Circuit arrangement and display system

Abstract

To provide a circuit arrangement and the like that can reduce polarization of the luminance of a backlight with respect to a display object in local dimming.SOLUTION: A circuit arrangement 100 includes a storage unit 170 and a light source luminance determination circuit 140. The storage unit 170 stores attenuation factor distribution information 171 indicating the distribution of the attenuation factor of light to the distance from a light source element to a pixel. The light source luminance determination circuit 140 determines light source luminance information indicating the luminance of light emitted from each light source element of a plurality of light source elements on the basis of the attenuation factor distribution information 171. A first direction and a second direction are opposite to each other. In this case, the light source luminance determination circuit 140 determines the light source luminance information on the basis of a pixel value of a target pixel when a selected pixel position is moved in the first direction on a first line and a pixel value of the target pixel when the selected pixel position is moved in the second direction on the first line. The selected pixel position is a position of a pixel that is selected as the target pixel in first image data input to the light source luminance determination circuit 140.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a circuit device, a display system, and the like.

Background Art

[0002] Patent Document 1 discloses a display device including a backlight divided into a plurality of control areas capable of independently changing the emission intensity, and a backlight control unit that controls the lighting of the backlight for each control area. The backlight control unit determines the emission intensity of the light source for each control area based on the gradation value of each pixel of the input image data.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In local dimming, the luminance of the light-emitting elements corresponding to the bright parts of the image increases. At this time, if the balance of the luminance of the light-emitting elements is lost on the left and right sides of the display object, the balance of the display brightness may deteriorate on the left and right sides of the display object. For example, for a bilaterally symmetric display object, if the luminance of the light-emitting elements is not bilaterally symmetric, there is a possibility that the display will not have symmetric brightness on the left and right sides of the display object. In addition, the same problem occurs when the balance of the luminance of the light-emitting elements is lost between the top and bottom of the display object.

Means for Solving the Problems

[0005] One aspect of the present disclosure relates to a circuit device that controls a display device including a plurality of light source elements and a display panel, the circuit device including a storage unit that stores attenuation rate distribution information indicating an attenuation rate distribution of light with respect to the distance between the light source elements and the pixels, and a light source luminance determination circuit that determines light source luminance information indicating the luminance of each of the plurality of light source elements based on the attenuation rate distribution information. When the opposite direction of the first direction is defined as the second direction, the light source luminance determination circuit determines the light source luminance information based on the pixel value of the target pixel at the selected pixel position, which is the position of the pixel selected as the target pixel in the first image data input to the light source luminance determination circuit, when the selected pixel position is moved in the first direction on the first line, and the pixel value of the target pixel when the selected pixel position is moved in the second direction on the first line.

[0006] Another aspect of the present disclosure relates to a display system including the above-described circuit device and the display device.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

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Figure 9

Embodiments for Carrying Out the Invention

[0008] Hereinafter, preferred embodiments of the present disclosure will be described in detail. Note that the embodiments described below do not unduly limit the content described in the claims, and not all of the configurations described in the embodiments are essential components.

[0009] 1. Electronic device, display system, and circuit device FIG. 1 is a configuration example of an electronic device including the display system of the present embodiment. The electronic device 500 includes a processing device 300 and a display system 400. As an example, the electronic device 500 includes an in-vehicle display device including a meter panel, a center information display, a head-up display, or an electronic mirror, a television device, or an information processing device including a display.

[0010] The display system 400 includes a circuit device 100 and a display device 200. The circuit device 100 is, for example, an integrated circuit device in which a plurality of circuit elements are integrated on a semiconductor substrate. Although FIG. 1 shows the circuit device 100 and the display device 200 as separate components, the circuit device 100 may be included in the display device 200.

[0011] The display device 200 includes a backlight 210, a display panel 220, a display driver 230, a light source driver 240, and a display controller 250. An example of the display device 200 is a display used in a television device or an information processing device. Alternatively, the display device 200 may be a head-mounted display including a device for projecting onto the eyes, or a head-up display including a device for projecting onto a screen. When the display device 200 is a head-up display, the display device 200 further includes an optical system for projecting the light emitted from the backlight 210 and transmitted through the display panel 220 onto the screen.

[0012] In a plan view of the backlight 210, light source elements are two-dimensionally arranged on the backlight 210. The light source element is a light-emitting element that emits light by power supply, and is, for example, an inorganic light-emitting diode or an organic light-emitting diode. In local dimming control, the light amounts of the two-dimensionally arranged light source elements are controlled independently of each other. Alternatively, the backlight 210 may be divided into a plurality of areas. In a plan view, a plurality of light source elements are arranged in each area. The light source elements arranged in the area are controlled to have the same light amount, and the light amounts of the respective areas are controlled independently of each other.

[0013] An example of the two-dimensional arrangement of the light source elements is a square arrangement in which light source elements are arranged at all intersections of a plurality of rows and a plurality of columns. However, the two-dimensional arrangement is not limited to the square arrangement. For example, the two-dimensional arrangement may be an arrangement called a rhombus arrangement or a staggered arrangement. In this arrangement, light source elements are arranged at intersections of one of odd rows and even rows and odd columns, and intersections of the other of odd rows and even rows and even columns, and no light source element is arranged at other intersections.

[0014] The light source driver 240 receives the light source luminance data DDIM from the circuit device 100 and drives each light source element of the backlight 210 based on the light source luminance data DDIM. The light source driver 240 is, for example, an integrated circuit device. Note that a plurality of light source drivers may be provided, and each of the light source drivers may be a separate integrated circuit device.

[0015] The display panel 220 is an electro-optical panel that transmits light from the backlight 210 and displays an image by controlling the transmittance. For example, the display panel 220 is a liquid crystal display panel.

[0016] The display controller 250 receives the image data IMB from the circuit device 100 and transmits the image data IMB and a timing control signal for controlling the display timing to the display driver 230. Note that the display controller 250 may perform image processing such as gradation correction, white balance correction, or enlargement / reduction on the received image data IMB.

[0017] The display driver 230 drives the display panel based on the received image data and the timing control signal, thereby causing the display panel 220 to display an image. Note that each of the display controller 250 and the display driver 230 may be configured by a separate integrated circuit device or may be configured by an integrated integrated circuit device.

[0018] The processing device 300 transmits the image data IMA to the circuit device 100. The processing device 300 is a processor such as a CPU, GPU, microcomputer, DSP, ASIC, or FPGA. CPU is an abbreviation for Central Processing Unit. GPU is an abbreviation for Graphics Processing Unit. DSP is an abbreviation for Digital Signal Processor. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array.

[0019] The circuit device 100 receives the image data IMA and performs local dimming control of the display device 200 based on the image data IMA. The circuit device 100 dims the emission luminance of each light source element or each area of the backlight 210 according to the luminance of the image data IMA, and outputs the light source luminance information obtained by the dimming as light source luminance data DDIM to the light source driver 240. Further, the circuit device 100 performs color correction on the image data IMA based on the light source luminance information, and outputs the image data IMB after color correction to the display controller 250.

[0020] FIG. 2 is a detailed configuration example of the circuit device. The circuit device 100 includes an interface circuit 110, a resolution reduction circuit 120, a light source control circuit 130, a light source luminance determination circuit 140, an illumination luminance calculation circuit 150, a color correction circuit 160, and a storage unit 170. Hereinafter, a case where the light emitting elements of the backlight 210 are independently dimmed for each local dimming will be described as an example, but the light emitting elements may be independently dimmed for each area including a plurality of light emitting elements.

[0021] The interface circuit 110 receives the image data IMA from the processing device 300. The interface circuit 110 may be an interface circuit of various image interface methods such as LVDS, parallel RGB method, or DisplayPort. LVDS is the abbreviation of Low Voltage Differential Signaling.

[0022] The storage unit 170 stores the attenuation rate distribution information 171. The storage unit 170 is a storage circuit such as a register or a memory. The memory is a volatile memory such as RAM, or a non-volatile memory such as OTP memory or EEPROM. RAM is the abbreviation of Random Access Memory. OTP is the abbreviation of One Time Programmable. EEPROM is the abbreviation of Electrically Erasable Programmable Read Only Memory. The processing device 300 may write the attenuation rate distribution information 171 to the storage unit 170 via an interface circuit such as the SPI method or the I2C method. Alternatively, when the storage unit 170 is a non-volatile memory, the attenuation rate distribution information 171 may be written to the storage unit 170 in advance.

[0023] The attenuation rate distribution information 171 indicates the attenuation rate distribution of the light reaching the display panel from the light source element. The attenuation rate distribution indicates the relationship between the distance from the light source element to the pixel and the attenuation rate of the light by which the light source element illuminates the pixel. The attenuation rate distribution is also called the attenuation characteristic or the luminance distribution. The attenuation rate distribution information 171 is, for example, a look-up table that takes the distance as an input and outputs the attenuation rate. Alternatively, the attenuation rate distribution information may be function information that defines a function of the attenuation rate distribution. The argument of the function is the distance, and the return value is the attenuation rate. The function information is, for example, the coefficient used in the function.

[0024] The resolution reduction circuit 120 receives the image data IMA from the interface circuit 110. The image data IMA is also referred to as input image data. The resolution reduction circuit 120 performs a process of reducing the resolution of the image data IMA, and generates low-resolution image data IMC with a lower resolution than the image data IMA. "Low resolution" means that the number of pixels of the image data per frame is small.

[0025] The light source luminance determination circuit 140 performs a dimming process using the low-resolution image data IMC and the attenuation rate distribution information 171 read from the storage unit 170, determines light source luminance information indicating the emission luminance of each light source element, and outputs the light source luminance information as light source luminance data LLD. Details of the dimming process will be described later with reference to FIG. 3 and subsequent figures. Note that the resolution reduction circuit 120 may be omitted. In that case, the light source luminance determination circuit 140 determines the light source luminance information by performing a dimming process using the image data IMA and the attenuation rate distribution information 171.

[0026] The light source control circuit 130 controls the light source driver 240 based on the light source luminance data LLD. Specifically, the light source control circuit 130 outputs a timing control signal for controlling the emission timing of the light emitting element or the update timing of the emission luminance to the light source driver 240, and outputs the light source luminance data LLD to the light source driver 240 as light source luminance data DDIM. The light source driver 240 drives each light emitting element with a PWM signal having a pulse width corresponding to the emission luminance of each light source element indicated by the light source luminance data DDIM at the timing specified by the timing control signal. Thereby, each light emitting element emits light with an emission luminance controlled by local dimming.

[0027] The illumination luminance calculation circuit 150 calculates illumination luminance information based on the light source luminance data LLD and the attenuation rate distribution information 171 stored in the storage unit 170, and outputs the illumination luminance information as illumination luminance data LPX. The illumination luminance information indicates the illumination luminance at the position on the display panel 220 corresponding to each pixel of the image data IMA when the display panel 220 is illuminated by the backlight 210.

[0028] The color correction circuit 160 performs color correction on the image data IMA based on the illumination luminance data LPX, and outputs the corrected image data IMB to the display driver 230. Specifically, the color correction circuit 160 multiplies the pixel data of each pixel by the reciprocal of the luminance of the light reaching that pixel, and uses the result as the new pixel data for that pixel.

[0029] Note that the resolution reduction circuit 120, the light source control circuit 130, the light source luminance determination circuit 140, the illumination luminance calculation circuit 150, and the color correction circuit 160 are logic circuits that process digital signals. Each of the resolution reduction circuit 120, the light source control circuit 130, the light source luminance determination circuit 140, the illumination luminance calculation circuit 150, and the color correction circuit 160 may be separately composed of logic circuits, or some or all of them may be composed of an integrated logic circuit. Alternatively, a processor such as a DSP may execute an instruction set or program in which the functions of the resolution reduction circuit 120, the light source control circuit 130, the light source luminance determination circuit 140, the illumination luminance calculation circuit 150, and the color correction circuit 160 are described, thereby realizing the functions of these circuits.

[0030] Alternatively, the circuit device 100 may be a processor such as a CPU, GPU, microcomputer, DSP, ASIC, or FPGA. And the functions of the circuit device 100 may be realized by the processor executing an instruction set or program in which the functions of each part of the circuit device 100 are described.

[0031] The circuit device 100 may include a distortion correction circuit. The distortion correction circuit corrects image distortion caused by the optical system that projects the image displayed on the display panel 220 onto a screen or the like, or image distortion caused by the distortion of the screen. Specifically, the distortion correction circuit performs image correction to cancel or reduce the above image distortion on the image data IMA received by the interface circuit 110, and outputs the corrected image data to the resolution reduction circuit 120, the illumination luminance calculation circuit 150, and the color correction circuit 160. However, the distortion correction circuit may be provided in the processing device 300 instead of the circuit device 100.

[0032] 2. Light Source Luminance Determination Circuit FIG. 3 is an explanatory diagram of a process for determining the luminance of a light source. FIG. 3 shows the correspondence between the image displayed on the display panel 220 and the light source element LG of the backlight 210 when the display panel 220 and the backlight 210 are viewed in plan view. The low-resolution image data IMC is not displayed on the display panel 220, but here shows the correspondence when it is hypothetically displayed. In FIG. 3, the x direction indicates the horizontal scanning direction, and the y direction indicates the vertical scanning direction. The horizontal scanning lines arranged in the +y direction are sequentially referred to as the first horizontal scanning line, the second horizontal scanning line, and so on.

[0033] As will be described later with reference to FIG. 7 and the like, the light source luminance determination circuit 140 selects the target pixel 22 from the low-resolution image data IMC and selects four-by-four light source elements LG around the target pixel 22 as the light source element group 30. The light source luminance determination circuit 140 obtains the luminance illuminated by the light source element group 30 at the position on the display panel 220 corresponding to the target pixel 22. When the luminance illuminated by the light source element group 30 is insufficient with respect to the luminance of the target pixel 22, the shortage is distributed to each light source element of the light source element group 30 to update the emission luminance of each light source element. The light source luminance determination circuit 140 determines the emission luminance of all the light source elements LG by repeating the update of the emission luminance while shifting the target pixel 22 one pixel at a time.

[0034] The light source brightness determination circuit 140 repeatedly performs the above update while selecting the pixels of the first horizontal scanning line one by one in the x direction as the target pixel 22, and then repeatedly performs the above update while selecting the pixels of the second horizontal scanning line one by one in the x direction as the target pixel 22, and repeats this until the last horizontal scanning line. FIG. 3 shows, as an image example, an example in which a high-brightness display object 25 is arranged on a black background. It is assumed that the display object 25 is symmetric. At this time, since the target pixel 22 moves in the x direction, the brightness is likely to be distributed to the light source elements LG corresponding to the left side of the display object 25. That is, when the target pixel 22 comes to the right side of the display object 25, if the target pixel 22 is illuminated with sufficient brightness by the light source elements LG on the left side, the brightness is not distributed to the light source elements LG corresponding to the right side of the display object 25. Therefore, the brightness of the light source elements LG tends to be higher on the left side of the display object 25.

[0035] In this way, in a method of determining the emission brightness by distributing the shortage of the brightness for illuminating the target pixel 22 to the brightness of the surrounding light source elements LG, when the target pixel 22 is moved in one direction, the brightness of the light source elements may be biased with respect to the display object 25. Note that even if the display object 25 is not symmetric, such a bias in the emission brightness may occur. Also, when the target pixel 22 is moved in the vertical scanning direction, the brightness of the light source elements LG tends to be higher on the upper side of the display object 25.

[0036] FIG. 4 is an explanatory diagram of the processing performed by the light source brightness determination circuit of the present embodiment. Note that mainly the parts different from FIG. 3 will be described, and the description of the parts similar to FIG. 3 will be omitted as appropriate.

[0037] In the q-th frame, the light source luminance determination circuit 140 repeatedly updates the emission luminance while selecting the pixels of the horizontal scanning line one by one as the target pixel 22 in the +x direction. In the (q + 1)-th frame, the light source luminance determination circuit 140 repeatedly updates the emission luminance while selecting the pixels of the horizontal scanning line one by one as the target pixel 22 in the -x direction. q is either odd or even. The (q + 1)-th frame is the frame next to the q-th frame. The light source luminance determination circuit 140 averages the emission luminance obtained in the q-th frame and the emission luminance obtained in the (q + 1)-th frame for the same light-emitting elements, and sets the average value as the final emission luminance. Note that after determining the emission luminance in the (q + 2)-th frame, the light source luminance determination circuit 140 averages the emission luminance obtained in the (q + 1)-th frame and the emission luminance obtained in the (q + 2)-th frame for the same light-emitting elements, and sets the average value as the final emission luminance.

[0038] In the q-th frame, the high-luminance light-emitting elements are biased to the left side of the display object 25, and in the (q + 1)-th frame, the high-luminance light-emitting elements are biased to the right side of the display object 25. By averaging them, the left-right bias of the backlight luminance is reduced.

[0039] Note that the light source luminance determination circuit 140 may perform both the process of updating the emission luminance while scanning in the +x direction and the process of updating the emission luminance while scanning in the -x direction for each frame, and obtain the average value as the final emission luminance. At this time, when the resolution reduction circuit 120 is used, since the number of pixels decreases, the processing load of light source luminance determination is reduced. Thereby, even if the process of obtaining both the above emission luminances is performed for each frame, it is possible to suppress an increase in the load.

[0040] Also, in the q-th frame, the light source luminance determination circuit 140 repeatedly updates the emission luminance while selecting the pixels in the first column in the vertical scanning direction one by one as the target pixel 22 in the +y direction, and then repeatedly updates the emission luminance while selecting the pixels in the second column in the vertical scanning direction one by one as the target pixel 22 in the +y direction, and this may be repeated until the last column. In the (q + 1)-th frame, the light source luminance determination circuit 140 repeatedly updates the emission luminance while selecting the pixels in the first column in the vertical scanning direction one by one as the target pixel 22 in the -y direction, and then repeatedly updates the emission luminance while selecting the pixels in the second column in the vertical scanning direction one by one as the target pixel 22 in the -y direction, and this may be repeated until the last column. Then, the light source luminance determination circuit 140 may average the emission luminance obtained in the q-th frame and the emission luminance obtained in the (q + 1)-th frame for the same light emitting elements, and use the average value as the final emission luminance.

[0041] Also, in the q-th frame, the light source luminance determination circuit 140 repeatedly updates the emission luminance while selecting the pixels in the first horizontal scanning line one by one as the target pixel 22 in the +x direction, and then repeatedly updates the emission luminance while selecting the pixels in the second horizontal scanning line one by one as the target pixel 22 in the +x direction, and this may be repeated until the last horizontal scanning line. In the (q + 1)-th frame, the light source luminance determination circuit 140 repeatedly updates the emission luminance while selecting the pixels in the last horizontal scanning line one by one as the target pixel 22 in the -x direction, and then repeatedly updates the emission luminance while selecting the pixels in the horizontal scanning line one before the last horizontal scanning line one by one as the target pixel 22 in the -x direction, and this may be repeated until the first horizontal scanning line. Then, the light source luminance determination circuit 140 may average the emission luminance obtained in the q-th frame and the emission luminance obtained in the (q + 1)-th frame for the same light emitting elements, and use the average value as the final emission luminance.

[0042] FIG. 5 is a detailed configuration example of a resolution reduction circuit and a light source luminance determination circuit. The resolution reduction circuit 120 includes an image luminance extraction unit 121 and a downsampler 122. The light source luminance determination circuit 140 includes a memory controller 141, a line buffer 142, and a luminance analysis unit 143. FIG. 6 is an example of a flow of processes performed by the resolution reduction circuit and the light source luminance determination circuit.

[0043] In step S51, the image luminance extraction unit 121 extracts the maximum value of RGB from each pixel data of the image data IMA, and outputs the extracted data as luminance image data LIMA. The image data IMA is an RGB color image and has RGB data for each pixel. The image luminance extraction unit 121 extracts the maximum value among the R data, G data, and B data for each pixel. Note that the image luminance extraction unit 121 may obtain a luminance value calculated from the R data, G data, and B data, for example, the luminance value Y in the YCrCb color space.

[0044] In step S52, the downsampler 122 downsamples the luminance image data LIMA having the same number of pixels as the image data IMA to generate low-resolution image data IMC having a smaller number of pixels than the image data IMA. The downsampling process is an interpolation process, a decimation process, a binning process, or the like.

[0045] In step S53, the memory controller 141 determines whether the frame number is odd or even. When the frame number is odd, the process proceeds to step S54, and when the frame number is even, the process proceeds to step S55.

[0046] In step S54, the memory controller 141 writes the data of the horizontal scan lines of the low-resolution image data IMC into the line buffer 142 from the left. The left of the line buffer 142 corresponds to the left end of the horizontal scan line and corresponds to the side where the scan starts in the horizontal scan of normal raster scanning. For example, when the address of the line buffer 142 increases in the horizontal scan direction, the memory controller 141 writes the data of the horizontal scan line from the side with the smaller address.

[0047] In step S55, the memory controller 141 writes the data of the horizontal scan lines of the low-resolution image data IMC into the line buffer 142 from the right. The right of the line buffer 142 corresponds to the right end of the horizontal scan line and corresponds to the side where the scan ends in the horizontal scan of normal raster scanning. For example, when the address of the line buffer 142 increases in the horizontal scan direction, the memory controller 141 writes the data of the horizontal scan line from the side with the larger address.

[0048] In step S56, the luminance analysis unit 143 reads out the data of the horizontal scan lines from the left of the line buffer 142. For example, when the address of the line buffer 142 increases in the horizontal scan direction, the luminance analysis unit 143 reads out the data of the horizontal scan line from the side with the smaller address.

[0049] In step S57, the luminance analysis unit 143 obtains the emission luminance of each light source element using the data read from the line buffer 142. The luminance analysis unit 143 reads out the data for one pixel from the line buffer 142, updates the emission luminance using it as the target pixel, reads out the data for the next one pixel from the line buffer 142, updates the emission luminance using it as the target pixel, and repeats this until the last pixel of one frame to determine the light source luminance information for all light source elements.

[0050] In odd frames, since data is written into line buffer 142 in order from the left and read out in order from the left, it is equivalent to the target pixel moving in the +x direction. In even frames, since data is written into line buffer 142 in order from the right and read out in order from the left, it is equivalent to the target pixel moving in the -x direction.

[0051] In step S58, the luminance analysis unit 143 stores the calculation result of step S57 in the storage unit 145 for averaging processing. The storage unit 145 may be a memory such as SRAM or DRAM, or may be a register. Note that the storage unit 170 may also serve as the storage unit 145.

[0052] The luminance analysis unit 143 includes an averaging processing unit 144. In step S59, the averaging processing unit 144 obtains the average value of the emission luminance of each light source element obtained in step S57 and the emission luminance of each light source element one frame before stored in the storage unit 145. Assume that the emission luminance of the q-th frame is stored in the storage unit 145 and the emission luminance of the q+1-th frame is obtained in step S57. When the light source element at the coordinates (x, y) in the q-th frame is represented as pow(x, y, q), the average value is {pow(x, y, q) + pow(x, y, q+1)} / 2. Note that the calculation method of the average value is not limited to simple addition average, and may be weighted addition average or a smoothing filter in the time direction, etc.

[0053] In step S60, the luminance analysis unit 143 determines the average value obtained by the averaging processing unit 144 as the final light source luminance information.

[0054] Note that in step S53, when the frame number is even, the process may proceed to step S54, and when the frame number is odd, the process may proceed to step S55.

[0055] Also, it may be configured to execute steps S54 and S55 for each frame. In that case, the light source luminance determination circuit 140 includes a frame memory. The memory controller 141 writes the low-resolution image data IMC of one frame into the frame memory. In the first half period of the next frame, the memory controller 141 writes the data of the horizontal scanning lines of the low-resolution image data IMC read from the frame memory into the line buffer 142 from the left. Steps S56 to S58 are executed. In the second half period of the frame, the memory controller 141 writes the data of the horizontal scanning lines of the low-resolution image data IMC read from the frame memory into the line buffer 142 from the right. Steps S56 to S57 are executed. In step S59, the averaging processing unit 144 obtains the average value of the emission luminance of each light source element obtained and stored in the storage unit 145 during the first half period of the frame and the emission luminance of each light source element obtained during the second half period of the frame.

[0056] Also, the light source luminance may be calculated while scanning the low-resolution image data IMC in the vertical scanning direction. In that case, the light source luminance determination circuit 140 includes a frame memory. The memory controller 141 writes the low-resolution image data IMC of one frame into the frame memory. In the next frame, the memory controller 141 writes the data of one column in the vertical scanning direction of the low-resolution image data IMC read from the frame memory into the line buffer 142 from the left. Steps S56 to S58 are executed. In the second half period of the frame, the memory controller 141 writes the data of one column in the vertical scanning direction of the low-resolution image data IMC read from the frame memory into the line buffer 142 from the right. Steps S56 to S57 are executed. In step S59, the averaging processing unit 144 obtains the average value of the emission luminance of each light source element obtained and stored in the storage unit 145 during the first half period of the frame and the emission luminance of each light source element obtained during the second half period of the frame.

[0057] In this embodiment, the circuit device 100 controls a display device 200 including a plurality of light source elements and a display panel 220. The circuit device 100 includes a storage unit 170 and a light source luminance determination circuit 140. The storage unit 170 stores attenuation rate distribution information 171 indicating the attenuation rate distribution of light with respect to the distance between the light source element and the pixel. The light source luminance determination circuit 140 determines light source luminance information indicating the luminance of each light source element of the plurality of light source elements based on the attenuation rate distribution information 171. The direction opposite to the first direction is defined as the second direction. At this time, the light source luminance determination circuit 140 determines the light source luminance information based on the pixel value of the target pixel when the selection pixel position is moved in the first direction on the first line and the pixel value of the target pixel when the selection pixel position is moved in the second direction on the first line. The selection pixel position is the position of the pixel selected as the target pixel in the first image data input to the light source luminance determination circuit 140.

[0058] According to this embodiment, the bias of the emission luminance with respect to the display object 25 is opposite between the light source luminance information determined while moving the target pixel in the first direction on the first line and the light source luminance information determined while moving the target pixel in the second direction on the first line. By determining the light source luminance information based on these two pieces of light source luminance information, the bias of the emission luminance of the backlight 210 can be reduced.

[0059] When the circuit device 100 includes a resolution reduction circuit 120, the first image data corresponds to low-resolution image data IMC. When the circuit device 100 does not include a resolution reduction circuit 120, the first image data corresponds to image data IMA. The first direction may be either the x direction or the y direction. When the first direction is the x direction, the first line corresponds to an arbitrary horizontal scanning line. When the first direction is the y direction, the first line corresponds to an arbitrary pixel column in the vertical scanning direction.

[0060] Also, in this embodiment, the light source luminance determination circuit 140 may determine the first light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the first direction on the first line in the first frame. The light source luminance determination circuit 140 may determine the second light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the second direction on the first line in the second frame.

[0061] According to this embodiment, based on the first light source luminance information determined while moving the target pixel in the first direction on the first line of the first frame and the second light source luminance information determined while moving the target pixel in the second direction on the first line of the second frame, the final light source luminance information can be determined.

[0062] Note that in the example of FIG. 4, the first frame corresponds to the q-th frame, and the second frame corresponds to the (q + 1)-th frame.

[0063] Also, in this embodiment, the light source luminance determination circuit 140 may perform an averaging process on the first light source luminance information and the second light source luminance information, and output the light source luminance information after the averaging process.

[0064] According to this embodiment, by averaging the first light source luminance information and the second light source luminance information in which the bias direction of the emission luminance with respect to the display object 25 is opposite, the bias of the emission luminance of the backlight 210 can be reduced.

[0065] Note that the averaging process may not be performed, and the light emitting element may be controlled by the first light source luminance information in the first frame and the light emitting element may be controlled by the second light source luminance information in the second frame. Since light emission is alternately performed with the first light source luminance information and the second light source luminance information in which the bias direction of the emission luminance with respect to the display object 25 is opposite, it is temporally averaged visually, and the bias of the emission luminance of the backlight 210 is reduced.

[0066] Also, in the present embodiment, the light source luminance determination circuit 140 may determine the first light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the first direction on the first line in the first frame. The light source luminance determination circuit 140 may determine the second light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the second direction on the first line in the first frame. Then, the light source luminance determination circuit 140 may perform an averaging process on the first light source luminance information and the second light source luminance information, and output the light source luminance information after the averaging process.

[0067] According to the present embodiment, within one frame, the first light source luminance information determined while moving the target pixel in the first direction on the first line and the second light source luminance information determined while moving the target pixel in the second direction on the first line of the second frame are determined, and they are averaged. As a result, in each frame, the first light source luminance information and the second light source luminance information, in which the bias direction of the emission luminance with respect to the display object 25 is opposite, are averaged. Compared with the method of reversing the direction for each frame, the responsiveness to the case where the image changes between frames can be increased.

[0068] Also, in the present embodiment, the light source luminance determination circuit 140 may include a line buffer 142 that buffers the first image data. When moving the selected pixel position in the first direction, the line buffer 142 may output the first image data while scanning it in the first direction. When moving the selected pixel position in the second direction, the line buffer 142 may output the first image data while scanning it in the second direction.

[0069] According to the present embodiment, depending on the scanning direction when the line buffer 142 outputs the first image data, it is possible to control whether to move the target pixel in the first direction or to move the target pixel in the second direction.

[0070] Also, in the present embodiment, the first direction may be the horizontal scanning direction. The second direction may be the direction opposite to the horizontal scanning direction.

[0071] According to this embodiment, the light source luminance information is determined based on the light source luminance information determined while moving the target pixel in the horizontal scanning direction in the first line and the light source luminance information determined while moving the target pixel in the direction opposite to the horizontal scanning direction in the first line. Thereby, the deviation of the emission luminance in the left - right direction with respect to the display object 25 can be reduced.

[0072] Also, in this embodiment, the first direction may be the vertical scanning direction. The second direction may be the direction opposite to the vertical scanning direction.

[0073] According to this embodiment, the light source luminance information is determined based on the light source luminance information determined while moving the target pixel in the vertical scanning direction in the first line and the light source luminance information determined while moving the target pixel in the direction opposite to the vertical scanning direction in the first line. Thereby, the deviation of the emission luminance in the up - down direction with respect to the display object 25 can be reduced.

[0074] Also, in this embodiment, the circuit device 100 may include a resolution reduction circuit 120 and a color correction circuit 160. The resolution reduction circuit 120 may generate first image data with a lower resolution than the input image data IMA from the input image data IMA. The color correction circuit 160 may color - correct the input image data IMA based on the light source luminance information after the averaging process.

[0075] According to this embodiment, in the determination of the light source luminance, since the first image data with a lower resolution than the input image data IMA is used in the light source luminance determination, the number of pixels to be calculated is reduced, so the processing load is reduced.

[0076] 3. Light Source Luminance Determination Circuit and Illumination Luminance Calculation Circuit FIG. 7 is an example of a flow of processing performed by the light source luminance determination circuit. This flow corresponds to S54, S56, S57 in FIG. 6 in odd frames and corresponds to S55, S56, S57 in FIG. 6 in even frames.

[0077] In step S2, the light source luminance determination circuit 140 initializes the light source luminance information. For example, the luminance values of all the light source elements are initialized to zero.

[0078] In step S3, the light source luminance determination circuit 140 selects one pixel from the pixels included in the low-resolution image data IMC. The selected pixel is referred to as the target pixel. Specifically, the light source luminance determination circuit 140 reads out data for one pixel from the line buffer 142 and uses it as the data of the target pixel. In the loop from step S3 to step S6, the target pixels are sequentially selected, and the selection order is as described in the flow of FIG. 6 and the like.

[0079] In step S4, the light source luminance determination circuit 140 selects n×m light source elements around the target pixel among the light source elements of the backlight 210. These n×m light source elements are also referred to as surrounding light source elements. n and m may each be an integer of 2 or more. FIG. 8 shows an example of the surrounding light source elements. Here, an example where n = m = 4 is shown.

[0080] As shown in FIG. 8, let the position of the target pixel 22 be (i, j). i indicates the x coordinate in the image data IMA, and j indicates the y coordinate in the image data IMA. In the flow of FIG. 7, the target pixel 22 is a pixel of the low-resolution image data IMC, but the xy coordinates in the image data IMA corresponding to the xy coordinates in the low-resolution image data IMC are used. The light source luminance determination circuit 140 selects the light source elements L1 to L16 in the two nearest columns in each of the +x direction and the -x direction, and in the two nearest rows in each of the +y direction and the -y direction, based on the position (i, j). When k is an integer from 1 to 16, the position of the light source element Lk is represented as (xk, yk). (xk, yk) is the xy coordinate on the image data IMA corresponding to the light source element Lk. Note that (i, j) and (xk, yk) may be xy coordinates on the low-resolution image data IMC.

[0081] In step S5 of FIG. 7, the light source luminance determination circuit 140 updates the light source luminance information of the n×m light source elements selected in step S4 by using the pixel value of the target pixel 22 in the low-resolution image data IMC and the attenuation rate distribution information 171 stored in the storage unit 170.

[0082] In step S6, the light source luminance determination circuit 140 determines whether all pixels have been selected as the target pixel. If all pixels have been selected, the process ends. If there are unselected pixels, the process returns to step S3.

[0083] The update process of the light source luminance information in step S5 will be described. The light source luminance determination circuit 140 determines the required change amount Δ ij indicating the required change amount of the light amount received by the target pixel 22 from the light source elements L1 to L16 by the following formula (1).

[0084]

Equation

[0085] In the above formula (1), INT ij is the luminance value of the target pixel 22 in the low-resolution image data IMC. lsf(k) is the attenuation rate of the light by which the light source element Lk illuminates the target pixel 22. The light source luminance determination circuit 140 obtains the distance between the target pixel 22 and the light source element Lk, and obtains the attenuation rate lsf(k) corresponding to the obtained distance from the attenuation rate distribution information 171. powc(k) is the previous light source luminance information of the light source element Lk. The previous light source luminance information is the light source luminance information calculated using the previous target pixel selected one before the current target pixel 22. The previous target pixel is the pixel at the position (i - 1, j) one before the position (i, j) in the +x direction in the odd frame, and the pixel at the position (i + 1, j) one before the position (i, j) in the -x direction in the even frame.

[0086] The light source luminance determination circuit 140 calculates the required change amount Δ ijBy distributing it to the light source luminance information of the light source element Lk, the light source luminance information is updated.

[0087]

Number

[0088] By executing the loop of steps S3 to S6 until the last pixel of the low-resolution image data IMC, the emission luminance is determined for all the light source elements of the backlight 210 using one frame of the low-resolution image data IMC. The average value of the emission luminance determined in the odd frames and the emission luminance determined in the even frames becomes the final emission luminance.

[0089] FIG. 9 is an example of a flow of processing performed by the illumination luminance calculation circuit. Here, the example of the surrounding light source elements in FIG. 8 is also used, but the processing performed by the illumination luminance calculation circuit 150 is a process separate from the processing performed by the light source luminance determination circuit 140.

[0090] In step S11, the illumination luminance calculation circuit 150 selects one pixel from the pixels included in the image data IMA. The selected pixel will be referred to as the target pixel. In the loop from step S11 to step S14, the target pixels are sequentially selected. For example, in the first step S11, the first pixel of the first scanning line of the image data IMA is selected, and in subsequent steps S11, the second pixel, the third pixel, ··· are sequentially selected. When all the pixels of the first scanning line are selected, the pixels of the second scanning line are sequentially selected, and this is repeated until the final scanning line.

[0091] In step S12, the illumination luminance calculation circuit 150 selects s×t light source elements around the target pixel among the light source elements of the backlight 210. These s×t light source elements are also referred to as surrounding light source elements. s and t may each be an integer of 2 or more, and FIG. 8 shows an example where s = t = 4. However, s×t and n×m may be different.

[0092] Based on the position (i, j), the illumination luminance calculation circuit 150 selects the light source elements L1 to L16 in the two columns closest to the +x direction and -x direction respectively, and in the two rows closest to the +y direction and -y direction respectively. When β is an integer from 1 to 16, the position of the light source element Lβ is represented as (xβ, yβ).

[0093] In step S13, the illumination luminance calculation circuit 150 obtains the illumination luminance information of the target pixel by using the light source luminance information of the selected s×t light source elements and the attenuation rate distribution information 171.

[0094] In step S14, the illumination luminance calculation circuit 150 determines whether all pixels have been selected as the target pixel. If all pixels have been selected, the process ends. If there are unselected pixels, the process returns to step S11.

[0095] The calculation process of the illumination luminance information in step S13 will be described. The illumination luminance calculation circuit 150 obtains the illumination luminance information of the target pixel 22 according to the following formulas (3) and (4).

[0096]

Equation

[0097]

Equation

[0098] In the above formula (3), PL(i, j) is the illumination luminance information for the pixel at the position (i, j). pow(β) is the light source luminance information determined by the light source luminance determination circuit 140. lsf(β) is the attenuation rate of the light emitted by the light source element Lβ illuminating the target pixel 22. The illumination luminance calculation circuit 150 calculates the distance between the target pixel 22 and the light source element Lβ, and obtains the attenuation rate lsf(β) corresponding to that distance from the attenuation rate distribution information 171. In the above formula (4), the square of the distance is used as the input to the look-up table, but the distance can also be used as the input to the look-up table.

[0099] Note that after the loop of steps S3 to S6 in the flow of FIG. 7 is executed until the last pixel of the low-resolution image data IMC, powu in the above formula (2) becomes the light source luminance information for one frame. The average value of powu for odd frames and powu for even frames is used as pow in the above formula (3).

[0100] The illumination luminance calculation circuit 150 may obtain the illumination luminance information of the target pixel from the light source luminance information of all the light source elements of the backlight 210 as well as the light source luminance information of s×t light source elements around the target pixel.

[0101] In the present embodiment, the light source luminance determination circuit 140 selects the p-th pixel as the target pixel 22 in the first image data. p is an integer of 2 or more. The light source luminance determination circuit 140 performs an update process of obtaining the p-th light source luminance information by updating the (p - 1)-th light source luminance information based on the (p - 1)-th light source luminance information obtained based on the pixel value of the (p - 1)-th pixel, the pixel value of the p-th pixel, and the attenuation rate distribution information 171. When moving the selected pixel position (i, j) in the first direction, the p-th pixel is the pixel in the first direction of the (p - 1)-th pixel. When moving the selected pixel position (i, j) in the second direction, the p-th pixel is the pixel in the second direction of the (p - 1)-th pixel.

[0102] Also in the present embodiment, in the update process, the light source luminance determination circuit 140 determines the required change amount Δ ij in the luminance for illuminating the p-th pixel in the display panel 220 based on the pixel value of the p-th pixel and the (p - 1)-th light source luminance information, ij and obtains the p-th light source luminance information by updating the (p - 1)-th light source luminance information based on the required change amount Δ

[0103] According to the present embodiment, when the update process is performed while moving the selected pixel position (i, j) in the first direction and when the update process is performed while moving the selected pixel position (i, j) in the second direction, the direction of the deviation of the emission luminance with respect to the display object 25 is opposite. By determining the light source luminance information based on the light source luminance information obtained in two directions, the deviation of the emission luminance of the backlight 210 can be reduced.

[0104] Note that in the examples of FIGS. 7 and 8, the first image data is the low-resolution image data IMC. However, when the resolution reduction circuit 120 is not provided, the first image data may be the image data IMA. In the examples of FIGS. 7 and 8, the first direction is the horizontal scanning direction. However, the first direction may be the vertical scanning direction. In the examples of FIGS. 7 and 8, when moving the selected pixel position (i, j) in the first direction, the coordinates of the p-th pixel are (i, j), and the coordinates of the p-1-th pixel are (i - 1, j). When moving the selected pixel position (i, j) in the second direction, the coordinates of the p-th pixel are (i, j), and the coordinates of the p-1-th pixel are (i + 1, j). As described above, the first direction may be the vertical scanning direction. In that case, when moving the selected pixel position (i, j) in the first direction, the coordinates of the p-th pixel may be (i, j), and the coordinates of the p-1-th pixel may be (i, j - 1). When moving the selected pixel position (i, j) in the second direction, the coordinates of the p-th pixel may be (i, j), and the coordinates of the p-1-th pixel may be (i, j + 1).

[0105] Note that although the present embodiment has been described in detail as above, those skilled in the art will easily understand that many modifications can be made without substantially departing from the novel matters and effects of the present disclosure. Therefore, all such modified examples are intended to be included within the scope of the present disclosure. For example, in the specification or drawings, a term that is described at least once together with a broader or synonymous different term can be replaced with that different term anywhere in the specification or drawings. Also, all combinations of the present embodiment and the modified examples are included within the scope of the present disclosure. Also, the configurations and operations of the interface circuit, resolution reduction circuit, light source luminance determination circuit, illumination luminance calculation circuit, light source control circuit, color correction circuit, storage unit, circuit device, backlight, display panel, display device, processing device, and electronic device are not limited to those described in the present embodiment, and various modified implementations are possible.

Explanation of Reference Numerals

[0106] 22…Target pixel, 25…Display object, 30…Light source element group, 100…Circuit device, 110…Interface circuit, 120…Resolution reduction circuit, 121…Image brightness extraction unit, 122…Downsampler, 130…Light source control circuit, 140…Light source brightness determination circuit, 141…Memory controller, 142…Line buffer, 143…Brightness analysis unit, 144…Averaging processing unit, 145…Storage unit, 150…Illumination brightness calculation circuit, 160…Color correction circuit, 170…Storage unit, 171…Attenuation rate distribution information, 200…Display device, 210…Backlight, 220…Display panel, 230…Display driver, 240…Light source driver, 250…Display controller, 300…Processing device, 400…Display system, 500…Electronic device, IMA, IMB…Image data, IMC…Low-resolution image data, L1~L16…Light source elements, LG…Light source element

Claims

1. A circuit device for controlling a display device including a plurality of light source elements and a display panel, a storage unit that stores attenuation rate distribution information indicating an attenuation rate distribution of light with respect to the distance between the light source element and the pixel; a light source luminance determination circuit that determines light source luminance information indicating the luminance of each light source element of the plurality of light source elements based on the attenuation rate distribution information; comprising: the light source luminance determination circuit When the direction opposite to the first direction is defined as the second direction, the selected pixel position, which is the position of the pixel selected as the target pixel in the first image data input to the light source luminance determination circuit, is moved in the first direction on the first line. The light source luminance information is determined based on the pixel value of the target pixel and the pixel value of the target pixel when the selected pixel position is moved in the second direction on the first line. A circuit device characterized by that.

2. In the circuit device according to claim 1, the light source luminance determination circuit determines first light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the first direction on the first line in the first frame, determines second light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the second direction on the first line in the second frame. A circuit device characterized by that.

3. In the circuit device according to claim 2, the light source luminance determination circuit performs an averaging process on the first light source luminance information and the second light source luminance information, and outputs the light source luminance information after the averaging process. A circuit device characterized by that.

4. In the circuit device according to claim 1, the light source luminance determination circuit determines first light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the first direction on the first line in the first frame, determines second light source luminance information based on the pixel value of the target pixel when the selected pixel position is moved in the second direction on the first line in the first frame, performs an averaging process on the first light source luminance information and the second light source luminance information, and outputs the light source luminance information after the averaging process. A circuit device characterized by that.

5. In the circuit device according to claim 1, the light source luminance determination circuit In the first image data, select the p-th pixel (p is an integer of 2 or more) as the target pixel, and update the (p - 1)-th light source luminance information based on the pixel value of the (p - 1)-th pixel, the pixel value of the p-th pixel, and the attenuation rate distribution information, thereby performing an update process to obtain the p-th light source luminance information. When moving the selected pixel position in the first direction, the p-th pixel is the pixel in the first direction of the (p - 1)-th pixel. A circuit device, wherein when moving the selected pixel position in the second direction, the p-th pixel is the pixel in the second direction of the (p - 1)-th pixel.

6. In the circuit device according to claim 5, the light source luminance determination circuit In the update process, based on the pixel value of the p-th pixel and the (p - 1)-th light source luminance information, obtain a required change amount of the luminance for illuminating the p-th pixel on the display panel, and update the (p - 1)-th light source luminance information based on the required change amount and the attenuation rate distribution information, thereby obtaining the p-th light source luminance information. A circuit device characterized by this.

7. In the circuit device according to claim 1, the light source luminance determination circuit includes a line buffer for buffering the first image data, the line buffer When moving the selected pixel position in the first direction, outputs the first image data while scanning it in the first direction. A circuit device, wherein when moving the selected pixel position in the second direction, outputs the first image data while scanning it in the second direction.

8. In the circuit device according to claim 1, the first direction is the horizontal scanning direction, A circuit device, wherein the second direction is the opposite direction of the horizontal scanning direction.

9. In the circuit device according to claim 1, the first direction is the vertical scanning direction, A circuit device, wherein the second direction is the opposite direction of the vertical scanning direction.

10. In the circuit device according to claim 1, a resolution reduction circuit that generates the first image data with a lower resolution than the input image data from the input image data, a color correction circuit that color-corrects the input image data based on the light source luminance information after the averaging process, A circuit device characterized by including these.

11. A display system, characterized by including the circuit device according to any one of claims 1 to 10, and the display device. ​

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