Circuit device and head-up display

Abstract

To provide a circuit arrangement that can appropriately detect a blinding error even when lighting control is performed.SOLUTION: A circuit arrangement 10 is used for a display unit 100 of a head-up display that projects an image by using display image data IMD and a light source, and the circuit arrangement includes a lighting control circuit 50 that performs lighting control of the light source based on image data IM; a color correction circuit 30 that performs color correction according to a result of the lighting control for the image data IM to output display image data IMD; and a blinding error detection circuit 90 that performs processing of detecting a blinding error in the head-up display according to the display image data IMD and the result of the lighting control.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a circuit device used in a head-up display. This circuit device detects the occurrence of a glare error when a glare index value calculated from display image data of the head-up display exceeds a threshold value. Meanwhile, in a display device, color correction is performed on image data, and the color-corrected display image data is sometimes displayed. For example, Patent Document 2 discloses a display device for a vehicle that corrects image data to a color tone that cancels a change in the color tone when the color tone of the backlight changes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-101784 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-117071 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, blinding errors, which are glare errors, are detected from display image data output to a head-up display. However, when color correction of the display image data is performed in accordance with dimming control of a light source, there is a risk that the error may not be detected properly if blinding errors are detected based on the display image data after color correction. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a circuit device used in a display device of a head-up display that projects an image using display image data and a light source, the circuit device including: a dimming control circuit that controls dimming of the light source based on image data; a color correction circuit that outputs the display image data by performing color correction on the image data according to a result of the dimming control; and a blinding error detection circuit that performs processing to detect a blinding error of the head-up display according to the display image data and the result of the dimming control.

[0006] Another aspect of the present disclosure relates to a head-up display including the circuit device described above and the display device that projects the display image based on the display image data from the circuit device. [Brief explanation of the drawings]

[0007] [Figure 1] 1 shows an example of the configuration of a circuit device according to an embodiment of the present invention. [Figure 2] An example of a head-up display. [Figure 3] 3 shows a detailed first configuration example of the circuit device of the present embodiment. [Figure 4] An example of the backlight and display panel configuration. [Figure 5] FIG. [Figure 6] 10 is a flowchart illustrating a process of calculating brightness for each pixel. [Figure 7] FIG. [Figure 8] FIG. 10 is an explanatory diagram of inverse color correction. [Figure 9] 10 shows a detailed second configuration example of the circuit device of the present embodiment. [Figure 10] 1A and 1B are explanatory diagrams of an input image, an output image, and an HUD display image of a distortion correction circuit. [Figure 11] 10 shows a detailed third configuration example of the circuit device of the present embodiment. [Figure 12] 10 is a detailed fourth configuration example of the circuit device of the present embodiment. [Figure 13] 10 shows a detailed fifth configuration example of the circuit device of the present embodiment. [Figure 14] 1 shows an example of the configuration of a head-up display according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] 1.Circuit device 1 shows an example of the configuration of a circuit device 10 according to this embodiment. The circuit device 10 includes a color correction circuit 30, a dimming control circuit 50, and a blinding error detection circuit 90.

[0010] The circuit device 10 is, for example, an integrated circuit device in which a plurality of circuit elements are integrated on a semiconductor substrate. The display device 100 displays an image based on display image data IMD from the circuit device 10. Specifically, the display device 100 is a display device for a head-up display that projects an image using the display image data IMD and a light source. For example, the display device 100 is a device for displaying a virtual image in the user's field of vision. The display device 100 is composed of, for example, a display panel, a display driver, etc. The display device 100 may also include a light source device such as a backlight. The circuit device 10 of this embodiment is a circuit device used in such a display device for a head-up display.

[0011] The color correction circuit 30 performs color correction on the image data IM and outputs the display image data IMD to the display device 100. That is, the color correction circuit 30 performs color correction on the image data IM and outputs the color-corrected image data IM as display image data IMD to the display device 100. Specifically, the color correction circuit 30 performs color correction on the image data IM according to the result of dimming control, and outputs the display image data IMD. The color correction is, for example, a color adjustment process for the image data IM, and is a correction process for adjusting the color level. The color correction can also be called a brightness correction or gradation correction for the image data IM.

[0012] The dimming control circuit 50 performs dimming control of the light source based on the image data IM. The dimming control is a control for adjusting the light amount of a light source device such as a backlight. The dimming control may be a local dimming dimming control that controls the brightness of a light source device such as a backlight for each of multiple areas, or may be a dimming control that globally controls the brightness of the entire display screen.

[0013] When the dimming control circuit 50 performs dimming control to display the display image data IMD on the display device 100, the color correction circuit 30 performs color correction on the image data IM according to the dimming amount in the dimming control. The dimming control involves reducing the light intensity of the light source of the light source device in order to reduce power consumption of the light source device or make black pixels appear blacker. In this case, the color correction circuit 30 performs color correction to increase the luminance of the pixels corresponding to the light source on the display screen of the display device 100 by the amount of the reduced light intensity of the light source. For example, the color correction circuit 30 performs color correction on each pixel value of the image data IM so that the image displayed on the display device 100 based on the display image data IMD has the same brightness and color as the image of the image data IM, and outputs the color-corrected image data IM to the display device 100 as display image data IMD. The color correction circuit 30 may also perform color correction to adjust the color tone, etc., of the image displayed on the display device 100.

[0014] The blinding error detection circuit 90 performs a process of detecting a blinding error in the head-up display. For example, the blinding error detection circuit 90 performs a process of detecting a blinding error according to the display image data IMD and the result of the dimming control.

[0015] For example, Figure 2 shows an example of a head-up display. Note that below, a head-up display will be referred to as an HUD where appropriate. A HUD includes a display panel, a backlight, and a projection optical system such as a reflector. The backlight emits light, which passes through a display panel such as an LCD panel, is reflected by the reflector toward a screen, and the light reflected by the screen enters the user's eyes. As a result, a virtual image object 6 corresponding to the object displayed on the display panel is projected into the user's field of vision. This virtual image object 6 is superimposed on the real space that is the background of the HUD display. The areas within the HUD display area 5 where the virtual image object 6 is not displayed are transparent areas with no display because the display panel is opaque, and the background is visible as is.

[0016] Typically, the display objects 6 occupy a small proportion of the display area 5 so that the user can see the background that is visible through the display area 5. However, if a large proportion of the display objects 6 obscure the background in the HUD display area 5, the user will not be able to see the background in the area where the display objects 6 are displayed. That is, the HUD's display objects 6 obscure the background, potentially reducing the visibility of the background that overlaps the display objects 6. Alternatively, if the HUD display is too bright compared to the background, the visibility of the background will be reduced. For example, suppose that pixel values ​​range from 0 to 255, and pixels with a pixel value of 0 are transparent to the background. In this case, as the pixel value increases from 0, the background becomes less visible through those pixels. When the proportion of pixels obscuring the background becomes high, the visibility of the background will be reduced as described above. In this embodiment, a display error in which the visibility of the background is reduced due to the obscuration of the display objects 6 or the HUD display being too bright is referred to as a blinding error. A blinding error can also be called an occlusion error or a glare error.

[0017] The blinding error detection circuit 90 detects such blinding errors. When a blinding error is detected, the blinding error detection circuit 90 outputs error detection information. For example, in FIG. 1, the blinding error detection circuit 90 outputs an error detection signal ERR as the error detection information. Note that the blinding error detection circuit 90 may also output error detection data of a blinding error as the error detection information. This error detection data is written, for example, to a register (not shown) that can be accessed by an external processing device.

[0018] Here, in the conventional technology of Patent Document 1 mentioned above, blinding errors are detected by checking only the display image data IMD output to the display device 100 and checking the brightness of specific areas of the display panel and the proportion of specific pixels.

[0019] However, the method of detecting blinding errors by checking only the display image data IMD has a problem in that when HUD dimming control and color correction of the display image according to the dimming control are performed, the luminance of the image projected by the HUD onto the windshield of the automobile, etc. cannot be correctly analyzed. In other words, although blinding errors should be detected taking dimming control and color correction into consideration, the method of checking only the display image data IMD cannot properly detect blinding errors.

[0020] Therefore, in this embodiment, the blinding error detection circuit 90 performs a blinding error detection process based on the display image data IMD and the result of the dimming control by the dimming control circuit 50. That is, in this embodiment, the dimming control circuit 50 controls the dimming of a light source such as a backlight based on the image data IM. The color correction circuit 30 then performs color correction on the image data IM based on the result of the dimming control, thereby outputting the display image data IMD. That is, in this embodiment, when dimming control is performed in the display device 100, the color correction circuit 30 performs color correction on the image data IM, which is a color adjustment that reflects the adjustment amount of the dimming control, so that the displayed colors remain the same even when the dimming amount changes. The blinding error detection circuit 90 then performs a blinding error detection process based on the display image data IMD and the result of the dimming control. This makes it possible to detect a blinding error that reflects the result of the dimming control by the dimming control circuit 50. For example, by reflecting the result of the dimming control, it is possible to detect a blinding error using image data with a luminance state corresponding to the original image data IM, rather than the luminance state of the display image data IMD after dimming control has been performed. Therefore, compared to a method of detecting a blinding error using only the display image data IMD, it is possible to properly detect a blinding error even when dimming control is performed.

[0021] Here, various processes can be considered for detecting a blinding error. For example, a blinding error can be detected by calculating the luminance of the color of a blinding error determination area from image data, or by calculating the integrated or average luminance of the determination area. Alternatively, a blinding error can be detected based on the number or ratio of pixels whose luminance exceeds a threshold. Alternatively, a blinding error can be detected based on the number or ratio of pixels whose luminance is below a threshold. When a blinding error is detected, control is performed to stop the supply of display image data IMD to the display device 100 or to turn off the backlight 120. The backlight may be turned off for the entire screen, or may be turned off for the light source corresponding to the area where the error was detected. Alternatively, when a blinding error is detected, a process may be performed to display the area where the error was detected or the entire screen in black. For example, the display image data IMD may be made transparent. A transparent color is a color that, when the color displayed on the display panel is projected by the HUD, nothing is displayed on the HUD display, allowing the background to be seen as is. Specifically, when the pixels of the display panel block light, the HUD display should become transparent, so the color that appears black when displayed on the display panel corresponds to the transparent color. For example, black data in the display image data IMD becomes the transparent color in the HUD display.

[0022] For example, the blinding error detection circuit 90 performs blinding error detection processing by calculating a blinding error determination index value and comparing the determination index value with a threshold. Specifically, the blinding error detection circuit 90 calculates a blinding error determination index value according to the display image data IMD and the result of dimming control, and compares the determination index value with a threshold to detect a blinding error. The blinding error determination index value according to the display image data IMD and the result of dimming control is, for example, a determination index value calculated based on the display image data IMD and the result of dimming control. The image data calculated based on the display image data IMD and the result of dimming control is, for example, inverse color-corrected image data, which will be described later, or inversely distortion-corrected image data based on the inverse color-corrected image data. The blinding error determination index value is an index value that indicates the degree to which the visibility of the background is reduced by the display image data IMD when the image is displayed on the HUD. For example, when an image of an object displayed on a HUD obscures the background, or when the background is difficult to see due to the glare of the image displayed on the HUD, the blinding error determination index value indicates the extent of these cases. The blinding error determination index value can also be called the occlusion error determination index value or the glare error determination index value.

[0023] The blinding error determination index value is, for example, the integrated value or average value of the luminance of pixels in the blinding error determination area. For example, the integrated value can be calculated by integrating the pixel values ​​of the pixels in the determination area, or the average value can be calculated by dividing the integrated value by the number of pixels in the determination area. As an example, the blinding error determination index value DV can be calculated using the formula DV = C1 × Rsum + C2 × Gsum + C3 × Bsum. Here, Rsum is the integrated value of red pixel values, Gsum is the integrated value of green pixel values, Bsum is the integrated value of blue pixel values, and C1, C2, and C3 are coefficients. The coefficients C1, C2, and C3 are coefficients used when converting RGB pixel values ​​to YCrCb luminance values ​​Y, and are set appropriately depending on the color space used in the image data. However, the coefficients C1, C2, and C3 are not limited to these and may be any real numbers greater than 0. Alternatively, the blinding error determination index value DV may be calculated by calculating the luminance value Y for each pixel and then integrating Y. In this case, Y = C1 × Rpx + C2 × Gpx + C3 × Bpx, and DV = Ysum. Rpx, Gpx, and Bpx are the red, green, and blue pixel values ​​of one pixel. Ysum is the integrated value of the luminance value Y.

[0024] Alternatively, the number of high-luminance pixels in the judgment area whose luminance exceeds a threshold value, or the ratio of the number of high-luminance pixels to the total number of pixels, may be calculated as a blinding error judgment index value. Then, when the judgment index value, which is the number or ratio of high-luminance pixels, exceeds the threshold value, it is determined that a blinding error has been detected. Alternatively, the number of black pixels in the judgment area, or the ratio of the number of black pixels to the total number of pixels, may be calculated as a blinding error judgment index value. Black pixels are pixels of black data, but are not limited to completely black data, and may be substantially black data. Then, when the judgment index value, which is the number or ratio of black pixels, is smaller than the threshold value, it is determined that a blinding error has been detected. In this way, various index values ​​can be used as the blinding error judgment index value.

[0025] The color correction circuit 30, the dimming control circuit 50, and the blinding error detection circuit 90 are logic circuits. These logic circuits may be configured as separate circuits, or may be configured as an integrated circuit using automatic placement and routing or the like. Alternatively, some or all of these logic circuits may be realized by a processor such as a DSP (Digital Signal Processor). In this case, a program or instruction set describing the function of each circuit is stored in memory, and the function of each circuit is realized by the processor executing the program or instruction set.

[0026] 2. First configuration example Fig. 3 shows a detailed first configuration example of the circuit device 10 of this embodiment. In addition to the configuration of Fig. 1, the circuit device 10 of Fig. 3 includes a distortion correction circuit 20, a light source control circuit 60, and a color inverse correction circuit 40. Note that the circuit device 10 is not limited to the configuration of the first configuration example of Fig. 3 or other configuration examples described later, and various modifications are possible, such as omitting some of the components, adding other components, or replacing some of the components with other components.

[0027] A processing device 200 is provided outside the circuit device 10. The processing device 200 is, for example, an SoC (System on Chip), and more specifically, a microcomputer, a CPU, or an MPU. For example, the circuit device 10 is communicatively connected to the processing device 200 via an interface circuit (not shown). Then, for example, input image data IMI from the processing device 200 is input to the circuit device 10 via the interface circuit.

[0028] The display device 100 includes a display panel 110, a backlight 120, and light source drivers 130-1 to 130-n, where n is an integer equal to or greater than 2. The display device 100 may also include a display driver (not shown) that drives the display panel 110. The display driver drives the display panel 110 based on display image data IMD from the circuit device 10, causing a display image to be displayed on the display panel 110. The display driver may include a data driver that drives data lines of the display panel 110, a scan driver that drives scan lines of the display panel 110, a display controller, and the like. The backlight 120 is provided with a plurality of light sources LS. For example, the plurality of light sources LS are arranged in an array.

[0029] 4 shows an example of the configuration of the backlight 120 and the display panel 110. In FIG. 4, direction D1 is the horizontal scanning direction of the display panel 110, and direction D2 is the vertical scanning direction of the display panel 110. Direction D3 is a direction perpendicular to directions D1 and D2, and is the direction in which the display panel 110 is viewed in plan. The backlight 120 is provided on the direction D3 side of the display panel 110, and emits illumination light in the opposite direction to direction D3, which is the direction toward the display panel 110.

[0030] The backlight 120 includes multiple light sources LS. FIG. 4 illustrates an example in which 8×5 light sources LS are arranged in a two-dimensional array. That is, eight light sources LS are arranged along direction D1, and five light sources LS are arranged along direction D2. For proper local dimming, it is desirable to provide the backlight 120 with, for example, 100 or more light sources LS. The light sources LS are, for example, light-emitting diodes (LEDs). Note that the light sources LS are not limited to LEDs, and any light source whose light output is independently controlled and approximates a point light source is sufficient. A light source approximates a point light source in that the size of the light-emitting portion of the light source LS is sufficiently smaller than the area AR corresponding to the light source LS. The light sources LS may be arranged in various configurations, such as a square arrangement or a hexagonal arrangement.

[0031] The display panel 110 has a pixel array, and the area of ​​the pixel array where a display image is displayed is referred to as the display area. The display area is divided into multiple areas AR. A light source LS is arranged corresponding to each area AR. That is, one light source LS corresponds to one area AR. For example, when the display panel 110 is viewed in a plan view, the light source LS is arranged at the center of the area AR. However, the arrangement position of the light source LS is not limited thereto. In FIG. 4, the display area is divided into 8 × 5 areas AR corresponding to the 8 × 5 light sources LS. Note that the areas AR are used for processing in the circuit device 10, and the boundaries of the areas AR do not exist in the display image actually displayed on the display panel 110. The display panel 110 is a panel in which the transmittance of each pixel is controlled according to the display image, and each pixel transmits illumination light from the backlight 120 to display the display image. For example, the display panel 110 is a liquid crystal display panel.

[0032] In this way, when the display area of ​​the display panel 110 is divided into multiple areas AR, with each light source LS disposed in each area AR, the light source LS that illuminates the display panel 110 has a light intensity distribution in which the light intensity decreases the further away from the light source LS. Therefore, the light intensity is lower at the periphery of the area AR than at the center. This light intensity distribution of the light source LS is called a PSF. Figure 5 shows an example of the light intensity distribution of the PSF. In Figure 5, the light intensity distribution is shown using a gradation, with whiter colors indicating larger coefficients of the light intensity distribution. In Figure 5, the size of the PSF corresponds to 3 x 3 areas AR1 to AR9, and the center of the PSF is located at the position of the light source.

[0033] As shown in FIG. 3, the circuit device 10 includes an inverse color correction circuit 40 that performs inverse color correction. Specifically, the inverse color correction circuit 40 performs inverse color correction on the display image data IMD to output inverse color-corrected image data IMR. Inverse color correction is the inverse of the color correction performed by the color correction circuit 30, and is the inverse conversion of the conversion performed in the color correction. For example, the inverse color correction performed by the inverse color correction circuit 40 is a color correction to return the color-corrected display image data IMD to the original image data IM. For example, if color correction is performed to increase the luminance of each pixel of the display image data IMD due to a decrease in the light source light intensity in the dimming control of the dimming control circuit 50, the inverse color correction circuit 40 performs inverse color correction to reduce the increased luminance and return it to the original luminance. Alternatively, if the hue is changed by color correction, inverse color correction may be performed to return the changed hue to the original hue. The inverse color-corrected image data IMR output by the inverse color correction circuit 40 does not need to match the original image data IM completely; they only need to match within a predetermined error range. The error range is, for example, the range of rounding error, etc. Furthermore, the resolution of the inverse color corrected image data IMR and the original image data IM do not have to match, and for example, the inverse color corrected image data IMR may be image data with a lower resolution.

[0034] The circuit device 10 also includes a distortion correction circuit 20. The distortion correction circuit 20 performs distortion correction on input image data IMI and outputs image data IM. The color correction circuit 30 performs color correction on the image data IM from the distortion correction circuit 20. The input image data IMI is input from the processing device 200, for example, via an interface circuit (not shown).

[0035] Specifically, the distortion correction circuit 20 performs distortion correction on the input image data IMI using coordinate transformation between pixel coordinates in the input image data IMI and pixel coordinates in the image data IM, and outputs the result as image data IM. Distortion correction involves applying image distortion to the image displayed on the display panel 110 that is the opposite of the image distortion that occurs when the image is projected. This image correction is intended to create a HUD display with reduced or no distortion. Image distortion due to projection includes image distortion due to the curved surface of the HUD screen, image distortion due to the HUD optical system, or both. For example, a HUD presents an image to a user by projecting it onto a transparent screen or displaying it on a transparent display panel. By transforming the image to match the curvature of the transparent screen or transparent display panel, the user sees an image without distortion. The distortion correction circuit 20 performs this image transformation process as distortion correction.

[0036] For example, the distortion correction circuit 20 performs reverse mapping or forward mapping. Reverse mapping, also known as reverse warping, is a mapping process that transforms pixel coordinates in image data IM, which is output image data, into corresponding reference coordinates and then obtains pixel data of the image data IM from pixel data of the input image data IMI at those reference coordinates. Forward mapping, also known as forward warping, is a mapping process that transforms pixel coordinates in the input image data IMI into corresponding destination coordinates and then obtains pixel data of the image data IM at those destination coordinates from pixel data of the input image data IMI at those pixel coordinates. The coordinate transformations in reverse mapping and forward mapping are defined by mapping parameters, also known as map data. The mapping parameters are a table that associates coordinates on an input image with coordinates on an output image, a table that indicates the amount of movement between coordinates on the input image and coordinates on the output image, or polynomial coefficients that associate coordinates on the input image with coordinates on the output image.

[0037] The dimming control circuit 50 performs dimming control of the light source based on the image data IM. Specifically, the dimming control circuit 50 performs dimming control of the backlight 120, which has multiple light sources, thereby achieving dimming control known as local dimming. For example, the dimming control circuit 50 performs arithmetic processing to determine information on the dimming amount based on the image data IM. The dimming amount information here is information for specifying the brightness at which the light source is to be illuminated by dimming control. The light source control circuit 60 performs control processing and instruction processing for the light source drivers 130-1 to 130-n of the display device 100 based on the dimming amount information from the dimming control circuit 50. The light source drivers 130-1 to 130-n, which are LED drivers, then drive the light sources LS of the backlight 120 based on the dimming amount information, thereby achieving dimming control of the backlight 120. For example, local dimming is achieved, in which dimming control is performed on each of multiple areas obtained by dividing the display area of ​​the display panel 110.

[0038] A processing device such as an MCU may be provided between the light source control circuit 60 and the light source drivers 130-1 to 130-n to absorb differences in communication protocols depending on the model of the light source drivers 130-1 to 130-n. In this case, the light source control circuit 60 controls the light source drivers 130-1 to 130-n via the processing device such as an MCU.

[0039] The dimming control circuit 50 includes a luminance analysis circuit 52 and a dimming amount calculation circuit 54. The luminance analysis circuit 52 performs luminance analysis of the image data IM. The dimming amount calculation circuit 54 calculates the dimming amount of each light source based on the results of the luminance analysis. Specifically, the luminance analysis circuit 52 searches for the pixel with the maximum luminance in each of the multiple areas of the display area based on the image data IM. The luminance analysis circuit 52 then determines the luminance distribution for each light source so that the color of the searched maximum luminance can be displayed. The dimming amount calculation circuit 54 then performs an arithmetic process to recalculate the luminance for each pixel based on the determined luminance distribution of the light source and diffusion coefficient information for the light source, and calculates the dimming amount corresponding to the luminance value of the backlight 120 for each pixel. The diffusion coefficient information is, for example, information on the diffusion coefficient parameter of the diffuser 115 shown in FIG. 14 (described later). Furthermore, information on the dimming amount from the dimming amount calculation circuit 54 is sent to the light source drivers 130-1 to 130-n via the light source control circuit 60, and the light source drivers 130-1 to 130-n drive the light sources of each of the multiple areas to emit light according to the dimming amount, thereby realizing local dimming.

[0040] Meanwhile, the color correction circuit 30 performs color correction in response to the dimming control performed by the dimming control circuit 50 and outputs the display image data IMD to the display device 100. For example, the display image data IMD is output to the display device 100 via an interface circuit (not shown). For example, the color correction circuit 30 performs color correction in response to the dimming control of the backlight 120 based on dimming level information from the dimming level calculation circuit 54. For example, when dimming control is performed to reduce the light intensity of the light source in an area corresponding to the light source, the color correction circuit 30 performs color correction to increase the luminance of the pixels in that area by the amount of the reduction in the light intensity of the light source in that area, and outputs the color-corrected display image data IMD to the display device 100. This reduces the light intensity of the light source in that area and enables an image corresponding to the original image data IM to be displayed in that area based on the color-corrected display image data IMD, thereby achieving local dimming. As a result, it is possible to reduce the power consumption of the backlight 120 and display an image in which black pixels appear blacker.

[0041] Furthermore, the inverse color correction circuit 40 performs inverse color correction on the color-corrected display image data IMD, thereby outputting inverse color-corrected image data IMR. For example, the inverse color correction circuit 40 performs inverse color correction to return the color-corrected display image data IMD to the image data IM before color correction, based on the display image data IMD and the dimming amount information from the dimming amount calculation circuit 54. For example, if dimming control is performed to reduce the light amount of the light source in an area corresponding to the light source, and color correction is performed to increase the brightness of the pixels in that area, the inverse color correction circuit 40 performs inverse color correction to reduce the brightness of the pixels in that area to restore them to their original state, and outputs the inverse color-corrected image data IMR.

[0042] As described above, the circuit device 10 of this embodiment includes the inverse color correction circuit 40 that performs inverse color correction on the display image data IMD based on the result of dimming control, and outputs inverse-color-corrected image data IMR. The blinding error detection circuit 90 then performs blinding error detection processing based on the inverse-color-corrected image data IMR.

[0043] This realizes a blinding error detection process according to the display image data IMD and the results of the dimming control. That is, the inverse color correction circuit 40 performs inverse color correction based on the display image data IMD and the dimming amount information from the dimming amount calculation circuit 54, and outputs the inverse color-corrected image data IMR. Therefore, the inverse color-corrected image data IMR is image data based on the display image data IMD and the results of the dimming control. By detecting a blinding error based on this inverse color-corrected image data IMR, a blinding error detection process according to the display image data IMD and the results of the dimming control is realized. For example, the blinding error detection circuit 90 calculates a blinding error determination index value based on the inverse color-corrected image data IMR and compares this determination index value with a threshold value to detect a blinding error. If a blinding error is detected, the supply of the display image data IMD to the display device 100 is stopped, the backlight 120 is turned off, or the display image data IMD in the error detection area is made transparent. These processes may be performed by the circuit device 10 or by a processing device 200 external to the circuit device 10. In this way, it becomes possible to prevent a situation in which the visibility of the background is reduced due to a blinding error.

[0044] For example, a method of detecting a blinding error based solely on the display image data IMD output to the display device 100 may fail to accurately reflect the dimming control of the dimming control circuit 50 and the color correction of the color correction circuit 30. That is, when the dimming control circuit 50 controls the dimming of the backlight 120, the color correction circuit 30 performs color correction in accordance with the dimming control, and the color-corrected display image data IMD is output to the display device 100. Therefore, due to the color correction in accordance with the dimming control, the color levels of the display image data IMD differ from the color levels of the original image data IM, and a detection process using only the display image data IMD may fail to accurately detect a blinding error. For example, in an area where the light intensity of the light source is reduced due to dimming control, color correction is performed on the display image data IMD to increase the luminance of the pixels in that area. Therefore, detecting a blinding error based solely on the display image data IMD may result in a false detection of a blinding error in that area. For example, a blinding error may be falsely detected when it is not. Alternatively, if color correction is performed by increasing the amount of light from the light source and reducing the brightness of the pixels accordingly, there is a risk that the actual blinding error will not be detected if the blinding error is detected based only on the display image data IMD.

[0045] In this regard, in FIG. 3 , inverse color correction is performed on the display image data IMD based on the results of dimming control, thereby generating inverse-color-corrected image data IMR corresponding to the original image data IM, and a blinding error is detected based on this inverse-color-corrected image data IMR. In this manner, blinding errors can be detected based on the inverse-color-corrected image data IMR restored from the original image data IM, rather than on the display image data IMD that has been color-corrected in accordance with dimming control. Therefore, blinding errors can be properly detected even when dimming control or color correction based on dimming control is performed. That is, when dimming control is performed by the dimming control circuit 50 and a display image based on the color-corrected display image data IMD is displayed on the display panel 110, the user's eyes see an image corresponding to the original image data IM. Therefore, by detecting blinding errors based on the inverse-color-corrected image data IMR corresponding to the original image data IM, proper error detection can be achieved.

[0046] The color correction circuit 30, the inverse color correction circuit 40, the blinding error detection circuit 90, the distortion correction circuit 20, the dimming control circuit 50, and the light source control circuit 60 are logic circuits, and these logic circuits may be configured as separate circuits or may be configured as an integrated circuit by automatic placement and routing or the like. Alternatively, some or all of these logic circuits may be realized by a processor such as a DSP. The same applies to other configuration examples described below.

[0047] Next, a specific example of processing in this embodiment will be described. FIG. 6 is a flowchart illustrating an example of processing for calculating the luminance of each pixel. First, for each area of ​​each light source, a search is made for a pixel with the maximum luminance (step S1). For example, in each area corresponding to each light source described in FIGS. 4 and 5, the luminance of pixels in that area is searched for based on image data IM, and the pixel with the maximum luminance in that area is found. Then, a luminance distribution for each light source is determined so that the color of the pixel with the maximum luminance can be displayed (step S2). For example, assume that the luminance range is 0 to 100 and the luminance of the pixel with the maximum luminance in the target area is 50. In this case, the luminance distribution of the light source is determined so that the pixel with the maximum luminance of 50 can be displayed in a color with a luminance of 100, for example, which is the upper limit of the luminance range. If the luminance of the pixel with the maximum luminance is at the upper limit of the luminance range, the luminance of the other pixels is guaranteed to be within the luminance range of 0 to 100. Then, the luminance is recalculated for each pixel of the display panel 110 based on the diffusion coefficient information (step S3). This determines the brightness value of the backlight 120 for each pixel.

[0048] For example, as shown in FIG. 14 (described later), the display device 100 includes a diffuser 115 between the backlight 120 and the display panel 110 to diffuse light from the light source and achieve a uniform luminance distribution. The diffuser 115 is also called a diffusion sheet. For example, as shown in FIG. 5 (a), the light intensity distribution PSF of the light source is an intensity distribution in which the light intensity decreases with increasing distance from the light source. However, by providing the diffuser 115 to diffuse the light from the light source, luminance unevenness can be reduced, enabling the realization of a uniform surface light source. Examples of light diffusion methods include direct, sidelight, and edgelight. In step S3 of FIG. 6 (b), the luminance of each pixel of the display panel 110 is recalculated, taking into account the light intensity distribution PSF of the light source shown in FIG. 5 as well as the diffusion of light from the light source by the diffuser 115, thereby obtaining the luminance value of the backlight 120 for each pixel. As an example, for a target pixel, the luminance is recalculated by determining the intensity of light from, for example, 4×4 LED light sources around the pixel based on the light intensity distribution PSF of Fig. 5 and the diffusion coefficient information of the diffuser 115, thereby determining the luminance value of the backlight 120 for each pixel. In this way, in the display device 100 having the backlight 120 with multiple light sources and the diffuser 115, it becomes possible to properly determine the luminance value of the backlight 120 for each pixel.

[0049] FIG. 7 is an explanatory diagram of an example of color correction processing. First, the luminance B of the backlight 120 of the target pixel is calculated as described in FIG. 6. A luminance-coefficient table is stored in a memory circuit (not shown) of the circuit device 10, and this table is used to calculate the coefficient K from the luminance B of the backlight 120. The luminance-coefficient table of FIG. 7 is configured so that the coefficient K increases as the luminance B decreases. Instead of using such a luminance-coefficient table, the coefficient K may be calculated from the luminance B based on a predetermined formula. While the luminance-coefficient table of FIG. 7 has linear characteristics, this is not limiting and any appropriate characteristics may be used in accordance with the human eye's response to light brightness. The coefficient K may also be calculated by interpolating the two output values ​​of the luminance-coefficient table using linear interpolation, spline interpolation, or the like. The coefficient K thus calculated is then multiplied by the level of the color C of the target pixel to determine the color level to be output to the display device 100. That is, a process is performed to increase the color level of image data for pixels with low luminance B of the backlight 120. In this way, the color correction circuit 30 can obtain display image data IMD from the image data IM and output it to the display device 100. In the brightness-coefficient table of Fig. 7, the coefficient K increases as the brightness B of the backlight 120 decreases, and therefore the color level of the target pixel increases as the brightness of the backlight 120 for the target pixel decreases, making it possible to achieve dimming control.

[0050] FIG. 8 is an explanatory diagram of an example of the inverse color correction process. First, a coefficient K is calculated based on the luminance B of the backlight 120 of the target pixel and a luminance-coefficient table. In the luminance-coefficient table of FIG. 7, the coefficient K increases as the luminance B of the backlight 120 decreases. However, in FIG. 8, the coefficient K decreases as the luminance B decreases, which is the opposite of FIG. 7. By using a table with such characteristics, it is possible to achieve the inverse color correction of the color correction of FIG. 7. The coefficient K thus calculated is then multiplied by the color CQ level of the output pixel to determine the color level of the original image. That is, while color correction involves increasing the color level of image data for pixels with a low luminance B of the backlight 120, inverse color correction involves decreasing the color level of image data for pixels with a low luminance B of the backlight 120. In this way, the inverse color correction circuit 40 can calculate inverse-color-corrected image data IMR corresponding to the original image data IM from the display image data IMD and output the result to the blinding error detection circuit 90. That is, in the brightness-coefficient table of Fig. 8, the coefficient K decreases as the brightness of the backlight 120 decreases, so it is possible to perform inverse color correction, which is the inverse conversion of the color correction of Fig. 7, on the display image data IMD to obtain inverse-color-corrected image data IMR corresponding to the original image data IM. Then, the blinding error detection circuit 90 performs blinding error detection processing based on the inverse-color-corrected image data IMR. In this way, blinding error detection processing according to the display image data IMD and the result of dimming control is realized.

[0051] Note that instead of using a brightness-coefficient table such as that shown in Figure 8, the coefficient K may be calculated from the brightness B based on a predetermined formula. The coefficient K may also be calculated by interpolating the two output values ​​of the brightness-coefficient table using linear interpolation, spline interpolation, or the like. Although Figures 7 and 8 show separate tables for color correction and inverse color correction, the color level of the original image may also be calculated by using the color correction table in Figure 7 and dividing the color CQ of the output pixel by the coefficient K.

[0052] As described above, in this embodiment, the color correction circuit 30 performs color correction on the image data IM according to the luminance of the light source of the display device 100. The inverse color correction circuit 40 performs inverse color correction on the display image data IMD according to the luminance of the light source of the display device 100.

[0053] In this way, when dimming control is performed to control the luminance of the light source of the display device 100, color correction according to the luminance of the light source due to the dimming control is performed on the image data IM, and color-corrected display image data IMD is output to the display device 100. Furthermore, by performing inverse color correction according to the luminance of the light source on the display image data IMD, inverse-color-corrected image data IMR corresponding to the original image data IM is output to the blinding error detection circuit 90. This allows the blinding error detection circuit 90 to detect a blinding error based on the inverse-color-corrected image data IMR restored from the original image data IM, rather than on the display image data IMD. Therefore, even when dimming control or color correction based on the dimming control is performed, it is possible to properly detect a blinding error.

[0054] Specifically, as shown in Fig. 3, the display device 100 includes a display panel 110 and a backlight 120 having a plurality of light sources. As described with reference to Figs. 4 and 5, a plurality of light sources are provided corresponding to each of a plurality of areas of the display panel 110. The color correction circuit 30 performs color correction on the image data IM according to the luminance of each light source, and the inverse color correction circuit 40 performs inverse color correction on the display image data IMD according to the luminance of each light source.

[0055] In this way, when dimming control is performed to control the luminance of the multiple light sources of the backlight 120, color correction according to the luminance of each of the multiple light sources due to the dimming control is performed on each pixel illuminated with light from each light source in the image data IM, and color-corrected display image data IMD is output to the display device 100. Furthermore, by performing inverse color correction according to the luminance of each of the multiple light sources of the backlight 120 on each pixel illuminated with light from each light source in the display image data IMD, inverse color-corrected image data IMR corresponding to the original image data IM is output to the blinding error detection circuit 90, and a blinding error can be detected. This makes it possible to properly detect blinding errors even when dimming control of the backlight 120 or color correction based on the dimming control is performed.

[0056] For example, the display device 100 displays an image by emitting light from the light source of the backlight 120 to the display panel 110 and driving the display panel 110 to display based on display image data IMD from the circuit device 10. Taking the head-up display 190 of Fig. 14 as an example, the image displayed on the display panel 110 is projected onto a transparent screen 160, which is the windshield, so that a virtual image corresponding to the displayed image is displayed to the user. The dimming control circuit 50 also performs dimming control to control the brightness of the light source of the backlight 120 based on the image data IM.

[0057] Then, the color correction circuit 30 performs color correction according to the luminance of the light source of the backlight 120, as described in FIG. 7. For example, the color correction circuit 30 performs color correction such that the color level of each pixel of the display image data IMD increases as the luminance of the light source decreases due to dimming control. That is, for pixels where the luminance of the light source has decreased due to dimming control, color correction is performed to increase the luminance of the color of the pixel. This achieves local dimming.

[0058] On the other hand, the inverse color correction circuit 40 performs inverse color correction according to the luminance of the light source of the backlight 120, as described in FIG. 8 . For example, the inverse color correction circuit 40 performs inverse color correction such that the color level of each pixel of the inverse color-corrected image data IMR decreases as the luminance of the light source decreases due to dimming control. That is, for pixels whose color luminance has increased due to color correction, inverse color correction is performed to decrease the color luminance, thereby generating inverse color-corrected image data IMR that restores the original image data IM. This allows the blinding error detection circuit 90 to detect blinding errors based on the inverse color-corrected image data IMR corresponding to the original image data IM. Therefore, blinding errors can be properly detected even when dimming control of the backlight 120 or color correction based on the dimming control is performed.

[0059] 3, the circuit device 10 includes a luminance analysis circuit 52 that performs luminance analysis of the image data IM, and a dimming amount calculation circuit 54 that calculates the dimming amount of each light source based on the results of the luminance analysis. The color correction circuit 30 performs color correction based on the dimming amount calculation result of the dimming amount calculation circuit 54, and the inverse color correction circuit 40 performs inverse color correction based on the dimming amount calculation result of the dimming amount calculation circuit 54. In this manner, the dimming amount of each of the multiple light sources of the backlight 120 is calculated based on the results of the luminance analysis of the image data IM, and dimming control of the backlight 120 is performed based on the calculated dimming amount. By performing color correction based on the dimming amount calculated in this manner, color correction according to the dimming control of the backlight 120 can be performed, and color-corrected display image data IMD can be output to the display device 100. Furthermore, by performing inverse color correction on the color-corrected display image data IMD according to the calculated dimming amount, the inverse color-corrected image data IMR corresponding to the image data IM before color correction can be input to the blinding error detection circuit 90, thereby enabling the blinding error to be properly detected.

[0060] Furthermore, dimming amount calculation circuit 54 calculates the dimming amount of each light source based on the diffusion coefficient information of backlight 120 and the results of luminance analysis. For example, when a diffuser 115 is provided for backlight 120 as shown in Fig. 14 and the light from the light source of backlight 120 is diffused, the dimming amount of each light source is calculated based on the diffusion coefficient information of the light from the light source by diffuser 115 and the results of luminance analysis of image data IM. In this way, when the light from the light source of backlight 120 is diffused to reduce luminance unevenness, dimming control and color correction that reflect the diffusion of the light from the light source become possible.

[0061] In this embodiment, the blinding error detection circuit 90 detects a blinding error by calculating a judgment index value for the blinding error and comparing the judgment index value with a threshold value. Specifically, the blinding error detection circuit 90 calculates a judgment index value according to the display image data IMD and the result of the dimming control, and compares the judgment index value with a threshold value to detect a blinding error. For example, in FIG. 3 , inverse color-corrected image data IMR generated based on the display image data IMD and the result of the dimming control is input to the blinding error detection circuit 90. The blinding error detection circuit 90 then calculates a judgment index value for the blinding error based on the inverse color-corrected image data IMR and compares it with a threshold value to detect a blinding error. Alternatively, as described below, the blinding error detection circuit 90 calculates a judgment index value based on the inverse distortion-corrected image data generated based on the display image data IMD and the result of the dimming control, and compares it with a threshold value to detect a blinding error. In this way, by using the judgment index value calculated based on the display image data IMD and the result of the dimming control, a blinding error can be detected through simple processing. If a blinding error is detected, the supply of the display image data IMD is stopped, the backlight 120 is turned off, or the display image data IMD is made transparent and displayed in black, thereby preventing the occurrence of a situation in which the visibility of the background is reduced due to a blinding error.

[0062] Here, the threshold value is stored, for example, in a memory circuit (not shown) of the circuit device 10. As described above, the judgment index value may be, for example, the integrated value or average value of pixel brightness in the blinding error judgment region, or the number or ratio of high-brightness pixels in the judgment region. In this case, the blinding error detection circuit 90 judges that a blinding error has been detected when the judgment index value exceeds the threshold value. Alternatively, the judgment index value may be, for example, the number or ratio of black pixels in the judgment region. In this case, the blinding error detection circuit 90 judges that a blinding error has been detected when the judgment index value is smaller than the threshold value. In this way, it is possible to realize an appropriate blinding error detection process using the judgment index value.

[0063] 3. Second configuration example 9 shows a second detailed configuration example of the circuit device 10 of this embodiment. In Fig. 9, the circuit device 10 includes a distortion correction circuit 20 that performs distortion correction on input image data IMI and outputs image data IM, and a blinding error detection circuit 90 performs processing for detecting blinding errors in each of a plurality of regions obtained by dividing the image of the input image data IMI, based on an area determination signal AJ output by the distortion correction circuit 20.

[0064] That is, the circuit device 10 of this embodiment includes a distortion correction circuit 20 that performs distortion correction on input image data IMI and outputs image data IM. This allows color correction and dimming control to be performed based on the image data IM after distortion correction by the distortion correction circuit 20. Therefore, even in a HUD display device 100 that requires distortion correction for image display, appropriate color correction and dimming control can be achieved. Specifically, for example, as shown in FIG. 14 , even if the transparent screen 160 on which the display image of the display device 100 is projected is curved, distortion correction according to this curvature can be performed, allowing an undistorted image to be displayed to the user and appropriate color correction and dimming control to be achieved. In this embodiment, the blinding error detection circuit 90 performs blinding error detection processing based on the area determination signal AJ output from the distortion correction circuit 20.

[0065] 10 is a diagram showing the relationship between the input image of the distortion correction circuit 20, the output image of the distortion correction circuit 20, and the display image of the HUD. The input image of the distortion correction circuit 20 corresponds to input image data IMI, and the output image of the distortion correction circuit 20 corresponds to image data IM. The HUD displays an image of display image data IMD, which is obtained by performing color correction on the image data IM.

[0066] In Fig. 10, each of the first divided areas of the first divided area group into which the input image is divided is indicated by ARA. Specifically, the divided areas are set by a plurality of straight lines in the horizontal scanning direction and a plurality of straight lines in the vertical direction. Note that Fig. 10 shows an example in which the image is divided into 6 x 4, but the number of divisions is not limited to this. Also, Fig. 10 shows an example in which the image is divided equally in the horizontal and vertical directions, but it may be divided unevenly.

[0067] The input image is corrected for distortion in the opposite direction to that caused by HUD projection, and then projected onto the HUD, resulting in a display without distortion similar to the input image. In other words, setting a first group of divided areas in the input image is equivalent to setting a group of divided areas in the HUD display. This group of divided areas in the HUD display is referred to as a third group of divided areas, and each third group of divided areas is indicated by ARH. The shape of the third group of divided areas ARH is the same as the first group of divided areas ARA corresponding to that third group of divided areas ARH. Furthermore, the coordinates (u, v) on the input image and the coordinates (x, y) on the output image are associated by coordinate transformation for distortion correction. This coordinate association divides the output image into a second group of divided areas corresponding to the first group of divided areas. Each second group of divided areas in the second group of divided areas is indicated by ARB. The second group of divided areas ARB has a distorted shape due to distortion correction.

[0068] For example, in this embodiment, a blinding error, in which the visibility of an object such as a person or bicycle is reduced due to the HUD image in FIG. 2, can be detected. In this case, an object such as a bicycle is detected, for example, by a camera (not shown), and the region of the object is used as a judgment region to perform blinding error detection processing. Taking FIG. 10 as an example, a blinding error can be detected using the third divided region ARH in the HUD display image, in which an object such as a person or bicycle is displayed, as the judgment region. Specifically, a different threshold value is set for the region in which an object such as a person or bicycle is detected and for the other region, and a blinding error is detected by comparing the set threshold value with the judgment index value for a blinding error. As an example, a small threshold value is set for the region in which an object is detected and a large threshold value is set for the other region, and a blinding error is determined to have occurred when the judgment index value exceeds the set threshold value. In this way, blinding errors are detected with smaller judgment index values ​​in areas where objects such as people and bicycles are located, which effectively prevents the objects from being obscured by the HUD image.

[0069] 9, the blinding error detection circuit 90 detects blinding errors based on an inverse color-corrected image obtained by performing inverse color correction after color correction on the output image of the distortion correction circuit 20. Therefore, in FIG. 10, it is necessary to detect blinding errors using the second divided area ARB, which is an area with a distorted shape, as the judgment area. This poses a problem in that it is difficult to determine which area of ​​the inverse color-corrected image should be used as the judgment area for detecting blinding errors.

[0070] Therefore, in this embodiment, the distortion correction circuit 20 outputs an area determination signal AJ, and the blinding error detection circuit 90 performs processing to detect blinding errors in each of the multiple areas into which the image of the input image data IMI is divided, based on the area determination signal AJ output by the distortion correction circuit 20. In this manner, the blinding error detection circuit 90 can determine a determination area based on the area determination signal AJ from the distortion correction circuit 20 in an inverse color corrected image obtained by performing color correction and inverse color correction on the output image of the distortion correction circuit 20, and detect blinding errors in the determination area.

[0071] For example, the input image data IMI corresponds to the input image shown in FIG. 10, and each of the multiple regions obtained by dividing the input image corresponds to the first divided region ARA shown in FIG. 10. The distortion correction circuit 20 performs distortion correction based on information relating to the correspondence between coordinates (u, v) in the input image and coordinates (x, y) in the output image. Therefore, the distortion correction circuit 20 can output a region determination signal AJ for determining which of the first divided regions ARA in the input image corresponds to the second divided region ARB in the output image. As described above, the first divided region ARA in the input image corresponds to the third divided region ARH in the HUD display image. Therefore, the blinding error detection circuit 90 determines the third divided region ARH in which the object is located in the inverse color-corrected image based on the region determination signal AJ from the distortion correction circuit 20, and can detect a blinding error using that region as the determination region. Therefore, the blinding error detection circuit 90 can determine the determination region based on the region determination signal AJ in the inverse color-corrected image corresponding to the output image of the distortion correction circuit 20, and can detect a blinding error in the determination region.

[0072] 4.Third configuration example FIG. 11 shows a detailed third example configuration of the circuit device 10 of this embodiment. In this third example configuration, an inverse distortion correction circuit 70 and line buffers 22 and 72 are provided in addition to the configuration of FIG. 3. For example, in FIG. 3, the blinding error detection circuit 90 detects blinding errors based on the inverse color-corrected image data IMR. In contrast, in FIG. 11, the blinding error detection circuit 90 detects blinding errors based on inverse-distortion-corrected image data IMRR, which is obtained by inversely correcting the inverse color-corrected image data IMR. In this way, the blinding error detection circuit 90 can perform blinding error detection processing based on the inverse-distortion-corrected image data IMRR corresponding to the original input image data IMI, and can detect blinding errors by setting a blinding error judgment region through simple processing.

[0073] For example, the distortion correction circuit 20 performs a mapping process, which maps an image to match the surface shape of the projection target, as the distortion correction process. This mapping process transforms the image so that the image projected onto the projection target does not appear distorted when viewed by the user. Meanwhile, the inverse distortion correction circuit 70 performs an inverse mapping process, which corresponds to the inverse transformation of the mapping process performed by the distortion correction circuit 20, as the inverse distortion correction process. This inverse mapping process transforms an image transformed to match the projection target back to the original image. The projection target is the object onto which the display image generated by the circuit device 10 is projected or displayed. In the case of an in-vehicle head-up display, the projection target is the automobile's windshield, etc. The mapping process is a process of coordinate transformation of pixel positions of the image based on mapping parameters, also known as map data. The mapping process can include pixel value interpolation as a process associated with the coordinate transformation. Mapping processes include forward mapping and reverse mapping. The mapping parameters are parameters that indicate coordinate transformation corresponding to the shape of the reflection surface of the projection target, and are table data, etc., that associate pixel positions in the image before the mapping process with those in the image after the mapping process. The mapping process performed by the distortion correction circuit 20 and the inverse mapping process performed by the inverse distortion correction circuit 70 can be realized using these mapping parameters. A line buffer 22 is provided upstream of the distortion correction circuit 20, and the distortion correction circuit 20 performs distortion correction using input image data IMI that is temporarily stored and accumulated in the line buffer 22. A line buffer 72 is also provided upstream of the inverse distortion correction circuit 70, and the inverse distortion correction circuit 70 performs inverse distortion correction using inverse color-corrected image data IMR that is temporarily stored and accumulated in the line buffer 72. The line buffers 22 and 72 temporarily store image data for, for example, a predetermined number of scanning lines.

[0074] As described above, the circuit device 10 of FIG. 11 includes a distortion correction circuit 20 that performs distortion correction on input image data IMI and outputs image data IM, and a color correction circuit 30 that performs color correction on the image data IM based on the results of dimming control and outputs display image data IMD. The circuit device 10 also includes an inverse color correction circuit 40 that performs inverse color correction on the display image data IMD based on the results of dimming control and outputs inverse-color-corrected image data IMR, and an inverse distortion correction circuit 70 that performs inverse distortion correction on the inverse-color-corrected image data IMR and outputs inverse-distortion-corrected image data IMRR. The blinding error detection circuit 90 performs blinding error detection processing based on the inverse-distortion-corrected image data IMRR. This configuration allows the blinding error determination area to be set in the coordinate system of the original input image data IMI, making it easier to set the determination area.

[0075] That is, the inverse-distortion-corrected image data IMRR is image data that has been subjected to inverse distortion correction by the inverse-distortion correction circuit 70 after the distortion correction circuit 20 has performed distortion correction on the original input image data IMI. Therefore, the inverse-distortion-corrected image, which is the image of the inverse-distortion-corrected image data IMRR, is an image without distortion, similar to the input image of the input image data IMI in Fig. 10. Therefore, unlike the case of Fig. 9, the blinding error detection circuit 90 can specify a determination area where an object such as a person or bicycle is located by simple processing and detect a blinding error in that determination area.

[0076] 5. Fourth Configuration Example FIG. 12 shows a detailed fourth example configuration of the circuit device 10 of this embodiment. In this fourth example configuration, a luminance calculation circuit 44 is provided instead of the inverse color correction circuit 40 of FIG. 3. The blinding error detection circuit 90 performs blinding error detection processing based on the luminance information BR from the luminance calculation circuit 44. For example, the luminance calculation circuit 44 converts the luminance value of each pixel of the color-corrected display image data IMD into the luminance value before the color correction based on the result of dimming control, and outputs the converted luminance information BR. In this way, blinding error detection processing based on the display image data IMD and the result of dimming control can be achieved by the low-load process of calculating the luminance information BR.

[0077] For example, in FIG. 3, inverse color correction is performed on color-corrected display image data IMD to obtain inverse color-corrected image data IMR corresponding to image data restored from the original image data IM, and blinding errors are detected based on this inverse color-corrected image data IMR. However, because blinding errors can be determined based on luminance, it is not necessary to restore the original image data IM. Therefore, in FIG. 12, a luminance calculation circuit 44 calculates luminance information BR corresponding to the original image data IM based on information on the dimming amount, which is the result of dimming control by the dimming control circuit 50, and the display image data IMD. For example, the luminance calculation circuit 44 calculates the luminance of each pixel in the display image data IMD and converts the calculated pixel luminance using a method similar to that shown in FIG. 7 to generate the luminance information BR. For example, based on the luminance value of the backlight 120, which is information on the dimming amount, a conversion process is performed so that the luminance of the pixel decreases as the luminance value of the backlight 120 decreases, thereby generating the luminance information BR. The luminance information BR is, for example, information in which a luminance value is set for each of multiple pixels constituting an image. The blinding error detection circuit 90 then determines the aforementioned blinding error determination index value based on this luminance information BR, and detects blinding errors by comparing the determined determination index value with a threshold. For example, the blinding error detection circuit 90 performs an integration process on the luminance of multiple pixels in the determination area based on the luminance information BR, and determines the integrated value or average value as the determination index value. Alternatively, the blinding error detection circuit 90 determines the number or ratio of high-luminance pixels or black pixels in the determination area as the determination index value based on the luminance information BR. In this way, it becomes possible to determine the luminance information BR with a process that is less burdensome than color inverse correction, and to detect blinding errors based on this luminance information BR.

[0078] 6. Fifth Configuration Example FIG. 13 shows a detailed fifth example of the circuit device 10 of this embodiment. In this fifth example, each circuit of the circuit device 10 sends a region determination signal AJ along with image data to a downstream circuit. For example, the distortion correction circuit 20 outputs the region determination signal AJ along with image data IM to the color correction circuit 30, and the color correction circuit 30 outputs the region determination signal AJ along with display image data IMD to the inverse color correction circuit 40. The inverse color correction circuit 40 also outputs the region determination signal AJ along with inverse color-corrected image data IMR to the blinding error detection circuit 90. For example, the region determination signal AJ is output to the downstream circuit as index data for region determination associated with each pixel data of the image data. That is, index data specifying the region in which each pixel is located is output in association with each pixel data. In this manner, the color correction circuit 30, the inverse color correction circuit 40, and the blinding error detection circuit 90 can determine which region each pixel data of the image data belongs to based on the region determination signal AJ. Then, similar to the method described in FIGS. 9 and 10, the blinding error detection circuit 90 can identify a judgment area where, for example, a person, a bicycle, etc. is located based on this area judgment signal AJ and detect a blinding error in that judgment area.

[0079] Although the first to fifth configuration examples of this embodiment have been described above, this embodiment is not limited to these, and various modifications are possible, such as a configuration that combines at least two of the first to fifth configuration examples.

[0080] 7. Head-up display 14 shows an example of the configuration of a head-up display 190 of this embodiment. The head-up display 190 of this embodiment includes the circuit device 10 of this embodiment and a display device 100. The display device 100 projects a display image based on display image data IMD from the circuit device 10. For example, the display device 100 includes a display panel 110 and a backlight 120. The display device 100 may also include a display driver 140 that drives the display panel 110, and a diffuser 115 that is provided between the display panel 110 and the backlight 120. The display device 100 may also include a projection optical system such as a mirror 150 that reflects projection light of the projected image.

[0081] The display driver 140 drives the data lines and scan lines of the display panel 110 based on the display image data IMD from the circuit device 10 to display an image. Light emitted by the backlight 120 passes through the diffuser 115 and the display panel 110 and is reflected by the mirror 150 toward the transparent screen 160. The transparent screen 160 is, for example, an automobile windshield. The reflective surface of the transparent screen 160 is, for example, concave, so that the projected image appears as a virtual image to the user. In other words, the projected image appears to be formed farther away from the user than the transparent screen 160. This allows the projected image to be displayed within a background. Note that the head-up display 190 is not limited to the configuration shown in FIG. 14 and can be modified in various ways. For example, a display panel other than a liquid crystal display panel can be used as the display panel 110, and various modifications can be made to the arrangement of the diffuser 115 and the projection optical system.

[0082] As described above, the circuit device of this embodiment is a circuit device used in a display device of a head-up display that projects an image using display image data and a light source. The circuit device includes a dimming control circuit that controls dimming of the light source based on the image data, a color correction circuit that outputs display image data by performing color correction on the image data in accordance with the result of the dimming control, and a blinding error detection circuit that detects a blinding error in the head-up display in accordance with the display image data and the result of the dimming control.

[0083] This makes it possible to detect blinding errors that reflect the results of dimming control in the dimming control circuit. Therefore, compared to a method of detecting blinding errors using only display image data, it is possible to properly detect blinding errors even when dimming control is performed.

[0084] Furthermore, this embodiment includes an inverse color correction circuit that performs inverse color correction on the display image data based on the result of the dimming control, and outputs image data after the inverse color correction, and the blinding error detection circuit may perform a blinding error detection process based on the image data after the inverse color correction.

[0085] In this way, the image data after inverse color correction becomes image data based on the display image data and the results of dimming control, and by detecting a blinding error based on such image data after inverse color correction, it becomes possible to realize a blinding error detection process according to the display image data and the results of dimming control.

[0086] Furthermore, this embodiment may include a distortion correction circuit that performs distortion correction on input image data and outputs the image data, and the blinding error detection circuit may perform a process of detecting blinding errors in each of a plurality of regions into which the image of the input image data is divided, based on the region determination signal output by the distortion correction circuit.

[0087] In this way, the determination area can be determined based on the area determination signal from the distortion correction circuit, and a blinding error in the determination area can be detected.

[0088] In addition, this embodiment may include a distortion correction circuit that performs distortion correction on input image data and outputs image data, an inverse color correction circuit that performs inverse color correction on display image data based on the result of light adjustment control and outputs inverse-color-corrected image data, and an inverse distortion correction circuit that performs inverse distortion correction on the inverse-color-corrected image data and outputs inverse-distortion-corrected image data.The blinding error detection circuit may perform blinding error detection processing based on the inverse-distortion-corrected image data.

[0089] In this way, it becomes possible to perform the blinding error detection process based on the image data after inverse distortion correction corresponding to the input image data, and it becomes possible to set the blinding error judgment area by simple processing and detect the blinding error.

[0090] In this embodiment, the color correction circuit may perform color correction on the image data according to the luminance of the light source of the display device, and the inverse color correction circuit may perform inverse color correction on the display image data according to the luminance of the light source.

[0091] In this way, blinding errors can be detected properly even when light adjustment control or color correction based on light adjustment control is performed.

[0092] In this embodiment, the display device may include a display panel and a backlight having a plurality of light sources, each of which may be provided corresponding to a plurality of areas of the display panel. The color correction circuit may perform color correction on the image data according to the luminance of each light source, and the inverse color correction circuit may perform inverse color correction on the display image data according to the luminance of each light source.

[0093] In this way, blinding errors can be detected properly even when backlight dimming control or color correction based on backlight dimming control is performed.

[0094] In addition, this embodiment may include a luminance calculation circuit that converts the luminance value of each pixel of the display image data that has been color corrected back to the luminance value before the color correction based on the result of the dimming control, and outputs the converted luminance information.The blinding error detection circuit may perform a blinding error detection process based on the luminance information.

[0095] In this way, it is possible to realize the process of detecting blinding errors according to the display image data and the results of dimming control by a process that involves only a low load of calculating brightness information.

[0096] In this embodiment, the dimming control circuit may include a luminance analysis circuit that performs luminance analysis of image data, and a dimming amount calculation circuit that calculates the dimming amount of the light source based on the results of the luminance analysis.

[0097] In this way, by using the amount of dimming calculated based on the result of luminance analysis of image data, it becomes possible to realize a blinding error detection process according to the display image data and the result of dimming control.

[0098] In addition, in this embodiment, the blinding error detection circuit may perform blinding error detection processing by calculating a blinding error judgment index value according to the display image data and the result of dimming control, and comparing the judgment index value with a threshold value.

[0099] In this way, by using the judgment index value calculated according to the display image data and the result of the dimming control, it becomes possible to detect a blinding error with simple processing.

[0100] The head-up display of this embodiment includes the circuit device described above and a display device that projects a display image based on display image data from the circuit device.

[0101] Although the present embodiment has been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and advantages of the present disclosure. Therefore, all such modifications are intended to be included within 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 or equivalent meaning may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of the present embodiment and modifications are also included within the scope of the present disclosure. Furthermore, the configurations and operations of the circuit device, display device, head-up display, etc. are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0102] 5...display area, 6...display object, 10...circuit device, 20...distortion correction circuit, 22...line buffer, 24...distortion correction circuit, 30...color correction circuit, 32...line buffer, 40...inverse color correction circuit, 50...dimming control circuit, 52...luminance analysis circuit, 54...dimming amount calculation circuit, 56...illuminance sensor, 60...light source control circuit, 70...inverse distortion correction circuit, 72...line buffer, 90...blinding error detection circuit, comparison circuit, 82...line buffer, 100...display device , 110...display panel, 115...diffuser, 120...backlight, 140...display driver, 150...mirror, 160...transparent screen, 190...head-up display, 200...processing device, AR, AR1 to AR9...area, ERR...error detection signal, IM...image data, IMD...display image data, IMI...input image data, IMR...image data after inverse color correction, IMRR...image data after inverse distortion correction, LS...light source, AJ...area determination signal, BR...luminance information

Claims

1. A circuit device used in a display device of a head-up display that projects an image using display image data and a light source, a light control circuit that controls the light source based on image data; a color correction circuit that performs color correction on the image data according to a result of the light adjustment control, and outputs the display image data; a blinding error detection circuit that performs a process of detecting a blinding error of the head-up display in accordance with the display image data and a result of the light adjustment control; an inverse color correction circuit that performs inverse color correction of the color correction on the display image data based on a result of the light adjustment control, and outputs inverse color corrected image data; Including, The blinding error detection circuit a circuit device that performs a process for detecting the blinding error based on the image data after the inverse color correction;

2. 2. The circuit device according to claim 1, a distortion correction circuit that performs distortion correction on input image data and outputs the image data; The blinding error detection circuit a circuit device that performs a process of detecting the blinding error in each of a plurality of regions into which the image of the input image data is divided, based on the region determination signal output by the distortion correction circuit;

3. A circuit device used in a display device of a head-up display that projects an image using display image data and a light source, a light control circuit that controls the light source based on image data; a color correction circuit that performs color correction on the image data according to a result of the light adjustment control, and outputs the display image data; a blinding error detection circuit that performs a process of detecting a blinding error of the head-up display in accordance with the display image data and a result of the light adjustment control; a distortion correction circuit that performs distortion correction on input image data and outputs the image data; an inverse color correction circuit that performs inverse color correction of the color correction on the display image data based on a result of the light adjustment control, and outputs inverse color corrected image data; an inverse distortion correction circuit that performs inverse distortion correction on the inverse color corrected image data, thereby outputting inverse distortion corrected image data; Including, The blinding error detection circuit a circuit device that performs a process for detecting the blinding error based on the image data after the inverse distortion correction;

4. 4. The circuit device according to claim 1, The color correction circuit performing the color correction on the image data according to the luminance of the light source of the display device; The inverse color correction circuit A circuit device that performs the reverse color correction according to the luminance of the light source on the display image data.

5. 4. The circuit device according to claim 1, The display device includes a display panel and a backlight having a plurality of light sources; a light source of each of the plurality of light sources is provided corresponding to each of the plurality of areas of the display panel; The color correction circuit performing the color correction on the image data according to the luminance of each of the light sources; The inverse color correction circuit A circuit device that performs the reverse color correction according to the luminance of each of the light sources on the display image data.

6. 2. The circuit device according to claim 1, a luminance calculation circuit that converts the luminance value of each pixel of the display image data that has been color corrected into a luminance value before the color correction based on a result of the light adjustment control, and outputs the converted luminance value as luminance information; The blinding error detection circuit a circuit device that performs a process for detecting the blinding error based on the luminance information;

7. 7. The circuit arrangement according to claim 1, The dimming control circuit includes: a luminance analysis circuit for performing luminance analysis on the image data; a dimming amount calculation circuit that calculates a dimming amount of the light source based on the result of the luminance analysis; A circuit device comprising:

8. 8. The circuit arrangement according to claim 1, The blinding error detection circuit a circuit device that performs a process of detecting the blinding error by calculating a judgment index value for the blinding error according to the display image data and a result of the dimming control, and comparing the judgment index value with a threshold value.

9. A circuit arrangement according to any one of claims 1 to 8; the display device that projects a display image based on the display image data from the circuit device; A head-up display comprising:

Images