Circuit unit and display system

Abstract

To provide a circuit unit capable of appropriately regulating light in both modes of global dimming and local dimming.SOLUTION: A circuit unit 100 controls a display device 200 including plural light source elements and a display panel 220. The circuit unit 100 includes a luminance analysis circuit 130 and light regulation circuit 150. The luminance analysis circuit 130 analyzes image data IMA of an input image in terms of a luminance, and outputs luminance information INT. The light regulation circuit 150 performs local dimming processing of regulating the light of each of the plural light source elements on the basis of the luminance information INT, and global dimming processing which uses a global light regulation parameter DIMG based on a sensor output of an external light sensor, and thus determines light source luminance information representing the light emission luminance of each of the light source elements. The light regulation circuit 150 performs light regulation processing which makes a speed of changing a light emission luminance during the global dimming processing slower than a speed of changing the light emission luminance during the local dimming processing.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses an image display device that, in global dimming, performs dark adaptation control such that the brightness converges in 15 seconds when the illuminance decreases, and performs light adaptation control such that the brightness converges in 4 seconds when the illuminance increases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-285064 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned Patent Document 1 does not disclose how the emission luminance of the light source element is controlled in response to a change in the luminance of the image in local dimming. [Means for solving the problem]

[0005] One aspect of the present disclosure is a circuit device that controls a display device including a plurality of light source elements and a display panel, the circuit device including: a luminance analysis circuit that performs luminance analysis of image data of an input image to output luminance information; a dimming circuit that determines light source luminance information indicating the emission luminance of each of the plurality of light source elements by performing a local dimming process that dims each of the light source elements based on the luminance information; and a global dimming process using a global dimming parameter based on a sensor output of an external light sensor, the dimming circuit relating to a circuit device that performs a dimming process in which the speed at which the emission luminance is changed in the global dimming process is slower than the speed at which the emission luminance is changed in the local dimming process.

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

[0007] [Figure 1] Example of electronic device configuration. [Diagram 2] 1 shows an example of the configuration of a circuit device. [Diagram 3] 1 shows a detailed configuration example of a luminance analysis circuit. [Figure 4] An example of change in luminance during global dimming processing. [Diagram 5] An example of change in luminance during global dimming processing. [Figure 6] An example of change in luminance during local dimming processing. [Figure 7] An example of change in luminance during local dimming processing. [Figure 8] 13 shows a first detailed configuration example of a dimming circuit and a memory unit. [Figure 9] FIG. [Figure 10] 13 shows a second detailed configuration example of the dimming circuit and the memory unit. [Figure 11] 13 shows a third detailed configuration example of a dimming circuit and a memory unit. [Figure 12] 4 is a flow of processing performed by the dimming processing unit. [Figure 13] An example of an ambient light source element. [Figure 14] 4 is a flow chart showing the lighting luminance calculation process performed by the color correction circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

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

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

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

[0013] An example of a two-dimensional arrangement of light source elements is a square arrangement in which light source elements are arranged at all intersections of multiple rows and multiple columns. However, the two-dimensional arrangement is not limited to a square arrangement. For example, the two-dimensional arrangement may be an arrangement called a diamond arrangement or a staggered arrangement. In this arrangement, light source elements are arranged at intersections between one of the odd-numbered rows and the even-numbered rows and the odd-numbered columns, and at intersections between the other of the odd-numbered rows and the even-numbered rows and the even-numbered columns, and light source elements are not arranged at other intersections.

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

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

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

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

[0018] The circuit device 100 receives image data IMA and a global dimming parameter DIMG, and performs a local dimming process on the display device 200 based on the image data IMA. The circuit device 100 also performs a global dimming process on the display device 200 based on the global dimming parameter DIMG. In local dimming, the circuit device 100 dims the light emission luminance of each light source element or each area of ​​the backlight 210 according to the luminance of the image data IMA, and outputs light source luminance information obtained by the dimming to the light source driver 240 as light source luminance data DDIM. In addition, the circuit device 100 performs color correction on the image data IMA based on the light source luminance information, and outputs the image data IMB after the color correction to the display driver 230. In global dimming, the circuit device 100 changes the light emission luminance of the entire backlight 210 according to the global dimming parameter DIMG.

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

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

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

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

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

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

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

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

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

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

[0029] The dimming circuit 150 generates light source luminance information indicating the light emission luminance of each light source element based on the luminance information INT. This corresponds to local dimming processing. The dimming circuit 150 then performs global dimming processing using the light source luminance information obtained by the local dimming processing and the global dimming parameter DIMG, and outputs the result as light source luminance data DDIM. The global dimming processing is a process for brightening or darkening the light emission luminance of each light source element determined by the local dimming processing as a whole. As described in FIG. 1, the global dimming parameter DIMG is input from the processing device 300 to the circuit device 100. However, the circuit device 100 may perform global dimming processing based on information on the amount of ambient light, and obtain the global dimming parameter DIMG.

[0030] In the local dimming process, the dimming circuit 150 determines the emission luminance of the light source element from the luminance information INT of the image around the light source element. When the luminance information INT of the image around the light source element changes, the dimming circuit 150 changes the emission luminance of the light source element accordingly. In addition, in the global dimming process, when the global dimming parameter DIMG changes, the dimming circuit 150 changes the emission luminance of the entire backlight 210 accordingly. When focusing on one light source element, the emission luminance of the light source element changes following the change in the global dimming parameter DIMG. At this time, the dimming circuit 150 performs the dimming process so that the speed at which the emission luminance changes in the global dimming process is slower than the speed at which the emission luminance changes in the local dimming process.

[0031] That is, when the brightness of the environment changes, the emission luminance of the backlight 210 changes relatively slowly, and when the brightness of the image changes, the emission luminance of the light source element corresponding to the change changes relatively quickly. For example, the brightness of the environment is unstable, such as when a car temporarily enters the shadow of a building or the like. For this reason, 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 210 can be suppressed, and for example, flickering of the screen can be reduced. On the other hand, in local dimming, by quickly changing the emission luminance of the light source element in response to the brightness change of the image, dimming that appropriately follows a moving picture such as a video can be achieved. According to this embodiment, appropriate dimming is possible in both global dimming and local dimming as described above.

[0032] The color correction circuit 120 calculates illumination luminance information based on the light source luminance data DDIM from the dimming circuit 150 and the attenuation rate distribution information 171 stored in the storage unit 170. The illumination luminance information indicates the illumination luminance at each pixel of the display panel 220 when the display panel 220 is illuminated by the backlight 210. Details of the calculation of the illumination luminance will be described later with reference to FIG. 14. The color correction circuit 120 performs color correction of the image data IMA based on the illumination luminance information, and outputs the corrected image data IMB. Specifically, the color correction circuit 120 multiplies the pixel data of each pixel by the reciprocal of the luminance of the light reaching that pixel, and sets the result as new pixel data for that pixel. The image represented by the image data IMB is called an output image.

[0033] The circuit device 100 transmits image data IMB of an output image to the display driver 230 via an image interface (not shown). The image interface may be of various types, such as LVDS, a parallel RGB type, or a display port.

[0034] The color correction circuit 120, the luminance analysis circuit 130, and the light control circuit 150 are logic circuits that process digital signals. The color correction circuit 120, the luminance analysis circuit 130, and the light control circuit 150 may each be configured as a separate logic circuit, or a part or all of them may be configured as an integrated logic circuit. Alternatively, a processor such as a DSP may execute an instruction set or a program in which the functions of the color correction circuit 120, the luminance analysis circuit 130, and the light control circuit 150 are described, thereby realizing the functions of these circuits. Alternatively, the circuit device 100 may be a processor such as a CPU, a GPU, a microcomputer, a DSP, an ASIC, or an FPGA. The processor may execute an instruction set or a program in which the functions of each part of the circuit device 100 are described, thereby realizing the functions of the circuit device 100.

[0035] 4 and 5 are examples of changes in emission luminance in the global dimming process. Here, attention is focused on the emission luminance of any one of the light source elements included in the backlight 210. However, the emission luminance of the other light source elements is also controlled in the same manner.

[0036] Figure 4 shows an example of a case where the brightness of the environment decreases and then the decrease is sustained. As shown in the figure above, assume that the output of the ambient light sensor decreases from SQ1 to SQ2 at time ta1. At this time, the global dimming parameter DIMG also decreases at time ta1.

[0037] As shown in the lower diagram, the light emission luminance corresponding to the output SQ1 of the external light sensor is KG1, and the light emission luminance corresponding to the output SQ2 of the external light sensor is KG2. The light control circuit 150 changes the light emission luminance from KG1 to KG2 at a predetermined speed. The speed at which the light emission luminance is changed is the slope of the change in the light emission luminance with respect to time, or the time at which the light emission luminance converges from KG1 to KG2, etc. FIG. 4 shows an example in which the light control circuit 150 converges the light emission luminance to KG2 at time Δta. In this case, the light emission luminance converges to KG2 at time ta2 after Δta from time ta1. As shown in FIG. 4, the light emission luminance may change at a constant slope, or the light emission luminance may gradually approach KG2 exponentially. Alternatively, the light emission luminance may be KG1 until just before time ta2 and change to KG2 at time ta2 in a step function manner. Alternatively, the light emission luminance may change stepwise from KG1 to KG2.

[0038] Figure 5 shows an example of the case where the brightness of the environment temporarily drops, and then returns to the original brightness. As shown in the figure above, the output of the ambient light sensor drops from SQ1 to SQ2 at time tb1, and returns to SQ1 at time tb2. At this time, the global dimming parameter DIMG also drops at time tb1, and returns to the original value at time tb2. Note that the interval between times tb1 and tb2 is Δtb, and Δtb is shorter than Δta.

[0039] As shown in the lower diagram, the light control circuit 150 reduces the light emission luminance from KG1 at a predetermined speed from time tb1, and increases the light emission luminance at a predetermined speed from time tb2. Since Δtb is shorter than Δta, the light emission luminance starts to increase before it decreases to KG2. When Δtb is sufficiently shorter than Δta, the decrease in the light emission luminance is smaller than the difference between KG1 and KG2. The speed at which the light emission luminance increases may be faster than the speed at which the light emission luminance decreases, or may be the same as the speed at which the light emission luminance decreases. FIG. 5 shows an example in which the light emission luminance immediately returns to KG1 at time tb2, but the light emission luminance may return to KG1 gradually, stepwise, or in steps after time t2, similar to the case in which the light emission luminance decreases.

[0040] 6 and 7 are examples of changes in emission luminance in local dimming processing. Here, attention is focused on the emission luminance of any one of the light source elements included in the backlight 210. However, the emission luminance of the other light source elements is also controlled in the same manner.

[0041] 6 shows an example of a case where the luminance of an image around a light-emitting element is decreased and then the decrease is maintained. As shown in the upper diagram, assume that the luminance of an image around a light-emitting element is decreased from INT1 to INT2 at time tc1.

[0042] As shown in the figure below, the light emission luminance corresponding to the image luminance INT1 is KL1, and the light emission luminance corresponding to the image luminance INT2 is KL2. The light control circuit 150 changes the light emission luminance from KL1 to KL2 at a predetermined speed. The speed at which the light emission luminance is changed is the slope of the change in the light emission luminance with respect to time, or the time at which the light emission luminance converges from KL1 to KL2, etc. Line A1 in FIG. 6 shows an example in which the light control circuit 150 immediately changes the light emission luminance from KL1 to KL2 at time tc1. Line A2 in FIG. 6 shows an example in which the light control circuit 150 converges the light emission luminance to KL2 at time Δtc. In the case of line A2, the light emission luminance converges to KL2 at time tc2 after Δtc from time tc1. As shown in line A2, the light emission luminance may change at a constant slope, or the light emission luminance may gradually approach KL2 exponentially. Alternatively, the emission luminance may be KL1 until just before time tc2 and change to KL2 at time tc2 in a step function manner. Alternatively, the emission luminance may change stepwise from KL1 to KL2. Note that line A1 can also be considered as the case where Δtc=0 on line A2.

[0043] The speed at which the emitted light luminance is reduced in the local dimming process is faster than the speed at which the emitted light luminance is reduced in the global dimming process, i.e., Δtc is shorter than Δta.

[0044] Figure 7 shows an example of the case where the brightness of the image around the light-emitting element temporarily drops and then returns to the original brightness. As shown in the figure above, the brightness of the image around the light-emitting element drops from INT1 to INT2 at time td1, and returns to INT1 at time td2. Note that the interval between times td1 and td2 is Δtd, and Δtd is approximately the same as Δtb and longer than Δtc.

[0045] As shown in the figure below, the light control circuit 150 reduces the emission luminance from KL1 at a predetermined speed at time td1, and increases the emission luminance at a predetermined speed from time td2. Since Δtd is longer than Δtc, the emission luminance drops to KL2 and then starts to rise. The speed at which the emission luminance rises may be faster than the speed at which the emission luminance drops, or may be the same as the speed at which the emission luminance drops. FIG. 7 shows an example in which the emission luminance instantly drops to KL2 at time td1 and instantly returns to KL1 at time td2. However, when the emission luminance drops or rises, the emission luminance may change gradually, stepwise, or in steps.

[0046] As described above, in global dimming, even if the brightness of the environment changes temporarily, the dimming response can be delayed. On the other hand, in local dimming, when the brightness of the image around the light source element changes, the dimming can be made to respond to the change. This makes it possible to perform appropriate dimming in both global dimming and local dimming.

[0047] 3. Detailed configuration example 8 is a 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. Note that the attenuation rate distribution information 171 and the filter setting information 172 may be written to the storage unit 170 from outside the circuit device 100 via an interface (not shown). The outside of the circuit device 100 is, for example, a processing device 300.

[0048] The local dimming processing unit 151 performs local dimming processing to determine the emission luminance of each light source element of the backlight 210, and outputs information indicating the emission luminance of each light source element as light source luminance information FLLD. The emission luminance in the light source luminance information FLLD changes at a predetermined speed with respect to the change in luminance of the image, as described in FIG. 6 and FIG. 7. The local dimming processing unit 151 includes a dimming processing unit 152 and a second filter processing unit 153.

[0049] The dimming processor 152 generates light source luminance information LLD indicating the emission luminance of each light source element based on the luminance information INT and the attenuation rate distribution information 171. The emission luminance in the light source luminance information LLD is the emission luminance before processing that changes at a predetermined speed in response to the luminance change of the image is applied, and is, for example, the emission luminance that responds immediately to the luminance change of the image. The details of the dimming process will be described later with reference to Figs. 12 and 13, but the dimming process is not limited thereto. For example, the dimming processor 152 may perform low-pass filter processing and downsampling processing on the luminance image that is the luminance information INT, and use the result as the emission luminance of each light source element. In that case, the attenuation rate distribution information 171 may not be used.

[0050] The second filter processing unit 153 generates light source luminance information FLLD by performing a second filter process on the emission luminance of each light source element included in the light source luminance information LLD. This second filter process causes the emission luminance of each light source element to change at a predetermined speed with respect to the change in luminance of the image, as described in Figs. 6 and 7. The filter setting information 172 includes information for setting the filter characteristics of the second filter process. That is, the filter setting information 172 includes information for setting how fast the emission luminance should be changed with respect to the change in luminance of the image. The speed at which the emission luminance increases and the speed at which the emission luminance decreases may be set separately.

[0051] 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 in which a maximum fluctuation amount per frame is determined and the emission luminance is changed by an amount of fluctuation equal to or less than the maximum fluctuation amount. In this case, the filter setting information 172 includes information on the maximum fluctuation amount per frame.

[0052] The global dimming processor 155 generates light source luminance data DDIM by performing global dimming processing on the light source luminance information FLLD. The emission luminance in the light source luminance data DDIM changes at a predetermined speed in response to changes in the brightness of the environment as described in Fig. 4 and Fig. 5, and also changes at a predetermined speed in response to changes in the luminance of the image as described in Fig. 6 and Fig. 7. The global dimming processor 155 includes a first filter processor 156 and a multiplier 157.

[0053] The first filter processor 156 performs a first filter process on the global dimming parameter DIMG to generate a global dimming parameter FDIMG after the first filter process. The filter setting information 172 includes information for setting the filter characteristics of the first filter process. That is, the filter setting information 172 includes information for setting how quickly the light emission luminance is changed in response to a change in the global dimming parameter DIMG. The speed at which the light emission luminance increases and the speed at which the light emission luminance decreases may be set separately.

[0054] The first filter processing 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 processing is lower than the cutoff frequency of the second filter processing. Alternatively, the first filter processing may be a processing in which a maximum fluctuation amount per frame is determined and the emission luminance is changed by an amount of fluctuation equal to or less than the maximum fluctuation amount. In this case, the filter setting information 172 includes information on the maximum fluctuation amount per frame. The maximum fluctuation amount of the first filter processing is smaller than the maximum fluctuation amount of the second filter processing.

[0055] The multiplication unit 157 multiplies the global dimming parameter FDIMG after the first filter process by the light source luminance information FLLD after the second filter process, and outputs the result as the light source luminance data DDIM. As a result of the first filter process and the multiplication process, as described in Fig. 4 and Fig. 5, the luminance of the backlight 210 changes at a predetermined speed in response to the change in the brightness of the environment.

[0056] An explanatory diagram of the multiplication process is shown in Fig. 9. Here, it is assumed that the backlight 210 includes light source elements LG1 to LG48 arranged in a matrix of 6 rows and 8 columns.

[0057] The second filter processing unit 153 of the local dimming processing unit 151 outputs the light emission luminance FLLDp of the light source element LGp, where p is an integer between 1 and 48. The first filter processing unit 156 of the global dimming processing unit 155 outputs a global dimming parameter FDIMG common to the light source elements LG1 to LG48. The multiplication unit 157 multiplies the light emission luminance FLLDp of the light source element LGp by the global dimming parameter FDIMG, and outputs the result as light source luminance data DDIM. FIG. 9 shows an example in which the multiplication process is a simple multiplication, but the multiplication process is not limited to this and may include, for example, multiplication or addition of a coefficient.

[0058] 10 is a second detailed configuration example of the dimming circuit and the storage unit. Differences from the first detailed configuration example will be described. In the second detailed configuration example, the local dimming processing unit 151 does not include the second filter processing unit 153. The multiplication unit 157 of the global dimming processing unit 155 multiplies the global dimming parameter FDIMG after the first filter processing by the light source luminance information LLD output by the dimming processing unit 152.

[0059] 11 is a third detailed configuration example of the dimming circuit and the storage unit. Differences from the first detailed configuration example will be described. In the third detailed configuration 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 by the light source luminance information FLLD after the second filter processing. Note that the second filter processing unit 153 may be omitted, and the multiplication unit 157 may multiply the global dimming parameter FDIMG after the first filter processing input from the processing device 300 by the light source luminance information FLLD output by the dimming processing unit 152.

[0060] In this embodiment, the circuit device 100 controls a display device 200 including a plurality of light source elements and a display panel 220. The circuit device 100 includes a luminance analysis circuit 130 and a dimming circuit 150. The luminance analysis circuit 130 performs luminance analysis on image data IMA of an input image and outputs luminance information INT. The dimming circuit 150 performs a local dimming process for dimming each of the plurality of light source elements based on the luminance information INT, and a global dimming process using a global dimming parameter DIMG based on the sensor output of an external light sensor, thereby determining light source luminance information indicating the emission luminance of each light source element. The dimming circuit 150 performs a dimming process in which the speed at which the emission luminance is changed in the global dimming process is slower than the speed at which the emission luminance is changed in the local dimming process.

[0061] According to this embodiment, the change in the emission luminance in global dimming is relatively slower than the change in the emission luminance in local dimming. That is, when the brightness of the environment changes, the emission luminance of the backlight 210 changes relatively slowly, and when the brightness of the image changes, the emission luminance of the light source element corresponding to the change changes relatively quickly. As a result, 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 210 can be suppressed, and for example, flickering of the screen can be reduced. On the other hand, in local dimming, the emission luminance of the light source element is quickly changed in response to the brightness change of the image, thereby enabling dimming that appropriately follows a moving picture such as a video. According to this embodiment, appropriate dimming is possible in both global dimming and local dimming.

[0062] In this embodiment, the dimming circuit 150 may perform a first filter process based on a first time constant on the global dimming parameter DIMG. This causes the dimming circuit 150 to change the light emission luminance at a slower rate in the global dimming process than the light emission luminance at a local dimming process.

[0063] According to this embodiment, a first filter process based on a first time constant is performed on the global dimming parameter DIMG. As a result, when the global dimming parameter DIMG changes, the emission luminance of the backlight 210 changes with the first time constant. This first time constant allows the speed at which the emission luminance is changed in the global dimming process to be slower than the speed at which the emission luminance is changed in the local dimming process.

[0064] The first time constant is a time constant indicating the speed of change in the emission luminance determined by the first filter process. For example, the first filter 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 be a constant indicating the time at which the change in the emission luminance converges. As an example, the first filter process may be a process in which a maximum fluctuation amount per frame is determined and the emission luminance is changed by an amount of fluctuation equal to or less than the maximum fluctuation amount. In this case, the first time constant is the time until the change in the emission luminance converges when the emission luminance is changed by that amount of fluctuation for each frame.

[0065] In this embodiment, the dimming circuit 150 may also perform a second filtering process on the result of the local dimming process based on a second time constant that is shorter than the first time constant.

[0066] According to this embodiment, a first filtering process based on a first time constant is performed on the global dimming parameter DIMG, and a second filtering process based on a 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 at which the light emission luminance is changed in the global dimming process can be slower than the speed at which the light emission luminance is changed in the local dimming process.

[0067] The second time constant is a time constant indicating the speed of change in the emission luminance determined by the second filter process. For example, the second filter 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 be a constant indicating the time at which the change in the emission luminance converges. As an example, the second filter process may be a process in which a maximum fluctuation amount per frame is determined and the emission luminance is changed by an amount of fluctuation equal to or less than the maximum fluctuation amount. In this case, the second time constant is the time until the change in the emission luminance converges when the emission luminance is changed by that amount of fluctuation for each frame.

[0068] In this embodiment, the dimming circuit 150 may receive a global dimming parameter FDIMG that has been subjected to a first filter process based on a first time constant from outside the circuit device 100. The dimming circuit 150 may determine light source luminance information using a result of the local dimming process and the global dimming parameter FDIMG.

[0069] According to this embodiment, an external device such as the processing device 300 performs a first filter process based on a first time constant on the global dimming parameter DIMG. This allows the external device such as the processing device 300 to control the first time constant. In this case, the dimming circuit 150 sets the second time constant of the second filter process to a time constant shorter than the first time constant. This allows the speed at which the light emission luminance is changed in the global dimming process to be slower than the speed at which the light emission luminance is changed in the local dimming process.

[0070] In this embodiment, the light adjustment circuit 150 may perform a light adjustment process in which the speed at which the emitted light luminance is reduced in the global dimming process is slower than the speed at which the emitted light luminance is reduced in the local dimming process.

[0071] From the viewpoint of visibility, it is desirable for the backlight 210 to quickly become bright when the brightness of the environment increases. On the other hand, it is desirable for the backlight 210 not to adjust the dimming when the brightness of the environment temporarily decreases. According to this embodiment, 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, so that it becomes difficult for the backlight 210 to adjust the dimming when the brightness of the environment temporarily decreases.

[0072] In this embodiment, the light control circuit 150 may perform light control processing in which the speed at which the light emission luminance is increased in the local dimming processing is faster than the speed at which the light emission luminance is increased in the global dimming processing.

[0073] In local dimming, it is desirable for the light source luminance of each light-emitting element to quickly track the luminance of the surrounding image. According to this embodiment, 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, so that the light source luminance of each light-emitting element quickly tracks the luminance of the surrounding image.

[0074] 4. Dimming processing section and color correction circuit FIG. 12 is a flow of processing performed by the dimming processor. In the following, an example of an ambient light source element shown in FIG. 13 is used. In FIG. 13, the x direction is the horizontal scanning direction of the display panel, and the y direction is the vertical scanning direction of the display panel. Here, it is assumed that the luminance information INT is not downsampled, and the number of pixels of the luminance information INT is the same as the number of pixels of the image data IMA. In this case, (x, y) in FIG. 13 is the coordinate on the luminance information INT and also the coordinate on the input image. Note that when downsampling is performed, the coordinate in the luminance information INT after downsampling can be used instead of (x, y) in the dimming process.

[0075] In step S1, the light adjustment processing unit 152 initializes light source luminance information. For example, the light adjustment processing unit 152 initializes the luminance values ​​of all light source elements to zero.

[0076] In step S2, the light adjustment processing unit 152 selects one pixel from the pixels included in the luminance information INT. The selected pixel is referred to as the target pixel. In the loop from step S2 to step S5, the target pixels are selected sequentially. For example, the first pixel of the first scan line of the luminance information INT is selected in the initial step S2, and the second pixel, the third pixel, ... are selected sequentially in the subsequent steps S2. When all the pixels of the first scan line have been selected, the pixels of the second scan line are selected sequentially, and this is repeated up to the final scan line.

[0077] In step S3, the light adjustment processor 152 selects n×m light source elements around the target pixel. These n×m light source elements are also called surrounding light source elements. n and m may each be an integer of 2 or more.

[0078] As shown in Fig. 13, the position of the target pixel 22 is (i, j). i and j are integers, and the position (i, j) indicates the i-th pixel of the j-th scan line. In the example of Fig. 13, n = m = 4. The dimming processor 152 selects light source elements L1 to L16 in the two nearest columns in each of the +x direction and the -x direction and the two nearest rows in each of the +y direction and the -y direction based on the position (i, j). When k is an integer between 1 and 16, the position of the light source element Lk is expressed as (xk, yk).

[0079] In step S4 of FIG. 12, the light source luminance information for 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 luminance information INT and the attenuation rate distribution information 171 stored in the memory unit 170.

[0080] In step S5, the light adjustment processing unit 152 determines whether or not all pixels have been selected as target pixels. If all pixels have been selected, the process ends. If there are any unselected pixels, the process returns to step S2.

[0081] The update process of the light source luminance information in step S4 will now be described. The light adjustment processor 152 obtains a required change amount Δij indicating a required change amount in the amount of light that the target pixel 22 receives from the light source elements L1 to L16, by the following formula (1).

[0082]

number

[0083] In the above formula (1), INT ijis the luminance value of the target pixel 22 in the luminance information INT. The luminance value is the maximum value of the RGB pixel values ​​of the target pixel 22 in the image data IMA as described above. Alternatively, the luminance value may be a luminance value calculated by multiplying the RGB pixel values ​​of the target pixel 22 in the image data IMA by a coefficient, such as Y in the YCrCb space. lsf(k) is the attenuation rate of light that the light source element Lk illuminates the target pixel 22, and is calculated from an actual attenuation rate distribution or an attenuation rate distribution that approximates it. The dimming processing unit 152 calculates lsf(k) using the attenuation rate distribution information 171. The attenuation rate distribution information 171 is a lookup table or a function. powc(k) is the previous light source luminance information of the light source element Lk. The previous light source luminance information is light source luminance information calculated using the previous target pixel selected one before the current target pixel 22. The previous target pixel is the pixel at the position (i-1, j) one before the position (i, j) in the x direction.

[0084] The light adjustment processing unit 152 calculates the requested change amount Δ ij to the light source luminance information of the light source element Lk, thereby updating the light source luminance information.

[0085]

number

[0086] In the above equation (2), powu(k) is the current light source luminance information, that is, the updated light source luminance information.

[0087] Fig. 14 is a flow of the illumination luminance calculation process performed by the color correction circuit. The example of Fig. 13 is used again here, but the process performed by the color correction circuit 120 is a process separate from the process performed by the dimming processor 152. In addition, in the explanation of the dimming processor 152, (x, y) was used as the coordinates on the luminance information INT, but here (x, y) is the coordinates on the input image indicated by the image data IMA.

[0088] In step S11, the color correction circuit 120 selects one pixel from the pixels included in the image data IMA. The selected pixel is referred to as the target pixel. In the loop from step S11 to step S14, the target pixels are selected sequentially. For example, in the first step S11, the first pixel of the first scan line of the image data IMA is selected, and in the subsequent steps S11, the second pixel, the third pixel, ... are selected sequentially. When all the pixels of the first scan line have been selected, the pixels of the second scan line are selected sequentially, and this is repeated up to the final scan line.

[0089] In step S12, the color correction circuit 120 selects s×t light source elements around the target pixel. These s×t light source elements are also called surrounding light source elements. Each of s and t may be an integer of 2 or more. Figure 13 shows an example where s=t=4.

[0090] The position of the target pixel 22 is (i, j). i and j are integers, and the position (i, j) indicates the i-th pixel of the j-th scan line. The color correction circuit 120 selects light source elements L1 to L16 in the two nearest columns in each of the +x and -x directions and the two nearest rows in each of the +y and -y directions based on the position (i, j). When β is an integer between 1 and 16, the position of the light source element Lβ is expressed as (xβ, yβ).

[0091] In step S13, the color correction circuit 120 uses the light source luminance information of the selected s×t light source elements and the attenuation rate distribution information 171 to obtain illumination luminance information of the target pixel.

[0092] In step S14, the color correction circuit 120 determines whether or not all pixels have been selected as target pixels. If all pixels have been selected, the process ends. If there are any unselected pixels, the process returns to step S11.

[0093] The illumination luminance information calculation process in step S13 will now be described. The color correction circuit 120 obtains the illumination luminance information of the target pixel 22 by the following equations (3) and (4).

[0094]

number

[0095]

number

[0096] In the above formula (3), PL(i,j) is lighting luminance information for the pixel at position (i,j). pow(β) is light source luminance information determined by the dimming processor 152. lsf(β) is the attenuation rate of light that the light source element Lβ illuminates 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 an input to the lookup table, but the distance may also be used as an input to the lookup table.

[0097] 12 is executed up to the last pixel of the luminance information INT, the powu in the above formula (2) is used as pow in the above formula (3). Even if the loop of steps S2 to S5 is not executed up to the last pixel of the luminance information INT, the updating of the light source luminance information of the light source elements is completed sequentially as the target pixel advances, so the light source luminance information after the updating may be used as pow.

[0098] The color correction circuit 120 may obtain illumination luminance information of the target pixel from light source luminance information of all light source elements of the backlight 210, not just from light source luminance information of s×t light source elements surrounding the target pixel.

[0099] Although the present embodiment has been described in detail as above, it will be easily understood by those skilled in the art that many modifications are possible without substantially departing from the novel matters and effects of the present disclosure. Therefore, all such modifications are intended to be included in the scope of the present disclosure. For example, a term described at least once in the specification or drawings together with a different term having a broader meaning or synonymy can be replaced with that different term anywhere in the specification or drawings. In addition, all combinations of the present embodiment and modifications are also included in the scope of the present disclosure. In addition, the configurations and operations of the circuit device, backlight, display device, display system, processing device, electronic device, etc. are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0100] 22... target pixel, 100... circuit device, 120... color correction circuit, 130... luminance analysis circuit, 131... luminance extraction section, 132... downsampling section, 150... dimming circuit, 151... local dimming processing section, 152... dimming processing section, 153... second filter processing section, 155... global dimming processing section, 156... first filter processing section, 157... multiplication section, 170... memory section, 171... attenuation rate distribution information, 172... filter setting information, 200... display device, 210... backlight, 220... display panel, 230... display driver, 240... light source driver, 300... processing device, 400... display system, 500... electronic device, DIMG... global dimming parameter, FDIMG... global dimming parameter after first filter processing, FLLD... light source luminance information after second filter processing, IMA, IMB... image data, INT... luminance information, LG1 to LG48... light source element, LLD... light source luminance information

Claims

1. A circuit device for controlling a display device including a plurality of light source elements and a display panel, a luminance analysis circuit that performs luminance analysis on image data of an input image and outputs luminance information; a light control circuit that determines light source luminance information indicating the emission luminance of each of the light source elements by performing a local dimming process for dimming each of the light source elements based on the luminance information and a global dimming process using a global dimming parameter based on a sensor output of an external light sensor; Including, The dimming circuit includes: A circuit device comprising: a dimming process that performs a dimming process in which the speed at which the light emission luminance is changed in the global dimming process is slower than the speed at which the light emission luminance is changed in the local dimming process.

2. 2. The circuit device according to claim 1, The dimming circuit includes: A circuit device characterized in that, by performing a first filter processing based on a first time constant on the global dimming parameter, the speed at which the light emission luminance is changed in the global dimming processing is made slower than the speed at which the light emission luminance is changed in the local dimming processing.

3. 3. The circuit device according to claim 2, The dimming circuit includes: a circuit device that performs a second filter process on a result of the local dimming process based on a second time constant that is shorter than the first time constant;

4. 2. The circuit device according to claim 1, The dimming circuit includes: The global dimming parameter that has been subjected to a first filtering process based on a first time constant is input from an outside of the circuit device; A circuit device that determines the light source luminance information using a result of the local dimming process and the global dimming parameter.

5. 2. The circuit device according to claim 1, The dimming circuit includes: A circuit device comprising: a light control circuit for controlling a light intensity of a light emitted from a light source; a light control unit for controlling a light intensity of a light emitted from a light source;

6. 2. The circuit device according to claim 1, The dimming circuit includes: A circuit device comprising: a light control circuit for controlling a light emission brightness of a light source; a light control unit for controlling a light emission brightness of a light source;

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

8. A circuit arrangement according to any one of claims 1 to 7; The display device; A display system comprising:

Images