WO2014167119A2

WO2014167119A2 - Projection display for reflecting an image to be displayed into the view of an occupant of a means of transportation

Info

Publication number: WO2014167119A2
Application number: PCT/EP2014/057436
Authority: WO
Inventors: Marcel Sieler; Peter Schreiber
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2013-04-12
Filing date: 2014-04-11
Publication date: 2014-10-16
Also published as: DE102013206614A1; WO2014167119A3

Abstract

The invention relates to a projection display that operates in a multi-channel manner to reflect an image to be displayed into the view of an occupant of a means of transportation. By means of this approach the construction size can be reduced, because the focal lengths of the optical units of the individual channels can be significantly smaller, which in turn also enables a weight reduction of the system. Because of the multi-channel nature, the susceptibility of the projection display to curvatures of the reflection surface is also reduced, which relives the burden on the corrective measures and thus can reduce the installation scope and/or the quality of the reflected image. The reflection can also be adapted in a simple manner to the current situation of the occupant of the means of transportation.

Description

Projection display for reflecting an image to be displayed in a view of a

Inmates of a means of transport

description

The present invention relates to a projection display for reflecting an image to be displayed into a view of an occupant of a means of locomotion such as a vehicle. in the view of a driver of an automobile.

Head-up displays in automotive applications are used to display moving or static virtual images, and are about 80 cm to 100 cm away from the eyes of the beholder. Such head-up displays (HUD) usually use a projection optics in the form of several free-form mirrors for generating a virtual image in the driver's direct field of vision. The object to be imaged is usually provided by a microdisplay or generated for example with a laser scanner on a screen. The virtual image is usually displayed at a distance of 2 to 3 m. Either the windscreen of the car or an additional, partially transparent optical element is used as a combiner for reflection.

The focal length of the projection optics f together with the horizontal extent of the microdisplay s D _{x determines} the field of view of the HUD: 0F = 2arctan - ^ -

2f

In order to realize common visual fields in the range of currently usually 6 °, focal lengths of about 300 mm are required for typical display widths of about 30 mm. The pupil diameter of the eyepiece optics thereby determines the size of the area in which the eye of the observer may move, i. the so-called Eye or Head Motion Box, EMB. The EMB is obtained from the ratio of focal length f to f-number f / # of the projection optics:

EMB = D _{Pm k} = ----- P """" (// #) For typical f-numbers in the range of approximately f / 2, this yields an EMF of the order of magnitude of approximately 150 mm. Here are the following main problems:

1. The comparatively large, required focal length of the mirror optics requires large system dimensions, which, even with multiple convolutions of the optical beam path, worsens the necessary construction volume and, consequently, the integrability of a vehicle.

2. The low f-number required for an EMB and the inclusion of the free-form surface of the windshield to reflect information directly

The driver's field of vision complicates the correction of aberrations, which further increases the complexity - and thus size and mass - of the projection optics. 3. Adjusting the position of the mirrored image is achieved by mechanically moving components of the projection optics, further complicating the system design, reducing robustness, and increasing manufacturing costs.

4. A setting of the distance of the virtual image is previously impossible without additional mechanically moving components.

To reduce the size of the optics for a given focal length, for example, multiply folded beam paths can be used. The main disadvantages of such optical schemes are the resulting large system dimensions and masses as well as the complicated free-form optics required for aberration correction. Due to the freeform surface of the vehicle windscreen, a strong pre-distortion of the image to be displayed is necessary. This goes hand in hand with a reduction in the image resolution that can be displayed for the driver. An alternative approach is to use a separate plating surface which may be flat or curved to eliminate the consequences of serial tolerances of the windshield due to their manufacturing process on the optical imaging beam path of the HUD.

It would be desirable to have a projection display for mirroring an image to be displayed into a vehicle occupant view that is more effective, such as requiring less space, being lighter, and / or allowing for greater user friendliness. The object of the present invention is therefore to provide such a more effective projection display. This object is solved by the subject matter of the independent patent claims. The core idea of the present invention is to have realized that it is possible to use a projection display which works in multiple channels for reflection of an image to be displayed in a view of an occupant of a means of locomotion. This procedure makes it possible to reduce the size, since the focal lengths of the optics of the individual channels can be significantly smaller, which in turn also makes it possible to reduce the weight of the system. Due to the multichannel nature, the susceptibility of the projection display to curvature of the mirror surface is also reduced, which relieves the corrective measures and thus can reduce the scope of installation and / or the quality of the mirrored image. An adaptation of the reflection to the situation in which the occupant of the vehicle is currently located is likewise possible in a simple manner.

Preferred embodiments of the present application are explained in more detail below with reference to the figures, wherein preferred embodiments are also subject of the dependent claims. Show under the figures

1 is a schematic view of a projection display according to an embodiment;

Fig. 2 is a side sectional view through a series of channels of the projection display of Fig. 1;

Fig. 3a is a schematic plan view of the projection display of Fig. 1;

FIGS. 3b and 3c show beam paths of a row of channels of the projection display for illustrating the relationship between frame center distance and removal of the virtual image;

Fig. 3d shows beam paths of a series of channels of the projection display to illustrate the achievement of an EMB shift from the setting of Fig. 3c; Fig. 3e and f are optical paths of a series of channels of the projection display to illustrate the achievement of a correction of the mirror surface curvature: Fig. 3e with and Fug. 3f without correction; 4 shows a room view of a projection display according to a further exemplary embodiment with Köhler's backlight in interaction with a planar mirror surface;

5a, b show spatial views of the projection display of FIG. 4 in interaction with a free-form reflection surface;

6 is a perspective view of an example of an installation of the projection display of FIG.

4 in an automobile; 7a, b are room views of an exemplary installation of a projection display in an automobile using the windshield as a mirror surface.

Fig. 1 shows an exemplary embodiment of a projection display for reflecting an image to be displayed in a view of an occupant of a means of locomotion. The occupant may be, for example, a driver, a passenger or another passenger, and the means of transportation may be, for example, an automobile such as a car. a car, a truck, a bus, a motorcycle or the like. The semi-transparent, semi-reflective surface used for the reflection can be done by a windshield of the means of locomotion or, as exemplified in Fig. 1, by a specially provided, additional semi-transparent, semi-reflective disk or a so-called combiner 10.

Due to the fact that the display is intended to mirror an image to be displayed in the view of an occupant of a means of locomotion, the distance between Einspiegelungsfläche 10 and the occupant, exemplified in Fig. 1 by the double arrow 12, is more than 500 mm. such as. in about 800 mm to 2000 mm or for example 800 mm to 1000 mm. For the most part, it is desirable that the virtual image of the image to be displayed with the occupant appears at a distance 14 behind the reflection surface 10 which is greater than 1 m, e.g. 3 m is.

In order to perform the reflection of the image to be displayed under these conditions as desired, the projection display 16 of FIG. 1 comprises a single image generation unit 18 and a multi-channel optical system 20. The individual image generation unit 18 A plurality of individual images 22 in laterally juxtaposed manner testify from the image to be displayed. The multi-channel optical system 20 has, per channel, an optical system 22 for virtual imaging of a respective image associated with the individual image 22 on the reflection in the view of the occupant, so that the individual images extend over part of the view of the occupant in order to to give the image to be displayed.

The individual image generation unit 22 is designed, for example, to generate the plurality of individual images 22 by laterally varying transmission of a backlighting. FIG. 1 illustrates, for example, that the individual image generation unit has a flat light source 26 for the areal backlighting of an image generator 28, which is designed to influence the areal backlighting in the areas associated with the individual images 22 in such a way Regions the individual images 22 arise. The imager 28 can be, for example, an LCD display or the like whose image area is divided into the image areas for the individual images 22, and the planar illuminant 26 can be packed tightly side by side, for example, around an LED array arranged LEDs for the most uniform possible backlighting of the individual frames 22 associated sub-areas. Each LED could have a collimator. The individual image generation unit 18 may further comprise an image controller 30 to control the image encoder 28 from incoming image data 32 such that the individual images are correspondingly displayed in the subregions assigned to the individual images 22, as will be explained in more detail below, namely with a suitable orientation to the optics 20, a suitable distortion, etc.

In particular, the frame generating unit 18, such as e.g. the image controller 30, designed to copy the respective individual image 22 from the image 32 to be displayed for each channel. In this case, the individual image generation unit 22 can be designed to adapt the individual images individually for each channel. The adjustments may include distortion corrections, as described below. Each frame 22 may, for example, be copied from the entire image to be displayed, or merely from a respective part thereof, but the portions over all the frames 22 overlap in every feature of the image 32 to be displayed, such as e.g. in each point the sections of more than half of the individual images 22 overlap.

Each channel is thus made of the optics 24 and the associated individual image 22 or the respective individual image 22 associated subregion of the individual image generating unit 18th by creating this frame 22 is formed. In the following, the reference numeral 22 is used for the area as well as for the single image displayed therein.

The subregions of the individual image generation unit 18, in which the individual images 22 are displayed, are distributed two-dimensionally and arranged laterally next to each other, wherein FIG. 2 shows a section through the projection display along a row of these individual image subregions with associated optics of the multi-channel optical system 20. The frame sections are arranged, for example, in rows and columns. The area covered by the subregions of the frames 22, e.g. For example, the smallest rectangle that encompasses all the frame subareas encloses an area having a width, such as an area. Screen diagonals of, for example, more than 40mm or more than 2 inches or 5cm, e.g. 2 to 10 inches.

As can be seen in FIG. 2, the array of frame subareas 22 opposes the array of optics 24 of the multichannel optics 20 by having the optics 24 in the emission direction of the frame generator 18 behind their respective frame subarea 22. The spacing between the optics 24 of the multichannel optics 20 and the frame portions 22 is approximately equal to the focal length of the optics 24, which may be single lenses, e.g. single or double convex lenses or Fresnel lenses. On the other hand, it would be possible for the multichannel optics 20 to be integrally formed to form the optics 24.

In order to clarify the positional relationship between the array of the optics 24 and the individual image subregions 22 a little more, FIG. 3a shows a plan view of the projection display 16. In particular, in FIG. 3a, the laterally juxtaposed ones are arranged in an array As already mentioned, in the case of a planar mirror surface 10 and a position of the virtual image that is perpendicular to the viewing direction of the occupant, the apertures 34 of the optics 24, the apertures 34 of the optics 24, whose array arrangement in the lateral direction is preferably congruent to the array-moderate Arrangement of the frame portions 22 is. However, the congruence here should only refer to the centers of the individual image subregions 22 and the centers of the optical apertures 34. As far as the area or extent of the individual image subregions 22 and the apertures 34 is concerned, it may be that the surface shape is different. For example, the area of the frame portions 22 is substantially rectangular, but it may also vary between the individual channels, such as for correcting channel-specific registration errors of the respective channel optics 24. The congruent arrangement of the frames 22 relative to the optics array Deviations from the free-form geometry of the injection surface 10 can also be deviated from by a channel-specific adaptation, as will be explained later.

In Fig. 3a is for clarity for each optics 24 and the optical center 36 of the respective optics, i. For example, the position of the lens vertex or the optical axis or entrance pupil of the respective optics shown. As illustrated in Figure 3a, they may be offset from the apertured centers of the apertures 34, but central alignment with the respective apertures 34 for all optical centers 36 would also be possible. In particular, the offset may be configured such that the optical centers 36 are also arranged in an array that is congruent with the frame subregion centers.

Around the channels, i. the pair of optics 24 and associated frame portion 22, indicated at 38 in Fig. 2, are optically separated from each other, i. In order to prevent the single image 22 of an adjacent channel from entering the eye of the occupant through the optical system 24 of the channel under consideration, it is optionally possible to provide between the channels preferably absorbent separations 40 between multi-channel optical system 20 and individual image generation unit 18 Aperturzwischenräumen or aperture boundaries 42 run. Preferably, the frame portions 22 as shown in FIG. 1 are portions of an otherwise continuous image area of an imager 28 such that the centers of the frame portions 22 can be changed in position at any time, i. centric stretching and / or translation. A reduction of the frame center distance relative to the center distance of the optical centers 36 determines a divergence of the radiation field emanating from the projection display and thus the distance 14 of the virtual image in the field of view of the occupant. As already mentioned, the optical centers 36 are preferably in the center of the apertures 34, i. the center distances of apertures 34 and optical centers 36 are the same, but a greater distance would also be conceivable.

Figures 3b and 3c illustrate, for the exemplary case of equal center distances of apertures 34 and optical centers 36, the effect of varying the pitch of the frame areas of the frame: Figure 3c shows a larger frame center distance Pβiider than Figure 3c. so that the channel-individual optical axes 35 are less divergent in the case of Fig. 3c, and the virtual image 37 has a low distance L _tal from the eye 39 of the occupant. As will be described later, such an adjustment can be made by the image controller 30, which places the frames 22 respectively in the plane of the imager 28, and the adjustment can be made automatically done using an example of an eye track sensor signal or by user control.

Fig. 3b and c also show the following: The individual channels cover the EMB area by area. In the shown position of the eye 39, the occupant sees over the scene 37 via the middle channel 38, but when the occupant moves down with the eye 39 he sees the scene via the next channel 38 to the left, and so on. In order to be imperceptible to the occupant, these connections must be precisely adjusted to one another, ie the image 37 that the occupant sees at the transition between the channels must be the same or in the same place, because otherwise the occupant sees unsightly transitions or If he sees the image incorrectly in the transition areas, and if one considers the coexistence of both eyes of the observer, then the EMB cover can be designed such that the two eyes of the observer always look into different channels, ie so that they correspond to the individual channels EMB areas in the horizontal direction are smaller than the eye relief, or so that this is only possible at boundaries between horizontally adjacent areas of the EMB Case is. In any case, it may be desirable to adapt the accommodation of the eyes to the convergence of the eyes. As already stated, the individual image generation unit (18) could now be designed to generate the plurality of individual images 22 such that each individual image contains an entire image content to be transmitted. Regardless of where the occupant's eyes are, he would then see the entire scene. An eye of the occupant, even after moving from a portion of the eye-motion box covered by a first channel to portions of the eye-motion box covered by channels adjacent to the first channel, would see the same scene as the eye through the first Channel covered area, referring to all EMB area or all channels. This need not be. The circumstance could also apply only to subgroups of the channels or the associated EMB area. It could be that parts of the scene are only visible from certain EMB area groups or shown only in a certain group of channels, such as in a group of areas having a lower EMB margin, or a right and / or left EMB Cover the edge. Only the frames of the respective channels then showed the corresponding part of the scene, such as a radio program transmitter or a turn-off arrow or the like, or faded these parts into the corresponding portions of the EMB so as not to be visible from the remainder of the EMB. As will be explained later, the gap 42 between the apertures 34 is a point to consider in the design of the projection slide because of the fact that the projection display serves to mirror an image 32 to be displayed into the view of an occupant , the distance 12th from the inmate over the It is also possible for the user's eye to focus on the intermediate spaces 42. The gaps 42 should therefore be as small as possible. According to one exemplary embodiment, the multichannel optical system 20 is designed so that the individual apertures 34 of the optics 24 of all the channels 38 are adjacent to one another in terms of area with less than 10% gap 42.

In Fig. 3a with a cross 43 is shown a center of the array of frame center areas. A centric extension of the image area centers relative to this center 43 results in a change in the distance 14 of the virtual image from the mirror surface 10, while a translational movement of the image area centers leads to a similar movement of the center 43. The connecting line between center 43 and a center of the array of optical centers 36 in turn forms a kind of center of the optical beam path 44 which leads from the projection display 16 to the occupant and there defines the EMB. By translational movement of the array of image area centers and thus the position 43 relative to the center of the optical centers 36 thus results in a change in position of the EMB, whereby it is possible to follow a head movement of the occupant, so that he can see the virtual image always, as will be explained below.

For this purpose, reference is made to FIG. 3d, in that an EMF shifted downwards relative to FIG. 3c is shown in order, for example, to take account of an eye position displaced from 39 to 39 '. As can be seen, in contrast to Fig. 3c, the array of frames has been shifted toward the occupant, e.g. through the image control.

Thus, while the systems mentioned in the introduction to the introduction used a single-channel optical system to generate a virtual image regardless of the type of mirror surface used, the embodiment described with reference to FIGS. 1 to 3 represents an implementation of a concept for projecting virtual images, which has many advantages compared to the systems described in the introduction. The display can have a size of 2 to 10 inches. In the upstream lens array 20, each of the optics 24 contained therein is positioned at a distance from the respective individual image 22, so that a virtual image of the associated display region of the image generator 28 takes place. In particular, the optics frame distance corresponds to the paraxialcn imaging equation of an object width, which is slightly below the focal length of the optics 24. This results in an array of projection optics 24, which result in a coherent overall virtual image by their dense, two-dimensional arrangement of the pupils 36. Compared to Naligen systems, as described in the introduction to the description, due to the relatively small focal lengths of the optics 24 of the individual channels 38 in the same field of view or FOV a much more compact depth or a much more compact system volume can be achieved.

As a result of the comparatively large distances 12 of the occupant's eye to the lens array 20 in comparison with, for example, near-eye HMD or video glasses applications, special demands are placed on minimizing the visibility of the lens surfaces of the lenses 24, as just described. The following technical measures are useful for this, which reduce the visibility of the individual pupils: the backlighting could advantageously be designed in such a way that no stray light is produced which affects the image quality in the eye of the observer. - A collimated backlighting could be used to increase system efficiency. Collimating elements for reducing the divergence of the surface radiation of the light source 26, which produces the backlighting of the imager 28, can be designed differently. One way would be to use one collimator per frame area 22. Reducing the divergence provides for a higher light output of the virtual image seen by the occupant. For example, as shown in FIG. 4, a field lens array could be located between imager 28 and light source 26 and have one field lens per frame area 22, such that Köhler illumination of each individual projection channel 38 is achieved. The additional use of Feldlinscnarrays 28 between the backlight 26 and imager 28 ensures the Köhler illumination of each individual channel 38 and thus increases the efficiency even further and for a more homogeneous impression of brightness across the virtual image.

Preferably, the individual apertures 34, which may assume, for example, square, rectangular, hexagonal or round shapes (pupil shapes), are preferably tightly packed so that the channel intermediate regions 42 are as little as possible visible to the occupant. As already mentioned, the optics 24 may be formed by Fresnel lenses. Such a Fresnel lens array for forming the multi-channel optical system 20 would further reduce the construction height of the projection display 16 as well as achieve it. NEN that the Fresnel lens surface is less visible to the viewer, since the scattered light on the Fresnel lens surface could not be resolved by the eye of the observer.

So far, the exemplary embodiments 1 and 4 were at least in the illustrated variants of it. that the mirror surface 10 is planar, which can be achieved in the case of automobiles, for example, in that the actual windshield is preceded by a semi-transparent disc. In the embodiment of Fig. 5 this is not the case. The basic structure of the projection display 16 of FIG. 5 corresponds to that of FIG. 4: on the backlit display 18, here by way of example with the field lens array 44 between the planar light source 26 and the imager 28, images 22 which contain, for example, the entire image content to be transmitted contained in an array next to each other. Each of these partial images 22 is imaged by an associated lens 24 of the multi-channel optical system 20 as a virtual image. This arrangement creates for the viewer a coherent, virtual overall picture in his field of vision, namely by the reflection in his view. In the case of Fig. 5, however, the mirror surface 10 is a curved surface such as the windshield of an automobile. In the exemplary embodiment of FIG. 5, the image controller 30 may be designed to perform channel-wise or channel-specific predistortions of the individual images 22. This can have a beneficial effect on the image quality perceived by the viewer. In other words, the image controller can perform a channel-wise aberration correction to ensure perfect superposition of the virtual images of the individual adjacent channels 38, thus also compensating for the curvature of the front screen 10. To put it a little more precisely, the image control can compensate for the curvature differences that the individual channels "see" from the curved imaging surface 10 by displacing the images 22 relative to their position in relation to the array of optical centers 36. For example, see FIG. 3e shows the changed positions of the individual images 22 at the same image distance compared with FIGURE 3b. Of course, the lateral displacement vectors of the individual images 22 would only change continuously over the array of individual images 22 in the case of a continuous curved mirror surface 10. This channel-specific frame shift would again result in the above-mentioned adaptation of the channel transitions in the EMB For comparison, Fig. 3f shows the case or the optical axes of the channels without such a channel-individual position correction of the individual images 22 e sit at the congruent to the optical centers distributed positions - despite curved surface 10. As without Further, the ports of the channels in the EMB are not correct here: they overlap, which means that the occupant sees different images at the same time.

However, since, as can be seen in FIG. 3e, each channel 38 performs only one image over a small section of free-form surface 10, the aberrations are limited to lower orders, so that they are easier to correct. Each optic 24 can be made individually so that, for example, an astigmatism, as it results from a vertical and horizontal direction differently curved surface 10, is compensated, namely by a corresponding individual astigmatism of the optics 24. Also the small distance of the pupils of the optics 24 to the surface 10 makes a positive impression here.

In other words, the centers of the individual images can be placed in such a way and the individual images can be individually predistorted in such a way that regions of individual image connections to each other are not visible in the overall virtual image resulting from the individual images 22. This is done by calculating the desired positions of two pixels in the overall image following two channels with known field size (= position with respect to the lens center, this determines distortion) with knowledge of the introduced by the single lens or mirror surface 10 field-dependent distortion or astigmatism. A subsequent individual transformation of all partial images, which corresponds to a channel-wise predistortion and / or pre-distortion, takes place with the goal of a good overall image impression, free from visible image connections. Fig. 5b shows only once again the scene of Fig. 5a from a slightly different angle. As already mentioned, the difference between FIGS. 5a and 5b and FIG. 4 is merely that in FIG. 4 only a planar, reflective optical surface was used for generating a virtual image superimposed on the environment. If a free-form reflecting surface 10 is used, as shown in FIGS. 5a and 5b, the channel-wise compensation of the aberrating effect of this surface 10 can be compensated for or at least reduced by the manipulation of the individual projections or image preprocessing in the image disturbance 30 become.

FIG. 6 shows the use of previously described projection displays in an automobile 50. In particular, the projection display 16 of FIG. 4 is shown. That is, it is located in the direction of travel and sight 52 behind the instrument panel 54 of the seat 56 for the driver of the automobile 50 on the inside of the windscreen 58 a specially designed for Einspiegdung, preferably planar disc 56. Also called combiner 60. via which / which the projection display 16 performs the reflection of the virtual image into the driver's view. Thus, FIG. 6 illustrates the use of a separate optical surface 60 for reflecting the virtual image into the driver's direct field of vision. The overall virtual image results from the superposition of a multiplicity of two-dimensionally distributed individual projectors formed from the two-dimensional arrangement of channels 38 become.

FIGS. 7a and 7b once again illustrate the use of the front screen 58 as a reflecting optical element 10 in the beam path. The multi-channel arrangement of the projection display 16 permits the compensation of the aberrations introduced by this surface 58, namely, for example, distortion and astigmatism. The compensation can be done electronically, e.g. via the aforementioned image control 30, done. However, it is also possible for a channel-specific adaptation of the shape of the optically effective surfaces of the optics 24 to be provided during the production.

Compared to conventional single-channel HUDs with, for example, a multiple mirror system, the shorter distances between the projector pupils, i. the entrance pupil of the optics 24, the mirror surface 10, namely the windshield 58 in the case of Fig. 7a and 7b, a strong simplification of aberration minimization. As described, the location or distance 14 of the virtual image plane in which the individual sub-images 22 overlap for the viewer or occupants may be influenced by increasing or decreasing the distances between the centers of the individual images 22 on the imager 28 , Thus, a purely software-technical adaptation of the image width of the virtual image or an adaptation of the projection distances is possible. An enlargement of the distances of the image centers of the individual images 22 to each other thereby increases the distance of the virtual image plane from the viewer.

A decentering of the eye of the observer, ie the driver in the case of the embodiments of Figs. 6-7b, with respect to the optical axis of the projection display 16, ie with respect to the center of the beam path 45 in the case of laterally non-displaced centers of the frame center region relative to the observer An array of optical centers can lead to the perception of ghost images by the observation of partial images of the image generator, not by the associated but by adjacent optics 24, ie by a so-called "crosstalk." To avoid this, the optionally provided separations 44 A uniform lateral or vertical displacement of all partial images 22 on the image generator 28 controlled by the image preprocessing in the image control 30 makes it possible within certain limits to compensate for such decentration in order to avoid crosstalk. In other words, it is possible to supplement the projection display 16 with an eye-tracking sensor. Such is illustrated by way of example in FIG. 7 a and provided with the reference numeral 70. This sensor 70 could be connected to the image controller 30, which in turn derived from the obtained position information of the eyeball of the driver, a target signal for decentering the sub-images 22 and the sub-images 22 are positioned so that, for example, the optical axis 45 leads to the eye and the previously described decentering the eyes of the occupant relative to the beam center 45 does not lead to ghosting. The image controller 30 will thus perform a translational shift of the partial images 22 or of the partial image region centers as a function of the position of the eyes of the driver or occupant such that, for example, the optical axis 45 points in the direction of the eyes.

Instead of an automatic change of the position of the EMB controlled via the eye tracker 70 or in addition, it would be possible for example in the instrument panel 54 or elsewhere, such as e.g. on the dashboard there is a manual input facility for the occupant to perform the change in the position of the EMB or a change in the direction of the optical axis 45. Depending on the sensor 70 and / or the manual input option, it would also be possible to adjust the centering, i. to allow the adjustment of the distance 14 of the virtual image, e.g. to adapt to a refractive error of the occupant and different objects in the image at different distances. A full-color representation can be achieved by a time-sequential switching of the partial images 22 in the primary colors RGB. Alternatively, RGB pixel triplets or superpixels are also conceivable which, however, reduce the number of pixels that can be represented for a given pixel size. Color transverse defects in the virtual image can be precompensated by suitable image preprocessing for the color-dependent predistortion of the primary color images.

As for the above embodiments, it should be noted that they are not limited to the application in automobiles. Furthermore, instead of backlit displays or Bildgebem 28 also self-illuminating displays or imagers can be used. It would also be possible to use a separate imager for each frame or for a subset of the frames. Furthermore, instead of a pixellated imager, a mask, such as a chrome mask, could be provided per frame, possibly even with areawise backlighting of individual mask or image objects in the individual frames. In all embodiments, it is possible different Display objects in the image at different image distances, such as speed-dependent.

As far as the image control 30 in the exemplary embodiments is concerned, it is pointed out that in the simplest embodiment it represents only an internal interconnection of the image generator, after which the incoming image data 32 are distributed to the individual image subregions. Alternatively, the image control can also have a processor which carries out the predistortion, for example by channel-specific distortion of the incoming image 32, in order in this way to reproduce a single image distorted in relation to the image 32 in each individual image subregion. Further, the multichannel optics 20 and frame imaging unit 18 may be packaged within a housing for ease of handling to be recessed as a whole inside the windshield 58 of an automobile, such as in the interior trim, in a corresponding opening.

As a result of the above embodiments having a multi-channel optical design, i. use a lens array to generate a continuous virtual image in the field of view of the driver, reduce the distances of the individual pupils of the array to the mirror surface, such as a single-channel projection optics. the windscreen. This reduces the aberrations introduced into the optical image by the free form of the mirror surface. This in turn simplifies the measures for optical compensation, namely, as mentioned above, for example, the software distortion in the image control or already in the production or design of the optics 24 in a channel-individual way measures taken in the form of a channel wise correction. Each individual projector 24 sees a well-defined area of the windscreen. The image content corresponding to the channel can be correspondingly predistorted in order to again be able to produce a clear overall image for the viewer. In other words, channel-by-channel adaptation of the individual object structures can compensate for the aberrations additionally introduced by the mirroring optics into the system, such as e.g. Compensating or reducing astigmatism, etc.

The above embodiments also showed that it is possible. perform an electronic adjustment to the driver's head position by image preprocessing. An electronic adaptation of the image removal 14 or the setting of multiple distances is possible. In addition to the above description, it should be noted that instead of a transmissive imager as used in the previous embodiments, a reflective imager may also be used. Finally, the possibility should be briefly discussed once again to set the distance 14 of the virtual image by electronic offset of the partial images 22 in the image generator 28 relative to one another. The geometric facts depend on the following relationships: L total = ^L HUD + = ^ HUD + ^? ~ with S = ^ * / for irf »f

Ppupil pictures ^ virt J

Here, L _total removal of the eye of the viewer to the virtual image, L _v i _rt, the distance of the virtual image to the lens array, LHUD the distance of the lens array to the eye of the viewer, p _pup ii, the center distance of the individual pupil 36 to each other, Pßiider the pitch of the Images 22 on the imager and s the intercept of the individual optics 24, which is usually designed to be slightly smaller than the focal length f of the individual optics 24 in order to project a virtual single image or an ensemble of virtual individual images.

Thus, if the center distance of the individual images 22, Piideri, is reduced, the distance 14 of the virtual image increases.

Once again, in briefly other words, the above embodiments have shown a projection display with an imager, an optics array, and optionally other elements for mirroring a virtual image over a mirror surface into the view of an occupant of a vehicle. The reflection can be done in particular via a combiner mirror, which may be planar, convex or concave, or a windshield. Artifact suppression may be provided, for example, mechanically via adjustment of edge steepness, transition radii or the like, or optically, via channel-wise distortion correction, collimated backlighting, or the provision of Fresnel structures. A reduction of operations introduced via a non-planar mirror surface can be done by a channel-by-channel compensation of the distortion. An aberration reduction is inherently also already by the stacked structure, namely by the ability to zoom closer to the Einspiegelfläche. The latter distance, namely the distance of the projection screen 16 from the mirror surface 10, for example, is less than 8 cm. The above exemplary embodiments are therefore ideal for applications in the automobile. The optical performance of I IUDs in automobiles is highly dependent on the geometric shape of the reflective surface. When using the windscreen as an optically effective device is inevitably faced with their geometric shape tolerances due to mass production. In conventional systems, you can only change the image content on the display, so only correct a distortion.

In the above embodiments, the distortion of the entire image may be corrected, but also channel-by-channel pre-distortion may be provided to suppress adverse effects of non-planar mirror optics for optical imaging. Furthermore, an adaptation of the optical image aberrations introduced by the free-form mirror surface can be corrected by image preprocessing on a channel-by-channel basis. For the occupant, there is also a movement tolerance by some of the above embodiments. After the latter Ausflihrungsbeispielen namely an electronically adjustable EMB is provided.

The above Ausfüihrungsbeispiele are also advantageous in terms of space. The construction area can be kept small. Since the above Ausiuhrungsbeispiele get along without field lens, although results in a reduced resolution in the virtual image, but it also just results in a larger EMB or head-motion box and due to the use of a variety of short focal length projection optics 24 a much more compact design, i. Compared with conventional HUD optics, which use free-form mirrors to generate the virtual image, there is a saving in space, for example, more than 60%.

In addition, adaptations are also possible according to some of the above exemplary embodiments. By image preprocessing, it is possible to set electronically controllable and / or multiple imagers 14. Image distances to the eye and / or adaptations to human visual defects are possible. With a single mirror optics, this is not possible.

Another advantage of the above embodiments is the robustness. In contrast to conventional systems, only one optically effective surface is needed, namely that of the multi-channel optics, and this can be realized in an optical component, i. in one piece or the like. This simplification of the overall structure results in an increased robustness.

Claims

Patent claims

Projection display for reflecting an image (32) to be displayed into a view of an occupant of a means of transport, with: an individual image generation unit (18) for generating a plurality of individual images (22) arranged laterally next to one another from the image to be displayed, and a multi-channel optics (26) with, per Channel (38), an optics (24) for the virtual imaging of an individual image (22) assigned to the respective channel via the reflection into the view of the occupant, so that the individual images extend over part of the view in order to produce the image to be displayed , and so that the channels cover areas of an eye motion box of the projection display.

Projection display according to claim 1, in which the individual image generation unit (18) is designed to copy the respective individual image (22) from the image (32) to be displayed for each channel (38).

Projection display according to claim 1 or 2, in which the individual image generation unit (18) is designed to copy the respective individual image (22) from the image (32) to be displayed for each channel (38) and to set the centers of the individual images 22 channel-individually compared to one To shift the centers of optical centers (36) of the optics (24) to a congruent position, so that despite a curvature of the reflection in an eye motion box of the projection display, the centers of the individual images are placed in such a way and the individual images are individually pre-distorted in such a way that in one In the individual images, the virtual overall image areas of connections between the individual images created by the virtual image of the individual images are not visible to one another.

Projection display according to claim 1, 2 or 3, in which the multi-channel optics are designed such that each optics is individually designed to correct an aberration introduced into the virtual image of the respective individual image by an area of the reflection assigned to the respective channel.

Projection display according to one of claims 1 to 4, wherein the individual image generation unit (18) is designed to generate the plurality of individual images (22) by laterally varying transmission of backlighting.

Projection display according to claim 5, in which the individual image generation unit (18) has an array of LEDs for backlighting.

Projection display according to claim 5 or 6, in which the individual image generation unit (18) has collimating optics for collimating the backlighting.

Projection display according to claim 7, in which the collimating optics have a field lens array (44) with one field lens per channel, which is designed to implement Köhler illumination for the respective channel.

Projection display according to one of the preceding claims, in which the individual image generation unit (18) is designed such that the individual images (22) together laterally occupy an area with an extent of more than 40 mm.

Projection display according to one of the preceding claims, in which the multi-channel optics (20) is designed such that the individual apertures (34) of the optics (24) of all channels (38) border one another in terms of area with less than 10% gap (42).

Projection display according to claim 10, in which the multi-channel optics (20) is formed in one piece.

Projection display according to claim 10 or 1 1, in which the optics (24) of the channels are each designed as a Fresnel lens.

Projection display according to one of the preceding claims, which further has a sensor (70) for detecting a position of the occupant's eyes and a control (30) for lateral decentering and / or translation relative to the multi-channel optics of the individual images depending on the position of the eyes.

Projection display according to one of the preceding claims, further comprising a control (30) for lateral decentering and/or translation relative to the multi-channel optics depending on user input.

Projection display according to one of the preceding claims, in which the individual image generation unit (18) displays the plurality of individual images (22) laterally next to one another. arranged differently from the image to be displayed so that each individual image contains the entire image content to be transmitted.

16. Projection display according to one of the preceding claims, in which the individual image generation unit (18). the plurality of individual images (22) arranged laterally next to one another are generated from the image to be displayed in such a way that an eye of the occupant, even after movement from an area of the eye motion box covered by a first channel, into areas of the eye motion box covered by channels adjacent to the first channel Eye Motion Box sees the same scene that the eye sees from the area covered by the first channel.

17. System with a projection display according to one of the preceding claims and the single-mirror surface.

18. Means of transport with a projection display according to one of the preceding claims.

19. Means of transport according to claim 18, which is designed as an automobile, wherein the projection display is arranged such that the image to be displayed is reflected into the driver's view.

20. Means of transport according to claim 19, in which the reflection takes place through a windshield (58) or an additional combiner mirror (60).