Hybrid HUD for enhanced AR display and simplified integration into a vehicle

Abstract

The invention relates to a projection unit for a head-up display in a vehicle, comprising: - a central HUD unit with an imager for generating a beam of light with a central display content and a projection and / or imaging optic, such that the beam of light leaves the central HUD unit in a predetermined shape and direction towards a reflective disc located in the field of vision of a vehicle occupant, in order to project this display content into their field of vision via reflection off the reflective disc at a predetermined first image distance; and - one or more extension displays, each with its display surface directly opposite the reflective disc and connected to the central HUD unit, so that their display images seamlessly extend the central display content to the left, right, top and / or bottom to form a composite virtual image via reflection on the reflective disc; - wherein the projection unit is designed and configured to provide a contact-analogous representation of the composite virtual image.

Description

[0001] The invention relates to a projection unit for a head-up display (HUD) for use in a vehicle. Such devices are designed to project a virtual image into a user's field of vision via reflection from a reflective screen, such as a windshield or rear window of the vehicle or a specially provided combiner screen arranged in the user's field of vision. The invention also relates to an associated operating method, a correspondingly configured control unit, a head-up display containing the projection unit, and a vehicle equipped therewith.

[0002] Particularly in motor vehicles, it is known to use a head-up display to overlay display content such as speed information or other useful navigation and vehicle operating instructions in the form of a virtual image onto the real surroundings in front of the vehicle as observed by the driver, so that the driver does not have to take their eyes off the road to read the display. For this purpose, a classic HUD design comprises a projection unit located below the windshield inside the instrument panel. This typically contains a display for generating a beam of light with the desired display content, as well as suitable imaging and projection optics (usually with a concave mirror) to shape the beam of light and direct it onto the windshield so that it is reflected back to the driver's eyes, allowing the driver to see the virtual image at a suitable size and distance beyond the windshield.

[0003] For future HUD technologies, an approach is known for road vehicles in which the virtual image plane is not vertical as usual, but almost parallel to the road. This can create a distinct depth or 3D effect for the viewer. As described, for example, in DE 11 2019 003 420 T5, a virtual image can be displayed while a vehicle is moving, which is perceived as adhering to the road surface. For this purpose, an image-generating display surface is arranged inside the device, which receives projection light from a projector and displays a real image. This display surface is arranged at a comparatively strong inclination to the light axis of the projection light.

[0004] Furthermore, a simplified HUD design is known, particularly for generating a panoramic virtual display, with an image sensor positioned opposite the windshield at the base of the windshield. This image is then reflected directly (i.e., without additional imaging or deflection optics) onto the windshield. This HUD variant is therefore also called a "simple HUD" or "windshield base display."

[0005] Furthermore, US 2023 / 0118314 A1 discloses an information display system in a vehicle in which a conventional HUD with a freeform concave mirror for the driver is installed in the instrument panel between the steering wheel and the windshield. The system also includes a simple windshield root display, such as a smartphone, arranged in the upper part of the instrument panel between the HUD and the windshield to display additional information for the driver in the windshield below the HUD image, approximately at the height of the hood. Alternatively or additionally, a similar windshield root display opposite the passenger seat can serve as a virtual image for the passenger.

[0006] Furthermore, JP 2017-140906 A discloses a display device in a vehicle in which a conventional HUD projects important information such as vehicle speed, etc., to the driver via the windshield through an opening in the upper side of the instrument panel behind the steering wheel. Additionally, two flat screens mounted on guide rails are provided to the left and right at a considerable distance from this opening. Each of these flat screens can be moved along the rail toward and away from the driver, rotated about a horizontal axis, and used as direct-view displays. A horizontal position of these flat screens close to the base of the windshield is also described, in which they are used as simple HUDs to project additional information for the driver via the windshield, for example, images from rear cameras on the left and right of the vehicle, which serve as a mirror replacement system for the side mirrors.

[0007] It is an object of the present invention to provide an alternative and / or improved concept for a HUD system in a vehicle with regard to installation space, display options, display quality and / or other aspects.

[0008] This object is achieved by a projection unit according to claim 1, as well as by an associated operating method, a corresponding control unit, a hybrid HUD containing this projection unit, and a vehicle equipped therewith according to the independent claims. Further embodiments are specified in the dependent claims. All further features and effects mentioned in the claims and in the following description for the projection unit also apply to the method, the control unit, the hybrid HUD, and the vehicle, and vice versa.

[0009] According to a first aspect, a projection unit for a head-up display (HUD) is provided for use in a vehicle. The vehicle can be a motor vehicle, but also any other land, air, or water vehicle. Unless otherwise stated, all positional information and spatial orientation terms mentioned herein, such as "vertical," "horizontal," "left," "right," "front," "rear," "below," "above," etc., always refer to the usual vehicle-specific Cartesian coordinate system with mutually perpendicular longitudinal, transverse, and vertical directions of the vehicle.

[0010] First, the projection unit comprises a central HUD unit. This comprises an image generator for generating a light beam with a central display content and projection and / or imaging optics configured in the beam path of this light beam such that the light beam exits the central HUD unit in a predetermined shape and direction toward a reflective disc arranged in the field of vision of a vehicle occupant, in order to project this display content into the occupant's field of vision via reflection from the reflective disc at a predetermined first virtual image distance of, for example, approximately two, three, four, or more meters from their eyes.

[0011] The projection unit also includes one or more extension displays. Their display surfaces are positioned directly opposite the reflection disc (i.e., without any additional optics in between) and are so closely aligned with the central HUD unit from the left and / or right in the transverse direction of the vehicle and / or from the front and / or rear in the longitudinal direction of the vehicle that their display images, reflected off the reflection disc, seamlessly extend the central display content to the left, right, bottom, or top, albeit at a shorter second virtual image distance, to form a composite virtual image. Each extension display forms a simple HUD with the reflection disc, which can also be referred to as a disc root display or simple HUD.The second virtual image distance is the sum of the distances the projection light travels from the respective extension display to the windshield and from the windshield to the occupant's eyes. For common vehicle configurations, this distance can be between one and one and a half meters, typically around 1.2 meters.

[0012] The projection unit is designed and configured to provide a contact-analog representation of the composite virtual image, i.e., one oriented toward real objects outside the vehicle. In other words, the projection unit is designed for AR (augmented reality) applications, in which the real environment viewed by the occupant through a vehicle window is enhanced with virtual image content. For this purpose, the projection unit can, for example, communicate with suitable sensor systems on board the vehicle for detecting an environment outside the vehicle, enabling the constant, up-to-date identification of such objects and the generation of virtual images oriented toward them.

[0013] One idea is to combine a central HUD unit, which, via its projection and imaging optics (e.g. mirror optics), enables a high-quality contact-analog display with a suitable virtual image distance and / or orientation, with one or more disc root displays, which ensure a seamless horizontal and / or vertical extension of this virtual display and can be located, for example, on the upper housing of the central HUD unit to the left and right (in the vehicle's transverse direction) and / or to the rear and front (in the vehicle's longitudinal direction) of its beam outlet opening and are directly adjacent to / connect to it, so that no gaps arise at the corresponding transition points in the composite virtual image.

[0014] For a high-quality contact-analog virtual representation, a first virtual image distance that is close to the actual distance of the real objects outside the vehicle, which are augmented with this image content, can be particularly suitable. For example, excellent results can be achieved with an image distance of around 2 m from the occupant's eyes. Depending on the application, greater image distances, for example up to around 10 m, can also be suitable so that the eye has to refocus as little as possible between the real object and the virtual image. Due to the limited space in the instrument panel, however, the optics required for this purpose can only cover a small angular range in the driver's field of vision, for example around 10° in the horizontal direction.Expanding the central HUD unit beyond this angular range is not possible because this would lead to installation space collisions with other essential elements of the vehicle, such as its supporting structure or the air conditioning system, etc. However, this angular range is barely sufficient to encompass, for example, lane markings or a hazard lurking at the side of the road, such as an animal or person, in a coherent virtual image.

[0015] The present invention is based on a surprising finding that, when a contact-analog overlay is seamlessly extended in the vehicle's transverse and / or vertical directions by virtual display content with a different image distance, which is feasible with a windscreen root display, the occupant's eye perceives this display content in the composite virtual image as a natural continuation of the central image. In this way, a lateral and / or vertical extension of the angular range of a contact-analog overlay by at least 3° to the left and right, or up and down, is possible.

[0016] According to one embodiment, the central HUD unit is designed to display the central display content in a virtual image plane that is inclined or horizontal with respect to the vertical direction. For this purpose, the surface of the image generator in which the display content is generated is oriented at a corresponding angle of inclination to an optical axis of the central HUD unit. For example, a tilted virtual image can be generated in this way with an image distance increasing from bottom to top of approximately 2-4 m for the lower image edge and approximately 6-20 m for the upper image edge. This embodiment enables a virtual overlay with a depth effect that resembles real objects outside the vehicle, such as a section of road, and thereby reinforces the contact-analog effect.

[0017] In principle, any technology is suitable for the imager of the central HUD unit, in particular a light-transmitting or light-emitting flat panel display, a projector-based imager, or a waveguide-based display. The respective extension display can, for example, be designed as a light-transmitting or light-emitting flat panel display, in particular a liquid crystal display (LCD) or µLED display.

[0018] According to one embodiment, the above-mentioned imaging and / or projection optics in the central HUD unit comprise at least one concave mirror. The respective concave mirror can, for example, be designed to perform a deflecting, image-magnifying, imaging, collimating, and / or image-correcting optical function. Alternatively or additionally, the imaging and / or projection optics can also comprise other optical elements, such as lenses, plane mirrors, or holographic-optical elements, with these or other optical functions.

[0019] According to one embodiment, the central HUD unit and / or each of the extension displays are configured for autostereoscopic image generation to further enhance the contact-analog perception of the composite virtual image through this additional depth effect. For this purpose, known techniques for creating a stereoscopic effect can be used in the imager of the central HUD unit or in the extension displays, for example. These techniques are based on generating different display contents for each eye from a perspective perspective and associated parallax barriers in the form of a stripe mask or a lenticular grid, etc., to direct corresponding portions of the total projection light generated to only one eye of the occupant.

[0020] In particular, the projection unit can be designed for installation in a vehicle's instrument panel. This allows the virtual image to be projected into the field of vision of a driver (or passenger), for example.

[0021] According to a further aspect, a method for operating a head-up display (hereinafter referred to as a hybrid HUD) in a vehicle with the projection unit presented herein is provided. The method comprises the following steps: - Determining at least one real object located outside the vehicle, which extends into a field of vision of the occupant that can be virtually covered by both the central HUD unit and at least one of the extension displays and is to be enhanced by virtual image content in a contact-analog manner; and - Controlling the central HUD unit and at least one of the extension displays to generate corresponding display contents, which are combined via reflection on the reflection disc to form a seamlessly composite virtual image.

[0022] In particular, this real object can be a section of road in front of the vehicle, the areas of which are to be contact-analogously enhanced (such as a lane or roadway boundary) extend to the left and / or to the right and / or upwards and / or downwards beyond the area that can be covered by the central HUD unit.

[0023] According to a further aspect, a control unit is provided that is designed and configured to automatically execute this method. For this purpose, a corresponding computer program (software) can be loaded into a processor of the control unit and run during operation of the hybrid HUD.

[0024] According to a further aspect, the above-mentioned hybrid HUD is provided for a vehicle. The hybrid HUD comprises the above-mentioned projection unit and a reflection disc arranged in the beam path of a projection light emitted by the projection unit. The reflection disc is arranged / is to be arranged in the field of vision of a vehicle occupant and is configured such that it reflects this projection light to a spatial area (eyebox) in the vehicle interior predetermined for their eyes, thereby superimposing the aforementioned composite virtual image into their field of vision.

[0025] The hybrid HUD further comprises the above control unit, which is designed to control the central HUD unit and the extension display(s) to carry out the above method.

[0026] According to a further aspect, the above-mentioned vehicle is provided. It comprises a passenger compartment and a vehicle window that at least partially defines it, in particular a windshield. Furthermore, the hybrid HUD presented herein is provided in the vehicle, the projection unit of which is arranged in the passenger compartment, in particular in an instrument panel arranged below the windshield, and the reflection window of which is designed as a section of said vehicle window or as a combiner window arranged in the passenger compartment.

[0027] The above aspects of the invention and their embodiments and specific configurations are explained in more detail below with reference to the examples shown in the accompanying drawings. The drawings are predominantly schematic and therefore not to scale. They show: Fig. 1 is a longitudinal sectional view of a vehicle with a hybrid HUD according to an embodiment of the invention, which is configured to provide a contact-analog display of a composite virtual image for a driver via reflection on a windshield; Fig. 2 a perspective view of the hybrid HUD of the Fig. 1 viewed from the passenger compartment in the direction of travel, showing the outlines of its central HUD unit and both extension displays, which are installed invisibly for the occupants in or under the upper surface of the instrument panel; and Fig. 3 a perspective view of the vehicle of the Fig. 1 and Fig. 2 from the driver's perspective with an example of a virtual image generated by the hybrid HUD in contact analogue form.

[0028] All of the various embodiments, variants and specific design features of the projection unit, the method, the control unit, the hybrid HUD and the vehicle according to the above aspects of the invention mentioned above in the description and in the following claims can be implemented in the Fig. 1-3, in particular alternatively or in addition to the features shown therein. They will therefore not be repeated again below. The same applies accordingly to the definitions and effects already given above with regard to individual features that are described in Fig. 1 to 3 are shown.

[0029] Fig. 1 shows, in a highly simplified schematic longitudinal sectional view, an embodiment of a vehicle 1 with a hybrid HUD 2 presented therein, which is used to generate a virtual image VZ+VL+VR that is seamlessly combined in the vehicle transverse direction (cf. Fig. 3 from a different perspective) in the field of vision of a driver of vehicle 1.

[0030] Vehicle 1 in this example is a motor vehicle that is Fig. 1 is only indicated by its windshield 3, which serves as a reflection disc of the hybrid HUD 2. Below it, in an instrument panel 4 (not shown in detail), a projection unit 5 of the hybrid HUD 2 is arranged. The driver is only indicated by a spatial area E (eyebox) in the vehicle interior intended for his eyes, from which he can see the composite virtual image VZ+VL+VR in the intended quality.

[0031] The projection unit 5 consists of a central HUD unit 5a and, purely as an example, two extension displays 5b and 5c arranged on the left and right of its upper housing (not shown separately) (in the longitudinal section plane of the Fig. 1 not included, therefore only dashed; cf. Fig. 2) together.

[0032] The central HUD unit 5a contains an image generator 6, in this example an LCD (liquid crystal display), which is designed to generate a central display content. The light beam L emanating from its display surface is indicated in simplified form by a central beam, which leads approximately from the center of this display surface to the center of the eyebox E. In the further beam path of the light beam L, the central HUD unit 5a comprises a concave mirror 7. The image generator 6 and the concave mirror 7 are arranged and designed such that the light beam L leaves the central HUD unit 5a in a suitable shape and direction in order to then be reflected by the windscreen 3 to the eyebox E and thus present the central display content to the driver in a contact-analog manner as a central virtual image VZ with the desired display properties. In this example, the image generator 6 orits display surface is arranged at an oblique angle of attack with respect to the said central beam in order to generate a correspondingly obliquely inclined, almost lying virtual image plane at a distance of 4 m (lower image edge) to 9 m (upper image edge) from the eyebox E. The angle of attack of the image generator 6 can also be different than in . Fig. 1, for example to create a nearly vertically aligned central virtual image VZ.

[0033] The extension displays 5b and 5c are located directly opposite the front screen 3, ie without any further optics in between, whereby their display images are reflected on the front screen 3 as virtual extension images VL and VR (in Fig. 3 better seen) seamlessly connect to the central virtual image VZ on the left and right, thereby expanding it into a composite contact-analog virtual image VZ+VL+VR in the driver's field of vision. Alternatively or additionally, one or two extension displays can be arranged in a similar manner in the longitudinal direction of the vehicle at the front or rear on the aforementioned upper housing of the HUD unit 5a in order to seamlessly and also contact-analogously expand its central virtual image VZ downwards and / or upwards.

[0034] Furthermore, the projection unit 5 comprises a control unit 8, which is configured to carry out a method according to an embodiment of the invention and is designed to correspondingly control the extension displays 5b and 5c and the image generator 6. The method comprises, among other things, the following steps: - Determining at least one real object located outside the vehicle 1, which extends in an area in the driver's field of vision that can be virtually covered by both the central HUD unit 5a and at least one of the extension displays 5b / 5c and is to be enhanced by virtual image content in a contact-analog manner; and - Controlling the central HUD unit 5a and the extension displays 5b / 5c to generate corresponding display contents, which are seamlessly combined to form a composite virtual image VZ+VL+VR via reflection on the windscreen 3 in the transverse direction of the vehicle.

[0035] Fig. 2 shows a perspective view of the hybrid HUD 2 in the vehicle 1 of the Fig. 1 with a view from the passenger compartment in the direction of travel. For clarity, the outlines of the central HUD unit 5a and both extension displays 5b and 5c are schematically indicated in addition to the windscreen 3: In fact, the projection unit 5 (cf. Fig. 1) is installed invisibly for the occupants in and below an upper side 9 of the instrument panel 4. To further clarify the positions and sizes of the central HUD unit 5a and both extension displays 5b and 5c in the vehicle 1, Fig. 2 also shows a steering wheel 10, a so-called black print 11 (darkening) along the lower edge of the windshield 3, and several air outlet openings 12 of an air conditioning system installed in the instrument panel 4. Since the hybrid HUD 2 is designed for AR applications, a transparent area of ​​the windshield 3 located above the black print 11 is used for the virtual image display.

[0036] Due to the Fig. 2 indicated vertical size of the central HUD unit 5a, which is responsible for its optical arrangement according to Fig. 1 is required, there is no space inside the instrument panel 4 for an extension of the central HUD unit 5a with this optics to the left and right without causing installation space collisions with a supporting structure (not shown), the air conditioning system, and other vehicle elements. With extension displays 5b and 5c directly adjoining an upper housing of the central HUD unit 5a, which, as window root displays, require comparatively little installation space in the vehicle height direction, the central virtual image VZ (see Fig. 1 and Fig. 3) be extended to the left and right in the driver’s field of vision without loss of the contact-analog effect, as in Fig. 3 illustrates this with an example: Fig. 3 shows a perspective view of the vehicle 1 of the Fig. 1 and Fig. 2 from the driver's perspective with an example of a composite virtual image VZ+VL+VR generated by the hybrid HUD 2 in a contact-analog manner. In this example, the above method enriches a road section 14 located in front of the vehicle 1 with virtual image content in order to clearly display a suitable lane change trajectory T and associated lane markings M to the driver.

[0037] How to Fig. 3, the virtual display area required for displaying the lane change trajectory T for the lane markings M (for example, on a snowy or unmarked roadway) extends to the left and right beyond the angular range in the driver's field of vision that can be covered by the central HUD unit 5a alone and, purely by way of example, includes a horizontal angle of approximately 10° and a vertical angle of approximately 3°. As proposed herein, the required contact-analog lane markings M are achieved by virtual extension images VL and VR using the above extension displays 5b and 5c, which are shown in Fig. 3 purely by way of example, each cover an angular range of approximately 3°x3°, which on the left and right seamlessly connects to the above central angular range of 10°×3° in which the central virtual image VZ is displayed. List of reference symbols 1 vehicle 2 Hybrid HUD 3 Windscreen 4 Instrument panel 5 Projection unit 5a central HUD unit 5b, 5c extension display 6 imagers 7 concave mirrors 8 Control unit 9 Top of the instrument panel 10 Steering wheel 11 Black printing 12 air outlet openings 14 road section L bundle of light rays E Eyebox VZ central virtual image VL, VR virtual augmentation images T Lane change trajectory M lane markings QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 11 2019 003 420 T5

[0003] US 2023 / 0118314 A1

[0005] JP 2017-140906 A

[0006]

Claims

[1] Projection unit (5) for a head-up display (2) for use in a vehicle (1), comprising: - a central HUD unit (5a) with an image generator (6) for generating a light beam (L) with a central display content and a projection and / or imaging optics configured in its beam path such that the light beam (L) leaves the central HUD unit (5a) in a predetermined shape and direction towards a reflection disc arranged in the field of vision of a vehicle occupant in order to display this display content in his field of vision via reflection on the reflection disc at a predetermined first virtual image distance; and - one or more extension displays (5b, 5c), the display surfaces of which are each directly opposite the reflection disc and are connected to the central HUD unit (5a) in such a way that their display images extend the central display content to the left, right, top and / or bottom seamlessly, albeit at a shorter second virtual image distance, to form a composite virtual image (VZ+VL+VR) via reflection on the reflection disc; - wherein the projection unit (5) is designed and configured to display the composite virtual image (VZ+VL+VR) oriented toward real objects outside the vehicle (1). [2] Projection unit (5) according to claim 1, wherein - the central HUD unit (5a) is designed to display the central display content in a virtual image plane that is inclined or lying obliquely with respect to the vertical direction, in that an image-generating surface of the image generator (6) is oriented at a correspondingly predetermined angle of inclination to an optical axis of the central HUD unit (5a). [3] Projection unit (5) according to claim 1 or 2, wherein - said projection and / or imaging optics comprises at least one concave mirror (7). [4] Projection unit (5) according to one of the preceding claims, wherein - the central HUD unit (5a) and / or each of the extension displays (5b, 5c) are designed for autostereoscopic image generation. [5] Projection unit (5) according to one of the preceding claims, which - is designed for installation in an instrument panel (4) of the vehicle (1), in particular to display the virtual image in the field of vision of a driver. [6] Method for operating a head-up display (2) in a vehicle (1) with a projection unit (5) according to one of the preceding claims, comprising the steps: - Determining at least one real object located outside the vehicle (1) which extends in the field of vision of the occupant in an area that can be virtually covered by both the central HUD unit (5a) and at least one of the extension displays (5b, 5c) and is thereby to be enhanced in a contact-analog manner; and - Controlling the central HUD unit (5a) and at least one of the extension displays (5b, 5c) to generate corresponding display contents which are complemented by reflection on the reflection plate to form a seamlessly composite virtual image (VZ+VL+VR). [7] Method according to claim 6, wherein - said real object is a road section (14) located in front of the vehicle (1), the areas of which are to be contact-analogously enhanced with virtual image content extending to the left, right, bottom and / or top beyond the area in the field of vision of the occupant which can be covered by the central HUD unit (5a). [8] Control unit (8) which is designed and arranged to automatically carry out the method according to claim 6 or 7. [9] Hybrid HUD (2) for a vehicle (1), comprising: - a projection unit (5) according to one of claims 1 to 5; - a reflection disc arranged in the beam path of a projection light emitted by the projection unit (5) as a whole, which reflection disc is arranged and designed in the field of vision of a vehicle occupant such that it reflects this projection light to an eyebox (E) predetermined for his eyes, whereby the said composite virtual image (VZ+VL+VR) is superimposed into his field of vision; and - a control unit (8) according to claim 8, which is designed to control the central HUD unit (5a) and each extension display (5b, 5c) in order to carry out the method according to claim 6 or 7. [10] Vehicle (1), in particular a motor vehicle, with mutually perpendicular longitudinal, transverse and height directions of a vehicle-fixed Cartesian coordinate system, comprising: - a passenger compartment with a vehicle window which at least partially delimits it, in particular a windscreen (3); and - a hybrid HUD (2) according to claim 9, whose projection unit (5) is arranged in the passenger compartment, in particular in an instrument panel (4) arranged below the windscreen (3), and whose reflection disc is designed as a section of said vehicle windscreen or as a combiner disc arranged in the passenger compartment.

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