Composite pane having a plurality of reflective structures for 3-dimensional illumination

Abstract

The invention relates to a composite pane (1), comprising – a light guide (2) having a first surface (III) and a second surface (IV), – an intermediate layer (3) having at least one first light-guiding layer (3.1) directly adjacent to the first surface (III), – an outer pane (4) and – at least one first light-scattering structure (5.1) and one second light-scattering structure (5.2), wherein the first light-scattering structure (5.1) is arranged on the first surface (III) or the second surface (IV), wherein the second light-scattering structure (5.2) is arranged on or within the first light-guiding layer (3.1) and is arranged closer to the outer pane (4) than the first light-scattering structure (5.1), wherein the refractive indices of the first layer (3.1) and of the light guide (2) differ at most by 0.1 and the light guide (2) and the outer pane (4) are separated at least by the first light-guiding layer (3.1), wherein the intermediate layer (3) has at least one further light-guiding layer (3.2) which is applied on a surface of the first layer (3.1) facing away from the light guide (2) and has at least one further light-scattering structure (5.3).

Description

[0001] Composite pane with multiple reflective structures for 3-dimensional illumination

[0002] The invention relates to a composite pane, its production and use, and an illuminable glazing element.

[0003] Illuminated glazing elements are well known as such. They are equipped with a light source whose light is coupled into a light guide, usually a glass pane, and spreads through total internal reflection. The light is often recoupled from the light guide by light-diffusing structures, thus creating the illumination. The shape of the light-diffusing structures can be freely selected, allowing illuminated surfaces of any shape, for example, as a pattern. Illuminated glazing elements of this type are known, for example, from WO2014 / 060409A1 or WO2014 / 167291 A1.

[0004] In the automotive sector, such illuminated glazing elements are particularly interesting for roof windows. The glazing element is typically designed as a composite pane, with the light coupled into the inner pane. However, such illuminated glazing elements can also be used for other vehicle windows, as well as for windows in buildings and architecture, or in furnishings. The light-diffusing structures create illuminated surfaces that can be used to display aesthetically pleasing shapes and patterns or to display information, for example, directional arrows, status indicators, warning notices, price lists, or similar.

[0005] There are various known ways to couple the light from the light source into the light guide formed as a glass pane. The light source (typically an LED) can be positioned at the side edge, so that the light is radiated through the side edge into the glass pane and thus coupled into the light. However, such coupling is often impossible, particularly because the side edge of the glass pane is usually ground to reduce the risk of injury, which results in the side edge becoming cloudy.

[0006] Alternatively, the light source can be arranged in a recess in the glass pane (for example, in a feedthrough), so that the light is radiated into the glass pane via the side edge surface of the recess and thus coupled into the glass pane. However, drilling the recess makes the production of such a glazing element considerably more complex and is associated with the risk of a comparatively high level of rejects due to glass breakage.

[0007] US2020241189A1 proposes coupling light through a main surface of the glass pane. For this purpose, a reflective structure is attached to the surface of the glass pane facing away from the light source. The reflective structure has sections inclined relative to one another. The light source irradiates the reflective structure through the glass pane, with the light being reflected at the inclined sections in such a way that it propagates through the glass pane as a result of total internal reflection. The application of reflective structures to both surfaces of the light guide is known from WO2022095959A1.

[0008] WO2016 / 102799A1 relates to a composite pane that can be illuminated by both its outer and inner panes. For this purpose, light from two different light sources is coupled into the respective pane. A light barrier ensures that no light can pass to other layers / panes, thus preventing mixing of the light from the two different light sources. The coupling means for illumination are arranged and designed such that a large portion of the light from the composite pane is coupled out via the pane into which the light was coupled.

[0009] DE102015219586A1 discloses a composite pane with a light-conducting intermediate layer and a light-conducting pane. Both the light-conducting intermediate layer and the light-conducting pane are provided with light extraction means. The composite pane is intended to be equipped with multiple light sources, with each light source either radiating light into the intermediate layer or coupling light into the pane. To reduce light mixing from the light coupled into the inner pane to the light-conducting layer, the layer and pane have significantly different refractive indices.

[0010] WO2022 / 095959A1 relates to a composite pane in which light is coupled into a light guide. The light guide can be provided with outcoupling means on two opposite surfaces.

[0011] In all generic solutions for coupling light, a significant portion of the light emitted by the light source is lost, since it is technically almost impossible to couple the light 100%, or even if the light is already coupled into the light guide, a partially undesired coupling of the light is possible.

[0012] The object of the present invention is to provide an improved laminated pane for an illuminated glazing unit in which the light from a light source, which is intended to be coupled into the laminated pane, can be used more efficiently and which is easy to manufacture.

[0013] The object of the present invention is achieved by a composite pane according to claim 1. Preferred embodiments emerge from the subclaims.

[0014] The composite pane according to the invention comprises at least one light guide with a first surface and a second surface, an intermediate layer which has at least one first light-conducting layer directly adjacent to the first surface of the light guide, a first light-scattering structure, a second light-scattering structure and an outer pane. The first light-scattering structure is arranged on the first surface or the second surface of the light guide. The second light-scattering structure is arranged, preferably applied, on the first light-conducting layer or arranged within the first light-conducting layer. This means that the second light-scattering structure is arranged, preferably applied, either on the surface of the first light-conducting layer facing towards the light guide or on the surface of the first light-conducting layer facing away from the light guide.Alternatively, the second light-scattering structure is arranged within the first light-conducting layer. The refractive index of the first layer and the refractive index of the light guide differ from each other by a maximum value of 0.1. The second light-scattering structure is arranged closer to the outer pane than the first light-scattering structure. In other words, the second light-scattering structure is offset in the orthogonal direction closer to the outer pane than the first light-scattering structure. The orthogonal direction refers to the direction orthogonal to the surface of the composite pane. According to the invention, this means that if the first light-scattering structure is arranged on the first surface of the light guide, the second light-scattering structure cannot be arranged on the surface of the first layer facing the light guide.The second light-scattering structure is preferably arranged at least 0.1 mm, particularly preferably at least 0.2 mm, closer to the outer pane than the first light-scattering structure. According to the invention, the intermediate layer additionally comprises at least one further light-conducting layer (hereinafter referred to as the second light-conducting layer). The second light-conducting layer is applied flatly to the first surface of the first layer (i.e., the surface of the first layer facing away from the light guide) or immediately adjacent thereto. The second light-conducting layer has at least one further (third) light-scattering structure. This at least third light-scattering structure is preferably applied to the first surface or the second surface of the second layer.The second light-conducting layer preferably has a refractive index that differs by a maximum of 0.1 from the refractive index of the first layer and / or that differs by a maximum of 0.1 from the refractive index of the light guide. The second layer particularly preferably has substantially the same refractive index, most preferably the same refractive index, as the first layer; in particular, the second layer is made of the same material as the first layer.

[0015] According to the invention, the first light-conducting layer and the second light-conducting layer of the intermediate layer are arranged between the outer pane and the light guide. The light guide and the outer pane are thus separated from each other at least by the first and second layers.

[0016] The light guide is preferably the inner pane of the composite pane, and the intermediate layer is arranged between the inner pane and the outer pane. Alternatively, the light guide is arranged between the inner pane and the outer pane, with the light guide preferably being arranged within the intermediate layer. The light guide can therefore be the inner pane of the composite pane; however, it can also be arranged between a separate inner pane and the outer pane, preferably within the intermediate layer. If the light guide is arranged between the inner pane and the outer pane, the intermediate layer preferably has at least one further layer extending beyond the second layer. The first and second layers of the intermediate layer are arranged between the light guide and the outer pane, whereas the further layer is preferably arranged between the inner pane and the light guide.The layers of the intermediate layer bond the outer pane, the inner pane and the light guide together.

[0017] For the purposes of the invention, “immediately adjacent” means, in the case that “an element A is immediately adjacent to an element B”, that element A is at least partially in direct spatial contact with element B. In relation to the first layer and the light guide, this means that the first layer is arranged in direct spatial contact with the light guide at least in one region, wherein in other regions, for example, light-scattering structures can also be arranged between the first layer and the light guide. Preferably, the light guide and the first layer have a contact area of ​​at least 50%, particularly preferably at least 70%. In other words, the light guide and the first light-conducting layer are in direct contact with one another over at least 50% of their area, particularly preferably over at least 70% of their area.In particular, the first surface of the light guide and the surface of the first layer facing the light guide are arranged essentially congruently and are in direct contact over their entire surface, with the exception of any light-scattering structures that may be present. Independently of this, the first layer and the second layer preferably have a contact area of ​​at least 50%, particularly preferably at least 70%. The size of the contact area of ​​any adjacent further light-conducting layers that may be present is preferably likewise at least 50%, preferably at least 70%. In the case of unequal areas of two directly adjacent layers (or light guide with a first layer), the percentage always refers to the layer with the larger area.

[0018] The laminated pane is intended to separate an interior space from the exterior environment in a window opening of a vehicle or building. In this context, “inner pane” within the meaning of the invention refers to the pane facing the interior (vehicle interior). “Outer pane” refers to the pane facing the exterior environment. However, the invention is not restricted to this. The inner pane has an interior-side surface facing away from the intermediate layer and an exterior surface facing the intermediate layer. If the light guide is also the inner pane of the laminated pane, the first surface of the light guide is the exterior surface of the inner pane and the second surface is accordingly the interior-side surface of the inner pane. The interior-side surface of the inner pane is also simultaneously the interior surface of the laminated pane.The outer pane has an outer surface facing away from the intermediate layer and an interior surface facing the intermediate layer. The outer surface of the outer pane is also the outer surface of the laminated pane.

[0019] For the purposes of the invention, "light guide" refers to a light-conducting medium, preferably a glass pane or a plastic pane, which is designed such that light can be coupled into the light guide using the effect of total internal reflection and is also suitable for guiding coupled light. The principle of light guidance using total internal reflection is generally known to those skilled in the art and is described in more detail, for example, in WO2008 / 047442A1, JP2011086547A, or JP2015043321A. The light guide is thus designed such that the light from a light source can be coupled into the light guide and propagate therein.

[0020] For the purposes of the invention, “light-scattering structure” means a structure suitable for coupling the light out of the light guide or out of the at least first and second light-conducting layers. According to the invention, at least one first light-scattering structure is arranged on the second surface or the first surface of the light guide. The light guide can have a plurality of light-scattering structures in different regions of the light guide. The light guide preferably has at least one further light-scattering structure, particularly preferably at least two further light-scattering structures, in particular at least three further light-scattering structures, on its second surface or its first surface. In-coupled light is therefore coupled out of the light guide via the second surface or the first surface of the light guide at the light-scattering structure.The at least second light-scattering structure can be arranged on the second surface of the first layer facing the light guide or on the first surface of the first layer facing away from the light guide. It is also possible for the second light-scattering structure to be arranged within the first layer, i.e. to be completely enclosed by the first layer. Further light-scattering structures can be arranged on the first layer or within the first layer. Preferably, at least one further light-scattering structure, particularly preferably at least two further light-scattering structures, in particular at least three further light-scattering structures, is arranged on the first layer or within the first layer. It is understood that the first light-scattering structure and the second light-scattering structure only extend over a region of the light guide orthe first layer and cannot extend over the entire surface, since otherwise no coupling and propagation of the light by means of total reflection would be possible.

[0021] According to the invention, a light-scattering structure arranged on the surface of the first light-conducting layer facing the light guide is automatically arranged between the light guide and the first layer. This light-scattering structure is thus also arranged on the first surface of the light guide. This can also be applied to further light-scattering structures arranged, for example, between the first light-conducting layer and another light-conducting layer, meaning that these further light-scattering structures are arranged both on the first layer and on the further layer.

[0022] It is technically almost impossible to fully couple the light radiated into the light guide by a light source using the effect of total internal reflection. Residual light is radiated into the surrounding layers or the external environment, either directly or after several reflection cycles in the light guide. Surprisingly, the inventors discovered that a significant portion of the light radiated into a surrounding light-guiding layer with a similar refractive index to that of the light guide is coupled into the surrounding layer. Light-guiding layers adjacent to the light guide thus become a light-guiding medium for the light emitted by the light guide. The light thus coupled into the surrounding layers is not lost and can also illuminate the composite pane by means of light-scattering structures.Another major and completely surprising advantage was that by coupling the light out at different layer levels of the composite pane, a 3-dimensional lighting effect is created for the viewer, which can improve the user experience.

[0023] In a preferred embodiment of the invention, the intermediate layer, in addition to the first and second layers, additionally comprises at least one further light-conducting layer, preferably at least two further light-conducting layers, in particular at least three further light-conducting layers. The at least one further layer is applied flatly to the first surface of the second layer (i.e., the surface of the first layer facing away from the light guide) or immediately adjacent thereto. If there is more than one further layer, all further layers, including the second layer, are preferably applied flatly as a layer sequence to the first surface of the first layer.

[0024] Each further layer, including the second layer, preferably has at least one further light-scattering structure, which is preferably applied to the first surface or the second surface of the respective further layer. The second surface of each further layer is the surface facing the light guide. The first surface of each further layer is the surface facing away from the light guide. Each further light-conducting layer provided with at least one light-scattering structure preferably has essentially the same refractive index, particularly preferably the same refractive index, as the first layer; in particular, all further layers are made of the same material as the first layer. “Essentially the same refractive index” in this sense means that said light-conducting layers differ in refractive index by a maximum value of 0.02.The light-scattering structures of the additional light-conducting layers (including the second light-conducting layer) are preferably arranged at different distances from the outer pane, at least in part, and particularly preferably all of them. During lamination, the additional light-conducting layers merge with the first layer to form a continuous layer. The light that passes from the light guide into the continuous layer is thus reflected between the interfaces, i.e., the second surface of the light guide and the surface of the continuous layer facing the outer pane. In this way, the light-scattering structures can be arranged very well within the intermediate layer, resulting in an even stronger 3-dimensional impression for the viewer. The interfaces of the continuous layer refer to those surfaces that directly border the outer pane or the light guide.

[0025] In a preferred embodiment, the intermediate layer has at least one further light-conducting layer (also called a third light-conducting layer). The third light-conducting layer is preferably applied to a surface of the second layer facing away from the light guide and has at least one further (fourth) light-scattering structure. This at least fourth light-scattering structure is preferably applied to the first surface or the second surface of the third layer. The third light-conducting layer preferably has a refractive index that differs by a maximum of 0.1 from the refractive index of the second layer and / or that differs by a maximum of 0.1 from the refractive index of the first layer.The third layer particularly preferably has substantially the same refractive index, very particularly preferably the same refractive index, as the second layer, in particular the third layer is made of the same material as the second layer.

[0026] If the intermediate layer has further light-conducting layers in addition to the first light-conducting layer, which are arranged as a layer sequence on the first layer, it is understood that these layers merge into a “continuous layer” during lamination. The continuous layer is formed from all light-conducting layers arranged between the light guide and the outer pane. At least the first and second layers therefore merge into a continuous layer during lamination. In a preferred embodiment, all light-scattering structures are arranged such that they are not congruent with one another when viewed through the composite pane. In other words, for example, the first light-scattering structure is not congruent with the second light-scattering structure when viewed through the composite pane.In particular, however, the first light-scattering structure and the second light-scattering structure can be arranged such that they overlap with each other in certain regions or when viewed through the laminated pane. Overlapping of the first light-scattering structure with any additional light-scattering structures is also possible. Likewise, overlapping of the second light-scattering structure with any additional light-scattering structures is also possible. This arrangement allows the light emitted by the light-scattering structures to be clearly visible even when viewed from an oblique angle onto the laminated pane.

[0027] In a first embodiment, the light guide is not the inner pane of the composite pane, but is arranged between the inner pane and the outer pane. The light guide is preferably arranged such that the second surface of the light guide faces the inner pane. Conversely, this means that the at least first layer and second layer are arranged between the light guide and the outer pane. Particularly preferably, the intermediate layer has at least one further layer which is arranged between the light guide and the inner pane. This layer preferably does not have a light-scattering structure, but serves to connect the light guide to the inner pane as an adhesive layer. Alternatively, this further layer can have at least one further light-scattering structure.The layer arranged between the light guide and the inner pane is also not necessarily a light-conducting layer unless it has a light-scattering structure. It can therefore deviate from the refractive index of the light guide by more than 0.1. It can also have a tint.

[0028] In an alternative second embodiment, the light guide represents the inner pane of the composite pane, so that the intermediate layer with the first layer is arranged between the outer pane and the light guide. This reduces the number of elements of the composite pane, simplifying production.

[0029] Light coupled into the light guide and the first layer, or possibly the continuous layer of the intermediate layer, propagates through the light guide and the first layer or the continuous layer until it either hits the side edge surface of the light guide, the first layer, or the continuous layer and is decoupled there, or encounters a light-scattering structure. The light-scattering structures interrupt total internal reflection through light scattering, causing the light to be decoupled from the light guide or the intermediate layer via the relevant surface.

[0030] In a preferred embodiment, the first light-scattering structure is arranged on the first surface of the light guide. Particularly preferably, at least one further light-scattering structure is arranged on the first surface of the light guide. Very particularly preferably, at least two, in particular at least three, further light-scattering structures are arranged on the first surface and also at least two, in particular at least three, further light-scattering structures are arranged on the second surface of the light guide. In the embodiment described here, the second light-scattering structure is arranged on the first surface of the first layer. The at least first light-scattering structure of the light guide on the first surface or the second surface of the light guide can, for example, be introduced into the surface of the light guide by roughening.Alternatively, the at least first light-scattering structure of the light guide can also be printed onto the first surface or the second surface. Alternatively, the first light-scattering structure of the light guide can also be applied, preferably printed, onto the surface of the first layer facing the light guide, wherein the at least first light-scattering structure is arranged in direct spatial contact with the first surface of the light guide. When the light propagating in the light guide strikes the light-scattering structure, it is scattered, preventing total internal reflection and causing the scattered light to be coupled out and exit the composite pane.

[0031] The light-diffusing structures appear as a luminous surface of the composite pane. This can be used, for example, to illuminate an interior space and, in particular, to display symbols or patterns that serve to convey information or may be intended for purely aesthetic reasons. The light-diffusing structure allows for the realization of any shape or pattern.

[0032] The first light-scattering structure can be applied directly to the first surface of the light guide or formed there. Preferably, a further structure is also applied to the second surface of the light guide or formed there. The first light-scattering structure can also be provided, for example, on a film that is attached to the second or first surface of the light guide, for example by gluing.

[0033] The second light-scattering structure can, for example, be provided as a film. The further light-scattering structures can likewise be provided as a film. The second light-scattering structure, as a film, is arranged, for example, between the light guide and the first layer, wherein the first structure in this case is arranged on the second surface of the light guide. Alternatively or additionally, the second light-scattering structure, as a film, can also be arranged between the first layer and the second light-conducting layer. Further light-scattering structures, which are designed as films, can also be arranged between individual layers of a layer sequence of further light-conducting layers. Light-scattering structures, as films, can also be arranged within the first layer and / or further layers. The films can, for example, be arranged by means of impressions within the respective layer.In this case, the respective layer completely encloses the film. This arrangement of the films can create a particularly powerful 3D light effect.

[0034] In an advantageous embodiment, the first light-scattering structure is formed as a print on the first surface of the light guide, the second surface of the light guide, or on the surface of the first layer facing the light guide. If the light guide is a glass pane, then a print on this is preferably formed as a light-scattering enamel. This enamel can be printed, for example, using a screen printing process. It preferably contains glass frits that are burned into the surface of the glass layer, creating a roughened and therefore light-scattering surface. If the first light-scattering structure is formed as a print on the first layer, then this is preferably achieved by printing the second surface of the first layer with a light-scattering, transparent printing paste.

[0035] In a further embodiment, the second light-scattering structure is printed on the first layer. The print on a light-conducting layer, regardless of whether it is a first light-scattering structure, a second light-scattering structure, or a further light-scattering structure, can be realized by printing a surface of the layer with a light-scattering printing paste. In an advantageous embodiment, the light-scattering structure is transparent so that it does not significantly restrict visibility through the laminated pane. The print (printing paste) therefore preferably contains no pigment. However, opaque or semi-transparent light-scattering structures with pigments are also conceivable, for example white structures. The print can also create a colored tint, i.e. at least not completely block visibility through the laminated pane, but allow it to appear in one or more color tints.The printing paste preferably contains dyes or color pigments if it is opaque, semi-transparent or tinted.

[0036] Light-scattering structures arranged on the light guide, which is designed as a glass or plastic pane, can also be formed by roughening the relevant surface of the light guide. This roughening can be done mechanically (e.g., by grinding techniques) or by laser processing. Laser processing has the advantage, particularly in the case of a composite pane, that the light-scattering structure can also be incorporated into the finished laminated composite pane, even if it is to be located inside the composite pane, since the laser radiation can also be focused onto a plane inside the composite pane. Laser processing also makes it possible to form at least the first light-scattering structure not on a surface, but inside the light guide.

[0037] The thickness of the outer pane is preferably from 0.5 mm to 10 mm, particularly preferably from 1 mm to 5 mm. The outer pane is preferably made of soda-lime glass. The intermediate layer has a thickness of, for example, 0.3 mm to 1.0 mm (sum of the thicknesses of all layers of the intermediate layer). The intermediate layer is preferably at least partially, particularly preferably completely, a thermoplastic intermediate layer, as is particularly advantageous for composite panes. In particular, the intermediate layer is formed from at least the first layer, which is based, for example, on polyvinyl butyral (PVB), ethylene vinyl acetate (EVA) or polyurethane (PU). The first light-conducting layer and / or the second layer preferably contains PVB or PET. Particularly preferably, the first light-conducting layer and / or the second light-conducting layer is based on PVB or PET.“Formed on the basis of a material” means in the sense of the invention that the film consists predominantly of the said material, i.e. the proportion of the material is more than 50 wt. %, preferably more than 60 wt. %. In addition, the layer can contain further components, for example plasticizers, stabilizers, UV or IR blockers. The further layers of the intermediate layer are also preferably formed on the basis of polyvinyl butyral (PVB), ethylene vinyl acetate (EVA) or polyurethane (PU). The first layer and any further layers present independently of one another preferably have a thickness of 0.05 mm to 1.0 mm, particularly preferably of 0.1 mm to 0.8 mm, in particular of 0.2 mm to 0.3 mm. If the light guide is a glass pane, it is preferably made of soda-lime glass, as is usual for window panes.Alternatively, the light guide can also be made of other types of glass, such as borosilicate glass, aluminosilicate glass, or quartz glass. If the light guide is a plastic pane, it is preferably made of a clear, rigid plastic, particularly preferably polycarbonate (PC) or polymethyl methacrylate (PMMA). If the light guide is the inner pane of the composite pane, the thickness of the light guide is preferably between 0.5 mm and 10 mm, particularly preferably between 1 mm and 5 mm.

[0038] If the light guide is arranged between the inner pane and the outer pane, the light guide preferably has a thickness of 0.03 mm to 1.5 mm, particularly preferably of 0.1 mm to 1 mm. The light guide is preferably made of soda-lime glass or, alternatively, of other types of glass, for example borosilicate glass, aluminosilicate glass or quartz glass. The light guide can also be a flexible light guide film and function as a transparent layer, for example a PET film with a thickness of 30 μm to 200 μm. The thickness of the outer pane and the inner pane is preferably, independently of one another, from 0.5 mm to 10 mm, particularly preferably from 1 mm to 5 mm. The outer pane and the inner pane are preferably made of soda-lime glass. The thickness of the intermediate layer is, for example, from 0.3 mm to 1.0 mm and is preferably based on polyvinyl butyral (PVB), ethylene vinyl acetate (EVA) or polyurethane (PU).Preferably, the first and / or second layer contains PVB, and any additional light-conducting layers contain PVB. The first layer and / or the second layer, as well as any additional layers present, independently of one another, preferably have a thickness of 0.05 mm to 1.0 mm, particularly preferably of 0.1 mm to 0.8 mm, in particular of 0.2 mm to 0.3 mm.

[0039] The light guide is preferably clear and has no significant tints or colorings in order to make the light propagation efficient. The outer pane can also be clear or tinted or colored. The first layer is preferably clear and has no significant tints or colorings in order to make the light propagation efficient. The second layer is preferably clear and has no significant tints or colorings in order to make the light propagation efficient. The further layers, provided they have a light-diffusing structure, are preferably clear and have no significant tints or colorings. According to the invention, the first light-guiding layer has a refractive index which differs from the refractive index of the light guide by a maximum of 0.1, preferably a maximum of 0.05, particularly preferably a maximum of 0.01.The further light-guiding layers, including the second layer, preferably have a refractive index which differs from the refractive index of the light guide by a maximum of 0.1, preferably by a maximum of 0.05, particularly preferably by a maximum of 0.01. In particular, the further layers have the same refractive index as the light guide. The refractive index of the first light-guiding layer and of any further light-guiding layers is preferably the same as or higher than the refractive index of the light guide. Preferably, the first layer and all further light-guiding layers have the same refractive index. Particularly preferably, the first layer and all further light-guiding layers are made of the same material. This is advantageous for light coupling with a high yield, wherein residual light components also significantly penetrate into the first layer orIf additional light-conducting layers are present, they can spread into the continuous layer. The first and / or second light-conducting layer is preferably a thermoplastic layer, in particular it is formed from PET or PVB. Any additional light-conducting layers present are preferably also thermoplastic layers, in particular they are formed from PET or PVB.

[0040] To ensure particularly advantageous light propagation between the light guide and the light-guiding layer, the difference in refractive index between the light guide and the light-guiding layer should not be greater than 0.1, and preferably less than 0.05. The greater the difference in the refractive indices, the more likely it is that light coupled into the light guide, for example, will not pass from the light guide to the light-guiding layer during propagation. With refractive indices greater than 0.1, a large portion of the coupled-in light remains in the light guide or the light-guiding layer into which the light was coupled. In order to achieve sufficient light intensity, it is therefore usually necessary to use a separate light source for coupling into each layer.A major advantage of the invention is that it is sufficient to simply couple light into the light guide and, due to the small difference in refractive index, this light is transferred to the light-guiding layer to a significant extent. This principle also applies to any additional light-guiding layers that may be present. The fact that the effect actually occurs as described can be illustrated using the principle of total internal reflection. The first surface and the second surface of the light guide represent interfaces to the adjacent medium. The second surface of the light guide is the interface to the first light-guiding layer. The first surface of the light guide is, for example, the interface to the surrounding atmosphere. Typically, the medium adjacent to the first surface (for example, the atmosphere of the interior) has a different refractive index than the light guide.This difference in refractive index results in a critical angle of total reflection, which is determined as a. T= arcsin(— ), where ni is the refractive index of the optically denser medium and n2 is the refractive index of the optically rarefying medium. In the case of the interface between the light guide and air, the refractive index of the light guide is m and the refractive index of the air is n2. If light hits the interface at an angle of incidence greater than the critical angle, the light is completely reflected (total internal reflection). For this reason, in order to couple in a large amount of light, the refractive indices must differ greatly from one another. If, on the other hand, it is desired that the light exits / passes over, the difference should be as small as possible. It should be noted that even with a refractive index difference of more than 0.1, some of the coupled-in light passes into the neighboring layers. However, the inventors have surprisingly discovered that with values ​​less than 0.1 the amount of light passed over can be significantly increased.

[0041] The light guide and the light-conducting layers, i.e. the first layer, the second layer and optionally further light-conducting layers, preferably have a light transmittance of at least 70%, particularly preferably at least 80%, very particularly preferably at least 90% (according to ISO 9050:2003).

[0042] Refractive indices are generally given in the context of the present invention relative to a wavelength of 550 nm. Methods for determining refractive indices are known to those skilled in the art. The refractive indices given in the context of the invention can be determined, for example, by ellipsometry, whereby commercially available ellipsometers can be used. The specification of layer thicknesses or thicknesses refers, unless otherwise stated, to the geometric thickness of a layer.

[0043] "Transparent" in the sense of the invention means a light transmission (according to ISO 9050:2003) of at least 70%, preferably at least 80%, and particularly preferably at least 90%. "Semi-transparent" (according to ISO 9050:2003) in the sense of the invention means a light transmission of at most 70%, preferably at most 50%, and particularly preferably at most 30%. "Opaque" in the sense of the invention means a light transmission (according to ISO 9050:2003) of less than 30%, preferably less than 20%, particularly preferably less than 5%, and in particular less than 0.1%.

[0044] In a preferred embodiment, the intermediate layer has further light-conducting layers which are based on PET. The second layer is preferably the only further layer which is based on PET. Independently of this, in this case the light guide and the first layer are also preferably based on PET and are arranged between the inner pane and the outer pane of the composite pane. In an advantageous extension of this embodiment, the intermediate layer also comprises a further layer without a light-scattering structure based on PVB on the interior surface of the outer pane and the exterior surface of the inner pane, so that the first light-conducting layer, the further light-conducting layers and the light guide are arranged between the PVB-based layers.This is a very viable option for achieving efficient distribution of the coupled light to the surrounding layers of the light guide. The PVB-based layers are not considered part of the "continuous layer" within the meaning of the invention.

[0045] The composite pane preferably has an opaque masking region through which no vision is possible. This masking region is preferably arranged circumferentially in an edge region of the composite pane and surrounds a central transparent see-through region in a frame-like manner. This is particularly common for vehicle windows. The masking region is formed in particular by an opaque element, for example by an opal masking print or an opaque section of the intermediate layer. The masking region is particularly preferably formed by an opaque masking print on the interior-side surface of the outer pane. Such a masking print is typically formed by an enamel containing glass frits and a black pigment, which is screen-printed and then fired into the surface.

[0046] The composite pane can be flat or curved in one or more directions of the room.

[0047] The various embodiments of the invention can be implemented individually or in any combination. In particular, the features mentioned above and those to be explained below can be used not only in the specified combinations, but also in other combinations or on their own, without departing from the scope of the invention. This applies unless exemplary embodiments and / or their features are explicitly mentioned only as alternatives or are mutually exclusive. In particular, the features described in the context of the composite pane according to the invention also apply to the illuminable glazing element, and vice versa.

[0048] The invention further extends to an illuminable glazing element comprising a light source and the composite pane according to the invention. The light source is arranged relative to the composite pane such that the light emitted by it can be at least partially coupled into the light guide. The coupled-in light is distributed within the light guide, in particular by utilizing the effect of total internal reflection, such that it can be at least partially coupled out at the first light-scattering structure and at least partially coupled out at the second light-scattering structure.

[0049] In an advantageous embodiment, the light source is arranged in the masking area of ​​the composite pane, and the light is coupled into the masking area. This makes the light source invisible, at least to an observer from the outside.

[0050] The light guide can be designed such that the light from the light source enters the light guide via an edge surface of the light guide. It is also possible for the light source to be arranged in a recess of the light guide (for example in a feedthrough) so that the light is radiated into the light guide via the side edge surface of the recess and is thereby coupled in. Methods for coupling light via the edge surface of the light guide or via a recess of the light guide are generally known to the person skilled in the art and are described, for example, in WO2010049638A1, US20120104789A1 and

[0051] WO2018149568A1 discloses.

[0052] In a preferred embodiment, the light guide has a reflective structure with a reflective surface, preferably a microprismatic structure. The reflective structure is preferably formed in the first surface of the light guide or attached to the first surface of the light guide. The reflective surface has a plurality of sections inclined relative to the second surface and is configured such that the light radiated into the light guide and passing through the light guide is reflected by the reflective surface and at least partially recoupled into the light guide.The light from the light source is reflected by the reflective surface into the light guide and coupled into it at an angle suitable for the coupled light to propagate at least partially (at least a portion of the coupled light) in the light guide by total internal reflection at the first surface and the second surface of the light guide. The light from the light source preferably enters the light guide via the second surface of the light guide and then strikes the reflective structure, allowing it to be coupled into the light guide. More specifically:

[0053] - the light from the light source passes through the light guide, strikes the first surface and is reflected there, if the reflective structure is formed in the first surface; the reflective surface of the reflective structure is then a partial area of ​​the first surface and the light is reflected by this partial area;

[0054] - Alternatively, the light from the light source passes through the light guide, exits the light guide again via the first surface, and is reflected on the reflective surface of the reflective structure if the reflective structure is attached to the first surface; preferably, the light exiting the light guide passes through the reflective structure and is reflected on its surface facing away from the light guide, which forms the reflective surface.

[0055] The reflective surface is preferably provided with a reflective coating. The reflective coating comprises at least one reflective layer based on a metal or metal alloy. This increases the reflectivity of the reflective surface.

[0056] Typically, not the entire first surface of the light guide is provided with the reflective structure, but only a portion of the first surface that is irradiated by the light source.

[0057] The reflective structure is preferably a microprism film. The microprism film is attached, for example, glued, to the first surface of the light guide. The reflective surface of the reflective structure is preferably arranged facing away from the light guide. The microprism film is transparent. The light from the light source exits the light guide via the first surface, passes through the microprism film, and strikes its reflective surface, where it is reflected and passes through the microprism film again, re-entering the light guide via the first surface. A microprism film is a flexible, particularly foil-like, polymeric film that has a smooth surface facing the light guide and is arranged on it, and a structured surface facing away from the light guide.The structured surface is designed in the form of a planar arrangement of a plurality of prisms with dimensions in the micrometer range, with the prism surfaces forming the inclined sections of the reflective surface. The microprisms act in particular as reflection prisms and reflect the light striking them in a direction that depends on the angle of inclination of the prism surfaces and the angle of incidence of the light. Microprism films are commercially available and can be purchased or specially produced during the manufacture of the glazing element according to the invention or the composite pane according to the invention. The edge length of the individual microprisms is preferably from 10 pm to 250 pm, particularly preferably from 20 pm to 100 pm, for example approximately 30 pm.

[0058] The microprism film can be multilayered. Commonly used microprism films include a substrate layer, for example, based on polyethylene terephthalate (PET), on which the microprisms are formed from a UV-curing polyacrylate.

[0059] The microprism film is transparent and preferably has a light transmittance of at least 70%, particularly preferably at least 80%, and most preferably at least 90%, relative to the light from the light source. It is advantageous if the difference between the refractive indices of the light guide and the microprism film is as small as possible in order to reduce reflection losses at the interface between the light guide and the microprism film. Preferably, the said difference in the refractive indices is at most 0.02 (relative to a wavelength of 550 nm), particularly preferably at most 0.01. If the light guide and the microprism film differ in their refractive index, the microprism film preferably has a higher refractive index than the light guide, which is advantageous for high-yield light coupling.

[0060] Instead of a flexible microprism film, a rigid microprism plate can also be used, i.e. a rigid plastic plate with a flat arrangement of microprisms.

[0061] The reflective structure can also be formed directly in the first surface of the light guide. For this purpose, a portion of the first surface is designed as a reflective surface. This is particularly easy to implement when the light guide is a polymer layer, for example a plastic disk or plate. The light from the light source is reflected directly at the first surface and thrown back into the light guide without exiting the light guide. If the reflective surface with the reflective coating is only partially reflective, then of course some of the light exits the light guide via the first surface and is not reflected. This light can, for example, be at least partially coupled into the first light-guiding layer or further light-guiding layers.

[0062] According to the invention, the reflective surface of the reflective structure has sections that are inclined relative to the second surface of the light guide. This means that the sections are not arranged parallel to the second surface, but at an angle greater than 0° to the second surface. Said sections have an angle to the second surface that lies between 0° and 90°, preferably from 28° to 60° or from 30° to 60°, very particularly preferably from 30° to 50°, in particular from 40° to 50°, for example approximately 45°. This refers to the absolute value of the respective angle. The sections can be inclined in different directions.

[0063] The sections are preferably also inclined relative to each other. This means that adjacent sections are inclined relative to each other, i.e., they are not parallel, but rather arranged at an angle between 0° and 180°.

[0064] Said sections of the reflective surface are preferably substantially flat. The inclination of the sections of the reflective surface relative to the second surface of the light guide determines the angle at which the reflected light is reflected back into the light guide.

[0065] The first and second surfaces of the light guide represent interfaces with the adjacent medium, the first light-conducting layer or the continuous layer, respectively, and either with the surrounding atmosphere or, for example, with another layer arranged between the light guide and the inner pane. Typically, the medium adjacent to the second surface (for example, the atmosphere of the interior if the light guide is the inner pane) has a different refractive index than the light guide.

[0066] The sections of the reflective surface are in particular inclined in such a way that at least a portion of the light is reflected back into the light guide at an input angle such that it hits the second surface at an angle (angle of incidence) which is greater than the critical angle of total internal reflection. The light beam is totally reflected at the second surface at an angle of reflection which corresponds to the angle of incidence. The light hits the first surface at precisely this angle of incidence, where it is partially totally reflected, with a portion of the light being emitted into the first light-guiding layer or into the continuous light-guiding layer. The reflected light propagates in the light guide as a result of repeated total internal reflection, being reflected back and forth between the two surfaces of the light guide. This propagation is also not completely loss-free.Due to the small differences in refractive indices between the light guide and the first layer or continuous layer, a portion of the light enters the first layer or the continuous layer. The light then spreads, at least partially, within the first layer or the continuous layer, utilizing the effect of total internal reflection. As is common in ray optics, the angle of incidence is the angle that the light beam incident on the surface makes to the surface normal at the point of impact. The angle of reflection is determined analogously to the surface normal, as is the critical angle of total internal reflection.

[0067] The light propagates through the light guide until it either hits the side edge surface of the light guide and is decoupled there, or it hits at least the first light-scattering structure on one of the two surfaces of the light guide, which interrupts total internal reflection through light scattering, causing the light to be decoupled from the light guide via the respective surface. This also applies analogously to the first light-conducting layer or the continuous layer.

[0068] The glazing element is provided with a light source suitable for coupling light into the laminated pane. During operation, the light source emits visible light, i.e. electromagnetic radiation in the visible spectral range, in particular in the range from 380 nm to 780 nm. The light source can have one or more emission bands which are arranged in the visible spectral range and cover or cover part of it. However, the light source can also have a broad emission band which covers the entire visible spectral range. The emission band(s) - and thus the color of the emitted light - can be freely selected according to the requirements of the specific application. The glazing element can have a single light source or several separate light sources whose light is coupled into the light guide at different points.

[0069] Said light sources with different emission wavelengths preferably comprise a light source with a red emission color (in particular with a (average) emission wavelength of approximately 630 nm), a light source with a green emission color (in particular with a (average) emission wavelength of approximately 550 nm), and a light source with a blue emission color (in particular with a (average) emission wavelength of approximately 473 nm). The light from these light sources (RGB) overlaps to form white light, so that white light can be coupled into the light guide and the first layer or the contiguous layer.

[0070] The light source preferably comprises at least one light-emitting diode (LED). The light source can be a single light-emitting diode, but is preferably an array of multiple light-emitting diodes. Said array is preferably installed in a common housing, for example, as a linear array in which the light-emitting diodes are arranged along a line. The electroluminescent material of the light-emitting diode can be, for example, an inorganic semiconductor or an organic semiconductor. In the latter case, it is also referred to as an organic light-emitting diode (OLED).

[0071] Optionally, a collimator can be arranged between the light source and the reflective structure, wherein the collimator is located in the beam path of the light source. The collimator is preferably arranged between the light source and the second surface of the light guide, in particular between the light source and the inner pane, so that the light is radiated into the composite pane or into the light guide via the collimator. The collimator generates a light beam from the typically divergent light beam of the light source, preferably with a substantially parallel beam path, or at least with a less divergent, i.e., more concentrated beam path. The beam cone of the light source is thus narrowed by the collimator.This has the advantage that the entire light beam is irradiated into the composite pane at the same angle of incidence, in particular at an angle of incidence which, in conjunction with the reflective properties of the reflective structure, ensures that a large proportion of the light is coupled into the light guide or at least the first layer or the continuous layer in such a way that total internal reflection occurs. This optimizes the light yield. In the simplest case, the collimator is a type of converging lens, with the light source preferably arranged at its focal point. The collimator can be made of glass or a transparent plastic, for example, in particular polycarbonate (PC) or polymethyl methacrylate (PMMA). The collimator is preferably attached, for example glued, to the second surface of the inner pane.If the light source is configured as an array of multiple LEDs, a separate collimator can be provided for each LED. However, a common collimator is preferably used for the entire LED array. In the case of a linear LED array, for example, a rod-like collimator can be used, the length of which is at least equal to the length of the LED array.

[0072] The invention also encompasses a method for producing a composite pane according to the invention. The method comprises the following steps in the specified order:

[0073] (A) Either the light guide, the intermediate layer, the first light-scattering structure, the second light-scattering structure and the outer pane are arranged to form a layer stack or the inner pane, the light guide, the intermediate layer, the first light-scattering structure, the second light-scattering structure and the outer pane are arranged to form a layer stack.

[0074] (B) The layer stack is laminated to form a composite pane, preferably by autoclaving.

[0075] The composite pane can be manufactured using conventional lamination processes, such as autoclave processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators, or combinations thereof. The bonding of the outer and inner panes is typically achieved using heat, vacuum, and / or pressure.

[0076] The invention further encompasses the use of a composite pane according to the invention as a window pane of a vehicle. A particularly preferred use is a vehicle roof pane that can be illuminated three-dimensionally. The vehicle can in principle be any land vehicle, watercraft, or aircraft, and is preferably a passenger car, truck, or rail vehicle. The composite pane can also be used in buildings, for example as a window pane, glass facade, or glass door, either indoors or outdoors, in particular as a window pane of a building or an interior. The composite pane can also be used as a component of furniture, electrical devices, as a component of furnishings, or as a furnishing.

[0077] The invention is explained in more detail below with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way.

[0078] They show:

[0079] Fig. 1 shows a cross section through an embodiment of the composite pane according to the invention,

[0080] Fig. 2 shows a cross section through a further embodiment of the composite pane according to the invention,

[0081] Fig. 3 shows a cross section through an embodiment of the glazing element according to the invention and

[0082] Fig. 4 is an enlarged view of section Z from Figure 3.

[0083] Figure 1 shows a first embodiment of the composite pane 1 according to the invention. The composite pane 1 is intended, for example, as a roof pane of a vehicle, in particular a passenger car. For the sake of simplicity, it is shown flat, although such vehicle roof panes are typically curved. The composite pane 1 is structurally formed from an outer pane 4, a light guide 2, which serves as the inner pane, and a thermoplastic intermediate layer 3, via which the outer pane 4 and the light guide 2 are connected to one another. The outer pane 4 and the light guide 2 are made of soda-lime glass and each have a thickness of, for example, 2.1 mm. The intermediate layer 3 is made of a PVB film with a thickness of, for example, 0.76 mm.The light guide 2 and the intermediate layer 3 are clear, the outer pane 4 is tinted in order to reduce the light transmission of the laminated pane 1 (for example to less than 15%), as is usual for vehicle roof windows.

[0084] In the installed position, the outer pane 4 faces the exterior environment of the vehicle. It has an exterior surface I facing the exterior environment and an interior surface II facing the vehicle interior. The light guide 2, which also represents the inner pane, faces the vehicle interior in the installed position. It has an exterior surface III facing the exterior environment and an interior surface IV facing the vehicle interior. The interior surface II of the outer pane 4 and the exterior surface III of the light guide 2 are connected to one another via the thermoplastic intermediate layer 3.

[0085] The composite pane 1 has a surrounding, opaque edge area (masking area) in which a black masking print 7 is applied to the interior-side surface II of the outer pane 4, which prevents visibility through the composite pane 1.

[0086] The intermediate layer 3 comprises a first light-conducting layer 3.1, a further second light-conducting layer 3.2 and a further third light-conducting layer 3.3. The first layer 3.1 is arranged flat and directly adjacent to the outer surface III of the light guide 2. The second layer 3.2 is applied flatly to the surface of the first layer 3.1 facing away from the light guide 2. The third layer 3.3 is applied flatly to the surface of the second layer 3.2 facing away from the light guide 2. The second layer 3.2 is therefore arranged between the first layer 3.1 and the third layer 3.3. The third layer 3.3 is also arranged directly adjacent to the interior-side surface II of the outer pane 4. It would also be possible for a further layer, preferably a tinted layer, to be arranged between the third layer 3.3 and the outer pane 4 (not shown here). Each of the layers 3.1, 3.2, 3.3 of the intermediate layer 3 has the same layer thickness, so that the total layer thickness of the intermediate layer 3 is 0.76 mm.

[0087] The laminated pane 1 is intended to be a component of an illuminated glazing element. The laminated pane 1 is designed such that light can be coupled into the light guide 2 and can propagate within the light guide 2 using the effect of total internal reflection. Light which exits the light guide 2 via the outer surface III of the light guide 2 passes into the first layer 3.1, the second layer 3.2 and / or the third layer 3.3. The first layer 3.1, the second layer 3.2 and the third layer 3.3 form a continuous layer in the laminated composite pane 1, such that the coupled-in light propagates within the continuous layer. The layers 3.1, 3.2, 3.3 of the intermediate layer 3 thus result in a continuous layer in the laminated composite pane 1, into which light can be coupled using the effect of total internal reflection.

[0088] In order to couple the light back out of the composite pane 1 and thereby create illumination, the light guide 2, the first layer 3.1, the second layer 3.2 and the third layer 3.3 are provided with light-diffusing structures 5.1, 5.2, 5.3. The light guide 2 has a first light-diffusing structure 5.1 on the interior-side surface IV of the light guide 2 in the form of a transparent enamel. When the light hits the light-diffusing structures 5.1, 5.2, 5.3, it is scattered and thereby coupled out of the light guide 2 and thus the composite pane 1. A second light-diffusing structure 5.2 and a further light-diffusing structure 5.3 are applied in the form of a transparent print to the surface of the first layer 3.1 facing the light guide 2 and are thus arranged between the light guide 2 and the first layer 3.1. A further light-scattering structure 5.3 is on the surface of the second layer 3 facing the light guide 2.2 in the form of a transparent print and thus arranged between the first layer 3.1 and the second layer 3.2. A further light-scattering structure 5.3 is applied in the form of a transparent print to the surface of the third layer 3.3 facing the light guide 2 and is thus arranged between the second layer 3.2 and the third layer 3.3. A further light-scattering structure 5.3 is applied in the form of a transparent print to the surface of the third layer 3.3 facing away from the light guide 2 and is thus arranged between the third layer 3.3 and the outer pane 4. The number of light-scattering structures 5.1, 5.2, 5.3 and their arrangement within the composite pane 1 can basically be freely selected, whereby according to the invention at least the second light-scattering structure 5.2 must be arranged closer to the outer pane 4 than the first light-scattering structure 5.1.

[0089] The light-diffusing structures 5.1, 5.2, 5.3 on various levels of the composite pane 1 create a three-dimensional light effect for the viewer when the light is coupled out. This results in an overall very pleasant light image. The light-diffusing structures 5.1, 5.2, 5.3 therefore appear to the viewer not only as two-dimensional luminous surfaces. Light that does not strike the light-diffusing structures 5.1, 5.2, 5.3 reaches the side edge surface of the light guide 2 or the side edge surface of the connected layer consisting of the first layer 3.1, the second layer 3.2 and the third layer 3.3 and is coupled out via these.

[0090] Figure 2 shows a second embodiment of the composite pane 1 according to the invention. The composite pane 1 of Figure 2, just like in the first embodiment of Figure 1, is, for example, a vehicle roof pane. In contrast to the first embodiment, however, here the light guide 2 is not simultaneously the inner pane, but instead is arranged between an inner pane 6 and the outer pane 4 and within the intermediate layer 3. The inner pane 6 has an outer surface V facing the intermediate layer 3 and an interior surface VI facing away from the intermediate layer 3. The inner pane 6 consists, for example, of soda-lime glass and has a thickness of, for example, 2.1 mm. The light guide 2 is, for example, a PET film with a thickness of, for example, 100 μm.The second embodiment differs from the first embodiment in the arrangement of the light guide 2 in the composite pane 1, the number of light-conducting layers 3.1, 3.2 and the arrangement and number of the light-scattering structures 5.1, 5.2, 5.3.

[0091] The first light-conducting layer 3.1 is arranged directly adjacent to the outer surface III of the light guide 2, and a second light-conducting layer 3.2 is arranged directly on the surface of the first layer 3.1 facing away from the light guide 2. The second layer 3.2 is also arranged directly on the interior surface II of the outer pane 4, so that two light-conducting layers 3.1, 3.2 are arranged between the light guide 2 and the outer pane 4. A plurality of light-scattering structures 5.2, 5.3 are applied to the layers 3.1, 3.2. Between the light guide 2 and the inner pane 6 there is a third layer 3.3 which, for example, is not light-conducting. However, the third layer 3.3 can also be light-conducting and provided with further light-scattering structures 5.3 (not shown here).By arranging the light guide 2 between the inner pane 6 and the outer pane 4, the light guide 2 is better protected against external influences and is more durable over time.

[0092] Figures 3 and 4 each show a detail of a glazing element 100 according to the invention. Figure 3 shows a cross-section of the glazing element 100. A section Z is marked there, which is shown enlarged in Figure 4.

[0093] The glazing element 100 comprises a laminated pane 1 as described for Figure 1.

[0094] The glazing element 100 comprises a light source 8, which is, for example, a light-emitting diode (LED). The light source 8 emits, for example, light 11 with a green emission color and an average emission wavelength of 550 nm. The light source 8 is directed onto a partial area of ​​the interior-side surface IV of the light guide 2, with a collimator 10 arranged between the light source 8 and the light guide 2. The collimator 10 is a transparent optical component, for example made of polycarbonate, which acts as a type of converging lens and reduces the beam cone of the light source 8, ideally to a parallel beam path. The collimator 10 is, for example, glued to the interior-side surface IV of the light guide 2, in particular via a layer of optically clear adhesive (not shown). The collimator 10 is merely optional; it particularly improves the light yield.The light source 8 can be arranged alternatively to the collimator 10 or additionally, for example, in a housing not shown, which is attached to the interior-side surface IV of the light guide 2.

[0095] The light 11 radiated via the interior surface IV passes through the light guide 2 and strikes the exterior surface III of the light guide 2. A reflective structure 9 is arranged there and is irradiated by the light 11. The reflective structure 9 is, for example, a microprismatic film having a reflective silver layer. The reflective structure 9 can simply be inserted between the intermediate layer 3 and the light guide 2, being fixed in place during the lamination of the composite pane 1. However, it is also possible for the reflective structure 9 to be glued to the light guide 2 or the first layer 3.1 as a microprismatic film, in particular using an optically clear adhesive.

[0096] The light 11 incident on the reflective structure 9 is reflected at a specific angle, the coupling angle α. Due to the beveled surfaces of the microprismatic film coated with the silver layer, a large portion of the light 11 emitted by the light source 8 is reflected at the coupling angle α. A remaining portion of the light 11 is not reflected at the coupling angle α.

[0097] The coupling angle α describes the change in the direction of light propagation (represented by dashed arrows). The coupling angle α is the angle between the light vector incident on the reflective structure 9 and the light vector emanating from the reflective structure 9. The coupling angle α is between 90° and 180° and is, for example, approximately 102°.

[0098] The surfaces III, IV of the light guide 2 each represent an interface to the adjacent first layer 3.1 and the vehicle interior. At the wavelength of the light source 8 of 550 nm, the refractive index of the light guide 2 is 1.53 (soda-lime glass), the refractive index of the layers 3.1, 3.2, 3.3 of the intermediate layer 3 is 1.48 (PVB) and the refractive index of air is approximately 1.00. From this, a critical angle of total reflection can be calculated for both surfaces III, IV: this is approximately 75.3° on the outside surface III (interface to the intermediate layer 3) and approximately 40.8° on the inside surface IV (interface to the air). The critical angle of total reflection is measured to the surface normal.

[0099] The light 11 from the light source 8 is radiated into the light guide 2 via the interior surface IV and, after transmission through the light guide 2 and exiting via the exterior surface III, strikes the reflective structure 9. There, the light 11 is reflected. The light 11 then passes through the light guide 2 and mostly strikes the interior surface IV of the light guide 2 at an angle of incidence of >75.3° (also measured relative to the surface normal). Since the angle of incidence is greater than the critical angle of total internal reflection (40.8°), the light 11 is totally reflected, passes through the light guide 2 again and strikes the exterior surface III at an angle of incidence of >75.3°. Here, too, the angle of incidence is greater than the critical angle of total internal reflection, so that the light 11 is again totally reflected.In this way, the light 11 is reflected back and forth between the surfaces III, IV, so to speak, so that it spreads in the light guide 2 until it hits the light-scattering structures 5.1, 5.2, 5.3 or the side edge surface of the light guide 2 and is coupled out there.

[0100] However, a portion of the light 11 emitted by the light source 8 does not strike the outer surface III of the light guide 2 at an angle of >75.3°. It is accordingly coupled out of the light guide 2 and enters the coherent layer or the intermediate layer 3. In the intermediate layer 3, consisting of the first layer 3.1, the second layer 3.2 and the third layer 3.3, there is now again the possibility of total internal reflection as described for the light guide 2. The light 11 in the intermediate layer is therefore reflected back and forth at the surfaces of the intermediate layer 3, i.e. the interfaces which border the light guide 2 and the outer pane 4. The path of the light 11, which is distributed in the layers 3.1, 3.2, 3.3 of the intermediate layer 3 is indicated as an example in Figure 3 by dashed arrows.The dashed arrows show that a part of the light 11 is reflected at the outer surface III of the light guide 2, whereas another part of the light 11 enters the intermediate layer 3 and spreads within the intermediate layer 3, which consists of a continuous layer of the first, second and third layers 3.1, 3.2, 3.3, by utilizing the effect of total reflection.

[0101] In the embodiment shown in Figures 3 and 4, the light 11 from the light source 8 strikes the interior-side surface IV at an angle of incidence of 0° (measured with the surface normal) before coupling. However, it is also possible to radiate the light 11 not perpendicularly, but at an angle of incidence other than 0°. Alternatively, the light source 8 can be arranged in a recess in the light guide 2 or on a section of the circumferential edge surface of the light guide 2 (not shown here). In these cases, the light 11 from the light source 8 is coupled directly into the light guide 2 via the edge surface (either the outer circumferential surface or that of the recess in the light guide 2). In these cases, no reflective structure 9 is necessary.

[0102] Reference symbols

[0103] 1 composite pane

[0104] 2 light guides

[0105] 3 Intermediate layer

[0106] 3.1 first layer of the intermediate layer 3

[0107] 3.2 second layer of the intermediate layer 3

[0108] 3.3 third layer of the intermediate layer 3

[0109] 4 Outer pane

[0110] 5.1 first light-scattering structure

[0111] 5.2 second light-scattering structure

[0112] 5.3 further light-scattering structure

[0113] 6 inner pane

[0114] 7 Cover print

[0115] 8 Light source

[0116] 9 reflective structure

[0117] 10 Collimator

[0118] 11 Light from the light source

[0119] 100 glazing elements

[0120] Z cutout

[0121] I outside surface of the outer pane 4

[0122] II Interior surface of the outer pane 4

[0123] III outer surface of the light guide 2

[0124] IV interior surface of the light guide 2

[0125] V outer surface of the inner pane 6

[0126] VI interior surface of the inner pane 6 a coupling angle

Claims

Patent claims 1. A composite pane (1), comprising a light guide (2) with a first surface (III) and a second surface (IV), an intermediate layer (3) which has at least one first light-conducting layer (3.1) and a second light-conducting layer (3.2) directly adjacent to the first surface (III), an outer pane (4) and at least one first light-scattering structure (5.1) and a second light-scattering structure (5.2), wherein the first light-scattering structure (5.1) is arranged on the first surface (III) or the second surface (IV), wherein the second light-scattering structure (5.2) is arranged on or within the first light-conducting layer (3.1) and is arranged closer to the outer pane (4) than the first light-scattering structure (5.1), wherein the refractive index of the first light-conducting layer (3.1) and of the light guide (2) differs by a maximum of 0.1 and the light guide (2) and the outer pane (4) are connected at least by the first light-conducting layer (3.1), wherein the second light-conducting layer (3.2) is applied to a surface of the first layer (3.1) facing away from the light guide (2) and has at least one further light-scattering structure (5.3).

2. Composite pane (1) according to claim 1, wherein the intermediate layer (3) has at least a third light-conducting layer (3.3).

3. Composite pane (1) according to claim 2, wherein the third light-conducting layer (3.3) is applied to a surface of the second layer (3.2) facing away from the light guide (2) and has at least one further light-scattering structure (5.3).

4. Composite pane (1) according to one of claims 1 to 3, wherein the light guide (2) is arranged between an inner pane (6) and the outer pane (4) and the second surface (IV) of the light guide (2) faces the inner pane (6).

5. Composite pane (1) according to claim 4, wherein a further layer (3.3) of the intermediate layer (3) is arranged between the inner pane (6) and the light guide (2).

6. Composite pane (1) according to one of claims 1 to 3, wherein the light guide (2) represents the inner pane (6) and the second light-scattering structure (5.2) is arranged on a surface of the first layer (3.1) facing away from the light guide (2).

7. Composite pane (1) according to one of claims 1 to 6, wherein the first layer (3.1) contains polyvinyl butyral.

8. Composite pane (1) according to one of claims 1 to 7, wherein the light guide (2) consists of soda-lime glass, borosilicate glass, aluminosilicate glass or quartz glass, preferably soda-lime glass.

9. Composite pane (1) according to one of claims 1 to 8, wherein the second light-scattering structure (5.2) is formed as an imprint on a surface of the first layer (3.1) facing away from the light guide (2).

10. Composite pane (1) according to one of claims 1 to 9, wherein the first light-scattering structure (5.1) of the light guide (2) is formed as a roughening of a partial area of the second surface (IV).

11. An illuminable glazing element (100) comprising a light source (8) and the composite pane (1) according to one of claims 1 to 10, wherein the light source (8) is arranged such that its light (11) can be at least partially coupled into the light guide (2) and the coupled-in light (11) can be at least partially coupled out at the first light-scattering structure (5.1) and the second light-scattering structure (5.2).

12. Glazing element (100) according to claim 11, wherein the light guide (2) has a reflective structure (9) on the first surface (III) or in the first surface (III).

13. Glazing element (100) according to claim 12, wherein the light source (8) is arranged such that the light (11) can be reflected by the reflective structure (9) and thereby coupled into the light guide (2).

14. A method for producing a composite pane (1) according to one of claims 1 to 10, wherein (A) the light guide (2), the intermediate layer (3) and the outer pane (4) are arranged to form a layer stack or (B) the inner pane (6), the light guide (2), the intermediate layer (3) and the outer pane (4) are arranged to form a layer stack and (C) the layer stack of (A) or (B) is laminated to form a composite pane (1), preferably by means of an autoclave process.

15. Use of a composite pane (1) according to one of claims 1 to 10 as a window pane of a vehicle, a building or an interior, as a component of furniture, electrical appliances, as a component of furnishings or as a furnishing, preferably as a 3-dimensionally illuminable vehicle roof pane.

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