Circuit arrangement and head-up display

Abstract

The present application provides a circuit device and a head-up display. The circuit device used in a display device of a head-up display using image data and a light source for image projection includes: a dimming control circuit that performs dimming control of the light source in accordance with the image data; a color correction circuit that performs color correction of the image data corresponding to a result of the dimming control, thereby outputting display image data; and a blur error detection circuit that performs detection processing of a blur error of the head-up display corresponding to the display image data and the result of the dimming control.

Description

Technical Field

[0001] This invention relates to circuit devices and head-up displays, etc. Background Technology

[0002] Patent Document 1 discloses a circuit device for a head-up display. In this circuit device, a glare error is detected when a glare index value calculated based on the displayed image data of the head-up display exceeds a threshold. On the other hand, in display devices, image data is sometimes color-corrected to display the color-corrected image data. For example, Patent Document 2 discloses a display device for vehicles that corrects image data to a tone that eliminates the tone change when the hue of the backlight changes.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-101784

[0004] Patent Document 2: Japanese Patent Application Publication No. 2001-117071

[0005] In Patent Document 1, glare error detection, or blur error detection, is performed on the display image data output to a head-up display. However, when color correction of the display image data is performed based on the dimming control of the light source, it may be impossible to properly detect the error if the blur error is detected based on the color-corrected display image data. Summary of the Invention

[0006] One aspect of this disclosure relates to a circuit device used in a head-up display (HUD) that projects an image using display image data and a light source. The circuit device includes: a dimming control circuit that dims the light source based on the image data; a color correction circuit that performs color correction on the image data corresponding to the result of the dimming control, thereby outputting the display image data; and a blur error detection circuit that performs blur error detection processing on the HUD corresponding to the display image data and the result of the dimming control.

[0007] Furthermore, another aspect of this disclosure relates to a head-up display, wherein the head-up display includes: the circuitry described above; and the display device that projects the display image based on the display image data from the circuitry. Attached Figure Description

[0008] Figure 1 This is an example of the structure of the circuit device in this embodiment.

[0009] Figure 2 This is an example of a head-up display.

[0010] Figure 3 This is a detailed first structural example of the circuit device in this embodiment.

[0011] Figure 4 This is an example of the structure of a backlight and a display panel.

[0012] Figure 5 This is an explanatory diagram of the light source and display area.

[0013] Figure 6 This is a flowchart illustrating the brightness calculation process for each pixel.

[0014] Figure 7 This is an explanatory diagram for color correction.

[0015] Figure 8 This is an illustration of inverse color correction.

[0016] Figure 9 This is a detailed second structural example of the circuit device in this embodiment.

[0017] Figure 10 This is an explanatory diagram of the input image, output image, and HUD display image of the distortion correction circuit.

[0018] Figure 11 This is a detailed third structural example of the circuit device in this embodiment.

[0019] Figure 12 This is a detailed fourth structural example of the circuit device in this embodiment.

[0020] Figure 13 This is a detailed fifth structural example of the circuit device in this embodiment.

[0021] Figure 14 This is a structural example of the head-up display in this embodiment.

[0022] Label Explanation

[0023] 5: Display area; 6: Display object; 10: Circuit device; 20: Distortion correction circuit; 22: Horizontal buffer; 30: Color correction circuit; 40: Inverse color correction circuit; 50: Dimming control circuit; 52: Brightness analysis circuit; 54: Dimming amount calculation circuit; 60: Light source control circuit; 70: Inverse distortion correction circuit; 72: Horizontal buffer; 90: Blur error detection circuit; 100: Display device; 110: Display panel; 115: Diffuser plate; 120: Backlight; 140: Display driver; 150: Reflector; 160: Transparent screen; 190: Head-up display; 200: Processing device; AR, AR1~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: Brightness information. Detailed Implementation

[0024] The preferred embodiments of this disclosure are described in detail below. Furthermore, the embodiments described below do not unduly limit the content of the technical solution described in this invention, and the structures described in these embodiments are not necessarily all necessary components.

[0025] 1. Circuit device

[0026] Figure 1 An example of the structure of the circuit device 10 of this embodiment is shown. The circuit device 10 includes a color correction circuit 30, a dimming control circuit 50, and a blur error detection circuit 90.

[0027] The circuit device 10 is, for example, an integrated circuit device on a semiconductor substrate on which multiple circuit elements are integrated. The display device 100 displays an image based on the display image data IMD from the circuit device 10. Specifically, the display device 100 is a head-up display device 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 view. The display device 100 is, for example, composed of a display panel, a display driver, etc. In addition, the display device 100 may include a light source device such as a backlight. Furthermore, the circuit device 10 of this embodiment is a circuit device used in such a head-up display device.

[0028] 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. Specifically, the color correction circuit 30 performs color correction on the image data IM and outputs the color-corrected image data IM as the display image data IMD to the display device 100. In particular, the color correction circuit 30 outputs the display image data IMD by performing color correction on the image data IM corresponding to the result of dimming control. Color correction is, for example, color adjustment processing of the image data IM, which is a correction process that adjusts the color level. Color correction can also be referred to as brightness correction or grayscale correction of the image data IM.

[0029] The dimming control circuit 50 performs dimming control of the light source based on image data IM. Dimming control is the control of adjusting the amount of light from light source devices such as backlights. Dimming control can be local dimming control, which controls the brightness of light source devices such as backlights in each of multiple areas, or global dimming control, which controls the overall brightness of the displayed screen.

[0030] Thus, when displaying the display image data IMD on the display device 100, under dimming control by the dimming control circuit 50, the color correction circuit 30 performs color correction on the image data IMD corresponding to the dimming amount in the dimming control. Furthermore, in the dimming control, to reduce the power consumption of the light source device and make black pixels appear darker, the light intensity of the light source device is reduced. In this case, the color correction circuit 30 performs color correction to increase the brightness of the pixels corresponding to the light source and reduce the light intensity of the light source in the display screen of the display device 100. For example, the color correction circuit 30 performs color correction on each pixel value of the image data IMD so that the image displayed on the display device 100 based on the display image data IMD has the same brightness and hue as the image of the image data IMD, and outputs the color-corrected image data IMD to the display device 100. Additionally, the color correction circuit 30 can also perform color correction for adjusting the hue, etc., of the display image on the display device 100.

[0031] The blur error detection circuit 90 performs blur error detection processing on the head-up display. For example, the blur error detection circuit 90 performs blur error detection processing corresponding to the display image data IMD and the results of dimming control.

[0032] For example, Figure 2An example of a head-up display is shown. Hereinafter, the head-up display will be appropriately referred to as a HUD. A HUD includes a display panel, a backlight, a reflector, and other projection optical systems. Light emitted from the backlight passes through the display panel (such as a liquid crystal display panel) and is reflected towards the screen by the reflector. The reflected light then enters the user's eyes. As a result, a virtual image 6 corresponding to the object displayed on the display panel is projected into the user's field of vision. This virtual image 6 overlaps with the background of the HUD display, i.e., the actual space. Areas within the HUD display area 5 where the virtual image 6 is not displayed are opaque in the display panel; therefore, these are transparent areas where nothing is displayed, allowing the background to be directly seen.

[0033] To allow users to see the background through the display area 5, the display object 6 typically occupies a relatively low proportion within the display area 5. However, if a large proportion of the display object 6 obscures the background in the HUD's display area 5, the user cannot see the background in the area where the display object 6 is displayed. That is, the visibility of the background overlapping with the display object 6 may decrease due to the HUD's display object 6 obscuring the background. Alternatively, when the HUD display becomes too bright relative to the background, the visibility of the background will also decrease. For example, in the pixel value range of 0 to 255, suppose a pixel with a pixel value of 0 can see through the background. In this case, as the pixel value increases from 0, it becomes increasingly difficult to see the background through that pixel. When the proportion of such background-obscuring pixels increases to a certain level, as described above, the visibility of the background decreases. In this embodiment, the display error that causes reduced background visibility due to the obstruction of the display object 6 or the HUD display becoming too bright is called a blurring error. A blurring error can also be called an occlusion error or a glare error.

[0034] The fuzzy error detection circuit 90 performs such fuzzy error detection. Then, if a fuzzy error is detected, error detection information is output. For example, in Figure 1 In this circuit, the fuzzy error detection circuit 90 outputs an error detection signal ERR as error detection information. Alternatively, the fuzzy error detection circuit 90 can also output fuzzy error detection data as error detection information. This error detection data is, for example, written to a register (not shown) accessible by an external processing device.

[0035] In the prior art of Patent Document 1 mentioned above, only the display image data IMD output to the display device 100 is examined to check the brightness of a specific area of ​​the display panel and the ratio of a specific pixel, thereby detecting blur errors.

[0036] However, in methods that detect blur errors by only verifying the displayed image data (IMD), there is a problem that the brightness of the image projected from the HUD onto the windshield of a car cannot be correctly analyzed when dimming control of the HUD and color correction of the displayed image corresponding to the dimming control are performed. In other words, while dimming control and color correction should be considered for blur error detection, methods that only verify the displayed image data (IMD) cannot adequately detect blur errors.

[0037] Therefore, in this embodiment, the blur error detection circuit 90 performs blur error detection processing corresponding to the result of the dimming control in the display image data IMD and the dimming control circuit 50. That is, in this embodiment, the dimming control circuit 50 performs dimming control of light sources such as backlights based on the image data IM. Then, the color correction circuit 30 performs color correction on the image data IM corresponding to the result of the dimming control and outputs the display image data IMD. That is, in this embodiment, when dimming control is performed in the display device 100, the displayed color remains the same even if the dimming amount changes, so the color correction circuit 30 performs color adjustment, i.e., color correction, on the image data IM reflecting the adjustment amount of the dimming control. Then, the blur error detection circuit 90 performs blur error detection processing corresponding to the result of the dimming control and the display image data IMD. In this way, blur errors reflecting the result of the dimming control in the dimming control circuit 50 can be detected. For example, by reflecting the result of the dimming control, blur errors can be detected using image data with a brightness state corresponding to the original image data IM, without using the brightness state of the display image data IMD after dimming control. Therefore, compared to methods that only use the displayed image data (IMD) to detect blur errors, blur errors can be properly detected even when dimming control is in place.

[0038] Here, various processing methods can be envisioned for detecting blur errors. For example, based on the image data, the brightness of the color in the region where the blur error is detected can be calculated, or the cumulative or average value of the brightness in the region can be calculated, thereby detecting the blur error. Alternatively, the blur error can be detected based on the number or ratio of pixels whose brightness exceeds a threshold. Alternatively, the blur error can be detected based on the number or ratio of pixels whose brightness is below a threshold. Furthermore, in the event of a blur error, control is performed to stop supplying display image data IMD to the display device 100, or control is performed to turn off the backlight 120. Turning off the backlight can be done by turning off the entire screen area, or by turning off the light source corresponding to the area where the error is detected. Alternatively, in the event of a blur error, processing can be performed to make the area where the error is detected or the entire screen area black. For example, the display image data IMD can be set to a transparent color. A transparent color refers to a color that, when the color displayed on the display panel is projected through the HUD, nothing is displayed in the HUD display and the background can be seen directly. Specifically, the HUD display should be transparent when the pixels of the display panel block light, so a color that appears black when displayed on the display panel is equivalent to a transparent color. For example, black data in the display image data IMD becomes transparent in the HUD display.

[0039] For example, the blur error detection circuit 90 calculates a blur error determination index value and compares the determination index value with a threshold to perform blur error detection processing. Specifically, the blur error detection circuit 90 calculates a blur error determination index value corresponding to the display image data IMD and the dimming control result, and compares the determination index value with a threshold to detect blur errors. The blur error determination index value corresponding to the display image data IMD and the dimming control result is a determination index value calculated based on image data, such as the display image data IMD and the dimming control result. The image data calculated based on the display image data IMD and the dimming control result is, for example, the inverse color-corrected image data described later, or the inverse distortion-corrected image data based on the inverse color-corrected image data. In addition, the blur error determination index value is an index value that indicates the degree to which the visibility of the background is reduced due to the image of the display image data IMD when it is displayed on the HUD. For example, there may be situations where the image of the object displayed on the HUD obscures the background, or the background is difficult to see due to the glare of the image displayed on the HUD, and the blur error determination index value indicates the degree of these situations. The criterion value for fuzziness error can also be called the criterion value for occlusion error or the criterion value for dazzle error.

[0040] The criterion for determining blur errors is, for example, the cumulative or average value of the brightness of the pixels in the region where blur errors are detected. For instance, the cumulative value can be calculated by accumulating the pixel values ​​of the pixels in the region, or the average value can be calculated by dividing the cumulative value by the number of pixels in the region. As an example, the criterion for determining blur errors, DV, can be calculated using the formula DV = C1 × Rsum + C2 × Gsum + C3 × Bsum. Here, Rsum is the cumulative value of red pixels, Gsum is the cumulative value of green pixels, Bsum is the cumulative value of blue pixels, and C1, C2, and C3 are coefficients. Coefficients C1, C2, and C3 are used to convert RGB pixel values ​​to YCrCb brightness values ​​Y, and appropriate coefficients are set according to the color space used in the image data. However, coefficients C1, C2, and C3 are not limited to these and can be any real number greater than 0. Alternatively, the criterion for determining blur errors, DV, can be calculated by accumulating the brightness value Y after calculating the brightness value Y per pixel. In this case, Y = C1 × Rpx + C2 × Gpx + C3 × Bpx, DV = Ysum. Rpx, Gpx, and Bpx are the red, green, and blue pixel values ​​of one pixel, respectively. Ysum is the cumulative value of the luminance value Y.

[0041] Alternatively, within the detection region, the number of high-brightness pixels exceeding a threshold, or the ratio of high-brightness pixels to the total number of pixels, can be calculated as a criterion for detecting blur errors. Then, if the criterion value for the number or ratio of high-brightness pixels exceeds the threshold, a blur error is detected. Alternatively, the number of black pixels or the ratio of black pixels to the total number of pixels in the detection region can be calculated as a criterion for detecting blur errors. Black pixels are pixels containing black data, but are not limited to completely black data; any data that is approximately black is acceptable. Furthermore, if the criterion value for the number or ratio of black pixels is less than the threshold, a blur error is detected. In this way, various criterions can be used as the criterion for detecting blur errors.

[0042] Furthermore, the color correction circuit 30, the dimming control circuit 50, and the fuzzy error detection circuit 90 are logic circuits. These logic circuits can be configured as separate circuits, or they can be integrated into a single circuit through automatic configuration wiring, etc. Alternatively, some or all of these logic circuits can be implemented 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 processor implements the function of each circuit by executing the program or instruction set.

[0043] 2. Example of the first structure

[0044] Figure 3 A detailed first structural example of the circuit device 10 of this embodiment is shown. Figure 3 The circuit device 10, in addition to Figure 1 In addition to its structure, the circuit device 10 also includes a distortion correction circuit 20, a light source control circuit 60, and an inverse color correction circuit 40. Furthermore, the circuit device 10 is not limited to... Figure 3 The structure of the first structural example or other structural examples described later can be modified in various ways, such as omitting some of their structural elements, adding other structural elements, or replacing some structural elements with other structural elements.

[0045] A processing device 200 is disposed externally to the circuit device 10. The processing device 200 is, for example, a SoC (System on Chip), specifically a microcomputer, CPU, or 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.

[0046] The display device 100 includes a display panel 110, a backlight 120, and light source drivers 130-1 to 130-n. Here, n is an integer of 2 or more. Furthermore, the display device 100 may 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 the display panel 110 to display a display image. The display driver may include a data driver that drives the data lines of the display panel 110, a scan driver that drives the scan lines of the display panel 110, a display controller, etc. Multiple light sources LS are provided in the backlight 120. For example, multiple light sources LS are arranged in an array.

[0047] Figure 4 This is an example of the structure of the backlight 120 and the display panel 110. Figure 4 In the diagram, 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 perpendicular to directions D1 and D2, and is the direction from which the display panel 110 is viewed from above. The backlight 120 is located on the side of the display panel 110 in direction D3, and emits illumination light in the opposite direction of direction D3, which is the direction towards the display panel 110.

[0048] Backlight 120 comprises multiple light sources LS. Figure 4The diagram illustrates an example of an 8×5 light source LS configured in a two-dimensional array. Specifically, 8 light source LSs are arranged along direction D1, and 5 light source LSs are arranged along direction D2. Furthermore, for appropriate local dimming, it is preferable to arrange 100 or more light source LSs in the backlight 120. The light source LS is, for example, an LED (Light Emitting Diode). However, the light source LS is not limited to LEDs; any light source that allows independent control of light intensity and is close to a point light source is acceptable. A light source close to a point light source is one whose light-emitting portion is sufficiently smaller than the corresponding area AR of that light source LS. Additionally, various configurations of the light source LS, such as square or hexagonal arrangements, can be considered.

[0049] The display panel 110 has a pixel array, and the area in this pixel array where the displayed image is shown is defined as the display area. The display area is divided into multiple regions AR. A light source LS is correspondingly arranged in each region AR. That is, one light source LS corresponds to one region AR. For example, when viewing the display panel 110 from above, the light source LS is arranged at the center of the region AR. However, the arrangement position of the light source LS is not limited to this. Figure 4 In this display panel 110, corresponding to 8×5 light sources LS, the display area is divided into 8×5 regions AR. Furthermore, the regions AR are used for processing in the circuit device 10, and the boundaries of the regions AR do not exist in the actual image displayed on the display panel 110. The display panel 110 is a panel that displays the image by controlling the transmittance of each pixel according to the image being displayed, through which the illumination light from the backlight 120 passes through each pixel. For example, the display panel 110 is a liquid crystal display panel.

[0050] Thus, when the display area of ​​the display panel 110 is divided into multiple regions, such that each region AR has a light source LS, the light source LS illuminating the display panel 110 has a light intensity distribution such that the light intensity decreases as one moves further away from the light source LS. Therefore, compared to the center of region AR, the light intensity is lower at the periphery. This light intensity distribution of the light source LS is called PSF. Figure 5 An example illustrating the light intensity distribution of a PSF. In Figure 5 The light intensity distribution is represented by a gradient; the whiter the light, the larger the light intensity distribution coefficient. Figure 5 In this context, the size of the PSF corresponds to 3×3 regions AR1 to AR9, with the center of the PSF positioned at the location of the light source.

[0051] like Figure 3As shown, 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 displayed image data IMD and outputs inverse color-corrected image data IMR. Inverse color correction is the opposite of the color correction performed by the color correction circuit 30, and is the inverse conversion of the conversion in color correction. For example, the inverse color correction performed by the inverse color correction circuit 40 is used to restore the color-corrected displayed image data IMD to the original image data IM. For example, in the case where color correction increases the brightness of each pixel of the displayed image data IMD due to a reduction in the amount of light source in the dimming control of the dimming control circuit 50, the inverse color correction circuit 40 performs inverse color correction to reduce the increased brightness and return it to the original brightness. Alternatively, in the case where the hue changes due to color correction, inverse color correction can also be performed to restore 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 be exactly the same as the original image data IM, as long as they are within a specified error range. Error ranges include, for example, rounding errors. Additionally, the resolution of the inverse color-corrected image data (IMR) may differ from the original image data (IM); for instance, the inverse color-corrected image data (IMR) may be low-resolution image data.

[0052] Furthermore, the circuit device 10 includes a distortion correction circuit 20. The distortion correction circuit 20 performs distortion correction on the input image data IMI and outputs image data IM. Additionally, 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).

[0053] Specifically, the distortion correction circuit 20 uses coordinate transformation between pixel coordinates in the input image data IMI and pixel coordinates in the image data IM to perform distortion correction on the input image data IMI, and outputs the result as the image data IM. Distortion correction refers to applying image distortion to an image that is the opposite of the image distortion when the image displayed on the display panel 110 is projected, and is used for image correction to achieve distortion-free or reduced-distortion HUD displays. Image distortion caused by projection includes image distortion caused by the curvature of the screen in the HUD, image distortion caused by the HUD optical system, or both. For example, the HUD prompts the user with an image by projecting an image onto a transparent screen or by displaying an image on a transparent display panel. In this case, by deforming the image accordingly to the curvature of the transparent screen or transparent display panel, the user can see an image without distortion. The distortion correction circuit 20 performs such image deformation processing as distortion correction.

[0054] 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 converts the pixel coordinates in the image data IM, which is the output image data, into their corresponding reference coordinates, and then calculates the pixel data of the image data IM based on the pixel data of the input image data IMI in these reference coordinates. Forward mapping, also known as forward warping, is a mapping process that converts the pixel coordinates in the input image data IMI into their corresponding destination coordinates, and then calculates the pixel data of the image data IM in the destination coordinates based on the pixel data of the input image data IMI in these pixel coordinates. The coordinate transformations in reverse mapping and forward mapping are defined by mapping parameters, also known as mapping data. Mapping parameters can be a table mapping coordinates on the input image to coordinates on the output image, a table representing the amount of movement between the coordinates on the input image and the coordinates on the output image, or the coefficients of a polynomial mapping coordinates on the input image to coordinates on the output image, etc.

[0055] The dimming control circuit 50 performs dimming control of the light source based on image data IM. Specifically, the dimming control circuit 50 performs dimming control of the backlight 120, which has multiple light sources, to achieve dimming control, for example, a type of dimming control known as local dimming. For example, the dimming control circuit 50 performs calculation processing to obtain dimming amount information based on the image data IM. Here, the dimming amount information is information used to specify the brightness of the light source to emit light through dimming control. The light source control circuit 60 performs control processing and instruction processing of 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. Moreover, the light source drivers 130-1 to 130-n, which are LED drivers, drive the light source LS of the backlight 120 based on the dimming amount information, thereby realizing dimming control of the backlight 120. For example, local dimming is achieved by implementing dimming control of each of the multiple areas obtained by dividing the display area of ​​the display panel 110.

[0056] Alternatively, a processing device such as an MCU can be provided between the light source control circuit 60 and the light source drivers 130-1 to 130-n to absorb communication protocol differences 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 this processing device such as the MCU.

[0057] The dimming control circuit 50 includes a brightness analysis circuit 52 and a dimming amount calculation circuit 54. The brightness analysis circuit 52 performs brightness analysis on the image data IM. The dimming amount calculation circuit 54 calculates the dimming amount for each light source based on the brightness analysis results. Specifically, based on the image data IM, the brightness analysis circuit 52 searches for pixels with maximum brightness in each of multiple regions of the display area. Then, it determines the brightness distribution of each light source in a way that displays the color with the maximum brightness found. The dimming amount calculation circuit 54 performs a calculation process based on the determined brightness distribution of the light sources and the diffusion coefficient information of the light sources, recalculating the brightness for each pixel, and calculates the dimming amount corresponding to the brightness value of the backlight 120 for each pixel. The diffusion coefficient information is, for example, described later. Figure 14 Information on the diffusion coefficient parameters of the diffuser plate 115. In addition, dimming amount information 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. The light source drivers 130-1 to 130-n drive the light sources in each of the multiple regions to emit light according to the dimming amount, thereby realizing local dimming.

[0058] On the other hand, the color correction circuit 30 performs color correction corresponding to the dimming control in 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 corresponding to the dimming control of the backlight 120 based on dimming amount information from the dimming amount calculation circuit 54. For example, if dimming control that reduces the light intensity of the light source is performed in the area corresponding to the light source, the color correction circuit 30 performs color correction that increases the pixel brightness in that area by the amount of light intensity reduction in that area, and outputs the color-corrected display image data IMD to the display device 100. As a result, the light intensity of the light source in that area can be reduced, and an image corresponding to the original image data IMD can be displayed in that area based on the color-corrected display image data IMD, enabling local dimming. As a result, it is possible to achieve low power consumption of the backlight 120 and image display that makes black pixels appear darker.

[0059] Furthermore, the inverse color correction circuit 40 performs inverse color correction on the color-corrected display image data IMD, and outputs inverse color-corrected image data IMR. For example, the inverse color correction circuit 40 performs inverse color correction based on the display image data IMD and the dimming amount information in the dimming amount calculation circuit 54, to restore the color-corrected display image data IMD to the image data IM before color correction. For example, if dimming control that reduces the light intensity of the light source is performed in the area corresponding to the light source, and color correction that increases the brightness of the pixels in that area is performed, the inverse color correction circuit 40 performs inverse color correction to reduce the brightness of the pixels in that area to restore the original brightness, and outputs inverse color-corrected image data IMR.

[0060] As described above, the circuit device 10 of this embodiment includes an inverse color correction circuit 40, which performs inverse color correction on the displayed image data IMD based on the result of dimming control, thereby outputting inverse color corrected image data IMR. Furthermore, the blur error detection circuit 90 performs blur error detection processing based on the inverse color corrected image data IMR.

[0061] Thus, blur error detection processing corresponding to the display image data IMD and the dimming control results is achieved. Specifically, the inverse color correction circuit 40 performs inverse color correction based on the display image data IMD and the dimming amount information in the dimming amount calculation circuit 54, and outputs the inverse color corrected image data IMR. Therefore, the inverse color corrected image data IMR becomes image data based on the display image data IMD and the dimming control results. By detecting blur errors based on such inverse color corrected image data IMR, blur error detection processing corresponding to the display image data IMD and the dimming control results is achieved. For example, the blur error detection circuit 90 calculates a blur error judgment index value based on the inverse color corrected image data IMR and compares this judgment index value with a threshold, thereby detecting blur errors. Furthermore, when a blur error is detected, processing is performed such as stopping the supply of display image data IMD to the display device 100, turning off the backlight 120, or making the display image data IMD in the error detection area transparent. These processes can be performed by the circuit device 10 or by a processing device 200 external to the circuit device 10. This prevents the background from becoming less visible due to blurry errors.

[0062] For example, in a method for detecting blur errors based solely on the display image data IMD output to the display device 100, it may be impossible to achieve blur error detection processing that accurately reflects the dimming control in the dimming control circuit 50 and the color correction in the color correction circuit 30. That is, when dimming control of the backlight 120 is performed by the dimming control circuit 50, color correction corresponding to this dimming control is performed by the color correction circuit 30, and the color-corrected display image data IMD is output to the display device 100. Therefore, due to the color correction corresponding to the dimming control, the color levels in the display image data IMD become different from the original color levels in the image data IMD, thus blur errors cannot be correctly detected in detection processing using only the display image data IMD. For example, in areas where the light intensity of the light source is reduced by dimming control, color correction is performed on the display image data IMD to increase the brightness of the pixels in that area. Therefore, when detecting blur errors based solely on the display image data IMD, blur errors may be incorrectly detected in that area. For example, what is not a blur error may be incorrectly detected as a blur error. Alternatively, if color correction is performed to increase the amount of light from the light source and correspondingly reduce the brightness of the pixels, the original blur error may not be detected if blur error is detected solely based on the displayed image data IMD.

[0063] Regarding this point, Figure 3 In this process, based on the result of dimming control, inverse color correction is performed on the displayed image data IMD, thereby generating inverse color-corrected image data IMR corresponding to the original image data IM. Blur errors are then detected based on this inverse color-corrected image data IMR. This allows blur errors to be detected based on the inverse color-corrected image data IMR, which restores the original image data IM, rather than on the displayed image data IMD that has undergone color correction corresponding to dimming control. Therefore, blur errors can be appropriately detected even when dimming control or color correction based on dimming control is performed. That is, when the displayed image is displayed on the display panel 110 based on the displayed image data IMD that has undergone dimming control by the dimming control circuit 50 and color correction, the user's eye can see an image corresponding to the original image data IM. Therefore, by detecting blur errors based on the inverse color-corrected image data IMR corresponding to the original image data IM, appropriate error detection can be achieved.

[0064] Furthermore, the color correction circuit 30, the inverse color correction circuit 40, the fuzzy error detection circuit 90, the distortion correction circuit 20, the dimming control circuit 50, and the light source control circuit 60 are logic circuits. These logic circuits can be configured as separate circuits or as an integrated circuit through automatic configuration wiring, etc. Alternatively, some or all of these logic circuits can be implemented by a processor such as a DSP. The same applies to the other structural examples described later.

[0065] Next, a specific processing example of this embodiment will be described. Figure 6 This is a flowchart illustrating an example of the brightness calculation process for each pixel. First, for each region of each light source, the pixel with the maximum brightness is searched (step S1). For example, in... Figure 4 , Figure 5 In each region corresponding to each light source, as described above, the brightness of pixels existing in that region is searched based on image data IM, and the pixel with the maximum brightness is found in that region. Then, the brightness distribution of each light source is determined in a way that allows the color of the pixel with the maximum brightness to be displayed (step S2). For example, assuming the brightness range is 0 to 100, in the target region, the brightness of the pixel with the maximum brightness is 50. In this case, the brightness distribution of the light source is determined in a way that the pixel with the maximum brightness, i.e., 50, can be displayed with a color that is the upper limit of the brightness range, i.e., 100. As long as the brightness of the pixel with the maximum brightness is the upper limit of the brightness range, it can be guaranteed that the brightness of other pixels falls within the brightness range of 0 to 100. Then, for each pixel of the display panel 110, the brightness is recalculated based on the diffusion coefficient information (step S3). Thus, the brightness value of the backlight 120 for each pixel is obtained.

[0066] For example, as described later Figure 14 As shown, in the display device 100, a diffuser plate 115 for diffusing light from the light source to achieve a uniform brightness distribution is disposed, for example, between the backlight 120 and the display panel 110. The diffuser plate 115 is also referred to as a diffuser sheet. For example, as... Figure 5 As shown, the light intensity distribution (PSF) of the light source decreases with distance from the light source. However, by using a diffuser plate 115 to diffuse the light from the light source, brightness unevenness can be reduced, achieving a uniform surface light source. Here, light diffusion methods include direct-lit, side-lit, and edge-lit methods. Furthermore, in... Figure 6 In step S3, besides Figure 5 In addition to the light intensity distribution (PSF) of the light source, it also reflects the diffusion of light from the light source by the diffuser plate 115. The brightness of each pixel on the display panel 110 is recalculated, and the brightness value of the backlight 120 for each pixel is determined. As an example, for an object pixel, based on... Figure 5The intensity of light from a light source, such as 4×4 LEDs, surrounding the pixel is calculated using the light intensity distribution PSF and the diffusion coefficient information of the diffuser plate 115. The brightness is then recalculated to determine the brightness value of the backlight 120 for each pixel. Thus, in a display device 100 that includes a backlight 120 with multiple light sources and a diffuser plate 115, the brightness value of the backlight 120 for each pixel can be appropriately determined.

[0067] Figure 7 This is an explanatory diagram of a color correction processing example. First, as... Figure 6 As explained, the brightness B of the backlight 120 of the target pixel is determined. Furthermore, a table of brightness-coefficients is stored in a storage circuit (not shown) of the circuit device 10, and using this table, the coefficient K is calculated based on the brightness B of the backlight 120. Figure 7 The luminance-coefficient table shows that the lower the luminance B, the larger the coefficient K. Alternatively, this luminance-coefficient table can be omitted, and the coefficient K can be calculated based on the luminance B using a prescribed formula. Furthermore, Figure 7 The brightness-coefficient table represents a first-order characteristic, but it is not limited to this; any suitable characteristic corresponding to the human eye's perception of light brightness is acceptable. Alternatively, the coefficient K can be obtained by interpolating the two output values ​​of the brightness-coefficient table using first-order interpolation or spline interpolation. Then, the obtained coefficient K is multiplied by the color level C of the target pixel to obtain the color level output to the display device 100. That is, for pixels with low brightness B in the backlight 120, the color level of the image data is increased. Thus, the color correction circuit 30 can obtain the display image data IMD from the image data IM and output it to the display device 100. Figure 7 In the brightness-coefficient table, the lower the brightness B of the backlight 120, the larger the coefficient K. Therefore, the lower the brightness of the backlight 120 for the object pixel, the higher the color level of the object pixel, thus enabling dimming control.

[0068] Figure 8 This is an explanatory diagram of an example of inverse color correction processing. First, based on the luminance B of the backlight 120 of the object pixel and a table of luminance coefficients, the coefficient K is calculated. Figure 7 In the brightness-coefficient table, the coefficient K increases as the brightness B of the backlight 120 decreases. Figure 8 In, with Figure 7 Conversely, the coefficient K decreases as the brightness B decreases. By using a table of such characteristics, it is possible to achieve... Figure 7The inverse color correction is performed by multiplying the calculated coefficient K with the color level CQ of the output pixel to obtain the color level of the original image. That is, in color correction, pixels with low brightness B of the backlight 120 are processed to increase the color level of the image data; conversely, in inverse color correction, pixels with low brightness B of the backlight 120 are processed to decrease the color level of the image data. Therefore, the inverse color correction circuit 40 can calculate the inverse color corrected image data IMR corresponding to the original image data IM based on the displayed image data IMD, and output it to the blur error detection circuit 90. That is, in... Figure 8 In the brightness-coefficient table, the lower the brightness of the backlight 120, the lower the coefficient K. Therefore, it is possible to perform brightness-coefficient analysis on the displayed image data IMD. Figure 7 The inverse transformation of color correction, i.e., inverse color correction, yields the inversely color-corrected image data IMR corresponding to the original image data IM. Furthermore, the blur error detection circuit 90 performs blur error detection processing based on the inversely color-corrected image data IMR. Thus, blur error detection processing corresponding to the display image data IMD and the dimming control results is achieved.

[0069] Alternatively, it can be omitted. Figure 8 Such a brightness-coefficient table, and the coefficient K is calculated based on the brightness B according to the prescribed formula. Alternatively, the coefficient K can also be calculated by interpolating the two output values ​​of the brightness-coefficient table using linear interpolation or spline interpolation. Furthermore, in Figure 7 , Figure 8 The code includes separate tables for color correction and inverse color correction, but it can also be used... Figure 7 The color correction table is used to calculate the coefficient K, and the color level of the original image is obtained by dividing the color CQ of the output pixel by the coefficient K.

[0070] As described above, in this embodiment, the color correction circuit 30 performs color correction on the image data IM to correspond to the brightness of the light source of the display device 100. Then, the inverse color correction circuit 40 performs inverse color correction on the displayed image data IMD to correspond to the brightness of the light source of the display device 100.

[0071] Thus, when dimming control is applied to the display device 100 to adjust the light source brightness, the image data IM undergoes color correction corresponding to the light source brightness based on the dimming control, and the color-corrected display image data IMD is output to the display device 100. Furthermore, by performing inverse color correction on the display image data IMD corresponding to the light source brightness, the inverse color-corrected image data IMR corresponding to the original image data IM is output to the blur error detection circuit 90. Therefore, the blur error detection circuit 90 can detect blur errors based on the inverse color-corrected image data IMR, which restores the original image data IM, rather than on the display image data IMD. Thus, even when dimming control is applied and color correction is performed based on dimming control, blur errors can be appropriately detected.

[0072] Specifically, such as Figure 3 As shown, the display device 100 includes a display panel 110 and a backlight 120 having multiple light sources. Additionally, as... Figure 4 , Figure 5 As explained, multiple light sources are provided corresponding to each of the multiple areas of the display panel 110. Then, the color correction circuit 30 performs color correction on the image data IM according to the brightness of each light source, and the inverse color correction circuit 40 performs inverse color correction on the displayed image data IMD according to the brightness of each light source.

[0073] Thus, when dimming control is applied to the multiple light sources of the backlight 120, each pixel illuminated by light from each light source in the image data IM undergoes color correction corresponding to the brightness of each light source based on the dimming control, and the color-corrected display image data IMD is output to the display device 100. Furthermore, in the display image data IMD, each pixel illuminated by light from each light source undergoes inverse color correction corresponding to the brightness of each light source of the backlight 120, and the inverse color-corrected image data IMR corresponding to the original image data IM is output to the blur error detection circuit 90 to detect blur errors. Therefore, even when dimming control of the backlight 120 or color correction based on dimming control is applied, blur errors can be appropriately detected.

[0074] For example, the display device 100 emits light from the backlight 120 onto the display panel 110 and drives the display panel 110 to display an image based on the display image data IMD from the circuit device 10. Figure 14Taking the head-up display 190 as an example, the displayed image of the display panel 110 is projected onto the transparent screen 160, which serves as a windshield, to display a virtual image corresponding to the displayed image to the user. Furthermore, the dimming control circuit 50 performs dimming control based on image data IM to control the brightness of the backlight 120.

[0075] Furthermore, as in Figure 7 As explained, the color correction circuit 30 performs color correction corresponding to the brightness of the backlight 120. For example, the color correction circuit 30 performs color correction as follows: the lower the brightness of the light source based on dimming control, the higher the color level of each pixel in the displayed image data IMD. That is, for pixels where the brightness of the light source decreases due to dimming control, color correction is performed to increase the color brightness of the pixel. Thus, local dimming is achieved.

[0076] On the other hand, such as in Figure 8 As explained, the inverse color correction circuit 40 performs inverse color correction corresponding to the brightness of the backlight 120. For example, the inverse color correction circuit 40 performs inverse color correction as follows: the lower the brightness of the light source based on dimming control, the lower the color level of each pixel in the inverse color corrected image data IMR. That is, for pixels whose color brightness has increased through color correction, inverse color correction is performed to reduce the color brightness, thereby generating inverse color corrected image data IMR that restores the original image data IM. As a result, the blur error detection circuit 90 can detect blur errors based on the inverse color corrected image data IMR corresponding to the original image data IM. Therefore, even when dimming control of the backlight 120 is performed and color correction is based on dimming control, blur errors can be detected appropriately.

[0077] In addition, such as Figure 3As shown, the circuit device 10 includes: a brightness analysis circuit 52 that performs brightness analysis on the image data IM; and a dimming amount calculation circuit 54 that calculates the dimming amount of each light source based on the brightness analysis results. Furthermore, the color correction circuit 30 performs color correction based on the dimming amount calculation results in the dimming amount calculation circuit 54, and the inverse color correction circuit 40 performs inverse color correction based on the dimming amount calculation results in the dimming amount calculation circuit 54. Thus, based on the brightness analysis results of the image data IM, the dimming amount of each of the multiple light sources of the backlight 120 is calculated, and dimming control of the backlight 120 is performed based on the calculated dimming amounts. Then, by performing color correction based on the calculated dimming amounts, color correction corresponding to the dimming control of the backlight 120 is performed, and the color-corrected display image data IMD can be output to the display device 100. In addition, based on the calculated dimming amount, the color-corrected display image data IMD is subjected to inverse color correction, thereby inputting the inverse color-corrected image data IMR corresponding to the image data IM before color correction to the blur error detection circuit 90, so as to appropriately detect blur errors.

[0078] Furthermore, the dimming calculation circuit 54 calculates the dimming amount of each light source based on the diffusion coefficient information of the backlight 120 and the results of brightness analysis. For example, as Figure 14 As shown, when a diffuser plate 115 is provided on the backlight 120 to diffuse the light from the backlight 120, the dimming amount of each light source is calculated based on the diffusion coefficient information of the light source by the diffuser plate 115 and the brightness analysis results of the image data IM. In this way, even when the brightness is reduced unevenly due to the diffusion of the light from the backlight 120, dimming control and color correction that reflect the diffusion of the light source can be performed.

[0079] Furthermore, in this embodiment, the blur error detection circuit 90 calculates a blur error determination index value and compares this determination index value with a threshold, thereby performing blur error detection processing. Specifically, the blur error detection circuit 90 calculates a determination index value corresponding to the display image data IMD and the result of dimming control, and compares this determination index value with a threshold, thereby detecting blur errors. For example, in Figure 3In this process, the inverse color-corrected image data IMR, generated based on the display image data IMD and the dimming control results, is input to the blur error detection circuit 90. Then, the blur error detection circuit 90 calculates a blur error determination index value based on this inverse color-corrected image data IMR and compares it with a threshold to detect blur errors. Alternatively, as described later, the blur error detection circuit 90 calculates a determination index value based on the inverse distortion-corrected image data generated from the display image data IMD and the dimming control results and compares it with a threshold to detect blur errors. Thus, by using the determination index value calculated based on the display image data IMD and the dimming control results, blur errors can be detected through simple processing. Furthermore, in the event of a blur error, the supply of display image data IMD is stopped, or the backlight 120 is turned off, or the display image data IMD is set to a transparent color for black display. This prevents the reduction of background visibility due to blur errors.

[0080] Here, the threshold is stored, for example, in a storage circuit (not shown) of the circuit device 10. Furthermore, as described above, the determination index value is, for example, the cumulative or average value of pixel brightness in the determination region of the blur error, or the number or ratio of high-brightness pixels in the determination region. In this case, if the determination index value exceeds the threshold, the blur error detection circuit 90 determines that a blur error has been detected. Alternatively, the determination index value is the number or ratio of black pixels in the determination region. In this case, if the determination index value is less than the threshold, the blur error detection circuit 90 determines that a blur error has been detected. Thus, appropriate blur error detection processing using the determination index value can be implemented.

[0081] 3. Example of the second structure

[0082] Figure 9 A detailed second structural example of the circuit device 10 of this embodiment is shown. Figure 9 In the circuit device 10, there is a distortion correction circuit 20 that performs distortion correction on the input image data IMI and outputs image data IM. The blur error detection circuit 90 performs blur error detection processing on each region of the multiple regions obtained by segmenting the image of the input image data IMI according to the region determination signal AJ output by the distortion correction circuit 20.

[0083] That is, the circuit device 10 of this embodiment includes a distortion correction circuit 20 that performs distortion correction on input image data IM and outputs image data IM. In this way, color correction or dimming control can be performed based on the image data IM after distortion correction by the distortion correction circuit 20. Therefore, appropriate color correction and dimming control can also be implemented in the HUD display device 100 that requires distortion correction of the image display. Specifically, for example... Figure 14 As shown, when the transparent screen 160, which serves as the projection surface for the displayed image of the display device 100, is bent, distortion correction corresponding to the bend can be performed to display a distortion-free image to the user, and appropriate color correction and dimming control can be achieved. Furthermore, in this embodiment, the blur error detection circuit 90 performs blur error detection processing based on the region determination signal AJ output from the distortion correction circuit 20.

[0084] For example, Figure 10 This diagram illustrates 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 the input image data IMI, and the output image of the distortion correction circuit 20 corresponds to the image data IM. The HUD displays the display image data IMD, which is obtained by color correction of the image data IM.

[0085] exist Figure 10 In this context, ARA represents each of the first segmentation regions in the first segmentation region group obtained by segmenting the input image. Specifically, the segmentation regions are defined by multiple straight lines in the horizontal scanning direction and multiple straight lines in the vertical direction. Furthermore, in... Figure 10 The example shown is dividing an image into 6×4 parts, but the number of divisions is not limited to this. Additionally, in Figure 10 The image is shown as being segmented equally in both the horizontal and vertical directions, but unequal segmentation is also possible.

[0086] The input image, after undergoing distortion correction in the opposite direction to the distortion caused by HUD projection, is projected by the HUD, thus becoming a distortion-free display identical to the input image. That is, setting a first segmentation group in the input image is equivalent to setting a segmentation group in the HUD display. This segmentation group in the HUD display is designated as the third segmentation group, and each third segmentation region is denoted by ARH. The shape of the third segmentation region ARH is the same as the first segmentation region ARA corresponding to that third segmentation region ARH. Furthermore, the coordinates (u, v) on the input image and the coordinates (x, y) on the output image are mapped through a coordinate transformation for distortion correction. Through this coordinate mapping, the output image is segmented into a second segmentation group corresponding to the first segmentation group. Each second segmentation region in the second segmentation group is denoted by ARB. The second segmentation region ARB becomes distorted in shape through distortion correction.

[0087] For example, in this embodiment, in Figure 2 In this system, blurring errors can be detected when the visibility of objects such as people and bicycles is reduced due to the HUD image. For example, when detecting objects like bicycles using a camera not shown, the area of ​​the object can be used as the decision area for blurring error detection. Figure 10 For example, in the HUD display image, the third segmentation region (ARH) displaying objects such as people and bicycles is used as the judgment region to detect blur errors. Specifically, different threshold values ​​are set for the regions where objects such as people and bicycles are detected and for other regions. These threshold values ​​are compared with a blur error judgment index to detect blur errors. For instance, a smaller threshold value is set in the regions where objects are detected, and a larger threshold value is set in other regions. If the judgment index value exceeds the set threshold, a blur error is determined to have occurred. In this way, by using a smaller judgment index value in the regions where objects such as people and bicycles are located, blur errors can be detected, effectively preventing objects from being obscured by the HUD image and thus becoming invisible.

[0088] Moreover, in Figure 9 In the image, the blur error detection circuit 90 detects blur errors based on the inversely color-corrected image obtained by performing inverse color correction on the output image of the distortion correction circuit 20. Therefore, in Figure 10 In this process, the deformed region, i.e., the second segmentation region ARB, needs to be used as the decision region to detect blur errors. Therefore, there is a problem of determining which region in the inverse color-corrected image should be used as the decision region to detect blur errors.

[0089] Therefore, in this embodiment, the distortion correction circuit 20 outputs a region determination signal AJ, and the blur error detection circuit 90 performs blur error detection processing on each of the multiple regions obtained by segmenting the input image data IMI based on the region determination signal AJ output by the distortion correction circuit 20. In this way, the blur error detection circuit 90 can determine the determination region based on the region determination signal AJ from the distortion correction circuit 20 in the inverse color-corrected image obtained by color correction and inverse color correction of the output image of the distortion correction circuit 20, and detect blur errors in that determination region.

[0090] For example, the image of the input image data IMI and Figure 10 The input image corresponds to each region obtained by segmenting the input image and... Figure 10 The first segmentation region ARA corresponds to the first segmentation region ARA in the input image. Furthermore, the distortion correction circuit 20 performs distortion correction based on the correspondence between coordinates (u, v) in the input image and coordinates (x, y) in the output image, thus outputting a region determination signal AJ to determine which of the first segmentation regions ARA in the input image corresponds to the second segmentation region ARB in the output image. As described above, the first segmentation region ARA in the input image corresponds to the third segmentation region ARH in the HUD display image. Therefore, the blur error detection circuit 90 can determine the third segmentation region ARH where the object is located in the inverse color-corrected image based on the region determination signal AJ from the distortion correction circuit 20, and use this region as the determination region to detect blur errors. Therefore, the blur 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 detect blur errors in that determination region.

[0091] 4. Example of the third structure

[0092] Figure 11 A detailed third structural example of the circuit device 10 of this embodiment is shown. In the third structural example, except... Figure 3 In addition to the structure, it also includes an inverse distortion correction circuit 70, and line buffers 22 and 72. For example, in Figure 3 In the image, the blur error detection circuit 90 detects blur errors based on the inverse color-corrected image data (IMR). In contrast, in... Figure 11 In this circuit, the blur error detection circuit 90 detects blur errors based on the inverse distortion-corrected image data IMRR, which is obtained by inverse distortion correction of the inverse color-corrected image data IMR. Thus, the blur error detection circuit 90 can perform blur error detection processing based on the inverse distortion-corrected image data IMRR corresponding to the original input image data IMI, and can detect blur errors by simply setting the judgment area for blur errors.

[0093] For example, the distortion correction circuit 20 performs a mapping process to map the image by matching it to the surface shape of the projected object, which is called distortion correction processing. This mapping process deforms the image so that the user can see the image projected onto the projected object in an undistorted state. On the other hand, the inverse distortion correction circuit 70 performs an inverse mapping process corresponding to the inverse transformation of the mapping process performed by the distortion correction circuit 20, which is called inverse distortion correction processing. This inverse mapping process is a transformation that restores the image deformed according to the projected object to the image before deformation. The projected object is an object on which the display image generated by the circuit device 10 is projected or displayed. In the case of a head-up display in a car, the projected object is the windshield of a car, etc. The mapping process is a process of performing coordinate transformation on the pixel positions of the image based on mapping parameters, which are also called mapping data. As a process accompanying coordinate transformation, the mapping process can include pixel value interpolation processing, etc. As a mapping process, there are forward mapping and reverse mapping. The mapping parameters are parameters that represent the coordinate transformation corresponding to the shape of the reflective surface of the projected object, and are data that corresponds between the pixel positions of the image before the mapping process and the pixel positions of the image after the mapping process, etc. The mapping processing performed by the distortion correction circuit 20 and the inverse mapping processing performed by the inverse distortion correction circuit 70 can be implemented using these mapping parameters. Furthermore, a line buffer 22 is provided before the distortion correction circuit 20, and the distortion correction circuit 20 uses the input image data IMI temporarily stored and accumulated in the line buffer 22 to perform distortion correction. Similarly, a line buffer 72 is also provided before the inverse distortion correction circuit 70, and the inverse distortion correction circuit 70 uses the inverse color-corrected image data IMR temporarily stored and accumulated in the line buffer 72 to perform inverse distortion correction. The line buffers 22 and 72, for example, temporarily store image data for a specified number of scan lines.

[0094] so, Figure 11 The circuit device 10 includes: a distortion correction circuit 20 that performs distortion correction on the 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 result of dimming control, thereby outputting display image data IMD. Furthermore, the circuit device 10 includes: an inverse color correction circuit 40 that performs inverse color correction on the display image data IMD based on the result of dimming control, thereby outputting 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, thereby outputting inverse distortion-corrected image data IMRR. Moreover, a blur error detection circuit 90 performs blur error detection processing based on the inverse distortion-corrected image data IMRR. In this way, a blur error determination region can be set in the coordinate system of the original input image data IMI, thus simplifying the setting of the determination region.

[0095] That is, the inversely distorted image data IMRR is image data that has undergone distortion correction by the distortion correction circuit 20 on the original input image data IMI, and then inversely distorted image data by the inverse distortion correction circuit 70. Therefore, the inversely distorted image, which is the image of the inversely distorted image data IMRR, and the image, which is the input image data IMI, are... Figure 10 The input image is also a distortion-free image. Therefore, with Figure 9 Depending on the situation, the fuzzy error detection circuit 90 can determine the judgment area where objects such as people and bicycles are located through simple processing, and detect fuzzy errors in the judgment area.

[0096] 5. Example of the fourth structure

[0097] Figure 12 A detailed fourth structural example of the circuit device 10 of this embodiment is shown. In the fourth structural example, instead of Figure 3 A brightness calculation circuit 44 is provided in addition to the inverse color correction circuit 40. Furthermore, the blur error detection circuit 90 performs blur error detection processing based on the brightness information BR from the brightness calculation circuit 44. For example, based on the dimming control result, the brightness calculation circuit 44 converts the brightness values ​​of each pixel in the color-corrected display image data IMD to their original brightness values ​​and outputs them as brightness information BR. In this way, blur error detection processing corresponding to the display image data IMD and the dimming control result can be achieved through a low-load processing method such as calculating the brightness information BR.

[0098] For example in Figure 3 In this process, inverse color correction is performed on the color-corrected display image data IMD to obtain the inverse color-corrected image data IMR corresponding to the image data after restoring the original image data IM. Blur errors are then detected based on this inverse color-corrected image data IMR. However, since blur errors can be determined based on brightness, restoring the original image data IM is not always necessary. Therefore, in... Figure 12 In this process, the brightness calculation circuit 44 calculates the brightness information BR corresponding to the original image data IM based on the dimming amount information, which is a result of the dimming control in the dimming control circuit 50, and the display image data IMD. For example, the brightness calculation circuit 44 calculates the brightness of each pixel in the display image data IMD, and compares it with... Figure 7The same method is used to convert the calculated pixel brightness to generate brightness information BR. For example, based on the brightness value of the backlight 120, which is information about dimming, a conversion process is performed where the lower the brightness value of the backlight 120, the lower the brightness of the pixel, generating brightness information BR. Brightness information BR, for example, is information that sets a brightness value for each pixel of multiple pixels constituting the image. Then, based on the brightness information BR, the blur error detection circuit 90 calculates the aforementioned blur error judgment index value and compares the calculated judgment index value with a threshold to detect blur errors. For example, based on the brightness information BR, the blur error detection circuit 90 performs cumulative processing on the brightness of multiple pixels in the judgment area and calculates the cumulative value or average value as the judgment index value. Alternatively, the blur error detection circuit 90 calculates the number or ratio of high-brightness pixels or black pixels in the judgment area based on the brightness information BR as the judgment index value. Thus, the brightness information BR can be calculated with less processing load compared to inverse color correction, and blur errors can be detected based on the brightness information BR.

[0099] 6. Example of the fifth structure

[0100] Figure 13 A detailed fifth structural example of the circuit device 10 of this embodiment is shown. In this fifth structural example, each circuit of the circuit device 10 sends a region determination signal AJ along with image data to a subsequent 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. Furthermore, the inverse color correction circuit 40 outputs the region determination signal AJ along with the inverse color corrected image data IMR to the blur error detection circuit 90. For example, the region determination signal AJ is output to the subsequent circuit as index data for region determination corresponding to each pixel data of the image data. That is, the index data specifying the region where each pixel is located is output in correspondence with each pixel data. In this way, each circuit of the color correction circuit 30, the inverse color correction circuit 40, and the blur error detection circuit 90 can determine which region each pixel data of the image data belongs to based on the region determination signal AJ. Furthermore, compared with... Figure 9 , Figure 10 Similarly, as described in the method, the fuzzy error detection circuit 90 can determine the determination area, such as where a person or bicycle is located, based on the area determination signal AJ, and detect fuzzy errors in the determination area.

[0101] Furthermore, while the first to fifth structural examples of this embodiment have been described above, this embodiment is not limited to these examples and can be modified in various ways, such as combining at least two of the first to fifth structural examples.

[0102] 7. Head-up display

[0103] Figure 14 This diagram illustrates a structural example of the head-up display 190 according to this embodiment. The head-up display 190 of this embodiment includes the circuitry 10 and the display device 100 of this embodiment. The display device 100 projects a display image based on display image data (IMD) from the circuitry 10. For example, the display device 100 includes a display panel 110 and a backlight 120. Furthermore, the display device 100 may include a display driver 140 for driving the display panel 110 and a diffuser 115 disposed between the display panel 110 and the backlight 120. Additionally, the display device 100 may include a projection optical system such as a reflector 150 for reflecting the projected light of the projected image.

[0104] The display driver 140 drives the data lines or scan lines of the display panel 110 to display an image based on the display image data IMD from the circuit device 10. Light emitted from the backlight 120 passes through the diffuser 115 and the display panel 110, and is reflected by the reflector 150 towards the transparent screen 160. The transparent screen 160 is, for example, a car windshield. The reflective surface of the transparent screen 160 is, for example, concave, so the projected image appears as a virtual image to the user. That is, from the user's perspective, the projected image appears to be formed at a position farther than the transparent screen 160. Thus, the projected image can be displayed within the background. Furthermore, the head-up display 190 is not limited to... Figure 14 The structure allows for various modifications. For example, the display panel 110 can be any display panel other than a liquid crystal display panel, and the configuration structure of the diffuser 115 and the projection optical system can also be modified in various ways.

[0105] As explained above, the circuit arrangement of this embodiment is used in a head-up display (HUD) that projects images using display image data and a light source. The HUD includes: a dimming control circuit that controls the dimming of the light source based on the image data; a color correction circuit that performs color correction on the image data corresponding to the result of the dimming control, thereby outputting display image data; and a blur error detection circuit that performs blur error detection processing on the HUD corresponding to the display image data and the result of the dimming control.

[0106] This allows for the detection of blur errors that reflect the dimming control results in the dimming control circuit. Therefore, compared to methods that only use displayed image data to detect blur errors, blur errors can be appropriately detected even when dimming control is in effect.

[0107] Alternatively, this embodiment may include an inverse color correction circuit, which performs inverse color correction on the displayed image data based on the dimming control result, thereby outputting inverse color corrected image data. The blur error detection circuit performs blur error detection processing based on the inverse distortion corrected image data.

[0108] In this way, the image data after inverse color correction becomes image data based on the displayed image data and the dimming control results. By detecting blur errors based on such inverse color correction image data, it is possible to achieve blur error detection processing corresponding to the displayed image data and the dimming control results.

[0109] In addition, this embodiment includes a distortion correction circuit that corrects the distortion of the input image data and outputs image data. The blur error detection circuit performs blur error detection processing in each region of the multiple regions obtained by segmenting the input image data according to the region determination signal output by the distortion correction circuit.

[0110] In this way, the region can be determined based on the region determination signal from the distortion correction circuit, and fuzzy errors in the region can be detected.

[0111] Alternatively, this embodiment may also include: a distortion correction circuit that performs distortion correction on the input image data and outputs image data; an inverse color correction circuit that performs inverse color correction on the displayed image data based on the dimming control result, thereby outputting inverse color-corrected image data; and an inverse distortion correction circuit that performs inverse distortion correction on the inverse color-corrected image data, thereby outputting inverse distortion-corrected image data. Furthermore, a blur error detection circuit can also perform blur error detection processing based on the inverse distortion-corrected image data.

[0112] In this way, blur error detection can be performed based on the inverse distortion corrected image data corresponding to the input image data, thereby enabling the simple setting of the blur error judgment area and the detection of blur errors.

[0113] Alternatively, in this embodiment, the color correction circuit may perform color correction on the image data corresponding to the brightness of the light source of the display device, and the inverse color correction circuit may perform inverse color correction on the displayed image data corresponding to the brightness of the light source.

[0114] In this way, blur errors can be properly detected even when dimming control is being performed or color correction based on dimming control is being performed.

[0115] Alternatively, in this embodiment, the display device may include a display panel and a backlight having multiple light sources, with each light source corresponding to a region of the multiple areas of the display panel. Furthermore, a color correction circuit may perform color correction on the image data corresponding to the brightness of each light source, and an inverse color correction circuit may perform inverse color correction on the displayed image data corresponding to the brightness of each light source.

[0116] In this way, even when performing color correction based on backlight dimming control, blur errors can be detected appropriately.

[0117] Alternatively, this embodiment may also include a brightness calculation circuit, which, based on the dimming control result, converts the brightness values ​​of each pixel in the color-corrected display image data into their original brightness values ​​before color correction, and outputs this as brightness information. Furthermore, a blur error detection circuit can also perform blur error detection processing based on the brightness information.

[0118] In this way, with minimal processing such as brightness information calculation, it is possible to detect and process blurry errors corresponding to the results of display image data and dimming control.

[0119] In addition, in this embodiment, the dimming control circuit may also include: a brightness analysis circuit that performs brightness analysis on the image data; and a dimming amount calculation circuit that calculates the dimming amount of the light source based on the result of the brightness analysis.

[0120] In this way, by using the dimming amount calculated based on the brightness analysis results of the image data, it is possible to achieve blur error detection and processing corresponding to the display image data and dimming control results.

[0121] In addition, in this embodiment, the blur error detection circuit can also calculate the blur error judgment index value corresponding to the display image data and the dimming control result, and compare the judgment index value with the threshold to perform blur error detection processing.

[0122] In this way, by using the judgment index value derived from the displayed image data and the results of dimming control, blur errors can be detected through simple processing.

[0123] Furthermore, 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.

[0124] Furthermore, although this embodiment has been described in detail above, those skilled in the art will readily understand that various modifications can be made without substantially departing from the novel aspects and effects of this disclosure. Therefore, all such modifications are included within the scope of this disclosure. For example, in the specification or drawings, any term that is described at least once with a different term that is more general or synonymous can be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of this embodiment and its modifications are also included within the scope of this disclosure. Additionally, the structure and operation of circuit devices, display devices, head-up displays, etc., are not limited to those described in this embodiment, and various modifications can be implemented.

Claims

1. A circuit device used in a head-up display (HUD) that projects images using displayed image data and a light source, characterized in that, The circuit device includes: A dimming control circuit that performs dimming control of the light source based on image data; A color correction circuit performs color correction on the image data corresponding to the result of the dimming control, thereby outputting the display image data. A blur error detection circuit performs blur error detection processing on the head-up display corresponding to the display image data and the result of the dimming control; as well as The inverse color correction circuit performs inverse color correction on the displayed image data based on the dimming control result, thereby outputting inverse color corrected image data. The blur error detection circuit performs blur error detection processing based on the inverse color-corrected image data.

2. The circuit device according to claim 1, characterized in that, The circuit device includes a distortion correction circuit that corrects the distortion of the input image data and outputs the image data. The blur error detection circuit performs blur error detection processing in each region of the multiple regions obtained by segmenting the input image data according to the region determination signal output by the distortion correction circuit.

3. The circuit device according to claim 1, characterized in that, The circuit device includes: Distortion correction circuit, which performs distortion correction on input image data and outputs the image data; and An inverse distortion correction circuit performs inverse distortion correction on the inverse color-corrected image data, thereby outputting inverse distortion-corrected image data. The blur error detection circuit performs blur error detection processing based on the inverse distortion corrected image data.

4. The circuit device according to any one of claims 1 to 3, characterized in that, The color correction circuit performs color correction on the image data to correspond to the brightness of the light source of the display device. The inverse color correction circuit performs inverse color correction on the displayed image data corresponding to the brightness of the light source.

5. The circuit device according to any one of claims 1 to 3, characterized in that, The display device includes a display panel and a backlight with multiple light sources. Each of the plurality of light sources is configured corresponding to a region of the plurality of areas on the display panel. The color correction circuit performs color correction on the image data corresponding to the brightness of each light source. The inverse color correction circuit performs inverse color correction on the displayed image data corresponding to the brightness of each light source.

6. A circuit device for use in a head-up display that projects images using displayed image data and a light source, characterized in that, The circuit device includes: A dimming control circuit that performs dimming control of the light source based on image data; A color correction circuit performs color correction on the image data corresponding to the result of the dimming control, thereby outputting the display image data. A blur error detection circuit performs blur error detection processing on the head-up display corresponding to the display image data and the result of the dimming control; as well as The brightness calculation circuit, based on the dimming control result, converts the brightness values ​​of each pixel in the color-corrected display image data back to their original brightness values ​​before color correction, and outputs them as brightness information. The blur error detection circuit performs blur error detection processing based on the brightness information.

7. The circuit device according to any one of claims 1 to 3 and 6, characterized in that, The dimming control circuit includes: A brightness analysis circuit performs brightness analysis on the image data; and The dimming calculation circuit calculates the dimming amount of the light source based on the results of the brightness analysis.

8. The circuit device according to any one of claims 1 to 3 and 6, characterized in that, The blur error detection circuit calculates the judgment index value of the blur error corresponding to the display image data and the dimming control result, and compares the judgment index value with a threshold to perform the blur error detection processing.

9. A head-up display, characterized in that, The head-up display includes: The circuit device according to any one of claims 1 to 8; and The display device projects a display image based on the display image data from the circuit device.

Images