Illuminated glazing element with diffractive holographic element for coupling in light

Abstract

The present invention relates to an illuminated glazing element, comprising - a glass pane (2) or a plastic pane having a first surface (III) and a second surface (IV), - a light source (5) for generating light, wherein the second surface (IV) of the glass pane (2) or plastic pane faces the light source (5), - a diffractive holographic element (4) which is irradiated by the light source (5), wherein the diffractive holographic element (4) is suitable for deflecting the light such that it is coupled into the glass pane (2) or plastic pane and propagates at least in the glass pane (2) or plastic pane, preferably through total reflection.

Description

[0001] Illuminated glazing element with diffractive holographic element for light coupling

[0002] The invention relates to an illuminated glazing element, a method for its production and its use.

[0003] Illuminated glazing elements are well known. They are equipped with a light source whose light is coupled into a pane of glass and spreads out due to total internal reflection. The light is often recoupled from the pane of glass 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, a pattern, to be created. Illuminated glazing elements of this type are known, for example, from WO2014 / 060409A1 or WO2014 / 167291A1.

[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 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 glass pane. However, such coupling is often impossible, especially 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] In the subsequently published international application WO2023144282A1, it was proposed to couple light via a main surface of the glass pane. For this purpose, a reflective structure with a reflective surface, in particular a microprism film, is attached to the surface of the glass pane facing away from the light source. The reflective surface 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 of the reflective surface in such a way that it spreads through the glass pane as a result of total internal reflection. However, the integration of the reflective structure into the glazing element makes the production of such a glazing element considerably more complex.In particular, in the case of a composite pane, the reflective structure must be integrated into it, which requires a more complex and lengthy lamination process.

[0008] The object of the present invention is to provide an improved illuminated glazing unit in which the light is coupled in with high efficiency and which is easy to manufacture.

[0009] The object of the present invention is achieved by an illuminated glazing element according to claim 1. Preferred embodiments emerge from the subclaims.

[0010] The invention is based on the coupling of light using a diffractive holographic element. This element has light-diffractive properties optimized for the emission wavelength of the light source. The light from the light source is deflected by light diffraction and coupled into the glazing element in such a way that it spreads there, particularly by total internal reflection, similar to a light guide. The diffractive holographic element enables efficient light coupling with very low light losses. This is the great advantage of the invention.

[0011] The illuminated glazing element, within the meaning of the invention, is a pane- or plate-like object comprising at least one glass or plastic pane (preferably a glass pane) and, in particular, is structurally formed from at least one glass or plastic pane. The glazing element can be a single pane and structurally consist only of said glass or plastic pane. Alternatively, the glazing element can be a laminated pane or insulating glazing containing said glass or plastic pane. In a laminated pane, the glass or plastic pane is connected to another pane via a thermoplastic intermediate layer. Alternatively, the glass or plastic pane can be embedded as a thin light guide in the intermediate layer of a laminated pane.In insulating glazing, the glass or plastic pane is connected to another pane at the edge via a surrounding spacer, creating a space between the panes, typically filled with an inert gas or evacuated. The glazing element can be used as a window pane, for example, in vehicles, buildings, or interiors. However, the glazing element can also be used as a component of furniture or electrical appliances, for example, as a door pane for a cupboard or shelf, or as a pane for an oven door. The glazing element can also be used as a furnishing item, for example, as a display panel in bars or nightclubs.

[0012] The illuminated glazing element according to the invention comprises or contains at least one glass pane or plastic pane, a light source and a diffractive holographic element.

[0013] The glass pane or plastic pane has a first surface (main surface), a second surface (main surface) and a side edge surface running between them.

[0014] The light source is intended and suitable for generating light. The light source is arranged in the glazing element such that one of the main surfaces of the glass or plastic pane faces the light source. This main surface is referred to in the invention as the second surface of the glass or plastic pane. The light source is directed onto the second surface and, during operation, irradiates it with light. The light is radiated (at least partially) into the glass or plastic pane via the second surface.

[0015] The glazing element according to the invention is characterized in that it is equipped with the diffractive holographic element. The diffractive holographic element is suitable and configured to deflect the light from the light source such that it is (at least partially) coupled into the glass or plastic pane. The light is coupled in at a coupling angle suitable for the coupled light to propagate at least partially (at least a portion of the coupled light) at least within the glass or plastic pane, in particular by total internal reflection.

[0016] The coupled light propagates like a light guide in the glazing element, being reflected back and forth between two interfaces to an adjacent, optically less dense medium by total internal reflection. The light can propagate exclusively within the glass or plastic pane, with total internal reflection occurring at the first and second surfaces of the glass or plastic pane. In this case, the glass or plastic pane alone forms the said light guide. However, it is also possible for the said light guide to comprise, in addition to the glass or plastic pane, one or more other layers connected to it with the same or a similar refractive index, so that the light propagates within the glass or plastic pane and at least one adjacent layer.If the glass or plastic pane is provided with one or more additional light-conducting layers on only one side, total reflection occurs on one surface of the glass or plastic pane and the surface of the at least one additional layer facing away from it. If the glass or plastic pane is provided with one or more additional light-conducting layers on both sides, total reflection occurs on the surfaces of the two additional layers or layer sequences connected to the glass or plastic pane facing away from the glass or plastic pane.

[0017] The diffractive holographic element is a holographic element, in particular a holographic film, which is suitable for diffracting light so that the propagation direction of light passing through the holographic element is changed.

[0018] Holography is a method for recording and reconstructing a wave field. While in photography only the intensity and (in the case of color photography) the frequency of the incident light are stored on film, in holography the phase and intensity of the light are stored. A hologram is created by irradiating an object with coherent light, which is reflected and scattered by the object. The resulting wave field (object wave) is superimposed with unscattered light (reference wave) from the same radiation source. Optical interference occurs between the object wave and the reference wave, creating an interference pattern. The holographic medium is exposed to this interference pattern. The holographic medium reacts only to the intensity of the light, but the relative phase (between the object and reference waves) is recorded through the interference of the wave fronts.The hologram is created by developing the holographic medium. A laser is usually used as the coherent radiation source, whose radiation is expanded using scattering lenses.

[0019] The holographic element is a holographic medium on which a hologram is recorded. The holographic medium is preferably a holographic film. This refers to a polymer film made of a light-sensitive polymer, containing light-sensitive inclusions, or provided with a light-sensitive coating. Alternatively, a glass plate with a light-sensitive coating can be used as the holographic medium, or a rigid plastic plate with a light-sensitive coating, with light-sensitive inclusions, or made of a light-sensitive polymer.

[0020] In a preferred embodiment, the holographic film comprises a layer of a photopolymer, which is arranged on a carrier film or which is arranged between two carrier films. The photopolymer layer preferably has a thickness of 5 μm to 50 μm, particularly preferably of 7 μm to 30 μm. The carrier films have, for example, a thickness of 50 μm to 200 μm. The holographic film is preferably provided with a circumferential edge seal to prevent contaminants from penetrating the photopolymer layer via the side edge. The edge seal can, for example, be a polymeric tape or adhesive tape, which is arranged circumferentially around the side edge of the holographic film.

[0021] It is well known that holography can be used to create optical components (holographic optical components, HOEs). This allows conventional optical components such as lenses, mirrors, or prisms to be replaced. The diffractive holographic element according to the invention can also be considered a holographic optical component.

[0022] Holographic elements with light-diffractive properties (diffractive holographic elements) and methods for producing them are also known to those skilled in the art. Examples include WO01037014A1, EP0467601B1, EP0179717A1, US020100253919A1, US20080002540A1. For example, the interference pattern with which the holographic medium is exposed can generate complex local refractive index changes in the medium, thereby creating a complex diffraction pattern. Particularly suitable light-sensitive components of the holographic medium are photorefractive materials that change their refractive index depending on exposure due to the photorefractive effect (e.g., lithium niobate, barium titanate, or gallium arsenide), or photopolymers in which polymerization is induced by exposure, thereby changing the optical properties such as the refractive index.

[0023] The wavelength of the radiation source for exposure (i.e., the wavelength of the reference and object waves) corresponds in particular to the wavelength of the light source of the illuminated glazing element according to the invention. In other words, the diffractive holographic element is exposed to a wavelength that corresponds to the emission wavelength of the light source, or in short, the diffractive holographic element is exposed to the emission wavelength of the light source. This allows the light-diffractive effect generated during exposure (in particular, the diffraction pattern resulting from complex refractive index changes) to have an optimal effect on the radiation of the light source. The emission wavelength of the light source is understood, in particular, to be the maximum of the emission band of the light source.

[0024] A light beam incident on the diffractive holographic element is diffracted, changing the direction of the beam. The angle between the incident light vector and the light vector emerging from the holographic element after diffraction is referred to as the diffraction angle within the meaning of the invention. If the diffraction angle is between 90° and 180°, the light beam passes through the diffractive holographic element with a changed beam direction. Such a holographic element is referred to as a transmissive-diffractive holographic element within the meaning of the invention. If the diffraction angle is between 0° and 90°, the light beam is reflected by the diffractive holographic element with a changed beam direction. Such a holographic element is referred to as a reflective-diffractive holographic element within the meaning of the invention.In a first embodiment of the illuminated glazing element according to the invention, the diffractive holographic element is a transmissive-diffractive holographic element. The radiation from the light source thus passes (at least predominantly) through the holographic element, where it is deflected. The diffraction angle is between 90° and 180°. The diffractive holographic element is arranged between the light source and the glass or plastic pane (or the light guide), in particular between the light source and the second surface of the glass or plastic pane (or the light guide) facing the light source, so that the light passed through the holographic element and deflected is coupled into the glass or plastic pane via the second surface.

[0025] The diffractive holographic element is preferably bonded to the second surface of the glass or plastic pane. A layer of optically clear adhesive is particularly preferred to ensure optimal optical quality of the glazing element.

[0026] In a second embodiment of the illuminated glazing element according to the invention, the diffractive holographic element is a reflective-diffractive holographic element. The radiation from the light source is thus (at least predominantly) reflected by the holographic element and does not pass through it. The diffraction angle is between 0° and 90°. The glass or plastic pane (or the light guide) is arranged between the light source and the diffractive holographic element, such that the first surface of the glass or plastic pane faces the diffractive holographic element. The light reflected and deflected by the holographic element is coupled into the glass or plastic pane via the first surface.

[0027] The diffractive holographic element is preferably arranged on the first surface of the glass or plastic pane (or the light guide). It can be glued to the first surface, preferably via a layer of an optically clear adhesive. If the glazing element is designed as a composite pane, the holographic element can be inserted between the glass or plastic pane and the thermoplastic intermediate layer and fixed to the first surface by the lamination of the composite pane. Optionally, a collimator can be arranged between the light source and the diffractive holographic element, 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 glass or plastic pane, such that the light is radiated into the glass or plastic pane via the collimator.The collimator converts the typically divergent light beam from the light source into a light beam with a preferably essentially parallel beam path, or at least a less divergent, i.e., more concentrated beam path. The light source's beam cone is thus narrowed by the collimator. This has the advantage that the entire light beam is irradiated into the glazing element at the same angle of incidence, particularly at an angle of incidence that, in conjunction with the light-diffractive properties of the holographic element, ensures that as much of the light as possible is coupled into the glass or plastic pane in such a way that total internal reflection occurs. This optimizes the light yield.

[0028] However, a collimator is not required. A major advantage of the invention is that the properties of the hologram can be adjusted very flexibly. The diffractive holographic element (or the light-diffracting hologram formed within it) can also be adapted to non-collimated light sources.

[0029] In the simplest case, the collimator is a type of converging lens, with the light source preferably positioned at its focal point. The collimator can be made, for example, from glass or a transparent plastic, in particular polycarbonate (PC) or polymethyl methacrylate (PMMA). The collimator is preferably attached, for example glued, to the second surface of the glass or plastic pane, or to the diffractive holographic element arranged on the second surface. If the light source is configured as an array of multiple light-emitting diodes, a separate collimator can be provided for each light-emitting diode. Preferably, however, a common collimator is 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 corresponds at least to the length of the LED array.

[0030] In principle, however, it is also possible to use a holographic optical component as a collimator, for example, a holographic film acting as a converging lens. In an advantageous embodiment, the glazing element comprises several light sources of different emission colors, i.e., several light sources with different emission wavelengths. The light sources are mounted on the glazing element at a distance from one another. The light sources can optionally be arranged in a common housing, which facilitates the attachment and positioning of the light sources on the glazing element.

[0031] With regard to the coupling of the light from the different light sources into the glass or plastic pane, three variants in particular are conceivable:

[0032] 1. In a first embodiment, each light source is assigned its own diffractive holographic element. Thus, a diffractive holographic element is used for each light source, the light-diffractive properties of which are optimized for the emission wavelength of the light source, in particular, which has been exposed to radiation of the same wavelength. The glazing element thus comprises several light sources with different emission wavelengths and the same number of diffractive holographic elements, with each light source being assigned exactly one holographic element, and each holographic element being assigned exactly one light source.Each diffractive holographic element is suitable for deflecting the light of the associated light source in such a way that it is coupled into the glass or plastic pane with a coupling angle that is suitable for the coupled light to propagate in the glass or plastic pane, in particular by total internal reflection.

[0033] 2. In a second embodiment, a single (common) diffractive holographic element is assigned to the multiple light sources. The holographic element has differently exposed regions. The number of these regions corresponds to the number of light sources. Each region is assigned to a light source and exposed to the emission wavelength of that light source. A common diffractive holographic element is therefore used for all of the light sources, which has different regions. For each light source, one of these regions is used, the light-diffractive properties of which are optimized for the emission wavelength of the light source, in particular, exposed to radiation of the same wavelength.The glazing element thus comprises several light sources with different emission wavelengths and a single diffractive holographic element with the same number of differently illuminated areas, with each light source being assigned exactly one area, and each area being assigned exactly one light source. Each area of ​​the diffractive holographic element is suitable for deflecting the light from the assigned light source such that it is coupled into the glass or plastic pane at an input angle suitable for the coupled light to propagate within the glass or plastic pane, in particular by total internal reflection.

[0034] 3. In a third embodiment, a single diffractive holographic element is assigned to the multiple light sources. The holographic element has a single, uniformly exposed region (whereby the holographic element can be fully exposed, so that said region encompasses the entire holographic element). This region is assigned to the entirety of the light sources and is exposed to the emission wavelengths of all light sources. This means that said region is completely (fully exposed) to each wavelength. The holographic element therefore has a multi-color hologram (for example, an RGB hologram). A common diffractive holographic element is used for the entirety of the light sources, the light-diffractive properties of which are optimized for the emission wavelength of all light sources, in particular having been exposed to radiation of the wavelengths of all light sources.The glazing element thus comprises multiple light sources with different emission wavelengths and a single diffractive holographic element with a single illuminated area, with all light sources being assigned to this area, and all of the light sources being assigned to this area. Said area of ​​the diffractive holographic element is suitable for deflecting the light from all assigned light sources in such a way that it is coupled into the glass or plastic pane at an angle suitable for the coupled light to propagate within the glass or plastic pane, in particular by total internal reflection.

[0035] The second and third embodiments with the common holographic element are preferred over the first embodiment because it is easier to attach a single holographic element to the glazing element than several separate holographic elements. The third embodiment with the similarly illuminated area is in turn preferred over the second embodiment. In the second embodiment, care must be taken when attaching the light sources to ensure that they are correctly positioned in relation to their assigned area, which is more complex than the third embodiment, in which each light source can be positioned anywhere in the common area. The glazing element can have several sets of light sources with different wavelengths in order to increase the coupled light source. The above statements then apply to each set.Each set is preferably assigned a holographic element, which either has differently exposed areas for each light source or a multi-colored exposed area for all light sources. In principle, it is also possible for all sets to be assigned only a single holographic element, either with differently exposed areas for each individual light source, or with different multi-colored exposed areas for each set, or with a single multi-colored exposed area for all sets.

[0036] The said light sources with different emission wavelengths preferably include:

[0037] - a light source with a red emission colour, preferably with an emission wavelength (maximum of the emission band) in the range from 600 nm to 660 nm, particularly preferably from 610 nm to 650 nm, very particularly preferably from 620 nm to 640 nm (in particular with an emission wavelength of about 630 nm),

[0038] - a light source with a green emission colour, preferably with an emission wavelength in the range from 500 nm to 560 nm, particularly preferably from 510 nm to 550 nm, very particularly preferably from 510 nm to 530 nm (in particular with an emission wavelength of about 520 nm) and

[0039] - a light source with a blue emission color, preferably with an emission wavelength in the range from 430 nm to 490 nm, more preferably from 440 nm to 480 nm, most preferably from 450 nm to 470 nm (in particular with an emission wavelength of about 460 nm).

[0040] The light from these light sources (RGB) is superimposed to form white light, so that white light can be coupled into the glass or plastic pane.

[0041] The light from the light source is coupled into the glass or plastic pane and then spreads through the glazing element. The light is reflected back and forth between two interfaces of the glazing element due to total internal reflection. At least a portion of the glazing element, which includes at least the glass or plastic pane, thus serves as a kind of light guide, distributing the light emitted by the light source across the surface of the glazing element.

[0042] The light guide can be formed exclusively by the glass or plastic pane. The light is then totally reflected at the first and second surfaces and thus propagates within the glass or plastic pane. However, it is also possible for the light guide to comprise one or more additional layers that are bonded to the glass or plastic pane and have the same or a similar refractive index as the glass or plastic pane. This can occur in particular when the glazing element is designed as a composite pane. One or more such additional layers can be bonded to the first surface and / or to the second surface of the glass or plastic pane.Total reflection then occurs at the surfaces of the light guide, each of which represents an interface to an adjacent medium (the surrounding air or a layer of the glazing element) with a significantly lower refractive index.

[0043] The glass or plastic pane (and any adjacent layers that are part of said light guide) is preferably transparent to ensure optimal light propagation. In the context of the invention, this means that the glass or plastic pane has a light transmission relative to the light from the light source of at least 70°, preferably at least 80°, particularly preferably at least 90°. Particularly preferably, the light transmission of the glass or plastic pane is at least 70%, in particular at least 80%, across the entire visible spectral range.

[0044] The first surface of the glass or plastic pane (or the light guide) faces away from the light source, while the second surface faces the light source. The light source illuminates the glass or plastic pane (or the light guide), with the light entering the glass or plastic pane (or the light guide) via the second surface. If a transmissive-diffractive holographic element is used, the light is coupled into the glass or plastic pane (or the light guide) via the second surface and propagates by total internal reflection.If a reflective-diffractive holographic element is used, the light enters the glass or plastic pane (or the light guide) via the second surface, passes through the glass or plastic pane (or the light guide), and then strikes the holographic element (on the first surface or behind the first surface), from which it is deflected and reflected back. It is coupled into the glass or plastic pane (or the light guide) via the first surface and then propagates by total internal reflection. The first and second surfaces of the glass or plastic pane (or the light guide) represent interfaces to an adjacent medium, either the surrounding atmosphere or another layer or position of the glazing element.Typically, the adjacent medium has a different refractive index than the glass or plastic disc (or the light guide). If the adjacent medium has a lower refractive index than the glass or plastic disc (or the light guide), this results in a critical angle of total internal reflection, which is determined as α. T = arcsin(— ), where ni is the refractive index of the glass or plastic disc (or the light guide) and n2 is the refractive index of the adjacent medium.

[0045] The light-diffractive properties, in particular the diffraction angle, of the diffractive holographic element are suitably selected to ensure efficient light coupling and propagation through total internal reflection. Coupling occurs via the second surface of the glass or plastic pane or the light guide (in the case of a transmissive-diffractive holographic element) or via the first surface (in the case of a reflective-diffractive holographic element). This surface represents the entrance surface. The diffraction angle of the holographic element is, in particular, adjusted such that the light (at least partially) strikes the surface opposite the entrance surface at an angle (angle of incidence) that is greater than the critical angle of total internal reflection. The light beam is totally reflected at this opposite surface at an angle of reflection that corresponds to the angle of incidence.The light hits the incident surface again at exactly this angle of incidence, where it is again totally reflected. The light does not escape into the environment and, as a result of repeated total reflection, propagates essentially losslessly through the glass or plastic pane (or the light guide), being reflected back and forth between the two surfaces. 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 reflection.

[0046] In certain embodiments of the invention, the medium adjacent to the first surface of the glass or plastic pane (or the light guide) differs from the medium adjacent to the second surface. This is the case, for example, with composite panes, where one of the surfaces of the glass or plastic pane is bonded to another of the glass or plastic pane via a thermoplastic intermediate layer. Then, one of the surfaces of the glass or plastic pane borders the surrounding atmosphere, and the other surface borders the thermoplastic intermediate layer. Therefore, different critical angles of total reflection occur at the two surfaces.In this case, the diffraction angle of the holographic element is designed in such a way that the light, after refraction at the entrance surface, hits the opposite surface at an angle (angle of incidence) which is greater than the larger critical angle of total reflection.

[0047] The light spreads through the glass or plastic pane (or the light guide) until it either hits the side edge surface of the glass or plastic pane (or the light guide) and is coupled out there, or it hits a light-scattering structure on one of the two surfaces of the glass or plastic pane (or the light guide), which interrupts the total reflection by scattering the light, whereby the light is coupled out of the glass or plastic pane (or the light guide) via the surface in question.

[0048] The glazing element is provided with a light source suitable for coupling light into the glass 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 that 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 that 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.

[0049] The glazing element can have a single light source or several separate light sources whose light is coupled into the transparent layer at different locations.

[0050] The light source preferably comprises or is preferably embodied as at least one light-emitting diode (LED). The light source can be a single light-emitting diode, but is preferably an arrangement of several light-emitting diodes. Said arrangement is preferably installed in a common housing, for example, as a linear arrangement 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).

[0051] The light source can be arranged in a housing that is attached to the glazing element, in particular to the second surface of the glass or plastic pane or to the surface of a further layer of the glazing element that faces away from the glass or plastic pane and is connected to the second surface of the glass or plastic pane. If multiple light sources of different emission colors are used, they are preferably arranged in a common housing that determines the relative positioning of the individual light sources. The housing can, for example, be glued to the glazing element.The light source can alternatively be attached to the glazing element via a transparent component made of glass or plastic, in particular to the second surface of the glass or plastic pane or to the surface of a further layer of the glazing element connected to the second surface of the glass or plastic pane facing away from the glass or plastic pane, or to any transmissive-diffractive holographic element on said surface. The beam path from the light source to the glazing element then runs through the transparent component, which can also act, for example, as a lens or collimator. The light source can, for example, be glued, screwed, or snapped onto the component.

[0052] The light beam can be irradiated into the glazing element or the glass or plastic pane at any angle of incidence. The angle of incidence is determined as the angle to the surface normal on the entrance surface. A major advantage of the invention is that the hologram can be very flexibly adapted to the requirements of each individual case. The optimal coupling angle (the angle at which the light penetrates the glass or plastic pane after diffraction by the diffractive holographic element) can be determined by simulations depending on the light guide used.The light-diffractive hologram, the angle of incidence, and the light source (particularly its light cone and emission color) can then be suitably selected so that the largest possible proportion of the light (preferably essentially all of the light) is coupled into the glass or plastic pane (or the light guide) in such a way that total internal reflection occurs at the surface layer and the light thus spreads. When designing the light-diffractive hologram, particular consideration is given to the type of light source and the angle of incidence so that the largest possible proportion of the light enters the glass or plastic pane at the desired angle of incidence to ensure total internal reflection. Any refraction effects at interfaces are also taken into account.

[0053] In a preferred embodiment, the glass or plastic pane is provided with at least one light-scattering structure suitable for coupling the light out of the glass or plastic pane via the first surface and / or the second surface. The light-scattering structure is arranged on the first or second surface or is in contact with said surface. When the light propagating in the glass or plastic pane strikes the light-scattering structure, it is scattered, preventing total internal reflection and allowing the scattered light to be coupled out and exit the glazing element.

[0054] The light-diffusing structure appears as a luminous surface of the glazing element. This can be used, for example, to illuminate an interior or to display symbols or patterns that serve to convey information or may be intended for purely aesthetic reasons. The light-diffusing structure can be present in a single, contiguous area of ​​the glazing element or in several separate areas. The light-diffusing structure allows for the realization of any shape or pattern.

[0055] The light-diffusing structure can be applied directly to the first or second surface of the glass or plastic pane or formed there. Alternatively, the light-diffusing structure can be provided, for example, on a carrier film that is attached to the first or second surface of the glass or plastic pane, for example by gluing. If the glazing element according to the invention is a laminated pane, the light-diffusing structure can be applied to the surface of a thermoplastic intermediate layer that is in contact with the glass or plastic pane. Alternatively, the light-diffusing structure (for example, applied to a carrier film) can be inserted between the glass or plastic pane and the intermediate layer.In an advantageous embodiment, the light-scattering structure is formed as a print, in particular as a print on one of the surfaces of the glass or plastic pane or - in the case of a composite pane - on the surface of the adjacent intermediate layer facing the glass or plastic pane. In the case of a glass pane, 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, which are fired into the surface of the glass layer, creating a roughened and therefore light-scattering surface. A print on a polymeric layer (for example an intermediate layer or a plastic pane) can be realized by printing a surface of the polymeric layer with a light-scattering printing paste, for example using a screen printing process.In an advantageous embodiment, the light-scattering structure is transparent, so that it does not significantly restrict visibility through the glazing element. The print (the enamel or printing paste) therefore preferably contains no pigment. However, opaque or semi-transparent light-scattering structures with pigments are also conceivable, for example, white structures.

[0056] Light-diffusing structures can also be created by roughening the relevant surface of the glass or plastic pane. This roughening can be achieved mechanically (e.g., by grinding) or by laser processing. Laser processing, particularly in the case of a laminated pane, has the advantage that the light-diffusing structure can also be incorporated into the finished laminated pane, even if it is intended to be located inside the laminated pane, since the laser radiation can also be focused onto a plane inside the laminated pane. Laser processing also makes it possible to create the light-diffusing structure not on a surface, but inside the glass or plastic pane.

[0057] However, the light-diffusing structure is not absolutely necessary within the scope of the present invention. Applications are also conceivable in which the light is to be coupled out via the side edge surface of the glass or plastic pane (or the light guide), whereby no light-diffusing structures are necessary on the first or second surface. Such illumination may be desirable for aesthetic reasons, for example as a type of ambient light function. The glazing element can be a monolithic pane, in particular a single pane of glass. Structurally, the glazing element is formed exclusively by the glass or plastic pane according to the invention, in particular a glass pane. The glass or plastic pane serves as a light guide, whereby the total reflection of the propagating light occurs at the first and second surfaces of the glass or plastic pane.The glass or plastic pane has, for example, a thickness of 1 mm to 10 mm. The monolithic pane is typically intended as a window pane for separating an interior space from an external environment. It has an interior-side surface that, in the installed position, faces the interior space, and an exterior-side surface that, in the installed position, faces the external environment. The interior-side surface is preferably the second surface within the meaning of the invention, and the light source is attached to it. The exterior surface is the first surface within the meaning of the invention.

[0058] In an advantageous embodiment, however, the glazing element according to the invention is designed as a composite pane. The glass or plastic pane according to the invention is connected to another glass or plastic pane via a thermoplastic intermediate layer. The composite pane is also typically intended as a window pane for separating an interior space from an external environment, with the pane facing the interior space being referred to as the inner pane and the pane facing the external environment being referred to as the outer pane. The outer pane and inner pane each have an interior-side surface that, in the installed position, faces the interior space, and an exterior-side surface that, in the installed position, faces the external environment.

[0059] Preferably, the glass or plastic pane according to the invention is the inner pane, and the further glass or plastic pane is the outer pane of the composite pane. The second surface of the glass or plastic pane according to the invention is preferably its interior-facing surface, which faces away from the intermediate layer and the outer pane, and the light source is attached to it. The first surface of the glass or plastic pane according to the invention is then connected to the outer pane via the thermoplastic intermediate layer.

[0060] Such a composite pane can be equipped with a transmissive-diffractive holographic

[0061] Element or with a reflective-diffractive holographic element. The transmissive-diffractive holographic element is arranged between the glass or plastic pane (inner pane) and the light source, preferably on the interior surface of the glass or plastic pane facing away from the intermediate layer. The reflective-diffractive holographic element is preferably arranged between the outer pane and the inner pane, particularly preferably on the outer surface of the glass or plastic pane (inner pane) facing the intermediate layer. A transmissive-diffractive holographic element is particularly preferred because it does not have to be integrated into the composite pane during manufacture, but can be attached subsequently. The integration of the holographic element therefore does not make the manufacture of the composite pane more technically and time-consuming.

[0062] If at least one layer of the intermediate layer adjacent to the glass or plastic pane (inner pane) is also part of the light guide, the reflective-diffractive holographic element is preferably arranged on the surface of said at least one layer facing away from the glass or plastic pane.

[0063] 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 is preferably made of soda-lime glass. The intermediate layer has a thickness of, for example, 0.3 mm to 1.0 mm. It is preferably formed from at least one thermoplastic film, for example based on polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA) or polyurethane (PU). In the context of the invention, this means that the film consists predominantly of the said material, i.e. the proportion of the material is more than 50% by weight, preferably more than 60% by weight. In addition, the film can contain further components, for example plasticizers, stabilizers, UV or IR blockers.

[0064] In an alternative embodiment, the glass or plastic pane according to the invention forms a thin light guide which is embedded in the intermediate layer of a composite pane. The glass or plastic pane is arranged between two panes (in particular an outer pane and an inner pane) and is connected to the first pane (outer pane) via at least one thermoplastic layer and to the second pane (inner pane) via at least one thermoplastic layer. The adjacent thermoplastic layers can have a lower refractive index than the glass or plastic pane, so that the latter can act as a light guide as a result of total internal reflection. Alternatively, the surfaces of the glass or plastic pane can be provided with a coating with a lower refractive index. The light-conducting glass or plastic pane preferably has a thickness of 0.2 mm to 1.5 mm, particularly preferably of 0.5 mm to 1 mm.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 thermoplastic layers have a thickness of, for example, 0.3 mm to 1.0 mm and are preferably each formed from a thermoplastic film, for example based on polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), or polyurethane (PU).

[0065] Such a composite pane can also be realized with a transmissive-diffractive holographic element or with a reflective-diffractive holographic element. The transmissive-diffractive holographic element can be arranged on the surface of the light-guiding glass or plastic pane facing the light source. Alternatively, the transmissive-diffractive holographic element can be arranged on the surface of the pane facing the light source (in particular the inner pane) facing the light source. The reflective-diffractive holographic element can be arranged on the surface of the light-guiding glass or plastic pane facing away from the light source.

[0066] The holographic element preferably comprises at least one carrier film and a photopolymer layer. If the holographic element is attached to an exposed surface of the glazing element (for example, the surface of a monolithic pane or the interior-facing surface of the inner pane of a composite pane), it may be preferred for the holographic element to have only a single carrier film and the photopolymer layer, wherein the carrier film faces away from said exposed surface and the photopolymer layer is attached to said surface, for example, via an optically clear adhesive. However, the photopolymer layer can also be arranged between two carrier films, wherein one of the carrier films is attached to said surface, for example, via an optically clear adhesive.If, however, the holographic element is arranged inside a composite pane, it preferably comprises a photopolymer layer between two carrier films.

[0067] 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. In an advantageous embodiment, the light source is arranged in the masking region and the light is coupled in via the diffractive holographic element in the masking region. The masking region is particularly preferably formed by an opaque masking print on the interior-side surface of the further glass or plastic pane (outer pane).Such a cover print is typically formed by an enamel containing glass frits and a black pigment, which is screen printed and then fired into the surface.

[0068] If the glass or plastic pane according to the invention is a glass pane, it is preferably made of soda-lime glass, as is common for window panes. Alternatively, the glass pane can also be made of other types of glass, for example, borosilicate glass, aluminosilicate glass, or quartz glass. If the glass or plastic pane according to the invention is a plastic pane, it is preferably made of a clear, rigid plastic, particularly preferably polycarbonate (PC) or polymethyl methacrylate (PMMA).

[0069] The glass or plastic pane according to the invention is preferably clear and has no significant tints or colorations to ensure efficient light propagation. In the case of a laminated pane, the additional glass or plastic pane and the intermediate layer can also be clear, tinted, or colored.

[0070] The glazing element can be flat or curved in one or more directions of the room.

[0071] The invention also comprises a method for producing an illuminated glass element according to the invention, wherein

[0072] - the glass pane or plastic pane is provided with the first surface and the second surface,

[0073] - the light source is mounted so that the second surface of the glass or plastic sheet faces the light source, the diffractive holographic element is mounted so that it is irradiated by the light source.

[0074] The light source can be attached before or after the diffractive holographic element is attached.

[0075] The diffractive holographic element is preferably created by holographically exposing a light-sensitive polymer film to produce a light-diffracting hologram. For this purpose, light of the same wavelength (or wavelengths) emitted by the light source (or light sources) is used. Thus, light with the same emission wavelength as the light source is used as the reference wave during exposure.

[0076] If the glazing element is designed as a composite pane, conventional lamination processes can be used for its production, 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 under the influence of heat, vacuum, and / or pressure.

[0077] The invention further encompasses the use of a glazing element according to the invention as a window pane of a vehicle. A particularly preferred use is a vehicle roof pane, which is used to illuminate the vehicle interior. The vehicle can in principle be any land vehicle, watercraft, or aircraft, and is preferably a passenger car, truck, or rail vehicle. The glazing element 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 glazing element can also be used as a component of furniture, electrical devices, as a component of furnishings, or as a furnishing. The invention is explained in more detail below with reference to drawings 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 glazing element according to the invention,

[0080] Fig. 2 is an enlarged view of section Z from Figure 1,

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

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

[0083] Figures 1 and 2 each show a detail of a first embodiment of the glazing element according to the invention. Figure 1 shows a cross-section of the glazing element. A section Z is marked there, which is shown enlarged in Figure 2.

[0084] The glazing element is designed as a laminated pane. The laminated pane 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 laminated pane is structurally formed from a glass pane 2, which serves as the inner pane, and another glass pane, which serves as the outer pane 1, and a thermoplastic intermediate layer 3, via which the glass pane 2 and the outer pane 1 are connected to one another. The outer pane 1 and the glass pane 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 glass pane 2 is clear, the outer pane 1 and the intermediate layer 3 are tinted to reduce the light transmission of the laminated pane (for example to less than 15%), as is common with vehicle roof windows.

[0085] In the installed position, the outer pane 1 faces the exterior environment of the vehicle. It has an outside surface I facing the exterior environment and an inside surface II facing the vehicle interior. The glass pane 2 (inner pane) faces the vehicle interior in the installed position. It has an outside surface III facing the exterior environment and an inside surface IV facing the vehicle interior. The inside surface II of the outer pane 1 and the outside surface III of the glass pane 2 are connected to one another via the thermoplastic intermediate layer 3.

[0086] The laminated pane has a surrounding, opaque edge region (masking region) in which a black masking print 9 is applied to the interior-facing surface II of the outer pane 1, preventing visibility through the laminated pane. In this edge region, a diffractive holographic element 4 is attached to the interior-facing surface IV of the glass pane 2, for example, using a layer of optically clear adhesive (not shown). The diffractive holographic element 4 is provided for coupling the light from a light source 5 into the glass pane 2.

[0087] The light source 5 is a light-emitting diode (LED), for example, with a green emission color and a mean emission wavelength of 550 nm. The light source 5 is connected to the diffractive holographic element 4 via a collimator 7. The collimator 7 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 5, ideally to a parallel beam path. The light from the light source 5 passes through the collimator 7 and then strikes the diffractive holographic element 4.

[0088] The diffractive holographic element 4 is a holographic film in which a hologram is formed. The hologram was generated using the same wavelength as the light source 5, for example, by exposure to a laser with a wavelength of 550 nm. This allows the holographic element 4 to optimally exert its effect on the light from the light source 5. The hologram creates a type of diffraction pattern, which results, for example, from complex refractive index changes that were formed in the holographic film during exposure. The diffractive holographic element 4 is suitable and intended to diffract the light from the light source 5 and thereby change its propagation direction.

[0089] The diffraction angle α describes the change in the direction of light propagation (represented by dashed arrows). The diffraction angle α is the angle between the light vector incident on the diffractive holographic element 4 and the light vector emanating from the diffractive holographic element 4. The diffraction angle α lies between 90° and 180° and is, for example, approximately 102°. This is therefore a transmissive-diffractive holographic element, with the light largely passing through the holographic element 4 with a changed direction of propagation.

[0090] The surfaces III, IV of the glass pane 2 each represent an interface to a neighboring optically less dense medium. At the wavelength of the light source 5 of 550 nm, the refractive index of the glass pane 2 is 1.53 (soda-lime glass), the refractive index of the intermediate layer 3 is 1.48 (PVB) and the refractive index of air is approximately 1.00. For both surfaces III, IV, a critical angle of total reflection can be calculated from this: 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.

[0091] The light from light source 5 is radiated into the glass pane 2 via the interior surface IV, where it is deflected by the holographic element 4 at a diffraction angle of 102°. The light then passes through the glass pane 2 and strikes the exterior surface III at an angle of incidence of 78° (also measured relative to the surface normal). Since the angle of incidence is greater than the critical angle of total internal reflection, the light is totally reflected, passes through the glass pane 2 again, and strikes the interior surface IV at an angle of incidence of 78°. Here, too, the angle of incidence is greater than the critical angle of total internal reflection, so that the light is again totally reflected. In this way, the light is reflected back and forth between the surfaces III and IV, so that it spreads out into the glass pane 2. The glass pane 2 acts as a type of flat light guide.

[0092] In order to decouple the light back out of the glass pane 2 and thereby create illumination, light-diffusing structures 6 made of transparent enamel are printed on the interior-side surface IV. When the light strikes these light-diffusing structures 6, it is scattered and thus decoupled from the glass pane 2. The light-diffusing structures 6 thus appear to an observer as luminous surfaces, which can be used, for example, for illumination or to display symbols or patterns. Light that does not strike the light-diffusing structures 6 reaches the side edge surface of the glass pane 2 and is decoupled via this. In the illustrated embodiment, the light from the light source 5 strikes the interior-side surface IV or the holographic element 4 at an incident angle of 0° (measured to the surface normal) before being coupled in.However, it is also possible to irradiate the light not perpendicularly, but at an angle of incidence other than 0°. By choosing the angle of incidence and the diffraction angle α, total internal reflection can be ensured depending on the critical angle of total internal reflection. The light must strike surfaces III and IV at an angle greater than the largest critical angle of total internal reflection.

[0093] The collimator 7 is merely optional; it primarily improves the light yield. Alternatively, the light source 5 could, for example, also be arranged in a housing attached to the interior surface IV of the glass pane 2, or be connected to the holographic element 4 via a transparent component that has no effect on the beam cone, in particular, it does not act as a collimator.

[0094] Figures 3 and 4 each show a detail of a second embodiment of the glazing element according to the invention. Figure 3 shows a cross-section of the glazing element. A section Y is marked there, which is shown enlarged in Figure 4.

[0095] The glazing element is designed as a composite pane, just as in the first embodiment of Figure 1, with the glass pane 2 as the inner pane, the further glass pane as the outer pane 1, the thermoplastic intermediate layer 3, the cover print 9 and the light-scattering structures 6. The second embodiment differs from the first embodiment in the type of light coupling.

[0096] The light from the light source 5 is again radiated via the interior surface IV into the glass pane 2 at an angle of incidence of 0°, although the angle of incidence may also deviate from 0°. An optional collimator 7 is arranged on the interior surface IV of the glass pane 2, which in this case is designed as a holographic film that acts as a type of converging lens (holographic-optical component). The collimator 7 is, for example, glued to the interior surface IV, in particular via a layer of optically clear adhesive (not shown). The light source can, for example, be arranged in a housing (not shown) that is attached to the interior surface IV of the glass pane 2. The light radiated via the interior surface IV passes through the glass pane.

[0097] 2 and strikes the outer surface III. A diffractive holographic element 4 is arranged there and is irradiated by the light. The diffractive holographic element 4 can simply be inserted between the intermediate layer 3 and the glass pane 2, whereby it is fixed in place during the lamination of the composite pane. However, it is also possible for the diffractive holographic element 4 to be attached to the glass pane 2 or the intermediate layer

[0098] 3 is glued, in particular by means of optically clear adhesive.

[0099] The diffractive holographic element 4 again acts as a light-diffractive element to change the propagation direction of the light and couple the light into the glass pane 2. The diffraction angle α in this case lies between 0° and 90° and is, for example, approximately 78°. This is therefore a reflective-diffractive holographic element, with the light being largely reflected by the holographic element 4 with a changed propagation direction.

[0100] The light is coupled from the holographic element 4 via the outer surface III into the glass pane 2. It passes through the glass pane 2 and strikes the interior surface IV at an angle of incidence of 78°. This angle of incidence is greater than the greatest critical angle of total internal reflection of the glass pane 2, so that the light propagates again in the manner of a light guide within the glass pane 2.

[0101] List of reference symbols:

[0102] (1) Outer pane

[0103] (2) Glass pane

[0104] (3) thermoplastic intermediate layer

[0105] (4) diffractive holographic element

[0106] (5) Light source

[0107] (6) light-scattering structure

[0108] (7) Collimator

[0109] (9) Cover printing

[0110] (I) first / outside surface of the outer pane 1

[0111] (II) second / interior-side surface of the outer pane 1

[0112] (III) first / outer surface of the inner pane 2

[0113] (IV) second / interior-side surface of the inner pane 2

[0114] (a) Diffraction angle

[0115] Z enlarged section

[0116] Y enlarged section

Claims

Patent claims 1. Illuminated glazing element, comprising - a glass pane (2) or plastic pane with a first surface (III) and a second surface (IV), - a light source (5) for generating light, wherein the second surface (IV) of the glass pane (2) or plastic pane faces the light source (5), - a diffractive holographic element (4) which is irradiated by the light source (5), wherein the diffractive holographic element (4) is suitable for deflecting the light in such a way that it is coupled into the glass pane (2) or plastic pane and propagates at least in the glass pane (2) or plastic pane, in particular by total reflection.

2. Illuminated glazing element according to claim 1, wherein the diffractive holographic element (4) is a transmissive-diffractive holographic element which is arranged between the light source (5) and the second surface (IV) of the glass pane (2) or plastic pane.

3. Illuminated glazing element according to claim 2, wherein the diffractive holographic element (4) is glued to the second surface (IV) of the glass pane (2) or plastic pane, preferably via a layer of an optically clear adhesive.

4. Illuminated glazing element according to claim 1, wherein the diffractive holographic element (4) is a reflective-diffractive holographic element and wherein the glass pane (2) or plastic pane is arranged between the light source (5) and the diffractive holographic element (4).

5. Illuminated glazing element according to claim 4, wherein the diffractive holographic element (4) is arranged on the first surface (III) of the glass pane (2) or plastic pane.

6. Illuminated glazing element according to one of claims 1 to 5, wherein the glass pane (2) or plastic pane and optionally adjacent layers of the Glazing element form a light guide between a first and a second interface to an optically less dense medium and wherein the light is coupled in via one of the interfaces in such a way that it hits the opposite interface at an angle of incidence which is greater than the largest critical angle of total reflection of the light guide.

7. Illuminated glazing element according to claim 6, wherein the light guide is formed exclusively by the glass pane (2) or plastic pane and wherein the first surface (III) and the second surface (IV) of the glass pane (2) or plastic pane are said boundary surfaces.

8. Illuminated glazing element according to one of claims 1 to 7, wherein the light source (5) comprises at least one light-emitting diode (LED).

9. Illuminated glazing element according to one of claims 1 to 8, which comprises a set of several light sources (5) with different emission wavelengths, wherein a common diffractive holographic element (4) is assigned to the several light sources (5), wherein - the holographic element (4) has several regions and each region is associated with a light source (5) and is illuminated with the emission wavelength of this light source (5), or - the holographic element (4) has a single region which is assigned to all light sources (5) and is exposed to the emission wavelengths of all light sources (5).

10. Illuminated glazing element according to claim 9, wherein a plurality of light sources (5) comprise: - a light source (5) with an emission wavelength in the range from 600 nm to 660 nm, preferably from 610 nm to 650 nm, particularly preferably from 620 nm to 640 nm, - a light source (5) with an emission wavelength in the range from 500 nm to 560 nm, preferably from 510 nm to 550 nm, particularly preferably 510 nm to 530 nm, - a light source (5) having an emission wavelength in the range from 430 nm to 490 nm, preferably from 440 nm to 480 nm, particularly particularly 450 nm to 470 nm.

11. Illuminated glazing element according to one of claims 1 to 10, wherein the glass pane (2) or plastic pane is provided with at least one light-scattering structure (6) which is suitable for coupling the light out of the glass pane (2) or plastic pane via the first surface (III) and / or via the second surface (IV).

12. Illuminated glazing element according to one of claims 1 to 11, which is designed as a composite pane, comprising an outer pane (1) and the glass pane (2) or plastic pane, wherein the first surface (III) of the glass pane (2) or plastic pane is connected to the outer pane (1) via a thermoplastic intermediate layer (3).

13. Illuminated glazing element according to one of claims 1 to 12, which is designed as a composite pane, wherein the glass pane (2) or plastic pane is arranged between an outer pane (1) and an inner pane and is connected to the outer pane (1) via at least one thermoplastic layer and to the inner pane via at least one thermoplastic layer.

14. A method for producing an illuminated glazing element according to any one of claims 1 to 13, wherein - the glass pane (2) or plastic pane is provided with the first surface (III) and the second surface (IV), - the light source (5) is mounted so that the second surface (IV) of the glass pane (2) or plastic pane faces the light source (5), - the diffractive holographic element (4) is mounted so that it is irradiated by the light source (5).

15. The method according to claim 14, wherein the diffractive holographic element (4) is produced by holographically exposing a light-sensitive polymer film to produce a light-diffractive hologram, wherein light having the emission wavelength of the light source (5) is used for the exposure.

16. Use of an illuminated glazing element according to one of claims 1 to 13 as a window pane of a vehicle, a building or an interior, as a component of furniture, electrical equipment, as a component of furnishings or as a furnishing, preferably as a vehicle roof window.

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