Device for generating a virtual image comprising a regulation mechanism for the antireflection slats

Abstract

The invention relates to a device for generating a virtual image (VB), comprising: - a display element (11) for generating an image; - an optical waveguide (5, 510, 520) for expanding an exit pupil; and - an anti-glare element (81) arranged downstream of the optical waveguide (5) in the beam path, wherein - the anti-glare element (81) is a light barrier (83) having a plurality of slats (82), the set angle (a) of which is defined by at least one integral spring (7, 7', 7a).

Description

TECHNICAL FIELD

[0001] The present invention relates to an adjustment mechanism for an anti-reflection slat of a display device having an image generating unit with display elements for displaying an image and an optical unit for projecting the image onto a projection surface. BACKGROUND

[0002] Such a display device can for example be used for a head-up display of a means of transport. A head-up display, also called HUD, is intended to mean a display system in which the viewer can keep his viewing direction, since the content to be presented is superimposed into his field of view. While such a system was initially mainly used in the field of aerospace due to its complexity and costs, it is now also used in the automotive field for mass production.

[0003] A head-up display is generally composed of an image generator, an optical unit and a mirror unit. The image generator produces an image. The optical unit directs the image onto the mirror unit. The image generator is also often called image generating unit or PGU (Picture Generating Unit). The mirror unit is a partially mirror-reflecting light-transmitting pane. Thus, the viewer sees the content presented by the image generator as a virtual image and at the same time the real world behind the pane. In the automotive field, the windshield is often used as mirror unit and the curved shape of the windshield has to be taken into account when presenting. Due to the interaction of the optical unit and the mirror unit, the virtual image is a magnified presentation of the image produced by the image generator.

[0004] The viewer can only see the virtual image from the position of the so-called eye-box. The area corresponding to the height and width of the theoretical viewing window is called eye-box. As long as one of the viewer's eyes is within the eye-box, all elements of the virtual image are visible to that eye. On the other hand, if the eye is outside the eye-box, the virtual image is only partially or not at all visible to the viewer. The larger the eye-box, the less the viewer is limited in choosing his seating position.

[0005] The size of the eye-box of a conventional head-up display is limited by the size of the optical unit. One method for enlarging the eye-box is to input the light from the image generating unit into an optical waveguide. The light input into the optical waveguide undergoes total reflection at the interfaces of the optical waveguide and is thus guided within the optical waveguide. In addition, a portion of the light is output at multiple positions along the propagation direction. Due to the optical waveguide, the exit pupil is enlarged in this way. Here, the effective exit pupil is composed of the image of the aperture of the image generating system.

[0006] In this context, US 2016 / 0124223 A1 describes a virtual image display device. The display device comprises a light waveguide that repeatedly subjects light emitted from an image generation unit and incident through a first light-incident surface to internal reflection so as to travel in a first direction away from the first light-incident surface. The light waveguide also has the effect that a portion of the light guided in the light waveguide is outcoupled through a region of a first light- exit surface extending in the first direction. The display device further comprises a first light-incident diffraction grating that diffracts the incident light to cause the diffracted light to enter the light waveguide and a first light-exit diffraction grating that diffracts light incident from the light waveguide. US 2012 / 0224062 A1 also relates to a virtual image display device with a light waveguide.

[0007] In the design of such devices known today, in which the light waveguide consists of a glass plate, the diffraction grating or hologram is arranged within the glass plate, problems arise if light is incident from the outside. Stray light can enter the eye of the user due to reflections of light incident from the outside. The contrast of the virtual image perceived by the user is further reduced.

[0008] Therefore, in conventional devices, the possible reflecting components are tilted and combined with a glare catcher, so that the reflection does not reach the area where the eyes of the driver are expected to be. Alternatively, anti-reflective coatings are employed and structure roughness is used to reduce the intensity of the reflection.

[0009] The tilting of the components significantly occupies the installation space, which is limited in a car. Further, the performance of the components generally decreases with the tilted installation. The coatings and rough structures reduce the achievable intensity, but the reflection remains generally clearly visible and significantly reduces the contrast. SUMMARY

[0010] It is an object of the present invention to provide an improved device for generating a virtual image, with which the influence of stray light is reduced.

[0011] This object is achieved by a device having the features of claim 1. Preferred configurations of the invention are the subject of the dependent claims.

[0012] The device for generating a virtual image according to the invention has a display element for generating an image, an optical waveguide for enlarging an exit pupil, and an anti-glare element arranged downstream of the optical waveguide in the beam path and being a light shutter having a plurality of slats, the set angle of which is defined by means of at least one integral spring. The integral spring has a resilient mechanism. This has the advantage of allowing an exact setting which is not influenced by hysteresis and play. In the solution according to the invention, the set angle is independent of temperature, since the thermal expansion of the integral spring can change its overall length, but not its basic shape. Even when the spring is thermally expanded, the slats, which are oriented with a defined angle of inclination, retain this angle. The slats are prescribed against a defined angle of inclination and are movably suspended at their respective end. As an alternative to this solution, at least two settable springs are provided, against which the slats are fastened in their end region at a defined angle of inclination.

[0013] According to the invention, the integral spring has a first plane and a second plane, which are connected to one another by means of a transition slope. This has the advantage that the transition slope represents a planar region of a constant slope and thus a large area against which the slats are prescribed. This enables an even more exact setting of the angle. According to the invention, the spring is punched from a thin two-dimensional material, which, after punching, is folded to form a three-dimensional component by moving the first plane and the second plane, which initially lie in the same starting plane, perpendicular to the starting plane in such a way that the first plane and the second plane are thus spaced apart from one another and connected to one another by means of the transition slope.

[0014] According to the invention, at least two parallel rows of transition slopes are provided, which are arranged offset from one another. This advantageously enables a dense arrangement of the slats. This better shields against unwanted light.

[0015] The transition slope advantageously has perforations and / or grooves and / or peripheral notches in its transition region to the at least one of the first plane and the second plane. In this way, an increased effective resilience is achieved in this transition region. This simplifies the shaping from a two-dimensional shape to a three-dimensional shape when manufacturing the spring.

[0016] According to the invention, the transition region of the integral spring has different lengths. As a result, different set angles are advantageously achieved for different slats. This enables the formation of a set angle gradient which is desired in a particular configuration of the device.

[0017] Advantageously, a plurality of springs are nested in one another or arranged side by side. This enables a denser arrangement of the slats without having to configure the springs too thinly. Thus, the repetition per unit length is advantageously multiplied.

[0018] Further features of the present application will become apparent from the following description and appended claims, considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A head-up display for a motor vehicle according to the prior art is schematically shown;

[0020] Figure 2 A light waveguide with two-dimensional magnification is shown;

[0021] Figure 3 A head-up display with a light waveguide is schematically shown;

[0022] Figure 4 A head-up display with a light waveguide in a motor vehicle is schematically shown;

[0023] Figure 5 A head-up display with a light waveguide and an anti-reflective element as an anti-glare element is schematically shown;

[0024] Figure 6 An alternative light waveguide with two-dimensional magnification is shown;

[0025] Figure 7 A device for generating a virtual image according to the present application is schematically shown;

[0026] Figure 8 A shutter and a detail enlargement thereof are shown;

[0027] Figure 9 A spring according to the present application is shown;

[0028] Figure 10 A spring according to the present application is shown;

[0029] Figure 11 A spring according to the present application is shown in a side view;

[0030] Figure 12 A spring according to the present application is shown in a side view;

[0031] Figure 13 A spring with and without applied force is shown in a side view;

[0032] Figure 14 An anti-glare element with and without applied force is shown in a top view;

[0033] Figure 15 An anti-glare element is shown in a schematic space view;

[0034] Figure 16 A schematic space illustration of a spring according to the present application is shown;

[0035] Figure 17 A spring with a set angle gradient is shown in a side view. DETAILED DESCRIPTION

[0036] For a better understanding of the principles of the application, embodiments of the present application will be explained in more detail below with reference to the attached drawings. In the drawings, the same reference notations are used to designate identical elements or functionally identical elements and are not necessarily described again for each figure. It should be appreciated that the application is not limited to the embodiments shown and that the described features can also be combined or modified without departing from the scope of the application as defined in the appended claims.

[0037] First, the basic concept of a head-up display with an optical waveguide will be explained with reference to Figures 1 to 4

[0038] Figure 1 A schematic of a head-up display for a motor vehicle according to the prior art is shown. The head-up display comprises an image generator 1, an optical unit 2 and a mirror unit 3. A bundle of light rays SB1 is emitted from a display element 11 and reflected by a folding mirror 21 onto a curved mirror 22 which reflects the bundle of light rays in the direction of the mirror unit 3. The mirror unit 3 is here presented as a windshield 31 of the motor vehicle. From there, the bundle of light rays SB2 travels in the direction of the viewer’s eye 61.

[0039] The viewer sees a virtual image VB which is located outside the motor vehicle, above the engine hood or even in front of the motor vehicle. Due to the interaction of the optical unit 2 and the mirror unit 3, the virtual image VB is a magnified presentation of the image displayed by the display element 11. Here, a speed limit, the current vehicle speed, and navigation instructions are symbolically presented. As long as the eye 61 is within the eye box 62 indicated by the rectangle, all elements of the virtual image are visible to the eye 61. If the eye 61 is outside the eye box 62, the virtual image VB is only partially visible or not at all to the viewer. The larger the eye box 62, the less the viewer is restricted in choosing his seating position.

[0040] ​The curvature of the curved mirror 22 serves on the one hand to adjust the beam path and thus to ensure a large image and a large eye box 62. On the other hand, the curvature of the curved mirror compensates for the curvature of the windshield 31, as a result of which the virtual image VB corresponds to a magnified reproduction of the image presented by the display element 11. The curved mirror 22 is mounted rotatably by means of a bearing 221. The rotation of the curved mirror 22 which is thus allowed makes it possible to displace the eye box 62 and thus to adapt the position of the eye box 62 to the position of the eye 61. The folding mirror 21 serves to ensure that the path of the light bundle SBl between the display element 11 and the curved mirror 22 is long, but at the same time ensures that the optical unit 2 is nevertheless compact. The optical unit 2 is separated from the environment by means of a transparent cover 23. The optical elements of the optical unit 2 are thus protected, for example, from dust located in the interior of the vehicle. Further, an optical film 24 or a coating for preventing incident sunlight SL from reaching the display element 11 via the mirrors 21, 22 is located on the cover 23. Otherwise, the display element 11 can be temporarily or permanently damaged by the heat generated thereby. In order to prevent this, for example, the infrared component of the sunlight SL is filtered out by means of the optical film 24 or is at least partially reflected by the optical film. A glare protection 25 serves to shield light incident from the front, so that light incident from the front is not reflected by the cover 23 in the direction of the windshield 31, which would cause the viewer to be dazzled. In addition to the sunlight SL, light from further stray light sources 64 can also reach the display element 11.

[0041] Figure 2 A schematic perspective view of a light waveguide 5 with two-dimensional magnification is shown. The lower left region shows an input hologram 53 by means of which light LI from an image generation unit (not shown) is input into the light waveguide 5. According to the arrows L2, the light propagates in the light waveguide to the upper right in the figure. In this region of the light waveguide 5, there is a folding hologram 51 which functions like a number of partially transmissive mirrors arranged one after the other and which produces a widening of the light bundle in the Y direction and a propagation in the X direction. This is indicated by the three arrows L3. In the part of the light waveguide 5 which extends to the right in the figure, there is an output hologram 52 which likewise functions like a number of partially transmissive mirrors arranged one after the other and which outputs the light waveguide 5 with a widening in the Z direction upwards, indicated by the arrow L4. In this case, a widening takes place in the X direction, so that the originally incident light bundle LI leaves the light waveguide 5 as a light bundle L4 which is magnified in two dimensions.

[0042] Figure 6 A schematic view of a light waveguide with two-dimensional magnification is shown, which is Figure 2An alternative. Here, the output hologram 52 is configured to output light not normal to the surface of the optical waveguide 5 but in an angled way with respect to the Z-direction, as indicated by the arrow L4. In this way, the optical waveguide 5 can be arranged according to the available installation space without having to take into account the perpendicular exit of the amplified light beam in two dimensions.

[0043] Figure 3 A perspective view is shown of a head-up display with three optical waveguides 5R, 5G, 5B, which are arranged one above the other and each of which represents a primary color red, green and blue. Together, these optical waveguides form the optical waveguide 5. The holograms 51, 52, 53 present in the optical waveguide 5 are wavelength-dependent, so that one optical waveguide 5R, 5G, 5B is used for one of the primary colors respectively. The image generator 1 and the optical unit 2 are shown above the optical waveguide 5. The optical unit 2 has a mirror 20 by means of which the light produced by the image generator 1 and shaped by the optical unit 2 is deflected in the direction of the respective input hologram 53. The image generator 1 has three light sources 14R, 14G, 14B for the three primary colors. It can be seen that the entire unit shown has a small total height compared to its light-emitting surface.

[0044] Figure 4 A head-up display in a motor vehicle is shown, which is similar to Figure 1 the one shown in Fig. 1, but here in a perspective view and with an optical waveguide 5. An image generator 1 is shown which is indicated schematically, which generates a bundle of parallel light rays SB1 which is input into the optical waveguide 5 by means of a mirror plane 523. For the sake of simplicity, the optical unit is not shown. Each of a plurality of mirror planes 522 reflects a portion of the light incident thereon in the direction of the windshield 31 (mirror unit 3). From here, the light is reflected in the direction of the eye 61. The viewer sees a virtual image VB above the hood or even at a greater distance in front of the motor vehicle.

[0045] Figure 5 A head-up display is shown schematically with an optical waveguide and an anti- glare element as an anti-glare element.

[0046] Figure 7 A device according to the invention is shown, in which the optical waveguide 5 is arranged in a plane parallel to the plane of the windshield 31. Figure 6The optical waveguide 5 is used in a corresponding manner. An image generator 1 with a display element 11 and the optical waveguide 5 are shown, from which the optical waveguide emits light L4 at an angle a with respect to the normal N of the light exit surface 54 of the optical waveguide 5, the angle a being greater than 0°. The exit light L4 is incident on the light entry surface 85 of a light shutter 83, the slats 82 of which are parallel to the exit light L4, so that the exit light can pass unhindered through the intermediate spaces 84 between the slats 82. The light L6 exiting from the light shutter 83 is incident on the windshield 31 at an angle β and is reflected by the windshield and enters the eye 61 of the vehicle occupant, here the driver, as light L8. The driver thus sees a virtual image VB. In this exemplary embodiment, the light shutter 83 forms a cover for the optical unit and, during operation, must be removed from any separate cover element that can be present. The light shutter 83 can thus also come into direct contact with objects or persons located in the interior of the vehicle. Damage to the light shutter 83 is thus not excluded. The light shutter 83 is therefore preferably arranged detachably, so that it can be removed without excessive effort, if necessary, and replaced with a new or repaired light shutter 83.

[0047] Figure 8 The light shutter 83 and a detail enlargement 830 are shown. The slats 82 are shown, which pass light L5 emitted from the optical waveguide 5 and running substantially parallel to the slats 82. Stray light SL running non-parallel to the slats 82 is blocked by the slats 82. The slats 82 have a spacing AL from one another and are inclined at an angle a with respect to the normal NJ of the light entry surface 85 of the light shutter 83. The slats have a height HL and a thickness DL, wherein the height HL is a multiple of the thickness DL. The angle a corresponds to the angle of the light emitted from the optical waveguide 5 when the light exit surface 54 of the optical waveguide 5 and the light entry surface 85 of the light shutter 83 are arranged parallel to one another. In the case of a non-parallel arrangement, the angles are converted accordingly. The angle a depends, inter alia, on the position of the driver and his viewing angle. The spacing AL needs to be adjusted, inter alia, for different types of vehicles or different inclinations of the windshield 31. The slats 82 are preferably configured to be non-reflective, i.e. substantially black. If the slats are arranged to be tiltable, i.e. the angle a is set variable during operation, the slats can be set to different positions of the eye window or to different positions of the eye 61 within the eye window. This assumes that the light emitted from the optical waveguide 5 covers a certain angular range, so that for each set angle a, the light rays parallel to the slats reach the slats and thus pass through the slats.

[0048] Figure 9A spring 7 according to the invention is shown in a top view. Here, the spring 7 is shown in its two-dimensional shape, which it has before transforming into its three-dimensional shape during manufacturing. A first plane 71 and a second plane 72 are shown in the figure, which are still in the same plane in their two-dimensional form, and are the planes in the figure. A tab 711 extends from the first plane 71 toward the second plane 72. A tab 721 extends from the second plane 72 toward the first plane 71. A transition slope 73 connects the tab 711 to the tab 721 in each case. A through hole 731 is arranged at the transition between the tab 711 and the transition slope 73 on the first plane 71. A through hole 732 is arranged at the transition between the tab 721 and the transition slope 73 on the second plane 72. When the spring 7 transforms from its shown two-dimensional shape to its three-dimensional shape, creases are formed at the through holes 731 and 732. Then, the transition slope 73 is angled to the planes 71 and 72, forming a substantially flat surface between the perforations 731 and 732. For manufacturing the spring 7, a thin rectangular sheet of metal or a corresponding foil is preferably used, which is cut, stamped, or processed in some other suitable manner according to the cutting profile 70. In the left-hand portion of the figure, a groove 734 is shown as an example, provided to replace or be attached to the perforation 731. A peripheral cutout 735 is also shown as an alternative to the perforation 731. It goes without saying that typically only the perforation 731, the groove 734, or the peripheral cutout 735 are provided in the spring 7. However, combinations of two or three of these elements can also be a design feature of the invention.

[0049] Figure 10 A spring 7 according to the invention is shown, wherein there are transition ramps 73 and 74 offset from each other. For example... Figure 9 As shown, the transition ramp 73 is connected to a portion of the first plane 71 shown in the upper region of the figure by means of a tab 711, and to the second plane 72 shown in the middle region of the figure by means of a tab 721. Tab 712 is shown in the lower region of the figure, arranged offset relative to tab 711, and extends from the region of the first plane 71 shown in the lower region of the figure toward the second plane 72. Correspondingly offset tab 722 extends from the region of plane 71 shown in the lower region of the figure toward plane 72. A transition ramp 74 is arranged between tabs 712 and 722. Through holes 741 and 742 are correspondingly provided as previously described. The cutting profile is as per the description of the cutting profile. Figure 9 As described, when the spring 7 is folded from a two-dimensional shape to a three-dimensional shape, the transition slopes 73 and 74 form parallel planes offset from each other. The transition slope 73 forms row 733, and the transition slope 74 forms row 734, the two rows being parallel to each other.

[0050] Figure 11The three-dimensional shape of a spring 7 according to the application is shown in a side view. Planes 71, 72 are shown which in this form are spaced apart from one another and connected to one another by means of transition bevels 73. In the embodiment shown, the transition bevels 73 are arranged obliquely and parallel to one another.

[0051] Figure 12 Two springs 7, 7a according to the application are shown in a side view. The springs 7, 7a are offset from one another such that their respective springs 73, 73a are arranged alternately with one another. By means of these springs 7, 7a inserted into one another, for example, a series of more densely packed slats 82 is achieved, thus improving the shading.

[0052] Figure 13 A spring 7 is shown in a side view, the upper drawing without force exerted on the planes 71, 72 and the lower drawing with force exerted on the planes 71, 72. It can be seen that the transition bevels 73 in the upper part of the drawing, i.e. in their original state, have a set angle a which is different from that in the lower part of the drawing, in which the set angle a' is smaller. This is achieved by exerting a force F on one of the two planes 71, 72, the other plane being mechanically fixed, or by forces acting on both planes 71, 72 but exerted in opposite directions. The force F can be introduced parallel, perpendicular or at an angle to the planes 71, 72.

[0053] Figure 14 A glare protection element 81 is shown in a top view, in the lower part of the drawing force is exerted and in the upper part of the drawing no force is exerted. The glare protection element 81 has springs 7 on the left and springs 7' on the right. As described above, these springs have first planes 71, 71' and second planes 72, 72'. Slats 82 are clamped between the springs 7, 7'. In the embodiment shown, the slats 82 are fastened at their ends to the transition bevels 73, which are therefore not visible in the drawing. It can be seen from the upper area of the drawing that the planes 71, 71' and the planes 72, 72' are not moved relative to one another. From the lower area of the drawing, a force F acts on the planes 72, 72', the result of which is that these planes are moved relative to the first planes 71, 71'. The transition bevels 73 change their angle and thus the slats 82.

[0054] Figure 15 A glare protection element 81 is shown in a schematic perspective view. Two springs 7, 7' and their transition bevels 73, which are only schematically represented by lines, can be seen, to which the slats 82 are fastened. The set angle a is also shown.

[0055] Figure 16A schematic perspective view is shown which shows the spring 7 according to the application in its three-dimensional form. Spatially separate planes 71, 72 are shown. The first plane 71 is located above the second plane 72. Transition ramps 73 extend obliquely from top left to bottom right. These transition ramps are connected at the top to tabs 711 and at their lower end to tabs 721. In the transition region between the tabs 711, 721 and the transition region 73 there are perforations 731. If the upper plane 71 is moved to the left as a result of an applied force, the set angle a becomes smaller, the inclination of the transition ramps 73 becomes smaller and also the inclination of the corresponding slats (not shown here) which are in contact with the transition ramps. If the upper plane 71 is moved to the right as a result of an applied force, the set angle a becomes larger, the transition ramps 73 are steeper and thus also the corresponding slats. The one-piece design of the spring 7 ensures that the transition ramps 73 are always parallel to each other in this case, i.e. have the same set angle a.

[0056] Figure 17 A variant of the spring 7 according to the application is shown in a side view. This variant has transition ramps 73, 73', 73" with different set angles. This is achieved by transition ramps 73, 73', 73" of different lengths, which are shown here in exaggerated fashion for the sake of clarity. In the variant shown, a set angle gradient is achieved. Depending on the extent to which the lengths of the transition ramps 73, 73', 73" differ from each other, it is provided that the planes 71, 72 are designed to be elastic. Alternatively, it is provided that a plurality of appropriately arranged perforations 731, corresponding slots 734 or peripheral cutouts 735 are located in the transition region between the tabs 711, 721 and the transition ramps 73, which perforations, slots or peripheral cutouts ensure an increased elasticity in this transition region and then allow different set angles a, a', a".

[0057] In other words, the application relates to the following: In head-up displays, anti-reflective means are implemented using a glare catcher with a curved foil, a so-called glare trap. This design has a minimum installation depth corresponding to the foil curvature. Anti-reflective means for head-up displays using the windshield as a mirror element or projection surface are implemented by means of a slat or grid structure as a terminal component, for example see Figure 5 Since the flat glass part directly below the windshield is particularly susceptible to interference reflections, a solution for anti-reflective means is particularly required for head-up displays with a flatly installed light waveguide. This solution is preferably angle-adjustable in order to reduce the occlusion in the human eye window. A slat clamped in a frame is preferably provided for the anti-reflective means.

[0058] According to the invention, different set angles of the slats are possible for different human eye window positions. This helps to avoid undesired obscuring. The invention proposes a secure solution for allowing angle adjustment of the slats.

[0059] According to the invention, uniform angle adjustment of all slats in the component part is achieved. The angle adjustment requires only one single element. Therefore, there is no need to adjust or control each individual slat.

[0060] The invention relates to a resilient spring mechanism for an angle-adjustable anti-reflection device (anti-glare element 81). Currently, for imaging methods, such as those used for telescopes, projectors or monitors, only anti-reflection devices or visual protection methods are known which have a fixed angle (mostly perpendicular to the surface). These are, for example, visual protection films for mobile phones, anti-reflection devices for telescopes, etc. Solutions with a coarsely adjustable transmission angle are also known, for example, blinds for windows. These non-adjustable methods do not allow the system to adapt to the viewer. The viewing angle and the angle range for visual / reflective protection are the same or related to each other. For applications which aim to allow only a particularly narrow light incidence angle, but at the same time aim to allow a larger viewing angle / transmission angle range and high transmission, a very fine transmission angle adjustment and very small obscuring in the transmission area are required. The dependency of the set angle on external influences, such as temperature or humidity, should be as small as possible.

[0061] According to the invention, the slats 82 are embodied as a resilient mechanism with a three-dimensionally shaped spring 7 outside the visible area. The spring 7 is cut from a one-piece foil or sheet metal. The cutting pattern is shown in Figure 9 (single version) and Figure 10 (double version with offset). The first plane 71 and all other planes form ideal continuous areas. Each plane 71, 72 is connected to the next plane with a transition slope 73, 73', 73", 74 via a tab 711, 712, 721, 722 in the respective plane. Perforations 741, 742 can be used between the tab 711, 712, 721, 722 and the transition slope 73, 73', 73", 74 in order to increase the effective resilience in the area.

[0062] The sheet metal / foil is then bent in two or more planes. Figure 11 The result is shown in a side view. The adjustment angle depends on the cutting pattern and can thus be defined individually for each slat 82. In this way, an adjustment angle gradient can be achieved on the emission surface of a head-up display. The number and offset of the planes can be changed and increased as required. Multiple springs 7, 7a can be inserted into each other, or attached next to each other or one above the other, in order to double or multiply the number of repeating units per unit length, see Figure 12If either plane is fixed and the respective next plane is subjected to a force along this plane, or if both planes are subjected to opposing shear or pulling forces, the angle of the slat 82 changes, see Figure 13 .

[0063] The spring 7 itself is located on the product outside the optical functional area, see Figure 14 According to one embodiment variant, the slat 82 is attached to the transition ramp 73, see Figure 15 .

[0064] In a further embodiment variant, the slat 82 is only adjusted in terms of angle by contact with the transition ramp 73 and is fastened in some other way. In one embodiment variant, the transition ramp 73 can correspond approximately to the height of the slat 82 or can be designed significantly longer. If the transition ramp 73 is significantly greater than the slat 82, it is advantageous to provide a groove in the transition ramp 73 in order to simplify the positioning of the slat 82 during assembly.

[0065] The changed slat sets the angle which changes the effective coverage of the beam path, see Figure 14 Advantageously, the connecting strips in the different planes are additionally connected with a stiffener.

[0066] The solution according to the invention allows a hysteresis-free and gap-free adjustment of the set angle of the slats 82 of the "shutter". The area coverage in the transmission area is minimal, so that as much light as possible reaches the eye 62 from the desired source, while as much stray light as possible is prevented from reaching the eye 62 of the viewer. In the solution according to the invention, the set angle is in principle independent of the temperature.

[0067] The solution according to the invention can also be used in conventional head-up displays (for example based on mirrors). Here, the anti-glare element is preferably used as a terminal assembly. The solution according to the invention can also be used as an adjustable anti-reflective element inside a module. The anti-glare element is then integrated into the module. The solution according to the invention can also be used as a visual protection for displays (privacy filters) as an adaptive solution. The solution according to the invention can also be used as a visual protection for window / dome light windows (smart windows) for brightness setting. The solution according to the invention can also be used in military applications (such as avoiding reflections of telescopic sights or generally making optical units anti-reflective), or for avoiding reflections, or for glare protection for laser radar devices (lidar: light detection and ranging), video cameras and surveillance cameras. The invention can also be used in the field of aerospace, for example for glare protection in optical measuring instruments or for the precise spatial resolution of radiation sources.

Claims

1. A device for generating a virtual image (VB), the device having: - a display element (11) for generating an image; - an optical waveguide (5, 510, 520) for enlarging an exit pupil; and - an anti-glare element (81) arranged downstream of the optical waveguide (5) in the beam path, wherein - the anti-glare element (81) is a light barrier (83) having a plurality of slats (82), wherein the slats (82) rest on a transition ramp of at least one one-piece spring (7, 7', 7a) respectively.

2. The apparatus of claim 1, wherein, The one-piece spring (7, 7', 7a) has a first plane (71) and a second plane (72) which are connected to one another by means of a transition ramp.

3. The device according to claim 2, having at least two parallel rows (723, 743) of transition ramps arranged offset from one another.

4. The apparatus of claim 2, wherein, The transition ramp has a perforation (731, 732, 741, 742), a slot (734) or a peripheral cutout (735) in its transition region to at least one of the first plane (71) and the second plane (72).

5. The apparatus of claim 1 or 2, wherein, The transition ramp of the one-piece spring has different lengths.

6. The apparatus of claim 1 or 2, wherein, A plurality of springs are nested in one another or arranged side by side.

7. The apparatus of claim 1 or 2, wherein, The slats (82) have a variably set set angle (a).

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