Circuit device and display system

Abstract

To provide a circuit device, etc., capable of controlling illumination to an optimum level for display content or environment in local dimming.SOLUTION: A circuit device 100 includes a luminance analysis circuit 130 and a dimmer circuit 150. The luminance analysis circuit 130 analyzes the luminance of image data IMA of an inputted image and outputs luminance information INT. The dimmer circuit 150 determines light source luminance information indicating the emission luminance of the light emitted by each of a plurality of light source elements in accordance with the luminance information INT. The dimmer circuit 150 uses a weight W(r) corresponding to a distance r between a pixel and a light source element as it determines the emission luminance of each light source element from the luminance information INT of the pixel. The dimmer circuit 150 sets the degradation degree of the weight W(r) for the distance r to a first degradation degree when a global dimming parameter DIMG is equal to a first value. The dimmer circuit 150 sets the degradation degree to a second degradation degree higher than the first degradation degree when the global dimming parameter DIMG is equal to a second value smaller than the first value.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses a backlit display device that changes the drive values ​​of LEDs to reduce sudden backlight changes in dark areas in order to avoid or reduce artifacts due to the halo effect. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2012-516458 Summary of the Invention [Problem to be solved by the invention]

[0004] By reducing the luminance of the light-emitting element that emits light to the display panel, the halo caused by that light can be reduced. However, there is a trade-off between the reduction in the halo and the reduction in the luminance illuminating the display panel, so there is a possibility that dimming that is optimal for the displayed content or environment, etc., may not be performed. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a circuit device for controlling a display device including a plurality of light source elements and a display panel, the circuit device including: a luminance analysis circuit that performs luminance analysis on image data of an input image to output luminance information; and a dimming circuit that determines light source luminance information indicating the emission luminance of each of the plurality of light source elements according to the luminance information, the dimming circuit determining the emission luminance of the light source element from the luminance information of the pixel using a weight according to the distance between the pixel and the light source element, and setting a first attenuation degree as an attenuation degree of the weight with respect to the distance when a global dimming parameter determined by a global dimming process is a first value, and setting a second attenuation degree higher than the first attenuation degree when the global dimming parameter is a second value smaller than the first value.

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

[0007] [Figure 1] Example of electronic device configuration. [Diagram 2] 1 shows an example of the configuration of a circuit device. [Diagram 3] 1 shows a detailed configuration example of a luminance analysis circuit. [Figure 4] FIG. 4 is an explanatory diagram of a process performed by a dimming circuit. [Diagram 5] First example of weighting according to global dimming parameters. [Figure 6] Second example of weighting according to global dimming parameters. [Figure 7] A third example of weighting depending on global dimming parameters. [Figure 8] 3 shows a detailed configuration example of a circuit device. [Figure 9] Example of a lookup table LUTA. [Figure 10] An example of the decay rate distribution of the LUTA lookup table. [Figure 11] Example of lookup table LUTB. [Figure 12]An example of the decay rate distribution of the lookup table LUTB. [Figure 13] Example of a lookup table LUTC. [Figure 14] An example of decay rate distribution for the LUTC lookup table. [Figure 15] The process flow of the dimming circuit. [Figure 16] 4 is a flow chart showing the lighting luminance calculation process performed by the color correction circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A preferred embodiment of the present disclosure will be described in detail below. Note that the embodiment described below does not unduly limit the contents described in the claims, and all of the configurations described in the embodiment are not necessarily essential configurations.

[0009] 1. Electronic equipment, display systems and circuit devices 1 shows an example of the configuration of an electronic device including a display system according to the present embodiment. The electronic device 500 includes a processing device 300 and a display system 400. The electronic device 500 is, for example, 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 the circuit device 100 and the display device 200 are illustrated as separate components in FIG. 1, 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, and a light source driver 240. An example of the display device 200 is a display used in a television device, an information processing device, or the like. Alternatively, the display device 200 may be a head-mounted display including a projection device onto the eyes, or a head-up display including a projection device onto a screen. When the display device 200 is a head-up display, the display device 200 further includes an optical system for projecting light emitted from the backlight 210 and transmitted through the display panel 220 onto a screen.

[0012] In a plan view of the backlight 210, light source elements are arranged two-dimensionally in the backlight 210. The light source elements are light-emitting elements that emit light when supplied with power, and are, for example, inorganic light-emitting diodes or organic light-emitting diodes. 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 an 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 a two-dimensional arrangement of light source elements is a square arrangement in which light source elements are arranged at all intersections of multiple rows and multiple columns. However, the two-dimensional arrangement is not limited to a square arrangement. For example, the two-dimensional arrangement may be an arrangement called a diamond arrangement or a staggered arrangement. In this arrangement, light source elements are arranged at intersections between one of the odd-numbered rows and the even-numbered rows and the odd-numbered columns, and at intersections between the other of the odd-numbered rows and the even-numbered rows and the even-numbered columns, and light source elements are not 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 of the light. For example, the display panel 220 is a liquid crystal display panel.

[0016] The display driver 230 receives image data IMB and a timing control signal for controlling display timing from the circuit device 100. The display driver 230 drives the display panel based on the received image data IMB and timing control signal, thereby causing the display panel 220 to display an image.

[0017] The processing device 300 transmits image data IMA to the circuit device 100. The processing device 300 also performs global dimming processing based on information on the amount of ambient light detected by an external light sensor or the like, and transmits the result to the circuit device 100 as a global dimming parameter DIMG. The processing device 300 may perform global dimming processing based on the brightness of an image represented by the image data IMA. The global dimming parameter is, for example, 0 or more and 1 or less, and is common to the entire backlight 210. The processing device 300 is a processor such as a CPU, a GPU, a microcomputer, a DSP, an ASIC, or an FPGA. CPU stands for Central Processing Unit. GPU stands for Graphics Processing Unit. DSP stands for Digital Signal Processor. ASIC stands for Application Specific Integrated Circuit. FPGA stands for Field Programmable Gate Array.

[0018] The circuit device 100 receives the image data IMA and the global dimming parameter DIMG, and performs local dimming control of the display device 200 based on the image data IMA and the global dimming parameter DIMG. The circuit device 100 adjusts 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 light source luminance information obtained by the dimming to the light source driver 240 as light source luminance data DDIM. The circuit device 100 also performs color correction on the image data IMA based on the light source luminance information, and outputs the color-corrected image data IMB to the display driver 230.

[0019] The circuit device 100 also incorporates a function of a display controller. That is, the circuit device 100 transmits image data IMB and a timing control signal for controlling display timing to the display driver 230. The circuit device 100 may also perform image processing such as gradation correction, white balance correction, or enlargement / reduction on the image data IMA or image data IMB. Note that the circuit device 100 may not incorporate the function of the display controller, and a display controller may be provided as an integrated circuit device separate from the circuit device 100. In this case, the display controller may be included in the display device 200. The display controller and the display driver 230 may each be configured as separate integrated circuit devices, or may be configured as an integrated circuit device.

[0020] 2. Example of circuit device configuration In the following, illustration and description of the display controller function built into the circuit device 100 will be omitted, and illustration and description will be given of dimming and color correction.

[0021] 2 shows an example of the configuration of a circuit device 100. The circuit device 100 includes a color correction circuit 120, a luminance analysis circuit 130, a light adjustment circuit 150, and a storage unit 170.

[0022] The storage unit 170 stores the attenuation rate distribution information 171. The storage unit 170 is a register or a memory. The memory is a volatile memory such as a RAM, or a non-volatile memory such as an OTP memory or an EEPROM. RAM is an abbreviation for Random Access Memory. OTP is an abbreviation for One Time Programmable. EEPROM is an abbreviation for Electrically Erasable Programmable Read Only Memory.

[0023] The attenuation rate distribution information 171 indicates the attenuation rate distribution of light reaching the display panel from a light source element. The attenuation rate distribution indicates the relationship between the distance from a light source element to a pixel and the attenuation rate of light with which the light source element illuminates the pixel. The attenuation rate distribution is also called attenuation characteristics or luminance distribution. The attenuation rate distribution information 171 is, for example, a lookup table or a function indicating the attenuation rate distribution. When the function is a polynomial, the attenuation rate distribution information 171 may be the coefficient of each term of the polynomial.

[0024] The circuit device 100 receives image data IMA from the processing device 300 through an image interface (not shown). An image represented by the image data IMA is called an input image. The image interface may be of various types, such as LVDS, a parallel RGB type, or a display port. LVDS is an abbreviation for Low Voltage Differential Signaling.

[0025] The received image data IMA is input to the luminance analysis circuit 130. The luminance analysis circuit 130 analyzes the luminance of the image data IMA and outputs the result as luminance information INT. The luminance information INT indicates the luminance of the image at each position of the input image. FIG. 3 shows an example of a detailed configuration of the luminance analysis circuit. The luminance analysis circuit 130 includes a luminance extraction unit 131 and a downsampling unit 132.

[0026] The input image is an RGB color image. That is, each pixel of the image data IMA has an R pixel value, a G pixel value, and a B pixel value. The luminance extraction unit 131 sets the maximum value of the R pixel value, the G pixel value, and the B pixel value as the luminance value of the pixel. This results in a first luminance image in which each pixel has a luminance value.

[0027] The downsampling unit 132 obtains a second luminance image by downsampling the first luminance image. The number of pixels of the second luminance image is smaller than the number of pixels of the first luminance image. It is sufficient that downsampling is performed in at least one of the horizontal scanning direction and the vertical scanning direction. As an example, the number of pixels is downsampled to 1 / 2 or less in both the horizontal scanning direction and the vertical scanning direction. The downsampling unit 132 outputs the second luminance image as luminance information INT.

[0028] The configuration of the luminance analysis circuit 130 is not limited to the above. For example, the downsampling unit 132 may be omitted, and the first luminance image may be output as the luminance information INT. Alternatively, the luminance extraction unit 131 may obtain the first luminance image from a luminance value calculated by multiplying an RGB pixel value by a coefficient, such as Y in the YCrCb space.

[0029] The dimming circuit 150 generates light source luminance information indicating the emission luminance of each light emitting element based on the luminance information INT and the global dimming parameter DIMG, and outputs the light source luminance information as light source luminance data DDIM. As described in Fig. 1, the global dimming parameter DIMG is input from the processing device 300 to the circuit device 100. However, the circuit device 100 may perform global dimming processing based on information on the amount of ambient light, and obtain the global dimming parameter DIMG.

[0030] 4 shows an explanatory diagram of the process performed by the light control circuit. The x direction is the horizontal scanning direction of the display panel, and the y direction is the vertical scanning direction of the display panel. Here, it is assumed that the number of pixels of the luminance information INT is the same as the number of pixels of the display panel 220. Even when downsampling is performed, it is possible to consider the coordinates and distances on the display panel 220 from the correspondence between the coordinates in the luminance information INT after downsampling and the coordinates on the display panel 220.

[0031] The target pixel 22 is any one pixel in the luminance information INT. The coordinates of the pixel are (i, j). The light control circuit 150 determines the emission luminance of the n×m light source elements surrounding the target pixel 22 from the luminance information INT(i, j) of the target pixel 22. Each of n and m may be an integer of 2 or more, and FIG. 4 shows an example of n=m=4. These 4×4 light source elements are L1 to L16. The light source element is represented as Lk, where k is an integer between 1 and 16. The light control circuit 150 determines the emission luminance of the light source element Lk from the luminance information of the target pixel 22 using a weight W(r) according to the distance r between the target pixel 22 and the light source element Lk. If the coordinates of the light source element Lk are (xk, yk), for example, 2 =(i-xk) 2 +(j-yk) 2 Figure 4 shows W(r) for k=6 as an example.

[0032] The weight W(r) decreases as the distance r increases. The light control circuit 150 changes the attenuation degree of the weight W(r) for the distance r according to the global light control parameter DIMG. Specifically, when the global light control parameter DIMG is large, the environment is bright or the brightness of the image represented by the image data IMA is high. In that case, the light control circuit 150 decreases the attenuation degree of the weight W(r) for the distance r. On the other hand, when the global light control parameter DIMG is small, the environment is dark or the brightness of the image represented by the image data IMA is low. In that case, the light control circuit 150 increases the attenuation degree of the weight W(r) for the distance r. The light control circuit 150 determines the emission brightness of the light source element Lk according to the brightness information INT(i,j) of the target pixel 22, and the weighting of how bright the emission brightness is is the weight W(r).

[0033] In addition, "high degree of attenuation with respect to distance" of a weight means that the distance over which the weight decreases to a predetermined value is short. The predetermined value may be any value, and is, for example, within a range of half the maximum value to zero. Alternatively, "high degree of attenuation with respect to distance" means that the weight decreases by a large amount with respect to a change in distance in the direction in which the distance increases. The weight may change smoothly with respect to the distance, or may change stepwise with respect to the distance.

[0034] In local dimming, light source elements around a pixel with high brightness are made to emit light at high brightness. Suppose the target pixel 22 is high brightness. In this case, the emission brightness of the light source element close to the target pixel 22 is likely to be bright, and the emission brightness of the light source element far from the target pixel 22 is unlikely to be bright. And how far away the light source element is from the high brightness target pixel 22 is determined by the attenuation degree of the weight W(r). When the attenuation degree of the weight W(r) is low, not only the light source element close to the target pixel 22 but also the light source element far from the target pixel 22 is likely to be bright. In other words, when the environment is bright, the light source element relatively far from the target pixel 22 emits light brightly. On the other hand, when the attenuation degree of the weight W(r) is high, the light source element Lk far from the target pixel 22 is unlikely to be bright, and only the light source element Lk close to the target pixel 22 is likely to increase in brightness. In other words, when the environment is dark, only the light source element relatively close to the target pixel 22 emits light brightly. In this way, appropriate local dimming is performed according to the brightness of the environment. For example, in a dark environment, only light source elements relatively close to high-luminance pixels emit light, thereby reducing haloing.

[0035] There are various methods for changing the attenuation degree of the weight W(r). In a first method example, as described in FIG. 8 and subsequent drawings, the dimming circuit 150 uses a plurality of lookup tables as the attenuation rate distribution information 171, switches the lookup table according to the global dimming parameter DIMG, and determines the emission luminance of each light source element using the lookup table and the luminance information INT. The plurality of lookup tables represent attenuation rate distributions with different attenuation degrees, and the attenuation degree of the weight W(r) changes by weighting the degree of increase in the emission luminance according to the attenuation rate distribution. In this case, the lower the attenuation degree of the attenuation rate distribution represented by the lookup table, the lower the attenuation degree of the weight W(r) is, since the luminance is distributed to light source elements farther from high-luminance pixels.

[0036] Alternatively, in the second technique example, the light control circuit 150 may perform low-pass filtering and down-sampling on the luminance information INT, and use the results as the emission luminance of each light source element. A filter matrix is ​​used for the low-pass filtering, and the element values ​​of the filter matrix attenuate from the center to the periphery. The attenuation degree of the weight W(r) changes according to the attenuation degree. In other words, the lower the attenuation degree of the filter matrix, the lower the attenuation degree of the weight W(r) because the luminance is distributed to light source elements farther away from high-luminance pixels.

[0037] The dimming circuit 150 may perform global dimming in addition to the above local dimming. Specifically, the dimming circuit 150 may multiply the light emission luminance of each light source element determined according to the luminance information INT by a global dimming parameter DIMG, and output the resulting light source luminance information indicating the light emission luminance of each light source element as light source luminance data DDIM.

[0038] The color correction circuit 120 calculates illumination luminance information based on the light source luminance data DDIM from the dimming circuit 150 and the attenuation rate distribution information 171 stored in the storage unit 170. The illumination luminance information indicates the illumination luminance at each pixel of the display panel 220 when the display panel 220 is illuminated by the backlight 210. Details of the calculation of the illumination luminance will be described later with reference to FIG. 16. The color correction circuit 120 performs color correction of the image data IMA based on the illumination luminance information, and outputs the corrected image data IMB. Specifically, the color correction circuit 120 multiplies the pixel data of each pixel by the reciprocal of the luminance of the light reaching that pixel, and sets the result as new pixel data for that pixel. The image represented by the image data IMB is called an output image.

[0039] The circuit device 100 transmits image data IMB of an output image to the display driver 230 via an image interface (not shown). The image interface may be of various types, such as LVDS, a parallel RGB type, or a display port.

[0040] The color correction circuit 120, the luminance analysis circuit 130, and the light control circuit 150 are logic circuits that process digital signals. The color correction circuit 120, the luminance analysis circuit 130, and the light control circuit 150 may each be configured as a separate logic circuit, or a part or all of them may be configured as an integrated logic circuit. Alternatively, a processor such as a DSP may execute an instruction set or a program in which the functions of the color correction circuit 120, the luminance analysis circuit 130, and the light control circuit 150 are described, thereby realizing the functions of these circuits. Alternatively, the circuit device 100 may be a processor such as a CPU, a GPU, a microcomputer, a DSP, an ASIC, or an FPGA. The processor may execute an instruction set or a program in which the functions of each part of the circuit device 100 are described, thereby realizing the functions of the circuit device 100.

[0041] Figure 5 shows a first example of weighting according to the global dimming parameter. The brighter the outside light is, the larger the value of the global dimming parameter DIMG is.

[0042] The dimming circuit 150 determines whether the global dimming parameter DIMG is equal to or greater than a threshold th. When the global dimming parameter DIMG is equal to or greater than the threshold th, the dimming circuit 150 sets the attenuation degree of the weight W(r) to a first attenuation degree. When the global dimming parameter DIMG is less than the threshold th, the dimming circuit 150 sets the attenuation degree of the weight W(r) to a second attenuation degree. The second attenuation degree is higher than the first attenuation degree.

[0043] When the above-described first technique example is used, the light control circuit 150 uses a lookup table corresponding to the first degree of attenuation or the second degree of attenuation among a plurality of lookup tables that are the attenuation rate distribution information 171. Alternatively, when the second technique example is used, the light control circuit 150 sets the filter matrix of the low-pass filter to the filter matrix corresponding to the first degree of attenuation or the second degree of attenuation.

[0044] Figure 6 shows a second example of weighting according to global dimming parameters.

[0045] The dimming circuit 150 determines whether the global dimming parameter DIMG is equal to or greater than a threshold th. When the global dimming parameter DIMG is equal to or greater than the threshold th, the dimming circuit 150 sets the local dimming control to a high brightness mode, and sets the attenuation degree of the weight W(r) to an attenuation degree corresponding to the high brightness mode. When the global dimming parameter DIMG is smaller than the threshold th, the dimming circuit 150 sets the local dimming control to a halo reduction mode, and sets the attenuation degree of the weight W(r) to an attenuation degree corresponding to the halo reduction mode. The attenuation degree corresponding to the halo reduction mode is higher than the attenuation degree corresponding to the high brightness mode.

[0046] When the above-described first example technique is used, the light control circuit 150 uses a lookup table corresponding to the high brightness mode or the halo reduction mode among a plurality of lookup tables that are the attenuation rate distribution information 171. Alternatively, when the second example technique is used, the light control circuit 150 sets the filter matrix of the low-pass filter to a filter matrix corresponding to the high brightness mode or the halo reduction mode.

[0047] A halo is a phenomenon in which light bleeds into the dark areas surrounding bright areas in a high-contrast image. The light source element behind the bright area emits light at high brightness, and the light leaks out of the surrounding dark areas, causing the halo. The halo reduction mode is a mode that prioritizes halo reduction in terms of the balance between display brightness and halo reduction. The high brightness mode is a mode that prioritizes display brightness in terms of the balance between display brightness and halo reduction.

[0048] Figure 7 shows a third example of weighting according to global dimming parameters.

[0049] The dimming circuit 150 determines whether the global dimming parameter DIMG is equal to or greater than a threshold th1 and equal to or greater than a threshold th2. The threshold th1 is greater than the threshold th2. When the global dimming parameter DIMG is equal to or greater than the threshold th1, the dimming circuit 150 sets the attenuation degree of the weight W(r) to a first attenuation degree. When the global dimming parameter DIMG is less than the threshold th2, the dimming circuit 150 sets the attenuation degree of the weight W(r) to a second attenuation degree. When the global dimming parameter DIMG is less than the threshold th1 and equal to or greater than the threshold th2, the dimming circuit 150 sets the attenuation degree of the weight W(r) to a third attenuation degree. The third attenuation degree is higher than the first attenuation degree, and the second attenuation degree is higher than the third attenuation degree.

[0050] When the above-mentioned first technique example is used, the light control circuit 150 uses a lookup table corresponding to the first attenuation degree, the second attenuation degree, or the third attenuation degree, among a plurality of lookup tables that are the attenuation rate distribution information 171. Alternatively, when the second technique example is used, the light control circuit 150 sets the filter matrix of the low-pass filter to a filter matrix corresponding to the first attenuation degree, the second attenuation degree, or the third attenuation degree.

[0051] Note that the weight setting according to the global dimming parameter is not limited to the above first to third examples. For example, the attenuation degree of the weight W(r) may be set according to the global dimming parameter DIMG in more stages than in Fig. 7. Alternatively, the attenuation degree of the weight W(r) may be set continuously according to the global dimming parameter DIMG.

[0052] 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 luminance analysis circuit 130 and a dimming circuit 150. The luminance analysis circuit 130 performs luminance analysis on image data IMA of an input image and outputs luminance information INT. The dimming circuit 150 determines light source luminance information indicating the emission luminance of each of the plurality of light source elements according to the luminance information INT. The dimming circuit 150 determines the emission luminance of the light source element from the luminance information INT of the pixel using a weight W(r) according to the distance r between the pixel and the light source element. When the global dimming parameter DIMG determined by the global dimming process is a first value, the dimming circuit 150 sets the attenuation degree of the weight W(r) for the distance r to a first attenuation degree. When the global dimming parameter DIMG is a second value smaller than the first value, the dimming circuit 150 sets the attenuation degree to a second attenuation degree higher than the first attenuation degree.

[0053] In the dimming process in the local dimming control, the emission luminance of the light source element arranged around the high-luminance pixel is increased. According to the present embodiment, by changing the attenuation degree of the weight W(r) according to the distance r between the pixel and the light source element, it is possible to control how far the light source element is from the high-luminance pixel to be brightened. This allows optimal dimming for the display content or environment. Specifically, by lowering the attenuation degree of the weight W(r) when the global dimming parameter DIMG is large, the emission luminance of the light source element around the high-luminance pixel is likely to increase. This allows the display to be displayed at a high luminance when the environment is bright. On the other hand, by increasing the attenuation degree of the weight W(r) when the global dimming parameter DIMG is small, it is possible to make it difficult for the emission luminance of the light source element away from the high-luminance pixel to increase. This allows the halo that is easily noticeable when the environment is dark to be reduced.

[0054] In the examples of FIGS. 5 or 6, the first value of the global dimming parameter DIMG belongs to the value where DIMG ≧ th, and the second value belongs to the value where DIMG < th. In the example of FIG. 7, the first value belongs to the value where DIMG ≧ th1, and the second value belongs to the value where DIMG < th2.

[0055] Also, in this embodiment, when the global dimming parameter DIMG is the first value, it may be a high-brightness mode that displays at a higher brightness than the halo reduction mode. When the global dimming parameter DIMG is the second value, it may be a halo reduction mode that reduces the occurrence of halos compared to the high-brightness mode.

[0056] According to this embodiment, it can be set to the high-brightness mode when the environment is bright, and to the halo reduction mode when the environment is dark. Specifically, when the global dimming parameter DIMG is the first value, by setting the attenuation degree of the weight W(r) to the first attenuation degree, it is set to the high-brightness mode. On the other hand, when the global dimming parameter DIMG is the second value smaller than the first value, by setting the attenuation degree of the weight W(r) to the second attenuation degree higher than the first attenuation degree, it is set to the halo reduction mode.

[0057] Also, in this embodiment, when the global dimming parameter DIMG of the dimming circuit 150 is the third value, the attenuation degree of the weight W(r) may be set to the third attenuation degree. The third value is between the first value and the second value. The third attenuation degree is between the first attenuation degree and the second attenuation degree.

[0058] According to this embodiment, even when the environment has an intermediate brightness, it is possible to perform optimal dimming for display content, the environment, etc. Specifically, when the global dimming parameter DIMG is the third value between the first value and the second value, by setting the attenuation degree of the weight W(r) to the third attenuation degree between the first attenuation degree and the second attenuation degree, an intermediate display mode between the high-brightness mode and the halo reduction mode can be realized.

[0059] In the example of FIG. 7, the third value is a value that belongs to th1>DIMG≧th2.

[0060] In this embodiment, the dimming circuit 150 may determine the light source luminance information by performing global dimming processing based on the global dimming parameter DIMG on the emission luminance of each light source element determined according to the luminance information INT.

[0061] According to this embodiment, global dimming processing is performed on the light emission luminance of each light source element determined by local dimming according to the global dimming parameter DIMG. This makes it possible to combine appropriate local dimming control according to the brightness of the environment and global dimming processing. It is possible to dim the brightness of the entire screen according to the brightness of the environment while improving the display quality, such as reducing halos, by appropriate local dimming control according to the brightness of the environment.

[0062] 3. Dimming circuit Below, we will explain configuration examples of the dimming circuit and the color correction circuit when the attenuation degree of the weight W(r) is set in the above-mentioned first method example, that is, when multiple lookup tables are used as attenuation rate distribution information.

[0063] Fig. 8 shows an example of the detailed configuration of the circuit device. Descriptions of components that are the same as those described in Fig. 2 will be omitted where appropriate.

[0064] In this configuration example, the storage unit 170 stores a lookup table indicating the attenuation rate distribution of light reaching the display panel from the light source element as attenuation rate distribution information 171. Fig. 2 shows an example in which the storage unit 170 stores three types of lookup tables LUTA, LUTB, and LUTC having different attenuation rate distributions. However, the number of lookup tables may be two or more.

[0065] The dimming circuit 150 reads out one of the lookup tables LUTA, LUTB, or LUTC from the storage unit 170 according to the global dimming parameter DIMG. The dimming circuit 150 performs dimming processing using the luminance information INT and the lookup table read out from the storage unit 170 to determine 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 DDIM.

[0066] The color correction circuit 120 reads out from the storage unit 170 a lookup table used to calculate the illumination luminance among the lookup tables LUTA, LUTB, and LUTC. Note that a lookup table used to calculate the illumination luminance may be prepared separately from the lookup tables LUTA, LUTB, and LUTC corresponding to the mode. The color correction circuit 120 calculates the luminance of the light illuminating each pixel of the display panel 220 based on the light source luminance data DDIM and the lookup table read out from the storage unit 170. The color correction circuit 120 multiplies the pixel data of each pixel in the image data IMA by the reciprocal of the luminance of the light illuminating that pixel, and sets the result as the pixel data of the image data IMB.

[0067] The lookup tables LUTA, LUTB, and LUTC output attenuation rate information associated with the input distance information. In the following, an example is shown in which the distance information is the square of the distance, and the attenuation rate information is an attenuation rate expressed as a percentage, but the present invention is not limited to this. The distance information may be the distance or the number of pixels, etc. The attenuation rate information may be an attenuation rate expressed in any unit.

[0068] FIG. 9 shows an example of the lookup table LUTA. The lookup table LUTA is a function of the decay rate distribution lsf 0 The multiplier on the right side of the lsf means the power of the lsf. Figure 10 shows an example of the decay rate distribution of the lookup table LUTA.

[0069] The light from the light source element is diffused by a diffusion sheet or the like, and the diffused light is irradiated onto the display panel. At this time, the luminance distribution of the light due to the diffusion is the attenuation rate distribution. However, the attenuation rate distribution used when calculating the emission luminance of the light source element does not have to be an actual attenuation rate distribution, and may be a virtual attenuation rate distribution programmed for calculating the emission luminance. Figures 9 and 10 show an example of an attenuation rate distribution with flat characteristics.

[0070] As shown in FIG. 9, the lookup table LUTA includes a lookup table LUTA1 in which the square of the distance is stored, and a lookup table LUTA2 in which the attenuation factor is stored.

[0071] Each index in the lookup table LUTA1 stores the square of the distance associated with that index. Here, an example is shown in which the indexes are 0 to 10, but the number of indexes is arbitrary. Also, an example is shown in which the distances are spaced equally in the range of 0 to 100, but the distance range is arbitrary and the spaces do not have to be equal. An index is, for example, a memory address.

[0072] Each index in the lookup table LUTA2 stores an attenuation rate associated with that index. The attenuation rate is expressed as a normalized value with the maximum luminance set to 100%. Attenuation rate distribution lsf 0 At , the decay rate of all indices is 100%.

[0073] For example, when the square of the distance is 300, the light control circuit 150 sequentially reads out the square of the distance for each index from the lookup table LUTA1 and compares it with 300 to determine indexes 1 and 2 corresponding to 100 and 400 on either side of 300. The light control circuit 150 reads out the attenuation rates of 100% and 100% for indexes 1 and 2 from the lookup table LUTA2, and determines the attenuation rate corresponding to the square of the distance, 300, by interpolation. Here, the distribution characteristic is flat, so the attenuation rate after interpolation is 100%.

[0074] FIG. 11 shows an example of the lookup table LUTB. The lookup table LUTB is a decay rate distribution lsf 1 FIG. 12 shows an example of the decay rate distribution of the lookup table LUTB. 1 is an example of a real attenuation rate distribution or an approximate attenuation rate distribution, but may be a virtual attenuation rate distribution programmed for calculating the light source luminance. 1 Here is an example where is a Gaussian distribution:

[0075] 11, the lookup table LUTB includes a lookup table LUTB1 in which the square of the distance is stored, and a lookup table LUTB2 in which the attenuation factor is stored. The contents of the lookup table and the method of reference are similar to those of the lookup table LUTA.

[0076] FIG. 13 shows an example of the lookup table LUTC. The lookup table LUTC is a decay rate distribution lsf 2 FIG. 14 shows an example of the decay rate distribution of the lookup table LUTC. 2 is an example of a distribution obtained by squaring the actual attenuation rate distribution, and is a virtual attenuation rate distribution. However, the attenuation rate distribution lsf 2 is not limited to the distribution obtained by squaring the actual attenuation rate distribution, but may be an arbitrary programmed distribution.

[0077] 13, the lookup table LUTC includes a lookup table LUTC1 in which the square of the distance is stored, and a lookup table LUTC2 in which the attenuation factor is stored. The contents of the lookup table and the method of reference are similar to those of the lookup table LUTA.

[0078] The attenuation rate distribution of the lookup table LUTB has a higher degree of attenuation with respect to distance than the attenuation rate distribution of the lookup table LUTA. The attenuation rate distribution of the lookup table LUTC has a higher degree of attenuation with respect to distance than the attenuation rate distribution of the lookup table LUTB. With regard to the attenuation rate distribution, "high degree of attenuation with respect to distance" means that the distance at which the attenuation rate decreases to a predetermined attenuation rate is short. The predetermined attenuation rate may be any attenuation rate, for example, within a range of 50% to 0%. Alternatively, "high degree of attenuation with respect to distance" means that the decrease in the attenuation rate is large with respect to the change in distance in the direction in which the distance increases. Alternatively, "high degree of attenuation with respect to distance" means that the spread of light represented by the attenuation rate distribution is relatively narrow. Although attenuation rate distributions that change smoothly with respect to distance are shown in Figs. 9 to 14, the attenuation rate distribution may change stepwise with respect to distance. Although one-dimensional lookup tables are shown in Figs. 9 to 14, two-dimensional lookup tables may be used.

[0079] Fig. 15 shows a flow of the process performed by the dimming circuit. In the following, an example of switching between the halo reduction mode and the high brightness mode according to the global dimming parameter DIMG will be described. However, the mode may be switched in more stages according to the global dimming parameter DIMG, or the mode may be switched continuously.

[0080] In step S1, the dimming circuit 150 determines whether the global dimming parameter DIMG is equal to or greater than the threshold th. If the global dimming parameter DIMG is equal to or greater than the threshold th, the dimming circuit 150 sets the high brightness mode, and selects the lookup table LUTA or LUTB in step S2. If the global dimming parameter DIMG is not equal to or greater than the threshold th, the dimming circuit 150 sets the halo reduction mode, and selects the lookup table LUTC in step S3.

[0081] In step S4, the light control circuit 150 initializes the light source luminance information. For example, the luminance values ​​of all light sources are initialized to zero.

[0082] In step S5, the light control circuit 150 selects one pixel from the pixels included in the luminance information INT. The selected pixel is referred to as the target pixel. In the loop from step S5 to step S8, the target pixels are selected sequentially. For example, in the initial step S5, the first pixel of the first scan line of the image data IMA is selected, and in the subsequent steps S5, the second pixel, the third pixel, ... are selected sequentially. When all the pixels of the first scan line are selected, the pixels of the second scan line are selected sequentially, and this is repeated up to the final scan line.

[0083] In step S6, the light control circuit 150 selects n×m light source elements around the target pixel. These n×m light source elements are also called surrounding light source elements. FIG. 4 above shows an example where n=4 and m=4. The light control circuit 150 selects light source elements L1 to L16 in the two nearest columns in the +x direction and the -x direction, and the two nearest rows in the +y direction and the -y direction, based on the position (i, j) of the target pixel 22. When k is an integer between 1 and 16, the position of the light source element Lk is expressed as (xk, yk).

[0084] In step S7, the light source luminance information for each of the n x m light source elements selected in step S6 is updated using the pixel value of the target pixel 22 in the image data IMA and the lookup table selected in step S2 or S3.

[0085] In step S8, the light adjustment circuit 150 determines whether or not all pixels have been selected as target pixels. If all pixels have been selected, the process ends. If there are any unselected pixels, the process returns to step S5.

[0086] The update process of the light source luminance information in step S7 will be described using the example of Fig. 4. Here, it is assumed that the number of pixels of the luminance information INT is the same as the number of pixels of the display panel 220. The light adjustment circuit 150 updates the light source luminance information INT by a requested change amount Δ ijis calculated using the following equations (1) and (2).

[0087]

number

[0088]

number

[0089] In the above formula (1), INT ij is the luminance value of the target pixel 22 in the luminance information INT. As shown in the above formula (2), lsf(k) is the attenuation rate of light that the light source element Lk illuminates the target pixel 22. In the above formula (2), the square of the distance is used as an argument, but the distance may also be used as an argument. The light control circuit 150 obtains lsf(k) using a lookup table LUTB. powc(k) is the previous light source luminance information of the light source element Lk. The previous light source luminance information is light source luminance information calculated using the previous target pixel selected immediately before the current target pixel 22. The previous target pixel is the pixel at the position (i-1, j) immediately before the position (i, j) in the x direction.

[0090] The dimming circuit 150 calculates the required change amount Δ ij The light source luminance information of the light source element Lk is updated by distributing Δ ij When k is >0, the denominator of the second term is the same regardless of k, so the required change Δ ij LSF x Weighted by (k). lsf x (k) is the attenuation rate distribution information selected according to the mode. For example, in the flow of FIG. 15, x=0 or 1 is selected in the high brightness mode, and x=2 is selected in the halo reduction mode. The larger x is, the faster the attenuation rate distribution attenuates. Therefore, the requested change amount Δ ij is easily distributed to the light source element far from the target pixel 22, ijThis makes it difficult for the light source luminance of light source elements far from high-luminance pixels to increase, resulting in a reduction in haloes.

[0091]

number

[0092]

number

[0093] In the above formula (3), powu(k) is the current light source luminance information, that is, the updated light source luminance information. As shown in the above formula (4), lsf x (k) is the attenuation rate of light that the light source element Lk illuminates the target pixel 22. In the above formula (4), the square of the distance is used as an argument, but the distance may be used as an argument. x is an integer equal to or greater than 0. In the examples of Figs. 9 to 14, x = 0, 1, and 2. That is, when x = 0, the light control circuit 150 refers to the lookup table LUTA to calculate lsf 0 (k), and when x=1, refer to the lookup table LUTB to find lsf 1 (k), and when x=2, refer to the lookup table LUTC to find lsf 2 Find (k).

[0094] In this embodiment, the storage unit 170 may store a plurality of pieces of attenuation rate distribution information indicating the attenuation rate distribution of light with respect to the distance when the light source element illuminates the pixel. When the global dimming parameter DIMG is a first value, the dimming circuit 150 may set the weight W(r) based on first attenuation rate distribution information among the plurality of pieces of attenuation rate distribution information. When the global dimming parameter DIMG is a second value, the dimming circuit 150 may set the weight W(r) based on second attenuation rate distribution information among the plurality of pieces of attenuation rate distribution information, the attenuation rate distribution of which is different from that of the first attenuation rate distribution information.

[0095] According to this embodiment, the attenuation rate distribution information corresponding to the global dimming parameter DIMG is selected from a plurality of pieces of attenuation rate distribution information having mutually different attenuation rate distributions, thereby making it possible to set the attenuation degree of the weight W(r).

[0096] 8 to 15, the plurality of pieces of attenuation rate distribution information correspond to the lookup tables LUTA, LUTB, and LUTC. In the flow example of FIG. 15, the first attenuation rate distribution information corresponds to the lookup table LUTA or LUTB, and the second attenuation rate distribution information corresponds to the lookup table LUTC. Also, the weight W(r) is expressed by the requested change amount Δ ij This coefficient corresponds to the coefficient of lsf x (k) is included. That is, the weight W(r) is set based on the attenuation rate distribution information.

[0097] Furthermore, in this embodiment, the attenuation rate distribution of the second attenuation rate distribution information has a higher degree of attenuation of light with respect to distance than the attenuation rate distribution of the first attenuation rate distribution information.

[0098] By performing local dimming using attenuation rate distribution information in which the degree of attenuation of light with respect to distance is high, the degree of attenuation of the weight W(r) can be increased. That is, when the global dimming parameter DIMG is a second value smaller than the first value, the degree of attenuation of the weight W(r) is set to a second attenuation degree higher than the first attenuation degree.

[0099] 4.Color correction circuit FIG. 16 is a flow chart showing the illumination luminance calculation process performed by the color correction circuit.

[0100] In step S11, the color correction circuit 120 selects one pixel from the pixels included in the image data IMA. The selected pixel is referred to as the target pixel. In the loop from step S11 to step S14, the target pixels are selected sequentially. For example, in the first step S11, the first pixel of the first scan line of the image data IMA is selected, and in the subsequent steps S11, the second pixel, the third pixel, ... are selected sequentially. When all the pixels of the first scan line have been selected, the pixels of the second scan line are selected sequentially, and this is repeated up to the final scan line.

[0101] In step S12, the color correction circuit 120 selects s×t light source elements around the target pixel. Each of s and t may be an integer equal to or greater than 2. The number s×t may be the same as the number n×m in FIG. 4, or may be different. Also, illumination luminance information may be obtained from all light source elements, rather than from the number s×t light source elements.

[0102] In step S13, the color correction circuit 120 obtains the illumination luminance information of the target pixel using the light source luminance information of the selected s×t light source elements and a lookup table for illumination luminance calculation. Specifically, the color correction circuit 120 obtains the illumination luminance information of the target pixel by the following formula (5).

[0103]

number

[0104] In the above formula (5), 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. That is, powu in the above formula (3) after the loop of steps S5 to S8 in FIG. 15 is executed up to the last pixel of the luminance information INT is used as pow in the above formula (5). Even if the loop of steps S5 to S8 is not executed up to the last pixel of the luminance information INT, the update of the light source luminance information of the light source element is sequentially completed as the target pixel proceeds, so the light source luminance information after the update may be used as pow. The color correction circuit 120 obtains lsf(β) using the lookup table LUTB.

[0105] In step S14, the color correction circuit 120 determines whether or not all pixels have been selected as target pixels. If all pixels have been selected, the process ends. If there are any unselected pixels, the process returns to step S11.

[0106] Although the present embodiment has been described in detail as above, it will be easily understood by those skilled in the art that many modifications are possible without substantially departing from the novel matters and effects of the present disclosure. Therefore, all such modifications are intended to be included in the scope of the present disclosure. For example, a term described at least once in the specification or drawings together with a different term having a broader meaning or synonymy can be replaced with that different term anywhere in the specification or drawings. In addition, all combinations of the present embodiment and modifications are also included in the scope of the present disclosure. In addition, the configurations and operations of the circuit device, backlight, display device, display system, processing device, electronic device, etc. are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0107] 22... target pixel, 100... circuit device, 120... color correction circuit, 130... luminance analysis circuit, 131... luminance extraction unit, 132... downsampling unit, 140... light source luminance determination circuit, 150... dimming circuit, 170... memory unit, 171... attenuation rate distribution information, 200... display device, 210... backlight, 220... display panel, 230... display driver, 240... light source driver, 300... processing device, 400... display system, 500... electronic device, DIMG... global dimming parameter, IMA, IMB... image data, INT... luminance information, L1 to L16... light source element, LUTA, LUTB, LUTC... lookup table, W(r)... weight

Claims

1. A circuit device for controlling a display device including a plurality of light source elements and a display panel, a luminance analysis circuit that performs luminance analysis on image data of an input image and outputs luminance information; a light control circuit that determines light source luminance information indicating the luminance of light emitted by each of the plurality of light source elements according to the luminance information; Including, The dimming circuit includes: determining the emission luminance of the light source element from the luminance information of the pixel using a weight according to the distance between the pixel and the light source element; When a global dimming parameter determined by the global dimming process is a first value, a decay rate of the weight with respect to the distance is set to a first decay rate; a circuit device for setting the degree of attenuation to a second degree of attenuation higher than the first degree of attenuation when the global dimming parameter is a second value smaller than the first value;

2. 2. The circuit device according to claim 1, a storage unit that stores a plurality of pieces of attenuation rate distribution information indicating a distribution of attenuation rates of light with respect to the distance when the light source element illuminates the pixel; The dimming circuit includes: When the global dimming parameter is the first value, the weight is set based on a first attenuation rate distribution information among the plurality of attenuation rate distribution information; When the global dimming parameter is the second value, the weight is set based on second attenuation rate distribution information among the plurality of attenuation rate distribution information, the second attenuation rate distribution information having an attenuation rate distribution different from that of the first attenuation rate distribution information.

3. 3. The circuit device according to claim 2, A circuit device, characterized in that the attenuation rate distribution of the second attenuation rate distribution information has a higher degree of light attenuation with respect to the distance than the attenuation rate distribution of the first attenuation rate distribution information.

4. 2. The circuit device according to claim 1, a high brightness mode in which, when the global dimming parameter is the first value, the display is displayed at a higher brightness than in the halo reduction mode; A circuit device characterized in that, when the global dimming parameter is the second value, the halo reduction mode reduces the occurrence of a halo compared to the high brightness mode.

5. 2. The circuit device according to claim 1, The dimming circuit includes: A circuit device characterized in that, when the global dimming parameter is a third value between the first value and the second value, the attenuation degree is set to a third attenuation degree between the first attenuation degree and the second attenuation degree.

6. 2. The circuit device according to claim 1, The dimming circuit includes: A circuit device characterized in that the light source luminance information is determined by performing the global dimming process based on the global dimming parameter on the emission luminance of each of the light source elements determined in accordance with the luminance information.

7. 2. The circuit device according to claim 1, a color correction circuit for correcting the color of the image data based on the light source luminance information.

8. 2. The circuit device according to claim 1, A circuit device, wherein the global dimming parameter is a parameter that is set to a larger value as the environment becomes brighter or the luminance of the input image becomes higher.

9. A circuit arrangement according to any one of claims 1 to 8; The display device; A display system comprising:

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