Illumination glazing element with emissivity-reducing coating - Patent Application 20070122997

Abstract

The present invention relates to an illuminated glazing element, which comprises a glass pane (2) having a first surface (III) and a second surface (IV). The glazing element comprises: - at least one light source (5) suitable for coupling light into the glass pane (2) so that the light propagates within the glass pane (2); - provided with at least one light-scattering structure (6) suitable for separating light from the glass pane (2) via the first surface (III) and / or the second surface (IV), Here, the second surface (IV) of the glass pane (2) has an emissivity-reducing coating (4) based on a transparent conductive oxide and having exactly one electrically conductive layer (4.1), the electrically conductive layer (4.1) having an imaginary component k of the refractive index such that k<0.035 applies within the wavelength range from 380 nm to 780 nm.

Description

[Technical Field]

[0001] The present invention relates to an illumination glazing element having at least one glass pane, a method for making same and uses thereof. [Background technology]

[0002] Illuminated glass panes are known as such. For illumination, the glass pane is equipped with a light source, typically a light-emitting diode, whose light is coupled into the glass pane so that it propagates within the pane in the manner of a light guide, in particular by total internal reflection at the surface of the glass pane. The light can be separated from the glass pane again by a light-scattering structure, thus achieving illumination. The shape of the light-scattering structure can be freely selected, thereby generating an illuminated surface of any shape, for example, as a pattern. Illuminated glass panes of this type are known, for example, from WO 2014 / 060409, WO 2014 / 167291, or the subsequently published WO 2023 / 144282. Light can be coupled in via a side edge surface of the glass pane, via an edge surface of a recess in the glass pane, or via one of the main surfaces of the glass pane. In the latter case, light is emitted through the glass pane and reflected back into the pane by a light entrance means facing the light source so that the condition of total internal reflection is met. For this purpose, the light entrance means has a correspondingly inclined reflective surface. For example, a microprism film can be used as the light entrance means.

[0003] In the automotive sector, such lighting glass panes are of particular interest as roof windows. They are typically the inner pane of a laminated pane. However, such lighting glass panes are also used for windows in other vehicles, or as window panes in the building and architecture sector or in furniture.

[0004] Glass panes with emissivity-reducing coatings (also known as low-E coatings) are also known, which improve the thermal comfort inside vehicles by reflecting thermal radiation. Transparent emissivity-reducing coatings include, for example, functional layers based on indium tin oxide (ITO). See, for example, WO 2013 / 131667, WO 2018 / 206236, German Utility Models 202022100518, and German Utility Models 202013006875. Emissivity-reducing coatings are typically provided on the interior surface of a glass pane (or an entire glazing element comprising multiple glass panes) and have reflective properties in the mid-infrared range. In summer, they reduce the amount of heat energy entering the interior from a heated glass pane. In winter, they reduce the radiation of heat in the interior through the glass pane into the external environment.

[0005] From WO 2022 / 136107 and WO 2007 / 077099, it is known in principle that emissivity-reducing coatings of this type can be applied to the surface of illuminated glass panes of the type mentioned at the outset. However, undesirable effects can occur: the coating affects the reflective properties of the surface, on which also total internal reflection of the light from the light source coupled into the glass pane occurs. The coating can reduce the intensity of the coupled-in light and / or change its color ("color cast").

[0006] Therefore, there is a need for an emissivity-reducing coating that can be used on lighting glass panes of the type mentioned in the introduction without the coating adversely affecting the lighting. Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to provide an illumination glazing element having at least one glass pane, which serves to distribute the light of a light source within the glazing element, and which is provided with a low-emissivity coating (hereinafter also referred to as low-E coating). The coating should not significantly reduce the intensity of the coupled-in light or change its color. The glazing element should also have low emissivity, low internal reflectivity, and an internally reflected color that is as neutral as possible. Furthermore, the coating should be efficient and economical to produce. [Means for solving the problem]

[0008] The object of the invention is achieved by an illumination glazing element according to claim 1. Preferred embodiments are set out in the dependent claims.

[0009] In the sense of the present invention, an illumination glazing element is a pane- or plate-like object that comprises at least one glass pane, and in particular is structurally formed from at least one glass pane. The glazing element may be a single glass pane, or may consist solely of said glass pane. Alternatively, the glazing element may be a laminated pane or insulation glazing that includes said glass pane. In the case of a laminated pane, the glass pane is connected to another pane via a thermoplastic interlayer. In the case of insulation glazing, the glass pane is connected to another pane via a circumferential spacer in the edge region, so that a space, typically filled with an inert gas or evacuated, is formed between the panes. The glazing element may be used as a window pane, for example, for vehicles, buildings, or interiors. However, the glazing element may also be used as a component of furniture or electrical equipment, for example, as a door pane for a cupboard or shelf, or as a pane for an oven door. The glazing element may also be used as furniture, for example, as a display panel in a bar or nightclub.

[0010] An illumination glazing element according to the invention comprises at least one glass pane having a first (major) surface and a second (major) surface, typically substantially parallel to each other, and side edge surfaces extending between the first and second surfaces.

[0011] The glazing element, or glass pane, may be flat or curved in one or more spatial directions. In the latter case, typically one surface is concave and the other is convex. The edge surfaces may be flat. However, it is common to polish the edge surfaces to minimize the risk of injury. In that case, the edge surfaces are curved or rounded, in particular convexly curved or rounded.

[0012] The glazing element, in particular the glass pane, comprises at least one light source, which is suitable for coupling light emitted thereby into the glass pane so that this light propagates (at least) within the glass pane.

[0013] Light propagates within the glazing element by total internal reflection at two interfaces, in particular into an optically less dense medium (a medium with a lower refractive index). One of these interfaces is the second surface of the glass pane, on which the emissivity-reducing coating is provided. This is preferably the exposed surface of the glazing element, and the adjacent optically less dense medium is preferably air. The other interface is preferably the first surface of the glass pane—in this case, light propagates only within the glass pane. In particular, if the glazing element is in the form of a laminated pane, at least one further layer may be in contact with the first surface, which has substantially the same refractive index as the glass pane, so that the first surface does not constitute a reflective interface. In this case, the other interface is the surface of the at least one further layer, which faces away from the glass pane, where there is a transition to the optically less dense medium.

[0014] In other words, light propagates within the glazing element by total internal reflection at the second surface of the glass pane, on which the emissivity-reducing coating is provided, and a further interface, which is preferably the first surface of the glass pane, but in the case of a laminated pane may also be formed by the surface of a layer facing away from the glass pane, which layer is in contact with the first surface and has the same refractive index as the glass pane.

[0015] The glazing element is also provided with at least one light-scattering structure, which is suitable for separating said light from the glass pane via its first surface and / or via its second surface. The light-scattering structure is arranged or formed on one of the totally reflective surfaces or between the totally reflective surfaces. Preferably, the light-scattering structure is arranged or formed on the first surface or the second surface of the glass pane. When light propagating within the glazing element strikes the light-scattering structure, it is scattered, and this light-scattering structure prevents total internal reflection, so that the scattered light is separated from the glazing element (in particular the glass pane) and exits the glazing element.

[0016] According to the present invention, the second surface of the glass pane is provided with an emissivity-reducing coating, which comprises exactly one electrically conductive layer based on a transparent conductive oxide (also called TCO), which has an imaginary component of the refractive index k of which k<0.035 in the wavelength range from 380 nm to 780 nm. This means that for each wavelength in the wavelength range from 380 nm to 780 nm, the electrically conductive layer has an imaginary component of the refractive index k of which k<0.035. Over the entire wavelength range, no k value is less than 0.035. Preferably, in the wavelength range from 380 nm to 780 nm, the electrically conductive layer has an imaginary component of the refractive index k of which k<0.030, particularly preferably k<0.025. Exactly one electrically conductive layer means that, apart from the electrically conductive layer based on TCO, there are no further electrically conductive layers inside, below, or above the emissivity-reducing coating. If the low-E coating comprises further layers other than the electrically conductive layer, these are dielectric layers.

[0017] The complex refractive index, tilde n, is the real part of the refractive index, n, and the imaginary part, n i It is constructed by the sum of the product of multiplying by the imaginary number i.

number

[0018] Imaginary part of the complex refractive index, n i is also called the extinction coefficient k. The extinction coefficient describes the attenuation ability of an optical medium; the larger the value of k, the more incident light is absorbed by the material. The magnitude of the extinction coefficient k depends on the chemical and crystalline structure of the material.

[0019] The inventors have discovered that low-E coatings with a single electrically conductive layer based on TCO are particularly suitable for achieving high light intensity within the glazing if the imaginary part of the refractive index of the TCO layer within the wavelength range of 380 nm to 780 nm is less than k=0.035. The specified wavelength range corresponds to that of visible light, in which the lighting glazing element also operates. If the extinction coefficient is selected to be this small, the light coupled into the lighting glazing element is only attenuated by absorption, and the high light intensity of the lighting glazing element is maintained.

[0020] Preferably, in the wavelength range of 380 nm to 490 nm, the electroconductive layer has an imaginary component k of the refractive index of k<0.020, particularly preferably k<0.015. In the wavelength range of 490 nm to 575 nm, the electroconductive layer has an imaginary component k of the refractive index of k<0.015, particularly preferably k<0.010. Preferably, in the wavelength range of 600 nm to 700 nm, the electroconductive layer has an imaginary component k of the refractive index of k<0.025, particularly preferably k<0.020. This allows for maintaining particularly high light intensity within these wavelength ranges. This means that for each wavelength within the wavelength range, the k value is smaller than a specific value. These wavelength ranges are particularly important because typical light sources of violet / blue, green, and red have emission wavelengths within these ranges.

[0021] The refractive index is essentially independent of the measurement method; it can be determined, for example, by ellipsometry. Ellipsometry is a common optical technique for determining layer thicknesses and optical constants, and allows measuring both the real and imaginary parts of the refractive index. Ellipsometers are commercially available, for example from Sentech.

[0022] The extinction coefficient of the electrically conductive layer is determined by measuring the imaginary refractive index of the low-E coating in the wavelength range of 380 nm to 780 nm. In addition to the electrically conductive layer, the low-E coating may also contain a dielectric layer. Since the dielectric does not contribute to absorption and can therefore be neglected, direct conclusions can be drawn about the electrically conductive layer from measurements of the low-E coating.

[0023] Unless otherwise specified, within the scope of the present invention, the refractive index of the additional layers of the low-E coating is essentially based on a wavelength of 550 nm. The optical thickness is the product of the geometric thickness and the refractive index (550 nm). The optical thickness of the layer sequence is calculated as the sum of the optical thicknesses of the individual layers. Unless otherwise specified, the layer thicknesses shown are geometric layer thicknesses.

[0024] The electrically conductive layer is preferably based on indium tin oxide (ITO). However, alternatively, the electrically conductive layer may be based on, for example, indium zinc mixed oxide (IZO), aluminum-doped zinc oxide (AZO, ZnO:Al), gallium-doped zinc oxide (GZO), fluorine-doped tin oxide (FTO, SnO2:F), antimony-doped tin oxide (ATO, SnO2:Sb), or niobium-doped titanium oxide (TiO2:Nb). Such layers are corrosion-resistant and can be used on exposed surfaces. The real part of the complex refractive index of the TCO layer is preferably between 1.5 and 2.3.

[0025] When a layer (thin layer) of a coating is "based on a material", it consists mainly of this material, in particular essentially of this material, in addition to any impurities or doping. An electrically conductive layer based on a TCO is therefore formed mainly from it. Preferably, an electrically conductive layer based on a transparent conductive oxide comprises at least 90% by weight of TCO, particularly preferably at least 95% by weight of TCO, in particular consisting of a transparent conductive oxide.

[0026] Preferably, the electrically conductive layer is deposited by physical vapor deposition. In principle, the extinction coefficient k can be influenced by the oxygen content of the process gas during physical vapor deposition, especially during magnetic field-assisted cathode sputtering. In a preferred embodiment, the oxygen content of the process gas is selected to be between 1% and 3% by volume. Such an oxygen content is particularly suitable for producing electrically conductive TCO layers with an extinction coefficient k of less than 0.035 in the wavelength range from 380 nm to 780 nm. Particularly preferably, the electrically conductive layer is based on indium tin oxide (ITO) and is deposited by physical vapor deposition with an oxygen content of 1% to 3% by volume in the process gas. In this way, particularly good results are achieved in terms of absorption properties.

[0027] In a preferred embodiment, the emissivity-reducing coating has a specific sheet resistance of less than 250 μΩ·cm, particularly preferably less than 200 μΩ·cm.

[0028] The inside emissivity of the glazing assembly is preferably 40% or less, particularly preferably 35% or less, and even more preferably 30% or less. Here, the inside emissivity is a measure of how much thermal radiation the pane emits in its installed state relative to the interior, for example the interior of a building or vehicle, compared to an ideal thermal radiator (black body). In the sense of the present invention, emissivity means the normal emissivity at 283 K according to standard EN 12898.

[0029] The electrically conductive layer preferably has a thickness of 60 nm to 100 nm, more preferably 65 nm to 95 nm, in which range a good emissivity reduction effect of the low-E coating and at the same time a sufficiently low absorption of the electrically conductive layer are achieved.

[0030] The low-E coating preferably comprises one or more dielectric layers arranged above or below a TCO layer. Typically, a dielectric layer or an arrangement of dielectric layers is provided below and / or above the TCO layer, which improves the optical properties, in particular the transmittance and reflectance. The emissivity-reducing coating is then preferably a thin film stack, i.e., an arrangement of thin individual layers. Preferred embodiments of the emissivity-reducing coating, by which particularly good results can be achieved, are described below.

[0031] If the first layer is arranged above the second layer, this means that the first layer is arranged further away from the substrate to which the coating is applied than the second layer. If the first layer is arranged below the second layer, this means that the second layer is arranged further away from the substrate than the first layer. The low-E coating is preferably formed as a thin film arrangement, which comprises multiple thin layers deposited on the second surface of the glass pane, one above the other. If the first of these thin layers is applied below the second thin layer, the distance between the first thin layer and the second surface of the glass pane is smaller than the distance between the second thin layer and the latter.

[0032] So-called anti-reflection or anti-reflective layers, which have a lower refractive index than the TCO layer and are arranged below and above it, have a particularly large influence on the optical properties. These anti-reflection layers can increase the transmittance of the pane or decrease its reflectance, especially as a result of interference effects. This effect is highly dependent on the refractive index and the layer thickness.

[0033] In an advantageous embodiment, the emissivity-reducing coating preferably comprises a dielectric lower antireflection layer disposed below the TCO layer. The refractive index of the lower antireflection layer is preferably 1.8 or less, for example 1.3 to 1.8, particularly preferably 1.6 or less, for example 1.3 to 1.6. The thickness of the lower antireflection layer is preferably 5 nm to 25 nm, particularly preferably 5 nm to 20 nm.

[0034] In an advantageous embodiment, the emissivity-reducing coating preferably comprises a dielectric upper antireflection layer disposed above the TCO layer. The refractive index of the upper antireflection layer is preferably 1.8 or less, for example 1.3 to 1.8, particularly preferably 1.6 or less, for example 1.3 to 1.6. The thickness of the upper antireflection layer is preferably 45 nm to 100 nm, particularly preferably 50 nm to 75 nm.

[0035] In an advantageous embodiment, the emissivity-reducing coating has both a bottom anti-reflective layer below the TCO layer and a top anti-reflective layer above the TCO layer.

[0036] The antireflection layer particularly provides advantageous optical properties for the pane. It increases the pane's transparency and promotes a neutral color impression. The antireflection layer is preferably based on an oxide or fluoride, particularly preferably on silicon oxide, magnesium fluoride, or calcium fluoride, and in particular on silicon oxide (SiO2). The silicon oxide may contain dopants, preferably doped with aluminum (SiO2:Al), boron (SiO2:B), titanium (SiO2:Ti), hafnium (SiO2:Hf), or zirconium (SiO2:Zr).

[0037] A relatively high or relatively low transparency of the glazing may be desirable or necessary depending on the field of application of the lighting glazing element: for example, a transmittance of 70% or more in the visible range of the light spectrum is legally required for automobile windscreens, while a relatively low transparency may be acceptable or even desirable for decorative glazing or automotive roof glazing.

[0038] The upper anti-reflective layer may be the top layer of the coating. In that case, this layer has the longest distance to the substrate surface (the second surface of the glass pane) and is the final layer in the layer stack. Depending on the application and installation of the glazing element, this layer may be exposed, i.e., accessible to humans. However, one or more further individual layers may also be arranged above the upper anti-reflective layer. Such further layers may, for example, serve to improve scratch resistance and may be based on zirconium oxide, titanium oxide, or hafnium oxide.

[0039] In an advantageous embodiment, the emissivity-reducing coating has an upper dielectric barrier layer between the TCO layer and the upper anti-reflection layer for controlling oxygen diffusion, with a refractive index of 1.9 or higher. The barrier layer serves to regulate the oxygen supply to an optimal level. Particularly good results are obtained when the refractive index of the barrier layer is between 1.9 and 2.5.

[0040] The upper dielectric barrier layer, which regulates oxygen diffusion, is preferably based on nitrides or carbides. It may be based on, for example, nitrides or carbides of tungsten, niobium, tantalum, zirconium, hafnium, chromium, titanium, silicon, or aluminum. In a preferred embodiment, the upper dielectric barrier layer is based on silicon nitride or silicon carbide, in particular silicon nitride (Si3N4), which provides particularly good results. The silicon nitride may contain dopants, and in a preferred embodiment, it is doped with aluminum (Si3N4:Al), zirconium (Si3N4:Zr), hafnium (Si3N4:Hf), titanium (Si3N4:Ti), or boron (Si3N4:B). During the temperature treatment after application of the coating according to the present invention, the silicon nitride may be partially oxidized. In that case, the barrier layer deposited as Si3N4 may be converted to Si after the temperature treatment. x N y O z The oxygen content is typically in the range of 0 atomic % to 35 atomic %.

[0041] The thickness of the upper dielectric barrier layer is preferably 5 nm to 40 nm, particularly preferably 8 nm to 25 nm, and even more preferably 9 nm to 15 nm. This allows the oxygen content of the TCO layer to be adjusted in a particularly advantageous manner. The thickness of the barrier layer is selected from the viewpoint of oxygen diffusion, with the optical properties of the pane being of relatively little consideration. However, barrier layer thicknesses in the specified ranges have been shown to be compatible with the emissivity-reducing coating according to the invention and its optical requirements.

[0042] In an advantageous embodiment, the emissivity-reducing coating comprises a lower dielectric blocking layer against alkali diffusion below the TCO layer and, optionally, below the lower antireflection layer. This blocking layer reduces or prevents the diffusion of alkali ions from the glass substrate into the coating system. Alkali ions can adversely affect the properties of the coating. The refractive index of the lower blocking layer is preferably 1.9 or higher. Particularly good results are obtained when the refractive index of the blocking layer is between 1.9 and 2.5. The blocking layer is preferably based on an oxide, nitride, or carbide, in particular an oxide, nitride, or carbide of tantalum, chromium, niobium, tantalum, zirconium, hafnium, titanium, silicon, or aluminum, such as WO3, Nb2O5, Bi2O3, TiO2, Ta2O5, YO3, ZrO2, HfO2, SnO2, or ZnSnO. x The blocking layer is preferably based on an oxide such as AlN or a nitride such as AlN. The blocking layer is particularly preferably based on silicon nitride (Si3N4), which achieves particularly good results. The silicon nitride may contain dopants, and in preferred embodiments is doped with aluminum (Si3N4:Al), titanium (Si3N4:Ti), zirconium (Si3N4:Zr), hafnium (Si3N4:Hf), or boron (Si3N4:B). The thickness of the blocking layer is 10 nm to 50 nm, particularly preferably 10 nm to 40 nm, for example 15 nm to 35 nm. The blocking layer is preferably the bottom layer of the layer stack; i.e., it is in direct contact with the substrate surface, where it can optimally exert its effect.

[0043] In a particularly advantageous embodiment, the coating consists only of the layers described, without any further layers. The emissivity-reducing coating particularly preferably consists of the following layers, in the specified order, starting from the substrate surface (second surface of the glass pane): - Blocking layer against alkali diffusion - Bottom anti-reflection layer - TCO-based electrically conductive layer - Upper barrier layer that regulates oxygen diffusion - Top anti-reflection layer

[0044] If the glazing element according to the invention is a window pane (e.g. for a vehicle, a building, an interior, a piece of furniture, or an item of furnishings), it is intended to be inserted into a window opening where it is intended to separate the interior space from the exterior environment. The glass pane then has an outer surface and an interior surface. In the sense of the present invention, the outer surface means the main surface intended to face the exterior environment when installed. In the sense of the present invention, the interior surface means the main surface intended to face the interior when installed. Instead of being used as a window pane in the narrower sense, the glazing element may equally well be used as a door pane or facade glazing, and the above statements apply analogously.

[0045] The second surface provided with the emissivity-reducing coating is the interior surface of the glass pane, particularly preferably the interior surface of the entire glazing element exposed to the interior. This is advantageous in terms of thermal comfort inside the room, since in particular heat radiation from the heated glazing element into the interior is optimally reduced. However, in principle, it is also conceivable for the second surface of the glass pane to form the exterior surface of the glass pane and / or the entire glazing element.

[0046] The emissivity-reducing coating is typically applied over the entire surface of the second surface, possibly excluding peripheral edges and / or other locally defined areas, which may function, for example, for data transmission or light coupling, etc. The coated area of ​​the substrate surface is preferably at least 80%.

[0047] In a first preferred embodiment, the glazing element according to the invention is a single pane of glass, structurally formed solely from a pane of glass, which acts as a light guide for light from a light source, in which case the total internal reflection interfaces are the first and second surfaces of the pane of glass, which form the exposed surfaces of the glazing element.

[0048] In a second preferred embodiment, the glazing element according to the invention is a laminated pane. In addition to the light-conductive glass pane with the emissivity-reducing coating and the light source, the laminated pane comprises a further pane (in particular a glass pane) connected to the light-conductive glass pane via a thermoplastic interlayer. This further pane also has a first surface, a second surface, and a peripheral edge surface extending therebetween. If the glass element is a window pane, one pane may be referred to as the outer pane and the other pane as the inner pane. In the sense of the present invention, the inner pane refers to the pane of the laminated pane that faces inward in the installed position. The outer pane refers to the pane that faces the external environment. The inner surface of the outer pane and the outer surface of the inner pane face each other, face the thermoplastic interlayer, and are connected to each other by the thermoplastic interlayer.

[0049] In the case of laminated panes, the total reflection interfaces are preferably the first and second surfaces of the light-conducting glass pane. Typically, the glass pane has a refractive index sufficiently different from that of the interlayer to ensure total reflection. However, it is also conceivable that a layer of the interlayer adjacent to the glass pane, or even the entire interlayer, has the same refractive index as the glass pane, thereby preventing total reflection on the surface of the glass pane facing the interlayer. In this case, the reflecting interface is formed by the nearest surface where the transition to an optically less dense medium occurs. This interface can be located within the interlayer, on the surface of the further pane facing the interlayer, or even on the surface of the further pane facing away from the interlayer.

[0050] The light-conducting glass pane with the emissivity-reducing coating is preferably the inner pane of the laminated pane; the further pane is the outer pane. The second surface of the glass pane provided with the emissivity-reducing coating is the inner surface of the glass pane (inner pane), which faces away from the interlayer and the outer pane and is exposed to the interior. This achieves particularly good emissivity-reducing properties and particularly advantageously improves thermal comfort inside.

[0051] Alternatively, the light-conductive glass pane having the emissivity-reducing coating may be the outer pane and the further pane may be the inner pane, where again the second surface of the glass pane provided with the emissivity-reducing coating is the surface facing away from the interlayer, i.e., the outer surface exposed to the external environment.

[0052] The glazing element is provided with a light source suitable for coupling light into the glass pane. The light can be coupled in particular via a side edge surface of the glass pane, via an edge surface of a recess in the glass pane, or via one of the surfaces (main surfaces) of the glass pane using light injection means. The light is emitted into the glass pane, propagates within (at least) the glass pane, and is totally reflected at said interfaces (particularly the surfaces of the glass pane) against a medium with a lower optical density. More precisely, those parts of the light that strike the surface of interest with an angle of incidence exceeding the critical angle for total internal reflection are totally reflected. Since there is a transition from a medium with a higher optical density to a medium with a lower optical density, the critical angle for total internal reflection α T can be determined as follows:

[0053]

number

[0054] where n1 is the refractive index of the glass pane and n2 is the refractive index of the adjacent medium.

[0055] In certain embodiments of the present invention, the medium adjacent to the first surface of the transparent layer is different from the medium adjacent to the second surface. This is the case for a laminated pane, for example, a laminated pane consisting of two laminated glass panes, one of which serves as the transparent layer. In this case, one surface of the glass pane is adjacent to the ambient air, and the other surface is adjacent to the thermoplastic interlayer of the laminated pane. Therefore, different critical angles for total internal reflection occur at the two surfaces. In this case, light propagating within the glass pane strikes the surface at an angle of incidence greater than the relatively large critical angle for total internal reflection.

[0056] In this case, the refractive index and critical angle for total internal reflection also depend on the wavelength of the light from the light source. For example, at a wavelength of 589 nm, the refractive index of a pane of soda-lime glass is 1.52. If the interface is the exposed surface of the glass pane and the adjacent medium is the surrounding atmosphere (specifically, air, which has a refractive index of 1.00 at a wavelength of 589 nm), then the critical angle for total internal reflection is α T T = 41°. If the interface is the surface of a glass pane facing the interlayer of a laminated pane of PVB film (refractive index 1.48 at light wavelength 589 nm), the critical angle for total internal reflection is α T T = 77°. As is common in geometric optics, the angle of incidence is the angle between a ray of light impinging on a surface and the surface normal to the surface at the point of impact. The critical angle for total internal reflection is also determined by the surface normal.

[0057] In operation, the light source emits visible light, i.e., electromagnetic radiation within the visible spectrum, in particular within the range of 380 nm to 780 nm. The light source may have one or more emission bands, which are located within the visible spectrum and cover a part of it. However, the light source may also have a broadband emission band covering the entire visible spectrum. The emission band or bands, and thus the color of the emitted light, can be freely selected depending on the requirements of a particular application.

[0058] The glazing element may have a single light source or multiple light sources, the light of which is coupled into the glass pane at different points. The light from the light sources may be emitted into the glass pane directly or via optical elements, such as lenses or collimators.

[0059] The light source is preferably a light emitting diode (LED). The electroluminescent material of the light emitting diode can be, for example, an inorganic or organic semiconductor. In the latter case, they are also called organic light emitting diodes (OLED).

[0060] Coupling the light from the light source into the glass pane can be done in a variety of ways, but three embodiments are particularly preferred.

[0061] In a first preferred embodiment, the light source is associated with one of the two surfaces (main surfaces) of the glass pane. The light source is arranged on one of the surfaces and emits light into the glass pane through this surface. The glazing element comprises, on the side opposite the light source, a light entrance means through which the light from the light source is projected through the glass pane. The light entrance means is suitable for coupling light into the glass pane via a surface facing away from the light source and towards the light entrance means, so that at least a portion of the light propagates within the glass pane by total internal reflection. For this purpose, the light entrance means typically has a reflective surface that is appropriately inclined relative to the surface of the glass pane. The light entrance means can be, for example, in the form of a microprism film, a structured plastic film, or a plastic plate on which microprisms are arranged in a planar manner. The light entrance means reflects the light back into the glass pane, at an angle deviating from 0° relative to the surface normal. Light is refracted at the surface of the glass pane, and at least a portion of the light remaining within the glass pane strikes the opposite surface at an angle of incidence greater than the critical angle for total internal reflection, resulting in the light being coupled into the glass pane.

[0062] The light source is preferably arranged on an exposed surface of the glass pane or glazing element, so that it can be installed later or easily replaced in case of failure. Particularly preferred is the surface exposed on the inner side of the glass pane or glazing element, which is preferably also provided with an emissivity-reducing coating (second surface of the glass pane). The light entrance means is preferably arranged on the first surface of the glass pane.

[0063] In a second preferred embodiment, the light source is associated with a recess in the glass pane. Thus, the glass pane has a recess. This recess is preferably a hole, i.e., a passageway extending between the first and second surfaces of the glass pane. Alternatively, however, the recess can also be in the form of a blind hole (a pouch-like recess) that extends from the first or second surface into the glass pane but does not reach the opposite main surface and thus does not constitute a passageway. The blind hole preferably extends into the glass pane from the surface that forms the exposed face of the glazing element according to the invention. In that case, the light source can be installed later or easily replaced in case of a malfunction. In the case of a laminated pane, the surface of the glass pane facing away from the interlayer is the exposed surface. The recess can be created in the glass pane, for example, by mechanically drilling a hole or by laser beam machining. The recess is preferably round, but in principle can have any shape, such as a polygon. This refers to the base of the recess, which lies in the plane of at least one surface of the glass pane, where the recess is created.

[0064] The recess, whether in the form of a passage or a depression, is limited by a peripheral edge surface extending between the main surfaces of the glass panes. In the case of a passage, this is the only limiting surface of the recess. In the case of a pouch-like depression, there is a further limiting surface facing the main surfaces of the glass pane, to which the depression does not extend and which forms, so to speak, the bottom of the blind hole. If the glazing element has several light sources, a separate recess is preferably provided for each light source.

[0065] In this embodiment, the light source is associated with the edge surface of the recess and is suitable for coupling light into the glass pane via this edge surface. The light source itself may be arranged within the recess, so that it is located in a plane defined by the glass pane and emits light that directly strikes the edge surface. For example, the light source may be sandwiched within the recess or glued to the edge surface. It is also conceivable that the light source is located within a housing or holder that fixes it in place and that the housing or holder is inserted into the recess, preferably with a precise fit. However, alternatively, the light source may not directly illuminate the edge surface, but rather its radiation may first be deflected. It is also conceivable that the light source is located within a housing, one part of which is inserted within the recess while another part of the housing is located outside the recess. The light source is located within a part of the housing outside the recess, and the light is deflected by a reflective surface or waveguide within the housing so that it illuminates the edge surface of the recess. The housing is preferably attached to the exposed surface of the glass pane and extends from there into the recess.

[0066] In a third preferred embodiment, the light source is associated with a side edge surface of the glass pane and is suitable for coupling light into the glass pane via the side edge surface. The light emitted by the light source can directly impinge on the side edge surface. The light source can be located on a side of the glass pane in the plane defined by the glass pane. For this purpose, the light source can be directly attached to the side edge surface, for example, by gluing or clamping. Alternatively, the light source can be located in a housing or holder that is fixed in place, and the housing or holder is attached to the glass pane, for example, by gluing or clamping, so that the light source illuminates the side edge surface. However, it is also possible that the light source does not directly illuminate the side edge surface, but rather its radiation is first deflected. It is also conceivable that the light source is located in a housing that includes a reflective surface or a waveguide that shapes the beam path of the light. This housing is attached to the glass pane in such a way that the beam path directs the light toward the side edge surface of the glass pane. In that case, the light source itself does not need to be located on a side of the glass pane in the plane defined by the glass pane, but can be arranged, for example, in front of or behind the glass pane in the viewing direction. The housing is preferably attached to an exposed surface of the glass pane and extends therefrom to a side edge surface of the glass pane.

[0067] Combinations of the above embodiments are also conceivable, where there are multiple light sources whose light is coupled into the glass pane in different ways.

[0068] The glazing element (in particular the glass pane) is also provided with a light-scattering structure suitable for directing light coupled therein out of the glass pane via the first surface and / or the second surface, the light-scattering structure being arranged at or between one of the two totally internally reflecting interfaces.

[0069] The light-scattering structure is preferably in direct contact with one of the surfaces of the glass pane, so that light propagating through the glass pane strikes it. The light-scattering properties of the light-scattering structure prevent total internal reflection. The light-scattering structure represents, so to speak, a scattering center, at which the light is scattered and therefore not totally reflected. Since the scattering is not generally unidirectional, at least a portion of the scattered light leaves the glass pane. In this way, illumination may be realized or information or aesthetic forms may be expressed.

[0070] A surface of a glazing element covered with light-scattering structures appears to an observer as a light-emitting surface. This can be used, for example, for lighting (e.g., interior) or for realizing displays to present information or aesthetic forms. The light-emitting structures can be present in a single continuous area of ​​the glazing element or in multiple separate areas. Any shape or pattern can be realized with the light-scattering structures.

[0071] The light-scattering structure may be applied directly to or formed on the first or second surface of the glass pane. Alternatively, the light-scattering structure may be provided, for example, on a carrier foil that is fixed to the first or second surface, for example by adhesive bonding. If the glass element according to the invention is a laminated pane, the light-scattering structure may be applied to the surface of the thermoplastic interlayer that is in contact with the glass pane. Alternatively, the light-scattering structure (e.g., applied to a carrier foil) may be inserted between the glass pane and the interlayer.

[0072] In an advantageous embodiment, the light-scattering structure is in the form of an imprint, in particular an imprint on one of the surfaces of the glass pane, or—in the case of a laminated pane—an imprint on the surface of the interlayer facing the glass pane. The imprint on the glass pane is preferably in the form of a light-scattering enamel. This enamel can be applied, for example, using a screen printing method. It preferably comprises a glass frit, which is baked into the surface of the glass pane and roughened to create a light-scattering surface. The imprint on the interlayer can be achieved, for example, by printing a light-scattering printing paste onto the surface of a thermoplastic film using a screen printing method. During the production of a laminated pane, the film is inserted between the outer and inner panes to form the interlayer, with the printed surface facing the glass pane, in particular in direct contact with the glass pane. In an advantageous embodiment, the light-scattering structure is transparent, thereby not substantially restricting the view through the glazing element. Therefore, the imprint (enamel or printing paste) preferably does not contain pigments. However, opaque or translucent light-scattering structures containing pigments, for example white structures, are also conceivable.

[0073] However, the light-scattering structures may also be formed by roughening the relevant surface of the glass pane or interlayer. This roughening can be done mechanically (for example, by grinding techniques) or by laser beam machining. The advantage of laser beam machining, especially in the case of laminated panes, is that the light-scattering structures can be installed in the finished laminated pane, even if they are located inside the laminated pane, because the laser radiation can also be focused, for example, through a transparent glass pane, onto the plane of the inside of the laminated pane. Laser beam machining also makes it possible to form the light-scattering structures inside the glass pane rather than on the surface.

[0074] The glass pane is preferably made of soda-lime glass, which is commonly used for window panes. In principle, however, the glass pane may also be made of other types of glass (e.g. borosilicate glass, quartz glass, aluminosilicate glass). In a preferred embodiment, glass compositions are used which have a transmittance of more than 90% in the visible range of the light spectrum. The thickness of the glass pane can vary widely. Pane thicknesses of 0.5 mm to 10 mm, preferably 1 mm to 5 mm, are preferably used. The same applies to the further pane in the case of laminated panes; the material and thickness of the further pane and of the glass pane can be selected independently of each other.

[0075] The glass pane is preferably clear, so that light can advantageously propagate within the glass pane. In the case of a laminated pane, the further pane and interlayer can be clear, tinted, or colored. In particular, when the glazing element has a laminated pane and is used as a roof window in a vehicle, the laminated pane can have a tinted interlayer and / or a tinted further pane. In particular, when the glass pane is the inner pane of the laminated pane and faces the interior of the vehicle, and the further pane is the outer pane and faces the external environment, this allows for both high light intensity and a neutral color display, and the tinted interlayer or the tinted outer pane increases thermal comfort and protects vehicle occupants from glare, especially in strong sunlight. The tinted outer pane or the tinted interlayer preferably has a visible light transmittance of less than 50%, particularly preferably less than 20%.

[0076] The thermoplastic intermediate layer comprises at least one layer of a thermoplastic compound material, preferably ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), or polyurethane (PU), or a mixture, copolymer, or derivative thereof, with PVB being particularly preferred. The intermediate layer is typically formed from at least one thermoplastic film. The film thickness is preferably 0.3 mm to 2 mm, with standard thicknesses of 0.36 mm and 0.76 mm being particularly common. The intermediate layer may have multiple layers of thermoplastic material, for example, formed from multiple polymer films arranged flat on top of each other.

[0077] The glazing element preferably has an opaque masking area that cannot be seen through. This masking area is preferably arranged peripherally in the edge area and surrounds a central transparent see-through area in the manner of a frame. This is particularly common for vehicle windows. The masking area is preferably formed by an opaque cover print on the glass pane and / or on the further pane (in the case of laminated panes). The cover print is typically made of an enamel containing glass frit and pigments and is preferably applied using a screen printing method and then baked. In an alternative embodiment, the cover print is applied using a digital printing method and then baked.

[0078] The present invention also includes a method for making an illumination glazing element according to the present invention, comprising the steps of: (a) a glass pane is provided having a first surface and a second surface; (b) providing on a second surface of the glass pane an emissivity-reducing coating having exactly one electrically conductive layer based on a transparent conductive oxide, the electrically conductive layer having an imaginary component of the refractive index k such that k<0.035 applies within the wavelength range of 380 nm to 780 nm; (c) the glass pane comprises at least one light source, the light source being suitable for coupling light into the glass pane so that the light propagates within the glass pane, in particular by total internal reflection at the first and second surfaces.

[0079] The glazing element is provided with at least one light-scattering structure suitable for separating said light from the glass pane via the first surface and / or via the second surface, which may be performed between method steps (a) and (b), between method steps (b) and (c), or after method step (c).

[0080] The emissivity-reducing coating is preferably deposited on the substrate surface by a vapor deposition method, such as chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or atomic layer deposition (ALD). Physical vapor deposition (PVD), such as evaporative deposition, is particularly preferred, with cathode sputtering ("sputtering") and in particular magnetic field-assisted cathode sputtering ("magnetron sputtering") being more particularly preferred.

[0081] In a preferred embodiment of the method according to the invention, the emissivity-reducing coating is deposited by vapor deposition, in particular by magnetic field-assisted cathode sputtering. An electrically conductive layer according to the invention, with an imaginary component of the refractive index k of less than 0.035, can be achieved in particular by adding oxygen to the process gas in a proportion of 1% to 3% by volume. The electrically conductive layer is preferably deposited by magnetic field-assisted cathode sputtering in DC mode, and the glass pane is preferably not actively heated.

[0082] Preferably, the emissivity-reducing coating is subjected to a thermal post-treatment after deposition. Such methods for thermally tempering conductive coatings are known in principle to those skilled in the art. The inventors of the present invention have discovered that the refractive index according to the invention can be achieved relatively easily by heat-treating the emissivity-reducing coating.

[0083] If the glass element is a laminated pane, the pane is connected to the further pane via a thermoplastic interlayer. In that case, the light-scattering structure and the light-scattering or light-diffracting layer, or the opaque element, as already explained above, can be applied to the interlayer rather than to the pane, or can be inserted between the interlayer and the pane. The light source is preferably installed after lamination of the laminated pane.

[0084] Known lamination methods may be used, such as autoclave, vacuum bag, vacuum ring, calendar, vacuum laminator, or a combination thereof. Typically, the outer and inner panes are joined under the influence of heat, vacuum, and / or pressure.

[0085] The present invention also includes the use of the glazing element according to the present invention as a window pane for a vehicle. Particularly preferred use is as a roof window for a vehicle. The vehicle can in principle be any land vehicle, ship, or aircraft, preferably a passenger car, truck, or rail car. The glazing element can also be used in buildings, for example as a window pane, glass facade, or glass door in an exterior or interior area, in particular as a window pane for a building or interior. The glazing element can be used as furniture, electrical equipment, as a component of furniture, or as furniture.

[0086] The present invention will now be described in more detail with reference to the drawings and exemplary embodiments. The drawings are schematic and not to scale. The drawings do not limit the present invention in any way. [Brief explanation of the drawings]

[0087] [Figure 1] FIG. 1 shows a cross-section of a first embodiment of a glazing element according to the invention. [Figure 2] FIG. 2 is an enlarged view of a portion Z in FIG. [Figure 3] FIG. 3 shows a cross-section of a further embodiment of a glazing element according to the invention. [Figure 4] FIG. 4 shows a cross-section of a further embodiment of a glazing element according to the invention. [Figure 5] FIG. 5 shows a graph of the extinction coefficient k (the imaginary part of the complex refractive index) of a conventional ITO layer according to the present invention. [Figure 6] FIG. 6 is a graph of the real part of the complex refractive index n of a conventional ITO layer according to the invention from FIG. DETAILED DESCRIPTION OF THE INVENTION

[0088] 1 and 2 each show details of a first embodiment of a glazing element according to the invention. The glass element is in the form of a laminated pane, which has an inner pane, glass pane 2, connected to an outer pane 1 via a thermoplastic interlayer 3. The outer pane 1 and glass pane 2 are made of, for example, soda-lime glass and each have a thickness of, for example, 2.1 mm. The interlayer 3 is formed, for example, from a PVB foil having a thickness of 0.76 mm. The glazing element is shown flat, but may also be curved into a cylindrical or spherical shape depending on the intended use. The glazing element is intended, for example, as a roof window for a passenger car.

[0089] In the installed position, the outer pane 1 faces the exterior environment and the glass pane 2 faces the interior of the vehicle. The outer pane 1 has an outer surface I facing the exterior environment and an inner surface II facing the interior of the vehicle. Similarly, the glass pane 2 has two parallel main surfaces, specifically a first surface III constituting the exterior surface and a second surface IV constituting the interior surface.

[0090] The glass pane 2 functions as a light-conducting layer of the illumination glazing element. A light source 5 is attached to the second (inner) surface IV of the glass pane 2. Opposite the light source 5, a light-injection means 7 is attached to the first (outer) surface III of the glass pane 2. The light source 5 emits light through the glass pane 2 to the light-injection means 7. The light source 5 is in the form of a light-emitting diode. The light-injection means 7 is in the form of a microprism film with multiple reflective surfaces that are inclined with respect to surfaces III and IV. The reflected light then re-enters the glass pane 2 through the first surface III with a varied beam angle. In this way, the light is coupled into the glass pane 2 through the first surface III by the light-injection means 7. The light emission is indicated by arrows in the diagram. A portion of the light strikes surfaces III and IV of the glass pane 2 at an angle of incidence greater than the critical angle for total internal reflection (or greater than the highest critical angle for total internal reflection, since different adjacent media result in different critical angles for total internal reflection at the two surfaces III and IV). A portion of this light propagates within the glass pane 2 by undergoing repeated total internal reflections.

[0091] At the peripheral edge of the glazing element, an opaque cover print 9 is applied to the inner surface II of the outer pane 1. The light source 5 and the light entrance means 7 are discreetly arranged within this opaque edge area (masking area).

[0092] A first surface III of the glass pane 2 is provided with a plurality of light-scattering structures 6, at which the light is scattered and total internal reflection is prevented, and thus the light is directed away from the glass pane 2, in particular via the second surface IV, so that vehicle occupants perceive the surface with the light-scattering structures 6 as a light-emitting surface.

[0093] The second (inner) surface IV of the glass pane 2 is provided with an emissivity-reducing coating 4, the optical properties of which are optimized so as not to significantly reduce the intensity of the transmitted light or change its color. The emissivity-reducing coating 4 is in the form of a stack of thin layers. The individual layers can be seen in the enlarged view of Figure 2.

[0094] The emissivity-reducing coating 4 comprises a lower dielectric blocking layer 4.2, a lower dielectric antireflective layer 4.3a, an electrically conductive layer 4.1, an upper dielectric barrier layer 4.4, an upper dielectric antireflective layer 4.3b, and an anti-scratch layer 4.5. The lower dielectric blocking layer 4.2 has a refractive index of 1.9 or greater and prevents diffusion of alkali ions from the glass pane 2 into the layers above the blocking layer 4.2. The lower dielectric antireflective layer 4.3a has a refractive index of 1.6 or less; the upper dielectric antireflective layer 4.3b has a refractive index of 1.8 or less. The antireflective layers 4.3a and 4.3b increase transmittance through the pane and reduce reflectance. The upper dielectric barrier layer 4.4 regulates oxygen diffusion within the layer stack and has a refractive index of 1.9 or greater. The electrically conductive layer 4.1 is made of ITO and has an imaginary refractive index k of <0.035 within the wavelength range of 380 nm to 780 nm.

[0095] Figure 3 shows a further embodiment of a glazing element according to the invention. The glazing element has the same design in principle as the embodiment of Figure 1, but with a different type of light incidence. A light source 5 is attached to a side edge surface e of the glass pane 2 and emits light into the glass pane 2 via this side edge surface e. Again, part of the light strikes surfaces III, IV of the glass pane 2 at an angle of incidence greater than the (maximum) critical angle for total internal reflection and propagates within the glass pane 2 by repeated total internal reflection.

[0096] For simplicity, the side edge surfaces e are shown as flat, but in practice they are often convexly rounded as a result of edge grinding.

[0097] Figure 4 shows a further embodiment of a glazing element according to the invention. The glazing element has, in principle, the same design as the embodiment of Figures 1 and 3, but the light is introduced differently. A recess A is provided in the glass pane 2, which extends as a passageway completely through the glass pane 2, i.e., from its first surface III to its second surface IV. This recess A has, for example, a circular base and is surrounded by a peripheral edge surface i. A light source 5 is inserted in the recess A, for example by being glued to the edge surface i. Light is coupled into the glass pane 2 via the edge surface i. Here too, part of the light strikes the surfaces III and IV of the glass pane 2 at an angle of incidence greater than the (highest) critical angle for total internal reflection and propagates repeatedly through total internal reflection within the glass pane 2. [Example]

[0098] The structure of the emissivity-reducing coating will be explained below using examples according to the present invention and comparative examples. The layer structures shown should be understood as examples only. For example, the arrangement of the dielectric layers may have a relatively large number of layers or a relatively small number of layers. Also, the arrangement of the dielectric layers does not have to be symmetrical. Exemplary materials and layer thicknesses can be found in the examples below. The emissivity-reducing coating is applied to the second surface IV of the glass pane 2, which is positioned adjacent to the interior of the vehicle when the glazing element is installed in the vehicle.

[0099] The layer arrangement of the emissivity-reducing coating 4 on the glass pane 2 according to Examples B1 to B6 of the present invention, together with the materials and geometric layer thicknesses of the individual layers, is shown in Table 1. The dielectric layers can be doped independently of one another, for example with boron, titanium, zirconium, or aluminum. The electrically conductive layer 4.1, provided as an ITO layer, is deposited in a process gas with an oxygen content according to Table 1 by magnetic field-assisted cathode sputtering. The magnetic field-assisted cathode sputtering is carried out, for example, in an industrial plant in direct current mode (DC mode) without actively heating the glass pane 2 during deposition. Each glass pane 2 has a thickness of 2.0 mm and consists of soda-lime glass. Examples B1 to B3 and B4 to B6 each have the same layer stack, except that in the former case a thin TiO 3 film is used as the scratch-resistant layer 4.5. x In the latter case, there is no such scratch-resistant layer 4.5. Examples B1 to B3 and B4 to B6 differ from each other in the oxygen content during deposition of the ITO layer.

[0100] Table 2 shows further examples B7 to B12 according to the invention. Examples B7 to B9 and B10 to B12 differ from one another in the oxygen content during deposition of the ITO layer. Here, layer alternatives with relatively thick ITO are considered. Table 3 shows comparative examples V1 to V4, which are not according to the invention. In these comparative examples, the emissivity-reducing coatings 4 have the same basic structure as the examples according to the invention, but differ in the layer thickness and the oxygen content of the process gas during deposition of the electrically conductive layer 4.1 (ITO). The structure of the emissivity-reducing coating 4 in comparative example V1 corresponds to the layer structure of the emissivity-reducing coatings 4 of examples B1, B2, and B3, except that in V1 the oxygen content of the process gas during deposition of the ITO layer was 0%. Similarly, the layer structure of the emissivity-reducing coating 4 in comparative example V2 corresponds to the layer structure of B4, B5 and B6, the layer structure in V3 corresponds to the layer structure of B7, B8 and B9, and the layer structure in V4 corresponds to the layer structure of B10, B11 and B12, with the difference in each case being that in comparative examples V2, V3 and V4, the oxygen content in the process gas is 0% when depositing the ITO layer.

[0101] [Table 1]

[0102] [Table 2]

[0103] [Table 3]

[0104] Table 4 shows the maximum extinction coefficient k of the electrically conductive layer 4.1 in the visible light wavelength range of 380 nm to 780 nm for the oxygen content in the ITO process gas. max In Examples B1 to B12 according to the invention, the electrically conductive layer 4.1 has maximum extinction coefficients k of 0.021, 0.015, and 0.016 in the visible light wavelength range. max These values ​​are thus less than 0.035, which is a prerequisite for the examples according to the invention. Furthermore, the maximum extinction coefficients k of the electrically conductive layer 4.1 are shown in the wavelength ranges of 380 nm to 490 nm, 490 nm to 575 nm, and 600 nm to 700 nm. The examples according to the invention have a maximum extinction coefficient k of less than 0.020 in the wavelength range of 380 nm to 490 nm, a maximum extinction coefficient k of less than 0.015 in the wavelength range of 490 nm to 575 nm, and a maximum extinction coefficient k of less than 0.025 in the wavelength range of 600 nm to 700 nm. The comparative examples each have an extinction coefficient k greater than these values ​​in the specified wavelength ranges.

[0105] In Comparative Examples V1 to V4, the electrically conductive layer 4.1 has a maximum extinction coefficient k of 0.048 in the visible light wavelength range of 380 nm to 780 nm. max which is thus greater than 0.035, so the comparative example does not comply with the present invention.

[0106] [Table 4]

[0107] Table 5 summarizes some characteristic parameters of Examples B1 to B3 according to the present invention in comparison with Comparative Example V1. Reflectance R L and the color value of the reflected light a * and b * and reflection (R) below 8° on the emissivity-reducing coating as seen from inside the vehicle using standard illuminant D65 with a 10° detector, respectively. L(コーティング) , a * コーティング , b * コーティング ) and the reflection within the glass at the coating interface of less than 80° (R L(界面) , a * 界面 , b * 界面 ) is measured. L and color value a * and b * The values ​​of were determined by simulation using CODE software. The specific reflection angles are shown relative to the associated surface normal.

[0108] R L is a measure of reflectance to optical radiation, and R L(コーティング) must be as low as possible to avoid unwanted reflections inside the vehicle, while R L(界面) should be maximized with a view to optimizing the light intensity of the lighting glazing element. * a * b * The color value in a color spectrum is a measure of how neutral the reflection of light is; the value should be as close to 0 as possible.

[0109] For Examples B1-B3 and Comparative Example V1, the sheet resistance and emissivity after heat treatment were further determined and are shown in Table 5. Low values ​​of sheet resistance and emissivity allow for relatively high thermal comfort. Therefore, Examples B1 and B2 are preferred because they have high light reflectance and low emissivity within the glass.

[0110] [Table 5]

[0111] Tables 6 and 7 show the reflective properties of the coating from both the outside (coating) and inside (interface) for Examples B4 to B12 according to the invention and Comparative Examples V2 to V4.

[0112] All examples according to the invention have an optimized light intensity of the lighting glazing element and an R of more than 96%. L(界面) , and color value a from -1.7 to 0.0 * 界面 and b * 界面 At the same time, the reflectivity of the coating R L(コーティング) is less than 7% for clear glass, which is classified as low reflective. * コーティング and b * コーティング The color value a is within the range acceptable to the customer. * 界面 and b * 界面 is significantly more neutral for the examples according to the invention, which is important for light steering without color shift.

[0113] [Table 6]

[0114] [Table 7]

[0115] It should be noted that reflectance and color values ​​vary depending on the tinting level of the pane and can differ between single panes and laminated panes. Tables 5-7 examine single ultra-clear glass panes, while Table 8 examines laminated panes. The laminated pane includes a glass pane 2 made of ultra-clear glass bearing an emissivity-reducing coating 4 according to Examples B1, B2, and B3 of the present invention and Comparative Example V1, and an outer pane 1 made of ultra-clear glass connected to the glass pane 2 via a thermoplastic interlayer 3, which is made of polyvinyl butyral (PVB) and is deeply tinted. By deeply tinted, we mean that the visible light transmittance through the laminated pane is reduced, for example to about 6%, while a single pane achieves a visible light transmittance of, for example, about 92%, where visible light transmittance refers to the average transmittance in the wavelength range from 380 nm to 780 nm. This is particularly advantageous when the glazing element having the laminated pane is used as a roof window in a vehicle. Using tinted laminated panes instead of single panes significantly affects the reflective properties of the layers when viewed from the outside (the "coating"), but does not affect the reflective properties within the glass (the "interfaces"), which in turn determine the light guidance.

[0116] [Table 8]

[0117] FIG. 5 shows the extinction coefficient k as a function of wavelength for several TCO layers. The TCO layers are in the form of ITO layers deposited by magnetic field-assisted cathode sputtering. No oxygen (0% O2) was added to the process gas, as in Comparative Examples V1, V2, V3, and V4; 1.5% oxygen was added to the process gas, as in Inventive Examples B1, B4, B7, and B10; 3% oxygen was added to the process gas, as in Inventive Examples B2, B5, B8, and B11; and 4% oxygen was added to the process gas, as in Inventive Examples B3, B6, B9, and B12. The extinction coefficient k is shown as a solid line for 0% oxygen, a long-dashed line for 1.5% oxygen, a short-dashed line for 3% oxygen, and a dotted line for 4% oxygen. In an example according to the invention, the ITO layer has an imaginary component of the refractive index k of <0.035 within the wavelength range of 380 nm to 780 nm. Figure 5(b) details the values ​​from Figure 5(a) in the visible wavelength range of 380 nm to 780 nm. Figure 5(b) shows that the comparative example with 0% oxygen content is not in accordance with the present invention because the extinction coefficient k is not less than 0.035 throughout the entire wavelength range. However, the examples with oxygen contents of 1.5%, 3%, and 4% have extinction coefficients less than 0.035 throughout the entire wavelength range of 380 nm to 780 nm. Therefore, these are examples of the present invention. Note that these are merely exemplary values ​​that demonstrate how the oxygen content in a process gas can affect the extinction coefficient k.

[0118] Figure 6 shows a diagram of the real part of the refractive index n as a function of wavelength for the ITO layers of the example according to the invention and the comparative example not according to the invention of Figure 5. The refractive indices were each determined by ellipsometry. [Explanation of symbols]

[0119] (1) Outer pane (2) Glass pane / inner pane (3) Thermoplastic intermediate layer (4) Low-emissivity coating (4.1) Electrically conductive layer (4.2) Lower Dielectric Blocking Layer (4.3) Antireflection layer (4.3a) Bottom dielectric anti-reflection layer (4.3b) Top dielectric anti-reflection layer (4.4) Upper Dielectric Barrier Layer (4.5) Anti-scratch layer (5) Light source (6) Light scattering structure (7) Light entrance means (9) Cover printing (I) Outer surface of outer pane 1 (II) Inner surface of outer pane 1 (III) First surface of glass pane 2 (IV) the second surface of the glass pane 2 (A) Recess in glass pane 2 (e) Side edge surface of glass pane 2 (i) End surface of recess A Z enlarged area

Claims

1. A lighting glazing element, comprising a glass pane (2) having a first surface (III) and a second surface (IV), wherein the glazing element is - at least one light source (5) suitable for coupling light into said glass pane (2) so that said light propagates within said glass pane (2), in particular by total internal reflection at said first surface (III) and said second surface (IV), - provided with at least one light-scattering structure (6) suitable for separating said light from said glass pane (2) via said first surface (III) and / or said second surface (IV), - provided on said second surface (IV) of said glass pane (2) with at least one emissivity-reducing coating (4); wherein the emissivity-reducing coating (4) comprises exactly one electrically conductive layer (4.1) based on a transparent conductive oxide, the electrically conductive layer (4.1) having an imaginary component of the refractive index k such that k<0.035 applies within the wavelength range from 380 nm to 780 nm, Lighting glazing elements.

2. The electrically conductive layer (4.1) is made of indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO, SnO ２ :F), aluminum-doped zinc oxide (AZO, ZnO:Al), gallium-doped zinc oxide (GZO, ZnO:Ga), antimony-doped tin oxide (ATO, SnO ２ : Sb), and / or niobium-doped titanium oxide (TiO ２ 2. The lighting glazing element according to claim 1, based on Indium Tin Oxide (ITO), preferably Indium Tin Oxide.

3. 3. Illumination glazing element according to claim 1 or 2, wherein the emissivity-reducing coating (4) has a specific sheet resistance of less than 250 μΩ·cm, preferably less than 200 μΩ·cm.

4. 4. Illumination glazing element according to any one of claims 1 to 3, wherein the electrically conductive layer (4.1) has an imaginary component k of the refractive index, such that k<0.025, preferably k<0.020, applies in the wavelength range from 600 nm to 700 nm.

5. Illuminating glazing element according to any one of claims 1 to 4, wherein the electrically conductive layer (4.1) has a thickness of 60 nm to 100 nm, preferably 65 nm to 95 nm.

6. The emissivity-reducing coating (4) comprises, starting from the glass pane (2), at least: a lower dielectric blocking layer (4.2) against ion diffusion, with a refractive index greater than or equal to 1.9; a lower dielectric anti-reflection layer (4.3a) with a refractive index of less than or equal to 1.6, said electrically conductive layer (4.1), - an upper dielectric barrier layer (4.4) for controlling the diffusion of oxygen, with a refractive index of 1.9 or higher; an upper dielectric anti-reflection layer (4.3b) having a refractive index of less than or equal to 1.8; 6. The lighting glazing element according to claim 1, wherein

7. 7. Illumination glazing element according to claim 6, wherein the lower dielectric blocking layer (4.2) is based on silver and preferably has a thickness of 10 nm to 40 nm, particularly preferably 15 nm to 35 nm.

8. The lower dielectric anti-reflective layer (4.3a) is made of SiO ２ 8. The lighting glazing element according to claim 6 or 7, preferably having a thickness of 5 nm to 25 nm, particularly preferably 5 nm to 20 nm.

9. 9. The lighting glazing element according to claim 6, wherein the upper dielectric barrier layer (4.4) is based on silicon nitride and preferably has a thickness of 5 nm to 40 nm, particularly preferably 8 nm to 25 nm, and even more preferably 9 nm to 15 nm.

10. The upper dielectric anti-reflective layer (4.3b) is made of SiO ２ 10. The lighting glazing element according to claim 6, wherein the thickness is preferably from 45 nm to 100 nm, particularly preferably from 50 nm to 75 nm.

11. 11. The lighting glazing element according to any one of claims 1 to 10, wherein the glass pane (2) is an inner pane of a laminated pane and is connected to an outer pane (1) via a thermoplastic interlayer (3), the second surface (IV) of the glass pane (2) facing away from the interlayer (3).

12. 12. An illuminated glazing element according to any one of claims 1 to 11, wherein the light source (5) is arranged on one of the surfaces (III, IV), in particular on the second surface (IV), and the glazing element is provided with light entrance means (7) facing the light source (5), in particular on the first surface (III), which light entrance means is suitable for coupling the light impinging on the light entrance means (7) through the glass pane (2) into the glass pane (2).

13. 12. An illuminated glazing element according to any one of claims 1 to 11, wherein the glass pane (2) has a recess (A) bounded by a peripheral edge surface (i), and the light source (5) is arranged in or on the recess (A) and is thereby suitable for coupling light into the glass pane (2) via the edge surface (i).

14. 12. The illuminated glazing element according to any one of claims 1 to 11, wherein the at least one light source (5) is arranged on a side edge surface (e) of the glass pane (2), extending between the first surface (III) and the second surface (IV), whereby the light source is suitable for coupling light into the glass pane (2) via the side edge surface (e).

15. 1. A method for making an illumination glazing element, comprising: (a) a glass pane (2) is provided having a first surface (III) and a second surface (IV); (b) on the second surface (IV) of the glass pane (2) an emissivity-reducing coating (4) is provided, which comprises exactly one electrically conductive layer (4.1) based on a transparent conductive oxide, said electrically conductive layer (4.1) having an imaginary component k of the refractive index such that k<0.035 applies within the wavelength range from 380 nm to 780 nm; (c) the glass pane (2) comprises at least one light source (5) suitable for coupling light into the glass pane (2) so that the light propagates within the glass pane (2), in particular by total internal reflection at the first surface (III) and the second surface (IV), wherein said glazing element is provided with at least one light-scattering structure (6) suitable for separating said light from said glass pane (2) via said first surface (III) and / or via said second surface (IV), Method for making lighting glazing elements.

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