Composite pane with holographic elements

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 a UV protective layer (6) is arranged on the inner surface (II) of the outer pane (1). 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 a UV protection coating, a method for producing such a composite glass pane and the use thereof.

[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] 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 angle is only p-polarized, the reflected portion of the light at the Brewster angle is close to zero.

[0015] Holographic materials for holographic HUD applications, for example for windshield panels in vehicles, can be photopolymers (PP) or gels. Such photosensitive materials are commercially available. It is known that incident light, especially in the UV spectrum, can significantly affect the physical properties of such photosensitive materials of holographic films over time. The typical service life and durability of windshield panels is about 7 to 12 years, 2 to 4 years in the truck sector. The aging effects observed within such a period relate in particular to changes in the color (discoloration), mechanical and physical properties, dimensions and even holographic properties of these films.

[0016] WO 2021 / 091818 A1 discloses a composite glass pane which provides an interlayer with UV-absorbing particles between the outer glass pane and the holographic medium to protect the holographic medium from UV light. The second interlayer remains free of UV-absorbing particles to enable UV curing of the photosensitive polymer. After full curing and lamination to form the composite glass pane, a UV-absorbing coating is applied to the inner side (face IV) of the inner glass pane.

[0017] WO 2021 / 219285 A1 describes a vehicle glazing comprising an electroluminescent device which emits light and an optical band-stop filter which significantly reduces the radiation of the electroluminescent device in one emission direction. In this way, light is prevented from being emitted in an unwanted emission direction. The band-stop filter is designed as a thin-layer coating comprising an optically high-refractive layer with a refractive index greater than 1.8 and an optically low-refractive layer with a refractive index less than 1.8.

[0018] WO 2021 / 041635 A1 discloses a method for producing glazing, wherein a first glass pane, a first interlayer, a photopolymer film, a second interlayer and a second glass pane are laminated together and the photopolymer film is subsequently exposed. Optionally, the glazing comprises an infrared-reflecting layer, which in turn may optionally also be at least partially reflective in other wavelength ranges, such as the UV range.

[0019] US 2022 / 0176682 A1 discloses an interlayer for a composite glass pane, which comprises a holographic element and a first thermoplastic interlayer, wherein the first thermoplastic interlayer contains a UV absorber.

[0020] The object of the invention is to provide an improved composite glass pane with a holographic element, in particular for head-up displays, in which the holographic element can have, in particular, an improved durability and service life. In particular, aging processes such as deterioration of properties, in particular holographic properties, or color changes in the visible spectrum should be avoided or at least significantly delayed in time. Furthermore, the composite glass pane with a holographic HUD should be producible simply and cost-effectively even in industrial series production.

[0021] 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.

[0022] 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.

[0023] A 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.

[0024] According to the invention, a UV protective layer is applied to the inner surface (surface II) of the outer glass pane at least in the region of the holographic element. In the region of the holographic element, this means that the projection of the holographic element in the plane of the UV protective layer overlaps the UV protective layer in terms of area. In the perspective through the composite glass pane, the UV protective layer is therefore located between the outer glass pane and the holographic element, so that the UV radiation that passes through the outer glass pane and impinges on the holographic element first passes through the UV protective layer. The UV protective layer is also called a UV protective coating, i.e., it is applied directly to the inner surface (surface II) of the outer glass pane in the form of a coating. The UV protective layer applied to the surface II of the outer glass pane can therefore advantageously prevent or at least substantially avoid aging processes and changes in the material properties of the holographic element caused by UV radiation in sunlight from the outside, or can delay them beyond the typical service life of the composite glass pane. In particular, changes in the photosensitive material caused by the incident sunlight, in particular the UV light part, and the associated changes and degradation of the hologram recorded in the holographic material can be effectively prevented or at least substantially avoided. Therefore, the durability of the composite glass pane of constant quality with a holographic HUD function can be advantageously significantly extended.

[0025] The outer pane, also referred to as the first pane, constitutes the pane of glass of the composite glazing which, in the installed state, adjoins the external environment. The outer pane has an outer surface, also referred to as face I, which faces and adjoins the vehicle surroundings. The pane surface of the outer pane opposite to the outer surface of the outer pane is referred to as the inner surface of the outer pane, also referred to as face II, and in the installed state of the glazing faces the interior. The inner pane, also referred to as the second pane, constitutes the pane of glass of the composite glazing which, in the installed state in the vehicle, faces the interior. The inner pane has an outer surface, also referred to as face III, which, in the installed state, faces the outer pane and the surroundings. The pane surface of the inner pane opposite to the outer surface of the inner pane is referred to as the inner surface of the inner pane, also referred to as face IV, and in the installed state faces the interior.

[0026] The composite glazing is preferably a vehicle glazing, ie it is suitable for installation in a vehicle, wherein the vehicle glazing in the installed state separates the vehicle interior from the vehicle environment.

[0027] In one embodiment, the UV protection layer is formed of a UV light reflecting and / or UV light absorbing material.

[0028] In a preferred embodiment, the UV protection layer comprises at least one layer of an optically high-refractive material, which preferably has a refractive index greater than or equal to 1.8, particularly preferably greater than or equal to 1.9, in particular greater than or equal to 2.

[0029] In a preferred embodiment, the UV protection layer is preferably an optically high-refractive layer, in particular having a refractive index of greater than 1.8, which is designed as a coating, particularly preferably based on silicon nitride, zinc-tin oxide, silicon-zirconium nitride or titanium oxide (TiOx).

[0030] According to the invention, the optically high-refractive layer can be formed, for example, on the basis of titanium dioxide, silicon nitride, tin-zinc oxide, silicon-zirconium nitride, silicon-titanium nitride or silicon-hafnium nitride.

[0031] If a layer is formed on the basis of a material, it consists predominantly of this material, in particular essentially of this material, apart from possible impurities or dopings. For example, the UV protection layer can be formed to an extent of more than 95% by weight (of the UV protection layer), preferably more than 97% by weight, for example 98% by weight or more, of the mentioned material.

[0032] These high-refractive layers can be formed preferably with a thickness of 10 nm to 100 nm, particularly preferably with a thickness of 20 nm to 50 nm.

[0033] In another design, the UV protection layer is multi-layered and comprises at least one layer of an optically high refractive material and at least one layer of an optically low refractive material.

[0034] In a further preferred embodiment, it is provided that the multilayer UV protective layer comprises at least two layers (sublayers) of a high-refractive material, which are preferably separated from one another by layers of an optically low-refractive material.

[0035] According to the present invention, the UV protective coating can be formed by layers with different refractive indices arranged alternately. The multilayer UV protective coating preferably comprises at least two optically high refractive layers, which particularly have a refractive index greater than 1.8, and at least one optically low refractive layer, which particularly has a refractive index less than 1.8, for example, less than 1.6. Starting from the inner surface of the outer glass plate, first the first high refractive layer, the first low refractive layer thereon, and the second high refractive layer thereon are preferably superimposed on each other over the entire surface. Such an embodiment has proven to be particularly advantageous in terms of the UV protective effect of the coating. The high refractive layer can be formed, for example, based on silicon nitride, zinc-tin oxide, silicon-zirconium nitride or titanium oxide; the low refractive layer can be formed, for example, based on silicon dioxide or magnesium fluoride. The material of the optically high refractive layer (sublayer) of the UV protective layer and the material of the low refractive layer (sublayer) can be, for example, doped with other transition metal oxides, such as ZnO, ZrO2, HfOx.

[0036] In the present invention, the refractive index is in principle given relative to a wavelength of 550 nm. 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 monolayer on a substrate and then measuring the refractive index by ellipsometry. Dielectric layers with said refractive index and methods for depositing them are known to those skilled in the art in the field of thin layers. Preferably, physical vapor deposition, in particular magnetron sputtering, or wet coating is used.

[0037] For example, the optically low refractive layer made of silicon dioxide or magnesium fluoride may be preferably formed in a thickness of 10 nm to 100 nm, particularly preferably in a thickness of 20 nm to 50 nm.

[0038] In an exemplary embodiment, the UV protective coating, starting from the inner surface of the outer glass plate, is formed into a three-layer UV protective layer of a 35 nm thick titanium dioxide layer, a 35 nm thick silicon dioxide layer disposed thereon, and a 30 nm thick titanium dioxide layer disposed thereon.

[0039] In one embodiment, the single-layer or multi-layer UV protection layer is formed with a layer thickness of 10 nm to 200 nm, preferably 20 nm to 100 nm, particularly preferably 30 nm to 80 nm.

[0040] In another embodiment of the composite glass pane according to the invention, the single-layer or multi-layer UV protective coating is formed from a UV light absorbing material or contains such a material. Known examples suitable for the invention are organic layers, which are based, for example, on benzotriazole (for example, available under the trade name Available from BASF), triazines or benzophenones or a combination thereof.

[0041] According to the present invention, such an organic UV protection layer is preferably formed with a thickness of 1 μm to 100 μm, for example, with a thickness of 10 μm to 80 μm, for example, with 20 μm, 40 μm, 50 μm or 60 μm.

[0042] 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.

[0043] The surface of a glass sheet is usually represented as follows:

[0044] 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.

[0045] If the composite glass pane is used in a window of a vehicle or a building to separate an interior from the exterior environment, the "inner glass pane" for the purposes of the invention is the glass pane facing the interior (vehicle interior). The outer glass pane is the glass pane facing the exterior environment.

[0046] 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.

[0047] 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.

[0048] Preferably, the holographic element contains photopolymers, dichromated gelatin or silver halide gelatin, photopolymers being particularly preferred as holographic material.

[0049] 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.

[0050] In one embodiment, the holographic material is formed as a coating on the inner surface of the outer glass sheet or as a coating on the outer surface of the inner glass sheet.

[0051] The composite glass pane may additionally comprise a second interlayer.In this 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 the additional second interlayer is arranged between the inner glass pane and the holographic element.

[0052] 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.

[0053] In another embodiment, a holographic element comprises a first substrate layer and a holographic material.

[0054] 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.

[0055] The first intermediate layer is preferably a thermoplastic intermediate layer, an adhesive layer or an optically clear adhesive (OCA).

[0056] The second intermediate layer is preferably a thermoplastic intermediate layer, an adhesive layer or an optically clear adhesive (OCA).

[0057] 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.

[0058] 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%.

[0059] The adhesive layer is preferably formed as a homogeneous layer.

[0060] 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.

[0061] 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.

[0062] The first substrate layer contains, for example, polyamide (PA), triacetyl cellulose (TAC) and / or polyethylene terephthalate (PET). The first substrate layer is, for example, 35 μm (micrometers) to 60 μm thick.

[0063] The second substrate layer contains, for example, polyamide (PA), cellulose triacetate (TAC) and / or polyethylene terephthalate (PET). The second substrate layer is, for example, 35 μm (micrometers) to 60 μm thick.

[0064] 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.

[0065] 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.

[0066] The outer pane and / or the inner pane may have other suitable coatings known per se, for example a non-stick coating, a scratch-resistant coating, a heatable coating, a sun protection coating or a low-E coating.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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 UV radiation, intermediate layers at least partially dyed and / or intermediate layers at least partially tinted. Thus, the first intermediate layer and, if present, the second intermediate layer, independently of one another, can also be, for example, bandpass filters. The mentioned embodiments of the intermediate layer are designed independently of the other features of the composite glass pane. Thus, the optionally present UV radiation absorbing function of the intermediate layer is in each case provided in addition to the UV protective layer of the outer glass pane, but not instead of it.

[0072] 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 800 μm, and for example 380 μm or 760 μm.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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 other layers arranged there and is thus protected from external influences, such as moisture and cleaning agents.

[0078] 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.

[0079] 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).

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] The composite glass pane can be, for example, a windshield or roof pane of a vehicle, or other vehicle glazing, such as a partition glass in a vehicle, preferably a rail vehicle or a bus. Alternatively, the composite glass pane can be an architectural glazing, such as in the facade of a building, or a partition glass in a building interior.

[0087] 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 at the holographic element.The composite glass pane according to the invention can be formed as described above in various embodiments.

[0088] 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.

[0089] The invention also relates to a method for producing a composite glass pane, wherein at least:

[0090] a) providing an outer glass pane having an outer surface and an inner surface, wherein a UV protection layer is formed on the inner surface of the outer glass pane; a first intermediate layer, a holographic element having at least one hologram, and an inner glass pane having an outer surface and an inner surface,

[0091] 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,

[0092] c) joining the layer stack by lamination.

[0093] As mentioned above, the holographic element may contain, for example, dichromated gelatin or silver halide gelatin or a photopolymer as the holographic material.

[0094] 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.

[0095] The application of the UV protection layer to the inner surface of the outer glass pane can be achieved, for example, by methods established per se, such as wet coating, by magnetron sputtering or by chemical vapor deposition (CVD) or physical vapor deposition (PVD).

[0096] Advantageously, such a coating can be incorporated into the industrial series production of composite glass panes without difficulty and at low cost.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] Any opaque cover print present, ie, a peripheral black print in particular in the edge region of the glass pane, is preferably applied by screen printing.

[0101] 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.

[0102] The invention further comprises the use of a composite glass pane according to the invention having at least one hologram as interior or exterior glazing of a vehicle or a building, in particular as a vehicle glazing 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.

[0103] 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:

[0104] Figure 1 A plan view showing a composite glass panel 100 according to the present invention is shown.

[0105] 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;

[0106] Figure 3 shows a cross section through another design of a composite glass pane 100 according to the invention,

[0107] Figure 4 shows a cross section through another design of a composite glass pane 100 according to the invention,

[0108] Figure 5 showing a cross section of one embodiment of a holographic element,

[0109] Figure 6 A cross section showing another embodiment of a holographic element,

[0110] Figure 7 A cross section showing another embodiment of a holographic element,

[0111] Figure 8 shows a cross section of one embodiment of a multilayer UV protection layer according to the invention,

[0112] Fig. 9 An embodiment of the method according to the invention is shown using a flow chart.

[0113] Figure 1 A plan view showing a composite glass panel 100 according to the present invention is shown. Figure 2Display 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, the composite glass panel 100 has a top edge O, a bottom edge U and two side edges S. Figure 2 As shown in FIG. 1 , a 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 UV protection layer 6, which is preferably applied as a coating on the entire inner surface II of the outer glass pane 1. Thus, the UV protection layer can filter or resist harmful UV light from incident sunlight and protect the holographic element. Aging processes induced by the UV light portion of the incident sunlight and thus changes in the properties and appearance of the composite glass pane 100, in particular the holographic element 4, can be avoided or at least delayed. Thus, the durability and service life of a composite glass pane with a holographic element of constant good quality having a holographic HUD function can be significantly improved.

[0114] exist 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 UV protective layer 6 is applied as a coating on the entire surface of the inner surface II of the outer glass plate 1.

[0115] 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.

[0116] exist Figure 1 and 2 In the embodiment shown in , the first intermediate layer 3 is, for example, a thermoplastic intermediate layer and consists, for example, of polyvinyl butyral (PVB) and is 0.76 mm thick.

[0117] 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 .

[0118] 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 .

[0119] 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 .

[0120] 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.

[0121] exist Figure 4 In the embodiment shown in FIG. , the holographic element 4 is, for example, Figure 5 , 6 Or as shown in 7.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] Figure 8 A cross section of one embodiment of a multi-layer UV protection layer 6 is shown. Figure 8In the embodiment shown in , the three-layer UV protective layer includes a first and a second optically high-refractive layer 6a and an optically low-refractive layer 6b arranged therebetween. The two optically high-refractive layers 6a can be independently formed of, for example, silicon nitride, zinc-tin oxide, silicon-zirconium nitride or titanium oxide, titanium dioxide; the low-refractive layer 6b can be formed of, for example, silicon dioxide or magnesium fluoride. The material of the optically high-refractive layer 6a (sublayer) of the UV protective layer 6 and the material of the low-refractive layer 6b (sublayer) can be doped with, for example, another transition metal oxide, such as ZnO, ZrO2, HfOx. In an exemplary embodiment, the UV protective coating 6 is formed into a three-layer UV protective layer 6 starting from the inner surface II of the outer glass plate by a 35nm thick titanium dioxide layer, a 35nm thick silicon dioxide layer arranged thereon, and a 30nm thick titanium dioxide layer arranged thereon.

[0126] The layers 6 a and 6 b of the UV protective layer 6 may be preferably formed in a thickness of 10 nm to 100 nm, particularly preferably in a thickness of 20 nm to 50 nm.

[0127] Fig. 9 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:

[0128] S1 provides an outer glass pane 1 having an outer surface I and an inner surface II, wherein a single or multi-layer UV protection layer is applied to the 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 the inner surface IV,

[0129] 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,

[0130] S3 joins the layer stack by lamination. Example

[0131] An outer glass pane according to the invention is produced which has a three-layer UV protection layer on the inner surface II of the outer glass pane, wherein the UV protection coating has the following structure starting from surface II: a TiO2 layer with a thickness of 35 nm, a SiO2 layer with a thickness of 35 nm and a TiO2 layer with a thickness of 30 nm.

[0132] An identical outer pane for a composite glazing without the UV protection layer according to the invention was provided for comparative measurements of light transmission (TL(A)) and UV light reflection (UV A and UV B blocking).

[0133] These outer glass panes were measured in stacks with the respective identical inner glass panes for the composite glass pane.

[0134] The results of these measurements performed in the same manner are reproduced in Table 1.

[0135] Table 1

[0136] TL(A)[%] UVA [%] UVB[%] Comparative example without UV protection layer 81.1 45.9 31.6 Having a UV protection layer according to the invention 80.4 20.7 11.4

[0137] The obtained measured values ​​and their comparison show that when measuring the outer pane according to the invention, the visible light transmission is advantageously only very slightly reduced compared to a stack of glass panes without the UV protection layer according to the invention, while the light fractions in both the UV A and UV B spectra can be significantly reflected (blocked) by the coating according to the invention on face II of the outer pane. Due to the highly efficient filtering according to the invention of the harmful UV light fraction from the incident sunlight, aging processes, in particular changes in the properties of the holographic element, can advantageously be avoided or significantly delayed. The durability and service life of the composite glass pane according to the invention of constant quality with a holographic HUD function can thus be improved and extended.

[0138] List of reference numerals:

[0139] 100 composite glass panel

[0140] 1 outer glass panel

[0141] 2 inner glass panels

[0142] 3First intermediate layer

[0143] 4Holographic elements

[0144] 5. Holographic Materials

[0145] 6UV protection layer

[0146] 6a optical high refractive UV protection layer

[0147] 6b optical low refractive UV protection layer

[0148] 7 Second middle layer

[0149] 8First base layer

[0150] 9 Second base layer

[0151] I. The outer surface of the outer glass plate 1

[0152] II Inner surface of outer glass plate 1

[0153] III. The outer surface of the inner glass plate 2

[0154] IV Inner surface of inner glass plate 2

[0155] O Top edge

[0156] U bottom edge

[0157] S side edge

[0158] 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), And wherein a single-layer or multi-layer UV protection layer (6) is applied in the form of a coating to the inner surface (II) of the outer glass pane (2) at least in the region of the holographic element (4).

2. The composite glass pane (100) according to claim 1, wherein the UV protection layer (6) is formed of a UV light reflecting and / or UV light absorbing material.

3. The composite glass pane (100) according to claim 1 or 2, wherein the UV protection layer (6) comprises at least one layer of an optically high-refractive material having a refractive index greater than or equal to 1.

8.

4. The composite glass pane according to claim 1 , wherein the UV protection layer ( 6 ) comprises at least one optically high-refractive layer ( 6 a ) having a refractive index greater than or equal to 1.8, which is based on titanium dioxide, silicon nitride, tin-zinc oxide, silicon-zirconium nitride, silicon-titanium nitride or silicon-hafnium nitride.

5. The composite glass pane (100) according to claim 1, wherein the UV protection layer (6) comprises at least one optically low-refractive layer (6b) having a refractive index of less than 1.8, which is preferably based on silicon dioxide or magnesium fluoride.

6. The composite glass pane according to any one of claims 1 to 5, wherein the UV protective layer (6) comprises at least one layer (6a) of an optically high refractive material having a refractive index greater than or equal to 1.8 and at least one layer (6b) of an optically low refractive material having a refractive index less than 1.8, preferably at least two layers (6a) of high refractive material, wherein the optically high refractive layers and the optically low refractive layers (6a, 6b) are preferably alternately superposed on each other in a planar manner. 7 . The composite glass pane according to claim 1 , wherein the single-layer or multi-layer UV protection layer ( 6 ) is formed with a layer thickness of 10 nm to 200 nm, preferably 20 nm to 100 nm, particularly preferably 30 nm to 80 nm.

8. The composite glass pane (100) according to any one of claims 1 to 7, 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).

9. The composite glass pane (100) according to any one of claims 1 to 8, wherein the first interlayer (3), and / or, if present, the second interlayer (7), independently of one another, is a thermoplastic interlayer (3), an adhesive layer or an optically clear adhesive.

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

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

12. A projection device comprising a composite glass pane (100) according to any one of claims 1 to 11 and a projector, which is aligned with the holographic element (4) from the interior space, wherein the inner surface (IV) of the inner glass pane (2) is the surface of the composite glass pane (100) closest to the projector.

13. A method for producing a composite glass pane (100) according to any one of claims 1 to 11, wherein at least: a) providing an outer pane (1) having an outer surface (I) and an inner surface (II), wherein a UV protection layer (6) is applied to the inner surface (II), a first intermediate layer (3), a holographic element (4) having at least one hologram, and an inner pane (2) having an outer surface (III) and an 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 single-layer or multi-layer UV protection layer (6) is applied to the inner surface (II) of the outer glass pane (1) by wet coating, by magnetron sputtering or by chemical vapor deposition (CVD) or physical vapor deposition (PVD).

15. Use of the composite glass pane (100) according to any one of claims 1 to 11 as interior glazing or exterior glazing in vehicles or buildings, in particular 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.

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