Windscreen and display system for a vehicle

Abstract

The present invention relates to a windscreen (10) comprising an outer pane (1) having an exterior surface (I) and an interior surface (II) and comprising an inner pane (2) with an exterior surface (III) and an interior surface (IV), wherein the interior surface (II) of the outer pane (1) and the exterior surface (III) of the inner pane (2) are connected to one another by means of a thermoplastic intermediate layer (3), wherein the windscreen (10) has a display region (B), wherein, at least in the display region (B), the interior surface (IV) of the inner pane (2) is provided with a reflection coating (20), which is suitable for reflecting radiation in the visible spectral range and which comprises the following, in the order specified, starting from the interior surface (IV) of the inner pane (2): - an optically highly refractive layer (21) or layer sequence (21f) having a refractive index greater than 1.9 - a reflection-increasing layer (22) based on a metal or semiconductor, which layer is optionally completely or partially oxidised, - an optically low-refractive layer (23) or layer sequence having a refractive index of less than 1.6, wherein the ratio of the optical thickness of the optically highly refractive layer (21) or layer sequence (21f) to the optical thickness of the optically low-refractive layer (23) or layer sequence is 1.8 to 2.3.

Description

[0001] SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0002] Windscreen and display system for a vehicle

[0003] The invention relates to a windshield, a method for its manufacture and a display system for a vehicle comprising the windshield.

[0004] Windshields for vehicles, especially motor vehicles such as passenger cars, are made of laminated glass (laminated safety glass), consisting of an outer and an inner pane bonded together with a thermoplastic interlayer. Modern vehicles are increasingly equipped with so-called head-up displays (HLIDs). A projector, typically located in the dashboard area, projects images onto the visible area of ​​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, such as current speed, navigation instructions, or warnings, to be projected into the driver's field of vision without taking their eyes off the road. Head-up displays can thus significantly contribute to improving road safety.

[0005] Such a HUD can be operated with s-polarized radiation. The projector radiation is then reflected off both external surfaces of the windshield. This results in a slightly offset secondary image, the so-called ghost image, appearing alongside the desired main image. This problem is usually mitigated by aligning the surfaces at an angle to each other, particularly by using a wedge-shaped interlayer for lamination of the windshield, which is designed as a composite glass, so that the main image and ghost image are superimposed. Laminated glass with wedge-shaped films for HUDs is known, for example, from W02009071135A1, EP1800855B1, or EP1880243A2.

[0006] HUD projectors typically illuminate the windshield at 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). This fact can be exploited for a clear HUD projection: if the HUD projector operates with p-polarized radiation, it hardly reflects the radiation at the external glass surfaces of the windshield. Instead, the windshield is coated 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 SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0007] With a reflective coating, a clear display image is produced without ghosting (or with only faint ghosting, which is due to residual reflection from the external glass surfaces when the angle of incidence deviates slightly from Brewster's angle). Examples include DE102014220189A1, EP3187917B1 and W02021104800A1.

[0008] The reflective coating can be arranged inside the laminated glass unit, for example on the inner surface of the outer pane or the outer surface of the inner pane. This is particularly advantageous if the reflective coating has corrosion-prone layers, such as silver layers.

[0009] Sometimes, however, it is not possible to use purely p-polarized radiation. Even if the projector radiation is purely p-polarized with respect to a point in the display area, the usual curvature of the lens, which affects the definition of the plane of incidence and thus the degree of polarization, can result in different polarization conditions at other points in the display area, leading to an s-polarized component. Often, the radiation itself is not purely p-polarized at a reference point, for example, due to projector limitations (such as power consumption or heat generation) or to increase the intensity of the displayed image. In practice, therefore, mixed polarization with s- and p-polarized radiation components is frequently used.

[0010] In this case, the arrangement of the reflective coating inside the laminated glass results in three reflection planes relative to the projector beam: the reflective coating itself, which typically reflects both polarization directions, and the two external surfaces of the windshield, which reflect s-polarized radiation (and also slightly reflect p-polarized radiation if the angle of incidence deviates from Brewster's angle). This results in ghosting, which is extremely distracting for the user and prevents a clear HUD display.

[0011] It is therefore advantageous to position the reflective coating on the interior surface of the inner pane. This way, two reflection planes coincide: the reflective coating and the interior exposed surface. A ghost image resulting from the reflection of s-polarized radiation, in particular, at the exterior exposed surface (the outer surface of the outer pane) can be prevented, if necessary, by a wedge-shaped intermediate layer. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0012] HllDs with a windshield featuring a reflective coating on the interior surface of the inner pane are known, for example, from WO2022253659A1.

[0013] CN113031276A discloses a display system wherein the interior surface of the inner disc is provided with a reflective coating comprising at least a sequence of a dielectric high refractive index (refractive index > 1.8) and a dielectric low refractive index (refractive index < 1.6).

[0014] WO2024165281 A1 discloses a windshield for a HUD, wherein a reflective coating is arranged on the interior surface of the inner pane. Starting from said surface, the reflective coating comprises an optically high refractive index layer or sequence of layers, a reflection-enhancing layer based on a metal or semiconductor, and an optically low refractive index layer.

[0015] US2025013050A1 discloses a windshield for a HUD, wherein a reflective coating is arranged on the interior surface of the inner pane. In Example 5, the reflective coating comprises, starting from said surface, a high-refractive-index layer sequence, an aluminum-based reflection-enhancing layer, and a low-refractive-index layer. The ratio of the optical thickness of the high-refractive-index layer sequence to the optical thickness of the low-refractive-index layer is approximately 2.6.

[0016] There is a constant need for windshields for HUD display systems that are equipped with a reflective coating and offer improved optical properties. This naturally concerns, on the one hand, the reflectance of the HUD projector's radiation and the color neutrality of the HUD display, but also parameters such as light transmission, transmission color, external reflection color, and internal reflectance of ambient light.

[0017] The invention is based on the objective of providing an improved windshield for a HUD display system. The windshield should have a reflective coating on its interior surface that exhibits a sufficient degree of reflectivity against the radiation from the HUD projector, particularly when using mixed-polarized radiation. The windshield should also have high light transmission and low interior reflection.

[0018] Reflectance to ambient light, a neutral exterior reflective color, and a neutral transmission color. Due to its application on the exposed interior surface of the inner pane, the reflective coating should be corrosion-resistant and exhibit high mechanical stability.

[0019] 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.

[0020] 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.

[0021] The outer pane and the inner pane each have an outer and an inner surface, and a circumferential side edge surface extending 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 via the thermoplastic intermediate layer.

[0022] The windshield is specifically designed as a projection surface for a display system (head-up display). The windshield has at least one display area, which can also be referred to as the HUD area. This display area is intended to be illuminated by an imaging unit to generate a display image (HUD projection) perceptible to the vehicle occupants, particularly the driver. During operation, the imaging unit illuminates the display area of ​​the windshield, where the radiation is reflected towards the viewer (driver), thereby creating a virtual image. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0023] According to the invention, a reflective coating is arranged on the interior surface of the inner screen, at least in the display area. The reflective coating is particularly suitable and designed to reflect the radiation from the imaging unit for generating the display image, which can be perceived by an observer located inside the vehicle, especially the driver. The reflective coating is suitable and designed to reflect radiation in the visible spectral range, in particular p-polarized radiation or radiation with a p-polarized component. The reflective coating covers the entire HUD area. It can optionally extend beyond the HUD area.

[0024] The reflective coating comprises, in the specified order starting from the interior surface of the inner pane:

[0025] - a (preferably dielectric) optically high-refractive-index layer or sequence of layers with a refractive index greater than 1.9,

[0026] - a reflection-enhancing layer based on a metal or semiconductor,

[0027] - a (preferably dielectric) optically low refractive index layer or sequence of layers with a refractive index of less than 1.6.

[0028] According to the invention, the optically high-refractive-index layer or layer sequence has a refractive index greater than 1.9, and the optically low-refractive-index layer or layer sequence has a refractive index of less than 1.6. In the case of a layer sequence, this means that each individual layer of the respective layer sequence has the aforementioned refractive index of greater than 1.9 or less than 1.6, respectively. The optically high-refractive-index layer or layer sequence is thus formed as a single optically high-refractive-index layer with a refractive index greater than 1.9 or as a layer sequence in which all layers of the layer sequence each have a refractive index greater than 1.9. Likewise, the optically low-refractive-index layer or layer sequence is formed as a single layer with a refractive index less than 1.6 or as a layer sequence in which all layers of the layer sequence each have a refractive index less than 1.6.

[0029] The reflection-enhancing layer, based on a metal or semiconductor, can optionally be fully or partially oxidized. The reflection-enhancing layer is generally designed as a pure or doped metal or semiconductor layer and is deposited accordingly. However, due to manufacturing processes, a certain degree of oxidation may occasionally occur. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0030] Oxidation can occur. Such oxidation is undesirable in itself, but can happen, especially when the coating is exposed to elevated temperatures. This can occur, for example, during the deposition of the layers themselves, but particularly during heat treatment of the coated inner disk, such as thermal prestressing or bending of the disk. As a result, the reflection-enhancing layer can be partially or completely oxidized, so that in the final product it exists partly (i.e., over a portion of its thickness) or completely (i.e., over its entire thickness) as a metal oxide layer or semiconductor oxide layer. Partial oxidation is particularly typical. In partial oxidation, the reflection-enhancing layer in the final product is therefore a combination of a layer based on a metal or semiconductor and a layer based on the oxide of said metal or semiconductor.

[0031] The optional, and in itself undesirable, oxidation of the reflection-enhancing layer is always a substoichiometric oxidation. The metal oxide or semiconductor oxide therefore exists as a substoichiometric metal oxide or semiconductor oxide, with a significantly lower oxygen content than the corresponding stoichiometric metal oxide or semiconductor oxide. In other words, the optional oxidation is complete or partial with respect to the thickness of the reflection-enhancing layer, but only partial or incomplete with respect to the stoichiometry or the oxygen content.

[0032] The optional oxidation occurs only to such an extent that the metallic or semiconducting properties of the reflection-enhancing layer are retained, which is why it still functions as intended in the oxidized state. The material of the reflection-enhancing layer does not transform into a dielectric metal oxide or semiconductor oxide. There are several ways to distinguish the (optionally oxidized) reflection-enhancing layer with its metallic or semiconducting properties from dielectric oxide layers:

[0033] - Regarding electrical conductivity: The material of a metallic layer exhibits an electrical conductivity (inverse of resistivity) greater than 10 4 S / m, even when oxidized to some extent. The material of a semiconductor layer exhibits an electrical conductivity of 10⁻⁵. 8 S / m up to 10 4S / m, even when oxidized to some extent. Dielectric layers, on the other hand, exhibit an electrical conductivity of less than 10⁻⁶. 8 S / m. The electrical conductivity can be determined by an eddy current test. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0034] Suitable measuring instruments are distributed, for example, by NAGY Messsysteme GmbH, in particular the SRM-14T instrument.

[0035] - Regarding the optical band gap (referenced to a temperature of 300 K): The material of a metallic layer has no band gap, the material of a semiconductor layer has a band gap of less than 3 eV, while dielectric layers have larger band gaps, generally more than 3 eV. In other words, the reflection-enhancing layer has a band gap of less than 3 eV (even if it is oxidized to some extent). The band gap can be determined using a so-called tau plot, which is known to those skilled in the art. The value (aE) is then calculated. 0 ' 5The graph plots the ordinate against the abscissa, where a denotes the absorption coefficient of the material and E the photon energy. A section with a linear dependence always appears, the extrapolation of which to the abscissa corresponds to the band gap. This linear section is fitted to the graph as a straight line by linear regression, which intersects the abscissa at a value corresponding to the band gap.

[0036] According to the invention, the ratio of the optical thickness of the optically high-refractive-index layer or layer sequence to the optical thickness of the optically low-refractive-index layer or layer sequence is from 1.8 to 2.3.

[0037] The arrangement of the reflective coating on the inner surface of the inner pane allows the windshield to be illuminated with s-polarized radiation components when a HUD is in operation. Since the inner surface of the inner pane is already reflective due to the reflective coating, this only results in further reflection from the outer surface of the outer pane, which could potentially create a ghost image. However, this is easily remedied by using a wedge angle. The reflective coating according to the invention results in a flat reflection spectrum, thus ensuring a color-neutral HUD projection. Furthermore, the reflectance is sufficiently high for a high-intensity HUD projection (especially greater than 10% compared to p-polarized radiation). The reflective coating according to the invention also achieves a neutral reflection color on the outer surface and a neutral transmission color, which is aesthetically pleasing.The reflective coating also results in a lower interior reflection rate compared to conventional reflective coatings, thus reducing glare for the driver. Light transmission is sufficiently high, so the SAINT-GOBAIN SEKURIT FRANCE 2025043- WO-PCT.

[0038] The windshield meets legal requirements for road traffic. These are major advantages of the present invention.

[0039] If a layer of the reflective coating is based on a material, the layer consists predominantly of this material (more than 50 atomic %) in addition to any impurities or dopants.

[0040] Metallic doping can impart a certain electrical conductivity to inherently dielectric materials. However, those skilled in the art will still identify them as dielectric layers, as is common practice in the field of thin films. The material of the dielectric layers preferably exhibits an electrical conductivity (inverse of the resistivity) of less than 10⁻⁶ Ω. 8 S / m. The material of metallic layers (electrically conductive layers) preferably has an electrical conductivity greater than 10 4 S / m. The material of a semiconductor layer preferably exhibits a conductivity between these values, i.e., of 10⁻⁶. 8 S / m up to 10 4S / m. Another characteristic that distinguishes semiconductors from metals is the negative temperature coefficient of their resistivity: the electrical conductivity of semiconductors increases with rising temperature, while that of metals decreases. This is due to their electronic band structure: semiconductors have a band gap between the valence and conduction bands, and to provide electrical conductivity, electrons as free charge carriers must be thermally excited from the valence band to the conduction band. In metals, there is no band gap; the valence and conduction bands overlap, so that free charge carriers are present regardless of temperature. An increase in temperature leads to the excitation of atomic core movements, which restricts the mobility of the electrons.

[0041] 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.

[0042] In the context of this application, the thickness of a layer always refers to the geometric layer thickness. If, instead, the optical thickness is meant, this is explicitly stated. The optical thickness of a layer is calculated as the product of the SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0043] geometric thickness and refractive index (at 550 nm). The optical thickness of a layer sequence is calculated as the sum of the optical thicknesses of the individual layers.

[0044] The reflective coating is, in particular, a transparent coating made of thin films (thin-film stack, thin-film sequence). A transparent coating is understood to be one that has an average transmission in the visible spectral range of at least 70%, meaning it does not significantly impair visibility through the pane. Generally, it is sufficient if the reflective coating is only present in the display area on the inner surface of the inner pane. However, for manufacturing reasons and to ensure a homogeneous appearance, preferably at least 80%, and particularly preferably at least 90%, of the inner surface of the inner pane is provided with the reflective coating.In particular, the reflective coating is applied across the entire interior surface of the inner pane, optionally with the exception of a circumferential edge area and / or local areas intended to ensure the transmission of electromagnetic radiation through the windshield as communication, sensor, or camera windows. The circumferential uncoated edge area, if present, has a width of up to 20 cm. It can, for example, be used for bonding the windshield to the vehicle body, allowing the adhesive and any sealing elements to be applied directly to the interior surface of the inner pane.

[0045] According to the invention, the ratio of the optical thickness of the optically high-refractive-index layer or layer sequence to the optical thickness of the optically low-refractive-index layer or layer sequence is from 1.8 to 2.3, preferably from 2.0 to 2.2. This results in particularly good results.

[0046] According to the invention, the optically high-refractive-index layer or layer sequence has a refractive index of more than 1.9. The refractive index is, for example, between 1.9 and 3.0, and preferably between 2.0 and 2.5.

[0047] The optically high-refractive-index layer or layer sequence preferably has an optical thickness of 150 nm to 300 nm, particularly preferably 200 nm to 270 nm, most preferably 200 nm to 250 nm, and especially 220 nm to 250 nm. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0048] The optically high-refractive-index layer or layer sequence preferably comprises at least one dielectric layer based on titanium oxide, silicon nitride, silicon-metal mixed nitride, tungsten oxide, niobium oxide, aluminum nitride, bismuth oxide, tantalum oxide, hafnium oxide, chromium oxide, tin oxide, zirconium oxide, titanium-zirconium oxide, silicon-zirconium oxide, hafnium oxide or tin-zinc oxide. Particularly preferred are titanium oxide, niobium oxide, silicon nitride (especially aluminum-doped silicon nitride), tin oxide, tin-zinc oxide and silicon-metal mixed nitride (especially silicon-aluminum nitride, silicon-zirconium nitride, silicon-hafnium nitride or silicon-titanium nitride) due to their suitable refractive index, good availability and good deposition rates, especially titanium oxide, silicon nitride (especially aluminum-doped silicon nitride) and silicon-metal mixed nitride (especially silicon-zirconium nitride, silicon-hafnium nitride or silicon-titanium nitride).In the case of a layer sequence, preferably at least one individual layer, and more preferably several individual layers, are formed based on one of the aforementioned materials. It is particularly advantageous if the optically high-refractive-index layer (if a single optically high-refractive-index layer is present) or each individual layer of the optically high-refractive-index layer sequence (if such a layer sequence is present) is formed based on one of the aforementioned materials.

[0049] The nitride materials can be partially oxidized during any heat treatment after the application of the reflective coating. For example, a layer deposited as silicon nitride will then contain silicon oxynitride (Si) after heat treatment. x N y O z ), where the oxygen content typically ranges from 0 atomic % to 35 atomic %.

[0050] In an advantageous embodiment, the optically high-refractive-index layer or layer sequence is formed as a sequence of multiple optically high-refractive-index layers of different materials. Each layer of the optically high-refractive-index layer sequence has a refractive index greater than 1.9, for example between 1.9 and 3.0, and preferably between 2.0 and 2.5. Preferably, the layer sequence comprises at least one layer with a refractive index greater than 2.1, for example between 2.1 and 3.0, in particular between 2.2 and 2.5. These particularly high-refractive-index layers are preferably based on titanium oxide or silicon-metal mixed nitride (in particular silicon zirconium nitride, silicon hafnium nitride, or silicon titanium nitride).

[0051] The layers of the layer sequence preferably each have a thickness of at most 80 nm, particularly preferably at most 70 nm, particularly preferably at most 60 nm, SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0052] The layer sequence can, for example, consist of two layers, each with a thickness of at most 80 nm, preferably at most 70 nm, and particularly preferably at most 60 nm. Alternatively, the layer sequence can, for example, consist of three layers, each with a thickness of at most 80 nm, preferably at most 60 nm, and particularly preferably at most 50 nm. By dividing the total thickness of the layer sequence into several, each thinner, individual layers, higher line speeds can be achieved with typical industrial coating systems, and the coating can consequently be deposited more quickly.In particular, the individual layers can be applied in successive chambers of a coating system, and by dividing the process into individual layers, each chamber is available for coating the next substrate sooner than if the entire layer module were deposited as a thicker single layer in a single chamber with a single target. Besides these economic advantages, such a layer sequence is also advantageous with regard to the flexibility of the coating. Directly successive layers of the layer sequence are preferably made of different materials. It can be particularly preferred that all layers of the layer sequence are made of different materials, i.e., that the layer sequence does not include any layers based on the same material.

[0053] According to the invention, the reflection-enhancing layer is based on a metal or a semiconductor. The reflection-enhancing layer can be completely or partially oxidized, which is particularly the case if the inner disk is subjected to heat treatment after the reflection-enhancing layer has been deposited. Therefore, instead of a purely metallic (metal-based) or semiconductor-based reflection-enhancing layer, a completely or partially oxidized reflection-enhancing layer can be present in the final product.

[0054] The reflection-enhancing layer is preferably a very thin layer with a thickness of 1 nm to 10 nm, particularly preferably from 1 nm to 8 nm, most preferably from 2 nm to 8 nm, and especially from 2 nm to 5 nm. These thicknesses are sufficient to significantly increase the reflectivity of the reflective coating and, on the other hand, do not reduce the light transmission of the windshield to a critical extent.

[0055] When selecting the metal, care should be taken to ensure that it is corrosion-resistant (as a thin film), because the reflective coating according to the invention is applied to the inner surface of the inner disc, which is typically SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0056] exposed to the atmosphere. Some metals commonly used for thin-film coatings on glass panes (for example, for IR-reflective solar control coatings) are therefore unsuitable for the reflection-enhancing layer, such as silver or copper. If the reflection-enhancing layer is metal-based, then that metal is preferred:

[0057] - a precious metal (in the chemical-technical sense as a metal with a more positive standard potential than hydrogen), in particular selected from the group consisting of platinum, ruthenium, rhodium, palladium, osmium and iridium;

[0058] - a (base) transition metal, in particular selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, nickel and chromium;

[0059] - Aluminum.

[0060] If the reflection-enhancing layer is based on a semiconductor, then the semiconductor is preferred:

[0061] - an elemental semiconductor or a semimetal, in particular selected from the group consisting of silicon, germanium and tin in the «-modification (a-tin); - an alloy or a mixture of one of the said semimetals with aluminium, in particular a silicon-aluminium alloy.

[0062] Alloys or mixtures of the aforementioned materials can also be used for the reflection-enhancing layer. The semiconductor material can be doped or mixed with a metal (e.g., aluminum), for example, up to 15 wt.%.

[0063] It can happen that the reflection-enhancing layer is based on a metal (for example, titanium) and a high-refractive-index layer is based on an oxide of the same metal (for example, titanium oxide). If the reflection-enhancing layer is then oxidized during a thermal transformation process, it will also be present in the final product as an oxide of the metal (for example, titanium oxide). The reflection-enhancing layer can typically still be distinguished from the high-refractive-index layer, primarily because it has a lower oxidation state, i.e., a lower oxygen content.

[0064] According to the invention, the optically low-refractive-index layer or layer sequence has a refractive index of less than 1.6. The refractive index is, for example, between 1.3 and 1.6, and preferably between 1.3 and 1.5. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0065] The optically low refractive index layer or layer sequence preferably has an optical thickness of 50 nm to 200 nm, particularly preferably of 100 nm to 200 nm, most preferably of 100 nm to 150 nm, and especially of 110 nm to 140 nm.

[0066] The optically low refractive index layer or layer sequence preferably comprises at least one dielectric layer based on silicon oxide, magnesium fluoride, or calcium fluoride. Particularly preferably, the optically low refractive index layer or layer sequence is formed as a single optically low refractive index layer based on silicon oxide.

[0067] The nitrides, oxides and fluorides listed as preferred dielectric materials can be deposited stoichiometrically, substoichiometrically or superstoichiometrically with respect to nitrogen, oxygen or fluorine content.

[0068] The dielectric layers of the optically high-refractive-index layer or layer sequence and the optically low-refractive-index layer or layer sequence may contain metallic dopants, for example, aluminum, boron, antimony, titanium, hafnium, or zirconium. The proportion of dopants is preferably less than 5 wt.%. If a dielectric layer contains metallic additives, these are referred to as doping within the meaning of the invention if their proportion is less than 5 wt.%. From a proportion of 5 wt.%, a layer is referred to as a mixture, for example, a silicon-metal mixed nitride.

[0069] 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 inner surface of the inner pane 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 inner surface of the inner pane than the first layer.

[0070] In principle, the reflective coating can contain further layers. However, preferably there is no optically low refractive index layer below the reflection-enhancing layer and no optically high refractive index layer above the reflection-enhancing layer. It is also conceivable that the reflective coating has further sequences of alternating optically high- and low-refractive index layers or layer sequences, with or without intervening reflection-enhancing layer(s). Preferably, the reflection-enhancing layer is combined with the optically high-refractive index layer or layer sequence and the optically low-refractive index layer or layer sequence. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0071] Each layer is in direct contact, so that no further layers are arranged between them. In particularly preferred embodiments, however, the reflective coating consists only of the optically high-refractive-index layer or layer sequence (in particular a layer sequence of preferably two or three layers), the reflection-enhancing layer, and the optically low-refractive-index layer or layer sequence (in particular a layer).

[0072] 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.

[0073] The windshield typically has a transparent viewing area and an opaque masking area. The viewing area is intended for seeing through. The light transmission of the windshield in the viewing area is preferably 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 this invention, the masking area is defined as an area of ​​the windshield through which visibility 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 typically formed by an opaque covering print on a surface of the outer and / or inner pane, preferably on the interior surface of the outer and / or inner pane. The covering print is particularly well-formed from an enamel containing glass frits and a pigment, which is screen-printed and then fired onto the pane 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 covering print preferably has a thickness of 5 pm to 50 pm, and more preferably 8 pm to 25 pm. Alternatively, an opaque film can also be used in the intermediate layer to form the masking area.

[0074] In a typical design, 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 surrounding border. SAINT-GOBAIN SEKURIT FRANCE 2025043- WO-PCT

[0075] the windshield and borders the side edge of the windshield. In a preferred embodiment, the masking area is therefore arranged in a circumferential edge region of the windshield and surrounds the central viewing area.

[0076] In a preferred embodiment of the invention, the display area is arranged within the field of view. This creates a display directly in the user's (especially the driver's) field of vision, which the user can see without having to take their eyes off the road. Such display systems are also known as head-up displays (HUDs). A particular advantage of the reflective coating according to the invention is its high light transmission, so that the transmission within the field of view is not reduced to a critical degree. The reflective coating preferably covers the entire field of view, thereby avoiding visible edges of the reflective coating.

[0077] However, it is also possible for the display area to be located within the masking area, particularly between the viewing area and the lower edge of the windshield. Displays that are conventionally shown on the dashboard can be shown there. This is aesthetically pleasing, and the driver doesn't have to take their eyes off the road as much, which can be advantageous for driving safety. Such display systems can also be called black-print displays. In this case, the opaque element that forms the masking area (especially the printed cover or the opaque polymer film) should be 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 the imaging unit.A combination of the aforementioned configurations is also conceivable, with one display area located in the transmission area and another display area in the masking area. Each display area is preferably illuminated by its own imaging unit.

[0078] The windshield coated with the reflective layer preferably has a reflectance of at least 10% towards p-polarized radiation, particularly preferably at least 11%, and most preferably at least 12%. This reflectance is measured with an angle of incidence of 65° and the standard light source A. The reflectance is determined as the integrated reflectance, where the viewing angle corresponds to the angle of incidence. SAINT-GOBAIN SEKURIT FRANCE 2025043- WO-PCT

[0079] 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 1.1 mm to 2.9 mm, are used, for example, with the standard thicknesses of 1.6 mm or 2.1 mm.

[0080] 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).

[0081] 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. During the bending process, the reflection-enhancing layer is typically oxidized. Therefore, in a curved windshield, the reflection-enhancing layer is typically completely or partially oxidized if the coating was applied before the bending process. However, the windshield can also be flat, for example, if it is intended for use as a windshield in buses, trains, or tractors.

[0082] 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, particularly preferably from 0.5 mm to 1 mm. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0083] In an advantageous embodiment, the external surfaces of the windshield (the outer surface of the outer pane and the inner surface of the inner pane) are arranged at an angle (wedge angle) to each other. This is particularly advantageous when the windshield serves as a projection surface for a display system, where the display area is illuminated by an imaging unit emitting s-polarized radiation. However, it can also be advantageous when using purely p-polarized radiation, which can be reflected from the aforementioned surfaces if the angle of incidence deviates from the Brewster angle. The wedge angle allows the reflections from the two surfaces to be superimposed, thus preventing ghosting. The distance between the surfaces increases from the lower edge towards the upper edge of the display area.The lower edge of the display area faces the lower edge of the windshield, and the upper edge of the display area faces the upper edge of the windshield. The wedge angle can be achieved by using a wedge-shaped film as an intermediate layer or as part of the intermediate layer, or alternatively by using a wedge-shaped outer and / or inner pane.

[0084] The windshield can be manufactured by applying the reflective coating to the inner pane (at least in the intended display area) and then bonding it to the outer pane via the intermediate layer.

[0085] The procedure comprises the following steps in the specified order: a) Providing the inner disc,

[0086] b) Applying a reflective coating to a surface of the inner disc, wherein b.1. the optically high refractive index layer or sequence of layers,

[0087] b.2. the reflection-enhancing layer,

[0088] b.3. the optically low refractive index layer or sequence of layers

[0089] to be separated in the specified order,

[0090] c) Bonding (laminating) the inner disc to the outer disc via the intermediate layer, whereby the surface of the inner disc with the reflective coating is turned away from the intermediate layer.

[0091] The reflective coating is preferably applied to the inner disk by physical vapor deposition (PVD), particularly preferably by cathode sputtering, and most preferably by magnetic field-assisted cathode sputtering (magnetron sputtering). In principle, however, the coating can also be applied, for example, by SAINT-GOBAIN SEKURIT FRANCE 2025043- WO-PCT

[0092] The coating can be applied by chemical vapor deposition (CVD), for example plasma-enhanced 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.

[0093] Optionally, a thermal transformation process, in particular a thermal tempering or bending process, is carried out after the application of the reflective coating and before lamination. In this process, the reflection-enhancing layer is typically partially or completely oxidized. The optional thermal transformation process involves heat treatment, typically at temperatures above 500 °C. Preferably, the outer and inner panes are bent congruently together (i.e., 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.If the process is carried out without such a transformation, the reflection-enhancing layer in the final product remains as a layer based on the metal or semiconductor, without oxidation. This occurs, for example, with a flat windshield or with a curved windshield where the coating was applied only after the bending process.

[0094] It is also possible that the inner disc first undergoes the transformation process, in particular being bent, and is then coated with the reflective layer. In this case as well, the reflection-enhancing layer in the final product remains a layer based on the metal or semiconductor, without oxidation.

[0095] Lamination can be carried out using known methods. 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. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0096] The invention also includes a display system for a vehicle. The display system can also be referred to as a projection arrangement. The display system comprises a windshield according to the invention and an imaging unit. The imaging unit is directed towards the display area of ​​the windshield and illuminates it with visible light to generate a display image.

[0097] As is typical for display systems of this type, the imaging unit illuminates an area of ​​the windshield where the radiation is reflected towards the viewer (driver), thereby creating a virtual image that the viewer perceives as if it were behind the windshield. The display area of ​​the windshield is therefore, in particular, the area that can be illuminated by, or is illuminated by, the imaging unit.

[0098] The imaging unit is preferably a projector or a screen (“display,” electronic display). A projector is preferred, especially when the display area is located within the viewing area of ​​the windshield (head-up display). Screens are particularly common and preferred when the display area is located within the masking area of ​​the windshield (black-print display). OLED and LCD screens are especially common.

[0099] In HUD projectors, the beam direction can typically be varied using mirrors, particularly vertically, to adjust the projection to the viewer's height. The area in which the viewer's eyes must be positioned for a given mirror position is called the eyebox window. This eyebox window can be shifted vertically by adjusting the mirrors, with the entire accessible area (i.e., the superposition of all possible eyebox windows) being referred to as 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 known to those skilled in the art.For a detailed description, please refer to the dissertation “Simulation-based measurement technology for testing head-up displays” by Alexander Neumann at the Institute of Computer Science of the Technical University of Munich (Munich: University Library of the TU Munich, 2012), in particular to Chapter 2 “The Head-Up Display”. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT.

[0100] The imaging unit is located on the inside 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 image. The radiation from the imaging unit lies in the visible spectral range of the electromagnetic spectrum, specifically in the range of 450 nm to 650 nm. Typical imaging units operate 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).

[0101] The radiation emitted by the imaging unit predominantly exhibits a p-polarized component. 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 windshield at a point within the display area, preferably at the geometric center of the display area. 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) may 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.

[0102] The proportion of p-polarized radiation in the imaging unit's output is preferably at least 50%. In a particularly advantageous embodiment, the imaging unit's output is mixed-polarized with a p-polarized to s-polarized radiation ratio of 80% / 20% to 50% / 50%. In other words, the p-polarized radiation component is 50% to 80% and the s-polarized radiation component is 20% to 50%, with the s-polarized and p-polarized radiation components adding up to 100%. This increases the intensity of the displayed image because the s-polarized radiation components are reflected by the disk surfaces, further contributing to the overall intensity of the displayed image. Furthermore, the use of SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0103] Imaging units with mixed polarization are often technically easier to implement compared to imaging units with purely p-polarized radiation.

[0104] 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 the angle of incidence corresponds exactly to 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°.

[0105] Since the angle of incidence typically does not deviate significantly from Brewster's angle, p-polarized radiation components are generally not reflected, or only to a very small extent, at the external surfaces of the windshield (outer surface of the outer pane and inner surface of the inner pane). The reflection of p-polarized radiation at the inner surface of the inner pane is practically solely due to the reflective coating. No further (significant) reflection of p-polarized radiation occurs at the outer surface of the outer pane. Therefore, there is only one significant reflection plane, namely the reflective coating on the inner surface of the inner pane, so the displayed image, which is based on p-polarized radiation, is shown clearly and without ghosting.It can nevertheless be advantageous to arrange the outer surface of the outer pane and the inner surface of the inner pane at an angle to each other, particularly by using a wedge-shaped intermediate layer. This allows a display image resulting from reflection at the outer surface of the outer pane to be aligned with the display image resulting from reflection at the inner surface of the inner pane, or at least reduces the distance between them. This avoids disturbing ghost images, which can be caused, for example, by s-polarized radiation components or by reflection.

[0106] of p-polarized radiation at the glass surfaces due to a deviation of the angle of incidence from the Brewster angle.

[0107] Besides avoiding ghost images, the use of (predominantly) p-polarized radiation also has the advantage that the displayed image is recognizable for wearers of polarization-selective sunglasses, which typically only allow p-polarized radiation to pass through and block s-polarized radiation.

[0108] The display system according to the invention can be manufactured by providing a windshield according to the invention, in particular by manufacturing it in the manner described above. The windshield and the imaging unit are then arranged in a defined spatial relationship to one another, such that the imaging unit is directed towards the display area of ​​the windshield and illuminates it during operation. The arrangement of the windshield and the imaging unit typically takes place during the manufacture of a vehicle, with the windshield and the imaging unit being installed at the designated locations.

[0109] 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.

[0110] The invention further comprises the use of a windshield designed according to the invention in a vehicle, for example a land, air or water vehicle, preferably a motor vehicle, rail vehicle, aircraft or ship, in particular a passenger car or truck. The windshield is preferably used as a projection surface for a display system, wherein an imaging unit is directed onto one display area.

[0111] 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. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0112] 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.

[0113] They show:

[0114] Fig. 1 shows a top view of a windshield of the type,

[0115] Fig. 2 shows a cross-section through a generic display system with the windshield from Figure 1,

[0116] Fig. 3 shows a cross-section through an embodiment of the windshield according to the invention,

[0117] Fig. 4 shows an enlarged view of section Z from Figure 3 in three embodiments according to the invention.

[0118] Fig. 5 Reflection spectra of windshields of examples 1 to 3 and of comparison examples 1 to 3.

[0119] Figure 1 shows a top view of an embodiment of a generic windshield 10. Figure 2 shows a cross-section through the windshield 10 as part of a generic display system.

[0120] The display system comprises the windshield 10, which is the front window of a passenger car. The display system also includes an imaging unit 4, which is directed at an area of ​​the windshield 10 referred to as display area B. Within display area B, the imaging unit 4 can generate images that are perceived by an observer 5 (the driver) as virtual images on the side of the windshield 10 facing away from them, provided their eyes are within the so-called eyebox E.

[0121] 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 the outer pane having a thickness of, for example, 2.1 mm and the inner pane a thickness of 1.6 mm. The interlayer 3 is made of a 0.76 mm thick PVB film (SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT).

[0122] trained. For the sake of simplicity, the windshield 10 is shown as flat, although real windshields typically have a spherical curvature.

[0123] The outer pane 1 has an outer surface I facing the external environment and an inner surface II facing the vehicle interior. Similarly, the inner pane 2 has an outer surface III facing the external environment and an inner surface IV facing the vehicle interior.

[0124] 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.

[0125] The display area B is located in the viewing area D of the windshield 10. The imaging unit 4 is a projector that operates with a p-polarized radiation component. The imaging unit 4 illuminates the display area B, thereby projecting a display image (HUD projection) directly into the field of vision of the viewer 5 (driver) – as a virtual image on the side of the windshield 10 facing away from them, when their eyes are within the eyebox E. Such a display system is also known as a "head-up display" (HUD). This allows the viewer 5 to be shown, in particular, status information (e.g., vehicle speed), navigation instructions (e.g., speed limits or directions), or warning symbols without having to take their eyes off the road.

[0126] The imaging unit 4 irradiates the display area B with an angle of incidence α, which is measured relative to the interior surface normal of the inner pane 2. 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 p-polarized radiation components of the imaging unit 4 are therefore hardly reflected by the glass surfaces.

[0127] The interior surface IV of the inner pane 2 is provided with a reflective coating, which is not shown in Figures 1 and 2. The reflective coating covers SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0128] The entire transmission area D is covered. The reflective coating reflects the radiation from the imaging unit 4 to generate the display image. For the p-polarized radiation components, it represents the only significant reflective interface, and a clear display image is produced without (or with only very weak) ghost images.

[0129] Figure 3 shows a cross-section through an embodiment of the windshield 10 according to the invention, which is particularly intended for a display system according to the invention. The windshield 10 again comprises the outer pane 1 (soda-lime glass, 2.1 mm), the inner pane 2 (soda-lime glass, 1.6 mm), and the thermoplastic intermediate layer 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. The reflective coating 20 according to the invention is arranged on the inner surface IV of the inner pane 2.

[0130] Figure 4 shows the section Z from Figure 3 in an enlarged view in three embodiments of the reflective coating 20 according to the invention.

[0131] Figure 4a shows a first embodiment of the reflective coating 20. The reflective coating 20 consists of

[0132] - an optically high-refractive-index layer 21 with a refractive index greater than 1.9,

[0133] - a reflection-enhancing layer 22 based on a metal or semiconductor and - an optically low-refractive-index layer 23 with a refractive index less than or equal to 1.6, which are deposited in the specified order starting from the interior surface IV on the inner disk 2, in particular by sputtering.

[0134] Figure 4b shows a second embodiment of the reflective coating 20. The reflective coating 20 consists of

[0135] - an optically high-refractive-index layer sequence 21f with a refractive index greater than 1.9, consisting of

[0136] o a first optically high-refractive layer 21.1,

[0137] o a second optically high refractive layer 21.2,

[0138] - a reflection-enhancing layer 22 based on a metal or semiconductor and - an optically low-refractive-index layer 23 with a refractive index less than or equal to 1, 6, SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0139] which are deposited in the specified order starting from the interior surface IV on the inner disk 2, in particular sputtered.

[0140] Figure 4c shows a third embodiment of the reflective coating 20. The reflective coating 20 consists of

[0141] - an optically high-refractive-index layer sequence 21f with a refractive index greater than 1.9, consisting of

[0142] o a first optically high-refractive layer 21.1,

[0143] o a second optically high refractive layer 21.2,

[0144] o a third optically high-refractive layer 21.3,

[0145] - a reflection-enhancing layer 22 based on a metal or semiconductor and - an optically low-refractive-index layer 23 with a refractive index less than or equal to 1.6, which are deposited in the specified order starting from the interior surface IV on the inner disk 2, in particular by sputtering.

[0146] The reflection-enhancing layer 22 can be completely or partially oxidized. This occurs particularly in curved windshields 10, with the oxidation taking place during the bending process of the inner pane 2.

[0147] Dividing the high-refractive-index layer sequence 21f into several individual layers 21.1, 21.2, 21.3 of different materials offers economic advantages with regard to the manufacturing process. Furthermore, the flexibility of the reflective coating 20 can be improved as a result.

[0148] The imaging unit can be operated with purely p-polarized radiation. Preferably, it is operated with mixed-polarized radiation, with an s-polarized component of 20% to 50%. Particularly in this case, it is advantageous to arrange the external surfaces of the windshield (outer surface I, inner surface IV) at a wedge angle to each other. S-polarized radiation is reflected at the inner surface IV with the reflective coating 20 and at the outer surface I. Due to the wedge-shaped arrangement, these reflections can be superimposed on each other, so that no ghost image occurs. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0149] Examples

[0150] In the following, three windshields 10 according to the invention (Examples 1 to 3) are compared with two windshields 10 not according to the invention (Comparative Examples 1 to 3). The reflective coating 20 in each case is composed of an optically high refractive index layer sequence 21f, a reflection-enhancing layer 22, and an optically low refractive index layer 23. The layer sequence of Example 1 and Comparative Examples 1 to 3, together with the materials and layer thicknesses of the individual layers, are shown in Table 1. The reflective coating 20 is configured according to Figure 4b (optically high refractive index layer sequence 21f consisting of two optically high refractive index layers). The layer sequence of Example 2 is shown in Table 2. The reflective coating 20 is configured according to Figure 4c (optically high refractive index layer sequence 21f consisting of three optically high refractive index layers).The reflection-enhancing layer 22 in Examples 1 and 2 and in Comparative Examples 1 to 3 is based on a metal, namely titanium (Ti). The layer sequence of Example 3 is shown in Table 3. The reflective coating 20 is configured according to Figure 4c (optically high-refractive-index layer sequence 21f consisting of three optically high-refractive-index layers), and the reflection-enhancing layer 22 is based on a semiconductor, namely silicon (Si). The silicon was doped with 10 wt% aluminum.

[0151] The optically high-refractive-index layer sequences 21 f each comprise a layer based on titanium oxide (TiO) and a layer based on silicon nitride (SiN). In Examples 2 and 3, a further optically high-refractive-index layer based on a silicon-zirconium mixed nitride (SiZrN) is present, which was deposited in a nitrogen atmosphere with added argon using a silicon-zirconium target with a zirconium content of 17 wt.%. The optically low-refractive-index layers 23 are each based on silicon oxide (SiO). SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0152] Table 1

[0153]

[0154] Table 2

[0155]

[0156] The oxides SiO₂ and TiO₂ and the nitrides SiN₂ and SiZrN₂ were deposited stoichiometrically with respect to their oxygen and nitrogen content, respectively. The layers may also contain dopants and impurities. The doping levels in layers based on the same material were identical in the examples and the comparison example. Thus, the layers based on SiO₂, SiN, and SiZrN were doped with aluminum. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0157] Table 3

[0158]

[0159] In examples 1 to 3 according to the invention, the ratio of the optical thickness of the optically high-refractive-index layer sequence 21f to the optical thickness of the optically low-refractive-index layer 23 is in the range of 1.8 to 2.3. Comparative example 1 is based on the technical teaching of WO2024165281A1 – the aforementioned ratio is significantly smaller (0.8). In comparative example 2, the aforementioned ratio is significantly larger (1.5), but smaller than the minimum value of 1.8 according to the invention. In comparative example 3, the aforementioned ratio (2.5) is larger than the values ​​of 1.8 to 2.3 according to the invention. The optical thicknesses of the optically high-refractive-index layer sequence 21f, the optical thicknesses of the optically low-refractive-index layer 23, and the resulting aforementioned ratio 4 ZU In summary: The optical thickness of the individual layers

[0160]

[0161] r

[0162] The optical thicknesses are calculated as the product of the geometric thickness and the refractive index at 550 nm. The optical thickness of layer sequence 21f is, in turn, the sum of the optical thicknesses of the high-refractive-index layers that comprise layer sequence 21f. The dielectric layers exhibit the following refractive indices at 550 nm: SiN (2.00), SiZrN (2.22), SiO (1.45), TiO (2.45). SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0163] Table 4

[0164]

[0165] Figure 5 shows the reflection spectra of the windshields 10 from Examples 1 to 3 and Comparative Examples 1 to 3, when the interior surface of the inner pane 2 is irradiated with fully p-polarized radiation at an angle of 67° to the surface normal (corresponding approximately to irradiation by a HUD projector). It can be seen that although the examples according to the invention have a somewhat lower reflectance than Comparative Examples 1 and 2, the reflection spectrum is significantly flatter. This allows the HUD display image to be rendered with significantly greater color neutrality, without undesirable color shifts caused by reflection. The flatter reflection spectrum is achieved by the higher ratio of the optical thickness of the optically high-refractive-index layer sequence 21f to the optical thickness of the optically low-refractive-index layer 23.At a ratio of 1.5 (Comparative Example 2), the spectrum is somewhat flatter, but still clearly uneven. In Examples 1 and 2, very flat spectra are observed with a ratio of 2.1. At a ratio of 2.5 (Comparative Example 3), the reflection spectrum becomes less flat again. The ratio of the optical thickness of the optically high-refractive-index layer sequence 21f to the optical thickness of the optically low-refractive-index layer 23 should therefore be between 1.8 and 2.3, ideally between 2.0 and 2.2. While the reflectance in the examples according to the invention is lower than in Comparative Examples 1 and 2, it is still sufficiently high (greater than 10% across the entire visible spectral range) to ensure high-intensity HUD projection. In Example 3, a very flat spectrum is also achieved with the aforementioned ratio of 2.1, albeit with a slightly lower reflectance.The design with the reflection-enhancing layer 22 based on a semiconductor therefore appears to be less preferred than the one with the reflection-enhancing layer 22 based on a metal. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT.

[0166] Table 5 lists further parameters of examples 1 to 3 and the comparison example Ibis 3:

[0167] the light transmission TL(A), corresponding to the total transmission according to ECE-R 43, Annex 3, § 9.1,

[0168] the transmission color values ​​a* and b* in the LAB color space, measured at an incidence angle of 0° using mixed-polarized radiation from a standard D65 light source and a 10° detector, and the external reflection color values ​​a* r and b* rin the LAB color space, with a reflection measurement at an angle of incidence and observation angle of 8°, measured with mixed-polarized radiation from a standard light source D65 and a 10° detector,

[0169] the interior integrated total reflectance RL(A), compared to mixed-polarized radiation at an incidence angle and observation angle of 8°, measured with the standard light source A and a 10° detector,

[0170] Table 5

[0171]

[0172] All windshields 10 have a light transmission TL(A) of well over 70% and can therefore be used in road traffic. The outer reflective color a* r / b* r and the transmission color a* / b* are significantly more neutral in the examples according to the invention than in comparative examples 1 and 2 (values ​​a*, b* closer to zero). The external reflection color a* r / b* rdescribes the color impression perceived by an observer looking at the outer surface of the windshield, i.e., located in the vehicle's external environment. The transmission color a* / b* describes the color impression perceived by an observer looking from inside the vehicle through the windshield 10 into the external environment. In both cases, the color impression for the user is significantly more pleasant in the examples than in comparison example 1. The interior reflectance RL(A) describes the reflection SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0173] of ambient light on the interior surface of the inner pane, which is perceived by an observer inside the vehicle as a disturbing reflection. These occur to a significantly lesser extent in the examples according to the invention than in comparative examples 1 and 2.

[0174] The reflective coating 20 acts as an anti-reflective coating - the reflection on the interior surface IV of the inner disk 2, especially towards s-polarized radiation, is reduced compared to an uncoated disk.

[0175] In summary, the optical properties of the windshield 10 are significantly improved by the reflective coating 20 according to the invention with the ratio according to the invention of the optical thickness of the optically high-refractive-index layer sequence 21f to the optical thickness of the optically low-refractive-index layer 23. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT

[0176] Reference symbol list:

[0177] (10) Windshield

[0178] (1) Outer pane

[0179] (2) Inner disc

[0180] (3) thermoplastic intermediate layer

[0181] (4) imaging unit

[0182] (5) Observer / Driver

[0183] (6) Cover printing

[0184] (20) Reflective coating

[0185] (21) (single) optically high-refractive-index layer

[0186] (21 f) optically high refractive index sequence

[0187] (21.1) first optically high-refractive layer of the layer sequence 21 f

[0188] (21.2) second optically high-refractive layer of the layer sequence 21 f

[0189] (21.3) third optically high-refractive layer of the layer sequence 21 f

[0190] (22) reflection-enhancing layer

[0191] (23) (single) optically low refractive index layer

[0192] (O) Top edge of the windscreen 10

[0193] (U) Lower edge of the windscreen 10

[0194] (D) Windscreen viewing area 10

[0195] (M) Windscreen masking area 10

[0196] (B) Windscreen display area 10

[0197] (E) Eyebox

[0198] (a) angle of incidence

[0199] (I) outer surface of the outer pane 1

[0200] (11) interior surface of the outer pane 1

[0201] (III) outer surface of the inner pane 2

[0202] (IV) interior surface of the inner pane 2

[0203] Y -Y' Intersection line

[0204] Z enlarged section

Claims

34 SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT 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), wherein the windscreen (10) has a display area (B), wherein a reflective coating (20) is arranged on the interior surface (IV) of the inner disc (2) at least in the display area (B), which is suitable for reflecting radiation in the visible spectral range, and which comprises in the specified order starting from the interior surface (IV) of the inner disc (2): - an optically high-refractive-index layer (21) or layer sequence (21f) with a refractive index greater than 1.9 - a reflection-enhancing layer (22) based on a metal or semiconductor, which is optionally fully or partially oxidized, - an optically low refractive index layer (23) or sequence of layers with a refractive index of less than 1.6, wherein the ratio of the optical thickness of the optically high refractive layer (21) or layer sequence (21f) to the optical thickness of the optically low refractive layer (23) or layer sequence is from 1.8 to 2.

3.

2. Windscreen (10) according to claim 1, wherein the ratio of the optical thickness of the optically high refractive index layer (21) or layer sequence (21 f) to the optical thickness of the optically low refractive index layer (23) or layer sequence is from 2.0 to 2.

2.

3. Windscreen (10) according to claim 1 or 2, wherein the optically high refractive index layer (21) or layer sequence (21f) has an optical thickness of 150 nm to 300 nm, preferably from 200 nm to 270 nm, particularly preferably from 200 nm to 250 nm, most preferably from 220 nm to 250 nm.

4. Windscreen (10) according to one of claims 1 to 3, wherein the optically high refractive index layer (21) or each individual layer of the optically high refractive index layer sequence (21f) is based on titanium oxide, silicon nitride, silicon-35 SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT is formed from metal mixed nitride, tungsten oxide, niobium oxide, aluminum nitride, bismuth oxide, tantalum oxide, hafnium oxide, chromium oxide, tin oxide, zirconium oxide, titanium zirconium oxide, silicon zirconium oxide, hafnium oxide or tin zinc oxide.

5. Windscreen (10) according to one of claims 1 to 4, wherein the optically high refractive index layer or layer sequence is formed as a layer sequence (21f) from a plurality of optically high refractive index layers (21.1, 21.2, 21.3) of different materials, wherein all optically high-refractive layers (21.1, 21.2, 21.3) preferably have a thickness of at most 80 nm, particularly preferably at most 60 nm, and wherein at least one optically high-refractive layer (21.1, 21.2, 21.3) preferably has a refractive index of more than 2.

1.

6. Windscreen (10) according to one of claims 1 to 5, wherein the reflection-enhancing layer (22) has a thickness of 1 nm to 10 nm, preferably from 1 nm to 8 nm, particularly preferably from 2 nm to 8 nm, most preferably from 2 nm to 5 nm.

7. Windscreen (10) according to one of claims 1 to 6, wherein the reflection-enhancing layer (22) is based on platinum, ruthenium, rhodium, palladium, osmium, iridium, titanium, zirconium, hafnium, niobium, tantalum, nickel, chromium, aluminium, silicon, germanium, α-tin or a silicon-aluminium alloy.

8. Windscreen (10) according to one of claims 1 to 7, wherein the optically low refractive index layer (23) or layer sequence has an optical thickness of 50 nm to 200 nm, preferably of 100 nm to 200 nm, particularly preferably of 100 nm to 150 nm, most preferably of 110 nm to 140 nm.

9. Windscreen (10) according to one of claims 1 to 8, wherein the optically low refractive index layer (23) or layer sequence is formed as a single layer based on silicon oxide.

10. Windshield (10) according to one of claims 1 to 9, wherein the windshield (10) has a transparent viewing area (D) and a SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT opaque masking area (M) and wherein the display area (B) is arranged in the see-through area (D).

11. Windscreen (10) according to one of claims 1 to 10, wherein the outer surface (I) of the outer pane (1) and the inner surface (II) of the inner pane (2) are arranged at a wedge angle to each other.

12. Method for manufacturing a windshield (10) according to any one of claims 1 to 11, comprising at least the following process steps in the specified order: (1) Provide the inner disc (2), (2) Applying the reflective coating (20) to a surface (IV) of the inner disc (2) at least in the display area (B), wherein a. the optically high refractive index layer (21) or layer sequence (21 f), b. the reflection-enhancing layer (22) based on a metal or semiconductor, c. the optically low refractive index layer (23) or layer sequence, deposited on the surface in the specified order, (3) optionally carrying out a thermal transformation process, in particular a thermal prestressing process or bending process, wherein the reflection-enhancing layer (22) is partially or completely oxidized, (4) Connecting the inner disk (2) to the outer disk (1) via the intermediate layer (3), wherein the surface (IV) of the inner disk (2) with the reflective coating (20) is turned away from the intermediate layer (3).

13. Display system for a vehicle, comprising - a windshield (10) according to one of claims 1 to 11, - an imaging unit (4) which is directed towards and illuminates the display area (B).

14. Display system according to claim 13, wherein the radiation of the imaging unit (4) has a p-polarized component of at least 50% and is preferably mixed polarized with a ratio of p-polarized to s-polarized radiation components of 80% / 20% to 50% / 50%. SAINT-GOBAIN SEKURIT FRANCE 2025043-WO-PCT 15. Display system according to claim 13 or 14, wherein the imaging unit (4) irradiates the display area (B) with an angle of incidence (a) of 60° to 70°.

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