CN121219625A - Head-up display comprising a real image plane and a further real or virtual image plane by means of two alternately switchable imagers - Google Patents

Abstract

The invention relates to a projection unit for a visual field display device, comprising a translucent optical element which reflects light having a first polarization on the front side and transmits light having a second polarization on the rear side, a first and a second imager which are designed to output respectively associated light beams having the first or the second polarization and having a desired display content to respective different sides of the element, imaging and/or projection optics which are designed in the further light paths of the two light beams such that the two light beams leave the projection unit in a predetermined direction to a reflective glass arranged in the visual field of the user for reflection by the reflective lens to the eye of the user, wherein the projection unit is designed to alternately generate a suspended real image and a virtual image or a real image in another distance by switching between the two images.

Description

Head-up display comprising a real image plane and a further real or virtual image plane by means of two alternately switchable imagers

Technical Field

The present invention relates to a projection unit for a visual field display device, in particular for use in a vehicle, which projection unit is also known under the name head-up display (HUD). Such devices are designed to produce a real or virtual image inserted into the field of view of the user by reflection on a reflective glass, for example a front or rear window glass of a vehicle or a composite glass provided specifically for this purpose. The invention is also directed to an associated operating method, to a correspondingly provided control unit, to a visual field display device comprising the projection unit, and to a vehicle equipped therewith.

Background

In particular for motor vehicles, it is known to superimpose display contents such as speed instructions or other useful navigation and vehicle operation prompts in the form of virtual images on the actual environment observed by the driver in front of the vehicle, so that the driver does not have to leave his line of sight from the road in order to read the display. To generate the display content, the HUD in a conventional manner includes a projection unit placed in the interior of the dashboard under the front window glass. The projection unit typically comprises a display for producing a light beam with the desired display content and generally comprises concave mirror imaging and projection optics in order to shape the light beam and steer it onto the front pane in such a way that the light beam is reflected by the front pane to the eyes of the driver and the driver can thereby see a virtual image of a determined size and distance outside the front pane.

In addition to the virtual image display, it is known from CN 217821128U, for example, to generate a real image suspended in the vehicle for one or more observers simultaneously by means of an imaged concave mirror, wherein the light path is also guided here to the eye boxes of the driver and the co-driver by reflection on the front window.

Furthermore, DE 10 2019 206 956 A1, for example, proposes a display device for a future vehicle, which is designed as a head-up display, which additionally comprises a movable projection surface that can be moved between a first, moved-in position and a second, moved-out position and with its surface lying on the windshield of the vehicle in the moved-out position. It is proposed that the projection surface is only used in the automatic driving mode of the vehicle in the moved-out position thereof in order to entertain the driver by displaying information of the entertainment system, for example movies and/or images, directly in the projection surface, which may be opaque in particular for this purpose. In the manually controlled driving mode of the vehicle, the projection surface is located in the position in which it is moved in order to make use of the HUD in its conventional functional aspects for displaying an image, which is visible only to the driver and includes useful information about the state of the vehicle, etc., on a virtual screen in the field of view of the driver. In the transition from the automatic driving mode to the manual driving mode, the opaque projection surface must therefore be moved out of the visual field of the driver, which may lead to additional distraction when the driver takes over in an emergency. Furthermore, the display in the automatic driving mode is limited to the projection surface lying on the windshield, which must be lowered by its entire size into the interior of the dashboard for the manual driving mode.

Furthermore, it is known, for example from DE 11 2015 002 814 T5, in HUDs in vehicles to generate light paths of different lengths and thereby virtual images at different distances from the observer by means of suitable polarization switches in the imager and corresponding polarization-dependent semitransparent mirrors. However, in such applications, too, there are difficulties in integrating the two projections in one component, for example ghosts from the exactly unused light path.

Furthermore, CN 218471055U also discloses a HUD for a vehicle, wherein two light paths of different distances with virtual images are produced by means of semi-transparent mirrors. Thus, for example, the first virtual image may be used to display important driving information such as vehicle speed and tank indicators, etc. at a distance of 2-4 meters from the driver, while the second virtual image may be used to display additional information about other objects in remote buildings and environments at a distance of 20-50 meters from the driver. In addition to the wavelength-dependent or polarization-dependent separation of the light of a common imager, it is also proposed for this purpose to use two imagers which are arranged directly next to one another, in particular in adjacent sections of the same circuit board. In the latter case an additional turning mirror is used in order to turn the light of one of the two imagers onto the back side of the translucent mirror, while the light of the other imager impinges directly onto the front side of the translucent mirror.

Disclosure of Invention

The object of the present invention is to provide an alternative projection unit for a visual field display device, in particular for a vehicle, and/or improved with respect to installation space, display possibilities, display quality and/or other aspects, with which images can be generated at different distances from the user.

This object is achieved by a projection unit according to claim 1 and by an associated operating method according to the parallel claim, a corresponding control unit, a visual field display device comprising the projection unit and a vehicle equipped therewith. Further designs are given in the dependent claims. All further features and effects described in the claims and in the subsequent description for projection units also apply to the method, the control unit, the visual field display device and the vehicle, respectively, and vice versa.

According to a first aspect, a projection unit for a visual field display device is specified, which can be designed in particular for use in a vehicle. The visual field display device may be configured as a head-up display (HUD), for example. The vehicle may be a motor vehicle, but may also be any other land, air or water vehicle.

The projection unit has a translucent optical element which is formed on the front side in a substantially reflective manner for light having a first polarization and on the rear side in a substantially transmissive manner for light having a second polarization which differs from the first polarization. Here, "substantially reflective for light having a first polarization" may for example denote a reflection coefficient for more than 50%, in particular more than 60 or 70% and ideally more than 80 or 90% of the light. Similarly, "substantially transmissive to light having the second polarization" may for example denote a transmittance of more than 50%, in particular more than 60 or 70% and ideally more than 80 or 90% for that light. Purely exemplary, the first polarization may correspond to a vertical polarization or p-polarization (e.g., reflective glass as described further below with respect to the field of view display device) and the second polarization corresponds to a horizontal polarization or s-polarization, or vice versa. The projection unit may (but need not) be surrounded by a protective housing comprising a light exit opening or a transparent cover sheet.

Furthermore, the projection unit comprises a first imager configured for generating and for outputting a light beam having the first polarization and having a desired display content to the front side of the translucent optical element, and a second imager configured for generating and for outputting a light beam having the second polarization and having a desired display content to the back side of the translucent optical element. In principle any imaging technique is suitable for the respective imager, in particular a light-transmissive or light-emitting flat screen, a projector-based imager or a waveguide-based display. If appropriate, two imagers comprising associated imaging optics can be arranged in a space-saving manner directly opposite the front or rear side of the translucent optical element. Alternatively, however, other deflection mirrors may also be used in order to arrange the two imagers, for example, next to one another on a circuit board or the like, and to deflect the associated light beam onto the respective side of the translucent optical element.

After the translucent optical element, the further optical path is identical for both light beams and contains imaging and/or projection optics configured such that both light beams leave the projection unit in a predetermined direction to a reflective glass arranged in the field of view of the user in order to be reflected by the reflective glass to the eyes of the user. According to an application-specific embodiment of the respective light path comprising the associated imager, at least one of the two light paths is provided for generating a real image suspended in the air between the user and the reflective glass. The further light path is either arranged for generating such a real image as well, but at a further distance or for generating a virtual image outside the reflective glass. The user may be, for example, a driver, co-driver or other passenger of the vehicle.

The projection unit is configured to alternately generate a real image suspended between the reflective glass and the user in a predetermined distance and a virtual image or real image suspended outside the reflective glass in another distance by switching between the two imaging.

The idea here is to provide a HUD design with alternately switchable image planes at different distances from the user, wherein at least one of the image planes is located between the reflective glass and the user and thus at a distance from the eyes of the user that is suitable for reading and working, for example. The second image plane, which is at a greater image distance from the eyes of the user, can be designed, for example, in a real or virtual image plane for entertainment content, such as movies or videos, or for a drive-related display for the driver. This may be required when used in a vehicle, for example for automatic driving, as the driver or other passenger may optionally also use the visual display device for work or reading messages or other digitally displayable content.

The two projections at different distances are achieved here by polarization splitting by means of polarization-dependent semitransparent optical elements which are arranged on different sides of the element (optionally including associated further reversing or imaging optics) and by means of a correspondingly embodied imager. The different image distances can be achieved, for example, by different optical paths from the imager up to the respective partial optical paths of the translucent optical element and/or by providing further or differently focused imaging optical elements in these partial optical paths.

The optical design can furthermore overcome the difficulties mentioned at the outset of integrating two projections in one component, for example ghosting, which is typically produced when the same imager is used alternately for two different light paths. The generation of a real image suspended in the air has a number of advantages over conventional light-scattering projection surfaces, such as, for example, only a freely selectable image distance from the visibility or structure of a predetermined spatial region (eye box) and an image orientation in the air, which is not possible with a rigid screen or scattering surface in the vehicle due to the freedom of movement required for the passengers.

The semitransparent optical element can be configured, for example, as a mirror or a prism. Alternatively or additionally, the front side and/or the back side of the translucent optical element may be configured as a free-form surface, the curvature of which produces predetermined imaging, magnification and/or image correction characteristics of the element.

According to one embodiment, the projection unit is configured for alternately generating a real image suspended between the reflective glass and the user and a virtual image suspended outside the reflective glass by switching between the two imaging. For this purpose, the projection unit has additional imaging optics, such as a converging lens or an imaging mirror, etc., in its beam path for producing a real image, between the associated imager and the translucent optical element.

In an alternative embodiment, the projection unit is configured for alternately generating a real image suspended between the reflective glass and the user at a first distance from the reflective glass and a real image suspended between the reflective glass and the user at a second distance from the reflective glass by switching between the two images. For this purpose, an imaging optical element, in particular a converging lens or an imaging mirror or the like, is arranged between the associated imager and the translucent optical element at least in the beam path having a short image distance from the reflective glass, and is formed in the other beam path either with a lack of focus or with a less intense focus.

According to one embodiment, the imaging and/or projection optics arranged in a common part of the light path have at least one concave mirror. The respective concave mirror can be designed, for example, as an optical function for reversing, image magnification, imaging, collimation and/or image correction. Alternatively or additionally, however, the imaging and/or projection optics may also include other optical elements such as lenses, mirrors, etc. having these or other optical functions.

According to a further aspect, a method for operating a visual field display device comprising the above-described projection unit is specified. The method comprises generating or receiving a predetermined triggering signal for activating the first or the second imager and thereby triggering the actuation of only the first imager or only the second imager for outputting a light beam having the associated polarization and having the desired display content. In contrast to the solutions known from the prior art, in this method, ghosts are therefore excluded from the respective further light path by switching on only one of the two imagers and generating the associated light beam, respectively, while the respective other imager is switched off. Suitable trigger signals can be generated, for example, by the user himself via any user interface formed for this purpose and/or automatically by recognizing predetermined conditions for this purpose, for example, transitions in a manually controlled driving mode or the like.

According to a further aspect, a control unit is specified, which is designed and provided for automatically carrying out the method. For this purpose, a corresponding computer program (Software) can be loaded, for example, in a processor of the control unit and executed during operation of the visual field display device.

According to another aspect, there is provided a visual field display device for a vehicle including the above-described projection unit and a reflection glass provided in an optical path of a light beam outputted by the projection unit. The reflective glass is arranged in the field of view of the user and is designed such that it reflects the light beam to an eye box predetermined for the user, so that the display can be displayed to the user as a floating real or virtual image. The field of view display device further comprises the control unit described above, which is designed to operate both imagers in order to carry out the method described above.

According to another aspect, the vehicle is defined. The vehicle comprises a passenger space and a vehicle glazing, in particular a front glazing, which at least partially defines the passenger space. The above-described visual field display device is furthermore provided in a vehicle, the projection unit of which is arranged in the passenger space, in particular in the interior of an instrument panel arranged below the front window pane, and the reflective glass of which is configured as a section of the vehicle window pane or as a composite glass arranged in the passenger space. When used in a vehicle and when not otherwise specified, positional specification and spatially oriented terms such as "vertical," "horizontal," "front," "rear," "below," "above," and the like are always with respect to a generally fixed cartesian coordinate system of the vehicle having a longitudinal direction, a transverse direction, and a height direction perpendicular to each other.

Drawings

The above-described aspects of the invention, as well as embodiments and specific embodiments thereof, are further explained below by way of example in the figures. The drawings are to be understood as schematic illustrations and are not to be construed as true to scale. Wherein:

Fig. 1 shows a longitudinal section of a vehicle comprising a visual field display device according to an embodiment of the invention, which is configured for alternately displaying a real image and a virtual image suspended in a vehicle interior space by reflection on a front window pane.

Detailed Description

All the different embodiments, variants and special embodiment features mentioned in the foregoing description and in the following claims of the projection unit, the method, the control unit, the visual field display device and the vehicle according to the above-described aspects of the invention can be realized in the examples shown in the figures, in particular also alternatively or in addition to the features shown therein. So that then not all the content is repeated again. The same applies correspondingly to the term definitions and roles already given above in relation to the individual features shown in fig. 1.

Fig. 1 shows an exemplary embodiment of a vehicle 1 comprising a visual field display device 2 described here, which is designed to alternately generate a real image R suspended in the passenger space of the vehicle 1 and a virtual image V suspended outside the vehicle 1 in the visual field of a user, in a greatly simplified schematic longitudinal section. The vehicle 1 is in this example a motor vehicle, which is represented in fig. 1 only by its front pane 3, which serves as the reflective glass of the visual field display device 2 described above. Below which a projection unit 5 of the visual field display device 2 is arranged in a dashboard 4, not shown further. Again purely exemplarily referring to head-up displays (HUDs). The user may be, for example, the driver or co-driver of the vehicle 1.

The projection unit 5 comprises a first imager 6, for example an LCD (liquid CRYSTAL DISPLAY, liquid crystal screen), which is designed to generate an associated first light beam L1 having a first polarization and having the desired display content. Furthermore, the projection unit 5 comprises a second imager 7 (also purely exemplary LCD) which is designed to generate an associated second light beam L2 having a second polarization which differs from the first polarization and having the desired display content. Purely exemplary, the first polarization corresponds to a vertical polarization or p-polarization, and the second polarization corresponds to a horizontal polarization or s-polarization, wherein the s-polarization and p-polarization can be defined, for example, with respect to the surface of the front pane 3 on the vehicle interior side that serves as a reflection surface.

The projection unit 5 furthermore comprises a translucent optical element 8 (in this example a mirror or prism) which is formed on the front side in a substantially reflective manner for light having the first polarization and on the rear side in a substantially transmissive manner for light having the second polarization. Correspondingly, the first imager 6 comprises an associated imaging optical element (in fig. 1 purely by way of example in the form of a converging lens 10, wherein the imaging optical element can alternatively or additionally also be embodied as a mirror and/or as a different type of imaging optical element) arranged directly opposite the front side of the translucent optical element 8, while the second imager 7 is arranged directly opposite the rear side of the translucent optical element 8 in this example. Thus, the first light beam L1 impinges on the front side of the translucent optical element 8 and is reflected for the most part by the optical element, while the second light beam L2 impinges on the back side of the optical element and is transmitted thereby. The two light beams L1 and L2 which are produced alternately in time are represented in fig. 1 by their edge beams which define the beam cross section for image generation.

In a further optical path coincident for the two light beams L1 and L2, the projection unit 5 comprises imaging and/or projection optics in the form of a concave mirror 9 in this example. The respective imager 6/7, the translucent optical element 8 and the concave mirror 9 are configured and arranged relative to one another in such a way that the respective light beam L1/L2 leaves the projection unit 5 in a suitable form and direction in order to be subsequently reflected by the reflective glass (here the front pane 3) onto an eye box E predetermined for the eyes of the user in the passenger space and thereby display the display content as a real image B or virtual image V to the user with the desired properties.

The projection unit 5 is in this example configured for alternately generating a real image R suspended between the front pane 3 and the eye-box E and a virtual image V suspended outside the front pane 3 by switching between the two imagers 6 and 7. For this purpose, in the beam path of the first light beam L1 for producing the real image R, the converging lens 10 is arranged as an additional imaging optical element between the first imager 6 and the translucent optical element 8.

The projection unit 5 can be surrounded, for example, by a mechanically protective housing (not shown) which is closed towards the front pane 3 by a cover plate 11 which is largely transparent to the light beams L1 and L2 and can be used as a partial section of the upper side of the dashboard 4, not shown.

Furthermore, the visual field display device 2 comprises a control unit 12 which is provided for carrying out the method according to an embodiment of the invention and which is designed for the corresponding actuation of the two imagers 6 and 7. The method comprises generating or receiving a predetermined triggering signal for activating the first imager 6 or the second imager 7 and triggering the first imager alone or the second imager 6 or 7 alone in this way for outputting the associated light beam L1/L2 having the desired display content. Suitable triggering signals can be generated, for example, by the user himself via any user interface provided for this purpose in the vehicle 1 and/or automatically by detecting predetermined conditions for this purpose, for example, a transition in a manually controlled driving mode or the like.

List of reference numerals

1 Vehicle

2-Field display device

3 Front window glass

4 Instrument panel

5 Projection unit

6 First imager

7 Second imager

8 Polarization dependent translucent optical element

9 Concave mirror

10-Converging lens

11 Cover plate

12 Control unit

L1 first light beam

L2 second light beam

E eye box

V virtual image outside the vehicle

R real image suspended in passenger space

Claims (9)

1. Projection unit (5) for a visual field display device (2), in particular for use in a vehicle (1), comprising:

-a translucent optical element (8) which is formed on the front side in a substantially reflective manner for light having a first polarization and on the back side in a substantially transmissive manner for light having a second polarization different therefrom;

-a first and a second imager (6, 7) configured for outputting respectively associated light beams (L1, L2) having a first or a second polarization and a desired display content to respective different sides of the element (8);

-imaging and/or projection optics constituted in the same further optical path for the two light beams (L1, L2) such that the two light beams (L1, L2) leave the projection unit (5) in a predetermined direction to a reflective glass arranged in the field of view of the user for reflection by the reflective glass to the eyes of the user;

-wherein the projection unit (5) is configured for alternately generating a real image (R) suspended between the reflective glass and the user and a virtual image (V) or real image in another distance by switching between the two imagers (6, 7).

2. Projection unit (5) according to claim 1, wherein

-The semitransparent optical element (8) is formed as a mirror or prism, and/or

-The front side and/or the back side of the translucent optical element (8) is configured as a free-form surface having predetermined imaging and/or image correction characteristics.

3. Projection unit (5) according to claim 1 or 2, which projection unit

-Configured for alternately generating a real image (R) suspended between the reflective glass and the user and a virtual image (V) suspended outside the reflective glass by switching between the two imagers (6, 7), and

-Having for this purpose an additional imaging optical element, in particular a converging lens (10) or mirror, between the associated imager (6) and the translucent optical element (8) in the light path of the projection unit for generating the real image.

4. Projection unit (5) according to claim 1 or 2, which projection unit

-Configured for alternately generating, by switching between the two imagers (6, 7), a real image (R) suspended at a first distance from the reflective glass between the reflective glass and the user and a real image suspended at a second distance from the reflective glass between the reflective glass and the user, and

For this purpose, at least in the beam path having a short image distance from the reflective glass, an imaging optical element, in particular a converging lens (10) or a mirror, is provided between the associated imager (6) and the translucent optical element (8), which imaging optical element is formed in the other beam path either with a lack of focusing or with a less intense focusing.

5. Projection unit (5) according to one of the preceding claims, wherein

-The projection and/or imaging optics comprise at least one concave mirror (9).

6. Method for operating a visual field display device (2) comprising a projection unit (5) according to one of the preceding claims, the method comprising the steps of:

-generating or receiving a predetermined trigger signal for activating the first or second imager (6, 7), and

-Thereby triggering the actuation of only the first or only the second imager (6, 7) for outputting a light beam (L1, L2) having the associated polarization and having the desired display content.

7. -A control unit (12) structured and arranged for automatically implementing the method according to claim 6.

8. A visual field display device (2) for a vehicle (1), the visual field display device comprising:

-a projection unit (5) according to one of claims 1 to 5;

-a reflective glass arranged in the light path of the light beams (L1, L2) respectively output by the projection unit (5), the reflective glass being arranged and configured in the field of view of the user such that the reflective glass reflects the light beams (L1, L2) to an eye box (E) predetermined for the eyes of the user, whereby the display content can be displayed to the user as a floating real or virtual image (R, V), and

-A control unit (12) according to claim 7, configured for operating two imagers (6, 7) in order to implement the method according to claim 6.

9. Vehicle (1), in particular a motor vehicle, having a longitudinal direction, a transverse direction and a height direction perpendicular to each other of a cartesian coordinate system fixed relative to the vehicle, comprising:

-a passenger space comprising a vehicle glazing, in particular a front glazing (3), which vehicle glazing at least partially defines the passenger space, and

-A visual field display device (2) according to claim 8, the projection unit (5) of which is arranged in the passenger space, in particular in the interior of an instrument panel (4) arranged under the front window pane (3), and the reflective glass of which is configured as a section of the vehicle window pane or as a composite glass arranged in the passenger space.