Circuit device and display system

Abstract

The invention provides a circuit device and a display system. The circuit device controls a display device (2) including a display panel and a plurality of light source elements. The circuit device comprises a brightness analysis circuit and a dimming circuit. The brightness analysis circuit performs brightness analysis on image data of an input image and outputs brightness information. The dimming circuit determines light source brightness information indicating the emission brightness of each of the light source elements by performing a local dimming process for dimming each of the plurality of light source elements on the basis of the brightness information and a global dimming process using a global dimming parameter based on the sensor output of the external light sensor. The dimming circuit performs dimming processing in which the speed at which the light emission brightness is changed in the global dimming processing is slower than the speed at which the light emission brightness is changed in the local dimming processing.

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 an image display device that performs dark adaptation control that converges within 15 seconds when the illuminance decreases in global dimming, and performs bright adaptation control that converges within 4 seconds when the illuminance increases.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-285064

[0004] Patent Document 1 mentioned above does not describe how to control the light emission brightness of a light source element in response to changes in the brightness of an image in local dimming. 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 light source element by performing local dimming processing for dimming each of the multiple light source elements based on the brightness information and global dimming processing using global dimming parameters based on sensor output of an external light sensor, the dimming circuit performing a dimming processing in which the speed at which the luminous brightness changes in the global dimming processing is slower than the speed at which the luminous brightness changes in the local dimming processing.

[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 an example of how light brightness changes during global dimming processing.

[0011] Figure 5 This is an example of how light brightness changes during global dimming processing.

[0012] Figure 6 This is an example of the change in light emission brightness in the local dimming process.

[0013] Figure 7 This is an example of the change in light emission brightness in the local dimming process.

[0014] Figure 8 This is the first detailed structural example of the dimming circuit and the storage unit.

[0015] Fig. 9 This is a diagram for explaining multiplication processing.

[0016] Fig.10 This is the second detailed structural example of the dimming circuit and the storage unit.

[0017] Fig.11 This is the third detailed structural example of the dimming circuit and the storage unit.

[0018] Fig.12 This is the process flow of the dimming processing unit.

[0019] Fig.13 is an example of an ambient light source element.

[0020] Fig.14 This is the flow of the illumination brightness calculation processing performed by the color correction circuit.

[0021] Description of symbols

[0022] 22: object pixel; 100: circuit device; 120: color correction circuit; 130: brightness analysis circuit; 131: brightness extraction unit; 132: downsampling unit; 150: dimming circuit; 151: local dimming processing unit; 152: dimming processing unit; 153: second filter processing unit; 155: global dimming processing unit; 156: first filter processing unit; 157: multiplication unit; 170: storage unit; 171: attenuation rate distribution information; 172: filter setting 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; FDIMG: global dimming parameter after the first filtering process; FLLD: light source brightness information after the second filtering process; IMA, IMB: image data; INT: brightness information; LG1~LG48: light source elements; LLD: light source brightness information. DETAILED DESCRIPTION

[0023] 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 not all of the structures described in the present embodiments are necessarily essential structural elements.

[0024] 1. Electronic equipment, display systems and circuit devices

[0025] 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.

[0026] 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 .

[0027] 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 for a television device or an information processing device. Alternatively, the display device 200 may be a head-mounted display including a projection device for eyes or a head-up display including a projection device for 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 passing through the display panel 220 onto a screen.

[0028] When looking down at 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 be divided into a plurality of areas. When looking down, 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.

[0029] 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 configuration 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 of the odd-numbered rows and the even-numbered rows and the odd-numbered columns, and at the intersections of the other 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.

[0030] 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 210 based on 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.

[0031] 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.

[0032] 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.

[0033] 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 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.

[0034] The circuit device 100 receives the image data IMA and the global dimming parameter DIMG, and performs local dimming processing of the display device 200 based on the image data IMA. In addition, the circuit device 100 performs global dimming processing of the display device 200 based on the global dimming parameter DIMG. In local dimming, 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. In global dimming, the circuit device 100 changes the overall light emitting brightness of the backlight source 210 according to the global dimming parameter DIMG.

[0035] 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.

[0036] 2. Configuration example of circuit device

[0037] 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.

[0038] 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 .

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 .

[0043] 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.

[0044] The downsampling unit 132 obtains the second luminance image by downsampling the first luminance image. The number of pixels of the second luminance image is less than the number of pixels of the first luminance image. Downsampling may 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 luminance image as luminance information INT.

[0045] 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.

[0046] The dimming circuit 150 generates light source brightness information indicating the light emission brightness of each light source element based on the brightness information INT. This is equivalent to local dimming processing. Furthermore, the dimming circuit 150 uses the light source brightness information obtained through the local dimming processing and the global dimming parameter DIMG to perform global dimming processing, and outputs the result as light source brightness data DDIM. The global dimming processing is a process that makes the light emission brightness of each light source element determined by the local dimming processing brighter or darker as a whole. Figure 1As 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.

[0047] In the local dimming process, the dimming circuit 150 determines the luminance of the light source element according to the brightness information INT of the image around the light source element. When the brightness information INT of the image around the light source element changes, the dimming circuit 150 follows this and changes the luminance of the light source element. In addition, in the global dimming process, when the global dimming parameter DIMG changes, the dimming circuit 150 follows this and changes the overall luminance of the backlight source 210. If a certain light source element is focused on, the luminance of the light source element changes following the change of the global dimming parameter DIMG. At this time, the dimming circuit 150 performs the dimming process in a manner in which the speed of the luminance change in the global dimming process is slower than the speed of the luminance change in the local dimming process.

[0048] That is, when the brightness of the environment changes, the luminance of the backlight source 210 changes slowly, and when the brightness of the image changes, the luminance of the corresponding light source element changes quickly. For example, when a car temporarily enters the shadow of a building, etc., the brightness of the environment is unstable. Therefore, by slowing down the response of dimming to the brightness of the environment in global dimming, the frequent changes in the amount of light of the backlight source 210 can be suppressed, for example, the flickering of the screen can be reduced. On the other hand, in local dimming, in response to the brightness changes of the image, by rapidly changing the luminance of the light source element, it is possible to perform dimming of the image that appropriately follows the movement of a dynamic image, etc. According to this embodiment, appropriate dimming can be performed in both global dimming and local dimming as described above.

[0049] 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. The calculation of the illumination brightness is described in detail in Fig.14 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.

[0050] 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.

[0051] 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 separate logic circuits, or part or all of them can 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, the processor can also realize 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.

[0052] Figure 4 as well as Figure 5 This is an example of the change in light emission brightness in the global dimming process. Here, attention is paid to the light emission brightness of any one of the plurality of light source elements included in the backlight 210. However, the light emission brightness of the other light source elements is also controlled in the same manner.

[0053] exist Figure 4 2 shows an example of a case where the brightness of the environment decreases and then the decrease is maintained. As shown in the above figure, it is assumed that the output of the external light sensor decreases from SQ1 to SQ2 at time ta1. At this time, the global dimming parameter DIMG also decreases at time ta1.

[0054] As shown in the figure below, the luminous brightness corresponding to the output SQ1 of the external light sensor is KG1, and the luminous brightness corresponding to the output SQ2 of the external light sensor is KG2. The dimming circuit 150 changes the luminous brightness from KG1 to KG2 at a predetermined speed. The speed of changing the luminous brightness is the slope of the change in luminous brightness relative to time or the time for the luminous brightness to converge from KG1 to KG2. Figure 4 An example is shown in which the dimming circuit 150 makes the light emission brightness converge to KG2 in time Δta. In this case, the light emission brightness converges to KG2 at time ta2 after Δta has passed from time ta1. Figure 4 As shown, the luminous brightness changes with a fixed slope, and the luminous brightness can also gradually approach KG2 in an exponential function manner. Alternatively, the luminous brightness can also be in a step function manner until it is KG1 just before time ta2, and change to KG2 at time ta2. Alternatively, the luminous brightness can also change from KG1 to KG2 in stages.

[0055] Figure 5 An example is shown in which the brightness of the environment temporarily decreases and then returns to the original brightness. As shown in the figure above, the output of the external light sensor decreases from SQ1 to SQ2 at time tb1 and returns to SQ1 at time tb2. At this time, the global dimming parameter DIMG also decreases at time tb1 and returns to the original value at time tb2. In addition, the interval between time tb1 and tb2 is Δtb, and Δtb is shorter than Δta.

[0056] As shown in the figure below, the dimming circuit 150 decreases the luminous brightness from KG1 at a specified speed from time tb1, and increases the luminous brightness at a specified speed from time tb2. Since Δtb is shorter than Δta, the luminous brightness turns to increase before it decreases to KG2. When Δtb is sufficiently shorter than Δta, the decrease in luminous brightness is less than the difference between KG1 and KG2. The speed at which the luminous brightness increases can be faster than the speed at which the luminous brightness decreases, or the same as the speed at which the luminous brightness decreases. Figure 5 An example is shown in which the luminous brightness immediately returns to KG1 at time tb2, but the luminous brightness may also return to KG1 gradually, staged, or stepped after time tb2, similarly to the case in which the luminous brightness decreases.

[0057] Figure 6 and Figure 7 This is an example of the change in light emission brightness in the local dimming process. Here, attention is paid to the light emission brightness of any one of the plurality of light source elements included in the backlight 210. However, the light emission brightness of the other light source elements is also controlled in the same manner.

[0058] Figure 6 This shows an example of a case where the brightness of an image around a light emitting element decreases and then the decrease is maintained. As shown in the above figure, it is assumed that the brightness of an image around a light emitting element decreases from INT1 to INT2 at time tc1.

[0059] As shown in the figure below, the luminance corresponding to the brightness INT1 of the image is KL1, and the luminance corresponding to the brightness INT2 of the image is KL2. The dimming circuit 150 changes the luminance from KL1 to KL2 at a predetermined speed. The speed of changing the luminance is the slope of the change in luminance relative to time or the time for the luminance to converge from KL1 to KL2. Figure 6 The line A1 shows an example in which the dimming circuit 150 changes the light emission brightness from KL1 to KL2 instantly at time tc1. Figure 6Line A2 represents an example in which the dimming circuit 150 makes the luminous brightness converge to KL2 in time Δtc. In the case of line A2, the luminous brightness converges to KL2 at time tc2 after Δtc from time tc1. The luminous brightness can change with a fixed slope as shown in line A2, or the luminous brightness can gradually approach KL2 in an exponential function manner. Alternatively, the luminous brightness can be KL1 in a step function manner until just before time tc2, and change to KL2 at time tc2. Alternatively, the luminous brightness can also change from KL1 to KL2 in stages. In addition, line A1 can also be considered as the case where Δtc=0 is set in line A2.

[0060] The speed at which the light emission luminance is reduced in the local dimming process is faster than the speed at which the light emission luminance is reduced in the global dimming process. That is, Δtc is shorter than Δta.

[0061] exist Figure 7 An example of a situation in which the brightness of an image around a light-emitting element temporarily decreases and then returns to the original brightness is shown in FIG. As shown in the figure above, the brightness of an image around a light-emitting element decreases from INT1 to INT2 at time td1 and returns to INT1 at time td2. In addition, the interval between time td1 and td2 is Δtd, and Δtd is set to be the same as Δtb and longer than Δtc.

[0062] As shown in the figure below, the dimming circuit 150 makes the luminous brightness decrease from KL1 at a predetermined speed at time td1, and makes the luminous brightness increase at a predetermined speed from time td2. Since Δtd is longer than Δtc, the luminous brightness decreases to KL2 and then increases. The speed at which the luminous brightness increases can be faster than the speed at which the luminous brightness decreases, or the same as the speed at which the luminous brightness decreases. Figure 7 The example in which the light emission brightness immediately drops to KL2 at time td1 and immediately returns to KL1 at time td2 is shown. However, when the light emission brightness drops or rises, the light emission brightness may change gradually, stepwise, or in a stepwise manner.

[0063] As described above, in global dimming, even if the brightness of the environment changes temporarily, the dimming response to this can be slowed down. On the other hand, in local dimming, when the brightness of the image around the light source element changes, the dimming can follow this and respond. In this way, appropriate dimming can be performed in both global dimming and local dimming.

[0064] 3. Detailed structure example

[0065] Figure 8The first detailed configuration example of the dimming circuit and the storage unit. The dimming circuit 150 includes a local dimming processing unit 151 and a global dimming processing unit 155. The storage unit 170 stores attenuation rate distribution information 171 and filter setting information 172. In addition, the attenuation rate distribution information 171 and the filter setting information 172 may be written to the storage unit 170 from the outside of the circuit device 100 via an interface not shown in the figure. The outside of the circuit device 100 is, for example, the processing device 300.

[0066] The local dimming processing unit 151 determines the light emission brightness of each light source element of the backlight source 210 by performing local dimming processing, and outputs information indicating the light emission brightness of each light source element as light source brightness information FLLD. Figure 6 and Figure 7 As described in , the light emission brightness in the light source brightness information FLLD changes at a predetermined speed in response to changes in the brightness of the image. The local dimming processing unit 151 includes a dimming processing unit 152 and a second filter processing unit 153 .

[0067] The dimming processing unit 152 generates light source brightness information LLD indicating the light emission brightness of each light source element based on the brightness information INT and the attenuation rate distribution information 171. The light emission brightness in the light source brightness information LLD is the light emission brightness before the image brightness change is processed to change at a predetermined speed, for example, the light emission brightness that responds immediately to the image brightness change. The dimming processing is described in detail in Fig.12 and Fig.13 The dimming process is described later in the text, but the dimming process is not limited to this. For example, the dimming process unit 152 may also perform low-pass filtering and down-sampling processing on the brightness image as the brightness information INT, and use the result as the luminous brightness of each light source element. In this case, the attenuation rate distribution information 171 may not be used.

[0068] The second filter processing unit 153 generates light source brightness information FLLD by performing a second filter processing on the light emission brightness of each light source element included in the light source brightness information LLD. Figure 6 and Figure 7 As described in , the light luminance of each light source element changes at a predetermined speed in response to the brightness change of the image. The filter setting information 172 includes information for setting the filter characteristics of the second filter processing. That is, the filter setting information 172 includes information for setting the speed at which the light luminance is changed in response to the brightness change of the image. The speed at which the light luminance rises and the speed at which the light luminance decreases can also be set separately.

[0069] The second filtering process is, for example, a low-pass filter in the time direction. The filter setting information 172 includes information on the cutoff frequency of the low-pass filter. Alternatively, the second filtering process may be a process of determining a maximum variation per frame and changing the luminous brightness by a variation below the maximum variation. In this case, the filter setting information 172 includes information on the maximum variation per frame.

[0070] The global dimming processing unit 155 generates light source brightness data DDIM by performing global dimming processing on the light source brightness information FLLD. The light emission brightness in the light source brightness data DDIM is as follows: Figure 4 and Figure 5 As described in the description, the brightness of the environment changes at a specified speed, and as Figure 6 and Figure 7 As described in , the global light adjustment processing unit 155 changes at a predetermined speed in response to changes in the brightness of the image. The global light adjustment processing unit 155 includes a first filter processing unit 156 and a multiplication unit 157 .

[0071] The first filter processing unit 156 generates a global dimming parameter FDIMG after the first filtering process by performing the first filtering process on the global dimming parameter DIMG. The filtering setting information 172 includes information for setting the filtering characteristics of the first filtering process. That is, the filtering setting information 172 includes information for setting the speed at which the light emission brightness is changed in response to the change of the global dimming parameter DIMG. The speed at which the light emission brightness increases and the speed at which the light emission brightness decreases can also be set separately.

[0072] The first filter process is, for example, a low-pass filter in the time direction. The filter setting information 172 includes, for example, information on the cutoff frequency of the low-pass filter. The cutoff frequency of the first filter process is lower than the cutoff frequency of the second filter process. Alternatively, the first filter process may be a process that determines the maximum variation of each frame and changes the luminous brightness by a variation below the maximum variation. In this case, the filter setting information 172 includes information on the maximum variation of each frame. The maximum variation of the first filter process is smaller than the maximum variation of the second filter process.

[0073] The multiplication unit 157 performs multiplication processing on the global dimming parameter FDIMG after the first filtering process and the light source brightness information FLLD after the second filtering process, and outputs the result as the light source brightness data DDIM. Figure 4 and Figure 5 As described in , the brightness of the backlight 210 changes at a predetermined speed in response to changes in the brightness of the environment.

[0074] Fig. 9 Here, the backlight 210 includes light source elements LG1 to LG48 arranged in a matrix of 6 rows and 8 columns.

[0075] The second filter processing unit 153 of the local dimming processing unit 151 outputs the light emission brightness FLLDp of the light source element LGp. p is an integer greater than 1 and less than 48. The first filter processing unit 156 of the global dimming processing unit 155 outputs the same global dimming parameter FDIMG to the light source elements LG1 to LG48. The multiplication unit 157 multiplies the light emission brightness FLLDp of the light source element LGp by the global dimming parameter FDIMG and outputs the result as the light source brightness data DDIM. Fig. 9 , the multiplication process is shown as an example of simple multiplication, but the multiplication process is not limited to this, and may include, for example, multiplication or addition of coefficients.

[0076] Fig.10 This is a second detailed configuration example of a dimming circuit and a storage unit. The differences from the first detailed configuration example are described. In the second detailed configuration example, the local dimming processing unit 151 does not include the second filter processing unit 153. In addition, the multiplication unit 157 of the global dimming processing unit 155 performs multiplication processing on the global dimming parameter FDIMG after the first filter processing and the light source brightness information LLD output by the dimming processing unit 152.

[0077] Fig.11 This is the third detailed structure example of the dimming circuit and the storage unit. The points different from the first detailed structure example are described. In the third detailed structure example, the global dimming processing unit 155 does not include the first filter processing unit 156, and the processing device 300 includes the first filter processing unit 156. The multiplication unit 157 multiplies the global dimming parameter FDIMG after the first filter processing input from the processing device 300 and the light source brightness information FLLD after the second filter processing. In addition, the second filter processing unit 153 may be omitted, and the multiplication unit 157 multiplies the global dimming parameter FDIMG after the first filter processing input from the processing device 300 and the light source brightness information FLLD output from the dimming processing unit 152.

[0078] In the present embodiment, the circuit device 100 controls the display device 200 including the display panel 220 and a plurality of light source elements. 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 the light source brightness information indicating the light emission brightness of each light source element by performing a local dimming process for dimming each of the plurality of light source elements based on the brightness information INT and a global dimming process using a global dimming parameter DIMG based on the sensor output of an external light sensor. The dimming circuit 150 performs a dimming process in which the speed of changing the light emission brightness in the global dimming process is slower than the speed of changing the light emission brightness in the local dimming process.

[0079] According to the present embodiment, the change in luminance in global dimming is relatively slow compared to the change in luminance in local dimming. That is, when the brightness of the environment changes, the luminance of the backlight source 210 changes slowly, and when the brightness of the image changes, the luminance of the corresponding light source element changes quickly. Thus, by slowing down the response of dimming to the brightness of the environment in global dimming, frequent changes in the amount of light of the backlight source 210 can be suppressed, for example, the flicker of the screen can be reduced. On the other hand, in local dimming, by rapidly changing the luminance of the light source element in response to the brightness change of the image, it is possible to perform dimming of an image that appropriately follows the movement of a dynamic image or the like. According to the present embodiment, appropriate dimming can be performed in both global dimming and local dimming.

[0080] In the present embodiment, the dimming circuit 150 may perform a first filtering process on the global dimming parameter DIMG based on a first time constant. Thus, the dimming circuit 150 changes the light emission brightness in the global dimming process at a slower speed than that in the local dimming process.

[0081] According to the present embodiment, the first filtering process based on the first time constant is performed on the global dimming parameter DIMG. Thus, when the global dimming parameter DIMG changes, the light luminance of the backlight source 210 changes with the first time constant. The first time constant can make the speed of changing the light luminance in the global dimming process slower than the speed of changing the light luminance in the local dimming process.

[0082] In addition, the first time constant is a time constant indicating the speed of change of the luminous brightness determined by the first filtering process. For example, the first filtering process is a low-pass filter, and the first time constant is a time constant corresponding to the cutoff frequency of the low-pass filter. Alternatively, the first time constant may also be a constant indicating the time for the change of the luminous brightness to converge. As an example, the first filtering process may also be a process of determining the maximum change amount per frame and changing the luminous brightness by a change amount less than the maximum change amount. In this case, the first time constant is the time until the change of the luminous brightness converges when the luminous brightness is changed for each frame by the change amount.

[0083] Furthermore, in the present embodiment, the dimming circuit 150 may perform a second filtering process based on a second time constant shorter than the first time constant on the result of the local dimming process.

[0084] According to this embodiment, the first filtering process based on the first time constant is performed on the global dimming parameter DIMG, and the second filtering process based on the second time constant is performed on the result of the local dimming process. Since the second time constant is shorter than the first time constant, the speed of changing the light luminance in the global dimming process can be made slower than the speed of changing the light luminance in the local dimming process.

[0085] In addition, the second time constant is a time constant indicating the speed of the change in luminous brightness determined by the second filtering process. For example, the second filtering process is a low-pass filter, and the second time constant is a time constant corresponding to the cutoff frequency of the low-pass filter. Alternatively, the second time constant may also be a constant indicating the time for the change in luminous brightness to converge. As an example, the second filtering process may also be a process of determining the maximum variation of each frame and changing the luminous brightness by a variation below the maximum variation. In this case, the second time constant is the time until the change in luminous brightness converges when the luminous brightness is changed for each frame by the variation.

[0086] In this embodiment, the dimming circuit 150 may input the global dimming parameter FDIMG subjected to the first filtering process based on the first time constant from outside the circuit device 100. The dimming circuit 150 may determine the light source brightness information using the result of the local dimming process and the global dimming parameter FDIMG.

[0087] According to the present embodiment, the external device such as the processing device 300 performs the first filtering process based on the first time constant on the global dimming parameter DIMG. Thus, the external device such as the processing device 300 can control the first time constant. In this case, the dimming circuit 150 sets the second time constant of the second filtering process to a time constant shorter than the first time constant. Thus, the speed of changing the light luminance in the global dimming process can be made slower than the speed of changing the light luminance in the local dimming process.

[0088] In addition, in the present embodiment, the dimming circuit 150 may perform a dimming process in which the speed at which the light emission luminance is reduced in the global dimming process is slower than the speed at which the light emission luminance is reduced in the local dimming process.

[0089] From the perspective of visibility, when the brightness of the environment increases, it is desirable that the backlight source 210 quickly becomes brighter. On the other hand, when the brightness of the environment temporarily decreases, it is preferred that the dimming of the backlight source 210 does not follow. According to this embodiment, the speed at which the light emission brightness is reduced in the global dimming process is slower than the speed at which the light emission brightness is reduced in the local dimming process, so that when the brightness of the environment temporarily decreases, the dimming of the backlight source 210 is not easy to follow.

[0090] In addition, in the present embodiment, the dimming circuit 150 may perform a dimming process in which the speed at which the light emission luminance is increased in the local dimming process is faster than the speed at which the light emission luminance is increased in the global dimming process.

[0091] In local dimming, it is preferred that the brightness of the light source of each light emitting element quickly follows the brightness of the image around it. According to this embodiment, the speed at which the light brightness is increased in the local dimming process is faster than the speed at which the light brightness is increased in the global dimming process, thereby allowing the brightness of the light source of each light emitting element to quickly follow the brightness of the image around it.

[0092] 4. Dimming processing unit and color correction circuit

[0093] Fig.12 This is the process flow of the dimming processing unit. Fig.13 Examples of ambient light elements are shown. Fig.13 In the example, 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 brightness information INT is not downsampled, and the number of pixels of the brightness information INT is the same as the number of pixels of the image data IMA. In this case, Fig.13 The (x, y) in is the coordinate on the brightness information INT, and is also the coordinate on the input image. In addition, when downsampling is performed, the coordinate in the brightness information INT after downsampling can be used instead of (x, y) in the dimming process.

[0094] In step S1, the dimming processing unit 152 initializes the light source brightness information. For example, the dimming processing unit 152 initializes the brightness values ​​of all light source elements to zero.

[0095] In step S2, the dimming processing unit 152 selects a 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 S2 to step S5, the object pixels are selected in sequence. For example, in the first step S2, the first pixel of the first scan line of the brightness information INT is selected, and in the subsequent steps S2, the second pixel, the third pixel, ... are selected in sequence. If all the pixels of the first scan line have been selected, the pixels of the second scan line are selected in sequence, and this is repeated until the final scan line.

[0096] In step S3, the light adjustment processing unit 152 selects n×m light source elements located around the target pixel. These n×m light source elements are also referred to as peripheral light source elements. n and m may be integers greater than or equal to 2.

[0097] like Fig.13 As shown in FIG. 1 , the position of the object pixel 22 is assumed to be (i, j). i and j are integers, and the position (i, j) indicates that it is the i-th pixel of the j-th scanning line. Fig.13In the example, n=m=4. The dimming processing unit 152 selects the light source elements L1 to L16 that are closest to the +x direction and the -x direction and the closest to the +y direction and the -y direction, respectively, based on the position (i, j). 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).

[0098] exist Fig.12 In step S4 , the light source brightness information of each of the n×m light source elements selected in step S3 is updated using the pixel value of the target pixel 22 in the brightness information INT and the attenuation rate distribution information 171 stored in the storage unit 170 .

[0099] In step S5 , the light adjustment processing unit 152 determines whether all pixels are selected as target pixels, and ends the processing if all pixels are selected, and returns to step S2 if there are unselected pixels.

[0100] The updating process of the light source brightness information in step S4 is described. The light adjustment processing unit 152 obtains 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 equation (1): ij .

[0101]

[0102] In the above formula (1), INT ij It is the brightness value of the object pixel 22 in the brightness information INT. As described above, the brightness value is the maximum value among the RGB pixel values ​​of the object pixel 22 in the image data IMA. Alternatively, the brightness value may be a brightness value calculated by multiplying the RGB pixel values ​​of the object pixel 22 in the image data IMA by a coefficient, such as Y in the YCrCb space. lsf(k) is the attenuation rate of the light irradiated by the light source element Lk to the object pixel 22, and is obtained based on the actual attenuation rate distribution or the attenuation rate distribution after approximation. The dimming processing unit 152 uses the attenuation rate distribution information 171 to obtain lsf(k). The attenuation rate distribution information 171 is a lookup table or a function. 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.

[0103] The dimming processing unit 152 converts the required change amount Δ into ij The light source luminance information is allocated to the light source element Lk, thereby updating the light source luminance information.

[0104]

[0105] In the above formula (2), powu(k) is the current light source brightness information, that is, the updated light source brightness information.

[0106] Fig.14 This is the flow of the illumination brightness calculation process performed by the color correction circuit. Fig.13 , but the processing performed by the color correction circuit 120 is different from the processing performed by the dimming processing unit 152. In the description of the dimming processing unit 152, (x, y) is used as the coordinate on the brightness information INT, but here, (x, y) is the coordinate on the input image shown by the image data IMA.

[0107] 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 have been selected, the pixels of the second scan line are selected in sequence, and this is repeated until the final scan line.

[0108] In step S12, the color correction circuit 120 selects s×t light source elements located around the target pixel. These s×t light source elements are also referred to as surrounding light source elements. s and t may be integers greater than or equal to 2. Fig.13 An example where s=t=4 is shown.

[0109] The position of the object pixel 22 is represented as (i, j). i and j are integers, and the position (i, j) indicates that it is the i-th pixel of the j-th scanning line. The color correction circuit 120 selects the light source elements L1 to L16 that are closest to the +x direction and the -x direction and the closest to the +y direction and the -y direction, respectively, based on the position (i, j). When β is an integer greater than 1 and less than 16, the position of the light source element Lβ is represented as (xβ, yβ).

[0110] In step S13 , the color correction circuit 120 obtains illumination brightness information of the target pixel using the light source brightness information of the selected s×t light source elements and the attenuation rate distribution information 171 .

[0111] 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.

[0112] The calculation process of the illumination brightness information in step S13 will be described. The color correction circuit 120 obtains the illumination brightness information of the target pixel 22 by the following equations (3) and (4).

[0113]

[0114] lsf(β)=lsf((i-xβ) 2 +(j-yβ) 2 )···(4)

[0115] In the above formula (3), 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 processing unit 152. lsf(β) is the attenuation rate of the light of the light source element Lβ irradiating the target pixel 22. The color correction circuit 120 calculates lsf(β) using the attenuation rate distribution information 171. In the above formula (4), the square of the distance is used as the input of the lookup table, but the distance can also be used as the input of the lookup table.

[0116] In addition, Fig.12 After the loop of steps S2 to S5 in the process is executed to the last pixel of the brightness information INT, the powu of the above formula (2) is used as the pow of the above formula (3). In addition, even if the loop of steps S2 to S5 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 at which the update is completed can also be used as pow.

[0117] The color correction circuit 120 may obtain the illumination brightness information of the target pixel based not only on the light source brightness information of s×t light source elements located around the target pixel but also on the light source brightness information of all the light source elements of the backlight 210 .

[0118] 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 light emission brightness of each of the plurality of light source elements by performing local dimming processing for dimming each of the plurality of light source elements based on the brightness information and global dimming processing using a global dimming parameter based on a sensor output of an external light sensor, The dimming circuit performs a dimming process in which a speed of changing the light emission luminance in the global dimming process is slower than a speed of changing the light emission luminance in the local dimming process.

2. The circuit arrangement according to claim 1, characterized in that The dimming circuit performs a first filter process based on a first time constant on the global dimming parameter, thereby making the speed of changing the light emission brightness in the global dimming process slower than the speed of changing the light emission brightness in the local dimming process.

3. The circuit arrangement according to claim 2, characterized in that The dimming circuit performs a second filtering process based on a second time constant shorter than the first time constant on a result of the local dimming process.

4. The circuit arrangement according to claim 1, characterized in that The dimming circuit receives the global dimming parameter after the first filtering process based on the first time constant from outside the circuit device, and determines the light source brightness information using the result of the local dimming process and the global dimming parameter.

5. The circuit arrangement according to claim 1, characterized in that The dimming circuit performs the dimming process such that a speed at which the light emission luminance is reduced in the global dimming process is slower than a speed at which the light emission luminance is reduced in the local dimming process.

6. The circuit arrangement according to claim 1, characterized in that The dimming circuit performs the dimming process such that a speed at which the light emission luminance is increased in the local dimming process is faster than a speed at which the light emission luminance is increased in the global dimming process.

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. A display system, characterized in that: The display system includes: The circuit arrangement of any one of claims 1 to 7; and The display device.

Images