figure 6C] 10 shows the provisional luminance value of the target backlight and the provisional luminance value of its reference backlight block. [Figure 7A] 10 shows examples of real backlight blocks and virtual backlight blocks that constitute a backlight. [Figure 7B] 10 shows a method for determining a provisional luminance value of a virtual backlight block. [Figure 7C] 10 shows a method for determining a provisional luminance value of a virtual backlight block. [Figure 8] 10A and 10B are diagrams for explaining a method for determining a correction coefficient for a backlight block of interest. [Figure 9] 10A and 10B are diagrams for explaining an example of a method for determining a correction luminance value of a backlight block of interest. [Figure 10] Other examples of arrangement patterns of reference backlight blocks are shown. [Figure 11] Other examples of arrangement patterns of reference backlight blocks are shown. [Figure 12A] 1 shows the luminance distribution of a video frame, and the provisional luminance value distribution, multiplying factor value distribution, and corrected luminance value distribution of a backlight block obtained from the luminance distribution. [Figure 12B] 12B shows a graph of the directly above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution of FIG. 12A. [Figure 13A] 1 shows the luminance distribution of a video frame, and the provisional luminance value distribution, multiplying factor value distribution, and corrected luminance value distribution of a backlight block obtained from the luminance distribution. [Figure 13B] 13B shows a graph of the directly above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution of FIG. 13A. [Figure 14A] 1 shows the luminance distribution of a video frame, and the provisional luminance value distribution, multiplying factor value distribution, and corrected luminance value distribution of a backlight block obtained from the luminance distribution. [Figure 14B]14B shows a graph of the directly above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution of FIG. 14A. [Figure 15A] 1 shows the luminance distribution of a video frame, and the provisional luminance value distribution, multiplying factor value distribution, and corrected luminance value distribution of a backlight block obtained from the luminance distribution. [Figure 15B] 15B shows a graph of the directly above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution of FIG. 15A. [Figure 16A] 1 shows the luminance distribution of a video frame, and the provisional luminance value distribution, multiplying factor value distribution, and corrected luminance value distribution of a backlight block obtained from the luminance distribution. [Figure 16B] 16B shows a graph of the directly above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution of FIG. 16A. [Figure 17A] 1 shows the luminance distribution of a video frame, and the provisional luminance value distribution, multiplying factor value distribution, and corrected luminance value distribution of a backlight block obtained from the luminance distribution. [Figure 17B] 17B shows a graph of the directly above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution of FIG. 17A. [Figure 18] In one embodiment of this specification, the luminance distribution of a video frame, the provisional luminance value distribution of a backlight block obtained from the luminance distribution, the multiplying factor value distribution, and the corrected luminance value distribution are shown. [Figure 19] 10 shows a flowchart of an example of processing by a correction coefficient calculation unit. [Figure 20] 1 illustrates an example of the configuration of a display device according to an embodiment of the present specification. [Figure 21] 1 shows a schematic diagram of a backlight configuration. [Figure 22] 10 shows an example of information on provisional luminance values ​​transmitted and received between video signal processing circuits. [Figure 23] 10 shows an example of the relationship between a video frame and the corrected luminance value of the corresponding backlight block. [Figure 24] 10 shows an example of data communicated between video signal processing circuits. [Figure 25]10 shows examples of waveforms of a clock signal SCK, a data signal SDA, and a control signal CS. [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 an example of information on provisional luminance values ​​transmitted and received between video signal processing circuits. [Figure 29] 10 shows an example of information on provisional luminance values ​​transmitted and received between video signal processing circuits. [Figure 30] 10 shows an example of information on provisional luminance values ​​transmitted and received between video signal processing circuits. [Figure 31] 10 shows an example of information on provisional luminance values ​​transmitted and received between video signal processing circuits. [Figure 32] 10 shows an example of the relationship between a video frame and the corrected luminance value of the corresponding backlight block. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] A display device according to an embodiment of the present specification disclosed below includes a backlight including a plurality of backlight blocks and a display panel. The display device determines a provisional brightness value for each backlight block based on input video data. The display device corrects the provisional brightness value of a target backlight block based on a statistic of the provisional brightness value of the target backlight block and the provisional brightness values ​​of reference backlight blocks including backlight blocks adjacent to the target backlight block.

[0014] The luminance that can be seen or measured directly above (in front of) a backlight block of interest (direct luminance) depends on the emission luminance of the backlight of interest as well as on the leakage light from the backlight blocks surrounding the backlight block of interest. When the emission luminance of the backlight block of interest is constant, for example, when the surrounding backlight blocks are turned off, the direct luminance of the backlight block of interest decreases compared to when the surrounding backlight blocks are turned on.

[0015] By correcting the provisional luminance value of the target backlight block based on the statistical value of the provisional luminance value of the reference backlight block, the display quality and power consumption of the display device can be improved with a simple configuration.

[0016] In one embodiment of the present specification, the display device compares the provisional brightness value of the target backlight block with the statistical value of the provisional brightness values ​​of the reference backlight block, and determines the correction coefficient based on the comparison result and a preset function. In one embodiment of the present specification, the comparison result is a value obtained by dividing the statistical value of the provisional brightness values ​​of the reference backlight block by the provisional brightness value of the target backlight block.

[0017] The reference backlight blocks may include virtual backlight blocks in addition to real backlight blocks within the backlight. For example, a backlight block of interest located at the edge of the backlight has no adjacent backlight blocks outside the backlight.

[0018] In one embodiment of the present specification, the display device defines a virtual backlight block outside the backlight as a reference backlight block for the target backlight block. The provisional luminance value of the virtual backlight block may be determined based on the provisional luminance values ​​of one or more actual backlight blocks. The virtual backlight block allows for correction of the luminance value of the backlight block with a simpler configuration.

[0019] The display device inputs the calculated value into a preset function to calculate a correction coefficient for correcting the provisional brightness value of the backlight block of interest. In one embodiment of the present specification, the correction coefficient is a correction multiplying factor. The display device calculates the product of the correction multiplying factor and the provisional brightness value of the backlight block of interest to determine the corrected brightness value of the backlight block of interest.

[0020] The backlight block of interest is controlled according to the correction luminance value. The provisional luminance value and the correction luminance value are, for example, relative luminance values, and are proportional to the actual luminance value of the backlight block. For example, the relative luminance value is normalized so that the maximum value is 1 and the minimum value is 0. The actual maximum light emission luminance value of the backlight block may differ between backlight blocks. When the correction luminance values ​​of different backlight blocks are the same, the light emission luminance values ​​(luminance values ​​of visible light) of those backlight blocks may be the same or different. Display devices according to embodiments of the present specification will be described in detail below.

[0021] First Embodiment 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, and a scan driver 22. The liquid crystal display device 1 further includes 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, and the scan driver 22 are included in a control device that controls the liquid crystal display panel 20.

[0022] The liquid crystal display device 1 displays images according to video data input from an external device. The video data includes video frames that are displayed sequentially. The liquid crystal display panel 20 is disposed in front of (on the viewing side of) the backlight 30, and displays the sequentially input video frames (images) by controlling the amount of transmitted light from the backlight 30.

[0023] The power supply generating circuit 11 includes, for example, a DC-DC converter, and generates power for operating other circuits and supplies the power to them. The video signal processing circuit 12 performs processes 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 generating circuit 11. The video signal supply source 14 supplies video signals to the video signal processing circuit 12 in accordance with video data from an external device.

[0024] 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.

[0025] 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.

[0026] The video signal processing circuit 12 uses the power supplied from the power generation circuit 11 to perform data array conversion for transmitting an externally input video signal to the display driver 21, and to generate and transmit timing signals for the drivers 21 and 22 to operate.

[0027] The video signal processing circuit 12 further generates drive control signals for driving and controlling the multiple backlight blocks included in the backlight 30, and transmits them to the backlight drive board 31. The backlight blocks are sometimes simply called blocks. Examples of drive control signals include a backlight ON / OFF control signal and a dimming signal. The dimming signal is a PWM (Pulse Width Modulation) signal for time-division control of the lighting time of the light source, and a signal for controlling the amount of current flowing through the light source.

[0028] 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.

[0029] The liquid crystal display device 1 employs local dimming technology. In the configuration example shown in Fig. 1, the backlight 30 is divided into X blocks (regions) along the X axis and into Y blocks along the Y axis. That is, each backlight block is rectangular, and the backlight blocks are arranged in a matrix.

[0030] The backlight 30 is composed of a plurality of backlight block rows, each of which is made up of backlight blocks arranged in the X-axis direction (row direction). In one example, the number of backlight blocks in all of the backlight block rows is the same. However, these do not have to be the same. In another aspect, the backlight is composed of a plurality of backlight block columns, each of which is made up of backlight blocks arranged in the Y-axis direction (column direction). The number of backlight blocks in all of the backlight block columns is the same. Although the explanation is given assuming the number of backlight blocks to be the same, the number of backlight blocks does not have to be the same. However, the backlight blocks may be arranged in other layouts.

[0031] The liquid crystal display device 1 can individually control the brightness value (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 pixels in the video frame.

[0032] The backlight 30 is, for example, a direct-type backlight, and 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 blocks. The number of LEDs in one block is arbitrary. An optimal number of LEDs are arranged in optimal positions based on the luminance efficiency and luminance distribution of the LEDs.

[0033] 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 light-emitting region of the backlight 30 may be configured, for example, of blocks arranged in a matrix, or may be configured of blocks arranged in a horizontal or vertical row.

[0034] 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 of the backlight 30, such as LEDs, 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.

[0035] 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.

[0036] 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 a provisional brightness value for each block of the backlight 30 based on the analysis results of the video frame.

[0037] Furthermore, the video signal processing circuit 12 determines a correction luminance value for each backlight block based on the provisional luminance value of the backlight block. The video signal processing circuit 12 determines the correction luminance value for each block as the luminance value for controlling the light emission of each backlight block.

[0038] In the example described below, the provisional brightness value is normalized to a maximum value of 1 and a minimum value of 0. Furthermore, there are cases where the calculation results in a correction brightness value exceeding 1. In this case, the correction brightness value is normalized to a maximum value of 1 and a minimum value of 0, and the provisional brightness value is corrected in advance to the corresponding relative value. For example, the maximum multiplying factor of the correction brightness value is known in advance, and if this is 2, it will be multiplied by 2 to make the correction brightness value 1, so the maximum value of the provisional brightness value can be set in advance to 0.5.

[0039] The video signal processing circuit 12 generates a drive control signal corresponding to the correction brightness value and outputs it to each backlight block. The relationship between the correction brightness value and the drive control signal is preset for each backlight block. The drive control signal represents the actual light emission brightness of each backlight block. In one example, the drive control signal indicates the duty ratio of the pulse width of PWM (Pulse Width Modulation) for power control. As described above, the light emission brightness of a backlight block for the same correction brightness value can be set for each backlight block.

[0040] The luminance directly above a backlight block depends on the light emission luminance of the backlight block as well as on the light leakage from surrounding backlight blocks. By determining the correction luminance value of the backlight block based on the provisional luminance value of the backlight block and the provisional luminance values ​​of the reference backlight blocks surrounding the backlight block, high display quality can be achieved.

[0041] 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 gradation-to-luminance conversion unit 201, a block provisional luminance value calculation unit 202, a block provisional luminance value arrangement unit 203, a backlight luminance control unit 210, and a backlight drive control signal generation unit 221. The backlight luminance control unit 210 includes a reference block luminance determination unit 211, a correction coefficient calculation unit 213, and a correction luminance value calculation unit 214.

[0042] The display control drive signal generation unit 231 generates signals to be transmitted 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 transmits signals of RGB gradation levels of each pixel indicated by the video frame together with timing signals to the display drive driver 21, and transmits the timing signals to the scan driver 22.

[0043] The gradation-to-luminance converter 201, block provisional luminance value calculator 202, and block provisional luminance value array unit 203 are circuits for determining provisional luminance values ​​(provisional lighting levels) for each block of the backlight 30 based on a video frame. Specifically, the gradation-to-luminance converter 201 converts the gradation levels of pixels indicated by the video frame into relative luminance values. The luminance value of a pixel is, for example, the maximum luminance value of the red, blue, and green elements (also called sub-pixels) that make up the pixel.

[0044] The block provisional luminance value calculation unit 202 determines a provisional luminance value for each block of the backlight 30 based on the luminance values ​​of the pixels in the video frame. For example, the block provisional luminance value calculation unit 202 sets the luminance value of the block to a luminance value determined from the maximum luminance value of the pixels in a portion of the display area opposite the block (also called a display area block). Each backlight block is associated with the opposite display area block.

[0045] In the following, the luminance value of a pixel and the luminance value of a block are each normalized relative luminance values ​​ranging from 0 to 1. The block provisional luminance value calculation unit 202 determines the maximum luminance value of the pixels in the corresponding display area block as the provisional luminance value of the backlight block. When different backlight blocks have the same provisional luminance value, even though the signals are the same, their actual luminance values ​​may be the same or may differ depending on individual differences between blocks and LEDs, the locations of the blocks, etc.

[0046] The block provisional brightness value array unit 203 generates an array of provisional brightness values ​​for each block calculated by the block provisional brightness value calculation unit 202. The array associates the blocks of the backlight 30 with their provisional brightness values. The block provisional brightness value array unit 203 transmits the generated array of provisional brightness values ​​to the backlight brightness control unit 210.

[0047] The backlight luminance control unit 210 corrects each of the received provisional luminance values ​​to determine a corrected luminance value for each backlight block. The backlight luminance control unit 210 determines a correction coefficient from the provisional luminance value for each backlight block based on the provisional luminance value array. The correction method will be described in detail later.

[0048] The backlight drive control signal generation unit 221 acquires the determined correction luminance value for each backlight block from the backlight luminance control unit 210 and generates a drive control signal according to each correction luminance value. The backlight drive control signal generation unit 221 generates a drive control signal for a specified luminance value according to, for example, the physical characteristics of the light source included in each backlight block. The backlight drive control signal generation unit 221 transmits the drive control signal for each block to the backlight drive board 31.

[0049] An example of a method for correcting the luminance value of each block of the backlight 30 by the backlight luminance control unit 210 is described below. The backlight luminance control unit 210 determines the amount of correction from each provisional luminance value determined according to the video frame, based on each provisional luminance value. The backlight luminance control unit 210 corrects each provisional luminance value by the correction amount. This makes it possible to improve display quality while reducing power consumption due to local dimming.

[0050] In one embodiment of this specification, the backlight brightness control unit 210 determines the correction brightness value of a target backlight block based on the provisional brightness value of the target backlight block and the provisional brightness value of a reference backlight block of an arrangement pattern that is preset for the target backlight block.

[0051] In the example described below, the backlight luminance control unit 210 corrects the provisional luminance value of the backlight block of interest according to the relative value (comparison value) of the provisional luminance value of the reference backlight block relative to the provisional luminance value of the backlight block of interest. The smaller the provisional luminance value of the reference backlight block, the greater the provisional luminance value of the backlight block of interest is increased. This allows the luminance directly above each backlight block to approach a desired value according to the provisional luminance value pattern of the backlight block.

[0052] The arrangement pattern of the reference backlight block depends on the design, and various examples can be used. The reference backlight block is composed of the backlight blocks surrounding the backlight block of interest. Some examples are described below. In one example, the reference backlight block is composed of all backlight blocks adjacent to the backlight block of interest.

[0053] An adjacent backlight block to a backlight block of interest is a backlight block whose side or corner is in contact with the backlight block of interest. As will be described below, in an example in which rectangular backlight blocks are arranged in a matrix, adjacent backlight blocks are backlight blocks that surround the backlight block of interest. If the backlight block of interest is located at the center of the backlight 30, the backlight block of interest is surrounded by eight adjacent backlight blocks.

[0054] When a backlight block of interest is located at the edge of the backlight 30, actual adjacent backlight blocks exist only inside the backlight 30. The reference block of a backlight block of interest located at the edge may consist of only adjacent actual backlight blocks, or may include adjacent virtual backlight blocks, as will be described later.

[0055] If the reference backlight block is composed of only real backlight blocks, the number of reference backlight blocks of the backlight block of interest located at the edge is less than 8. If the reference backlight block includes a virtual backlight block, the number of reference backlight blocks of all backlight blocks of interest is 8.

[0056] The reference backlight block may be composed of some of the adjacent backlight blocks. For example, the reference backlight block may be composed of the actual backlight blocks adjacent to the target backlight block on the left, right, above, and below. The left and right adjacent backlight blocks are backlight blocks adjacent along the X axis, and the top and bottom adjacent backlight blocks are backlight blocks adjacent along the Y axis.

[0057] The reference backlight blocks of a backlight block of interest located at the edge of the backlight 30 may be composed of only real backlight blocks, or may be composed of real and virtual backlight blocks. If the reference backlight blocks include virtual backlight blocks, the reference backlight blocks of all backlight blocks of interest are composed of four adjacent backlight blocks. If no virtual backlight blocks are defined, the number of reference backlight blocks of a backlight block of interest located at the edge is less than four.

[0058] In another example, the reference backlight block may be composed of adjacent backlight blocks and backlight blocks adjacent to the adjacent backlight blocks on the outside. In the example of the matrix layout, the central backlight block of interest is surrounded by 24 actual reference backlight blocks. The handling of virtual light blocks for a backlight block of interest located near the edge of the backlight 30 is similar to the other examples above.

[0059] In one embodiment of the present specification, the backlight luminance control unit 210 compares the statistical value of the provisional luminance values ​​of the reference backlight block with the provisional luminance value of the backlight block of interest, and corrects the provisional luminance value of the backlight block of interest based on the comparison result (relative value). The statistical value may be, for example, a median value in addition to an average value such as a simple average or a weighted average.

[0060] In one embodiment of the present specification, the backlight luminance control unit 210 may use division to compare the provisional luminance value of the target backlight block with the provisional luminance value of the reference backlight block. For example, the backlight luminance control unit 210 calculates the relative value of the provisional luminance value of the target backlight block by dividing the statistical value of the provisional luminance value of the reference backlight block by the provisional luminance value of the target backlight block. Subtraction may be used instead of division.

[0061] 3 is a flowchart showing an example of a process for determining a correction luminance value for each backlight block for an input video frame. The reference block luminance determination unit 211 selects an unselected backlight block of interest from the backlight 30 (S11). The reference block luminance determination unit 211 refers to information on the backlight block provisional luminance values ​​acquired from the block provisional luminance value arrangement unit 203, and determines the provisional luminance value of the reference backlight block for the selected backlight block of interest (S12).

[0062] The correction coefficient calculation unit 213 acquires the provisional luminance values ​​of the reference backlight blocks from the reference block luminance determination unit 211 and determines their statistical values ​​(S13). The statistical values ​​may be, for example, simple average values, weighted average values, or median values. The correction coefficient calculation unit 213 compares the calculated statistical values ​​with the provisional luminance values ​​of the backlight blocks of interest and determines the relative values ​​of the statistical values ​​with respect to the provisional luminance values ​​of the backlight blocks of interest (S14). An example of the relative value is the value obtained by dividing the statistical values ​​by the provisional luminance values ​​of the backlight blocks of interest.

[0063] The correction coefficient calculation unit 213 determines a correction coefficient based on the calculated relative value and a preset function (S15). The function is expressed by, for example, an arithmetic expression or a look-up table. An example of the correction coefficient is a multiplication factor for the provisional luminance value of the backlight block of interest.

[0064] The correction luminance value calculation unit 214 corrects the provisional luminance value of the backlight block of interest using the calculated correction coefficient to determine the correction luminance value (S16). A drive control signal corresponding to this correction luminance value is transmitted to the backlight drive board 31 to cause the backlight block of interest to emit light.

[0065] The reference block luminance determination unit 211 determines whether all backlight blocks of the backlight 30 have been selected (S17). If there are unselected backlight blocks (S17: NO), the flow returns to step S11. If all backlight blocks have been selected (S17: YES), the process of calculating the corrected luminance values ​​of the backlight blocks for the current video frame ends.

[0066] An example of a method for correcting the provisional brightness value of a target backlight block will be described below. In the example described below, the real backlight blocks are assumed to be rectangular and arranged in a matrix. The virtual backlight blocks are assumed to have the same shape as the real backlight blocks. The reference backlight blocks are all real or virtual backlight blocks adjacent to the target backlight block. In other words, the number of reference backlight blocks is eight. In the following description, unless otherwise specified, the backlight block refers to the real backlight block.

[0067] First, while X and Y shown in FIG. 1 may each be any natural number, the following explanation will be given using an example in which X=3 and Y=3. First, a method for determining a correction luminance value for a backlight block of interest located at the center of the backlight 30 will be described. FIG. 4 shows a backlight block of interest and its reference backlight blocks. The backlight block of interest 300 is surrounded by eight reference backlight blocks 301 to 308. The reference backlight blocks 304 and 305 are adjacent to the backlight block of interest 300 on the left and right. The reference backlight blocks 302 and 307 are adjacent to the backlight block of interest 300 on the top and bottom. The reference backlight blocks 301, 303, 306, and 308 are diagonally adjacent to the backlight block of interest 300.

[0068] The reference block luminance determination unit 211 acquires information on the provisional luminance values ​​of all backlight blocks from the block provisional luminance value arrangement unit 203. The reference block luminance determination unit 211 refers to the information and determines provisional luminance values ​​LUMI_1 to LUMI_8 of the reference backlight blocks 301 to 308, respectively.

[0069] The correction coefficient calculation unit 213 calculates the statistical value of the provisional luminance values ​​of the reference backlight blocks 301 to 308. In this example, the simple average value AVE_ADJ is calculated as expressed by the following formula. AVE_ADJ=(LUMI_1+LUMI_2+LUMI_3+LUMI_4 +LUMI_5+LUMI_6+LUMI_7+LUMI_8) / 8

[0070] Next, the correction coefficient calculation unit 213 compares the provisional luminance value LUMI_SELF of the backlight block of interest 300 with the statistical value AVE_ADJ of the provisional luminance values ​​of the reference backlight block, and calculates the relative value LUMI_COEF of the statistical value AVE_ADJ relative to the provisional luminance value LUMI_SELF of the backlight block of interest 300.

[0071] Here, as shown in the following formula, the statistical value AVE_ADJ of the provisional luminance values ​​of the reference backlight block is divided by the provisional luminance value LUMI_SELF of the backlight block 300 of interest. LUMI_COEF=AVE_ADJ / LUMI_SELF

[0072] Here, the maximum value of LUMI_COEF is defined as 1. In other words, if the value of AVE_ADJ / LUMI_SELF is greater than 1, the value of LUMI_COEF is determined to be 1. Furthermore, if LUMI_SELF is 0, LUMI_COEF is determined to be 1.

[0073] The correction coefficient calculation unit 213 determines a correction coefficient for the provisional luminance value LUMI_SELF of the backlight block of interest 300 from the relative value LUMI_COEF. The correction coefficient calculation unit 213 calculates the correction coefficient from the relative value LUMI_COEF using information of a preset function. The function may be expressed, for example, by a mathematical formula or a look-up table. For example, the correction coefficient MULT_COEF is calculated by a linear function. MULT_COEF=A-(A-1)*LUMI_COEF

[0074] The constant A is a constant that indicates the maximum value of the correction coefficient. As described above, the maximum value of the relative value LUMI_COEF is 1. Therefore, the minimum value of the correction coefficient MULT_COEF calculated by the above formula is 1. The function for calculating the correction coefficient is not limited to a linear function. For example, a quadratic function or a higher-order function can be used.

[0075] 5 shows an example of a function for calculating a correction coefficient. In the graph, line 401 shows an example of a linear function, and line 402 shows an example of a quadratic function. The function for calculating a correction coefficient may be a higher-order function than a linear function. The higher-order function may be expressed, for example, as follows: MULT_COEF=1+(A-1)*(ABS(LUMI_COEF-1))^n ABS() represents the absolute value. n is a natural number greater than or equal to 2. For quadratic functions, n=2.

[0076] Line 401 represents a linear function in the above formula where the constant A is set to 2. In both functions 401 and 402, the maximum value of the correction coefficient MULT_COEF is 2 and the minimum value is 1. As shown in FIG. 5, the value of the correction coefficient MULT_COEF obtained by the quadratic function 402 is equal to or less than the value of the correction coefficient MULT_COEF obtained by the linear function 401. A quadratic function can reduce power consumption more than a linear function.

[0077] Next, the correction brightness value calculation unit 214 corrects the provisional brightness value LUMI_SELF of the backlight block of interest using the calculated correction coefficient MULT_COEF. Here, the correction coefficient MULT_COEF is used as a multiplying factor for correcting the provisional brightness value LUMI_SELF. That is, the correction brightness value calculation unit 214 multiplies the provisional brightness value LUMI_SELF by the correction coefficient MULT_COEF to calculate the correction brightness value of the backlight block of interest.

[0078] In the above example, if the statistical value of the provisional luminance value of the reference backlight block is equal to or greater than the provisional luminance value of the target backlight block, the relative value LUMI_COEF is 1. In this case, the correction coefficient is 1, and the correction amount of the provisional luminance value of the target backlight block is 0. In other words, the provisional luminance value of the target backlight block is maintained.

[0079] If the statistical value of the provisional brightness values ​​of the reference backlight block is smaller than the provisional brightness value of the target backlight block, the correction coefficient is greater than 1. Furthermore, the smaller the statistical value of the provisional brightness values ​​of the reference backlight block, the larger the correction coefficient. Thus, the smaller the amount of light leakage from the reference backlight block, the greater the increase in the provisional brightness value of the target backlight block. This allows the brightness value of the target backlight block to be appropriately determined according to the amount of light leakage from the reference backlight block.

[0080] A specific example of correcting the provisional luminance value of the backlight block of interest using the linear function 401 shown in Fig. 5 will be described below. An example of correcting the provisional luminance value LUMI_SELF of the backlight block of interest 300 shown in Fig. 4 will be described.

[0081] 6A shows the provisional brightness value of the backlight block of interest 300 and the provisional brightness values ​​of its reference backlight blocks 301 to 308. In the example of FIG. 6A, the provisional brightness values ​​of the backlight block of interest 300 and the reference backlight blocks 301 to 308 are 1.

[0082] The simple average value AVE_ADJ of the provisional luminance values ​​of the reference backlight blocks 301 to 308 is 8 / 8=1. The relative value LUMI_COEF of the provisional luminance statistical value of the reference backlight block with respect to the provisional luminance value of the backlight block of interest 300 is 1 / 1=1. Therefore, the correction coefficient (multiplying factor) MULT_COEF is (2-(2-1)*1)=1.

[0083] 6B shows the provisional brightness value of the backlight block of interest 300 and the provisional brightness values ​​of its reference backlight blocks 301 to 308. In the example of FIG. 6B, the provisional brightness value of the backlight block of interest 300 is 1, and the provisional brightness values ​​of the reference backlight blocks 301 to 308 are 0.

[0084] The simple average value AVE_ADJ of the provisional luminance values ​​of the reference backlight blocks 301 to 308 is 0 / 8 = 0. The relative value LUMI_COEF of the provisional luminance statistical value of the reference backlight block, based on the provisional luminance value of the backlight block of interest 300, is 0 / 1 = 0. Therefore, the correction coefficient (multiplying factor) MULT_COEF is (2-(2-1)*0) = 2.

[0085] Fig. 6C shows the provisional brightness value of the backlight block of interest 300 and the provisional brightness values ​​of its reference backlight blocks 301 to 308. In the example of Fig. 6C, the provisional brightness value of the backlight block of interest 300 is 1, and the provisional brightness values ​​of the reference backlight blocks 301 to 308 are the values ​​shown in Fig. 6C.

[0086] The simple average value AVE_ADJ of the provisional luminance values ​​of the reference backlight blocks 301 to 308 is 1.25 / 8=0.15625. The relative value LUMI_COEF of the provisional luminance statistical value of the reference backlight block, based on the provisional luminance value of the backlight block of interest 300, is 0.15625 / 1=0.15625. Therefore, the correction coefficient (multiplying factor) MULT_COEF is (2-(2-1)*0.15625)=1.84375.

[0087] Next, a method for correcting the provisional brightness value of a backlight block of interest located at the edge of the backlight 30 will be described. In the example described below, a virtual backlight block is defined, and a reference backlight block is composed of an actual backlight block and a virtual backlight block. By defining the virtual backlight block, the provisional brightness values ​​of all actual backlight blocks can be corrected using a common calculation method. In other words, the provisional brightness values ​​can be corrected using a common calculation circuit or calculation code.

[0088] The reference backlight blocks are eight backlight blocks adjacent to the target backlight block, as in the example described with reference to Fig. 4. Some of the eight backlight blocks are real backlight blocks, and the other are virtual backlight blocks. Note that the provisional luminance values ​​of backlight blocks located at the edges may be corrected based on the provisional luminance values ​​of fewer than eight real backlight blocks. In this case, the calculation method of the correction coefficient is set according to the position of the backlight block.

[0089] 7A shows an example of real backlight blocks and virtual backlight blocks that make up the backlight 30. The backlight 30 is made up of real backlight blocks 451 to 459. Virtual backlight blocks 471 to 486 are defined around the real backlight blocks 451 to 459.

[0090] 7A, the provisional brightness value of actual backlight block 455 is 1.0, and the provisional brightness values ​​of the other actual backlight blocks are 0.0. The provisional brightness values ​​of virtual backlight blocks 471 to 486 have not yet been determined.

[0091] The reference block luminance determination unit 211 determines the provisional luminance values ​​of the virtual backlight blocks 471 to 486 based on the provisional luminance values ​​of the actual backlight blocks 451 to 459. In one embodiment of this specification, the provisional luminance value of a virtual backlight block is the same as the provisional luminance value of the actual backlight block closest to that virtual backlight block. This allows appropriate provisional luminance values ​​of the virtual backlight blocks to be determined.

[0092] 7B shows a method for determining the provisional brightness values ​​of virtual backlight blocks 476 to 481. Reference block brightness determination unit 211 determines the provisional brightness value of virtual backlight block 476 as the provisional brightness value of adjacent actual backlight block 451 on the right side thereof. Similarly, the provisional brightness values ​​of virtual backlight blocks 478 and 480 are determined as the provisional brightness values ​​of adjacent actual backlight blocks 454 and 457 on the right side thereof.

[0093] The reference block luminance determination unit 211 determines the provisional luminance value of the virtual backlight block 477 as the provisional luminance value of the adjacent actual backlight block 453 on the left side thereof. Similarly, the provisional luminance values ​​of the virtual backlight blocks 479 and 481 are determined as the provisional luminance values ​​of the adjacent actual backlight blocks 456 and 459 on the right side thereof.

[0094] 7C shows a method for determining the provisional brightness values ​​of virtual backlight blocks 471 to 475 and 482 to 486. The reference block brightness determination unit 211 determines the provisional brightness value of virtual backlight block 472 as the provisional brightness value of the adjacent actual backlight block 451 below it. Similarly, the provisional brightness values ​​of virtual backlight blocks 473 and 474 are determined as the provisional brightness values ​​of the adjacent actual backlight blocks 452 and 453 below them.

[0095] The provisional luminance values ​​of virtual backlight blocks 471 and 475 are determined as the provisional luminance values ​​of their adjacent virtual backlight blocks 476 and 477 below them. In other words, the provisional luminance values ​​of virtual backlight blocks 471 and 475 are determined as the provisional luminance values ​​of their nearest adjacent backlight blocks 451 and 453.

[0096] The reference block luminance determination unit 211 determines the provisional luminance value of the virtual backlight block 483 as the provisional luminance value of the adjacent actual backlight block 457 above it. Similarly, the provisional luminance values ​​of the virtual backlight blocks 484 and 485 are determined as the provisional luminance values ​​of the adjacent actual backlight blocks 458 and 459 above them.

[0097] The interim brightness values ​​of virtual backlight blocks 482 and 486 are determined as the interim brightness values ​​of their upper adjacent virtual backlight blocks 480 and 481. In other words, the interim brightness values ​​of virtual backlight blocks 482 and 486 are determined as the interim brightness values ​​of their nearest adjacent backlight blocks 457 and 459.

[0098] An example of determining the correction coefficient of a backlight block of interest located at the edge of the backlight 30 will be described. Fig. 8 is a diagram for explaining a method of determining the correction coefficient of a backlight block of interest 451. The backlight block of interest 451 is located at the upper right corner of the backlight 30.

[0099] The reference backlight blocks of the backlight block of interest 451 are made up of virtual backlight blocks 471 to 473, 476, and 478 and real backlight blocks 452, 454, and 455.

[0100] The provisional brightness value of the focused backlight block 451 is 0.0, and the provisional brightness value of the reference backlight block 455 is 1.0. The provisional brightness values ​​of the other reference backlight blocks are 0.0. The simple average value AVE_ADJ of the provisional brightness values ​​of the reference backlight blocks 471 to 473, 476, 452, 478, 454, and 455 is 1 / 8 = 0.125. Because the provisional brightness value of the focused backlight block 451 is 0.0, the relative value LUMI_COEF of the provisional brightness statistics of the reference backlight blocks is 1. Therefore, the correction coefficient (multiplying factor) MULT_COEF is (2-(2-1)*1) = 1.

[0101] <Second embodiment> In the following, an example of another method for determining the correction luminance value of the backlight block of interest will be described. In the example described below, the handling of the virtual backlight block for the backlight block located at the edge of the backlight may be the same as in the first embodiment.

[0102] 9 is a diagram illustrating an example of a method for determining a correction luminance value of a backlight block of interest. As in the example described with reference to FIG. 4, all adjacent backlight blocks of the backlight block of interest are referenced for correcting the provisional luminance value of the backlight block of interest.

[0103] In the example shown in Fig. 9, the statistical value of the reference backlight block is a weighted average value. Other points are similar to the example described with reference to Fig. 4. In this example, a smaller weight is assigned to the diagonally adjacent backlight blocks 301, 303, 306, and 308 compared to the adjacent backlight blocks 302, 304, 305, and 307 on the top, bottom, left, and right. By assigning a smaller weight to backlight blocks farther from the target backlight block, the amount of leaked light from each reference backlight block can be more appropriately referenced.

[0104] The weighting coefficient values ​​are appropriately set by design. The weights of adjacent backlight blocks 302, 304, 305, and 307 on the top, bottom, left, and right are the same, and the weights of diagonally adjacent backlight blocks 301, 303, 306, and 308 are the same.

[0105] The weighted average WAVE_ADJ can be calculated, for example, as shown in the following formula: WAVE_ADJ =(B(LUMI_1+LUMI_3+LUMI_6+LUMI_8) +C(LUMI_2+LUMI_4+LUMI_5+LUMI_7)) / 8

[0106] "B" and "C" are weighting coefficients, and are set to appropriate positive values ​​depending on the design. When the function shown in FIG. 5 is used, for example, the relationship (B+C)=2 holds. For example, B=1.25, C=0.75.

[0107] Fig. 10 shows an example of another arrangement pattern of the reference backlight block. Compared to the example shown in Fig. 4, the backlight block of interest and the backlight blocks diagonally adjacent to it are excluded from the reference backlight block. In other words, the reference backlight block is made up of the adjacent backlight blocks on the top, bottom, left, and right.

[0108] The method for calculating the correction coefficient from the provisional brightness value of the reference backlight block and the provisional brightness value of the backlight block of interest shown in Fig. 10 may be the same as the method described with reference to Fig. 4. That is, the average value of the provisional brightness values ​​of the reference backlight blocks 302, 304, 305, and 307 is calculated, and the correction coefficient is calculated from this average value and the provisional brightness value of the backlight block of interest 300 using a predetermined function.

[0109] Calculating the correction coefficient from the provisional luminance value of the reference backlight block shown in FIG. 10 is the same as setting the weighting coefficient of the diagonally adjacent backlight block to 0 in the example shown in FIG.

[0110] 11 shows another example of an arrangement pattern of reference backlight blocks. The reference backlight block in this example includes backlight blocks 511-518 adjacent to the backlight block 500 of interest, as well as backlight blocks 521-536 on the outer periphery. The outer backlight blocks 521-536 are adjacent to the backlight blocks 511-518 adjacent to the backlight block 500 of interest.

[0111] The calculation of the statistics of the reference backlight block includes the interim brightness values ​​of the outer backlight blocks 521-536 in addition to the interim brightness values ​​of the adjacent backlight blocks 511-518.

[0112] When the statistical value is a weighted average value, for example, the weights of the outer backlight blocks 521 to 536 are set to values ​​smaller than the weights of the adjacent backlight blocks 511 to 518. This is because the outer backlight blocks 521 to 536 are farther from the target backlight block 500 than the adjacent backlight blocks 511 to 518. This makes it possible to calculate a statistical value according to the amount of leaked light from the reference backlight block to the target backlight block.

[0113] The weighted average value can be calculated, for example, by the following formula: WAVE_ADJ2 =(D(LUMI_A1+LUMI_A2+LUMI_A3+LUMI_A4+ LUMI_A5+LUMI_A6+LUMI_A7+LUMI_A8) +E(LUMI_B1+LUMI_B2+LUMI_B3+LUMI_B4+ LUMI_B5+LUMI_B6+LUMI_B7+LUMI_B8+ LUMI_B9+LUMI_B10+LUMI_B11+ LUMI_B12+LUMI_B13+LUMI_B14+ LUMI_B15+LUMI_B16)) / 24

[0114] "D" and "E" are weighting coefficients, and are set to appropriate positive values ​​depending on the design. When the function shown in Fig. 5 is used, for example, the relationship (D+E)=2 holds.

[0115] 9, the weights of the four backlight blocks located at the corners of the adjacent backlight blocks 511 to 518 may be smaller than the weights of the other backlight blocks. The same applies to the outer backlight blocks 521 to 536. The calculation method of the relative value of the reference backlight block luminance statistical value with respect to the tentative luminance value of the backlight block of interest and the correction coefficient may be the same as in the first embodiment.

[0116] <Calculation example of direct luminance> The following describes an example of the directly above luminance value of each backlight block obtained by the correction luminance value determined according to the method of the first embodiment. As described below, the method according to the embodiment of this specification can obtain the desired directly above luminance value of each backlight block.

[0117] In the example described below, the reference backlight block is the eight backlight blocks adjacent to the target backlight block. The statistical value of the provisional brightness values ​​of the reference backlight block is a simple average value, and the relative value is a value obtained by dividing the simple average value of the provisional brightness values ​​of the reference backlight block by the provisional brightness value of the target backlight block. The correction coefficient is calculated using the linear function described with reference to FIG. 5 and is a multiplication factor of the provisional brightness value of the target backlight block.

[0118] 12A shows a luminance distribution 610 of a video frame, a provisional luminance value distribution 611 of a backlight block obtained from the luminance distribution 610, a multiplying factor value distribution 612, and a corrected luminance value distribution 613. Note that the terms "distribution" used here, such as "luminance distribution" and "provisional luminance value distribution," do not mean luminance gradient (luminance distribution) information within a backlight block when each backlight block is illuminated, but rather mean a collection of luminance values ​​of the backlight block (luminance value group).

[0119] In the video frame 610, one partial region has a relative luminance value of 1.0, while the surrounding regions have relative luminance values ​​of 0.0. The partial region faces only one central backlight block. Therefore, in the backlight block group, the provisional luminance value of the central backlight block is 1.00, while the provisional luminance values ​​of the other backlight blocks are 0.00. The multiplying factor values, which are the correction coefficients for each backlight block, are as shown in the multiplying factor value distribution 612. As a result, a corrected luminance value distribution 613 for the backlight blocks is obtained.

[0120] 12B shows a graph of the directly above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution 613. The horizontal axis of the graph represents the X-axis value at the center position on the Y-axis on the main surface of the backlight. The vertical axis represents the directly above luminance. A directly above luminance value of 1.0 represents the desired directly above luminance value.

[0121] 12A, the desired directly above luminance value of the central backlight block is 1.0, and the desired directly above luminance values ​​of the other backlight blocks are 0.0. Line 711 shows the directly above luminance value obtained by the backlight controlled according to the correction luminance value, and line 712 shows the directly above luminance value obtained by the backlight controlled according to the tentative luminance value. The backlight controlled according to the correction luminance value achieves a directly above luminance value that is closer to the desired directly above luminance value.

[0122] FIG. 13A shows a luminance distribution 620 of a video frame, a provisional luminance value distribution 621 of a backlight block obtained from the luminance distribution 620, a multiplying factor value distribution 622, and a corrected luminance value distribution 623.

[0123] In video frame 620, one partial region has a relative luminance value of 1.0, while the surrounding regions have relative luminance values ​​of 0.0. The partial region faces the four backlight blocks on the lower right. Therefore, in the backlight block group, the provisional luminance values ​​of the four backlight blocks on the lower right are 1.00, while the provisional luminance values ​​of the other backlight blocks are 0.00. The multiplying factor values, which are the correction coefficients for each backlight block, are as shown in multiplying factor value distribution 622. As a result, a corrected luminance value distribution 623 for the backlight blocks is obtained.

[0124] 13B shows a graph of the direct-above luminance distribution by a backlight block whose light emission is controlled according to the corrected luminance value distribution 623. Line 721 shows the direct-above luminance value by the backlight controlled according to the corrected luminance value, and line 722 shows the direct-above luminance value by the backlight controlled according to the provisional luminance value. The backlight controlled according to the corrected luminance value achieves a direct-above luminance value that is closer to the desired direct-above luminance value.

[0125] FIG. 14A shows a luminance distribution 630 of a video frame, a provisional luminance value distribution 631 of a backlight block obtained from the luminance distribution 630, a multiplying factor value distribution 632, and a corrected luminance value distribution 633.

[0126] In video frame 630, one partial region has a relative luminance value of 1.0, while the surrounding areas have relative luminance values ​​of 0.0. The partial region faces six backlight blocks on the right side. Therefore, in the backlight block group, the provisional luminance values ​​of the six backlight blocks on the right side are 1.00, while the provisional luminance values ​​of the other backlight blocks are 0.00. The multiplying factor values, which are the correction coefficients for each backlight block, are as shown in multiplying factor value distribution 632. As a result, a corrected luminance value distribution 633 for the backlight blocks is obtained.

[0127] 14B shows a graph of the direct-above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution 633. Line 731 shows the direct-above luminance value by the backlight controlled in accordance with the corrected luminance value, and line 732 shows the direct-above luminance value by the backlight controlled in accordance with the provisional luminance value. The backlight controlled in accordance with the corrected luminance value achieves a direct-above luminance value that is closer to the desired direct-above luminance value.

[0128] FIG. 15A shows a luminance distribution 640 of a video frame, a provisional luminance value distribution 641 of a backlight block obtained from the luminance distribution 640, a multiplying factor value distribution 642, and a corrected luminance value distribution 643.

[0129] In the video frame 640, one partial region has a relative luminance value of 1.0, and the relative luminance values ​​of its surrounding regions are 0.0. The partial region faces all nine backlight blocks. Therefore, the provisional luminance values ​​of all backlight blocks are 1.00. The multiplying factor values, which are the correction coefficients for each backlight block, are as shown in the multiplying factor value distribution 642. As a result, a corrected luminance value distribution 643 for the backlight blocks is obtained.

[0130] 15B shows a graph of the direct-above luminance distribution by a backlight block whose light emission is controlled according to the corrected luminance value distribution 643. Line 741 shows the direct-above luminance value by the backlight controlled according to the corrected luminance value, and line 742 shows the direct-above luminance value by the backlight controlled according to the provisional luminance value. The backlight controlled according to the corrected luminance value achieves the desired direct-above luminance value.

[0131] FIG. 16A shows a luminance distribution 650 of a video frame, a provisional luminance value distribution 651 of a backlight block obtained from the luminance distribution 650, a multiplying factor value distribution 652, and a corrected luminance value distribution 653.

[0132] In video frame 650, the relative luminance value of two intersecting lines is 1.0, and the relative luminance value of the surrounding areas is 0.0. The two lines face five backlight blocks, consisting of the backlight blocks at the four corners and the central backlight block. Therefore, in the backlight block group, the provisional luminance values ​​of these five backlight blocks are 1.00, and the provisional luminance values ​​of the other backlight blocks are 0.00. The multiplying factor values, which are the correction coefficients for each backlight block, are as shown in multiplying factor value distribution 652. As a result, corrected luminance value distribution 653 of the backlight blocks is obtained.

[0133] 16B shows a graph of the direct-above luminance distribution by a backlight block whose light emission is controlled in accordance with the corrected luminance value distribution 653. Line 751 shows the direct-above luminance value by the backlight controlled in accordance with the corrected luminance value, and line 752 shows the direct-above luminance value by the backlight controlled in accordance with the provisional luminance value. The backlight controlled in accordance with the corrected luminance value achieves a direct-above luminance value that is closer to the desired direct-above luminance value.

[0134] FIG. 17A shows a luminance distribution 660 of a video frame, a provisional luminance value distribution 661 of a backlight block obtained from the luminance distribution 660, a multiplying factor value distribution 662, and a corrected luminance value distribution 663.

[0135] In video frame 660, the relative brightness value of the rectangular frame near the periphery is 1.0, and the relative brightness value of the surrounding area is 0.0. The rectangular frame faces eight backlight blocks other than the central backlight block. Therefore, in the backlight block group, the provisional brightness values ​​of the eight backlight blocks are 1.00, and the provisional brightness values ​​of the other backlight blocks are 0.00. The multiplying factor values, which are the correction coefficients for each backlight block, are as shown in multiplying factor value distribution 662. As a result, corrected brightness value distribution 663 of the backlight blocks is obtained.

[0136] 17B shows a graph of the direct-above luminance distribution by a backlight block whose light emission is controlled according to the corrected luminance value distribution 663. Line 761 shows the direct-above luminance value by the backlight controlled according to the corrected luminance value, and line 762 shows the direct-above luminance value by the backlight controlled according to the provisional luminance value. The backlight controlled according to the corrected luminance value achieves a direct-above luminance value that is closer to the desired direct-above luminance value.

[0137] <Third embodiment> Another embodiment of the present specification will be described. The differences from the first embodiment will be mainly described below. When a predetermined condition is satisfied, the correction coefficient calculation unit 213 of this embodiment calculates the correction coefficient MULT_COEF by the following method. MULT_COEF=K+LUMI_SELF×(1-K) K is an arbitrary coefficient (0≦K<1)

[0138] The predetermined conditions are the following two. Condition 1: All surrounding blocks are 1 (AVE_ADJ=1) Condition 2: LUMI_SELF<1

[0139] When all the areas around the backlight block of interest are lit (condition 1) and the backlight block of interest is not lit at maximum brightness (condition 2), the backlight block of interest inevitably receives light leaking from the surrounding backlight blocks. This reduces the contrast ratio of the backlight block of interest relative to the surrounding backlight blocks. In this embodiment, under these conditions, the brightness of the backlight block of interest is reduced by the amount of light leaking from the surrounding backlight blocks. This reduces image quality degradation and also reduces the backlight power corresponding to the backlight block of interest.

[0140] 18 shows a luminance distribution 800 of a video frame, a provisional luminance value distribution 801 of a backlight block obtained from the luminance distribution 800, a multiplying factor value distribution 802, and a corrected luminance value distribution 803 in this embodiment. In the video frame 800, the relative luminance value of the central partial region is 0.5, and the relative luminance value of the surrounding regions is 1.0. Each partial region faces a different backlight block.

[0141] The provisional brightness value of the central backlight block is 0.5, and the provisional brightness values ​​of the other backlight blocks are 1.0. The multiplying factor values, which are the correction coefficients for each backlight block, are as shown in multiplying factor value distribution 802. As a result, a corrected brightness value distribution 803 of the backlight blocks is obtained.

[0142] The multiplying factor value (correction coefficient) is calculated as follows: The multiplying factor value of the central backlight block is calculated according to the following formula in this embodiment: K is a value equal to or greater than 0 and less than 1. MULT_COEF=K+LUMI_SELF×(1-K) The coefficient K is set to 0.8.

[0143] The multiplying factor values ​​of the surrounding backlight blocks are calculated according to the following formula in the first embodiment: MULT_COEF=A-(A-1)*LUMI_COEF The coefficient A is set to 2.

[0144] In the example shown in FIG. 18, the central backlight block of interest receives light leakage from the surrounding backlight blocks in a luminance distribution including actual light leakage. Therefore, a value greater than 0.5, which is the original target feature value, can be ensured. The target feature value can be obtained by setting the multiplying factor (correction coefficient) to a value less than 1. When determining the coefficient K for calculating the multiplying factor (correction coefficient), the amount of leakage from the surrounding backlight blocks is measured in advance, and the value of coefficient K can be determined so that the value exceeds the calculated value of the feature value of each backlight block. Note that correction coefficients less than 1 may be calculated using other methods. Correction coefficients less than 1 are determined based on the relationship between the statistical values ​​of the luminance of the backlight block of interest and the reference backlight block.

[0145] 10, in this embodiment, the backlight blocks diagonally adjacent to the backlight block of interest may be excluded from the reference backlight block. In other words, the reference backlight block may be composed of adjacent backlight blocks on the top, bottom, left, and right. The method of calculating the correction coefficient may be the same as the example shown in FIG. 18, except that a portion of the reference backlight block is excluded.

[0146] 19 shows a flowchart of an example of processing by the correction coefficient calculation unit 213. As described in the first embodiment, the correction coefficient calculation unit 213 calculates a statistical value AVE_ADJ of the provisional luminance values ​​of the reference backlight block (S31) and makes a determination on the value (S32). If AVE_ADJ is smaller than 1 (S32: AVE_ADJ<1), the correction coefficient calculation unit 213 calculates a relative value LUMI_COEF of the statistical value AVE_ADJ with respect to the provisional luminance value LUMI_SELF of the target backlight block 300 (S33), as described in the first embodiment. Furthermore, the correction coefficient calculation unit 213 calculates a correction coefficient MULT_COEF (S34), as described in the first embodiment.

[0147] If AVE_ADJ is 1 in step S32 (S32: AVE_ADJ=1), the correction coefficient calculation unit 213 determines whether the provisional luminance value LUMI_SELF of the backlight block 300 of interest is 1 (S35). If the provisional luminance value LUMI_SELF of the backlight block 300 of interest is 1, the flow proceeds to step S33. If the provisional luminance value LUMI_SELF of the backlight block 300 of interest is less than 1, the correction coefficient calculation unit 213 calculates the correction coefficient MULT_COEF using the method of the present embodiment (S36).

[0148] <Fourth embodiment> FIG. 20 shows an example of the configuration of a display device according to an embodiment of the present specification. Differences from the configuration example 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.

[0149] 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.

[0150] The display drive driver 21A generates a data signal from the video signal transmitted from the video signal processing circuit 12A and supplies it to the first display region 250A. The display drive driver 21B generates a data signal from the video signal transmitted from the video signal processing circuit 12B and supplies it to the second display region 250B. The video signal processing circuit 12A also transmits a timing signal to the display drive driver 21A, and the display drive driver 21A generates a data signal from the received video signal in accordance with the timing signal and supplies it to the first display region 250A. The video signal processing circuit 12B also transmits a timing signal to the display drive driver 21B, and the display drive driver 21B generates a data signal from the received video signal in accordance with the timing signal and supplies it to the second display region 250B.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] FIG. 21 schematically shows the configuration of the backlight 30. The backlight 30 is composed of a first backlight 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.

[0158] The first backlight area 350A is composed of 12 backlight blocks (first backlight block group) B1L to B12L. Here, the case of 12 backlight blocks will be described, but the number is not limited to 12 and may be N×M (N and M are natural numbers) blocks. The second backlight area 350B is composed of 12 backlight blocks (second backlight block group) B1R to B12R. Backlight blocks B3L, B6L, B9L, and B12L are adjacent to the second backlight area 350B. Backlight blocks B1R, B4R, B7R, and B10R are adjacent to the first backlight area 350A.

[0159] The video signal processing circuit 12A transmits information about the provisional brightness value of the first backlight region 350A to the video signal processing circuit 12B. The video signal processing circuit 12B determines a correction coefficient for the second backlight region 350B based on the provisional brightness value of the second backlight region 350B and the provisional brightness value of the first backlight region 350A received from the video signal processing circuit 12A.

[0160] The video signal processing circuit 12B transmits information about the provisional brightness value of the second backlight region 350B to the video signal processing circuit 12A. The video signal processing circuit 12A determines a correction coefficient for the first backlight region 350A based on the provisional brightness value of the first backlight region 350A and the provisional brightness value of the second backlight region 350B received from the video signal processing circuit 12B.

[0161] 22 shows an example of information on provisional brightness values ​​transmitted and received between the video signal processing circuits 12A and 12B. The video signal processing circuit 12A transmits information on provisional brightness values ​​of a backlight block group 351A adjacent to the second backlight region 350B in the first backlight region 350A to the video signal processing circuit 12B. The backlight block group 351A is made up of backlight blocks B3L, B6L, B9L, and B12L.

[0162] The video signal processing circuit 12B transmits information on the provisional brightness values ​​of the backlight block group 351B adjacent to the first backlight region 350A in the second backlight region 350B to the video signal processing circuit 12A. The backlight block group 351B is made up of backlight blocks B1R, B4R, B7R, and B10R.

[0163] In calculating the correction coefficients of the backlight block group 351A, the video signal processing circuit 12A refers to the information on the provisional brightness values ​​of the backlight block group 351B received from the video signal processing circuit 12B. Similarly, in calculating the correction coefficients of the backlight block group 351B, the video signal processing circuit 12B refers to the information on the provisional brightness values ​​of the backlight block group 351A received from the video signal processing circuit 12A. The method of determining the correction coefficients may be the same as that described in the first embodiment.

[0164] By transmitting and receiving provisional brightness values ​​of backlight blocks adjacent to backlight blocks controlled by other devices in the backlight blocks controlled by the video signal processing circuits 12A and 12B, it is possible to more appropriately determine the correction coefficients of the backlights located at the boundaries of the backlight area.

[0165] 23 shows an example of the relationship between video frames and the corrected luminance values ​​of the corresponding backlight blocks. In video frame 821, only the area facing one backlight block is white, and the other areas are black. Video signal processing circuit 12A controls only the first backlight area 350A, and video signal processing circuit 12B controls only the second backlight area 350B.

[0166] As described above, when the backlight block of interest is adjacent to the division boundary of the backlight 30, each video signal processing circuit transmits information on the provisional brightness value of the backlight block adjacent to the boundary to the other video signal processing circuit to complement it.

[0167] In Figure 23, only the area in the video frame corresponding to backlight block B4R is white, and the other areas are black. To determine the correction coefficient for backlight block B4R, video signal processing circuit 12B references the provisional luminance values ​​of backlight blocks B1R, B2R, B5R, B8R, and B7R in the second backlight area 350B as well as the provisional luminance values ​​of backlight blocks B3L, B6L, and B9L in the first backlight area 350A. The method for calculating the correction coefficient is, for example, as described in the first embodiment. This allows an appropriate correction luminance value of 2.0 to be obtained for backlight block B4R.

[0168] 24 shows an example of data communicated between the video signal processing circuits 12A and 12B. The video signal processing circuit 12A uses a clock signal SCK1 and a control signal CS1 to transmit a data signal SDA1 indicating a provisional luminance value to the video signal processing circuit 12B. The video signal processing circuit 12B uses a clock signal SCK2 and a control signal CS2 to transmit a data signal SDA2 indicating a provisional luminance value to the video signal processing circuit 12A. Note that some signal lines may be shared between the video signal processing circuits 12A and 12B to reduce the number of signal transmission lines.

[0169] Figure 25 shows an example of the waveforms of the clock signal SCK, the data signal SDA, and the control signal CS. The data signal SDA shows an example of transmitting data between four boundary backlight blocks. In the example of Figure 25, the provisional brightness of each of the four backlight blocks is transmitted in 16 bits, and the provisional brightness value is expressed with a 12-bit resolution.

[0170] 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 provisional brightness values ​​is communicated between the video signal processing circuits that control adjacent display areas and backlight areas.

[0171] <Fifth embodiment> Figure 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 Figure 1 will be mainly explained below. The liquid crystal display device 1 includes video signal supply sources 14A to 14D and display drivers 21A to 21D. The signal processing board 10 includes video signal processing circuits 12A to 12D. The video signal processing circuits 12A to 12D are first to fourth processing circuits, respectively.

[0172] The liquid crystal display panel 20 is divided into four display regions 250A to 250D. The video signal processing circuit 12A performs processing for displaying video in the first display region 250A. The video signal processing circuit 12B performs processing for displaying video in the second display region 250B. The video signal processing circuit 12C performs processing for displaying video in the third display region 250C. The video signal processing circuit 12D performs processing for displaying video in the fourth display region 250D.

[0173] Video signal supply source 14A supplies a video signal to video signal processing circuit 12A, and video signal supply source 14B supplies a video signal to video signal processing circuit 12B. Video signal supply source 14C supplies a video signal to video signal processing circuit 12C, and video signal supply source 14D supplies a video signal to video signal processing circuit 12D.

[0174] The display drive driver 21A generates a data signal from the video signal transmitted from the video signal processing circuit 12A and supplies it to the first display region 250A. The display drive driver 21B generates a data signal from the video signal transmitted from the video signal processing circuit 12B and supplies it to the second display region 250B. The display drive driver 21C generates a data signal from the video signal transmitted from the video signal processing circuit 12C and supplies it to the third display region 250C. The display drive driver 21D generates a data signal from the video signal transmitted from the video signal processing circuit 12D and supplies it to the fourth display region 250D.

[0175] 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.

[0176] 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.

[0177] The video signal processing circuit 12C uses power supplied from the power generation circuit 11 to convert data arrays for transmitting externally input video signals to the display driver 21C, and to generate and transmit timing signals for operating the drivers 21C and 22. The video signal processing circuit 12C further generates drive control signals for driving and controlling the backlight 30, and transmits them to the backlight drive board 31.

[0178] The video signal processing circuit 12D uses power supplied from the power generation circuit 11 to convert data arrays for transmitting externally input video signals to the display driver 21D, and to generate and transmit timing signals for operating the drivers 21D and 22. The video signal processing circuit 12D further generates drive control signals for driving and controlling the backlight 30, and transmits them to the backlight drive board 31.

[0179] 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 to 12D.

[0180] The video signal processing circuits 12A to 12D 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 of each block indicated by the drive control signal from the video signal processing circuits 12A to 12D.

[0181] 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.

[0182] The video signal processing circuit 12C generates timing signals for the display drive driver 21C 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 21C. The video signal processing circuit 12D generates timing signals for the display drive driver 21D 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 21D.

[0183] 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.

[0184] Video signal processing circuit 12C analyzes the video frame and, based on the analysis results, generates and transmits a drive control signal to backlight 30 that illuminates third display region 250C from behind. Video signal processing circuit 12D analyzes the video frame and, based on the analysis results, generates and transmits a drive control signal to backlight 30 that illuminates fourth display region 250D from behind.

[0185] 27 schematically shows the configuration of the backlight 30. The backlight 30 is made up of a first backlight area 350A on the upper left, a second backlight area 350B on the upper right, a third backlight area 350C on the lower left, and a fourth backlight area 350D on the lower right.

[0186] 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 back surface 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 back surface of the second display region 250B, and irradiates light onto the second display region 250B.

[0187] The third backlight region 350C is located directly below the third display region 250C. The third backlight region 350C faces the third display region 250C on the backside of the third display region 250C and irradiates light onto the third display region 250C. The fourth backlight region 350D is located directly below the fourth display region 250D. The fourth backlight region 350D faces the fourth display region 250D on the backside of the fourth display region 250D and irradiates light onto the fourth display region 250D.

[0188] The first backlight area 350A, the second backlight area 350B, the third backlight area 350C, and the fourth backlight area 350D are controlled by the video signal processing circuit 12A, the video signal processing circuit 12B, the video signal processing circuit 12C, and the video signal processing circuit 12D, respectively.

[0189] The first backlight area 350A is made up of 12 backlight blocks B1UL to B12UL. The second backlight area 350B is made up of 12 backlight blocks B1UR to B12UR. The third backlight area 350C is made up of 12 backlight blocks B1DL to B12DL. The fourth backlight area 350D is made up of 12 backlight blocks B1DR to B12DR. Here, the case of 12 backlight blocks will be described, but this is not limited to 12, and N×M blocks (N and M are natural numbers) may also be used. The number of blocks in the backlight area may be different.

[0190] The following describes the transmission and reception of brightness value information between video signal processing circuits. In the example described below, information on provisional brightness values ​​of boundary portions of adjacent backlight areas on the left and right is transmitted and received between video signal processing circuits and complemented. Next, information on provisional brightness values ​​of boundary portions of adjacent backlight areas on the top and bottom is transmitted and received between video signal processing circuits and complemented. Note that information on the boundary portions of the top and bottom backlight areas may be transmitted and received between video signal processing circuits first, and then information on the boundary portions of the left and right backlight areas may be transmitted and received between video signal processing circuits.

[0191] 28 to 31 show examples of information transmitted and received between video signal processing circuits. In the example described below, it is assumed that the provisional luminance value of the backlight block B10UR is 1.0 and the provisional luminance values ​​of the other backlight blocks are 0.0.

[0192] 28 shows an example of information on provisional brightness values ​​transmitted and received between the video signal processing circuits 12A and 12B. The video signal processing circuit 12A transmits information on provisional brightness values ​​of a backlight block group 351A adjacent to the second backlight region 350B in the first backlight region 350A to the video signal processing circuit 12B. The backlight block group 351A is made up of backlight blocks B3UL, B6UL, B9UL, and B12UL.

[0193] The video signal processing circuit 12B transmits information on the provisional brightness values ​​of the backlight block group 351B adjacent to the first backlight region 350A in the second backlight region 350B to the video signal processing circuit 12A. The backlight block group 351B is made up of backlight blocks B1UR, B4UR, B7UR, and B10UR.

[0194] 29 shows an example of information about provisional brightness values ​​transmitted and received between the video signal processing circuits 12C and 12D. The video signal processing circuit 12C transmits information about provisional brightness values ​​of a backlight block group 351C adjacent to the fourth backlight region 350D in the third backlight region 350C to the video signal processing circuit 12D. The backlight block group 351C is made up of backlight blocks B3DL, B6DL, B9DL, and B12DL.

[0195] The video signal processing circuit 12D transmits information on the provisional brightness values ​​of the backlight block group 351D adjacent to the third backlight region 350C in the fourth backlight region 350D to the video signal processing circuit 12C. The backlight block group 351D is made up of backlight blocks B1DR, B4DR, B7DR, and B10DR.

[0196] 30 shows an example of information on provisional brightness values ​​transmitted and received between the video signal processing circuits 12A and 12C. The video signal processing circuit 12A transmits information on provisional brightness values ​​of a backlight block group 352A that is adjacent to the third backlight region 350C or the backlight block group 351D in the first backlight region 350A and the backlight block group 351B to the video signal processing circuit 12C. The backlight block group 352A is made up of backlight blocks B10UL, B11UL, B12UL, and B10UR.

[0197] The video signal processing circuit 12C transmits information on the provisional brightness values ​​of the backlight block group 352C adjacent to the first backlight region 350A or the backlight block group 351B in the third backlight region 350C and the backlight block group 351D to the video signal processing circuit 12A. The backlight block group 352C is made up of backlight blocks B1DL, B2DL, B3DL, and B1DR.

[0198] 31 shows an example of information on provisional brightness values ​​transmitted and received between the video signal processing circuits 12B and 12D. The video signal processing circuit 12B transmits information on provisional brightness values ​​of the backlight block group 352B adjacent to the fourth backlight region 350D or the backlight block group 351C in the second backlight region 350B and the backlight block group 351A to the video signal processing circuit 12D. The backlight block group 352B is made up of backlight blocks B10UR, B11UR, B12UR, and B12UL.

[0199] The video signal processing circuit 12D transmits information on the provisional brightness values ​​of the backlight block group 352D adjacent to the second backlight region 350B or the backlight block group 351A in the fourth backlight region 350D and the backlight block group 351C to the video signal processing circuit 12B. The backlight block group 352D is made up of backlight blocks B1DR, B2DR, B3DR, and B3DL.

[0200] Through the above processing, the video signal processing circuit 12A can obtain provisional brightness values ​​for the backlight blocks B1UR, B4UR, B7UR, B10UR, B1DL, B2DL, B3DL, and B1DR adjacent to the first backlight region 350A. Also, the video signal processing circuit 12B can obtain provisional brightness values ​​for the backlight blocks B3UL, B6UL, B9UL, B12UL, B3DL, B1DR, B2DR, and B3DR adjacent to the second backlight region 350B.

[0201] The video signal processing circuit 12C can obtain provisional brightness values ​​for the backlight blocks B1DR, B4DR, B7DR, B10DR, B10UL, B11UL, B12UL, and B10UR adjacent to the third backlight region 350C. The video signal processing circuit 12D can obtain provisional brightness values ​​for the backlight blocks B3DL, B6DL, B9DL, B12DL, B12UL, B10UR, B11UR, and B12UR adjacent to the fourth backlight region 350D.

[0202] Each video signal processing circuit refers to the provisional luminance values ​​of the other backlight areas received from the other video signal processing circuits when calculating the correction coefficients for the backlight block groups adjacent to the other backlight areas in the backlight area it controls. The method of determining the correction coefficients may be the same as that described in the first embodiment.

[0203] 32 shows an example of the relationship between video frames and the corrected luminance values ​​of the corresponding backlight blocks. In video frame 851, only the area facing one backlight block is white, and the other areas are black.

[0204] As described above, when the backlight block of interest is adjacent to the division boundary of the backlight 30, each video signal processing circuit transmits information on the provisional brightness value of the backlight block adjacent to the boundary to the other video signal processing circuit to complement it.

[0205] In Fig. 32, only the area in the video frame corresponding to the backlight block B10UR is white, and the other areas are black. To determine the correction coefficient for the backlight block B10UR, the video signal processing circuit 12B refers to the provisional luminance values ​​of the backlight blocks B7UR, B8UR, and B11UR in the second backlight region 350B, as well as the backlight blocks B9UL and B12UL in the first backlight region 350A, the backlight block B3DL in the third backlight region 350C, and the backlight blocks B1DR and B2DR in the fourth backlight region 350D (see Fig. 27). The method for calculating the correction coefficient is, for example, as described in the first embodiment. As a result, an appropriate correction luminance value of 2.0 can be obtained for the backlight block B10UR.

[0206] 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]

[0207] 1 Display device 10 Signal processing board 11 Power generation circuit 12 Video signal processing circuit 13 Power supply source 14 Video signal source 20 LCD display panel 30 Backlight 201 Gradation-to-brightness conversion unit 202 Block provisional luminance value calculation unit 203 Block provisional luminance value array section 210 Backlight brightness control section 211 Reference block luminance determination unit 213 Correction coefficient calculation unit 214 Corrected luminance value calculation unit 221 Backlight drive control signal generation unit 231 Display control drive signal generation unit

Claims

1. a backlight including a plurality of backlight blocks; a display panel that displays using light from the backlight; a control device; Including, The control device Acquire video data, determining a provisional luminance value for each of the plurality of backlight blocks based on the video data; determining a correction coefficient for a target backlight block selected from the plurality of backlight blocks; determining a correction luminance value of the backlight block of interest based on the provisional luminance value of the backlight block of interest and the correction coefficient; Controlling the backlight block of interest according to the corrected luminance value; In determining the correction coefficient of the backlight block of interest, Calculating statistics of provisional luminance values ​​of a plurality of reference backlight blocks including backlight blocks adjacent to the target backlight block; Calculating a relative value of the statistical value with respect to the provisional luminance value of the backlight block of interest; determining the correction coefficient of the target backlight block based on the relative value and a preset function; Display device.

2. The display device according to claim 1 , The control device determining a product of the provisional luminance value of the backlight block of interest and a correction coefficient as the corrected luminance value of the backlight block of interest; The correction coefficient is a value of 1 or more. Display device.

3. The display device according to claim 1 , The relative value is a value obtained by dividing the statistical value by the provisional luminance value of the backlight block of interest. Display device.

4. The display device according to claim 1 , the plurality of backlight blocks includes a first target backlight block whose entire periphery is surrounded by adjacent backlight blocks; the plurality of reference backlight blocks of the first target backlight block are configured by all adjacent backlight blocks of the first target backlight block; Display device.

5. The display device according to claim 1 , The statistical value is a simple average value. Display device.

6. The display device according to claim 1 , The plurality of backlight blocks are arranged in a matrix, the statistical value is a weighted average; the control device, in calculating the statistical value, gives a smaller weight to a reference backlight block diagonally adjacent to the backlight block of interest than to a reference backlight block adjacent to the backlight block of interest in a row direction or a column direction; Display device.

7. The display device according to claim 1 , the plurality of reference backlight blocks include backlight blocks adjacent to the target backlight block and backlight blocks adjacent to the target backlight block on the outside of the target backlight block; Display device.

8. The display device according to claim 1 , The plurality of backlight blocks are arranged in a matrix, The plurality of reference backlight blocks are configured by backlight blocks adjacent to the target backlight block in the row direction or column direction. Display device.

9. The display device according to claim 1 , the control device selects each of the plurality of backlight blocks as the target backlight block and determines a correction luminance value; The target backlight block and the reference backlight block have a common arrangement pattern; the plurality of backlight blocks includes a second target backlight block located at an end of the backlight; the reference backlight block of the second target backlight block includes a backlight block adjacent to the second target backlight block within the backlight, and a virtual backlight block adjacent to the second target backlight block outside the backlight; Display device.

10. The display device according to claim 9, the provisional luminance value of the virtual backlight block is equal to the provisional luminance value of a reference backlight block adjacent to the virtual backlight block; Display device.

11. The display device according to claim 1 , The control device When a predetermined condition is satisfied, the correction coefficient smaller than 1 is determined for the backlight block of interest by a method different from that used to determine the correction coefficient; If the predetermined condition is not satisfied, determining the correction coefficient of the backlight block of interest based on the relative value and the function; the predetermined condition is that the provisional luminance values ​​of the plurality of reference backlight blocks are the maximum value and the provisional luminance value of the target backlight block is smaller than the maximum value; Display device.

12. The display device according to claim 1 , 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 acquiring information on provisional luminance values ​​of boundary second backlight block groups adjacent to the first backlight block groups from the second processing circuit; controlling the first backlight block group based on the provisional luminance values ​​of the first backlight block group and the boundary second backlight block group; The second processing circuit obtaining information on provisional luminance values ​​of a boundary first backlight block group adjacent to the second backlight block group from the first processing circuit; controlling the second backlight block group based on the provisional brightness values ​​of the second backlight block group and the boundary first backlight block group; Display device.

13. A method for controlling a backlight of a display device including a plurality of backlight blocks, comprising: Acquire video data, determining a provisional luminance value for each of the plurality of backlight blocks based on the video data; determining a correction coefficient for a target backlight block selected from the plurality of backlight blocks; determining a correction luminance value of the backlight block of interest based on the provisional luminance value of the backlight block of interest and the correction coefficient; controlling the backlight block of interest according to the corrected luminance value; This includes: The determination of the correction coefficient of the backlight block of interest is Calculating statistics of provisional luminance values ​​of a plurality of reference backlight blocks including backlight blocks adjacent to the target backlight block; Calculating a relative value of the statistical value with respect to the provisional luminance value of the backlight block of interest; determining the correction coefficient of the target backlight block based on the relative value and a preset function; A control method comprising:

Images