Waveguide Display Assembly for a 3D Head-up Display Device in a Vehicle, and Method for Operating Same

Abstract

A waveguide display assembly includes a flat waveguide; a passage filter layer, which is divided into a plurality of area segments, which can be switched to light passage independently of each other; an image-generating unit, which is configured to generate different 2D images, each of which is intended only for one eye of a user for autostereoscopic 3D presentation, and to couple the 2D images into the waveguide in the form of collimated light beams, the propagation directions of which correspond to individual pixels; and a control unit, which is configured to control the image-generating unit and the passage filter layer such that only one or a subset of the area segments is switched to light passage at a time and, synchronously therewith, the image-generating unit generates only one image area segment of the 2D image intended for one eye of the user.

Claims

1.-10. (canceled)

11. A waveguide display assembly for a 3D head-up display device, the waveguide display assembly comprising: a flat waveguide with a light-emitting surface formed on a flat side of the waveguides, for light which is couplable laterally into the waveguide, a passband filter layer, arranged in a beam path of emitted light, wherein the passband filter layer completely covers the light-emitting surface and is divided into a plurality of area segments which are switchable to light transmission independently of one another; an image-generating unit which is configured to generate two different 2D images, each of which is intended for only one eye of a user for autostereoscopic 3D image presentation, and to couple the 2D images into the waveguide in a form of collimated light beams, wherein propagation directions of the collimated light beams correspond to individual pixels; and a control unit which is configured to control the image-generating unit and the passband filter layer such that only one or a subset of the area segments is/are switched to light transmission at a time and that, synchronously therewith, the image-generating unit generates only one image area segment of the 2D image intended for one eye of the user, the image area segment being such that the light beams transmitted by the passband filter layer cannot reach an eyebox predefined for the respective other eye of the user.

12. The waveguide display assembly according to claim 11, wherein the light is couplable laterally into the waveguide at a front face of the waveguide.

13. The waveguide display assembly according to claim 11, wherein the passband filter layer: is configured as a liquid crystal layer with at least one polarization filter for switching the area segments thereof between a light-transmitting and a light-blocking state, and/or is fixedly connected to the waveguide, and/or is either directly adjacent to the light-emitting surface or separated from the light-emitting surface by an air gap of a predefined thickness.

14. The waveguide display assembly according to claim 11, wherein the passband filter layer is divided into three or more area segments in a longitudinal direction of the light-emitting surface, wherein the longitudinal direction corresponds to a horizontal direction of eyeboxes predefined for the eyes of the user.

15. The waveguide display assembly according to claim 11, wherein the light-emitting surface in a longitudinal direction of the light-emitting surface has a light-emission efficiency gradient, such that an essentially uniformly illuminated 2D image is generated in an entire eyebox predefined for a respective eye, and the longitudinal direction corresponds to a horizontal direction of eyeboxes predefined for the eyes of the user.

16. The waveguide display assembly according to claim 11, wherein a length of the area segments in a longitudinal direction of the light-emitting surface, which longitudinal direction corresponds to a horizontal direction of eyeboxes predefined for the eyes of the user: is between approximately 1 mm and approximately 80 mm; is essentially the same for all area segments.

17. The waveguide display assembly according to claim 16, wherein the length is between approximately 2 mm and approximately 60 mm.

18. The waveguide display assembly according to claim 16, wherein the length is between approximately 3 mm and approximately 40 mm.

19. An autostereoscopic 3D head-up display device comprising: the waveguide display assembly according to claim 11; and an at least partially transparent reflection pane, which is arranged in a field of view of the user and is configured to reflect the collimated light beam generated by the waveguide display assembly toward the eyes of thee user so that a virtual 3D image appears in the field of view of the user in front of or behind the reflection pane.

20. The autostereoscopic 3D head-up display device according to claim 19, wherein the at least partially transparent reflection pane is a windscreen of a vehicle.

21. A method for operating the waveguide display assembly according to claim 11, the method comprising controlling the image generation unit and the passband filter layer such that: only one or a subset of the area segments at a time is/are switched to light transmission, and the image-generating unit, synchronously with switching to light transmission, generates only one image area segment of the 2D image intended for one eye of the user, the image area segment being such that the light beams transmitted by the passband filter layer cannot reach the eyebox predefined for the other eye of the user, wherein the respective 2D image is built up sequentially from the image area segments.

22. The method according to claim 21, further comprising controlling the image-generating unit and the passband filter layer such that: a plurality of the area segments of the passband filter layer are simultaneously switched to light transmission, at least intermittently, and while in the image-generating unit, synchronously with switching to light transmission, only such image area segments of the respective 2D images are generated that do not allow the light beams transmitted by the passband filter layer to reach the eyebox predefined for the respective other eye of the user.

23. The method according to claim 21, further comprising controlling the image-generating unit and the passband filter layer such that the 2D image intended for the left eye of the user and the 2D image intended for the right eye of the user: are generated alternately, by alternating construction of the entire respective 2D image, or are generated at least partially simultaneously by simultaneously switching different area segments of the passband filter layer to light transmission.

24. The method according to claim 21, further comprising controlling the image-generating unit and the passband filter layer such that the 2D image intended for the left eye of the user and the 2D image intended for the right eye of the user: are generated alternately, are generated at least partially simultaneously.

25. An assembly in a vehicle, the assembly comprising: a windscreen and an instrument panel arranged below the windscreen, and the autostereoscopic 3D head-up display device according to claim 19, the reflection pane of which is formed by the windscreen or a combiner pane arranged in front of the windscreen inside of a vehicle and the waveguide display assembly of which is arranged in an instrument panel such that the light beams generated by the waveguide display assembly are cast onto the reflection pane and reflected from the reflection pane to the eyes of the user, creating a virtual 3D image in the field of view of the user in front of or behind the reflection pane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 shows a lateral sectional view of a waveguide display assembly of the kind set forth herein.

[0040] FIG. 2a shows the lateral sectional view of the waveguide display assembly as shown in FIG. 1, during a first step of a three-stage image-building sequence for the 2D image for a user's right eye.

[0041] FIG. 2b shows the lateral sectional view of the waveguide display assembly as shown in FIG. 1, during a second step of the three-stage image-building sequence for the 2D image for the user's right eye.

[0042] FIG. 2c shows the lateral sectional view of the waveguide display assembly as shown in FIG. 1, during a third step of the three-stage image-building sequence for the 2D image for the user's right eye.

DETAILED DESCRIPTION OF THE DRAWINGS

[0043] All the different designs, variants and specific design features of the waveguide display assembly, the head-up display device, the method and the vehicle as specified in the above aspects of the invention and referred to above in the description and in the following claims may be implemented in the examples shown in FIGS. 1 to 2c. Therefore, they will not all be repeated in the following. The same applies accordingly to the definitions of terms and effects already given above in relation to individual features shown in FIGS. 1-2c.

[0044] FIG. 1 shows an example of a waveguide display assembly 1 of an autostereoscopic 3D head-up display device 10 of the kind set forth herein in a highly simplified schematic lateral sectional view. The head-up display device 10 may be in particular a head-up display (HUD) for use in a motor vehicle.

[0045] The waveguide display assembly 1 comprises a flat, in this example planar, waveguide 2 with a light-emission surface 4 formed in its flat side 3 (which is only symbolically indicated in the figures and actually corresponds to a surface of the waveguide) for light that is coupled into the waveguide 2 laterally, in this example at a left front face 8 of the waveguide 2, during operation of the waveguide display assembly 1. (In FIGS. 1 to 2c, for better recognition the light-emission surface 4 is only indicated as a schematic separately drawn rectangular light-emission element.) In addition, the waveguide display assembly 1 comprises a passband filter layer 6, which completely covers the light-emission surface 4 and can be directly adjacent to the light-emission surface 4.

[0046] In this example, the passband filter layer 6 is divided into exactly three area segments 61, 62 and 63, which can be switched independently to light transmission, in the beam path of the light L that is decoupled from the light-emission surface 4. As described above, this sub-division into three area segments should only be regarded as an exemplary embodiment that has proven to be successful for a typical motor vehicle geometry.

[0047] Depending on the particular vehicle geometry, there may be more or fewer area segments than in FIGS. 1 and 2a-2c. The only principle is that the area segments must be selected in such a way as to guarantee that image contents intended for the autostereoscopic 3D image display for the right eye A1 of a user can at no time reach the user's left eye A2, and vice versa. In this example, the passband filter layer 6 is designed as a liquid crystal layer with a polarization filter for switching its area segments 61, 62, 63 between a light-transmitting and a light-blocking state. The individual area segments 61, 62 and 63 are macroscopic and in a longitudinal direction X of the light-emission surface 4, which corresponds to a horizontal direction of the eyeboxes predefined for the eyes A1, A2 of the user, they have, purely by way of example, equal lengths D in the range 3 mm<D<40 mm.

[0048] The waveguide display assembly 1 also comprises an image generating unit 7, which is designed to generate two different 2D images, each intended for autostereoscopic 3D display for only one of the user's eyes. The image generation unit 7 is designed to couple these 2D images into the waveguide 2 in the form of collimated light beams, the propagation directions of which correspond to the individual picture elements.

[0049] Furthermore, the waveguide display assembly 1 also comprises a control unit 9, which is designed to control the image-generating unit 7 and the passband filter layer 6 in such a way that only one or a subset of the area segments 61, 62, 63 is/are switched to light transmission at a time and that, synchronously therewith, the image-generating unit 7 generates only one image area segment or segments of the 2D image intended for one eye A1, A2 of the user, said image area segment(s) being such that the light beams transmitted by the passband filter layer 6 cannot reach a spatial region (eyebox) predefined for the respective other eye of the user.

[0050] A corresponding example of an operating method of the kind set forth herein, which can be carried out in the waveguide display assembly 1 according to FIG. 1 by its control unit 9, is described below by reference to FIGS. 2a to 2c. In this case, only the area segments 61, 62, 63 of the passband filter layer 6 mentioned above are drawn and relevant to the present context, which are arranged in the beam path of the light L which is coupled out via the light-emission surface 4 of the waveguide 2 and thus overlap it.

[0051] The autostereoscopic 3D head-up display device 10 of the kind set forth herein comprises, in addition to the waveguide display assembly 1, an at least partially transparent reflection pane, not drawn in FIG. 1 for reasons of presentation. This should be arranged in the beam path of the light L generated by the waveguide display assembly 1 in the user's field of view in such a way that the light is reflected to the eyes A1 and A2 of the user, so that a virtual 3D image (not shown) appears in the user's field of view in front of or behind the reflection pane. For example, this reflection pane can be formed by a windscreen of the vehicle.

[0052] FIG. 2a shows the lateral sectional view of the waveguide display assembly as shown in FIG. 1 during a first step of a three-stage image-building sequence for the 2D image for a right eye A1 of a user. In this first step, only the first (right-hand in FIG. 2a) area segment 61 of the passband filter layer 6 is switched to light transmission, while the other two area segments 62 and 63 are in their light-blocking state (shown hatched) and do not transmit the light in the part of the light-emitting surface 4 behind them. Synchronously with this, the image content generated in the image-generating unit 7 is limited to the outer right third of the 2D image for the right eye A1 of the user. As a result, only the light beams L which pass through the first area segment 61 reach the right eye A1. These light beams cannot reach the user's left eye A2. The critical beam L1 (dashed) for this condition at the edge of the image area segment generated in FIG. 2a is transmitted at the left edge of the active area segment 61.

[0053] FIG. 2b shows the lateral sectional view of the waveguide display assembly as shown in FIG. 1, during a second step of the three-stage image-building sequence following the first step of FIG. 2a for the 2D image for the right eye A1 of the user. In this step, only the central area segment 62 of the passband filter layer 6 is switched to light transmission, while the other two area segments 61 and 63 are in their light-blocking state (shown hatched) and do not transmit the light in the part of the light-emitting surface 4 behind them. Synchronously with this, the image content generated in the image-generating unit 7 is now limited to a central third of the 2D image for the right eye A1 of the user. As a result, only the light beams L which pass through the second area segment 62 reach the right eye A1. Again, these light beams, the critical beam L2 of which is shown dashed, cannot reach the user's left eye A2.

[0054] FIG. 2c shows the lateral sectional view of the waveguide display assembly as shown in FIG. 1, during a third step of the three-stage image-building sequence following the second step of FIG. 2b for the 2D image for the right eye A1 of the user. In this step, only the left-hand area segment 63 of the passband filter layer 6 is now switched to light transmission, while the other two area segments 61 and 62 are in their light-blocking state (shown hatched) and do not transmit the light in the part of the light-emitting surface 4 behind them. Synchronously with this, the image content generated in the image-generating unit 7 is now limited to only a left third of the 2D image for the right eye A1 of the user. As a result, only the light beams L which pass through the third area segment 63 reach the right eye A1. Again, these light beams, the critical beam L3 of which is shown dashed, cannot reach the user's left eye A2.

[0055] After completion of the 3-stage sequence described, the user's right eye A1 has received all the image information of the 2D image intended for that eye. At the same time, the left eye A2 has been prevented from seeing any part of this 2D image.

[0056] In this example, a 3-stage image building sequence with corresponding image contents and active area segments can then be executed for the left eye A2 in a similar way.

LIST OF REFERENCE SIGNS

[0057] 1 waveguide display assembly [0058] 10 autostereoscopic 3D head-up display device [0059] 2 planar waveguide [0060] 3 flat side of the waveguide [0061] 4 light-emitting surface [0062] 6 passband filter layer [0063] 61, 62, 63 area segments of the passband filter layer [0064] 7 image generating unit [0065] 8 front face of the waveguide [0066] 9 control unit [0067] L light emitted from the light-emitting surface [0068] L1, L2, L3 critical beams in the sequential 2D image construction for the right eye [0069] A1, A2 the right/left eye of the user, i.e. viewer of the virtual 3D image [0070] X longitudinal direction of the light-emitting surface [0071] D length of the area segment