Vehicle display device

Abstract

Vehicle display device (10), comprising: a projection direction change mechanism (15) configured to set a light projection direction in which display light containing a specific image is emitted; and a display control unit (16) for changing a correction pattern from a plurality of correction patterns for correcting a shape of the image based on a projection direction adapted by the projection direction change mechanism (15), and for correcting the shape of the image based on the correction pattern; wherein the the indicator light, which contains the shape of the image corrected by the display control unit (16), is emitted and directed onto a windshield (WS) so that the indicator light reflected on a surface of the windshield (WS) is visually detected, wherein the display control unit (16) has a plurality of correction patterns corresponding to changes in the image according to the projection direction of the projection direction change mechanism (15), selects a correction pattern from the correction patterns according to a segment corresponding to an eye level (ER) of a driver specified on the basis of the projection direction set by the projection direction change mechanism (15), and corrects the shape of the image based on the correction pattern, and wherein the display control unit (16) has a plurality of types of correction patterns corresponding to a change in the image that occurs due to variations in a shape and size of the windscreen (WS), based on a manufacturing variation parameter (Pw) that characterizes the type of manufacturing variations between the windscreens (WS), wherein the manufacturing variation parameter (Pw) is associated with the status of an operating switch, and corrects the shape of the image based on the correction patterns specified from the plurality of types.

Description

Area

[0001] The present invention relates to a vehicle display device for displaying images using optical reflection on a windshield (a glass window) arranged in front of a vehicle driver. background

[0002] Typically, head-up display (HUD) systems for vehicles project informational light from a HUD unit onto a reflective surface, often called the windshield, or a combiner. This creates an optical path so that the light reflected from the windshield is aligned with the driver's line of sight. The driver can visually perceive an image contained in the light emitted by the HUD unit and projected onto the windshield, while simultaneously viewing the front of the vehicle through the windshield. The driver can visually perceive various types of information contained in the HUD unit's light while maintaining normal driving conditions and without obstructing their view.

[0003] In devices such as a head-up display (HUD) that project various types of information onto a windshield using optical reflection, the driver may perceive a distorted image. Optical reflection off the surface of a sloping windshield distorts the shape of the image. The slightly curved surface of the windshield further distorts the image. The curvature and angle of inclination to the horizontal (or vertical) surface vary between positions on the windshield, and these differences cause different types of distortion depending on the position from which the indicator light is projected onto the image perceived by the driver. This distortion negatively impacts the visually perceived image.

[0004] With this in mind, techniques for correcting the distortion of an image in a vehicle HUD device were developed (see patent literature 1 and patent literature 2).

[0005] The display device described in patent literature 1 has a manual operating switch that is movable up and down. The device is configured such that an image is corrected by manually operating the switch. In a case where a virtual image is warped in such a way that its lateral expansion narrows upwards or downwards, the image can be corrected by operating the switch.

[0006] The vehicle display device described in patent literature 2 uses a coordinate conversion table to correct the distortion of a displayed image. The display device stores the coordinate conversion table in a removable external read-only memory (ROM) or non-volatile memory.

[0007] Furthermore, DE 10 2009 019 945 A1 discloses a system and associated methods for processing images in a head-up display (HUD) system of a vehicle. The images are processed by adjusting the image data in a way that compensates for various shape and contour properties of the vehicle's windshield. List of quotations Patent literature Patent literature 1: Publication of the Japanese patent application JP H11-30764 A Patent Literature 2: JP 2002-205571 A Summary: Technical Task

[0008] In the technique described in patent literature 1, image distortion caused by the surface shape of the windshield or other factors can be corrected as needed by operating the manual control switch. In the technique described in patent literature 2, image distortion can be corrected by replacing the external ROM or overwriting the coordinate conversion table of the non-volatile memory.

[0009] However, the position of a viewpoint changes depending on the driver's height, seating position, posture, and other factors. The optical path the indicator light travels to reach the viewpoint changes accordingly. This change in optical path also alters the degree of image distortion.

[0010] If, according to the technique described in patent literature 1, a driver wants to be able to perceive an image visually without distortion at all times, the driver must frequently activate the switch whenever the viewing position changes. According to the technique described in patent literature 2, the external ROM must be replaced or the contents of the non-volatile memory overwritten every time the image becomes distorted due to a change in the viewing position. Both patent literature 1 and patent literature 2 require rather complicated procedures from drivers attempting to perceive an image visually without distortion at all times.

[0011] To overcome the disadvantages described above, one objective of the present invention is to provide a vehicle display device with improved operability for correcting a distortion caused on a display image that is visually perceived by a driver. Technical solution

[0012] The above objective is achieved by a vehicle display device according to claim 1.

[0013] A vehicle display device according to the present invention for achieving the problem solution described above comprises a projection direction change mechanism configured to adjust a light projection direction in which a display light containing a specific image is emitted; and a display control unit configured to change a correction pattern to correct the shape of the image based on a projection direction adjusted by the projection direction change mechanism, and to correct the shape of the image based on the correction pattern; wherein the display light containing the shape of the image corrected by the display control unit is emitted and directed onto a windshield so that the display light reflected on a surface of the windshield is visually detected.

[0014] In the vehicle display device, the display control unit is preferably configured to have a plurality of correction patterns, to select a correction pattern from the correction patterns according to a segment corresponding to a driver's eye level specified on the basis of the projection direction set by the projection direction change mechanism, and to correct the shape of the image based on the correction pattern.

[0015] In the vehicle display device, the display control unit is configured to have a variety of correction patterns corresponding to changes in the image that occur due to variations in the shape and size of the windscreen, and to correct the shape of the image based on the correction patterns specified from the variety of types. Advantageous effects of the invention

[0016] In the vehicle display device according to the present invention, the operability for correcting distortion caused in a display image perceived by a driver is improved. Brief description of the drawings Fig. Figure 1 is a perspective view of a detailed example of a positional relationship between main components of a vehicle display device. Fig. Figure 2 is a vertical sectional view illustrating a structural component of a head-up display (HUD) unit and an optical path of light projected by the HUD unit. Fig. Figure 3 is a schematic representation illustrating examples of corrected and uncorrected display formats. Fig. Figure 4 is a schematic representation illustrating relationships between shapes from a variety of correction pattern data and parameters stored in a database. Fig. Figure 5 is a flowchart illustrating the sequence of a main protocol of the vehicle display device in an embodiment of the present invention. Fig. Figure 6A is a schematic representation illustrating a correspondence between segments in the vertical direction of an eye box, correction pattern shapes in image processing, and shapes of visually recognized display images. Fig. Figure 6B is a schematic representation illustrating a correspondence between segments in the vertical direction of the eye box, correction pattern shapes in image processing, and shapes of visually recognized display images. Description of the exemplary embodiments

[0017] In the following, an embodiment relating to a vehicle display device of the present invention is described in detail with reference to the drawings. Summary of device configuration

[0018] Fig. 1 and Fig. Figure 2 shows the vehicle display device according to the present embodiment and its associated main components. Fig. 1 and Fig. 2 the vehicle display device according to the present invention corresponds to a head-up display unit (HUD) 10.

[0019] The HUD unit 10 is located in a vehicle instrument panel and is configured to emit light upwards from an opening formed on part of the surface of the instrument panel.

[0020] A liquid crystal display panel 11, a backlight 12, an aspherical mirror 13, a projection direction change mechanism 15 and a display control unit 16 are contained in the HUD unit 10, as shown in Fig. 1 and Fig. 2 shown.

[0021] The liquid crystal display panel 11 is a transparent liquid crystal display with a rectangular display area configured with a multitude of pixels aligned in the vertical and horizontal directions. Various types of controls can be applied to the liquid crystal display panel 11, for example, regarding the on / off status of the display, display colors, and contrast density for individual pixels, in response to a command from a display control unit 16 described below.

[0022] The backlight 12 is a light source located on the rear surface of the liquid crystal display panel 11 and emits illumination necessary to project a display image onto the liquid crystal display panel 11. The backlight 12's light source has sufficient luminosity to project an image to a relatively distant position. The emission of illumination from the backlight 12 onto the liquid crystal display panel 11 is controlled in response to a command from the display control unit 16, described below.

[0023] The aspherical mirror 13 reflects light incident on its surface from the side of the liquid crystal display panel 11 and emits the light towards a windshield WS (a transparent glass window). The aspherical mirror 13 has the optical property of forming an image at a specific distant position.

[0024] The projection direction change mechanism 15 assists the aspherical mirror 13 in such a way that the tilt angle of the surface of the aspherical mirror 13 can be adjusted. For example, the tilt angle of the aspherical mirror 13 can be changed as needed by driving the projection direction change mechanism 15 with an electric motor (not shown). Changing the tilt angle of the aspherical mirror 13 alters the direction of the light emitted by the HUD unit 10. The adjustment of the tilt angle of the surface of the aspherical mirror 13 using the projection direction change mechanism 15 is controlled in response to a command from the display control unit 16, described below.

[0025] The display control unit 16 displays an image on the display surface of the liquid crystal display panel 11. For example, the display control unit 16 acquires information about the current speed (km / h) of a vehicle and draws graphically visible information, including a letter pattern and the like, corresponding to the numerical value indicating the speed, onto the two-dimensional plane of the display surface. The display control unit 16 can serve as an image processing unit to correct image distortion and the like due to the properties of an optical system element of the vehicle display device. The display control unit 16 is connected to the liquid crystal display panel 11 described above, the rear light 12, and the projection direction change mechanism 15, and controls the activities of these mechanisms by issuing commands to them.The hardware configuration of the display control unit 16 consists of a central processing unit (CPU), which acts as the control unit and primarily performs the computational processing; memory (such as main memory (RAM) and read-only memory (ROM)), which serves as a storage unit for programs and information; an input / output interface; and other components. The configuration is the same as that of familiar PCs, so a detailed description is omitted. The storage unit of the display control unit 16 stores information, including, as described later, a pattern of uncorrected display data, a variety of types of correction patterns used in image processing, a pattern of corrected display data, and other information.The display control unit 16 is connected to an engine control unit (ECU) (not shown), which serves as a control unit for controlling the vehicle in a communicative manner and is capable of acquiring various types of information (such as vehicle speed) that indicate the vehicle's driving conditions. Summary of the optical path

[0026] While using HUD unit 10, as described in Fig. 1 and Fig. As shown in Figure 2, the indicator light, as visible information including an image displayed on the display surface of the liquid crystal display panel 11, passes through the illumination light from the rear light 12 onto the aspherical mirror 13. The light reflected by the aspherical mirror 13 is emitted towards the windshield (WS). The light is reflected off an irradiation surface 14 on the windshield WS and directed towards an eyepiece EB (see Figure 2). Fig. 1) projected, which is a box-shaped space that includes the assumed positions of the driver's eyes (point of view).

[0027] In this configuration, the driver can visually perceive an image on the windshield WS that is equivalent to the visible information displayed on the display area of ​​the liquid crystal display panel 11. This process is effectively caused by projecting an image using reflection on the surface of the windshield WS. A display image 30, which is visually perceived at the position of the eye box EB, is thus an image that is formed as a virtual image and is visually perceived as if the image were present at a position, for example, two meters in front of the windshield WS, as in Fig. 1 and Fig. 2 shown.

[0028] The display image 30, which is formed by projection through the HUD unit 10, can be visually recognized in the region of an eye area ER (see Fig. 1), which is a larger space than the eye box EB and which includes the eye box EB within its interior. If the height of the eye area region ER changes, for example, due to seat height adjustment or a difference in driver height, this change can be adjusted by changing the tilt angle of the aspherical mirror 13. In this case, the display control unit 16 issues a command to the projection direction change mechanism 15 in response to a driver operation, which is initiated by an operating switch (not shown) or the like, located in the HUD unit 10. In response to the command, the projection direction change mechanism 15 controls the change in the tilt angle of the aspherical mirror 13. The direction of any light emitted by the HUD unit 10 is changed according to the change in the tilt angle of the aspherical mirror 13.Thus, the irradiation area 14 on the windshield WS is changed, which accordingly changes the projection direction of the light reflected on the irradiation area 14. This allows the height of the eye area ER to be changed.

[0029] In this embodiment, the tilt angle of the aspherical mirror 13 is variable. In another embodiment, the entire HUD unit 10 can tilt variably relative to the vehicle, with the aspherical mirror 13 fixed to the HUD unit 10. Furthermore, by configuring the HUD unit 10 to be displaceable longitudinally with respect to the vehicle's direction of travel, the position at which the HUD unit 10 emits light can be changed. This displacement alters the irradiation area 14, thereby changing the assumed height of the eye area ER. Description of the image distortion

[0030] In a top-down view of the optical path, the windscreen WS is not perpendicular to the optical path, but rather inclined to it. The windscreen WS generally has a slightly curved shape, with the curvature varying slightly depending on the position of the elements on the windscreen WS. Even when the HUD unit 10 projects a rectangular image, a distorted display image is actually perceived visually. Description of the principle for correcting the distortion of the display image 30

[0031] Fig. Figure 3 shows detailed examples of uncorrected and corrected forms of display images. The examples from Fig. Figure 3 shows the pattern of uncorrected display data 35A in a grid pattern, with lines drawn at equal intervals in the vertical and horizontal directions within a rectangular outer frame.

[0032] If the pattern of uncorrected display data 35A is displayed without correction on the liquid crystal display panel 11, distortion will occur with such a shape of the display image 30A, depending on the shape of the irradiation area 14 on the windshield WS or other effects. Fig. 3. This is caused by the image that is visually perceived by the driver. In this case, the display image 30A must be corrected to the shape of display image 30B, the same shape as the pattern of the uncorrected display data 35A.

[0033] In this case, corrected display data 35B is generated by transforming the coordinates of the uncorrected display data 35A, and the pattern of the corrected display data 35B is displayed on the liquid crystal display panel 11. Since the pattern of the corrected display data 35B is distorted in exactly the opposite way to the distortion of the display image 30A, the two types of distortion cancel each other out. The display image 30C, as visually perceived by the driver, is therefore identical to the uncorrected display data 35A and exhibits no distortion. Description of the data required to correct the distortion of the display image 30

[0034] The method described under “Description of the Principle for Correcting the Distortion of the Display Image 30” eliminates the distortion from the display image 30; however, the types of distortion vary depending on the driver's line-of-sight height, so that the distortion is less likely to be eliminated with just a single correction pattern. To correctly correct the distortion of the display image 30 caused by a difference in the height of the eye area ER, different correction patterns must be prepared according to the respective segments based on the height of the eye area ER. In one embodiment, the height of the eye area ER is divided into one of five segments Hr1, Hr2, Hr3, Hr4, and Hr5, and five types of correction patterns are prepared according to the respective segments.In the exemplary embodiment, the case with the segments in five stages is described; however, the number of segment stages in the present invention is not limited to five, but can be equal to or greater than two. In this case, the number of prepared correction patterns corresponds to the number of stages.

[0035] Taking into account the variations between the windshields WS due to the manufacturing process, the following four types of correction patterns are prepared to correct the uncorrected display data 35A and to generate corrected display data 35B. (A) A desired correction pattern without manufacturing variations (B) A correction pattern taking into account the distortion resulting from manufacturing variations (C) A correction pattern taking into account the rotation resulting from manufacturing variations. (D) A correction pattern taking into account a size difference resulting from manufacturing variations.

[0036] A database DB1 is located in the display control unit 16 and serves as a storage unit that stores 20 types of correction patterns as data ([five types of correction patterns (the altitude direction from Fig. 4) based on the segments according to the height of the eye area ER] x [four types of correction patterns (the width direction from Fig. 4) based on the manufacturing variations between the windshields WS]), as in Fig. Figure 4 shows that when using the DB1 database, a correction pattern record can be selected from the 20 types of correction patterns, based on the combination of a parameter Pw, which identifies the type of manufacturing variations between the windscreens WS, and a parameter Ph, which indicates a segment by height of the eye area ER. Description of an exemplary control system for the vehicle display device

[0037] Fig. Figure 5 shows the contents of a main control unit of the vehicle display device in the present embodiment. Fig. Figure 5 is a flowchart illustrating a process in which the display control unit 16 transforms coordinates on the display data shown on the liquid crystal display panel 11 to correct the distortion. Fig. 6A and Fig. Figure 6B illustrates the correspondence between the segments in the vertical direction of the eye box EB, the shapes of the correction patterns in image processing, and the shapes of the visually recognized display images.

[0038] When power is switched on, the display control unit 16 performs a predefined initialization at step S11. Specifically, the display control unit 16 establishes a communication line to retrieve various types of display information (such as vehicle speed) from other control units (not shown), such as an engine control unit (ECU), and to continuously update the information to the latest state. Furthermore, the display control unit 16 transmits a command so that a graphics processing unit (GPU), which acts as the control unit for drawing the content to be displayed on the screen of the liquid crystal display panel 11, can execute a predefined operation. The display control unit 16 reads the database DB1 for standard correction pattern data and transmits the data to an image processing unit, which transforms the coordinates in the GPU.

[0039] The display control unit 16 retrieves the parameter Pw, which relates to the manufacturing variations between the windshields WS, at step S12. The manufacturing variation parameter Pw can be assigned to the status of an operating switch (not shown) connected to the display control unit 16, or it can be stored as a variable data record in a specific non-volatile memory.

[0040] The manufacturing variation parameter Pw is adjusted to the optimal value based on the conditions of the windshield WS that is actually installed in the vehicle, at a location such as a vehicle production facility or a vehicle dealership.

[0041] In step S13, the display control unit 16 retrieves information about the projection direction Dr1 (see Fig. 6B) of the display light from, for example, a sensor (not shown) connected to the projection direction change mechanism 15. In other words, the display control unit 16 determines the projection direction DR1, which changes with a change in the tilt angle of the aspherical mirror 13. If the display control unit 16 detects a change in the projection direction Dr1 at step S14 (Yes at step S14), the process continues with the next processing step at S15. If the display control unit 16 does not detect a change in the projection direction Dr1 at step S14 (No at step S14), the process returns to processing step S13.

[0042] The projection direction Dr1 changes in accordance with a change in the vertical direction of the eyebox EB. At step S15, the projection direction Dr1 is compared to a set of threshold values ​​to determine which segment from segments Hr1, Hr2, Hr3, Hr4, and Hr5 in the vertical direction of the eyebox EB the projection direction Dr1 belongs to. The result is defined as the vertical parameter Ph. If a change in the vertical parameter Ph compared to the previous result is detected at step S16 (Yes at step S16), the process continues with the next processing step at S17. If it is determined at step S16 that the vertical parameter Ph has not changed compared to the previous result (No at step S16), the process returns to the processing step at S13. As in Fig. As shown in 6A, the position of the eye box EB in the vertical direction decreases sequentially in the order of segments Hr1, Hr2, Hr3, Hr4 and Hr5.

[0043] In step S17, the display control unit 16 retrieves a correction pattern data set from database DB1 according to the two parameters Pw and Ph described above. For example, if the manufacturing variation parameter Pw is "B" and the altitude parameter Ph is "3", the display control unit 16 selects correction pattern data DTx, as shown in Fig. 4 shown.

[0044] In step S18, the display control unit 16 updates the correction pattern data used for coordinate transformation by the image processing unit in the graphics processor GP to the correction pattern data last selected in step S17.

[0045] If the control that is in Fig. 2 is shown, and is carried out as described in Fig. 6A and Fig. As shown in Figure 6B, when there is a change between the segments in the vertical direction of the eyepiece EB, the correction pattern is automatically changed to a pattern corresponding to the segment. The display image 30 is therefore generated so that it can be visually recognized without distortion at any height. The distortion resulting from manufacturing variations between the windshields WS can be modified more precisely by separately selecting the manufacturing variation parameter Pw for each individual windshield WS. With this configuration, the driver does not need to perform any special operations on the distortion of the display image 30, which improves performance. Furthermore, the manufacturing variation parameter Pw only needs to be selected from a variety of predefined patterns, making adjustment effortless. Deformation possibilities

[0046] HUD Unit 10, which is located in Fig. 1 and Fig. As shown in Figure 2, an image is projected using the aspherical mirror 13, which is located in the center of the optical path; however, the HUD unit 10 can also be configured without the aspherical mirror 13. In the case where the aspherical mirror 13 is not used, the projection direction of an image can be changed in a manner corresponding to a change in the vertical direction of the eyepiece EB, for example, by adjusting the tilt angle of the HUD unit 10 as a whole or by adjusting the position of the HUD unit 10 in the longitudinal direction.

[0047] Furthermore, HUD unit 10, which is located in Fig. 1 and Fig.As shown in Figure 2, the projection direction Dr1, based on the tilt angle of the aspherical mirror 13 located in the center of the optical path, determines which segment from segments Hr1, Hr2, Hr3, Hr4, and Hr5 the projection direction Dr1 belongs to and changes the correction pattern accordingly; however, another type of control can also be used. For example, a method can be applied that uses the correspondence between the image projection direction of the HUD unit 10 and the actual position (height) of the driver's eyes, determines the position of the driver's eyes with a camera, and changes the correction pattern based on the actual eye level. In the case where an operating switch or the like is used to adjust the projection direction based on the actual eye level, the correction pattern can be changed according to the operating state of the switch.With each control mode, the direction in which an image is projected from the HUD unit 10 is ultimately changed according to the height of the eye box EB, and the correction pattern is automatically changed accordingly.

[0048] As described above, in the vehicle display device according to the present embodiment, the correction pattern is automatically changed when the projection direction of a projection direction change mechanism is adjusted due to a change in the driver's eye level. Even if the driver's eye level changes due to a change in posture or the like, this configuration automatically corrects the distortion in the visually perceived image without requiring any operator action from the driver. Consequently, this configuration improves the functional performance in correcting distortion generated in a display image visually perceived by a driver.

[0049] In the vehicle display device according to the present embodiment, a correction pattern is selected based on the segment corresponding to a driver's eye level, and the distortion caused in a visually detected image is automatically corrected. This approach has advantageous effects on the correction of distortion caused in a display image through simple configuration and can reduce the amount of correction pattern data required for the correction.

[0050] Even if distortion is caused in the vehicle display device according to the present embodiment due to variations between windscreens, such as differences in shape and size that arise during the manufacturing processes, the display image can be made less distorted by selecting the optimal correction pattern from a variety of correction patterns. Reference symbol list 10 HUD units 11 Liquid Crystal Display Panel 12 Rear lights 13 aspherical mirrors 14 Irradiation area 15 Projection direction change mechanism 16 Display control unit 30 Display image 35A uncorrected display data 35B corrected display data DB1 Database EB Eyebox ER eye area GP graphics processor WS Windscreen

Claims

[1] Vehicle display device (10) comprising: a projection direction changing mechanism (15) configured to adjust a light projection direction in which display light containing a specific image is emitted; and a display control unit (16) for changing one of a plurality of correction patterns for correcting a shape of the image based on a projection direction adjusted by the projection direction changing mechanism (15), and for correcting the shape of the image based on the correction pattern; wherein the the display light containing the shape of the image corrected by the display control unit (16) is emitted and directed onto a windshield (WS) so that the display light reflected on a surface of the windshield (WS) is visually recognized, wherein the display control unit (16) has a plurality of correction patterns corresponding to changes in the image according to the projection direction of the projection direction changing mechanism (15), selects a correction pattern from the correction patterns according to a segment corresponding to an eye height (ER) of a driver specified based on the projection direction set by the projection direction changing mechanism (15), and corrects the shape of the image based on the correction pattern, and wherein the display control unit (16) has a plurality of types of the correction patterns corresponding to a change in the image occurring due to variations in a shape and a size of the windshield (WS) based on a manufacturing variation parameter (Pw) indicating the type of manufacturing variation between the windshields (WS), the manufacturing variation parameter (Pw) being associated with the status of an operation switch, and corrects the shape of the image based on the correction patterns specified from the plurality of types.

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