Window pane having composite construction

Abstract

The invention relates to a vehicle window pane (11), in particular of a vehicle roof (10), comprising a composite structure having a window pane outer body (16), a window pane inner body (18) designed as a light-guiding layer (40), at least one connecting layer (13) and a heat-insulating layer (21) directed in the direction of a vehicle interior (102), the window glass outer body (16) is connected with the window glass inner body (18) through the connecting layer. An optical insulating layer (17) is arranged on an inner side (19) of the glazing inner body (18), said inner side facing in the direction of the vehicle interior (102), between the glazing inner body (18) and the heat-insulating layer (21), the refractive index n2 of the material of the optical insulating layer (17) being smaller than the refractive index n1 of the following material: the glazing inner body (40) is formed from the material.

Description

Field of the Invention

[0001] The present invention relates to a window glass having the features of the preamble of claim 1. Background Art

[0002] This type of window glass is known from practice and can in particular be used as a fixed roof element in the area of the vehicle roof or also as an adjustable cover element of a roof opening system. The window glass is configured as a composite member, which includes a window glass outer body facing the vehicle environment and a window glass inner body facing the vehicle interior space, and the window glass inner body forms the inner visible surface of the window glass. The window glass inner body is connected to the window glass outer body by a connecting layer, which in the simplest case can be configured as an adhesive layer. Alternatively, such an adhesive layer can also include a multi-layer structure having at least one functional layer. An exemplary functional layer can be a light-shielding component, which includes a liquid crystal component that can be electrically switched, i.e., a so-called LC layer or a PDLC layer. For example, the LC layer or the PDLC layer is arranged between two foils, and transparent electrodes are respectively present on the inner sides of the foils. Through the electrodes, the LC layer or the PDLC layer can be switched between a conductive state and a blocking state.

[0003] It is also known from the prior art to directly couple the light of a light source, for example, through the inner side of the window glass inner body or in the case of using a prism or other light-coupling elements, into a light guide layer. In addition, the following window glass is known: in the vehicle window pane, light is coupled into the window glass inner body by a light source arranged in the edge region of the window glass.

[0004] When light is conducted in the light guide layer, light losses occur. Due to these light losses, on the one hand, the light quality or light intensity of the light subsequently coupled out of the light guide layer is negatively affected. On the other hand, if necessary, the light losses have to be compensated for by using stronger or brighter light sources and / or by increasing the number of light sources, which results in additional cost. For example, in known light coupling-in, the light beam starting from the light source is coupled into the light guide layer not only through the light coupling-in surface of the light guide layer and remains until it is coupled out, in particular due to multiple total internal reflections in the light guide layer. More precisely, at least a part of the coupled-in light beam passes through the window glass body configured as a light guide layer not only in the direction of the vehicle exterior but also in the direction of the vehicle interior space. This component of the light is no longer available for the targeted light coupling-out from the light guide layer, which is manifested in a lower luminous density. The undesired light coupling-out from the light guide layer is mainly due to the fact that the coupled-in light tends to leave the light guide layer into the adjacent boundary layer due to the differences in the refractive indices of the different layers. The adjacent boundary layer is, for example, the adjacent air layer of the vehicle interior space or a polymer adhesive layer. Here, the closer the refractive index of the surrounding medium and / or material is to the refractive index of the light guide layer or the window glass body, the stronger the light losses due to the undesired light coupling-out into the surrounding layer.

[0005] In order to avoid heat losses or heat emissions from the vehicle interior space in the direction of the vehicle exterior, a more recent trend in the automotive industry consists in providing the window glass with a heat-insulating layer or heat-insulating coating having a low emissivity of thermal radiation. This heat-insulating layer or heat-insulating coating is usually applied to the inner side of the window glass body facing the vehicle interior space and thus at least in the top region minimizes the undesired heat discharge from the vehicle interior space. Thereby, the vehicle interior heat management can be improved and ultimately the comfort in the vehicle. Known heat-insulating layers are characterized in that they are almost penetrable for visible light, while the penetrability for infrared radiation (IR radiation) is minimized by a corresponding material selection. Thus, for example, in winter, heat losses can be reduced by such thermally insulated window glass. Thereby, despite possibly cold external conditions, the temperature in the passenger compartment remains increased compared to non-thermally insulated window glass without additionally loading the vehicle's air conditioning system.

[0006] However, in known window glasses, the installation of the thermal insulation layer results in light losses through the inner side of the window glass body, mainly due to the properties of the thermal insulation layer. This light loss is caused, for example, by a change in the optical properties (color coordinate shift) during the coupling-in of light when the light passes through the thermal insulation layer. A solution is known for minimizing such light losses or color coordinate shifts that typically occur due to the changing refractive properties at the interface, namely, locally removing the thermal insulation layer, for example, in the area where light is coupled into the light guide layer by a coupling element. In addition, absorption of the thermal insulation layer in the visible spectrum can lead to color coordinate non-uniformities when observing from the light coupling point towards the center of the light guide layer or when observing at an increasing distance from the light source.

[0007] However, recent experience has shown that the local removal of the thermal insulation layer does not adequately solve the problem of light losses. Although the color coordinate shift between the input color of the light source and the light entering the inner light guide layer can be eliminated by local removal. However, the problems of reduced luminous density and color coordinate non-uniformity caused by the thermal layer are not adequately solved. In the case of some types of thermal insulation layers, this reduced luminous density and color coordinate non-uniformity also occur, for example, in the case of light coupling through the edge region of the light guide layer. Therefore, more precisely, this points to a general problem when using a thermal insulation layer in combination with a light guide layer. Especially in the field of sunshades and / or insulating glass, this problem is exacerbated because the required insulation performance of the window glass does not allow the thermal insulation layer to be dispensed with.

[0008] The light loss is caused by the changing refractive properties of the light guide layer including the thermal insulation coating. The refractive index of the thermal insulation layer can be different from the refractive index of the material from which the light guide layer is made. As a result, the required performance of total internal reflection (TIR) by the light guide layer is changed compared to the uninsulated interface between the light guide and the adjacent vehicle interior space. This can be particularly pronounced if the thermal insulation layer is multilayered or an antireflection function (AR) is integrated into the thermal insulation layer. The changed TIR conditions can lead to more light losses. In addition, light can remain "trapped" in or absorbed by the thermal insulation layer and thus is no longer available for coupling out from the light guide layer. This problem is further complicated by the variation of the thermal insulation layer because different thermal insulation layers have different refractive properties, which hinders a generally effective solution to this problem.

[0009] Even though solutions for reducing light losses have been disclosed in the prior art, there is still a need for additional alternative solutions that can in particular enable cost-effective and simple production of a composite structure and reduce light losses therein. Summary of the Invention

[0010] Therefore, the object of the present invention is to further develop a vehicle window glass in such a way that the above-mentioned disadvantages are at least partially minimized, and in particular to provide an additional technically alternative solution, which can in particular enable a cost-effective and simple production of a composite structure, and by means of which the light loss can be minimized.

[0011] According to the present invention, this object is solved by a vehicle window glass having the features of claim 1.

[0012] Advantageous embodiments of the present invention are the subject matter of the dependent claims. All combinations consisting of at least two of the features disclosed in the description, the claims and / or the drawings fall within the scope of the present invention. It should be understood that the explanations made with respect to the vehicle window glass relate in an equivalent manner to the vehicle and / or the vehicle roof according to the present invention, without the need for a redundant mention of the vehicle and / or the vehicle roof according to the present invention. Herein, in particular, it should be understood that within the framework of customary language practice, customary language conversions and / or analogical substitutions of the respective terms, in particular the use of synonyms supported by recognized language documents, are included in this disclosure without the need for an explicit mention in the respective expressions.

[0013] According to the present invention, there is provided a vehicle window glass, in particular a window glass of a vehicle roof, the vehicle window glass comprising a composite structure having an outer window glass body, an inner window glass body configured as a light guide layer, at least one connecting layer, and a thermal insulation layer directed towards the vehicle interior space, the outer window glass body being connected to the inner window glass body by the connecting layer, characterized in that an optical insulation layer is arranged between the inner side of the inner window glass body directed towards the vehicle interior space and the thermal insulation layer. The material of the optical insulation layer has a refractive index n2. The refractive index n2 is less than the refractive index n1 of the following material: the inner window glass body is constructed of the material.

[0014] According to the present invention, different from the prior art, at least one additional intermediate layer, namely the optical insulation layer according to the present invention, is provided between the inner window glass body and the thermal insulation layer. The refractive index of the optical insulation layer is lower than the refractive index of the inner window glass body. In this way, total internal reflection (TIR) in the inner window glass body configured as a light guide layer is maintained. In this way, it is effectively prevented that the light coupled into the light guide layer interacts with the thermal insulation layer or is trapped in the thermal insulation layer or partially absorbed by the thermal insulation layer. The light can be coupled into the light guide layer through the edge region of the vehicle window glass or directly through the inner side of the inner window glass body or through a coupling element arranged on the inner side of the inner window glass body.

[0015] In the present case, all layer structures located between the outer window glass body and the inner window glass body are referred to as connecting layers.

[0016] Thus, according to the present invention, compared with the prior art, the loss of luminous density is minimized. The optical insulation layer according to the present invention may also have an additional advantage that it can prevent color change caused by absorption of certain wavelengths through the thermal insulation layer. That is, overall, there is less light loss and / or less color change loss.

[0017] In a preferred embodiment, the optical insulation layer comprises a carrier layer. The carrier layer can be constructed and / or manufactured from polycarbonate (PC) or from polyethylene terephthalate (PET). Other types of plastics are also possible. PC and PET are advantageous materials that can be widely used. Particularly preferably, the carrier layer has an optically insulating coating on the side facing the inside of the window glass body, and this coating is composed of a material having a refractive index n2. This coating can be printed and / or vapor-deposited and / or applied by other means.

[0018] In a preferred alternative embodiment, the optical insulation layer is applied directly as a coating in particular to the inside of the window glass body or is constructed on the inside. The coating can be printed and / or vapor-deposited and / or applied by other means.

[0019] In a preferred embodiment, the coating comprises a fluoropolymer and / or an oxide and / or silica gel (SiO2) and / or magnesium fluoride (MgF2). Silica gel or silica is colorless, amorphous silicon dioxide, which has a consistency ranging from gel-like, rubbery to solid. In the case of high temperatures, crystalline silicon dioxide can be formed. Depending on the oxygen fraction present, a coating based on silicon oxide (SiOx) can form a combination of stoichiometric oxide (SiO2) and non-stoichiometric suboxide (SiOx, x < 2). As a powder, this crystalline silicon dioxide is strongly hygroscopic and is suitable as a gelling agent, filter material, adsorption material, and desiccant. As a thin layer, this crystalline silicon dioxide is suitable as an insulating material and / or passivation material in semiconductor technology and optical technology. Magnesium fluoride (MgF2) is a material that is transparent in the wavelength range between 0.12 μm and 7.5 μm. In addition, this magnesium fluoride is birefringent. The combination of these two properties enables the manufacture of polarization optical devices.

[0020] In a preferred embodiment, the coating is applied by chemical vapor deposition and / or by physical deposition, in particular by sputtering and / or solution deposition and / or spray deposition. Other application methods, such as printing processes or the like, are also conceivable.

[0021] In a preferred embodiment, the optical insulation layer comprises a single-layer structure or a multi-layer structure. In other words, the optical insulation layer itself can also be structured in a single layer or in multiple layers. For example, the optical insulation layer can be a laminated foil having a multi-layer structure. Preferably, the individual layers can be connected to one another via an adhesive layer.

[0022] In a preferred embodiment, the difference formed by the refractive index n1 of the inner body of the window glass and the refractive index n2 of the coating is greater than or equal to (≥) 0.06. Preferably, the refractive index n2 of the optical insulation layer can be between 1.3 and 1.52, wherein, particularly preferably, this refractive index is less than or equal to (≤) 1.45. The refractive index of the solid can be further reduced by increasing the share of porosity in the material.

[0023] In a preferred embodiment, the thermal insulation layer can comprise nanowires and / or nanoparticles. Particularly preferably, the thermal insulation layer can comprise inorganic metal oxides and / or indium tin oxide and / or fluorine-doped tin oxide and / or graphene and / or silver.

[0024] In a preferred embodiment, the thermal insulation layer can also have an additional buffer layer. A buffer layer of this type can be structured, for example, as an adhesion layer / as a diffusion barrier layer. Particularly preferably, the optical insulation layer can be positioned between the preferred buffer layer and the thermal insulation layer. Alternatively, the optical insulation layer can be positioned between the inner body of the window glass and the preferred buffer layer. Preferably, the refractive index of the preferred buffer layer is greater than the refractive index of the optical insulation layer. Particularly preferably, the chemical composition of the preferred buffer layer is similar to the chemical composition of the optical insulation layer. However, preferably here, the buffer layer can vary in its stoichiometric composition, for example in terms of the oxygen share. Preferably, the preferred buffer layer and the optical insulation layer are structured as discrete layers. Particularly preferably, the preferred buffer layer and the optical insulation layer are formed as a single layer, yet include stepped compositions and / or stepped refractive indices within this layer. This is also referred to as a graded layer.

[0025] In a preferred embodiment, the thermal insulation layer can be applied by chemical vapor deposition and / or by physical deposition, in particular by sputtering and / or solution deposition and / or spray deposition. Other application methods are also conceivable. For example, the thermal insulation layer can also be printed.

[0026] In a preferred embodiment, the connection layer comprises a light-shielding component having a liquid crystal component capable of switching and / or at least one polymer adhesive layer and / or at least one additional transparent and / or colored adhesive layer and / or an additional heat-insulating layer and / or a layer for reflecting infrared radiation and / or at least one additional functional layer. The liquid crystal component may be an LC layer or a PDLC layer. PDLC is a polymer-dispersed-liquid-crystal. The light-shielding component may comprise at least one colored and / or dyed layer and / or foil, and / or the matrix in which a plurality of crystals of the liquid crystal component are arranged may be colored and / or dyed. Alternatively, at least one polymer adhesive layer may also be colored and / or dyed. PDLC mainly has the following advantages: there is no change in brightness, but only the haze (turbidity) of the window glass is changed and thus the transparency is changed.

[0027] Alternatively to the light-shielding component, the vehicle window glass may also comprise a roller blind system which, in the unfolded state, covers the vehicle window glass, for example, on the inner side at the top and can thus cause the interior of the vehicle to be darkened.

[0028] In a preferred embodiment, the light-shielding component comprises an additional colored and / or dyed and / or transparent plastic layer and / or an additional, in particular transparent, adhesive layer and / or a layer for reflecting infrared radiation. That is, the light-shielding component may have a multi-layer structure. In addition, each layer may in turn be subdivided into a plurality of layers. Thus, for example, the plastic foil of the light-shielding component itself may comprise a plurality of layers and can thus be constructed as a foil laminate.

[0029] The preferably colored and / or dyed and / or blackened light-shielding component is preferably characterized by strong absorption of electromagnetic radiation in the wavelength range between 350 nm and 2500 nm. For visible light, the penetrability is preferably less than 30%. Preferably, for infrared radiation in the range between 700 nm and 2500 nm, the penetrability may be less than 40%.

[0030] In the Lab color space, the preferred coloring of the light-shielding component and / or at least one polymer adhesive layer may be defined in particular by the color coordinates L, a and b, where L < 30, -15 < a < 15, and -15 < b < 15.

[0031] Preferably, the preferably present plastic foil of the light-shielding component has transparent electrodes on its inner side, such that the adjacent liquid crystal component can be adjusted between a blocking state and a conducting state by changing the electric field. Alternatively, the carrier layer may also comprise such transparent electrodes.

[0032] The above-mentioned preferred plastic foil and / or preferred carrier layer can in particular be configured as a PET (polyethylene terephthalate) foil, a COP (cyclic olefin polymer) foil or can also be configured as a PC (polycarbonate) foil. Particularly preferably, in the case of the light-shielding assembly, the two plastic foils can be coated with ITO (indium tin oxide) or PEDOT:PSS in order to form electrodes for the liquid crystal assembly.

[0033] If the connecting layer comprises a light-shielding assembly, the liquid crystal assembly of this connecting layer can be a PNLC (polymer network liquid crystal) layer, wherein a conducting state is generated by applying a voltage, and a blocking state exists in the absence of a voltage. Alternatively, the connecting layer can be a layer in which a voltage is applied in each switching state. This is the so-called reverse bistable PDLC layer. PDLC is a polymer-dispersed-liquid-crystal. Irrespective of the selected PDLC layer variant, the PDLC layer can be segmented or provided with a pattern. Alternatively, the liquid crystal assembly can be an LC layer. PDLC mainly has the following advantages: there is no change in brightness, but only the haze (turbidity) of the window glass is changed and thus the transparency is changed.

[0034] In order to also ensure the functional ability of the preferably present light-shielding assembly at high external temperatures, the composite construction of a preferred embodiment of the window glass according to the invention comprises at least one layer for reflecting infrared radiation on the side of the liquid crystal assembly facing the window glass exterior. Thus, undesired defects that may be caused by the absorption of heat by the liquid crystal assembly can be avoided.

[0035] Preferably, the reflection ability of the layer for reflecting infrared radiation is greater than 60%. In particular, in the case where the reflection ability of the layer for infrared radiation is less than 60%, for example from 2% to <60%, an additional layer for reflecting infrared radiation can be provided between the window glass exterior and the light-shielding assembly. Additionally, this additional layer can be arranged on the light-shielding assembly and / or on at least one plastic foil of the light-shielding assembly and / or between such a plastic foil and the liquid crystal assembly, for example, it can be arranged on an additionally applied foil (this additionally applied foil can thus be an IR-coated PET foil), or it can also be arranged on the lower side of the window glass exterior, or can also be arranged in other ways between the window glass exterior and the light-shielding assembly. At least 60% total reflection of infrared radiation of the composite construction can be achieved by the additional layer.

[0036] In a preferred embodiment of the window glass according to the invention, the layer for reflecting infrared radiation is arranged on the plastic foil of the light-shielding assembly, which preferably includes the connecting layer, facing the outer body of the window glass. Preferably, the layer for reflecting infrared radiation can be applied as a coating to such a plastic foil. Alternatively, another coated foil provided with an IR coating can be laminated to such a plastic foil. It is also conceivable that the layer for reflecting infrared radiation is arranged on the inner side of the outer body of the window glass.

[0037] In order to maintain a particularly high reflection effect for infrared radiation and a high transmission ability for visible light, in a specific embodiment of the window glass according to the invention, the layer for reflecting infrared radiation has a multi-layer structure. For example, this type of multi-layer structure can include additional heat-insulating layers and / or heat-insulating coatings (Low-E layer; Low-E = low emissivity). Configuring the layer for reflecting infrared radiation as a multi-layer structure results in a high reflection ability, especially in the wavelength range of 650 nm to 2500 nm.

[0038] The high reflection ability can be achieved in particular by the fact that each layer of the preferred layer or multi-layer structure for reflecting infrared radiation is formed from at least one material of the following group: the group includes metals (such as gold, silver, and copper) and oxides (such as tin oxide, titanium dioxide, zinc oxide, indium tin oxide, tin fluoride oxide, zinc tin oxide, aluminum oxide).

[0039] Particularly preferably, the window glass includes at least one polymer adhesive layer, which is also exemplarily referred to as the first and second polymer adhesive layers hereinafter. Preferably, the light-shielding assembly, which includes the connecting layer, is connected to the outer body of the window glass through the first polymer adhesive layer, especially directly or indirectly (i.e., possibly with at least one additional layer interposed), and is connected to the inner body of the window glass through the second polymer adhesive layer, especially directly or indirectly (i.e., possibly with at least one additional layer interposed). Alternatively, if the light-shielding assembly itself includes additional adhesive layers, and the attachment to the inner body of the window glass can be achieved directly through the additional adhesive layers, for example, only one polymer adhesive layer can also be provided.

[0040] Preferred polymer adhesive foils are formed, for example, from thermoplastic polyurethane (TPU), ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), epoxy resin, silicone, polyethylene terephthalate, or other transparent plastic foils. Preferably, the refractive index of the polymer adhesive foil used respectively lies within the range of the refractive index of the inner body of the window glass or the outer body of the window glass and, for example, has a value of approximately 1.5.

[0041] In a preferred embodiment, the window glass comprises a light source configured to couple light into the light guide layer particularly directly through the inner side of the inner body of the window glass, directly or indirectly through the outer edge of the inner body of the window glass, i.e., through a side surface that is not the main surface of the inner body of the window glass and / or through a coupling-in element.

[0042] In a preferred embodiment, a coupling-in element of this type is arranged on the inner side of the inner body of the window glass. In an embodiment of this type, the light source can be arranged on the side surface of the coupling-in element such that the light emitted by the light source can be deflected by the coupling-in element and then preferably can be coupled into the light guide layer through the inner side of the inner body of the window glass.

[0043] If a coupling-in element is provided, it is particularly preferred that the thermal insulation layer and / or the optical insulation layer is removed, in particular cut out, in the region of the coupling-in element. Thereby, an undesired color shift due to the interaction of the light to be coupled in with the thermal insulation layer can be prevented.

[0044] Conversely, if the light is directly coupled in through the inner side of the inner body of the window glass, i.e., if the light source is preferably arranged such that the main radiation direction is substantially perpendicular to the inner side, preferably with a deviation of + / - 30°, in particular a maximum of + / - 5°, from the normal of the main surface of the inner body of the window glass, then the cutting out of the thermal insulation layer and / or the optical insulation layer in the region of the light source can also be dispensed with, since color shift preferably does not occur through the radiation of the light substantially perpendicular to the inner side. Here, it can be preferred that the light of the light source is directed, for example, through a collimator.

[0045] A light scattering assembly is arranged on the side of the inner body of the window glass opposite the light source. The light scattering assembly is arranged such that the light of the light source coupled into the inner body of the window glass is scattered such that most of the light coupled in and conducted to the light scattering assembly is reflected back in all possible spatial directions such that the light is conducted by total internal reflection within the window glass body. For example, the light scattering assembly can be a print (e.g., a print with white), a surface structuring, and / or a coating. On the surface of the inner body of the window glass assigned to the light source, an additional light scattering assembly and / or a reflector can be arranged in the region of the light source.

[0046] In addition, the light source can have a background reflector and / or a background light scattering assembly such that the light of the light source not coupled into the inner body of the window glass is reflected or scattered back onto the inner body of the window glass again.

[0047] In an embodiment, the light source is arranged such that the light of the light source is mainly coupled in through the side edges of the inner body of the window glass, i.e., through side surfaces that extend substantially perpendicular or at an angle with respect to the plane of the inner body of the window glass. Preferably, the light source is arranged laterally offset with respect to the inner body of the window glass in the plane orientation of the inner body of the window glass.

[0048] In a preferred embodiment, the light extraction structure can be provided on the outer side of the window glass inner body opposite to the inner side of the window glass inner body, and can be configured to extract the light coupled into the light guide layer from the window glass inner body again, in particular directionally and / or in a predefined manner, preferably defined by the light extraction structure, in the direction of the vehicle interior space. Preferably, the light source is an LED light source and / or includes a plurality of light-emitting diodes. Preferably, when observing the composite structure, the outer side of the light guide layer is opposite to the inner side of the window glass inner body.

[0049] In order to be able to use the window glass according to the invention also as a so-called ambient light element, which forms a planar light emitter in the vehicle interior space, at least one light source is provided, wherein the window glass inner body forms a light guide layer, and the light of the light source can be coupled into the light guide layer such that the window glass inner body emits light as a whole or in defined segments. According to the invention, the functions of switchable glass, heat insulation and ambient light illumination are integrated in the window glass according to the invention. Particularly preferably, at least one light source is arranged directly or indirectly on the inner side of the window glass inner body such that the light is directly coupled in through the inner side of the window glass inner body.

[0050] Alternatively or additionally, the coupling-in element is arranged on the inner side of the window glass inner body, and the light source is arranged on the side surface of the coupling-in element such that the light emitted by the light source can be deflected by the coupling-in element and can be coupled into the light guide layer. Preferably, the coupling-in element is a body of material transparent to the light of the light source, which body is configured in a plate-like manner and / or has a wedge-shaped or trapezoidal cross-section. Preferably, the coupling-in element is configured as a prism, which prism is adhesively bonded to the inner side. Particularly preferably, the coupling-in element is a prism.

[0051] In a preferred embodiment, the coupling-in element is a body of material transparent to the light of the light source, the body of material being configured in the form of a strip and / or having a wedge-shaped or trapezoidal cross-section. Preferably, the coupling-in element is arranged on the inner side of the window pane assembly in a manner close to the edge. Then, light can be coupled into the light guide layer of the window pane assembly through the extension of the strip-shaped coupling-in element. The coupling-in element can be configured, for example, as an optical prism. Preferably, the coupling-in element is made of a material comprising PMMA (polymethyl methacrylate), PC (polycarbonate), PA (polyamide), COC (cycloolefin copolymer) or COP (cycloolefin polymer). The refractive index of the coupling-in element is particularly adapted to the refractive index of the adjacent light guide layer and preferably has a value between 1.40 and 1.65 and in particular between 1.48 and 1.59. Preferably, the coupling-in element is manufactured according to an extrusion method or an injection molding method. Alternatively or additionally, the coupling-in element can also be constructed of a resin and / or of a transparent polyurethane and can preferably be arranged on the window pane assembly. To improve the internal reflection, the coupling-in element can be provided with a reflective coating, which can comprise a metal (such as aluminum or silver) and can be applied according to a vapor deposition process or a sputtering process. To further improve the coupling-in characteristics of the light into the light guide layer, in an advantageous embodiment of the vehicle window glass according to the invention, an additional deflection structure is arranged between the coupling-in element and the window pane assembly. By means of the additional deflection structure, the angle of incidence of the light onto the light guide layer can be changed by means of a corresponding refraction in order to increase the internal reflection in the light guide layer. The additional deflection structure can comprise a series of asymmetrical prisms having dimensions in the millimeter range or in the micrometer range and arranged as a three-dimensional array or arranged linearly, as is the case, for example, with a Fresnel lens array. The additional deflection structure can be constructed integrally with the coupling-in element and directly during the manufacture of the coupling-in element, for example during an extrusion process or an injection molding process. It is also conceivable that the additional deflection structure is a coating of the coupling-in element, for example in the form of a separate structured film.

[0052] In a preferred embodiment, the coupling-in element is adhesively bonded to the window pane, in particular to the inner side, by means of an adhesive layer. The adhesive layer, preferably having a refractive index between 1.40 and 1.65 and in particular between 1.48 and 1.56, can be formed by any optically suitable adhesive. For example, the adhesive layer is formed by a pressure-sensitive adhesive, an optically transparent liquid adhesive (LOCA = liquid optically clear adhesive), EVA (ethylene vinyl acetate), PVB (polyvinyl butyral), TPU (thermoplastic polyurethane), an epoxy resin adhesive or an acrylate adhesive. Preferably, the materials selected each have a refractive index that minimizes the refraction of the light beam at the interface and optimizes the coupling-in efficiency under ideal angular conditions.

[0053] In a specific embodiment of a window glass according to the invention, in order to optimize the light coupling into and out of the optocoupler in the window glass body, a reflective layer for reflecting visible light is arranged on the outer side of the window glass body. The reflectivity of the reflective layer is preferably at least 2%, and / or the reflective layer can be a layer for reflecting infrared radiation. Additionally, the ambient light effect is enhanced by internal reflection in the window glass body. The reflective layer for reflecting visible light can also be configured as a multi-layer structure or a single-layer structure. The single-layer or multi-layer structure layer can be formed by at least one material from the following group of materials: the group includes, for example, silver, gold, copper, tin oxide, titanium dioxide, zinc oxide, indium tin oxide, tin fluoride oxide, zinc tin oxide, and aluminum oxide.

[0054] Preferably, the light transmissibility of the composite structure for visible light is low not only in the conductive state of the liquid crystal component but also in the blocking state, which preferably results in low light input into the vehicle interior through the window glass.

[0055] The outer window glass body and the inner window glass body of the window glass according to the invention can be made of transparent glass or other suitable glass, or can also be made of plastic materials, such as polycarbonate. In a specific embodiment, the inner window glass body can also be formed by a hard, impact-resistant, and scratch-resistant coating, which is configured on the side of the light-shielding component facing away from the outer window glass body.

[0056] In a specific embodiment of the window glass according to the invention, the outer window glass body and the inner window glass body are each configured to be arched, more precisely in the longitudinal direction of the window glass and / or in the transverse direction of the window glass. The radius of curvature defining the arched portion can vary in the relevant direction and can, for example, have a value between 1,000 mm and 10,000 mm, especially between 2,000 mm and 5,000 mm. The light-shielding component can follow the arched portion.

[0057] Furthermore, the invention relates to a vehicle and / or a vehicle roof, which includes at least one window glass, wherein the window glass can be a cover element of a top opening system or a fixed top element.

[0058] It should be understood that the features mentioned above and those yet to be described below can be configured not only individually but also in any combination with each other without departing from the framework of the invention. It should also be understood that the embodiments and examples mentioned above and those yet to be described below relate to all embodiments of the invention in an equivalent or at least similar manner, without the need to mention them separately. Description of the Drawings

[0059] The basic and specific embodiments of the present invention are schematically shown in the drawings and are exemplified below. The drawings show:

[0060] Figure 1 A schematic top view of a vehicle roof having a window glass according to the present invention;

[0061] Figure 2 A schematic cross-section of an exemplary window glass;

[0062] Figure 3 A schematic cross-section of an exemplary window glass;

[0063] Figure 4 A schematic cross-section of an exemplary window glass; and

[0064] Figure 5 A schematic cross-section of an exemplary window glass. Detailed Description

[0065] Figure 1 The vehicle roof 10 of a motor vehicle is shown, which is not shown in more detail in other respects. The vehicle roof 10 is a panoramic roof, which has an adjustable cover element 12 and a fixed roof element 14, which is connected to the vehicle body in a fixed or non-movable manner. The cover element 12 and the fixed roof element 14 are each constructed as a glass element and thus as a window glass 11. The cover element 12 and the fixed roof element 14 have the same or different composite structures, which are shown Figures 2 to 5 in different implementation variants.

[0066] Alternatively, the vehicle roof 10 may have a second fixed roof element 14 instead of the roof element 12 or may have a single fixed roof element 14 instead of the fixed roof element 14 and the roof element 12. The roof elements 12 and 14, each constructed as a window glass 11, are each composite members, which include an outer window glass body 16, a connecting layer 13 and an inner window glass body 18. The outer window glass body 16 and the inner window glass body 18 are each made of soda-lime clear glass, but may also be made of other materials, such as plastics. In the simplest case (see Figure 2 ), the connecting layer may be an adhesive layer, such as a PVB layer, or may include a complex multi-layer structure (see Figures 3 to 5 ). In the present case, all layer structures located between the outer window glass body 16 and the inner window glass body 18 are referred to as the connecting layer 13.

[0067] The outer window glass body 16 faces the vehicle environment, while the inner window glass body 18 faces the vehicle interior space 102 by means of the inner side 19 and forms the inner visible surface of the window glass 10.

[0068] In Figure 2 a particularly simple layer structure of a vehicle window glass 11 configured as a composite member is shown. Here, the outer window glass body 16 is connected to the inner window glass body 18 by a connecting layer 13. The optical insulation layer 17 according to the invention is arranged on the inner side 19 of the inner window glass body 18. The optical insulation layer 17 may include a carrier layer 15 made of polycarbonate or polyethylene terephthalate. Such a carrier layer 15 may have an optically insulating coating on the side oriented towards the inner side 19 of the inner window glass body 18, and the coating is made of a material having a refractive index n2. Alternatively, the optical insulation layer 17 may also be made of a material having a refractive index, for example, directly applied as a coating to the inner side 19.

[0069] The refractive index n2 is less than the refractive index n1 of the material: the inner window glass body 18 is constructed of this material. Thus, as schematically shown by the dashed arrow 1 in Figure 2 , the undesired coupling out of light in the direction of the vehicle interior space is minimized because the light is refracted back into the light guiding layer 40 due to the refractive index difference n1 - n2 between the inner window glass body 18 serving as the light guiding layer 40 and the optical insulation layer 17 and thus remains in the light guiding layer. This is also indicated by the dashed arrow 2 in Figure 2 . The exemplary light path within the light guiding layer 40 is represented by the arrow 3. Here, according to Figure 2 , the light coupling into the light guiding layer 40 is achieved by a light source 36 arranged laterally in the region of the inner window glass body 18. Thus, according to Figure 2 , a lateral light coupling is shown, which is also known from the prior art.

[0070] When observed in the direction of the vehicle interior space 102, the heat insulation layer 21 according to the invention is adjacent to the optical insulation layer 17. The heat insulation layer serves as a low-emission layer, so that the heat discharge from the vehicle interior space 102 in the direction towards the vehicle environment (towards the outer window glass body) is minimized. Preferably, the heat insulation layer 21 blocks infrared radiation.

[0071] In Figures 3 to 5 another vehicle window glass 11 with a different composite structure is shown. Here, the connecting layer 13 is designed as a complex multi-layer structure.

[0072] According to Figure 3 and Figure 4, a light-shielding component 20 is provided between the outer window glass body 16 and the inner window glass body 18, and the light-shielding component is attached to the outer window glass body 16 through the first polymer adhesive layer 22 or through an adhesive layer. The light-shielding component 20 also includes a carrier layer 15', and an optical insulating layer 17' is applied on the carrier layer. The optical insulating layer 17' can be constructed to be similar to the optical insulating layer 17, and in particular can have the same refractive index n2. The carrier layer 15' is attached to the inner window glass body 18 purely exemplarily through the second polymer adhesive layer 24 and / or through an additional adhesive layer.

[0073] It should be understood that in other embodiments, additional layers, especially functional layers, such as layers for weakening infrared radiation, may be provided and / or arranged in a sandwich manner between the outer window glass body 16 and the first polymer adhesive layer 22. It should be understood that in other embodiments, additional layers, especially functional layers, may be provided and / or arranged in a sandwich manner between the first polymer adhesive layer 22 and the light-shielding component 20. It should be understood that in other embodiments, additional layers, especially functional layers, may be provided and / or arranged in a sandwich manner between the light-shielding component 20 and the second polymer adhesive layer 24. It should be understood that in other embodiments, additional layers, especially functional layers, may be provided and / or arranged in a sandwich manner between the second polymer adhesive layer 24 and the inner window glass body 18. For example, this type of functional layer can supplement and / or extend and / or improve the function of the vehicle window glass.

[0074] The light-shielding component 20 includes a liquid crystal component (LC layer or PDLC layer) 26. The liquid crystal component 26 includes a plurality of crystals, and the crystals exist in the liquid crystal layer in a matrix arrangement. The liquid crystal component 26 is bounded on both sides by plastic foils 28, 30 belonging to the light-shielding component 20. The plastic foils 28, 30 can be made of PET, for example. Although the carrier layer 15' and the plastic foil 30 are shown as being separate, this is only for illustrative purposes of the structure. However, it may be preferred that the carrier layer 15' is constructed by the plastic foil 30 itself.

[0075] Transparent electrodes 32 or 34 are respectively arranged on the inner sides of the plastic foils 28 and 30. A voltage can be applied to the liquid crystal component 26 by means of the electrodes 32 and 34, so that the liquid crystal component 26 can be adjusted between a blocking state and a conducting state through the orientation change of the plurality of crystals.

[0076] In the illustrated embodiment, the plastic foils 28 and 30 and / or the liquid crystal component 26 have a colored and / or black coloring, which is produced by means of dyes dispersed in the corresponding materials. In the prior art, the coloring and / or blackening and / or staining of the crystals and / or the matrix of the polymer-dispersed liquid crystal layer 26 are known as dye-dope technology.

[0077] The liquid crystal module 26 can be switched such that the liquid crystal module has a light transmittance for visible light of less than 3% in the blocking state, in which voltage is not applied to the electrodes 32 and 34. In the conducting state, voltage is applied to the electrodes 32 and 34, in which the light-shielding module 20 is light-transmissive for visible light due to the sum of the plastic foils 28 and 30 and / or the black dyeing of the liquid crystal module 26 such that a share of approximately 10% passes through.

[0078] In order to provide an ambient light function in the form of a surface lighting device, the vehicle window glass 11 includes at least one light source 36. According to Figure 3 , the light source 36 is arranged directly on the thermal insulation layer 21 and is adhesively bonded to the thermal insulation layer in particular. The light source 36 can also be arranged in a spaced-apart manner from the inner side 19 of the window glass body 18 (not shown). A light-scattering module 52 is arranged on the side of the window glass body 18 opposite to the light source 36. In the case of this arrangement of the light source 36, the thermal insulation layer 21 and the optical insulation layer 17 do not have to be locally cut out.

[0079] Alternatively, in order to couple light into the window glass body 18, a coupling-in element 38 can be arranged on the inner side 19 and the coupling-in element can be adhesively bonded to the inner side 19 in particular, see Figure 3 . For this purpose, as Figure 4 shown, the thermal insulation layer 21 and / or the optical insulation layer 17 are at least locally cut out. As Figure 4 shown, the light source 36 can be arranged laterally beside the window glass body 18 via the coupling-in element 38. Thereby, the design freedom when placing the light source 36 is increased. The coupling-in element 38 is configured to redirect the light emitted by the light source 36 and thus couple it into the window glass body 18 through the inner side 19. The window glass body 18 forms a light-guiding layer 40 for the light to be coupled into the window glass body.

[0080] A light-coupling-out structure 42 is arranged on the outer side 41 of the window glass body 18 opposite to the inner side 19 of the window glass body 18 and is configured to couple out the light coupled into the light-guiding layer 40 from the window glass body 18 again in a predefined manner, in particular predefined by the structure of the light-coupling-out structure 42, in the direction of the vehicle interior space 102. Preferably, the light-coupling-out structure 42 is printed onto and / or vapor-deposited onto and / or coated onto and / or laminated onto the outer side 41 of the window glass body 18.

[0081] Furthermore, in the edge region of the vehicle window glass 11 for light coupling-in and where the light source 36 is arranged, a light-shielding element 44 can be provided sectionally, in particular between the window glass outer body 16 and the first polymer adhesive layer 22. For example, the light-shielding element 44 can be printed onto the window glass outer body 16 and / or the first polymer adhesive layer 22 and / or applied as a laminated layer.

[0082] The carrier layer 15' includes an optically insulating layer 17' as a coating on the side oriented in the direction of the outer side 41 towards the inner body 18 of the window glass. The optically insulating layer 17' is made of a material having a refractive index n2, which is less than the refractive index n1 of the material of which the inner body 18 of the window glass is composed. Preferably, the carrier layer 15' is constructed of polycarbonate or polyethylene terephthalate. The coatings 17, 17' include a fluoropolymer and / or SiO2 and / or MgF2. Preferably, the difference formed by the refractive index n1 of the inner body 18 of the window glass and the refractive index n2 of the optically insulating layers 17, 17' ≥ 0.06. Particularly preferably, the refractive index n2 of the optically insulating layers 17, 17' ≤ 1.46. In other embodiments, the refractive index n2 of the optically insulating layers 17, 17' can be between 1.3 and 1.52, where, particularly preferably, the refractive index can also ≤ 1.45.

[0083] As Figure 5 shown in the embodiments of [], the light-shielding assembly 20 can include additional colored and / or dyed and / or transparent plastic layers 15 and / or additional, in particular transparent, adhesive layers and / or layers for reflecting infrared radiation.

[0084] Viewed from the outside of the vehicle in the direction of the interior space 102 of the vehicle, the window glass 11 shown in Figure 5 includes the following exemplary multi-layer structure. The outer body 16 of the window glass is connected to an optional layer 46 for reflecting infrared radiation via a first polymer adhesive layer 22 or a hot-melt adhesive layer. The colored plastic foil 28 is adjacent to the layer 46, and the colored plastic foil is connected to another transparent plastic foil 50 via a transparent adhesive layer 48 (such as an optically transparent adhesive layer (OCA layer) or silicone gel). The electrode 32 is adjacent to the plastic foil 50, and the electrode is adjacent to the liquid crystal assembly 26 (LC layer or PDLC layer). The electrode 34 is arranged opposite to the electrode 32 on the side of the liquid crystal assembly 26 facing the interior space 102 of the vehicle. Another transparent plastic foil 50 is adjacent again. The plastic foil 50 can serve as the corresponding carrier for the electrodes 32 and 34. The transparent plastic foil 50 is connected to the colored plastic foil 30 via another transparent adhesive layer 48 (such as an optically transparent adhesive layer (OCA layer)), and the carrier layer 15 with the coating 17 according to the invention is adjacent to the colored plastic foil, wherein the carrier layer 15 is connected to the inner body 18 of the window glass via a second polymer adhesive layer 24. In addition, the layer structure includes the optically insulating layer 17 according to the invention and the heat-insulating layer 21 adjacent thereto, and the optically insulating layer has a refractive index n2.

[0085] In other embodiments, the carrier layer 15’ can also be constructed by an additional transparent adhesive layer 48. In this case, the polymer adhesive layer 24 can even be omitted, such that the carrier layer 15’ configured as the adhesive layer 48 is directly laminated onto the outer side 51 of the light guide layer 50.

[0086] List of reference numerals

[0087] 1 Arrow

[0088] 2 Arrow

[0089] 3 Arrow

[0090] 10 Vehicle top

[0091] 11 Window glass

[0092] 12 Cover element

[0093] 13 Connection layer

[0094] 14 Fixed top element

[0095] 15, 15’ Carrier layer

[0096] 16 Outer window glass body

[0097] 17, 17’ Optical insulation layer

[0098] 18 Inner window glass body

[0099] 19 Inner side

[0100] 20 Light-shielding component

[0101] 21 Thermal insulation layer

[0102] 22 Polymer adhesive layer

[0103] 24 Polymer adhesive layer

[0104] 26 Liquid crystal component

[0105] 28 Plastic foil

[0106] 30 Plastic foil

[0107] 32 Electrode

[0108] 34 Electrode

[0109] 36 Light source

[0110] 38 Coupling element

[0111] 40 Light guide layer

[0112] 41 Outer side

[0113] 42 Optocoupler output structure

[0114] 44 Light shielding element

[0115] 46 Layer for reflecting infrared radiation

[0116] 48 Adhesive layer

[0117] 50 Another plastic foil

[0118] 52 Light scattering component

[0119] 100 Vehicle

[0120] 102 Vehicle interior space

[0121] n1 Refractive index

[0122] n2 Refractive index

Claims

1. A window glass (11), in particular a window glass on a vehicle roof (10), said window glass comprising a composite structure having an outer window glass body (16), an inner window glass body (18) configured as a light guide layer (40), at least one connecting layer (13) and a heat-insulating layer (21) pointing in the direction of the vehicle interior space (102), the outer window glass body (16) being connected to the inner window glass body (18) by means of the connecting layer, characterized in that On the inner side (19) of the inner body (18) of the window glass, which faces in the direction of the vehicle interior space (102), an optical insulation layer (17) is arranged between the inner body (18) of the window glass and the thermal insulation layer (21), wherein the refractive index n2 of the material of the optical insulation layer (17) is less than the refractive index n1 of the following material: the inner body (40) of the window glass is constructed from this material.

2. The window glass according to claim 1, characterized in that, The optical insulation layer (17) comprises a carrier layer (15) made of polycarbonate or polyethylene, wherein the carrier layer (15) has an optically insulating coating on the side oriented in the direction of the inner side (19) of the inner body (18) of the window glass, and the coating is made of a material having a refractive index n2.

3. The window glass according to claim 1, characterized in that, The optical insulation layer (17) is configured as a coating on the inner side (19) of the inner body (18) of the window glass.

4. The window glass according to claim 2 or 3, characterized in that, The coating comprises a fluoropolymer and / or SO2 and / or MgF2, or has other oxide coatings.

5. The window glass according to any one of claims 2 to 4, characterized in that, The coating is applied by chemical vapor deposition and / or by physical deposition, in particular by sputtering and / or solution deposition and / or spray deposition.

6. The window glass according to any one of the above claims, characterized in that, The optical insulation layer (17) comprises a single-layer configuration or a multi-layer configuration.

7. The window glass according to any one of the above claims, characterized in that, The difference formed by the refractive index n1 of the inner body (18) of the window glass and the refractive index n2 of the optical insulation layer (17) ≥ 0.06, and / or the refractive index n2 of the optical insulation layer (17) is between 1.3 and 1.52, particularly preferably ≤ 1.

45.

8. The window glass according to any one of the above claims, characterized in that, The thermal insulation layer (21) comprises nanowires and / or nanoparticles.

9. The window glass according to any one of the above claims, characterized in that, The thermal insulation layer (21) comprises inorganic metal oxides and / or indium tin oxide and / or fluorine-doped tin oxide and / or graphene and / or silver.

10. The window glass according to any one of the above claims, characterized in that, The thermal insulation layer (21) is applied by chemical vapor deposition and / or by physical deposition, in particular by sputtering and / or solution deposition and / or spray deposition.

11. The window glass according to any one of the above claims, characterized in that, The connecting layer (13) comprises a light-shielding component (20) having a switchable liquid crystal component (26) and / or at least one polymer adhesive layer and / or at least one further transparent and / or colored adhesive layer and / or a further thermal insulation layer and / or a layer for reflecting infrared radiation and / or at least one further functional layer.

12. The window glass according to any one of the above claims, characterized in that, The vehicle window (11) comprises a light source (42), which is configured to couple light, in particular directly through the inner side (19) of the inner body (18) of the window glass and / or through a coupling-in element (38), into the light guide layer (40), wherein, optionally, a light extraction structure (42) is arranged on the outer side (41) of the inner body (18) of the window glass, which is opposite to the inner side (19) of the inner body (18) of the window glass, and is configured to extract the light coupled into the light guide layer (40) from the inner body (18) of the window glass in the direction of the vehicle interior space (102).

13. The window glass according to claim 9 or 10, characterized in that, The coupling-in element (38) is arranged on the inner side (19) of the window glass body (18), and the light source (36) is arranged on a side surface of the coupling-in element (38) such that light emitted by the light source (42) can be redirected by the coupling-in element (38) and coupled into the light guide layer (40), wherein the thermal insulation layer (21) and the optical insulation layer (17) are removed, in particular cut out, in the region of the coupling-in element (38).

14. The window glass according to any one of claims 9 to 11, characterized in that, The coupling-in element (38) is a body of a material that is transparent to the light of the light source (36), and the body of material is configured in a plate-like manner and / or has a wedge-shaped or trapezoidal cross-section.

15. A vehicle (100) and / or a vehicle roof (10), said vehicle and / or said vehicle roof comprising a window glass (11) according to any one of the preceding claims, wherein, The vehicle window (11) is a lid element (12) or a fixed roof element (14) of a top-opening system.

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