Composite pane having holographic element and optically highly refractive layer

Abstract

The invention relates to a composite pane (100) comprising at least an outer pane (1) having an outer surface (I) and an inner surface (II), an inner pane (2) having an outer surface (III) and an inner surface (IV), a first intermediate layer (3), and a holographic element (4) having at least one hologram, the first intermediate layer (3) being arranged between the outer pane (1) and the inner pane (2), a holographic element (4) is arranged between the outer pane (1) and the first intermediate layer (3) or between the inner pane (2) and the first intermediate layer (3), and wherein an optically highly refractive layer (6) is arranged on the inner surface (IV) of the inner pane (2). The invention also relates to a projection device comprising such a composite pane, to a method for producing such a composite pane and to the use thereof.

Description

[0001] The invention relates to a composite glass pane having a holographic element and an optically high-refractive coating, a method for producing such a composite glass pane, and the use of such a composite glass pane.

[0002] Composite glass panels are currently used in many places, in particular in vehicle construction. In this context, the term "vehicle" includes in particular road vehicles, aircraft, ships, agricultural machinery or even construction equipment.

[0003] Composite glass panes are also used in other areas. These include, for example, architectural glazing or information displays, for example in museums or as advertising displays.

[0004] Composite glass panes are often also used as head-up displays (HUDs) to display information. In this case, an image is projected onto the composite glass pane by means of an imaging unit to display the information in the field of vision of a viewer. In the vehicle sector, the imaging unit is arranged, for example, on the dashboard so that the projected image is reflected in the direction of the viewer on the nearest glass surface of the composite glass pane which is tilted toward the viewer (see, for example, European patent EP 0420228 B1 or German patent application DE 102012211729 A1).

[0005] Head-up displays in which the projected image is reflected in the direction of the viewer on the nearest glass surface of the composite glass pane tilted towards the viewer are governed by the law of reflection, according to which the angle of incidence and the angle of reflection are equal in magnitude. The tilt angle of the composite glass pane cannot therefore be freely selected.

[0006] Holographic elements laminated between the glass sheets of a composite glass sheet can also be used for head-up displays. The holographic element has at least one hologram, and the hologram can contain information recorded therein. The hologram can be activated by light emitted by a projector, whereby the information recorded in the hologram is reproduced for the viewer. For example, head-up displays based on the holographic principle, so-called holographic head-up displays, are disclosed in the publications WO 2012 / 156124 A1, US 2019 / 0056596 A1, US 10,394,032 B2, US 10,061,069 B2 and US 2015 / 205138 A1.

[0007] DE 102020112447 A1 discloses a method for integrating a hologram into a rigid component having a predetermined surface target geometry using a hologram-receiving layer of a liquid photopolymer.

[0008] Holograms can be produced in a holographic material, i.e. a photosensitive material, laminated between the glass plates of a composite glass plate. To record a hologram, two mutually coherent light beams, a so-called reference beam (which can also be referred to as a reference wave) and a so-called object beam (which can also be referred to as an object wave), are directed onto the holographic material. The resulting interference pattern of the superimposed wavefronts is written into the holographic material as an alternating refractive index modulation. If the reference wave and the object wave have parallel wavefronts, the interference pattern corresponds to parallel gratings, the angles of whose lamellae are lower than the angular bisectors of the reference wave and the object wave. After recording, the holographic material is cured, thereby losing the ability to record further holograms. If the holographic material in which the hologram is recorded is irradiated again with a reference wave, the light is diffracted at the recording grating of the hologram so that the diffracted wave corresponds to the object wave. By irradiating the interference pattern written into the holographic material with a reference wave, the object wave can thereby be reconstructed.

[0009] Thus, a head-up display in which a projected image is reproduced in the direction of a viewer by means of a hologram enables the production of a composite glass pane with a laminated hologram, wherein the angle of incidence on the composite glass pane is not as great as the angle of reflection. Thus, for a holographic head-up display, the tilt angle of the composite glass pane can be selected more freely.

[0010] When producing composite glass panes with a hologram, it is advantageous to record the hologram in the holographic material of the holographic element precursor only after the lamination process, since the lamination process can have a negative impact on the optical properties of the recorded hologram. For example, EP 3461636 B1 discloses a method for producing a laminated holographic display, in which the hologram is recorded only after lamination.

[0011] However, recording a hologram in a holographic material of a holographic element precursor laminated between two glass plates is problematic because any change in the refractive index causes reflections of the object beam and the reference beam when the hologram is recorded. As a result, poor reflections on the surfaces of the two glass plates facing away from the holographic material lead to poor interference patterns and, therefore, to poor gratings recorded in the holographic material. These recorded poor gratings cause the hologram to exhibit poor artifacts when illuminated with a reference wave after the holographic material has been cured. Furthermore, the poor gratings recorded in the hologram can be activated from the outside by an external light source. This causes unnecessary interference and can cause glare to the viewer, which should therefore be minimized for safety reasons.

[0012] In the present application, the term "holographic element precursor" refers to a precursor of a holographic element. The holographic element precursor does not have a hologram. A holographic element is obtained by recording at least one hologram by applying an object beam and a reference beam to a holographic material of the holographic element precursor. The obtained holographic element differs from the holographic element precursor in that at least one hologram is recorded in the holographic element.

[0013] In WO 2021 / 087286 A1, a replication tool for producing a holographic film by replication is disclosed, and a method for producing a composite glazing using the replication tool is disclosed. During the replication process, an oil or gel with a matching refractive index can be arranged in the cavity between the laminated glazing and the main holographic film arrangement to reduce reflections during the replication process and improve the quality of the composite glazing.

[0014] US2019 / 101865 A1 discloses a method for producing a laminated holographic display, wherein a display precursor is first provided. The display precursor comprises a first glass layer, a second glass layer, an unexposed photopolymer film layer arranged between the first glass layer and the second glass layer, and a polymer layer arranged between the second glass layer and the unexposed photopolymer film layer.

[0015] WO 2022 / 053404 A1 discloses a method for producing a composite glass pane with a hologram, wherein a photosensitive material is applied as a holographic element in a coating area on the surface of a first glass pane, a hologram is formed in the holographic element by selective laser irradiation, and the first glass pane with the hologram is laminated with a second glass pane to form a composite glass pane.

[0016] WO 2021 / 209201 A1 discloses a projection device for a head-up display (HUD), comprising a composite glass pane having a HUD region and a HUD projector emitting p-polarized radiation. The composite glass pane comprises an outer glass pane and an inner glass pane joined together via an intermediate layer, wherein a highly refractive sol-gel coating having a refractive index of at least 1.7 is applied to the surface of the inner glass pane facing away from the intermediate layer.

[0017] EP 0536763 B1 discloses a composite glass panel integrated into a projection device, which contains a hologram, wherein a light beam emitted from a light source passes through a liquid crystal panel, projects the information displayed on the liquid crystal panel onto a mirror, and the information is reflected by the mirror onto the composite glass panel with the hologram. The light beam incident on the hologram is diffracted and reflected by the pattern of the holographic element, wherein the light beam resulting from the diffraction is emitted from the holographic element, hits the film of the windshield plate and is reflected by the latter in the direction of the driver and is perceived as an image. The hologram is therefore not introduced in the windshield plate itself, but in a further glass plate installed in the interior space of the vehicle.

[0018] In a head-up display in which the projected image is reproduced in the direction of the viewer by means of a hologram, the reflection of the reference wave on the outer surface of the outer glass pane is attenuated due to diffraction at the recording grating of the hologram; in particular, the reflection of the reference wave on the inner surface of the inner glass pane can appear as a weak but still disturbing ghost image. If the light emitted by the projector and incident on the composite glass pane at the Brewster (incident) angle is only p-polarized, the reflected portion of the light at the Brewster angle is close to zero. The Brewster angle is determined by the difference in refractive index between the two media. The refractive index of a conventional composite glass pane with a holographic medium is about 1.5. If the external medium is air with a refractive index of 1, as is usually the case, the Brewster angle is about 56°. If a minimum reflection is to be achieved, i.e. the incidence of the light is as close to the Brewster angle as possible, the freedom of arrangement of the projector (e.g. relative to the projection surface, i.e., for example, a windshield with HUD function) is greatly restricted.

[0019] The object of the invention is to provide an improved composite glass pane with a holographic element, in particular for head-up displays, wherein the inclination angle of the composite glass pane can be selected more freely, in particular to a greater inclination angle, while maintaining a good image quality, and at the same time the occurrence of undesirable ghost images and artifacts of the composite glass pane is minimized. Furthermore, the composite glass pane should be producible simply and inexpensively, even in industrial mass production.

[0020] The object of the invention is achieved by a composite glass pane according to independent claim 1. Preferred embodiments are evident from the dependent claims. A method for producing a composite glass pane according to the invention and its use are evident from the further independent claims.

[0021] The invention relates to a composite glass pane comprising at least an outer glass pane having an outer surface and an inner surface, an inner glass pane having an outer surface and an inner surface, a first intermediate layer and a holographic element having at least one hologram.

[0022] The composite glazing is a vehicle glazing, ie it is suitable for installation in a vehicle, wherein in the installed state the vehicle glazing separates the vehicle interior from the surroundings.

[0023] The outer glass pane, also referred to as the first glass pane, constitutes the glass pane of the composite glazing panel, which is adjacent to the vehicle environment in the installed state. The outer glass pane has an outer surface, also referred to as face I, which faces and is adjacent to the vehicle environment. The glass pane surface of the outer glass pane opposite to the outer surface of the outer glass pane is referred to as the inner surface of the outer glass pane, also referred to as face II, and faces the vehicle interior in the installed state of the glazing. The inner glass pane, also referred to as the second glass pane, constitutes the glass pane of the composite glazing panel, which faces the vehicle interior in the installed state in the vehicle. The inner glass pane has an outer surface, also referred to as face III, which faces the outer glass pane and the vehicle environment in the installed state. The glass pane surface of the inner glass pane opposite to the outer surface of the inner glass pane is referred to as the inner surface of the inner glass pane, also referred to as face IV, and is adjacent to the vehicle interior in the installed state.

[0024] The first interlayer is arranged between the outer glass pane and the inner glass pane, and the holographic element is arranged between the outer glass pane and the first interlayer or between the inner glass pane and the first interlayer. The first interlayer and the optional additional interlayers join the first glass pane and the second glass pane together.

[0025] According to the invention, exactly one optically high-refractive and preferably transparent layer is arranged on the inner surface (surface IV) of the inner glass pane. In the sense of the invention, "preferably transparent" means that the optically high-refractive layer is preferably transparent to light in the visible range of the spectrum from 380 nm to 780 nm. Particularly preferably, the optically high-refractive layer has a transmittance of at least 70% in the visible range of the spectrum. Such an optically high-refractive layer advantageously enables a freer selection of the tilt angle of the composite glass pane in the projection device, in particular enables it to be shifted towards a larger Brewster angle. This means that even in the case of steeper mounting positions of the composite glass pane (for example in the case of trucks or tractors), artifacts and ghost images caused by reflected parts of the light can be substantially avoided.

[0026] The optically high-refractive layer is also referred to below as an HI layer or HI coating, where HI stands for the term "high refractive index", i.e. high refraction. According to the invention, it is provided that exactly one HI layer is applied directly to the inner surface (inner side / face IV) of the inner pane. This is necessary at least in the region of the composite glass pane which is intended to serve as a projection surface in a projection device. The HI layer thus forms the outer surface of the composite glass pane according to the invention which faces the interior space.

[0027] According to the present invention, the optically high-refractive layer (HI layer) has a refractive index greater than or equal to 2.

[0028] In the present invention, the refractive index is in principle given relative to a wavelength of 550nm. The refractive index can be measured, for example, by ellipsometry. Ellipsometry is commercially available, for example from Sentech. The refractive index of the dielectric layer is preferably measured by first depositing it as a single layer on a substrate and then measuring the refractive index by ellipsometry. In order to measure the refractive index of a dielectric layer sequence, the layers of the layer sequence are each deposited separately on a substrate as a single layer, and the refractive index is then measured by ellipsometry. According to the present invention, for each of these single layers, a refractive index of at least 2 must be achieved. Dielectric layers having a refractive index of at least 2 and methods for depositing them are known to those skilled in the art in the thin layer field. Physical vapor deposition, in particular magnetron sputtering, is preferably used.

[0029] The composite glass pane is a vehicle glass pane. The holographic element is thus integrated directly into the vehicle glazing and no additional composite glass pane with a hologram is required in the beam path of the projector of the projection device. The composite glass pane is preferably a windshield pane in which the holographic element is directly integrated.

[0030] In a preferred embodiment, the HI coating on the inner surface of the inner glass pane is formed on the basis of silicon nitride, tin-zinc oxide, silicon-zirconium nitride, silicon-titanium nitride, silicon-hafnium nitride or titanium oxide, particularly preferably on the basis of silicon-zirconium nitride or titanium oxide (TiOx). These materials have proven to be particularly advantageous for increasing the Brewster angle.

[0031] The optically high-refractive layer having a refractive index greater than or equal to 2 is formed as a coating, preferably based on silicon nitride, zinc-tin oxide, silicon-zirconium nitride or titanium oxide (TiOx).

[0032] According to the invention, the phrase "formed on the basis of" means that the HI coating consists of or essentially consists of the above-mentioned material, apart from possible customary impurities or dopants. According to the invention, more than 95% by weight, preferably more than 97% by weight, for example 98% by weight of the HI layer is formed from this material. The above-mentioned material of the HI layer can be undoped or, for example, doped with a transition metal oxide such as ZnO, ZrO 2 and HfOx doping.

[0033] In one configuration of the present invention, the optically high-refractive layer is formed with a layer thickness of 10 nm to 100 nm, preferably 20 nm to 80 nm, particularly preferably 50 nm to 70 nm.

[0034] The outer glass pane and the inner glass pane each have an outer surface, i.e. the outer side surface, and an inner surface, i.e. the inner side surface, and a peripheral side edge extending between them. For the purposes of the present invention, an "outer surface" is understood to mean a main surface which is intended to face the external environment in the installed position. For the purposes of the present invention, the term "inner surface" is understood to mean a main surface which is intended to face the interior space in the installed position. In the composite glass pane according to the present invention, the inner surface of the outer glass pane and the outer surface of the inner glass pane face each other.

[0035] The surface of a glass sheet is usually represented as follows:

[0036] The outer surface of the outer glass sheet is referred to as face I. The inner surface of the outer glass sheet is referred to as face II. The outer surface of the inner glass sheet is referred to as face III. The inner surface of the inner glass sheet is referred to as face IV.

[0037] The composite glass pane is used in a vehicle window to separate an interior space from the exterior environment, wherein the "inner glass pane" for the present invention is the glass pane facing the interior space (vehicle interior space) and the outer glass pane is the glass pane facing the exterior environment.

[0038] A holographic element is a holographic medium in which a hologram is contained. A holographic element contains a light-sensitive material, i.e. a holographic material. By exposing it to a suitable light source, a hologram can be recorded therein. In the finished composite glass pane, the material of the holographic element is no longer light-sensitive, since the holographic material is altered during the process to such an extent that no further recording of a hologram is possible.

[0039] The holographic element comprises a holographic material and may additionally optionally comprise a first substrate layer and / or a second substrate layer. Suitable holographic materials are known to the person skilled in the art. Suitable first and second substrate layers are likewise known to the person skilled in the art.

[0040] Preferably, the holographic element contains photopolymers, dichromated gelatin or silver halide gelatin, photopolymers being particularly preferred as holographic material.

[0041] Silver halides or dichromates are usually used in a gelatin matrix, which is first dried, usually at room temperature, and then the hologram can be recorded by exposure to light.

[0042] In a first preferred embodiment, the holographic material is formed as a coating on the inner surface of the outer glass pane or as a coating on the outer surface of the inner glass pane.

[0043] The composite glass pane may additionally comprise a second interlayer.In a second preferred embodiment of the composite glass pane according to the invention, the holographic element is arranged between the first interlayer and the inner glass pane, and an additional second interlayer is arranged between the inner glass pane and the holographic element.

[0044] In a preferred embodiment, the holographic element comprises a holographic material, a first substrate layer and a second substrate layer, wherein the holographic material is arranged between the first intermediate layer and the inner glass pane, the second intermediate layer is arranged between the holographic material and the inner glass pane, the first substrate layer is arranged between the holographic material and the first intermediate layer, and the second substrate layer is arranged between the holographic material and the second intermediate layer. The holographic material is therefore arranged between the first substrate layer and the second substrate layer in this embodiment.

[0045] In another embodiment, a holographic element comprises a first substrate layer and a holographic material.

[0046] In this embodiment, the composite glass pane may also optionally comprise a second interlayer. When present, the second interlayer is arranged between the inner glass pane and the holographic element, and the first interlayer is arranged between the outer glass pane and the holographic element.

[0047] The interlayer may independently be a thermoplastic interlayer, an adhesive layer or an optically clear adhesive.

[0048] The first intermediate layer is preferably a thermoplastic intermediate layer, an adhesive layer or an optically clear adhesive (OCA).

[0049] The second intermediate layer is preferably a thermoplastic intermediate layer, an adhesive layer or an optically clear adhesive (OCA).

[0050] Optically clear adhesives (OCA) are characterized by high light transmittance, low haze, no birefringence, high UV resistance and good aging resistance. Uncontrolled and therefore undesirable impairment of light transmission or unsightly distortions can thus be avoided.

[0051] The adhesive layer preferably has an absorption in the visible spectral range of less than 5%, in particular less than 2% or even 1%, and preferably a haze of less than 5%, in particular less than 2% or even less than 1%.

[0052] The adhesive layer is preferably formed as a homogeneous layer.

[0053] The adhesive layer preferably has a thickness of 20 μm to 200 μm, particularly preferably 50 μm to 150 μm, very particularly preferably 60 μm to 100 μm. Good optical properties are thus achieved. In addition, adhesive layers with these thicknesses are commercially available as adhesive films. Alternatively, the adhesive of the adhesive layer can also be used as a liquid adhesive.

[0054] The adhesive of the adhesive layer is preferably a chemically active adhesive, in particular a chemically curing adhesive, or a UV-curing adhesive, particularly preferably an acrylate adhesive or a silicone-based adhesive.

[0055] The first substrate layer contains, for example, polyamide (PA), polycarbonate (PC), triacetyl cellulose (TAC) and / or polyethylene terephthalate (PET). The first substrate layer is, for example, 35 μm (micrometers) to 60 μm thick.

[0056] The second substrate layer contains, for example, polyamide (PA), polycarbonate (PC), triacetyl cellulose (TAC) and / or polyethylene terephthalate (PET). The second substrate layer is, for example, 35 μm (micrometers) to 60 μm thick.

[0057] The materials mentioned for the substrate layer are suitable for advantageously reducing or preventing diffusion of the plasticizer.

[0058] As mentioned above, in a preferred embodiment, the holographic material comprises a photopolymer. The photopolymer is, for example, 10 μm to 100 μm, for example 16 μm thick. Suitable photopolymers are known to those skilled in the art. The photopolymer preferably comprises a cross-linked polyurethane (PU). Alternatively, a liquid photopolymer may also be used.

[0059] In one embodiment, in the composite glass pane according to the invention, a UV protection layer is arranged between the outer glass pane and the holographic material. Such a UV protection layer prevents aging processes of the hologram recorded in the holographic material caused by UV radiation from the outside.

[0060] As is customary for window panes, the outer pane and the inner pane are made of glass, particularly preferably soda-lime glass. However, the outer pane and the inner pane can also be made of other types of glass, for example quartz glass, borosilicate glass or aluminosilicate glass, or hard transparent plastics, for example polycarbonate or polymethyl methacrylate. The outer pane and the inner pane can be transparent independently of one another or can also be tinted or dyed. The composite glass pane designed as a windshield must have a sufficient light transmittance in the central viewing area, preferably a light transmittance of at least 70% in the main viewing area A according to ECE-R43. The outer pane and the inner pane are preferably curved, i.e. they have a curvature.

[0061] The outer side (face III) of the outer pane and / or the inner pane can have suitable coatings known per se, for example non-stick coatings, scratch-resistant coatings on the outer side of the outer pane, heatable coatings, sun protection coatings or low-e coatings.

[0062] Preferably, the first intermediate layer or the second intermediate layer formed as a thermoplastic intermediate layer contains at least polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU) or a copolymer or derivative thereof, more preferably polyvinyl butyral (PVB), most preferably polyvinyl butyral (PVB) and additives known to those skilled in the art such as plasticizers, or consists of the same.

[0063] Preferably, the first intermediate layer or the second intermediate layer formed as a thermoplastic intermediate layer contains at least 60% by weight, particularly preferably at least 70% by weight, in particular at least 90% by weight, for example at least 97% by weight, of polyvinyl butyral.

[0064] The first intermediate layer formed as a thermoplastic intermediate layer may be formed from a single film or may also be formed from more than one film.

[0065] The second intermediate layer formed as a thermoplastic intermediate layer can likewise be formed from a single film or also from more than one film.

[0066] The first intermediate layer and, if present, the second intermediate layer, independently of one another, can also be functional intermediate layers, in particular intermediate layers with acoustic damping properties, intermediate layers reflecting infrared radiation, intermediate layers absorbing infrared radiation, intermediate layers absorbing ultraviolet radiation, intermediate layers that are at least partially dyed and / or intermediate layers that are at least partially colored. Thus, the first intermediate layer and, if present, the second intermediate layer, independently of one another, can also be, for example, bandpass filters.

[0067] The thickness of the first intermediate layer or the second intermediate layer formed as a thermoplastic intermediate layer is 30 μm to 1500 μm, preferably 50 μm to 780 μm, preferably 350 μm to 760 μm, and for example 380 μm or 760 μm.

[0068] The holographic element preferably has a thickness of 5 μm to 500 μm, preferably 10 μm to 200 μm, particularly preferably 15 μm to 150 μm.

[0069] The thickness of the outer pane and the inner pane can vary greatly and thus be adapted to the requirements of the individual case. The outer pane and the inner pane preferably have a thickness of 0.5 mm to 5 mm, particularly preferably 1 mm to 3 mm.

[0070] The composite glass pane according to the invention may contain one or more additional interlayers, in particular functional interlayers. The additional interlayer may in particular be an interlayer having sound damping properties, an interlayer reflecting infrared radiation, an interlayer absorbing infrared radiation, an at least partially dyed interlayer and / or an at least partially tinted interlayer. When a plurality of additional interlayers are present, they may also have different functions.

[0071] The composite glass pane according to the invention can further comprise a cover print, which is in particular made of a dark, preferably black enamel. The cover print is in particular a peripheral (i.e. frame-shaped) cover print. The peripheral cover print serves primarily as UV protection for the mounting adhesive of the composite glass pane. The cover print can be opaque and formed over the entire surface. The cover print can also be at least partially translucent, for example formed as a dot grid, a strip grid or a square grid. Alternatively, the cover print can also have a gradient - for example from an opaque cover to a translucent cover.

[0072] The holographic element preferably does not extend to the edge of the glass pane, while the first intermediate layer extends to the edge of the glass pane. In this embodiment, the holographic element in the composite glass pane is sealed at its peripheral edge by the first intermediate layer or a further layer arranged there and is thus protected from external influences such as moisture and cleaning agents. In addition, diffusion of plasticizers from the holographic element can be reduced or avoided.

[0073] Preferably, if the holographic element is not arranged on the entire surface of the glass plate, a barrier film with a hollowing out is arranged around the holographic element in a frame-like manner. The hollowing out corresponds to the area where the holographic element is arranged. The holographic element is arranged in this hollowing out and is completely filled. The barrier film is in the form of a peripheral frame and is in direct contact with the peripheral edge of the holographic element. The holographic element and the barrier film are therefore located in the same plane and are in contact with each other along their edges, wherein their contact surface is substantially orthogonal to the glass plate surface of the composite glass plate. In the composite glass plate according to the invention, the barrier film in the form of a peripheral frame compensates for the local thickness difference between the area with the holographic element and the surrounding area. According to the invention, the barrier film does not overlap with the holographic element, but is applied only in close proximity to the peripheral edge of the holographic element, thereby making it possible to compensate for the thickness difference. Therefore, the composite glass plate with a holographic element has not only improved aging resistance, but also improved durability due to the minimization of stress and glass breakage.

[0074] The barrier film is preferably a polymer layer, and preferably contains or essentially consists of polyvinyl butyral (PVB), polyethylene terephthalate (PET), polyamide (PA), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl chloride (PVC), triacetyl cellulose (TAC).

[0075] As is common in motor vehicle windows, the composite glass pane according to the invention is preferably curved in one or more spatial directions, with typical radii of curvature being from about 10 cm to about 40 m. However, the composite glass may also be flat - for example, if it is intended as a window pane for a bus, train or tractor.

[0076] The composite glass pane according to the invention has a top edge and a bottom edge and two side edges extending between the top edge and the bottom edge. The top edge is the edge that is to be facing upwards in the installed position. The bottom edge is the edge that is to be facing downwards in the installed position. The top edge is often also referred to as the top edge, while the bottom edge is often also referred to as the engine edge.

[0077] Composite glass panels designed as windshield panels have a central field of view, which places high demands on their optical quality. The central field of view must have a high light transmittance (usually greater than 70%). The central field of view is particularly what the person skilled in the art calls field of view B, field of view B or area B. Field of view B and its technical requirements are defined in Regulation No. 43 (ECE-R43 "Uniform provisions concerning the approval of safety glazing materials for vehicles and their installation") of the Economic Commission for the European Union (UN / ECE). Field of view B is defined in Annex 18.

[0078] The holographic element is advantageously arranged in the central field of view (field of view B) in the composite glass pane designed as a windshield. The holographic element can, but does not necessarily, cover the entire area and can also extend beyond this area. The holographic element preferably extends over at least 30% of the glass pane, particularly preferably over at least 50%, and even more preferably over at least 80%. Thus, a visible transition between the holographic element and a section of the visible area of ​​the glass pane without the holographic element can be avoided. Particularly preferably, the holographic element is arranged so that the peripheral edge of the holographic element is arranged in the area of ​​the opaque cover print. This has the advantage that the opaque cover print hides the transition from the holographic element to the surrounding layer. This cover print is usually located in the edge area of ​​the glass pane and prevents the mounting components or adhesive from being seen. The windshield pane usually has a surrounding peripheral cover print made of opaque enamel, which is particularly used to protect the adhesive used for mounting the windshield pane from UV radiation and visually hide it. This peripheral cover print is preferably also used to cover the peripheral edge of the holographic element. Preferably, both the outer pane and the inner pane of the composite glass pane have a cover print in order to block the see-through in the edge region from both sides.

[0079] The holographic element can also have recesses or holes - for example in the area of ​​so-called sensor windows or camera windows. These areas are intended to be equipped with sensors or cameras, and a holographic element in the beam path could impair their function.

[0080] The holographic element is preferably arranged over the entire width and the entire height of the composite glass pane, particularly preferably minus a peripheral edge region with a width of, for example, 5 mm to 50 mm. This protects the holographic element from contact with the surrounding atmosphere and corrosion. The width of the peripheral edge region can be constant or can vary.

[0081] The composite glass pane may be, for example, a windshield or roof pane of a vehicle, or other vehicle glazing, for example in a motor vehicle, rail vehicle or bus.

[0082] The invention also comprises a projection device for presenting information to a viewer, comprising at least a composite glass pane according to the invention and a projector, which is directed from the inside, i.e. from the interior of the vehicle, at the holographic element on face IV. The composite glass pane according to the invention can be formed as described above in various embodiments.

[0083] The projector of the projection device emits light having a wavelength to which the hologram (or holograms if more than one hologram is present) of the holographic element responds.

[0084] In the projection device according to the invention, undesirable reflections of the light emitted by the projector on the inner surface of the inner glass pane of the composite glass pane are minimized by the HI coating. Advantageously, the Brewster angle at which the reflected portion of the light is minimized - in particular close to zero for p-polarized light - can be shifted to a larger angle and selected more freely.

[0085] The invention also relates to a method for producing a composite glass pane, wherein at least:

[0086] a) providing an outer pane having an outer surface and an inner surface, a first intermediate layer, a holographic element having at least one hologram, and an inner pane having an outer surface and an inner surface and a HI coating applied to the inner surface,

[0087] b) forming a layer stack, wherein the first intermediate layer is arranged between the outer glass pane and the inner glass pane, and the holographic element is arranged between the outer glass pane and the first intermediate layer or between the inner glass pane and the first intermediate layer,

[0088] c) joining the layer stack by lamination.

[0089] As mentioned above, the holographic element may contain, for example, dichromated gelatin or silver halide gelatin or a photopolymer as the holographic material.

[0090] In the above-described embodiments of the method according to the invention, an optically high-refractive layer is applied to the inner surface of the inner glass pane prior to lamination.

[0091] Alternatively, it is also possible to apply the optically high-refractive coating to the inner surface (face IV) of the inner pane only after lamination, so that in step a) an uncoated inner pane is initially provided.

[0092] Therefore, according to the present invention, there is also provided a method for producing a composite glass pane, wherein at least:

[0093] a) providing an outer pane having an outer surface and an inner surface, a first intermediate layer, a holographic element having at least one hologram and an inner pane having an outer surface and an inner surface,

[0094] b) forming a layer stack, wherein the first intermediate layer is arranged between the outer glass pane and the inner glass pane, and the holographic element is arranged between the outer glass pane and the first intermediate layer or between the inner glass pane and the first intermediate layer,

[0095] c) joining the layer stack by lamination,

[0096] d) Applying an optically high refractive layer to the inner surface of the inner glass pane.

[0097] The application of the optically high-refractive layer to the inner surface of the inner pane can be achieved, for example, by methods established per se, such as wet coating, by magnetron sputtering or by chemical (CVD) or physical vapor deposition (PVD).

[0098] Advantageously, such a coating can be incorporated into the industrial series production of composite glass panes without difficulty and at low cost.

[0099] It is to be understood that in step a), instead of a holographic element in which at least one hologram is recorded, an unexposed holographic element precursor made of a photosensitive material may in each case be provided alternatively. Thus, the formation of the layer stack may also be carried out in step b), and the lamination with the unexposed holographic element precursor or with the final holographic element with the recorded hologram may be carried out in step c). It is to be understood that when an unexposed holographic element precursor is provided in step a), the method according to the invention comprises recording at least one hologram in the holographic element precursor as an additional step after the lamination of the layer stack.

[0100] The layer stack is preferably laminated under the effect of heat, vacuum and / or pressure. It is possible to use lamination methods known per se, such as the autoclave method, the vacuum bag method, the vacuum ring method, the calendaring method, a vacuum laminator or a combination thereof.

[0101] If the composite glass pane is to be bent, the outer and inner glass panes are preferably subjected to a bending process before lamination. Preferably, the outer and inner glass panes are bent together congruently (i.e., simultaneously and by the same tool), as this allows the shape of the glass panes to be optimally matched to the lamination that is subsequently performed. Typical temperatures for the glass bending process are, for example, 500° C. to 700° C.

[0102] Any opaque cover print present, ie, in particular a peripheral black print in the edge region of the glass pane, is preferably applied by screen printing.

[0103] In one design, the cover print in the edge region of the composite glass pane can also be provided on the inner side of the inner glass pane. Such a cover print can also advantageously prevent the mounting components, wires or adhesive bonds from being visible from the interior space, thus contributing to a more visually attractive appearance of the composite glass pane and also improving the adhesive bonds or protecting them from UV light. The cover print can be applied directly to the inner side of the inner glass pane. In this case, no HI coating is applied to face IV in this edge region. Alternatively, however, the cover print in the edge region can also be formed on the HI coating so that the HI layer substantially covers the entire surface of the inner surface of the inner glass pane.

[0104] The embodiments described above with respect to the composite glass pane according to the invention also apply in the same manner to the method according to the invention, and vice versa.

[0105] The invention further comprises the use of a composite glass pane according to the invention having at least one hologram as a vehicle glass pane in land, air or water vehicles, in particular in motor vehicles, in particular as a windshield pane serving as a projection surface for a head-up display.

[0106] The invention is explained in more detail with reference to the accompanying drawings and examples. The accompanying drawings are schematic diagrams and are not drawn to scale. The accompanying drawings do not limit the invention in any way. In the accompanying drawings:

[0107] Figure 1 A plan view showing a composite glass panel 100 according to the present invention is shown.

[0108] Figure 2 Show Through Figure 1 A cross section of a design of a composite glass pane 100 according to the invention is shown in;

[0109] Figure 3 shows a cross section through another design of a composite glass pane 100 according to the invention,

[0110] Figure 4 shows a cross section through another design of a composite glass pane 100 according to the invention,

[0111] Figure 5 showing a cross section of one embodiment of a holographic element,

[0112] Figure 6 A cross section showing another embodiment of a holographic element,

[0113] Figure 7 A cross section showing another embodiment of a holographic element, and

[0114] Figure 8 An embodiment of the method according to the invention is shown using a flow chart.

[0115] Figure 1 A plan view showing a composite glass panel 100 according to the present invention is shown. Figure 2 Display along the cutting line X-X' through Figure 1 The cross section of the design of the composite glass pane 100 according to the invention is shown in FIG. Figure 1 In the embodiment shown in FIG. 1 , the composite glass pane 100 has a top edge O, a bottom edge U and two side edges S. In the embodiment shown in FIG.

[0116] like Figure 2 As shown in FIG. 1 , the composite glass pane 100 comprises an outer glass pane 1 having an outer surface I and an inner surface II, a first intermediate layer 3, a holographic element 4, an inner glass pane 2 having an outer surface III and an inner surface IV, and a HI coating 6. Figure 1 and 2 In the embodiment shown in , the holographic element 4 is arranged on the entire surface between the outer glass plate 1 and the inner glass plate 2, the first intermediate layer 3 is arranged on the entire surface between the outer glass plate 1 and the holographic element 4, and the HI coating 6 is arranged on the entire surface of the inner surface IV of the inner glass plate 2. According to the invention, the HI coating 6 is preferably formed on the basis of silicon nitride, tin-zinc oxide, silicon-zirconium nitride, silicon-titanium nitride, silicon-hafnium nitride or titanium oxide, particularly preferably on the basis of silicon-zirconium nitride or titanium oxide (TiOx). The HI layer 6 is formed, for example, with a layer thickness of 20 nm to 80 nm, particularly preferably 50 nm to 70 nm.

[0117] The outer glass pane 1 consists, for example, of soda-lime glass and is 2.1 mm thick. The inner glass pane 2 consists, for example, of soda-lime glass and is 1.6 mm thick. Figure 1 and 2 In the embodiment shown in , the first intermediate layer 3 is, for example, a thermoplastic intermediate layer which, for example, consists of polyvinyl butyral (PVB) and is 0.76 mm thick.

[0118] exist Figure 1 and 2 In the embodiment shown in FIG. , the holographic element 4 is, for example, Figure 5 or as shown in 7. If the holographic element 4 is as Figure 7 , the holographic element 4 is preferably arranged such that the first substrate layer 8 is arranged directly adjacent to the first intermediate layer 3 .

[0119] Figure 3 A cross section is shown of another embodiment of a composite glass pane 100 according to the invention. Figure 3 The composite glass pane 100 shown in cross section in FIG. Figure 2 The composite glass pane shown in FIG. 4 differs only in that a first intermediate layer 3 is arranged between the inner glass pane 2 and the holographic element 4 .

[0120] exist Figure 3 In the embodiment shown in FIG. , the holographic element 4 is, for example, Figure 5 or as shown in 7. If the holographic element 4 is as Figure 7 , the holographic element 4 is preferably arranged such that the first substrate layer 8 is arranged directly adjacent to the first intermediate layer 3 .

[0121] Figure 4 A cross section is shown of another embodiment of a composite glass pane 100 according to the invention. Figure 4 The composite glass pane 100 shown in cross section in FIG. Figure 2 The composite glass pane shown in FIG. 1 differs in that a second intermediate layer 7 is arranged between the holographic element 4 and the inner glass pane 2. The second intermediate layer 7 is, for example, a thermoplastic intermediate layer and consists, for example, of polyvinyl butyral (PVB) and is 0.76 mm thick.

[0122] exist Figure 4 In the embodiment shown in FIG. , the holographic element 4 is, for example, Figure 5 , 6 Or as shown in 7.

[0123] Figure 5 A cross section of one embodiment of a holographic element 4 is shown. Figure 5 In the embodiment shown in FIG, the holographic element 4 consists of a holographic material 5. The holographic material 5 is, for example, a photopolymer, dichromated gelatin or silver halide gelatin.

[0124] Figure 6 A cross section of another embodiment of a holographic element 4 is shown. Figure 6 In the embodiment shown in , the holographic element 4 comprises a first substrate layer 8, a second substrate layer 9 and arranged between them a holographic material 5. The holographic material 5 is, for example, a photopolymer, dichromated gelatin or silver halide gelatin.

[0125] Figure 7 A cross section of another embodiment of a holographic element 4 is shown. Figure 7 In the embodiment shown in FIG. 4 , the holographic element 4 comprises a first substrate layer 8 and a holographic material 5. The holographic material 5 is, for example, a photopolymer, dichromated gelatin or silver halide gelatin.

[0126] Figure 8 An embodiment of the method according to the invention for producing a composite glass pane 100 according to the invention is shown using a flow chart, which comprises the steps:

[0127] S1 provides an outer glass pane 1 having an outer surface I and an inner surface II, a first intermediate layer 3, a holographic element 4 having at least one hologram, and an inner glass pane 2 having an outer surface III and an inner surface IV and an optically high-refractive layer 6 applied to said inner surface IV,

[0128] S2 forms a layer stack, wherein the first intermediate layer 3 is arranged between the outer glass sheet 1 and the inner glass sheet 2, and the holographic element 4 is arranged between the outer glass sheet 1 and the first intermediate layer 3 or between the inner glass sheet 2 and the first intermediate layer 3,

[0129] S3 joins the layer stack by lamination.

[0130] According to the invention, exactly one optically highly refractive and preferably transparent layer is arranged on the inner surface (surface IV) of the inner glass pane. Such an optically highly refractive layer provided according to the invention advantageously enables a freer selection of the tilt angle of the composite glass pane in the holographic head-up display projection device, in particular enables a shift towards a larger Brewster angle. This means that even in the case of steeper installation positions of the composite glass pane (for example in the case of trucks or tractors), HUD functions can be realized and at the same time artifacts and ghost images caused by reflected parts of the light can be substantially avoided.

[0131] List of reference numerals:

[0132] 100 composite glass panel

[0133] 1 outer glass panel

[0134] 2 inner glass panels

[0135] 3First intermediate layer

[0136] 4Holographic elements

[0137] 5. Holographic Materials

[0138] 6HI ​​coating (optical high refractive layer)

[0139] 7 Second middle layer

[0140] 8First base layer

[0141] 9 Second base layer

[0142] I. The outer surface of the outer glass plate 1

[0143] II Inner surface of outer glass plate 1

[0144] III. The outer surface of the inner glass plate 2

[0145] IV Inner surface of inner glass plate 2

[0146] O Top edge

[0147] U bottom edge

[0148] S side edge

[0149] X-X' cutting line

Claims

1. A composite glass plate (100), comprising at least - an outer glass pane (1) having an outer surface (I) and an inner surface (II), - an inner glass pane (2) having an outer surface (III) and an inner surface (IV), - a first intermediate layer (3), and - a holographic element (4) having at least one hologram, wherein the first intermediate layer (3) is arranged between the outer glass plate (1) and the inner glass plate (2), and the holographic element (4) is arranged between the outer glass plate (1) and the first intermediate layer (3) or between the inner glass plate (2) and the first intermediate layer (3), wherein the composite glass panel (100) is a vehicle glass panel, And wherein an optically high refractive layer (6) having a refractive index greater than or equal to 2 is arranged on the inner surface (IV) of the inner glass sheet (2).

2. The composite glass pane (100) according to claim 1, wherein the composite glass pane (100) is a windshield pane.

3. The composite glass pane (100) according to claim 1 or 2, wherein the optically high-refractive layer (6) is formed based on silicon nitride, tin-zinc oxide, silicon-zirconium nitride, silicon-titanium nitride, silicon-hafnium nitride or titanium oxide, preferably based on silicon-zirconium nitride or titanium oxide.

4. The composite glass pane (100) according to any one of claims 1 to 3, wherein the optically high-refractive layer (6) is formed with a layer thickness of 10 nm to 100 nm, preferably 20 nm to 80 nm, particularly preferably 50 nm to 70 nm.

5. The composite glass pane (100) according to any one of claims 1 to 4, wherein the holographic element (4) contains a holographic material (5), and the holographic material (5) is formed as a coating on the inner surface (II) of the outer glass pane (1) or as a coating on the outer surface (III) of the inner glass pane (2).

6. The composite glass pane (100) according to any one of claims 1 to 4, wherein the holographic element (4) is arranged between a first intermediate layer (3) and an inner glass pane (2), and the composite glass pane (100) further comprises a second intermediate layer (7) arranged between the inner glass pane (2) and the holographic element (4).

7. A composite glass pane (100) according to any one of claims 1 to 6, wherein the first intermediate layer (3), and / or if a second intermediate layer (7) is arranged between the inner glass pane (2) and the holographic element (4), the second intermediate layer (7), independently of each other, is a thermoplastic intermediate layer, an adhesive layer or an optically transparent adhesive.

8. The composite glass pane (100) according to any one of claims 1 to 7, wherein the holographic element (4) comprises a holographic material (5) and a first substrate layer (8) and / or a second substrate layer (9).

9. The composite glass pane (100) according to claim 1, wherein the holographic element (4) contains a photopolymer, dichromated gelatin or silver halide gelatin as holographic material (5).

10. The composite glass pane (100) according to claim 8 or 9, wherein the holographic element (4) comprises a holographic material (5), a first substrate layer (8) and a second substrate layer (9), wherein the first substrate layer (8) is arranged between the holographic material (5) and the first intermediate layer (3), and the second substrate layer (9) is arranged between the holographic material (5) and the second intermediate layer (7).

11. The composite glass pane (100) according to any one of claims 8 to 10, wherein the first substrate layer (8) and / or the second substrate layer (9) comprises polyamide, cellulose triacetate and / or polyethylene terephthalate.

12. A projection device comprising a composite glass pane (100) according to any one of claims 1 to 11 and a projector, the projector being directed toward the holographic element (4) from the side of the inner glass pane (2).

13. A method for producing a composite glass panel (100) according to any one of claims 1 to 11, wherein at least: a) providing an outer glass pane (1) having an outer surface (I) and an inner surface (II), a first intermediate layer (3), a holographic element (4) having at least one hologram, and an inner glass pane (2) having an outer surface (III) and an inner surface (IV) and a transparent optically high-refractive layer (6) applied to the inner surface (IV), b) forming a layer stack, wherein the first intermediate layer (3) is arranged between the outer glass pane (1) and the inner glass pane (2), and the holographic element (4) is arranged between the outer glass pane (1) and the first intermediate layer (3) or between the inner glass pane (2) and the first intermediate layer (3), c) joining the layer stack by lamination.

14. Method for producing a composite glass pane (100) according to claim 13, wherein the optically high-refractive layer (6) is applied to the inner surface (III) of the inner glass pane (2) by wet coating, by magnetron sputtering or by chemical or physical vapor deposition.

15. Use of the composite glass pane (100) according to any one of claims 1 to 11 as a vehicle glass pane in a land, air or water vehicle, in particular in a motor vehicle, in particular as a windshield pane serving as a projection surface for a head-up display.

Images