Projection unit for a field of view display device with a contactless, conveyor-type display surface, in particular for a vehicle, field of view display device and vehicle with such a

Abstract

Projection unit (7) for a field of view display device (2) which is designed to display a virtual image (V) via reflection on a reflection plate arranged in the field of view of a user, in particular a vehicle window (4), comprising: - at least one rectangular imaging display surface (8) which is to be arranged in or under an upper side of an instrument panel (5) of a vehicle (1) and is formed by a mechanically movable belt (10) with at least one light source strip (9) fastened thereon, which extends transversely to its belt movement direction (R) and carries light sources arranged in a row in its direction of extension, which can be controlled contactlessly in synchronism with the belt movement and independently of one another to generate a desired display content in the display surface (8); and - at least one receiver board (16) fastened to the belt (10) and electrically connected to the light sources, and at least one associated transmitter board (15) which is arranged in the projection unit (7) in a stationary manner and mechanically decoupled from the belt (10) and is designed for contactless energy and video signal transmission to the light sources via the at least one receiver board (16).

Description

[0001] The invention relates to a projection unit for a head-up display (HUD) device, which is also known as a head-up display (HUD) and can be used in particular in a motor vehicle or other land, air, or water vehicle. Head-up display devices of this type are designed to generate a virtual image superimposed into the user's field of vision via reflection from a vehicle window, in particular a windshield, or from a combiner window provided specifically for this purpose and arranged in the user's field of vision. The invention also relates to such a head-up display device and to a vehicle equipped therewith.

[0002] Particularly in motor vehicles, it is well known that a head-up display (HUD) overlays information such as speed limit 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 information. To generate the display content, a conventional HUD comprises a projection unit located below the windshield inside the instrument panel.This typically includes a display for generating a light beam with the desired display content, as well as imaging and projection optics, usually with a concave mirror, to shape the light beam and direct it onto the windshield so that it is reflected back to the driver's eyes, allowing them to see the virtual image at a suitable size and distance beyond the reflection screen. However, the dimensions of the concave mirror scale linearly with the size of the virtual display area, which severely limits its size.

[0003] Alternatively, for applications requiring a significantly larger virtual display area, a HUD design with a large-area display extending directly opposite the windshield on the upper surface of the instrument panel is known. This is particularly suitable for future fully automated or autonomous vehicles, which are intended to operate without user input from the driver, so that the associated entertainment systems in the passenger compartment are becoming increasingly important. For example, with a HUD of this type, one would want to display additional information to a driver and / or a passenger across the entire width of the windshield, depending on the situation and the external environment, and, if necessary, also display a continuous panoramic virtual image. For this to happen, the image-generating display would have to extend across the entire width of the windshield.

[0004] To meet the high intensity requirements for display light reflected in the transparent area of the windshield in broad daylight, an LED display would be more suitable than a liquid crystal display because high intensity losses in the liquid crystal layer are unavoidable. However, such a large display area would require an excessive number of LEDs (several million), which in turn would have a significant impact on the vehicle's energy balance and associated greenhouse gas emissions. A possible display size for a panoramic view is 1200 mm (length) by 300 mm (width), for a 4:1 ratio. Using a conventional display, this would require the installation of approximately 2,000,000 LEDs. These are arranged in approximately 1920 columns across the width of the HUD display. This large number of LEDs would generate greenhouse gas emissions of more than 1.2 CO2 equivalents.

[0005] Rotating display devices with a circular display surface that can be generated by rotation are known in the prior art, for example for design and toy items or greeting cards, as described, for example, in US Pat. No. 9,190,028 B2 or EP 4 030 412 A1. Such a rotating display device comprises a fixed motor, to whose motor shaft a rotating unit is attached, such that the rotating unit is rotated by the motor. The rotating unit is designed as at least one rod-shaped arm arranged in the radial direction, with an LED strip attached longitudinally to the arm. Suitable rotation or position sensors are provided to synchronize the LED control with the rotation of the arm. Depending on the embodiment, this display device can, for example, comprise a single radial arm, two individual radial arms spaced 180° apart, or four individual radial arms spaced 90° apart.Similarly, WO 2019 / 023489 A1 discloses an apparatus and method for displaying an image generated by the emission or reflection of light by rotating elements such as fan blades.

[0006] Furthermore, WO 99 / 35634 A1 discloses a rotating display arrangement with a round, elongated, oval, or polygonal cross-section and a plurality of display elements evenly distributed on a moving belt forming a peripheral surface of the arrangement. To realize several different radiation directions, partition walls with different inclinations can be provided between the individual display elements. US 2004 / 0212572 A1 discloses a similar display arrangement, wherein a belt is wound around one or more parallel axes of rotation arranged at the corners of a correspondingly polygonal cross-section.The energy and signal transmission required to generate the display to one or more LED strips that are attached to the belt and thus moved like a conveyor belt during operation is carried out by means of a communication unit that has protruding metallic or other type of solid-state contacts that engage with corresponding contact rings on the surface of one of the rotating axes, thereby establishing electrical contact with it. Metal strips are provided at corresponding positions in the moving belt to ensure electrical contact with the contact rings of the rotating axis. However, due to the rapid and frequent rotation of the belt, such sliding contacts can quickly become worn. This would then require regular replacement of the sliding contacts, for example, which entails ongoing costs for the corresponding servicing.

[0007] The object of the present invention is to provide an alternative and / or improved design concept for a field-of-view display device with regard to energy balance, robustness, and / or cost-effectiveness, which also enables the generation of a large-area virtual image, for example, for a panoramic display. In particular, this field-of-view display device should be suitable for integration into a vehicle and for virtual display via reflection on its windshield.

[0008] This object is achieved by a projection unit according to claim 1, as well as a visual field display device containing the same, 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 the following description for the projection unit also apply to the visual field display device and the vehicle, and vice versa.

[0009] According to a first aspect, a projection unit for a field-of-view display device is provided, which can be designed in particular for use in a vehicle. The field-of-view display device is designed to project a virtual image into a user's field of vision via reflection from a reflective panel arranged in the user's field of vision, in particular a vehicle window. It can be designed, for example, as a head-up display (HUD).

[0010] During operation of the field-of-view display device, the projection unit is designed to generate a projection light beam with a desired display content and project it onto the aforementioned reflective disc, whereby the desired virtual image appears to the user as floating beyond the reflective disc. The user can be, in particular, a driver and / or front passenger, but also other vehicle occupants.

[0011] For this purpose, the projection unit comprises at least one rectangular imaging display surface, which can be designed in particular for arrangement in or beneath the upper side of the instrument panel or the parcel shelf of the vehicle. The display surface is designed according to a conveyor belt concept to save material and energy resources. For this purpose, it comprises a mechanically movable belt (also referred to herein as a "conveyor belt") with at least one light source bar attached thereto, which extends transversely to the direction of belt movement and carries light sources, for example, LEDs, arranged in a row along its extension direction. The respective light source bar can, for example, have the height (or width) of the desired display area and, by means of the belt movement, can be moved quickly back and forth across the entire width (or height) of the desired display area, or can be "rotated" in a constant direction of movement.

[0012] To generate a desired display content on the display surface, the light sources can be controlled contactlessly, synchronously with the belt movement and independently of each other. For this purpose, at least one receiver board is mounted on the belt and electrically connected to the light sources, as well as at least one associated transmitter board. The transmitter board is arranged in a fixed position in the projection unit, mechanically decoupled from the belt, and is designed for contactless power and video signal transmission to the light sources via the at least one receiver board.

[0013] One idea behind this projection unit is to replace a large, high-intensity, image-generating display surface in a field-of-view display device, such as a HUD, which can be designed for use in a vehicle, with a conveyor-type display surface known from other applications. This allows the number of LEDs required in the HUD display surface to be significantly reduced so that, despite the additional rotary drive consumption for the conveyor belt, a significant improvement in the vehicle's energy balance and thus a reduction in greenhouse gas emissions can be achieved. If the vehicle includes a battery-electric drive, a correspondingly greater range can be achieved.Furthermore, this display surface is easily scalable by adding additional rectangular display surfaces of this type, allowing it to be flexibly adapted to the geometric requirements of various applications. Another idea involves a completely contactless power and signal supply for the light sources arranged on the conveyor belt. This eliminates the need for sliding contacts, resulting in lower rolling resistance for the conveyor belt overall, allowing for a longer operating time compared to the display devices mentioned above. This also allows for greater robustness and reliability of the device, which is particularly important for use in vehicles.

[0014] According to one embodiment, the projection unit comprises two parallel belt rotation axes for each rectangular display surface, extending along its two opposite edges, as well as a rotary drive configured to rotate at least one of the two belt rotation axes. The belt forms a loop that is stretched between and wound around the two belt rotation axes, with the at least one belt rotation axis, which can be rotated by the rotary drive, being configured to entrain the belt to generate the aforementioned belt movement. This can be, for example, a belt conveyor. The light source strips can, for example, extend parallel to the rotation axes.

[0015] In particular, in this embodiment, the at least one receiver board can be attached to the outside of the belt. Alternatively, it can also be integrated into the belt, for example, and much more. The at least one transmitter board is arranged in an empty space defined by the loop in such a way that it has no mechanical contact with the belt or the belt's rotation axes. This makes it possible to achieve the most space-saving transmitter arrangement possible. In addition, the distance to the light source strips or to the receiver boards can be minimized and, in particular, both sides of the loop can be supplied with data and energy in order to further increase the frame or data rate, for example. Alternatively or additionally, one or more transmitter boards can also be arranged elsewhere in the projection unit, for example outside the belt loop on the side facing away from the user, and much more.

[0016] For example, the contactless transmission of power occurs inductively, and the transmission of video signals occurs contactlessly via NFC ("Near-Field Communication"), although other data transmission standards can also be used. Accordingly, at least some of the aforementioned transmitter and receiver boards can be configured for inductive power supply to the light sources (in other words, for contactless energy transmission through electromagnetic induction), and at least some of the transmitter and receiver boards can be configured for contactless video signal transmission via NFC. For this purpose, the necessary electrical and electronic components such as capacitors, receiver coils, antennas, etc., are arranged on the aforementioned boards.

[0017] The transmitter and / or receiver boards can in particular be evenly distributed along the band and / or connected to each other.

[0018] The receiver boards can, for example, be integrated into the strips themselves. Alternatively or additionally, the receiver boards can also be arranged on the strip next to the at least one light source strip or between the light source strips. With a higher number of transmitter and / or receiver boards, a correspondingly higher data rate for the video signal transmission can be achieved, for example.

[0019] According to one embodiment, the belt has a plurality of slats arranged on the outside and, for example, evenly distributed along the belt's direction of movement. The slats extend parallel to one another and to the light source strips and are designed to impose a predetermined radiation direction on the projection light generated by the light source strips and / or to shield the display surface in other directions. For this purpose, the slats can be spatially oriented, i.e., aligned, essentially parallel to one another across the entire display surface. They can, for example, be light-absorbing or coated to block light rays in directions other than the aforementioned radiation direction.

[0020] Furthermore, the projection unit can comprise a cover plate that extends along the imaging display surface in the beam path of the projection light emanating from it and is designed to transmit the projection light essentially without loss, while at least partially sealing and protecting the projection unit from the outside. The cover plate can serve, among other things, to prevent a vehicle occupant from interfering with elements of the display surface that are moving in a conveyor belt-like manner and can optionally be equipped with further mechanical and / or optical functions. It can be made of any suitable material, for example, glass or transparent plastic such as acrylic glass, etc.

[0021] According to a further aspect, the above-mentioned field of view display device is provided, which, in addition to a projection unit presented herein, further comprises a reflection plate mentioned above, which can be formed, for example, by a vehicle window or designed as a specially provided combiner plate. The reflection plate is arranged in the beam path of the projection light emitted by the projection unit. It is reflective towards the user and can, in particular, be at least partially transparent to the ambient light incident from behind, so that the virtual image is superimposed on the real environment observed by the user through the reflection plate.The reflection disc is arranged and designed in the user's field of vision in such a way that it reflects the projection light to an eyebox predetermined for the user's eyes, so that the display content can be presented to the user in the form of a virtual image beyond the reflection disc.

[0022] In the embodiment described above, the slats can ideally extend approximately parallel to the reflection disc and, when installed in a vehicle, for example, to its windscreen in order to conceal the view of the light source strips from the users or occupants and to emit the projection light only in the required direction towards the reflection disc.

[0023] According to a further aspect, the above vehicle is provided, which may, for example, be a motor vehicle or any other land, air, or water vehicle. It has a passenger compartment and a vehicle window that at least partially delimits it towards the outside. The vehicle window can, for example, be a windshield with an instrument panel arranged underneath it, or a rear window with a parcel shelf arranged underneath it, which delimit the passenger compartment to the front and rear, respectively, in the longitudinal direction of the vehicle. Unless otherwise stated, all spatial orientation terms used herein, such as "horizontal," "vertical," "above," "below," "beneath," "front," "rear," "left," "right," etc., refer to the usual vehicle-fixed Cartesian coordinate system with mutually perpendicular longitudinal, transverse, and vertical directions of the vehicle.Furthermore, the vehicle comprises the above-mentioned field of view display device, the projection unit of which is arranged in the passenger compartment, in particular in or under an upper side of the instrument panel or parcel shelf, and the reflection disc of which is designed as part of the vehicle window or as a combiner disc arranged separately in the passenger compartment.

[0024] In particular, the windshield can be bounded to the left and right in the vehicle's transverse direction by an A-pillar of the vehicle, and the projection unit and its imaging display surface can be arranged in or below the upper side of the instrument panel in such a way that the windshield serves as a reflection plate of the field of view display device, at least over a large part of its extension in the vehicle's transverse direction. This makes it possible, in particular, to create a panoramic virtual display for the driver and / or front passenger. For this purpose, in particular, several rectangular display surfaces of the type presented here can be arranged next to one another to create a larger total area.

[0025] The above aspects of the invention and their embodiments and specific configurations are explained in more detail below with reference to examples shown in the accompanying drawings. The drawings are purely schematic and therefore not to scale. They show: Fig. 1 shows a section of a vehicle with a field of view display device according to an embodiment of the invention in a vertical longitudinal section; Fig. 2a is a cross-sectional view of an imaging display surface of the field of view display device of the Fig. 1; Fig. 2b a plan view of the imaging display surface of the Fig. 2a; and Fig. 3 is a cross-sectional view of another example of the imaging display surface of the field of view display device of Fig. 1, which additionally shows at least part of the transmitter and receiver boards intended for contactless power and video signal transmission.

[0026] All the various embodiments, variants and specific design features of the projection unit, the field of view display device 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 to 3, in particular alternatively or in addition to the features shown therein. Therefore, they will 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 the Fig. 1-3 are shown.

[0027] Fig. Figure 1 shows, in a highly simplified schematic representation in a vertical longitudinal section, a section of a vehicle 1 with a field of view display device 2 according to an exemplary embodiment of the invention. The field of view display device 2 is embodied here purely by way of example as a head-up display (HUD).

[0028] The field of view display device 2 is designed to generate a virtual image V in the field of view of a user, for example a driver of the vehicle 1, which in the vertical longitudinal sectional view of the Fig. 1 is indicated only by his eyes 3 and a designated eyebox E in the passenger compartment of the vehicle 1. (As usual, the eyebox is understood here as a spatial area designated for the eyes of a user of the field of view display device 2, from which he can see the virtual image V in the intended display quality.) The vehicle 1 is purely exemplary of a motor vehicle. It is in Fig. 1 is indicated solely by its windscreen 4, an instrument panel 5 extending underneath it (not shown in detail) and a roof liner 6 extending above it.

[0029] The field of view display device 2 comprises a projection unit 7, which in this example is arranged below the windshield 4 in the instrument panel 5. The projection unit 7 is designed and arranged to generate and output a projection light beam L (hereinafter also referred to as "projection light") with the desired display content in the direction of the windshield 4, so that the projection light L is reflected from the windshield 4 to the user eyebox E, and the user thereby sees the virtual image V when looking into the windshield 4.

[0030] For this purpose, the projection unit 7 has a rectangular imaging display surface 8, which is arranged with its surface in or almost directly below an upper side of the instrument panel 5 and in Fig. 2a-2b and Fig. 3 is shown in more detail. The projection light L is in Fig. 1 is indicated solely by its central beam, which leads from a center of the imaging display surface 8 to a center of the eyebox E. The projection unit 7 can optionally comprise a cover plate 11, which at least partially covers and protects the display surface 8 towards the front plate 4 and thereby transmits the projection light L emanating from it largely without loss.

[0031] Fig. 2a-2b show in a cross-sectional view ( Fig. 2a) and a top view ( Fig. 2b) a basic structure of the imaging display surface 8 of the projection unit 7 of the Fig. 1. In this example, the rectangular imaging display surface 8 is created purely by way of example by a total of two light source strips 9, which are arranged equidistantly on a moving belt 10 (conveyor belt). With the aid of the conveyor belt 10, for example a belt conveyor, the light source strips 9, which in this example have the height of the desired display area measured in the longitudinal direction of the vehicle, are quickly moved back and forth across the entire width of the desired display area measured in the transverse direction of the vehicle and / or constantly rotate in the same belt movement direction R. Each light source strip 9 carries light sources (not separately shown) arranged in a row in its longitudinal direction, in this example LEDs, which can be controlled independently of one another and synchronously with the belt movement to generate images in the imaging display surface 8.

[0032] To generate this conveyor belt movement, the projection unit 7 comprises two parallel belt rotation axes 12, which extend along two opposite edges of the rectangular display surface 8, as well as a rotary drive (not shown) which is designed to rotate at least one of the two belt rotation axes 12. As best shown in the cross-sectional view of the Fig. 2a, the band 10 forms a loop that is stretched between and wound around the two band rotation axes 12. In this example, both band rotation axes 12 have gear-like projections for driving the band 10 during their rotation. The band 10 has complementary projections on its inner surface facing the rotation axes 12, which engage positively between the gear-like projections of the rotation axes.

[0033] For the conveyor belt 10, only a powerful electric rotary drive is required. Furthermore, the number of LED strips 9 used can be reduced to a minimum. This allows the overall energy balance of the arrangement to be optimized and—in the case of a battery-electric vehicle—the vehicle's range to be increased. To increase the operating time and robustness of the arrangement, the power and video signal transmission to the LED strips 9 is contactless, as shown below using the Fig. 3 explained.

[0034] Fig. Fig. 3 shows a cross-sectional view of another example of the rectangular imaging display surface 8 of the field of view display device 2 of the Fig. 1. To avoid repetition, only differences or additional features are described below that have not already been mentioned above with regard to Fig. 2a-2b. Thus, in Fig. 3 a total of four or more (not all shown) light source strips 9 are arranged on the conveyor belt 10, which can in particular be evenly distributed along the belt 10. Optionally, Fig. 3, a plurality of slats 14 are additionally arranged on the outside of the belt 10, which slats can, for example, also be evenly distributed along the belt movement direction R, as shown. All slats 14 in the display surface 8 are spatially oriented in the same way to each other in order to project projection light L (cf. Fig. 1) in a predetermined radiation direction to the front screen 4 and to efficiently shield other viewing and radiation directions.

[0035] In this example, the power is transmitted inductively, and the video signals are transmitted contactlessly via NFC ("Near Field Communication"). For this purpose, appropriately designed transmitter boards 15 are provided inside the conveyor belt 10, i.e., in an empty space 17 created thereby, and corresponding receiver boards 16 are provided on the outside of the conveyor belt 10. The receiver boards 16 are electrically connected to the light source strips 9 and are equipped with the capacitors, receiver coils, antennas, etc. designed for the aforementioned transmission. By providing multiple transmitter and receiver boards 15, 16, for example, the data rate of the signal transmission can be increased, wherein the multiple transmitter boards 15 can be arranged at a sufficient distance from one another in the space 17 to avoid crosstalk. Fig.In Figure 3, for the sake of simplicity, receiver boards 16 are shown only on one side of the conveyor belt 10, which faces the user and serves as a display surface 8. In particular, the other conveyor belt side can be configured similarly, ie, have the same number of light source strips 9 and receiver boards 16. List of reference symbols 1 vehicle 2 Field of view display device 3 User's eye 4 Windscreen 5 Instrument panel 6 headliner 7 Projection unit 8 imaging display area 9 Light source bar 10 moving belt, also called assembly line 11 Cover plate 12 Belt rotation axis 14 slats 15 Transmitter board 16 Receiver board 17 gap E User's eyebox L Projection light (beam) R Belt movement direction V virtual image

Claims

[1] Projection unit (7) for a field of view display device (2) which is designed to display a virtual image (V) via reflection on a reflection plate arranged in the field of view of a user, in particular a vehicle window (4), comprising: - at least one rectangular imaging display surface (8) which is to be arranged in or under an upper side of an instrument panel (5) of a vehicle (1) and is formed by a mechanically movable belt (10) with at least one light source strip (9) fastened thereon, which extends transversely to its belt movement direction (R) and carries light sources arranged in a row in its direction of extension, which can be controlled contactlessly in synchronism with the belt movement and independently of one another to generate a desired display content in the display surface (8); and - at least one receiver board (16) fastened to the belt (10) and electrically connected to the light sources, and at least one associated transmitter board (15) which is arranged in the projection unit (7) in a stationary manner and mechanically decoupled from the belt (10) and is designed for contactless energy and video signal transmission to the light sources via the at least one receiver board (16). [2] Projection unit (7) according to claim 1, - further comprising, for each rectangular display surface (8), two parallel strip rotation axes (12) extending on its two opposite edge sides, and a rotary drive designed to rotate at least one of the two strip rotation axes (12); - wherein the band (10) forms a loop which is stretched between the two band rotation axes (12) and wound around them, wherein the at least one band rotation axis (12) rotatable by the rotary drive is designed to entrain the band (10) to generate the said band movement. [3] Projection unit (7) according to claim 2, wherein - the at least one receiver board (16) is attached to the outside of the band (10); and / or - the at least one transmitter board (15) is arranged in a space (17) delimited by the loop, such that it has no mechanical contact with the band (10) and the band rotation axes (12). [4] Projection unit (7) according to one of the preceding claims, wherein - at least some of the transmitter and receiver boards (15, 16) are designed for inductive power supply of the light sources. [5] Projection unit (7) according to one of the preceding claims, wherein - at least some of the transmitter and receiver boards (15, 16) are designed for contactless video signal transmission by near-field communication. [6] Projection unit (7) according to one of the preceding claims, wherein - the transmitter and / or receiver boards (15, 16) are evenly distributed along the band (10); and / or - the receiver boards (16) are arranged on the strip (10) next to the at least one light source strip (9) or between the light source strips (9). [7] Projection unit (7) according to one of the preceding claims, wherein - the band (10) has a plurality of slats (14) arranged on the outside and preferably evenly distributed along the band movement direction (R), which extend parallel to one another and to the light source strips (9) and are designed to impose a predetermined radiation direction on the projection light (L) generated by the light source strips (9) and / or to shield the display surface (8). [8] Projection unit (7) according to claim 7, wherein - the slats (14) are spatially aligned substantially parallel to one another over the entire display surface (8). [9] Field of view display device (2), in particular for use in a vehicle (1), comprising: - a projection unit (7) according to one of the preceding claims; and - a reflection disc arranged in the beam path of the projection light (L) emitted by the projection unit (7), such as a vehicle window (4) or a specially provided combiner disc; - wherein the reflection disc is arranged and designed in the field of vision of the user in such a way that it reflects the projection light (L) to an eyebox (E) predetermined for the user's eyes (3), whereby the display content can be presented to the user in the form of a virtual image (V) beyond the reflection disc. [10] Vehicle (1) with mutually perpendicular longitudinal, transverse and height directions of a vehicle-fixed Cartesian coordinate system, in particular a motor vehicle, comprising: - a passenger compartment and a vehicle window which at least partially delimits it towards the outside, in particular a windscreen (4) with an instrument panel (5) arranged underneath; and - a field of view display device (2) according to claim 9, the projection unit (7) of which is arranged in the passenger compartment and the reflection disc of which is designed as part of the vehicle window or as a combiner disc arranged separately in the passenger compartment; - wherein the projection unit (7) and its imaging display surface (8) are preferably arranged in or below an upper side of the instrument panel (5) in such a way that the windscreen (4) serves as a reflection screen of the field of view display device (2) at least with a large part of its horizontal extent.

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