SYSTEM FOR CALIBRINGING A WAVE GUIDE-BASED HOLOGRAPHIC HEAD-UP DISPLAY

Abstract

System (10) for calibrating a waveguide-based holographic head-up display (12) that projects images onto a windshield (16) of a vehicle (14), the system (10) comprising: a light-scattering panel (24) positioned at the center (52) of an eye ellipse (54) to reflect the images projected by the waveguide-based holographic head-up display (12), wherein an eye frame (58) of the waveguide-based holographic head-up display (12) is positioned at the center (52) of an eye ellipse (54) and wherein the eye frame (58) is divided into a plurality of unit exit pupils (44); a camera (22) positioned to capture the images reflected by the light-scattering panel (24); and one or more controllers (20) in electronic communication with the waveguide-based holographic head-up display (12) and the camera (22), wherein the one or more controllers (20) are configured to execute instructions to: to instruct the waveguide-based holographic head-up display (12) to generate a calibration graphic (60) on the windscreen (16) of the vehicle (12), wherein the calibration graphic (60) contains a plurality of individual calibration patterns (62), each corresponding to one of the plurality of unit exit pupils (44) of the eye frame (58); to receive image data from the camera (22), wherein the image data captures the calibration graph (60) reflected on the light-scattering panel (24), and wherein the calibration graph (60) reflected on the light-scattering panel (24) contains a plurality of distorted individual calibration patterns (62); to correct distortions in each of the multitude of distorted individual calibration patterns (62) of the calibration graph (60) in order to generate a multitude of corrected individual calibration patterns (70); and to determine a distortion map (100) based on the multitude of corrected individual calibration patterns (80).

Description

[0001] The present disclosure relates to a system for calibrating a waveguide-based holographic head-up display.

[0002] A head-up display (HUD) projects information such as vehicle speed and navigation instructions directly onto the windshield of a vehicle in the driver's front field of vision. This allows the driver to access information without taking their eyes off the road. In some cases, head-up displays can be integrated with augmented reality displays, which project images onto the windshield to enhance the driver's view of the area outside the vehicle and require precise alignment of these images relative to the driver.

[0003] After the head-up display is installed in the vehicle at a final assembly plant, a line-end calibration is performed to compensate for distortions caused by variations in the windshield. During line-end calibration, a distortion map, also known as a distortion compensation map, is calculated. The distortion map provides a shaped or pre-distorted image that accounts for the windshield's shape variations, and this pre-distorted image is then projected onto the windshield. A camera mounted on a robotic arm may be used for line-end calibration at the final assembly plant. During calibration, the robotic arm moves the camera to different positions within the eye ellipse of the head-up display located inside the vehicle to capture images projected from the head-up display onto the windshield.The distortion map is calculated to compensate for image artifacts at different positions within the eye's ellipse. However, adjusting the camera to different angles using the robot arm requires a relatively long cycle time. Such a relatively long cycle time can be difficult to accommodate in some cases, especially when time is limited on the assembly line.

[0004] Although current approaches to calibrating a head-up display serve their purpose, there is a need for an improved system to calibrate a head-up display in a shorter time.

[0005] US 2021 / 0 157 135 A1 describes a device and method for acquiring and correcting HUD images for a vehicle. The device comprises a HUD patch defined on a reflective surface of the vehicle's windshield, a virtual image generator for projecting images within the HUD patch, and an array of virtual image sensors located within a HUD eyebox area of ​​the vehicle and having a field of view encompassing the HUD patch. A control unit is configured to control the projection of a predetermined test image within the HUD field, receive a HUD field image from the virtual image sensor assembly, determine a compensation function based on the predetermined test image and the HUD field image, and provide the compensation function to the virtual image generator for application to raw images prior to projection.

[0006] DE 10 2018 001 969 A1 describes a method for calibrating a contact-analog head-up display of a vehicle in a workshop, in which a warping matrix and parameters of a virtual camera are determined. In this method, which enables reliable calibration of the head-up display even in a workshop, 2D / 3D correspondences between a virtual image and vehicle sensors are established before determining the warping matrix and the parameters of the virtual camera.

[0007] DE 10 2014 013 221 A1 describes a device for calibrating a vehicle's image display unit. The device comprises a projection unit belonging to the image display unit for projecting images onto a projection screen in the field of vision of a vehicle occupant and a headrest arranged on a vehicle seat. The projection unit can project a test pattern directly onto a surface of the headrest, wherein at least one detection unit is provided for detecting the test pattern and wherein an evaluation unit determines any deviation of the detected test pattern from a target pattern. Furthermore, a method for calibrating a vehicle's image display unit is disclosed, wherein virtual images are projected onto a projection screen in the field of vision of a vehicle occupant by means of a projection unit belonging to the image display unit.The projection unit can project a test pattern directly onto a surface of the headrest, the test pattern is captured by at least one detection unit, and the captured test pattern is compared with a target pattern by means of an evaluation unit.

[0008] DE 10 2017 100 676 A1 describes a method for calibrating a head-up display of a motor vehicle. The method comprises: placing a calibration object with a predefined reference geometry into a head-up area of ​​a beam path, along which, in a normal operating mode of the head-up display, optical information generated by a display unit of the head-up display is projected into the head-up area and thus to a viewer; capturing infrared radiation reflected by the calibration object by an infrared camera of the head-up display arranged in a beam path of the infrared radiation behind a cold light mirror of the head-up display; comparing a radiation pattern, which is given by the spatial distribution of the radiation intensity of the infrared radiation, with a stored reference pattern, which is assigned to the predefined reference geometry, by a computing unit of the head-up display;Calculating calibration information based on a result of comparison by the computing device; and calibrating the display device using the calibration information to improve the calibration of a motor vehicle's head-up display.

[0009] The object of the invention can be considered to be to provide a system for improving the calibration of a head-up display.

[0010] The invention relates to a system for calibrating a waveguide-based holographic head-up display that projects images onto a vehicle's windshield. The system comprises a light-diffusing panel positioned at the center of an ellipse to reflect the images projected by the waveguide-based holographic head-up display. The eye frame of the waveguide-based holographic head-up display is positioned at the center of this ellipse and is divided into a plurality of unit exit pupils. The system also includes a camera positioned to capture the images reflected by the light-diffusing panel. The system further includes one or more controllers that communicate electronically with the waveguide-based holographic head-up display and the camera.The one or more controllers are configured to execute instructions to direct the waveguide-based holographic head-up display to generate a calibration graphic on the vehicle's windshield, wherein the calibration graphic contains a plurality of individual calibration patterns, each corresponding to one of the plurality of unit exit pupils of the eye frame. The one or more controllers execute instructions to receive image data from the camera, wherein the image data captures the calibration graphic reflected on the light-scattering panel, and wherein the calibration graphic reflected on the light-scattering panel contains a plurality of distorted individual calibration patterns.The one or more controllers execute instructions to correct distortions in each of the multitude of distorted individual calibration patterns of the calibration graph, in order to generate multiple corrected individual calibration patterns. The one or more controllers determine a distortion map based on the multitude of corrected individual calibration patterns.

[0011] In one embodiment, at least one reference alignment mark is arranged along a light-scattering surface of the light-scattering panel.

[0012] In one embodiment, the light-scattering panel is positioned in place by aligning the reference alignment mark of the light-scattering surface relative to a center of the eye ellipse.

[0013] In one embodiment, one or more controllers are configured to execute instructions to determine a misalignment of the calibration graph relative to a center of the eye ellipse.

[0014] In one embodiment, the one or more controllers are configured to execute instructions to direct the waveguide-based holographic head-up display to align the calibration graphic with the center of the eye ellipse, wherein, once the calibration graphic is aligned with the center of the eye ellipse, the center of each distorted individual calibration pattern of the calibration graphic is aligned with the center of a corresponding corrected individual calibration pattern.

[0015] In one embodiment, the one or more controllers are to execute instructions to correct distortions in a remaining part of each of the plurality of distorted individual calibration patterns of the calibration graph in response to the determination that the center of each of a plurality of distorted individual calibration patterns is aligned with the center of the corresponding corrected individual calibration pattern.

[0016] In one embodiment, correcting the distortions in the remaining part of the distorted individual calibration pattern comprises aligning a remaining part of a plurality of alignment marks that are part of the distorted individual calibration pattern with a plurality of alignment marks that are part of the corresponding corrected individual calibration pattern.

[0017] In one embodiment, the one or more controllers are configured to execute instructions to determine a positional difference between each of the plurality of alignment markers that are part of the distorted individual calibration pattern and each of the alignment markers that are part of the corresponding corrected individual calibration pattern.

[0018] In one embodiment, the distortion map contains a plurality of individual unit exit pupil distortion maps, each corresponding to one of the unit exit pupils of the eye ellipse.

[0019] In one embodiment, each individual unit exit pupil distortion map contains a plurality of coordinates, each corresponding to an alignment marker that is part of the individual calibration pattern.

[0020] In one application, the system according to the invention is used in a vehicle. In another application, a method for calibrating a waveguide-based holographic head-up display is disclosed, in which the system according to the invention is used to project images onto a vehicle's windshield. The method comprises instructing the waveguide-based holographic head-up display to generate a calibration graphic on the vehicle's windshield by means of one or more controllers, wherein the calibration graphic comprises a plurality of individual calibration patterns, each corresponding to one of the plurality of unit exit pupils of an eye frame, and wherein the eye frame of the waveguide-based holographic head-up display is positioned at the center of an eye ellipse of the light-scattering panel.The method also includes receiving image data from a camera by one or more controllers, wherein the image data captures the calibration graph reflected on a light-scattering panel, and wherein the calibration graph reflected on the light-scattering panel contains a plurality of distorted individual calibration patterns, and wherein the light-scattering panel is located at the center of the eye ellipse. The method includes correcting distortions in each of the plurality of distorted individual calibration patterns of the calibration graph to generate a plurality of corrected individual calibration patterns. The method includes determining a distortion map based on the plurality of corrected individual calibration patterns by the one or more controllers.

[0021] In one embodiment, the method includes determining a misalignment of the calibration graph relative to a center of the eye ellipse.

[0022] In a further embodiment, the method comprises instructing the waveguide-based holographic head-up display to align the calibration graphic to the center of the eye ellipse, wherein, once the calibration graphic is aligned to the center of the eye ellipse, a center of each distorted individual calibration pattern of the calibration graphic is aligned to a center of a corresponding corrected individual calibration pattern.

[0023] In a further embodiment, the method comprises, in response to the finding that the center of each of several distorted individual calibration patterns is aligned with the center of the corresponding corrected individual calibration pattern, correcting distortions in a remaining part of each of the several distorted individual calibration patterns of the calibration graph.

[0024] In a further embodiment, the method comprises correcting the distortions in the remaining part of the distorted individual calibration pattern by aligning a remaining part of a plurality of alignment marks that are part of the distorted individual calibration pattern with a plurality of alignment marks that are part of the corresponding corrected individual calibration pattern.

[0025] In a further embodiment, the method comprises determining a position difference between each of the plurality of alignment marks that are part of the distorted individual calibration pattern and each of the alignment marks that are part of the corresponding corrected individual calibration pattern.

[0026] The drawings described here are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Fig. Figure 1 is a schematic diagram of the disclosed system for calibrating a waveguide-based holographic head-up display system, which includes a camera and a light-scattering panel; Fig. Figure 2 is a front view of the light-scattering panel, an eye ellipse and an eye frame with a plurality of unit exit pupils; Fig. Figure 3A shows an exemplary calibration graph with a variety of individual calibration patterns, each corresponding to one of the unit exit pupils of the eye frame; Fig. Figure 3B shows an alternative embodiment of an individual calibration pattern; Fig. Figure 4 shows an example of a distorted individual calibration pattern superimposed on a corrected calibration pattern; Fig. Figure 5 is an exemplary representation of a distortion map containing a variety of individual unit exit pupil distortion maps; Fig. 6 is a representation of one of the in Fig. 5 unit exit pupil distortion maps shown; and Fig. Figure 7 is a process flow diagram showing a procedure for calibrating a waveguide-based holographic head-up display system.

[0027] The following description is merely exemplary and is not intended to limit the present disclosure, application or use.

[0028] In Fig. Figure 1 shows an exemplary system 10 for calibrating a waveguide-based holographic head-up display 12 for a vehicle 14. The waveguide-based holographic head-up display 12 projects virtual images onto a windshield 16 of the vehicle 14. The vehicle 14 can be any type of vehicle, such as a sedan, truck, SUV, van, or motorhome, without limitation. The system 10 comprises the waveguide-based holographic head-up display 12, one or more controllers 20, a camera 22, and a light-diffusing panel 24. The light-diffusing panel 24 defines a light-diffusing surface 26. The light-diffusing panel 24 is attached by a bracket (not shown) during the calibration of the waveguide-based holographic head-up display 12 and removed after the calibration is complete.The one or more controllers 20 are in electronic communication with the waveguide-based holographic head-up display 12 and the camera 22. As explained below, the system 10 calibrates the waveguide-based holographic head-up display 12 by calculating a distortion map 100 (see . Fig. 5) takes into account the variations in the shape of the windshield 16 of the vehicle 14. In one embodiment, the calibration of the waveguide-based holographic head-up display 12 is performed during line-end calibration in a final assembly plant. However, it is understood that the calibration can also be performed in a car dealership.

[0029] The waveguide-based holographic head-up display 12 comprises a holographic projector 30 and a waveguide 32, wherein the holographic projector 30 includes a laser light source 34 and a spatial light modulator 36. The one or more controllers 20 are in electronic communication with the holographic projector 30. The spatial light modulator 36 is arranged between the laser light source 34 and the waveguide 32. The spatial light modulator 36 is configured to receive laser light from the laser light source 34 and project a holographic image into an exit pupil replicator 38 of the waveguide 32, the holographic image propagating within the exit pupil replicator 38 and being extracted multiple times before being projected as a virtual image onto the windshield 16.The one or more controllers 20 instruct the holographic projector 30 of the waveguide-based holographic head-up display 12 to generate the virtual images that are projected onto the windscreen 16.

[0030] As already mentioned, during the calibration of the waveguide-based holographic head-up display 12, a (not shown) bracket is used to attach the light-scattering panel 24 in an interior 50 of the vehicle 14. Fig. Figure 2 is a front view of the light-diffusing panel 24. As in Fig. As can be seen in Figure 2, at least one reference alignment mark 42 is arranged along the light-diffusing surface 26 of the light-diffusing panel 24. In the Fig. In the example shown, at least one reference alignment mark 42 is a crosshatch pattern; however, it should be understood that other types of reference alignment marks can also be used. The light-scattering panel 24 is positioned by the (not shown) bracket by aligning the reference alignment mark 42 of the light-scattering surface 26 relative to a center 52 of an eye ellipse 54 of the waveguide-based holographic head-up display 12. In other words, the light-scattering panel 24 is aligned in a yz-plane of a vehicle coordinate system such that it intersects the center 52 of the eye ellipse 54.

[0031] As in Fig. As shown in Figure 1, the camera 22 is located in the interior cabin 50 of the vehicle 14 and is positioned to capture image data representing the virtual images reflected by the light-scattering surface 26 of the light-scattering panel 24 during the calibration of the waveguide-based holographic head-up display 12. When the light-scattering panel 24 is removed after the calibration of the waveguide-based holographic head-up display 12, and a driver is now seated in the vehicle 14, the camera 22 captures image data showing the position of the driver's head and the position of the driver's left and right eyes. In a non-restrictive embodiment, the camera 22 is part of a driver monitoring system for the vehicle 14.

[0032] As in the Fig. 1 and Fig. As shown in Figure 2, the eye ellipse 54 comprises two elliptical volumes 40, each representing a potential position of either the right or left eye of a driver of the vehicle 14 and determined based on statistical data. An eye frame 58 of the waveguide-based holographic head-up display 12 is aligned with the center 52 of the eye ellipse 54. If the eye frame 58 is not aligned with the center 52 of the eye frame 58, the virtual image projected onto the windshield 16 by the waveguide-based holographic head-up display 12 may not be fully visible or may appear incorrectly positioned. The eye frame 58 represents a volume in the interior 50 of the vehicle 14, within which the driver of the vehicle 14 can see the entire virtual image projected by the waveguide-based holographic head-up display 12. The eye frame 58 is subdivided into a multitude of unit exit pupils 44.

[0033] As in Fig. As shown in Figure 2, the reference alignment mark 42 is arranged along the light-scattering surface 26 of the light-scattering panel 24. The reference alignment mark 42 positions the light-scattering panel 24 such that each of the unit exit pupils 44 of the eye frame 58 is arranged along the light-scattering surface 26. In other words, the reference alignment mark 42 ensures that each individual unit exit pupil 44 of the eye frame 58 is arranged along the light-scattering surface 26 of the light-scattering panel 24.

[0034] It should be understood that the eye ellipse 54 represents only one possible position of a driver's eyes. Fig. Figure 2, however, shows an actual position A of the driver's right eye and an actual position B of the driver's left eye within a respective elliptical volume 40 of the eye ellipse 54. Each of the driver's eyes is located within a different unit exit pupil 44 of the eye frame 58. In particular, in the Fig. In the example shown, the unit exit pupils 44 are divided into nine rows and seven columns, and the actual position A of the right eye is in the unit exit pupil 44 located in the fourth row and sixth column, and the actual position B of the left eye is in the unit exit pupil 44 located in the second row and first column.

[0035] With reference to the Fig. 1 and Fig. 2 It becomes clear that, due to the different positions A and B of the driver's right and left eyes (i.e., the different unit exit pupils 44 of the eye frame 58), each eye sees a different distortion of the virtual image projected onto the windscreen 16 by the waveguide-based holographic head-up display 12. As explained below, the disclosed system 10 calibrates the waveguide-based holographic head-up display 12 by determining a distortion map 100, which uses individual unit exit pupil distortion maps 102 (in Fig. 5 to be seen) contains, each corresponding to one of the unit exit pupils 44 of the eye frame 58, wherein the distortion map 100 is stored in the memory of one or more controllers 20.

[0036] After the system 10 has calibrated the waveguide-based holographic head-up display 12 and the light-scattering panel 24 has been removed, a driver can be seated in the vehicle 14 with the driver's head positioned in the eye frame 58. The camera 22 can then detect the position of the driver's right and left eyes, and the one or more controllers 20 determine the unit exit pupils 44 corresponding to the actual positions A, B of the driver's right and left eyes. The controller 20 can then generate the individual unit exit pupil distortion maps 102 ( Fig. 5) Selecting unit exit pupils 44 that correspond to the actual positions A, B of the driver's right and left eyes. If the driver moves his head and the actual positions A, B of the driver's right and left eyes change, different individual unit exit pupil distortion maps 102 can also be selected to compensate for the changed position of the driver's head.

[0037] Fig. Figure 3A shows an example calibration graph 60 generated by the waveguide-based holographic head-up display 12 during calibration. As shown in Fig. As can be seen in Figure 3A, the calibration graph 60 contains a variety of individual calibration patterns 62, each associated with one of the in Fig. The unit exit pupils 44 of the eye frame 58 shown in Figures 1-2 correspond to the individual calibration pattern 62, which comprises a symmetrical arrangement of alignment markers 66 arranged in corresponding rows and columns, the size and spacing of the individual alignment markers 66 being stored in the memory of one or more controllers 20. Fig. In the non-restrictive embodiment shown in Figure 3A, the individual alignment markings 66 are represented as dots. However, it should be noted that Fig. 3A is merely an example, and the calibration pattern 62 can include any type of pattern or graphic with a known size and distance for calibrating and removing distortions from an image. Although Fig. While 3A shows a symmetrical arrangement of points, calibration pattern 62 can also contain a non-symmetrical pattern. In the Fig. In the embodiment shown in Figure 3B, the individual calibration pattern 62 includes, for example, an asymmetric arrangement of alignment marks 66. Some examples of alternative individual calibration patterns 62 are, among others, a checkerboard pattern and a grid pattern.

[0038] Referring to the Fig. 1 and Fig. 2. Before calibrating the waveguide-based holographic head-up display 12, the light-scattering panel 24 is positioned in place by aligning the reference alignment mark 42 of the light-scattering surface 26 with the center 52 of the eye ellipse 54. With reference to the Fig. 1 and Fig. 3A The one or more controllers 20 can receive a request indicating that the waveguide-based holographic head-up display 12 should be calibrated. In response to receiving the request, the one or more controllers 20 instruct the waveguide-based holographic head-up display 12 to generate the calibration graphic 60 on the windshield 16 of the vehicle 14. The calibration graphic 60 is reflected from the light-scattering surface 26 of the light-scattering panel 24, and the camera 22 captures image data representing the calibration graphic 60 reflected from the light-scattering surface 26 of the light-scattering panel 24. The one or more controllers 20 receive the image data from the camera 22, representing the virtual images reflected from the light-scattering surface 26 of the light-scattering panel 24.

[0039] It is understood that the calibration graph 60 reflected by the light-scattering panel 24 contains distortions caused by changes in the shape of the windshield 16 of the vehicle 14. With reference to the Fig. 1 and Fig. 4 contains the calibration graph 60 reflected by the light-scattering panel 24 ( Fig. 3A) a variety of distorted individual calibration patterns 68, wherein Fig. Figure 4 shows an exemplary distorted individual calibration pattern 68 superimposed on a corrected calibration pattern 70, wherein the corrected calibration pattern 70 is identical to the individual calibration pattern 62 that corresponds to one of the unit exit pupils 44 of the eye frame 58 (as seen in Figure 4). Fig. 3A).

[0040] As explained below, the one or more controllers 20 correct distortions in each of the several distorted individual calibration patterns 68 of the calibration graph 60 to produce the corrected individual calibration patterns 70. The one or more controllers 20 then determine the distortion map 100 ( Fig. 5) based on the multiple corrected calibration patterns 70.

[0041] With reference to the Fig. 1, Fig. 2 and Fig. 3A determines the one or more controllers 20 first a misalignment of the calibration graph 60 ( Fig. 3A) in relation to the center 52 of the eye ellipse 54 ( Fig. 2) The one or more controllers 20 then instruct the waveguide-based holographic head-up display 12 to align the calibration graphic 60 with the center 52 of the eye ellipse 54 based on the misalignment. As in Fig. As can be seen in Figure 4, once the calibration graph 60 is aligned with the center 52 of the eye ellipse 54, the center 74 of each distorted individual calibration pattern 68 is now aligned with the center 78 of a corresponding corrected individual calibration pattern 70. In the Fig. In the example shown, the center 74 of the distorted individual calibration pattern 68 contains a central alignment mark 66A which is aligned with a central alignment mark 76A of the corresponding corrected individual calibration pattern 70.

[0042] In response to the finding that the center point 74 of each distorted individual calibration pattern 68 is aligned with the center point 78 of the corrected individual calibration pattern 70, the one or more controls 20 correct the distortions in a remaining portion of each of the multiple distorted individual calibration patterns 68 of the calibration graph 60. In the Fig. In the example shown in Figure 4, the remaining portion of the distorted individual calibration pattern 68 comprises each alignment mark 66 except for the central alignment mark 66A. Correcting the distortions in the remaining portion of the distorted individual calibration pattern 68 involves aligning the alignment marks 66 that are part of the distorted individual calibration pattern 68 with the alignment marks 76 of the corresponding corrected individual calibration pattern 70. Once the distortions from the remaining portion of each of the multiple distorted individual calibration patterns 68 of the calibration graph 60 ( Fig. 3A) are removed, the one or more controllers 20 can then determine a position difference between each of the alignment marks 66 that are part of the distorted individual calibration pattern 68 and each of the alignment marks 76 that are part of the corrected individual calibration pattern 70.

[0043] As from Fig. As can be seen from Figure 5, the distortion map contains 100 individual unit exit pupil distortion maps 102, each corresponding to one of the unit exit pupils 44 of the eye frame 58 (see Figure 5). Fig. 2). Fig. Figure 6 shows an exemplary individual unit exit pupil distortion map 102, corresponding to one of the unit exit pupils 44 of the eye frame 58. The individual unit exit pupil distortion map 102 contains a plurality of coordinates 104, each corresponding to one of the alignment markers 66 that are part of the individual calibration patterns 62. Each coordinate 104 comprises an x-coordinate and a y-coordinate, the x-coordinate and y-coordinate representing the positional difference between an alignment marker 66 that is part of the distorted individual calibration pattern 68 and an alignment marker 76 that is part of the corresponding corrected individual calibration pattern 70. Fig. 4).

[0044] Fig. Figure 7 is a process flow diagram showing a procedure 200 for calibrating the waveguide-based holographic head-up display 12. Referring to the Fig. 1, Fig. 2 and Fig. 7. Procedure 200 can begin in block 202. In block 202, the light-scattering panel 24 is positioned by the (not shown) holder by aligning the reference alignment mark 42 of the light-scattering surface 26 relative to the center 52 of the eye ellipse 54. Procedure 200 can then be continued with block 204.

[0045] In block 204, the one or more controllers 20 receive a request indicating that the waveguide-based holographic head-up display 12 should be calibrated. The procedure 200 can then proceed to block 206.

[0046] In block 206, the one or more controllers 20, in response to receiving the request, instruct the waveguide-based holographic head-up display 12, the calibration graphic 60 ( Fig. 3A) on the windscreen 16 of the vehicle 14. As already mentioned, the calibration graph 60 reflected by the light-scattering panel 24 contains a variety of distorted individual calibration patterns 68, which are in Fig. 4 are shown. Procedure 200 can then proceed to block 208.

[0047] In block 208, the one or more controllers receive 20 image data from camera 22, where the image data is the calibration graph 60 ( Fig. 3A) capture, which is reflected on the light-scattering panel 24. The calibration graph 60, which is reflected on the light-scattering panel 24, contains a variety of distorted individual calibration patterns 68 ( Fig. 4) Procedure 200 can then proceed to block 210.

[0048] In block 210, the one or more controllers correct 20 distortions in each of the several distorted individual calibration patterns 68 ( Fig. 4) of the calibration graph 60 to create the multiple corrected individual calibration patterns 70.

[0049] As mentioned above, the correction of the distortions first involves determining the misalignment of the calibration graph 60 ( Fig. 3A) relative to the center 52 of the eye ellipse 54 ( Fig. 2) and then the instruction to the waveguide-based holographic head-up display 12 to align the calibration graph 60 based on the misalignment to the center 52 of the eye ellipse 54. As in Fig. As can be seen in Figure 4, the center 74 of the distorted individual calibration pattern 68 contains the central alignment mark 66A, which is aligned with the central alignment mark 76A of the corresponding corrected individual calibration pattern 70. In response to the finding that the center 74 of each distorted individual calibration pattern 68 is aligned with the center 78 of the corrected individual calibration pattern 70, the one or more controls 20 correct the distortions in the remaining portion of each of the multiple distorted individual calibration patterns 68 of the calibration graph 60. The procedure 200 can then proceed to block 212.

[0050] In block 212, the one or more controllers 20 determine the distortion card 100 ( Fig. 5) based on the multiple corrected individual calibration patterns 70 ( Fig.4) The distortion map 100 is stored in the memory of one or more controllers 20. The procedure 200 can then be terminated.

[0051] The waveguide-based holographic head-up display calibration system depicted in the figures offers several technical effects and advantages. In particular, the disclosure provides a relatively fast, cost-effective approach to determining a distortion map for each unit exit pupil of the eye frame. Compared to conventional approaches that perform line-end calibration to determine the distortion map, the disclosed system results in a reduced cycle time. The disclosed system also determines unique distortion maps, each corresponding to one of the multiple unit exit pupils of the eye frame. Thus, once a driver is inside the eye frame, the system can select the distortion maps that correspond to the unit exit pupils representing the actual positions of the driver's right and left eyes.

Claims

[1] System (10) for calibrating a waveguide-based holographic head-up display (12) that projects images onto a windshield (16) of a vehicle (14), the system (10) comprising: a light-scattering panel (24) positioned at the center (52) of an eye ellipse (54) to reflect the images projected by the waveguide-based holographic head-up display (12), wherein an eye frame (58) of the waveguide-based holographic head-up display (12) is positioned at the center (52) of an eye ellipse (54) and wherein the eye frame (58) is divided into a plurality of unit exit pupils (44); a camera (22) positioned to capture the images reflected by the light-scattering panel (24); and one or more controllers (20) in electronic communication with the waveguide-based holographic head-up display (12) and the camera (22), wherein the one or more controllers (20) are configured to execute instructions to: to instruct the waveguide-based holographic head-up display (12) to generate a calibration graphic (60) on the windscreen (16) of the vehicle (12), wherein the calibration graphic (60) contains a plurality of individual calibration patterns (62), each corresponding to one of the plurality of unit exit pupils (44) of the eye frame (58); to receive image data from the camera (22), wherein the image data captures the calibration graph (60) reflected on the light-scattering panel (24), and wherein the calibration graph (60) reflected on the light-scattering panel (24) contains a plurality of distorted individual calibration patterns (62); to correct distortions in each of the multitude of distorted individual calibration patterns (62) of the calibration graph (60) in order to generate a multitude of corrected individual calibration patterns (70); and to determine a distortion map (100) based on the multitude of corrected individual calibration patterns (80). [2] System (10) according to claim 1, wherein at least one reference alignment mark (42) is arranged along a light-scattering surface (26) of the light-scattering panel (24). [3] System (10) according to claim 2, wherein the light-scattering panel (24) is positioned in place by aligning the reference alignment mark (42) of the light-scattering surface (26) relative to a center (52) of the eye ellipse (54). [4] System (10) according to claim 1, wherein the one or more controllers (20) are configured to execute instructions to: to determine a misalignment of the calibration graph (60) relative to the center (52) of the eye ellipse (54). [5] System (10) according to claim 4, wherein the one or more controllers (20) are configured to execute instructions to: to instruct the waveguide-based holographic head-up display (12) to align the calibration graph (60) with the center (52) of the eye ellipse (54), wherein, once the calibration graph (60) is aligned with the center (52) of the eye ellipse (54), a center (74) of each distorted individual calibration pattern (68) of the calibration graph (60) is aligned with a center (78) of a corresponding corrected individual calibration pattern (70). [6] System (10) according to claim 5, wherein the one or more controllers are configured to execute instructions to: in response to determining that the center (74) of each of a plurality of distorted individual calibration patterns (68) is aligned with the center (78) of the corresponding corrected individual calibration pattern (70), to correct distortions in a remaining part of each of the plurality of distorted individual calibration patterns (68) of the calibration graph (60). [7] System (10) according to claim 6, wherein correcting the distortions in the remaining part of the distorted individual calibration pattern (68) comprises aligning a remaining part of a plurality of alignment marks (66) that are part of the distorted individual calibration pattern (68) with a plurality of alignment marks (66) that are part of the corresponding corrected individual calibration pattern (70). [8] System (10) according to claim 7, wherein the one or more controllers (20) are configured to execute instructions to: to determine a position difference between each of the plurality of alignment markers (66) that are part of the distorted individual calibration pattern (68) and each of the alignment markers (66) that are part of the corresponding corrected individual calibration pattern (70). [9] System (10) according to claim 1, wherein the distortion map (100) comprises a plurality of individual unit exit pupil distortion maps (102), each corresponding to one of the unit exit pupils (44) of the eye frame (58). [10] System (10) according to claim 9, wherein each individual unit exit pupil distortion map (102) contains a plurality of coordinates (104) each corresponding to an alignment mark (66) that is part of the individual calibration pattern (62).

Images