Detection device for head-up display (HUD)

Abstract

The invention relates to a detection device for a head-up display (HUD), comprising at least: an imaging unit (8), an optical element (13), which is suitable for deflecting radiation from the imaging unit (8) in the direction of a windshield (1) and thereby illuminating a HUD area (B) of the windshield (1) to generate a virtual image (7), a positioning device (11), which is suitable for fixing the windshield (1) in a specific arrangement relative to the optical element, and a camera unit (12), which is suitable for capturing the virtual image (7) through the windshield (1) from different eye positions, wherein the optical element (13) is designed so that the entire virtual image (7) is located within a depth of field area (Δd) of the camera unit (12).

Description

[0001] The present invention relates to a detection device for a head-up display (HUD), in particular for simulating contact with a HUD, a method for detecting such a HUD, and the use of an optical element in such detection.

[0002] Modern cars are increasingly equipped with so-called head-up displays (HUD). By means of a projector, for example in the instrument panel area or in the overhead area, the image is projected onto the windshield, reflected there and perceived by the driver (from his perspective) as a virtual image behind the windshield. Important information can thus be projected into the driver's field of vision, such as the current driving speed, navigation instructions or warning instructions, which can be perceived by the driver without him having to take his eyes off the road. Head-up displays can thus contribute significantly to increasing traffic safety. The projection distance (distance between the virtual image and the driver) of a conventional HUD for displaying static information is typically about 2 m.

[0003] Newer variants of HUD are called simulated contact HUD or augmented reality HUD. These HUDs are characterized by a larger HUD area (projection surface on the glass plate) and a significantly larger projection distance of at least 5 m, usually even more than 7 m. Simulated contact HUD opens up the possibility that the information to be read is no longer just statically projected onto the glass plate, but optical information is used to identify elements of the real vehicle environment - exemplary applications are visually marking lane boundaries, visually highlighting pedestrians on the side of the road, navigation instructions directly on the lane, or marking vehicles recognized by the driving assistance system. The larger projection distance is generated by the larger optical path length of the light beam in the projector (for example, by additional reflectors and a larger volume). Simulated contact HUD is known, for example, from DE102014001710A1, WO2014079567A1, US2013249942A1, US2014354692A1, US2014375816A1 and WO2013136374A1.

[0004] It is customary for the conception of a HUD to check the optical quality of the image in a test device. In this case, the windshield is illuminated by an imaging unit, wherein a virtual image corresponding to the HUD image is generated, usually in the form of a characteristic pattern of dots and lines. This image is recorded through the windshield by a camera unit from a number of possible eye positions of the driver. With the help of these images, the occurrence of distortions, aberrations, phantoms due to multiple reflections and other optical effects can then be evaluated in detail for different eye positions.

[0005] Due to the curved geometry of conventional windshields and the associated field curvature, the virtual HUD image is not arranged in one plane, but is also curved in space. This does not cause problems when detecting conventional HUDs, since the image has only relatively small dimensions and can therefore be captured by the camera unit in an overall clear manner despite the curvature. However, in the case of simulated contact HUDs with their significantly enlarged image size, the image curvature can have the effect that some parts of the image always appear unclear due to the limited depth of field of the camera unit, which makes evaluation difficult or impossible. Since the radiation strikes the windshield at a certain angle to the optical axis, further aberrations arise from astigmatism.

[0006] The object of the present invention is to provide an improved detection device for a head-up display (HUD), which in particular can also be used to simulate contact with the HUD.

[0007] A test device of the type (Gattungsgemäß) comprises at least one imaging unit, a positioning device and a camera unit. The test device according to the invention for a head-up display (HUD) further comprises an optical element. The imaging unit emits radiation to generate a virtual image after reflection on the windshield to be tested, the positioning and size of which correspond to the later HUD image. However, the windshield is not directly illuminated by the imaging unit, but indirectly through the optical element. The optical element is suitable and arranged to deflect the radiation of the imaging unit in the direction of the windshield and thereby illuminate the HUD area of ​​the windshield to generate a virtual image. The positioning device is suitable and arranged to fix the windshield in a specific arrangement relative to the optical element and relative to the imaging unit. The windshield should be illuminated by the imaging unit in the same way as it will be later illuminated by the HUD projector in the vehicle, so that the image generated in the test device is a good model for the subsequent HUD projection. The radiation of the imaging unit should therefore strike the same area of ​​the windshield at essentially the same angle of incidence and the same aperture angle as the radiation of the later HUD projector. The camera unit is suitable and arranged for recording virtual images through the windshield from different eye positions. The eye position refers to the possible positioning of the eyes of a later observer / user of the HUD.

[0008] The fact that the curvature of the virtual image in space (curvature of field) can be reduced by means of the optical element, so that the entire image of the camera unit can be captured in sharp focus, is a great advantage of the invention. The optical element is designed so that the entire virtual image lies within the depth of field region of the camera unit. More precisely, this means that the size of the image along the optical axis (extending between the camera unit and the center of the image) is smaller than or equal to the size of the depth of field region of the camera unit, so that it is possible to focus the camera unit on the image so that the entire image lies within this depth of field region and is therefore displayed in sharp focus. Strictly speaking, the image here includes an overlap of the main image and the phantom image, since both should be displayed in sharp focus. Ideally, the main image is arranged in a single plane, onto which the camera unit can be focused. However, slight deviations from this ideal planarity, i.e. slight residual curvature of the image, are acceptable. The degree of acceptable curvature depends here on the camera unit used and its depth of field. In addition to the curvature of field, astigmatism can also be compensated by means of the optical element according to the invention.

[0009] The object of the invention is to shorten the image size so that the entire image can be captured within the depth of field of the camera. This problem arises in particular in the context of simulated contact HUDs. Therefore, in a preferred embodiment, without the use of optical elements, the virtual image will not be completely within the depth of field of the camera unit. In other words, without the use of optical elements, the size of the image along the optical axis is larger than the depth of field of the camera unit.

[0010] Another advantage of the invention is that the beam path is virtually bent by the optical element, whereby the detection device can be designed to save considerable space, which is advantageous in particular with regard to simulated contact HUDs and their large projection distances.

[0011] The present invention also includes a method for testing a HUD, the method comprising at least the following method steps:

[0012] (a) positioning the windshield panel with the HUD area with a specific arrangement relative to the optical element by means of a positioning device,

[0013] (b) irradiating the optical element via an imaging unit, wherein the radiation is deflected by the optical element in the direction of the windshield and irradiates the HUD area, thereby generating a virtual image,

[0014] (c) capturing virtual images from different eye positions with the aid of a camera unit,

[0015] The optical element (13) is designed in such a way that the entire virtual image (7) lies within the depth of field region (Δd) of the camera unit (12).

[0016] The present invention is described in detail below, wherein preferred embodiments also relate to the device and method.

[0017] The optical element is preferably a mirror, in particular a curved mirror. By appropriately designing the curvature of the mirror, undesired field curvatures of the virtual image and possible astigmatism can be compensated. Thus, for example, the radius of curvature of the mirror can be changed starting from the center in the direction of the edge in order to influence the positioning of the image portion generated by the respective mirror area. When conceiving the reflector, the geometry of the glass sheet to be inspected is decisive and the position of the camera unit must also be taken into account. The required design of the reflector, in particular the curvature of the reflector, can be determined by professional conventional methods, for example by using the known Coddington equations, in particular by using the so-called ray tracing method. The optical element is particularly preferably a highly polished metal mirror, which can be manufactured with high precision. Alternatively, however, other optical elements are also conceivable, such as lenses with a suitable curvature distribution.

[0018] In a preferred embodiment, the optical element (especially when it is designed as a reflector) is not rotatable, but rather statically arranged. This allows for a simpler and less error-prone construction, which allows for a higher measurement accuracy and a faster measurement. The optical element must then be designed so that the entire eyebox is illuminated simultaneously. In this regard, the optical element of the invention differs in particular from a reflector in a HUD projector, which can only illuminate a limited window of the eyebox and must be rotated to cover the entire eyebox.

[0019] The detection device of the invention is particularly advantageously suitable for detecting simulated contact HUDs (so-called Augmented reality head-up display monitor (AR-HUD)). They have a significantly greater projection distance (distance between image and observer) and a significantly larger projected image than conventional HUDs. As a result, the effect of the curvature of the projected image is more noticeable when recording the projected image, so that the entire image may not be captured clearly using conventional detection devices, because parts of the image extend outside the depth of field of the camera unit. This effect is reduced by the device according to the invention. Conventional HUDs have a projection distance of less than 3 m, while simulated contact HUDs have a projection distance that (sometimes significantly) exceeds 3 m. Therefore, in a particularly advantageous embodiment, a virtual image is generated whose projection distance is greater than 3 m, preferably greater than 4 m, and particularly preferably greater than 5 m.

[0020] A projection assembly for a head-up display (HUD) comprises at least a vehicle windshield (in particular of a motor vehicle, such as a passenger car) and a projector. The projector illuminates an area of ​​the windshield in which radiation is reflected in the direction of an observer (driver), thereby generating a virtual image, which an observer located in the vehicle perceives from behind the windshield. The area of ​​the windshield that can be illuminated by the projector is called the HUD area. The projector is directed toward the HUD area. The beam direction of the projector can usually be changed by a reflector, in particular vertically, so that the projection is matched to the height of the observer. The area in which the observer's eyes must be located at a given reflector setting is called the eye range window. The eye range window can be moved vertically by adjusting the reflector, whereby the entire area that can be reached thereby (i.e. the superposition of all possible eye range windows) is called the eye range. An observer located within the eye range can perceive the virtual image. Of course, this means that the observer's eyes must be located within the eye range, and not, for example, the entire body. The eye range seems to be the sum of all possible positioning of the observer's eyes, which are usually referred to as eye positions. The beam extending between the projector and the center of the eyebox is often referred to as the center beam. It is the characteristic reference beam used to conceive HUD projection combinations.

[0021] The technical terms used here from the field of HUD are generally known to the skilled person. For a detailed explanation, reference is made to the paper "Simulation-based measurement technology for testing head-up displays" by Alexander Neumann of the Institute of Computer Science at the Technical University of Munich (Munich: Technical University of Munich, 2012), in particular Chapter 2 "Head-up displays".

[0022] The perception of the HUD projection depends on the eye position. Therefore, HUDs are usually conceived to be optimized for the center of the eye range, and at other eye positions distortions, stronger phantoms or other undesirable optical effects may sometimes appear. This should be checked by the device of the present invention.

[0023] The HUD area of ​​the windshield is illuminated by means of an imaging unit to generate a virtual test image. The test image is usually a pattern of dots and / or lines. Such a pattern can then be quantitatively evaluated well in terms of optical criteria. The pattern may have a pre-distortion so that possible distortions inevitably caused by the windshield are compensated and the pattern in the virtual image (at least relative to the central light beam) looks regular. In a preferred embodiment, the imaging unit comprises a plate and a surface light source that backlights the plate. The pattern is introduced into the plate in the form of a penetration depending on the type of aperture plate. The plate can be made, for example, of metal or plastic. Alternatively, the imaging unit can also be implemented, for example, as a display (screen), such as an LED, LCD or DLP display.

[0024] The radiation of the imaging unit strikes the optical element and from there is projected onto the HUD region of a windshield that is fixed in a positioning device. The positioning device is, for example, a holder in which the windshield is clamped, whereby the position of the windshield can be reproduced. The relative arrangement of windshield, optical element and imaging unit is selected so that the radiation strikes the windshield at the same angle and in the same size as the radiation of the HUD projector that will be later projected, so that the test image is a realistic model of the HUD projection.

[0025] The virtual test images thus generated are recorded from different eye positions by means of a camera unit. For this purpose, a single camera can be used which is movably mounted, for example, on a robot arm so that it can be moved between the different eye positions. Alternatively, a plurality of cameras can also be used which are each assigned to an eye position. In this case, there is no need for movement during the test, so that the cameras are preferably mounted statically.

[0026] The images recorded by the camera unit are then analyzed using conventional image processing programs. For example, depending on the eye position, the occurrence and intensity of phantoms, distortions such as rotation or keystoning, and other optical effects can be examined.

[0027] A windshield panel usually comprises an outer glass panel and an inner glass panel which are joined to each other by a thermoplastic interlayer. The windshield panel is provided for separating the interior from the external environment in the window opening of the vehicle. In the context of the present invention, the inner glass panel refers to the glass panel of the composite glass panel which faces the interior (vehicle interior). The outer glass panel refers to the glass panel which faces the external environment. Windshield panels are usually curved, wherein a common radius of curvature is about 10 cm to about 40 m. A radius of curvature of 2 m to 20 m usually occurs in the HUD. The interior side surface of the inner glass panel is manufactured to be essentially concave, and the outer side surface of the outer glass panel is manufactured to be convex. The interior side surface here refers to the surface facing the interior of the vehicle in the installed position. The outer side surface refers to the surface facing the external environment in the installed position.

[0028] As with the HUD, the windshield is illuminated from the inside in the detection device. Therefore, the HUD projector and the imaging unit are arranged on the interior side of the windshield so that the inner glass sheet of the windshield faces them. The windshield is illuminated via the interior side surface of the inner glass sheet.

[0029] In HUD, the so-called phantom problem is common. The projector is arranged in the interior of the vehicle, and its radiation is projected onto the interior-side surface of the inner glass plate, on which a part is reflected in the direction of the driver's eyes, thereby generating the required virtual image, which the driver perceives from his perspective behind the windshield, that is, on the outside. Most of the radiation passes through the windshield, of which a part is reflected again on the outer surface of the outer glass plate. This secondary reflection generates another HUD image - a phantom, which the driver perceives slightly offset from the main image and with less intensity in an interfering manner. Common windshields have a wedge shape, so that the interior-side surface of the inner glass plate and the outer surface of the outer glass plate are arranged at a certain angle to each other so that the phantom overlaps with the main image or at least reduces its distance, so that the phantom appears less interfering. However, this compensation is usually not ideal and also depends on the position of the eyes.

[0030] The wedge shape of the windshield is usually achieved by using a wedge-shaped thermoplastic interlayer. Here, the thickness of the interlayer in the vertical extension between the upper edge and the lower edge of the windshield is at least partially variable. "Partial" here means that the vertical extension between the upper edge and the lower edge has at least one part in which the thickness of the interlayer varies depending on the position, i.e. the interlayer has a wedge angle. The thickness of the interlayer is variable at least in the HUD area. However, the thickness can also vary in a plurality of parts or increase substantially continuously over the entire vertical extension (e.g. from the lower edge to the upper edge). The vertical extension means an extension between the upper edge and the lower edge with an extension direction substantially perpendicular to the upper edge. Since the upper edge in the windshield can deviate significantly from a straight line, the vertical extension in the context of the present invention more precisely has the orientation of the connecting line between the angles perpendicular to the upper edge. The interlayer has a limited wedge angle at least partially, i.e. in the part with variable thickness, i.e. a wedge angle greater than 0°. The wedge angle refers to the angle between the two surfaces of the interlayer. If the wedge angle is not constant, a tangent to the surface should be used at one point for its measurement. Typical wedge angles are 0.2 mrad to 1 mrad, in particular 0.3 mrad to 0.7 mrad. The wedge angle can be constant in the vertical extension, which results in a linear variation of the thickness of the intermediate layer, wherein the thickness generally and preferably increases from the bottom to the top. The directional specification "from the bottom to the top" means the direction from the lower edge to the upper edge. However, more complex thickness profiles can also exist, in which the wedge angle is variable linearly or nonlinearly from the bottom to the top (i.e. depending on the position in the vertical extension).

[0031] In a simulated contact HUD or augmented reality HUD, not only is information projected onto a limited area of ​​the windshield, but elements of the external environment are also included in the display. Examples of this are marking pedestrians, displaying the distance to the vehicle driving ahead or projecting navigation instructions directly onto the lane, for example to mark the lane to be selected. A simulated contact HUD differs from a conventional static HUD in that the projection distance is greater than 3 m, preferably greater than 4 m and typically even greater than 5 m. In the case of a static HUD, the projection distance is significantly smaller, typically about 2 m. In the context of the present invention, the projection distance denotes the distance between the virtual image and the observer, ie typically the driver's head. The projection distance is preferably at least 7 m. The projection distance is preferably at most 15 m.

[0032] In the case of a projection assembly that simulates a contact HUD, the projection distance for all projected images is essentially constant. Projections that the observer should subjectively perceive at different distances also have essentially the same projection distance in reality. The subjective impression of different distances is achieved through geometric optical effects.

[0033] The distance between the windshield and the virtual image is usually referred to as the image distance. Since the distance between the driver's head and the windshield is usually about 1 meter, the image distance is approximately 1 meter smaller than the projection distance. Instead of the projection distance, the image distance can therefore also be used as a criterion with sufficient accuracy. The image distance is therefore preferably greater than 2 m, particularly preferably greater than 3 m, very particularly preferably greater than 4 m, preferably at most 14 m.

[0034] Compared with conventional static HUDs, the HUD area in simulated contact HUDs is usually larger. In a preferred embodiment, the area of ​​the HUD area is at least 7%, particularly preferably at least 8%, of the area of ​​the windshield. The area of ​​the HUD area of ​​a static HUD is usually at most 4-5% of the area of ​​the windshield.

[0035] The inner and outer glass panes are preferably made of glass, particularly preferably soda-lime glass, which has proven to be advantageous for window glass. The glass panes may also be made of other glass types, such as borosilicate glass or aluminosilicate glass. The glass panes may in principle be made of plastic, in particular polycarbonate or PMMA, instead. The thickness of the outer and inner glass panes can in principle be freely selected within the range of values ​​commonly found in the profession. Common single glass pane thicknesses for conventional windshields are 1 mm to 5 mm, in particular 1.2 mm to 3 mm. Standard glass pane thicknesses are, for example, 2.1 mm or 1.6 mm. The outer glass panes, the inner glass panes and the thermoplastic interlayer may be clear and colorless, but may also be tinted or colored. In a preferred embodiment, the total transmittance through the composite glass is greater than 70%, in particular when the composite glass is a windshield. The term total transmittance is based on the method for detecting the light transmittance of motor vehicle glass panes as specified by ECE-R 43, Annex 3, § 9.1.

[0036] The intermediate layer is usually formed by at least one thermoplastic film, which is preferably based on polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU) or mixtures or copolymers or derivatives thereof, particularly preferably PVB. In the case of a wedge-shaped film, the thickness of the intermediate layer measured at its thin edge is usually 0.2 mm to 2 mm, in particular 0.5 mm to 1 mm.

[0037] The installation angle of the windshield panel is usually 55° to 75°, in particular 60° to 70°, for example about 65°, relative to the horizontal plane.

[0038] The present invention also includes a detection assembly for HUD, which includes the detection device of the present invention and a windshield plate fixed in a positioning device.

[0039] The HUD tested according to the invention is preferably used in a vehicle, particularly preferably a motor vehicle, very particularly preferably a passenger car.

[0040] The invention also includes the use of an optical element for deflecting radiation from an imaging unit onto a HUD region of a windshield panel, the arrangement of which relative to the optical element is fixed by a positioning device, thereby generating a virtual image which is recorded through the windshield panel from different eye positions for detection purposes by means of a camera unit,

[0041] The optical elements are designed in such a way that the entire virtual image lies within the depth of field of the camera unit.

[0042] The invention is explained in more detail below with reference to the accompanying drawings and examples. The drawings are schematic and not true to scale. The drawings do not limit the invention in any way.

[0043] in:

[0044] Figure 1 A top view of the windshield panel used for the HUD is shown.

[0045] Figure 2 Shows the projection surface passing through the HUD Figure 1 The cross section of the windshield panel,

[0046] Figure 3 shows a side view through a conventional detection device for a HUD,

[0047] Figure 4 shows a side view through the detection device of the present invention for a HUD,

[0048] Figure 5 Shows Figure 3 Traditional detection devices and Figure 4 A simulated example image of the detection device of the present invention, and

[0049] Figure 6 A schematic diagram showing the dimensions of the virtual image and the depth of field area of ​​the camera unit.

[0050] Figure 1 A top view of a windshield panel 1 of a HUD projection assembly is shown. The windshield panel 1 has an upper edge O, a lower edge U and two side edges joining them. The upper edge O points upwards towards the roof of the vehicle (top edge) in the installed position, and the lower edge U points downwards towards the engine compartment (engine edge). The windshield panel 1 has a HUD area B, which can be illuminated by the HUD projector in the installed position and is illuminated during operation.

[0051] Figure 2 A cross section through a HUD projection assembly is shown, the HUD projection assembly comprising Figure 1 The windshield 1 is cut along the cutting line A-A'. The windshield 1 consists of an outer glass pane 2 and an inner glass pane 3, which are joined to each other via a thermoplastic intermediate layer 4. The windshield 1 separates the vehicle interior from the external environment, wherein the outer glass pane 2 faces the external environment in the installed position and the inner glass pane 3 faces the vehicle interior. The installation angle β to the horizontal is, for example, 65°.

[0052] The outer glass pane 2 and the inner glass pane 3 consist, for example, of non-prestressed soda-lime glass. For example, the thickness of the outer glass pane 2 is 2.1 mm and the thickness of the inner glass pane 3 is 1.6 mm. These glass panes are often used for windshields. The thickness of the intermediate layer 4 increases continuously in the vertical direction from the lower edge U to the upper edge O at a substantially constant angle between the two surfaces. The intermediate layer 4 is formed by a single PVB film. The thickness of the intermediate layer 4 at the upper edge O is, for example, 1.0 mm, and the thickness of the intermediate layer 4 at the lower edge U is, for example, 0.76 mm. Due to the wedge-shaped design of the intermediate layer 4, the two images generated by the reflection of the projector image on the two surfaces of the outer glass pane 2 and the inner glass pane 3 facing away from the intermediate layer 4 overlap each other. Therefore, disturbing phantoms occur to a lesser extent.

[0053] The projector 5 is directed toward the HUD region B. In this region, an image is to be generated by the projector 5. The projector image is reflected by the windshield 1 in the direction of the observer 6 (vehicle driver). This generates a virtual image 7, which the observer 6 in the vehicle perceives from his perspective behind the windshield 1. The distance between the observer 6 and the virtual image 7 is called the projection distance d. The distance between the windshield 1 and the virtual image 7 is called the image distance w.

[0054] The projection combination is a so-called simulated contact HUD or augmented reality HUD, which is characterized by a large projection distance d of, for example, 10 m. This enables the environment to be included in the visual display, so that, for example, the lane to be selected can appear to be projected directly onto the road as a navigation prompt for the observer 6. In addition to the large projection distance d, the simulated contact HUD also differs from a conventional HUD by a larger HUD area B, which is, for example, 9% of the area of ​​the windshield 1.

[0055] The area within which the eye of the observer 6 must be located to perceive the virtual image is called the eye range window. The eye range window can be adjusted vertically by a mirror in the projector 5 so that the HUD can be matched to observers 6 of different heights and seat positions. The entire reachable area within which the eye range window can move is called the eye range E.

[0056] In the case of a HUD, a series of undesirable optical effects can occur. This involves, on the one hand, distortions of the display, such as rotation or keystoning. On the other hand, the projector radiation is reflected on the two outer surfaces of the windshield 1 so that a slightly offset phantom image is produced in addition to the main image. By means of a wedge angle a, the main image and the phantom image are essentially superimposed on one another, wherein the conception of the wedge angle is usually based on the central beam (the beam between the projector 5 and the center of the eye field E). However, the occurrence of the optical effect depends greatly on the eye position, i.e. the exact arrangement of the observer within the eye field E. Therefore, the occurrence of the effect should be tested depending on the eye position, for which purpose a detection device, which is the subject of the present invention, is used.

[0057] Figure 3 A test device of the type for a HUD according to the prior art is shown. A windshield 1 for the HUD is fixed in a positioning device 11, which specifies its arrangement relative to an imaging unit 8. The imaging unit comprises a plate 9 with a characteristic pattern of penetrations (holes) in the form of points and / or lines and a surface light source 10 which additionally backlights the plate 9. The relative arrangement of the windshield 1 and the imaging unit 8 corresponds to the relative arrangement of the windshield 1 and the HUD projector 5 in the planned HUD configuration at the site of use. The HUD area B of the windshield 1 is illuminated by the imaging unit 8, whereby a virtual image 7 of the characteristic pattern of points and / or lines is generated behind the windshield 1. The radiation is indicated by a gray box arrow. The virtual image 7 is captured by a camera unit 12, for example a camera fixed to a robot arm, from different eye positions within the eye range E. The image of the camera unit 12 can then be evaluated in detail with the aid of image processing software. For example, in particular, the occurrence of undesirable optical effects, such as ghost images or distortions, can be evaluated quantitatively and depending on the eye position to draw conclusions about the quality of the HUD image.

[0058] As shown in the figure, the virtual image 7 is not flat, but is curved, in particular due to the curvature of the glass pane in space. In particular, in the case of large images 7, as they appear in the simulated touch HUD, problems can arise during recording. The camera unit 12 has a limited depth of field, so that it is sometimes not possible to record the entire image in a clear manner. Instead, in each focal plane there are regions of the image 7 that extend outside the depth of field and are therefore not recorded in a clear manner. This affects the evaluation of the recording.

[0059] on the contrary, Figure 4 The detection device for HUD of the present invention is shown. Figure 3In contrast to conventional detection devices of the invention, the windshield 1 is not directly illuminated by the imaging unit 8. Instead, the radiation is deflected by the optical element 13 in the direction of the windshield 1. The radiation is again represented by the grey box arrow. By means of the optical element 13, the virtual image 7 can be influenced so that it is transformed so that it is arranged approximately in a plane, as shown in the figure. At least the curvature of the image 7 is reduced so that its size along the optical axis is at most as large as the depth of field area of ​​the camera unit 12. The camera unit 12 can then be focused so that the entire image 7 is captured clearly and can be evaluated without any problems.

[0060] The optical element 13 is designed, for example, as a curved mirror made of a highly polished metal plate, wherein the influencing of the curvature of the image 7 according to the invention is achieved by a suitable curvature profile of the mirror, wherein the radius of curvature changes appropriately starting from the center of the mirror towards the side edges.

[0061] Figure 5 The embodiment of the present invention and the simulation shooting of the comparative example are shown. Figure 5 (a) Based on Figure 3 In a conventional detection device, the windshield 1 is illuminated directly from the position of the HUD projector with the imaging unit 8. It can be clearly seen that image areas are not displayed sharply because they are not located in the depth of field of the camera area 12. Figure 5 (b) Based on Figure 4 The detection device of the present invention has an aspherical reflector as the optical element 13. The size of the image 7 along the optical axis can be reduced by the optical element 13 so that the image 7 is completely located in the depth of field area and is displayed clearly accordingly.

[0062] In the simulation, a backlit perforated plate with a two-dimensional pattern in the holes was assumed as the imaging unit, a projection distance of 10 m and an image size of 1600 mm x 800 mm (in the plane of the virtual image measured at a distance of 10 m from the central camera (eye point)). Figure 5 In (a), the distance between the perforated plate and the composite glass plate is 10 m. Figure 5 In (b), the distance between the aspheric reflector and the composite glass plate is 300 mm.

[0063] Figure 6 The effect that the invention aims to achieve is shown. The camera unit 12 has a limited depth of field region Δd. This is the depth of field at a far point d along the optical axis (the connecting axis between the camera unit 12 and the center of the image 12) at a given focus setting. f (the point farthest from the camera unit 12, which is clearly shown) and the near point d n(the point closest to the camera unit 12, which is clearly displayed). The virtual image 7 is curved in space, which is mainly caused by the curvature of the windshield 1. This results in a size Δx of the image 7 along the optical axis. If the size Δx is greater than the depth of field area Δd, there is no focal plane in which the entire image 7 can be clearly displayed - it always extends partially outside the depth of field area Δd ( Figure 6 a). By means of the optical element 13 according to the invention, the dimension Δx is reduced so that it is smaller than the depth of field region Δd. Now a focal plane can be selected for which the entire image 7 is clearly visible and can then be analyzed ( Figure 6 b). In order to open up the possibility of an overall sharp display of the image 7, it must generally apply that: Δx ≤ Δd.

[0064] For simplicity here, the image 7 is shown in a single line. In reality, the dimension Δx is based on the entirety of the main image and the phantom, as both should be clearly shown for analysis.

[0065] List of reference numerals:

[0066] (1) Windshield

[0067] (2) Outer glass panel

[0068] (3) Inner glass panel

[0069] (4) Thermoplastic middle layer

[0070] (5) Projector

[0071] (6) Observer / Vehicle Driver

[0072] (7) Virtual Image

[0073] (8) Imaging unit

[0074] (9) (Metal) plate with pattern at the penetration point

[0075] (10) Surface light source

[0076] (11) Positioning device for windshield panel

[0077] (12) Camera unit

[0078] (13) Optical components

[0079] (O) Upper edge of windshield plate 1

[0080] (U) Lower edge of windshield panel 1

[0081] (B) HUD area of ​​windshield panel 1

[0082] α Wedge angle of the middle layer 4

[0083] β Installation angle 1 relative to the horizontal

[0084] d Projection distance / distance between 6 and 7

[0085] w Image distance / distance between 1 and 7

[0086] d n The near point of the camera unit 12

[0087] d f The far point of the camera unit 12

[0088] Δd Depth of field of the camera unit 12

[0089] Δx Dimension of image 7 along the optical axis

[0090] (E) Eye movement range

[0091] AA' vertical cutting line.

Claims

1. A detection device for a head-up display, i.e., HUD, comprising at least: - an imaging unit (8), an optical element (13) arranged to deflect the radiation of the imaging unit (8) in the direction of the windshield (1) and thereby illuminate the HUD area (B) of the windshield (1) in order to generate a virtual image (7), - positioning means (11) arranged to fix the windshield (1) in a specific arrangement relative to the optical element (13), and a camera unit (12) arranged to capture a virtual image (7) through the windshield (1) from different eye positions, wherein the optical element (13) is a curved mirror or lens and is designed so that the curvature of the virtual image caused by the windshield (1) in space is reduced so that the entire virtual image (7) is located within the depth of field region (Δd) of the camera unit (12), wherein the size (Δx) of the virtual image (7) along the optical axis is less than or equal to the depth of field area (Δd) of the camera unit (12), and the size (Δx) of the virtual image (7) along the optical axis is greater than the depth of field area (Δd) of the camera unit (12) when no optical element (13) is used, and wherein the imaging unit comprises a plate having a pattern at the through-holes and backlit by a surface light source or the imaging unit is a display, It is suitable for producing a virtual image (7) at a projection distance (d) greater than 3 m.

2. The detection device for a head-up display according to claim 1, wherein the radius of curvature of the reflector or lens is variable from the center toward the edge.

3. The detection device for a head-up display according to claim 1 or 2, wherein the optical element (13) is arranged in a non-rotatable manner.

4. The detection device for a head-up display according to claim 1 or 2, wherein the camera unit (12) is implemented as a single, movably mounted camera or as a plurality of statically mounted cameras.

5. A method for detecting a head-up display, i.e., HUD, using the detection device according to claim 1 or 2, comprising at least the following method steps: (a) positioning a windshield (1) having a HUD region (B) with the aid of a positioning device (11) in a specific arrangement relative to an optical element (13), (b) irradiating the optical element (13) via the imaging unit (8), wherein the radiation is deflected by the optical element (13) in the direction of the windshield (1) and irradiates the HUD area (B), thereby generating a virtual image (7), (c) recording virtual images (7) from different eye positions by means of a camera unit (12), wherein the optical element (13) is designed such that the curvature of the virtual image caused by the windshield (1) in space is reduced so that the entire virtual image (7) lies within the depth of field region (Δd) of the camera unit (12), and wherein the size (Δx) of the virtual image (7) along the optical axis is less than or equal to the depth of field area (Δd) of the camera unit (12), and the size (Δx) of the virtual image (7) along the optical axis is greater than the depth of field area (Δd) of the camera unit (12) without using the optical element (13), and wherein the imaging unit comprises a plate having a pattern at the through-hole and backlit by a surface light source or the imaging unit is a display, In this case, a virtual image (7) is generated at a projection distance (d) greater than 3 m.

6. Method according to claim 5, wherein the HUD area (B) occupies at least 7% of the area of ​​the windshield (1).

7. A method according to claim 5 or 6, wherein the windshield (1) comprises an outer glass pane (2) and an inner glass pane (3), which are joined to one another by means of a thermoplastic intermediate layer (4), wherein the intermediate layer (4) is configured in a wedge shape at least in the HUD region (B).

8. Method according to claim 7, wherein the windshield (1) is illuminated through the inner glass pane (3).

9. Use of an optical element (13) for deflecting radiation from an imaging unit (8) onto a HUD region (B) of a windshield (1), the arrangement of the windshield relative to the optical element (13) being fixed by a positioning device (11), thereby generating a virtual image (7), which is recorded through the windshield (1) from different eye positions for detection purposes by means of a camera unit (12), wherein the virtual image (7) is generated at a projection distance (d) of greater than 3 m, wherein the optical element (13) is designed such that the curvature of the virtual image caused by the windshield (1) in space is reduced so that the entire virtual image (7) is located within the depth of field region (Δd) of the camera unit (12), wherein the size (Δx) of the virtual image (7) along the optical axis is less than or equal to the depth of field area (Δd) of the camera unit (12), and the size (Δx) of the virtual image (7) along the optical axis is greater than the depth of field area (Δd) of the camera unit (12) when no optical element (13) is used, and wherein the imaging unit comprises a plate having a pattern at the through-holes and backlit by a surface light source or the imaging unit is a display, The optical element (13) is a curved reflector or lens, and the radius of curvature of the reflector or lens is variable from the center toward the edge.

Images