Projection system

Abstract

The invention relates to a projection system having - a projector (22, 22'); and - a retroreflector (23), wherein the projector (22, 22') illuminates the retroreflector (23) and the retroreflector (23) reflects in a certain solid angle range.

Description

[0001] 202405074

[0002] 1

[0003] Description

[0004] Projection system

[0005] The present invention relates to a projection system. Such projection systems are used, for example, in a head-up display to generate a virtual image on the windshield or to project it onto other windows or surfaces of a motor vehicle.

[0006] A head-up display, also known as a HUD, is a display system that allows the viewer to maintain their line of sight by projecting the content into their field of vision. While such systems were originally used primarily in aviation due to their complexity and cost, they are now also being mass-produced in the automotive industry.

[0007] Head-up displays generally consist of an image-generating unit (PGU), an optical unit, and a mirror unit. The image-generating unit creates the image, using at least one display element. Modern head-up displays typically use displays or scanning systems for image generation. Displays can be, for example, LCDs (LC: Liquid Crystal), p-LED displays (LED: Light Emitting Diode), LCoS displays (LCoS: Liquid Crystal on Silicon), or DMD systems (DMD: Digital Micromirror Device). A laser scanning system is an example of a scanning system. The optical unit directs the image onto the mirror unit. The mirror unit is a partially reflective, translucent disc.The viewer thus sees the content displayed by the imaging unit as a virtual image and simultaneously the real world behind the glass. In the automotive sector, the windshield often serves as the mirror unit, its curved shape being taken into account in the display, for example by pre-distorting the image displayed by the imaging unit. (See 202405074.)

[0008] 2

[0009] The interaction of the optical unit and the mirror unit results in a virtual image that is an enlarged and distorted representation of the image produced by the imaging unit.

[0010] Projection systems generally consist of a projector with a picture generating unit (PGU) and a projection surface on which a real image is visible. The projection surface can be a transparent window pane of a vehicle or an opaque projection surface, such as one mounted on a vehicle's dashboard. The picture generating unit creates the image, using at least one display element. Modern projectors typically use displays or scanning systems for image generation. Displays can include, for example, LCDs (Liquid Crystal), p-LED displays (Light Emitting Diode), LCoS displays (Liquid Crystal on Silicon), or DMD systems (Digital Micromirror Devices).An example of a scanning system is a laser beam scanner (often abbreviated as LBS). In this system, a laser beam modulated with image information is guided across the projection surface. This can be done, for example, in a line grid. If the projection surface has a diffuser, the image drawn by the laser beam can be seen by a viewer. Since the laser beam has a small angular spread (small aperture angle), the light coming from the diffuser is also generally limited to a specific angular range. This depends on the diffuser's scattering properties. If the diffuser scatters over a large angular range, then less light reaches the viewer's eye than with a diffuser that has a small angular range. For energy-saving reasons, a diffuser that scatters over a relatively small angular range is therefore usually used.This also benefits the brightness of the image, which can be achieved with the given, usually quite limited, projector output. The smaller the angle of dispersion of the diffuser, the greater the perceived brightness of the image. 202405074.

[0011] 3

[0012] The diffuser can be, for example, a scattering, possibly backscattering, and transparent disc. Partial scattering or backscattering is desirable for the projection to be visible. The viewer then sees the content displayed by the imaging unit as a virtual image and simultaneously the real world behind this disc. In the automotive sector, a side window or the rear window, another transparent or reflective surface, or even an opaque surface, such as the dashboard or headliner, often serves as the projection surface. The curved shape of these surfaces is taken into account during the projection, for example, by pre-distorting the image displayed by the imaging unit.

[0013] The viewer can only perceive the virtual image of a head-up display or the real image emanating from a diffuser from the position of the so-called eyebox. The eyebox is defined as an area whose height and width correspond to a theoretical viewing window. The size of the eyebox depends on the angle of incidence of the light coming from the display element or the diffuser. As long as the viewer's eye is within the eyebox, all elements of the virtual or real image are visible. If, however, the eye is outside the eyebox, the virtual or real image is only partially visible or not visible at all. Therefore, the larger the eyebox, the less restricted the viewer is in their choice of seating position.When using a diffuser, the eyebox is not sharply cut off at the edge, as is the case with a head-up display without a diffuser. Instead, the image brightness decreases towards the edge of the eyebox, but it may still be visible further outside. In this case, the eyebox boundary can be defined, for example, by a relative decrease in the image brightness.

[0014] The optical unit of a head-up display typically includes several mirrors to minimize the required installation space. The light emitted from the imaging unit is directed by a folding mirror onto a curved surface.

[0015] 4

[0016] The mirror reflects the light, which is then reflected towards the windshield. Currently used curved mirrors are essentially flat plates with a high degree of curvature, corresponding to the desired optical function.

[0017] In laser beam scanner (LBS) systems, light from RGB color laser diodes is scanned across the display area by a scanner that, for example, incorporates oscillating MEMS mirrors (MEMS: micro-electro-mechanical system). The image is then generated on the display area by modulating the power of the color laser diodes synchronously with the movement of the mirrors. Compared to LCD-based display solutions, laser scanning systems are characterized by less complex optics, higher energy efficiency, and different cooling requirements.

[0018] Laser scanning systems typically exhibit higher power dissipation than LCD-based display solutions. The latter can therefore often be passively cooled, while laser-based systems in the automotive sector generally require active cooling, such as cooling using Peltier elements. As an alternative to RGB color laser diodes, a short-wavelength laser can also be used to scan an RGB wavelength converter in a suitable intermediate image plane.

[0019] Laser beam scanner systems can project image content onto a variety of surfaces. For example, in a vehicle, image content can be projected onto surfaces such as the dashboard, ceiling, or windows.

[0020] With coherent light, such as that emitted by a laser light source, unwanted speckle patterns often appear, which should be reduced or eliminated to achieve a good image quality. Speckle patterns, light granulation, laser granulation, or simply speckle, refer to the granular interference phenomena that occur, for example, when optically rough object surfaces (irregularities in the 202405074) are illuminated with sufficiently coherent light.

[0021] 5

[0022] These effects can be observed on the order of the wavelength. In more ordered structures, such as lens arrays, the interfering interference effects can also exhibit a higher degree of order. At this point, we broaden our definition of speckle or speckle pattern to include such effects.

[0023] The term "speck," which refers to both a single spot of light and the entire interference pattern, is derived from the English word "speckle." Depending on the imaging system used, the predominantly English-language literature also distinguishes between "subjective speckle" and "objective speckle": If the speckle is projected directly onto a screen without the aid of a lens or other optical devices, it is called objective speckle. In contrast, subjective speckle refers to the imaging of the interference pattern using a lens or more complex optical systems. This includes the human eye.

[0024] In known designs, the MEMS mirror of the laser beam scanner is a flat element which is connected to the surrounding structure via thin elements and is excited to vibrate via further elements, such as piezoelectric elements.

[0025] The oscillating MEMS mirror reflects the incoming collimated, modulated laser beam and directs it through a subsequent projection optic to focus the beam and create the desired pixel at the desired distance. However, there are also variants with a convergent modulated laser beam.

[0026] In a so-called windshield root display, the image of a display positioned some distance away is reflected in the lower part of the windshield, also known as the windshield root. Due to the distance of the display from the windshield root, the reflected image appears to the viewer to be behind the windshield root. Therefore, similar to a head-up display, the eye does not need to focus on a very short distance.

[0027] 6. This simplifies the transition from observing the traffic situation in front of the vehicle to viewing the windshield root display. Today's windshield root displays reflect specular planar displays that are mounted on or in the dashboard.

[0028] Disc root displays (hereinafter referred to as "display" and "indication" are used interchangeably) are currently implemented using displays recessed beneath the disc. Alternatively, solutions are being discussed in which the display is projected directly onto the disc. Disadvantages of this approach include: displays are dim and energy-intensive; multiple displays arranged side-by-side do not blend seamlessly, thus interrupting the image visible to the viewer; and projecting onto the entire disc, which requires a projection screen integrated into the disc, leading to susceptibility to stray light and poor contrast, as well as a shorter projection distance.

[0029] The light from the displays is distributed over a wide area. This requires a lot of energy, and all viewers see the same image. The virtual image is always visible at approximately the same distance as the base of the disc.

[0030] An optimization of the disc root display is desired.

[0031] A projection system according to the invention comprises a projector and a retroreflector. The projector illuminates the retroreflector, and the retroreflector reflects the light within a certain solid angle range.

[0032] The retroreflector does not reflect light back exclusively in a 180° arc, but rather within a certain solid angle range, for example, 10° around the axis of an incident light beam. This ensures that the viewer's eye does not need to be positioned precisely in the projector's line of sight. 202405074

[0033] 7

[0034] According to one embodiment of the invention, the retroreflector, which reflects into a certain solid angle range, is a direction-changing reflective scattering screen. This is a scattering retroreflector; according to this embodiment, the retroreflector corresponds to a projection screen. Since this embodiment is not a retroreflector in the strict sense, it can also be described as a directional scattering screen that does not reflect back exactly, but rather deflects the reflection.

[0035] The retroreflector advantageously changes the direction of the light. In this case, the retroreflector only acts as a retroreflector in a first plane, where its output rays are parallel to its input rays, while this is not the case in a second plane perpendicular to the first. In this second plane, the classical rule applies, for example, that the angle of incidence equals the angle of output.

[0036] The retroreflector advantageously changes the direction of light differently at different locations. In this case, the retroreflector only acts as a retroreflector in a first plane, where its output rays are parallel to its input rays, while this is not the case in a second plane perpendicular to the first. In this second plane, the direction of light changes differently depending on the relative position to the projector. This locally varying change in the direction of light is advantageously achieved in such a way that the emitted light is directed towards the eyebox, i.e., towards the eye(s) of a viewer. This has the advantage that even if the projector is positioned relatively close to the retroreflector, its light rays reach the viewer's eye. For the viewer, the image projected by the projector then appears to be located behind the base of the disc, i.e., further away than the disc itself.This has the advantage that when switching from viewing the surroundings through the windshield to viewing the display at the base of the windshield, the eye only needs to adjust its focus slightly compared to looking directly at a display at the base of the windshield. This is a similar effect to that achieved with a head-up display. 202405074.

[0037] 8

[0038] In a vehicle according to the invention, the retroreflector is arranged below the base of a windscreen. This has the advantage that the retroreflector is not directly visible to an observer sitting in the vehicle. This distracts the observer less from the traffic situation and thus contributes to improved safety, for example in road traffic.

[0039] In a vehicle according to the invention, the disc root advantageously has a scattering function. This scattering function is achieved, for example, by a scattering film applied to the disc root, by a scattering paint layer applied to the disc root, by a scattering surface structure of the disc root, or in another suitable manner. The disc root thus advantageously serves as a projection surface onto which a viewer can see an image projected by the projector, largely independent of their position. If the retroreflector itself does not have a scattering function and therefore does not serve as a scattering projection surface, the disc root then serves as the projection surface.

[0040] In one embodiment, a reflector surface is positioned in front of the windshield's base. The light coming from the retroreflector is thus reflected by the reflector surface, which is designed, for example, as a plastic surface, instead of by the windshield. Advantageously, the reflector surface is a freeform reflective surface. This has the advantage that the reflection occurs at the reflector surface, whose geometric shape and reflective properties are easier to optimize for the projection system than those of the windshield's base. Insofar as the shape and properties of the windshield's base cannot be optimized for the projection system, or only with great difficulty, the use of a reflector surface eliminates the need for otherwise necessary adjustments to other components of the projection system.

[0041] According to one embodiment, the projector is arranged at the upper edge of the disc, the edge furthest from the disc root. This increases the 202405074

[0042] 9

[0043] The projection distance creates the impression of a distant virtual image for the viewer. The eye's adjustment from infinity to the distance of the virtual image is thus faster. This is less distracting and therefore contributes to increased safety. In the embodiment of the invention where the retroreflector is a direction-changing reflective screen serving as the image surface, the distance of the projector from the direction-changing reflective screen has no influence on the perceived distance of the virtual image. This perceived distance depends solely on the position of the screen. The advantage of mounting the projector at the top of the disc in this embodiment of the invention lies in the simplified projection and the fact that only a few, ideally a single, projector can be used to project the entire surface of the direction-changing reflective screen.

[0044] In one embodiment, the projector is positioned near the base of the windshield. While this reduces the distance between the virtual image and the viewer, it also minimizes the likelihood of interfering objects or media being located between the projector and the windshield base. A lower probability of interference reduces the likelihood of distraction for the viewer, especially the driver, thus contributing to increased safety. Furthermore, this design allows for a compact and fully integrated solution.

[0045] According to one embodiment, several projectors are arranged in the vehicle to illuminate the retroreflector. This makes it possible to illuminate a larger, contiguous area without the brightness of the image information reaching the viewer being too low or requiring high power from a single projector. The projection areas of the individual projectors can overlap completely or only partially. In the case of complete overlap, it is not critical if interfering objects or media are located between that projector and the base of the windscreen, as long as the majority of the other projectors are not subject to such interference. 202405074

[0046] 10

[0047] It is advantageous if at least one of the projectors is a laser beam scanner.

[0048] Instead of displays, a retroreflective projection screen is recessed into the dashboard below the base of the windshield. This screen is continuously illuminated by a wide-angle laser projector or several projectors with narrower beam angles. The screen is viewed from above the base of the windshield. The projector(s) are either also located in the recess of the dashboard or in the upper part of the windshield. Alternatively, a flexible "visor" reflector can be positioned in front of the windshield as a reflector screen.

[0049] The invention relates to a projection-based windshield root display, also known as a scenic view HUD, based on a retroreflector. Advantages of the solution according to the invention and its embodiments are: They are more energy-efficient than conventional displays, they exhibit better image characteristics, and they enable a continuous image, whereas with adjacent conventional displays, a boundary area always remains visible between them. The solution according to the invention and its embodiments are very compact. Compared to direct projection onto the windshield, a greater projection distance is achieved, less stray light occurs, and in the case of a reflector screen, it can be recessed, resulting in a more refined cockpit appearance.

[0050] The invention can be applied to all types of vehicles.

[0051] Further features of the present invention will become apparent from the following description and the attached claims in conjunction with the figures.

[0052] Figure overview 202405074

[0053] 11

[0054] Fig. 1 schematically shows a head-up display;

[0055] Fig. 2 shows an embodiment of an imaging unit;

[0056] Fig. 3 shows an imaging unit according to the invention;

[0057] Fig. 4 shows a projection system;

[0058] Fig. 5 shows a projection system with a laser beam scanner;

[0059] Fig. 6 shows a laser beam scanner mounted in a dashboard;

[0060] Fig. 7 shows an area marked in Fig. 6;

[0061] Fig. 8 shows an area marked in Fig. 6;

[0062] Fig. 9 shows a projection system according to the invention in sectional view; and

[0063] Fig. 10 shows the embodiment of Fig. 9 in a top view.

[0064] Character description

[0065] To better understand the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. The same reference numerals are used in the figures for identical or equivalently acting elements and are not necessarily described again for each figure. It is understood that the invention is not limited to the embodiments shown and that the described features can also be combined or modified without limiting the scope of the invention.

[0066] 12

[0067] to leave the scope of protection of the invention as defined in the attached claims.

[0068] Fig. 1 schematically shows a head-up display for a vehicle as an example of an image generation system 1. The head-up display comprises an imaging unit 2, an optical unit 3, and a mirror unit 4. A beam of light SB1 originates from a projection surface 21 and is reflected by a first mirror 31 onto a curved mirror 32, which reflects it towards the mirror unit 4. The mirror unit 4 is represented here as the windshield 41 of the vehicle. From there, the beam of light SB2 travels towards the eye 61 of a viewer.

[0069] The viewer sees a virtual image VB, which is located outside the vehicle, above the hood or even in front of the vehicle. Through the interaction of optical unit 3 and mirror unit 4, the virtual image VB is a magnified representation of the image coming from the projection surface 21. Here, a speed limit, the current vehicle speed, and navigation instructions are symbolically displayed. As long as the eye 61 is within the eyebox 62, indicated by a rectangle, all elements of the virtual image are visible to the eye 61. If the eye 61 is outside the eyebox 62, the virtual image VB is only partially visible or not visible at all. The larger the eyebox 62, the less restricted the viewer is in choosing their seating position.The curvature of the curved mirror 32 is adapted to the curvature of the windshield 41 and ensures that the image distortion is as stable as possible across the entire eyebox 62. The curved mirror 32 is rotatably mounted by means of a bearing 321. The resulting rotation of the curved mirror 32 allows the eyebox 62 to be moved and thus its position to be adjusted to the position of the eye 61. The first mirror 31 serves to ensure that the path traveled by the beam SB1 between the projection surface 21 and the curved mirror 32 is long, while simultaneously keeping the optical unit 3 compact. The optical unit 3 is supported by a 202405074.

[0070] A transparent cover 33 separates the optical elements of the optical unit 3 from the surrounding environment. This protects them, for example, from dust present in the interior of the vehicle. A glare shield 34 serves to reliably absorb light reflected across the interface of the cover 33, thus preventing glare for the viewer. In addition to sunlight SL, light from another ambient light source 64 can also reach the projection surface 21.

[0071] Fig. 2 schematically shows an embodiment of an imaging unit 2 with light sources 14R, 14G, 14B that emit coherent light. The figure shows a controllable mirror unit 73 in the imaging unit 2, which acts as a display element 11. The mirror unit 73 consists, for example, of a two-dimensional arrangement of micromirrors, each of which is positioned in one of two positions when controlled. A light beam LB incident on it is thus modulated in a pixel grid to generate the virtual image VB. This is a DMD. According to another embodiment, the controllable mirror unit 73 consists of a mirror adjustable about several axes, which is controlled such that an incident laser beam is reflected according to a two-dimensional grid, thereby generating the virtual image VB.

[0072] The light beam LB, which strikes the micromirrors of mirror unit 73, or the laser beam that falls on the mirror adjustable about several axes, originates from the light sources 14R, 14G, 14B. The light sources 14R, 14G, 14B are indicated here as schematic boxes. They can be designed as conventional light sources, for example as light-emitting diodes (LEDs), or as laser light sources.

[0073] Fig. 3 shows an imaging unit 2 according to the invention. The light sources 14R, 14G, 14B are designed as laser diodes. The light emitted by them is collimated, indicated here by means of lenses 151. The light emitted by the three light sources is focused by means of a mirror 161 or by means of two dichroics 162, 163.

[0074] The emitted light is combined in a common direction of propagation. It passes through a lens, which here schematically represents an illumination optic 155. It is then deflected by means of the mirror unit 73 as an image transmitter 11 according to an image to be displayed. It then reaches a lens, which here schematically represents a projection optic 156. It then reaches a diffuser 172 arranged in the projection surface 21 of the projection optic 156. After the diffuser 172, the light continues as a beam SB1.

[0075] Fig. 4 schematically shows a projection system comprising a projection device as the imaging unit 2, here a laser beam scanner 22, which is installed inside a vehicle 100. The laser beam scanner 22 is shown, by way of example, mounted on a rearview mirror of the vehicle 100. The laser beam scanner 22 projects an image onto the instrument panel, which serves here as the projection surface 21. The projection image is indicated here as a direction and speed indication. A computer unit 52 executes an algorithm that controls the laser beam scanner 22 to generate the desired image at the desired location. Since the instrument panel is not a flat surface but a three-dimensionally curved surface, the projection surface 21 is also curved accordingly; the computer unit takes this curvature into account when controlling the laser beam scanner 22.As an example, another laser beam scanner 22' is arranged on the rearview mirror of the vehicle. This laser beam scanner 22' is aligned with a side window, which forms its projection surface 21'. A circular diffuser 172 is arranged on the side window. The laser light coming from the laser beam scanner 22' is scattered by the diffuser 172 into a limited angular range. Depending on the scattering properties of the diffuser 172, a real image is visible both from inside the vehicle and from outside the vehicle, as long as the viewer's eye is within the corresponding angular range, i.e., within the eyebox. 202405074.

[0076] 15

[0077] Fig. 5 schematically shows a projection system with a laser beam scanner 22 as the imaging unit 2 and a projection surface 21. The beam generator 140 produces a modulated collimated light beam LBM. The beam generator 140 contains, for example, light sources 14R, 14G, 14B, lenses 151, mirrors 161, dichroics 162, 163, illumination optics 155, and electronic control elements, which are not shown in this figure. The modulated light beam LBM is reflected by the mirror unit 73. The reflected light beam LBR passes through a projection optic 156 and reaches the projection surface 21. Due to the modulation, the light beam LBM carries image information that is synchronized with a movement of the mirror unit 73, so that the image to be displayed is formed when the reflected light beam LBR moves on the projection surface 21.

[0078] Fig. 6 shows a laser beam scanner 22 in the lower section, which is arranged in the dashboard 101 of a vehicle. Adjacent to the dashboard 101 is the windshield 41, which is connected to the vehicle at its lower edge by its base 411. A retroreflector 23 is arranged between the base 411 and the dashboard 101. It is indicated here by two surfaces 1621, 1622 inclined at almost right angles to each other, which reflect incident light back into themselves at a 90° angle. Since an angle other than 90° is used, the retroreflection occurs within a certain solid angle. A light beam LBR coming from the laser beam scanner 22 is reflected by the retroreflector 23 and is reflected by the disc 41 in the area of ​​the disc root 411 as a light beam LBSW in the direction of an observer, in this case the driver.Another or alternative laser beam scanner 22' is arranged at the upper edge of the windshield 41 and directed at the retroreflector 23. Alternatively, a reflector surface 412 can be arranged in front of the windshield root 411. In the figure, it is tilted sharply relative to the windshield root. In this position, the retroreflector 23 only needs to illuminate a small angular range around the direction of back reflection. 202405074.

[0079] 16

[0080] The upper part of the figure shows a three-dimensional representation of the windshield 41. It can be seen that several laser beam scanners 22 are arranged in the dashboard 101. These illuminate the retroreflector 23, which—not directly visible in this view—is located behind the dashboard 101. The area of ​​the windshield root 411 is shown hatched; the light reflected there is visible to passengers in the vehicle.

[0081] Fig. 7 shows the area F8 marked in Fig. 6 to illustrate the principle of retroreflection. Instead of a flat reflective surface for the retroreflector 23, a structure of reflective surfaces 1621, 1622 arranged at right angles to each other is provided. They therefore act as a retroreflector. Light L231 incident along the line of sight 231 is always reflected in such a way that the reflected light L231' is aligned parallel to it. To ensure that the light reflected by the retroreflector 23 reaches the viewer, the reflected light L231' can be deflected in the viewer's direction. For this purpose, for example, a scattering coating (not shown here) is provided on the surfaces 1621, 1622. A scattering coating can also be provided on another surface located between the retroreflector 23 and the viewer.

[0082] Fig. 8 shows the area F8 marked in Fig. 6, similar to the description in the previous figure, to illustrate retroreflection with angular deviation. The reflective surfaces 1621, 1622, arranged at an angle to each other, have an angle that deviates from 90°. Two reflective surfaces 1621, 1622 are shown here as an example, arranged at an angle slightly greater than 90° to each other. They therefore act as a retroreflector with angular deviation. Light L231 incident along the line of sight 231 is reflected in such a way that the reflected light L232' reaches the viewer. For this purpose, the orientation of the contact lines of the surfaces 1621, 1622, as well as the angle exceeding 90°, is appropriately adjusted to the position of the projector and the viewer. 202405074

[0083] 17

[0084] The retroreflector 23, 4123 is advantageously designed as a planar element with a microstructure, wherein many small structures corresponding to the retroreflectors shown in Fig. 8 are arranged side by side in the plane of the planar element. This is useful both in the variant in which the retroreflector does not scatter and in the variant in which the retroreflector is a direction-changing reflecting scattering screen.

[0085] The retroreflector according to the invention is a modified retroreflector of a type commonly known. In a conventionally known retroreflector, the light returns in the same direction from which it came. This is impractical when the projector is positioned close to the base of the disc. In such a case, the invention provides for a significant change in the direction of the light. The reflector screen is optimized so that light is directed as precisely as possible only in the desired output direction. Depending on the positioning of the reflector screen and the projector, this requires a relatively strong and locally varying deflection.

[0086] Fig. 9, similar to the lower part of Fig. 6, shows a projection system according to the invention in a sectional view. The projector 22', mounted above the head of a vehicle occupant, is visible. Light rays LBR' from this projector radiate towards the base of the disc 411. Before reaching the base of the disc 411, they encounter a retroreflector 4123, which changes the direction of the light. This retroreflector is provided in place of the reflector surface 412 shown in Fig. 6. In this embodiment, the reflections from the reflector surface 412 are directed towards the retroreflector 23, from there back to the reflector surface 412, and from there away from the viewer. In this illustration, there is a direct reflection of the light incident on the retroreflector 4123 towards the viewer. It can be seen that the light ray LBSW reflected by the retroreflector 4123, as the reflected ray in the plane AA shown in this illustration, has a different direction of light than the incident ray. 202405074

[0087] 18

[0088] Fig. 10 shows the embodiment of Fig. 9 in a top view. It can be seen that the dashed line AA corresponds to the plane AA of Fig. 9. An example of this is a light beam LBR' as the incident beam for the retroreflector 4123. In the plane shown in this figure, which is perpendicular to plane AA, the retroreflector 4123 acts like a conventional retroreflector, in which the directions of the incident and reflected beams are parallel, and the reflected beam is reflected back into the incident beam. The reflected beam reaches the vehicle occupant, the observer, as light beam LBSW.

[0089] 202405074

[0090] Reference symbol list

[0091] 1 Image generation system 100 Vehicle 101 Dashboard 11 Display element, image transmitter 14R, 14G, light source 14B 140 Beam generator 151 Lens 155 Illumination optics 156 Projection optics

[0092] 161 Mirror 162 Dichroic 1621 ,1622 Reflective inclined surface 163 Dichroic

[0093] 172 Diffuser

[0094] 2 Imaging Unit

[0095] 21,21' projection surface

[0096] 22.22' Laser Beam Scanner

[0097] 23 Retroreflector

[0098] 231, 232 Line of sight

[0099] 3 Optical unit

[0100] 31 mirrors

[0101] 32 mirrors

[0102] 321 Storage

[0103] 33 Transparent Cover

[0104] 34 Glare protection

[0105] 4 mirror unit

[0106] 41 Windscreen

[0107] 411 disc root

[0108] 412 Reflector area 202405074

[0109] 20

[0110] 4123 Retroreflector

[0111] 52 computer units

[0112] 61 Eye of a beholder

[0113] 62 Eyebox

[0114] 64 Source of interference

[0115] 73 Controllable mirror unit

[0116] AA level

[0117] F8 area

[0118] LB light beam

[0119] LBM Modulated Light Beam

[0120] LBR,LBR' Reflected light beam

[0121] LBSW,LBSW' light beam

[0122] L231 ,L231' light

[0123] L232' Light

[0124] SB1 beam bundle

[0125] SB2 beam bundle

[0126] SL Sunlight

[0127] VB Virtual Image

Claims

202405074 21 Patent claims 1. Projection system, featuring - a projector (22.22'); and - a retroreflector (23), wherein the projector (22,22') illuminates the retroreflector (23,4123) and the retroreflector (23,4123) reflects into a certain solid angle range.

2. Projection system according to claim 1, wherein the retroreflector (23,4123) which reflects into a certain solid angle range is a direction-changing reflecting scatter screen.

3. Projection system according to claim 1 or 2, wherein the retroreflector (23,4123) changes the direction of the light.

4. Projection system according to claim 3, wherein the retroreflector (23,4123) changes the direction of light locally differently.

5. Vehicle with a projection system according to one of claims 1-4, wherein the retroreflector (23,4123) is arranged below a disc root (411) of the vehicle.

6. Vehicle according to claim 5, wherein a reflector surface (412) is arranged in front of the disc root (411).

7. Vehicle according to one of claims 4-6, wherein the projector (22) is arranged at the upper edge of the disc (41) furthest from the disc root.

8. Vehicle according to one of claims 4-6, wherein the projector (22) is arranged near the disk root (411). 202405074 22 9. Vehicle according to one of claims 4-8, wherein several projectors (22) are arranged in the vehicle which illuminate the retroreflector (23,4123).

10. Projection system or vehicle according to any of the preceding claims, wherein the projector (22,22') is a laser beam scanner.

Images