Circuit device and display system

Abstract

The invention provides a circuit device and a display system. The circuit device comprises a brightness analysis circuit and a dimming circuit. The luminance analysis circuit performs luminance analysis on image data of an input image and outputs luminance information. The dimming circuit determines, on the basis of the luminance information, light source luminance information indicating the luminance of light emitted by each of the plurality of light source elements. The dimming circuit uses a weight corresponding to the distance between the pixel and the light source element, and determines the light emission brightness of the light source element according to the brightness information of the pixel. When the global dimming parameter is a first value, the dimming circuit sets the degree of attenuation of the weight with respect to the distance to a first degree of attenuation. When the global dimming parameter is a second value smaller than the first value, the dimming circuit sets the degree of attenuation to a second degree of attenuation higher than the first degree of attenuation.

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 backlight display device that changes the driving value of LEDs to reduce abrupt changes in backlight in dark areas in order to avoid or reduce artifacts caused by the halo effect.

[0003] Patent Document 1: Japanese Patent Application No. 2012-516458

[0004] By reducing the brightness of the light emitting element that emits light to the display panel, the halo caused by the light can be reduced. However, since the reduction of halo has a trade-off relationship with the reduction of the brightness of the display panel, it may not be possible to perform dimming that is most suitable for the display content or environment. Summary of the invention

[0005] One embodiment of the present disclosure relates to a circuit device that controls a display device including a display panel and multiple light source elements, the circuit device including: a brightness analysis circuit that performs brightness analysis on image data of an input image and outputs brightness information; and a dimming circuit that determines light source brightness information representing the luminous brightness of each of the multiple light source elements based on the brightness information, the dimming circuit using a weight corresponding to a distance between a pixel and a light source element, and determining the luminous brightness of the light source element based on the brightness information of the pixel, and when a global dimming parameter determined by a global dimming process is a first value, the dimming circuit sets the attenuation degree of the weight relative to the distance to a first attenuation degree, and when the global dimming parameter is a second value smaller than the first value, the dimming circuit sets the attenuation degree to a second attenuation degree that is higher than the first attenuation degree.

[0006] In addition, another aspect of the present disclosure relates to a display system including the above-mentioned circuit device and the above-mentioned display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a structural example of an electronic device.

[0008] Figure 2 This is a structural example of a circuit device.

[0009] Figure 3 This is a detailed configuration example of a brightness analysis circuit.

[0010] Figure 4 This is a diagram for explaining the processing performed by the dimming circuit.

[0011] Figure 5This is the first example of weight setting corresponding to the global dimming parameter.

[0012] Figure 6 This is the second example of weight setting corresponding to the global dimming parameter.

[0013] Figure 7 This is the third example of weight setting corresponding to the global dimming parameters.

[0014] Figure 8 This is a detailed configuration example of a circuit device.

[0015] Fig. 9 is an example of a lookup table LUTA.

[0016] Fig.10 is an example of the attenuation rate distribution of the lookup table LUTA.

[0017] Fig.11 is an example of a lookup table LUTB.

[0018] Fig.12 is an example of the attenuation rate distribution of the lookup table LUTB.

[0019] Fig.13 is an example of a lookup table LUTC.

[0020] Fig.14 is an example of a decay rate distribution of a lookup table LUTC.

[0021] Fig.15 This is the process flow performed by the dimming circuit.

[0022] Fig.16 This is the flow of the illumination brightness calculation processing performed by the color correction circuit.

[0023] Description of symbols

[0024] 22: object pixel; 100: circuit device; 120: color correction circuit; 130: brightness analysis circuit; 131: brightness extraction unit; 132: downsampling unit; 150: dimming circuit; 170: storage unit; 171: attenuation rate distribution information; 200: display device; 210: backlight source; 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: brightness information; L1~L16: light source elements; LUTA, LUTB, LUTC: lookup table; W(r): weight. DETAILED DESCRIPTION

[0025] Hereinafter, preferred embodiments of the present disclosure will be described in detail. In addition, the present embodiments described below do not unduly limit the contents described in the claims, and all the structures described in the present embodiments are not necessarily essential structural elements.

[0026] 1. Electronic equipment, display systems and circuit devices

[0027] Figure 1 The electronic device 500 includes a processing device 300 and a display system 400. As an example, the electronic device 500 is a vehicle-mounted display device including an instrument panel, a central information display, a head-up display, or an electronic mirror, a television device, or an information processing device including a display.

[0028] 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. Figure 1 Although the circuit device 100 and the display device 200 are described as different components, the circuit device 100 may be included in the display device 200 .

[0029] The display device 200 includes a backlight source 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 or an information processing device. Alternatively, the display device 200 may be a head-mounted display including a projection device to the eyes or a head-up display including a projection device to the 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 source 210 and passing through the display panel 220 onto the screen.

[0030] In a top view of the backlight source 210, light source elements are arranged two-dimensionally in the backlight source 210. The light source element is a light-emitting element that emits light by supplying power, such as an inorganic light-emitting diode or an organic light-emitting diode. In local dimming control, the light amount of each light source element arranged two-dimensionally is controlled independently of each other. Alternatively, the backlight source 210 may also be divided into a plurality of areas. In a top 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 amount of each area is controlled independently of each other.

[0031] An example of a two-dimensional configuration of light source elements is a square configuration 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 configuration. For example, the two-dimensional configuration may also be a configuration called a diamond configuration or a staggered configuration. In this configuration, light source elements are arranged at the intersections of one side of the odd-numbered rows and the even-numbered rows and the odd-numbered columns, and at the intersections of the other side of the odd-numbered rows and the even-numbered rows and the even-numbered columns, and no light source elements are arranged at other intersections.

[0032] The light source driver 240 receives the light source brightness data DDIM from the circuit device 100 and drives each light source element of the backlight source 210 according to the light source brightness data DDIM. The light source driver 240 is, for example, an integrated circuit device. In addition, a plurality of light source drivers may be provided, each of which is an independent integrated circuit device.

[0033] The display panel 220 is an electro-optical panel that transmits light from the backlight 210 and displays an image by controlling its transmittance. For example, the display panel 220 is a liquid crystal display panel.

[0034] The display driver 230 receives the 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 the timing control signal, thereby causing the display panel 220 to display an image.

[0035] The processing device 300 sends the image data IMA to the circuit device 100. In addition, the processing device 300 performs global dimming processing based on information on the amount of ambient light detected by an external light sensor, etc., and sends the result as a global dimming parameter DIMG to the circuit device 100. The processing device 300 may also perform global dimming processing based on the brightness of the image represented by the image data IMA. The global dimming parameter is, for example, greater than 0 and less than 1, and is the same for the entire backlight source 210. The processing device 300 is a processor such as a CPU, GPU, a microcomputer, a DSP, an ASIC, or an FPGA. CPU is the abbreviation of Central Processing Unit. GPU is the abbreviation of Graphics Processing Unit. DSP is the abbreviation of Digital Signal Processor. ASIC is the abbreviation of Application Specific Integrated Circuit. FPGA is the abbreviation of Field Programmable Gate Array.

[0036] 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 dims the light emitting brightness of each light source element or each area of ​​the backlight source 210 according to the brightness of the image data IMA, and outputs the light source brightness information obtained by the dimming as the light source brightness data DDIM to the light source driver 240. In addition, the circuit device 100 performs color correction on the image data IMA based on the light source brightness information, and outputs the color-corrected image data IMB to the display driver 230.

[0037] In addition, the circuit device 100 has a built-in display controller function. That is, the circuit device 100 sends the image data IMB and the timing control signal for controlling the display timing to the display driver 230. In addition, the circuit device 100 may also perform image processing such as grayscale correction, white balance correction, or zooming in and out for the image data IMA or the image data IMB. In addition, the circuit device 100 may not have a built-in display controller function, but may provide a display controller as an integrated circuit device different from the circuit device 100. In this case, the display controller may also be included in the display device 200. In addition, the display controller and the display driver 230 may be respectively composed of different integrated circuit devices, or may be composed of an integrated integrated circuit device.

[0038] 2. Configuration example of circuit device

[0039] In the following, illustration and description of the display controller function built into the circuit device 100 are omitted, and dimming and color correction are illustrated and described.

[0040] Figure 2 The circuit device 100 includes a color correction circuit 120 , a brightness analysis circuit 130 , a dimming circuit 150 , and a storage unit 170 .

[0041] 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 of Random Access Memory. OTP is an abbreviation of One Time Programmable. EEPROM is an abbreviation of Electrically ErasableProgrammable Read Only Memory.

[0042] 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 illuminating the pixel by the light source element. The attenuation rate distribution is also called attenuation characteristics or brightness distribution. The attenuation rate distribution information 171 is, for example, a lookup table or function representing the attenuation rate distribution. In the case where the function is a polynomial, the attenuation rate distribution information 171 may also be the coefficients of each term of the polynomial.

[0043] The circuit device 100 receives image data IMA from the processing device 300 via an image interface (not shown). The image represented by the image data IMA is referred to as an input image. The image interface method may be various methods such as LVDS, parallel RGB method or display port. LVDS is the abbreviation of Low Voltage Differential Signaling.

[0044] The received image data IMA is input to the brightness analysis circuit 130. The brightness analysis circuit 130 analyzes the brightness of the image data IMA and outputs the result as brightness information INT. The brightness information INT indicates the brightness of the image at each position of the input image. Figure 3 A detailed configuration example of the brightness analysis circuit is shown below. The brightness analysis circuit 130 includes a brightness extraction unit 131 and a down-sampling unit 132 .

[0045] 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 brightness extraction unit 131 uses the maximum value among the R pixel value, the G pixel value, and the B pixel value as the brightness value of the pixel. Thus, a first brightness image is obtained in which each pixel has a brightness value.

[0046] The downsampling unit 132 downsamples the first brightness image to obtain a second brightness image. The number of pixels of the second brightness image is less than the number of pixels of the first brightness image. Downsampling can be performed in at least one of the horizontal scanning direction and the vertical scanning direction. As an example, the number of pixels in both the horizontal scanning direction and the vertical scanning direction is downsampled to less than 1 / 2. The downsampling unit 132 outputs the second brightness image as brightness information INT.

[0047] In addition, the structure of the brightness analysis circuit 130 is not limited to the above structure. For example, the downsampling unit 132 may be omitted and the first brightness image may be output as the brightness information INT. Alternatively, the brightness extraction unit 131 may obtain the first brightness image by multiplying the RGB pixel values ​​by coefficients based on Y in the YCrCb space or the like.

[0048] The dimming circuit 150 generates light source brightness information indicating the light emission brightness of each light emitting element based on the brightness information INT and the global dimming parameter DIMG, and outputs the light source brightness information as light source brightness data DDIM. Figure 1 As described in , 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 to obtain the global dimming parameter DIMG.

[0049] Figure 4 An explanatory diagram showing the processing performed by the dimming 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, the number of pixels of the brightness information INT is the same as the number of pixels of the display panel 220. In addition, even in the case of downsampling, the coordinates and distances on the display panel 220 can be considered based on the correspondence between the coordinates in the downsampled brightness information INT and the coordinates on the display panel 220.

[0050] The object pixel 22 is any pixel in the brightness information INT. Let the coordinates of the pixel be (i, j). The dimming circuit 150 determines the brightness of the n×m light source elements around the object pixel 22 according to the brightness information INT(i, j) of the object pixel 22. n and m can be integers greater than 2. Figure 4 , an example of n=m=4 is shown. The 4×4 light source elements are L1 to L16. Let k be an integer greater than 1 and less than 16, and the light source element is represented by Lk. The dimming circuit 150 uses the weight W(r) corresponding to the distance r between the target pixel 22 and the light source element Lk to determine the light emission brightness of the light source element Lk based on the brightness information of the target pixel 22. If the coordinates of the light source element Lk are (xk, yk), for example, r 2 =(i-xk) 2 +(j-yk) 2 .exist Figure 4 FIG. 4 illustrates W(r) by taking k=6 as an example.

[0051] The weight W(r) decreases as the distance r increases. The dimming circuit 150 changes the attenuation degree of the weight W(r) relative to the distance r according to the global dimming parameter DIMG. Specifically, when the global dimming parameter DIMG is large, the environment is bright or the brightness of the image represented by the image data IMA is high. In this case, the dimming circuit 150 reduces the attenuation degree of the weight W(r) relative to the distance r. On the other hand, when the global dimming parameter DIMG is small, the environment is dark or the brightness of the image represented by the image data IMA is low. In this case, the dimming circuit 150 increases the attenuation degree of the weight W(r) relative to the distance r. The dimming circuit 150 determines the luminous brightness of the light source element Lk based on the brightness information INT(i, j) of the object pixel 22, and the weight W(r) is the weight to determine how bright the luminous brightness is.

[0052] In addition, regarding the weight, "high attenuation relative to distance" means that the distance until the weight decreases to the specified value is short. The specified value can be arbitrary, for example, in the range of half the maximum value to zero. Alternatively, "high attenuation relative to distance" means that the weight decreases greatly relative to the distance change in the direction of increasing distance. The weight can change smoothly relative to the distance, or it can change in stages relative to the distance.

[0053] In local dimming, the light source elements around the high-brightness pixel are made to emit light at high brightness. Assume that the object pixel 22 is high-brightness. At this time, the light emission brightness of the light source element close to the object pixel 22 is easy to become bright, and the light emission brightness of the light source element far from the object pixel 22 is difficult to become bright. Moreover, the degree of attenuation of the weight W(r) determines to what extent the light source element far from the high-brightness object pixel 22 becomes bright. When the attenuation degree of the weight W(r) is low, not only the light source element close to the object pixel 22 is easy to become bright, but also the light source element far from the object pixel 22 is easy to become bright. That is, in the case of bright environment, the light source element relatively far from the object pixel 22 also emits brightly. On the other hand, when the attenuation degree of the weight W(r) is high, the light source element Lk far from the object pixel 22 is difficult to become bright, and only the brightness of the light source element Lk close to the object pixel 22 is easy to increase. That is, in the case of dark environment, only the light source element relatively close to the object pixel 22 emits brightly. Thus, appropriate local dimming is performed according to the brightness of the environment. For example, in a dark environment, halation can be reduced by emitting light only from light source elements that are relatively close to high-brightness pixels.

[0054] In addition, various methods of changing the attenuation degree of the weight W(r) are considered. In the first method example, Figure 8As described later, the dimming circuit 150 uses a plurality of lookup tables as attenuation rate distribution information 171, switches the lookup table according to the global dimming parameter DIMG, and uses the lookup table and the brightness information INT to determine the luminous brightness of each light source element. The plurality of lookups show attenuation rate distributions with different attenuation degrees, and the attenuation degree of the weight W(r) is changed by weighting the enhancement degree of the luminous brightness 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 more brightness is allocated to the light source element away from the pixel with high brightness, and therefore the attenuation degree of the weight W(r) is lower.

[0055] Alternatively, in the second method example, the dimming circuit 150 may also perform low-pass filtering and down-sampling processing on the brightness information INT, and use the result as the luminous brightness of each light source element. A filter matrix is ​​used in the low-pass filtering process, but the values ​​of the elements of the filter matrix decay from the center to the periphery. The degree of decay of the weight W(r) varies according to the degree of decay. That is, the lower the degree of decay of the filter matrix, the more the brightness is distributed to the light source element away from the pixel with high brightness, and therefore the degree of decay of the weight W(r) is lower.

[0056] In addition, the dimming circuit 150 may perform global dimming in addition to the above-mentioned local dimming. Specifically, the dimming circuit 150 may multiply the luminous brightness of each light source element determined according to the brightness information INT by the global dimming parameter DIMG, and output the resulting light source brightness information representing the luminous brightness of each light source element as the light source brightness data DDIM.

[0057] The color correction circuit 120 calculates the illumination brightness information based on the light source brightness data DDIM from the dimming circuit 150 and the attenuation rate distribution information 171 stored in the storage unit 170. The illumination brightness information indicates the illumination brightness of each pixel of the display panel 220 when the display panel 220 is illuminated by the backlight source 210. Fig.16 The calculation of illumination brightness is described in detail. The color correction circuit 120 performs color correction on the image data IMA based on the illumination brightness information and outputs the corrected image data IMB. Specifically, the color correction circuit 120 multiplies the pixel data of each pixel by the inverse of the brightness of the light reaching the pixel and uses the result as the new pixel data of the pixel. In addition, the image represented by the image data IMB is called an output image.

[0058] The circuit device 100 transmits the image data IMB of the output image to the display driver 230 via an image interface (not shown). The image interface may be of various types such as LVDS, parallel RGB, or display port.

[0059] In addition, the color correction circuit 120, the brightness analysis circuit 130, and the dimming circuit 150 are logic circuits for processing digital signals. The color correction circuit 120, the brightness analysis circuit 130, and the dimming circuit 150 can be respectively composed of logic circuits, and part or all of them can also be composed of an integrated logic circuit. Alternatively, the functions of these circuits can be realized by executing an instruction set or program that describes the functions of the color correction circuit 120, the brightness analysis circuit 130, and the dimming circuit 150 through a processor such as a DSP. Alternatively, the circuit device 100 can also be a processor such as a CPU, a GPU, a microcomputer, a DSP, an ASIC, or an FPGA. Moreover, it is also possible that the processor realizes the functions of the circuit device 100 by executing an instruction set or program that describes the functions of each part of the circuit device 100.

[0060] Figure 5 This is a first example of weight setting corresponding to the global dimming parameter. The brighter the external light, the larger the value of the global dimming parameter DIMG.

[0061] The dimming circuit 150 determines whether the global dimming parameter DIMG is greater than the threshold value th. When the global dimming parameter DIMG is greater than the threshold value th, the dimming circuit 150 sets the attenuation degree of the weight W(r) to the first attenuation degree. When the global dimming parameter DIMG is less than the threshold value th, the dimming circuit 150 sets the attenuation degree of the weight W(r) to the second attenuation degree. The second attenuation degree is higher than the first attenuation degree.

[0062] When the first method example is used, the dimming circuit 150 uses a lookup table corresponding to the first attenuation level or the second attenuation level among the plurality of lookup tables as the attenuation rate distribution information 171. Alternatively, when the second method example is used, the dimming circuit 150 sets the filter matrix of the low-pass filter to the filter matrix corresponding to the first attenuation level or the second attenuation level.

[0063] Figure 6 This is the second example of weight setting corresponding to the global dimming parameter.

[0064] The dimming circuit 150 determines whether the global dimming parameter DIMG is greater than the threshold value th. When the global dimming parameter DIMG is greater than the threshold value th, the dimming circuit 150 sets the local dimming control to the high brightness mode, and sets the attenuation degree of the weight W(r) to the attenuation degree corresponding to the high brightness mode. When the global dimming parameter DIMG is less than the threshold value th, the dimming circuit 150 sets the local dimming control to the halo reduction mode, and sets the attenuation degree of the weight W(r) to the 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.

[0065] When the first method example is used, the dimming circuit 150 uses a lookup table corresponding to the high brightness mode or the halo reduction mode among the plurality of lookup tables as the attenuation rate distribution information 171. Alternatively, when the second method example is used, the dimming circuit 150 sets the filter matrix of the low-pass filter to the filter matrix corresponding to the high brightness mode or the halo reduction mode.

[0066] In addition, halo refers to the phenomenon that light bleeds into the dark area around the bright area in a high-contrast image. The light source element behind the bright area emits light at a high brightness, so the light leaks from the surrounding dark area and produces halo. The reduced halo mode is a mode that emphasizes reducing halo in the balance between display brightness and reducing halo. The high brightness mode is a mode that emphasizes display brightness in the balance between display brightness and reducing halo.

[0067] Figure 7 This is the third example of weight setting corresponding to the global dimming parameters.

[0068] The dimming circuit 150 determines whether the global dimming parameter DIMG is greater than or equal to the threshold value th1 and whether it is greater than or equal to the threshold value th2. The threshold value th1 is greater than the threshold value th2. When the global dimming parameter DIMG is greater than or equal to the threshold value th1, the dimming circuit 150 sets the attenuation degree of the weight W(r) to the first attenuation degree. When the global dimming parameter DIMG is less than the threshold value th2, the dimming circuit 150 sets the attenuation degree of the weight W(r) to the second attenuation degree. When the global dimming parameter DIMG is less than the threshold value th1 and greater than the threshold value th2, the dimming circuit 150 sets the attenuation degree of the weight W(r) to the 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.

[0069] When the first method example is used, the dimming circuit 150 uses a lookup table corresponding to the first attenuation level, the second attenuation level, or the third attenuation level among the plurality of lookup tables as the attenuation rate distribution information 171. Alternatively, when the second method example is used, the dimming circuit 150 sets the filter matrix of the low-pass filter to the filter matrix corresponding to the first attenuation level, the second attenuation level, or the third attenuation level.

[0070] In addition, the weight setting corresponding to the global dimming parameter is not limited to the first to third examples described above. Figure 7 The attenuation degree of the weight W(r) may be set in more stages according to the global dimming parameter DIMG. Alternatively, the attenuation degree of the weight W(r) may be set continuously according to the global dimming parameter DIMG.

[0071] In the present embodiment, the circuit device 100 controls the display device 200 including a plurality of light source elements and a display panel 220. The circuit device 100 includes a brightness analysis circuit 130 and a dimming circuit 150. The brightness analysis circuit 130 performs brightness analysis on the image data IMA of the input image and outputs brightness information INT. The dimming circuit 150 determines light source brightness information indicating the brightness of light emitted by each of the plurality of light source elements based on the brightness information INT. The dimming circuit 150 uses a weight W(r) corresponding to a distance r between a pixel and the light source element to determine the brightness of light emitted by the light source element based on the brightness information INT of the pixel. 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) relative to 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.

[0072] In the dimming process in the local dimming control, the luminance of the light source elements arranged around the high-brightness pixels becomes higher. According to the present embodiment, by changing the attenuation degree of the weight W(r) corresponding to the distance r between the pixel and the light source element, it is possible to control to what extent the light source element away from the high-brightness pixel becomes brighter. Thus, dimming that is most suitable for displaying content or environment, etc. can be performed. Specifically, by reducing the attenuation degree of the weight W(r) when the global dimming parameter DIMG is large, the luminance of the light source elements around the high-brightness pixels is easily increased. Thus, it is displayed as high brightness in a bright environment. 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 luminance of the light source elements away from the high-brightness pixels to increase. Thus, the halo that is easily noticeable in a dark environment can be reduced.

[0073] In addition, Figure 5 or Figure 6 In the example of , the first value of the global dimming parameter DIMG is a value belonging to DIMG≥th, and the second value is a value belonging to DIMG<th. Figure 7 In the example of , the first value is a value belonging to DIMG≥th1, and the second value is a value belonging to DIMG<th2.

[0074] In addition, in this embodiment, when the global dimming parameter DIMG is the first value, the high brightness mode is used for displaying at a higher brightness than the halo reduction mode. Alternatively, when the global dimming parameter DIMG is the second value, the halo reduction mode is used for reducing the generation of halo compared to the high brightness mode.

[0075] According to the present embodiment, it is possible to set the high brightness mode when the environment is bright, and to set the halo reduction mode when the environment is dark. Specifically, when the global dimming parameter DIMG is the first value, the high brightness mode is set by setting the attenuation degree of the weight W(r) to the first attenuation degree. On the other hand, when the global dimming parameter DIMG is the second value less than the first value, the halo reduction mode is set by setting the attenuation degree of the weight W(r) to the second attenuation degree higher than the first attenuation degree.

[0076] In addition, in this embodiment, the dimming circuit 150 may also set the attenuation degree of the weight W(r) to a third attenuation degree when the global dimming parameter DIMG is a third value. 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.

[0077] According to the present embodiment, even when the environment is of intermediate brightness, dimming that is most suitable for displaying content or the environment, etc. can be performed. Specifically, when the global dimming parameter DIMG is a 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, a display mode intermediate between the high brightness mode and the halo reduction mode can be achieved.

[0078] In addition, Figure 7 In the example, the third value is a value that satisfies th1>DIMG≥th2.

[0079] In addition, in the present embodiment, the dimming circuit 150 may determine the light source brightness information by performing a global dimming process based on the global dimming parameter DIMG on the light emission brightness of each light source element determined based on the brightness information INT.

[0080] According to this embodiment, the luminous brightness of each light source element determined by the local dimming corresponding to the global dimming parameter DIMG is subjected to global dimming processing. Thus, it is possible to combine appropriate local dimming control corresponding to the brightness of the environment and global dimming processing. By appropriate local dimming control corresponding to the brightness of the environment, it is possible to achieve an improvement in display quality such as reducing halo, and dim the overall brightness of the screen according to the brightness of the environment.

[0081] 3. Dimming circuit

[0082] Hereinafter, a configuration example of a dimming circuit and a color correction circuit will be described in the case where the attenuation degree of the weight W(r) is set in the first method example described above, that is, a case where a plurality of lookup tables are used as attenuation rate distribution information.

[0083] Figure 8 is a detailed structural example of a circuit device. Figure 2 The description of the same components as those described in is appropriately omitted.

[0084] 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 . Figure 8 The example in which the storage unit 170 stores three types of lookup tables LUTA, LUTB, and LUTC having different attenuation rate distributions is shown. However, the number of lookup tables may be two or more.

[0085] The dimming circuit 150 reads 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 by using the brightness information INT and the lookup table read from the storage unit 170, determines the light source brightness information indicating the light emission brightness of each light source element, and outputs the light source brightness information as the light source brightness data DDIM.

[0086] The color correction circuit 120 reads out the lookup table for calculating the illumination brightness from the storage unit 170, among the lookup tables LUTA, LUTB, and LUTC. In addition, the lookup table for calculating the illumination brightness may be prepared independently of the lookup tables LUTA, LUTB, and LUTC corresponding to the mode. The color correction circuit 120 calculates the brightness of the light irradiating each pixel of the display panel 220 based on the light source brightness 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 inverse of the brightness of the light irradiating the pixel, and uses the result as the pixel data of the image data IMB.

[0087] The lookup tables LUTA, LUTB, and LUTC output attenuation rate information corresponding to the input distance information. The following shows an example in which the distance information is the square of the distance and the attenuation rate information is the attenuation rate expressed as a percentage of 100, but the present invention is not limited thereto. The distance information may be a distance or a number of pixels, etc. The attenuation rate information may be an attenuation rate expressed in an arbitrary unit.

[0088] Fig. 9 is an example of a lookup table LUTA. The lookup table LUTA is the attenuation rate distribution lsf 0 The exponent in the upper right corner of lsf here represents the power of lsf. Fig.10 is an example of the attenuation rate distribution of the lookup table LUTA.

[0089] The light from the light source element is diffused by a diffuser, etc., and the diffused light is irradiated onto the display panel. At this time, the brightness distribution of the light caused by the diffusion is an attenuation rate distribution. However, the attenuation rate distribution used when calculating the luminous brightness of the light source element may not be the actual attenuation rate distribution, but may be a virtual attenuation rate distribution programmed for calculating the luminous brightness. Fig. 9 and Fig.10 In FIG. 1 , a flat characteristic attenuation rate distribution is taken as an example.

[0090] like Fig. 9 As shown, the lookup table LUTA includes a lookup table LUTA1 storing the square of the distance and a lookup table LUTA2 storing the attenuation rate.

[0091] Each index of the lookup table LUTA1 stores the square of the distance corresponding to the index. Here, an example of an index of 0 to 10 is shown, but the number of indexes is arbitrary. In addition, an example of equally spaced distances within a range of 0 to 100 is shown, but the range of distances is arbitrary and the scale may not be equally spaced. As an example, the index is a memory address.

[0092] Each index of the lookup table LUTA2 stores the attenuation rate corresponding to the index. The attenuation rate is expressed as a value normalized by setting the maximum brightness to 100%. 0 In the example, the decay rate of all indexes is 100%.

[0093] For example, when the square of the distance is 300, the dimming circuit 150 sequentially reads the square of the distance of each index from the lookup table LUTA1 and compares it with 300, thereby determining the indexes 1 and 2 corresponding to 100 and 400 sandwiching 300. The dimming circuit 150 reads the attenuation rates of 100% and 100% of the indexes 1 and 2 from the lookup table LUTA2, and obtains the attenuation rate corresponding to the square of the distance 300 by interpolation. Here, since the distribution characteristic is flat, the attenuation rate after interpolation is 100%.

[0094] Fig.11 is an example of a lookup table LUTB. The lookup table LUTB is the decay rate distribution lsf 1 of table. Fig.12 This is an example of the decay rate distribution of the lookup table LUTB. 1 As an example, it is an actual attenuation rate distribution or an attenuation rate distribution approximated therefrom, but it may also be a virtual attenuation rate distribution programmed for calculation of light source brightness. Fig.11 and Fig.12 The decay rate distribution lsf is shown in 1 is an example of a Gaussian distribution.

[0095] like Fig.11As shown, the lookup table LUTB includes a lookup table LUTB1 storing the square of the distance and a lookup table LUTB2 storing the attenuation rate. The content and reference method of the lookup table are the same as those of the lookup table LUTA.

[0096] Fig.13 is an example of a lookup table LUTC. The lookup table LUTC is the attenuation rate distribution lsf 2 of table. Fig.14 is an example of the attenuation rate distribution of the lookup table LUTC. Attenuation rate distribution lsf 2 As an example, the distribution after squaring the actual attenuation rate distribution is a virtual attenuation rate distribution. 2 The distribution is not limited to the distribution obtained by squaring the actual attenuation rate distribution, but may be a distribution obtained by arbitrary programming.

[0097] like Fig.13 As shown, the lookup table LUTC includes a lookup table LUTC1 storing the square of the distance and a lookup table LUTC2 storing the attenuation rate. The content and reference method of the lookup table are the same as those of the lookup table LUTA.

[0098] The attenuation rate distribution of the lookup table LUTB has a higher attenuation degree relative to the distance than the attenuation rate distribution of the lookup table LUTA. The attenuation rate distribution of the lookup table LUTC has a higher attenuation degree relative to the distance than the attenuation rate distribution of the lookup table LUTB. With respect to the attenuation rate distribution, "a high attenuation degree relative to the distance" means that the distance over which the attenuation rate decreases to a specified attenuation rate is short. The specified attenuation rate may be arbitrary, for example, an attenuation rate in the range of 50% to 0%. Alternatively, "a high attenuation degree relative to the distance" means that the attenuation rate decreases greatly with respect to a change in distance in a direction in which the distance increases. Alternatively, "a high attenuation degree relative to the distance" means that the spread of light represented by the attenuation rate distribution is relatively narrow. In Figures 9 to 14 , the attenuation rate distribution changes smoothly with respect to the distance, but the attenuation rate distribution may also change in stages with respect to the distance. Figures 9 to 14 A one-dimensional lookup table is shown in FIG, but a two-dimensional lookup table may also be used.

[0099] Fig.15 This is the process flow of the dimming circuit. Hereinafter, 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 modes may be switched in more stages according to the global dimming parameter DIMG, or the modes may be switched continuously.

[0100] In step S1, the dimming circuit 150 determines whether the global dimming parameter DIMG is greater than the threshold value th. When the global dimming parameter DIMG is greater than the threshold value th, the dimming circuit 150 sets the high brightness mode and selects the lookup table LUTA or LUTB in step S2. When the global dimming parameter DIMG is not greater than the threshold value th, the dimming circuit 150 sets the halo reduction mode and selects the lookup table LUTC in step S3.

[0101] In step S4, the dimming circuit 150 initializes the light source brightness information. For example, the brightness values ​​of all light sources are initialized to zero.

[0102] In step S5, the dimming circuit 150 selects one pixel from the pixels included in the brightness information INT. The selected pixel is referred to as an object pixel. In the loop from step S5 to step S8, the object pixels are selected in sequence. For example, in the first 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 in sequence. When all the pixels of the first scan line are selected, the pixels of the second scan line are selected in sequence, and this is repeated until the final scan line.

[0103] In step S6, the dimming circuit 150 selects n×m light source elements located around the target pixel. These n×m light source elements are also referred to as surrounding light source elements. Figure 4 An example of n=4 and m=4 is shown in FIG. The dimming circuit 150 selects the light source elements L1 to L16 that are closest to the two columns in the +x direction and the two rows in the +y direction and the two rows in the -y direction, respectively, based on the position (i, j) of the target pixel 22. When k is an integer greater than 1 and less than 16, the position of the light source element Lk is represented as (xk, yk).

[0104] In step S7 , the light source brightness information for each of the n×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 .

[0105] In step S8 , the light control circuit 150 determines whether all pixels are selected as target pixels, and ends the process if all pixels are selected, and returns to step S5 if there are unselected pixels.

[0106] use Figure 4The updating process of the light source brightness information in step S7 is described by taking an example. Here, it is assumed that the number of pixels of the brightness information INT is the same as the number of pixels of the display panel 220. The dimming circuit 150 calculates the required change amount Δ representing 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 equations (1) and (2): ij .

[0107]

[0108] lsf(k)=lsf((i-xk) 2 +(j-yk) 2 )…(2)

[0109] In the above formula (1), INT ij It is the brightness value of the object pixel 22 in the brightness information INT. As shown in the above formula (2), lsf(k) is the attenuation rate of the light irradiated by the light source element Lk to the object pixel 22. In the above formula (2), the square of the distance is used as the independent variable, but the distance can also be used as the independent variable. The dimming circuit 150 uses the lookup table LUTB to calculate lsf(k). powc(k) is the previous light source brightness information of the light source element Lk. The previous light source brightness information is the light source brightness information calculated using the previous object pixel selected before the current object pixel 22. The previous object pixel is the pixel at the position (i-1, j) that is one position before the position (i, j) in the x direction.

[0110] The dimming circuit 150 uses the following equations (3) and (4) to calculate the required change Δ ij The light source brightness information assigned to the light source element Lk is updated accordingly. ij > 0, the denominator of the second term does not depend on k but is the same, so the required change Δ ij LSF x (k) is weighted. lsf x (k) is the attenuation rate distribution information selected according to the mode. Fig.15 In the process of , x=0 or 1 is selected in the high brightness mode, and x=2 is selected in the halo reduction mode. Since the decay rate distribution decays faster as x increases, it is easy to allocate the required change amount Δ to the light source element close to the target pixel 22. ij , it is difficult to allocate the required change amount Δ to the light source element far from the target pixel 22 ij As a result, the light source brightness of the light source element far from the high-brightness pixel is less likely to increase, and the effect of reducing halation can be achieved.

[0111]

[0112] lsfx (k) = lsf x ((i-xk) 2 +(j-yk) 2 )…((4)

[0113] In the above formula (3), powu(k) is the current light source brightness information, that is, the updated light source brightness information. As shown in the above formula (4), lsf x (k) is the attenuation rate of the light emitted by the light source element Lk to the target pixel 22. In the above formula (4), the square of the distance is used as the independent variable, but the distance can also be used as the independent variable. x is an integer greater than 0. Figures 9 to 14 In the example, x=0, 1, 2. That is, when x=0, the dimming circuit 150 refers to the lookup table LUTA to find lsf 0 (k), when x=1, refer to the lookup table LUTB to find lsf 1 (k), when x=2, refer to the lookup table LUTC to find lsf 2 (k).

[0114] In the present embodiment, the storage unit 170 may also store a plurality of attenuation rate distribution information indicating the attenuation rate distribution of light relative to the distance when the light source element illuminates the pixel. The dimming circuit 150 may also set the weight W(r) based on the first attenuation rate distribution information among the plurality of attenuation rate distribution information when the global dimming parameter DIMG is the first value. The dimming circuit 150 may also set the weight W(r) based on the second attenuation rate distribution information among the plurality of attenuation rate distribution information whose attenuation rate distribution is different from the first attenuation rate distribution information when the global dimming parameter DIMG is the second value.

[0115] According to the present embodiment, the attenuation degree of the weight W(r) can be set by selecting attenuation rate distribution information corresponding to the global dimming parameter DIMG from a plurality of attenuation rate distribution information having different attenuation rate distributions.

[0116] In addition, Figure 8 to Figure 15 In the example of , the plurality of attenuation rate distribution information corresponds to the lookup tables LUTA, LUTB, and LUTC. Fig.15 In the example of the process, 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. In addition, the weight W(r) is related to the required change Δ on the right side of the above formula (3). ij The coefficient corresponds to the coefficient of . This coefficient contains lsf representing the attenuation rate distribution information x (k) That is, the weight W(r) is set based on the attenuation rate distribution information.

[0117] Furthermore, in the present 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.

[0118] By using the attenuation rate distribution information of the attenuation degree of light relative to the distance for local dimming, the attenuation degree 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 attenuation degree of the weight W(r) is set to a second attenuation degree that is higher than the first attenuation degree.

[0119] 4. Color correction circuit

[0120] Fig.16 This is the flow of the illumination brightness calculation processing performed by the color correction circuit.

[0121] 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 an object pixel. In the loop from step S11 to step S14, the object pixels are selected in sequence. 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 in sequence. When all the pixels of the first scan line are selected, the pixels of the second scan line are selected in sequence, and this is repeated until the final scan line.

[0122] In step S12, the color correction circuit 120 selects s×t light source elements located around the target pixel. s and t can be integers greater than 2. Figure 4 The n×m light source elements may be the same or different. The illumination brightness information may be obtained based on all the light source elements instead of the s×t light source elements.

[0123] In step S13, the color correction circuit 120 obtains the illumination brightness information of the target pixel using the light source brightness information of the selected s×t light source elements and the lookup table for illumination brightness calculation. Specifically, the color correction circuit 120 obtains the illumination brightness information of the target pixel using the following equation (5).

[0124]

[0125] In the above equation (5), PL(i, j) is the illumination brightness information for the pixel at position (i, j). pow(β) is the light source brightness information determined by the dimming circuit 150. Fig.15After the loop of steps S5 to S8 is executed to the last pixel of the brightness information INT, the powu of the above formula (3) is used as the pow of the above formula (5). In addition, even if the loop of steps S5 to S8 is not executed to the last pixel of the brightness information INT, the update of the light source brightness information of the light source element is completed in sequence as the object pixel advances, so the light source brightness information after the update can also be used as pow. The color correction circuit 120 obtains lsf(β) using the lookup table LUTB.

[0126] In step S14 , the color correction circuit 120 determines whether all pixels are selected as target pixels, and ends the process if all pixels are selected, and returns to step S11 if there are unselected pixels.

[0127] In addition, the present embodiment is described in detail as described above, but those skilled in the art can easily understand that various modifications can be made without substantially departing from the new matters and effects of the present disclosure. Therefore, all such modifications are included in the scope of the present disclosure. For example, in the specification or the drawings, a term recorded at least once together with a different term in a broader sense or synonymous can be replaced with the different term in any part of the specification or the drawings. In addition, all combinations of the present embodiment and the modifications are also included in the scope of the present disclosure. In addition, the structure and operation of the circuit device, backlight source, display device, display system, processing device, electronic device, etc. are not limited to the contents described in the present embodiment, and various modifications can be implemented.

Claims

1. A circuit device, characterized in that: The circuit device controls a display device including a display panel and a plurality of light source elements, and the circuit device includes: a brightness analysis circuit that performs brightness analysis on image data of an input image and outputs brightness information; as well as a dimming circuit that determines light source brightness information indicating the brightness of light emitted by each of the plurality of light source elements based on the brightness information, The dimming circuit uses a weight corresponding to the distance between the pixel and the light source element to determine the light emission brightness of the light source element according to the brightness information of the pixel. When the global dimming parameter determined by the global dimming process is a first value, the dimming circuit sets the attenuation degree of the weight with respect to the distance to a first attenuation degree, When the global dimming parameter is a second value smaller than the first value, the dimming circuit sets the attenuation level to a second attenuation level higher than the first attenuation level.

2. The circuit arrangement according to claim 1, characterized in that The circuit device includes a storage unit storing a plurality of attenuation rate distribution information indicating an attenuation rate distribution of light with respect to the distance when the light source element irradiates the pixel. When the global dimming parameter is the first value, the dimming circuit sets the weight based on the first attenuation rate distribution information among the plurality of attenuation rate distribution information. When the global dimming parameter is the second value, the dimming circuit sets the weight based on second attenuation rate distribution information in which the attenuation rate distribution is different from the first attenuation rate distribution information among the plurality of attenuation rate distribution information.

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

4. The circuit arrangement according to claim 1, characterized in that When the global dimming parameter is the first value, the dimming circuit sets a high brightness mode for displaying at a higher brightness than the halo reduction mode. When the global dimming parameter is the second value, the dimming circuit sets the halo reduction mode in which the generation of halo is reduced compared to the high brightness mode.

5. The circuit arrangement according to claim 1, characterized in that When the global dimming parameter is a third value between the first value and the second value, the dimming circuit sets the attenuation level to a third attenuation level between the first attenuation level and the second attenuation level.

6. The circuit arrangement according to claim 1, characterized in that The dimming circuit determines the light source brightness information by performing the global dimming process based on the global dimming parameter on the light emission brightness of each light source element determined based on the brightness information.

7. The circuit arrangement according to claim 1, characterized in that The circuit device includes a color correction circuit that performs color correction on the image data based on the light source brightness information.

8. The circuit arrangement according to claim 1, characterized in that The global dimming parameter is a parameter that is set to a larger value as the environment is brighter or the brightness of the input image is higher.

9. A display system, characterized in that: The display system comprises: The circuit arrangement of any one of claims 1 to 8; and The display device.

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