Privacy display with real image generation in the vehicle interior via a partially transparent combiner screen functioning as a concave mirror

Abstract

The invention relates to a privacy display, in particular for use in a motor vehicle. The privacy display comprises an imager, which is designed for generating a light beam with a desired display content, and an imaging and projection optical system located in the beam path of the generated light beam. Said optical system comprises a combiner screen located in the field of view of a user, which is designed on the user side as an imaging concave mirror for the light beam and on the rear side so as to be at least partially transparent to the ambient light. The imaging and projection optical system is designed, by reflecting the light beam from the combiner screen to an eyebox specified for the user's eyes, to map the display content generated in the imager onto a real image that is suspended in the air between the combiner screen and the eyebox.

Description

[0001] Description

[0002] Privacy display with real image generation in the vehicle interior via a partially transparent combiner screen acting as a concave mirror

[0003] The invention relates to a privacy display designed to generate images via reflection from a partially transparent combiner panel arranged in the user's field of vision. In particular, it can be designed for installation in the passenger compartment of a vehicle and for generating images for a vehicle occupant, so the invention also applies to a vehicle equipped with such a display.

[0004] Head-up displays (HUDs) are particularly well known for motor vehicles. These are designed to project a virtual image into the field of vision of an occupant via reflection from a partially transparent reflective screen, typically a windshield or a specially designed combiner screen. This allows, for example, speed information and other useful navigation, warning, and vehicle operating instructions to be superimposed on the real environment in front of the vehicle observed by the driver or another occupant. For this purpose, a conventional HUD for the driver, for example, comprises a projection unit housed in the instrument panel. This generates a beam of light with the desired display content and projects it in a suitable shape and direction onto the windshield or combiner screen, from which it is reflected to the driver's eyes or to a spatial area defined for this purpose (eyebox).To read a head-up display, the driver does not need to take their eyes off the road and, with a suitable design of the projection optics, does not need to significantly refocus. In the prior art, head-up displays are also proposed for use as passenger entertainment or as driver entertainment during parking or autonomous driving. In addition to virtual image display, the generation of a real image floating in the air for one or more viewers using an imaging concave mirror is known, for example from CN 217821128 U. The beam path always leads to the eyeboxes of a driver and / or passenger via a subsequent reflection on the vehicle's windshield.

[0005] It is an object of the present invention to provide an alternative and / or improved display concept which, compared to known devices, enables an improvement, for example, with regard to possible applications, installation space, image distance, image resolution, image quality and / or other aspects and is particularly well suited for use in a vehicle as driver or passenger entertainment.

[0006] This object is achieved by a privacy display according to claim 1 and by a vehicle equipped therewith according to the independent claim. Further embodiments are specified in the dependent claims. All further features and effects mentioned in the claims and the following description for the privacy display also apply to the vehicle, and vice versa.

[0007] According to a first aspect, a privacy display is provided which can be designed in particular for installation in a vehicle, for example in its instrument panel or parcel shelf. The vehicle can be a motor vehicle, but also any other land, air, or water vehicle. Unless otherwise stated, when used in the vehicle, all spatial orientation terms used herein, such as "from," "rear," "top," "bottom," "horizontal," "vertical," etc., refer to the usual vehicle-fixed Cartesian coordinate system with mutually perpendicular longitudinal, transverse, and vertical directions of the vehicle. The privacy display comprises an image generator designed to generate a desired display content and a light beam (also referred to herein as "projector light") that transports this content.Furthermore, the privacy display comprises an imaging and projection optics which is arranged in the beam path of the generated light beam and comprises a combiner disc which is to be arranged in the field of vision of a user.

[0008] This combiner disc is designed to reflect the light beam to an eyebox predefined for the user's eyes. It is configured on the user side as an imaging concave mirror for the light beam and on the rear side is at least partially transparent to ambient light. The imaging and projection optics are designed to project the display content generated in the imager onto a real image suspended in the air between the combiner disc and the eyebox.

[0009] In principle, any imaging technology is suitable for the imager. In particular, it can be designed to dynamically generate the required or desired display content in a two-dimensional pixel matrix. In particular, the imager can be designed as a light-transmitting or light-emitting flat panel display, such as a liquid crystal display (LCD) or a pLED or OLED display, or alternatively as a projector-based imager or a waveguide-based display. This makes it possible, for example, to generate display content that reproduces a work computer desktop or an open book and / or whose content can be controlled by the user via a suitable user interface (such as acoustic input, touchpad, keyboard, and much more).On the other hand, it can be used to create display content that plays a video film or a video game, etc.

[0010] The combiner disc can be made of any material suitable for the functionality presented here, for example, plastic or glass. It can, for example, be a glass or plastic disc with a regular or free-form concave mirror surface.

[0011] The user can see the real image when their eyes are in the eyebox and they are looking toward the combiner disk. Unlike a virtual image, this real image floating in the air can be captured by a light-sensitive material (e.g., photographic film) and made visible to everyone by means of a diffusely light-scattering surface (e.g., a sheet of paper) when such a material or surface is placed at the specified image position in the air.

[0012] As is customary, an eyebox is defined as a two- or three-dimensional spatial area from which the displayed real image is fully visible. In other words, the light beam is essentially confined to this spatial area. Therefore, the generated image is only visible to the user whose eyes are located within the eyebox, which, for example, does not extend beyond the width of their seat or vehicle seat. This allows confidential content to be displayed to this user (“privacy”). On the other hand, other users, such as the driver or other passengers in the same vehicle, are not visually disturbed by this display because they cannot see it.

[0013] One idea of ​​the present invention consists in a projector (privacy display) which is designed to project a real image floating freely in the air via reflection from a partially transparent combiner screen that acts as an imaging concave mirror. This display concept is therefore particularly suitable for vehicles with a screen contour that does not allow a conventional head-up display with projection via the windshield. Due to the at least partial rear-side transparency of the combiner screen to ambient light, the environment beyond the combiner screen also remains visible to the user of the privacy display. This means that, for example, in the event of an approaching hazard, they can visually perceive it through the combiner screen in good time and react accordingly.

[0014] Using the aforementioned imaging and projection optics, particularly through a suitable selection of their effective focal length, the real image can be generated at a significantly shorter image distance from the user's eyes than with virtual image generation. For the present privacy display, this image distance can be, for example, less than one meter or even less than half a meter. Such image distances can be particularly designed for reading or working applications. Such a privacy display can be of interest, for example, to the passenger in a vehicle, but also to the driver, for example, during autonomous driving or when the vehicle is stationary.For example, it can be used for working or reading news or other digitally displayable content at a significantly shorter image distance and with a significantly higher spatial resolution than is possible with the virtual image generation of a conventional combiner HUD.

[0015] According to one embodiment, the imaging and projection optics of the privacy display further comprise at least one additional imaging concave mirror in the beam path of the light beam between the imager and the combiner disk, which, together with the combiner disk, contributes to imaging the display content generated in the imager onto the real image suspended between the eyebox and the combiner disk. The imaging concave mirrors, with their respective focal lengths, are designed such that the display content of the light beam is projected onto a real image suspended freely in the air at a predetermined position between the eyebox and the combiner disk. By providing an additional concave mirror, for example, a particularly high image quality and / or other specific requirements such as a predetermined image distance, etc., can be realized.In addition to its imaging function, the respective concave mirror can also be designed, for example, to deflect, magnify, and / or correct the light beam. Alternatively or additionally, the imaging and projection optics can also include other imaging elements, such as lenses, for generating the real image, as well as other deflecting elements, such as plane mirrors, for folding the beam path.

[0016] According to one embodiment, the imaging and projection optics are designed to display the real image in a real image plane or curved image surface floating in the air between the combiner disk and the eyebox. By appropriately selecting the mutual arrangement and design of the image generator, the combiner disk, and any additional elements of the imaging and projection optics, an optimal orientation (in terms of image inclination) of the floating image plane or image surface for viewing the floating real image can be achieved. In particular, this allows a floating real image plane or image surface to be created at positions and with orientations that are not available for hard display surfaces due to the required arm and legroom of the user, particularly in a vehicle.

[0017] In particular, this floating real image plane / image surface can be inclined upwards from the vertical at a predetermined angle of inclination, and thus towards the eyebox. Such an inclination can be particularly ergonomic, for example, compared to a vertically or obliquely downwardly oriented image plane / image surface. Particularly when reading, the variation in the image distance along the floating real image plane / image surface and the associated variation in the focus of the reader's eyes can thereby be significantly reduced. This angle of inclination, which is measured with respect to the vertical (i.e., the vehicle height direction in the vehicle), can be, for example, at least approximately 10°, in particular at least approximately 20° or even at least approximately 30°. According to a further aspect, the above vehicle is provided. The vehicle comprises a passenger compartment which is directed forwards (i.e.,in the vehicle's longitudinal direction, sometimes also referred to as the direction of travel) and / or by a rear window and a parcel shelf extending underneath it to the rear (i.e., in the opposite direction). The vehicle is equipped with at least one privacy display of the type presented herein. Each of these privacy displays is integrated into the vehicle's passenger compartment in such a way that its combiner pane is positioned directly in the field of vision of a vehicle occupant who is the user of this privacy display.

[0018] According to one embodiment, at least one of the privacy displays is integrated into the instrument panel or parcel shelf in such a way that its combiner pane extends upwards from a top side of the instrument panel or parcel shelf, at least during operation of this privacy display, and is located directly in the field of vision of the occupant when looking towards the windshield or rear window. The imager and any additional elements of the imaging and projection optics of this privacy display are concealed inside the instrument panel or parcel shelf. In particular, the combiner pane can be manually and / or automatically lowered or retracted into the interior of the instrument panel / parcel shelf when the privacy display is not needed.

[0019] In particular, one of the privacy displays can be arranged opposite a passenger seat and designed for use as passenger entertainment. Alternatively or additionally, one of the privacy displays can be arranged opposite a driver's seat and designed, for example, for use as driver entertainment during autonomous driving or in a parked vehicle.

[0020] The above aspects of the invention and their embodiments and specific configurations are explained in more detail below using an example shown in the accompanying drawing. The drawing is to be understood as a purely schematic illustration of the basic optical design principle and is not to scale. It shows:

[0021] Figure 1 shows a vertical longitudinal section of a section of a vehicle with a privacy display according to an embodiment of the invention.

[0022] All of the various embodiments, alternatives, and specific design features of the privacy display and the vehicle according to the above aspects of the invention mentioned above in the description and in the subsequent claims can be implemented in the example shown in Fig. 1, in particular also alternatively or in addition to the features shown therein. Therefore, they will not all be repeated below. The same applies accordingly to the definitions and effects already given above with regard to individual features shown in Fig. 1.

[0023] Fig. 1 shows, in a highly simplified schematic vertical longitudinal sectional view, an embodiment of a vehicle 1 with a privacy display 2 of the type presented herein. In this example, the vehicle 1 is a motor vehicle, which is only indicated in Fig. 1 by its windshield 3 and an instrument panel 4 extending beneath it, which delimit its passenger compartment to the front. As already mentioned, the spatial orientation terms such as "from", "rear", "top", "bottom", "side", "horizontal", "vertical", etc. refer to the usual vehicle-fixed Cartesian coordinate system with mutually perpendicular longitudinal, transverse and vertical directions of the vehicle 1.

[0024] In this example, the privacy display 2 is integrated into the instrument panel 4 and contains an image generator 5, which is designed to generate a light beam L with the desired display content, as well as imaging and projection optics arranged in its beam path. The imaging and projection optics comprise a combiner disk 6 in the form of an imaging concave mirror arranged in the user's field of vision and, purely by way of example, a further optical imaging element in the form of another concave mirror 7.

[0025] The user, in this example a passenger, is only indicated by a spatial area E (eyebox) intended for their eyes. The eyebox E is again sketched purely symbolically and is located in the area of ​​a corresponding front vehicle seat (not shown) or its headrest. The light beam L (also called projector light) is only schematically indicated by its peripheral rays.

[0026] The combiner pane 6 extends upwards from the top of the instrument panel 4, i.e., approximately along the windshield 3, at least when the privacy display 2 is in operation, and is located directly in the field of vision of the user when looking forward toward the windshield 3. The imager 5 and the additional concave mirror 7 are concealed inside the instrument panel 4, in the top of which an exit opening (not separately shown) is provided that is permeable to the light beam L. In particular, the combiner pane 6 can be manually and / or automatically lowered or retracted into the interior of the instrument panel 4 when the privacy display 2 is not needed.

[0027] The combiner pane 6 is designed to reflect the light beam L to the user's eyebox E. On the user side, it is configured as an imaging concave mirror for the light beam L and on the rear side is at least partially transparent to the ambient light. As a result, the windshield 3 and the external environment in front of the vehicle 1 are at least partially visible to the user through the combiner pane 6. The imaging and projection optics are designed to project the display content generated in the imager 5 onto a real image R that floats in the air in the passenger compartment of the vehicle 1 between the combiner pane 6 and the eyebox E. The imager 5 is only schematically indicated by a functional block in Fig. 1.It can be designed purely as an example as a flat screen, in particular a liquid crystal display (LCD), so that the respective desired display content is dynamically generated in its display area (not shown separately). However, the image generator 5 can also be designed as a projector and, for example, contain a light-scattering projection surface (not shown separately) onto which the respective display content is projected as a real image. Alternatively, the projector-based image generator 5 can comprise a laser scanner or a light source with suitable illumination optics for generating a homogeneous, collimated illumination beam, as well as an image generation surface illuminated thereby (for example in the form of an LCOS (Liquid Crystal on Silicon) or DMD (Digital Micromirror Device, not shown separately), which can be controlled pixel by pixel to generate the display content.

[0028] By appropriately selecting the mutual arrangement and design of the image generator 5 and the imaging and projection optics, an optimal position (in terms of image distance) and orientation (in terms of image inclination) of the floating real image R between the combiner disk 6 and the eyebox E can be achieved, which would not be possible with conventional display technologies such as flat screens or head-up displays. In particular, the user can view the floating real image R at a comfortable reading distance of, for example, approximately 30-50 cm from their eyes, without restricting their arm and leg freedom.

[0029] The user can see the real image R if their eyes are in the designated eyebox E and they are looking toward the combiner disk 6. It is not visible to other occupants whose eyes are not in said eyebox E (privacy). In contrast to virtual image generation known from the prior art, with the present privacy display 2, the real image R can be recorded using light-sensitive material (e.g., photographic film) and made visible to everyone using a diffusely light-scattering surface (e.g., a sheet of paper), if such a material or surface were to be brought into its image position shown in Fig. 1.

[0030] List of reference symbols

[0031] 1 vehicle

[0032] 2 Privacy Display

[0033] 3 Windscreen

[0034] 4 Instrument panel

[0035] 5 imagers

[0036] 6 Combiner disc

[0037] 7 additional imaging concave mirrors

[0038] L Light beam (also called projector light)

[0039] R real image floating in the air

[0040] E Eyebox

Claims

Claims 1. A privacy display (2), particularly for use in a vehicle (1), comprising: an image generator (5) configured to generate a light beam (L) with the desired display content; and imaging and projection optics arranged in the beam path of the generated light beam (L), comprising a combiner disk (6) to be arranged in the field of vision of a user, which is configured on the user side as an imaging concave mirror for the light beam (L) and on the rear side at least partially transparent to the ambient light; wherein the imaging and projection optics are configured to project the display content generated in the image generator (5) onto a real image (R) suspended in the air between the combiner disk (6) and the eyebox (E) by reflecting the light beam (L) from the combiner disk (6) to an eyebox (E) predetermined for the user's eyes.

2. Privacy display (2) according to claim 1, the imaging and projection optics of which comprise at least one further imaging concave mirror (7) in the beam path of the light beam (L) between the image generator (5) and the combiner disk (6), which is also used to image the display content generated in the image generator (5) onto the screen between the eyebox (E) and the combiner disc (6) floating real image (R).

3. A vehicle (1) with mutually perpendicular longitudinal, transverse, and vertical directions of a vehicle-fixed Cartesian coordinate system, in particular a motor vehicle, comprising: a passenger compartment; and at least one privacy display (2) according to one of the preceding claims, which is integrated in the passenger compartment of the vehicle (1) such that its combiner pane (6) is arranged directly in the field of vision of a respective occupant of the vehicle (1) who is the user of the privacy display (2).

4. Vehicle (1) according to claim 3, further comprising a windshield (3) and an instrument panel (4) extending therebelow, which delimit the passenger compartment to the front; wherein at least one of the privacy displays (2) is integrated in the instrument panel (4) such that its combiner panel (6) extends upwards from an upper side of the instrument panel (4), at least during operation of this privacy display (2), and is located directly in the field of vision of said occupant when looking towards the windshield (3), while the image generator (5) and any further elements of the imaging and projection optics of this privacy display (2) are hidden inside the instrument panel (4).

5. Vehicle (1) according to claim 3 or 4, wherein one of the privacy displays (2) is arranged opposite a passenger seat and is designed for use as passenger entertainment; and / or one of the privacy displays (2) is arranged opposite a driver's seat and is preferably designed for use as driver entertainment during autonomous driving or in a parked vehicle (1).

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