Projection device for a motor vehicle with a specific anti-reflection structure on shaft walls, as well as a motor vehicle with a projection device

Abstract

Projection device (2) for a motor vehicle (1), which is designed to generate a virtual image (10) on a projection surface (7), and which has an outer housing (12) in which at least one light-generating device (3) and an image-generating unit (13) for generating the image (10) from the light (4) emitted by the light-generating device (3) are formed, wherein the outer housing (12) has a shaft-like recess (18) on a top surface (17), which is bounded by shaft walls (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32) and through which the image (10) can be emitted from the outer housing (12) onto the projection surface (7), characterized in that a first anti-reflection structure (35) is provided on a first shaft wall (20 to 32) for at least Reflection reduction of incident solar radiation (33,34) is formed with first structural elements (35a) and on a second shaft wall (20 to 32) oriented differently to the first shaft wall (20 to 32) a second anti-reflection structure (36) is formed with second structural elements (36a) for at least reducing the reflection of incident solar radiation (33, 34), wherein an orientation direction (38) of the first structural elements (35a) is equal to an orientation direction (39) of the second structural elements (36a).

Description

[0001] The invention relates to a projection device for a motor vehicle, designed to generate a virtual image on a projection surface. The projection device comprises an outer housing in which at least one light-generating device and an image-generating unit for generating the image from the light emitted by the light-generating device are provided. The outer housing has a shaft-like recess on its upper side, which is bounded by shaft walls and through which the generated virtual image can be projected from the outer housing onto the projection surface.

[0002] Common projection devices used as optical displays in motor vehicles utilize mirrors to project information in a specific direction. These are usually so-called combiner mirrors, which have a semi-transparent reflective surface. This surface allows information projected onto the mirror and reflected by it to be superimposed on information from the surrounding area visible through the mirror. When the projection device is not needed, the mirror is retracted or folded away, for example, into a compartment, to protect it.

[0003] Such display devices are optical projection devices with which virtually generated images are projected, and which are designed as head-up display devices, also known as head-up displays.

[0004] The following documents are known from the state of the art: US 2011 / 0 267 702 A1: This document discloses a head-up display (HUD) system for a vehicle, installed in the dashboard. The system comprises a housing and an optical unit that projects a display light onto the windshield. The optical unit is configured to reflect incident external light, such as sunlight, away from the driver's field of vision and into the housing. This prevents the driver from being disturbed by glare from external light. EP 2 190 025 A1: This document discloses an imaging unit, particularly for wafer-scale image sensors such as CMOS sensors. To prevent unwanted internal reflections, antireflection structures are provided on the non-transparent areas within the unit's air gaps. These structures are preferably "moth-eye" structures, i.e., nanoscale protrusions smaller than the wavelength of light. This method reduces stray light and ghosting within the imaging system. LOHMÜLLER, Theobald. SPATZ, Joachim P. BRUNNER, Robert: Antireflection based on the model of moth eyes. Physics in Our Time, 2008, Vol. 39, No. 6, pp. 266-267: This publication describes a method for producing antireflection coatings by mimicking the structure of moth eyes. The method uses block copolymer nanolithography to deposit nanoparticles onto an optical substrate, which then serve as a mask for a plasma etching process. This creates a nanoscopic columnar structure on the surface, generating a continuous refractive index gradient. The resulting surface significantly reduces reflection over a broad range of wavelengths and angles of incidence. DE 10 2011 114 850 A1: This document discloses a stray light baffle for an optical detection system, such as a vehicle camera. To reduce stray light, at least one inner surface of the baffle is provided with a surface structure whose structural elements have dimensions in the sub-micrometer range. This nanostructure, which may be modeled on a moth's eye, acts as an anti-reflective coating by creating a gradual change in the refractive index. This suppresses reflections from the inner walls of the baffle.

[0005] These head-up display devices also come in other versions where the virtual image is projected onto the inside of the windshield, allowing it to be viewed from the inside by the observer, particularly the driver. Furthermore, various versions of head-up display devices are known where the virtual image is not projected onto the windshield, but rather, with the help of an additional mirror—the aforementioned combination mirror—is projected towards the observer. Thus, with proper adjustment of the combination mirror, the image is projected onto the observer's face.

[0006] In known projection devices of this type, the view of the virtual image or the perception of this virtual image for an observer and thus a driver is impaired by disturbing scattered light, which occurs through reflection of solar radiation on the outer housing, especially in the area of ​​the shaft-like depression.

[0007] It is also known that corresponding areas of the outer casing are currently coated with a deep black, matte paint to reduce this scattered light. However, this approach is very expensive and, moreover, only partially effective in suppressing these unwanted reflections of sunlight.

[0008] Furthermore, this type of coating has another disadvantage: depending on the viewing angle, the incident light, and therefore sunlight, is reflected to varying degrees. This means that at certain sun positions and thus specific angles between the incident sunlight and such a shaft wall, certain areas appear black while others reflect a grayish hue. As a result, depending on the sun's position, distracting, visible areas appear in the virtual image.

[0009] Furthermore, it is also known that instead of such coatings, an eroded or etched surface is created on individual wall areas, which, however, makes the effect described above even more pronounced. Further processing can achieve a slight improvement in this regard, but with the result that very strong angle-dependent reflections and thus undesirable scattered light still occur. The shallower the angle of incidence, the more pronounced this effect becomes.

[0010] The object of the present invention is to provide an optical projection device for a motor vehicle in which the solar radiation incident on the outer casing is prevented from undesirable reflection and in this context the observation of the virtual image by a user of the motor vehicle is not undesirably impaired.

[0011] This task is solved by a projection device and a motor vehicle according to the independent claims.

[0012] A projection device according to the invention for a motor vehicle is designed to generate a virtual image on a projection surface. The projection device comprises an outer housing in which at least one light-generating device is formed and a separate image-generating unit is formed for generating the image from the light emitted by the light-generating device.

[0013] The outer housing has an inward-facing, shaft-like recess on its upper surface, bounded by shaft walls, through which the image from the outer housing can be projected onto the projection surface. The projection surface can be the windshield of the vehicle. However, the projection device can also be designed to include its own additional external mirror as the final mirror in the beam path to the observer, a so-called combining mirror, which then reflects the virtual image towards the observer. This combining mirror is then separate from the windshield.

[0014] A key aspect of the invention is that a first, structurally defined anti-reflection structure is formed on a first shaft wall of this shaft-like depression to at least reduce the reflection of incident solar radiation. This first anti-reflection structure has first, structurally defined geometric elements. On a second shaft wall, oriented differently from the first shaft wall, a second, structurally defined anti-reflection structure is formed to at least reduce the reflection of incident solar radiation. This second anti-reflection structure also has second, structurally defined geometric elements, with one orientation direction of the first structural elements being the same as one orientation direction of the second structural elements.Thus, through very specific, tangible, and geometrically defined structural elements, it is achieved that incident solar radiation is not undesirably reflected in such a way as to impair the observer's perception of the virtual image. The anti-reflection structures essentially cause the solar radiation to "fall off," preventing it from being undesirably reflected, particularly in the direction of the observer. This effect is achieved to a particularly high degree by the identical orientation of these separate first and second structural elements, as also required by the invention. Virtually independent of how the shaft walls are oriented relative to each other and / or how they are oriented to the incident solar radiation, the same effect of at least reducing the reflection of the incident solar radiation is achieved across all shaft walls.

[0015] Preferably, structural elements are formed integrally with the shaft walls. This reduces the number of components, avoids undesirable positional tolerances, and allows for the precise manufacturing and production of highly intricate and diverse structural elements.

[0016] Preferably, the first anti-reflection structure has points as its first structural elements, and the second anti-reflection structure also has points as its second structural elements. These points, extending from the surfaces of the shaft walls in the same orientation, taper towards the sides facing away from the surfaces. These points allow for high structural element densities with particularly advantageous configurations to achieve an anti-reflection structure.

[0017] Preferably, these points are arrowheads and thus have a quasi-conical or pyramidal shape. However, a point-like structure can also be realized in cross-section, in which case one structural element is an elongated rib that, for example, advantageously extends in a straight line.

[0018] In a further advantageous embodiment, it can be provided that the first anti-reflection structure has moth-eye shapes as its first structural elements, and the second anti-reflection structure has moth-eye shapes as its second structural elements. These specific configurations of the structural elements also enable a very advantageous reflection behavior of the sunlight with regard to avoiding any undesirable influence on the observation of the virtual image.

[0019] In a further advantageous embodiment, it can be provided that the first anti-reflection structure comprises retroreflectors, in particular retroprisms, as its first structural elements, or that the second anti-reflection structure comprises retroreflectors, in particular retroprisms, as its second structural elements. These specific additional structural elements also generate the aforementioned advantages.

[0020] It may be provided that the orientation directions of the anti-reflection structures, with their main extensions (which may also be, for example, central axes or axes of symmetry), are aligned towards the observer, particularly towards the driver's eye. It may also be provided that the orientation directions of the anti-reflection structures are directed at an angle between 80° and 130° to the orientation of the light forming the image and emerging from the shaft-like recess.

[0021] In an advantageous embodiment, the anti-reflection structures are designed as microstructures. The aforementioned advantages are then also present. Microstructuring, where the structural elements are thus formed in the micrometer range, allows for the creation of very small structures that are practically invisible or only partially perceptible to the human eye. This ensures that there are no elements on the shaft walls that appear undesirably bulky and, at the same time, do not impede the emission of light, which represents the virtual image.

[0022] In particular, the shaft walls with their anti-reflective structures are designed as one-piece injection-molded components. Preferably, the outer housing is also designed as a one-piece injection-molded part. This plastic design makes it particularly advantageous for the anti-reflective structures, especially if they are created as microstructures, to be incorporated into an injection mold as a negative mask, particularly by means of laser radiation. This allows the desired anti-reflective structure to be created with very high precision when the plastic is introduced into the injection mold, and also ensures very high reproducibility.

[0023] In particular, the anti-reflection structure ensures that, when viewing the chamber of the optical path, the surfaces at angles to each other, and especially the aforementioned shaft walls, are perceived by an observer as a homogeneous surface. The disturbing color and brightness variations are thereby eliminated by the invention or an advantageous embodiment thereof.

[0024] It may also be provided that the structural elements are varied in their structural form and / or in their dimensions, especially in height from the surface of a shaft wall, in order to achieve a correspondingly homogeneous perception of the shaft walls.

[0025] In a particularly advantageous embodiment, the shaft walls are provided to be completely unpainted, at least on the surfaces where the anti-reflective structures are applied or formed. In particular, they are also neither eroded nor etched.

[0026] Furthermore, the invention also relates to a motor vehicle with a projection device according to the invention or an advantageous embodiment thereof.

[0027] The individual orientation direction or preferred direction of the different structural elements ensures that the reflectance, which otherwise depends on the angle of incidence of the light on a surface, is the same for the differently oriented shaft walls, since the structural elements on these shaft walls are not oriented perpendicular to the surface, but are directed in a common preferred direction or orientation direction.

[0028] Further features of the invention are evident from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as those subsequently mentioned in the description of the figures and / or shown in the figures alone, are not only usable in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments that are not explicitly shown and explained in the figures, but which can be derived and generated from the explained embodiments by separate combinations of features, are also to be considered as encompassed and disclosed by the invention. Embodiments and combinations of features that do not exhibit all the features of an originally formulated independent claim are also to be considered disclosed.

[0029] The invention will now be explained in more detail with reference to preferred embodiments and the accompanying drawings.

[0030] This shows: Fig. 1 a partial representation of an embodiment of a motor vehicle according to the invention, which has a projection device according to an embodiment of the present invention; Fig. 2 the projection device in a mounted state in a motor vehicle; Fig. 3 a perspective view of the projection device with a view from above of a shaft-like recess of an outer housing; Fig. 4 a perspective sectional view of the view in Fig. 3; and Fig. 5 a simplified representation of shaft walls with anti-reflection structures.

[0031] In the figures, identical and functionally equivalent elements are given the same reference symbols.

[0032] Fig. Figure 1 shows a partial view of a motor vehicle 1 according to an embodiment of the present invention. In this embodiment, the motor vehicle 1 is configured as a passenger car. The motor vehicle 1 comprises an optical projection device 2, which is configured to project a virtual image onto a projection surface. In this embodiment, the projection device 2 is configured as a head-up display.

[0033] The projection device 2 comprises an outer housing 12 in which a light-generating device 3 is arranged. Light 4 is emitted by means of the light-generating device 3, which has at least one light source. Furthermore, the projection device 2 also comprises an image-generating unit 13, for example, a TFT display, which generates the image from the light 4. The projection device 2 can, for example, have a screen with which light from a light source of the light-generating device 3 is processed to generate the virtual image 10, and the image to be displayed is then provided. In addition, the projection device 2 comprises an optical device 5. In this case, the optical device 5 comprises a mirror 6. The light emitted by the image-generating unit 13, in the form of the virtual image, first strikes the mirror 6 and then a display element or...a projection surface external to the device, which in the exemplary embodiment is in particular a windshield 7. The light-generating device 3, the image-generating unit 13 and the optical device 5 are arranged inside the outer housing 12, which in turn is arranged inside a dashboard 14 of the motor vehicle 1.

[0034] The windshield 7 has a reflective surface and is semi-transparent. The light emitted by the image-generating unit 13 is projected onto the windshield 7 by means of the optical device 5. Furthermore, the light projected onto the windshield 7 is reflected to the eyes 9 of an observer, in particular a driver 8 of the motor vehicle 1. Thus, this display superimposes itself on the light reaching the eyes 9 of the driver 8 from an ambient area 11 of the motor vehicle 1 and on the light projected onto the windshield 7. For the driver 8 of the motor vehicle 1, this results in a virtual display or a virtual image 10.

[0035] Fig. Figure 2 shows a schematic perspective view of the projection device 2 in a mounted state on a motor vehicle component 15, in particular on the dashboard 14. The outer housing 12 is arranged on a support 16. In particular, the arrangement is effected by bonding the outer housing 12 to the support 16.

[0036] In Fig. Figure 3 shows a perspective view of an embodiment of a projection device 2 with an embodiment of an outer housing 12. The outer housing 12 has a top surface 17, which, when the outer housing 12 is installed in the motor vehicle 1, as shown in Fig. As shown in Figure 2, the opening faces the vehicle interior and thus also the windshield 7, in which a shaft-like recess 18 is formed. The shaft-like recess 18, projecting into the interior of the outer housing 12, is also the opening from which the virtual image 10 is emitted from the outer housing 12 to the outside. This shaft-like recess 18 is bounded by a plurality of shaft walls 19, 20, 21, 22, 23, 24, 25. The number and orientation of these shaft walls 21 to 25 are shown in Figure 2. Fig. 3 is not to be understood as exhaustive. As is also stated in Fig. Figure 4 shows exemplary further shaft walls 26, 27, 28, 29, 30, 31, 32, which in the exemplary embodiment also delimit this shaft-like depression 18. In particular, it is provided that these shaft walls delimiting the shaft-like depression 18, as shown in Figure 4, are constructed of a shaft-like depression 18. Fig. 3 and Fig. The four examples mentioned above each have an anti-reflection structure on their surfaces facing recess 18.

[0037] The essential point is that the surfaces of the shaft walls, which are arranged with different orientations and thus not parallel to each other, have anti-reflection structures that at least reduce the reflection of incident solar radiation 33, 34 ( Fig. 5) are formed. These anti-reflection structures each have structural elements that are geometric components. These structural elements of the individual anti-reflection structures are oriented in the same way relative to each other on the respective shaft walls, so that they also have the same orientation direction and, in this context, this orientation direction of the structural elements is practically independent of the respective orientations of the shaft walls relative to each other.

[0038] Thus is in Fig. Figure 5 shows a simplified schematic representation of the area with the shaft walls 29, 30, and 31. An anti-reflection structure 35 is formed on the shaft wall 31, a further separate anti-reflection structure 36 on the shaft wall 30, and a further separate anti-reflection structure 37 on the shaft wall 29 on the surfaces facing the shaft-like depression 18. For example, anti-reflection structure 35 represents a first anti-reflection structure, anti-reflection structure 36 a second anti-reflection structure, and anti-reflection structure 37 a third anti-reflection structure.

[0039] The respective anti-reflection structures 35 to 37 each have several individual structural elements 35a, 36a, and 37a. In this cross-sectional view, the structural elements 35a, 36a, and 37a are points in the embodiment shown. As in Fig. As can be seen in Figure 5, the structural elements 35a, representing the first structural elements, the structural elements 36a, representing the second structural elements, and the structural elements 37a, representing the third structural elements, are oriented in the same way and are therefore also designed with correspondingly identical orientation directions. In the specific embodiment, this means that a central axis 38 of a point 35a, which is oriented the same way for all further structural elements 35a, and the other central axes of the other structural elements 35a are arranged parallel to this central axis 38, parallel to the central axes 39 of the structural elements 36a, and also parallel to the central axes 40 of the structural elements 37a. These central axes 38, 39, and 40 are thus aligned parallel to each other, regardless of how the individual shaft walls 31, 30, and 29 are oriented relative to each other and thus at what angle the surfaces of these shaft walls 29 to 31 are oriented.

[0040] Structural elements 35, 36 and 37 are formed in one piece. In particular, a design as an injection-molded component is provided.

[0041] It can also be provided that an anti-reflection structure additionally or instead of a structural element 35a, 36a, 37a designed as a point, has at least one structural element designed as a moth's eye. Additionally or instead of this, it can also be provided that an anti-reflection structure additionally or instead of this has at least one structural element which is a retroreflector, in particular a retroprism.

[0042] Advantageously, the anti-reflection structures are designed as microstructures. The shaft walls, which feature these anti-reflection structures, are unpainted.

[0043] It can be used in the design in Fig. 3 and Fig. 4 It is also provided that the funnel-shaped enclosures 41, which open onto the shaft-like depression 18, also have an anti-reflection structure at least in some areas.

[0044] In Fig. Figure 5 shows two different examples of solar radiation 33 and 34, which do not occur simultaneously, but rather represent different sun positions relative to the outer casing 2 and thus also to the shaft walls. For both sun positions and thus both orientations of solar radiation 33 and 34 relative to the outer casing 12, the design of the anti-reflection structures enables at least a reduction in reflection, whereby the sun rays 33 and 34 then dissipate within this anti-reflection structure.

Claims

[1] Projection device (2) for a motor vehicle (1), which is designed to generate a virtual image (10) on a projection surface (7), and which has an outer housing (12) in which at least a light-generating device (3) and an image-generating unit (13) for generating the image (10) from the light (4) emitted by the light-generating device (3) are formed, wherein the outer housing (12) has a shaft-like recess (18) on a top surface (17), which is bounded by shaft walls (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32) and through which the image (10) can be emitted from the outer housing (12) onto the projection surface (7), characterized by, that on a first shaft wall (20 to 32) a first anti-reflection structure (35) for at least reducing the reflection of incident solar radiation (33, 34) with first structural elements (35a) is formed and on a second shaft wall (20 to 32) oriented differently to the first shaft wall (20 to 32) a second anti-reflection structure (36) for at least reducing the reflection of incident solar radiation (33, 34) with second structural elements (36a) is formed, wherein an orientation direction (38) of the first structural elements (35a) is equal to an orientation direction (39) of the second structural elements (36a). [2] Projection device (2) according to claim 1, characterized by , that structural elements (35a, 36a, 37a) are formed in one piece with the shaft walls (20 to 32). [3] Projection device (2) according to claim 1 or 2, characterized by, that the first anti-reflection structure (35) has spikes as first structural elements (35a) and the second anti-reflection structure (36) has spikes as second structural elements (36a). [4] Projection device (2) according to any one of the preceding claims, characterized by , that the first anti-reflection structure (35) has moth eyes as first structural elements (35a) and the second anti-reflection structure (36) has moth eyes as second structural elements (36a). [5] Projection device (2) according to any one of the preceding claims, characterized by , that the first anti-reflection structure (35) has retroreflectors, in particular retroprisms, as first structural elements (35a) and the second anti-reflection structure (36) has retroreflectors, in particular retroprisms, as second structural elements (36a). [6] Projection device (2) according to any one of the preceding claims, characterized by, that the orientation directions (38, 39, 40) of the structural elements (35a, 36a, 37a) are directed at an angle between 80° and 130° to an orientation of the light representing the image (10) and emerging from the shaft-like depression (18). [7] Projection device (2) according to any one of the preceding claims, characterized by that the anti-reflection structures (35, 36, 37) are formed as microstructures. [8] Projection device (2) according to any one of the preceding claims, characterized by , that the shaft walls (20 to 32) with the anti-reflection structures (35, 36, 37) are formed as a one-piece injection-molded component. [9] Projection device (2) according to any one of the preceding claims, characterized by , that the shaft walls (20 to 32) are unpainted at least on the surfaces on which the anti-reflective structures (35, 36, 37) are applied. [10] Motor vehicle (1) with a projection device (2) according to one of the preceding claims.

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