Optical system and a method for operating an HUD

Abstract

Described is an optical system and method for operating an HUD. The optical system includes an imaging system that generates optical radiation based on image information, a display system that projects the optical radiation, a deflection device that deflects the projected optical radiation, and at least one optically transparent pane-shaped element that at least partially reflects the deflected optical radiation. The deflection device guides the projected optical radiation onto the pane-shaped element, the optical radiation hitting the pane-shaped element at an angle. The imaging system, the display system, the deflection device and the pane-shaped element are arranged to generate a virtual image of optical radiation containing the image information. The optical system includes first and second edge points of the pane-shaped element. The first edge point has a minimal distance (d.sub.min.sup.(1)) to the deflection device and the second edge point has a minimal distance (d.sub.min.sup.(2)) to the imaging system.

Claims

1. An optical system, comprising: an imaging system designed to impress image information onto an optical radiation; a display system designed to project the optical radiation; a deflection device designed to deflect the projected optical radiation, wherein the deflection device allows an active control of the deflection direction in at least two degrees of freedom, wherein the deflection device comprises a mirror that is supported in such a manner that it can be rotated and/or its position can be changed; at least one optically transparent pane-shaped element designed to at least partially reflect the deflected optical radiation, wherein the deflection device guides the projected optical radiation onto the pane-shaped element in such a manner that the optical radiation hits the pane-shaped element at an angle, wherein the imaging system, the display system, the deflection device and the pane-shaped element are arranged in relation to each other such that a virtual image of optical radiation containing the image information is generated, wherein a first edge point of the pane-shaped element differs from a second edge point of the pane-shaped element, and wherein the first edge point comprises a minimal distance (d.sub.min.sup.(1)) to the deflection device and the second edge point comprises a minimal distance (d.sub.min.sup.(2)) to the imaging system, wherein a distance between the first edge point and the second edge point along a circumference (U) of the pane-shaped element is at least 10% of the circumference (U) of the pane-shaped element; an eye tracking module, designed to determine a Line-of-Sight of an observer onto the pane-shaped element; and a control unit, adapted to vary a position of the virtual image in a region of the pane-shaped element by means of the deflection device such that the virtual image is tracked to the Line-of-Sight of the observer, wherein for every Line-of-Sight of an observer onto the pane-shaped element the size of the virtual image directly created by the imaging system is smaller than 90% of a Field-of-View of the optical system.

2. The optical system according to claim 1, wherein the control unit is designed to adjust an eyebox and/or image information shown to a direction of view of the observer onto the pane-shaped element.

3. The optical system according to claim 1, wherein the imaging system is a Pico projector.

4. The optical system according to claim 2, wherein the eyebox has a diameter of between 5 mm and 30 mm.

5. The optical system according to claim 1, wherein in order to control optical properties of the display system, a pivoting lens system is tilted and/or at least an air gap within the display system is adapted.

6. The optical system according to claim 1, wherein the optical system comprises a glare protection for suppressing sun reflections.

7. A method for operating a Head-Up Display, comprising the following method steps: providing an optical system according to claim 1; and creating a virtual optical display of image information shown by the imaging system in an area of the pane-shaped element.

8. The method according to claim 7, further comprising: determining an eye position of an observer onto the pane-shaped element; and changing the position of the virtual image in the region of the pane-shaped element and/or adjusting the image information shown to the direction of view of an observer onto the pane-shaped element.

9. The method according to claim 7, wherein a control of optical properties of the display system is conducted by tilting a pivoting lens system and/or by adjusting at least one air gap within the display system.

10. The method according to claim 8, wherein a control of optical properties of the display system is conducted by tilting a pivoting lens system and/or by adjusting at least one air gap within the display system.

11. The optical system according to claim 1, wherein the optical system comprises a computational evaluation of previously ascertained eye position data or an additional system for determining a length of the Line-of-Sight, wherein the control unit adapts the size of the eyebox to the length of the Line-of-Sight of the observer.

12. The method according to claim 9, further comprising: determining the length of the Line-of-Sight of the observer; and adjusting the size of the eyebox of the imaging system to the length of the Line-of-Sight.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be explained below in exemplary embodiments with reference to the associated drawings, in which:

(2) FIG. 1 shows a schematic view of a conventional optical system for operating an HUD in motor vehicles;

(3) FIG. 2 shows a schematic view of a first embodiment of an optical system according to the invention for operating an HUD in motor vehicles;

(4) FIG. 3 shows a schematic view of a second embodiment of an optical system according to the invention for operating an HUD in motor vehicles;

(5) FIG. 4 shows a schematic view of a third embodiment of an optical system according to the invention for operating an HUD in motor vehicles;

(6) FIG. 5 shows a schematic view of a top view of an embodiment of an optical system according to the invention for operating an HUD in motor vehicles;

(7) FIG. 6 shows a schematic view of a preferred embodiment of a pane-shaped element;

(8) FIGS. 7a and 7b show beam paths for a specific embodiment of an optical system according to the invention in the side view (FIG. 7a) and in the top view (FIG. 7b) for a nominal position; and

(9) FIGS. 8a and 8b show beam paths for a specific embodiment of an optical system according to the invention in the side view (8a) and in the top view (FIG. 8b) for the extreme positions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) FIG. 1 shows a schematic view of a conventional system for operating an HUD in motor vehicles. The creation of a virtual image 60 is here enabled by a reflection of an optical radiation, containing the image information to be displayed, on the windscreen 55 of the motor vehicle as a pane-shaped element 50. The reflection occurs in the direction of an observer 30, e.g. a vehicle driver. Typically, such an optical system comprises at least one imaging system 10, a display system 20 and a deflection device 40. The display system 20 usually comprises a lens system as a lens. Further, a means for beam guidance 22 of the display system 20 can be comprised. Here, this can in particular be a mirror, which guides optical radiation of the deflection device 40 that enters the mirror. The means for beam guidance 22 here serve primarily to create the most compact folding possible of the beam path. The deflection device 40 can also be a mirror. The deflection device 40 has the task of guiding the entering optical radiation to the pane-shaped element 50 in such a manner that the generation of a virtual display for a plurality of observer positions within a certain HMB is enabled. The mirror of the deflection device 40 is also usually aspherical or formed as a free-formed surface and can be changed in its situation or position, so that an adjustment of the image generation to the size or sitting position of an observer 30 is enabled. The latter can then for example select a favourable setting for the position of the virtual image 60 before starting to drive.

(11) In the prior art, imaging system 10, display system 20 and deflection device 40 are usually arranged and housed as a compact unit within the dashboard of the vehicle, preferably in the area of the steering column along a shared main plane (drawing plane). With a distance observation according to the invention between the pane-shaped element 50 and the deflection device 40 or the pane-shaped element 50 and the imaging system 10, the distance vectors which here result from the first minimal distance d.sub.min.sup.(1) and the second minimal distance d.sub.min.sup.(2) also lie within this plane and thus feature a shared intersection point with the edge of the pane-shaped element 50. Thus, a first edge point 51 emerges, which coincides with the second edge point 52. Such an optical system therefore requires the corresponding construction space below the windscreen 55.

(12) FIG. 2 shows a schematic view of a first embodiment of an optical system according to the invention for operating an HUD in motor vehicles. The construction parts shown in FIG. 1 with their reference numerals are found accordingly. Unlike the optical system shown in FIG. 1, however, the situation of the imaging system 10 and the display system 20 differs in relation to the deflection device 40 and to the pane-shaped element 50. The imaging system 10, display system 20 and deflection device 40 are also located in the drawing below a common main plane (drawing plane). Due to the arrangement of the imaging system 10 and the display system 20 in the upper area of the pane-shaped element 50 and of the deflection device 40 on the lower area of the pane-shaped element 50, with a distance observation according to the invention with regard to the pane-shaped element 50, a first minimal distance d.sub.min.sup.(1) and a second minimal distance d.sub.min.sup.(2) to the edge of the pane-shaped element 50 result. Thus, a first edge point 51 of the pane-shaped element 50 results, which differs from a second edge point 52 of the pane-shaped element 50, wherein the first edge point 51 features a minimal distance d.sub.min.sup.(1) to the deflection device 40 and the second edge point 52 features a minimal distance d.sub.min.sup.(2) to the imaging system 10. As a result, preferably, the position of the imaging system 10 and display facility 20 can be spatially decoupled from the position of the deflection device 40. Accordingly, below the pane-shaped element 50, i.e. in motor vehicles, in the area below the windscreen 55, preferably in the area of the steering column, considerably less construction space is required than would be the case with a conventional optical system. Otherwise, the imaging system 10, the display system 20 and the deflection device 40 feature no shared main plane. All these components can be positioned freely in the space. In particular, beam paths folded three-dimensionally in the space are preferred, for example in order in motor vehicles to enable the optical radiation of an imaging system 10 located on the driver's side B-pillar through the use of a corresponding means for beam guidance 22 for generating a virtual image 60 in a position located centrally on the windscreen 55.

(13) FIG. 3 shows a schematic view of a second embodiment of an optical system according to the invention for operating an HUD in motor vehicles. The embodiment shown largely corresponds to the embodiment shown in FIG. 2, and the reference numerals apply accordingly. Unlike in FIG. 2, with this exemplary embodiment, however, the means for beam guidance 22 are lacking in the display system 22. In particular, this exemplary embodiment comprises an embodiment of an optical system according to the invention in which a direct viewing axis between the imaging system 10 and the deflection device 40 exists. An additional means for beam guidance 22 can be omitted as a result. In motor vehicles, for example, the imaging system 10 and the display system 20 can be housed within the rear mirror carrier, so that due to a direct viewing axis to a deflection device 40 located in the dashboard, additional construction space can be saved.

(14) FIG. 4 shows a schematic view of a third embodiment of an optical system according to the invention for operating an HUD in motor vehicles. The embodiment shown largely corresponds to the embodiment shown in FIG. 3, and the same reference numerals apply. With this embodiment, however, the virtual image 60 is not generated by a reflection of the radiation entering on a windscreen 55. To a far greater extent, an additional pane-shaped element 50 is located in front of the windscreen 55, which reflects the radiation entering from the direction of the deflection device 40 in the direction of an observer 30. The pane-shaped element 50 can here consist of a reflection pane made of acrylic glass, for example, or another transparent plastic.

(15) FIG. 5 shows a schematic view of the top view of an embodiment of an optical system according to the invention for operating an HUD in motor vehicles. The view shown largely corresponds to the embodiment shown in FIG. 3, with a windscreen 55 as a pane-shaped element 50, the same reference numerals apply. The view shows a preferred beam guidance of the optical system according to the invention in motor vehicles. The imaging system 10 and the display system 20 are arranged in the lower area of the windscreen 55. The deflection device 40 is arranged in the lower area of the windscreen 55. Here, the first minimal distance d.sub.min.sup.(1) between the pane-shaped element 50 and the deflection device 40 marks a first edge point 51 and the second minimal distance d.sub.min.sup.(2) between the pane-shaped min element 50 and the imaging system 10 marks a second edge point 52. Both edge points differ from each other due to their location, wherein the distance between the first edge point 51 and the second edge point 52 along the circumference U of the pane-shaped element 50 is according to the invention at least 10% of the circumference U of the pane-shaped element 50.

(16) FIG. 6 shows a schematic view of a preferred embodiment of a pane-shaped element 50. In particular, this can be the windscreen 55 of a motor vehicle, a water vehicle, an airborne vehicle or a space vehicle. Otherwise, however, all other types of window panes, viewing windows, windscreens or similar are also comprised. According to the invention, a pane-shaped element 50 is characterised at least by the fact that on this element, a surrounding edge with a corresponding circumference U can be defined. Further, in the minimal outer dimension of the pane-shaped element, a height H and a breadth B preferably occur. The height H and breadth B here preferably deviate by at least one scale of size upwards from the spatial depth T also occurring in the outer dimension of the pane-shaped element 50. The thickness here preferably arises from the middle thickness of the edge. With windscreens 55 of motor vehicles, this value corresponds to a uniform pane thickness.

(17) Below, a specific exemplary embodiment is given for an HUD in motor vehicles. In FIGS. 7a and 7b, the beam paths for an embodiment of an optical system according to the invention is shown in the side view (FIG. 7a) and in the top view (FIG. 7b) for a nominal position of the driver or an eye. In FIGS. 8a and 8b, with this embodiment, the beam paths of the optical system according to the invention are shown in the side view (FIG. 8a) and in the top view (FIG. 8b) for the extreme positions of the driver or an eye. The extreme positions are determined by the size of the HMB, wherein the nominal position is preferably located in the geometric centre of the HMB.

(18) The virtual image is mirrored only in one eye. The eye is preferably freely selectable in an application. When the beam path was simulated, it was assumed that the distance between the eyebox and the virtual image was 5 m.

(19) Field of view: 157.5

(20) Diameter of the eyebox: 22.3 mm

(21) Head Motion Box (BHD): 200160160 mm.sup.3

(22) Resolution: 1152676 px.sup.2

(23) Mirror size of the deflection device: 440260 mm.sup.2

(24) Mirror size of the display system: 14487 mm.sup.2

(25) Number of lenses in the lens system: 7

(26) Size of the windscreen: 1300650 mm.sup.2

(27) Angle of the windscreen to the horizon: 30

(28) Distance, lower windscreen edgeroad approx. 95 mm

(29) Distance, windscreeneyebox (nominal position): 600 mm

(30) Distance, eyebox (nominal position)road: 1100 mm

(31) The lens system comprises an aspherical surface, a free-form surface and a cementing element. Two mirrors are used. One mirror serves as a deflection device, while the second is a part of the display system. Both mirrors are free-form surfaces. Due to a typical curvature of windscreens in motor vehicles, at least one free-form surface is required here as compensation. Both mirrors are tilted around the two lateral axes which stand vertical in relation to each other. With this embodiment, the rotation points are located on the mirror surfaces. Preferably, however, the rotating point of the mirror in the deflection facility can also be arranged below or above the mirror, so that the mirror can additionally also be laterally moved for tilting. As a result, the construction space in the dashboard remains largely unchanged, but the required mirror surface is reduced in size and the mirror can thus be produced at a lower cost and in a simpler manner.

LIST OF REFERENCE NUMERALS

(32) 10 Imaging system 20 Display system 22 Means for beam guidance 30 Observer 40 Deflection device 50 Pane-shaped element 51 First edge point 52 Second edge point 55 Windscreen 60 Virtual image d.sub.min.sup.(1) First minimal distance (pane-shaped elementdeflection device) d.sub.min.sup.(1) Second minimal distance (pane-shaped elementimaging system) B Breadth H Height U Circumference