Laminated glass designed for heads-up display, featuring an electroconductive and anti-reflective coating.

Description

[0001] The invention relates to a composite disc and a projection arrangement for a head-up display.

[0002] Modern cars are increasingly equipped with so-called head-up displays (HUDs). A projector, typically located in the dashboard area, projects images onto the windshield, where they are reflected and perceived by the driver as a virtual image (from their perspective) behind the windshield. This allows important information to be projected into the driver's field of vision, such as current speed, navigation instructions, or warnings, which the driver can see without taking their eyes off the road. Head-up displays can thus significantly contribute to improving road safety.

[0003] The problem with the head-up displays described above is that the projected image is reflected off both surfaces of the windshield. As a result, the driver not only perceives the desired main image, which is caused by the reflection off the inner surface of the windshield (primary reflection), but also a slightly offset, usually less intense, secondary image caused by the reflection off the outer surface of the windshield (secondary reflection). The latter is commonly referred to as a ghost image. This problem is generally solved by positioning the reflective surfaces at a deliberately chosen angle to each other, so that the main image and the ghost image are superimposed, thus making the ghost image less noticeable.

[0004] Windscreens consist of two panes of glass laminated together with a thermoplastic film. If the surfaces of the glass panes are to be arranged at an angle, as described, it is common to use a thermoplastic film with a non-constant thickness. This is also referred to as a wedge-shaped film or wedge film. The angle between the two surfaces of the film is called the wedge angle. The wedge angle can be constant across the entire film (linear thickness variation) or change depending on the position (non-linear thickness variation). Laminated glass with wedge films is known, for example, from WO2009 / 071135A1, EP1800855B1, or EP1880243A2.

[0005] It is also known to apply transparent, electrically conductive coatings to windshields. These coatings can act as IR-reflective coatings to reduce the heating of the vehicle interior and thus improve thermal comfort. The coatings can also be used as heated coatings by connecting them to a voltage source, causing an electric current to flow through the coating. Suitable coatings contain conductive metallic layers, for example, based on silver or aluminum. Because these layers are susceptible to corrosion, it is common practice to apply them to the surface of the outer or inner pane facing the intermediate layer, so that they do not have contact with the atmosphere. Silver-containing transparent coatings are known, for example, from WO 03 / 024155, US 2007 / 0082219 A1, US 2007 / 0020465 A1, WO2013 / 104438, and WO2013 / 104439.In connection with head-up displays, coated windshields often have the problem that the conductive coating creates an additional reflective interface for the projector image. This leads to another unwanted side image, also known as a layer ghost image or layer "ghost".

[0006] If the intermediate layer of the windshield is located between the conductive coating and the outer pane, the layer ghosting could also be avoided or reduced by a wedge-shaped design of the layer. However, to optimally prevent the ghosting caused by the two glass surfaces, different wedge angles would be required, meaning the result cannot be ideal but must always represent a compromise. Therefore, one object of the invention is to provide an improved laminated windshield for a head-up display that effectively reduces both types of ghosting.

[0007] The radiation from a HUD projector is typically predominantly s-polarized due to the windshield's superior reflective properties compared to p-polarization. However, if the driver is wearing polarization-selective sunglasses that only transmit p-polarized light, they will barely be able to perceive the HUD image, or not at all. Therefore, there is a need for HUD projection systems that are compatible with polarization-selective sunglasses.

[0008] German patent DE 10 2014 220 189 A1 discloses a HUD projection arrangement that uses p-polarized radiation to generate a HUD image that is also perceptible with polarization-selective sunglasses. Since the angle of incidence is typically close to the Brewster angle and p-polarized radiation is therefore only minimally reflected by the glass surfaces, the windshield has a reflective structure that can reflect p-polarized radiation towards the driver. One proposed reflective structure is a single metallic layer with a thickness of 5 nm to 9 nm, for example, made of silver or aluminum. While the p-polarized HUD image can be perceived by drivers with and without polarization-selective sunglasses, it is primarily reflected by the metallic layer and not significantly by the glass surfaces. This limits the intensity of the HUD image.

[0009] Therefore, there is also a need to provide improved projection arrangements for HUDs, using composite lenses with an electrically conductive coating, where the projection is also clearly perceptible to drivers wearing polarization-selective sunglasses and has a high intensity.

[0010] The object of the present invention is achieved according to the invention by a composite disk according to claim 1. Preferred embodiments are described in the dependent claims.

[0011] The advantages of the composite screen according to the invention are based on the combination of an anti-reflective coating and a wedge film. This gives the composite screen two independent features for preventing ghosting. The anti-reflective coating effectively suppresses reflection from the inner surface, so that the HUD projection is only significantly reflected from the outer surface. This avoids or at least reduces ghosting caused by the two screen surfaces. The wedge film allows the HUD images, which are created by reflections from the outer surface of the screen and the electrically conductive coating, to be superimposed or approximated, thus avoiding or at least reducing the layer ghosting. Overall, the occurrence of ghosting is therefore significantly reduced compared to conventional composite screens.

[0012] Unlike conventional composite lenses for HUDs, where the wedge-shaped intermediate layer serves to superimpose the reflections of the two external lens surfaces, the thickness of the inner lens has no influence on the calculation of the ideal wedge angle. The thickness of the inner lens can therefore be changed without requiring an adjustment of the wedge angle. This is a further advantage of the invention.

[0013] The composite pane according to the invention comprises an outer pane and an inner pane bonded together via a thermoplastic interlayer. The composite pane is intended to separate the interior from the external environment in a window opening, particularly the window opening of a vehicle. For the purposes of the invention, the term "inner pane" refers to the pane of the composite pane facing the interior (especially the vehicle interior). The term "outer pane" refers to the pane facing the external environment. The composite pane is preferably a vehicle windshield (in particular, the windshield of a motor vehicle, for example, a passenger car or truck).

[0014] The composite disc has a top edge and a bottom edge, as well as two side edges running between them. The top edge is the edge that is intended to point upwards when installed. The bottom edge is the edge that is intended to point downwards when installed. The top edge is often also referred to as the roof edge and the bottom edge as the motor edge.

[0015] The outer pane and the inner pane each have an outer and an inner surface, and a circumferential side edge running between them. For the purposes of the invention, the outer surface is defined as the main surface intended to face the external environment when installed. The inner surface is defined as the main surface intended to face the interior when installed. The inner surface of the outer pane and the outer surface of the inner pane face each other and are connected by the thermoplastic intermediate layer.

[0016] The laminated windscreen features a so-called HUD area. The HUD area is the area that can be illuminated by a projector. The HUD area is specifically designed to be illuminated by a projector to generate the HUD image. The light is reflected towards the viewer (driver), creating a virtual image that the viewer perceives behind the windscreen.

[0017] The intermediate layer of the composite disc is formed by at least one layer of thermoplastic material. This intermediate layer can consist of a single layer of thermoplastic material, such as a single polymer film or cast resin layer. Alternatively, the intermediate layer can comprise multiple layers of thermoplastic material, such as several polymer films arranged on top of each other.

[0018] The composite disc also features an electrically conductive coating. This coating is preferably applied to the outer surface of the inner disc facing the interlayer. Alternatively, the coating can be located within the interlayer. For this purpose, the coating is typically applied to a carrier film, for example, made of polyethylene terephthalate (PET) with a thickness of approximately 50 µm, which is sandwiched between two layers of thermoplastic material, for example, between two polymer films.

[0019] In every case, a layer of thermoplastic material is positioned between the electrically conductive coating and the outer pane. This layer of thermoplastic material is partially or completely designed as a so-called wedge film. The thickness of this thermoplastic layer varies vertically between the bottom and top edges of the laminated pane, at least in the HUD area, and in particular increases monotonically. However, the thickness can also vary along its entire vertical path, especially increasing monotonically from the bottom edge to the top edge. The term "vertical path" refers to the path between the bottom and top edges with a direction essentially perpendicular to these edges. The angle between the two surfaces of the interlayer is called the wedge angle. If the wedge angle is not constant, the tangents to the surfaces must be used to measure it at a given point.

[0020] The intermediate layer is wedge-shaped or wedge-like, at least in the HUD area. The wedge angle can be constant along the vertical axis, resulting in a linear change in the thickness of the intermediate layer, with the thickness typically increasing from bottom to top. The direction "from bottom to top" refers to the direction from the bottom edge to the top edge, i.e., the vertical path. However, more complex thickness profiles are also possible, in which the wedge angle varies from bottom to top (i.e., is location-dependent along the vertical path), either linearly or non-linearly.

[0021] Statt einer Keilfolie in der Zwischenschicht kann grundsätzlich auch eine keilartige Außenscheibe zum Einsatz kommen, um die Reflexionsflächen gegeneinander anzuwinkeln.

[0022] The wedge angle is appropriately chosen to superimpose, or at least reduce the distance between, the projected images caused by reflections from the electrically conductive coating on the one hand and the outer surface of the outer pane on the other. Due to the wedge angle, the outer pane and the conductive coating are not parallel to each other and enclose precisely this wedge angle. In the case of parallel reflective surfaces, the image (generated by reflection from the outer surface of the outer pane) and the ghost image (generated by reflection from the conductive coating) would appear offset from each other, which is distracting for the viewer. The wedge angle essentially superimposes the ghost image spatially with the image, so that the viewer perceives only a single image or at least reduces the distance between the image and the ghost image.

[0023] In conventional composite displays for HUDs, a wedge-shaped film is used to superimpose the HUD images due to reflections off the display surfaces. Typical wedge angles range from 0.3 mrad to 0.7 mrad, and particularly from 0.4 mrad to 0.5 mrad. Since the distance between the reflective surfaces is smaller in this case, smaller wedge angles are required than in conventional composite displays. Wedge films with smaller wedge angles are simpler and less expensive to manufacture.

[0024] The composite lens also features an anti-reflective coating applied to the inner surface of the inner lens, facing away from the intermediate layer. This anti-reflective coating significantly reduces the reflection of the projector's radiation from the inner surface, so that no HUD image, or at least no perceptible one, is generated by this reflection. The anti-reflective coating is preferably formulated to be particularly effective against radiation in the wavelength range used by the projector.

[0025] Antireflection coatings can be designed in various ways. For example, antireflection coatings made of porous silicon dioxide layers are known, as are those produced by etching a glass surface into a skeleton. In a preferred embodiment, however, the antireflection coating is formed from alternating layers with different refractive indices, which, due to interference effects, lead to a reduction in reflection at the coated surface. Such coatings are very effective and can be readily optimized for specific applications by selecting the appropriate materials and layer thicknesses.

[0026] The antireflective coating preferably comprises at least two optically high-refractive-index layers, particularly with a refractive index greater than 1.8, and two optically low-refractive-index layers, particularly with a refractive index less than 1.8. Starting from the substrate (the inner disk), a first high-refractive-index layer is arranged, followed by a first low-refractive-index layer, then a second high-refractive-index layer, and finally a second low-refractive-index layer. The high-refractive-index layers can be based, for example, on silicon nitride, tin-zinc oxide, silicon zirconium nitride, or titanium oxide, while the low-refractive-index layers can be based on silicon dioxide.

[0027] The electrically conductive coating is, in particular, a transparent, electrically conductive coating. The conductive coating can, for example, be provided as an IR-reflective solar control coating or as a heatable coating that is electrically contacted and heats up when an electric current flows through it. A transparent coating is understood to be a coating that has an average transmission in the visible spectral range of at least 70%, preferably at least 80%, and thus does not significantly restrict the view through the pane. Preferably, at least 80% of the pane surface is provided with the coating according to the invention.In particular, the laminated glass pane is fully coated with the coating, with the exception of a surrounding edge area and optionally local areas that serve as communication, sensor, or camera windows to ensure the transmission of electromagnetic radiation through the laminated glass and are therefore not coated. The surrounding uncoated edge area, for example, has a width of up to 20 cm. It prevents direct contact between the coating and the surrounding atmosphere, thus protecting the coating inside the laminated glass pane from corrosion and damage.

[0028] The electrically conductive coating is preferably a layer stack or a layer sequence comprising one or more electrically conductive, in particular metal-containing, layers, wherein each electrically conductive layer is arranged between two dielectric layers or layer sequences. The coating is thus a thin-film stack with n electrically conductive layers and ( n + 1) dielectric layers or layer sequences, wherein n is a natural number and wherein a conductive layer and a dielectric layer or layer sequence alternately follow each lower dielectric layer or layer sequence. Such coatings are known as solar control coatings and heatable coatings, wherein the electrically conductive layers are typically silver-based. The conductive coating preferably comprises at least two electrically conductive layers, more preferably at least three electrically conductive layers, and most preferably at least four electrically conductive layers. The higher the number of conductive layers, the better the coating can be optimized with regard to a desired transmittance, color, or surface resistance.

[0029] The electrical conductivity of the coating is achieved through functional, electrically conductive layers. By dividing the total conductive material into several separate layers, each layer can be made thinner, thereby increasing the coating's transparency. Each electrically conductive layer preferably contains at least one metal or metal alloy, for example, silver, aluminum, copper, or gold, and is particularly preferably metal- or alloy-based, meaning it consists essentially of the metal or metal alloy apart from any dopants or impurities. Silver or a silver-containing alloy is preferably used. In an advantageous embodiment, the electrically conductive layer contains at least 90 wt.% silver, preferably at least 99 wt.% silver, and particularly preferably at least 99.9 wt.% silver.

[0030] According to the invention, dielectric layers or sequences of layers are arranged between the electrically conductive layers, as well as below the lowest conductive layer and above the uppermost conductive layer. Each dielectric layer or sequence of layers comprises at least one anti-reflective layer. The anti-reflective layers reduce the reflection of visible light and thus increase the transparency of the coated disk. The anti-reflective layers contain, for example, silicon nitride (SiN), silicon-metal mixed nitrides such as silicon zirconium nitride (SiZrN), aluminum nitride (AlN), or tin oxide (SnO). The anti-reflective layers may also contain dopants. The thickness of the individual anti-reflective layers is preferably from 10 nm to 70 nm.

[0031] The anti-reflective coatings can in turn be subdivided into at least two sub-layers, in particular into a dielectric layer with a refractive index less than 2.1 and an optically high-refractive-index layer with a refractive index greater than or equal to 2.1.

[0032] Preferably, at least one anti-reflective layer arranged between two electrically conductive layers is subdivided, and more preferably, each anti-reflective layer arranged between two electrically conductive layers is subdivided. Subdividing the anti-reflective layer results in lower surface resistance of the electrically conductive coating while maintaining high transmission and high color neutrality. The order of the two sublayers can be chosen arbitrarily, with the optically high-refractive-index layer preferably being arranged above the dielectric layer, which is particularly advantageous with regard to surface resistance. The thickness of the optically high-refractive-index layer is preferably from 10% to 99%, and more preferably from 25% to 75%, of the total thickness of the anti-reflective layer.

[0033] The optically high-refractive-index layer with a refractive index greater than or equal to 2.1 contains, for example, MnO, WO₃, Nb₂O₅, Bi₂O₃, TiO₂, Zr₃N₄, and / or Al₃, preferably a silicon-metal mixed nitride, such as silicon-aluminum mixed nitride, silicon-hafnium mixed nitride, or silicon-titanium mixed nitride, and particularly preferably silicon-zirconium mixed nitride (SiZrN). This is particularly advantageous with regard to the surface resistance of the electrically conductive coating. The silicon-zirconium mixed nitride preferably contains dopants. The layer of an optically high-refractive-index material can, for example, contain an aluminum-doped silicon-zirconium mixed nitride. The proportion of zirconium is preferably between 15 and 45 wt.%, and particularly preferably between 15 and 30 wt.%.

[0034] The dielectric layer with a refractive index of less than 2.1 preferably has a refractive index n between 1.6 and 2.1, particularly preferably between 1.9 and 2.1. The dielectric layer preferably contains at least one oxide, for example tin oxide, and / or a nitride, particularly preferably silicon nitride.

[0035] In a preferred embodiment, each anti-reflective layer arranged between two electrically conductive layers is subdivided into a dielectric layer with a refractive index less than 2.1 and an optically high-refractive-index layer with a refractive index greater than or equal to 2.1. The thickness of each anti-reflective layer arranged between two electrically conductive layers ranges from 15 nm to 60 nm. The anti-reflective layers above the uppermost electrically conductive layer and below the lowermost electrically conductive layer can also be subdivided, but are preferably designed as single layers and each have a thickness of 10 nm to 25 nm.

[0036] In an advantageous embodiment, one or more dielectric layer sequences have a first matching layer, preferably each dielectric layer sequence, arranged below an electrically conductive layer. The first matching layer is preferably arranged above the anti-reflective layer.

[0037] In an advantageous embodiment, one or more dielectric layer sequences have a smoothing layer, preferably each dielectric layer sequence arranged between two electrically conductive layers. The smoothing layer is arranged below one of the first matching layers, preferably between the anti-reflective layer and the first matching layer. The smoothing layer is particularly preferably in direct contact with the first matching layer. The smoothing layer optimizes, in particular smooths, the surface for a subsequently applied electrically conductive layer above it. An electrically conductive layer deposited on a smoother surface exhibits a higher transmittance with a simultaneously lower surface resistance. The thickness of a smoothing layer is preferably from 3 nm to 20 nm, particularly preferably from 4 nm to 12 nm.The smoothing layer preferably has a refractive index of less than 2.2.

[0038] The smoothing layer preferably contains at least one non-crystalline oxide. The oxide can be amorphous or partially amorphous (and thus partially crystalline), but is not fully crystalline. The non-crystalline smoothing layer has low roughness and thus forms an advantageously smooth surface for the layers to be applied above it. Furthermore, the non-crystalline smoothing layer improves the surface structure of the layer deposited directly above it, which is preferably the first matching layer. The smoothing layer can, for example, contain at least one oxide of one or more of the elements tin, silicon, titanium, zirconium, hafnium, zinc, gallium, and indium. The smoothing layer particularly preferably contains a non-crystalline mixed oxide. The smoothing layer most preferably contains a tin-zinc mixed oxide (ZnSnO). The mixed oxide may contain dopants.The smoothing layer can, for example, contain an antimony-doped tin-zinc mixed oxide. The mixed oxide preferably has a substoichiometric oxygen content. The tin content is preferably between 10 and 40 wt.%, particularly preferably between 12 and 35 wt.%.

[0039] In an advantageous embodiment, one or more dielectric layer sequences have a second matching layer, preferably each dielectric layer sequence, arranged above an electrically conductive layer. The second matching layer is preferably arranged below the anti-reflective layer.

[0040] The first and second matching layers improve the coating's surface resistance. The first and / or second matching layer preferably contains zinc oxide (ZnO) with δ ≤ 0.01. The first and / or second matching layer further preferably contains dopants. For example, the first and / or second matching layer can contain aluminum-doped zinc oxide (ZnO:Al). The zinc oxide is preferably deposited substoichiometrically with respect to oxygen to prevent a reaction of excess oxygen with the silver-containing layer. The layer thicknesses of the first and second matching layers are preferably from 3 nm to 20 nm, and particularly preferably from 4 nm to 12 nm.

[0041] In an advantageous embodiment, the electrically conductive coating comprises one or more blocker layers. Preferably, at least one, and more preferably each, electrically conductive layer is associated with at least one blocker layer. The blocker layer is in direct contact with the electrically conductive layer and is arranged directly above or directly below it. No further layer is arranged between the electrically conductive layer and the blocker layer. Alternatively, a blocker layer can be arranged directly above and directly below a conductive layer. The blocker layer preferably contains niobium, titanium, nickel, chromium, and / or alloys thereof, particularly nickel-chromium alloys. The thickness of the blocker layer is preferably from 0.1 nm to 2 nm, and more preferably from 0.1 nm to 1 nm.A blocker layer directly below the electrically conductive layer serves, in particular, to stabilize the electrically conductive layer during heat treatment and improves the optical quality of the electrically conductive coating. A blocker layer directly above the electrically conductive layer prevents contact between the sensitive electrically conductive layer and the oxidizing reactive atmosphere during the deposition of the subsequent layer by reactive cathode sputtering, for example, the second matching layer.

[0042] If a first layer is arranged above a second layer, this means, within the meaning of the invention, that the first layer is arranged further away from the substrate on which the coating is applied than the second layer. If a first layer is arranged below a second layer, this means, within the meaning of the invention, that the second layer is arranged further away from the substrate than the first layer. If a first layer is arranged above or below a second layer, this does not necessarily mean, within the meaning of the invention, that the first and second layers are in direct contact with each other. One or more further layers may be arranged between the first and second layers, unless this is explicitly excluded. The stated values ​​for refractive indices were measured at a wavelength of 550 nm.

[0043] The outer and inner panes are preferably made of glass, in particular soda-lime glass, which is common for window panes. However, the panes can also be made of other types of glass (for example, borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (for example, polymethyl methacrylate or polycarbonate). The thickness of the outer and inner panes can vary widely. Preferably, panes with a thickness in the range of 0.8 mm to 5 mm, more preferably from 1.4 mm to 2.5 mm, are used, for example, those with the standard thicknesses of 1.6 mm or 2.1 mm.

[0044] The outer pane, the inner pane, and the thermoplastic interlayer can be clear and colorless, or tinted or colored. In a preferred embodiment, the total transmission through the laminated glass is greater than 70%. The term "total transmission" refers to the procedure for testing the light transmittance of motor vehicle windows as specified in ECE-R 43, Annex 3, Section 9.1. The outer pane and the inner panes can be independently untempered, partially tempered, or tempered. If at least one of the panes is to have a temper, this can be thermal or chemical.

[0045] The laminated glass is preferably curved in one or more spatial directions, as is common for automotive windshields, with typical radii of curvature ranging from about 10 cm to about 40 m. However, the laminated glass can also be flat, for example, if it is intended as a windshield for buses, trains, or tractors.

[0046] The thermoplastic interlayer contains at least one thermoplastic polymer, preferably ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU), or mixtures, copolymers, or derivatives thereof, particularly preferably PVB. The interlayer is typically formed from a thermoplastic film. The thickness of the interlayer is preferably from 0.2 mm to 2 mm, particularly preferably from 0.3 mm to 1 mm. If a wedge-shaped interlayer is used, the thickness is determined at its thinnest point, typically at the bottom edge of the composite disc.

[0047] The laminated glass pane can be manufactured using methods known per se. The outer and inner panes are laminated together via the intermediate layer, for example by autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators, or combinations thereof. The bonding of the outer and inner panes typically occurs under the influence of heat, vacuum, and / or pressure.

[0048] The electrically conductive coating and the antireflective coating are preferably applied to the inner disc by physical vapor deposition (PVD), particularly preferably by sputtering, and most preferably by magnetically assisted sputtering. The coatings are preferably applied to the discs before lamination. Instead of applying the electrically conductive coating to a disc surface, it can also be provided on a carrier film that is placed in the intermediate layer.

[0049] If the laminated glass pane is to be curved, the outer and inner panes are preferably bent before lamination and preferably after any coating processes. Preferably, the outer and inner panes are bent congruently together (i.e., simultaneously and using the same tool) because this ensures that the shape of the panes is optimally matched for the subsequent lamination. Typical temperatures for glass bending processes are, for example, 500°C to 700°C.

[0050] The invention also includes the use of a composite screen according to the invention in a motor vehicle, preferably a passenger car, as a windscreen which serves as a projection surface for a head-up display.

[0051] The invention further comprises a projection arrangement for a head-up display (HUD). The projection arrangement includes at least one composite screen according to the invention and a projector directed at the HUD area of ​​the composite screen. The projector's beam direction can typically be varied by mirrors, particularly vertically, to adapt the projection to the viewer's height. The area in which the viewer's eyes must be located for a given mirror position is called the eyebox window. This eyebox window can be shifted vertically by adjusting the mirrors, with the entire area thereby accessible (i.e., the superposition of all possible eyebox windows) being called the eyebox. A viewer located within the eyebox can perceive the virtual image. This means, of course, that the viewer's eyes must be located within the eyebox, not their entire body.

[0052] The technical terms used here from the field of HUDs are generally known to experts. For a detailed explanation, please refer to the dissertation "Simulation-based measurement technology for testing head-up displays" by Alexander Neumann at the Institute of Computer Science of the Technical University of Munich (Munich: University Library of the Technical University of Munich, 2012), in particular to Chapter 2 "The Head-Up Display".

[0053] The projector's radiation preferably strikes the composite screen at an angle of incidence of 50° to 80°, particularly 60° to 70°, typically around 65°, as is common in HUD projection setups. The angle of incidence is the angle between the incident vector of the projector radiation and the surface normal at the geometric center of the HUD area.

[0054] Since the angle of incidence is close to the Brewster angle for an air-glass interface (57.2°, soda-lime glass), only s-polarized radiation is efficiently reflected by the lens surfaces. Conventional projectors therefore typically operate with purely s-polarized radiation. This poses a problem for drivers wearing polarization-selective sunglasses: they can perceive the HUD image poorly or not at all. To make the HUD image visible despite such sunglasses, an advantageous embodiment uses at least partially p-polarized radiation to generate the HUD image, preferably a mixture of s- and p-polarized radiation. S-polarized radiation components are efficiently reflected by the lens surfaces. The p-polarized radiation components are reflected by the electrically conductive coating, thus making the HUD image visible even to the wearer of polarization-selective sunglasses.For viewers without such sunglasses, the s- and p-polarized components add up, making the HUD image particularly intense.

[0055] The projector is positioned on the inner side of the composite glass and illuminates the composite glass via the inner surface of the inner pane. It is directed towards the HUD area and illuminates it to generate the HUD projection. The projector's radiation preferably has a p-polarized component > 0%. In principle, the p-polarized component can also be 100%, meaning the projector emits purely p-polarized radiation. However, for the overall intensity of the HUD, it is advantageous if the projector's radiation contains both s-polarized and p-polarized components. In this case, the p-polarized radiation components are efficiently reflected by the coating, and the s-polarized radiation components by the glass surfaces. The ratio of p-polarized to s-polarized radiation components can be freely selected according to the specific requirements.The proportion of p-polarized radiation in the total projector radiation is, for example, from 20% to 100%, preferably from 20% to 80%. In a particularly advantageous embodiment, the proportion of p-polarized radiation is at least 50%, i.e., from 50% to 100%, preferably from 50% to 80%, which ensures, in particular, that a driver wearing polarization-selective sunglasses can perceive a high-intensity image. The polarization direction is specified as the plane of incidence of the radiation on the composite lens. P-polarized radiation is defined as radiation whose electric field oscillates in the plane of incidence. S-polarized radiation is defined as 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 composite lens at the geometric center of the HUD area.

[0056] To increase the intensity of the HUD image, the electrically conductive coating is, in an advantageous embodiment, optimized for the reflection of p-polarized radiation. The electrically conductive coating according to the invention is configured, particularly through the selection of the materials and thicknesses of the individual layers as well as the structure of the dielectric layer sequences, such that only a single local reflection maximum for p-polarized radiation occurs in the spectral range from 400 nm to 650 nm, preferably in the spectral range from 400 nm to 750 nm. This reflection maximum for p-polarized radiation is located, in particular, in the spectral range from 510 nm to 550 nm.

[0057] The inventors recognized that such an electrically conductive coating efficiently reflects the p-polarized radiation components, and that the composite lens also exhibits a relatively neutral coloration in both transmission and reflection. With the coating formulated according to the invention, it is particularly possible to freely select the p-polarized radiation component according to the specific requirements of each case, while the coloration always remains relatively neutral. Thus, the p-polarized radiation components can be selected in each individual case, depending on the projector used, the wavelength of its radiation, the angle of incidence, and the geometry of the composite lens, in such a way as to achieve an advantageous overall intensity. The invention is therefore flexibly applicable to various HUD systems, which represents a significant advantage.

[0058] Crucial for the properties of the projection setup is the reflection behavior of the composite disk, which is largely determined by the electrically conductive coating. The reflection spectrum is measured on the composite disk with both the electrically conductive coating and the antireflection coating. More precisely, the reflection properties described here for p- or s-polarized radiation (reflectivity, local reflection maxima) do not refer to the isolated electrically conductive coating, but rather to the composite disk with both the electrically conductive coating and the antireflection coating.

[0059] 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 dimensionless number from 0 to 1 (normalized to the incident radiation). Plotted as a function of wavelength, it forms the reflection spectrum.

[0060] In an advantageous embodiment, the difference between the reflectance for p-polarized radiation occurring at the local reflection maximum in the spectral range of 400 nm to 650 nm and the minimum reflectance for p-polarized radiation occurring in the same spectral range is at most 10%, preferably at most 8%. The reflection curve is then relatively flat, which is advantageous for achieving the most accurate color reproduction of the projector image. The percentages given here represent the absolute difference in reflectance (relative to 100% incident radiation).

[0061] The reflection spectrum for s-polarized radiation should also be as flat as possible, i.e., without pronounced maxima and minima, particularly in the spectral range of 450 nm and 600 nm. If the reflection spectra for both polarization directions are sufficiently flat, the relative proportions of s-polarized and p-polarized radiation can advantageously be freely chosen without introducing an undesirable color shift. In an advantageous embodiment, the reflectance for s-polarized radiation is essentially constant in the spectral range from 450 nm to 600 nm.

[0062] In the context of the invention, this means that the difference between the maximum observed reflectance and the mean value, as well as the difference between the minimum observed reflectance and the mean value, is at most 5%, preferably at most 3%, and particularly preferably at most 1%. The percentages here indicate the absolute difference in reflectance (relative to 100% incident radiation).

[0063] The electrically conductive coating with the preferred reflective characteristics can, in principle, be realized in various ways, preferably using the layers described above, so that the invention is not limited to a specific layer sequence. A particularly preferred embodiment of the coating is presented below, with which especially good results are achieved, particularly at a typical angle of incidence of the radiation of approximately 65°.

[0064] In a particularly preferred embodiment, the conductive coating comprises at least four, and in particular exactly four, electrically conductive layers. Each electrically conductive layer preferably has a thickness of 3 nm to 20 nm, and more preferably of 5 nm to 15 nm. The total thickness of all electrically conductive layers is preferably of 20 nm to 50 nm, and more preferably of 30 nm to 40 nm.

[0065] The anti-reflective layer between the second and third conductive layers is significantly thicker (preferably 45 nm to 55 nm) than the anti-reflective layers between the first and second conductive layers and between the third and fourth conductive layers (preferably 15 nm to 35 nm, with one of the two anti-reflective layers having a thickness of 15 nm to 25 nm and the other a thickness of 25 nm to 35 nm). The anti-reflective layer between the first and second electrically conductive layers particularly preferably has a thickness of 25 nm to 35 nm. The anti-reflective layer between the second and third electrically conductive layers particularly preferably has a thickness of 45 nm to 55 nm. The anti-reflective layer between the third and fourth electrically conductive layers particularly preferably has a thickness of 15 nm to 25 nm.

[0066] All anti-reflective coatings arranged between two electrically conductive layers are, as described above, divided into a dielectric layer with a refractive index less than 2.1 (preferably based on silicon nitride) and an optically high-refractive-index layer with a refractive index greater than or equal to 2.1 (preferably based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride). Preferably, the optically high-refractive-index layer accounts for 25% to 75% of the total thickness of the anti-reflective coatings.

[0067] The anti-reflective layers below the lowest conductive layer and above the uppermost conductive layer are formed as single layers with a thickness of 10 nm to 25 nm. Preferably, the anti-reflective layer below the lowest conductive layer is based on silicon nitride with a thickness of 15 nm to 25 nm, and the anti-reflective layer above the uppermost conductive layer is based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of 8 nm to 18 nm.

[0068] The particularly preferred embodiment of the coating also includes adaptation layers and smoothing layers, as well as optional blocker layers, as described above.

[0069] A particularly preferred embodiment of the electrically conductive coating contains, or consists of, the following layer sequence starting from the substrate: an anti-reflective layer based on silicon nitride with a thickness of 20 nm to 23 nm, a first matching layer based on zinc oxide with a thickness of 8 nm to 12 nm, an electrically conductive layer based on silver with a thickness of 8 nm to 11 nm, optionally a blocking layer based on NiCr with a thickness of 0.1 nm to 0.5 nm, a second matching layer based on zinc oxide with a thickness of 8 nm to 12 nm, an anti-reflective layer with a thickness of 28 nm to 32 nm, preferably subdivided into a dielectric layer based on silicon nitride with a thickness of 14 nm to 17 nm and an optically high-refractive-index layer based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of 14 nm to 17 nm, a smoothing layer based on tin-zinc mixed oxide with a thickness of 5 nm to 9 nm, a first Zinc oxide-based adaptation layer with a thickness of 8 nm to 12 nm,an electrically conductive layer based on silver with a thickness of 11 nm to 14 nm, optionally a blocking layer based on NiCr with a thickness of 0.1 nm to 0.5 nm, a second matching layer based on zinc oxide with a thickness of 8 nm to 12 nm, an anti-reflective layer with a thickness of 48 nm to 52 nm, preferably subdivided into a dielectric layer based on silicon nitride with a thickness of 33 nm to 37 nm and an optically high-refractive-index layer based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of 14 nm to 17 nm, a smoothing layer based on tin-zinc mixed oxide with a thickness of 5 nm to 9 nm, a first matching layer based on zinc oxide with a thickness of 8 nm to 12 nm, an electrically conductive layer based on silver with a thickness of 8 nm to 11 nm, optionally a Blocking layer based on NiCr with a thickness of 0.1 nm to 0.5 nm,a second matching layer based on zinc oxide with a thickness of 8 nm to 12 nm, an anti-reflective layer with a thickness of 18 nm to 22 nm, preferably subdivided into a dielectric layer based on silicon nitride with a thickness of 4 nm to 7 nm and an optically high-refractive-index layer based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of 14 nm to 17 nm, a smoothing layer based on tin-zinc mixed oxide with a thickness of 5 nm to 9 nm, a first matching layer based on zinc oxide with a thickness of 8 nm to 12 nm, an electrically conductive layer based on silver with a thickness of 4 nm to 7 nm, optionally a blocker layer based on NiCr with a thickness of 0.1 nm to 0.5 nm, a second matching layer based on zinc oxide with a thickness of 8 nm to 12 nm,an anti-reflective coating based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of 11 nm to 15 nm, ,

[0070] If a layer is formed based on a material, the layer consists predominantly of this material, along with any impurities or dopants.

[0071] The presence of the antireflection coating affects the reflection behavior of the composite disk. The antireflection coating is preferably adjusted, particularly by suitable selection of materials and layer thicknesses, so that the composite disk with the electrically conductive coating and the antireflection coating meets the preferred requirements for reflection behavior, i.e., in particular, exhibits only a single local reflection maximum for p-polarized radiation in the spectral range from 400 nm to 650 nm, which is located in the range from 510 nm to 550 nm. The preferred embodiments described above apply accordingly.

[0072] In a particularly preferred embodiment, with which good results are achieved, the anti-reflective coating, starting from the substrate (i.e. the interior surface of the inner pane), comprises the following layers: a layer (high-refractive index layer) based on silicon nitride, tin-zinc oxide, silicon-zirconium nitride or titanium oxide, preferably silicon nitride, with a thickness of 15 nm to 25 nm, preferably from 18 nm to 22 nm; a layer (low-refractive index layer) based on silicon dioxide with a thickness of 15 nm to 25 nm, preferably from 18 nm to 22 nm; a layer (high-refractive index layer) based on silicon nitride, tin-zinc oxide, silicon-zirconium nitride or titanium oxide, preferably silicon nitride, with a thickness of 90 nm to 110 nm, preferably from 95 nm to 105 nm; a layer (low-refractive index layer) based on silicon dioxide with a thickness of 80 nm to 100 nm, preferably from 85 nm to 95 nm.

[0073] The invention is explained in more detail below with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way.

[0074] They show: Fig. 1 shows a cross-section through a composite disk according to the invention, Fig. 2 shows the composite disk of the Figure 1 as part of a HUD projection setup, Fig. 3 shows a top view of the composite screen of the Figures 1 and 2 Fig. 4 shows a cross-section through a preferred electrically conductive coating, Fig. 5 shows a cross-section through a preferred antireflective coating, Fig. 6 shows reflection spectra of a composite disk with an electrically conductive coating according to Figure 4 and a composite disc with a conventional electrically conductive coating.

[0075] Fig. 1Figure 1 shows an embodiment of a composite glass pane 10 according to the invention, which is intended as a windshield for a passenger car. The composite glass pane 10 consists of an outer pane 1 and an inner pane 2, which are bonded together via a thermoplastic intermediate layer 3. In its installed position, the outer pane 1 faces the external environment, and the inner pane 2 faces the vehicle interior. The outer pane 1 has an outer surface I, which in its installed position faces the external environment, and an inner surface II, which in its installed position faces the interior. Similarly, the inner pane 2 has an outer surface III, which in its installed position faces the external environment, and an inner surface IV, which in its installed position faces the interior. The lower edge U of the composite glass pane 10 is arranged downwards in the direction of the passenger car's engine, and its upper edge O is arranged upwards in the direction of the roof.

[0076] The outer pane 1 and the inner pane 2 are made of, for example, soda-lime glass. The outer pane 1 has a thickness of, for example, 2.1 mm, and the inner pane 2 a thickness of 1.6 mm. The intermediate layer 3 consists of a single layer 3a of thermoplastic material, for example, a PVB film with a thickness of 0.76 mm (measured at the bottom edge U). The intermediate layer 3 is wedge-shaped with a wedge angle α, so that the thickness of the intermediate layer 3, and thus of the entire laminated pane 10, increases from bottom to top.

[0077] The laminated pane 10 also includes an electrically conductive coating 20, which is applied to the outer surface III of the inner pane 2 and is designed, for example, as an IR-reflective coating or as a heatable coating. The laminated pane also includes an anti-reflective coating 30, which is applied to the inner surface IV of the inner pane 2.

[0078] Fig. 2 Figure 1 shows a projection arrangement according to the invention for a HUD. The projection arrangement comprises, in addition to the composite screen 10, a Figure 1A projector 4 is directed at an area B of the composite screen 10. In area B, which is usually referred to as the HUD area, the projector 4 can generate images which are perceived by a viewer 5 (vehicle driver) as virtual images on the side of the composite screen 10 facing away from him, when his eyes are within the so-called eyebox E.

[0079] In typical projection setups, the projector's radiation 4 is partially reflected by the inner surface IV of the inner pane 1 (primary reflection) and by the outer surface I of the outer pane 1 (secondary reflection). With a conventional laminated glass pane 10, these two reflections result in two offset HUD projections (a main image and a so-called ghost image), which is distracting for the viewer 5. The anti-reflective coating 30 drastically reduces the reflection from the inner surface IV of the inner pane 1. As far as the glass surfaces are concerned, only the outer surface I of the outer pane 1 contributes to the generated HUD image. No ghost image, or only a barely perceptible one, occurs as a result of the two external glass surfaces I and IV.

[0080] The electrically conductive coating 20 on the outer surface II of the inner pane 2 represents an additional reflective surface for the projector's radiation 4. With conventional laminated panes with parallel surfaces, this would also result in a ghost image. To avoid or at least reduce this, the intermediate layer 3 is wedge-shaped. The thickness of the intermediate layer 3 increases steadily in the vertical direction from the lower edge U to the upper edge O. For simplicity, the increase in thickness is shown linearly in the figures, but it can also have more complex profiles. The wedge angle α describes the angle between the two surfaces of the intermediate layer and is, for example, approximately 0.5 mrad. Due to the wedge-shaped intermediate layer, which results in an angled arrangement of the two reflective surfaces I, 20, the main image and ghost image are ideally superimposed precisely, or at least their separation is reduced.

[0081] Fig. 3 shows a top view of the composite disc 10 made of Figure 1 The upper edge O, the lower edge U, and the HUD area B are clearly visible.

[0082] The radiation from projector 4 comprises a mixture of s-polarized and p-polarized components. Since projector 4 illuminates the composite disk 10 at an angle of incidence of approximately 65°, which is close to Brewster's angle, the surfaces of the composite disk 10 predominantly reflect the s-polarized radiation components. The electrically conductive coating 20, on the other hand, is optimized for reflecting the p-polarized radiation components. A viewer 5 wearing polarization-selective sunglasses, which only allow p-polarized radiation to pass through, can therefore perceive the HUD projection. This is not the case with conventional projection setups that only use s-polarized radiation. A viewer 5 without sunglasses sees the sum of s-polarized and p-polarized radiation, so the intensity of the HUD projection is not reduced for them.

[0083] The coating 20 is particularly optimized for the reflection of p-polarized radiation if it has only a single local reflection maximum for p-polarized radiation in the spectral range from 400 nm to 650 nm, which is located in the range from 510 nm to 550 nm.

[0084] Fig. 4Figure 1 shows the layer sequence of an embodiment of the electrically conductive coating 20, which is optimized for the reflection of p-polarized radiation. The coating 20 contains four electrically conductive layers 21 (21.1, 21.2, 21.3, 21.4). Each electrically conductive layer 21 is arranged between two of a total of five anti-reflective layers 22 (22.1, 22.2, 22.3, 22.4, 22.5). The anti-reflective layers 22.2, 22.3, 22.4, which are arranged between two electrically conductive layers 21, are each subdivided into a dielectric layer 22a (22a.2, 22a.3, 22a.4) and an optically high-refractive-index layer 22b (22b.2, 22b.3, 22b.4). The coating 20 also contains three smoothing layers 23 (23.2, 23.3, 23.4), four first adaptation layers 24 (24.1, 24.2, 24.3, 24.4), four second adaptation layers 25 (25.2, 25.3, 25.4, 25.5) and four blocker layers 26 (26.1, 26.2, 26.3, 26.4).

[0085] The layer sequence is shown schematically in the figure. The layer sequence of a composite disc 10 with the coating 20 on the outer surface III of the inner disc 2 is also shown in Table 1 (example), along with the materials and layer thicknesses of the individual layers. Table 1 also shows the layer sequence of an electrically conductive coating, as currently in use (comparative example). It can be seen that the preferred reflection properties of the coating 20 were achieved by appropriately optimizing the layer thicknesses of the individual layers.

[0086] Fig. 5Figure 1 shows the layer sequence of an antireflection coating 30, comprising two high-refractive-index layers 31 (31.1, 31.2) and two low-refractive-index layers 32 (32.1, 32.2). The layer sequence is shown schematically in the figure. The layer sequence of a composite disk 10 according to the invention, with the electrically conductive coating 20 on the outer surface III of the inner disk 2 and the antireflection coating 30 on the inner surface IV of the inner disk 2, is also shown in Table 2, along with the materials and layer thicknesses of the individual layers. The antireflection coating 30 is designed such that it does not significantly shift the reflection spectrum of the composite disk 10 for p-polarized radiation, so that the preferred properties with respect to p-polarized radiation are retained. Table 1 material Reference sign Layer thickness Example comparative example Glass 1 2.1 mm 2.1 mm PVB 3 0.76 mm 0.76 mm SiZrN 20 22.5 12.3 nm 25.2 nm ZnO 25.5 10.0 nm 10.0 nm NiCr 26.4 0.2 nm 0.2 nm AG 21.4 5.3 nm 14.1 nm ZnO 24.4 10.0 nm 10.0 nm SnZnO:Sb 23.4 7.0 nm 7.0 nm SiZrN 22b.4 22.4 15,0 22.9 nm SiN 22a.4 5.2 nm 29.8 nm ZnO 25.4 10.0 nm 10.0 nm NiCr 26.3 0.2 nm 0.2 nm AG 21.3 9.6 nm 14.2 nm ZnO 24.3 10.0 nm 10.0 nm SnZnO:Sb 23.3 7.0 nm 7.0 nm SiZrN 22b.3 22.3 15.0 nm 20.1 nm SiN 22a.3 35.1 nm 29.6 nm ZnO 25.3 10.0 nm 10.0 nm NiCr 26.2 0.2 nm 0.2 nm AG 21.2 12.4 nm 17.1 nm ZnO 24.2 10.0 nm 10.0 nm SnZnO:Sb 23.2 7.0 nm 7.0 nm SiZrN 22b.2 22.2 15.0 nm 19.4 nm SiN 22a.2 15.5 nm 34.1 nm ZnO 25.2 10.0 nm 10.0 nm NiCr 26.1 0.2 nm 0.2 nm AG 21.1 9.5 nm 11.7 nm ZnO 24.1 10.0 nm 10.0 nm SiN 22.1 21.2 nm 28.8 nm Glass 2 1.6 mm 1.6 nm Table 2 material Reference sign Layer thickness SiO 30 32.2 92.7 nm SiN 31.2 102.2 nm SiO 32.1 20.5 nm SiN 31.1 19.9 nm Glass 2 1.6 mm 20 (see Table 1) PVB 3 0.76 mm Glass 1 2.1 mm

[0087] Fig. 6 Figure 1 shows the reflection spectrum of a composite disk 10 with a conventional conductive coating 20 according to the comparison example and a preferred conductive coating 20 according to the example (see Table 1) for p-polarized radiation (part a) and for s-polarized radiation (part b). The spectra were measured on the interior side at an angle of incidence of 65°, thus representing the reflection behavior for the HUD projector.

[0088] The conventional coating, as used in the comparative example, exhibits two local reflection maxima for p-polarized radiation in the spectral range of 400 nm to 650 nm: at 476 nm and at 600 nm. The difference between the reflectance of the local reflection maximum and the minimum reflectance for p-polarized radiation in the spectral range of 400 nm to 650 nm is significantly more than 10%.

[0089] In contrast, the preferred coating according to the example exhibits only a single local reflection maximum for p-polarized radiation in the spectral range from 400 nm to 650 nm. This local reflection maximum is located at 516 nm, i.e., in the green spectral range to which the human eye is particularly sensitive. The difference between the reflectance of the local reflection maximum and the minimum reflectance for p-polarized radiation in the spectral range from 400 nm to 650 nm is only 6.7%.

[0090] Even for s-polarized radiation, the reflection spectrum of the preferred coating is significantly flatter than that of the conventional coating in the spectral range of 450 nm to 600 nm. The difference between the maximum observed reflectance and the mean value is 0.4%, and the difference between the minimum observed reflectance and the mean value is 0.3%.

[0091] The preferred coating design of the example produces a HUD image with neutral color. Furthermore, the relative proportions of s-polarized and p-polarized radiation can be freely selected without any color shift or other undesirable effects. The radiation proportions can therefore be adjusted according to the specific requirements of each case, without the coating imposing any limitations on the user. A ratio can be set to achieve optimal HUD projection intensity for drivers both with and without polarization-selective sunglasses.

[0092] Table 3 shows the overall reflectance for different polarization fractions of the projector radiation, firstly for a conventional laminated lens (coating 20 as specified in Table 1 under Comparative Example, no antireflective coating 30), and secondly for a laminated lens according to the invention (coating 20 as specified in Table 1 under Example, structure with antireflective coating 30 as specified in Table 2). It is clearly evident that the reflectance for p-polarized radiation (perceived by a viewer wearing polarization-selective sunglasses) is significantly increased at any given polarization ratio. The reflectance for s- and p-polarized radiation (perceived by a viewer without polarization-selective sunglasses) is also increased from a p-polarization fraction of 50%. Overall, this results in a more intense image. Table 3 Radiation components of the projector radiation Total reflectance / % comparative example Example P s s+p p s+p p 0 100 33,1 0 26,4 0,0 10 90 30,5 0,7 25,4 1,6 20 80 27,9 1,4 24,4 3,3 30 70 25,3 2,1 23,4 4,9 40 60 22,7 2,8 22,4 6,6 50 50 20,1 3,5 21,4 8,2 60 40 17,4 4,2 20,4 9,8 70 30 14,8 4,9 19,4 11,5 80 20 12,2 5,6 18,4 13,1 90 10 9,6 6,3 17,4 14,8 100 0 7,0 7,0 16,4 16,4 Reference symbol list:

[0093] (10) Laminated glass (1) Outer pane (2) Inner pane (3) Thermoplastic interlayer (3a) Layer of thermoplastic material of the interlayer (4) Projector (5) Viewer / Vehicle driver (20) Electrically conductive coating (21) Electrically conductive layer (21.1), (21.2), (21.3), (21.4) 1st, 2nd, 3rd, 4th electrically conductive layer (22) Anti-reflective coating (22.1), (22.2), (22.3), (22.4), (22.5) 1st, 2nd, 3rd, 4th, 5th anti-reflective coating (22a) Dielectric layer of anti-reflective coating 4 (22a.2), (22a.3), (22a.4) 1st, 2nd, 3rd dielectric layer (22b) Optically high refractive index layer of anti-reflective coating 4 (22b.2), (22b.3), (22b.4) 1st, 2nd, 3rd optically high-refractive-index layer (23) Smoothing layer (23.2), (23.3), (23.4) 1st, 2nd, 3rd smoothing layer (24) First matching layer (24.1), (24.2), (24.3), (24.4) 1st, 2nd, 3rd, 4th first matching layer (25) Second matching layer (25.2), (25.3), (25.4), (25.5) 1st, 2nd, 3rd, 4th second matching layer (26) Blocker layer (26.1), (26.2), (26.3), (26.4) 1st, 2nd, 3rd, 4th blocker layer (30) Anti-reflective coating (31) High-refractive-index layer of the anti-reflective coating 30 (31.1), (31.2) 1st, 2nd high-refractive-index layer (32) Low-refractive-index layer of the anti-reflective coating 30 (32.1), (32.2) 1st, 2nd low-refractive-index layer (O) Top edge of the laminated pane 10 (U) Bottom edge of the laminated pane 10 (B) HUD area of ​​the laminated pane 10 (E) Eyebox (I) Outer surface of the outer pane 1 facing away from the intermediate layer 3 (II) Inner surface of the outer pane 1 facing towards the intermediate layer 3 (III) Outer surface of the inner pane 2 facing towards the intermediate layer 3 (IV) Inner surface of the Inner disc 2 α wedge angle.

Claims

1. Composite pane (10) for a head-up display with an upper edge (O), a lower edge (U), and an HUD region (B), at least comprising an outer pane (1) and an inner pane (2), which are joined to one another by a thermoplastic intermediate layer (3), and a transparent, electrically conductive coating (20) on the surface (III) of the inner pane (2) facing the intermediate layer (3) or within the intermediate layer (3), - wherein the intermediate layer (3) is formed by at least one ply (3a) of thermoplastic material, which is arranged between the electrically conductive coating (20) and the outer pane (1), - wherein the thickness of the ply (3a) of thermoplastic material is variable with a wedge angle (α) over its vertical course between the lower edge (U) and the upper edge (O) at least in the HUD region (B), and - wherein an anti-reflective coating (30) is applied on the surface (IV) of the inner pane (2) facing away from the intermediate layer (3).

2. Composite pane (10) according to claim 1, wherein the wedge angle (α) is suitable for superimposing the reflections at the electrically conductive coating (20) and at the exterior-side surface (I) of the outer pane (1) or for at least reducing the distance between them.

3. Composite pane (10) according to claim 1 or 2, wherein the electrically conductive coating (20) includes at least two, preferably at least three, particularly preferably at least four electrically conductive layers (21), which are in each case arranged between two dielectric layers or layer sequences.

4. Composite pane (10) according to one of claims 1 through 3, wherein the anti-reflective coating (30) is formed from alternatingly arranged layers with different refractive indices.

5. Projection arrangement for a head-up display (HUD), at least comprising - a composite pane (10) according to one of claims 1 through 4, and - a projector (4) that is aimed at the HUD region (B).

6. Projection arrangement according to claim 5, wherein the light of the projector (4) has at least one p-polarised component, and wherein the composite pane (10) has, in the spectral range from 400 nm to 650 nm, only a single local reflection maximum for p-polarised light, which is in the range from 510 nm to 550 nm.

7. Projection arrangement according to claim 6, wherein, in the spectral range from 400 nm to 650 nm, the difference between the reflectance of the local reflection maximum and the minimally occurring reflectance for p-polarised light is at most 10%, preferably at most 8%.

8. Projection arrangement according to claim 6 or 7, wherein the reflectance for s-polarised light in the spectral range from 450 nm to 600 nm is substantially constant such that the difference between the maximally occurring reflectance and the mean as well as the difference between the minimally occurring reflectance and the mean are at most 5%, preferably at most 3%, particularly preferably at most 1%.

9. Projection arrangement according to one of claims 5 through 8, wherein the proportion of p-polarised light in the total light of the projector (4) is from 20% to 80%, particularly preferably from 50% to 80%.

10. Projection arrangement according to one of claims 5 through 9, wherein the electrically conductive coating (20) includes at least four electrically conductive layers (21), which are in each case arranged between two dielectric layers or layer sequences.

11. Projection arrangement according to claim 10, wherein the electrically conductive layers (21) are based on silver and have, in each case, a layer thickness from 5 to 15 nm, wherein the total layer thickness of all electrically conductive layers (21) is from 20 nm to 50 nm.

12. Projection arrangement according to claim 10 or 11, wherein each dielectric layer sequence includes an anti-reflective layer (22), and wherein - the anti-reflective layer (22.1) below the first electrically conductive layer (21.1) has a thickness from 15 nm to 25 nm, - the anti-reflective layer (22.2) between the first and the second electrically conductive layer (21.1, 21.2) has a thickness from 25 to 35 nm, - the anti-reflective layer (22.3) between the second and the third electrically conductive layer (21.2, 21.3) has a thickness from 45 nm to 55 nm, - the anti-reflective layer (22.4) between the third and the fourth electrically conductive layer (21.3, 21.4) has a thickness from 15 nm to 25 nm, and - the anti-reflective layer (22.5) above the fourth electrically conductive layer (21.4) has a thickness from 8 nm to 18 nm.

13. Projection arrangement according to one of claims 10 through 12, wherein all anti-reflective layers (22.2, 22.3, 22.4) that are arranged between two electrically conductive layers (21) are divided into a dielectric layer (22a) having a refractive index smaller than 2.1, preferably based on silicon nitride, and an optically high refractive layer (22b) having a refractive index greater than or equal to 2.1, preferably based on a mixed silicon / metal nitride such as silicon-zirconium nitride or silicon-hafnium nitride.

14. Projection arrangement according to one of claims 5 through 13, wherein the anti-reflective coating (30) includes the following layers, starting from the inner pane (2): - a high refractive layer (31.1) based on silicon nitride with a thickness from 15 nm to 25 nm, preferably from 18 nm to 22 nm, - a low refractive layer (32.1) based on silicon dioxide with a thickness from 15 nm to 25 nm, preferably from 18 nm to 22 nm, - a high refractive layer (31.2) based on silicon nitride with a thickness from 90 nm to 110 nm, preferably from 95 nm to 105 nm, - a low refractive layer (32.2) based on silicon dioxide with a thickness from 80 nm to 100 nm, preferably from 85 nm to 95 nm.

15. Use of a composite pane according to one of claims 1 through 4 in a motor vehicle, preferably a passenger car, as a windshield that serves as a projection surface of a head-up display.