Device for auxiliary system of vehicle

Abstract

The invention relates to a device (1) for an auxiliary 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 windshield (5) having a reflective layer (7), and an image display (6) for outputting visible light (11) and having a layer (8) reflecting infrared radiation, wherein the image display (6) is arranged relative to the reflecting layer (7) in such a way that visible light (11) output by the image display (6) can be reflected by the reflecting layer (7) towards the face (9) of the vehicle occupant, and wherein the radiation source (3) and the radiation receiver (4) are arranged relative to the infrared radiation reflecting layer (8), the radiation receiver (4) is arranged in such a way that the infrared radiation (10) output by the radiation source (3) is reflected towards the radiation receiver (4) in the following order via the infrared radiation reflecting layer (8), the reflecting layer (7), the face (9) of the vehicle occupant, the reflecting layer (7) and the infrared radiation reflecting layer (8) and can be received by the radiation receiver (4), the reflective layer (7) is arranged entirely in front of the opaque background (19) of the windshield (5).

Description

[0001] The present invention relates to a device for an auxiliary system of a vehicle. Furthermore, the present invention relates to an auxiliary system for a vehicle having such a device, to the use of such a device in an auxiliary system of a vehicle, and to a method for monitoring vehicle occupants of a vehicle by means of such an auxiliary system.

[0002] Modern vehicles are usually equipped with electronic auxiliary systems, in particular driver assistance systems, which support the driver in guiding the vehicle, for example by automatically applying the brakes if there is a risk of collision or by automatically staying in the lane if the vehicle leaves the lane. Such driver assistance systems have proven to be very successful in practice, especially if they have a monitoring function for the driver, for example, identifying driver fatigue at an early stage, but also identifying distractions from safe operation, such as caused by using a mobile phone. However, they are increasingly used not only to monitor the driver but also to monitor other vehicle occupants. For example, checking the overall health of the occupants.

[0003] For this purpose, it is known to use infrared radiation to scan the faces of vehicle occupants, and in particular their eyes, which is invisible to the naked eye and thus does not disturb the driver and other vehicle occupants. Thereby, algorithms can be used to capture the driver's gaze direction and gaze duration, which can indicate fatigue, for example, if the gaze duration in a particular direction is unusually long (staring). On the other hand, if the driver's line of sight is shifted away from the driving direction too frequently, this may indicate distraction. Facial expressions can also be recognized, which can also give an indication of the state of the vehicle occupants.

[0004] EP 1 333 410 A2 discloses a device for eye tracking of a vehicle driver.

[0005] DE 10 2014 115 958 A1 discloses a system for monitoring a vehicle driver, including an infrared flash lamp for irradiating an infrared light beam onto the driver; an infrared camera for capturing an image (including reflections) irradiated by the light beam, and a reflective infrared film incorporated into the windshield of the vehicle.

[0006] Modern driver assistance systems operate with infrared-based monitoring functions that employ wavelengths in the range of approximately 1 μm (micrometer) to 2 μm, in particular using infrared radiation with a wavelength of 940 nm or using infrared radiation with a wavelength of 1400 nm or using infrared radiation with a wavelength of 1550 nm. In order to be able to obtain even more information about vehicle occupants, information is increasingly collected with the aid of monitoring functions operating in the visible light range.

[0007] CN217037318U discloses a driver assistance system that uses a visible light camera in addition to an IR camera. WO2022224173A1 discloses a gaze detection system for a driver, in which a visible light camera can be used as an alternative to an IR camera.

[0008] JP201912889 and US2016150218A1 disclose a windshield with a HUD device. To better align the HUD device for a vehicle occupant, the HUD device can be connected to an infrared camera and an infrared radiation source, which are designed to detect the head position of the vehicle occupant. Visible light and infrared radiation from the image display of the HUD device are reflected on the glass of the windshield.

[0009] FR3073053A1 discloses a HUD device and a fatigue detection device that includes an infrared camera and an infrared radiation source. The fatigue detection system can be used to check the condition of a vehicle occupant.

[0010] The disadvantage of such solutions is the low reflectivity on the glass, as visibility through the glass pane must be maintained in HUD applications.

[0011] If the vehicle also has a projection device, such as a HUD display or a high-contrast HUD display, it is more difficult for the vehicle assistance system to adapt to the geometry of the vehicle. In such cases, the sensors and cameras for the assistance system often have to share the limited space in the vehicle with the image display intended for the projection device.

[0012] The object of the present invention is to provide an improved device for an assistance system of a vehicle, the assistance system of the vehicle having an infrared-based monitoring function for the driver and / or vehicle occupants, the device being able to simply and reliably obtain information about the driver and / or vehicle occupants. In particular, the task is to provide an improved device that efficiently utilizes the geometry and equipment of a modern vehicle in a space-saving manner.

[0013] These and other objects are achieved by the device, assistance system, and method according to the independent claims. Preferred embodiments can be seen in the dependent claims.

[0014] The invention relates to a device for an auxiliary system of a vehicle, in particular a motor vehicle, the device having a monitoring function for at least one vehicle occupant of the vehicle based on infrared radiation. The device is particularly suitable for a driver assistance system for monitoring a driver based on infrared radiation. The device comprises a radiation source for emitting infrared radiation and a radiation receiver for receiving infrared radiation. The device further comprises a windshield preferably consisting of an outer glass plate and an inner glass plate, the outer glass plate and the inner glass plate being connected to each other by a thermoplastic interlayer. The windshield is thus preferably a laminated glass plate. The windshield has a reflective layer. The device further comprises an image display having an infrared radiation reflective layer, the image display being intended to emit visible light. According to the invention, the reflective layer is arranged on the windshield in such a way that, as seen by the vehicle occupant, when looking through the windshield, it is entirely arranged on an opaque background against the windshield.

[0015] The radiation source is arranged in such a way that the infrared radiation emitted by the radiation source is directed towards the infrared radiation reflective layer and is reflected by the infrared radiation reflective layer onto the reflective layer and can be reflected by the reflective layer onto the face of the vehicle occupant.

[0016] The infrared radiation emitted by the radiation source thus first strikes the infrared radiation reflective layer of the image display, is reflected by the infrared radiation reflective layer onto the reflective layer and then in turn is reflected by the reflective layer onto the face of the vehicle occupant. The infrared radiation is reflected back from the face of the vehicle occupant to the reflective layer, the infrared radiation is then reflected by the reflective layer onto the infrared radiation reflective layer and finally is reflected by the infrared radiation reflective layer to the radiation receiver.

[0017] For the sake of convenience of reference, the infrared radiation emitted by the radiation source and reflected by the infrared radiation reflecting layer is referred to as the first reflected radiation. After being reflected by the infrared radiation reflecting layer, the first reflected radiation irradiates on the reflecting layer and can be reflected by the reflecting layer onto the face of the vehicle occupant. For the sake of convenience of reference, the infrared radiation emitted from the infrared radiation reflecting layer and reflected by the reflecting layer is referred to as the second reflected radiation. After being reflected by the reflecting layer, the second reflected radiation irradiates on the face of the vehicle occupant and is then reflected by the face of the vehicle occupant. For the sake of convenience of reference, the infrared radiation emitted by the reflecting layer and reflected by the face of the vehicle occupant is referred to as the third reflected radiation. After being reflected by the face of the vehicle occupant, the third reflected radiation irradiates on the reflecting layer and is then reflected by the reflecting layer. For the sake of convenience of reference, the infrared radiation emitted from the face of the vehicle occupant and reflected by the reflecting layer is referred to as the fourth reflected radiation. After being reflected by the reflecting layer, the fourth reflected radiation irradiates on the infrared radiation reflecting layer and is then reflected by the infrared radiation reflecting layer. For the sake of convenience of reference, the infrared radiation emitted from the reflecting layer and reflected by the infrared radiation reflecting layer is referred to as the fifth reflected radiation. In this case, the radiation receiver is arranged in such a way that the fifth reflected radiation reflected by the infrared radiation reflecting layer can be reflected to the radiation receiver and can be received by the radiation receiver.

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

[0019] The image display is arranged relative to the reflecting layer in such a way that the visible light emitted by the image display can be reflected by the reflecting layer, wherein the reflected visible light can be reflected onto the face of the vehicle occupant and can be visually perceived by the vehicle occupant. Due to the opaque background, a highly reflective reflecting layer can be used, which allows highly reflective infrared light and visible light. Due to the high contrast, the visible light is easily perceived by the vehicle occupant. This provides a projection device with high contrast in the classical sense, which is significantly different from a head-up display (HUD). The image display is thus designed to project a virtual image that can be visually perceived by the vehicle member onto the reflecting layer.

[0020] The windshield is provided to separate the interior from the external environment in the window opening of the vehicle.

[0021] A major advantage of the present invention is that, due to the combination of the opaque background and the reflective layer, a highly reflective reflective layer can be used for both visible light and infrared light because visible light cannot escape from the vehicle. It is known to those skilled in the art that the infrared light reflection effect is usually associated with the reflectivity for the visible radiation range. Another advantage is the space-saving arrangement of the infrared radiation reflective layer, the radiation source, and the radiation receiver, which can thus be placed in the vehicle. These elements can be combined with the projection device comprising the reflective layer and the image display in such a way that they do not interfere with the interior of the vehicle. At the same time, they can effectively collect information about the vehicle occupants. The device according to the invention of the infrared radiation reflective layer on the image display simplifies the positioning of the radiation receiver and the radiation source. They do not have to be directly aligned with the vehicle occupants (which may be aesthetically disturbing), but can capture the line of sight of the vehicle occupants via the infrared radiation reflective layer and the reflective layer. The detection of the vehicle occupants' faces is also improved because the occupants can directly see the image projected onto the reflective layer by the image display and can simultaneously obtain information about the vehicle occupants with the help of the radiation source and the radiation receiver. Another advantage of the device according to the invention is that the infrared radiation can be irradiated onto the faces of the vehicle occupants from the front due to reflection on the reflective layer. The radiation reflected onto the faces of the vehicle occupants can thus contain a radiation component that falls vertically onto the faces of the vehicle occupants. Similarly, the infrared radiation reflected in a corresponding manner from the faces can be received; this infrared radiation contains a radiation component reflected vertically from the faces of the vehicle occupants.

[0022] The windshield has an inner side surface intended to face the interior of the vehicle. In addition, the windshield has an outer side surface intended to face the external environment. In the preferred case where the windshield comprises an outer glass plate and an inner glass plate, these each have an outer side surface and an inner side surface, and a peripheral side edge extending therebetween. In the context of the present invention, the term "outer side surface" refers to the main surface intended to face the external environment in the installation position, where the outer side surface of the outer surface is simultaneously the outer side surface of the windshield. In the context of the present invention, the inner side surface refers to the main surface intended to face the interior in the installation position, where the inner side surface of the inner glass plate is simultaneously the inner side surface of the windshield. The inner side surface of the outer glass plate and the outer side surface of the inner glass plate face each other and are joined to each other by a thermoplastic interlayer. In the context of the present invention, the term "inner glass plate" refers to the glass plate of the windshield facing the interior of the vehicle. The outer glass plate refers to the glass plate facing the external environment.

[0023] The outer side surface of the outer glass plate is called side I. The inner side surface of the outer glass plate is called side II. The outer side surface of the inner glass plate is called side III. The inner side surface of the inner glass plate is called side IV.

[0024] For the purposes of the present invention, the expression "can be reflected" means that it is also possible to reflect only a part of the incident radiation. This also means that the incident radiation can be completely reflected.

[0025] In a preferred embodiment of the present invention, the infrared radiation reflecting layer is arranged on the surface of the image display facing the windshield and is visible light transmissive. The surface of the image display facing the windshield is preferably at the same time the surface of the image display intended to emit visible light onto the reflecting layer and technically suitable for this purpose. Particularly preferably, the infrared radiation reflecting layer extends over at least 40%, very particularly preferably at least 80%, especially 100% of the surface of the image display facing the windshield.

[0026] The infrared radiation 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 radiation 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 reflecting layer.

[0027] The infrared radiation reflecting layer preferably contains at least one metal selected from aluminum, tin, titanium, niobium, copper, chromium, cobalt, iron, manganese, nickel-chrome, zirconium, silver, gold, platinum and palladium or mixtures thereof. The thickness of the metal 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 in terms of infrared radiation reflection effect while maintaining high optical transparency.

[0028] In an advantageous embodiment, the infrared radiation reflecting layer contains at least one transparent conductive oxide (TCO). Such layers are corrosion resistant and can be used on exposed surfaces. The infrared radiation reflecting layer preferably contains indium tin oxide (ITO), which has proven to be particularly useful. However, 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 conductive layer is from 50 nm to 1 mm, particularly preferably from 70 nm to 1000 nm, particularly preferably from 80 nm to 500 nm.

[0029] In a particularly preferred embodiment, the infrared radiation reflecting layer contains an alternating layer sequence of high refractive index layers and low refractive index layers. Particularly preferably, the infrared radiation reflecting layer 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 starts with a high refractive index layer and ends with a high refractive index layer. The surfaces of the infrared radiation reflecting layer at which the layer stack begins and ends are thus each formed by a high refractive index layer (the remaining one or more layers are thus located between two high refractive index layers). The alternating layer structure enables a uniform and sufficiently high degree of reflection of infrared radiation to be obtained.

[0030] In the case of an alternating layer sequence of high refractive index layers and low refractive index layers, the layer adjacent to a low refractive index layer is a high refractive index layer, and the layers adjacent to a high refractive index layer are low refractive index layers.

[0031] In another preferred embodiment, the infrared radiation 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 adjacent thereto. Particularly preferably, the infrared radiation reflecting layer precisely consists of such a layer sequence. Thus, in this embodiment, the infrared radiation reflecting layer has the following layer sequence:

[0032] High refractive index layer - low refractive index layer - high refractive index layer.

[0033] In another preferred embodiment, the infrared radiation 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 the two high refractive index layers adjacent thereto. Particularly preferably, the infrared radiation reflecting layer precisely consists of such a layer sequence. Thus, in this embodiment, the infrared radiation reflecting layer has the following layer sequence:

[0034] High refractive index layer - low refractive index layer - high refractive index layer - low refractive index layer - high refractive index layer.

[0035] In another preferred embodiment, the infrared radiation 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 the two high refractive index layers adjacent thereto. Particularly preferably, the infrared radiation reflecting layer precisely consists of such a layer sequence. Thus, in this embodiment, the infrared radiation reflecting layer has the following layer sequence:

[0036] High refractive index layer - low refractive index layer - high refractive index layer - low refractive index layer - high refractive index layer - low refractive index layer - high refractive index layer.

[0037] Preferably, the infrared radiation reflecting layer consists of a total of three to seven layers, wherein the high refractive index layers and the low refractive index layers are arranged in an alternating layer sequence, and wherein each of the infrared radiation reflecting layer surfaces at which the layer stack of the infrared radiation reflecting layer begins and ends is formed by a high refractive index layer. Particularly preferably, the infrared radiation reflecting layer additionally has a conductive layer, in particular a metal layer.

[0038] The high refractive index layer preferably has a refractive index greater than 1.9, particularly preferably greater than 2.1, and the low refractive index layer preferably has a refractive index less than 1.6, particularly preferably less than 1.5.

[0039] Preferably, the high refractive index layer is formed based on silicon nitride, aluminum nitride, tin zinc oxide, silicon aluminum nitride, silicon zirconium nitride, silicon titanium nitride, silicon hafnium nitride, or titanium oxide, wherein particularly preferably it is based on silicon zirconium nitride or in particular titanium oxide. Preferably, the low refractive index layer is formed on the basis of silicon dioxide or doped silicon dioxide.

[0040] In a preferred embodiment, the thickness of the high refractive index layer is 50 nm to 200 nm, particularly preferably 50 nm to 180 nm, and most preferably 80 nm to 150 nm. In a preferred embodiment, the thickness of the low refractive index layer is 100 nm to 300 nm, particularly preferably 150 nm to 300 nm, and most preferably 160 nm to 280 nm.

[0041] In the context of the present invention, the refractive index is specified in all cases with respect to a wavelength of 550 nm. The method for determining the refractive index is known to those skilled in the art. The refractive index specified within the scope of the present invention can be measured, for example, by ellipsometry, where commercially available ellipsometers can be used. Unless otherwise stated, the layer thickness or the specification of the thickness refers to the geometric thickness of the layer.

[0042] The infrared radiation reflecting layer preferably has an infrared radiation reflectivity of at least 20%, particularly preferably at least 40%, most preferably at least 60% and in particular at least 80%. In the context of the present invention, the reflection within a certain percentage range refers to the average reflectance at a defined angle of incidence, for example 65°, with respect to the surface normal of the surface coated with the infrared radiation reflecting layer. Infrared radiation is radiation within the infrared range, i.e., radiation with a wavelength of 780 nm to 1 mm. The infrared radiation reflecting layer preferably has a higher reflectivity in the wavelength range of 940 nm to 2000 nm, particularly preferably 940 nm to 1400 nm, than in other wavelength ranges. This wavelength range is particularly suitable for obtaining information about vehicle occupants.

[0043] The term "reflectivity" is used in the sense of standard DIN EN 410–2011-04. Reflectivity always refers to the layer reflectivity measured when the coated surface of the element (i.e., the image display or the windshield) faces the light source and the detector.

[0044] Reflectivity describes the proportion of the total incident radiation that is reflected. It is shown as a percentage (based on 100% emitted radiation) or as a dimensionless number from 0 to 1 (normalized to the emitted radiation). When plotted as a function of wavelength, it forms a reflection spectrum. The reflectivity value is related to the reflection measurement of a light source that emits uniformly with a normalized radiation intensity of 100% within the spectral range under consideration.

[0045] In a preferred embodiment, the reflective layer is arranged between the inner glass plate and the outer glass plate. Particularly preferably, the reflective layer is applied to the outer surface of the inner glass plate or the inner surface of the outer glass plate. In this way, the reflective layer is better protected from corrosion and mechanical damage.

[0046] In another embodiment of the present invention, the reflective layer is arranged on the inner surface of the windshield closest to the vehicle occupant. If the windshield comprises an inner glass plate, an outer glass plate and a thermoplastic interlayer therebetween, the reflective layer is preferably arranged on the inner surface of the inner glass plate. Particularly preferably, a protective layer is applied over the entire surface of the reflective layer. By arranging the reflective layer on the inner surface of the windshield, ghost images caused by multiple reflections on the windshield are avoided. The protective layer serves to protect the reflective layer from corrosion or mechanical damage.

[0047] In another particularly preferred embodiment of the present invention, in addition to the inner glass plate, the outer glass plate and the thermoplastic interlayer, the windshield further comprises another glass plate - and the reflective layer is applied to the surface of the another glass plate. The another glass plate is preferably made of transparent glass, particularly soda-lime glass. However, it can also be prepared from other glasses (such as borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (such as polymethyl methacrylate or polycarbonate). The another glass plate has two surfaces, one of which preferably faces the inner surface of the inner glass plate, while the other surface faces away from the inner surface of the inner glass plate. The another glass plate also has an outer periphery.

[0048] Preferably, another glass plate coated with the reflective layer is applied to the inner or outer side surface of the inner glass plate by means of an adhesive layer. The reflective layer is preferably arranged between the other glass plate and the inner glass plate. The reflective layer is thus applied to the surface of the other glass plate facing the inner or outer side surface of the inner glass plate. As a result, the reflective layer is better protected from external influences. For example, the reflective layer will not be scraped off if the other glass plate has not been detached from the inner glass plate in advance. The reflective layer preferably extends over at least 80%, particularly preferably at least 90% of the surface of the other glass plate. In particular, except for the outer peripheral frame-shaped edge region adjacent to the outer peripheral edge of the other glass plate, the reflective layer extends over the entire surface of the other glass plate. As a result, the reflective layer is better protected from moisture and corrosion.

[0049] The other glass plate preferably extends over at least 10%, particularly preferably at least 15%, especially at least 20% of the surface area of the windshield.

[0050] The other glass plate is preferably thinner than the inner and outer glass plates. Alternatively or additionally, the other glass plate has a thickness of 50 μm to 1000 μm, preferably 150 μm to 500 μm and particularly preferably 150 μm to 250 μm. At this thickness, a good ratio of material cost to mechanical stability is achieved for the inner glass plate. The reflective layer and the other glass plate are also less aesthetically displeasing, and the optical quality of the windshield is improved compared to a greater thickness.

[0051] The reflective layer preferably has an infrared radiation reflectivity of at least 20%, particularly preferably at least 40%, most preferably at least 60% and especially at least 80%.

[0052] The reflective layer preferably has a reflectance of at least 20%, particularly preferably at least 40%, most preferably at least 60% and especially at least 80% for visible radiation. For the purposes of the present invention, reflection within a specific percentage range refers to the average reflectance at a defined angle of incidence, for example 65°, relative to the surface normal of the surface coated with the reflective layer. The reflective layer is designed to reflect the image projected onto the reflective layer by the image display and to reflect the infrared radiation from the radiation source. The reflective layer may be transparent, but is preferably opaque.

[0053] The reflective layer preferably comprises at least one metal selected from 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 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 glass plate or another glass plate because they can have high reflectivity to visible light and infrared radiation. The reflective layer preferably has a thickness of 10 nm (nanometers) to 100 μm (micrometers), particularly preferably 50 nm to 50 μm, especially 100 nm to 5 μm.

[0054] In a particularly preferred embodiment of the present invention, the reflective layer is a coating containing a thin film stack, i.e., a layer sequence of thin individual layers. The thin film stack contains one or more conductive layers based on nickel, nickel-chromium, titanium and / or aluminum. The conductive layers based on nickel, nickel-chromium, titanium and / or aluminum impart the basic reflective properties to the reflective layer, as well as the effect of reflecting infrared radiation and conductivity. The conductive layers are based on nickel, nickel-chromium, titanium and / or aluminum. The conductive layer preferably contains at least 90 wt% of nickel, titanium and / or aluminum, particularly preferably at least 99 wt% of aluminum, and very particularly preferably at least 99.9 wt% of nickel, titanium and / or aluminum. Layers based on aluminum, nickel-chromium, nickel and / or titanium may have dopants, such as palladium, gold, copper or silver. Materials based on aluminum, nickel, nickel-chromium and / or titanium are particularly suitable for reflecting light, and particularly preferably p-polarized light and infrared radiation. It has been shown that the use of nickel, nickel-chromium, titanium and / or aluminum in the reflective layer is particularly advantageous in terms of light reflection. Aluminum, nickel, nickel-chromium and / or titanium are significantly cheaper compared to many other metals such as gold or silver. In addition, these metals have high chemical resistance and thermomechanical resistance. The individual layers of the thin film stack preferably have a thickness of 10 nm to 1 μm. The thin film stack preferably has 2 to 20 individual layers, and particularly 5 to 10 individual layers.

[0055] In a very particularly preferred embodiment of the present invention, the reflective layer is a metal-free reflective film. The reflective layer then preferably is a film that functions on the basis of cooperating prisms and a reflective polarizer. The reflective layer preferably has a carrier film based on polyvinyl chloride or polyethylene terephthalate. The cooperating prisms and the reflective polarizer are applied to such a carrier film. Films for use as the reflective layer are commercially available, for example, from 3M Company. In this way, complex metal depositions can be avoided. The reflective layer, as a reflective film, is preferably applied to the inner side surface of the windshield (optionally the inner glass plate) via an adhesive layer, or is arranged within a thermoplastic interlayer (for example, by laminating the reflective layer into the thermoplastic interlayer or between two thermoplastic composite films). Alternatively, the reflective layer can also be applied as a reflective film to the other glass plate by means of an adhesion layer.

[0056] In another particularly preferred embodiment of the present invention, the reflective layer contains:

[0057] · a dielectric layer stack containing a TiO2 layer and a SiO2 layer,

[0058] · a dielectric layer stack containing a SiZrN layer and a SiO2 layer,

[0059] · a layer stack containing a Si:B layer or a SiZrAl layer,

[0060] · a layer stack containing a Si layer and a SiO2 layer,

[0061] · a layer stack containing a Si layer and a Si3N4 layer, or

[0062] · a carbide layer stack containing a TiC layer and / or a ZrC layer

[0063] or consists of one or more of these layer stacks. The described layer stacks have suitable reflective properties to achieve a uniform image as part of a projection device and also have a sufficiently high reflectance for infrared radiation. Preferably, the above layer stacks are applied as a coating to the windshield, particularly to the inner glass plate or the other glass plate.

[0064] Preferably, the reflective layer does not extend in the outer peripheral frame-shaped edge region (adjacent to the outer periphery of the windshield) of the windshield. The uncoated outer peripheral frame-shaped edge region serves to better separate the reflective layer from the external environment. Thus, the reflective layer is better protected from corrosion or mechanical damage. The uncoated edge region preferably has a width of less than 20 cm, particularly preferably less than 10 cm, especially less than 1 cm.

[0065] The windshield has an outer peripheral edge which particularly preferably includes an upper edge and a lower edge and two side edges extending therebetween - a left edge and a right edge. The upper edge is the edge intended to face upward in the installed position. The lower edge is the edge intended to face downward in the installed position. The upper edge is also commonly referred to as the roof edge, and the lower edge is also commonly referred to as the engine edge. The windshield can have any suitable geometry and / or curvature. The terms "left" and "right" refer to the side indication or direction indication when an observer looks at the windshield installed according to the invention from the inside.

[0066] In a particularly preferred embodiment, the reflective layer preferably extends over at most 50% of the area of the windshield, particularly preferably at most 40%, especially at most 20%. Particularly preferably, the reflective layer is arranged in the upper edge region of the windshield adjacent to the upper edge of the windshield and / or in the lower edge region of the windshield adjacent to the lower edge of the windshield, where an uncoated edge region is preferably located between the reflective layer and the upper edge and / or the lower edge. Alternatively, the reflective layer can also be additionally or exclusively arranged in the side edge region adjacent to one or both side edges of the windshield, in which case, the uncoated edge region is also preferably located between the reflective layer and the adjacent side edge (left and / or right edge). The uncoated edge region preferably has a width of less than 20 cm, particularly preferably less than 10 cm, especially less than 1 cm. The reflective layer preferably extends in a strip shape from one (left) side edge to the other (right) side edge and is particularly 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, especially at least 30 cm. This embodiment is particularly suitable because the reflective layer is not intended to be arranged in the perspective area. This can obtain higher reflection values for visible light and infrared radiation. Such an arrangement is generally used for projection devices that require high-contrast images.

[0067] According to the invention, the reflective layer is arranged on the windshield in such a way that, as seen by a vehicle occupant, when viewed through the windshield, it is completely arranged on an opaque background that is behind the windshield. In other words: when viewed from the outside, the reflective layer is completely hidden by the opaque background when viewed through the windshield. It is to be understood that when viewed through the windshield from inside the vehicle in a perspective view, the opaque background is arranged behind the reflective layer. The opaque background can thus be arranged in a consistent manner with the reflective layer, or extend over an area of the windshield beyond the area of the reflective layer. Viewing through the windshield means a viewing direction that is perpendicular to the main surface of the windshield. In the context of the present invention, "completely covering element A with element B" means that the orthogonal projection of element A onto the plane of element B is completely arranged within element B. This arrangement results in a high contrast, which makes the virtual image generated by visible light more visually perceptible. It also allows the use of a reflective layer with a lower transparency and allows the use of a reflective layer with a higher reflectivity for infrared radiation and visible light.

[0068] The opaque background can be produced by an opaque enamel (also known as screen printing) or an opaque thermoplastic film, which is arranged behind the reflective layer when viewed from inside the vehicle. The opaque background can also be produced by a locally (inregion) opaque thermoplastic film and is thus a component of the thermoplastic interlayer. The opaque background is particularly produced by a dark, preferably black, enamel that is applied to the outer glass pane. The enamel is preferably applied to the inner side surface of the outer glass pane. However, the enamel can also be applied to the inner side surface of the inner glass pane. The opaque background is preferably produced by a peripheral (framing) layer that extends along the outer perimeter of the windshield and can be widened in the area of the reflective layer. The enamel mainly serves as UV protection for the structural adhesive (e.g., for bonding to the vehicle) of the windshield. The opaque background preferably has a visible light transmittance of less than 15%, preferably less than 10%, and particularly preferably less than 1% (according to ISO9050:2003). The opaque background can also be designed to be semi-transparent - at least in some parts (insection) - for example, designed as a dot matrix, a stripe matrix, or a grid matrix. Alternatively, the opaque background can also have a gradient - for example, from opaque to semi-transparent coverage. The opaque background is preferably also opaque to infrared light and has an infrared light transmittance of less than 10%, particularly preferably less than 1%.

[0069] "Width" in the context of the present invention means the extension perpendicular to the extension direction.

[0070] Within the meaning of the present invention, "opaque" means a light transmittance of less than 30%, preferably less than 20%, particularly preferably less than 5%, and especially less than 0.1% (according to ISO 9050:2003). Within the context of the present invention, "transparent" means a light transmittance of at least 50%, preferably at least 60%, particularly preferably at least 70%, and especially at least 80% (according to ISO 9050:2003). The value of the light transmittance (TL), as is commonly used for automotive glazing, refers to light source A, i.e., the visible part of sunlight with wavelengths from 380 nm to 780 nm, and thus is essentially the visible spectrum of solar radiation. An infrared light beam is understood to mean a light beam with a wavelength greater than approximately 780 nm.

[0071] If a thin layer is mentioned, i.e., a layer with a thickness below 1000 nm, the following applies: If something is "formed based on" a material, it consists mainly of this material, especially consisting essentially of this material apart from any impurities or dopants. Unless otherwise stated, the layer thickness or the specification of the thickness refers to the geometric thickness of the layer.

[0072] If something is "formed based on" a polymeric material, it consists mainly - i.e., at least 50%, preferably at least 60%, and especially at least 70% - of this material. It can thus also contain other materials, such as stabilizers or plasticizers for example.

[0073] Such a layer structure of the reflective layer and / or the infrared radiation reflective layer is usually obtained by a series of deposition processes, which are carried out by vacuum methods, such as magnetron sputtering assisted by a magnetic field or by chemical vapor deposition (CVD). Alternatively, the layer structure of the functional layer can also be obtained by wet coating.

[0074] The thermoplastic interlayer is preferably formed as at least one thermoplastic laminate film and is based on ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU) or a mixture or copolymer or derivative thereof, particularly preferably based on polyvinyl butyral (PVB), and in addition additives known to those skilled in the art, such as plasticizers. The thermoplastic film preferably contains at least one plasticizer.

[0075] The thermoplastic interlayer can be formed by one or more thermoplastic films arranged one above the other, where after lamination of the layer stack, the thickness of the thermoplastic interlayer is preferably from 0.25 mm to 1 mm, usually 0.38 mm or 0.76 mm. The thermoplastic interlayer can also be formed by a film that is locally colored and thus is opaque. The opaque background can thus also be a component of the thermoplastic interlayer. The interlayer can also be formed by more than one film, and the at least two films can extend over different regions in the windshield area.

[0076] The outer glass plate and the inner glass plate are preferably made of transparent glass, in particular soda-lime glass, which is customary for vehicle glass plates. However, in principle, the glass plates can also be made of other types of glass (such as borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (such as polymethyl methacrylate or polycarbonate). The thicknesses of the outer glass plate and the inner glass plate can vary greatly. Preferably, glass plates with a thickness in the range from 0.8 mm to 5 mm, preferably from 1.4 mm to 2.5 mm, are used, such as those with a standard thickness of 1.6 mm or 2.1 mm. The outer glass plate, the other glass plate, and the inner glass plate can be prestressed, partially prestressed, or not prestressed independently of one another. If at least one of the glass plates is to be tempered, this can be thermal or chemical prestressing.

[0077] The outer glass plate, the inner glass plate, and the windshield can have any three-dimensional shape. Preferably, the inner glass plate and the outer glass plate do not have any shaded areas, so that they can be effectively coated by cathodic sputtering. The inner glass plate and the outer glass plate, and thus the windshield, are also preferably flat, or slightly or strongly curved in one direction or in multiple spatial directions. The optional other glass plate is preferably curved in the area of the reflective layer in the same shape as the windshield or the optional inner glass plate.

[0078] In another embodiment of the present invention, the device according to the present invention comprises another radiation receiver, wherein the other radiation receiver is preferably directed towards the face of the vehicle occupant, so that visible light reflected by the face of the vehicle occupant can be at least partially received by the other radiation receiver. In this way, other information about the vehicle occupant can be obtained. The visible spectral range can be used to obtain information that cannot be obtained using infrared radiation (such as certain vital signs). Alternatively or additionally, the visible light received by the other radiation receiver can be used for video transmission (such as for digital communication inside or outside the vehicle).

[0079] In a preferred embodiment of the present invention, the 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 has a reflectivity of preferably at least 20%, particularly preferably at least 40%, very particularly preferably at least 60%, especially at least 80% for incident s-polarized visible light. The functional layer preferably extends over at least 40%, very particularly preferably over at least 80%, especially 100% of the surface of the image display facing the windshield.

[0080] The radiation receiver is preferably adapted to receive visible light in addition to infrared radiation, such that s-polarized visible light reflected by the face of the vehicle occupant can be reflected via the reflective layer and subsequently via the functional layer and received by the radiation receiver. Alternatively, another radiation receiver is arranged relative to the functional layer and the reflective layer in such a way that s-polarized visible light reflected by the face of the vehicle occupant can be reflected via the reflective layer and subsequently via the functional layer and received by the other radiation receiver. For the purposes of the present invention, "reflected via the reflective layer and subsequently via the functional layer to the radiation receiver or to the other radiation receiver" means that the visible s-polarized light reflected by the face of the vehicle occupant at least partially illuminates 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 illuminates 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 towards the radiation receiver or towards the other radiation receiver, such that the radiation receiver or the other radiation receiver can receive the visible s-polarized light. In this embodiment, the image display preferably emits more than 50%, particularly preferably more than 70%, in particular only p-polarized light, which can be transmitted through the functional layer. This arrangement allows information about the vehicle occupant to be obtained using the visible spectral range, while maintaining a space-saving and aesthetically unobtrusive solution. The visible s-polarized light can be generated by another radiation source, which directly or indirectly illuminates the face of the vehicle occupant. However, the visible s-polarized light can also be exclusively or additionally natural light (solar radiation) from the external environment. A person skilled in the art knows that natural light contains both p-polarized light and s-polarized light.

[0081] In a particularly preferred embodiment of the present invention, a linear polarizer is arranged between the radiation receiver or optionally another 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 the visible light reflected by the functional layer first irradiates the linear polarizer before it can irradiate the radiation receiver and be received by the radiation receiver. Alternatively, the linear polarizer is arranged between the other radiation receiver and the functional layer in such a way that the visible light reflected by the functional layer first irradiates the linear polarizer before it can irradiate the other radiation receiver and be received by the other radiation receiver. This also applies to the p-polarized light emitted by the image display, which passes through the functional layer and would irradiate the radiation receiver or possibly another radiation receiver if the p-polarized light were not absorbed by the linear polarizer beforehand. The light beam path of the visible light and the p-polarized light from the functional layer to the radiation receiver or optionally another radiation receiver is thus interrupted by the linear polarizer, where the s-polarized part of the visible light passes through the linear polarizer and the p-polarized light is absorbed by the linear polarizer. For technical reasons, the part of the p-polarized light emitted by the image display is directed in such a way that the p-polarized light passes through the functional layer and then irradiates the radiation receiver or another radiation receiver. Due to the linear polarizer 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 the p-polarized light emitted by the image display from irradiating the radiation receiver or optionally another radiation receiver, because otherwise it would lead to an unwanted image superposition.

[0082] Preferably, the circular polarizer is arranged between the radiation receiver or another radiation receiver and the linear polarizer such that the s-polarized light transmitted by the linear polarizer first passes through the circular polarizer and is thus circularly polarized. For technical reasons, the light that is circularly polarized at the circular polarizer can then be at least partially reflected at the (another) radiation receiver (e.g., reflected at the lens of the (another) radiation receiver). The circularly polarized light reflected at the radiation receiver or optionally another radiation receiver changes its direction of rotation upon reflection, i.e., now has the opposite direction of rotation. The circular polarizer is arranged between the linear polarizer and the radiation receiver or optionally another radiation receiver in such a way that the reflected circularly polarized light is reflected towards the circular polarizer and then passes through the circular polarizer, where the circularly polarized light with the opposite direction of rotation changes its polarization to p-polarization and then irradiates the linear polarizer. The linear polarizer is designed in such a way that the p-polarized light is absorbed by the linear polarizer. The s-polarized light irradiating the circular polarizer is thus circularly polarized, then the circularly polarized light is reflected at the radiation receiver or optionally another radiation receiver, where the circularly polarized light reverses its direction of rotation, and then the circularly polarized light with the opposite direction of rotation irradiates the circular polarizer again. Where the circularly polarized light with the opposite direction of rotation changes its polarization to p-polarized light. Then the p-polarized light irradiates the linear polarizer, where the p-polarized light is absorbed. The combination of the circular polarizer and the linear polarizer can prevent the circularly polarized light reflected at the radiation receiver or another radiation receiver from entering the field of view of the vehicle occupants via subsequent reflections at the functional layer and the reflective layer.

[0083] A circular polarizer is an optical element that produces a phase shift in transmitted light. The desired delay is achieved by changing the thickness and alignment of the circular polarizer in the light beam path. In the case of a circular polarizer, there is a 90° phase shift. A circular polarizer is also referred to as a λ / 4 plate or a quarter-wave plate. Suitable circular polarizers are known to those skilled in the art. A circular polarizer consists of a birefringent material. A birefringent material has slightly different refractive indices of light from each other.

[0084] In a preferred embodiment, the λ / 4 circular polarizer is designed as a polymer circular polarizer. The λ / 4 circular polarizer is commercially available in the form of a birefringent plastic film. In another preferred embodiment, the λ / 4 circular polarizer is designed as a circular polarizer made of crystalline quartz or sapphire.

[0085] Preferably, the linear polarizer is made of a polymer film stretched in one direction. The linear polarizer preferably consists of a polyvinyl alcohol film (PVA film), which has been stretched and colored with iodine during manufacturing. Optionally, the PVA film of the linear polarizing filter can be laminated with optically neutral cellulose triacetate carriers on both sides. Suitable linear polarizers with p-polarized light absorption properties are known to those skilled in the art.

[0086] The radiation source, the radiation receiver, and, if applicable, another radiation receiver must be positioned so as to irradiate the face only indirectly with respect to the suitable reflection of infrared radiation or visible light radiation on the reflective layer and the infrared radiation reflective layer or the functional layer, and this can generally be done in such a way that they are invisible or at least almost invisible to the vehicle occupants. For example, they can be located in the rear region of the vehicle's instrument panel. This is another advantage of the present invention.

[0087] The radiation source is preferably a thermal radiator, such as an incandescent lamp and a radiant heater. The radiation source can also be a selective radiator, such as a Nernst lamp, a Welsbach 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, such as a semiconductor laser, a Nd:YAG laser, or a CO2 laser. The radiation receiver is preferably a thermal detector. If infrared radiation in the range from 800 nm to 1400 nm is used, the radiation receiver is preferably a semiconductor detector.

[0088] The indication of the polarization direction here 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 spanned by the incident vector and the surface normal of the windshield at the geometric center of the irradiated area.

[0089] The functional layer is preferably a reflective, linear polarizing filter, in particular a broadband wire grid polarizing filter. The polarizing filter is designed to reflect s-polarized light but allow p-polarized light to pass through. Wire grid polarizing filters (wire grid polarizers) are generally known to those skilled in the art. A wire grid polarizing filter contains wires preferably applied to a first transparent layer, which is preferably made of glass, in particular fused silica. A second transparent layer, preferably made of glass, in particular fused silica, is applied as a protective layer to the wires. The wires are thus arranged between a first protective layer and a second protective layer. To achieve the desired polarization effect, the wires are applied parallel to each other on the first transparent layer. Electromagnetic waves (visible light) - one component of whose electric field is aligned parallel to the wires - induce electrons to move along the length of the wires. Since the electrons can move freely in this direction, the polarizer behaves like a metal surface when 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 wires). For electromagnetic waves whose electric field is perpendicular to the wires, the electrons cannot move very far across the width of a single wire. Therefore, only a small amount of energy is reflected, and the incident wave can penetrate the grating. In this case, the grating behaves like a dielectric material. In the context of the present invention, this means that visible light is polarized by the birefringence properties of the wire grid polarizing filter. Visible light irradiating the wire grid polarizing filter is reflected according to the polarization of the light components, or it can be transmitted through the wire grid polarizing filter. The p-polarized light is transmitted to the dielectric (and thus can be transmitted through the wire grid polarizing filter), while the s-polarized light is reflected. The wires preferably contain a metal, preferably aluminum. The wires are particularly preferably made of aluminum. The wires preferably have a diameter of from 100 nm to 10 μm, particularly preferably from 500 nm to 5 μm, especially from 1 μm to 3 μm. The distance between the wires is preferably less than 780 nm, particularly preferably less than 400 nm, especially less than 100 nm.

[0090] The image display is preferably a liquid crystal display (LCD), a thin film transistor (TFT) display, a light emitting diode (LED) display, an organic light emitting diode (OLED) display, an electroluminescent display (ELD) or a micro-LED display.

[0091] The technical terms from the HUD field used here are generally known to a person skilled in the art. For a detailed description, reference is made to the dissertation “Simulation-based measurement technique for testing head-up displays” by Alexander Neumann of the Institute for Informatics of the Technical University of Munich (Munich: University Library of TU Munich, 2012) - especially Chapter 2 “The Head-Up Display”.

[0092] The above-described desired reflection characteristics of the reflective layer, the infrared radiation reflective layer, and the functional layer are achieved in particular by the selection of materials and thicknesses and the structure of individual layers or layer sequences.

[0093] The invention is further extended to an assistance system, in particular a driver assistance system, which has an infrared and possibly visible light-based monitoring function for vehicle occupants, in particular drivers, of a vehicle, and which contains a device according to the invention. The assistance system further contains at least one actuator and / or at least one signal output device, and an electronic control device which is configured to obtain information about the vehicle occupant based on the output signals of the radiation receiver and optionally another radiation receiver, and to output an electrical signal to at least one actuator for performing a mechanical action and / or to at least one signal output device for outputting visual and / or acoustic signals based on the information obtained about the vehicle occupant.

[0094] Preferably, the control device obtains an actual value from the deviation of the signals emitted by the radiation source and the radiation receiver. Such an actual value can be compared with a target value range stored on the control device. The target value range indicates a value range in which no electrical signal is output to at least one actuator for performing a mechanical action and / or to at least one signal output device for outputting optical and / or acoustic signals. This is a value range that reflects, for example, an alert, attentive, and healthy vehicle occupant. The control device is designed in such a way that if the actual value deviates from the target value range, i.e., if the actual value is outside the target value range, then an electrical signal is sent to at least one actuator for performing a mechanical action and / or to at least one signal output device for outputting optical and / or acoustic signals. Preferably, the target value range is obtained by a previous calibration and stored digitally on the control device.

[0095] Furthermore, the invention extends to a method for monitoring a vehicle occupant, in particular a driver, of a vehicle, in which an assistance system according to the invention is provided. The method at least comprises the following steps:

[0096] (a) Infrared radiation is emitted by a radiation source and reflected to a radiation receiver in the following order: via an infrared radiation reflecting layer, a reflecting layer, the face of the vehicle occupant, a reflecting layer, and an infrared radiation reflecting layer.

[0097] (b) The infrared radiation is received by the radiation receiver.

[0098] (c) Information about the vehicle occupant is obtained by an electronic control device based on the infrared radiation received by the radiation receiver.

[0099] (d) Based on the information, an action is performed by the actuator and / or an optical and / or acoustic signal is output by the signal output device.

[0100] It should be understood that the method follows the order of (a), (b), (c), and finally (d).

[0101] In a preferred embodiment of the method according to the invention, in method step (a), s-polarized visible light is reflected by the face of the vehicle occupant to the radiation receiver or optionally another radiation receiver via a reflecting layer and then via a functional layer. In method step (b), the s-polarized visible light is received by the radiation receiver or optionally another radiation receiver.

[0102] In method step (c), other information about the vehicle occupant is obtained by an electronic control device based on the visible s-polarized light received by the radiation receiver or optionally another radiation receiver.

[0103] In method step (d), an action is performed by the actuator and / or an optical and / or acoustic signal is output by the signal output device based on the other information.

[0104] Preferably, in method step (c), an actual value is obtained from the deviation of the signals emitted by the radiation source and the radiation receiver by means of a control device. This actual value is compared with a target value range stored in the control device. In method step (d), if the actual value deviates from the target value range, then based on the detected deviation, an action is performed by the actuator and / or an optical and / or acoustic signal is output by the signal output device.

[0105] In another preferred embodiment, in method step (c), another actual value is obtained from the signal of another radiation source received by means of the control device. This another actual value is compared with another target value range stored on the control device. In method step (d), if the another actual value deviates from the another target value range, an action is performed by means of an actuator and / or an optical and / or acoustic signal is output by means of the signal output device based on the detected deviation.

[0106] The preferred design of the device according to the invention described above applies correspondingly to the method according to the invention.

[0107] Furthermore, the invention extends to the use of the device according to the invention in an auxiliary system, in particular a driver assistance system, of a vehicle for land, water or air transportation, in particular a motor vehicle.

[0108] The various embodiments of the invention can be implemented individually or in any combination. In particular, without departing from the scope of the invention, the features described above and the features explained below can be used not only in the specified combinations, but also in other combinations or individually.

[0109] The invention is explained in more detail below with reference to exemplary embodiments, in which reference is made to the accompanying drawings. The drawings are schematic and not to scale. The drawings do not limit the invention in any way. In the drawings:

[0110] Figure 1 is a schematic view of the front part of a vehicle with a driver, having a device for monitoring the driver based on infrared and a driver assistance system,

[0111] Figure 2 is Figure 1 an enlarged cross-sectional view of the device of

[0112] Figure 3 is a cross-sectional view of an embodiment of the device according to the invention,

[0113] Figure 3A is Figure 3 a plan view of the windshield of the embodiment of

[0114] Figures 4 - 5 is another embodiment of the device according to the invention shown in cross-section.

[0115] Figure 1 is a schematic view of the front part of a vehicle 2 with a vehicle occupant, the vehicle occupant being the driver of the vehicle 2, having a device 1 for monitoring the vehicle occupant based on infrared and a driver assistance system 100. In Figure 2 device 1 is shown enlarged.

[0116] The device 1 includes the windshield 5 of the vehicle 2, the windshield 5 having an outer glass plate 12 and an inner glass plate 13 firmly connected to each other by a thermoplastic interlayer 14, and a reflective layer 7 (see Figure 2 ).

[0117] The windshield 5 has an upper edge and a lower edge and two side edges connecting the upper edge and the lower edge (all together forming the outer peripheral edge of the windshield 5). The lower edge of the windshield 5 (also referred to as the engine edge) is the edge facing the ground in the installed position. The upper edge of the windshield 5 (also referred to as the roof edge) is the edge facing the vehicle roof in the vehicle 2 in the installed position.

[0118] The outer glass plate 12 and the inner glass plate 13 are each composed of glass, preferably heat-strengthened soda-lime glass, and are transparent to visible light 11. The outer glass plate 12 has a thickness of, for example, 2.1 mm, and the inner glass plate 13 has a thickness of, for example, 1.5 mm. The thermoplastic interlayer 14 contains a thermoplastic, preferably polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), and / or polyethylene terephthalate (PET), and is, for example, 0.8 mm thick.

[0119] The reflective layer 7 is, for example, a dielectric layer stack containing a TiO2 layer and a SiO2 layer. The reflective layer 7 is, for example, applied to the outer surface III of the inner glass plate 13 by means of magnetron sputtering. Except for the outer peripheral border edge region, the reflective layer 7 extends over the entire surface III of the inner glass plate 13, the edge region being arranged adjacent to the outer peripheral edge of the windshield 5.

[0120] The device 1 further includes an image display 6 having an infrared radiation reflective layer 8. The image display 6 is intended to emit a virtual image onto the reflective layer 7 by means of visible light 11. The virtual image is reflected on the reflective layer 7 towards the face 9 of the vehicle occupant (shown by the bold arrow in Figure 2 ), such that the vehicle occupant can visually perceive the virtual image in the form of visible light 11. The reflective layer 7 on the inner glass plate 13 and the image display 6 together form a head-up display. The image display 6 is, for example, a light-emitting diode display (LED display).

[0121] The infrared radiation reflective layer 8 is applied flatly to the surface A of the image display 6 facing the windshield 5. The surface A of the image display 6 facing the windshield 5 is at the same time the surface of the image display 6 through which the visible light of the image display 6 can be emitted in the direction of the reflective layer 7. The visible light 11 of the image display 6 is, for example, only p-polarized light to avoid double images when reflected on the windshield 5.

[0122] The device 1 further includes a radiation source 3 and a radiation receiver 4, as inFigure 1 and Figure 2 As schematically shown in Figure 2 , the radiation source 3 and the radiation receiver 4 can be arranged adjacent to each other, but can also be installed in an assembly. The radiation source 3 and the radiation receiver 4 are, for example, installed in the rear region of the instrument panel of the vehicle 2 (at a position closer to the windshield 5 than the vehicle occupants), where they are hardly visible to the vehicle occupants. The radiation source 3 is positioned and oriented in such a way that the infrared radiation 10 emitted by the radiation source 3 irradiates the infrared radiation reflecting layer 8 and is reflected by the infrared radiation reflecting layer 8 to the reflecting layer 7 there. The infrared radiation 10 emitted from the infrared radiation reflecting layer 8 is reflected by the reflecting layer 7 onto the face 9 of the vehicle occupant. The infrared radiation 10 (hereinafter referred to as infrared reflected radiation 15 for clarity) is reflected by the face 9 of the vehicle occupant in the direction of the reflecting layer 7. The infrared reflected radiation 15 is reflected by the reflecting layer 7 onto the infrared radiation reflecting layer 8. The infrared reflected radiation 15 is reflected by the infrared radiation reflecting layer 8 onto the radiation receiver 4. The radiation receiver 4 is oriented toward the surface A of the image display 6 coated with the infrared radiation reflecting layer 8 and can receive the infrared reflected radiation 15 reflected by the infrared radiation reflecting layer 8. Assuming that the vehicle occupant is in a normal sitting position in the vehicle 2, the infrared radiation 10 reflected by the reflecting layer 7 onto the face 9 of the vehicle occupant preferably irradiates the face 9 of the vehicle occupant substantially vertically. The infrared radiation 10 preferably reflects back from the face 9 of the vehicle occupant to the reflecting layer 7 substantially vertically as the infrared reflected radiation 15. In this way, particularly suitable and a large amount of information about the condition of the vehicle occupant can be obtained.

[0123] The infrared radiation reflecting layer 8 is, for example, a layer stack having two high refractive index layers and one low refractive index layer. The high refractive index layers are, for example, based on silicon nitride. The low refractive index layer is, for example, formed based on nanoporous silica.

[0124] The radiation source 3 is, for example, an infrared light emitting diode (IR-LED). The radiation receiver 4 is, for example, a thermal detector.

[0125] Based on the driver data collected in this way, information about the vehicle occupant (in this case the driver) can be obtained in a particularly reliable manner. Thereby, features of the face 9, such as facial expressions and eye movements, can be obtained particularly well and reliably. In addition, the radiation source 3, the image display 6, and the radiation receiver 4 can be arranged in the rear region of the instrument panel such that they can be easily integrated into the interior of the vehicle 2 and do not interfere with the design of the vehicle interior. By integrating the projection device (i.e., the head-up display having the reflecting layer 7 and the image display 6) into the device 1 for monitoring the vehicle occupant, the limited space available in the vehicle 2 can be optimally utilized.

[0126] Now referring to Figure 3 and Figure 3A, which shows an enlarged cross-sectional view and a plan view of the windshield 5 from inside the vehicle. Figure 3 and Figure 3A relates to an embodiment of the present invention. Figure 3 The cross-sectional view of the windshield 5 in Figure 3A corresponds to the cutting line A-A' shown in Figure 3 and Figure 3A The variants shown in Figure 1 and Figure 2 basically correspond to the variants from Figure 1 and Figure 2 , so only the differences will be discussed here, and for other aspects, reference is made to the description related to Figure 1 and Figure 2 .

[0127] Different from the variants of Figure 1 and Figure 2 , the reflective layer 7 does not extend over the entire outer surface III of the inner glass plate 13 in Figure 3 and Figure 3A , but is only arranged in the lower edge region of the windshield 5. The reflective layer 7 extends in a strip shape with a width of approximately 15 to 20 cm from the left edge of the windshield 5 to the right edge of the windshield 5. Between the reflective layer 7 and the left and right edges of the windshield 5, there is an approximately 5 cm wide area that is not coated with the reflective layer 7. There is also an approximately 5 cm wide area that is not coated with the reflective layer 7 between the reflective layer 7 and the lower edge of the windshield 5. The reflective layer 7 is thus arranged outside the intended visible area of the windshield 5. When viewing through the windshield 5 from inside the vehicle, the reflective layer 7 is also arranged in front of the opaque background 19. This also means that when viewing through the windshield 5 from the external environment, the reflective layer 7 is completely shielded by the opaque background 19.

[0128] The opaque background 19 is designed, for example, in the form of a black silk screen printing applied to the inner side surface II of the outer glass plate 12. The silk screen printing extends along the outer peripheral edge of the windshield 5 in a border shape (see Figure 3A ). The silk screen printing is applied wider along the lower edge of the windshield 5 so that the reflective layer 7 is completely arranged in front of the silk screen printing, i.e., the opaque background 19. The silk screen printing especially serves as UV protection for the mounting adhesive of the windshield 5 (for example, for bonding to the vehicle 2).

[0129] By arranging the reflective layer 7 outside the intended viewing area of the windshield 5, a reflective layer 7 with a higher reflectivity to visible light 11 can be used, and an increase in the reflectivity to visible light 11 generally automatically leads to an increase in the reflectivity to infrared radiation 10. As a result, the visible light 11 emitted from the image display 6 onto the reflective layer 7 can be better visually perceived by the vehicle occupants, and at the same time, the condition of the vehicle occupants can be better determined by means of the infrared radiation 10.

[0130] Reference is now made Figure 4 and Figure 5 , which shows an enlarged cross-sectional view of the device 1. Figure 4 and Figure 5 relate to other embodiments of the present invention. Figure 4 and Figure 5 The variants shown in Figure 3 and Figure 3A basically correspond to the variants from Figure 3 and Figure 3A , so only the differences will be discussed here, and reference is made in other respects to the description relating to Figure 3 and Figure 3A .

[0131] In contrast to the variants of Figure 3 and Figure 3A , Figure 4 the opaque background 19 in Figure 4 is not formed as a black screen printing, but as a partially colored thermoplastic interlayer 14. The thermoplastic interlayer 14 is locally colored, and the opaque coloring appears in a border shape along the outer peripheral edge of the windshield 5. The colored area of the thermoplastic interlayer 14 widens along the lower edge of the windshield 5 such that the reflective layer 7 is completely arranged in front of the colored area of the thermoplastic interlayer 14, i.e., the opaque background 19.

[0132] The windshield 5 has another glass plate 16, wherein the another glass plate 16 has an outer lateral surface V facing the inner glass plate 13 and an inner lateral surface VI facing away from the inner glass plate 13. The reflective layer 7 is applied over the entire surface of the outer lateral surface V of the another glass plate 16 instead of on the inner glass plate 13. The another glass plate 16 is made of soda-lime glass, for example, and has a thickness of 1 mm. The another glass plate 16 does not extend over the entire surface of the windshield 5, but has the same dimensions as the reflective layer 7. The another glass plate 16 is arranged on the inner lateral surface IV of the inner glass plate 13 by means of an adhesive layer (not shown here), for example. The adhesive layer is arranged between the reflective layer 7 and the inner glass plate 13 and connects (bonds) them together.

[0133] In Figure 5In the embodiment of the device 1 according to the invention shown, in addition to the radiation receiver 4 for infrared radiation 10, another radiation receiver 17 is directed towards the surface A of the image display 6 facing the windshield 5. A functional layer 18 is also arranged on the surface A of the image display 6 facing the windshield 5, and the functional layer has a light transmittance of, for example, at least 70% for p-polarized visible light and a reflectance of, for example, 70% for s-polarized visible light 20. The functional layer 18 is, for example, a broadband wire grid polarizing filter.

[0134] The windshield 5 also has another glass plate 16, wherein the other glass plate 16 has an outer surface V facing the inner glass plate 13 and an inner side surface VI facing away from the inner glass plate 13. The reflective layer 7 is applied over the entire surface of the outer surface V of the other glass plate 16 rather than on the inner glass plate 13. The dimensions of the other glass plate 16, its arrangement on the windshield 5, and the bonding of the other glass plate 16 to the inner glass plate 13 are equivalent to Figure 4 those of the embodiment of

[0135] The other radiation receiver 17, the image display 6 with the functional layer 18, and the reflective layer 7 are arranged relative to each other in such a way that the s-polarized light 20 reflected by the face 9 of the vehicle occupant (which irradiates the reflective layer 7) is at least partially reflected by the reflective layer 7 towards the functional layer 18. The visible s-polarized light 20 irradiating the functional layer 18 is reflected by the functional layer 18 towards the other radiation receiver 17 and received by the other radiation receiver 17. The image display 6 only emits visible p-polarized light, and at least 70% of the visible p-polarized light 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 affected.

[0136] For example, a linear polarizer and a circular polarizer (not shown here) can be arranged between another radiation receiver 17 and the functional layer 18. The linear polarizer and the circular polarizer are arranged such that, for example, visible light containing a part of s-polarized light 20 and a part of p-polarized light (which is reflected by the functional layer 18 in the direction of another radiation receiver 17) first irradiates the linear polarizer, where the p-polarized light is absorbed and the s-polarized light 20 is transmitted through the linear polarizer. The s-polarized light 20 then passes through the circular polarizer and is accordingly circularly polarized and finally irradiates another radiation receiver, which at least partially receives the circularly polarized light. It is possible that a part of the circularly polarized light irradiating another radiation receiver 17 is reflected at the other radiation receiver 17, for example, on a lens for receiving the s-polarized light 20, in the opposite direction of rotation. The circularly polarized light reflected in this way (now having the opposite direction of rotation) first irradiates the circular polarizer again, where its polarization becomes p-polarized during transmission through the circular polarizer. The light that is now p-polarized then irradiates the linear polarizer and is absorbed by it. The linear polarizer and the circular polarizer are also arranged, for example, such that the residual p-polarized light (scattered light) generated for technical reasons - which is emitted by the image display 6 and which inevitably points to another radiation receiver technically - first passes through the functional layer 18 and then irradiates the linear polarizer, where the residual p-polarized light is absorbed.

[0137] With the help of another radiation receiver 17, other information about the vehicle occupants can be collected. This information can contribute to improving the assistance system 100. By arranging the reflective layer 7 in front of the opaque background 19, a reflective layer 7 with a higher reflectivity for s-polarized visible light 20 can be used. This allows for more effectively obtaining information about the condition of the vehicle occupants. Another radiation receiver 17 can also be a camera that continuously records the face 9 of the vehicle occupants. The continuously recorded video can be used, for example, for communication with other vehicle occupants or people outside the vehicle 2. The video of the call participants can be projected onto the reflective layer 7 with the help of the image display 6, such that the vehicle occupants and the call participants can see each other in real time.

[0138] List of reference numerals

[0139] 1 Device

[0140] 2 Vehicle

[0141] 3 Radiation source

[0142] 4 Radiation receiver

[0143] 5 Windshield

[0144] 6 Image display

[0145] 7 Reflective layer

[0146] 8 Infrared radiation reflecting layer

[0147] 9 Face of the vehicle occupant

[0148] 10 Infrared radiation

[0149] 11 Visible light

[0150] 12 Outer glass plate

[0151] 13 Inner glass plate

[0152] 14 Thermoplastic interlayer

[0153] 15 Infrared reflected radiation

[0154] 16 Another glass plate

[0155] 17 Another radiation receiver

[0156] 18 Functional layer

[0157] 19 Opaque background

[0158] 20 s-polarized light

[0159] 100 Auxiliary system

[0160] I Outer surface of the outer glass plate 12

[0161] II Inner side surface of the outer glass plate 12

[0162] III Outer surface of the inner glass plate 13

[0163] IV Inner side surface of the inner glass plate 13

[0164] V Outer surface of another glass plate 16

[0165] VI Inner side surface of another glass plate 16

[0166] A Surface of the image display 6 facing the windshield 5

[0167] A - A’ section line

Claims

1. A device (1) for an auxiliary 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 windshield (5) having a reflective layer (7), and - an image display (6) for emitting visible light (11), having an infrared radiation reflective layer (8), wherein the image display (6) is arranged relative to the reflective layer (7) in such a way that the visible light (11) emitted by the image display (6) can be reflected by the reflective layer (7) towards the face (9) of the vehicle occupant, and wherein the radiation source (3) and the radiation receiver (4) are arranged relative to the infrared radiation reflective layer (8) in such a way that the infrared radiation (10) emitted by the radiation source (3) is reflected in the following order: Reflected via the infrared radiation reflective layer (8), the reflective layer (7), the face (9) of the vehicle occupant, the reflective layer (7) and the infrared radiation reflective layer (8) to the radiation receiver (4), and can be received by the radiation receiver (4), wherein the reflective layer (7) is, as seen by the vehicle occupant, completely arranged in front of the opaque background (19) of the windshield (5) when viewed through the windshield (5).

2. The device (1) according to claim 1, wherein the infrared radiation reflective layer (8) is arranged on the surface (A) of the image display (6) facing the windshield (5) and is permeable to visible light (11).

3. The device (1) according to claim 1 or 2, wherein the windshield (5) comprises an outer glass plate (12), a thermoplastic interlayer (14) and an inner glass plate (13), and the reflective layer (7) is arranged between the inner glass plate (13) and the outer glass plate (12).

4. The device (1) according to claim 1 or 2, wherein the reflective layer (7) is arranged on the inner side surface (IV) of the windshield (5) closest to the vehicle occupant.

5. The device (1) according to any one of claims 1 to 4, wherein the infrared radiation reflective layer (8) consists of an alternating layer sequence of a high refractive index layer with a refractive index greater than 1.9 and a low refractive index layer with a refractive index less than 1.

6.

6. The device (1) according to claim 5, wherein the high refractive index layer is formed based on silicon nitride, aluminum nitride, tin zinc oxide, silicon zirconium nitride, silicon aluminum nitride, silicon titanium nitride, silicon hafnium nitride or titanium oxide, preferably formed based on silicon zirconium nitride or titanium oxide.

7. The device (1) according to claim 5 or 6, wherein the low refractive index layer is formed based on silica or doped silica.

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

9. The device (1) according to any one of claims 1 to 8 further comprises another radiation receiver (17) for receiving visible s-polarized light (20), and a linear polarizer preferably arranged between the another radiation receiver (17) and the image display (6).

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

11. The device (1) according to claim 10, wherein the another radiation receiver (17) and the functional layer (18) are arranged relative to each other such that s-polarized visible light (20) reflected by the face (9) of the vehicle occupant can be reflected via the reflective layer (7) and then via the functional layer (18) and received by the another radiation receiver (17).

12. An assistance system (100) having a monitoring function for vehicle occupants of a vehicle (2), comprising: - the device (1) according to any one of claims 1 to 11, - at least one actuator and / or at least one signal output device, - an electronic control device configured to obtain information about the vehicle occupant based on the output signal of the radiation receiver (4), and output an electrical signal to at least one actuator for performing a mechanical action and / or to at least one signal output device for outputting a visual and / or acoustic signal based on the obtained information.

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

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

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