Projection display with uniform illuminance for projecting a

Abstract

The invention relates to a projection display having: at least one light source; a projection surface; an assembly formed by a plurality of projection optics to project the light of the light source onto a projection surface by an associated light propagation, respectively; an imaging device arranged between the light source and the projection surface for light propagation, the imaging device having a first two-dimensional distribution of sub-imaging devices; wherein a plurality of projection optics are arranged in a second two-dimensional distribution, and each projection optics is assigned a sub-imaging device of the imaging device, the plurality of projection optics are arranged to project the sub-images of the sub-imaging device as projection sub-images onto a projection surface by means of one of the projection optics, and the projection sub-images are combined into a full image, at least two projection sub-images having a planar overlap in the projection surface, the invention also relates to related uses.

Description

Technical Field

[0001] The invention relates to a projection display. Background Art

[0002] This projection display includes a light source, a projection surface and at least one projection optical device, so that the light of the light source is projected onto the projection surface respectively through the relevant light propagation. This projection display also has an imaging device arranged between the light source and the projection surface for light propagation, and the imaging device is arranged to project the image of the imaging device onto the projection surface through the at least one projection optical device. Such components are, for example, part of a human-machine interface to visually display the functional status to the operator. For example, the component is used to display the functional status of a motor vehicle component. The projection surface is, for example, a reflective surface in the interior of a motor vehicle, a transmissive frosted glass plate or a translucent glass plate backlit by the projection component. The projection display is used in a motor vehicle, for example, as a head-up display. In order to be more flexible in designing the projection surface, the use of multiple projection optical devices (such as a microlens array) has been proven to be superior to the use of a single projection optical device, wherein each of these projection optical devices projects a sub-image of the imaging device onto the projection surface and these projected sub-images complement each other into a full image. The advantage of using multiple projection optical devices is that it can save construction space and can adapt the focal depth, so that each projection optical device can be adapted to the curve of the projection surface, so that the projection surface does not have to be flat and / or does not have to have a predetermined orientation. Then, for example, it is no longer required that the optical axis of the only existing projection optical device is oriented perpendicular to the projection surface. Therefore, the design leeway, especially with respect to the projection surface, is increased. However, the following problem still exists: especially when the shortest distance between the corresponding projection optical device and the projection surface changes, the brightness of the entire image measured on the projection surface changes, making it impossible to achieve the desired uniform illumination of the entire image. Summary of the invention

[0003] Against this background, a projection display is needed that provides an improved optical display, in particular a uniform illumination of the entire projected image, with a relatively small construction volume. This object is achieved by a projection display according to claim 1. Likewise advantageous uses are the subject matter of the parallel claims. Advantageous designs are the subject matter of the dependent claims, respectively. It should be noted that the features detailed individually in the claims can be combined with one another in any technically meaningful manner and present other designs of the invention. The description additionally characterizes and explains the invention in detail, in particular in conjunction with the drawings.

[0004] The invention relates to a projection display having at least one light source and a projection surface. The term "projection surface" shall include the following alternatives: projection onto a rearward projection surface from the perspective of an observer, that is, projection onto the projection surface from a half-space facing away from the observer, wherein the projection surface is formed, for example, by translucent frosted glass, or alternatively projection from a half-space shared with the observer, wherein, for example, projection is performed onto a diffuse scattering surface of a panel or lining.

[0005] According to the invention, the projection display further comprises an assembly formed by a plurality of projection optical devices, so that the light of the light sources is projected onto the projection surface respectively by means of the associated light propagation. For example, a number of light sources corresponding to the number of projection optical devices is provided. In the case of a small number of light sources, for example, further optical elements such as collimators are provided in the light path of the light between the light sources and the assembly of projection optical devices. Preferably, 64 or more, preferably 128 or more, projection optical devices are involved.

[0006] According to the present invention, an imaging device is provided which is arranged between the light source and the projection surface for light propagation, and the imaging device has a first two-dimensional distribution of sub-imaging devices. The sub-imaging devices are, for example, integrally connected to form an imaging device. For example, the imaging device is a holographic image carrier. The imaging device is preferably a transmissive imaging device. In most cases, preferably, the transmissive imaging device has a mask formed by an opaque coating of a transparent substrate. The mask is preferably formed by a metal coating of the substrate, such as a chrome coating. The first two-dimensional distribution has periodicity, for example, in two spatial directions extending therefrom.

[0007] According to the present invention, the plurality of projection optical devices are arranged according to a second two-dimensional distribution, wherein the projection optical devices are respectively assigned sub-imaging devices of the imaging device, i.e., each of the projection optical devices is arranged to project exactly one sub-image of the sub-imaging device onto the projection surface. The second two-dimensional distribution is periodic, for example, in each of the two spatial directions extending from the distribution.

[0008] According to the present invention, the assembly formed by a plurality of projection optical devices is configured to project the sub-images of the sub-imaging device as projection sub-images onto the projection surface, respectively, by means of one of the projection optical devices, so that the projection sub-images are combined into a full image. The term "sub-image" should not imply that each sub-image must necessarily constitute a small part of the full image. Instead, it is preferably proposed that at least one projection sub-image corresponds to the full image. For example, it is proposed that at least 25% of the projection sub-images do not correspond to the full image, but, for example, at least 25% of the projection sub-images each constitute a small part of the full image. However, it is preferably proposed that a plurality of the projection sub-images do not correspond to the full image, but, for example, a plurality of the projection sub-images each constitute a small part of the full image.

[0009] According to the invention, at least two projection sub-images have a planar overlap in the projection surface. This is achieved, for example, by the relative orientation of the optical axes of the relevant projection optical devices. Therefore, for example, the optical axes of at least two projection optical devices are not parallel to each other. Through this design according to the invention, it is possible to compensate for brightness losses caused, for example, by different optical path lengths between the respective light sources and the positions of the full image projected on the projection surface, without having to adapt the spatial distribution of the light intensity of the light source in a technically relatively expensive manner. The overlapping method is preferably selected so that the brightness adjustment within the full image is achieved by the overlap of at least two projection sub-images, so as to achieve, for example, uniform brightness over the entire full image. The projection surface is preferably formed to be uneven, and / or the shortest distances determined between one of the projection optical devices and the projection surface are different for a plurality of the projection optical devices.

[0010] The components formed by multiple projection optical devices and the corresponding forming method of the sub-images are preferably designed so that along an image curve, for example a straight line, located within the full image projected onto the projection surface, the number of overlapping projection sub-images changes, and due to the different area ratios of the projection sub-images in the full image, the projection sub-images participating in the image curve change.

[0011] Preferably, at least one point is provided in the image curve at which more than two projection sub-images participate in the projection of the overall image.

[0012] A first position of the image curve has a greater minimum distance from the second two-dimensional distribution of the sub-imaging means than a second position of the image curve, and the number of superimposed projection sub-images is greater at the first position than at the second position. In other words: as the distance to be projected is larger, more projection sub-images overlap. Still more preferably, more than two positions are provided along the image curve, which differ not only in the number of superimposed projection sub-images at the respective positions but also in the respective minimum distances from the second two-dimensional distribution of the sub-imaging means.

[0013] The first two-dimensional distribution of the sub-imaging device is preferably not parallel to the projection surface. The projection surface, for example, has one or more curved portions. Still more preferably, the projection surface is formed to be flat, and the first two-dimensional distribution of the sub-imaging device and the projection surface are arranged to be inclined relative to each other.

[0014] At least two projection sub-images, preferably a plurality of the projection sub-images, preferably differ in their area ratio in the overall image.

[0015] It is preferably provided that at least two projection sub-images are congruent and completely overlap one another.

[0016] The projection optical systems arranged directly adjacent to each other in the second two-dimensional distribution preferably each generate a projection sub-image having the greatest areal coverage, while the projection sub-images projected, for example, by projection optical systems arranged further adjacent to each other, have a smaller areal coverage.

[0017] It is preferably provided that the relative spacing of the first two-dimensional distribution corresponds to the relative spacing of the second two-dimensional distribution, that is, the relative arrangement relationship of the sub-images corresponds to the relative arrangement relationship of the projection optical device.

[0018] According to a preferred design, the imaging device is designed to make the following true for multiple sub-images of the sub-images: a sub-image located radially outside with respect to a geometric midpoint of the first two-dimensional distribution is smaller than multiple, preferably all, sub-images located radially inside.

[0019] For example, the projection of a central sub-image arranged in the geometric midpoint of the first distribution produces a projected sub-image corresponding to the full image, while the sub-images located radially outside it constitute only a small part of the area of ​​the central sub-image, wherein the area of ​​the sub-image decreases as the radial distance from the geometric midpoint increases.

[0020] The assembly formed by a plurality of projection optics preferably comprises a plurality of plano-convex or bi-convex projection lenses arranged in a corresponding relationship to the second two-dimensional distribution. The projection lenses are microlenses, that is to say lenses having a diameter smaller than 1 mm, preferably smaller than 100 μm.

[0021] It is preferably provided that each projection optical unit of the assembly comprises a plurality of lenses, for example two lenses.

[0022] The assembly formed by a plurality of projection optical devices is preferably formed by at least one microlens array according to a second two-dimensional distribution, which is applied to one of the main surfaces of the substrate or is formed by one of the main surfaces of the substrate. The two main surfaces of the substrate are preferably respectively formed as a microlens array according to the second two-dimensional distribution or are respectively provided with such an array.

[0023] Preferably, a plurality of light sources are provided, the light of which differs in the relevant color spectrum. In this embodiment, the assembly formed by the plurality of projection optical components is configured to achieve color adjustment within the full image by superposition of at least two projected sub-images. The superposition of the sub-images thus achieves color mixing, which is preferably used in most cases to achieve color adjustment over the entire full image.

[0024] The invention furthermore relates to the use of a projection display in one of the above-described embodiments in a motor vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention is explained in detail with reference to the following drawings. The drawings are to be understood as being merely exemplary and represent only preferred embodiments. In the drawings:

[0026] Figure 1 A cross-sectional view showing a projection display 1 of the present invention;

[0027] Figure 2 Show Figure 1 FIG. 5 is a top view of the imaging device 5 of the projection display 1 of the present invention. DETAILED DESCRIPTION

[0028] Figure 1 The projection display 1 according to the invention shown in FIG. 1 has a projection surface 3 and a light source 2. The term "projection surface 3" shall include the following alternatives: a projection onto a rearward projection surface from the perspective of an observer B, that is, a projection onto the projection surface 3 from a half-space facing away from the observer, wherein the projection surface is formed, for example, of translucent frosted glass, or alternatively a projection from a half-space shared with the observer B, wherein, for example, the projection is made onto a diffusely scattering surface, which is part of the visible surface of the panel 10 or the lining, such as Figure 1 This is exactly the case in .

[0029] The projection display 1 further comprises an assembly formed by a plurality of projection optical devices 4a, 4b, in order to project the light L of the light source 2 onto the projection surface 3 by means of associated light propagation. Further optical elements, such as a collimator 7, are arranged in the beam path of the light L between the light source 2 and the assembly of projection optical devices 4a, 4b, which are respectively formed by microlenses 4a facing the projection surface 3 and microlenses 4b facing the light source 2. This involves 64 or more, preferably 128 or more, projection optical devices 4a, 4b.

[0030] In addition, an imaging device 5 is provided, which is arranged between the light source 2 and the projection surface 3 for light propagation, and has a first two-dimensional distribution of sub-imaging devices 9a, 9b. The sub-imaging devices 9a, 9b are integrally connected here to form a transmissive imaging device 5, which is formed by an opaque chrome coating of a transparent substrate 6 (for example, formed by a glass material). The chrome coating is applied to the substrate 6, for example, by vapor deposition. The uncoated translucent to transparent areas form sub-images 8a, 8b here. The first two-dimensional distribution of the sub-imaging devices 9a, 9b is essentially periodic in the two spatial directions extending therefrom. Here, the plano-convex microlenses forming the projection optical devices 4a, 4b are applied on the main surface of the substrate 6 or are formed by one of the main surfaces of the substrate 6.

[0031] According to the present invention, the plurality of projection optical devices 4a, 4b are arranged according to a second two-dimensional distribution, wherein the projection optical devices 4a, 4b are respectively assigned sub-imaging devices 9a, 9b of the imaging device 5, i.e., each of the projection optical devices 4a, 4b is arranged to project exactly one sub-image 8a, 8b of the sub-imaging device 9a, 9b onto the projection surface 3. The second two-dimensional distribution of the sub-imaging devices 9a, 9b is periodic, for example, in two spatial directions extended by the distribution. It is further proposed that the relative spacing of the first two-dimensional distribution of the sub-imaging devices 9a, 9b corresponds to the relative spacing of the second two-dimensional distribution of the projection optical devices 4a, 4b, i.e., the relative arrangement relationship of the sub-images 8a, 8b or the sub-imaging devices 9a, 9b corresponds to the relative arrangement relationship of the projection optical devices 4a, 4b.

[0032] like Figure 1 As shown, the first two-dimensional distribution of the sub-imaging devices 9a, 9b is not parallel to the projection plane 3. More specifically, the projection plane 3 is formed to be flat, and the first two-dimensional distribution of the sub-imaging devices 9a, 9b and the projection plane 3 are arranged to be inclined relative to each other.

[0033] Here, the assembly formed by the plurality of projection optical devices 4a, 4b is configured to project the sub-images 8a, 8b of the sub-imaging devices 9a, 9b as projection sub-images 8a', 8b' onto the projection surface 3 by means of one of the projection optical devices 4a, 4b, respectively, so that the projection sub-images 8a', 8b' are combined into a full image G. Here, at least one projection sub-image 8a' corresponds to the full image G. The plurality of said projection sub-images do not correspond to the full image G, and the projection sub-image 8b' is here an exemplary representation thereof.

[0034] At least two projected sub-images 8a', 8b' have a planar overlap in the projection surface 3. This is achieved, for example, by the relative orientation of the optical axes of the relevant projection optical devices 4a, 4b. Therefore, for example, the optical axes of at least two projection optical devices 4a, 4b are not parallel to each other. Through this design according to the present invention, it is possible to compensate for brightness losses caused, for example, by different optical path lengths l, l' between the light source 2 and the position X or X' of the full image G projected on the projection surface 3, without having to adapt the spatial distribution of the light intensity of the light source 2 in a technically relatively expensive manner. The overlapping method is preferably selected so that the brightness adjustment within the full image G is achieved by the overlap of at least two projected sub-images 8a', 8b', so as to achieve, for example, uniform brightness over the entire full image G.

[0035] Here, the assembly formed by the plurality of projection optical devices 4a, 4b and the corresponding shaping of the sub-images 8a, 8b are designed so that along the image curves X, X' that are located within the overall image G projected onto the projection surface 3, Figure 1 In the curve from point X to point X' in FIG. 1 , the number of overlapping projection sub-images 8a', 8b' changes, and the projection sub-images 8a', 8b' participating in the image curve change due to the different area ratios of the projection sub-images 8a', 8b' in the full image G. For this purpose, the corresponding beam paths l, l' of the two projection optical devices 4a, 4b to the first position X of the image curve X, X' and to the second position X' of the image curve X, X' are marked.

[0036] As shown here, the difference between the first position X of the image curve X, X' projected onto the projection surface 3 and the second position X' of the image curve X, X' lies in the corresponding minimum distance d or d' of the first distribution of the sub-imaging devices 9a, 9b, wherein the minimum distance d, d' here are respectively perpendicular lines passing through the corresponding position X or X' to the first distribution. It is proposed here that the minimum distance d at the first position X is greater than the minimum distance d' at the second position X'. It also follows from this that the number of overlapping projection sub-images 8a', 8b' at position X is greater than the number of overlapping projection sub-images 8a' at the second position X'. In other words: in the case where the distance to be projected is greater, more projection sub-images 8a', 8b' overlap. Here, the difference between at least two projection sub-images 8a', 8b' lies in the proportion of their area in the overall image G. It is preferred to set the ratio along the image curves X, X'. Figure 1 The two positions X, X' shown in the figure are more positions, the difference between the positions is not only in the number of superimposed projection sub-images 8a', 8b' at the corresponding position but also in the corresponding minimum distance d, d' of the second two-dimensional distribution from the sub-imaging devices 9a, 9b. For example, the number of superimposed projection sub-images 8a', 8b' increases along the image curves X, X' in the direction of increasing minimum distance d, d'.

[0037] like Figure 2 As shown in the top view of the imaging device 5 in FIG. 1 , the imaging device 5 is designed so that the following is true for a plurality of the included sub-images 8a, 8b: the sub-image 8b located radially outside the geometric center point Z of the first two-dimensional distribution is smaller than a plurality of, preferably all, radially inside sub-images, such as the sub-image 8a. Thus, the projection of the central sub-image 8a arranged in the geometric center point Z of the first distribution produces a projected sub-image 8a' corresponding to the full image G, while the sub-images located radially outside thereof, such as the sub-image 8b, only constitute a small portion of the area of ​​the central sub-image 8a, wherein the area of ​​the sub-image 8b decreases as the radial distance from the geometric center point Z increases.

Claims

1. A projection display (1), comprising: at least one light source (2); Projection surface (3); An assembly formed by a plurality of projection optical devices (4a, 4b) for respectively projecting the light (L) of the light source (2) onto the projection surface (3) by means of associated light propagation; An imaging device (5) arranged between the light source (2) and the projection surface (3) for the light propagation, the imaging device having a first two-dimensional distribution of sub-imaging devices (9a, 9b); The plurality of projection optical devices (4a, 4b) are arranged in a second two-dimensional distribution, and sub-imaging devices (9a, 9b) of the imaging device (5) are respectively assigned to the projection optical devices (4a, 4b), and the assembly formed by the plurality of projection optical devices (4a, 4b) is configured to project sub-images (8a, 8b) of the sub-imaging devices (9a, 9b) as projection sub-images (8a', 8b') onto the projection surface (3) by means of one of the projection optical devices (4a, 4b), and the projection sub-images (8a', 8b') are combined into a full image (G), wherein at least two projection sub-images (8a', 8b') have a planar overlap in the projection surface (3).

2. A projection display (1) according to claim 1, wherein the components formed by a plurality of projection optical devices (4a, 4b) and the corresponding forming methods of the sub-images are designed so that along an image curve (X, X') located within a full image (G) projected onto the projection surface (3), the number of overlapping projection sub-images (8a', 8b') changes, and due to different area ratios of the projection sub-images (8a', 8b') in the full image (G), the projection sub-images (8a', 8b') participating in the image curve (X, X') change.

3. A projection display (1) according to the preceding claim, wherein at least one position is provided in the image curve (X, X') at which more than two projected sub-images (8a', 8b') participate in the projection of the full image (G).

4. A projection display (1) according to one of the two preceding claims, wherein a first position (X) of the image curve (X, X') has a larger minimum distance (d, d') from the second two-dimensional distribution of the sub-imaging devices (9a, 9b) than a second position (X') of the image curve (X, X'), and the number of superimposed projection sub-images (8a', 8b') is greater at the first position (X) than at the second position (X').

5. A projection display (1) according to the preceding claim, wherein more than two positions are set along the image curve (X, X'), which positions differ not only in the number of projected sub-images (8a', 8b') superimposed at the corresponding position but also in the corresponding minimum distance (d, d') from the second two-dimensional distribution of the sub-imaging devices (9a, 9b).

6. The projection display (1) according to one of the preceding claims, wherein the first two-dimensional distribution of the sub-imaging devices (9a, 9b) is not parallel to the projection plane (3).

7. A projection display (1) according to the preceding claim, wherein the projection surface (3) is flat and the first two-dimensional distribution of the sub-imaging devices (9a, 9b) and the projection surface (3) are arranged to be inclined relative to each other.

8. A projection display (1) according to one of the preceding claims, wherein at least two projection sub-images (8a', 8b'), preferably a plurality of projection sub-images in the projection sub-images (8a', 8b'), differ in their area ratio in the overall image (G).

9. The projection display (1) according to one of the preceding claims, wherein at least two projected sub-images (8a', 8b') are formed to be congruent and completely overlap one another.

10. The projection display (1) according to claim 1, wherein projection optical systems (4a, 4b) arranged directly adjacent to each other in the second two-dimensional distribution each generate a projection sub-image (8a', 8b') having a maximum areal coverage.

11. The projection display (1) according to one of the preceding claims, wherein the first two-dimensional distribution coincides with the second two-dimensional distribution.

12. A projection display (1) according to one of the preceding claims, wherein the imaging device (5) is designed to make the following true for a plurality of the sub-images (8a, 8b): a sub-image (8b) located radially outside with respect to the geometric midpoint (Z) of the first two-dimensional distribution is smaller than a plurality of, preferably all, sub-images (8a) located radially inside.

13. The projection display (1) according to one of the preceding claims, wherein the assembly formed by a plurality of projection optics (4a, 4b) comprises a plurality of plano-convex or bi-convex projection lenses having the second two-dimensional distribution.

14. The projection display (1) according to one of the preceding claims, wherein each projection optics (4a, 4b) comprises a plurality of lenses.

15. The projection display (1) according to one of the preceding claims, wherein the imaging device (5) is a transmissive imaging device.

16. The projection display (1) according to the preceding claim, wherein the transmissive imaging device (5) has a mask formed by an opaque coating of a transparent substrate (6).

17. The projection display (1) according to the preceding claim, wherein the mask is formed by a metal coating of the substrate (6).

18. A projection display (1) according to one of the preceding claims, wherein the assembly formed by a plurality of projection optical devices (4a, 4b) is formed by a microlens array according to the second two-dimensional distribution, the microlens array being applied on one of the main surfaces of the substrate (6) or formed by one of the main surfaces of the substrate (6).

19. A projection display (1) according to one of the preceding claims, wherein a plurality of light sources (2) are provided, the light of which differs in a relevant color spectrum, and the assembly formed by a plurality of projection optical devices (4a, 4b) is configured to achieve color adjustment within the full image by overlapping at least two projected sub-images (8a', 8b').

20. The projection display (1) according to one of the preceding claims, wherein at least one projected sub-image (8a', 8b') corresponds to the full image.

21. The projection display (1) according to one of the preceding claims, wherein a plurality of the projected sub-images (8a', 8b') do not correspond to the full image.

22. The projection display (1) according to one of the preceding claims, wherein the number of projection optical devices (4a, 4b) is 64 or more, preferably 128 or more.

23. A projection display (1) according to one of the preceding claims, wherein the projection surface (3) is formed to be uneven and / or the shortest distance determined between one of the projection optical devices (4a, 4b) and the projection surface (3) is different for a plurality of the projection optical devices (4a, 4b).

24. Use of a projection display (1) according to one of the preceding claims in a motor vehicle.

Images