Head-up display system with programmable free-form optics and motor vehicle with such a head-up display system

Abstract

A head-up display (HUD) system is calibrated via a method for use with a windshield having a predetermined curvature and tilt angle and includes a HUD projector, a programmable freeform optics (PFO) device, and a deflection mirror. The projector is configured to project an input image along a primary light transmission path. The PFO device is disposed in the primary light transmission path and reflects or transmits the input image along a secondary light transmission path as an output image. The deflection mirror, disposed in the secondary light transmission path, reflects the output image along a tertiary light transmission path as a HUD image. The PFO device is programmed to locally control a wavefront characteristic of the output image to compensate for the curvature and tilt angle when the HUD system displays the HUD image via a HUD panel.

Description

[0001] A head-up display (HUD) system can be used in a vehicle to project information near the driver's or operator's forward line of sight. Using a HUD system, the operator can view real-time vehicle information unobstructed by the types of information normally communicated through instrument cluster gauges or a center console screen. For example, a HUD system can display the vehicle's current speed and heading, or graphics such as lane markings, lane departure warnings, or obstacle detection alerts. Projecting this information into or near the operator's line of sight allows them to view the displayed information without taking their attention away from the road or other traffic conditions.

[0002] An onboard HUD system typically includes a projector integrated into the instrument panel that directs a light-based image onto a reflective deflecting mirror. The projected image is reflected by the deflecting mirror onto an aspherical mirror, which in turn directs the image onto a specific area of ​​the windshield. This specific area, referred to herein and in the technical literature as the HUD patch, may be a planar piece of reflective glass or plastic, or possibly a coated portion of the inner surface of the windshield. To the operator, the projected image may appear to float seamlessly in front of the windshield.

[0003] DE 11 2017 006 073 T5 discloses an imaging system that generates virtual images at different depths by using a light structuring device to provide independently configurable lens simulations with different focal lengths on different surface areas. DE 10 2022 106 738 A1 teaches a holographic display system that forms a complete field of view by using a spatial light modulator to generate subframes from coherent light and a scanner to selectively direct these onto a display surface.

[0004] One of the problems underlying the invention is to provide an improved head-up display system and a motor vehicle with an improved head-up display system.

[0005] This problem is solved by the subject matter according to claim 1 and the subject matter according to claim 8.

[0006] This disclosure discloses a head-up display (HUD) system for a vehicle, such as a motor vehicle, aircraft, spacecraft, rail vehicle / train, watercraft / boat, or other mobile system with a windshield. The HUD system of this disclosure includes, as part of its design, a programmable free-form optic (PFO) which is used to enable the use of the HUD system across a wide range of vehicle models, each with differently configured windshields.

[0007] As is well known in engineering, the surface curvature, tilt angle, and other geometries of an installed windshield tend to vary between vehicle models. The non-planar surface of an installed windshield often distorts or defocuses passing light and can cause further imaging errors or aberrations. The aspherical mirror mentioned above is typically used to correct such aberrations when light-based information is projected using a head-up display (HUD) system. However, aspherical mirrors are specifically tailored to the particular curvature and tilt angle of the installed windshield. Consequently, HUD systems are usually customized for use in vehicles of a specific make or model.The solutions presented here are intended to enable the use of a specific HUD system regardless of windscreen configuration across a wide range of vehicle models, thus addressing many of the manufacturing inefficiencies associated with the process of redesigning a HUD system.

[0008] The solutions described herein replace the aspherical mirror of a typical HUD system with the PFO device. The PFO device, in its various configurations, constitutes a controllable hardware element that facilitates calibration and enables local correction of the light transmission path between the PFO device and a downstream deflecting mirror. Among other associated advantages, the non-transient, computer-readable storage medium / memory of the PFO device is rewritable, thus enabling the use of the disclosed HUD system for a wide range of vehicle models, as mentioned above.

[0009] According to the invention, a HUD system for use with a windshield having a predetermined curvature and angle of inclination is disclosed. The HUD system comprises the HUD projector, the PFO device, and the deflecting mirror. The HUD projector is configured to project an input image along a primary light transmission path. The PFO device, positioned in the primary light transmission path, reflects or transmits the input image as an output image along a secondary light transmission path. The deflecting mirror is arranged in the secondary light transmission path and configured to reflect the output image along a tertiary light transmission path, with this reflected light forming a HUD image.The PFO device, as described herein, is programmed to locally control a wavefront characteristic of the output image to compensate for curvature and tilt angle when the HUD system displays the HUD image on a HUD field. The HUD system further includes a processor configured to maintain the optical profile of the PFO device during operation of the HUD system, ensuring that the optical profile does not deviate from a recorded baseline during the lifetime of the HUD system. The HUD field, in turn, may in some configurations be part of the HUD system, possibly including a HUD field located on an inner surface of the windshield.

[0010] The PFO device in one or more embodiments comprises a reflective element, such as a liquid crystal-based mirror, e.g., a liquid crystal-on-silicon (LCoS) mirror, or a piston-mode spatial light modulator comprising an array of individually controllable micromirrors. In other embodiments, the PFO device may include a transmissive element.

[0011] The processor is configured to maintain the optical profile of the PFO device during operation of the HUD system, so that the optical profile does not deviate from a recorded baseline during the lifetime of the HUD system.

[0012] This also discloses a motor vehicle. The motor vehicle comprises a vehicle body defining a vehicle interior, one or more road wheels connected to the vehicle body, a windshield, and a HUD system. The windshield is connected to the vehicle body and has a specific curvature and angle of inclination. The HUD system in this embodiment is used to display a HUD image within the vehicle interior and comprises a HUD projector configured to project an input image along a primary light transmission path, a HUD field located on or near the windshield, and a PFO device located in the primary light transmission path.

[0013] The PFO device in this embodiment reflects or transmits the input image along a secondary light transmission path using a stored optical profile as the output image. A deflecting mirror is also arranged in the secondary light transmission path, configured to reflect the output image along a tertiary light transmission path as the HUD image. The PFO device is programmed to locally control a wavefront characteristic of the output image to compensate for curvature and tilt when the HUD system displays the image over the HUD field. The vehicle further includes a processor configured to maintain the optical profile of the PFO device during operation of the HUD system, ensuring that the optical profile does not deviate from a recorded baseline during the lifetime of the HUD system.

[0014] Another aspect of the disclosure includes a method for calibrating a HUD system for use with a windshield having a predetermined curvature and angle of inclination. The method, according to an exemplary embodiment, comprises projecting an input test image along a primary light transmission path using a HUD projector of the HUD system. The method also includes reflecting or transmitting the input test image along a secondary light transmission path using a recorded optical profile via a PFO device positioned in the primary light transmission path as the output image.

[0015] Furthermore, the method includes reflecting the output image along a tertiary light transmission path using a deflecting mirror as the HUD image, and also determining, via a camera, a translational shift and displayed size of the test graphic with respect to a specific target location and target area on a HUD field of the HUD system. As part of the method, an optical profile is recorded in a non-transient, computer-readable storage medium (memory) of the PFO device, wherein, when executed, the optical profile eliminates the translational shift and adjusts or calibrates the target area. The method also includes executing the optical profile from the PFO device's memory during operation of the HUD system.

[0016] The method may include maintaining the optical profile of the PFO device during operation of the HUD system, so that the optical profile does not deviate from a recorded baseline during the lifetime of the HUD system.

[0017] Projecting the input test image along a primary light transmission path involves displaying the input test image on an inner surface of the windshield, with the HUD field possibly located on the inner surface of the windshield.

[0018] The above features and advantages, as well as further features and advantages of the present teaching, are readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the present teaching as defined in the attached claims, when considered in conjunction with the attached drawings.

[0019] The accompanying drawings, which are included in the description and form part of this description, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. Fig. Figure 1 illustrates a motor vehicle equipped with a head-up display (HUD) with a programmable free-form optics (PFO) device according to the present disclosure. Fig. Figure 2 illustrates the PFO device of Fig. 2 according to one possible embodiment. Fig. 3A, Fig. 3B, Fig. 3C and Fig. 3D illustrates non-restrictive, representative implementations of the in Fig. 2 PFO devices shown. Fig. Figure 4 is a flowchart that describes a calibration procedure for the HUD system of the Fig. 1 and Fig. 2 according to one embodiment describes

[0020] The accompanying drawings are not necessarily to scale and may present a simplified representation of various preferred features of the present disclosure as disclosed herein, including, for example, certain dimensions, orientations, locations or positions, and shapes. Details associated with such features are partly determined by the intended application and operating environment.

[0021] The components of the disclosed embodiments can be arranged in a multitude of configurations. Consequently, the following detailed description is not intended to limit the scope of the disclosure as claimed, but is merely representative of its possible embodiments. Furthermore, while numerous specific details are set forth in the following description to provide a comprehensive understanding of the various representative embodiments, some embodiments can be implemented in practice without some of the described details. To improve clarity, certain technical details understood or known from the prior art have also been omitted from the detailed description. Moreover, the disclosure can be implemented in practice, as illustrated and described herein, in the absence of an element not specifically disclosed herein.

[0022] If we now refer to the drawings, where the same reference numbers refer to the same features across the different views, we find Fig. Figure 1 represents a vehicle 10 with a vehicle body 12 defining a vehicle interior 15. A windshield 11 is connected to the vehicle body 12. The vehicle 10 can be, as shown, embodied as a motor vehicle, i.e., with a set of road wheels 14 and one or more (not shown) propulsion sources such as an internal combustion engine and / or an electric drive motor. In other configurations, the vehicle 10 can be designed as an aircraft, spacecraft, motorcycle, train / rail vehicle, boat / ship, etc. The present teaching is therefore not limited to the example of Fig. 1 limited. For the sake of clarity and consistency, vehicle 10 shall be referred to herein without restriction as motor vehicle 10.

[0023] Motor vehicle 10 of Fig. 1 comprises a head-up display (HUD) system 25, of which a non-restrictive embodiment is described in Fig. 2 is shown. In the illustrated implementation or design of Fig. 1 The HUD system 25 is configured to project information onto the windshield 11, or more specifically onto a HUD patch or field (HP) 250 located on or near the windshield 11. A driver or operator 18 in the non-restrictive embodiment of Fig. Figure 1 is shown in a forward-facing position on a driver's seat 16, with the operator 18 seated behind a steering wheel 17. The information projected onto the HUD field 250 is thus presented near or along a normal, forward-facing line of sight of the operator 18 for easy / undistracted viewing of the displayed information.

[0024] The design or structure of the HUD field 250 can vary depending on the specific design of the HUD system 25. For example, the HUD field 250 can be a coated part of the windshield 11 for a projection onto the windshield, or in possible embodiments, the HUD field 250 can be a pop-up screen, a combination screen, a fixed panel, or an augmented reality (AR) display. The latter AR version can be particularly useful for overlaying symbols, images, or other graphics onto the windshield 11 and onto a real-world view of the roadway visible to the operator 18.

[0025] Referring to Fig. Figure 2 illustrates the HUD system 25 according to a representative design. The HUD system 25 is, as considered herein, located near the (also in Fig. 1 shown) windshield 11 installed as for example under / behind a dashboard 26. In the non-restrictive implementation of Fig. 2 the operator 18 or a camera 37 is viewed during the calibration procedure 100 of Fig. 4 the HUD field 250 located on or near an inner surface of the windscreen 11. The three-dimensional (3D) volume within which the driver's eyes are located in order to correctly see information projected onto the HUD field 250 is referred to as eyebox 19. The eyebox 19 in Fig. 2 therefore limits an area in which the driver's eyes 18 can move while maintaining a clear view of the displayed information, i.e. without distortion or loss of field of view / image cut-off.

[0026] As is known in engineering, the windshield 11 on the motor vehicle 10 is the Fig. 1 with a corresponding curvature (arc) and a corresponding angle of inclination, i.e., the angle formed between the installed windshield 11 and a vertical line arranged perpendicular to a ground plane. The size and surface geometry of the windshield 11 give a vehicle make / model the desired degree of aerodynamic performance and rigidity and also increase or decrease the available headroom within the vehicle interior 15. Fig. 1. Thus, motor vehicles of 10 different makes or models are often equipped with windshields 11 with different curvatures and / or angles of inclination. As mentioned above, this reality complicates the reuse of typical hardware elements of HUD systems across vehicle platforms.

[0027] To mitigate the manufacturing problems associated with this lack of reusability, the HUD system 25 from Fig. 2 equipped with a device 35 with programmable freeform optics (PFO), which enables a manufacturer of the motor vehicle 10 ( Fig. 1) enables the optical properties of the HUD system 25 to be modified during calibration to achieve a desired optical performance. The use of the PFO device 35, as described below, allows for in-house calibration of the HUD system 25 for a specific windshield 11. The optical performance of the HUD system 25 is achieved via simple programming inputs, with an exemplary calibration approach shown below with reference to Fig. 4 is described.

[0028] In the illustrated implementation of Fig. The HUD system 25 comprises a HUD projector 30, the PFO device 35, and a deflecting mirror 32. The HUD projector 30 can be implemented as an array of light-emitting diodes (LEDs), a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, a quantum dot display, etc. The HUD projector 30 is thus designed as a light display that serves to generate light-based information, i.e., an input image 33, and project it along a primary light transmission path (P1) toward the PFO device (35). The PFO device 35 also includes, or is connected to, a controller (C) 50, as described below, and can be connected to an image generation unit or other device that serves to control the context of the generated information. The PFO device 35 then transmits a corrected output image 133 along a secondary image transmission path (P2).

[0029] The deflecting mirror 32 serves to fold or deflect the output image 133 from the PFO device 35 as a HUD image 233, which appears via a tertiary image transmission path (P3). This HUD image 233 is finally directed onto the windscreen 11 (or the HUD field 250) by means of the deflecting mirror 32. As used herein, the terms primary, secondary, and tertiary are used to denote the sequential positions of the light transmission paths (P1, P2, P3) with respect to the HUD projector 30, i.e., the primary tertiary light transmission paths (P1 and P3) being closest to and furthest from the HUD projector 30, respectively.

[0030] In one or more embodiments, the deflecting mirror 32 can be constructed as a reflective piece made of a curved or flat material. Exemplary construction materials include, for example, high-quality optical glass or plastic with an aluminum, silver, or other highly reflective coating, dielectric mirrors, etc. Due to the aforementioned packaging and installation space limitations of the dashboard 26 / instrument panel area, the use of the deflecting mirror 32 allows the HUD projector 30 to be positioned in a space-optimized location. More than one deflecting mirror 32 can be used in other implementations, and therefore the representative construction of Fig. 2 not restrictive.

[0031] The controller 50 of the PFO device 35 can be equipped with one or more processors 52 and a non-transient, computer-readable storage medium 54, i.e., a memory 54. The memory 54 is rewritable and is accessible via an optical profile (CC). P ) as set out below. This feature allows the PFO device 35 to be configured in a logic for a specific windshield 11 as mentioned above. The processor 52 in one or more embodiments can be configured to control the optical profile (CC). P ) to maintain the PFO device 35 during operation of the HUD system 25, so that the optical profile (CC) P) does not deviate from a recorded baseline during the lifetime of the HUD system 25. The memory 54 can comprise memory chips or circuits, e.g., magnetic or optical media, a CD-ROM, solid-state / semiconductor memory (e.g., RAM or ROM), etc. The processor 52 can be composed of various combinations of application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), electronic circuits, central processing units, e.g., microprocessors, and the like.

[0032] Non-transitory components of the memory 54 are capable of storing machine-readable instructions in the form of one or more software or firmware programs or routines, combinational logic circuit(s), input / output circuit(s) and devices, a signal conditioning and buffer circuit arrangement, and other components that can be accessed by one or more processors 52, for example, to maintain a phase profile of the PFO device 35 during use of the HUD system 25 in some embodiments. Input / output circuits and devices for use with the actuator controller 50 may include analog-to-digital converters and related devices that monitor inputs from sensors, such inputs being monitored at a preset sampling frequency or in response to a trigger event.Software, firmware, programs, instructions, control routines, code, algorithms and similar terms refer to sets of instructions executable by the controller, including calibrations and lookup tables.

[0033] The PFO device 35 of Fig. 2 can be controlled to generate different wavefronts. For this purpose, the PFO device 35 can vary depending on the intended application. In general, the PFO device 35 can have an optical freeform surface that is controlled to deviate from purely aspherical or spherical shapes. Embodiments of the PFO device 35 within the scope of the disclosure can include at least one reflective element or at least one transmissive element, the former being a more mature and thus commercially available option. To implement the latter, i.e., a transmissive element, the PFO device 35 can incorporate materials such as fused silica, calcium fluoride, optical polymers, etc., which can offer advantages in terms of installation space due to the smaller size of transmissive elements compared to reflective elements.In an embodiment with transmissive elements, the PFO device 35 can contain at least one transmissive element that allows incident light to pass through, while the wavefront and / or phase profiles of the transmitted light are actively controlled, for example, by manipulating a refractive index distribution, thickness and / or a surface profile.

[0034] As in Fig. As illustrated in Figure 3A, an incident wavefront 40 of the light-based input image 33 propagates from the HUD projector 30. Fig. 2 along the primary light transmission path (P1) in the direction of the PFO device 35, which in the embodiment of Fig. 3A is represented as a PFO device 35A, i.e., a reflective element. The PFO device 35A is optionally embodied as a liquid crystal-based mirror or reflective optic, e.g., a liquid crystal-on-silicon (LCoS) mirror, or as an optical component with a silicon chip / backplane of miniature mirrors as known in engineering. Each LCoS-based mirror corresponds to one pixel of the image / icon or other information. The crystal orientation of a liquid crystal material located on the backplane can be controlled to reflect light from the HUD projector 30. Fig. 2. to modulate with other possible components such as polarizers and waveplates, which are used to control the optical properties of light. As in, for example, Fig. As shown in 3B, the output image 133, forming a reflected wavefront 40R, propagates away from the PFO device 35A in the direction of the deflecting mirror 32. Fig. 2 out, where the reflected wavefront 40R has different optical properties than the incident wavefront 40 of Fig. 3A, for example, has a different phase.

[0035] Referring to Fig. 3C and Fig. Alternatively, a further PFO device 35B can be configured as a spatial light modulator with a reflection bulb mode, which has an array of individually controllable micromirrors 350. Such a variant can be used to control the incident light of the input image 33 from the HUD projector 30. Fig. 2, e.g., to modulate the phase, amplitude, and / or polarization. In such an implementation, an array of micromirrors 350 in micrometer size (or smaller) is arranged on different planes ( Fig. 3C). The input image 33 forming the incident wavefront 40 is projected by means of the HUD projector 30 ( Fig. 2) along the primary light transmission path (P1) of Fig. 2 directed onto the array of micromirrors 350. The micromirrors 350 reflect or diffract the light of the input image 33 as output image 133, the latter forming a corrected wavefront 40C. This is reflected by the deflecting mirror 32 towards the windshield 11 / HUD field 250 to produce the HUD image 233. Fig. to generate 2.

[0036] The PFO device 35B of the Fig. 3C and Fig. 3D can be constructed with a flexible / deformable mirror surface and / or using electroactive materials, wherein the mirror surface is formed by the array of micromirrors 350. Such a mirror surface can be shaped or contoured using an actuator assembly 46, wherein the actuator assembly 46 is mounted on a base 44 in one possible configuration. The controller 50 can be connected to or commutated with the actuator assembly 46 and configured to individually control a corresponding state of each of the micromirrors 350. For example, the controller 50 can apply a calibrated electric field to induce a desired change in the refractive index or surface deformation of each of the micromirrors 350, thereby controlling the optical properties and the wavefront characteristics of the corrected wavefront 40C.

[0037] Referring to Fig. 4. The procedure 100 can be implemented in a production plant, a repair depot, or another suitable environment if the HUD system 25 of Fig. 1 for use with a specific windscreen 11, i.e. one that is compatible with the vehicle body 12 of Fig. 1 is connected and has a predetermined surface curvature and a predetermined inclination angle. The procedure 100 is illustrated as a series of execution and decision blocks. The blocks can be performed using manual and / or automated process steps to configure the PFO device 35 of Fig. 2 to calibrate for use with the windscreen 11, i.e. without having to replace an aspherical mirror of the type mentioned elsewhere above or any other hardware of the HUD system 25.

[0038] Starting with block B102, with the HUD system 25 installed in the motor vehicle 10 relative to the windshield 11, the PFO device 35 is set to a standard non-functional state. Using a working example where the PFO device 35 is configured to vary the phase of a light forming the input image 33, block B102 can be set by defining the optical profile (CC). P The PFO device 35 is connected via the controller 50 so that no phase variation of the light forming the input image 33 occurs. The procedure 100 then proceeds to block B104.

[0039] Block B104 includes the placement of camera 37 ( Fig. 2) along a central axis of the eyebox 19, i.e. at the eye level of the operator 18 at the expected position of the operator's eyes when he is inside the vehicle interior 15 of Fig. 1. Commercially available cameras suitable for this purpose include, for example, digital cameras made of a complementary metal-oxide semiconductor (CMOS), which act as image sensors to record digital pixel data of the displayed test image, i.e., a test version of HUD image 233. Fig. 2 or a graphical variant of the HUD image 233. The placement position of the camera 37 corresponds to a stereo viewpoint of the operator 18, and thus the camera 37 acts as a proxy for the operator 18 for calibration purposes. Block B104 also includes projecting the input image 33, in this case as an input test image, along a primary light transmission path (P1) using the HUD projector 30 of the HUD system 25. The procedure 100 proceeds to block B105 once the camera 37 is correctly positioned and the input image 33 (test image) is projected towards the PFO device 35.

[0040] In block B105 of Fig. 4 The method 100 includes reflecting or transmitting or passing through the input image 33 along the secondary light transmission path (P2) as the output image 133 ( Fig. 2) using the recorded optical profile (CC) P), which was initially set to a standard non-functional state in block B102. Reflection / transmission in block B105 occurs via the PFO device 35, which is positioned in the primary light transmission path (P2), as shown in Fig. 2 is shown. Block B105 also includes the reflection of the output image 133 along the tertiary light transmission path (P3) as the HUD image 233 using the deflecting mirror 32 of Fig. 2.

[0041] Furthermore, block B105 includes determining the extent or magnitude of a translational shift and the displayed size of the test version of the HUD image 233 with respect to a corresponding target position and target area on the HUD field 250. For example, block B105 may be associated with determining whether the HUD image 233 (the test graphic) from block B104 has been translated or shifted with respect to a predefined target area of ​​corresponding pixels on the windscreen 11 or the HUD field 250. In some implementations, block B105 may involve the use of computer vision software so that a position of the displayed test graphic is compared with predefined coordinates of the desired target area, such as a single point or a defined display area consisting of multiple points. Procedure 100 proceeds to block B106 when the test graphic, i.e.,The displayed HUD image 233 used during calibration is translated / shifted with respect to the target area, and alternatively to block B109 if the test graphic is not translated / shifted with respect to the target area.

[0042] Block B106 is associated with setting a state of the PFO device 35 via an optical profile setting (CC). P ) connected until a test graphic is no longer translated / shifted with respect to the target area in order to shift the beam that uses the secondary light transmission path (P2) from Fig. 2 forms, e.g., using linear phase variation. The setting of the optical profile (CC) PThis may include setting a suitable prism function for the PFO device 35 via the controller 50, modifying the periodicity or other characteristics of the PFO device 35 until the test graph no longer shows any translational shift, etc. The procedure then continues to block B108.

[0043] In block B108, procedure 100 includes saving the optical profile (CC). P ) or a function of block B106 in memory 54 of controller 50. The updated optical profile (CC P If executed using controller 50, this would eliminate the translational shift and align with the target area, so that the PFO device 35 maintains the desired position of the test graphic. Procedure 100 then proceeds to block B109.

[0044] Block B109 involves determining whether the size of the test graphic has changed, i.e., whether it has shrunk or grown relative to a desired size. As in Block B105, this decision can be made in the logic of Controller 50 by comparing a true pixel area or pixel range of the displayed test graphic—the HUD image 233 used during calibration—with a predetermined pixel range to determine whether the two ranges are within an acceptable application-specific tolerance. Procedure 100 proceeds to Block B110 if the displayed size of the test graphic is reduced (or enlarged) relative to the predetermined size. Alternatively, Procedure 100 proceeds to Block B112 if the test graphic is the correct size, i.e., if its number of image pixels or other criteria match the predetermined size.

[0045] In block B110, if the test graphic from block B109 has been determined to have shrunk (or grown) with respect to its predetermined or desired size, procedure 100 can apply a one-dimensional or two-dimensional parabolic total phase function in addition to the existing displacement correction function previously stored in block B108. This additional total phase function is maintained until the size difference is eliminated. The procedure then proceeds to block B112.

[0046] Block B112 includes maintaining the phase profile of the PFO device, e.g., the overall phase function, and storing the corresponding state, e.g., voltage, current, capacitance, etc., for each of the constituent pixels of the test graph. The calibration is thus complete, and therefore camera 37 is... Fig. 2 removed. The display of the test graphic is interrupted. The HUD system 25 can therefore be prepared for use with windshields 11 that have the same surface curvature and the same angle of inclination as the windshield 11 used to calibrate the PFO device 35.

[0047] As a person skilled in the art will recognize, the advantage of the present teaching now enables the use of the PFO 35 described herein, whose representative embodiments are in Fig. 2-3D illustrations demonstrate a program-based compensation for differences in surface curvature and the inclination angle of the in Fig. 1 and Fig. 2 shown windshield 11. The HUD system 25 is characterized by the absence of the aforementioned aspherical mirror. Instead, the HUD system 25 utilizes the PFO 35 and places the deflecting mirror 32 in the position normally occupied by the aspherical mirror and the PFO 35 in the position normally occupied by the deflecting mirror 32. With such a HUD system 25 in place, the calibration procedure 100 of the Fig. 4 can be used to enable the installation of a given HUD system 25 in a wide range of different vehicle models, thus eliminating countless potential manufacturing problems and inefficiencies associated with redesign requirements related to aspherical mirrors. These and other advantages of the present disclosure are readily apparent in light of the preceding disclosure.

[0048] Aspects of the present disclosure have been described in detail with reference to the illustrated embodiments; however, the person skilled in the art will recognize that many modifications can be made without departing from the scope of the present disclosure. The present disclosure is not limited to the exact construction and compositions disclosed herein; any and all modifications, changes, and variants apparent from the preceding descriptions are within the scope of the disclosure as defined by the appended claims. Furthermore, the present concepts include any and all combinations and partial combinations of the foregoing elements and features.

Claims

[1] Head-up display (HUD) system (25) for use with a windscreen (11) having a predetermined curvature and angle of inclination, comprising: a HUD projector (30) configured to project an input image (33) along a primary light transmission path (P1); a device (35) with programmable freeform optics (PFO) positioned in the primary light transmission path (P1), wherein the PFO device (35) is configured to reflect or transmit the input image (33) along a secondary light transmission path (P2) using a recorded optical profile (CCP) as the output image (133); a deflecting mirror (32) arranged in the secondary light transmission path (P2), wherein the deflecting mirror (32) is configured to reflect the output image (133) along a tertiary light transmission path (P3) as a HUD image (233), wherein the PFO device (35) is programmed to locally control a wavefront characteristic of the output image (133) to compensate for the curvature and tilt angle when the HUD system (25) displays the HUD image (233) via a HUD field (250); and a processor (52) configured to maintain the optical profile (CCP) of the PFO device (35) during operation of the HUD system (25) so that the optical profile (CCP) does not deviate from a recorded baseline during the lifetime of the HUD system (25). [2] HUD system (25) according to claim 1, wherein the PFO device (35) comprises a reflective element. [3] HUD system (25) according to claim 2, wherein the reflecting element comprises a liquid crystal-based mirror. [4] HUD system (25) according to claim 3, wherein the liquid crystal-based mirror comprises a liquid crystal-on-silicon (LCoS)-based mirror. [5] HUD system (25) according to claim 2, wherein the reflecting element comprises a spatial light modulator in piston mode having an array of individually controllable micromirrors (350). [6] HUD system (25) according to claim 1, wherein the PFO device (35) comprises a transmissive element. [7] HUD system (25) according to claim 1, further comprising: the HUD field (250). [8] Motor vehicle (10), comprising: a vehicle body (12) that defines a vehicle interior (15); one or more road wheels (14) connected to the vehicle body (12); a windshield (11) connected to the vehicle body (12), wherein the windshield (11) has a predetermined curvature and a predetermined angle of inclination; and a head-up display (HUD) system (25) for displaying a head-up display (HUD) image (233) in the vehicle interior (15), the HUD system (25) comprising: a head-up display (HUD) projector (30) configured to project an input image (33) along a primary light transmission path (P1); a HUD field (250) that is located on or near the windscreen (11); a device (35) with programmable freeform optics (PFO) arranged in the primary light transmission path (P1), wherein the PFO device (35) is configured to reflect or transmit the input image (33) along a secondary light transmission path (P2) using a recorded optical profile (CCP) as the output image (133); a deflecting mirror (32) positioned in the secondary light transmission path (P2), wherein the deflecting mirror (32) is configured to reflect the output image (133) along a tertiary light transmission path (P3) as a HUD image (233), wherein the PFO device (35) is programmed to locally control a wavefront characteristic of the output image (133) to compensate for the curvature and tilt angle when the HUD system displays the HUD image (233) over the HUD field (250); and a processor (52) configured to maintain the optical profile (CCP) of the PFO device (35) during operation of the HUD system, so that the optical profile (CCP) does not deviate from a recorded baseline during the lifetime of the HUD system.

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