WO2019206493A1

WO2019206493A1 - Composite pane having electrically conductive coating and anti-reflective coating

Info

Publication number: WO2019206493A1
Application number: PCT/EP2019/054176
Authority: WO
Inventors: Klaus Fischer; Jan Hagen
Original assignee: Saint-Gobain Glass France
Priority date: 2018-04-26
Filing date: 2019-02-20
Publication date: 2019-10-31
Also published as: CN110650844A

Abstract

The invention relates to a composite pane (10), in particular for a head-up display, at least comprising an outer pane (1) and an inner pane (2) which are connected to one another via a thermoplastic intermediate layer (3); an electrically conductive coating (20) on the surface (II, III) of the outer pane (1) facing the intermediate layer (3), or on the inner pane (2) or within the intermediate layer (3); and an anti-reflective coating (30) on the surface (IV) of the inner pane (2) facing away from the intermediate layer (3), wherein the composite pane (10) has a transmission in the visible spectral range of at least 70% and the electrically conductive coating (20) has a sheet resistance of max. 0.65 Ω/□. The electrically conductive coating (20) comprises at least four electrically conductive layers (21), which are each arranged between two dielectric layers or layer sequences, and the total thickness of all electrically conductive layers (21) is at least 60 nm.

Description

Composite disc with electrically conductive coating and

Anti-reflection coating

The invention relates to a composite pane and a projection arrangement for a head-up display.

It is known to provide windshields with transparent, electrically conductive coatings. These coatings can act as IR reflective coatings to reduce the heating of the vehicle interior and thereby improve thermal comfort. However, the coatings can also be used as heatable coatings by being connected to a voltage source so that a current flows through the coating. Suitable coatings include conductive, metallic layers based on silver. Since these layers are susceptible to corrosion, it is common to apply them to the intermediate layer facing surface of the outer pane or the inner pane, so that they have no contact with the atmosphere. Silver-containing transparent coatings are known, for example, from WO 03/024155, US 2007/0082219 A1, US 2007/0020465 A1, WO2013 / 104438 or WO2013 / 104439.

WO02007015861A2 and WO2013104439A1 disclose further composite panes with a heatable coating comprising three electrically conductive layers.

In order to achieve the best possible heating power for a given supply voltage, which is typically about 14 V in vehicles, the electrically conductive coating should have the lowest possible sheet resistance. The lowering of the sheet resistance is possible in particular by an increase in the amount of conductive material, that is, by a thicker configuration of the electrically conductive layers or a higher number of electrically conductive layers.

However, a higher amount of conductive material results in a reduction in the transparency of the windshield. The typically metalliferous conductive layers reduce the transmission in the visible spectral range. However, since a windscreen has to meet strict minimum transparency requirements (at least 70% transmission in the visible spectral range according to Regulation 43 of the United Nations Economic Commission for Europe (ECE R 43)), the amount of conductive material is limited. Modern automobiles are increasingly equipped with so-called head-up displays (HUDs). With a projector, typically in the area of the dashboard, images are projected onto the windshield, reflected there and perceived by the driver as a virtual image (seen from it) behind the windshield. Thus, important information can be projected into the driver's field of vision, for example the current driving speed, navigation or warning notices that the driver can perceive without having to turn his eyes off the road. Head-up displays can thus contribute significantly to increasing traffic safety.

In the head-up displays described above, the problem arises that the projector image is reflected on both surfaces of the windshield. As a result, the driver not only perceives the desired main image caused by the reflection on the inside surface of the windshield (primary reflection). The driver also perceives a slightly offset, generally low-intensity sub-picture, which is caused by the reflection on the outside surface of the windshield (secondary reflection). The latter is commonly referred to as a ghost ("ghost"). This problem is commonly solved by arranging the reflective surfaces at a deliberately chosen angle to each other so that the main image and the ghost image are superimposed, whereby the ghost image is no longer distracting.

Windshields consist of two glass panes, which are laminated together via a thermoplastic film. If the surfaces of the glass sheets are to be arranged at an angle as described, it is customary to use a thermoplastic film of non-constant thickness. One speaks of a wedge-shaped foil or wedge foil. The angle between the two surfaces of the film is called the wedge angle. The wedge angle can be constant over the entire film (linear change in thickness) or change in a position-dependent manner (nonlinear change in thickness). Laminated glasses with wedge foils are known, for example, from W02009 / 071135A1, EP1800855B1 or EP1880243A2.

If the windshield has an electrically conductive coating, the coating forms a further reflective interface for the projector image. This leads to another unwanted subpicture, which is also referred to as layer ghost or layer "ghost". WO2017157660A1 discloses a composite pane with an electrically conductive coating as a projection surface for a HUD. The layer ghosting is reduced by the use of a very thin inner pane. Requirements for the coating are not disclosed.

WO2017198363A1 also discloses a composite pane having an electrically conductive coating as a projection surface for a HUD. In the single embodiment, the coating has four electrically conductive layers, with a total thickness of 57 nm.

US6068914A discloses a composite disk with an antireflection coating.

The invention has for its object to provide an improved composite disc with electrically conductive coating. The composite disk should have a low sheet resistance despite a high transmission and be particularly suitable for a head-up display (HUD).

The object of the present invention is achieved by a composite pane according to claim 1. Preferred embodiments will become apparent from the dependent claims.

The advantages of the composite pane according to the invention are based on the combination of an electrically conductive coating with an antireflection coating. The antireflection coating reduces the reflection of the composite disc, which increases its transmission in the visible spectral range. As a result, the amount of the conductive material of the electrically conductive coating can be increased, in particular the layer thickness of the conductive layers contained, without the transparency being reduced to such an extent that the composite pane would no longer be suitable as a vehicle windshield. In turn, increasing the amount of conductive material lowers the sheet resistance of the coating, thereby increasing its heating power at a given supply voltage. The invention therefore enables the production of heated windshield with increased heating power.

The composite pane according to the invention comprises an outer pane and an inner pane, which are connected to one another via a thermoplastic intermediate layer. The composite pane is intended, in a window opening, in particular the window opening of a vehicle, the interior space with respect to the external environment separate. With inner pane in the sense of the invention, the interior of the interior (in particular vehicle interior) facing disc of the composite pane is called. With outer pane, the outer environment facing disc is called. The composite pane is preferably a vehicle windshield (in particular the windshield of a motor vehicle, for example a passenger or heavy goods vehicle).

The composite disc has an upper edge and a lower edge and two side edges extending therebetween. With the upper edge that edge is referred to, which is intended to point in the installed position upwards. The lower edge is the edge which is intended to point downwards in the installed position. The upper edge is often referred to as the roof edge and the lower edge as the engine edge.

The outer pane and the inner pane each have an outer side and an inner side surface and an intervening, circumferential side edge. For the purposes of the invention, the outside surface is that main surface which is intended to face the outside environment in the installed position. With interior side surface is referred to in the sense of the invention, that main surface, which is intended to be facing the interior in the installed position. The inner side surface of the outer disk and the outer side surface of the inner disk face each other and connected to each other through the thermoplastic intermediate layer.

The composite pane is provided in a preferred embodiment for a head-up display and has a so-called HUD area. The HUD area is the area that can be irradiated by a HUD projector. The HUD area is intended to be irradiated by a projector for generating the HUD image. There, the radiation is reflected in the direction of the viewer (driver), whereby a virtual image is generated, which the viewer perceives seen from behind the windshield.

The composite pane also has a transparent, electrically conductive coating. The electrically conductive coating is preferably applied to the outer surface of the inner pane facing towards the intermediate layer or on the inner side surface of the outer pane facing the intermediate layer. The coating may alternatively be disposed within the intermediate layer. This is the Coating typically applied to a carrier foil, for example of polyethylene terephthalate (PET) with a thickness of about 50 pm, which is arranged between two layers of thermoplastic material, for example between two polymer films. A transparent coating is understood as meaning a coating which has an average transmission in the visible spectral range of at least 70%, preferably at least 75%, which therefore does not significantly limit the viewing through the pane.

The composite pane also has an antireflection coating, which is applied on the interior side surface of the inner pane facing away from the intermediate layer.

The invention provides a composite disk with a high transmission in the visible spectral range and with a low sheet resistance of the conductive coating, which allows a high heating power. According to the invention, composite disks with a transmission in the visible spectral range of at least 70% can be realized and with a sheet resistance of the electrically conductive coating of at most 0.65 W / p, preferably at most 0.60 W / p. The transmission in the visible spectral range is determined according to the procedure defined by ECE-R 43, Annex 3, § 9.1 for testing the light transmission of vehicle windows. The transmission in the visible spectral range is preferably at least 70.5%, more preferably at least 71%.

The electrically conductive coating can be provided, for example, as an IR-reflecting sunscreen coating or as a heatable coating, which is electrically contacted and heated when the current flows through. Preferably, at least 80% of the disk surface is provided with the coating according to the invention. In particular, the composite disk is provided with the coating over its entire area, with the exception of a peripheral edge region and optionally local area, which are intended as communications, sensor or camera windows to ensure the transmission of electromagnetic radiation through the composite disk and are therefore not provided with the coating. The circumferential uncoated edge region has, for example, a width of up to 20 cm. It prevents direct contact of the coating with the surrounding atmosphere, so that the coating inside the composite pane is protected against corrosion and damage. When the electrically conductive coating is provided as a heatable coating, it is typically provided with busbars connected to connecting cables which extend beyond the side edge of the composite disk. By means of the connecting cables, the busbars can be connected to an external voltage source. The bus bars are arranged in the edge region along two opposite side edges along a large part of the entire coating width and conduct the electric current as homogeneously as possible into the conductive coating. The bus bars are typically formed as strips of a conductive foil (eg, copper foil) and placed on or over the coating, or printed as a conductive paste (typically containing silver particles and glass frit) on the coating or on the pane under the coating.

The electrically conductive coating is preferably a layer stack or a layer sequence comprising one or more electrically conductive, in particular metal-containing layers, each electrically conductive layer being arranged in each case between two dielectric layers or layer sequences. The coating is therefore a thin-layer stack with n electrically conductive layers and (n + 1) dielectric layers or layer sequences, where n is a natural number and where a lower dielectric layer or layer sequence is alternately a conductive layer and a dielectric layer or layer sequence follows. Such coatings are known as sunscreen coatings and heatable coatings, wherein the electrically conductive layers are typically formed on the basis of silver. In addition to the conductive layers and the dielectric layers or layer sequences, the coating may contain further metallic layers, in particular thin blocking layers, for example based on NiCr or Ti.

The conductive coating preferably has a plurality of electrically conductive layers, that is to say at least two electrically conductive layers, particularly preferably at least three electrically conductive layers, very particularly preferably at least four electrically conductive layers. The higher the number of conductive layers, the better the coating can be optimized with regard to a desired transmittance, coloring or a desired surface resistance.

The antireflection layer according to the invention makes it possible to use thicker electrically conductive layers and thereby to reduce the sheet resistance and the Increase conductivity. The total thickness of all electrically conductive layers is at least 60 nm in an advantageous embodiment.

By the functional, electrically conductive layers, the electrical conductivity of the coating is effected. By dividing the entire conductive material into several separate layers, they can each be made thinner, which increases the transparency of the coating. Each electrically conductive layer preferably contains at least one metal or a metal alloy, for example silver, aluminum, copper, palladium, platinum or gold, and is particularly preferably formed on the basis of the metal or the metal alloy, that is to say consists essentially of the metal or the metal alloy apart from any dopants or impurities. Preferably, silver or a silver-containing alloy are used. In an advantageous embodiment, the electrically conductive layer contains at least 90% by weight of silver, preferably at least 99% by weight of silver, particularly preferably at least 99.9% by weight of silver.

The disc is particularly advantageous for a head-up display, if the electrically conductive coating and the anti-reflection coating are optimized with regard to their optical properties especially for this purpose, which will be described below.

The radiation of the HUD projector typically hits the composite wafer at an angle of incidence of about 65 °. The angle of incidence is the angle between the incident vector of the projector radiation and the surface normal in the geometric center of the HUD area. Since this angle of incidence is relatively close to the Brewster angle for an air-glass transition (57.2 °), only s-polarized radiation is efficiently reflected by the disk surfaces, while p-polarized radiation is hardly reflected. For this reason, the radiation of HUD projectors is typically purely s-polarized. Conventional HUD projectors emit three wavelengths (RGB): 473 nm, 550 nm and 630 nm.

The antireflection coating according to the invention on the interior-side surface of the inner pane significantly reduces the reflection of the projector radiation on this surface. The HUD projection is therefore based mainly on the reflection on the outside surface of the outer pane. On the one hand, this has a positive effect on the problem of ghost images: the ghost image as a result of the reflection on the interior surface is very weak in intensity, so that it is sometimes not disturbing is perceptible. On the other hand, however, the overall intensity of the HUD projection is reduced. In order to increase the overall intensity again, the coatings are preferably adjusted in such a way that they contribute to the reflection of s-polarized radiation and thus to the intensity of the HUD projection. In particular, the reflection on the electrically conductive coating is responsible, but also the design of the anti-reflection coating has an influence.

In a preferred embodiment, the coatings are adjusted such that the composite pane having the coatings at wavelengths of 473 nm, 550 nm and 630 nm has a reflectivity for s-polarized radiation of at least 15%, preferably at least 20%, particularly preferably at least 25%. , Thus, the RGB radiation of conventional projectors is sufficiently reflected to produce a high-intensity HUD image. The reflectance describes the proportion of total irradiated radiation that is reflected. It is given in% (based on 100% radiated radiation) or as a unitless number from 0 to 1 (normalized to the radiated radiation). Plotted as a function of the wavelength, it forms the reflection spectrum. The specified values for the reflectance of the composite pane are measured when the inner pane is irradiated (interior reflection) with an angle of incidence and a detection angle of 65 ° (angle to the surface normal).

The standard deviation of the reflectivities at wavelengths of 473 nm, 550 nm and 630 nm (stated in%, based on 100%) is preferably not more than 10%, particularly preferably not more than 6%, in order to ensure as color-true HUD imaging as possible.

In conventional composite disks for HUDs, the reflectance for s-polarized radiation is primarily determined by the reflections on the outside and inside disk surfaces, but in the composite disk according to the invention primarily by the reflections on the outside disk surface and the electrically conductive coating. The desired reflectivity of the composite disk is therefore significantly influenced by the reflectivity of the conductive coating. In order to contribute to a high-intensity HUD image and in particular to achieve the above-mentioned preferred reflection values of the composite pane, the electrically conductive coating in a preferred embodiment at wavelengths of 473 nm, 550 nm and 630 nm has a reflectivity for s-polarized radiation of at least 3 %, more preferably at least 4%. In a very particularly preferred embodiment, the electrically conductive Coating at a wavelength of 473 nm, a reflectance of at least 6%, at a wavelength of 550 nm, a reflectance of at least 4% and at a wavelength of 630 nm, a reflectance of at least 15% (for s-polarized radiation). The reflectance of the coating can be determined, for example, by simulations (for example with the customary simulation program CODE) or by measurement against a reference disk of the same design, but without an electrically conductive coating. It is determined under the same experimental conditions as described above in relation to the reflectance of the composite disc.

However, when designing the coatings, the person skilled in the art can not only consider the reflection spectrum of the composite pane, but has to take into account further boundary conditions. This applies in particular to the color effect of the composite pane, since the vehicle manufacturers only accept panes with a green-blue coloration, but not a yellow or red coloration (in relation to the reflection color). In a preferred embodiment, the coatings are adjusted such that the composite disc has an a ^* color value of less than 1, more preferably less than 0 and a b ^* color value of less than 1, more preferably less than 0. Thus, the composite disc suitable for use as a windshield in the vehicle area. The specified color values describe the reflection color of the composite pane and relate to the L ^* a ^* b ^* color space (also: lab color space), which is described in EN ISO 11664-4 "Colorimetry - Part 4: CIE 1976 L ^* a ^* b ^* Color space "and the newer DIN EN 410 is standardized.

The specified color values a ^* , b ^* of less than 1, preferably less than 0, relate at least to the outside reflection color under irradiation with the light source D65 and angles of incidence of 8 ° and 60 ° (angle to the surface normal), measured on irradiation of the outer pane with radiation of mixed polarization (50% s, 50% p) and measurement conditions specified in the standards mentioned with D65 / 10 ⁰ .

In a particularly preferred embodiment, the specified color values a ^* , b ^* of less than 1, preferably less than 0, also relate to the interior-side reflection color under irradiation with the light source D65 and an angle of incidence of 1 15 ° (angle to the surface normal) when irradiating the inner pane with s-polarized radiation and measuring conditions specified in the standards mentioned with D65 / 10 ⁰ . This measurement simulates the irradiation with a HUD projector the color values ensure playback of the HUD projection without disturbing color shift.

The intermediate layer may optionally (at least in the HUD range) be wedge-shaped or wedge-shaped, so that the thickness of the intermediate layer in the vertical course between the lower edge and the upper edge of the composite disc, at least in the HUD range variable, in particular monotonously increasing. However, the thickness can also change over the entire vertical course, in particular starting monotonically from the lower edge to the upper edge. With a vertical course, the course between the lower edge and the upper edge with the course direction is substantially perpendicular to said edges. The angle between the two surfaces of the intermediate layer is called the wedge angle. If the wedge angle is not constant, the tangents to the surfaces should be used for its measurement at one point. The wedge angle can be constant in the vertical course, resulting in a linear change in thickness of the intermediate layer, wherein the thickness is typically larger from bottom to top. The direction "from bottom to top" designates the direction from lower edge to upper edge, ie the vertical curve. But there may also be more complex thickness profiles in which the wedge angle is variable from bottom to top (that is location-dependent in the vertical course), linear or non-linear. The intermediate layer is preferably formed of at least one polymer film, which is partially or completely formed as a so-called wedge film.

The wedge angle is designed according to the requirements in the application. Thus, the wedge angle may be suitably selected in order to superimpose the projection images, which are caused by the reflections on the electrically conductive coating on the one hand and on the outside surface of the outer pane, on one another or at least reduce their distance from one another (reduction of the layer ghost image). , Alternatively, the wedge angle may be suitably selected to superimpose or at least reduce the distance of the projection images caused by the reflections on the outside surface of the outside disk on the one hand and on the inside surface of the inside disk on the other hand. Although the reflection on the interior-side surface of the inner pane is reduced by the antireflection coating, the wedge angle can also be used to avoid any remaining ghost image (wafer ghosting). Also, a compromise between the two embodiments is conceivable in which the wedge angle is selected according to a kind of mean, so that the expression of both the Layer ghost image as well as the disk ghost image is reduced. Due to the wedge angle, the respective reflection planes are not parallel to one another and precisely include those wedge angles. In the case of parallel reflection surfaces image (generated by reflection on the outside surface of the outer pane) and ghost image (generated by reflection of the conductive coating or by reflection on the interior side surface of the inner pane) would appear offset to each other, which is disturbing to the viewer. Due to the wedge angle, the ghost image is essentially superimposed spatially with the image, so that the viewer only perceives a single image or the distance between image and ghost image is at least reduced. Typical wedge angles are in the range of 0.3 mrad to 0.7 mrad, in particular from 0.4 mrad to 0.5 mrad.

In one embodiment of the invention, the electrically conductive layer is applied to the outside surface of the inner pane. The outer surface of the outer pane (reflection image for the main image) and the electrically conductive coating (reflection surface for the layer ghost) then have a relatively large distance from each other, so that the main image and layer ghost are clearly offset from each other. The layer ghost can then attract attention. In this embodiment, the intermediate layer is preferably wedge-shaped, at least in the HUD region, in order to avoid or mitigate the occurrence of the layer ghost image. The reflection on the interior-side surface of the inner pane is typically sufficiently reduced by the antireflection coating, so that no disturbing ghosting is caused thereby.

In a further embodiment of the invention, the electrically conductive layer is applied to the interior-side surface of the outer pane. The outside surface of the outer pane (reflection surface for the main image) and the electrically conductive coating (reflection surface for the layer ghost) then have a relatively small distance from each other, so that the main image and layer ghost image are offset only slightly from one another. The layer ghost then often comes to only acceptable levels to light. In this embodiment, the intermediate layer is not formed wedge-like, but has in the vertical course between the lower edge and upper edge substantially a constant thickness (without taking into account the usual surface roughness of polymer films). The intermediate layer can then be made of standard films of constant thickness, which are much cheaper than wedge films. The reflection on the interior-side surface of the inner pane is typically sufficiently reduced by the antireflection coating, so that no disturbing Ghost picture is caused. Another advantage of this embodiment is that the conductive coating and the antireflection coating are deposited on different wafers. The production of the composite pane is thereby simplified because the double-sided coating of a substrate is technically more complicated.

The electrically conductive coating is preferably a layer stack or a layer sequence comprising a plurality of electrically conductive layers, wherein each electrically conductive layer is in each case arranged between two dielectric layers or layer sequences. The dielectric layers or layer sequences are advantageously designed using materials known per se, the properties according to the invention being set by a suitable choice of the respective layer thicknesses.

Dielectric layers or layer sequences are arranged between the electrically conductive layers and below the lowermost conductive layer and above the uppermost conductive layer. Each dielectric layer or layer sequence preferably has at least one antireflection coating. The antireflection coatings reduce the reflection of visible light and thus increase the transparency of the coated disc. The antireflection coatings contain, for example, silicon nitride (SiN), silicon-metal mixed nitrides such as silicon zirconium nitride (SiZrN), tin oxide (ZnO) or tin-zinc oxide (SnZnO). The antireflection coatings may also have dopants. The layer thickness of the individual anti-reflection layers is preferably from 20 nm to 70 nm.

The antireflection layers can in turn be subdivided into at least two sublayers, in particular into a dielectric layer with a refractive index of less than 2.1 and a optically high refractive index layer with a refractive index greater than or equal to 2.1. Preferably, at least one antireflective layer arranged between two electrically conductive layers is subdivided in such a way, particularly preferably each antireflection layer arranged between two electrically conductive layers. The subdivision of the anti-reflection layer leads to a lower sheet resistance of the electrically conductive coating with simultaneously high transmission and high color neutrality. In principle, the sequence of the two partial layers can be chosen as desired, wherein the optically high-index layer is preferably arranged above the dielectric layer, which is particularly advantageous with regard to sheet resistance. The thickness of the optically high-index layer is preferably from 10% to 99%, particularly preferably from 25% to 75%, most preferably from 30% to 45% of the total thickness of the antireflection coating.

The optically high refractive index layer having a refractive index greater than or equal to 2.1 comprises, for example, WO3, Nb20s, B12O3, T1O2 and / or Zr3N _4, preferably a silicon-metal mixed nitride, for example silicon-aluminum mixed nitride, silicon-hafnium composite nitride or silicon Mixed titanium nitride, more preferably silicon-zirconium mixed nitride (SiZrN). This is particularly advantageous with regard to the sheet resistance of the electrically conductive coating. The silicon-zirconium mixed nitride preferably has dopants. The layer of optically high refractive index material may, for example, contain an aluminum-doped mixed silicon-zirconium nitride. The zirconium content of the mixed silicon-zirconium nitride is preferably from 15% by weight to 45% by weight.

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

In a preferred embodiment, each anti-reflection layer arranged between two electrically conductive layers is subdivided into a dielectric layer having a refractive index of less than 2.1 and an optically high-refractive index layer having a refractive index greater than or equal to 2.1. The thickness of each anti-reflection layer arranged between two electrically conductive layers is from 40 nm to 60 nm. The anti-reflection layers above the uppermost electrically conductive layer and below the lowermost electrically conductive layer may likewise be subdivided, but are preferably formed as individual layers and each have a thickness of 20 nm to 35 nm.

In an advantageous embodiment, one or more dielectric layer sequences has a first matching layer, preferably each dielectric layer sequence, which is arranged below an electrically conductive layer. The first adaptation layer is preferably arranged above the antireflection coating.

In an advantageous embodiment, one or more dielectric layer sequences have a smoothing layer, preferably each dielectric layer sequence, which is arranged between two electrically conductive layers. The smoothing layer is arranged below one of the first matching layers, preferably between the anti-reflection layer and the first matching layer. The smoothing layer is particularly preferably in direct contact with the first matching layer. The smoothing layer effects an optimization, in particular smoothing of the surface for a subsequently applied electrically conductive layer. An electrically conductive layer deposited on a smoother surface has a higher transmittance with a simultaneously lower surface resistance. The layer thickness of a smoothing layer is preferably from 3 nm to 20 nm, more preferably from 5 nm to 10 nm. The smoothing layer preferably has a refractive index of less than 2.2.

The smoothing layer preferably contains at least one non-crystalline oxide. The oxide may be amorphous or partially amorphous (and thus partially crystalline) but is not completely crystalline. The non-crystalline smoothing layer has a low roughness and thus forms an advantageously smooth surface for the layers to be applied above the smoothing layer. The non-crystalline smoothing layer further effects an improved surface structure of the layer deposited directly above the smoothing layer, which is preferably the first matching layer. The smoothing layer may contain, for example, at least one oxide of one or more of the elements tin, silicon, titanium, zirconium, hafnium, zinc, gallium and indium. The smoothing layer particularly preferably contains a non-crystalline mixed oxide. The smoothing layer very particularly preferably contains a tin-zinc mixed oxide (ZnSnO). The mixed oxide may have dopants. The smoothing layer may contain, for example, an antimony-doped tin-zinc mixed oxide. The mixed oxide preferably has a substoichiometric oxygen content. The tin content of the tin-zinc mixed oxide is preferably from 12% by weight to 50% by weight.

In an advantageous embodiment, one or more dielectric layer sequences has a second adaptation layer, preferably each dielectric layer sequence, which is arranged above an electrically conductive layer. The second adaptation layer is preferably arranged below the antireflection coating.

The first and second matching layers improve the sheet resistance of the coating. The first matching layer and / or the second matching layer preferably contains zinc oxide ZnOi- _d with 0 <d <0.01. The first matching layer and / or the second matching layer more preferably contains Dopants. The first matching layer and / or the second matching layer may contain, for example, aluminum-doped zinc oxide (ZnO: Al). The zinc oxide is preferably deposited substoichiometrically with respect to the oxygen in order to avoid a reaction of excess oxygen with the silver-containing layer. The layer thicknesses of the first matching layer and the second matching layer are preferably from 3 nm to 20 nm, more preferably from 8 nm to 12 nm.

In an advantageous embodiment, the electrically conductive coating comprises one or more blocking layers. At least one, particularly preferably each electrically conductive layer is preferably assigned at least one blocking layer. The blocker layer is in direct contact with the electrically conductive layer and is arranged directly above or immediately below the electrically conductive layer. Thus, no further layer is arranged between the electrically conductive layer and the blocking layer. The blocking layer preferably contains niobium, titanium, nickel, chromium and / or alloys thereof, particularly preferably nickel-chromium alloys. The layer thickness of the blocking layer is preferably from 0.1 nm to 2 nm, particularly preferably from 0.1 nm to 1 nm. A blocking layer immediately below the electrically conductive layer serves, in particular, to stabilize the electrically conductive layer during a temperature treatment and improves the optical quality the electrically conductive coating. A blocker layer immediately above the electrically conductive layer prevents contact of the sensitive electrically conductive layer with the oxidizing reactive atmosphere during the deposition of the following layer by reactive sputtering, for example the second matching layer.

If a first layer is arranged above a second layer, this means in the sense of the invention that the first layer is arranged further away from the substrate on which the coating is applied than the second layer. If a first layer is arranged below a second layer, this means in the sense of the invention that the second layer is arranged further from the substrate than the first layer. If a first layer is arranged above or below a second layer, this does not necessarily mean within the meaning of the invention that the first and the second layer are in direct contact with one another. One or more further layers may be arranged between the first and the second layer, unless this is explicitly excluded. The indicated values for refractive indices are measured at a wavelength of 550 nm. The electrically conductive coating with the preferred optical properties can basically be realized in various ways, preferably using the layers described above, so that the invention is not limited to a specific layer sequence. In the following, a particularly preferred embodiment of the coating is presented, with which particularly good results are achieved, in particular with a typical angle of incidence of the radiation of about 65 °.

In the particularly preferred embodiment, the conductive coating has at least four, in particular exactly four, electrically conductive layers. Each electrically conductive layer preferably has a layer thickness of 10 nm to 20 nm. The total layer thickness of all electrically conductive layers is preferably from 60 nm to 70 nm.

The electrically conductive coating contains, starting from the substrate (ie the disk or film on which the coating is deposited) in particular the following layer sequence, or consists of this:

an antireflection coating, in particular based on silicon nitride, having a thickness of 25 nm to 33 nm,

a first matching layer, in particular based on zinc oxide, with a thickness of 8 nm to 12 nm, in particular approximately 10 nm,

an electrically conductive layer based on silver with a thickness of 10 nm to 17 nm,

optionally a blocking layer, in particular based on NiCr, with a thickness of 0.1 nm to 0.5 nm,

a second adaptation layer, in particular based on zinc oxide, having a thickness of 8 nm to 12 nm, in particular approximately 10 nm,

an antireflection coating having a thickness of 50 nm to 55 nm, preferably subdivided into a dielectric layer, in particular based on silicon nitride, with a thickness of 32 nm to 35 nm and above an optically high refractive index layer, in particular based on a silicon-metal oxide. Mixed nitrides such as silicon zirconium nitride or silicon hafnium nitride, with a thickness of 18 nm to 22 nm,

a smoothing layer, in particular based on tin-zinc mixed oxide, with a thickness of 5 nm to 9 nm, a first matching layer, in particular based on zinc oxide, with a thickness of 8 nm to 12 nm, in particular approximately 10 nm,

an electrically conductive layer based on silver with a thickness of 15 nm to 19 nm,

an antireflection coating having a thickness of 47 nm to 52 nm, preferably subdivided into a dielectric layer, in particular based on silicon nitride, with a thickness of 28 nm to 32 nm and above an optically high refractive index layer, in particular based on a silicon-metal oxide. Mixed nitrides such as silicon zirconium nitride or silicon hafnium nitride, with a thickness of 18 nm to 22 nm,

a smoothing layer, in particular based on tin-zinc mixed oxide, with a thickness of 5 nm to 9 nm,

an electrically conductive layer based on silver with a thickness of 12 nm to 17 nm, optionally a blocking layer, in particular based on NiCr, with a thickness of 0.1 nm to 0.5 nm,

an antireflection coating, in particular based on a mixed silicon-metal nitride, such as silicon zirconium nitride or silicon hafnium nitride, with a thickness of 22 nm to 32 nm.

If a layer is formed on the basis of a material, the majority of the layer consists of this material in addition to any impurities or dopings.

The composite pane also has an antireflection coating, which is applied on the interior side surface of the inner pane facing away from the intermediate layer. The antireflection coating increases the light transmission of the composite pane and, moreover, significantly reduces the reflection of the HUD projector radiation on the interior-side surface, so that no or at least no appreciably perceptible HUD image is produced by this reflection.

The antireflection coating can basically be designed in various ways. For example, antireflection coatings of porous silicon dioxide layers are known or those produced by corrosive skeletonization of a glass surface. In a preferred embodiment, however, the antireflection coating is formed from alternately arranged layers with different refractive indices, which due to interference effects lead to a reduction of the reflection at the coated surface. Such coatings are very effective and can be optimized well by the choice of materials and layer thicknesses of the individual layers to the requirements in each case.

The antireflection coating preferably comprises at least two optically high refractive index layers, in particular with a refractive index greater than 1.8, and two optically low refractive index layers, in particular with a refractive index of less than 1.8. Starting from the substrate (the inner pane), a first high refractive index layer, above a first low refractive index layer, above a second high refractive index layer and above a second low refractive index layer is arranged. The high-index layers can, for example, be based on silicon nitride, tin-zinc oxide, silicon Zirconium nitride or titanium oxide, the low-refraction layers based on silicon dioxide.

The antireflection coating is adjusted so that in combination with the electrically conductive coating, the desired optical properties of the composite disc can be achieved. It has been found that particularly suitable antireflection coatings differ from those customary hitherto, in particular by the layer thicknesses of the high-index layers. The first high-index layer preferably has an optical thickness (product of refractive index and layer thickness) of 35 nm to 43 nm, particularly preferably 37 nm to 39 nm. The second high-index layer preferably has an optical thickness of 195 nm to 234 nm, particularly preferably from 204 nm to 215 nm. When silicon nitride is used as the material for the high-index layers having a refractive index of 1.95, this corresponds approximately to layer thicknesses for the first high-index layer of preferably 18 nm to 22 nm, particularly preferably 19 nm 20 nm, and layer thicknesses for the second high-index layer of preferably 100 nm to 120 nm, particularly preferably from 105 nm to 1 10 nm.

In a particularly preferred embodiment, with which good results are achieved, the antireflection coating starting from the substrate (that is to say the interior-side surface of the inner pane) comprises or consists of the following layers:

a layer (high refractive index layer) based on silicon nitride, tin-zinc oxide, silicon-zirconium nitride or titanium oxide with an optical thickness of 29 nm to 49 nm, preferably from 35 nm to 43 nm, particularly preferably from 37 nm to 39 nm, in particular a layer based on silicon nitride with a layer thickness of 15 nm to 25 nm, preferably from 18 nm to 22 nm, particularly preferably from 19 nm to 20 nm,

a layer (low refractive index layer) based on silicon dioxide with a thickness of 20 nm to 25 nm, preferably of 22 nm to 24 nm,

a layer (high-index layer) based on silicon nitride, tin-zinc oxide, silicon-zirconium nitride or titanium oxide with an optical thickness of 195 nm to 234 nm, preferably from 204 nm to 215 nm, in particular based on silicon nitride with a Layer thickness from 100 nm to 120 nm, preferably from 105 nm to 1 10 nm,

a layer (low refractive index layer) based on silicon dioxide with a thickness of 80 nm to 90 nm, preferably from 82 nm to 86 nm. The optical properties also depend on where the conductive coating is located. In a first, particularly preferred embodiment, the conductive

Coating is applied on the outside surface of the inner pane and contains, starting from the inner pane following layer sequence, or consists of this:

an anti-reflection coating based on silicon nitride with a thickness of 26 nm to 27 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

an electrically conductive layer based on silver with a thickness of 15 nm to 16 nm,

optionally a blocking layer, in particular based on NiCr, having a thickness of about 0.1 nm to 0.5 nm, in particular about 0.2 nm,

a second matching layer based on zinc oxide with a thickness of about 10 nm,

an antireflection coating having a thickness of 54 nm to 55 nm, preferably subdivided into a dielectric layer based on silicon nitride having a thickness of 34 nm to 35 nm and above an optically high refractive index layer based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of about 20 nm,

a smoothing layer based on tin-zinc mixed oxide with a thickness of approximately 7 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

a second matching layer based on zinc oxide with a thickness of about 10 nm,

an antireflection coating having a thickness of 49 nm to 50 nm, preferably subdivided into a dielectric layer based on silicon nitride with a thickness of 29 nm to 30 nm and above an optically high refractive index layer based on a mixed silicon-metal nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of about 20 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

an electrically conductive layer based on silver with a thickness of 18 nm to 19 nm, optionally a blocking layer, in particular based on NiCr, having a thickness of about 0.1 nm to 0.5 nm, in particular about 0.2 nm,

a second matching layer based on zinc oxide with a thickness of about 10 nm,

an antireflection coating having a thickness of 53 nm to 54 nm, preferably subdivided into a dielectric layer based on silicon nitride with a thickness of 33 nm to 34 nm and above an optically high refractive index layer based on a mixed silicon-metal nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of about 20 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

an electrically conductive layer based on silver with a thickness of 12 nm to 13 nm,

a second matching layer based on zinc oxide with a thickness of about 10 nm,

an antireflection coating based on a mixed silicon-metal nitride, such as silicon zirconium nitride or silicon hafnium nitride, with a thickness of 29 nm to 30 nm.

The antireflection coating comprises, starting from the inner pane, the following layers:

a layer (high refractive index layer) based on silicon nitride with a thickness of 19 nm to 20 nm,

a layer (low refractive index layer) based on silicon dioxide with a thickness of

22.5 nm to 23.5 nm,

a layer (high refractive index layer) based on silicon nitride with a thickness of 105 nm to 106 nm,

85.5 nm to 86.5 nm.

When specifying a value with the indication "about", a deviation from the specified value of +/- 0.5 nm is permissible, preferably of only +/- 0.2 nm. The term thickness always means the geometric layer thickness, unless explicitly stated the optical thickness is referred to. In a second, particularly preferred embodiment, the conductive coating is applied to the interior-side surface of the outer pane and contains, starting from the outer pane, the following layer sequence, or consists of this:

an anti-reflection coating based on silicon nitride with a thickness of 31 nm to 32 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

- An electrically conductive layer based on silver with a thickness of 1 1, 5 nm to

12.5 nm,

a second matching layer based on zinc oxide with a thickness of about 10 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

an electrically conductive layer based on silver with a thickness of 18 nm to 19 nm,

a second matching layer based on zinc oxide with a thickness of about 10 nm,

an antireflective layer having a thickness of 49.5 nm to 50.5 nm, preferably divided into a dielectric layer based on silicon nitride with a thickness of 29.5 nm to

30.5 nm and above an optically high refractive index layer based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of about 20 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

optionally a blocking layer, in particular based on NiCr, having a thickness of about 0.1 nm to 0.5 nm, in particular about 0.2 nm, a second matching layer based on zinc oxide with a thickness of about 10 nm,

an anti-reflection layer having a thickness of 52.5 nm to 53.5 nm, preferably divided into a dielectric layer based on silicon nitride with a thickness of 32.5 nm to

33.5 nm and above an optically high refractive index layer based on a silicon-metal mixed nitride such as silicon zirconium nitride or silicon hafnium nitride with a thickness of about 20 nm,

a first matching layer based on zinc oxide with a thickness of about 10 nm,

an electrically conductive layer based on silver with a thickness of 16 nm to 17 nm,

a second matching layer based on zinc oxide with a thickness of about 10 nm,

an antireflection coating based on a mixed silicon-metal nitride, such as silicon zirconium nitride or silicon hafnium nitride, with a thickness of 22.5 nm to 23.5 nm.

21.5 nm to 22.5 nm,

a layer (high refractive index layer) based on silicon nitride with a thickness of 109 nm to 110 nm,

81.5 nm to 82.5 nm.

The outer pane and the inner pane are preferably made of glass, in particular of soda-lime glass, which is customary for window panes. In principle, 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 pane and the inner pane can vary widely. Preferably, disks having a thickness in the range of 0.6 mm to 5 mm, preferably from 1, 4 mm to 2.5 mm used, for example, the standard thicknesses 1, 6 mm or 2.1 mm.

The outer pane, the inner pane and the thermoplastic intermediate layer can be clear and colorless, but also tinted or colored. The outer pane and the inner pane can be independently biased, partially biased or biased independently. If at least one of the discs has a bias, this may be a thermal or chemical bias.

The composite panel is preferably bent in one or more directions of the space, as is conventional for automotive windows, with typical radii of curvature ranging from about 10 cm to about 40 m.

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

The composite pane can be produced by methods known per se. The outer pane and the inner pane are laminated together via the intermediate layer, for example, by autoclave method, vacuum bag method, vacuum ring method, calender method, vacuum laminator or combinations thereof. The connection between outer pane and inner pane is usually carried out under the action of heat, vacuum and / or pressure.

The electrically conductive coating and the antireflection coating are preferably applied to the inner pane by physical vapor deposition (PVD), particularly preferably by sputtering (cathode sputtering), very particularly preferably by magnetic field assisted cathode sputtering. The coatings are preferably applied to the discs prior to lamination. Instead of applying the electrically conductive coating to a wafer surface, it can in principle also be provided on a carrier film which is arranged in the intermediate layer. If the composite pane is to be bent, the outer pane and the inner pane are preferably subjected to a bending process prior to lamination and preferably after any coating processes. Preferably, the outer pane and the inner pane are congruently bent together (ie at the same time and by the same tool), because this optimally matches the shape of the panes for the later lamination. Typical temperatures for glass bending processes are for example 500 ° C to 700 ° C.

The invention also includes the use of a composite pane according to the invention in a motor vehicle, preferably a passenger car, truck, bus, ship or aircraft, as a windshield, which serves as a projection surface of a head-up display.

The invention also includes a projection arrangement for a head-up display (HUD). The projection arrangement comprises at least one composite pane according to the invention and a projector which is directed onto the HUD area of the composite pane. The beam direction of the projector can typically be varied by mirrors, in particular vertically, to adapt the projection to the viewer's body size. The area in which the eyes of the beholder must be at the given mirror position is called an eyebox window. This eyebox window can be moved vertically by adjusting the mirrors, whereby the entire accessible area (ie the superimposition of all possible eyebox windows) is called eyebox. An observer within the eyebox can perceive the virtual image. This of course means that the eyes of the beholder must be within the eyebox, not the entire body.

The technical terms used here in the field of HUDs are generally known to the person skilled in the art. For a detailed description, please refer to the dissertation "Simulation-based Measurement Techniques 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 Displays". Up Display ". The radiation of the projector preferably impinges on the composite pane at an angle of incidence of 50 ° to 80 °, in particular 60 ° to 70 °, typically about 65 °, as is customary in HUD projection arrangements. The angle of incidence is the angle between the incident vector of the projector radiation and the surface normal in the geometric center of the HUD area.

The projector is arranged on the inside of the composite pane and irradiates the composite pane over the inside surface of the inner pane. It is aimed at the HUD area and irradiates it to produce the HUD projection. The radiation of the projector is preferably substantially or exclusively s-polarized. This is common in HUD projection arrangements because the angle of incidence is close to the Brewster angle for an air-to-glass transition (57.2 °), and therefore only s-polarized radiation is efficiently reflected from the disc surfaces. Although the reflection on the interior-side surface of the inner pane is weakened by the antireflection coating according to the invention, the conductive coating is adjusted so that it contributes to the reflection of s-polarized radiation and thus to the overall intensity of the HUD projection. With s-polarized radiation is called a radiation whose electric field oscillates perpendicular to the plane of incidence. The plane of incidence is defined by the incident vector and the surface normal of the composite disk in the geometric center of the HUD area.

In the following the invention will be explained in more detail 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.

Show it:

Fig. 1 shows a cross section through a first embodiment of the invention

Laminated pane,

2 shows the composite pane of FIG. 1 as part of a HUD projection arrangement, FIG.

3 is a plan view of the composite pane of Figures 1 and 2,

4 shows a cross section through a second embodiment of the invention

Laminated pane,

5 shows a cross section through a preferred electrically conductive coating,

6 shows a cross section through a preferred antireflection coating,

FIG. 7 shows reflection spectra of a composite pane with an electrically conductive. FIG

Coating according to Figure 4 and a composite disk with a conventional electrically conductive coating. Fig. 1 shows an embodiment of a composite disc 10 according to the invention, which is provided as a windshield of a passenger car. The composite pane 10 is constructed from an outer pane 1 and an inner pane 2, which are connected to one another via a thermoplastic intermediate layer 3. The outer pane 1 faces in the installation position of the external environment, the inner pane 2 the vehicle interior. The outer pane 1 has an outer surface I, which faces in the installed position of the external environment, and an inner side surface II, which faces the interior in the installed position. Likewise, the inner pane 2 has an outer surface III, which faces in the installed position of the external environment, and an inner side surface IV, which faces the interior in the installed position. The lower edge U of the composite disc 10 is arranged downward in the direction of the motor of the passenger car, its upper edge O upwards in the direction of the roof.

The outer pane 1 and the inner pane 2 consist for example of soda-lime glass. The outer pane 1 has, for example, a thickness of 2.1 mm, the inner pane 2 a thickness of 1.6 mm. The intermediate layer 3 is formed from a single layer of thermoplastic material, for example a PVB film having a thickness of 0.76 mm (measured at the lower edge U). The intermediate layer 3 is wedge-shaped with a wedge angle a, so that the thickness of the intermediate layer 3 and thus of the entire composite pane 10 increases from bottom to top. The increase in thickness is shown linearly in the figures for the sake of simplicity, but may also have more complex profiles. The wedge angle a describes the angle between the two surfaces of the intermediate layer and is for example about 0.5 mrad.

The composite pane 10 also comprises an electrically conductive coating 20, which is applied to the outside surface III of the inner pane 2 and is provided, for example, as a heatable coating. The composite pane also includes an antireflection coating 30 applied to the interior side surface IV of the inner pane 2.

The antireflection coating 30 increases the light transmission of the composite disk 10. This makes it possible to accommodate a larger amount of conductive material in the conductive coating 20 without reducing the overall light transmission to an extent such that the composite disk 10 is no longer usable as a windshield would. This achieves a lower surface resistance, which is reflected in a higher heating power for a given supply voltage.

2 shows a projection arrangement according to the invention for a HUD. The projection arrangement comprises, in addition to the composite pane 10 from FIG. 1, a projector 4 which is directed onto a region B of the composite pane 10. In the area B, which is usually referred to as the HUD area, images can be generated by the projector 4 which are perceived by a viewer 5 (vehicle driver) as virtual images on the side of the composite pane 10 facing away from him, when his eyes located within the so-called Eyebox E.

The antireflection coating 30 does not strongly reflect the s-polarized radiation of the projector 4 on the interior-side surface IV of the inner pane 1. The reflections take place primarily on the outside surface I of the outer pane 1 and on the conductive coating 20. The conductive coating 20 is then optimized to reflect relatively strongly polarized s-polarized radiation, so that in total despite the anti-reflection coating 30, a high-intensity HUD image is formed. By the wedge angle a, the two reflections are superimposed or at least approximated to each other, so that the viewer 5 does not perceive a disturbing ghost.

The coatings 20 and 30 according to the invention are not shown in the figure for the sake of clarity.

FIG. 3 shows a plan view of the composite pane 10 from FIG. 1. The top edge O, the bottom edge U and the HUD area B can be seen.

FIG. 4 shows a further embodiment of the composite pane 10 according to the invention. In contrast to the embodiment of FIG. 1, the electrically conductive coating 20 is applied to the interior-side surface II of the outer pane 1. Since the intermediate layer 3 is not arranged between the two main reflection planes (coating 20, surface I), it can not influence the occurrence of a ghost due to these reflections. The intermediate layer is therefore not wedge-like, but designed as a standard film with a constant thickness, which is much cheaper available. However, the two reflection planes are sufficiently small spaced apart, so that the ghost image is offset only slightly compared to the main image and usually not disturbing. 5 shows the layer sequence of a preferred embodiment of the electrically conductive coating 20. The coating 20 contains four electrically conductive layers 21 (FIG. 21.1, FIG.

21.2, 21.3, 21.4). Each electrically conductive layer 21 is in each case arranged between two of a total of five antireflection layers 22 (22.1, 22.2, 22.3, 22.4, 22.5). The

Anti-reflection layers 22.2, 22.3, 22.4, which are arranged between two electrically conductive layers 21, are each subdivided into a dielectric layer 22a (22a.2, 22a.3, 22a.4) with a refractive index of less than 2.1 and a layer with high refractive index 22b (22b.2, 22b.3, 22b.4) with a refractive index greater than or equal to 2.1. The coating 20 also contains three smoothing layers 23 (23.2, 23.3, 23.4), four first matching layers 24 (24.1, 24.2, 24.3, 24.4), four second matching layers 25 (25.2,

25.3, 25.4, 25.5) and four blocking layers 26 (26.1, 26.2, 26.3, 26.4).

The coating 20 is applied by way of example to the inner pane 2, as in the embodiment of FIG. 1. The remaining components of the composite pane 10 are just as little represented as the anti-reflection coating 30 for the sake of simplicity.

6 shows the layer sequence of a preferred embodiment of the antireflection coating 30 applied to the interior-side surface IV of the inner pane 2. The antireflection coating 30 consists of two high-index layers 31 (31.1, 31.2) with a refractive index greater than 1.8, and two low-refraction layers 32 (FIG. 32.1, 32.2) with a refractive index smaller than 1.8. The remaining components of the composite disk 10 are not shown for the sake of simplicity as the conductive coating 30th

Examples

In Example 1, the composite pane 10 is configured as in FIG. 1, with the electrically conductive coating 20 on the outside surface III of the inner pane 2. In Example 2, the composite pane 10 is configured as in FIG. 4, with the electrically conductive coating 20 on the interior side Surface II of the Outer Disk 1. In both Examples 1 and 2, the composite disk 10 has an antireflection coating 30 on the inner side surface IV of the inner disk 2. In Comparative Example 1, the composite disk 10 is configured as in FIG. 1, with the electrically conductive coating 20 on the outside surface III of the inner pane 2. The composite pane, however, has no antireflection coating 30.

The materials and layer thicknesses of the electrically conductive layer 20 for Examples 1 and 2 and Comparative Example 1 are summarized in Table 1. In each case, the material is indicated on the basis of which the layer is formed. In addition, the layers have partial doping: for example, the SnZnO layers are doped with antimony and the ZnO, SiZrN and SiN layers are doped with aluminum. The materials and layer thicknesses of the antireflection coating 30 for Examples 1 and 2 are summarized in Table 2. Again, the SiN layers are doped with aluminum and the SiO layers with aluminum. Table 2 also contains an already used antireflection coating, referred to as Comparative Example 2.

Table 3 summarizes the overall structure of the composite disc 10 of Examples 1 and 2 and Comparative Example 1 together schematically.

Table 1

Table 2

Table 3

7 shows the reflection spectrum of a composite pane 10 (part a) and the electrically conductive coating 20 (part b) according to example 1, example 2 and comparative example 1. The reflection spectra apply to s-polarized radiation at an irradiation angle (angle of incidence) of 65 ° , viewed through the inner pane. Highlighted are the wavelengths 473 nm, 550 nm and 630 nm, which correspond to the RGB diodes of typical HUD projectors.

All composite wafers 10 have a high reflectivity with respect to s-polarized radiation at the RGB wavelengths, which is summarized in Table 4. The efficient reflection of the HUD radiation results in high-intensity HUD imaging. The values for Examples 1 and 2 according to the invention are somewhat lower than those of Comparative Example 1, but are still sufficiently high. The total reflectivity (integrated over the entire visible spectrum from 380 nm to 780 nm) is 27.3% for example 1, 28.4% for example 2 and 33.7% for the comparative example.

Table 4

The difference between the inventive examples and the comparative example becomes clear when comparing the reflection spectra of the isolated coatings 20. The reflectance at the RGB wavelengths is summarized in Table 5. The coating 20 contributes significantly more to the reflection in the examples than in the comparative example. It is therefore capable of compensating for the loss of intensity of HUD imaging due to the antireflection coating 30, which weakens the reflection on the interior surface. Therefore, despite the antireflection coating 30, a high-intensity HUD imaging can be achieved. The total reflectivity is 5.95% for example 1, 5.62% for example 2 and only 2.96% for the comparative example. Table 5

Table 6 summarizes information on the amount of silver and sheet resistance of the electrically conductive coating 20 and on the light transmission and color values of the composite pane 10 of Examples 1 and 2 and Comparative Example 1. Due to the antireflection coating 30, the amount of silver could be increased significantly in the examples according to the invention, while still comparable with Comparative Example 1 light transmission (ECE R 43, Annex 3, § 9.1) is achieved, so that the composite discs are suitable as windscreens. The increased amount of silver results in a reduced sheet resistance, allowing, for example, a higher heat output.

Table 6

Various color values a ^* and b ^* are indicated, each measured under the measurement conditions D65 / 10 ⁰ according to the standard. The degrees in the table refer to the angle of incidence during the measurement. The values at angles of incidence of 8 ° and 60 ° were measured with mixed-polarized radiation and indicate the outside reflection color (irradiation via outer pane). They characterize the color impression of an observer in the external environment. The values at an angle of incidence of 115 ° were measured with s-polarized radiation and indicate the interior reflection color (irradiation via inner pane). They are a measure of the driver's color impression of the HUD projection.

It can be seen from the table that the outside reflection has color values always smaller than 0, whereby the composite pane has a pleasant and accepted by the automotive industry and the consumer reflection color. The color values relevant to the HUD viewer are always less than 1. Under these conditions, a composite disk is realized which has a pleasant reflection color and does not lead to disturbing color shifts in the HUD projection.

LIST OF REFERENCE NUMBERS

(10) composite disk

(1) Outer pane

(2) Inner pane

(3) thermoplastic intermediate layer

(4) projector

(5) viewer / vehicle driver

(20) electrically conductive coating

(21) electrically conductive layer

(21.1), (21.2), (21.3), (21.4) 1 2., 3., 4. electrically conductive layer

(22) Anti-reflection coating

(22.1), (22.2), (22.3), (22.4), (22.5) 1st, 2nd, 3rd, 4th, 5th antireflective coating

(22a) Dielectric layer of the antireflection coating 4

(22a.2), (22a.3), (22a.4) 1st, 2nd, 3rd dielectric layer (22b) optically high-index layer of the antireflection coating 4

(22b.2), (22b.3), (22b.4) 1., 2., 3. optically high refractive index layer

(23) smoothing layer

(23.2), (23.3), (23.4) 1st, 2nd, 3rd smoothing layer

(24) first adaptation layer

(24.1), (24.2), (24.3), (24.4) 1st, 2nd, 3rd, 4th first adaptation layer

(25) second adaptation layer

(25.2), (25.3), (25.4), (25.5) 1st, 2nd, 3rd, 4th second adaptation layer

(26) blocker layer

(26.1), (26.2), (26.3), (26.4) 1st, 2nd, 3rd, 4th blocker layer

(30) Antireflection coating

(31) High-refraction layer of anti-reflection coating 30

(31.1), (31.2) 1st, 2nd high refractive layer

(32) low-refractive-index anti-reflection coating 30

(32.1), (32.2) 1st, 2nd low-refraction layer

(O) top edge of the composite pane 10

(U) lower edge of the composite pane 10

(B) HUD area of the composite disk 10

(E) Eyebox

(I) on the outside, facing away from the intermediate layer 3 surface of the outer pane 1 (II) interior side, facing the intermediate layer 3 surface of the outer pane. 1

(III) outside, facing the intermediate layer 3 surface of the inner pane. 2

(IV) interior side, facing away from the intermediate layer 3 surface of the inner pane 2 a wedge angle

Claims

claims

1. Composite disc (10) at least comprising an outer disc (1) and an inner disc (2), which are interconnected via a thermoplastic intermediate layer (3), and

an electrically conductive coating (20) on the surface (II, III) facing the intermediate layer (3) of the outer pane (1) or the inner pane (2) or within the intermediate layer (3) and

an antireflection coating (30) on the surface (IV) of the inner pane (2) facing away from the intermediate layer (3),

wherein the composite pane (10) has a transmission in the visible spectral range of at least 70% and the electrically conductive coating (20) has a surface resistance of at most 0.65 W / p,

and wherein the electrically conductive coating (20) comprises at least four electrically conductive layers (21) which are each arranged between two dielectric layers or layer sequences, and wherein the total thickness of all the electrically conductive layers (21) is at least 60 nm.

2. Composite disc (10) according to claim 1, which has a reflectance for s-polarized radiation of at least 15% at wavelengths of 473 nm, 550 nm and 630 nm, preferably at least 20%, more preferably at least 25%.

3. The composite disc (10) according to claim 2, wherein the standard deviation of the reflectance at wavelengths of 473 nm, 550 nm and 630 nm is at most 10%, preferably at most 6%.

4. The composite pane (10) according to any one of claims 1 to 3, wherein the electrically conductive coating (20) at wavelengths of 473 nm, 550 nm and 630 nm has a reflectance for s-polarized radiation of at least 15%, preferably at least 20% , more preferably at least 25%.

5. The composite pane (10) according to one of claims 1 to 4, whose a ^* color value and b ^* color value is less than 1, preferably less than 0.

6. The composite pane (10) according to one of claims 1 to 5, wherein the electrically conductive coating (20) on the wall facing the intermediate layer (3) surface (III) of Inner pane (2) is applied, and wherein the thickness of the intermediate layer (3) in the vertical course between the lower edge (U) and the upper edge (O) of the

Composite disc (10) at least in the HUD area (B) is variable with a wedge angle (a).

7. Laminate (10) according to any one of claims 1 to 5, wherein the electrically conductive

Coating (20) is applied on the surface (II) of the outer pane (1) facing the intermediate layer (3), and wherein the thickness of the intermediate layer (3) lies vertically between the lower edge (U) and the upper edge (O) of the

Composite disc (10) is substantially constant.

8. The composite pane according to claim 1, wherein the layer thickness of each electrically conductive layer is from 10 nm to 20 nm, and wherein the total thickness of all electrically conductive layers is preferably from 60 nm to 70 nm is.

9. Laminate (10) according to any one of claims 1 to 8, wherein the

Antireflection coating (30) of alternately arranged layers (31, 32) is formed with different refractive indices.

10. Laminate (10) according to claim 9, wherein the antireflection coating (30) starting from the inner pane (2) comprises the following layers:

a first high refractive index layer (31.1) based on silicon nitride with a thickness of 15 nm to 25 nm,

a first low-refraction layer (32.1) based on silicon dioxide with a thickness of 20 nm to 25 nm,

a second high refractive index layer (31.2) based on silicon nitride with a thickness of 100 nm to 120 nm,

a second low-refraction layer (32.2) based on silicon dioxide with a thickness of 80 nm to 90 nm.

11. Projection arrangement for a head-up display (HUD), at least comprising

- A composite disc (10) according to any one of claims 1 to 10, and

- A projector (4) which is directed to a region (B) of the composite disc (10).

12. Projection arrangement according to claim 1 1, wherein the radiation of the projector (4) is substantially s-polarized.

13. Projection arrangement according to claim 11 or 12, wherein the radiation of the projector (4) with an incident angle of 60 ° to 70 ° on the composite disc (10).

14. Use of a composite pane according to one of claims 1 to 10 in a motor vehicle, preferably a passenger car, truck, bus, ship or aircraft, as a windshield, which serves as a projection surface of a head-up display.