Windscreen with reflective coating and display system for a vehicle

Abstract

The present invention relates to a windscreen (10), comprising an outer pane (1) with an outer surface (I) and a surface (II) towards the interior and an inner pane (2) with an outer surface (III) and a surface (IV) towards the interior. The surface (II) towards the interior of the outer pane (1) and the outer surface (III) of the inner pane (2) are connected together by a thermoplastic intermediate layer (3), which has a transparent see-through region (D) and an opaque masking region (M) and which has a display region (A) arranged in the masking region (M), and which is provided at least in the display region (A) with a reflective coating (20) arranged on the outer surface (III) or the surface (IV) towards the interior of the inner pane (2). The reflective coating (20) comprises, starting from the inner pane (2) in the order indicated: • a dielectric lower blocker layer (21) having a refractive index of greater than or equal to 1.9, • at least one functional layer (22) based on at least one metal selected from the group consisting of nickel, chromium, niobium, tantalum, titanium, zirconium, hafnium, vanadium, molybdenum, tungsten, palladium, platinum, indium and tin, • a dielectric upper blocker layer (23) having a refractive index of greater than or equal to 1.9, • an optically low refractive layer (24.1) having a refractive index of less than or equal to 1.6, and • an optically high refractive layer (24.2) having a refractive index of greater than or equal to 1.9.

Description

[0001] Windscreen with reflective coating and display system for a vehicle

[0002] The invention relates to a windshield and a display system for a vehicle, comprising the windshield.

[0003] Windshields for vehicles, especially motor vehicles such as passenger cars, are designed as laminated glass (laminated safety glass), consisting of an outer pane and an inner pane laminated together with a thermoplastic interlayer. They typically feature an opaque masking area, which forms a circumferential border and surrounds a central viewing area. The primary purpose of this opaque masking area is to protect the adhesive used to bond the windshield to the vehicle body from UV radiation. This masking area is typically created by a black printed masking layer on the surface of the outer pane facing the interlayer.

[0004] Modern vehicles are increasingly equipped with display systems that project graphic representations directly onto the windshield. A well-known example of this is the so-called head-up display (HUD). With an imaging unit (especially a projector) located in the dashboard area, images are projected onto the visible area of ​​the windshield, reflected there, and perceived by the driver as a virtual image (from their perspective) behind the windshield.

[0005] It has proven advantageous to operate such display systems with p-polarized radiation. Firstly, the displayed images are then easily perceptible even to people wearing polarization-selective sunglasses. Secondly, distracting ghost images can be avoided. Examples include DE102014220189A1, EP3187917B1, and W02021104800A1. The imaging units typically illuminate the windshield with an angle of incidence of approximately 65%, which is close to the Brewster angle for an air-glass interface (57.2° for soda-lime glass). When the HUD projector is operated with p-polarized radiation, the radiation is hardly reflected by the external glass surfaces of the windshield. Instead, the windshield is equipped with a reflective coating suitable for reflecting the p-polarized radiation to generate the displayed image.Since there is only one significant reflection plane, namely the reflective coating, a clear display image is produced without ghosting (or with only faint ghosting, which is due to residual reflection at the external glass surfaces when the angle of incidence deviates slightly from Brewster's angle). W02021004685A1 discloses another HUD display system that operates with p-polarized radiation, with a reflective coating comprising a single metallic reflective layer, preferably based on silver, or alternatively on gold, copper, or aluminum.

[0006] It has also been proposed to use the opaque masking area as a display surface for such a display system. For this purpose, a display area within the masking area is illuminated by an imaging unit (in particular, a screen). Examples include DE102009020824A1, WO2022073894A1, and WG2022073860A1. In this way, displays for the driver, which were previously located on the dashboard, can be projected directly onto the windshield. Examples of such displays include vehicle speed, time, engine speed, navigation system information, speed limit information (traffic sign recognition), a rear-view camera image, and various status indicators for the vehicle's condition. These display systems within the masking area are also preferably operated using p-polarized radiation to achieve a clear and easily readable display.WO2022073894A1 discloses such a display system with a printed reflective layer in the display area.

[0007] Such reflective coatings often contain a reflective functional layer based on a metal. The reflective coating is typically applied to the initially flat inner disc, which is then bent spherically. The problem here is that many reflective coatings, especially the metallic functional layers, are not corrosion-resistant at the elevated temperatures during the bending process and are therefore not bendable. Corrosion impairs the optical properties, particularly the reflective properties of the coating, and can manifest as discoloration or even localized flaking of the coating. Insufficient bendability is primarily manifested by the formation of cracks in the coating.

[0008] The present invention is based on the objective of providing a windshield with a reflective coating that is corrosion-resistant and flexible. The reflective coating should also exhibit good optical properties, in particular a low overall reflectance combined with comparatively high reflectivity towards p-polarized radiation and a pleasing reflection color, as well as allowing for flexible adjustment of these properties, whereby the ratio of the reflectivities towards s-polarized and p-polarized radiation should also be adjustable.

[0009] The object of the present invention is achieved according to the invention by a windshield according to claim 1. Preferred embodiments are described in the dependent claims.

[0010] The core of the invention is an improved reflective coating. In the reflective coating according to the invention, a reflective, metallic functional layer is arranged between two blocker layers. The blocker layers protect the functional layer from oxidation, particularly during heat treatment in the windshield manufacturing process (for example, when bending the coated glass). Above the functional layer with the blocker layers, an anti-reflective module is arranged, which comprises at least one optically low-refractive-index and one optically high-refractive-index layer. The anti-reflective module allows the optical properties of the reflective coating to be adjusted, in particular the reflectance and the reflection color. It has been shown that the optical properties can be adjusted very flexibly.This applies not only to the overall reflectivity but also to the ratio of reflectivities towards s-polarized and p-polarized radiation. The optical properties can therefore be precisely tailored to meet specific requirements in each individual case. Furthermore, it has been surprisingly found that the anti-reflective module improves the flexibility of the reflective coating. It can be applied to a flat disk and then bent along with the disk without critical cracking occurring in the coating. These are significant advantages of the present invention.

[0011] The windshield according to the invention is designed as a laminated glass and comprises an outer pane and an inner pane, which are bonded together via a thermoplastic intermediate layer. The windshield is intended to separate the interior (vehicle interior) from the external environment in the forward-facing window opening of a vehicle. For the purposes of the invention, the inner pane refers to the pane of the windshield facing the interior. The outer pane refers to the pane facing the external environment.

[0012] 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 to each other via the thermoplastic intermediate layer.

[0013] The windshield has a transparent viewing area and an opaque masking area. The viewing area is intended for seeing through. The viewing area preferably has a light transmission of at least 70%. Light transmission here refers to the total transmission, determined by the method for testing the light transmittance of motor vehicle windows specified in ECE-R 43, Annex 3, Section 9.1. For the purposes of the invention, the masking area is defined as an area of ​​the windshield through which seeing through is not possible. The light transmission of the masking area is less than 5%, preferably less than 2%, particularly preferably less than 0.5%, and most preferably less than 0.1% (especially essentially 0%). The masking area is formed by an opaque element, for example, an opaque print or an opaque film.The opaque element is positioned behind the reflective coating in the direction of view from the vehicle interior to the outside environment, so that the latter can be illuminated by an imaging unit in the vehicle interior when the windshield is used as a projection surface for a display system. Therefore, in its installed position, the reflective coating is closer to the vehicle interior (and any imaging unit) than the opaque element and further away from the outside environment.

[0014] The masking area is typically formed by an opaque covering print on a surface of the outer or inner pane, for example.

[0015] - on the outer surface of the outer pane,

[0016] - on the inner surface of the outer pane, - on the outer surface of the inner pane (the reflective coating can then be arranged on the inner surface of the inner pane or also on the outer surface, below the cover print) or

[0017] - on the interior surface of the inner pane (the reflective coating can also be applied to the interior surface of the inner pane, above the cover print)

[0018] Preferably, the cover print is arranged on the interior surface of the outer pane.

[0019] The cover print is formed in particular from an enamel containing glass frits and a pigment, which is screen-printed and then fired into the disc surface. The pigment is typically a black pigment, for example carbon black, aniline black, bone black, iron oxide black, spinel black, and / or graphite. The cover print preferably has a thickness of 5 pm to 50 pm, particularly preferably 8 pm to 25 pm.

[0020] Alternatively, the masking area can also be formed by an opaque film in the intermediate layer, for example an opaque bonding film which creates the adhesive bond between the outer and inner panes, or a specially designed opaque masking film, for example based on PET, which is inserted between two bonding films.

[0021] In a typical embodiment, the masking area surrounds the viewing area like a frame. The masking area is thus arranged all the way around the viewing area. Typically, the masking area forms the perimeter of the windshield and borders the side edge of the windshield. Therefore, in a preferred embodiment, the masking area is arranged in a perimeter of the windshield and surrounds the central viewing area.

[0022] The windshield has a display area located within the masking area. This display area is designed to be illuminated by an imaging unit to create a display image perceptible to the vehicle occupants, particularly the driver. The imaging unit illuminates the display area of ​​the windshield, where the radiation is reflected towards the viewer (driver), thus creating a virtual image. The windshield 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 engine edge.If the masking area is located in a circumferential border region of the windshield, a section of the masking area is assigned to each of the upper, lower, and both side edges, extending along and preferably adjacent to the respective edge. The display area is preferably located in the section of the masking area corresponding to the lower edge. In other words, the display area is preferably located between the viewing area and the lower edge. Displays can be shown there that are conventionally shown in the dashboard area. This is aesthetically pleasing, and the driver does not have to take their eyes off the road as much, which can be advantageous for driving safety. Such display systems can also be referred to as black-print displays.

[0023] The windshield is provided with a reflective coating, at least in the display area. This reflective coating is specifically designed and intended to reflect the radiation from the imaging unit used to generate the displayed image.

[0024] The reflective coating is applied to the outer or inner surface of the inner pane. The reflective coating covers the entire display area. It can optionally extend beyond the display area. Preferably, however, it is arranged exclusively within the masking area and does not extend into the viewing area. The viewing area preferably does not have the reflective coating.

[0025] In a particularly advantageous embodiment, the reflective coating is arranged on the inner surface of the inner pane. This is especially advantageous with regard to a clear display image. A reflective coating on the outer surface of the inner pane, on the other hand, carries the risk of a ghost image, which results from some reflection of the radiation at the inner surface of the inner pane, which the radiation must first pass through to reach the reflective coating. The reflective coating according to the invention comprises, in the specified order starting from the inner pane (more precisely, starting from that surface of the inner pane on which it is applied):

[0026] - a dielectric lower blocker layer with a refractive index greater than or equal to 1.9,

[0027] - at least one functional layer based on at least one metal,

[0028] - a dielectric upper blocker layer with a refractive index greater than or equal to 1.9,

[0029] - an optically low refractive index layer with a refractive index of less than or equal to 1.6,

[0030] - an optically high-refractive-index layer with a refractive index greater than or equal to 1.9.

[0031] The reflective coating is specifically a coating made of thin films (thin-film stack, thin-film sequence). All layers of the reflective coating are thin films.

[0032] The functional layer is an electrically conductive layer based on at least one metal. Specifically, this means that the functional layer is based on a metal or a metal alloy. The functional layer provides the reflective properties of the reflective coating.

[0033] The functional layer is preferably based on at least one metal selected from the group consisting of nickel, chromium, niobium, tantalum, titanium, zirconium, hafnium, vanadium, molybdenum, tungsten, palladium, platinum, indium and tin.

[0034] In an advantageous embodiment, the functional layer is based on at least one metal selected from the group consisting of nickel, chromium, niobium, tantalum, titanium, zirconium, hafnium, vanadium, molybdenum, and tungsten. These materials have proven to be sufficiently hard and scratch-resistant, so that, for example, there is no risk of damage from scratches when wiping or other mechanical contact. Such wiping can, for example, be carried out as a cleaning step during the windshield manufacturing process. Scratch resistance is particularly important when the reflective coating is applied to the exposed, interior surface of the inner pane, which is regularly cleaned or otherwise touched even when installed. Functional layers based on nickel, chromium, a nickel-chromium alloy, or niobium have proven to be particularly suitable in this regard.A nickel-chromium alloy has the advantage over pure nickel or chromium that it can be easily deposited, especially sputtered.

[0035] In an alternative design, the functional layer is based on at least one metal selected from the group consisting of palladium, platinum, indium, and tin. These metals are inherently softer and sometimes susceptible to scratching. In this case, it can be particularly advisable to provide the reflective coating with a scratch-resistant topcoat to protect the vulnerable functional layer from damage.

[0036] According to the invention, the reflective coating comprises at least one functional layer. It can have exactly one functional layer, which is preferred with regard to a simple coating structure. However, it can also have several functional layers, wherein adjacent functional layers are separated from each other by dielectric layers.

[0037] In an advantageous embodiment, the at least one functional layer has a total thickness of 10 nm to 150 nm. Good results are achieved in this range with regard to reflection and other optical properties. In the case of multiple functional layers, the aforementioned total thickness is the sum of the thicknesses of the individual functional layers. In the case of a single functional layer, the aforementioned total thickness corresponds to the thickness of that single functional layer.

[0038] In a particularly preferred embodiment, the functional layer is based on at least one metal selected from the group consisting of nickel, chromium, and niobium. This achieves particularly good results.

[0039] In a first, particularly preferred embodiment, the functional layer is based on nickel and / or chromium, in particular on a nickel-chromium alloy. The at least one functional layer has a total thickness of preferably at least 40 nm to ensure good reflective properties, and particularly preferably at least 75 nm to prevent light transmission, which is advantageous for aesthetic reasons. The total thickness of the at least one functional layer is preferably from 40 nm to 130 nm, particularly preferably from 75 nm to 125 nm, and most preferably from 90 nm to 110 nm, particularly from 95 nm to 105 nm, for example, about 100 nm. This yields particularly good results. If a nickel-chromium alloy is used, the nickel content is preferably from 70 wt.% to 90 wt.%, particularly preferably from 75 wt.% to 85 wt.%, for example, 80 wt.%.-%, and the proportion of chromium preferably from 10 wt.% to 30 wt.%, particularly preferably from 15 wt.% to 25 wt.%, for example 20 wt.%, wherein they add the proportions of nickel and chromium, apart from any impurities, to 100 wt.%.

[0040] In a second, particularly preferred embodiment, the functional layer is based on niobium. The total thickness of the at least one functional layer is preferably from 10 nm to 50 nm, particularly preferably from 20 nm to 40 nm, and most preferably from 25 nm to 35 nm, for example, about 30 nm. This yields particularly good results, especially good reflective properties and a significant reduction in light transmission. Niobium-based functional layers have proven to be even more flexible than those based on a nickel-chromium alloy and allow for improved polarization-selective reflection behavior with simultaneously lower overall reflection (high reflection towards p-polarized radiation and low reflection towards s-polarized radiation).

[0041] The functional layer can (in all configurations) optionally contain doping, for example silicon, preferably with a proportion of no more than 1 wt.%.

[0042] Unless otherwise specified, the stated layer thicknesses or thicknesses refer to the geometric thickness of a layer. If the optical thickness is meant instead, this will be explicitly stated. The optical thickness within the meaning of the invention is the product of the geometric thickness and the refractive index at 550 nm.

[0043] The refractive index is specified within the scope of the present invention with reference to a wavelength of 550 nm, unless explicitly stated otherwise. The refractive index is fundamentally independent of the measurement method. It can be determined, for example, by ellipsometry. Ellipsometers are commercially available, for example from Sentech.

[0044] If a first layer is arranged above a second layer, this means, according to the invention, that the first layer is arranged further away from the surface of the inner disk than the second layer. If a first layer is arranged below a second layer, this means, according to the invention, that the second layer is arranged further away from the surface of the inner disk than the first layer. The at least one functional layer is electrically conductive. The remaining layers of the reflective coating are dielectric layers. By adding metallic dopants (for example, aluminum, boron, antimony, zirconium, or titanium), inherently dielectric materials can be provided with a certain degree of electrical conductivity. However, those skilled in the art will still identify them as dielectric layers with regard to their function, as is customary in the field of thin films.The material of the dielectric layers preferably has an electrical conductivity (inverse of the resistivity) of less than 10⁻¹⁰. 8 S / m. The material of metallic layers (electrically conductive layers) preferably has an electrical conductivity greater than 10 4 S / m on.

[0045] If a layer of the reflective coating is formed on the basis of a material, the layer consists predominantly of this material in addition to any impurities or dopants (preferably with a proportion of less than 10 wt.%, particularly preferably less than 5 wt.%).

[0046] The lower and upper blocker layers surround the at least one functional layer and protect it from corrosion, particularly during heat treatment, such as that which can occur during the manufacturing process, for example, during tempering or bending of the coated inner disc. According to the invention, the refractive index of the blocker layers is greater than or equal to 1.9, preferably from 1.9 to 2.5, and particularly from 1.9 to 2.3.

[0047] In an advantageous embodiment, the lower and upper blocker layers are based on a nitride. Oxides are less suitable because they can lead to oxidation of the metallic functional layer during the deposition process. The blocker layers are preferably oxide-free.

[0048] The lower and upper blocker layers are preferably based on silicon nitride, a silicon-metal mixed nitride (preferably silicon zirconium nitride, silicon titanium nitride, or silicon hafnium nitride), or aluminum nitride. Besides a suitable refractive index, these materials offer the advantage of good bendability. Silicon nitride is particularly preferred.

[0049] In an advantageous embodiment, the lower and upper blocker layers each have an optical thickness of 20 nm to 160 nm, preferably 30 nm to 120 nm. The lower blocker layer particularly preferably has an optical thickness of 30 nm to 100 nm, most preferably 30 nm to 70 nm, and more preferably 40 nm to 60 nm. The upper blocker layer particularly preferably has an optical thickness of 60 nm to 120 nm, most preferably 60 nm to 100 nm, and more preferably 70 nm to 100 nm or 70 nm to 90 nm. This results in good results with regard to the corrosion protection of the functional layer and the optical properties of the reflective coating.

[0050] Blocker layers with the aforementioned optical thicknesses can be realized, for example, by layers based on silicon nitride with a refractive index of 2.0 (or other materials with this refractive index) with a thickness of 10 nm to 80 nm, preferably from 15 nm to 60 nm, and particularly preferably for the lower blocker layer from 15 nm to 50 nm, most preferably from 15 nm to 35 nm, in particular from 20 nm to 30 nm, and for the upper blocker layer from 30 nm to 60 nm, most preferably from 30 nm to 50 nm, in particular from 35 nm to 50 nm or from 35 nm to 45 nm.

[0051] Above the upper blocker layer, at least the optically low-refractive-index layer with a refractive index of 1.6 or less, and above that, the optically high-refractive-index layer with a refractive index of 1.9 or greater, are arranged. The optically low-refractive-index and the optically high-refractive-index layers together act as an anti-reflective module. The following may optionally be present above the high-refractive-index layer in the order specified:

[0052] - another optically low refractive index layer with a refractive index < 1.6,

[0053] - one or more further layer sequences consisting of an optically low refractive index layer with a refractive index < 1.6 and an optically high refractive index layer with a refractive index > 1.9 or

[0054] - one or more further layer sequences consisting of an optically low refractive index layer with a refractive index < 1.6 and an optically high refractive index layer with a refractive index > 1.9 and above that another optically low refractive index layer with a refractive index < 1.6.

[0055] All alternating optically low-refractive and high-refractive layers work together as an anti-reflective module.

[0056] In other words, an anti-reflective module is arranged above the upper blocker layer, comprising at least one optically low-refractive-index layer and at least one optically high-refractive-index layer. The anti-reflective module comprises a layer sequence of the type "(low-refractive-high-refractive-index) x “ or of the type “(low refractive index - high refractive index) x - low refractive index” in the specified order starting from the upper anti-reflective layer, where x is an integer of at least (that is, greater than or equal to) 1.

[0057] The anti-reflective module, with its alternating arrangement of low-refractive-index and high-refractive-index layers, influences the optical properties of the reflective coating through optical interference effects, particularly the reflectance and reflection color. By appropriately selecting the materials and layer thicknesses, the optical properties can be tailored to the specific requirements of each application. Specifically, the anti-reflective module allows for adjustment of the reflectance to p-polarized and s-polarized radiation, the overall reflectance, and the ratio of reflectance to p-polarized radiation to reflectance to s-polarized radiation. This high degree of flexibility in terms of optical properties enables the glass manufacturer to respond very specifically to customer requirements.

[0058] It has also been shown that the anti-reflective module improves the flexibility of the reflective coating. It allows the inner pane with the applied reflective coating to be bent without cracks forming in the coating.

[0059] The refractive index of the at least one optically low-refractive-index layer is preferably from 1.3 to 1.6, and particularly from 1.4 to 1.6. The at least one optically low-refractive-index layer is preferably based on silicon oxide, magnesium fluoride, or calcium fluoride. Silicon oxide is particularly preferred.

[0060] The refractive index of the at least one optically high-refractive-index layer is preferably from 1.9 to 2.5, and particularly from 1.9 to 2.3. The at least one optically high-refractive-index layer is preferably based on silicon nitride, silicon oxynitride, a silicon-metal mixed nitride (preferably silicon zirconium nitride, silicon titanium nitride, or silicon hafnium nitride), or aluminum nitride. Besides a suitable refractive index, these materials have the advantage of good bendability. Silicon nitride is particularly preferred. In the simplest case, which may be preferred for manufacturing reasons, the antireflection modulus is a layer sequence of the type "(low-refractive-high-refractive-index)". x“with x=1. The antireflection module thus comprises exactly one optically low-refractive-index layer and exactly one optically high-refractive-index layer, in that order starting from the upper blocker layer. In an advantageous embodiment, the optically low-refractive-index layer has an optical thickness of 5 nm to 75 nm, preferably from 15 nm to 45 nm, particularly preferably from 17 nm to 32 nm, for example from 18 nm to 29 nm. In an advantageous embodiment, the optically high-refractive-index layer has an optical thickness of 10 nm to 160 nm, preferably from 20 nm to 100 nm, particularly preferably from 20 nm to 60 nm, and especially from 30 nm to 50 nm. This achieves good results with regard to the bendability and the optical properties of the reflective coating.”

[0061] Optically low refractive index layers with the aforementioned optical thicknesses can be realized, for example, by layers based on silicon dioxide (SiÜ2) with a refractive index of 1.45 with a thickness of 5 nm to 50 nm, preferably from 10 nm to 30 nm, particularly preferably from 12 nm to 22 nm, for example from 13 nm to 20 nm.

[0062] Optically high-refractive-index layers with the aforementioned optical thicknesses can be realized, for example, by layers based on silicon nitride with a refractive index of 2.0 (or other materials with this refractive index) with a thickness of 5 nm to 80 nm, preferably from 10 nm to 50 nm, particularly preferably from 10 nm to 30 nm, especially from 15 nm to 25 nm.

[0063] The reflective coating can, in principle, also comprise further layers. However, in preferred embodiments, the reflective coating consists only of the layers explicitly listed here.

[0064] The nitrides (silicon nitride, silicon-metal mixed nitride, aluminum nitride), oxides (silicon oxide), and fluorides (magnesium fluoride, calcium fluoride) listed as preferred dielectric materials can be deposited stoichiometrically, substoichiometrically, or superstoichiometrically with respect to nitrogen, oxygen, or fluorine content, respectively. The stoichiometry generally influences the refractive index of the layer, as do any doping. The reflective coating layers may contain dopants, such as aluminum, zirconium, titanium, boron, antimony, or hafnium in the dielectric layers, or silicon in the functional layer.

[0065] In an advantageous embodiment, an additional top layer is arranged above the optically high-refractive-index layer (or above the anti-reflective modulus). This top layer improves both scratch and abrasion resistance. The improvement in scratch resistance is particularly relevant when the functional layer is based on a relatively soft metal that is susceptible to scratching (especially palladium, platinum, indium, or tin). The improvement in abrasion resistance is always advantageous, regardless of the metal of the functional layer. The top layer is preferably the uppermost layer of the reflective coating. The top layer is preferably based on titanium oxide, titanium-zirconium oxide, or silicon-zirconium oxide. The top layer preferably has a thickness of 1 nm to 10 nm, and particularly preferably 2 nm to 5 nm.Such a top layer is particularly advantageous when the functional layer is based on a comparatively soft metal.

[0066] The reflective coating then comprises, in the specified order starting from the inner disc (more precisely, starting from that surface of the inner disc on which it is applied):

[0067] - the dielectric lower blocker layer with a refractive index greater than or equal to 1.9,

[0068] - at least one functional layer based on at least one metal,

[0069] - the dielectric upper blocker layer with a refractive index greater than or equal to 1.9,

[0070] - the optically low refractive index layer with a refractive index of less than or equal to 1.6,

[0071] - the optically high-refractive-index layer with a refractive index greater than or equal to 1.9,

[0072] - optionally one or more further layer sequences consisting of an optically low refractive index layer with a refractive index < 1.6 and an optically high refractive index layer with a refractive index > 1.9,

[0073] - optionally, an additional optically low-refractive-index layer with a refractive index < 1.6,

[0074] - the top layer. In an advantageous embodiment, the windshield with the reflective coating has a total reflectance R ges at an angle of 8° and at an angle of 60° of at most 35% and a reflectance R p-poiCompared to p-polarized radiation at an angle of 60°, the reflectance is at least 35%, for example, 38% to 42%. This is advantageous for achieving a high-intensity display of an image by irradiation with a p-polarized imaging unit while simultaneously reducing interfering reflections. Here, the integrated reflectance in the spectral range from 380 nm to 780 nm is meant, measured at the aforementioned angle (to the surface normal; angle of incidence and viewing angle) using a standard D65 light source and a 10° detector, irradiating the interior surface of the windshield (interior reflectance). Purely p-polarized radiation is used to determine Rp-poi, and to determine R gesMixed-polarized radiation (50% s / 50% p). A particular advantage of the present invention is that the ratio of reflectivities towards s- and p-polarized radiation can be flexibly adjusted, in particular by the design of the anti-reflective module, and that thereby R ges and R p-poi They can be adjusted largely independently of each other. The reflectance R s-P The oi opposite s-polarized radiation at an angle of 60° is preferably less than 25%, preferably less than 15%, or even less than 10%. The reflectance R s-P The reflectance Rp-pol relative to s-polarized radiation is measured under the same conditions as the reflectance Rp-pol relative to p-polarized radiation, but using only s-polarized radiation.

[0075] The windshield with the reflective coating has an interior reflection color characterized in the Lab color space by an a* value and a b* value, each ranging from -10 to 10. This allows for a color-neutral display image. The reflection color is measured by illuminating the interior surface of the inner pane with a p-polarized standard light source D65 at an angle of 60° (to the surface normal; angle of incidence and viewing angle), using a 10° detector.

[0076] 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 mm to 3 mm, are used, for example, with the standard thicknesses of 1.6 mm or 2.1 mm.

[0077] The outer pane, the inner pane, and the thermoplastic interlayer can be clear and colorless, or tinted or colored. The outer pane and the inner panes can be independently unstressed, partially stressed, or stressed (thermally or chemically).

[0078] The windshield is preferably curved in one or more directions, as is common for motor vehicle windshields (especially those of passenger cars), with typical radii of curvature ranging from about 10 cm to about 40 m. Typically, the outer surface of the outer pane has a convex curve and the inner surface of the inner pane has a concave curve. However, the windshield can also be flat, for example, if it is intended as a windshield for buses, trains, or tractors.

[0079] The thermoplastic interlayer contains at least one thermoplastic polymer, preferably polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), or polyurethane (PU), or mixtures, copolymers, or derivatives thereof, particularly preferably PVB. The interlayer is typically formed from at least one thermoplastic film (bonding film), preferably based on one of the aforementioned polymers, especially PVB. In the context of the invention, this means that the film contains the aforementioned material predominantly (a proportion greater than 50% by weight) and may optionally contain other components, such as plasticizers, stabilizers, or UV or IR absorbers. The thickness of the interlayer is preferably from 0.2 mm to 2 mm, and particularly preferably from 0.5 mm to 1 mm.

[0080] The windshield 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. The reflective coating is preferably applied to the inner pane by physical vapor deposition (PVD), particularly preferably by sputtering, and most preferably by magnetron sputtering. However, the coating can also be applied, for example, by chemical vapor deposition (CVD), such as plasma-enhanced chemical vapor deposition (PECVD), by evaporation, or by atomic layer deposition (ALD).The coating is preferably deposited on the inner disc before lamination and before any bending process. A particular advantage of the reflective coating according to the invention is that it is corrosion-resistant and bendable and can therefore be deposited on the inner disc before bending.

[0081] If the windshield is to be curved, the outer and inner panes are preferably bent before lamination and preferably after the inner pane has been coated with the reflective coating. Preferably, the outer and inner panes are bent congruently together (i.e., while lying on top of each other, 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. All standard bending methods can be used, such as gravity bending, press bending, and / or suction bending.

[0082] The invention further comprises a display system for a vehicle. The display system comprises a windshield according to the invention and at least one imaging unit which is directed towards and illuminates the display area of ​​the windshield.

[0083] The at least one imaging unit is directed at one of the display areas of the windshield. It is located on the inner side of the windshield and illuminates the windshield via the inner surface of the inner pane. When the display system is operating, the radiation emitted by the imaging unit illuminates the display area to generate the projection or displayed image. The radiation from the imaging unit is (partially) reflected by the reflective coating towards the viewer, creating a virtual image that appears slightly behind the reflective surface (reflective coating).

[0084] The radiation of the imaging unit lies in the visible spectral range of the electromagnetic spectrum, especially in the spectral range of 450 nm to 650 nm - typical imaging units work with RGB colors (red, green, blue), for example with a wavelength of 450 to 475 nm (blue), a wavelength of 520 nm to 550 nm (green) and a wavelength of 620 to 650 nm (red).

[0085] The imaging unit is preferably a projector or a screen (“display,” electronic display). A screen is particularly preferred. In principle, any type of screen can be used for the display system according to the invention, for example, a field emission display (FED), a liquid crystal display (LCD), a thin-film transistor display (TFT-LCD), a cathode ray tube display (CRT), a plasma display, an organic light-emitting diode (OLED), a (true) LED display, or a surface conduction electron emitter display (SED). OLED and LCD screens are particularly common.

[0086] In projectors, the beam direction can typically be varied using mirrors, particularly vertically, to adjust the projection to the viewer's height. Screens can be mounted on a swivel, allowing the beam direction (especially vertically) to be varied to adjust the projection to the viewer's height. The area in which the viewer's eyes must be positioned for a given beam direction is called the eyebox. This eyebox can be shifted vertically by adjusting the projector's mirrors or by changing the orientation of the screen (if it is mounted on a swivel), with the entire accessible area (i.e., the superposition of all possible eyeboxes) 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 within the eyebox, not their entire body. The technical terms used here from the field of HUDs are generally familiar 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, Technical University of Munich (Munich: University Library of the Technical University of Munich, 2012), in particular to Chapter 2, "The Head-Up Display." It is possible to use multiple imaging units, with each unit illuminating only a portion of the display area. This can be particularly useful for very large display areas, for example, if the display area is intended to extend along the entire lower edge of the windshield.In this case, several adjacent imaging units (e.g., screens) can be used, with the entire display area being illuminated by all of them. The display area can then be conceptually divided into several sub-display areas, with each sub-display area being assigned to and illuminated by exactly one imaging unit.

[0087] In an advantageous embodiment, the display system is operated with p-polarized radiation. The imaging unit illuminates the display area with p-polarized radiation. This means that the radiation from the at least one imaging unit has a p-polarized component, preferably is predominantly p-polarized, i.e., has a p-polarized component of more than 50%, particularly preferably at least 80%, and most preferably at least 95%. The radiation is, in particular, essentially purely p-polarized—that is, the p-polarized component is 100% or deviates only insignificantly from this. The polarization direction is specified as the plane of incidence of the radiation on the windshield. 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 windshield at a point within the display area, preferably at the geometric center of the display area. If multiple imaging units are used, each illuminating a sub-area of ​​the display area (sub-display area), this applies to the sub-display area illuminated by each imaging unit, independently of the other imaging units. Due to the curvature of windshields, which is common in vehicles and affects the plane of incidence and thus the definition of polarization, the polarization components (especially the ratio of p-polarized to s-polarized radiation or vice versa) can differ from this reference point at other locations.To generate the desired polarized radiation, a polarization filter or a polarizing beam splitter can be placed in the beam path between the imaging unit and the windshield, for example, if the imaging unit does not already provide radiation of the desired polarization direction.

[0088] The angle of incidence of the radiation on the windshield is preferably between 45° and 70°, particularly preferably between 60° and 70°, for example, approximately 65°. These angles of incidence deviate only slightly from the Brewster angle. The Brewster angle for an air-glass interface in the case of soda-lime glass, which is commonly used for window panes, is 57.2° (with a refractive index of 1.55 for soda-lime glass at a wavelength of 550 nm). The angle of incidence can also be referred to as the angle of incidence. It is the angle between the incident vector of the radiation and the surface normal on the interior side (i.e., the surface normal to the interior surface of the inner pane) determined at a point in the display area, preferably at the geometric center of the display area.If multiple imaging units are used, each illuminating a sub-area of ​​the display (sub-display area), this applies to the sub-display area illuminated by each imaging unit, independently of the other imaging units. If the angle of incidence exactly matches the Brewster angle, only s-polarized radiation is reflected, not p-polarized radiation. In an advantageous embodiment, the angle of incidence deviates from the Brewster angle by a maximum of 10°.

[0089] The advantage of p-polarized radiation and the preferred angle of incidence lies, on the one hand, in the avoidance of disturbing ghost images. Such ghost images can occur when the radiation from the imaging unit is reflected multiple times at the windshield, for example, at the inner surface of the inner pane, the reflective coating, and the outer surface of the outer pane. Since the display area according to the invention is arranged in the opaque masking area, the radiation is blocked by the opaque element before it reaches the outer surface, where consequently no reflection can occur. The p-polarized radiation allows the reflective coating to be arranged on the outer surface of the inner pane without creating a ghost image due to additional reflection at the inner surface.Since the angle of incidence does not deviate significantly from Brewster's angle, p-polarized radiation is generally not reflected, or only to a very small extent, at the inner surface of the lens. The reflection of the radiation from the imaging unit is practically solely due to the reflective coating. On the other hand, the advantage of p-polarized radiation is that the displayed image is visible to wearers of polarization-selective sunglasses, which typically only allow p-polarized radiation to pass through and block s-polarized radiation.

[0090] The invention further comprises the use of a windshield according to the invention as a projection surface for a display system in a vehicle, wherein at least one imaging unit is directed onto one of the display areas. The preferred embodiments described above apply accordingly to the use.

[0091] The invention further comprises a vehicle equipped with the windshield or display system according to the invention. The vehicle can be a land, air, or water vehicle. Preferably, the vehicle is a motor vehicle, rail vehicle, aircraft, or ship, in particular a passenger car or truck.

[0092] The invention further comprises the use of a display system according to the invention in a vehicle on land, water or in the air, preferably a motor vehicle, rail vehicle, aircraft or ship, in particular a passenger car or truck.

[0093] 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.

[0094] They show:

[0095] Fig. 1 shows a top view of a windshield of the type,

[0096] Fig. 2 shows a cross-section of the windshield from Figure 1 in a generic display system,

[0097] Fig. 3 shows a cross-section through an embodiment of the windshield according to the invention,

[0098] Fig. 4 is an enlarged view of section Z from Figure 3.

[0099] Figure 1 shows a top view of a windshield 10 of the generic type. This is the windshield of a passenger car. Figure 2 shows a cross-section through the windshield 10 from Figure 1, which functions as a projection surface in a display system of the generic type.

[0100] The display system comprises the windshield 10 and an imaging unit 4, which is directed at a display area A of the windshield 10. Images can be generated in display area A by the imaging unit 4, which are perceived by a viewer 5 (vehicle driver) as virtual images on the side of the windshield 10 facing away from him, provided his eyes are within the so-called eyebox E.

[0101] The windshield 10 consists of an outer pane 1 and an inner pane 2, bonded together by a thermoplastic interlayer 3. Its lower edge U points downwards towards the engine of the passenger car, and its upper edge O points upwards towards the roof. 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 and the inner pane 2 are made of soda-lime glass with a thickness of 2.1 mm for the outer pane 1 and 1.6 mm for the inner pane 2. The interlayer 3 is made of a 0.76 mm thick PVB film. For simplicity, the windshield 10 is shown as planar, although real windshields typically have a spherical curvature. The outer pane 1 has an outer surface I facing the external environment and an inner surface II facing the vehicle interior.Likewise, the inner pane 2 has an outer surface III facing the external environment and an inner surface IV facing the vehicle interior.

[0102] The windshield 10 has an opaque masking area M, which is arranged in a circumferential edge region and surrounds a transparent viewing area D in a frame-like manner. Such masking areas M are common in vehicle windows – they primarily serve to protect the adhesive used to bond the windshield 10 to the vehicle body from UV radiation.

[0103] Display area A is located in the masking area M between the viewing area D and the lower edge U. Such a display system can also be referred to as a "black-print display." This display area A serves to show information for the vehicle occupants. This can include, in particular, vehicle status information (for example, the vehicle speed or a fuel gauge), navigation instructions (for example, speed limits or directions), or the image from a rear-facing camera. Entertainment content can also be displayed (for example, films, internet data, or computer games), especially on the passenger side.

[0104] The imaging unit 4 is, for example, an LCD screen. Since the display area A is relatively large and extends along most of the lower edge U, multiple such imaging units 4 are typically used, with each imaging unit 4 illuminating a portion of the display area A. The imaging unit 4 illuminates the display area A with an angle of incidence α, which is measured relative to the interior surface normal of the inner pane. The angle of incidence α is, for example, 65°, which is relatively close to Brewster's angle (approximately 57° for an air-soda-lime glass interface). The radiation from the imaging unit 4 is p-polarized—it is therefore hardly reflected by the glass surfaces.

[0105] To generate the display image, the windshield 10 in display area A is equipped with a reflective coating, which is not shown in the figure for the sake of simplicity. The reflective coating reflects the p-polarized radiation from the imaging unit 4 to generate the display image. Since it represents the only significant reflective interface, a clear display image is produced without (or with only very weak) ghost images.

[0106] Figures 3 and 4 each show a detail of a windshield 10 according to the invention, preferably used for a display system as shown in Figure 2. The windshield comprises an outer pane 1 (soda-lime glass, 2.1 mm) and an inner pane 2 (soda-lime glass, 1.6 mm), which are bonded together via a thermoplastic interlayer 3 (PVB, 0.76 mm). The masking area M is formed by a black masking print 6 on the inner surface II of the outer pane 1. The masking print 6 consists of an enamel with glass frits and a black pigment, which is applied by screen printing and subsequently fired into the pane surface. On the inner surface IV of the inner pane 2, the reflective coating 20 according to the invention is arranged in an area that contains the display area A.

[0107] The reflective coating 20 consists of

[0108] - a lower blocker layer 21 ,

[0109] - a functional layer 22,

[0110] - an upper blocker layer 23,

[0111] - an optically low refractive index layer 24.1 and

[0112] - an optically high refractive layer 24.2, which is deposited, in particular sputtered, in the specified sequence starting from the interior surface IV on the inner disk 2.

[0113] The functional layer 22 is, for example, based on a nickel-chromium alloy (NiCr) or on niobium (Nb). It is electrically conductive and exhibits reflective properties. The functional layer 22 imparts its reflectivity to the reflective coating 20.

[0114] The lower blocker layer 21 and the upper blocker layer 23 are dielectric layers based on silicon nitride (SisN). They have a refractive index of 2.0. The blocker layers 21 and 23 protect the functional layer 22 from corrosion during the manufacturing process.

[0115] The optically low-refractive-index layer 24.1 is a dielectric layer based on silicon dioxide (SiO2). It has a refractive index of 1.45. The optically high-refractive-index layer 24.2 is a dielectric layer based on silicon nitride (SiO2). It has a refractive index of 2.0. The optically low-refractive-index layer 24.1 and the optically high-refractive-index layer 24.2 form an antireflection module 24. The antireflection module 24 makes the reflective coating 20 flexible, allowing it to be applied to the flat inner disk 2 and then bent together with it. The antireflection module also allows the optical properties of the reflective coating 20 to be adjusted based on optical interference effects, in particular the reflectance towards s-polarized and p-polarized radiation, the total reflectance, and the reflection color.

[0116] The layer sequences can be seen schematically in the figure. The layer sequence of a windshield 10 with the reflective coating 20 on the interior surface IV of the inner pane 2, together with the materials and layer thicknesses of the individual layers, is shown in Tables 1 and 2 for five examples 1 to 5 according to the invention.

[0117] Table 1 Table 2

[0118] In contrast, Table 3 shows the layer sequences of two windscreens 10 with non-inventive reflective coatings 20 (comparative examples 1 and 2).

[0119] In comparative example 1, the reflective coating 20 consists only of a functional layer 22 and an optically low refractive index layer 24.1 above it. In comparative example 2, the reflective coating 20 consists of a lower blocker layer 21, a functional layer 22, and an upper blocker layer 23, without the optically low refractive index layer 24.1 and optically high refractive index layer 24.2 according to the invention.

[0120] Table 3 Table 4 lists some optical properties of the windshields 10. These are:

[0121] - R g es (8°): the integrated total reflectance against mixed-polarized radiation at an incident and observation angle of 8°, measured with the standard light source D65 and a 10° detector,

[0122] - Rges (60°): the integrated total reflectance against mixed-polarized radiation at an incident and observation angle of 60°, measured with the standard light source D65 and a 10° detector,

[0123] - Rp-poi.: the integrated reflectance to p-polarized radiation at an incident angle and observation angle of 60°, measured with the standard light source D65 and a 10° detector,

[0124] - Rs-poi.: the integrated reflectance against s-polarized radiation at an incident angle and observation angle of 60°, measured with the standard light source D65 and a 10° detector,

[0125] - a*: the color value a* in the Lab color space in a reflection measurement at an incident angle and observation angle of 60°, measured with p-polarized radiation from a standard light source D65 and a 10° detector,

[0126] - b*: the color value b* in the Lab color space in a reflection measurement at an angle of incidence and observation angle of 60°, measured with p-polarized radiation from a standard light source D65 and a 10° detector.

[0127] Table 4 Examples 1 to 5 demonstrate that the design of the anti-reflective module 24 allows for very flexible adjustment of the optical properties, particularly the reflection behavior. For instance, it is possible to set the reflectance towards p-polarized radiation relatively high and the reflectance towards s-polarized radiation relatively low, resulting in a comparatively low overall reflectance. This enables a high-intensity display while minimizing distracting reflections at the

[0128] The reflective coating 20 can be minimized. This is particularly noticeable in examples 2 and 5. However, other ratios of polarized reflectivities are also achievable. It allows for a very flexible response to the specific requirements of each application.

[0129] Furthermore, experiments were conducted in which the reflective coating 20 was applied to a flat inner pane 2, which was then spherically bent at elevated temperatures using a standard bending process, as is common with windshields. The observations are summarized qualitatively in Table 5.

[0130] Table 5

[0131] In comparative example 1, significant corrosion of the reflective coating 20 was observed. This was prevented by the blocking layers 21 and 23 in examples 1-5 and in comparative example 2. However, in comparative example 2, the reflective coating 20 was not flexible but developed distinct cracks. Similar behavior is observed when the functional layer is made of niobium instead of the nickel-chromium alloy. This was prevented by the antireflection modulus 24 in examples 1 to 5.

[0132] Reference symbol list:

[0133] (10) Windshield

[0134] (1) Outer pane

[0135] (2) Inner disc

[0136] (3) thermoplastic intermediate layer

[0137] (4) imaging unit

[0138] (5) Observer / Driver

[0139] (6) Cover printing

[0140] (20) Reflective coating

[0141] (21) lower blocker layer

[0142] (22) Functional layer

[0143] (23) upper blocker layer

[0144] (24) Anti-reflective module

[0145] (24.1) optically low refractive index layer of the antireflection module 24

[0146] (24.2) optically high refractive index layer of the anti-reflective module 24

[0147] (O) Top edge of the windscreen 10

[0148] (U) Lower edge of the windscreen 10

[0149] (D) Viewing area

[0150] (M) Masking area

[0151] (A) Windscreen display area 10

[0152] (E) Eyebox

[0153] (a) angle of incidence

[0154] (I) outer surface of the outer pane 1

[0155] (11) interior surface of the outer pane 1

[0156] (III) outer surface of the inner pane 2

[0157] (IV) interior surface of the inner pane 2

[0158] X - X' Intersection line

[0159] Z enlarged section

Claims

Patent claims 1. Windscreen (10) comprising an outer pane (1) with an outer surface (I) and an inner surface (II) and an inner pane (2) with an outer surface (III) and an inner surface (IV), wherein the inner surface (II) of the outer pane (1) and the outer surface (III) of the inner pane (2) are connected to each other via a thermoplastic intermediate layer (3) which has a transparent viewing area (D) and an opaque masking area (M) and which has a display area (A) arranged in the masking area (M), and which is provided at least in the display area (A) with a reflective coating (20) arranged on the outer surface (III) or the inner surface (IV) of the inner pane (2), wherein the reflective coating (20) comprises, in the specified order starting from the inner pane (2): - a dielectric lower blocker layer (21) with a refractive index greater than or equal to 1.9, - at least one functional layer (22) based on at least one metal selected from the group consisting of nickel, chromium, niobium, tantalum, titanium, zirconium, hafnium, vanadium, molybdenum, tungsten, palladium, platinum, indium and tin, - a dielectric upper blocker layer (23) with a refractive index greater than or equal to 1.9, - an optically low refractive index layer (24.1) with a refractive index of less than or equal to 1.6, - an optically high refractive index layer (24.2) with a refractive index greater than or equal to 1.

9.

2. Windscreen (10) according to claim 1, wherein the lower blocker layer (21) and the upper blocker layer (23) are formed on the basis of a nitride, preferably on the basis of silicon nitride, on the basis of a silicon-metal mixed nitride, preferably silicon-zirconium nitride, silicon-titanium nitride or silicon-hafnium nitride, or on the basis of aluminium nitride.

3. Windscreen (10) according to claim 1 or 2, wherein the lower blocker layer (21) and the upper blocker layer (23) each have an optical thickness of 20 nm to 160 nm, preferably of 30 nm to 120 nm, and wherein the lower blocker layer (21) particularly preferably has an optical thickness of 30 nm to 100 nm, in particular of 30 nm to 70 nm and the upper blocker layer (23) has an optical thickness of 60 nm to 120 nm, in particular of 70 nm to 100 nm.

4. Windscreen (10) according to one of claims 1 to 3, wherein the at least one functional layer (22) has a total thickness of 10 nm to 150 nm.

5. Windscreen (10) according to one of claims 1 to 4, wherein the at least one metal of the at least one functional layer (22) is selected from the group consisting of nickel, chromium and niobium.

6. Windscreen (10) according to claim 5, wherein the at least one functional layer (22) is based on nickel and / or chromium, preferably on a nickel-chromium alloy, and wherein the at least one functional layer (22) preferably has a total thickness of 40 nm to 130 nm, particularly preferably of 75 nm to 125 nm, most preferably of 90 nm to 110 nm.

7. Windscreen (10) according to claim 5, wherein the at least one functional layer (22) is based on niobium and wherein the at least one functional layer (22) preferably has a total thickness of 10 nm to 50 nm, particularly preferably of 20 nm to 40 nm.

8. Windscreen (10) according to one of claims 1 to 7, wherein the optically low refractive index layer (24.1) is based on silicon oxide.

9. Windscreen (10) according to any one of claims 1 to 8, wherein the optically low refractive index layer (24.1) has an optical thickness of 5 nm to 75 nm, preferably of 15 nm to 45 nm, particularly preferably of 17 nm to 32 nm.

10. Windscreen (10) according to one of claims 1 to 9, wherein the optically high refractive index layer (24.2) is based on silicon nitride, on silicon oxynitride, on a silicon-metal mixed nitride, preferably silicon- zirconium nitride, silicon titanium nitride or silicon hafnium nitride, or based on aluminium nitride, preferably based on silicon nitride.

11. Windscreen (10) according to any one of claims 1 to 10, wherein the optically high refractive index layer (24.2) has an optical thickness of 10 nm to 160 nm, preferably of 20 nm to 100 nm, particularly preferably of 20 nm to 60 nm.

12. Windscreen (10) according to one of claims 1 to 11, wherein the reflective coating (20) above the optically high refractive layer (24.2) has a top layer based on titanium oxide, titanium zirconium oxide or silicon zirconium oxide, which is preferably the top layer of the reflective coating (20).

13. Windscreen (10) according to one of claims 1 to 12, which has a total reflectance R gesreflectance against mixed-polarized radiation of at most 35%, measured at an angle of 8° and 60°, and a reflectance Rp-poi against p-polarized radiation of at least 35%, measured at an angle of 60°, each determined as an integrated reflectance in the spectral range from 380 nm to 780 nm, measured using a standard light source D65 and a 10° detector, when irradiating the interior surface (IV).

14. Display system for a vehicle, comprising - a windshield (10) according to one of claims 1 to 13 and - at least one imaging unit (4) which is directed towards and illuminates the display area (A).

15. Display system according to claim 14, wherein the imaging unit (4) irradiates the display area (A) with p-polarized radiation at an angle of incidence (a) of 60° to 70°.

Images