Arrangement for an assistance system of a vehicle

Abstract

The invention relates to an arrangement (1) for an assistance system (100) of a vehicle (2), comprising a radiation source (3) for outputting infrared radiation (10), a radiation receiver (4) for receiving infrared radiation (10), a windscreen (5) with a reflective layer (7) and an image display (6) for outputting visible light (11) and having a layer (8) that reflects infrared radiation, wherein the image display (6) is arranged relative to the reflective layer (7) such that the visible light (11) output by the image display (6) can be reflected by the reflective layer (7) towards the face (9) of a vehicle occupant, and wherein the radiation source (3) and the radiation receiver (4) are arranged relative to the infrared radiation-reflecting layer (8) such that the infrared radiation (10) output by the radiation source (3) can be reflected in the following order via the infrared radiation-reflecting layer (8), the reflective layer (7), the face (9) of the vehicle occupant, the reflective layer (7) and the infrared radiation-reflecting layer (8) towards the radiation receiver (4) and can be received by the radiation receiver (4), wherein, as seen by the vehicle occupant, when looking through the windscreen (5), the reflective layer (7) is arranged entirely in front of an opaque background (19) of the windscreen (5).

Description

[0001] Arrangement for a vehicle assistance system

[0002] The invention relates to an arrangement for a vehicle assistance system. Furthermore, the invention relates to an assistance system for a vehicle having such an arrangement, the use of such an arrangement in a vehicle assistance system, and a method for monitoring a vehicle occupant using such an assistance system.

[0003] Modern vehicles are often equipped with electronic assistance systems, particularly driver assistance systems, which support the driver in controlling the vehicle, for example, by automatically applying the brakes when a collision is imminent or automatically keeping the vehicle in lane if the vehicle veers out of its lane. Such driver assistance systems have proven highly effective in practice, particularly when they include a driver monitoring function, for example, to detect driver fatigue early on or excessive distraction from safe vehicle operation, for example, by using a mobile phone. However, they are increasingly being used not only to monitor the driver but also to monitor other vehicle occupants, for example, to check the general well-being of the occupants.

[0004] For this purpose, it is known to scan the face, and in particular the eyes, of the vehicle occupant using infrared radiation, which is invisible to the naked eye and thus does not disturb the driver or other vehicle occupants. Algorithms can detect the driver's gaze direction and gaze duration, which can indicate fatigue, for example, if the gaze is unusually long in a certain direction (staring). On the other hand, excessively frequent averting of the gaze from the direction of travel, in the case of the driver, can indicate distraction. It is also possible to recognize facial expressions, which can also provide an indication of the vehicle occupant's condition.

[0005] EP 1 333 410 A2 discloses a device for eye tracking of the driver of a vehicle.

[0006] DE 10 2014 115 958 A1 discloses a system for monitoring a driver of a vehicle, comprising an infrared flash for radiating an infrared light onto the driver, an infrared camera for capturing an image illuminated by the beam, including reflections, and a reflective infrared film incorporated into the windshield of the vehicle.

[0007] Modern driver assistance systems with infrared-based monitoring functions operate with wavelengths in the range of 1 pm (micrometer) to 2 pm, in particular with infrared radiation with a wavelength of 940 nm or with infrared radiation with a wavelength of 1400 nm or with infrared radiation with a wavelength of 1550 nm. In order to be able to record even more information about the vehicle occupants, information is increasingly being collected using monitoring functions that operate in the visible light range.

[0008] CN217037318U discloses a driver assistance system that uses a visible-light camera in addition to an IR camera. WO2022224173A1 shows a gaze detection system for a driver, in which a visible-light camera can be used as an alternative to an IR camera.

[0009] JP201912889 and US2016150218A1 disclose a windshield with a HUD assembly. To better align the HUD assembly for a vehicle occupant, the HUD assembly can be connected to an infrared camera and an infrared radiation source, which are designed to detect the position of the vehicle occupant's head. The visible light from the image display of the HUD assembly and the infrared radiation are reflected by the windshield glass.

[0010] FR3073053A1 discloses a HUD assembly and a drowsiness detection assembly comprising an infrared camera and an infrared radiation source. The drowsiness detection assembly can be used to monitor the condition of the vehicle occupant.

[0011] A disadvantage of such solutions is the low degree of reflection on the glass, since visibility through the pane must be maintained in HUD applications.

[0012] Vehicle assistance systems are more difficult to adapt to the geometry of a vehicle if the vehicle also has a projection system, such as a HUD display or a high-contrast HUD display. In such cases, the sensors and cameras for the assistance system often have to share the limited space in the vehicle with the image displays intended for the projection systems.

[0013] The object of the present invention is to provide an improved arrangement for a vehicle assistance system with an infrared-based monitoring function for the driver and / or vehicle occupants, which enables simple and reliable acquisition of information about the driver and / or vehicle occupants. In particular, the object is to provide an improved arrangement that efficiently and space-savingly utilizes the geometry and equipment of modern vehicles.

[0014] These and other objects are achieved according to the invention by an arrangement, an assistance system, and a method according to the independent patent claims. Preferred embodiments are set out in the subclaims.

[0015] The invention relates to an arrangement for an assistance system for a vehicle, in particular a motor vehicle, with a monitoring function for a vehicle occupant of the vehicle based on infrared radiation. The arrangement is particularly suitable for a driver assistance system for monitoring a driver based on infrared radiation. The arrangement comprises a radiation source for emitting infrared radiation and a radiation receiver for receiving infrared radiation. The arrangement further comprises a windshield, preferably consisting of an outer pane and an inner pane, which are connected to one another via a thermoplastic intermediate layer. The windshield is therefore preferably a composite pane. The windshield has a reflective layer. The arrangement also comprises an image display with an infrared radiation-reflecting layer, wherein the image display is intended to emit visible light.According to the invention, the reflective layer is arranged on the windshield in such a way that, when viewed through the windshield, as seen by the vehicle occupant, it is arranged completely against an opaque background of the windshield.

[0016] The radiation source is arranged so that the infrared radiation emitted by the radiation source is directed at the infrared-reflecting layer, reflected by the infrared-reflecting layer onto the reflective layer, and then reflected by the reflective layer onto the face of a vehicle occupant. The infrared radiation emitted by the radiation source first strikes the infrared-reflecting layer of the image display, is reflected by the reflective layer onto the reflective layer, and is then reflected in turn by the reflective layer onto the face of the vehicle occupant. The infrared radiation is reflected from the face of the vehicle occupant back to the reflective layer, then from the reflective layer to the infrared-reflecting layer, and finally from the infrared-reflecting layer to the radiation receiver.

[0017] For ease of reference, the infrared radiation emanating from the radiation source and reflected by the infrared radiation-reflecting layer is called the first reflection radiation. After being reflected by the infrared radiation-reflecting layer, the first reflection radiation hits the reflection layer and can be reflected by the reflection layer onto the vehicle occupant's face. For ease of reference, the infrared radiation emanating from the infrared radiation-reflecting layer and reflected by the reflection layer is called the second reflection radiation. After being reflected by the reflection layer, the second reflection radiation hits the vehicle occupant's face and is then reflected by the vehicle occupant's face. For ease of reference, the infrared radiation emanating from the reflection layer and reflected by the vehicle occupant's face is called the third reflection radiation.After being reflected from the vehicle occupant's face, the third reflection radiation hits the reflection layer and is then reflected by the reflection layer. For ease of reference, the infrared radiation emanating from the vehicle occupant's face and reflected by the reflection layer is referred to as fourth reflection radiation. After being reflected from the reflection layer, the fourth reflection radiation hits the infrared radiation-reflecting layer and is then reflected by the infrared radiation-reflecting layer. For ease of reference, the infrared radiation emanating from the reflection layer and reflected by the infrared radiation-reflecting layer is referred to as fifth reflection radiation. The radiation receiver is arranged so that the fifth reflection radiation reflected by the infrared radiation-reflecting layer is reflected to the radiation receiver and can be received by the radiation receiver.

[0018] Thus, in the arrangement according to the invention, the radiation source, the infrared radiation-reflecting layer, the reflection layer and the radiation receiver are arranged such that infrared radiation emitted by the radiation source can be reflected by the infrared radiation-reflecting layer as first reflection radiation onto the reflection layer, the first reflection radiation can be reflected by the reflection layer as second reflection radiation onto the face of a vehicle occupant, the second reflection radiation can be reflected by the face of the vehicle occupant as third reflection radiation onto the reflection layer, the third reflection radiation can be reflected by the reflection layer as fourth reflection radiation onto the infrared radiation-reflecting layer,the fourth reflection radiation can be reflected by the infrared radiation-reflecting layer as fifth reflection radiation to the radiation receiver and can be received by the radiation receiver.

[0019] The image display is arranged relative to the reflective layer in such a way that visible light emitted by the image display can be reflected by the reflective layer, whereby the reflected visible light is reflected onto a vehicle occupant's face and can be visually perceived by the vehicle occupant. Due to the opaque background, highly reflective reflective layers can be used, which allow a high degree of reflection for infrared light and visible light. The visible light is easily perceived by the vehicle occupant due to the high contrast. This provision represents a high-contrast projection arrangement in the classic sense, which differs significantly from head-up displays (HUDs). The image display is therefore designed to project a virtual image onto the reflective layer, which can be visually perceived by a vehicle occupant.

[0020] The windshield is designed to separate the interior from the outside environment in a window opening of a vehicle.

[0021] A major advantage of the invention is that, due to the combination of an opaque background and a reflective layer, highly reflective layers can be used for both visible light and infrared light, since the visible light cannot escape from the vehicle. Those skilled in the art know that the infrared light-reflecting effect generally correlates with the reflectance for the visible radiation range. A further advantage is the space-saving arrangement of the infrared radiation-reflecting layer, the radiation source, and the radiation receiver, as made possible in a vehicle. These elements can be combined with the projection arrangement, comprising a reflective layer and an image display, in such a way that they do not create a disruptive effect in the vehicle interior. At the same time, they can effectively determine information about a vehicle occupant.The inventive arrangement of the infrared radiation-reflecting layer on the image display simplifies the positioning of the radiation receiver and the radiation source. These do not have to be directed directly at the vehicle occupant, which can be aesthetically disturbing, but can capture the vehicle occupant's gaze via the infrared radiation-reflecting layer and the reflective layer. Detection of the vehicle occupant's face is also improved because the occupant can look directly at the image projected onto the reflective layer by the image display, and at the same time, information about the vehicle occupant can be determined using the radiation source and radiation receiver. A further advantage of the inventive arrangement is that the infrared radiation can hit the vehicle occupant's face from the front due to reflection from the reflective layer.The radiation reflected onto the face of the vehicle occupant can thus contain a radiation component that falls perpendicularly onto the face of the vehicle occupant. Similarly, infrared radiation reflected from the face in a corresponding manner can be received, which contains a radiation component that is reflected perpendicularly from the face of the vehicle occupant.

[0022] The windshield has an interior-side surface which is intended to face the vehicle interior. The windshield also has an exterior-side surface which is intended to face the exterior environment. In the preferred case where the windshield comprises an outer pane and an inner pane, these each have an exterior-side surface and an interior-side surface and a circumferential side edge running between them. In the sense of the invention, the term exterior surface refers to the main surface which is intended to face the exterior environment in the installed position, wherein the exterior surface of the outer surface is also simultaneously the exterior surface of the windshield.For the purposes of the invention, the "interior-side surface" refers to the main surface intended to face the interior in the installed position, with the interior-side surface of the inner pane simultaneously being the interior-side surface of the windshield. The interior-side surface of the outer pane and the outer surface of the inner pane face each other and are connected to one another by the thermoplastic intermediate layer. For the purposes of the invention, the "inner pane" refers to the pane of the windshield facing the vehicle interior. The "outer pane" refers to the pane facing the outside environment.

[0023] The outside surface of the outer pane is called Side I. The inside surface of the outer pane is called Side II. The outside surface of the inner pane is called Side III. The inside surface of the inner pane is called Side IV.

[0024] For the purposes of the invention, the expression "can be reflected" means that it is also possible for only a portion of the incident radiation to be reflected. It is equally understood that it is possible for the incident radiation to be completely reflected.

[0025] In a preferred embodiment of the invention, the infrared-reflecting layer is arranged on a surface of the image display facing the windshield and is permeable to visible light. The surface of the image display facing the windshield is preferably simultaneously the surface of the image display that is intended to emit visible light onto the reflective layer and is technically suitable for this purpose. Particularly preferably, the infrared-reflecting layer extends over at least 40%, very particularly preferably at least 80%, in particular 100%, of the surface of the image display facing the windshield.

[0026] The infrared-reflecting layer is preferably transparent to visible light, especially if it extends over more than 40% of the surface of the image display facing the windshield. However, the infrared-reflecting layer can also be opaque, for example, if it is arranged outside the surface of the image display intended to emit visible light onto the reflective layer.

[0027] The infrared radiation-reflecting layer preferably comprises at least one metal selected from the group consisting of aluminum, tin, titanium, niobium, copper, chromium, cobalt, iron, manganese, nickel-chromium, zirconium, silver, gold, platinum, and palladium, or mixtures thereof. The thickness of the metallic layer is from 50 nm to 1 mm, particularly preferably from 70 nm to 1000 nm, particularly preferably from 80 nm to 500 nm. This achieves particularly good results with regard to the infrared radiation-reflecting effect while simultaneously maintaining high optical transparency. In an advantageous embodiment, the infrared radiation-reflecting layer contains at least one transparent, electrically conductive oxide (TCO). Such layers are corrosion-resistant and can be used on exposed surfaces.The infrared-reflecting layer preferably contains indium tin oxide (ITO), which has proven particularly effective. Alternatively, the conductive layer can also contain, for example, aluminum-zinc mixed oxide (AZO), indium-zinc mixed oxide (IZO), gallium-doped tin oxide (GZO), fluorine-doped tin oxide (SnO2:F), or antimony-doped tin oxide (SnO2:Sb). The thickness of the transparent, electrically conductive oxide is from 50 nm to 1 mm, particularly preferably from 70 nm to 1000 nm, and particularly preferably from 80 nm to 500 nm.

[0028] In a particularly preferred embodiment, the infrared-reflecting layer contains an alternating layer sequence of high-refractive-index layers and low-refractive-index layers. The infrared-reflecting layer particularly preferably consists of an alternating layer sequence of high-refractive-index layers and low-refractive-index layers. The alternating layer sequence of high-refractive-index layers and low-refractive-index layers begins with a high-refractive-index layer and ends with a high-refractive-index layer. The surfaces of the infrared-reflecting layer, with which the layer stack of the infrared-reflecting layer begins and ends, are thus each formed by a high-refractive-index layer (the remaining layer or layers are therefore located between two high-refractive-index layers).The alternating layer structure enables a homogeneous and sufficiently high degree of reflection of infrared radiation to be achieved.

[0029] In an alternating sequence of layers of high-refractive index and low-refractive index, the layers immediately adjacent to a low-refractive index layer are high-refractive index and the layers immediately adjacent to a high-refractive index layer are low-refractive index.

[0030] In a further preferred embodiment, the infrared-reflecting layer contains two high-refractive-index layers and one low-refractive-index layer, and the low-refractive-index layer is arranged between the two high-refractive-index layers, directly adjacent to them. Particularly preferably, the infrared-reflecting layer consists of precisely this layer sequence. Thus, in this embodiment, the infrared-reflecting layer has the following layer sequence:

[0031] High-index layer - low-index layer - high-index layer.

[0032] In a further preferred embodiment, the infrared-reflecting layer contains three high-refractive-index layers and two low-refractive-index layers, and each of the two low-refractive-index layers is arranged between two high-refractive-index layers immediately adjacent to them. Particularly preferably, the infrared-reflecting layer consists of precisely this layer sequence. Thus, in this embodiment, the infrared-reflecting layer has the following layer sequence:

[0033] High refractive index layer - low refractive index layer - high refractive index layer - low refractive index layer - high refractive index layer.

[0034] In a further preferred embodiment, the infrared-reflecting layer contains four high-refractive-index layers and three low-refractive-index layers, and each of the two low-refractive-index layers is arranged between two high-refractive-index layers immediately adjacent to them. Particularly preferably, the infrared-reflecting layer consists of precisely this layer sequence. Thus, in this embodiment, the infrared-reflecting layer has the following layer sequence:

[0035] High refractive index layer - low refractive index layer - high refractive index layer - low refractive index layer - high refractive index layer - low refractive index layer.

[0036] The infrared radiation-reflecting layer preferably consists of a total of three to seven layers, with high-refractive-index layers and low-refractive-index layers being arranged in an alternating layer sequence, and the surfaces of the infrared radiation-reflecting layer, with which the layer stack of the infrared radiation-reflecting layer begins and ends, each being formed by a high-refractive-index layer. Particularly preferably, the infrared radiation-reflecting layer additionally comprises an electrically conductive layer, in particular a metallic layer. A high-refractive-index layer preferably has a refractive index greater than 1.9, particularly preferably greater than 2.1, and a low-refractive-index layer preferably has a refractive index less than 1.6, particularly preferably less than 1.5.

[0037] The high-index layers are preferably based on silicon nitride, aluminum nitride, tin-zinc oxide, silicon-aluminum nitride, silicon-zirconium nitride, silicon-titanium nitride, silicon-hafnium nitride, or titanium oxide, with silicon-zirconium nitride or, in particular, titanium oxide being particularly preferred. The low-index layers are preferably based on silicon dioxide or doped silicon oxide.

[0038] In a preferred embodiment, the thickness of the high-refractive-index layers is between 50 nm and 200 nm, particularly preferably between 50 nm and 180 nm, very particularly preferably between 80 nm and 150 nm. In a preferred embodiment, the thickness of the low-refractive-index layers is between 100 nm and 300 nm, particularly preferably between 150 nm and 300 nm, very particularly preferably between 160 nm and 280 nm.

[0039] Refractive indices in the context of the present invention are generally given relative to a wavelength of 550 nm. Methods for determining refractive indices are known to those skilled in the art. The refractive indices specified in the context of the invention can be determined, for example, by ellipsometry, whereby commercially available ellipsometers can be used. Unless otherwise stated, the specification of layer thicknesses or thicknesses refers to the geometric thickness of a layer.

[0040] The infrared radiation-reflecting layer preferably has a reflectance for infrared radiation of at least 20%, particularly preferably at least 40%, most preferably at least 60%, and in particular at least 80%. For the purposes of the invention, reflection in a specific percentage range means an average reflectance at a defined angle of incidence of, for example, 65° to the surface normal of the surface coated with the infrared radiation-reflecting layer. Infrared radiation refers to radiation with a wavelength from the infrared range, i.e., radiation with a wavelength of 780 nm to 1 mm. The infrared radiation-reflecting layer preferably has a higher reflectance in a wavelength range from 940 nm to 2000 nm, particularly preferably from 940 nm to 1400 nm, than in the other wavelength ranges.This wavelength range is particularly suitable for determining information about the vehicle occupants.

[0041] The term "reflectance" is used in accordance with the DIN EN 410 - 2011-04 standard. Reflectance always refers to the coating-side reflectance, which is measured when the coated surface of an element (e.g., a display or windshield) faces the light source and the detector.

[0042] The reflectance describes the proportion of the total incident radiation that is reflected. It is expressed as a percentage (relative to 100% incident radiation) or as a unitless number from 0 to 1 (normalized to the incident radiation). Plotted as a function of wavelength, it forms the reflection spectrum. The reflectance data refer to a reflection measurement with a light source that radiates uniformly in the considered spectral range with a normalized radiation intensity of 100%.

[0043] In a preferred embodiment, the reflective layer is arranged between the inner pane and the outer pane. Particularly preferably, the reflective layer is applied to the outer surface of the inner pane or the interior surface of the outer pane. This provides better protection for the reflective layer against corrosion and mechanical damage.

[0044] In a further embodiment of the invention, the reflective layer is arranged on a surface of the windshield closest to the vehicle occupant on the interior side. If the windshield comprises an inner pane, an outer pane, and a thermoplastic intermediate layer therebetween, the reflective layer is preferably arranged on the interior surface of the inner pane. Particularly preferably, a protective layer is applied over the entire surface of the reflective layer. By arranging the reflective layer on the interior surface of the windshield, ghost images caused by multiple reflections on the windshield are avoided. The protective layer protects the reflective layer from corrosion or mechanical damage.In a further particularly preferred embodiment of the invention, the windshield comprises, in addition to an inner pane, an outer pane, and a thermoplastic intermediate layer, a further pane, and the reflective layer is applied to a surface of the further pane. The further pane is preferably made of transparent glass, in particular soda-lime glass. However, it can also be made of other glass (e.g. borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (e.g. polymethyl methacrylate or polycarbonate). The further pane has two surfaces, wherein one surface preferably faces the interior-side surface of the inner pane and the other surface faces away from the interior-side surface of the inner pane. The further pane further has a circumferential edge.

[0045] Preferably, the additional pane coated with the reflective layer is applied to the interior surface or the exterior surface of the inner pane by means of an adhesive layer. The reflective layer is preferably arranged between the additional pane and the inner pane. The reflective layer is therefore applied to a surface of the additional pane that faces the interior surface or the exterior surface of the inner pane. This better protects the reflective layer from external influences. For example, the reflective layer cannot be scraped off without first detaching the additional pane from the inner pane. The reflective layer preferably extends over at least 80%, particularly preferably over at least 90%, of the surface of the additional pane.In particular, the reflective layer extends over the entire surface of the additional pane, with the exception of a surrounding, frame-shaped edge area located adjacent to the peripheral edge of the additional pane. This provides better protection for the reflective layer against moisture and corrosion.

[0046] The further pane preferably extends over at least 10%, particularly preferably at least 15%, in particular at least 20% of the surface of the windshield.

[0047] The additional pane is preferably thinner than both the inner pane and the outer pane. Alternatively or additionally, the additional pane preferably has a thickness of 50 μm to 1000 μm, preferably 150 μm to 500 μm, and particularly preferably 150 μm to 250 μm. This thickness achieves a good balance between material costs and mechanical stability on the inner pane. The reflective layer and the additional pane are also less aesthetically pleasing, thus improving the optical quality of the windshield compared to a greater thickness.

[0048] The reflective layer preferably has a reflectance for infrared radiation of at least 20%, particularly preferably at least 40%, most preferably at least 60% and in particular at least 80%.

[0049] The reflective layer preferably has a reflectance for visible radiation of at least 20%, particularly preferably at least 40%, most preferably at least 60%, and in particular at least 80%. Reflectance within a specific percentage range, within the meaning of the invention, means an average reflectance at a defined angle of incidence of, for example, 65° to the surface normal of the surface coated with the reflective layer. The reflective layer is intended to reflect an image projected onto the reflective layer by the image display and the infrared radiation from the radiation source. The reflective layer can be transparent, but is preferably opaque.

[0050] The reflective layer preferably comprises at least one metal selected from a group consisting of aluminum, magnesium, tin, indium, titanium, tantalum, niobium, nickel, copper, chromium, cobalt, iron, manganese, zirconium, cerium, scandium, yttrium, silver, gold, platinum, palladium, ruthenium, or mixtures thereof. Alternatively or additionally, the reflective layer comprises oxides, carbides, silicon compounds, and / or nitrides selected from a group consisting of boron-doped silicon, silicon-zirconium mixed nitride, silicon nitride, titanium oxide, silicon oxide, titanium carbide, zirconium carbide, silicon-zirconium-aluminum, or mixtures thereof. Aluminum, titanium, nickel-chromium, and / or nickel are preferably applied to the inner pane or the further pane because they can exhibit high reflection for visible light and infrared radiation.The reflective layer preferably has a thickness of 10 nm (nanometers) to 100 pm (micrometers), particularly preferably from 50 nm to 50 pm, in particular from 100 nm to 5 pm.

[0051] In a particular embodiment of the invention, the reflective layer is a coating comprising a thin-film stack, i.e., a sequence of thin individual layers. This thin-film stack contains one or more electrically conductive layers based on nickel, nickel-chromium, titanium, and / or aluminum. The electrically conductive layer based on nickel, nickel-chromium, titanium, and / or aluminum imparts basic reflective properties to the reflective layer, as well as an infrared radiation-reflecting effect and electrical conductivity. The electrically conductive layer is based on nickel, nickel-chromium, titanium, and / or aluminum. The conductive layer preferably contains at least 90 wt.% nickel, titanium, and / or aluminum, more preferably at least 99 wt.% aluminum, most preferably at least 99.9 wt.% nickel, titanium, and / or aluminum.The layer based on aluminum, nickel-chromium, nickel, and / or titanium can contain dopants, for example palladium, gold, copper, or silver. Materials based on aluminum, nickel, nickel-chromium, and / or titanium are particularly suitable for reflecting light, particularly preferably p-polarized light and infrared radiation. The use of nickel, nickel-chromium, titanium, and / or aluminum in reflective layers has proven particularly advantageous for reflecting light. Aluminum, nickel, nickel-chromium, and / or titanium are significantly cheaper than many other metals such as gold or silver. In addition, these metals have high chemical and thermomechanical resistance. The individual layers of the thin-film stack preferably have a thickness of 10 nm to 1 pm. The thin-film stack preferably has 2 to 20 individual layers, and in particular 5 to 10 individual layers.

[0052] In a particularly preferred embodiment of the invention, the reflective layer is a metal-free reflective film. The reflective layer is then preferably a film based on synergistically interacting prisms and reflective polarizers. The reflective layer preferably comprises a carrier film based on polyvinyl chloride or polyethylene terephthalate. Synergistically interacting prisms and reflective polarizers are applied to this carrier film. Such films for use with reflective layers are commercially available, for example, from the 3M Company. This avoids the need for complex metal deposition.The reflective layer is applied as a reflective film, preferably via an adhesive layer, to the interior surface of the windshield, optionally the inner pane, or is arranged within the thermoplastic intermediate layer (for example, by pressing the reflective layer into the thermoplastic intermediate layer or between two thermoplastic composite films). Alternatively, the reflective layer can also be applied as a reflective film to the other pane by means of an adhesive layer. In another particularly preferred embodiment of the invention, the reflective layer contains

[0053] • a dielectric layer stack containing TiC>2 layers and SiC>2 layers,

[0054] • a dielectric layer stack containing SiZrN layers and SiC>2 layers,

[0055] • a layer stack containing Si:B layers or SiZrAI layers,

[0056] • a layer stack containing Si layers and SiC>2 layers,

[0057] • a layer stack containing Si layers and SisN^ layers or

[0058] • a carbide layer stack containing TiC layers and / or ZrC layers or consists of one or more of these layer stacks. The described layer stacks have suitable reflection properties to achieve a homogeneous image as part of a projection arrangement and also have a sufficiently high reflectance for infrared radiation. The described layer stacks are preferably applied as a coating on the windshield, particularly preferably the inner pane, or the other pane.

[0059] Preferably, the reflective layer does not extend into a circumferential, frame-shaped edge region of the windshield (adjacent to a circumferential edge of the windshield). The uncoated circumferential, frame-shaped edge region serves to better separate the reflective layer from the external environment. The reflective layer is thereby better protected against corrosion or mechanical damage. The coating-free edge region preferably has a width of less than 20 cm, particularly preferably less than 10 cm, in particular less than 1 cm.

[0060] The windshield has a circumferential edge, which particularly preferably comprises an upper edge and a lower edge, as well as two side edges running between them, comprising a left and a right side edge. The upper edge refers to the edge which is intended to point upwards in the installed position. The lower edge refers to the edge which is intended to point downwards in the installed position. The upper edge is often also referred to as the roof edge and the lower edge as the engine edge. The windshield can have any suitable geometric shape and / or curvature. The terms “left” and “right” refer to the side or direction for a viewer looking at the installed windshield according to the invention from an interior space.In a very particularly preferred embodiment, the reflective layer extends over a maximum of 50%, particularly preferably a maximum of 40%, in particular a maximum of 20%, of the surface of the windshield. The reflective layer is particularly preferably arranged in an upper edge region of the windshield adjacent to the upper edge of the windshield and / or in a lower edge region of the windshield adjacent to the lower edge of the windshield, wherein a coating-free edge region is preferably located between the reflective layer and the upper edge and / or lower edge. Alternatively, the reflective layer can also be arranged additionally or exclusively in a lateral edge region adjacent to one or both side edges of the windshield, wherein in this case too, a coating-free edge region is preferably located between the reflective layer and the nearest side edge (left and / or right side edge).The coating-free edge region preferably has a width of less than 20 cm, particularly preferably less than 10 cm, in particular less than 1 cm. The reflective layer preferably extends in a strip-like manner from one (left) side edge to the other (right) side edge and is in particular adjacent to the lower edge of the windshield. The reflective layer preferably has a width of at least 10 cm, particularly preferably at least 20 cm, in particular at least 30 cm. This embodiment is particularly suitable since the reflective layer is not intended to be arranged in the view-through area. This enables higher reflectances for visible light and infrared radiation. This arrangement is frequently used for projection arrangements that are intended to have a high-contrast image.

[0061] According to the invention, the reflective layer is arranged on the windshield in such a way that, when viewed through the windshield by the vehicle occupant, it is completely positioned against an opaque background of the windshield. In other words: when viewed from the outside, the reflective layer is completely obscured by the opaque background when viewed through the windshield. It is understood that when viewed through the windshield from the vehicle interior, the opaque background is arranged behind the reflective layer. The opaque background can be arranged congruently with the reflective layer, or it can extend beyond the surface of the reflective layer and beyond the surface of the windshield. When viewed through the windshield, this means a viewing direction perpendicular to the main surface of the windshield.For the purposes of the invention, "complete occlusion of an element A with an element B" means that the orthonormal projection of element A to the plane of element B is arranged entirely within element B. This arrangement creates a high contrast, which makes virtual images generated by visible light more visually perceptible. It also allows the use of reflective layers with lower transparency, allowing the use of reflective layers with a higher reflectivity for infrared radiation and visible light.

[0062] The opaque background can be created by an opaque enamel (also called screen printing) or an opaque thermoplastic film, which are arranged behind the reflective layer as seen from the vehicle interior. The opaque background can also be created by a partially opaque thermoplastic film and thus be part of the thermoplastic intermediate layer. The opaque background is created in particular by a dark, preferably black, enamel, which is applied to the outer pane. The enamel is preferably applied to the interior-side surface of the outer pane. However, the enamel can also be applied to the interior-side surface of the inner pane. The opaque background is preferably created by a peripheral (frame-shaped) layer, which extends along the circumferential edge of the windshield and can be widened in the area of ​​the reflective layer.Enamels primarily serve as UV protection for the windshield assembly adhesive (e.g., for bonding to a vehicle). The opaque background preferably has a transmittance (according to ISO 9050:2003) for visible light of less than 15%, preferably less than 10%, particularly preferably less than 1%. The opaque background can also be semi-transparent, at least in sections, for example, as a dot matrix, striped matrix, or checkered matrix. Alternatively, the opaque background can also have a gradient, for example, from an opaque covering to a semi-transparent covering. The opaque background is preferably also opaque to infrared light, with a transmittance for infrared light of less than 10%, particularly preferably less than 1%.

[0063] For the purposes of the invention, “width” means the extent perpendicular to the direction of extension.

[0064] For the purposes of the invention, "opaque" means a light transmission (according to ISO 9050:2003) of less than 30%, preferably less than 20%, particularly preferably less than 5%, and in particular less than 0.1%. For the purposes of the invention, "transparent" means a light transmission (according to ISO 9050:2003) of at least 50%, preferably at least 60%, particularly preferably at least 70%, and in particular at least 80%. The light transmission (TL) values ​​refer (as is usual for automotive glazing) to illuminant type A, i.e., the visible portion of sunlight at a wavelength of 380 nm to 780 nm, essentially the visible spectrum of solar radiation. Infrared rays are understood to be rays with a wavelength greater than approximately 780 nm.

[0065] When talking about thin layers, i.e., layers with a thickness of less than 1000 nm, the following applies: if something is "based" on a material, it consists predominantly of this material, in particular, essentially of this material alongside any impurities or dopants. Unless otherwise stated, the specified layer thickness or thicknesses refer to the geometric thickness of a layer.

[0066] If something is "based" on a polymeric material, it consists predominantly of this material, i.e., at least 50%, preferably at least 60%, and especially at least 70%. It may therefore also contain other materials such as stabilizers or plasticizers.

[0067] The layer structure of the reflective layer and / or the infrared-reflecting layer is generally obtained through a sequence of deposition processes carried out by a vacuum process such as magnetic field-assisted sputtering or chemical vapor deposition (CVD). Alternatively, the layer structure of the functional layer can also be obtained by wet coating.

[0068] The thermoplastic intermediate layer is preferably formed as at least one thermoplastic composite film and is based on ethylene-vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU), or mixtures or copolymers or derivatives thereof, particularly preferably based on polyvinyl butyral (PVB), and additionally contains additives known to those skilled in the art, such as plasticizers. The thermoplastic film preferably contains at least one plasticizer.

[0069] The thermoplastic intermediate layer can be formed by one or more thermoplastic films arranged one above the other, wherein the thickness of the thermoplastic intermediate layer after lamination of the layer stack is preferably from 0.25 mm to 1 mm, typically 0.38 mm or 0.76 mm. The thermoplastic intermediate layer can also be formed from a film that is colored in certain areas and is thus opaque. The opaque background can therefore also be a component of the thermoplastic intermediate layer. The thermoplastic intermediate layer can also be formed from more than one film, with the at least two films extending over different areas of the windshield surface.

[0070] The outer pane and the inner pane are preferably made of transparent glass, in particular soda-lime glass, which is common for vehicle windows. In principle, however, the panes can also be made of other types of glass (e.g. borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (e.g. polymethyl methacrylate or polycarbonate). The thickness of the outer pane and the inner pane can vary widely. Preferably, panes with a thickness in the range of 0.8 mm to 5 mm, more preferably 1.4 mm to 2.5 mm, for example those with the standard thicknesses of 1.6 mm or 2.1 mm, are used. The outer pane, the other pane and the inner panes can independently of one another be untempered, partially tempered or tempered. If at least one of the panes is to be tempered, this can be thermal or chemical prestressing.

[0071] The outer pane, the inner pane, and the windshield can have any three-dimensional shape. Preferably, the inner pane and the outer pane have no shadow zones, allowing them to be efficiently coated by cathode sputtering. The inner pane and outer pane, and thus also the windshield, are preferably flat or slightly or strongly curved in one or more directions of the room. Any additional pane present is preferably curved in the same shape as the windshield or, if present, the inner pane in the region of the reflective layer.

[0072] In a further embodiment of the invention, the arrangement according to the invention comprises a further radiation receiver, wherein the further radiation receiver is preferably directed towards the face of the vehicle occupant such that visible light reflected from the face of the vehicle occupant can be at least partially received by the further radiation receiver. In this way, further information about the vehicle occupant can be determined. Information (for example, certain vital signs) that cannot be determined via infrared radiation can be determined via the visible spectral range. Alternatively or additionally, the visible light received by the further radiation receiver can be used for video transmission (for example, for digital communication outside or inside the vehicle).

[0073] In a preferred embodiment of the invention, a functional layer is arranged, preferably applied, on the surface of the image display facing the windshield. The functional layer is transparent to p-polarized visible light and reflective to s-polarized visible light. The functional layer preferably has a reflectance of at least 20%, particularly preferably at least 40%, very particularly preferably at least 60%, in particular at least 80% for incident s-polarized visible light. The functional layer preferably extends over at least 40%, very particularly preferably at least 80%, in particular over 100% of the surface of the image display facing the windshield.

[0074] The radiation receiver is preferably suitable for receiving visible light in addition to infrared radiation, so that s-polarized visible light reflected from the face of the vehicle occupant can be reflected via the reflective layer and then via the functional layer to the radiation receiver and received. Alternatively, a further radiation receiver is arranged relative to the functional layer and the reflective layer such that s-polarized visible light reflected from the face of the vehicle occupant can be reflected via the reflective layer and then via the functional layer to the further radiation receiver and received.For the purposes of the invention, "reflected via the reflective layer and then via the functional layer to the radiation receiver or further radiation receiver" means that the visible s-polarized light reflected from the face of the vehicle occupant at least partially strikes the reflective layer and is at least partially reflected by the reflective layer. The visible s-polarized light reflected by the reflective layer at least partially strikes the functional layer and is at least partially reflected by the functional layer. The visible s-polarized light reflected by the functional layer is at least partially reflected toward the radiation receiver or further radiation receiver, so that the radiation receiver or further radiation receiver can receive the visible s-polarized light.In this embodiment, the image display preferably emits more than 50%, particularly more than 70%, of p-polarized light, which can transmit through the functional layer. This arrangement allows information about the vehicle occupant to be obtained using the visible spectral range, while simultaneously maintaining a space-saving and aesthetically unobtrusive solution. The visible s-polarized light can be generated by another radiation source that directly or indirectly illuminates the face of the vehicle occupant. However, the visible s-polarized light can also be exclusively or additionally natural light from the external environment (solar radiation). Those skilled in the art are aware that natural light contains both p-polarized and s-polarized light components.

[0075] In a particularly preferred embodiment of the invention, a linear polarizer is arranged between the radiation receiver or the optionally further radiation receiver and the image display. The linear polarizer is transparent to visible s-polarized light but opaque to visible p-polarized light. The linear polarizer is preferably arranged between the radiation receiver and the functional layer in such a way that visible light reflected by the functional layer first strikes the linear polarizer before it can strike the radiation receiver and be received by the radiation receiver.Alternatively, the linear polarizer is arranged between the additional radiation receiver and the functional layer such that visible light reflected by the functional layer first strikes the linear polarizer before it can strike the additional radiation receiver and be received by the additional radiation receiver. This also applies to p-polarized light emitted by the image display, which would be transmitted through the functional layer and strike the radiation receiver or, if applicable, another radiation receiver if it were not first absorbed by the linear polarizer.The beam path of the visible light and p-polarized light from the functional layer to the radiation receiver or, if applicable, another radiation receiver is thus interrupted by the linear polarizer, with the s-polarized portion of the visible light being transmitted through the linear polarizer and the p-polarized light being absorbed by the linear polarizer. For technical reasons, a portion of the p-polarized light emitted by the image display is aligned in such a way that it is transmitted through the functional layer and then strikes the radiation receiver or the other radiation receiver. Due to the linear polarizer, which is arranged between the functional layer and the (other) radiation receiver, the p-polarized light emitted by the image display cannot be received by the (other) radiation receiver.The linear polarizer prevents p-polarized light emitted by the image display from hitting the radiation receiver or possibly other radiation receivers, as otherwise undesirable image overlays would result.

[0076] Preferably, a circular polarizer is arranged between the radiation receiver or the additional radiation receiver and the linear polarizer, so that the s-polarized light transmitted by the linear polarizer is first transmitted through the circular polarizer and thereby circularly polarized. The light, now circularly polarized at the circular polarizer, can then, for technical reasons, be at least partially reflected at the (additional) radiation receiver (e.g., reflected at a lens of the (additional) radiation receiver). The circularly polarized light reflected at the radiation receiver or, if applicable, the additional radiation receiver changes its direction of rotation upon reflection, thus now exhibiting a reversed direction of rotation.The circular polarizer is arranged between the linear polarizer and the radiation receiver, or optionally another radiation receiver, such that the reflected circularly polarized light is reflected toward the circular polarizer, then transmitted through the circular polarizer. The circularly polarized light, with the direction of rotation reversed at the circular polarizer, changes its polarization to p-polarization and then impinges on the linear polarizer. The linear polarizer is designed such that the p-polarized light is absorbed by the linear polarizer.S-polarized light striking the circular polarizer is therefore circularly polarized. The circularly polarized light is then reflected by the radiation receiver or, if applicable, another radiation receiver, where the circularly polarized light reverses its direction of rotation. The circularly polarized light then strikes the circular polarizer again with the opposite direction of rotation, where the circularly polarized light changes its polarization to p-polarized light. The thus p-polarized light then strikes the linear polarizer, where the p-polarized light is absorbed. The circular polarizer in conjunction with the linear polarizer can prevent the circularly polarized light reflected by the radiation receiver or another radiation receiver from entering the field of vision of the vehicle occupant via subsequent reflection by the functional layer and the reflective layer.A circular polarizer is an optical element that creates a phase shift in the transmitted light. The desired retardation is achieved by varying the thickness and orientation of the circular polarizer in the beam path. A circular polarizer has a phase shift of 90°. A circular polarizer is also called a quarter-wave plate. Suitable circular polarizers are known to those skilled in the art. Circular polarizers are made of birefringent materials. Birefringent materials have slightly different refractive indices for light.

[0077] In a preferred embodiment, the λ / 4 retardation plate is designed as a polymeric retardation plate. λ / 4 retardation plates are commercially available in the form of birefringent plastic films. In another preferred embodiment, the λ / 4 retardation plate is designed as a retardation plate made of crystalline quartz or sapphire.

[0078] The linear polarizer is preferably made of a polymer film that is stretched in one direction. The linear polarizer preferably consists of a polyvinyl alcohol (PVA) film that has been stretched during the manufacturing process and dyed with iodine. Optionally, the PVA film of the linear polarization filter can be laminated on both sides with an optically neutral cellulose triacetate carrier. Suitable linear polarizers with absorbing properties for p-polarized light are known to those skilled in the art.

[0079] Due to the indirect irradiation of the face, the radiation source, the radiation receiver, and, if applicable, the additional radiation receiver only need to be positioned with regard to suitable reflection of the infrared radiation or visible light radiation by the reflective layer and infrared-reflecting layer or functional layer. This can generally be done in such a way that they are not, or at least practically not, visible to the vehicle occupants. They can be arranged, for example, in the rear area of ​​the vehicle's dashboard. This is a further advantage of the invention.

[0080] The radiation source is preferably a thermal radiator, such as incandescent lamps and radiant heaters. The radiation source can also be a selective radiator, such as a Nernst lamp, an incandescent mantle, or a high-pressure gas discharge lamp. In particular, the radiation source is an infrared light-emitting diode (IR LED). The radiation source can also be an infrared laser, for example, a semiconductor laser, an Nd:YAG laser, or a CO2 laser. The radiation receiver is preferably a thermal detector. If infrared radiation from 800 nm to 1400 nm is used, the radiation receiver is preferably a semiconductor detector.

[0081] The polarization direction refers to the plane of incidence of the radiation on the windshield. P-polarized radiation refers to radiation whose electric field oscillates in the plane of incidence. S-polarized radiation refers to radiation whose electric field oscillates perpendicular to the plane of incidence. The plane of incidence is defined by the incidence vector and the surface normal of the windshield at the geometric center of the irradiated area.

[0082] The functional layer is preferably a reflective, linear polarization filter, in particular a broadband wire-grid polarization filter (wire-grid polarizing filter). The polarization filter is designed such that it reflects s-polarized light but transmits p-polarized light. Wire-grid polarizers are generally known to those skilled in the art. Wire-grid polarization filters contain wires, which are preferably applied to a first transparent layer, preferably made of glass, in particular quartz glass. A second transparent layer, preferably made of glass, in particular quartz glass, is applied to the wires as a protective layer. The wires are thus arranged between a first and a second protective layer. To achieve the desired polarization effect, the wires are applied parallel to one another on the first transparent layer.Electromagnetic waves (visible light), with a component of their electric field aligned parallel to the wires, induce the movement of electrons along the length of the wires. Because the electrons are free to move in this direction, the polarizer behaves much like the surface of a metal in reflecting light, and the wave is reflected back along the incident beam (minus a small amount of energy lost due to Joule heating of the wire). For electromagnetic waves with electric fields perpendicular to the wires, the electrons cannot travel very far across the width of the individual wires. Therefore, little energy is reflected, and the incident wave can penetrate the grating. In this case, the grating behaves like a dielectric material.For the purposes of the invention, this means that visible light is polarized by the birefringent properties of the wire grid polarization filter. The visible light striking the wire grid polarization filter is reflected, depending on the polarization of the light components, or it can transmit through the wire grid polarization filter. P-polarized light is transmitted to a dielectric (and can therefore transmit through the wire grid polarization filter), while s-polarized light is reflected. The wires preferably contain metal, preferably aluminum. The wires are particularly preferably made of aluminum. The wires preferably have a diameter of 100 nm to 10 pm, preferably 500 nm to 5 pm, particularly preferably 1 pm to 3 pm. The spacing between the wires is preferably less than 780 nm, particularly preferably less than 400 nm, in particular less than 100 nm.

[0083] The image display is preferably a liquid crystal (LCD) display, thin film transistor (TFT) display, light emitting diode (LED) display, organic light emitting diode (OLED) display, electroluminescent (EL) display or microLED display.

[0084] The technical terms used here from the field of HUDs are generally familiar to those skilled in the art. For a detailed description, please refer to the dissertation "Simulation-based Measurement Technology for Testing Head-Up Displays" by Alexander Neumann at the Institute of Computer Science at the Technical University of Munich (Munich: University Library of the Technical University of Munich, 2012), particularly Chapter 2, "The Head-Up Display."

[0085] The above-mentioned desired reflection characteristics of the reflection layer, the infrared radiation-reflecting layer and the functional layer are achieved in particular by the choice of materials and thicknesses as well as the structure of the individual layers or layer sequences.

[0086] The invention further extends to an assistance system, in particular a driver assistance system, with an infrared-based and optionally visible light-based monitoring function for the vehicle occupant, in particular the driver, of a vehicle, which comprises an arrangement according to the invention. The assistance system further comprises at least one actuator and / or at least one signal output device, as well as an electronic control device which is configured to determine information about the vehicle occupant based on an output signal of the radiation receiver and optionally of the further radiation receiver, and to output an electrical signal to the at least one actuator for carrying out a mechanical action and / or to the at least one signal output device for outputting an optical and / or acoustic signal based on the determined information about the vehicle occupant.

[0087] Preferably, the control device determines an actual value from the deviation between the signals emitted by the radiation source and the radiation receiver. This actual value can be compared with a target value range stored on the control device. The target value range specifies a value range in which no electrical signal is to be transmitted to the at least one actuator for executing a mechanical action and / or to the at least one signal output device for outputting an optical and / or acoustic signal. Thus, a value range that reflects, for example, an awake, attentive, and healthy vehicle occupant.The control device is configured such that, if the actual value deviates from the nominal value range, i.e., if the actual value lies outside the nominal value range, an electrical signal is transmitted to the at least one actuator for performing a mechanical action and / or to the at least one signal output device for outputting an optical and / or acoustic signal. The nominal value range is preferably obtained through a prior calibration and stored digitally on the control device.

[0088] Furthermore, the invention extends to a method for monitoring a vehicle occupant, in particular a driver, in which an assistance system according to the invention is provided. The method comprises at least the following steps:

[0089] (a) Infrared radiation is emitted from the radiation source and reflected in the following order via the infrared radiation reflecting layer, the reflection layer, the face of the vehicle occupant, the reflection layer and the infrared radiation reflecting layer to the radiation receiver.

[0090] (b) The infrared radiation is received by the radiation receiver,

[0091] (c) Information about the vehicle occupant is determined by the electronic control device on the basis of the infrared radiation received by the radiation receiver.

[0092] (d) An action is carried out by the actuator based on the information and / or an optical and / or acoustic signal is output by the signal output device.

[0093] It is understood that the method proceeds in the order (a), (b), (c), and finally (d). In a preferred embodiment of the method according to the invention, in method step (a), s-polarized visible light is reflected from the face of the vehicle occupant via the reflective layer and then via the functional layer to the radiation receiver or, if appropriate, to the additional radiation receiver. In method step (b), the s-polarized visible light is received by the radiation receiver or, if appropriate, the additional radiation receiver.

[0094] In method step (c), further information about the vehicle occupant is determined by the electronic control device on the basis of the visible s-polarized light received by the radiation receiver or, if applicable, the further radiation receiver.

[0095] In method step (d), an action is carried out by the actuator on the basis of the further information and / or an optical and / or acoustic signal is output by the signal output device.

[0096] Preferably, in method step (c), an actual value is determined from the deviation between the signals emitted by the radiation source and the radiation receiver using the control device. This actual value is compared with the target value range stored on the control device. In method step (d), if the actual value deviates from the target value range, an action is performed by the actuator based on the detected deviation and / or an optical and / or acoustic signal is output by the signal output device.

[0097] In a further preferred embodiment, in method step (c), a further actual value is determined from the received signal of the further radiation source using the control device. This further actual value is compared with a further target value range stored on the control device. In method step (d), if the further actual value deviates from the further target value range, an action is performed by the actuator based on the determined deviation and / or an optical and / or acoustic signal is output by the signal output device.

[0098] The preferred embodiments of the arrangement according to the invention described above also apply accordingly to the method according to the invention. Furthermore, the invention extends to the use of the arrangement according to the invention in an assistance system, in particular a driver assistance system, of a vehicle, in particular a motor vehicle, for traffic on land, water, or in the air.

[0099] The various embodiments of the invention can be implemented individually or in any combination. In particular, the features mentioned above and explained below can be used not only in the specified combinations, but also in other combinations or on their own, without departing from the scope of the present invention.

[0100] The invention is explained in more detail below using exemplary embodiments, with reference to the accompanying figures. The figures are schematic representations and not to scale. The figures do not limit the invention in any way. They show:

[0101] Fig. 1 is a schematic view of the front part of a vehicle with a driver with an arrangement and driver assistance system for infrared-based monitoring of the driver,

[0102] Fig. 2 shows the arrangement from Fig. 1 in an enlarged cross-section,

[0103] Fig. 3 shows an embodiment of an arrangement according to the invention in cross section,

[0104] Fig. 3A is a plan view of the windshield of the embodiment of Fig.3 and

[0105] Fig. 4-5 further embodiments of the arrangement according to the invention shown in cross section.

[0106] Fig. 1 shows a schematic view of the front part of a vehicle 2 with a vehicle occupant who is the driver of the vehicle 2, with an arrangement 1 and driver assistance system 100 for infrared-based monitoring of the vehicle occupant. The arrangement 1 is shown enlarged in Fig. 2. The arrangement 1 comprises a windshield 5 of a vehicle 2, which comprises an outer pane 12 and an inner pane 13, which are firmly connected to one another by a thermoplastic intermediate layer 14, and has a reflective layer 7 (see Fig. 2).

[0107] The windshield 5 has an upper edge and a lower edge, as well as two side edges connecting the upper and lower edges (all together forming a circumferential edge of the windshield 5). The lower edge (also called the engine edge) of the windshield 5 refers to the edge that faces the ground in the installed position. The upper edge (also called the roof edge) of the windshield 5 refers to the edge that faces the vehicle roof in the installed position in the vehicle 2.

[0108] The outer pane 12 and the inner pane 13 are each made of glass, preferably thermally toughened soda-lime glass, and are transparent to visible light 11. The outer pane 12 has a thickness of 2.1 mm, for example, and the inner pane 13 has a thickness of 1.5 mm, for example. The thermoplastic intermediate layer 14 comprises a thermoplastic material, preferably polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), and / or polyethylene terephthalate (PET), and is, for example, 0.8 mm thick.

[0109] The reflective layer 7 is, for example, a dielectric layer stack containing TiO2 layers and SiO2 layers. The reflective layer 7 is applied, for example, by magnetron sputtering to the outer surface III of the inner pane 13. The reflective layer 7 extends over the entire surface III of the inner pane 13 with the exception of a circumferential, frame-shaped edge region, which is arranged adjacent to the circumferential edge of the windshield 5.

[0110] The arrangement 1 also comprises an image display 6 with an infrared radiation-reflecting layer 8. The image display 6 is designed to emit a virtual image onto the reflective layer 7 using visible light 11. The virtual image is reflected by the reflective layer 7 toward the face 9 of the vehicle occupant (indicated by bold arrows in Fig. 2), so that the vehicle occupant can visually perceive the virtual image in the form of visible light 11. The reflective layer 7 on the inner window 13 together with the image display 6 thus form a head-up display. The image display 6 is, for example, a light-emitting diode (LED) display. The infrared radiation-reflecting layer 8 is applied flatly to a surface A of the image display 6 facing the windshield 5.The surface A of the image display 6 facing the windshield 5 is simultaneously the surface of the image display 6 through which the visible light 11 of the image display 6 can be emitted toward the reflective layer 7. The visible light 11 of the image display 6 is, for example, exclusively p-polarized light in order to avoid ghost images upon reflection from the windshield 5.

[0111] The arrangement 1 further comprises a radiation source 3 and a radiation receiver 4, which, as shown schematically in Fig. 1 and Fig. 2, are arranged next to one another, but can also be installed in one assembly. Both the radiation source 3 and the radiation receiver 4 are installed here, for example, in the rear area of ​​a dashboard (closer to the windshield 5 than to the vehicle occupant) of the vehicle 2, where they are practically invisible to vehicle occupants. The radiation source 3 is positioned and aligned such that the infrared radiation 10 emitted by the radiation source 3 strikes the infrared radiation-reflecting layer 8 and is reflected there by the infrared radiation-reflecting layer 8 to the reflective layer 7. The infrared radiation 10 emanating from the infrared radiation-reflecting layer 8 is reflected by the reflective layer 7 onto the face 9 of the vehicle occupant.The infrared radiation 10, hereinafter referred to as infrared reflection radiation 15 for ease of tracking, is reflected from the face 9 of the vehicle occupant toward the reflection layer 7. The infrared reflection radiation 15 is reflected by the reflection layer 7 onto the infrared radiation-reflecting layer e. The infrared reflection radiation 15 is reflected by the infrared radiation-reflecting layer 8 onto the radiation receiver 4. The radiation receiver 4 is directed toward the surface A of the image display 6 coated with the infrared radiation-reflecting layer e and can receive the infrared reflection radiation 15 reflected by the infrared radiation-reflecting layer 8.The infrared radiation 10, which is reflected by the reflective layer 7 onto the face 9 of the vehicle occupant, preferably strikes the face 9 of the vehicle occupant essentially perpendicularly, assuming a normal seating position of the vehicle occupant in the vehicle 2. The infrared radiation 10 is preferably reflected back essentially perpendicularly as infrared reflected radiation 15 from the face 9 of the vehicle occupant to the reflective layer 7. In this way, particularly suitable and extensive information about the condition of the vehicle occupant can be obtained. The infrared radiation-reflecting layer 8 is, for example, a layer stack with two high-refractive-index layers and one low-refractive-index layer. The high-refractive-index layers are constructed, for example, based on silicon nitride. The low-refractive-index layer is constructed, for example, based on silicon oxide.

[0112] The radiation source 3 is, for example, an infrared light-emitting diode (IR LED). The radiation receiver 4 is, for example, a thermal detector.

[0113] Based on the driver data acquired in this way, information about the vehicle occupant, in this case the driver, can be determined in a particularly reliable manner. Characteristics of the face 9, such as facial expressions and eye movements, can thus be determined particularly well and reliably. Furthermore, the radiation source 3, image display 6, and radiation receiver 4 can be arranged in the rear area of ​​the dashboard, so that they can be easily integrated into the interior of the vehicle 2 and do not disrupt the design of the vehicle interior. By integrating the projection arrangement, i.e. the head-up display with reflective layer 7 and image display 6, into the arrangement 1 for monitoring the vehicle occupant, the limited space available in a vehicle 2 can be optimally utilized.

[0114] Reference is now made to Fig. 3 and Fig. 3A, which show an enlarged cross-sectional view and a plan view of the windshield 5 from a vehicle interior. Fig. 3 and Fig. 3A relate to an embodiment of the invention. The cross-sectional view of the windshield 5 in Fig. 3 corresponds to the section line A-A', which is indicated in Fig. 3A. The variants shown in Fig. 3 and Fig. 3A essentially correspond to the variant from Fig. 1 and Fig. 2, so that only the differences will be discussed here and otherwise the description of Fig. 1 and Fig.

[0115] 2 is referred to.

[0116] Unlike the variant from Fig. 1 and Fig. 2, the reflection layer 7 in Fig.

[0117] 3 and Fig. 3A, the reflective layer 7 is not applied over the entire outer surface III of the inner pane 13, but is arranged only in a lower edge region of the windshield 5. The reflective layer 7 extends in a strip-like manner with a width of approximately 15 to 20 cm from the left side edge of the windshield 5 to the right side edge of the windshield 5. Between the reflective layer 7 and the left and right side edges of the windshield 5 there is an area approximately 5 cm wide that is not coated with the reflective layer 7. Between the reflective layer 7 and the lower edge of the windshield 5 there is also an area approximately 5 cm wide that is not coated with the reflective layer 7. The reflective layer 7 is therefore arranged outside a region of the windshield 5 intended for transparency. The reflective layer 7 is also arranged against an opaque background 19 when viewed through the windshield 5 from the vehicle interior.This means at the same time that the reflection layer 7 is completely hidden by the opaque background 19 when viewed through the windshield 5 from the outside environment.

[0118] The opaque background 19 is designed, for example, in the form of a black screen print applied to the interior-side surface II of the outer pane 12. The screen print extends in a frame-like manner along the circumferential edge of the windshield 5 (see Fig. 3A). The screen print is applied in a widened manner along the lower edge of the windshield 5, so that the reflective layer 7 is arranged completely in front of the screen print, i.e., the opaque background 19. The screen print serves, among other things, as UV protection for the assembly adhesive of the windshield 5 (for example, for gluing it into the vehicle 2).

[0119] By arranging the reflective layer 7 outside the area of ​​the windshield 5 intended for viewing, a reflective layer 7 with a higher reflectance for visible light 11 can be used, whereby the increase in the reflectance for visible light 11 often automatically also results in an increase in the reflectance for infrared radiation 10. This allows the visible light 11 emitted by the image display 6 onto the reflective layer 7 to be better visually perceived by the vehicle occupant, and at the same time, the condition of the vehicle occupant can be better determined using infrared radiation 10.

[0120] Reference is now made to Fig. 4 and Fig. 5, which show enlarged cross-sectional views of the arrangement 1. Fig. 4 and Fig. 5 relate to further embodiments of the invention. The variants shown in Fig. 4 and Fig. 5 essentially correspond to the variant from Fig. 3 and Fig. 3A, so that only the differences will be discussed here and otherwise reference is made to the description of Fig. 3 and Fig. 3A. Unlike the variant from Fig. 3 and Fig. 3A, the opaque background 19 in Fig. 4 is not formed as a black screen print, but rather a partially colored thermoplastic intermediate layer 14. The thermoplastic intermediate layer 14 is colored in certain areas, with the opaque coloring occurring in a frame-like manner along the circumferential edge of the windshield 5.The colored area of ​​the thermoplastic intermediate layer 14 is widened along the lower edge of the windshield 5, so that the reflection layer 7 is arranged completely in front of the colored area of ​​the thermoplastic intermediate layer 14, i.e. the opaque background 19.

[0121] The windshield 5 has a further pane 16, wherein the further pane 16 has an outer surface V facing the inner pane 13 and an interior-side surface VI facing away from the inner pane 13. The reflective layer 7 is applied over the entire surface V of the further pane 16 instead of to the inner pane 13. The further pane 16 is made of soda-lime glass, for example, and has a thickness of 1 mm, for example. The further pane 16 does not extend over the entire surface of the windshield 5, but has the same dimensions as the reflective layer 7. The further pane 16 is arranged, for example, by means of an adhesive layer (not shown here), on the interior-side surface IV of the inner pane 13. The adhesive layer is arranged between the reflective layer 7 and the inner pane 13 and connects (glues) them together.

[0122] In the embodiment of the arrangement 1 according to the invention shown in Fig. 5, in addition to the radiation receiver 4 for infrared radiation 10, a further radiation receiver 17 is directed onto the surface A of the image display 6 facing the windshield 5. Also arranged on the surface A of the image display 6 facing the windshield 5 is a functional layer 18 which has a light transmittance for p-polarized visible light of, for example, at least 70% and a reflectance for s-polarized visible light 20 of, for example, 70%. The functional layer 18 is, for example, a broadband wire-grid polarization filter.

[0123] The windshield 5 also has a further pane 16, wherein the further pane 16 has an outer surface V facing the inner pane 13 and an interior-side surface VI facing away from the inner pane 13. The reflective layer 7 is applied over the entire surface V of the outer pane 16 instead of to the inner pane 13. The dimensions of the further pane 16, the arrangement on the windshield 5, and the bonding of the further pane 16 to the inner pane 13 are equivalent to those of the embodiment of Fig. 4.

[0124] The additional radiation receiver 17, the image display 6 with the functional layer 18, and the reflective layer 7 are arranged relative to one another such that s-polarized light 20 reflected from the face 9 of the vehicle occupant, which impinges on the reflective layer 7, is at least partially reflected by the reflective layer 7 to the functional layer 18. The visible s-polarized light 20, which impinges on the functional layer 18, is reflected by the functional layer 18 toward the additional radiation receiver 17 and is received by the additional radiation receiver 17. The image display 6 emits exclusively visible p-polarized light, at least 70% of which is transmitted through the functional layer 18. The visual perception of the virtual image projected onto the reflective layer 7 is thus hardly or not at all impaired.

[0125] Between the further radiation receiver 17 and the functional layer 18, for example, a linear polarizer and a circular polarizer can be arranged (not shown here). The linear polarizer and circular polarizer are arranged, for example, such that visible light, comprising portions of s-polarized light 20 and portions of p-polarized light, which is reflected by the functional layer 18 in the direction of the further radiation receiver 17, first strikes the linear polarizer, with p-polarized light being absorbed and s-polarized light 20 being transmitted through the linear polarizer. The s-polarized light 20 then transmits through the circular polarizer and is circularly polarized in the process, finally striking the further radiation receiver, which at least partially receives the circularly polarized light.It is possible that a portion of the circularly polarized light incident on the additional radiation receiver 17 is reflected with the opposite direction of rotation by the additional radiation receiver 17, for example, by the lens for receiving the s-polarized light 20. The circularly polarized light reflected in this way, now with the opposite direction of rotation, initially strikes the circular polarizer again, where it changes its polarization to p-polarization upon transmission through the circular polarizer. The now p-polarized light then strikes the linear polarizer and is absorbed by it.The linear polarizer and circular polarizer are, for example, also arranged such that a technically conditioned p-polarized residual light (scattered light), which is emitted by the image display 6 and which is technically unavoidably directed towards the further radiation receiver, is first transmitted through the functional layer 18 and then strikes the linear polarizer, whereby the p-polarized residual light is absorbed.

[0126] By means of the additional radiation receiver 17, further information about the vehicle occupant can be collected. This information can contribute to an improvement of the assistance system 100. By arranging the reflective layer 7 in front of the opaque background 19, a reflective layer 7 with a higher reflectance for s-polarized visible light 20 can be used. This allows more effective information about the condition of the vehicle occupant to be obtained. The additional radiation receiver 17 can also be a camera that continuously records the face 9 of the vehicle occupant. The video continuously recorded in this way can be used, for example, for communication with other vehicle occupants or persons outside the vehicle 2. A video of a conversation participant could be projected onto the reflective layer 7 using the image display 6, so that the vehicle occupant and the conversation participant can see each other in real time.

[0127] List of reference symbols

[0128] 1 arrangement

[0129] 2 vehicles

[0130] 3 Radiation source

[0131] 4 radiation receivers

[0132] 5 Windshield

[0133] 6 Image display

[0134] 7 Reflective layer

[0135] 8 Infrared radiation-reflecting layer

[0136] 9 Face of the vehicle occupant

[0137] 10 Infrared radiation

[0138] 11 visible light

[0139] 12 Outer pane

[0140] 13 Inner pane

[0141] 14 thermoplastic intermediate layer

[0142] 15 infrared reflected radiation

[0143] 16 more discs

[0144] 17 additional radiation receivers

[0145] 18 Functional layer

[0146] 19 opaque background

[0147] 20 s-polarized light

[0148] 100 assistance system

[0149] I outside surface of the outer pane 12

[0150] II Interior surface of the outer pane 12

[0151] III outer surface of the inner pane 13

[0152] IV interior surface of inner pane 13

[0153] V outer surface of the further pane 16

[0154] VI Interior surface of the further pane 16

[0155] A surface of the image display 6 facing the windshield 5

[0156] AA' section line

Claims

Patent claims 1. Arrangement (1) for an assistance system (100) of a vehicle (2), comprising - a radiation source (3) for emitting infrared radiation (10), - a radiation receiver (4) for receiving infrared radiation (10), - a windscreen (5) with a reflective layer (7) and - an image display (6) for emitting visible light (11) with an infrared radiation-reflecting layer (8), wherein the image display (6) is arranged relative to the reflection layer (7) such that the visible light (11) emitted by the image display (6) can be reflected by the reflection layer (7) toward a face (9) of a vehicle occupant, and wherein the radiation source (3) and the radiation receiver (4) are arranged relative to the infrared radiation-reflecting layer (8) such that the infrared radiation (10) emitted by the radiation source (3) can be reflected in the following order via the infrared radiation-reflecting layer (8), the reflection layer (7), the face (9) of the vehicle occupant, the reflection layer (7) and the infrared radiation-reflecting layer (8) toward the radiation receiver (4) and can be received by the radiation receiver (4), wherein the reflection layer (7), as seen from the vehicle occupant,when viewed through the windscreen (5) is arranged entirely against an opaque background (19) of the windscreen (5).

2. Arrangement (1) according to claim 1, wherein the infrared radiation-reflecting layer (8) is arranged on a surface (A) of the image display (6) facing the windshield (5) and is transparent to visible light (11).

3. Arrangement (1) according to claim 1 or 2, wherein the windshield (5) comprises an outer pane (12), a thermoplastic intermediate layer (14) and an inner pane (13) and the reflection layer (7) is arranged between the inner pane (13) and the outer pane (12).

4. Arrangement (1) according to claim 1 or 2, wherein the reflection layer (7) is arranged on an interior-side surface (IV) of the windshield (5) closest to the vehicle occupant.

5. Arrangement (1) according to one of claims 1 to 4, wherein the infrared radiation reflecting layer (8) consists of an alternating layer sequence of high refractive index Layers with a refractive index greater than 1.9 and low-index layers with a refractive index less than 1.

6.

6. Arrangement (1) according to claim 5, wherein the high-index layers are formed on the basis of silicon nitride, aluminum nitride, tin-zinc oxide, silicon zirconium nitride, silicon aluminum nitride, silicon titanium nitride, silicon hafnium nitride or titanium oxide, preferably on the basis of silicon zirconium nitride or titanium oxide.

7. Arrangement (1) according to claim 5 or 6, wherein the low-refractive-index layers are formed on the basis of silicon dioxide or doped silicon oxide.

8. Arrangement (1) according to one of claims 1 to 7, wherein the reflection layer (7) reflects visible light (11) and infrared radiation (10) to at least 40%, preferably to at least 60% and particularly preferably to at least 80%.

9. Arrangement (1) according to one of claims 1 to 8, further comprising a further radiation receiver (17) for receiving visible s-polarized light (20) and preferably a linear polarizer which is arranged between the further radiation receiver (17) and the image display (6).

10. Arrangement (1) according to claim 9, wherein the image display (6) has a functional layer (18) which is transparent to p-polarized light (20) and reflective to s-polarized light (20).

11. Arrangement (1) according to claim 10, wherein the further radiation receiver (17) and the functional layer (18) are arranged relative to one another such that an s-polarized visible light (20) reflected from the face (9) of the vehicle occupant can be reflected and received via the reflection layer (7) and then via the functional layer (18) to the further radiation receiver (17).

12. Assistance system (100) with monitoring function for a vehicle occupant of a vehicle (2), comprising - an arrangement (1) according to one of claims 1 to 11, - at least one actuator and / or at least one signal output device, - an electronic control device which is designed to determine information about the vehicle occupant on the basis of an output signal of the radiation receiver (4) and to determine, on the basis of the determined information, to output an electrical signal to the at least one actuator for carrying out a mechanical action and / or to the at least one signal output device for outputting an optical and / or acoustic signal.

13. A method for monitoring a vehicle occupant of a vehicle (2), in which an assistance system (100) according to claim 12 is provided, wherein a) infrared radiation (10) is emitted by the radiation source (3) and is reflected in the following order via the infrared radiation-reflecting layer (8), the reflection layer (7), the face (9) of the vehicle occupant, the reflection layer (7) and the infrared radiation-reflecting layer (8) to the radiation receiver (4), b) the infrared radiation (10) is received by the radiation receiver (4), c) information about the vehicle occupant is determined by the electronic control device and d) an action based on the information is carried out by the actuator and / or an optical and / or acoustic signal is output by the signal output device.

14. Use of the arrangement (1) according to one of claims 1 to 11 in an assistance system (100) with infrared-based monitoring of a vehicle occupant of a vehicle (2) for traffic on land, on water or in the air.

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