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

Abstract

The present invention relates to a projection device for a head-up display (HUD), the projection device comprising at least - a composite glass plate (10) having a HUD region (B), the composite glass plate comprising an outer glass plate (1) and an inner glass plate (2), the outer glass plate and the inner glass plate being interconnected via a thermoplastic interlayer (3); - a conductive coating (20) on or within the interlayer (3) of the outer glass plate (1) or the inner glass plate (2) facing the interlayer (3); and - a HUD projector (4) aligned with the HUD region (B); wherein the radiation of the projector (4) is p-polarized, wherein the conductive coating (20) comprises at least the following layers arranged in a given order starting from the substrate: - a first dielectric layer or layer sequence (M1), - a first conductive layer (21.1) having a thickness of 11 nm to 14 nm, - a second dielectric layer or layer sequence (M2), - having a thickness of 10 nm to 13 nm - A second conductive layer (21.2) with a thickness of 10 nm to 13 nm, - a third dielectric layer or layer sequence (M3), - a third conductive layer (21.3) with a thickness of 10 nm to 13 nm, - a fourth dielectric layer or layer sequence (M4), - a fourth conductive layer (21.4) with a thickness of 7 nm to 11 nm, and - a fifth dielectric layer or layer sequence (M5).

Description

Technical Field

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

[0002] Modern cars are increasingly being 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 (from the driver's perspective). Therefore, 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 important information without having to take their eyes off the lane. Head-up displays can thus significantly contribute to improved traffic safety.

[0003] HUD projectors primarily operate using s-polarized radiation and illuminate the windshield panel at an incident angle of approximately 65%, which is close to the Brewster-Winkel angle used for air glass transitions (56.5° for soda-lime glass). A problem arises here: the projected image is reflected at both outer surfaces of the windshield panel. This results in a slightly offset double image, a so-called "ghost," in addition to the desired main image. This problem is typically mitigated, particularly by laminating the windshield panel, which is constructed as a composite glass panel, with wedge-shaped interlayers, aligning the surfaces at an angle to each other, causing the main image and the ghost to overlap. Composite glass with wedge-shaped films used for HUDs is known, for example, from WO2009 / 071135A1, EP1800855B1, or EP1880243A2.

[0004] Wedge-shaped films are expensive, making the manufacture of such composite glass panels for HUDs quite cost-intensive. Therefore, there is a need for HUD projection devices that can function using windshield panels without wedge-shaped films. Thus, for example, it is possible to operate the HUD projector using p-polarized radiation, which is not significantly reflected at the glass surface. Alternatively, the windshield panel has a conductive coating as a reflective surface for p-polarized radiation. DE102014220189A1 discloses such a HUD projection device that is operated using p-polarized radiation. A single metal layer with a thickness of 5 nm to 9 nm, made, for example, of silver or aluminum, is proposed as the reflective structure.

[0005] More complex conductive coatings for windshield panels are also known, for example, as infrared reflective coatings (sunshade coatings) to reduce temperature rise in the vehicle interior and thereby improve thermal comfort. However, the coating can also be used as a heatable coating by connecting it to a voltage source, allowing current to flow through it. Suitable coatings comprise conductive metal layers, particularly silver-based layers. Because these layers are susceptible to corrosion, it is common practice to apply them to the surface of the outer or inner glass panel facing the interlayer, preventing them from contacting the atmosphere. Silver-containing transparent coatings are known, for example, from WO03 / 024155, US2007 / 0082219A1, US2007 / 0020465A1, WO2013 / 104438, or WO2013 / 104439.

[0006] While these known infrared (IR) reflective coatings can theoretically be used as reflective coatings for HUDs, this usually does not lead to completely satisfactory results. That is, the HUD reflective coating must meet other requirements, especially a high and stable reflectance coefficient (Reflexionsgrad) in the area radiated by the projector, in order to result in a strong and color-neutral HUD projection.

[0007] WO2017198363A1 proposes a four-silver coating for a HUD with s-polarized radiation. However, the requirements for reflectivity differ when using s-polarized radiation compared to p-polarized radiation. WO2019179683A1 and WO2020094422A1 propose four-silver coatings for a HUD with p-polarized radiation. While these coatings are optimized for reflectivity relative to p-polarized radiation, they each have very thin silver layers, leading to a decrosslinking problem during heat treatment, resulting in island-like accumulations of silver instead of a uniform layer. WO2021004685A1 and WO2021104800A1 propose single-silver coatings for a HUD with p-polarized radiation. However, these coatings exhibit relatively low reflectivity relative to infrared radiation and relatively high surface resistivity. Therefore, although these coatings result in good reflection of HUD radiation, they can only be used as sunshade coatings or heatable coatings with limitations.

[0008] The conductive coatings known to date therefore have certain drawbacks, which involve either reflectivity relative to p-polarized HUD radiation or shading properties or stability of the layer structure. There is a need for further improved coatings to overcome these drawbacks. Summary of the Invention

[0009] The objective of this invention is an improved projection device for head-up displays (HUDs). The composite glass plate of the projection device should ideally be wedge-free and have a conductive coating that is stable and can also be used as a sunshade coating and / or a heat-resistant coating. The HUD projection should produce high intensity, and the composite glass plate should have a pleasing appearance.

[0010] According to the present invention, the objective is achieved by the projection device according to claim 1. Preferred embodiments are known from the dependent claims.

[0011] According to the present invention, p-polarized radiation is used to generate HUD images, and the composite glass plate has a conductive coating that sufficiently reflects p-polarized radiation. Since the typical incident angle of approximately 65° for a HUD projection device is relatively close to the Brewster angle (56.5°, soda-lime glass) used for air glass transitions, p-polarized radiation is hardly reflected by the glass plate surface, but is primarily reflected by the conductive coating. Therefore, ghosting occurs virtually nonexistently, eliminating the need for expensive wedge-shaped films. The coating has a high and stable reflectance coefficient relative to p-polarized radiation, ensuring a strong and color-neutral HUD representation. Simultaneously, the coating has high reflectivity relative to infrared radiation, effectively reducing energy introduction into vehicles via solar radiation. The coating also has low surface resistance, allowing it to be used as a heatable coating even with the onboard voltage (14V) of common vehicles. The individual conductive layers of the coating are sufficiently thick to ensure the stability of the layer structure, whereas very thin conductive layers could lead to decrosslinking of the layer structure. In particular, it also meets the optical requirements for windshield panels in terms of transparency and tinting. This is a major advantage of the present invention.

[0012] The projection device according to the invention for a head-up display (HUD) comprises at least one composite glass plate with a conductive coating and a projector (HUD projector). As is common in HUD cases, the projector illuminates an area of ​​the windshield where radiation is reflected in the direction of the observer (driver), thereby producing a virtual image perceived by the observer behind the windshield. The area of ​​the composite glass plate that is illuminated by the projector is called the HUD area. The beam direction of the projector can typically be changed by a mirror, especially vertically, to adapt the projection to the viewer's body size. The area in 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 shifted by adjusting the mirror, wherein 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. Of course, this means that the viewer's eyes must be within the eye-tracking range, and not necessarily the entire body.

[0013] The technical terms used here from the HUD field are generally known to those skilled in the art. For a more detailed description, please refer to Alexander Neumann's paper "Simulationsbasierte Messtechnik zur Prüfung von Head-Up Displays" (Munich: University Library of TMU, 2012), especially Chapter 2 "Das Head-Up Display (Head-Up Display)".

[0014] The composite glass panel comprises an outer glass panel and an inner glass panel, which are interconnected via a thermoplastic interlayer. The composite glass panel is used in window openings, particularly in vehicle window openings, to separate an interior space from the external environment. In the context of this invention, the term "inner glass panel" refers to the glass panel of the composite glass panel facing the interior space (particularly the interior space of a vehicle). The term "outer glass panel" refers to the glass panel facing the external environment.

[0015] The composite glass panel according to the invention is preferably a windshield (front glass panel) of land, water, or air vehicles, especially windshields of motor vehicles, such as passenger cars or trucks, or front glass panels of aircraft, ships, or rail vehicles, especially trains. HUDs that project projector radiation is reflected at the windshield panel to produce an image perceptible to the driver (viewer) are particularly common. However, it is also conceivable in principle to project the HUD onto other glass panels, especially vehicle glass panels, such as side window or rear window panels. The position of a person or other vehicle with whom an impending collision is determined by a camera or other sensor can be marked via the HUD on the side window panel, for example. When reversing, the HUD on the rear window panel can provide information to the driver.

[0016] The composite glass panel has a top edge and a bottom edge, as well as two side edges extending between them. The top edge is used to indicate the side positioned to point upwards in the mounting position. The bottom edge is used to indicate the side positioned to point downwards in the mounting position. In the case of a windshield panel, the top edge is often also referred to as the top edge, while the bottom edge is often referred to as the engine edge.

[0017] The outer glass panel and the inner glass panel each have an outer surface and an inner space side surface, as well as a surrounding side extending therebetween. In the context of this invention, the outer surface refers to the main surface configured to face the external environment in the installation position. Similarly, the inner space side surface refers to the main surface configured to face the inner space in the installation 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 interconnected by a thermoplastic interlayer.

[0018] The composite glass panel has a conductive coating, particularly a transparent conductive coating. The conductive coating is preferably applied to the surfaces of the two glass panels facing the interlayer, i.e., the inner space side surface of the outer glass panel or the outer surface of the inner glass panel. Alternatively, the conductive coating can also be disposed within a thermoplastic interlayer, for example, applied to a carrier film disposed between two thermoplastic connecting films. The conductive coating can be, for example, configured as an infrared-reflective shading coating or as a heatable coating, which is electrically contacted and heats up when current flows through it. The transparent coating is understood to have an average transmittance of at least 70%, preferably at least 75%, in the visible spectrum, and the coating does not significantly restrict visibility through the glass panel. Preferably, at least 80% of the glass panel surface is equipped with the coating according to the invention. In particular, except for surrounding edge regions and optionally localized regions, the coating is applied to the entire surface of the glass panel, which, as communication, sensor, or camera windows, should ensure the transmission of electromagnetic radiation through the composite glass panel and are therefore not equipped with a coating. For example, the surrounding uncoated edge area has a width of up to 20 cm. This edge area prevents the coating from direct contact with the surrounding atmosphere, thus protecting the coating inside the composite glass panel from corrosion and damage.

[0019] A conductive cladding is a stack or sequence of layers, particularly composed of thin layers comprising multiple conductive, especially metallic, layers, with each conductive layer disposed between two dielectric layers or sequences of layers. Thus, a cladding is a stack of thin layers having n conductive layers and (n+1) dielectric layers or sequences of layers, where n is a natural number, and where the conductive layers and dielectric layers or sequences of layers alternately follow the underlying dielectric layers or sequences of layers. Such claddings are known as shading claddings and heatable claddings, where the conductive layers are typically based on a silver construction.

[0020] The conductive coating according to the invention has at least four conductive layers. Therefore, the natural number n is at least 4. The coating comprises at least the following layers or layer sequences, arranged in a given order starting from the substrate on which the coating is deposited (i.e., in particular the carrier film in the outer glass plate, inner glass plate, or intermediate layer): First dielectric layer or layer sequence -First conductive layer, -Second dielectric layer or layer sequence -Second conductive layer, -Third dielectric layer or layer sequence -Third conductive layer, - Fourth dielectric layer or layer sequence - Fourth conductive layer, and - The fifth dielectric layer or layer sequence.

[0021] The coating according to the invention may include other conductive layers and dielectric layers or sequences of layers disposed above a fifth dielectric layer or sequence of layers (n>4). However, in a particularly preferred configuration, the natural number n is exactly 4. In principle, a more complex layer structure is not required to achieve the desired specifications of the coating. However, other metal-containing layers may be present, which do not significantly contribute to the conductivity of the reflective coating but serve other purposes. This is particularly suitable for metal barrier layers with a geometric thickness of less than 1 nm, preferably disposed between the silver layer and the dielectric layer sequence.

[0022] The advantageous properties of the coating according to the invention are achieved, in particular, by the targeted selection of the thickness of the conductive layer. According to the invention, the layer thickness is as follows: - The first conductive layer is 11 nm to 14 nm in size. - The second conductive layer is 10 nm to 13 nm. - The third conductive layer is 10 nm to 13 nm. - The fourth conductive layer is 7 nm to 11 nm.

[0023] Preferably, the thickness of the first conductive layer is greater than the thickness of the fourth conductive layer. More preferably, the thicknesses of the second and third conductive layers are also greater than the thickness of the fourth conductive layer. This achieves particularly good results. Furthermore, it is also preferable that the thickness of the first conductive layer is greater than the thickness of the second conductive layer.

[0024] Unless otherwise specified, the description of layer thickness or thickness refers to the geometric thickness of the layers. The thickness of the first conductive layer is preferably 11.5 nm to 13.5 nm, especially 12 nm to 13 nm. The thickness of the second conductive layer is preferably 10 nm to 12.5 nm, especially 10 nm to 12 nm. The thickness of the third conductive layer is preferably 11 nm to 12.5 nm. The thickness of the fourth conductive layer is preferably 7.5 nm to 10 nm, especially 7.5 nm to 9.5 nm. This achieves particularly good results.

[0025] The conductivity of the coating is caused by a functional conductive layer. Each conductive layer preferably comprises at least one metal or metal alloy, and is particularly preferably based on a metal or metal alloy construction, i.e., substantially composed of a metal or metal alloy except for possible dopants or impurities. The conductive layer is preferably based on silver (Ag) or a silver-containing alloy construction. In an advantageous configuration, the conductive layer comprises at least 90 wt% (Gew.%) of silver, preferably at least 99 wt% of silver, and particularly preferably at least 99.9 wt% of silver. The silver layer may have dopants, such as palladium, gold, copper, or aluminum.

[0026] In particular, the thickness of the conductive layer according to the invention provides favorable reflective properties relative to the radiation of the HUD projector. These reflective properties can be further optimized by the dielectric layers or layer sequences, with the optical thickness being particularly influential. The optical thickness is derived as the product of the refractive index and the geometric thickness. The optical thicknesses of the first and fifth dielectric layers or layer sequences have a significant impact. The optical thickness of the first dielectric layer or layer sequence is preferably 50 nm to 150 nm, particularly preferably 80 nm to 120 nm, completely particularly preferably 90 nm to 110 nm, and especially preferably 95 nm to 105 nm. The optical thickness of the fifth dielectric layer or layer sequence is preferably 50 nm to 150 nm, particularly preferably 70 nm to 110 nm, completely particularly preferably 75 nm to 95 nm, and especially preferably 80 nm to 90 nm. The optical thickness of the second, third, and fourth (“intermediate”) dielectric layers or layer sequences is preferably 100 nm to 200 nm, particularly preferably 120 nm to 180 nm, and very particularly preferably 150 nm to 170 nm, independent of each other.

[0027] In one configuration of the invention, all dielectric layers have a refractive index greater than 1.8, preferably greater than 1.9. In other words, all dielectric layers or layer sequences are constructed solely of dielectric layers having a refractive index greater than 1.8. This yields favorable results. The dielectric layers can be constructed, for example, based on silicon nitride, silicon-metal mixed nitrides (e.g., silicon-zirconium nitride (SiZrN), silicon-aluminum mixed nitrides, silicon-hafnium mixed nitrides, or silicon-titanium mixed nitrides), aluminum nitride (AlN), tin oxide (SnO), manganese oxide (MnO), tungsten oxide (WO3), niobium oxide (Nb2O5), bismuth oxide (Bi2O3), titanium oxide (TiO2), zinc oxide (ZnO), or tin-zinc mixed oxides (SnZnO). The preferred ranges given above for the optical thickness of the dielectric layers or layer sequences are particularly applicable to such dielectric layers or layer sequences comprising only layers having a refractive index greater than 1.8.

[0028] Within the scope of this invention, the refractive index is given in principle with respect to a wavelength of 550 nm. For example, the refractive index can be determined by means of ellipsometric measurement. Ellipsometrometers are commercially available, for example from companies such as Sentech.

[0029] The materials mentioned in this specification can be deposited in a stoichiometric, substoichiometric, or overstoichiometric manner. The materials may contain dopants, particularly aluminum, boron, zirconium, or titanium. Through doping, the dielectric material itself can be equipped with a certain conductivity. However, those skilled in the art will identify the dielectric material in terms of its function as a dielectric layer, as is common in the field of thin layers. The dielectric layer material preferably has a conductivity of less than 10. -4The conductivity (the reciprocal of the specific resistance) is S / m. The material of the conductive layer preferably has a conductivity greater than 10. 4 Conductivity in S / m.

[0030] In a preferred configuration, at least one of the dielectric layer sequences comprises a dielectric layer having a refractive index of less than 1.8, preferably less than 1.6, which may also be referred to as a low-refractive-index layer. The layer sequence further preferably comprises one or more dielectric layers having a refractive index greater than 1.8. The optical thickness of the low-refractive-index layer is preferably 20 nm to 40 nm, particularly preferably 25 nm to 35 nm. The low-refractive-index layer is preferably based on a silicon oxide structure and may further contain dopants (e.g., aluminum, boron, or antimony) or impurities. The dielectric layer sequence having the low-refractive-index layer is preferably arranged between two conductive layers, particularly between the first and second conductive layers. Surprisingly, such a dielectric layer sequence can significantly improve the reflectance coefficient of p-polarized projector radiation relative to the relevant spectral range of 450 nm to 650 nm. The sum of the optical thicknesses of all layers in the layer sequence having a refractive index greater than 1.8 preferably corresponds to the aforementioned values, i.e., preferably 100 nm to 200 nm, particularly preferably 120 nm to 180 nm, and very particularly preferably 150 nm to 170 nm. The sum of the optical thicknesses of all layers in the layer sequence having a refractive index greater than 1.8 is particularly preferably 150 nm to 160 nm. The total optical thickness of the layer sequence is preferably 150 nm to 220 nm, particularly preferably 170 nm to 200 nm, and entirely particularly preferably 180 nm to 190 nm. The remaining dielectric layers or layer sequences are preferably constructed only of dielectric layers having a refractive index greater than 1.8 with optical thicknesses of preferably 100 nm to 200 nm, particularly preferably 120 nm to 180 nm, and entirely particularly preferably 150 nm to 170 nm.

[0031] The conductive coating according to the invention has infrared reflective properties, enabling it to function as a sunshade coating that reduces heating of the vehicle's interior space by reflecting thermal radiation. Here, the TTS value of the composite glass panel equipped with the coating is preferably less than 50%, particularly preferably less than 45%. The TTS value represents the total solar radiant energy measured according to ISO 13837—the TTS value is a measure of thermal comfort. If the coating is electrically contacted, allowing current to flow through it, it can also be used as a heating coating, the current causing the coating to heat up. The surface resistivity of the coating is preferably less than 1 Ω / square, particularly less than 0.9 Ω / square.

[0032] In particular, the spectral range of 450 nm to 650 nm is important for the reflectivity of HUD projectors, as the radiation of typical projectors lies within this range, especially with dominant wavelengths of 473 nm, 550 nm, and 630 nm (RGB). Within this spectral range, the reflectivity should be as high as possible to ensure a strong HUD image. The composite glass plate equipped with a conductive coating preferably has an average reflectivity of at least 5%, and particularly preferably at least 7%, relative to p-polarized radiation in the spectral range of 450 nm to 650 nm.

[0033] The reflection coefficient describes the reflected component of the total incident radiation. The reflection coefficient is given as a percentage (with respect to 100% of the incident radiation) or as a dimensionless value from 0 to 1 (normalized to the incident radiation). Depending on the wavelength, the reflection coefficient constitutes the reflection spectrum. Statements regarding the reflection coefficient relative to p-polarized radiation, within the scope of this invention, refer to the reflection coefficient measured at an angle of incidence of 65° relative to the normal to the side plane of the interior space, which roughly corresponds to illumination through a common projector. Descriptions of the reflection coefficient or reflection spectrum refer to reflection measurements using a light source that radiates uniformly with 100% normalized radiant intensity over the considered spectral range.

[0034] To achieve the most color-neutral representation of the projector image possible, the reflectance spectrum should be as smooth as possible and not exhibit significant local minima and maxima. In a preferred configuration, the difference between the maximum reflectance coefficient and the average reflectance coefficient, and the difference between the minimum reflectance coefficient and the average reflectance coefficient, should be at most 5% in the spectral range of 450 nm to 650 nm. The given differences can be understood as absolute deviations of the reflectance coefficients (given as %), rather than as percentage deviations relative to the average. This smoothness of the reflectance spectrum can be achieved without problem using the conductive coating according to the invention.

[0035] The desired reflective characteristics are achieved, in particular, through the selection of the material and thickness of the single layer and the structure of the dielectric layer sequence. Therefore, the conductive coating can be appropriately adjusted.

[0036] A projector (HUD projector) is aimed at the HUD area of ​​the composite glass panel. The projector is positioned on the inner space side of the composite glass panel and illuminates the composite glass panel via the inner space side surface of the inner glass panel. According to the invention, the radiation from the projector is at least partially p-polarized, i.e., has at least one p-polarized component. The p-polarized radiation component is preferably at least 80%. The radiation from the projector is preferably completely or almost completely p-polarized (essentially purely p-polarized). The p-polarized radiation component is hereby 100% or only negligibly deviates from this. This produces a particularly strong HUD image and avoids ghosting. The description of the polarization direction here refers to the radiation on the plane of incidence on the composite glass panel. p-polarized radiation represents radiation whose electric field oscillates in the plane of incidence. s-polarized radiation represents radiation whose electric field oscillates perpendicular to the plane of incidence. The plane of incidence is defined by the incident vector at a point on the composite glass panel within the HUD area, preferably at the geometric center of the HUD area, and the plane normal. Due to the bending of glass plates, a common feature in the field of transportation, which affects the plane of incidence and thus the definition of polarization, the ratio of p-polarized radiation to s-polarized radiation may differ at other points from this reference point.

[0037] When a HUD is in operation, p-polarized radiation emitted by a projector illuminates the HUD area to produce a HUD projection. The projector's radiation lies within the visible spectrum of the electromagnetic spectrum—typical HUD projectors operate at wavelengths of 473 nm, 550 nm, and 630 nm (RGB). Since the typical incident angle for a HUD projection device is relatively close to the Brewster angle used for the air glass transition (56.5° to 56.6°, soda-lime glass, n² = 1.51–1.52), the p-polarized radiation is hardly reflected by the glass surface. Therefore, ghosting caused by reflections at the inner space side surface of the inner glass and the outer surface of the outer glass appears with only a small intensity. Besides avoiding ghosting, using p-polarized radiation has the advantage that the HUD image is visible to wearers of polarization-selective sunglasses, which typically allow only p-polarized radiation to pass through while blocking s-polarized radiation.

[0038] The projector's radiation is preferably incident on the composite glass plate at an angle of incidence of 45° to 70°, particularly 60° to 70°. In an advantageous configuration, the angle of incidence deviates from the Brewster angle by at most 10°. The p-polarized radiation is then reflected only negligibly at the surface of the composite glass plate, so that no ghosting occurs. The angle of incidence is the angle between the incident vector of the projector radiation at the geometric center of the HUD area and the normal to the plane of the inner space side (i.e., the plane normal to the outer surface of the inner space side of the composite glass plate). Ideally, the angle of incidence should be as close as possible to the Brewster angle. However, an angle of incidence of 65° can also be used, for example, which is common for HUD projection devices, can be implemented without problems in vehicles, and deviates only slightly from the Brewster angle, so that the reflection of p-polarized radiation increases only negligibly.

[0039] Since the reflection of projector radiation occurs primarily at the reflective coating and not at the outer glass surface, it is unnecessary to arrange the outer glass surfaces at an angle to each other to avoid ghosting. Here, "outer glass surface" refers to the opposing surfaces of the individual glass panels, i.e., the outer surface of the outer glass panel and the inner space side surface of the inner glass panel. Therefore, the outer surfaces of the composite glass panels are preferably arranged substantially parallel to each other. For this purpose, the thermoplastic interlayer is preferably not constructed in a wedge shape, but has a substantially constant thickness, especially not in the vertical direction between the upper and lower edges of the composite glass panel, as with the inner and outer glass panels. A wedge-shaped interlayer would have a variable, and particularly increasing, thickness in the vertical direction between the lower and upper edges of the side window glass panels. The interlayer is typically constructed of at least one thermoplastic film. Since standard films are significantly less expensive than wedge-shaped films, the manufacture of composite glass panels becomes more advantageous.

[0040] The reflectivity of the conductive coating relative to the radiation emitted by the HUD projector is primarily influenced by the material and thickness of the conductive layer, as well as the optical thickness of the dielectric layer or layer sequence. However, by appropriately shaping the dielectric layer sequence, the coating properties can be further optimized, for example, in terms of surface resistivity or transparency. In a preferred configuration, dielectric layer sequences consisting of multiple dielectric layers exist between adjacent conductive layers, above the uppermost conductive layer, and below the lowermost conductive layer, instead of a single dielectric layer.

[0041] In an advantageous configuration, each dielectric layer or layer sequence includes an antireflective layer. The antireflective coating reduces the reflection of visible light and thus improves the transparency of the coated glass plate. For example, the antireflective layer is constructed based on silicon nitride (SiN), silicon-metal mixed nitrides, such as zirconium silicon nitride (SiZrN), aluminum nitride (AlN), or tin oxide (SnO). The antireflective layer may also have dopants. The antireflective layer preferably has a thickness of 10 nm to 100 nm, particularly preferably 20 nm to 50 nm.

[0042] The antireflective layer can be further subdivided into at least two sublayers, particularly into a dielectric layer having a refractive index less than 2.1 and an optically high-refractive-index layer having a refractive index greater than or equal to 2.1. At least one antireflective coating disposed between the two conductive layers is preferably subdivided in this manner. This subdivision of the antireflective layer results in a lower surface resistance of the conductive coating while simultaneously achieving high transmittance and high color neutrality. In principle, the order of the two sublayers can be arbitrarily chosen, with the optically high-refractive-index layer preferably disposed above the dielectric layer, which is particularly advantageous in terms of surface resistance. The thickness of the optically high-refractive-index layer is preferably 10% to 99% of the total thickness of the antireflective layer, particularly preferably 25% to 75%, and completely, particularly preferably 40% to 60%.

[0043] Optically high refractive index layers having a refractive index greater than or equal to 2.1 include, for example, MnO, WO3, Nb2O5, Bi2O3, TiO2, Zr3N4, and / or AlN, preferably silicon-metal mixed nitrides, such as silicon-hafnium mixed nitrides or silicon-titanium mixed nitrides, and particularly preferably silicon-zirconium mixed nitrides (SiZrN). This is particularly advantageous in terms of the surface resistivity of the conductive coating. The silicon-zirconium mixed nitrides preferably have dopants. The optically high refractive index layer may, for example, comprise an aluminum-doped silicon-zirconium mixed nitride. Here, the zirconium content is preferably between 15 and 45 wt%, and particularly preferably between 15 and 30 wt%.

[0044] The dielectric layer having a refractive index of less than 2.1 preferably has a refractive index between 1.6 and 2.1, particularly preferably between 1.9 and 2.1. The dielectric layer preferably comprises at least one oxide, such as tin oxide, and / or a nitride, particularly preferably silicon nitride.

[0045] In an advantageous configuration, one or more dielectric layer sequences have a first adapter layer, preferably each dielectric layer sequence disposed below a conductive layer. The first adapter layer is preferably disposed above an antireflective layer. The first adapter layer is preferably disposed directly below the conductive layer, such that the first adapter layer is in direct contact with the conductive layer. This is particularly advantageous in terms of the crystallinity of the conductive layer.

[0046] In an advantageous configuration, one or more dielectric layer sequences have a smoothing layer, preferably each dielectric layer sequence disposed between two conductive layers has a smoothing layer, and particularly preferably the bottommost dielectric layer sequence (the first dielectric layer sequence) also has a smoothing layer. If such a first adapter layer is present, the smoothing layer is disposed below one of the first adapter layers, preferably disposed between the antireflective layer and the first adapter layer. The smoothing layer is particularly preferably in direct contact with the first adapter layer. The smoothing layer optimizes, in particular, the surface of the conductive layer subsequently applied above. The conductive layer deposited on a smoother surface has higher transmittance with simultaneously lower surface resistance. The thickness of the smoothing layer is preferably 5 nm to 20 nm, particularly preferably 7 nm to 12 nm. The smoothing layer preferably has a refractive index of less than 2.2.

[0047] The smoothing layer preferably comprises at least one amorphous oxide. The oxide may be amorphous or partially amorphous (and therefore partially crystalline), but not fully crystalline. The amorphous smoothing layer has low roughness and thus constitutes a favorable smooth surface for the layer to be applied over it. The amorphous smoothing layer further results in an improved surface structure for the layer deposited directly over it, which is preferably a first adapter layer. The smoothing layer may, for example, comprise at least one oxide of one or more of the elements tin, silicon, titanium, zirconium, hafnium, zinc, gallium, and indium. The smoothing layer particularly preferably comprises an amorphous mixed oxide. The smoothing layer particularly preferably comprises a tin-zinc mixed oxide (ZnSnO). The mixed oxide may have dopants. The smoothing layer may, for example, comprise an antimony-doped tin-zinc mixed oxide. The mixed oxide preferably has a substoichiometric oxygen content. Here, the tin content is preferably between 10 and 40% by weight, particularly preferably between 12 and 35% by weight.

[0048] In an advantageous configuration, one or more dielectric layer sequences have a second adapter layer, preferably each dielectric layer sequence disposed above the conductive layer has a second adapter layer. The second adapter layer is preferably disposed below the antireflective layer.

[0049] The first and second adapter layers improve the surface resistivity of the coating. The first and / or second adapter layers preferably comprise zinc oxide (ZnO). 1-δ , of which 0 δ 0.01. The first adapter layer and / or the second adapter layer further preferably contain dopants. The first adapter layer and / or the second adapter layer may, for example, contain aluminum-doped zinc oxide (ZnO:Al). The zinc oxide is preferably deposited with respect to oxygen in a substoichiometric manner to avoid excess oxygen reacting with the silver-containing layer. The layer thickness of the first adapter layer and the second adapter layer is preferably 5 nm to 20 nm, particularly preferably 10 nm to 20 nm.

[0050] In an advantageous configuration, the conductive coating includes one or more barrier layers. Preferably, at least one barrier layer is assigned to each conductive layer, particularly preferably each. The barrier layer is in direct contact with the conductive layer and is disposed directly above or below the conductive layer. Therefore, no other layers are disposed between the conductive layer and the barrier layer. Alternatively, barrier layers can be disposed directly above and directly below the conductive layer, respectively. The barrier layer preferably comprises niobium, titanium, nickel, chromium, and / or alloys thereof, particularly preferably nickel-chromium alloys. The thickness of the barrier layer is preferably from 0.1 nm to 1 nm, particularly preferably from 0.1 nm to 0.5 nm. The barrier layer directly below the conductive layer is particularly useful for stabilizing the conductive layer during temperature processing and improving the optical quality of the conductive coating. The barrier layer directly above the conductive layer prevents the sensitive conductive layer from contacting the oxidizing reactive atmosphere during the deposition of an adjacent layer (e.g., a second adapter layer) by sputtering with a reactive cathode.

[0051] If the dielectric layer sequence includes a low-refractive layer with a refractive index of less than 1.8, the low-refractive layer is preferably disposed between the anti-reflective layer and the conductive layer above it, particularly between the anti-reflective layer and the smoothing layer above it.

[0052] If the layer is constructed based on a material, then the layer is mostly composed of that material, except for possible impurities or dopants. If the first layer is disposed above the second layer, this in the sense of the invention means that the first layer is disposed further away from the substrate than the second layer, and the cladding is applied to said substrate. If the first layer is disposed below the second layer, this in the sense of the invention means that the second layer is disposed further away from the substrate than the first layer. If the first layer is disposed above or below the second layer, this does not necessarily mean that the first and second layers are in direct contact with each other in the sense of the invention. One or more other layers may be disposed between the first and second layers, provided that this is not explicitly excluded.

[0053] In an advantageous configuration, a sequence of dielectric layers is arranged between two conductive layers, the sequence of dielectric layers comprising: - Antireflective layers based on silicon nitride, silicon-metal mixed nitrides, such as silicon zirconium nitride, aluminum nitride, and / or tin oxide. - A smoothing layer based on oxides of one or more of the elements tin, silicon, titanium, zirconium, hafnium, zinc, gallium, and indium. - First and second adapter layers based on zinc oxide, and - Optionally, a barrier layer based on niobium, titanium, nickel, chromium, and / or alloys thereof. A specific order of the layers is not required. The anti-reflective layer and adapter layer based on the aforementioned preferred materials are preferably arranged below the bottommost conductive layer and above the topmost conductive layer.

[0054] The conductive coating having the reflective characteristics according to the invention can preferably be implemented in different ways when using the aforementioned layers, so that the invention is not limited to a specific layer sequence. A particularly preferred configuration of the coating is then described, especially with which particularly good results are obtained at a typical radiation incident angle of about 65°.

[0055] A particularly preferred configuration of the conductive coating comprises, or consists of, the following layer sequence starting from the substrate: - An antireflective layer preferably based on a silicon-metal mixed nitride, such as silicon zirconium nitride or silicon hafnium nitride, having a thickness of 10 nm to 30 nm, preferably 15 nm to 25 nm, particularly preferably 18 nm to 23 nm. - A smooth layer, preferably based on a tin-zinc mixed oxide, having a thickness of 5 nm to 15 nm, preferably 5 nm to 10 nm. -Having a first adapter layer preferably based on zinc oxide with a thickness of 5 nm to 15 nm, preferably 8 nm to 12 nm, -A silver-based conductive layer having a thickness of 11 nm to 14 nm, preferably 11.5 nm to 13.5 nm. - Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.5 nm. -Having a second adapter layer, preferably based on zinc oxide, with a thickness of 10 nm to 20 nm, preferably 14 nm to 18 nm. - An antireflective layer having a thickness of 20 nm to 40 nm, preferably 25 nm to 35 nm, particularly preferably 30 nm to 35 nm, preferably based on a silicon-metal mixed nitride, such as silicon zirconium nitride or silicon hafnium nitride. -Optionally, it has a refractive index of less than 1.8 and a preferably silicon oxide-based low-refractive-index layer with a thickness of 5 nm to 50 nm, preferably 10 nm to 30 nm, particularly preferably 15 nm to 25 nm. - A smooth layer, preferably based on a tin-zinc mixed oxide, having a thickness of 5 nm to 15 nm, preferably 8 nm to 12 nm. -Having a first adapter layer, preferably based on zinc oxide, with a thickness of 10 nm to 20 nm, preferably 13 nm to 18 nm. -A silver-based conductive layer having a thickness of 10 nm to 13 nm, preferably 10 nm to 12.5 nm. -Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.5 nm. -Having a second adapter layer, preferably based on zinc oxide, with a thickness of 10 nm to 20 nm, preferably 13 nm to 18 nm. - An antireflective layer having a thickness of 25 nm to 45 nm, preferably 30 nm to 40 nm, preferably subdivided into a silicon nitride-based dielectric layer having a thickness of 15 nm to 20 nm and an optically high-refractive-index layer having a thickness of 15 nm to 20 nm, based on a silicon-metal hybrid nitride, such as silicon zirconium nitride or silicon hafnium nitride. - A smooth layer, preferably based on a tin-zinc mixed oxide, having a thickness of 5 nm to 15 nm, preferably 8 nm to 12 nm. -Having a first adapter layer preferably based on zinc oxide with a thickness of 10 nm to 20 nm, preferably 12 nm to 17 nm, -A silver-based conductive layer having a thickness of 10 nm to 13 nm, preferably 11 nm to 12.5 nm. - Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.5 nm. -Having a second adapter layer, preferably based on zinc oxide, with a thickness of 10 nm to 20 nm, preferably 13 nm to 18 nm. - An antireflective layer having a thickness of 30 nm to 50 nm, preferably 35 nm to 45 nm, preferably subdivided into a silicon nitride-based dielectric layer having a thickness of 18 nm to 23 nm and an optically high-refractive-index layer having a thickness of 18 nm to 23 nm, based on a silicon-metal hybrid nitride, such as silicon zirconium nitride or silicon hafnium nitride. - A smooth layer, preferably based on a tin-zinc mixed oxide, having a thickness of 5 nm to 15 nm, preferably 8 nm to 12 nm. -Having a first adapter layer preferably based on zinc oxide with a thickness of 8 nm to 18 nm, preferably 10 nm to 15 nm, -A silver-based conductive layer having a thickness of 7 nm to 11 nm, preferably 7.5 nm to 10 nm. -Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.5 nm. -Having a second adapter layer, preferably based on zinc oxide, with a thickness of 8 nm to 18 nm, preferably 10 nm to 15 nm. - An antireflective layer having a thickness of 25 nm to 45 nm, preferably 30 nm to 40 nm, is preferably subdivided into an optically high refractive layer having a thickness of 10 nm to 15 nm based on a silicon-metal mixed nitride, such as silicon zirconium nitride or silicon hafnium nitride, and a silicon nitride-based dielectric layer having a thickness of 22 nm to 27 nm.

[0056] A particularly preferred configuration of the conductive coating comprises, or consists of, the following layer sequence starting from the substrate: - An antireflective layer with a thickness of 20 nm to 23 nm based on silicon-metal mixed nitrides, such as silicon zirconium nitride or silicon hafnium nitride. - A smooth layer based on a tin-zinc mixed oxide with a thickness of 7 nm to 9 nm. - It has a zinc oxide-based first adapter layer with a thickness of 10 nm to 12 nm. -Having a silver-based conductive layer with a thickness of 11.5 nm to 13.5 nm, especially 12 nm to 13 nm, - Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.3 nm. - It has a zinc oxide-based second adapter layer with a thickness of 15 nm to 17 nm. - An antireflective layer with a thickness of 31 nm to 33 nm based on silicon-metal mixed nitrides, such as silicon zirconium nitride or silicon hafnium nitride. - Preferably, it has a low-refractive-index layer based on silicon oxide with a thickness of 18 nm to 22 nm and a refractive index of less than 1.8. - A smooth layer based on a tin-zinc mixed oxide with a thickness of 9 nm to 11 nm. - It has a zinc oxide-based first adapter layer with a thickness of 15 nm to 17 nm. -Having a silver-based conductive layer with a thickness of 10 nm to 12.5 nm, especially 10 nm to 12 nm, - Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.3 nm. - It has a zinc oxide-based second adapter layer with a thickness of 14 nm to 16 nm. - Antireflective layer, which is further subdivided into a silicon nitride-based dielectric layer with a thickness of 16 nm to 18 nm and an optically high-refractive-index layer based on silicon-metal hybrid nitrides, such as silicon zirconium nitride or hafnium silicon nitride, with a thickness of 16 nm to 18 nm. - A smooth layer based on a tin-zinc mixed oxide with a thickness of 10 nm to 12 nm. - It has a zinc oxide-based first adapter layer with a thickness of 13 nm to 15 nm. - Contains a silver-based conductive layer with a thickness of 11 nm to 12.5 nm. - Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.3 nm. - It has a zinc oxide-based second adapter layer with a thickness of 15 nm to 17 nm. - Antireflective layer, which is further subdivided into a silicon nitride-based dielectric layer with a thickness of 20 nm to 22 nm and an optically high-refractive-index layer based on silicon-metal hybrid nitrides, such as silicon zirconium nitride or hafnium silicon nitride, with a thickness of 20 nm to 22 nm. - A smooth layer based on a tin-zinc mixed oxide with a thickness of 9 nm to 11 nm. - It has a zinc oxide-based first adapter layer with a thickness of 11 nm to 13 nm. -Having a silver-based conductive layer with a thickness of 7.5 nm to 10 nm, especially 7.5 nm to 9.5 nm, - Optionally, it has a NiCr-based barrier layer with a thickness of 0.1 nm to 0.3 nm. -Having a zinc oxide-based second adapter layer with a thickness of 12 nm to 14 nm, - Antireflective layers, which are further subdivided into silicon-metal hybrid nitride-based high-refractive-index layers with a thickness of 11 nm to 13 nm, such as silicon zirconium nitride or silicon hafnium nitride, and silicon nitride-based dielectric layers with a thickness of 24 nm to 26 nm.

[0057] The outer and inner glass panes are preferably made of glass, particularly soda-lime glass, which is common for window panes. 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 in the range of 0.8 mm to 5 mm, preferably 1.4 mm to 2.9 mm, are preferred, for example, glass panes with a standard thickness of 1.6 mm or 2.1 mm.

[0058] The outer glass pane, inner glass pane, and thermoplastic interlayer can be bright and colorless, but can also be tinted or colored. In a preferred configuration, the total transmittance through the composite glass for light type A is greater than 70%. The term total transmittance is referenced by ECE-R 43, Annex 3. The method specified in 9.1 for testing the light transmittance of automotive glass panels. The outer and inner glass panels may be unstressed, partially stressed, or stressed independently of each other. If at least one of the glass panels is required to have prestress, this may be thermal or chemical prestress. It must be ensured that the conductive coating does not significantly reduce the total transmittance.

[0059] The windshield panel is preferably curved in one or more directions in space, as is common for motor vehicle glass panels, with a typical radius of curvature ranging from about 10 cm to about 40 m. However, the composite glass panel can also be flat, for example, when it is used for glass panels in buses, trains, or tractors.

[0060] The thermoplastic interlayer comprises at least one thermoplastic polymer, preferably ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU), or a mixture, copolymer, or derivative thereof, particularly preferably PVB. The interlayer is typically constructed of a thermoplastic film. The thickness of the interlayer is preferably from 0.2 mm to 2 mm, particularly preferably from 0.3 mm to 1 mm.

[0061] Composite glass sheets can be manufactured using methods known per se. For example, they can be laminated together via an interlayer using methods such as autoclaving, vacuum bagging, vacuum ringing, calendering, vacuum lamination, or combinations thereof. Here, the bonding of the outer and inner glass sheets is typically performed under the influence of heat, vacuum, and / or pressure.

[0062] The conductive coating is preferably applied to the inner glass plate by physical vapor deposition (PVD), particularly preferably by cathode sputtering (“sputtering”), and especially preferably by magnetic field-assisted cathode sputtering (“magnetron sputtering”). However, in principle, the coating can also be applied by means of chemical vapor deposition (CVD), such as plasma-assisted vapor deposition (PECVD), by vapor deposition, or by atomic layer deposition (ALD). The coating is preferably applied to the glass plate prior to lamination. Instead of applying the conductive coating to the surface of the glass plate, the conductive coating can also be provided in principle on a carrier film disposed in an intermediate layer.

[0063] 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, more preferably, after any possible coating process. The outer and inner glass sheets are preferably bent together (i.e., simultaneously and using the same tool) in a completely uniform manner, as this ensures that the shapes of the glass sheets are optimally coordinated for subsequent lamination. Typical temperatures for the glass bending process are, for example, 500°C to 700°C. This temperature treatment also improves transparency and reduces the surface resistivity of the conductive coating.

[0064] If the conductive coating is to be used as a heatable coating, it must be electrically contacted so that it can be connected to a voltage source, typically the on-board voltage of a vehicle. A particular advantage of the coating according to the invention is that, based on its surface resistance, the coating can be operated as a heatable coating using the common on-board voltage of motor vehicles, especially passenger cars, where the heating effect is sufficient for rapid de-icing or moisture removal. Common on-board voltages are 12 V to 15 V, especially around 14 V. For connection to a voltage source, the coating is preferably equipped with a busbar that can be connected to the poles of the voltage source to conduct current into the coating over the largest possible portion of the glass plate width. For example, the busbar can be constructed as an embossed and calcined conductor, typically in the form of a calcined screen-printed paste with glass frit and silver particles. However, alternatively, strips of conductive films (e.g., copper or aluminum films) can also be used as busbars, which are placed or adhered to the coating. Two bus conductors are typically positioned near two opposite sides of the composite glass plate, such as near the top and bottom edges.

[0065] The invention further includes the use of a composite glass plate constructed according to the invention as a projection surface for a projection device for a head-up display (HUD), wherein the projector is aligned with the HUD area and the radiation from the projector is p-polarized. The foregoing preferred configuration is accordingly suited to this application.

[0066] The invention also includes the use of the projection device according to the invention as a HUD in land, water or air transportation, preferably motor vehicles, rail vehicles, aircraft or ships, especially passenger cars or trucks. Attached Figure Description

[0067] The invention will now be described in more detail with reference to the accompanying drawings and embodiments. The drawings are schematic and not drawn to scale. The drawings do not limit the invention in any way.

[0068] Figure 1 A top view of the composite glass plate of this type of projection device is shown. Figure 2 The cross-section of this type of projection device is shown. Figure 3 The cross-section of the composite glass plate through the projection device according to the invention is shown. Figure 4 The cross-section of the conductive coating according to the invention is shown, and Figure 5 The reflection spectra of the composite glass plate according to the invention and a comparative example are shown relative to p-polarized radiation. Detailed Implementation

[0069] Figures 1 and 2 illustrate details of this type of projection device for a HUD. The projection device includes a composite glass panel 10, particularly the windshield of a passenger vehicle. The projection device further includes a HUD projector 4, which is aimed at region B of the composite glass panel 10. In region B, commonly referred to as the HUD area, an image can be generated by the projector 4, which is perceived by the observer 5 (e.g., a vehicle driver) as a virtual image of the composite glass panel 10 on the side facing away from the observer, when the observer's eyes are within the so-called eyebox E.

[0070] 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 via a thermoplastic interlayer 3. The lower edge U of the composite glass panel is arranged downwards in the direction of the passenger vehicle's engine, and the upper edge O of the composite glass panel is arranged upwards in the top direction. 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.

[0071] Figure 3 This diagram illustrates a configuration of a composite glass panel 10 constructed according to the present invention. The outer glass panel 1 has an outer surface I facing the external environment in the mounting position and an inner space side surface II facing the internal space in the mounting position. Similarly, the inner glass panel 2 has an outer surface III facing the external environment in the mounting position and an inner space side surface IV facing the internal space in the mounting position. The outer glass panel 1 and the inner glass panel 2 are, for example, composed of soda-lime glass. The outer glass panel 1 has, for example, a thickness of 2.1 mm, and the inner glass panel 2 has a thickness of 1.6 mm. The intermediate layer 3 is, for example, constructed of a PVB film with a thickness of 0.76 mm. The PVB film has a substantially constant thickness, except for surface roughness commonly found in the industry.

[0072] The outer surface III of the inner glass plate 2 is provided with a conductive coating 20 according to the invention, which is configured as a reflective surface for projector radiation and is additionally configured, for example, as an infrared reflective coating or a heatable coating.

[0073] According to the present invention, the radiation from the projector 4 is p-polarized, and in particular, essentially purely p-polarized. Since the projector 4 illuminates the composite glass plate 10 at an incident angle of approximately 65°, close to Brewster's angle, the radiation from the projector is only negligibly reflected at the outer surfaces I and IV of the composite glass plate 10. The conductive coating 20 according to the present invention optimizes the reflection of p-polarized radiation. This conductive coating serves as a reflective surface for the radiation from the projector 4 to produce a HUD projection.

[0074] Figure 4 The diagram illustrates the layer sequence of the conductive coating 20 on the inner glass plate 2 according to the invention. The coating 20 comprises five dielectric layer sequences M1, M2, M3, M4, and M5 arranged alternately and four conductive layers 21 (21.1, 21.2, 21.3, and 21.4). Thin barrier layers 26 (26.1, 26.2, 26.3, and 26.4) are arranged between each conductive layer 21 and the dielectric layer sequence above it.

[0075] The first dielectric layer sequence M1 is constructed from an antireflection layer 22.1, a smoothing layer 23.1, and a first adapter layer 24.1.

[0076] The second dielectric layer sequence M2 is constructed from a second adapter layer 25.1, an anti-reflection layer 22.2, an optically low refractive layer 27 with a refractive index of less than 1.8, a smoothing layer 23.2, and a first adapter layer 24.2.

[0077] The third dielectric layer sequence M3 is constructed from a second adapter layer 25.3, an antireflective layer 22.3, a smoothing layer 23.3, and a first adapter layer 24.3. The antireflective layer 22.3 is further subdivided into a dielectric layer 22a.3 with a refractive index less than 2.1 and an optically high refractive layer 22b.3 with a refractive index greater than 2.1.

[0078] The fourth dielectric layer sequence M4 is constructed from a second adapter layer 25.4, an anti-reflection layer 22.4, a smoothing layer 23.4, and a first adapter layer 24.4. Here, the anti-reflection layer 22.4 is further subdivided into a dielectric layer 22a.4 and an optical high-refractive-index layer 22b.4.

[0079] The fifth dielectric layer sequence M5 is constructed from a second adapter layer 25.5 and an anti-reflective layer 22.5, the latter of which is further subdivided into an optical high-refractive-index layer 22b.5 and a dielectric layer 22a.5. Compared with dielectric layer sequences M3 and M4, the optical high-refractive-index layer 22b.5 and the dielectric layer 22a.5 are arranged in the reverse order.

[0080] All dielectric layers except the low-refractive-index layer 27 have a refractive index greater than 1.8. The layer sequence can be schematically seen from this figure. The structure shown corresponds to Example 5 described below. The layer sequence of the composite glass plate 10 having a cladding layer 20 on the outer surface III of the inner glass plate 2 is shown in Table 1 along with the material and thickness of the single layers (Example 5). Table 1 also shows four other examples (Examples 1 to 4) according to the invention.

[0081] Table 2 shows the layer sequences of a conductive coating not according to the invention (Comparative Example 1) and another configuration of the coating according to the invention (Example 6). The difference between Comparative Example 1 and the example according to the invention lies particularly in the thickness of the conductive layer 21, wherein the second conductive layer 21.2, the third conductive layer 21.3, and the fourth conductive layer 21.4 are constructed to be significantly thicker. Furthermore, the optical thickness of the first dielectric layer sequence M1 (69.46 nm) and the optical thickness of the fifth dielectric layer sequence M5 (77.2 nm) are much smaller than those in the example according to the invention (85.52 nm for M1 and 102.4 nm for M5). Example 6 essentially corresponds to Example 5, wherein a low-refractive-index layer 27 is provided in the third dielectric layer sequence M3 instead of the second dielectric layer sequence M2.

[0082] The optical thickness of the layer is obtained as the product of the refractive index and the geometric layer thickness. The refractive indices of silicon nitride (SiN), tin oxide (ZnO), and tin-zinc mixed oxide (ZnSnO) are 2.0, the refractive index of silicon zirconium nitride (SiZrN) is 2.2, and the refractive index of silicon oxide (SiO) is 1.5.

[0083] The material of the layer can have dopants not given in the table. Thus, for example, a SnZnO-based layer can be doped with antimony and a ZnO, SiN, or SiZrN-based layer can be doped with aluminum.

[0084] Figure 5 The reflection spectra of the composite glass plate 10 according to Examples 1 to 6 and Comparative Example 1 of the invention are shown relative to p-polarized radiation. The spectra were measured at an incident angle of 65° on the interior space side, thus mimicking the reflection behavior for a HUD projector. The upper spectrum shows the spectral range of 350 nm to 800 nm, and the lower spectrum magnifies the spectral range of 400 nm to 700 nm. The two representations of the figure differ only in the scale of the vertical axis.

[0085] A comparison of Examples 1 to 4 with Comparative Example 1 makes it clear that, in particular, the thickness of the conductive layer 21 according to the invention results in a higher average reflectance and a smoother spectrum in the 450 nm to 650 nm spectral range relevant to HUD representation. This leads to a more intense and color-neutral representation of the HUD projection. The average reflectance can be further improved by the low-refractive-index layer 27 (Examples 5 and 6). Advantageously, the low-refractive-index layer 27 is arranged in layer sequence M2 (Example 5) – if the low-refractive-index layer is included in layer sequence M3 (Example 6), a similarly high average reflectance is achieved, but the spectrum is slightly rotlastig-rich. Authoritative observations are summarized in Table 3.

[0086] Table 3 The average reflectance relative to p-polarized radiation, 450 nm–650 nm The difference between the maximum reflectance and the average reflectance, 450 nm-650 nm The difference between the minimum reflectance and the average reflectance, 450 nm-650 nm Example 1 8.2% 2.5% 1.9% Example 2 7.8% 2.7% 2.0% Example 3 7.8% 2.3% 4.1% Example 4 8.2% 3.7% 4.2% Example 5 9.9% 1.8% 4.2% Example 6 13.7% 5.9% 9.9% Comparison Example 1 6.5% 6.4% 4.3% .

[0087] Tables 4 and 5 provide comparative examples based on Tables 1 and 2 and some physical parameters of the composite glass panel (example) according to the invention, which are commonly used by those skilled in the art and are generally considered for characterizing vehicle glass panels. Here, RL represents integrated light reflection and TL represents integrated light transmission (according to ISO 9050). The description following RL or TL describes the light source used, where A represents light source A and HUD represents a HUD projector with radiation wavelengths of 473 nm, 550 nm, and 630 nm (RGB). The angle description following the light type describes the angle of incidence of the radiation relative to the normal to the outer plane. Thus, an angle of incidence less than 90° indicates outer illumination, while an angle of incidence greater than 90° indicates inner space side illumination. The described angle of incidence of 115° corresponds to an angle of incidence of 65° (=180°-115°) relative to the normal to the inner space side plane and simulates illumination using the projector according to the invention. Below the reflectance values ​​are the corresponding color values ​​a* and b* in the L*a*b* color space, followed by a description of the light source used (HUD projector) and the viewing angle (the angle at which the light beam enters the eye and hits the retina).

[0088] The composite glass panel has sufficient total transmittance to be used as a windshield. The internal space-side reflection of the p-polarized HUD projector radiation is sufficiently high to ensure a strong HUD projection. Simultaneously, the reflected colors are relatively neutral, allowing the HUD projection to be reproduced in a color-neutral manner.

[0089] Table 4 Example 1 Example 2 Example 3 Example 4 Example 5 TL A 0° / % 71.6 71.3 71.2 71.3 71.2 RL HUD p-polarization 115° / % 8.3 7.8 7.9 8.1 9.9 a* (HUD / 10°) 5.5 1.6 -2.3 2.2 2.2 b* (HUD / 10°) -4.0 -3.7 -0.8 -4.0 -3.3 Surface resistance / Ω / square 0.9 0.9 0.9 0.9 0.9 .

[0090] Table 5 Comparison Example 1 Example 6 TL A 0° / % 71.7 64.3 RL HUD p-polarization 115° / % 5.7 16.3 a* (HUD / 10°) 8.2 2.4 b* (HUD / 10°) -12.6 27.5 Surface resistance / Ω / square 0.7 0.9 .

[0091] List of reference numerals in the attached diagram: (10) Composite glass plate (1) Outer glass panel (2) Inner glass plate (3) Thermoplastic interlayer (4) HUD projector (5) Observer / Vehicle driver (20) Conductive coating (M1), (M2), (M3), (M4), (M5) First, second, third, fourth, and fifth dielectric layer sequences (21) Conductive layer (21.1), (21.2), (21.3), (21.4) First, second, third, and fourth conductive layers (22) Anti-reflective layer (22.1), (22.2), (22.3), (22.4), (22.5) First, second, third, and fourth anti-reflective layers (22a) Dielectric layer of antireflective layer 4 (22a.3), (22a.4), (22a.5) First, second, and third dielectric layers (22b) Optical high-refractive-index layer of antireflective layer 4 (22b.3), (22b.4), (22b.5) First, second, and third optical high-refractive-index layers (23) Smoothing layer (23.1), (23.2), (23.3), (23.4) First, second, third, and fourth smoothing layers (24) First adaptation layer (24.1), (24.2), (24.3), (24.4) First, Second, Third, and Fourth First Adaptor Layers (25) Second adaptation layer (25.2), (25.3), (25.4), (25.5) First, second, third, and fourth second adaptation layers (26) Barrier layer (26.1), (26.2), (26.3), (26.4) First, second, third, and fourth barrier layers (27) Optical low-refractive layer (O) The upper edge of the composite glass plate 10 (U) The lower edge of the composite glass plate 10 (B) HUD area of ​​composite glass panel 10 (E) Eye movement range (I) The outer surface of the outer glass plate 1 (II) The internal space side surface of the outer glass panel 1 (III) The outer surface of the inner glass plate 2 (IV) The inner space side surface of the inner glass plate 2.

Claims

1. A projection device for a head-up display (HUD), the projection device comprising at least... - A composite glass panel (10) having a HUD area (B), the composite glass panel comprising an outer glass panel (1) and an inner glass panel (2), the outer glass panel and the inner glass panel being connected to each other via a thermoplastic interlayer (3); -A conductive coating (20) on the surface (II, III) of the outer glass plate (1) or the inner glass plate (2) facing the intermediate layer (3) or within the intermediate layer (3). and - HUD projector (4) aligned with the HUD area (B); The radiation from the projector (4) is p-polarized. The conductive coating (20) comprises at least the following components arranged in a given order, starting from the substrate: - First dielectric layer or layer sequence (M1). -Has a first conductive layer (21.1) with a thickness of 11 nm to 14 nm. - Second dielectric layer or layer sequence (M2). - It has a second conductive layer (21.2) with a thickness of 10 nm to 13 nm. - The third dielectric layer or layer sequence (M3). - It has a third conductive layer (21.3) with a thickness of 10 nm to 13 nm. - Fourth dielectric layer or layer sequence (M4). - It has a fourth conductive layer (21.4) with a thickness of 7 nm to 11 nm and - The fifth dielectric layer or layer sequence (M5). - The optical thickness of the first dielectric layer or layer sequence (M1) is 50 nm to 150 nm. - The optical thickness of the fifth dielectric layer or layer sequence (M5) is 50 nm to 150 nm.

2. The projection device according to claim 1, wherein the thickness of the first conductive layer (21.1) is greater than the thickness of the fourth conductive layer (21.4).

3. The projection device according to claim 2, wherein the thickness of the second conductive layer (21.2) and the third conductive layer (21.3) is greater than the thickness of the fourth conductive layer (21.4).

4. The projection device according to any one of claims 1 to 3, wherein - The thickness of the first conductive layer (21.1) is 11.5 nm to 13.5 nm. - The thickness of the second conductive layer (21.2) is 10 nm to 12.5 nm. - The thickness of the third conductive layer (21.3) is 11 nm to 12.5 nm, and - The thickness of the fourth conductive layer (21.4) is 7.5 nm to 10 nm.

5. The projection device according to any one of claims 1 to 3, wherein The surfaces (I, IV) of the outer glass plate (1) and the inner glass plate (2) that are opposite to the intermediate layer (3) are arranged substantially parallel to each other.

6. The projection device according to claim 5, wherein - The optical thickness of the first dielectric layer or layer sequence (M1) is 80 nm to 120 nm.

7. The projection device according to claim 5, wherein - The optical thickness of the first dielectric layer or layer sequence (M1) is 90 nm to 110 nm.

8. The projection device according to claim 5, wherein - The optical thickness of the fifth dielectric layer or layer sequence (M5) is 70 nm to 110 nm.

9. The projection device according to claim 5, wherein - The optical thickness of the fifth dielectric layer or layer sequence (M5) is 75 nm to 95 nm.

10. The projection device according to any one of claims 1 to 3, wherein all dielectric layers or layer sequences (M1, M2, M3, M4, M5) are constructed of dielectric layers having a refractive index greater than 1.

8.

11. The projection device according to any one of claims 1 to 3, wherein the second dielectric layer sequence (M2) comprises a dielectric optical low refractive index layer (27) having a refractive index of less than 1.8 and at least one dielectric layer having a refractive index of greater than 1.8, and wherein the remaining dielectric layers or layer sequences (M1, M3, M4, M5) are constructed of dielectric layers having a refractive index of greater than 1.

8.

12. The projection device according to claim 11, wherein the optical thickness of the low-refractive layer (27) is 20 nm to 40 nm.

13. The projection device according to claim 12, wherein the optical low-refractive layer (27) has an optical thickness of 25 nm to 35 nm.

14. The projection device according to claim 10, wherein the sum of the optical thicknesses of all layers having a refractive index greater than 1.8 in each of the second dielectric layer or layer sequence (M2), the third dielectric layer or layer sequence (M3), and the fourth dielectric layer or layer sequence (M4) is 100 nm to 200 nm.

15. The projection device of claim 14, wherein the sum of the optical thicknesses of all layers having a refractive index greater than 1.8 in each of the second dielectric layer or layer sequence (M2), the third dielectric layer or layer sequence (M3), and the fourth dielectric layer or layer sequence (M4) is 120 nm to 180 nm.

16. The projection device of claim 14, wherein the sum of the optical thicknesses of all layers having a refractive index greater than 1.8 in each of the second dielectric layer or layer sequence (M2), the third dielectric layer or layer sequence (M3), and the fourth dielectric layer or layer sequence (M4) is 150 nm to 170 nm.

17. The projection device according to any one of claims 1 to 3, wherein the composite glass plate (10) having a conductive coating (20) has an average reflectance coefficient of at least 5% relative to p-polarized radiation in a spectral range of 450 nm to 650 nm.

18. The projection device according to claim 17, wherein the composite glass plate (10) having a conductive coating (20) has an average reflectance coefficient of at least 7% relative to p-polarized radiation in the spectral range of 450 nm to 650 nm.

19. The projection apparatus according to any one of claims 1 to 3, wherein in the spectral range of 450 nm to 650 nm, the difference between the maximum occurrence of the reflection coefficient and the average value of the reflection coefficient relative to p-polarized radiation and the difference between the minimum occurrence of the reflection coefficient and the average value of the reflection coefficient are at most 5%.

20. The projection device according to any one of claims 1 to 3, wherein the conductive layer (21) is based on a silver structure.

21. The projection apparatus according to any one of claims 1 to 3, wherein the radiation of the projector (4) is substantially p-polarized.

22. The projection device according to any one of claims 1 to 3, wherein the cover (20) is equipped with two buses connected to a voltage source of 12V to 14V, so that current can be guided through the cover (20) to heat the composite glass plate (10).

23. The projection device according to any one of claims 1 to 22 is used as a HUD in a land, water or air vehicle.

24. The use according to claim 23, wherein the projection device is used as a HUD in a motor vehicle, rail vehicle, aircraft, or ship.

25. The use according to claim 23, wherein the projection device is used as a HUD in a passenger car or a truck.

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