Projection apparatus with p-polarized radiation for head-up display (HUD)

Abstract

A projection device for a head-up display (HUD) comprising at least: a composite glass plate (10) having a conductive coating (20), including an outer glass plate (1) and an inner glass plate (2) connected to each other by a thermoplastic interlayer (3); and a projector (4) aligned with a HUD region (B); wherein: the radiation of the projector (4) is primarily p-polarized; the conductive coating (20) has a first surface region (20.1) within the HUD region (B) and a second surface region (20.2) outside the HUD region (B); the conductive coating (20) within the first surface region (20.1) has at least one sub-region in which the conductive coating (20) is sequentially formed by a first dielectric layer (22) or a layer sequence (22a, 22b, 22c), a silver-based... The first conductive layer (21a) and the second dielectric layer (23) or layer sequence (23a, 23b, 23c) are composed and adapted to reflect p-polarized radiation. The conductive coating (20) in the second surface region (20.2) sequentially includes at least the first dielectric layer (22) or layer sequence (22a, 22b, 22c), the silver-based first conductive layer (21a), the second dielectric layer (23) or layer sequence (23a, 23b, 23c), the silver-based second conductive layer (21b), and the third dielectric layer (24) or layer sequence (24a, 24b, 24c). The conductive coating (20) in the first surface portion (20.1) in the HUD region (B) can be obtained from the conductive coating (20) in the second surface portion (20.2) by means of a subtractive method.

Description

[0001] This invention relates to a projection device for a head-up display and its application.

[0002] Modern cars are increasingly equipped with so-called head-up displays (HUDs). Using a projector, typically in the dashboard area, an image is projected onto the windshield, where it is reflected and perceived by the driver as a virtual image behind the windshield (as seen by the driver). In this way, important information, such as current speed, navigation, or warning prompts, can be projected into the driver's field of vision, allowing the driver to perceive this information without taking their eyes off the road. Therefore, head-up displays can make a significant contribution to improving traffic safety.

[0003] HUD projectors primarily operate using s-polarized radiation and illuminate the windshield at an incident angle of approximately 65%, which is close to the Brewster angle of the air-glass transition (56.5° for soda-lime glass). Here, a problem arises where the projected image is reflected from both outer surfaces of the windshield. This results in a slightly misaligned secondary image, a so-called ghost image ("phantom"), in addition to the desired primary image. This problem is typically mitigated by arranging the surfaces at an angle to each other, particularly by using a wedge-shaped interlayer for laminating the windshield into a composite glass panel, thereby superimposing the primary and ghost images. Composite glass with a wedge-shaped film for HUDs is known, for example, from WO2009 / 071135A1, EP1800855B1, or EP1880243A2.

[0004] Wedge films are expensive, making the manufacture of such HUDs using composite glass panels quite costly. Therefore, there is a need for HUD-projection devices that do not require wedge films and can be applied to windshields. For example, a HUD projector can be operated using p-polarized radiation that is substantially unreflected on the glass surface. Instead, the windshield has a reflective coating as a reflective surface for p-polarized radiation. DE102014220189A1 discloses such a HUD projection device operating with p-polarized radiation. As a reflective structure, a single-layer metal layer with a thickness of 5 nm to 9 nm, such as silver or aluminum, is particularly recommended. WO2019046157A1 also discloses a HUD with p-polarized radiation, wherein a reflective coating having at least two metal layers is used.

[0005] US2017242247A1 discloses another HUD projection device having a reflective coating for p-polarized radiation. This reflective coating may include one or more conductive silver layers, in addition to a dielectric layer. However, the reflectance spectrum has a significantly curved shape in the relevant spectral range, making the reflectivity relatively strongly dependent on wavelength. This is disadvantageous for color-neutral display of the HUD projection.

[0006] CN204143067U describes a HUD projection device consisting of a light source for p-polarized light and a composite glass plate, wherein the composite glass plate has a transparent layer comprising at least two dielectric layers and at least one metal layer.

[0007] There is a need for projection devices for HUDs with reflective coatings that ensure high transmittance in the visible spectrum and high reflectance to p-polarized radiation while allowing for color-neutral display. In addition to these specific requirements in the projection area of ​​the HUD, there is an additional need, particularly outside the HUD area, for the lowest possible infrared transmittance and favorable reflectivity within the visible spectrum for the observer. The object of this invention is to provide such an improved projection device.

[0008] According to the present invention, the object of the invention is achieved by the projection device according to claim 1. Preferred embodiments are known from the dependent claims.

[0009] The projection device for a head-up display (HUD) according to the present invention includes at least a composite glass plate with a conductive coating and a projector that primarily generates p-polarized radiation and is aligned with the HUD area. The composite glass plate includes an outer glass plate and an inner glass plate, which are interconnected by a thermoplastic interlayer. The conductive coating is divided into a first surface region located within the HUD area and a second surface region located outside the HUD area. Within the first surface region, the conductive coating has at least one sub-region in which the conductive coating sequentially comprises a first dielectric layer or layer sequence, a silver-based conductive layer, and a second dielectric layer or layer sequence, and is adapted to reflect p-polarized radiation. Within the second surface region, the conductive coating has at least one sub-region in which the conductive coating sequentially comprises at least a first dielectric layer or layer sequence, a silver-based first conductive layer, a second dielectric layer or layer sequence, a silver-based second conductive layer, and a third dielectric layer or layer sequence. The conductive coating in the first planar portion within the HUD area can be obtained from the conductive coating in the second planar portion by means of a subtractive method.

[0010] According to the present invention, the composite glass panel has a conductive coating comprising at least two silver-based conductive layers in at least one sub-region of the second surface area. This coating with two functional silver layers advantageously suppresses the transmission of infrared radiation through the composite glass panel. This avoids undesirable heating of the vehicle interior space due to excessive sunlight transmission. Furthermore, an improved visual appearance of the composite glass panel can be achieved by means of the conductive coating with at least two functional silver layers. On the surface of the glass panel facing the environment in the mounted state of the composite glass panel, a layer structure with only one functional silver layer may exhibit undesirable strong reflections. This is avoided with the conductive coating present in the second surface area outside the HUD area according to the present invention.

[0011] In the first surface region of the conductive coating disposed within the HUD area of ​​the composite glass panel, at least one sub-region contains a coating comprising only one functional silver-based layer, namely a silver-based conductive layer. This is suitable for reflecting p-polarized radiation. The conductive coating in the first surface region can be obtained from the conductive coating in the second surface region by means of a subtractive method. In the first surface region, the layer stack of the conductive coating thus includes a portion of the surface cross-section of the conductive coating in the second surface region, wherein additional layers beyond the layer stack in the first surface region exist in the second surface region. In this way, a conductive coating specifically optimized for the reflection of p-polarized light can be provided in the HUD region, while a coating satisfying the requirements for large-area application on the composite glass panel exists in the second surface region outside the HUD region, deviating from this. The partial corresponding layer stacks of the conductive coating in the first and second surface regions here facilitate the manufacture of the composite glass panel.

[0012] According to the present invention, the layer stack in the first surface region can be obtained by means of a subtractive method from the layer stack of the conductive coating in the second surface region. The characteristic that the conductive coating in the first surface region can be obtained from the coating in the second surface region relates to the composition and layer sequence of the conductive coating, but is independent of the coating manufacturing process. Therefore, decisively, when observing the layer stack of the conductive coating in the second surface region, a portion of the layer stack can be ignored, thereby generating the layer stack of the conductive coating in the first surface region. Here, it is not important whether a subtractive method is used to obtain the layer stack of the conductive coating in the first surface region, or whether the coatings are applied independently to the two surface regions by means of an additive method.

[0013] According to the present invention, p-polarized radiation is used to generate the HUD image, and the composite glass plate has a conductive coating that sufficiently reflects p-polarized radiation. Because the typical incident angle of approximately 65° for a HUD projection device is relatively close to the Brewster angle (56.5°, soda-lime glass) of the air-glass transition, p-polarized radiation is hardly reflected by the glass surface, but primarily by the conductive coating. Therefore, no ghosting image occurs or is almost imperceptible, thus eliminating the need for expensive wedge-shaped films. Furthermore, the HUD image is also identifiable to wearers of polarization-selective sunglasses, which typically allow only p-polarized radiation to pass through and block s-polarized radiation. The conductive coating in the first surface region has high reflectivity for p-polarized radiation in the spectral range of 450 nm to 650 nm, which is relevant to HUD displays (HUD projectors typically operate at wavelengths of 473 nm, 550 nm, and 630 nm (RGB)). This achieves a high-intensity HUD image. The single-layer silver layer does not excessively reduce light transmittance, so the glass plate can also be used as a windshield. The optical thickness ratio of the upper and lower dielectric layer sequences according to the invention produces a smooth reflectance spectrum, thereby ensuring a color-neutral display. The advantageous reflectance properties, especially the spectral uniformity, extend even beyond the HUD-related spectral range to the 400 nm to 680 nm range, thus achieving a good overall impression of the glass plate in the first surface area without interfering color distortion, in addition to a good HUD display. This is a major advantage of the invention.

[0014] The projection device for a head-up display (HUD) according to the invention comprises at least a composite glass plate with a conductive coating and a projector. As is common in HUDs, the projector illuminates an area of ​​the composite glass plate in which radiation is reflected in the direction of the observer (in the case of the composite glass plate as a windshield of a vehicle: the driver), thereby producing a virtual image that the observer perceives as appearing behind the composite glass plate. The area of ​​the composite glass plate illuminated by the projector is called the HUD area. The beam direction of the projector can typically be changed by a mirror, particularly vertically, to match the projection to the viewer's body size. The area within which the observer's eyes must be located at a given mirror position is called the eye-tracking range window. This eye-tracking range window can be vertically moved by adjusting the mirror, and the entire area thus accessible (i.e., the superposition of all possible eye-tracking range windows) is called the eye-tracking range. An observer within the eye-tracking range can perceive the virtual image. Therefore, it naturally implies that the observer's eyes, rather than, for example, the entire body, must be within the eye-tracking range.

[0015] The technical terms used here in the field of HUD are those commonly known to those skilled in the art. For a detailed explanation, see Alexander Neumann’s paper “Simulationsbasierte Messtechnik zur Prüfung von Head-Up Displays” (Munich: University Library of Technical University of Munich, 2012), especially Chapter 2, “Das Head-Up Display”.

[0016] The composite glass panel comprises an outer glass panel and an inner glass panel, which are connected to each other by a thermoplastic interlayer. The composite glass panel is provided for separating an interior space from the external environment within a window opening of a vehicle. In the context of this invention, the inner glass panel refers to the glass panel of the composite glass panel facing the interior space of the vehicle. The outer glass panel refers to the glass panel facing the external environment. The composite glass panel is preferably a windshield or roof glass of a motor vehicle, particularly a passenger car or truck.

[0017] In its embodiment as a windshield, the composite glass panel has an upper edge and a lower edge, as well as two side edges extending between them. The upper edge is the edge provided for pointing upwards in the mounting position. The lower edge is the edge provided for pointing downwards in the mounting position. The upper edge is often also referred to as the top edge, and the lower edge is referred to as the engine edge.

[0018] The outer glass panel and the inner glass panel each have an outer and an inner space side surface and a surrounding side edge extending therebetween. In the context of this invention, the outer surface refers to a main surface that is provided for facing the external environment in the mounting position. In the context of this invention, the inner space side surface refers to a main surface that is provided for facing the inner space in the mounting position. The inner space side surface of the outer glass panel and the outer surface of the inner glass panel face each other and are connected to each other by a thermoplastic interlayer.

[0019] The projector is aimed at the HUD area of ​​the composite glass panel. The projector's radiation is primarily p-polarized. The reflective coating is suitable for reflecting p-polarized radiation. Thus, a virtual image is generated by the projector's radiation, which the observer can perceive as appearing behind the composite glass panel. Therefore, when the composite glass panel according to the invention is used as a windshield, this virtual image is perceived by the driver of the vehicle as being located on the road.

[0020] The conductive coating comprises a first surface region and a second surface region. The first surface region of the conductive coating is located within the HUD region of the composite glass panel. Therefore, it is the area of ​​the conductive coating that is directed by the p-polarized radiation of the projector. The second surface region of the conductive coating is located outside the HUD region of the composite glass panel. Preferably, the second surface region surrounds the first surface region, wherein the sum of the first and second surface regions results in the area of ​​the composite glass panel covered by the conductive coating. The conductive coating is applied extensively to the composite glass panel, wherein preferably at least a majority, preferably at least 80%, particularly preferably at least 90%, of the transparent area of ​​the composite glass panel is covered by the conductive coating. The transparent area of ​​the composite glass panel is defined herein as the area visible in the opening to which the glass is to be mounted in the installed state of the composite glass panel and not obscured by fastening elements or opaque cover printing. In particular, the circumferential edge region of the composite glass panel, which is arranged adjacent to the circumferential edge of the composite glass panel, preferably has no conductive coating. This avoids the coating from being corroded by moisture entering at the circumferential edge. Furthermore, the uncoated edge region is advantageous in improving the transmission of high-frequency electromagnetic radiation through the composite glass panel. For example, uncoated edge areas can be created by removing the conductive coating. Optionally, further delamination areas can also be provided, such as in the areas of camera windows or sensor windows. The conductive coating in the second surface area is optimized for large-area application on the composite glass plate in terms of its low solar transmittance and attractive optical appearance, while the conductive coating in the first surface area is selected for p-polarized light in terms of its reflectivity, but is only limited to large-area application on the glass plate in terms of its solar transmittance and appearance. Preferably, the first surface area of ​​the conductive coating accounts for a maximum of 30% of the total area of ​​the composite glass plate, particularly preferably a maximum of 20%, and especially a maximum of 10%. The first and second surface areas can each be designed as continuous surfaces, or they can also be composed of different sub-surfaces. In particular, for example, the first surface area can consist of two or more areas arranged independently of each other, each assigned to a projector. In this way, multiple HUD images can be generated on the glass plate in areas optimized for reflection of p-polarized radiation.

[0021] If the first layer is disposed above the second layer, this means, in the sense of the invention, that the first layer is disposed further away from the substrate on which the coating is applied than the second layer. If the first layer is disposed below the second layer, this means, in the sense of the invention, that the second layer is disposed further away from the substrate than the first layer. The first dielectric layer or layer sequence may also be referred to as the lower dielectric layer or layer sequence and is the dielectric layer closest to the substrate among a plurality of dielectric layers. The second dielectric layer or layer sequence is the dielectric layer disposed above the first dielectric layer on the substrate as the next subsequent dielectric layer among a plurality of dielectric layers. A first conductive layer is located between the first dielectric layer or layer sequence and the second dielectric layer or layer sequence.

[0022] If the layer is based on a material, then the layer is mainly composed of that material, in particular, it is essentially composed of that material except for possible impurities or dopants.

[0023] In a preferred embodiment, the conductive coating over the entire first surface region consists sequentially of a first dielectric layer or layer sequence, a silver-based conductive layer, and a second dielectric layer or layer sequence, and is suitable for reflecting p-polarized radiation. Therefore, a substantially uniform coating exists within the HUD region of the composite glass plate, thereby avoiding sub-regions with different layer structures within this HUD region. This results in an advantage in the manufacturing method, as uniform and identical delamination of the first surface region can be achieved much more easily compared to structuring different types of sub-regions. Furthermore, a uniform HUD image is obtained.

[0024] In another preferred embodiment, the conductive coating has a regular or irregular grid of first and second regions within a first surface region. Within the first region, the conductive coating consists sequentially of a first dielectric layer or layer sequence, a silver-based conductive layer, and a second dielectric layer or layer sequence, and is adapted to reflect p-polarized radiation. In the second region, the conductive coating corresponds to the layer stack of the conductive coating in the second surface region. In this way, the region of the coating corresponding to the second surface region in its optical appearance is also preserved within the first surface region. Thus, the first surface region is optically inconspicuously integrated. Preferably, the first and second regions are arranged in the form of a regular grid. The first and second regions can be identical or different in their shaping. Identical first and second regions can be implemented, for example, as a checkerboard pattern or a honeycomb pattern. Preferably, the first region is in the form of a recess in which the conductive coating is implemented, with the second region formed around the recess. Layers of the conductive coating are removed within the recess such that the remaining layer stack within the first region consists of a first dielectric layer or layer sequence, a silver-based conductive layer, and a second dielectric layer. Here, the first region takes the shape of, for example, a grid and is surrounded by a continuous second region. The grid can be, for example, square or hexagonal. Here, a first region with functional silver layers alternates with a second region containing at least two functional silver layers. The total reflectivity of p-polarized radiation in the first surface region is slightly worse in this grid-shaped design compared to a layer system with only one functional silver layer covering the entire surface in the first surface region. The first and / or second regions preferably have edge lengths of 50 μm to 500 μm, where the edge length is determined to be the maximum dimension of the region in one direction. It has been found that a good trade-off between optical appearance and reflectivity is achieved if the dimensions of the first and / or second regions are designed to have edge lengths of 50 μm to 150 μm, for example, 100 μm.

[0025] In a particularly preferred embodiment of the invention, the two embodiments just described are combined such that the regular grid of the first and second regions exists only along such a surrounding edge of the first surface region, where the first and second surface regions are adjacent to each other. A continuous region with only one functional silver layer is located at the surface center of the first surface region, i.e., outside the edge region adjacent to the surrounding edge. Therefore, the desired high reflectivity of p-polarized radiation exists at the surface center of the first surface region, where most of the HUD image is visible. Conversely, in the edge regions of the first surface region, the transition between the coatings in the first and second surface regions is masked, thus making the composite glass panel visually more pleasing.

[0026] The conductive coating advantageously has at least one sub-region in the first surface region, in which the first dielectric layer or layer sequence has a refractive index of at least 1.9 and / or the second dielectric layer or layer sequence has a refractive index of at least 1.9. Preferably, the first dielectric layer or layer sequence and the second dielectric layer or layer sequence each have a refractive index of at least 1.9 throughout the first surface region. Particularly preferably, in the second surface region, the first dielectric layer or layer sequence, the second dielectric layer or layer sequence, the third dielectric layer or layer sequence, and optionally further dielectric layers or layer sequences also each have a refractive index of at least 1.9. Embodiments of the invention using low-refractive-index layers are possible in principle, but silicon oxide layers are particularly considered as low-refractive-index layers with a refractive index of less than 1.9. However, in the case of magnetic field-assisted cathodic deposition, silicon oxide layers have a low deposition rate. However, using high-refractive-index layers with a refractive index of at least 1.9 allows for the rapid and inexpensive fabrication of reflective coatings according to the invention.

[0027] Within the scope of this invention, the refractive index is given in principle based on a wavelength of 550 nm. Optical thickness is the product of 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 each individual layer. For example, the refractive index can be determined using ellipsometrics. Ellipsometrists are commercially available, for example, from Sentech.

[0028] Preferably, the ratio of the optical thickness of the second dielectric layer or layer sequence to the optical thickness of the first dielectric layer or layer sequence is at least 1.7. It has been surprisingly shown that this asymmetry in optical thickness produces a significantly smoother reflection spectrum for p-polarized radiation, resulting in a relatively constant reflectivity across the entire relevant spectral range (400 nm to 680 nm). This ensures a color-neutral display of the HUD projection and achieves an overall impression of color neutrality from the glass panel.

[0029] The preferred ratio of optical thicknesses is calculated as the quotient of the optical thickness (dividend) of the second dielectric layer or layer sequence divided by the optical thickness (divisor) of the first dielectric layer or layer sequence.

[0030] In a preferred embodiment, the ratio of the optical thickness of the second dielectric layer or layer sequence to the optical thickness of the first dielectric layer or layer sequence is at least 1.8, particularly preferably at least 1.9. This yields particularly good results.

[0031] The conductive coating is preferably applied to the surfaces of the two glass panes facing the thermoplastic interlayer, i.e., the inner space side surface of the outer glass pane or the outer surface of the inner glass pane. Alternatively, the conductive coating can be disposed within the thermoplastic interlayer, for example, applied to a carrier film disposed between the two thermoplastic connecting films. The conductive coating is transparent, which in the sense of the invention means that it has an average transmittance of at least 70%, preferably at least 80%, in the visible spectrum range, and thus substantially does not restrict the visibility through the glass panes. In one embodiment of the invention, at least 80% of the glass pane surface is covered with the conductive coating. In particular, the conductive coating is applied to the entire surface of the glass pane, except for the surrounding edge region and optional local areas that serve as communication windows, sensor windows, or camera windows, where electromagnetic radiation should be ensured to pass through the windshield and therefore are not equipped with a conductive coating. The surrounding uncoated edge region, for example, has a width of at most 20 cm. This prevents the conductive coating from direct contact with the surrounding atmosphere, thereby protecting the coating inside the windshield from corrosion and damage.

[0032] Because of the conductive silver layer, the conductive coating according to the invention has IR reflective properties, and therefore it is used as a sun-protective coating, which reduces heating of the vehicle's interior space by reflecting thermal radiation. If the conductive coating is made electrically contacted, allowing current to flow through it and thus heating it, the conductive coating can also be used as a heating coating.

[0033] The composite glass plate with a conductive coating preferably has an average reflectance of at least 10%, particularly preferably at least 15%, to p-polarized radiation in the first surface region within a spectral range of 400 nm to 680 nm. This produces a projected image of sufficiently high intensity. Here, reflectance is measured at an incident angle of 65° to the surface normal on the inner space side, which approximately corresponds to illumination produced by a common projector. The spectral range of 400 nm to 680 nm is plotted to characterize reflective properties, as the observer's visual impression is primarily determined by this spectral range. Furthermore, it covers wavelengths relevant to HUD displays (RGB: 473 nm, 550 nm, 630 nm). High reflectance in the case of a relatively simple layer structure is a major advantage of the present invention. Particularly good results are obtained when the reflectance is at least 15%, preferably at least 20%, across the entire spectral range of 400 nm to 680 nm, so that there is no place in the given spectral range where the reflectance is lower than the given value.

[0034] Reflectivity describes the proportion of total incident radiation that is reflected. It is given as a percentage (based on a 100% incident radiometer) or as a dimensionless number from 0 to 1 (based on normalized incident radiation). Plotted as a function of wavelength, it forms the reflection spectrum. Within the scope of this invention, the description of reflectivity for p-polarized radiation refers to reflectivity measured at an incident angle of 65° to the surface normal on the interior space side. The description of reflectivity or reflection spectrum refers to reflection measurements performed using a light source uniformly illuminated with 100% normalized radiation intensity over the considered spectral range.

[0035] To achieve the most color-neutral display of the projected image, the reflectance spectrum should be as smooth as possible without significant local minima and maxima. In a preferred embodiment, the difference between the maximum reflectance and the average reflectance, and the difference between the minimum reflectance and the average reflectance, should be at most 3%, particularly preferably at most 2%, in the spectral range of 400 nm to 680 nm. Here, even the reflectance of p-polarized radiation measured at an incident angle of 65° to the surface normal on the interior space side is used. The given differences should be understood as absolute deviations in reflectance (given as %), rather than percentage deviations relative to the average. Since the conductive coating according to the invention has exactly one conductive layer in the first surface region, the desired smoothness of the reflectance spectrum can be achieved without problems in the first surface region using the conductive coating according to the invention.

[0036] Alternatively, the standard deviation in the spectral range of 400 nm to 680 nm can be used as a measure of the smoothness of the reflectance spectrum. It is preferably less than 1%, particularly preferably less than 0.9%, and very particularly preferably less than 0.8%.

[0037] The desired reflective properties are achieved, in particular, by selecting the materials and thicknesses of each layer and the structure of the dielectric layer sequence. Therefore, the conductive coating can be appropriately adjusted.

[0038] The conductive coating is a thin film stack, i.e., a sequence of thin, monolayer layers. This thin film stack comprises exactly one silver-based conductive layer in at least one sub-region of a first surface region, preferably throughout the entire first surface region. This silver-based conductive layer imparts basic reflective properties to the coating, as well as IR reflection and conductivity. This silver-based conductive layer can also be simply referred to as a silver layer. The conductive coating comprises exactly one silver layer in this sub-region of the first surface region, i.e., no more than one silver layer, and no other silver layer is disposed above or below the conductive coating. A particular advantage of the invention is that the desired reflective properties can be obtained with a silver layer without a significant reduction in transmittance, as is the case when using multiple conductive layers. However, additional conductive layers may exist that do not significantly contribute to the conductivity of the conductive coating but serve other purposes. This is particularly suitable for metal barrier layers with a geometrical thickness of less than 1 nm, preferably disposed between the silver layer and the dielectric layer sequence.

[0039] The first and second conductive layers are formed based on silver. The conductive layers preferably contain at least 90% by weight silver, particularly preferably at least 99% by weight silver, and very particularly preferably at least 99.9% by weight silver. The silver layer may have dopants, such as palladium, gold, copper, or aluminum. The geometric thickness of the silver layer is preferably at most 15 nm, particularly preferably at most 14 nm, and very particularly preferably at most 13 nm. This enables favorable reflectivity in the IR range without drastically reducing transmittance. The geometric thickness of the silver layer is preferably at least 5 nm, particularly preferably at least 8 nm. Thinner silver layers result in dehumidification of the layer structure. The geometric thickness of the silver layer is particularly preferably from 10 nm to 14 nm or from 11 nm to 13 nm.

[0040] Alternating with the silver layer, the conductive coating preferably comprises a single dielectric layer or sequence of dielectric layers, each with a refractive index of at least 1.9. The dielectric layers can be formed, for example, based on silicon nitride, zinc oxide, tin-zinc oxide, silicon-metal-mixed nitrides such as silicon-zirconium nitride, zirconium oxide, niobium oxide, hafnium oxide, tantalum oxide, tungsten oxide, or silicon carbide. The aforementioned oxides and nitrides can be deposited stoichiometrically, substoichiometrically, or superstoichiometrically. They can have dopants, such as aluminum, zirconium, titanium, or boron.

[0041] The optical thickness of the second dielectric layer or layer sequence is preferably 100 nm to 200 nm, particularly preferably 130 nm to 170 nm. The optical thickness of the first dielectric layer or layer sequence is preferably 50 nm to 100 nm, particularly preferably 60 nm to 90 nm. This achieves good results in terms of a significantly smoother reflection spectrum for p-polarized radiation. The first and second dielectric layers are present in the first surface region, and therefore they are particularly relevant to the reflectivity in the HUD region. The third dielectric layer and optionally additional dielectric layers are disposed in the second surface region outside the HUD region. Therefore, they are not relevant to the performance of the HUD region. Thus, the optical thickness of the third dielectric layer or layer sequence, and any further dielectric layers or layer sequences that may exist, can be selected within a wider range. The optical thickness of the third dielectric layer or layer sequence is preferably 50 nm to 200 nm, particularly preferably 60 nm to 150 nm. The optical thickness of the further dielectric layers or layer sequences can be freely selected within the same range.

[0042] In an advantageous embodiment, a dielectric layer, which may be referred to as an antireflection layer, is disposed above and below the silver layer. This antireflection layer is preferably, in each case, part of a first dielectric layer or layer sequence, a second dielectric layer or layer sequence, and a third dielectric layer or layer sequence. The antireflection layer is preferably based on an oxide, such as tin oxide, and / or a nitride, such as silicon nitride, particularly preferably based on silicon nitride. Silicon nitride has proven advantageous due to its optical properties, its availability, and its high mechanical and chemical stability. Silicon is preferably doped with, for example, aluminum or boron. In the case of dielectric layer sequences, the silicon nitride-based layer is preferably the uppermost layer of the upper (i.e., the second or third) layer sequence or the lowermost layer of the lower (i.e., the first) layer sequence. The geometric thickness of the upper antireflection layer present in the second and / or third dielectric layer or layer sequence is preferably 25 nm to 100 nm, particularly preferably 30 nm to 80 nm, and especially 60 nm to 70 nm. The geometric thickness of the lower antireflection layer present in the first dielectric layer or layer sequence is preferably 10 nm to 50 nm, particularly preferably 15 nm to 40 nm, and especially 20 nm to 35 nm.

[0043] The stacking of the third dielectric layer preferably ends with an anti-reflection layer. Preferably, a second anti-reflection layer is provided as the ending layer in the first surface region. Thus, the second anti-reflection layer forms the layer furthest from the substrate.

[0044] In addition to the anti-reflective layer, an additional dielectric layer with a refractive index of at least 1.9 may optionally be present. Therefore, the layer sequence of dielectric layers can independently include adapter layers that improve the reflectivity of the silver layer. The adapter layer is preferably based on zinc oxide, and particularly preferably zinc oxide (ZnO). 1-δ Formed, of which 0 < δ <0.01. The adapter layer preferably further comprises dopants. The adapter layer may comprise, for example, aluminum-doped zinc oxide (ZnO:Al). To avoid excessive oxygen reacting with the silver-containing layer, zinc oxide is preferably deposited in a substoichiometric manner relative to oxygen. The adapter layer is preferably disposed between the silver layer and the antireflective layer. The geometric thickness of the adapter layer is preferably 5 nm to 30 nm, particularly preferably 8 nm to 12 nm.

[0045] A refractive index-enhancing layer, having a higher refractive index than the antireflective layer, may also be present, also independently of each other in the dielectric layer sequence. This allows for further improvement and fine-tuning of optical properties, particularly reflective properties. The refractive index-enhancing layer preferably comprises a silicon-metal-mixed nitride, such as a silicon-zirconium-mixed nitride, a silicon-aluminum-mixed nitride, a silicon-titanium-mixed nitride, or a silicon-hafnium-mixed nitride, with a particularly preferred silicon-zirconium-mixed nitride. Here, the proportion of zirconium is preferably 15 to 45% by weight, particularly preferably 15 to 30% by weight. Alternative materials such as WO3, Nb2O5, Bi2O3, TiO2, Zr3N4, and / or AlN can be considered. The refractive index-enhancing layer is preferably disposed between the antireflective layer and the silver layer, or between the adapter layer (if present) and the antireflective layer. The geometric thickness of the refractive index-enhancing layer is preferably 5 nm to 30 nm, particularly preferably 5 nm to 15 nm.

[0046] The dielectric layer sequence may also include a smoothing layer. This is preferably disposed below or above the adapter layer adjacent to the silver layer. The smoothing layer is preferably in direct contact with the adapter layer. The smoothing layer serves an optimizing function, particularly smoothing the surface on which a conductive layer is subsequently applied. A conductive layer deposited on a smoother surface has higher transmittance and lower sheet resistance. The smoothing layer comprises at least one amorphous oxide. This oxide may be amorphous or partially amorphous (and therefore partially crystalline), but not fully crystalline. The amorphous smoothing layer has low roughness and thus forms a smooth surface favorable for the layer to be applied above it. The amorphous first smoothing layer further improves the surface structure of the layer directly deposited above the smoothing layer; this is preferably the first adapter layer. The smoothing layer may comprise at least one oxide of one or more of the elements tin, silicon, titanium, zirconium, hafnium, zinc, gallium, and indium. The smoothing layer preferably comprises an amorphous mixed oxide. The smoothing layer particularly preferably comprises a tin-zinc mixed oxide. This mixed oxide may also optionally have dopants. The smoothing layer may, for example, comprise an antimony-doped tin-zinc mixed oxide (SnZnOx:Sb). This mixed oxide preferably has a substoichiometric oxygen content. A method for preparing a tin-zinc mixed oxide layer by reactive cathode sputtering is known, for example, from DE 198 48 751 C1. The deposition of the tin-zinc mixed oxide is carried out by adding oxygen as a reactant gas during cathode sputtering. The thickness of the smoothing layer is preferably from 3 nm to 20 nm, particularly preferably from 4 nm to 12 nm. The refractive index of the smoothing layer is preferably at least 1.9 and less than 2.2.

[0047] In another embodiment of the invention, the first dielectric layer comprises a first antireflective layer and a first adapter layer. Similarly, the second dielectric layer comprises a second antireflective layer and a second adapter layer, and the third dielectric layer comprises a third antireflective layer and a third adapter layer. In a second surface region following the second dielectric layer is a second silver layer, the second dielectric layer preferably comprises two adapter layers, such that one adapter layer is adjacent to both the first and second silver layers. The refractive index of the antireflective layer and the adapter layer is at least 1.9. The antireflective layer is preferably formed based on silicon nitride, and the adapter layer is formed based on zinc oxide. The adapter layers are preferably arranged between their respective antireflective layers and silver layers, creating a layer sequence from the substrate: first antireflective layer - first adapter layer - first silver layer - second adapter layer - second antireflective layer, followed in the second surface region by another second adapter layer - second silver layer - third adapter layer - third antireflective layer. The conductive coating preferably does not contain an additional dielectric layer in the first surface region. In the second surface region, if more than two silver layers are present, additional dielectric layers may be provided. The geometric thickness of the second antireflective layer is preferably 50 nm to 100 nm, particularly preferably 55 nm to 80 nm, and especially 60 nm to 70 nm. The geometric thickness of the first antireflective layer is preferably 10 nm to 50 nm, particularly preferably 15 nm to 40 nm, and especially 20 nm to 35 nm. The geometric thickness of the adapter layer is preferably 5 nm to 30 nm, and especially preferably 8 nm to 12 nm.

[0048] In another embodiment of the invention, the first dielectric layer includes a first antireflective layer, a first adapter layer, and a first refractive index increasing layer. Similarly, the second dielectric layer includes a second antireflective layer, a second adapter layer, and a second refractive index increasing layer, and the third dielectric layer includes a third antireflective layer, a third adapter layer, and a third refractive index increasing layer. In a second surface region of the second silver layer following the second dielectric layer, the second dielectric layer preferably includes two adapter layers, such that one adapter layer is adjacent to both the first and second silver layers. The refractive index of the antireflective layer, the adapter layer, and the refractive index increasing layer is at least 1.9. The refractive index increasing layer has a higher refractive index than the antireflective layer, preferably at least 2.1. The antireflective layer is preferably formed based on silicon nitride, the adapter layer is based on zinc oxide, and the refractive index increasing layer is based on a silicon-metal-mixed nitride, such as a silicon-zirconium-mixed nitride or a silicon-hafnium-mixed nitride. The adapter layer preferably has a minimum distance from the silver layer, while the refractive index increasing layer is disposed between the adapter layer and the antireflective layer. The resulting layer sequence, starting from the substrate, is as follows: first antireflective layer – first refractive index-increasing layer – first adapter layer – first silver layer – second adapter layer – second refractive index-increasing layer – second antireflective layer, followed by another second adapter layer – second silver layer – third adapter layer – third refractive index-increasing layer – third antireflective layer in the second surface region. In the first surface region, the conductive coating preferably does not contain an additional dielectric layer. In the second surface region, if more than two silver layers are present, additional dielectric layers may be provided. The geometric thickness of the upper antireflective layer is preferably 25 nm to 100 nm, particularly preferably 30 nm to 80 nm. The geometric thickness of the lower antireflective layer is preferably 10 nm to 50 nm, particularly preferably 15 nm to 40 nm, especially 20 nm to 35 nm. The geometric thickness of the adapter layer is preferably 5 nm to 30 nm, particularly preferably 8 nm to 12 nm. The geometric thickness of the refractive index-increasing layer is preferably 5 nm to 30 nm, particularly preferably 5 nm to 15 nm.

[0049] In another advantageous embodiment of the invention, the first dielectric layer comprises a first antireflective layer, a first adapter layer, a first refractive index increasing layer, and a first smoothing layer. Similarly, the second dielectric layer comprises a second antireflective layer, a second adapter layer, a second refractive index increasing layer, and a second smoothing layer, and the third dielectric layer comprises a third antireflective layer, a third adapter layer, a third refractive index increasing layer, and optionally a third smoothing layer. A third smoothing layer is particularly present if the conductive coating comprises more than two silver layers. In a second surface region following the second dielectric layer and containing the second silver layer, the second dielectric layer preferably comprises two adapter layers, such that one adapter layer is adjacent to both the first and second silver layers. The refractive index of the antireflective layer, adapter layer, smoothing layer, and refractive index increasing layer is at least 1.9. The refractive index increasing layer has a higher refractive index than the antireflective layer, preferably at least 2.1. The antireflective layer is preferably formed based on silicon nitride, the adapter layer is based on zinc oxide, and the refractive index increasing layer is based on a silicon-metal-mixed nitride, such as a silicon-zirconium-mixed nitride or a silicon-hafnium-mixed nitride. The adapter layer preferably has a minimum distance from the silver layer, while the refractive index increasing layer is disposed between the adapter layer and the antireflective layer. Smoothing layers are preferably disposed below or above each adapter layer adjacent to the silver layer. The smoothing layers are preferably in direct contact with the adapter layers. The smoothing layers particularly preferably contain a tin-zinc mixed oxide. This results in a layer sequence starting from the substrate: first antireflective layer – first refractive index increasing layer – first smoothing layer – first adapter layer – first silver layer – second adapter layer – second smoothing layer – second refractive index increasing layer – second antireflective layer, followed in the second surface region by another second adapter layer – second silver layer – third adapter layer – third refractive index increasing layer – third antireflective layer. The conductive coating preferably does not contain an additional dielectric layer in the first surface region. In the second surface region, if more than two silver layers are present, additional dielectric layers are particularly suitable. In the case of more than two silver layers, a third smoothing layer is preferably also used within the third dielectric layer sequence. The geometric thickness of the upper antireflective layer is preferably 25 nm to 100 nm, particularly preferably 30 nm to 80 nm. The geometric thickness of the lower anti-reflection layer is preferably 10 nm to 50 nm, particularly preferably 15 nm to 40 nm, and especially 20 nm to 35 nm. The geometric thickness of the adaptor layer is preferably 5 nm to 30 nm, particularly preferably 8 nm to 12 nm. The geometric thickness of the refractive index increasing layer is preferably 5 nm to 30 nm, particularly preferably 5 nm to 15 nm. The thickness of the smoothing layer is preferably 3 nm to 20 nm, particularly preferably 4 nm to 12 nm.

[0050] Since all dielectric layer sequences can be formed independently of each other, combinations of the above embodiments are also feasible, wherein a first, second, and / or third dielectric layer / layer sequence is formed according to one embodiment and the remaining dielectric layer / layer sequence is formed according to one or more other embodiments. The following preferred layer sequence is generated in the first surface region of the conductive coating (in each case starting from the substrate, i.e., from the surface on which the conductive coating is deposited):

[0051] - First anti-reflective layer – First silver layer – Upper anti-reflective layer

[0052] - First anti-reflective layer – First silver layer – Second adapter layer – Second anti-reflective layer

[0053] - First anti-reflective layer – First silver layer – Second adapter layer – Second refractive index increasing layer – Second anti-reflective layer

[0054] - First anti-reflective layer – First adapter layer – First silver layer – Second anti-reflective layer

[0055] - First anti-reflective layer – First adapter layer – First silver layer – Second adapter layer – Second anti-reflective layer

[0056] - First anti-reflective layer – First adapter layer – First silver layer – Second adapter layer – Second refractive index increasing layer – Second anti-reflective layer

[0057] - First anti-reflective layer – First refractive index increasing layer – First adapting layer – First silver layer – Second anti-reflective layer

[0058] - First anti-reflective layer – First refractive index increasing layer – First adapter layer – First silver layer – Second adapter layer – Second anti-reflective layer

[0059] - First anti-reflective layer – First refractive index increasing layer – First adapter layer – First silver layer – Second adapter layer – Second refractive index increasing layer – Second anti-reflective layer

[0060] An additional layer, at least one second silver layer and a third dielectric layer, is present in the second surface region. The third dielectric layer itself may also comprise the aforementioned sequence of dielectric layers. A third or further silver layer and a fourth and further sequence of dielectric layers may also be present in the second surface region of the conductive coating.

[0061] In an advantageous embodiment, the conductive coating includes at least one metallic barrier layer. This barrier layer may be disposed below and / or above the silver layer, and preferably in direct contact with the silver layer. The barrier layer is then positioned between the silver layer and the dielectric layer / layer sequence. The barrier layer serves to protect the silver layer from oxidation, particularly when the coated glass plate is subjected to temperature treatments, such as those typically occurring in bending processes. The geometric thickness of the barrier layer is preferably less than 1 nm, for example, 0.1 nm to 0.5 nm. The barrier layer is preferably formed based on titanium or a nickel-chromium alloy.

[0062] The barrier layer negligibly alters the optical properties of the conductive coating and is preferably present in all the embodiments described above. Particularly preferably, one barrier layer is disposed directly above the silver layer, i.e., between the silver layer and the next dielectric layer (sequence), where it is particularly effective. The following preferred layer sequence is generated in the first surface region of the conductive coating (in each case starting from the substrate, i.e., from the surface on which the conductive coating is deposited):

[0063] - First anti-reflective layer – First silver layer – First blocking layer – Second anti-reflective layer

[0064] - First anti-reflective layer – First silver layer – First blocking layer – Second adapter layer – Second anti-reflective layer

[0065] - First anti-reflective layer – First silver layer – First blocking layer – Second adapter layer – Second refractive index increasing layer – Second anti-reflective layer

[0066] - First anti-reflective layer – First adapter layer – First silver layer – First blocking layer – Second anti-reflective layer

[0067] - First anti-reflective layer – First adapter layer – First silver layer – First blocking layer – Second adapter layer – Second anti-reflective layer

[0068] - First anti-reflective layer – First adapter layer – First silver layer – First blocking layer – Second adapter layer – Second refractive index increasing layer – Second anti-reflective layer

[0069] - First anti-reflective layer – First refractive index increasing layer – First adapting layer – First silver layer – First blocking layer – Second anti-reflective layer

[0070] - First anti-reflective layer – First refractive index increasing layer – First adapter layer – First silver layer – First blocking layer – Second adapter layer – Second anti-reflective layer

[0071] - First anti-reflective layer – First refractive index increasing layer – First adapter layer – First silver layer – First barrier layer – Second adapter layer – Second refractive index increasing layer – Second anti-reflective layer

[0072] In each case, the additional barrier layer may optionally be disposed directly below each silver layer, i.e., between the silver layer and the dielectric layer (sequence) located below it.

[0073] A projector is positioned on the inner space side of the composite glass panel and projects onto the composite glass panel above the inner space side surface of the inner glass panel. It is aligned with and projects onto the HUD area to produce a HUD projection. If the composite glass panel is a windshield, the projector is positioned inside the vehicle's interior space. According to the invention, the projector's radiation is primarily p-polarized, i.e., has a p-polarized radiation component greater than 50%. The higher the p-polarized radiation component in the total radiation of the projector, the stronger the desired projected image and the weaker the intensity of undesirable reflections on the surface of the composite glass panel. The p-polarized radiation component of the projector is preferably at least 70%, particularly preferably at least 80%, and especially at least 90%. In a particularly advantageous embodiment, the projector's radiation is essentially purely p-polarized—the p-polarized radiation component is 100% or only slightly deviated. The description of polarization direction here refers to the radiation incident plane on the composite glass panel. p-polarized radiation refers to radiation whose electric field vibrates in the incident plane. s-polarized radiation refers to radiation whose electric field vibrates perpendicular to the incident plane. The incident plane is spanned by the incident vector and the surface normal of the composite glass plate at the geometric center of the irradiation area, forming a vector space.

[0074] The projector's radiation is preferably incident on the composite glass panel at an angle of incidence of 45° to 70°, particularly 60° to 70°. These angles are preferred, especially when the composite glass panel is used as a windshield. In an advantageous embodiment, the angle of incidence deviates from the Brewster's angle by a maximum of 10°. The p-polarized radiation is then reflected only negligibly on the surface of the composite glass panel, thus preventing ghosting. The angle of incidence is the angle between the incident vector of the projector's radiation and the surface normal of the inner space side surface at the geometric center of the HUD area (i.e., the surface normal on the outer surface of the inner space side of the composite glass panel). In the case of soda-lime glass, the Brewster's angle for the air-glass transition is 56.5°, which is commonly seen for window glass. Ideally, the angle of incidence should be as close to this Brewster's angle as possible. However, for example, an angle of incidence of 65°, common for HUD projection devices, can also be used, which is readily achievable in vehicles and deviates only slightly from the Brewster's angle, thus increasing the reflection of p-polarized radiation only negligibly.

[0075] Since the reflection of projector radiation occurs primarily on the conductive coating, rather than on the outer glass surface, it is unnecessary to arrange the outer glass surfaces at an angle to each other to avoid ghosting images. Therefore, the outer surfaces of the composite glass panels are preferably arranged substantially parallel to each other. The thermoplastic interlayer is therefore preferably not wedge-shaped, but rather has a substantially constant thickness, particularly in the vertical direction between the upper and lower edges of the composite glass panel, as with the inner and outer glass panels. Conversely, a wedge-shaped interlayer has a variable, particularly increasing, thickness in the vertical direction between the upper and lower edges of the composite glass panel. The interlayer is typically formed from at least one thermoplastic film. Because standard films are significantly more cost-effective than wedge films, the manufacture of the composite glass panel becomes cheaper.

[0076] The outer and inner glass panes are preferably made of glass, particularly soda-lime glass, which is common for window glass. However, in principle, the glass panes can also be made of other types of glass (e.g., borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (e.g., polymethyl methacrylate or polycarbonate). The thickness of the outer and inner glass panes can vary widely. Glass panes with a thickness of 0.8 mm to 5 mm are preferred, more preferably 1.4 mm to 2.5 mm, such as those with standard thicknesses of 1.6 mm or 2.1 mm.

[0077] The outer glass pane, inner glass pane, and thermoplastic interlayer can be transparent and colorless, but can also be tinted or colored. In a preferred embodiment, the total transmittance (including the reflective coating) through the composite glass pane is greater than 70%. Therefore, this composite glass pane is suitable as a windshield for motor vehicles. The term total transmittance refers to the test method for the light transmittance of a motor vehicle glass pane as specified in ECE-R 43, Annex 3, §9.1. The outer and inner glass panes can be independently unstressed, partially prestressed, or prestressed. If at least one of the glass panes is required to be prestressed, this can be thermal or chemical prestressing.

[0078] In an advantageous embodiment, the outer glass pane is tinted or colored. This reduces the outer reflectivity of the composite glass pane (especially in the first surface area), thus making the impression of the glass pane more pleasing to the external viewer. However, to ensure the windshield's specified 70% light transmittance (total transmittance), the light transmittance of the outer glass pane should preferably be at least 80%, particularly preferably at least 85%. The inner glass pane and the interlayer are preferably transparent, i.e., untinted or uncolored. For example, green or blue tinted glass can be used as the outer glass pane.

[0079] The composite glass panel is preferably a windshield, which is particularly preferably curved in one or more directions in space, as is common for motor vehicle glass panels, where the typical radius of curvature is about 10 cm to about 40 m. However, the windshield can also be flat, for example, when intended as a glass panel for a bus, train, or tractor.

[0080] The thermoplastic interlayer comprises at least one thermoplastic polymer, preferably ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU), or mixtures, copolymers, or derivatives thereof, with PVB being particularly preferred. The thermoplastic interlayer may comprise one or more thermoplastic films. The thickness of the interlayer is preferably from 0.2 mm to 2 mm, particularly preferably from 0.3 mm to 1 mm, for example, 0.76 mm.

[0081] The present invention further includes a method for manufacturing a projection device according to the invention. Here, an outer glass plate having an outer surface and an inner surface, or an inner glass plate having an outer surface and an inner surface, is first provided. A conductive coating is optionally deposited on the inner surface of the inner or outer glass plate. The conductive coating here comprises at least a first dielectric layer or layer sequence, a silver-based first conductive layer, a second dielectric layer or layer sequence, a silver-based second conductive layer, and a third dielectric layer or layer sequence. In a first surface region, a portion of the conductive coating layer stack is removed, thereby thereafter, in at least one sub-region of the first surface region, the conductive coating consists sequentially of a first dielectric layer or layer sequence, a silver-based first conductive layer, and a second dielectric layer or layer sequence. No additional conductive layer is present in this sub-region of the first surface region. The outer or inner glass plate, coated with the conductive coating and having a correspondingly reduced coating layer stack in the first surface region, is then bonded to the inner or outer glass plate to form a composite glass plate. For this purpose, a thermoplastic interlayer is placed on the inner surface of the inner glass plate or the inner surface of the outer glass plate. Here, one of the inner surfaces already has a conductive coating, and therefore points towards the thermoplastic interlayer. The stack formed by the glass plate and the thermoplastic interlayer ends with an inner or outer glass plate, and the resulting stack of layers consisting of the inner glass plate, the thermoplastic interlayer, and the outer glass plate is laminated into a composite glass plate. For manufacturing a projection device, a projector is provided whose radiation is primarily p-polarized. The projector is aligned such that when the projector is in operation, its p-polarized radiation illuminates the first surface region of the conductive coating.

[0082] The composite glass plate can be manufactured by methods known per se. The outer and inner glass plates are laminated together by an intermediate layer, for example by autoclave methods, vacuum bag methods, vacuum ring methods, calendering methods, vacuum laminators, or combinations thereof. The bonding of the outer and inner glass plates is typically carried out under the influence of heat, vacuum, and / or pressure.

[0083] The conductive coating is preferably applied to the glass surface by physical vapor deposition (PVD), particularly preferably by cathodic sputtering (“sputtering”), and very particularly preferably by magnetic field-assisted cathodic sputtering (“magnetron sputtering”). This coating is preferably applied prior to lamination. Alternatively, in principle, the coating can also be provided on a carrier film disposed in an intermediate layer, instead of being applied to the glass surface.

[0084] Removal of the conductive coating layer in the first surface region is preferably performed by means of a laser method, particularly laser ablation. For this purpose, the laser is focused on one of the layers of the conductive coating to be removed, and is preferably guided on the coating by means of a scanning device. Here, the laser beam is absorbed by the stacked layers, such as a silver-based layer or a barrier layer. The involved layer and the layers above it are removed by peeling, while the layers below are retained. In this way, the layer of the conductive coating to be removed is removed. The substrate and the laser beam move relative to each other, wherein the laser beam and / or the workpiece can optionally be moved. A suitable laser scanner is commercially available and can be used to selectively guide the laser beam onto a stationary or equally movable workpiece. A pulsed solid-state laser is preferably used as the laser. It has proven advantageous to select a laser radiation wavelength of 150 nm to 1200 nm, preferably 300 nm to 1200 nm, and particularly preferably 400 nm to 1100 nm. This region is particularly suitable for processing conductive coatings. A solid-state laser is preferred, particularly an IR laser, such as one with a wavelength of 1064 nm or higher harmonics, for example, 532 nm. The laser operates in a pulsed manner. This is particularly advantageous for high power density and efficient coating removal. The pulse energy is, for example, 10 μJ to 50 μJ per pulse. The pulse repetition rate is preferably 10,000 to 400,000 Hz, for example, 25,000 Hz. The scan speed is preferably selected to be from 0.01 m / s to 5 m / s. The pulse duration of the laser is preferably less than or equal to 20 ns, particularly less than or equal to 10 ps, ​​and especially less than or equal to 400 fs.

[0085] Partial removal of the conductive coating layer stack is preferably performed after all layers of the conductive coating have been applied. Alternatively, the layers can be removed during the deposition process. For this purpose, an abrasion step is inserted between the various deposition steps, in which one or more layers are removed again in the first surface area. For example, a conductive coating comprising one, two, or three silver-based conductive layers and corresponding dielectric layers is first deposited over a large area on the glass plate surface. Then, the conductive coating that was just applied is completely removed in the HUD area of ​​the glass plate. Finally, a layer stack comprising exactly one silver-based conductive layer and the desired dielectric layer is again deposited over a large area on the glass plate surface. This results in a conductive coating in the first surface area consisting of a first dielectric layer or layer sequence, exactly one conductive layer, and a second dielectric layer or layer sequence. Conversely, a conductive coating comprising two, three, or four conductive layers exists in the second surface area. The abrasion step mentioned can be, for example, an ion beam-based etching step or laser ablation. Coating is preferably performed by means of magnetic field-assisted cathode sputtering. Delamination can optionally be performed outside the coating apparatus or in a separate section within the coating apparatus.

[0086] If the conductive coating is provided as a heatable coating, it is electrically contactable. For this purpose, busbars are applied to the coating, enabling it to be electrically connected to a voltage source via electrical connection elements and cables. The busbars used for electrical contact with the coating, their arrangement on the conductive coating, and the methods of applying the busbars are well known to those skilled in the art. The busbars are preferably implemented in the form of printed and burned-in conductive structures. Printed busbars contain at least one metal, preferably silver. Suitable silver printing pastes are commercially available and known to those skilled in the art.

[0087] If the composite glass sheet is to be curved, the outer and inner glass sheets are preferably subjected to a bending process before lamination and preferably after the coating process. Preferably, the outer and inner glass sheets are bent together (i.e., simultaneously and using the same tool) in a consistent manner, as this ensures that the shapes of the glass sheets optimally match each other for the subsequent lamination. Typical temperatures for the glass bending process are, for example, 500°C to 700°C. This temperature treatment also increases transparency and reduces the surface resistivity of the conductive coating.

[0088] The product features described in the process of describing the method also apply to the projection device and the composite glass plate, and conversely, the features mentioned in the description of the projection device and the composite glass plate also apply to the method.

[0089] The present invention also includes the use of the projection device formed according to the invention for a head-up display (HUD) in a motor vehicle, wherein the composite glass panel is the windshield of the motor vehicle and the projector is aimed at the HUD area, and its radiation is primarily p-polarized. The above-described preferred embodiments are accordingly applicable to this use.

[0090] The invention will now be explained in more detail with reference to the accompanying drawings and embodiments. The drawings are schematic and not to scale. The drawings are not intended to limit the invention in any way.

[0091] in:

[0092] Figure 1 A plan view of the composite glass plate of a universal projection device is shown.

[0093] Figure 2 A cross-section through a universal projection device is shown.

[0094] Figure 3 A cross-section of a composite glass plate projected by the projection device according to the invention is shown.

[0095] Figure 4a The layer sequence of the conductive coating 20 within the first surface region 20.1 according to one embodiment of the invention is shown.

[0096] Figure 4b The layer sequence of the conductive coating 20 within the second surface region 20.2 according to one embodiment of the invention is shown.

[0097] Figure 5a A composite glass plate 10 according to the invention, having a first region 26a and a second region 26b within a first surface region 20.1 in the enlarged portion Z, is shown.

[0098] Figure 5b Another composite glass plate 10 according to the invention, having a first region 26a and a second region 26b within a first surface region 20.1 in the enlarged portion Z, is shown.

[0099] Figure 6a The transmission spectrum of the composite glass plate 10 in the second surface region 20.2 is shown according to Table 1.

[0100] Figure 6b The transmission spectrum of the composite glass plate 10 in the first surface region 20.1 is shown according to Table 1.

[0101] Figure 7a The reflection spectrum of p-polarized radiation in the second surface region 20.2 of the composite glass plate 10 according to Table 1 is shown, and

[0102] Figure 7b The reflection spectrum of p-polarized radiation in the first surface region 20.1 of the composite glass plate 10 according to Table 1 is shown.

[0103] Figure 1 and Figure 2Details of a general projection device for a HUD are shown. The projection device includes a composite glass panel 10, which serves as a windshield, particularly for passenger vehicles. The device also includes a projector 4, which is aimed at an area of ​​the composite glass panel 10. In this area, commonly referred to as the HUD area B, an image can be generated by the projector 4, which is perceived by the viewer 5 (driver) as a virtual image on the side of the composite glass panel 10 furthest from him when the viewer's eyes are within the so-called eye-tracking range E.

[0104] The composite glass panel 10 is constructed from an outer glass panel 1 and an inner glass panel 2, which are connected to each other by a thermoplastic interlayer 3. Its lower edge U is arranged downwards towards the engine of the passenger vehicle, and its upper edge O is arranged upwards towards the roof. In the installation position, the outer glass panel 1 faces the external environment, and the inner glass panel 2 faces the interior space of the vehicle. The composite glass panel 10 includes a conductive coating 20, which includes a first surface region 20.1 within the HUD region B and a second surface region 20.2 outside the HUD region B.

[0105] Figure 3 An embodiment of a composite glass panel 10 as a motor vehicle windshield, formed according to the present invention, is shown. The outer glass panel 1 has an outer surface I facing the external environment in the installed position and an inner space side surface II facing the interior space in the installed position. Similarly, the inner glass panel 2 has an outer surface III facing the external environment in the installed position and an inner space side surface IV facing the interior space in the installed position. The outer glass panel 1 and the inner glass panel 2 are, for example, made of soda-lime glass. The thickness of the outer glass panel 1 is, for example, 2.1 mm, and the thickness of the inner glass panel 2 is, for example, 1.6 mm or 2.1 mm. The intermediate layer 3 is, for example, formed of a PVB film with a thickness of 0.76 mm. This PVB film has a substantially constant thickness and, apart from the surface roughness commonly found in the art, it is not formed as a so-called wedge film.

[0106] The outer surface III of the inner glass plate 2 has a conductive coating 20 according to the invention, the conductive coating 20 being in accordance with... Figure 1 The first surface region 20.1 is provided as a reflective surface for projector radiation and additionally, according to Figure 1 The second surface region 20.2 is used as an IR reflective coating.

[0107] According to the invention, the radiation from the projector 4 is p-polarized, and particularly essentially purely p-polarized. Since the projector 4 illuminates the composite glass panel 10, which serves as a windshield, at an incident angle of approximately 65°, close to Brewster's angle, the radiation from the projector is only negligibly reflected on the outer surfaces I and IV of the composite glass panel 10. Conversely, the conductive coating 20 according to the invention is optimized for the reflection of p-polarized radiation within the first surface region 20.1. It serves as a reflective surface for the radiation from the projector 4, used to generate the HUD projection.

[0108] Figure 4a A layer sequence of one embodiment of a conductive coating 20 within a first surface region 20.1 is shown. The coating 20 is a stack of thin layers and includes exactly one silver-based conductive layer 21a. There are no additional conductive layers in the first surface region 20.1 of the coating 20. A metal barrier layer 25 is disposed directly above the first conductive layer 21a. A second dielectric layer sequence 23 is disposed thereon, consisting from bottom to top of a second adapter layer 23b, a second refractive index increasing layer 23c, and a second anti-reflection layer 23a. Below the first conductive layer 21a, a first dielectric layer sequence 22 is disposed, consisting from top to bottom of a first adapter layer 22b, a first refractive index increasing layer 22c, and a first anti-reflection layer 22a.

[0109] The layer structure shown is provided as an example only. Therefore, the dielectric layer sequence may also include more or fewer layers, as long as at least one dielectric layer exists above and below the first conductive layer 21a. The dielectric layer sequence also need not be symmetrical. Exemplary materials and layer thicknesses can be learned from the embodiments below.

[0110] Figure 4b A layer sequence of one embodiment of the conductive coating 20 within the second surface region 20.2 is shown. The coating 20 is a stack of thin layers and includes a first dielectric layer sequence 22, which, from bottom to top, originates from the substrate (here, the inner glass plate 2) and proceeds upwards from a first anti-reflection layer 22a, a first refractive index increasing layer 22c, and a first adapter layer 22b. Following this dielectric layer sequence 22 is a first silver-based conductive layer 21a. A metal barrier layer 25 is disposed directly above the first conductive layer 21a. A second dielectric layer sequence 23 is disposed thereon, which, from bottom to top, includes a second adapter layer 23b, a second refractive index increasing layer 23c, and a second anti-reflection layer 23a. For example, the layer structure of the conductive coating 20 in the second surface region 20.2 corresponds to… Figure 4a The layer structure in the first surface region 20.1 described in [the text]. According to [the text]... Figure 4bIn the second surface region 20.2, another second adapter layer 23b is disposed on the second antireflective layer 23a, so that the second dielectric layer sequence 23 in the second surface region 20.2 consists from bottom to top of the second adapter layer 23b, the second refractive index increasing layer 23c, the second antireflective layer 23a, and another second adapter layer 23b. Following the other second adapter layer 23b is a silver-based second conductive layer 21b having a barrier layer 25. Above the second conductive layer 21b, the layer stack of this coating ends with a third dielectric layer 24. The third dielectric layer 24 consists sequentially from bottom to top of the third adapter layer 24b and the third antireflective layer 24a that ends the layer stack.

[0111] First surface region 20.1 (according to) Figure 4a The conductive coating 20 in the structure is applied over a large area on the inner surface of the inner glass plate 2 by means of magnetron sputtering. Figure 4b The layer structure is then generated in the first surface region 4.1 by means of laser ablation to remove the third dielectric layer 24, the second conductive layer 21b having the associated barrier layer 25, and another second adapter layer 23b located below the second conductive layer 21b.

[0112] The layer structures shown are provided illustratively only. The dielectric layer sequence can therefore include more or fewer layers, provided that at least one dielectric layer is present above and below the first conductive layer 21a in each case. The dielectric layer sequence also need not be symmetrical. Exemplary materials and layer thicknesses can be learned from the following embodiments.

[0113] Table 1 shows the respective layer sequences of the composite glass plate 10 having a conductive coating 20 on the inner surface III of the inner glass plate 2 within the first surface region 20.1 and the second surface region 20.2 according to the present invention, as well as the material and geometry of each layer and the layer thickness. The dielectric layers can be doped independently of each other, for example with boron or aluminum.

[0114]

[0115] Table 2 presents the transmittance, reflectance, and color values ​​of the composite glass plate 10 in the first region 20.1 and the second region 20.2 of the conductive coating 20, from Table 1. TLA This represents the transmittance within the visible range of the spectrum. RL (A) This represents the reflectance within the visible spectrum, measured at an angle of 8° on the outer surface I of the outer glass plate 1. Furthermore, the total solar transmittance is measured according to DIN ISO 13831 and is referred to as... TTS The reflectivity of p-polarized light, which is crucial to image quality, is used... RL(A) p-polThis is indicated and determined at 65° on the outer surface IV of the inner glass plate 2. The corresponding color values ​​are used to determine this. a*p-pol and b*p-pol It can be determined whether there is a favorable neutral color impression in the HUD image.

[0116]

[0117] Comparison of the performance of the conductive coating 20 in the first surface region 20.1 and the second surface region 20.2 shows that a high transmittance of greater than 70% in the visible spectrum, suitable for use as a windshield, can be achieved in both regions. In the second surface region 20.2, a favorable low reflectance RL(A) exists on the outer surface I of the outer glass plate 1, thus the conductive coating in the second surface region 20.2 is well-suited for large-area application on the glass plate. Furthermore, a favorable low total daylight transmittance can be observed in the second surface region 20.2. In the second surface region 20.2, the composite glass plate 10 has a relatively low p-polarized light reflectance and displays a color HUD image. The first surface region 20.1 of the coating 20 is optimized for use in the HUD region of the glass plate. In this region, a favorable high p-polarized light reflectance can be observed, and a HUD image with a neutral color impression is obtained.

[0118] Figure 5a It is shown in accordance with Figure 1 An enlarged view shows one embodiment of the composite glass plate 10 of the projection device according to the invention within portion Z. This composite glass plate 10 substantially corresponds to... Figure 3 As described in [the text]. The difference lies in that the first surface region 20.1 has a first region 26a and a second region 26b. The first region 26a has a layer sequence of conductive coating 20, which corresponds to [the text is incomplete and requires further context to translate accurately]. Figure 4a As described in [the text]. The second region 26b generates a region surrounding the first region 26a and has [the following characteristics]. Figure 4b The conductive coating described herein is a continuous surface of stacked layers. The first region 26b is arranged in the form of a square grid.

[0119] Figure 5b Another embodiment of the composite glass plate 10 of the projection device according to the present invention is shown, also according to... Figure 1 The magnified portion Z is shown. Figure 5b The composite glass plate basically corresponds to Figure 5a The composite glass panel differs in that the first region 26a is arranged in the form of a hexagonal grid.

[0120] Figure 6a The transmission spectrum of the composite glass plate 10 with conductive coating 20 in the second surface region 20.2 is shown according to Table 1, while Figure 6b The transmission spectrum of the composite glass plate 10 in the first surface region 20.1 is shown. Figure 7a The table shows the reflection spectrum of the composite glass plate 10 in the second surface region 20.2 according to Table 1, while... Figure 7b The corresponding reflection spectrum in the first surface region 20.1 is shown. Using a light source emitting p-polarized radiation of uniform intensity within the observed spectral range, the reflection spectrum was recorded above the inner glass plate 2 (reflected from the so-called internal space side) at an incident angle of 65° relative to the surface normal of the internal space side. Therefore, this reflection measurement approximates the case in a projection device. As can be seen from the graphical representation of the spectrum, a much smoother spectrum is achieved in the relevant spectral range of 400 nm to 680 nm in the first surface region 20.1, optimized for the HUD area according to the present invention. This ensures a more color-neutral display of the HUD projection.

[0121] List of reference numerals in the attached diagram:

[0122] 10 Composite Glass Panel

[0123] 1. Outer glass panel

[0124] 2. Inner glass plate

[0125] 3. Thermoplastic interlayer

[0126] 4. Projector

[0127] 5. Observer / Vehicle Driver

[0128] 20 Conductive coating

[0129] 20.1 First surface area of ​​the conductive coating

[0130] 20.2 Second surface region of the conductive coating

[0131] 21a First conductive layer

[0132] 21b Second conductive layer

[0133] 22 First dielectric layer

[0134] 22a Eliminate reflective layer

[0135] 22b adapter layer

[0136] 22c refractive index enhancement layer

[0137] 23 Second dielectric layer

[0138] 23a Second anti-reflective layer

[0139] 23b Second Adaptor Layer

[0140] 23c Second Refractive Index Increased Layer

[0141] 24 Third dielectric layer

[0142] 24a Third anti-reflective layer

[0143] 24b Third Adaptor Layer

[0144] 25 Metal Barrier Layer

[0145] The first region of grid 26a

[0146] The second region of the 26b grid

[0147] O Composite glass plate 10 upper edge

[0148] The lower edge of the U-shaped composite glass plate 10

[0149] B. HUD area of ​​composite glass panel 10

[0150] E Eye movement range

[0151] Part Z

[0152] I. The outer surface of the outer glass plate 1 away from the intermediate layer 3

[0153] II. The inner space side surface of the outer glass panel 1 facing the intermediate layer 3

[0154] III. The outer surface of the inner glass plate 2 facing the intermediate layer 3

[0155] IV. The inner space side surface of the inner glass plate 2 away from the intermediate layer 3.

Claims

1. A projection device for a head-up display (HUD), comprising at least: - A composite glass plate (10) having a conductive coating (20), comprising an outer glass plate (1) and an inner glass plate (2) connected to each other by a thermoplastic interlayer (3), and - Projector (4), which is aligned with the HUD area (B); in - The radiation from the projector (4) has a p-polarized radiation component greater than 50%. - The conductive coating (20) has a first surface region (20.1) within the HUD region (B) and a second surface region (20.2) outside the HUD region (B). - The conductive coating (20) within the first surface region (20.1) has at least one sub-region in which the conductive coating (20) is sequentially composed of a first dielectric layer (22) or layer sequence (22a, 22b, 22c), a silver-based first conductive layer (21a), and a second dielectric layer (23) or layer sequence (23a, 23b, 23c) and is adapted to reflect p-polarized radiation. - The conductive coating (20) within the second surface region (20.2) sequentially comprises at least a first dielectric layer (22) or layer sequence (22a, 22b, 22c), a silver-based first conductive layer (21a), a second dielectric layer (23) or layer sequence (23a, 23b, 23c), a silver-based second conductive layer (21b), and a third dielectric layer (24) or layer sequence (24a, 24b, 24c). Furthermore, the conductive coating (20) in the first surface portion (20.1) within the HUD region (B) can be obtained from the conductive coating (20) in the second surface portion (20.2) by means of a subtractive method.

2. The projection device according to claim 1, wherein the conductive coating (20) in the entire first surface region (20.1) is composed of a first dielectric layer (22) or layer sequence (22a, 22b, 22c), a silver-based first conductive layer (21a), and a second dielectric layer (23a) or layer sequence (23a, 23b, 23c) and is adapted to reflect p-polarized radiation.

3. The projection device according to claim 1, wherein the conductive coating (20) in the first surface region (20.1) has a regular or irregular grid of a first region (26a) and a second region (26b), wherein the conductive coating (20) in the first region (26a) is composed of a first dielectric layer (22) or a layer sequence (22a, 22b, 22c), a silver-based first conductive layer (21a) and a second dielectric layer (23) or a layer sequence (23a, 23b, 23c) and is adapted to reflect p-polarized radiation, wherein the conductive coating (20) in the second region (26b) corresponds to the coating (20) in the second surface region (20.2).

4. The projection device according to any one of claims 1 to 3, wherein the conductive coating (20) in the first surface region (20.1) has at least one sub-region in which the first dielectric layer (22) or layer sequence (22a, 22b, 22c) has a refractive index of at least 1.9 and / or the second dielectric layer (23) or layer sequence (23a, 23b, 23c) has a refractive index of at least 1.

9.

5. The projection device according to any one of claims 1 to 3, wherein the conductive coating (20) in the first surface region (20.1) has at least one sub-region in which the optical thickness of the second dielectric layer (23) or layer sequence (23a, 23b, 23c) to the optical thickness of the first dielectric layer (22) or layer sequence (22a, 22b, 22c) is at least 1.

7.

6. The projection device according to claim 5, wherein the conductive coating (20) in the first surface region (20.1) has at least one sub-region in which the optical thickness of the second dielectric layer (23) or layer sequence (23a, 23b, 23c) to the optical thickness of the first dielectric layer (22) or layer sequence (22a, 22b, 22c) is at least 1.

9.

7. The projection device according to any one of claims 1 to 3, wherein the composite glass plate (10) having a conductive coating (20) in the HUD area (B) has an average reflectivity of at least 10% for p-polarized radiation in the spectral range of 400 nm to 680 nm.

8. The projection device according to any one of claims 1 to 3, wherein the conductive coating (20) does not include a dielectric layer having a refractive index of less than 1.

9.

9. The projection device according to any one of claims 1 to 3, wherein - A first dielectric layer sequence (22a, 22b) is disposed below the first conductive layer (21a), the first dielectric layer sequence (22a, 22b) comprising a first anti-reflection layer (22a) and a first adapter layer (22b), and the first dielectric layer sequence (22a, 22b) having a refractive index of at least 1.9, and / or - A second dielectric layer sequence (23a, 23b) is disposed above the first conductive layer (21a), the second dielectric layer sequence (23a, 23b) including a second anti-reflection layer (23a) and a second adapter layer (23b), and the second dielectric layer sequence (23a, 23b) has a refractive index of at least 1.

9.

10. The projection device according to claim 9, wherein the first anti-reflection layer (22a) is based on silicon nitride, the first adapter layer (22b) is based on zinc oxide, the second anti-reflection layer (23a) is based on silicon nitride, and the second adapter layer (23b) is based on zinc oxide.

11. The projection device according to any one of claims 1 to 3, wherein - A first dielectric layer sequence (22a, 22b, 22c) is disposed below the first conductive layer (21a), the first dielectric layer sequence (22a, 22b, 22c) comprising a first anti-reflection layer (22a), a first adapter layer (22b), and a first refractive index increasing layer (22c), and the first dielectric layer sequence (22a, 22b, 22c) has a refractive index of at least 1.9, and / or - A second dielectric layer sequence (23a, 23b, 23c) is disposed above the first conductive layer (21a). The second dielectric layer sequence (23a, 23b, 23c) includes a second anti-reflection layer (23a), a second adapter layer (23b), and a second refractive index increasing layer (23c). The second dielectric layer sequence (23a, 23b, 23c) has a refractive index of at least 1.

9.

12. The projection device according to claim 11, wherein the first anti-reflection layer (22a) is based on silicon nitride, the first adapter layer (22b) is based on zinc oxide, the first refractive index increasing layer (22c) is based on silicon-metal-mixed nitride, the second anti-reflection layer (23a) is based on silicon nitride, the second adapter layer (23b) is based on zinc oxide, and the second refractive index increasing layer (23c) is based on silicon-metal-mixed nitride.

13. The projection device according to claim 12, wherein the first refractive index increasing layer (22c) is based on silicon-zirconium-mixed nitride, and the second refractive index increasing layer (23c) is based on silicon-zirconium-mixed nitride.

14. The projection device according to any one of claims 1 to 3, wherein the conductive coating (20) comprises at least one metal barrier layer (25) disposed above and / or below the conductive layers (21a, 21b) and having a geometric thickness of less than 1 nm.

15. The projection device according to any one of claims 1 to 3, wherein the outer surfaces (I, IV) of the composite glass plate (10) are arranged parallel to each other.

16. The projection device according to any one of claims 1 to 3, wherein the conductive coating (20) is disposed on or within the surface (II, III) of the outer glass plate (1) or the inner glass plate (2) facing the thermoplastic intermediate layer (3).

17. A method for manufacturing a projection device according to any one of claims 1 to 16, wherein at least a) Provide an outer glass plate (1) having an outer surface (I) and an inner surface (II) or an inner glass plate (2) having an inner surface (III) and an outer surface (IV), b) Deposit a conductive coating (20) on the inner surface (II) of the outer glass plate (1) or the inner surface (III) of the inner glass plate (2), wherein the conductive coating (20) comprises at least a first dielectric layer (22) or a layer sequence (22a, 22b, 22c), a silver-based first conductive layer (21a), a second dielectric layer (23) or a layer sequence (23a, 23b, 23c), a silver-based second conductive layer (21b), and a third dielectric layer (24) or a layer sequence (24a, 24b, 24c). c) Removing the conductive coating (20) layer within the first surface region (20.1), wherein after removal, the conductive coating (20) in at least one sub-region of the first surface region (20.1) consists sequentially of a first dielectric layer (22a) or layer sequence (22a, 22b, 22c), a silver-based first conductive layer (21a), and a second dielectric layer (23) or layer sequence (23a, 23b, 23c). d) Place the thermoplastic interlayer (3) on the inner surface (II) of the outer glass plate (1) or the inner surface (III) of the inner glass plate (2), and finish the layer stacking with the inner glass plate (2) or the outer glass plate (1). e) The layers consisting of at least an inner glass plate (2), a thermoplastic intermediate layer (3), and an outer glass plate (1) are stacked and laminated to form a composite glass plate (10). f) Provide a projector (4) whose radiation has a p-polarized radiation component greater than 50%, and g) Align the projector (4) in such a way that its radiation can irradiate the first surface region (20.1) on the conductive coating (20) of the composite glass plate (10).

18. The method according to claim 17, wherein in step c), the conductive coating (20) is removed by means of a laser method.

19. The method according to claim 18, wherein in step c), the conductive coating (20) is removed by means of laser ablation.

20. Use of the projection device according to any one of claims 1 to 16 for a head-up display for a motor vehicle, wherein the composite glass panel (10) is the windshield of the motor vehicle.

Images