Programmable free-form optical system for 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, the HUD system including an HUD projector, a programmable free form optical (PFO) device, and a fold mirror. The projector is configured to project an input image along the primary light transmission path. The PFO device is positioned in the primary light transmission path and reflects or transmits the input image as an output image along the secondary light transmission path. A folding mirror arranged in the secondary optical transmission path reflects the output image as an HUD image along the third-stage optical transmission path. The PFO device is programmed to locally control wavefront characteristics of the output image to compensate for curvature and tilt when the HUD system displays the HUD image via the HUD patch.

Description

[0001] INTRODUCTION Head-up display (HUD) systems can be used on vehicles to present information near an operator's forward-facing line of sight. With a HUD system, an operator is able to freely view real-time vehicle information that is typically communicated via dashboard gauges or a center console screen. For example, a HUD system can display current vehicle speed and heading, or graphics such as lane boundary markers, lane departure or obstacle detection warnings. Projecting such information into or near an operator's line of sight allows the operator to view the displayed information without diverting attention from the roadway or other travel path.

[0002] In-vehicle HUD systems typically include a dashboard-embedded projector that directs a light-based image to a reflective folding mirror. The projected image is reflected off the folding mirror onto an aspheric mirror, which in turn directs the image to a designated area of the windshield. The designated area, referred to herein and in the art as the HUD patch, can include a flat sheet of reflective glass or plastic, or can include a coated interior surface portion of the windshield. To the vehicle operator, the projected image can appear to seamlessly float in front of the windshield. SUMMARY

[0003] Disclosed herein is a head-up display (HUD) system for a vehicle, such as a motor vehicle, an aircraft, a spacecraft, a rail vehicle / train, a watercraft / ship, or other mobile system having a windshield. The disclosed HUD system includes a programmable freeform optics (PFO) device as part of its construction, which is used to facilitate use of the HUD system across a wide variety of vehicle models, each having a differently configured windshield.

[0004] As appreciated in the art, the surface curvature, rake angle, and other geometry of the installed windshield tends to vary between vehicle models. The non-planar surface of the installed windshield often distorts or defocuses light rays passing therethrough, and can cause other aberrations. The aforementioned aspheric mirror is typically used to correct for such aberrations when projecting light-based information using a HUD system. However, the aspheric mirror is uniquely tailored to the specific curvature and rake angle of the installed windshield. As a result, the HUD system is typically customized for use in a given make or model of vehicle. The present solution aims to enable a given HUD system to be used across a wide variety of vehicle models, regardless of windshield configuration, thereby addressing many manufacturing inefficiencies associated with the HUD system redesign process.

[0005] The solution described herein replaces the aspherical mirror of a typical HUD system with a PFO device. The PFO device, in its various configurations, forms a controllable hardware element that facilitates calibration and allows for local correction of the light transmission path between the PFO device and the downstream folding mirror. Among other attendant benefits, the non-transitory computer readable storage medium / memory of the PFO device is rewritable, thereby enabling the disclosed HUD system to be shared across a wide variety of vehicle models, as described above.

[0006] According to particular embodiments, a HUD system is disclosed for use with a windshield having a predetermined curvature and tilt angle. The HUD system includes a HUD projector, a PFO device, and a folding 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. This occurs along a secondary light transmission path. The folding mirror is disposed in the secondary light transmission path and is configured to reflect the output image along a tertiary light transmission path, where the reflected light forms a HUD image. The PFO device set forth herein is programmed to locally control wavefront characteristics of the output image to compensate for the curvature and tilt angle when the HUD system displays the HUD image on the HUD patch. In some configurations, the HUD patch in turn can be part of the HUD system, possibly including a HUD patch located on an interior surface of the windshield.

[0007] In one or more embodiments, the PFO device includes a reflective element, such as a liquid crystal based mirror, e.g., a liquid crystal on silicon (LCoS) based mirror, or a piston mode spatial light modulator having an array of individually controllable micromirrors. In other embodiments, the PFO device can include a transmissive element.

[0008] The processor can be configured to maintain an optical profile of the PFO device during operation of the HUD system such that the optical profile does not deviate from a recorded baseline over the life of the HUD system.

[0009] A motorized vehicle is also disclosed herein. In possible configurations, the motorized vehicle includes 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 predetermined curvature and tilt angle. In this embodiment, the HUD system is operable to display a HUD image in the vehicle interior and includes a HUD projector configured to project an input image along a primary light transmission path, a HUD patch disposed on or near the windshield, and a PFO device positioned in the primary light transmission path.

[0010] In this embodiment, the PFO device reflects or transmits the input image along a secondary light transmission path as an output image using a recorded optical profile. Additionally, a fold mirror is disposed in the secondary light transmission path, where the fold mirror is configured to reflect the output image along a tertiary light transmission path as a HUD image. The PFO device is programmed to locally control wavefront properties of the output image to compensate for the curvature and tilt when the HUD system displays the HUD image via a HUD patch.

[0011] Another aspect of the present disclosure includes a method for calibrating a heads-up display (HUD) system for use with a windshield having a predetermined curvature and tilt. The method according to an exemplary embodiment includes 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 as an output image using a recorded optical profile via a programmable freeform optical (PFO) device positioned in the primary light transmission path.

[0012] Additionally, the method includes reflecting the output image along a tertiary light transmission path as a HUD image using a fold mirror and determining a translational offset and display size of the test graphic relative to a corresponding target location and target area on a HUD patch of the HUD system via a camera. As part of the method, the optical profile is recorded in a non-transitory computer readable storage medium (memory) of the PFO device, where the optical profile, when executed, eliminates the translational offset and matches to the target area. The method also includes executing the optical profile from the memory of the PFO device during operation of the HUD system.

[0013] The method can include maintaining the optical profile of the PFO device during operation of the HUD system such that the optical profile does not deviate from the recorded baseline over the life of the HUD system.

[0014] Projecting the input test image along the primary light transmission path includes displaying the input test image on an interior surface of the windshield, where the HUD patch can be located on the interior surface of the windshield.

[0015] The present disclosure provides the following embodiments.

[0016] 1. A heads-up display (HUD) system for use with a windshield having a predetermined curvature and tilt, comprising: a HUD projector configured to project an input image along a primary light transmission path; a programmable freeform optical (PFO) device positioned in the primary light transmission path, the PFO device configured to reflect or transmit the input image along a secondary light transmission path as an output image using a recorded optical profile; and a fold mirror disposed in the secondary light transport path, the fold mirror configured to reflect the output image as a HUD image along a tertiary light transport path, wherein the PFO device is programmed to locally control wavefront properties of the output image to compensate for the curvature and the tilt when the HUD system displays the HUD image via the HUD patch.

[0017] 2. The HUD system of embodiment 1, wherein the PFO device comprises a reflective element.

[0018] 3. The HUD system of embodiment 2, wherein the reflective element comprises a liquid crystal based mirror.

[0019] 4. The HUD system of embodiment 3, wherein the liquid crystal based mirror comprises a liquid crystal on silicon (LCoS) based mirror.

[0020] 5. The HUD system of embodiment 2, wherein the reflective element comprises a piston mode spatial light modulator having an array of individually controllable micromirrors.

[0021] 6. The HUD system of embodiment 1, wherein the PFO device comprises a transmissive element.

[0022] 7. The HUD system of embodiment 1, further comprising a processor configured to maintain an optical profile of the PFO device during operation of the HUD system such that the optical profile does not deviate from a recorded baseline over a lifetime of the HUD system.

[0023] 8. The HUD system of embodiment 1, further comprising a HUD patch.

[0024] 9. The HUD system of embodiment 8, wherein the HUD patch is located on an interior surface of the windshield.

[0025] 10. A motorized vehicle comprising: a vehicle body defining an interior of the vehicle; one or more road wheels connected to the vehicle body; a windshield connected to the vehicle body, the windshield having a predetermined curvature and tilt; and a head-up display (HUD) system operable to display a head-up display (HUD) image within the interior of the vehicle, the HUD system comprising: a head-up display (HUD) projector configured to project an input image along a primary light transport path; a HUD patch disposed on or near the windshield; a programmable freeform optical (PFO) device positioned in a primary light transmission path, the PFO device configured to reflect or transmit an input image along a secondary light transmission path as an output image using a recorded optical profile; and a fold mirror disposed in the secondary light transmission path, the fold mirror configured to reflect the output image along a tertiary light transmission path as a HUD image, wherein the PFO device is programmed to locally control wavefront properties of the output image to compensate for curvature and tilt when the HUD system displays the HUD image via a HUD patch.

[0026] 11. The motorized vehicle of embodiment 10, wherein the PFO device comprises a reflective element.

[0027] 12. The motorized vehicle of embodiment 11, wherein the reflective element comprises a liquid crystal based mirror.

[0028] 13. The motorized vehicle of embodiment 12, wherein the liquid crystal based mirror comprises a liquid crystal on silicon (LCoS) based mirror.

[0029] 14. The motorized vehicle of embodiment 11, wherein the reflective element comprises a piston mode spatial light modulator having an array of individually controllable micromirrors.

[0030] 15. The motorized vehicle of embodiment 10, wherein the PFO device comprises a transmissive element.

[0031] 16. The motorized vehicle of embodiment 10, further comprising: a processor configured to maintain the optical profile of the PFO device during operation of the HUD system such that the optical profile does not deviate from the recorded baseline over the lifetime of the HUD system.

[0032] 17. A method for calibrating a head-up display (HUD) system for use with a windshield having a predetermined curvature and tilt, the method comprising: projecting an input test image along a primary light transmission path using a HUD projector of the HUD system; reflecting or transmitting the input test image along a secondary light transmission path as an output image via a programmable freeform optical (PFO) device positioned in the primary light transmission path using a recorded optical profile; reflecting the output image along a tertiary light transmission path as a HUD image using a fold mirror; determining a translational offset and display size of the test pattern relative to a corresponding target position and target area on a HUD patch of the HUD system via a camera; recording an optical profile in a non-transitory computer readable storage medium (memory) of the PFO device, the optical profile, when executed, eliminates translational offset and matches to a target area; and executing the optical profile from the memory of the PFO device during operation of the HUD system.

[0033] 18. The method of embodiment 17, wherein the PFO device comprises a reflective element, and wherein reflecting or transmitting the input test image along the secondary light transmission path is performed using the reflective element.

[0034] 19. The method of embodiment 17, further comprising: maintaining the optical profile of the PFO device during operation of the HUD system such that the optical profile does not deviate from the recorded baseline over the lifetime of the HUD system.

[0035] 20. The method of embodiment 17, wherein projecting the input test image along the primary light transmission path comprises displaying the input test image on an interior surface of the windshield, and wherein the HUD patch is located on the interior surface of the windshield.

[0036] The above-mentioned features and advantages of the present teachings, as well as other features and advantages of one or more of the embodiments of the present teachings provided herein, are readily apparent to one skilled in the art from the following detailed description of some of the best modes and other embodiments for carrying out the present teachings, as defined by the appended claims, when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings incorporated in and forming a part of the specification, illustrate implementations of the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0038] Figure 1 illustrates a motor vehicle equipped with a heads-up display (HUD) system having a programmable free-form optical (PFO) device in accordance with the present disclosure.

[0039] Figure 2 illustrates a PFO device in accordance with a possible embodiment. Figure 2

[0040] Figure 3A , 3B , 3C and 3D illustrate non-limiting representative implementations of the PFO device shown in Figure 2

[0041] Figure 4 is a flowchart depicting a calibration method for a HUD system in accordance with an embodiment. Figure 1 and Figure 2

[0042] ​​​The accompanying drawings are not necessarily to scale and may present simplified representations of various preferred features of the present disclosure, including, for example, specific dimensions, orientations, positions, and shapes. Details associated with these features will be determined in part by the specific intended application and environment of use. Detailed Implementation

[0043] The components of the disclosed embodiments can be arranged in various configurations. Therefore, the following detailed description is not intended to limit the scope of the claimed disclosure, but merely to illustrate possible embodiments therein. Furthermore, while numerous specific details are set forth in the following description to provide a thorough understanding of various representative embodiments, some embodiments may be practiced without some of the details disclosed. Additionally, for the sake of clarity, certain technical materials known in the related art have not been described in detail. Moreover, the disclosure illustrated and described herein can be practiced in the absence of elements not specifically disclosed herein.

[0044] Referring now to the accompanying drawings, where the same reference numerals are used throughout several views to refer to the same features. Figure 1 A vehicle 10 is described having a vehicle body 12, which defines the vehicle interior 15. A windshield 11 is connected to the vehicle body 12. The vehicle 10 can be embodied in various ways as a motorized vehicle as shown, i.e., having a set of wheels 14 and one or more propulsion sources (not shown), such as an internal combustion engine and / or an electric traction motor. In other configurations, the vehicle 10 can be constructed as an aircraft, spacecraft, motorcycle, train / rail vehicle, boat / ship, etc. Therefore, this teaching is not limited to... Figure 1 Example. For the sake of consistency, vehicle 10 will be described below as motor vehicle 10 without limitation.

[0045] Figure 1 The motor vehicle 10 includes a head-up display (HUD) system 25, the non-limiting example embodiment of which is shown in Figure 2 As shown in [the image]. Figure 1 In the illustrated implementation, the HUD system 25 is configured to project information onto the windshield 11, or more specifically, onto a HUD patch (HP) 250 located on or near the windshield 11. Figure 1 In a non-limiting embodiment, the operator 18 is shown in a forward-facing position in the driver's seat 16, with the operator 18 seated behind the steering wheel 17. The information projected onto the HUD patch 250 is thus presented near or along the operator 18's normal forward line of sight for easy / non-distracted viewing of the displayed information.

[0046] The construction of the HUD patch 250 can vary with the specific design of the HUD system 25. For example, in possible embodiments, the HUD patch 250 can be a coated portion of the windshield 11 in a windshield projection implementation, or the HUD patch 250 can be implemented as a deployable "pop-up" screen, a combiner screen, a fixed panel, or an augmented reality (AR) display. The latter AR embodiment can be particularly useful for superimposing icons, images, or other graphics onto the real-world view of the travel path visible to the operator 18 through the windshield 11.

[0047] Reference is made to Figure 2 , which illustrates a HUD system 25 according to a representative configuration. As contemplated herein, the HUD system 25 is installed in the vicinity of the windshield 11 (also shown in Figure 1 ), such as under / at the rear of the dashboard 26. In the non-limiting implementation of Figure 2 , the operator 18 or the camera 37 views the HUD patch 250 located on or in the vicinity of the inner surface of the windshield 11 during the calibration method 100 of Figure 4 . The three-dimensional (3D) volume within which the driver's eyes are located in order to properly view the projected information on the HUD patch 250 is referred to as the eyebox 19. Thus, Figure 2 , the eyebox 19 of defines a region in which the eyes of the operator 18 can move while maintaining a clear view of the displayed information, e.g., without distortion or loss of field of view / image cutoff.

[0048] As appreciated in the art, the windshield 11 is installed on the motor vehicle 10 of Figure 1 with a corresponding curvature (camber) and a rake angle, i.e., an angle formed between the installed windshield 11 and a vertical line perpendicular to the ground plane. The size and surface geometry of the windshield 11 provide the vehicle brand / model with a desired level of aerodynamic performance and strength, and also increase or decrease the available headroom within the vehicle interior 15 of Figure 1 . Thus, different brands or models of motor vehicles 10 are typically equipped with windshields 11 having different curvatures and / or rake angles. As indicated above, this reality complicates the reuse of typical HUD system hardware elements across vehicle platforms.

[0049] To alleviate the manufacturing issues associated with this lack of reusability, Figure 2 , the HUD system 25 is equipped with a programmable freeform optics (PFO) device 35 that enables the motor vehicle 10 ( Figure 1manufacturers of the HUD system 25 can modify the optical properties of the HUD system 25 during calibration in order to achieve the desired optical performance. The use of the PFO device 35 set forth below enables in-facility calibration of the HUD system 25 to a given windshield 11. The optical performance of the HUD system 25 is achieved via simple programming inputs, where reference is made below to Figure 4 An exemplary calibration method is described.

[0050] In Figure 2 In the illustrated implementation of the HUD system 25, the HUD projector 30, the PFO device 35 and the fold mirror 32. The HUD projector 30 can be embodied as an array of light emitting diodes (LEDs), or a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a quantum dot display, etc. Thus, the HUD projector 30 is structured as a light display operable to generate light-based information, i.e., an input image 33, and project the light-based information along a primary light transmission path (PI) toward the PFO device 35. The PFO device 35 further includes or is connected to a controller (C) 50 described below, and can be connected to a picture generation unit, or other device operable to control the context of the generated information. The PFO device 35 then directs the corrected output image 133 along a secondary image transmission path (P2).

[0051] The fold mirror 32 is operable to fold or redirect the output image 133 from the PFO device 35 as a HUD image 233 that emerges on a tertiary light transmission path (P3). The HUD image 233 is ultimately directed by the fold mirror 32 toward the windshield 11 (or a HUD patch 250). As used herein, the terms "primary", "secondary" and "tertiary" are used to indicate the sequential position of the light paths (PI, P2, P3) relative to the HUD projector 30, i.e., where the primary and tertiary light transmission paths (PI and P3) are located closest and farthest, respectively, from the HUD projector 30.

[0052] In one or more embodiments, the fold mirror 32 can be constructed from a reflective sheet of curved or planar material. Exemplary construction materials include, for example, optical glass, or high quality plastics with aluminum, silver or other high reflective coatings, dielectric mirrors, etc. Due to the physical packaging constraints of the instrument panel 26 / dash area described above, the use of the fold mirror 32 allows the HUD projector 30 to be positioned in a spatially optimal location. More than one fold mirror 32 can be used in other implementations, and thus Figure 2 The representative construction of the HUD system 25 is non-limiting.

[0053] The controller 50 of the PFO device 35 can be equipped with one or more processors 52 and a non-transitory computer-readable storage medium 54, i.e., a memory 54. The memory 54 is rewritable and can be programmed via an optical profile (CC P ) as set forth below. As noted above, this feature allows the PFO device 35 to be logically configured for a given windshield 11. In one or more embodiments, the processor(s) 52 can be configured to maintain the optical profile (CC P ) of the PFO device 35 during operation of the HUD system 25 so that the optical profile (CC P ) does not deviate from the recorded baseline over the life of the HUD system 25. The memory 54 can comprise a memory chip or circuit, e.g., a magnetic or optical medium, a CD-ROM, a solid state / semiconductor memory (e.g., RAM or ROM), etc. The processor(s) 52 can be comprised of various combinations of application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), electronic circuits, central processing units (e.g., microprocessors), etc.

[0054] In some embodiments, the 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 circuits, input / output circuits and devices, signal conditioning and buffering circuits, and other components accessible to the processor(s) 52 to maintain, for example, the phase profile of the PFO device 35 during use of the HUD system 25. The input / output circuits and devices used with the actuator control unit 50 can include analog / digital converters and related devices that monitor inputs from sensors, where such inputs are monitored at a preset sampling frequency or in response to a triggering event. Software, firmware, programs, instructions, control routines, code, algorithms, and like terms mean sets of instructions executable by the controller, including calibration and lookup tables.

[0055] The controller 50 can be configured to control the PFO device 35 to maintain the optical profile (CC Figure 2The PFO device 35 of FIG. 1 is configured to produce a different wavefront. To this end, the configuration of the PFO device 35 can vary with the intended application. Generally speaking, the PFO device 35 can include a freeform optical surface that is controlled to deviate from a pure aspheric or spherical shape. Embodiments of the PFO device 35 within the scope of the present disclosure can include at least one reflective element or at least one transmissive element, with the former option being the more mature and thus commercially available option. To implement the latter, i.e., a transmissive element, the PFO device 35 can include materials such as fused silica, calcium fluoride, optical polymers, etc., which can offer packaging space advantages due to the smaller size of the transmissive element relative to the reflective element. In transmissive element embodiments, the PFO device 35 can include at least one transmissive element that allows incident light to pass through while actively controlling the wavefront and / or phase profile of the transmitted light, e.g., by manipulating the refractive index profile, thickness, and / or surface profile.

[0056] As shown in FIG. 1, the incident wavefront 40 of the light-based input image 33 from the HUD projector 30 propagates along a primary light transmission path (PI) toward the PFO device 35, which in embodiments of FIG. 1 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 optic piece with a miniature mirror silicon chip / backplane as appreciated in the art. Each LCoS-based mirror corresponds to one pixel of an image / icon or other information. The crystal orientation of the liquid crystal material residing on the backplane can be controlled to modulate the light from the HUD projector 30, with other possible components such as polarizers and waveplates used to control the optical properties of the light. For example, as shown in FIG. 1, the output image 133 forming a reflected wavefront 40R propagates away from the PFO device 35A toward the folding mirror 32 of FIG. 1, with the reflected wavefront 40R having different optical properties, e.g., a different phase, than the incident wavefront 40 of FIG. 1. Figure 3A Figure 2 As shown in FIG. 1, the incident wavefront 40 of the light-based input image 33 from the HUD projector 30 propagates along a primary light transmission path (PI) toward the PFO device 35, which in embodiments of FIG. 1 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 optic piece with a miniature mirror silicon chip / backplane as appreciated in the art. Each LCoS-based mirror corresponds to one pixel of an image / icon or other information. The crystal orientation of the liquid crystal material residing on the backplane can be controlled to modulate the light from the HUD projector 30, with other possible components such as polarizers and waveplates used to control the optical properties of the light. For example, as shown in FIG. 1, the output image 133 forming a reflected wavefront 40R propagates away from the PFO device 35A toward the folding mirror 32 of FIG. 1, with the reflected wavefront 40R having different optical properties, e.g., a different phase, than the incident wavefront 40 of FIG. 1. Figure 3A Figure 2 As shown in FIG. 1, the incident wavefront 40 of the light-based input image 33 from the HUD projector 30 propagates along a primary light transmission path (PI) toward the PFO device 35, which in embodiments of FIG. 1 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 optic piece with a miniature mirror silicon chip / backplane as appreciated in the art. Each LCoS-based mirror corresponds to one pixel of an image / icon or other information. The crystal orientation of the liquid crystal material residing on the backplane can be controlled to modulate the light from the HUD projector 30, with other possible components such as polarizers and waveplates used to control the optical properties of the light. For example, as shown in FIG. 1, the output image 133 forming a reflected wavefront 40R propagates away from the PFO device 35A toward the folding mirror 32 of FIG. 1, with the reflected wavefront 40R having different optical properties, e.g., a different phase, than the incident wavefront 40 of FIG. 1. Figure 3B Figure 2 As shown in FIG. 1, the incident wavefront 40 of the light-based input image 33 from the HUD projector 30 propagates along a primary light transmission path (PI) toward the PFO device 35, which in embodiments of FIG. 1 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 optic piece with a miniature mirror silicon chip / backplane as appreciated in the art. Each LCoS-based mirror corresponds to one pixel of an image / icon or other information. The crystal orientation of the liquid crystal material residing on the backplane can be controlled to modulate the light from the HUD projector 30, with other possible components such as polarizers and waveplates used to control the optical properties of the light. For example, as shown in FIG. 1, the output image 133 forming a reflected wavefront 40R propagates away from the PFO device 35A toward the folding mirror 32 of FIG. 1, with the reflected wavefront 40R having different optical properties, e.g., a different phase, than the incident wavefront 40 of FIG. 1. Figure 3A

[0057] As shown in FIG. 1, the incident wavefront 40 of the light-based input image 33 from the HUD projector 30 propagates along a primary light transmission path (PI) toward the PFO device 35, which in embodiments of FIG. 1 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 optic piece with a miniature mirror silicon chip / backplane as appreciated in the art. Each LCoS-based mirror corresponds to one pixel of an image / icon or other information. The crystal orientation of the liquid crystal material residing on the backplane can be controlled to modulate the light from the HUD projector 30, with other possible components such as polarizers and waveplates used to control the optical properties of the light. For example, as shown in FIG. 1, the output image 133 forming a reflected wavefront 40R propagates away from the PFO device 35A toward the folding mirror 32 of FIG. 1, with the reflected wavefront 40R having different optical properties, e.g., a different phase, than the incident wavefront 40 of FIG. 1. Figure 3C Figure 3D As shown in FIG. 1, the incident wavefront 40 of the light-based input image 33 from the HUD projector 30 propagates along a primary light transmission path (PI) toward the PFO device 35, which in embodiments of FIG. 1 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 optic piece with a miniature mirror silicon chip / backplane as appreciated in the art. Each LCoS-based mirror corresponds to one pixel of an image / icon or other information. The crystal orientation of the liquid crystal material residing on the backplane can be controlled to modulate the light from the HUD projector 30, with other possible components such as polarizers and waveplates used to control the optical properties of the light. For example, as shown in FIG. 1, the output image 133 forming a reflected wavefront 40R propagates away from the PFO device 35A toward the folding mirror 32 of FIG. 1, with the reflected wavefront 40R having different optical properties, e.g., a different phase, than the incident wavefront 40 of FIG. 1. Figure 2 ​​​​​of the HUD projector 30, such as phase, amplitude, and / or polarization. In this implementation, an array of micromirrors 350 of micrometer size (or smaller) is arranged in different planes Figure 3C ). The input image 33 forming the incoming wavefront 40 is directed by the HUD projector 30 Figure 2 ) along a primary light transmission path (PI) to the array of micromirrors 350. The micromirrors 350 reflect or diffract the light of the input image 33 as an output image 133, which forms the corrected wavefront 40C. It is reflected from the folding mirror 32 towards the windshield 11 / HUD patch 250 to form the HUD image 233. Figure 2 Figure 2

[0058] Figure 3C and 3D The PFO device 35B can be made of a flexible / deformable mirror and / or using electroactive materials, where the mirror is formed by the array of micromirrors 350. Such a mirror can be shaped or contoured using an actuator assembly 46, where in possible configurations the actuator assembly 46 is mounted on a base 44. A controller 50 can be connected to or in communication with the actuator assembly 46 and configured to individually control the corresponding state of each respective micromirror 350. For example, the controller 50 can apply a calibrated electric field to induce a desired refractive index change or surface deformation of each micromirror 350 to control the optical properties and wavefront characteristics of the corrected wavefront 40C.

[0059] Referring to Figure 4 , when the HUD system 25 of Figure 1 is configured for use with a particular windshield 11 (i.e., a windshield connected to the vehicle body 12 of Figure 1 and having a predetermined surface curvature and tilt angle), the method 100 can be implemented in a manufacturing facility, a repair shop, or other suitable environment. The method 100 is shown as a series of execution and decision blocks. These blocks can be performed using manual and / or automated process steps to calibrate the PFO device 35 of Figure 2 for use with the windshield 11, i.e., without having to replace an aspherical mirror or other hardware of the HUD system 25 of the type noted elsewhere above.

[0060] Starting from block B102, in the case where the HUD 25 is installed in the motor vehicle 10 relative to the windshield 11 of Figure 1 , the PFO device 35 is set to a default non-operational state. Using a working example in which the PFO device 35 is configured to vary the phase of the light forming the input image 33, block B102 can entail setting the optical profile (CC P ​​This prevents phase changes in the light that forms the input image 33. Method 100 proceeds to box B104.

[0061] Frame B104 includes a camera 37 positioned along the central axis of eyebox 19. Figure 2 That is, when operator 18 sits Figure 1 When the camera 37 is inside the vehicle 15, it is positioned at eye level of the operator at the intended location of the operator's eyes. Commercially available cameras for this purpose include, for example, complementary metal-oxide-semiconductor (CMOS) digital cameras, which act as image sensors to capture digital pixel data of the displayed test images, i.e., Figure 2 The test version of the HUD image 233, or a graphical variant of the HUD image 233. The camera 37 is positioned to correspond to the stereoscopic viewing point of the operator 18, and thus the camera 37 acts as a proxy for the operator 18 for calibration purposes. Box B104 also includes the HUD projector 30 of the HUD system 25 projecting the input image 33, in this case, as the input test image, along the primary light transmission path (P1). Once the camera 37 has been correctly positioned and the input image 33 (test image) has been projected toward the PFO device 35, method 100 proceeds to box B105.

[0062] exist Figure 4 At box B105, method 100 includes using the recorded optical profile (CC). P The input image 33 is reflected or transmitted along the secondary optical transmission path (P2) as the output image 133. Figure 2 ), the optical profile (CC P The light is initially set to the default inoperable state in box B102. Reflection / transmission in box B105 occurs via PFO device 35, which is positioned in the primary optical transmission path (P2), as... Figure 2 As depicted in the diagram. Box B105 also includes the use of... Figure 2 The folding mirror 32 reflects the output image 133 along the third-order light transmission path (P3) as the HUD image 233.

[0063] Additionally, frame B105 includes determining the translation offset and display size of the test version of the HUD image 233 relative to a corresponding target position and target area on the HUD patch 250. For example, frame B105 may need to determine whether the HUD image 233 (test pattern) from frame B104 has been translated or offset relative to a predefined target area of ​​a corresponding pixel on the windshield 11 or HUD patch 250. In some implementations, frame B105 may include using computer vision software to compare the position of the displayed test pattern with predetermined coordinates of a desired target area, such as a single point or a defined display area consisting of multiple points. When the test pattern, i.e., the displayed HUD image 233 used during calibration, has been translated / offset relative to the target area, method 100 proceeds to frame B106, and alternatively, when the test pattern has not been translated / offset relative to the target area, method 100 proceeds to frame B109.

[0064] Frame B106 requires adjustment of the optical profile (CC). P Adjust the state of the PFO device 35 until the test pattern no longer shifts / offsets relative to the target area to form Figure 2 Beam deflection in the secondary optical transmission path (P2), for example, using linear phase change. Optical profile (CC) P The adjustments may include adjusting the corresponding prism function of the PFO device 35 via the controller 50, modifying the periodicity or other characteristics of the PFO device 35, until the test pattern no longer exhibits translational offset, etc. Afterward, method 100 proceeds to box B108.

[0065] At box B108, method 100 includes taking the optical profile (CC) from box B106. P The optical profile (CC) or function is stored in the memory 54 of the controller 50. When executed by the controller 50, the updated optical profile (CC) is... P This will eliminate translational offset and match the target area, allowing the PFO device 35 to maintain the desired position of the test pattern. Afterward, method 100 proceeds to box B109.

[0066] Block B109 includes determining whether the test pattern has changed in size, i.e., shrunk or grown relative to the expected size. As in the case of block B105, this determination can be made in the logic of controller 50 by comparing the real pixel area of the displayed test pattern (the displayed HUD image 233 used during calibration) to the predetermined pixel area to determine whether the two areas match within an application-specific tolerance that is allowable. When the display size of the test pattern is reduced (or enlarged) relative to the predetermined size, method 100 proceeds to block B110. Alternatively, when the test pattern is the correct size, i.e., matches the predetermined size in terms of its image pixel quantity or other criteria, method 100 proceeds to block B112.

[0067] At block B110, where the test pattern of block B109 is determined to have shrunk (or grown) relative to its predetermined or expected size, method 100 can apply a one- or two-dimensional parabolic total phase function on top of the existing offset correction function previously stored at block B108. This additional total phase function is maintained until the size discrepancy is eliminated. Thereafter, method 100 proceeds to block B112.

[0068] Block B112 includes maintaining the phase profile of the PFO device, e.g., the total phase function, and storing the corresponding state, e.g., voltage, current, capacity, etc., of each constituent pixel of the test pattern. Thus, the calibration is complete, and therefore Figure 2 the camera 37 is removed. The display of the test pattern is discontinued. Thus, the HUD system 25 is ready for use with the windshield 11 having the same surface curvature and tilt angle as the windshield 11 used to calibrate the PFO device 35.

[0069] As will be appreciated by those of ordinary skill in the art with the benefit of this teaching, the use of the PFO 35 described herein, representative embodiments of which are illustrated in Figure 2-3D enables programmed-based compensation for differences in surface curvature and tilt angle of the windshield 11 as shown in Figure 1 and Figure 2 The HUD system 25 is characterized by the absence of the above-mentioned aspherical mirror. Instead, the HUD system 25 uses the PFO 35, places the folding mirror 32 in the position normally occupied by the aspherical mirror, and places the PFO 35 in the position normally occupied by the folding mirror 32. With this HUD system 25 in place, Figure 4The calibration method 100 can be used to enable a given HUD system 25 to be installed across a wide variety of different vehicle models, thereby eliminating a large number of potential manufacturing issues and inefficiencies associated with the redesign requirements related to aspherical mirrors. These and other benefits of the present disclosure will be readily appreciated in view of the foregoing disclosure.

[0070] Aspects of the present disclosure can be described in detail with reference to the illustrated embodiments; however, as one skilled in the art will appreciate, there are numerous modifications that can be made without departing from the scope of the present disclosure. The present disclosure is not limited to the precise constructions and compositions disclosed herein; any and all modifications, changes, and variations that are evident from the foregoing description and appended claims are within the scope of the present disclosure. Further, the present concept expressly includes any and all combinations and subcombinations of the foregoing elements and features.

Claims

1. A heads-up display (HUD) system for use with a windshield having a predetermined curvature and tilt, comprising: a HUD projector configured to project an input image along a primary light transport path; a programmable freeform optical (PFO) device positioned in the primary light transport path, the PFO device configured to reflect or transmit the input image as an output image along a secondary light transport path using a recorded optical profile; and a fold mirror disposed in the secondary light transport path, the fold mirror configured to reflect the output image as a HUD image along a tertiary light transport path, wherein the PFO device is programmed to locally control wavefront characteristics of the output image to compensate for the curvature and tilt when the HUD system displays the HUD image via a HUD patch.

2. The HUD system of claim 1, wherein the PFO device comprises a reflective element.

3. The HUD system of claim 2, wherein the reflective element comprises a liquid crystal based mirror.

4. The HUD system of claim 3, wherein the liquid crystal based mirror comprises a liquid crystal on silicon (LCoS) based mirror.

5. The HUD system of claim 2, wherein the reflective element comprises a piston mode spatial light modulator having an array of individually controllable micromirrors.

6. The HUD system of claim 1, wherein the PFO device comprises a transmissive element.

7. The HUD system of claim 1, further comprising: a processor configured to maintain the optical profile of the PFO device during operation of the HUD system such that the optical profile does not deviate from a recorded baseline over the lifetime of the HUD system.

8. The HUD system of claim 1, further comprising: a HUD patch.

9. A motorized vehicle, comprising: a vehicle body defining an interior of the vehicle; one or more road wheels connected to the vehicle body; a windshield connected to the vehicle body, the windshield having a predetermined curvature and tilt; and a heads-up display (HUD) system operable to display a heads-up display (HUD) image within the interior of the vehicle, the HUD system comprising: a heads-up display (HUD) projector configured to project an input image along a primary light transport path; a HUD patch disposed on or near the windshield; a programmable freeform optical (PFO) device positioned in the primary light transport path, the PFO device configured to reflect or transmit the input image as an output image along a secondary light transport path using a recorded optical profile; and a fold mirror disposed in the secondary light transport path, the fold mirror configured to reflect the output image as a HUD image along a tertiary light transport path, wherein the PFO device is programmed to locally control wavefront characteristics of the output image to compensate for the curvature and tilt when the HUD system displays the HUD image via the HUD patch.

10. The motorized vehicle of claim 9, further comprising: a processor configured to maintain the optical profile of the PFO device during operation of the HUD system such that the optical profile does not deviate from a recorded baseline over the lifetime of the HUD system.

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