DE202021004037U1 - Vehicle window with an electroluminescent device and an optical band-stop filter - Google Patents

Abstract

Vehicle pane consisting of an outer pane (1), which has an outside surface (I) and an inside surface (II), and an inner pane (2), which has an outside surface (III) and an inside surface (IV), the inside Surface (II) of the outer pane (1) and the outside surface (III) of the inner pane (2) are connected to one another via a thermoplastic intermediate layer (3), equipped with an electroluminescent device (20, 30) and an optical band-stop filter (40, 50 ) with a blocking area, wherein- the optical band-stop filter (40, 50) is designed as a thin-layer coating of optically high-index layers with a refractive index greater than 1.8 and optically low-index layers with a refractive index less than 1.8, which are arranged alternately,- the mean wavelength of the radiation emitted by the electroluminescent device (20, 30) in the stop region of the optical band blocking filter (40, 50), - the optical band blocking filter (40, 50) is arranged in such a way that the emission of the electroluminescent device (20, 30) over the outer pane (1) or over the inner pane (2) is blocked and the full width at half maximum (Δλ) of the stop band of the band elimination filter (40, 50) is from 10 nm to 50 nm.

Description

The invention relates to a vehicle window with an electroluminescent device and an optical bandstop filter, and a vehicle equipped therewith.

It is known to equip vehicle windows with electroluminescent devices. Depending on the application, the electroluminescent devices can be designed as flat light sources in the manner of an LED or OLED or in the form of individual light-emitting diodes (LEDs, light emitting diodes). A planar light source can be introduced into the thermoplastic intermediate layer of a laminated pane, for example in the form of an electroluminescent film. Discrete light-emitting diodes can, for example, also be embedded in the thermoplastic intermediate layer of a composite pane or be attached to one of the individual panes of the composite pane. Vehicle windows with electroluminescent devices are known, for example DE102016209914 , WO2017203132 or WO2017103426 .

The electroluminescent devices have an intended emission direction, which is usually directed into the vehicle interior. For example, vehicle roof panes are known whose electroluminescent devices are used to illuminate the vehicle interior. Likewise, windshields are known whose electroluminescent devices are used to generate a display for the driver.

However, the radiation from electroluminescent devices is not directional, or only to a small extent. All of these applications therefore have in common that the electroluminescent device not only radiates in the intended direction of emission, but also in the opposite direction. If the electroluminescent devices are arranged in the viewing area of the vehicle window, the undesired emission cannot be prevented by opaque elements such as a peripheral masking print. The radiation in the undesired direction is then at least annoying, if not completely unacceptable for the user.

WO2017103426A1 discloses a vehicle window with an electroluminescent device. A color filter can be present in the emission direction of the electroluminescent device in order to filter out parts of the white radiation of the electroluminescent device and thereby provide the radiation with a color. The color filter can be designed as a dielectric interference filter made of alternating optically high and low refractive layers. In the opposite direction, radiation is prevented by an opaque masking print.

US20150228696A1 discloses another vehicle window having an electroluminescent device. US20150228696A1 also teaches that radiation in the undesired direction can be prevented by a reflective element. The reflective element can be designed as a metal-containing coating or as a dielectric mirror.

WO2014029536A1 discloses a vehicle window with a switchable functional element, which can be an electroluminescent device, for example. The vehicle window has an IR-reflecting coating to protect the functional element from impairment by infrared components of solar radiation.

DE102017003621A1 discloses another vehicle window with an electroluminescent device, wherein radiation in the undesired direction is prevented by an opaque masking print.

The object of the present invention is to provide a vehicle window with an electroluminescent device in which the radiation in the undesired emission direction is prevented or at least significantly reduced.

The object of the present invention is achieved according to the invention by a vehicle window according to claim 1 . Preferred embodiments emerge from the dependent claims.

The invention is based on the combination of an electroluminescent device with an optical band-stop filter. With regard to its optical properties, the band stop filter is matched to the radiation of the electroluminescent device and is arranged so that it overlaps with the electroluminescent device in such a way that radiation into the external environment or into the vehicle interior is prevented. The bandstop filter is designed as a thin-layer coating that acts as an interference filter. Of the In this way, the band stop filter can be set very precisely with regard to its optical properties and can be integrated into the vehicle window in an optically unobtrusive manner. These are great advantages of the present invention.

The vehicle pane according to the invention is designed as a composite pane. It comprises an outer pane and an inner pane, which are connected to one another via a thermoplastic intermediate layer. The vehicle window is intended to separate the vehicle interior from the outside environment in a window opening of a vehicle. In the context of the invention, inner pane refers to the pane of the vehicle pane facing the interior in the installed position. The outer pane refers to the pane facing the outside environment.

The outer pane and the inner pane each have an outside and an inside surface and a circumferential side edge running in between. Within the meaning of the invention, the outside surface designates that main surface which is intended to face the external environment in the installed position. Within the meaning of the invention, the interior-side surface designates that main surface which is intended to face the interior in the installed position. The interior surface of the outer pane and the outside surface of the inner pane face each other and the thermoplastic intermediate layer and are connected to one another by the thermoplastic intermediate layer.

The intermediate layer of the vehicle window is formed by at least one layer of thermoplastic material (connecting material). The intermediate layer can consist of this one layer of thermoplastic material and can be formed, for example, from a single polymer film or cast resin layer. However, the intermediate layer can also comprise a plurality of layers of thermoplastic material and be formed, for example, from a plurality of polymer films arranged flat on top of one another.

According to the invention, the vehicle window is equipped with an electroluminescent device. The electroluminescent device can also be referred to as an electroluminescent device. The electroluminescent device is preferably monochromatic, ie emits radiation of only one color, in contrast to multicolored devices. Monochromatic radiation can be blocked particularly efficiently by the bandstop filter because it is typically optimized for one color. In the case of multicolor electroluminescent devices, multiple notch filters can be used.

The electroluminescent device can be designed, for example, as an electroluminescent film, in particular in the manner of an LED or OLED (organic light-emitting diode, organic light-emitting diode) and can represent a planar light source. An electroluminescent film comprises an active layer that contains electroluminescent material and that is contacted on both sides by a transparent electrode layer (for example made of silver or ITO), and electrically insulating carrier layers as outer layers, between which the active layer with the electrodes is enclosed. The electroluminescent device can alternatively be formed, for example, from a plurality of light-emitting diodes, which then form discrete, approximately punctiform light sources. All light-emitting diodes preferably have the same emission color. Through electrical excitation, the electroluminescent device emits electromagnetic radiation in the visible spectral range.

The electroluminescent device is preferably arranged in the see-through area of the pane, which is not provided with additional opaque elements. The invention is particularly advantageous there.

According to the invention, the vehicle window is also provided with an optical band stop filter. The optical band-stop filter is designed as a thin-layer coating of optically high-refractive layers and optically low-refractive layers. The optically high refractive layers have a refractive index greater than 1.8, the optically low refractive layers have a refractive index less than 1.8. In the context of the present invention, information on the refractive index relates to a wavelength of 550 nm. The optically high-index layers and optically low-index layers are arranged alternately, ie alternately one above the other. The thin-layer coating preferably comprises n optically high-index layers with a refractive index greater than 1.8 and n optically low-index layers with a refractive index less than 1.8, where n is a natural number greater than or equal to 1. Particularly preferably, the thin-film coating consists of n optically low-refractive layers and (n+1) optically high-refractive layers, which are each arranged alternately. The top and bottom layers of the coating are correspondingly optically high-index layers. This achieves the best interference effects. However, it is also possible that the thin-film coating of n optically low-index layers and n optically high-index layers or consists of (n+1) optically low-index layers and n optically high-index layers, even if the interference effect is generally weaker as a result.

• - Die Zentralwellenlänge gibt den Mittelpunkt des Sperrbereichs an.
• - Die Minimaltransmission gibt den kleinsten Transmissionswert an, der innerhalb des Sperrbereichs auftritt.
• - Die Blocktiefe beschreibt die Differenz zwischen dem Transmissionswert, der an den dem Sperrbereich benachbarten lokalen Transmissionsmaxima auftritt, und der Minimaltransmission. Ist die Transmissionswert der lokalen Transmissionsmaxima beidseitig des Sperrbereichs unterschiedlich, so ist der Mittelwert heranzuziehen.
• - Die Breite des Sperrbereichs wird als Bandbreite bezeichnet und kann als Halbwertsbreite beschrieben werden. Die obere und untere Grenze der Bandbreite ist als die Wellenlänge definiert, bei welcher der Filter 50% der Blocktiefe erreicht, bei denen also ein Transmissionswert auftritt, der 50% der Blocktiefe zuzüglich der Minimaltransmission beträgt.
• - Die Steigung beschreibt den Spektralbereich, über den der Filter von hoher Blockung zu hoher Transmission übergeht. An beiden Begrenzungen des Sperrbereichs kann eine Steigung bestimmt werden als der Spektralbereich zwischen der Wellenlänge, bei der 80% der Blocktiefe erreicht werden (der Transmissionswert beträgt 80% der Blocktiefe zuzüglich der Minimaltransmission), und der Wellenlänge, bei der 10% der Blocktiefe erreicht werden (der Transmissionswert beträgt 10% der Blocktiefe zuzüglich der Minimaltransmission).

An optical bandstop filter is an optical filter that blocks the transmission of electromagnetic radiation in a certain spectral range, i.e. significantly weakens it (particularly as a result of reflection), while electromagnetic radiation with shorter and longer wavelengths is largely transmitted, i.e. only slightly or insignificantly is weakened. Said spectral range within which the radiation is blocked is referred to as the blocking range. The band stop filter is the complementary counterpart of an optical band pass filter. The optical properties of the notch filter can be described quantitatively by a number of parameters which are used within the scope of the present invention as follows:

• - The central wavelength indicates the midpoint of the stop band.
• - The minimum transmission indicates the smallest transmission value that occurs within the stop band.
• - The block depth describes the difference between the transmission value, which occurs at the local transmission maxima adjacent to the stop band, and the minimum transmission. If the transmission value of the local transmission maxima is different on both sides of the blocking range, the mean value should be used.
• - The width of the stopband is called the bandwidth and can be described as the full width at half maximum. The upper and lower limit of the bandwidth is defined as the wavelength at which the filter reaches 50% of the block depth, ie at which a transmission value occurs that is 50% of the block depth plus the minimum transmission.
• - The gradient describes the spectral range over which the filter changes from high blocking to high transmission. At both limits of the stop band, a slope can be determined as the spectral range between the wavelength at which 80% of the block depth is reached (the transmission value is 80% of the block depth plus the minimum transmission) and the wavelength at which 10% of the block depth is reached (the transmission value is 10% of the block depth plus the minimum transmission).

The transmittance, the wavelength-dependent plotting of which results in the transmission spectrum, is measured in the sense of the invention with an angle of incidence of 0° to the normal to the surface.

The radiation emitted by the electroluminescent device is in the stop band of the optical band elimination filter. In the context of the invention, this is particularly the case when the mean wavelength of the electroluminescent radiation is “within the bandwidth (full width at half maximum) of the band elimination filter”, i.e. the difference between the central wavelength of the band elimination filter and the mean wavelength of the electroluminescent radiation is less than half the full width at half maximum of the band elimination filter. The average wavelength of the electroluminescent radiation is then in the blocking range of the band-stop filter. The full width at half maximum of the band elimination filter should be greater than the full width at half maximum of the electroluminescent spectrum of the electroluminescent device. Preferably, the sum of half the full width at half maximum of the electroluminescent radiation and the difference between the central wavelength of the bandstop filter and the middle wavelength of the electroluminescent radiation is less than half the maximum width at half maximum of the bandstop filter. This achieves a particularly good blocking effect. The minimum transmission of the band stop filter is preferably less than 20%. The full width at half maximum of the band-stop filter (more precisely: the blocking range of the band-stop filter) is preferably at least 10 nm, for example from 10 nm to 50 nm, particularly preferably from 20 nm to 50 nm, very particularly preferably from 20 nm to 30 nm. Preference is given to at least 50 % of the radiation from the electroluminescent device (more precisely, the intensity of the radiation emitted in the direction of the band-stop filter) is not transmitted by the band-stop filter, more preferably at least 70%.

The blocking range of the band stop filter is in the visible spectral range from 380 nm to 780 nm. The blocking range of the band stop filter is preferably completely in the visible spectral range, so that it does not extend beyond the limits of the visible spectral range. Of course, the blocking range does not cover the entire visible spectral range, but preferably has a half-width in the range mentioned above.

The optical band stop filter is arranged in or on the vehicle window in such a way that the emission of the electroluminescent device beyond the outer window or beyond the inner window is blocked, ie prevented or at least significantly reduced.

The emission of the electroluminescent device via a pane selected from the outer pane and the inner pane is therefore blocked by the band stop filter. The electroluminescent device emits into the environment via the other pane, selected from the outer pane and inner pane. In particular, the radiation through said other pane is not prevented (e.g. by an opaque element such as a masking print) or significantly specifically attenuated (e.g. by a band-stop filter). Of course, the radiation can still be easily attenuated by elements of the vehicle pane which do not specifically affect the radiation of the electroluminescent device, for example by the pane itself or a coating located thereon.

The band stop filter preferably allows at most 50% of the incident radiation to pass through the electroluminescent device, ie the degree of blocking is at least 50%. To this end, the band elimination filter and the electroluminescent device are arranged superimposed as seen through the vehicle window, by which is meant that the orthogonal projection of the electroluminescent device onto the plane of the band elimination filter is arranged entirely within the band elimination filter. Depending on the intended emission direction of the electroluminescent device, the optical bandstop filter can be arranged on the outside or inside of the electroluminescent device. The outside arrangement of the band elimination filter means within the meaning of the invention that the band elimination filter is arranged closer to the exterior of the vehicle than the electroluminescent device in the installed position, ie has a smaller distance to the exterior. This case occurs when the intended direction of emission is directed into the vehicle interior. Then the emission of the electroluminescent device into the external environment, ie beyond the outer pane, is prevented or at least reduced. The arrangement of the band elimination filter on the interior side means within the meaning of the invention, however, that the band elimination filter is arranged closer to the vehicle interior than the electroluminescent device in the installed position, ie has a smaller distance to the vehicle interior. This case occurs when the intended direction of emission is directed towards the outside environment. The emission of the electroluminescent device into the vehicle interior, ie beyond the inner pane, is then prevented or at least reduced.

• - Die elektrolumineszente Vorrichtung ist auf der innenraumseitigen Oberfläche der Innenscheibe angeordnet. Der Bandsperrfilter ist auf der außenseitigen Oberfläche der Innenscheibe, innerhalb der Zwischenschicht, auf der innenraumseitigen Oberfläche der Außenscheibe oder auf der außenseitigen Oberfläche der Außenscheibe angeordnet.
• - Die elektrolumineszente Vorrichtung ist auf der außenseitigen Oberfläche der Innenscheibe angeordnet. Der Bandsperrfilter ist innerhalb der Zwischenschicht, auf der innenraumseitigen Oberfläche der Außenscheibe oder auf der außenseitigen Oberfläche der Außenscheibe angeordnet.
• - Die elektrolumineszente Vorrichtung ist innerhalb der Zwischenschicht angeordnet. Der Bandsperrfilter ist innerhalb der Zwischenschicht zwischen elektrolumineszenter Vorrichtung und Außenscheibe, auf der innenraumseitigen Oberfläche der Außenscheibe oder auf der außenseitigen Oberfläche der Außenscheibe angeordnet.
• - Die elektrolumineszente Vorrichtung ist auf der innenraumseitigen Oberfläche der Außenscheibe angeordnet. Der Bandsperrfilter ist auf der außenseitigen Oberfläche der Außenscheibe angeordnet.

In the case of an arrangement of the band-stop filter on the outside of the electroluminescent device, the following configurations in particular are possible:

• - The electroluminescent device is arranged on the interior-side surface of the inner pane. The band elimination filter is disposed on the outside surface of the inner pane, inside the intermediate layer, on the inside surface of the outer pane, or on the outside surface of the outer pane.
• - The electroluminescent device is arranged on the outside surface of the inner pane. The band elimination filter is arranged inside the intermediate layer, on the inside surface of the outer pane or on the outside surface of the outer pane.
• - The electroluminescent device is arranged inside the intermediate layer. The band elimination filter is arranged within the interface between the electroluminescent device and the outer pane, on the inside surface of the outer pane or on the outside surface of the outer pane.
• - The electroluminescent device is arranged on the interior side surface of the outer pane. The band elimination filter is arranged on the outside surface of the outer pane.

• - Die elektrolumineszente Vorrichtung ist auf der außenseitigen Oberfläche der Innenscheibe angeordnet. Der Bandsperrfilter ist auf der innenraumseitigen Oberfläche der Innenscheibe angeordnet.
• - Die elektrolumineszente Vorrichtung ist innerhalb der Zwischenschicht angeordnet. Der Bandsperrfilter ist innerhalb der Zwischenschicht zwischen elektrolumineszenter Vorrichtung und Innenscheibe, auf der außenseitigen Oberfläche der Innenscheibe oder auf der innenraumseitigen Oberfläche der Innenscheibe angeordnet.
• - Die elektrolumineszente Vorrichtung ist auf der innenraumseitigen Oberfläche der Außenscheibe angeordnet. Der Bandsperrfilter ist innerhalb der Zwischenschicht, auf der außenseitigen Oberfläche der Innenscheibe oder auf der innenraumseitigen Oberfläche der Innenscheibe angeordnet.
• - Die elektrolumineszente Vorrichtung ist auf der außenseitigen Oberfläche der Außenscheibe angeordnet. Der Bandsperrfilter ist auf der innenraumseitigen Oberfläche der Außenscheibe, innerhalb der Zwischenschicht, auf der außenseitigen Oberfläche der Innenscheibe oder auf der innenraumseitigen Oberfläche der Innenscheibe angeordnet. Diese Konfiguration ist allerdings weniger bevorzugt, weil die elektrolumineszente Vorrichtung Beeinträchtigungen aus der äußeren Umgebung weitestgehend ungeschützt ausgesetzt ist und insbesondere leicht beschädigt werden kann.

In the case of an arrangement of the bandstop filter on the interior side of the electroluminescent device, the following configurations in particular are possible:

• - The electroluminescent device is arranged on the outside surface of the inner pane. The band elimination filter is arranged on the interior side surface of the inner pane.
• - The electroluminescent device is arranged inside the intermediate layer. The band elimination filter is arranged within the interface between the electroluminescent device and the inner pane, on the outside surface of the inner pane or on the inside surface of the inner pane.
• - The electroluminescent device is arranged on the interior side surface of the outer pane. The band elimination filter is arranged inside the intermediate layer, on the outside surface of the inner pane, or on the inside surface of the inner pane.
• - The electroluminescent device is arranged on the outside surface of the outer pane. The band elimination filter is arranged on the inside surface of the outer pane, inside the intermediate layer, on the outside surface of the inner pane, or on the inside surface of the inner pane. However, this configuration is less preferred because the electroluminescent device is largely exposed to intrusions from the external environment and, in particular, is easily damaged.

When the bandstop filter is located within the intermediate layer, the thin film coating is usually deposited on a carrier film sandwiched between two layers of thermoplastic bonding material. The carrier layer is, for example, a film based on polyethylene terephthalate (PET) with a thickness of 10 μm to 100 μm.

If the electroluminescent device is arranged within the intermediate layer, it can also be arranged on a carrier film which is arranged between two layers of thermoplastic bonding material. For example, a plurality of light-emitting diodes can be arranged with their electrodes on the carrier film. An electroluminescent device designed as an electroluminescent film can also be arranged between two layers of thermoplastic connecting material. However, light-emitting diodes can also be melted directly into the thermoplastic connecting material, for example via the interface between two layers of thermoplastic connecting material.

If the electroluminescent device is arranged on a surface of one of the panes, it can be attached to the planar surface and fixed there, for example with an adhesive, or pressed onto it by the thermoplastic intermediate layer (if it is a surface facing the intermediate layer). If the electroluminescent device is in the form of individual light-emitting diodes, these can also be fitted in recesses in the surface, which are designed, for example, as bores in the pane.

Such vehicle panes are also known in which an electroluminescent device, for example an LED or an optical fiber, is arranged on the side edge of the inner pane or the outer pane. The radiation is coupled into the corresponding pane via the side edge and propagates within the pane as a result of total reflection at the surfaces. The pane is then provided with a light-scattering structure, for example a screen print or a roughened area, at which the radiation is coupled out of the pane. The light-scattering structure then forms the perceptible luminous area. The invention can also be applied to such vehicle windows, in which case the positioning of the band-stop filter is then accordingly not based on the position of the actual electroluminescent device, but rather on the position of the light-scattering structure. The band-stop filter and the light-scattering structure are superimposed when viewed through the vehicle window, by which is meant that the orthogonal projection of the light-scattering structure onto the plane of the band-stop filter is located entirely within the band-stop filter. Depending on the intended emission direction, the optical bandstop filter can be arranged on the outside or on the inside of the light-scattering structure.

• - Die elektrolumineszente Vorrichtung ist dafür vorgesehen, nach außen zu strahlen, um eine Durchsicht durch die Fahrzeugscheibe zu verhindern („Privacy“-Scheibe). Die elektrolumineszente Vorrichtung ist insbesondere eine Elektrolumineszenzfolie und der Bandsperrfilter ist innenraumseitig zur elektrolumineszenten Vorrichtung angeordnet. Bevorzugt ist die Elektrolumineszenzfolie in die Zwischenschicht eingelagert. Die Fahrzeugscheibe ist bevorzugt eine Fahrzeugdachscheibe.
• - Die elektrolumineszente Vorrichtung ist dafür vorgesehen, nach innen zu strahlen, um ein Anzeigeelement zu bilden. Die elektrolumineszente Vorrichtung ist insbesondere eine Elektrolumineszenzfolie oder eine Mehrzahl von Leuchtdioden. Der Bandsperrfilter ist außenseitig zur elektrolumineszenten Vorrichtung angeordnet. Bevorzugt ist die elektrolumineszente Vorrichtung zwischen Außenscheibe und Innenscheibe angeordnet, als in die Zwischenschicht eingelagert oder auf einer der einander zugewandten Oberfläche der Scheiben angeordnet. Die Fahrzeugscheibe ist bevorzugt eine Windschutzscheibe.
• - Die elektrolumineszente Vorrichtung ist dafür vorgesehen, als Lichtquelle nach innen zu strahlen, um den Fahrzeuginnenraum zu beleuchten. Die elektrolumineszente Vorrichtung ist insbesondere eine Mehrzahl von Leuchtdioden. Der Bandsperrfilter ist außenseitig zur elektrolumineszenten Vorrichtung angeordnet. Die Fahrzeugscheibe ist bevorzugt eine Fahrzeugdachscheibe.

The invention is suitable for a variety of technical applications, including the following:

• - The electroluminescent device is intended to radiate outwards to prevent viewing through the vehicle window ("privacy" window). The electroluminescent device is in particular an electroluminescent film and the bandstop filter is arranged on the interior side of the electroluminescent device. The electroluminescent film is preferably embedded in the intermediate layer. The vehicle window is preferably a vehicle roof window.
• - The electroluminescent device is intended to radiate inwards to form a display element. The electroluminescent device is in particular an electroluminescent film or a plurality of light-emitting diodes. The band elimination filter is arranged outside the electroluminescent device. The electroluminescent device is preferably arranged between the outer pane and the inner pane, embedded in the intermediate layer or arranged on one of the surfaces of the panes facing one another. The vehicle window is preferably a windshield.
• - The electroluminescent device is intended to radiate inward as a light source to illuminate the vehicle interior. The electroluminescent device is in particular a plurality of light-emitting diodes. The band elimination filter is arranged outside the electroluminescent device. The vehicle window is preferably a vehicle roof window.

The optical bandstop filter is designed as a series of thin layers, with optically high-refractive and optically low-refractive layers being arranged alternately one above the other. The optical band stop filter is an interference filter, radiation passing through the filter being either (mainly) reflected or (mainly) transmitted depending on its wavelength as a result of interference effects. The interference is based on reflections of the radiation at the interfaces of the individual layers, which leads to multiple overlapping of the radiation. Depending on the optical path length between the interfaces, at a given wavelength, the interference is either constructive or destructive, on which the filter effect is based.

The optical band-stop filter can be provided with the properties desired for the application through the structure of the thin-film stack. The refractive index of the materials of the individual layers in particular play a role here, as does the thickness of the individual layers and the total number of individual layers. The refractive index and the geometric thickness of the individual layers (the product of which gives the so-called optical path length or optical thickness) particularly influence the central wavelength of the bandstop filter, i.e. the spectral position of the stopband. In principle, the optical filter properties can be designed more precisely, the more individual layers the thin-layer stack comprises. Bandstop filters with low minimum transmission, high block depth and low gradient can be produced with layer systems from a large number of individual layers. Bandwidth is also affected by the number of layers, with a higher number of layers resulting in lower bandwidth.

The thin film stack of the band elimination filter typically contains optically high refractive index dielectric layers. These can be based, for example, on silicon nitride (Si ₃ N ₄ ), a silicon-metal mixed nitride (such as silicon zirconium nitride, silicon-aluminum mixed nitride, silicon-hafnium mixed nitride or silicon-titanium mixed nitride), aluminum nitride, titanium oxide, tin oxide, tin -Zinc oxide, zirconium oxide, niobium oxide, hafnium oxide, tantalum oxide, tungsten oxide, manganese oxide, bismuth oxide or silicon carbide. Silicon nitride, silicon-metal mixed nitride (in particular silicon zirconium nitride) and titanium oxide are preferred because of their good optical properties, their durability and their good separability, in particular by gas phase deposition.

The thin film stack of the band elimination filter typically contains dielectric low optical index layers and/or electrically conductive low optical index layers. Dielectric, optically low-index layers can be formed, for example, on the basis of silicon oxide (SiO ₂ ), aluminum oxide, magnesium fluorite, silicon oxynitride or calcium fluorite. Silicon oxide is preferred because of its good optical properties, its durability and good separability.

The materials mentioned can be deposited stoichiometrically, under-stoichiometrically or over-stoichiometrically. The materials can have dopings, in particular aluminum, boron, zirconium or titanium. The materials can be provided with a certain electrical conductivity through the doping. The person skilled in the art will nevertheless identify them as dielectric layers with regard to their function, as is usual in the area of thin layers. The material of the dielectric layers preferably has an electrical conductivity (reciprocal of the specific resistance) of less than 10 ^-4 S/m. The material of the electrically conductive layers preferably has an electrical conductivity greater than 10 ⁴ S/m.

The refractive index of the optically high-index layers is preferably at least 2.0, the refractive index of the optically low-index layers is preferably at most 1.6, particularly preferably at most 1.5.

In a preferred embodiment of the invention, all optically high-refractive and low-refractive layers of the bandstop filter are designed as dielectric layers. The thin-film coating then forms a so-called dielectric superlattice. Physically, the dielectric superlattice can also be understood as a Bragg mirror.

The materials mentioned above are particularly suitable for the optically high-index dielectric layers. For reasons of cost and separability, preference is given to silicon nitride, silicon-metal mixed nitride (in particular silicon zirconium nitride) and titanium oxide, with silicon nitride being particularly preferred.

The optical thicknesses of the individual layers depend in particular on the desired spectral position of the stop band, which in turn depends on the emission wavelength of the electroluminescent device at incidence. The optical thickness of the optically high-index layers is preferably from 10 nm to 30 nm. These optical thicknesses can be achieved, for example, with high-index layers based on silicon nitride (refractive index 2.04) with geometric thicknesses of about 5 nm to 15 nm.

The materials mentioned above are particularly suitable for the optically low-index dielectric layers. Silicon oxide is preferred. The optical thickness of the optically low-index layers is preferably from 150 nm to 400 nm. These optical thicknesses can be achieved, for example, with low-index layers based on silicon oxide (refractive index 1.47) with geometric thicknesses of about 100 nm to 270 nm.

The superlattice comprises n optically high-index layers and n optically low-index layers, where n is a natural number greater than or equal to 1. The superlattice is preferably built up from (n+1) optically high-index layers and n optically low-index layers, so that the uppermost and the lowermost layer is an optically high-index layer. Here too, however, a structure consisting of n optically high-index layers and n optically low-index layers or n optically high-index layers and (n+1) optically low-index layers is possible in principle. n is preferably at least 5, particularly preferably at least 10, very particularly preferably at least 15. Advantageous and useful optical properties can be achieved in this way. n is preferably from 5 to 50, particularly preferably from 10 to 30 and in particular from 15 to 25. These ranges represent good compromises with regard to the optical properties of the bandstop filter on the one hand and the simplest possible layer structure on the other. No further layers are preferably present.

In a further preferred embodiment of the invention, at least some of the optically low-index layers of the bandstop filter are designed as electrically conductive layers. The optically high-index layers and, if present, the other optically low-index layers are designed as dielectric layers. The thin-layer coating then forms a so-called Fabry-Perot interferometer. Here, too, interference effects occur after the radiation passing through has been reflected at the boundary surfaces, in particular the highly reflective, electrically conductive layers, on which the filter effect is based. A band stop filter of the Fabry-Perot interferometer type has the advantage over the band stop filter of the dielectric superlattice type that comparable optical properties can be achieved with a smaller number of individual layers. It is also possible to create a further blocking range in addition to the main blocking range in the visible spectrum, for example in the infrared (IR) range, so that the band elimination filter also functions as a sun protection coating (IR-reflecting coating). A disadvantage of the Fabry-Perot interferometer compared to the dielectric superlattice is the fact that many electrically conductive layers are susceptible to corrosion, for example silver layers. In this case, the use of the Fabry-Perot interferometer on an external surface of the inner pane or the outer pane facing away from the intermediate layer should be avoided. In addition, the Fabry-Perot interferometer reduces the total light transmission more than the superlattice due to the absorption by the conductive layers.

The electrically conductive layers can be metal-containing layers, for example based on silver (Ag), gold, copper, aluminum, or layers based on a transparent conductive oxide (TCO, transparent conductive oxide), for example indium tin oxide (ITO, indium tin oxide). The electrically conductive layers are preferably formed on the basis of silver. The conductive layers preferably contain at least 90% by weight silver, particularly preferably at least 99% by weight silver, very particularly preferably at least 99.9% by weight silver. Particularly good results are achieved in this way. The silver layers preferably have a geometric thickness of 2 nm to 10 nm. In this range, they have sufficient reflective properties to ensure the interference effects, so that they do not have to be made thicker.

In principle, all low-index layers can be designed as electrically conductive layers, with an optically high-index dielectric between adjacent conductive layers cal layer is arranged. However, only some of the low-index layers are preferably designed as electrically conductive layers, while the remaining low-index layers are designed as dielectric layers. A regular structure is particularly preferred, so that the same number of dielectric layers is arranged between all adjacent conductive layers. For example, every second low-index layer can be designed as a conductive layer, so that one dielectric low-index layer and two high-index dielectric layers are arranged between adjacent conductive layers.

The materials mentioned above are particularly suitable for the dielectric layers. Silicon nitride, silicon-metal mixed nitride (in particular silicon zirconium nitride) and titanium oxide for the high-index layers and silicon oxide for the low-index layers are particularly preferred because of the separability. A particularly good anti-reflection coating of the conductive layers is achieved with titanium oxide.

The Fabry-Perot interferometer comprises n optically high-index layers and n optically low-index layers, where n is a natural number greater than or equal to 1. The Fabry-Poerot interferometer is preferably constructed from (n+1) optically high-refractive layers and n optically low-refractive layers, so that the uppermost and the lowermost layer is an optically high-refractive layer. n is preferably at least 3, particularly preferably at least 5, very particularly preferably at least 7. Advantageous and useful optical properties can be achieved in this way. n is preferably from 3 to 20, very particularly preferably from 5 to 15 and in particular from 7 to 12. These ranges represent good compromises with regard to the optical properties of the bandstop filter on the one hand and the simplest possible layer structure with high light transmission on the other. No further layers are preferably present.

In other words, the Fabry-Perot interferometer comprises a plurality of electrically conductive layers, in particular based on silver, a dielectric layer or dielectric layer sequence being arranged between adjacent conductive layers and above the topmost conductive layers and below the bottommost conductive layer. In this case, dielectric layer sequences are made up of m optically low-index layers and (m+1) optically high-index layers which are arranged alternately, so that an optically low-index layer is arranged between two adjacent high-index layers. The number m is a natural number greater than or equal to 1. Individual dielectric layers between adjacent conductive layers, above the uppermost conductive layers or below the lowermost conductive layer are preferably optically high-index layers. The number m can be selected independently for each dielectric layer sequence, but is preferably the same for all layer sequences. m is particularly preferably equal to 1. A dielectric layer sequence is preferably arranged in each case between all adjacent conductive layers. The number of conductive layers is preferably at least 3, particularly preferably from 3 to 7.

In the design of the band stop filter in the manner of a Fabry-Perot interferometer, too, the optical thicknesses of the individual dielectric layers depend in particular on the desired spectral position of the blocking range, which in turn depends on the emission wavelength of the electroluminescent device at incidence. The optical thickness of the optically high-index layers is preferably from 30 nm to 300 nm. These optical thicknesses can, for example, be based on high-index layers based on titanium oxide (refractive index 2.8) with geometric thicknesses of about 10 nm to 100 nm or with high-index layers of silicon nitride (refractive index 2.04) with geometric thicknesses of about 15 nm to 150 nm. The optical thickness of the dielectric optically low-index layers is preferably from 150 nm to 400 nm. These optical thicknesses can be achieved, for example, with low-index layers based on silicon oxide (refractive index 1.47) with geometric thicknesses of about 100 nm to 270 nm.

If a first layer is arranged above a second layer, this means within the meaning of the invention that the first layer is arranged further away from the substrate on which the coating is applied than the second layer. If a layer is formed on the basis of a material, the majority of the layer consists of this material in addition to any impurities or dopings.

In a particularly preferred embodiment, the electroluminescent device is designed as an electroluminescent film that is arranged between the outer pane and the inner pane. The arrangement between the outer pane and the inner pane includes the case where the electroluminescent device is directly on one of the facing surfaces of the outer pane or inner pane is arranged. The electroluminescent film is preferably embedded in the thermoplastic intermediate layer and is arranged there between two layers of thermoplastic connecting material, as a result of which a stable connection of the electroluminescent film to the two panes is ensured. The optical band stop filter is arranged on the inside of the electroluminescent film, in particular on the outside surface of the inner pane, on the inside surface of the inner pane or within the intermediate layer between the electroluminescent film and the inner pane. The envisaged emission direction of the electroluminescent device is directed towards the outside environment, while the emission beyond the inner pane into the vehicle interior is prevented by the band stop filter. Such vehicle windows are used as so-called “privacy” windows, with the view from the outside into the vehicle interior being prevented or at least made more difficult by the radiation of the electroluminescent film, which represents a planar light source. In this embodiment, the vehicle window is particularly preferably a vehicle roof window.

In a further particularly preferred embodiment, the electroluminescent device is designed as an electroluminescent film which is arranged between the outer pane and the inner pane. The electroluminescent film is preferably arranged on the outside surface of the inner pane or embedded in the thermoplastic intermediate layer. The optical band stop filter is arranged on the outside of the electroluminescent film, in particular on the outside surface of the outer pane, on the interior surface of the outer pane or within the intermediate layer between the electroluminescent device and the outer pane. The envisaged direction of emission of the electroluminescent device is directed into the interior of the vehicle, while the emission beyond the outer pane into the outside environment is prevented by the band stop filter. The electroluminescent device can be used in such a vehicle window as a display element (display) in order to display information, in particular for the driver (for example in the manner of a head-up display). In this configuration, the vehicle window is particularly preferably a windshield. Instead of the electroluminescent film, such a display element can also be formed from a plurality of light-emitting diodes, in particular light-emitting diodes of the same color. However, the electroluminescent device can also serve as a planar light source for illuminating the vehicle interior—the vehicle window is then particularly preferably a vehicle roof window.

In a further particularly preferred configuration, the electroluminescent device comprises a plurality of light-emitting diodes, which are arranged on the (flat) interior-side surface of the inner pane or in recesses in the interior-side surface of the inner pane. The main emission direction of the light-emitting diodes opposite the electrical contacts faces the vehicle interior. The surface of the inner pane on the interior side is preferably provided with an electrically conductive coating, which is structured in particular by insulating lines and ensures the electrical contacting of the light-emitting diodes. Light-emitting diodes are securely fixed on or in the pane surface, for example by using an adhesive or soldering to the conductive coating. The optical bandstop filter is arranged on the outside of the light-emitting diodes, in particular on the outside surface of the outer pane, on the interior surface of the outer pane, within the intermediate layer or on the outside surface of the inner pane. The envisaged direction of emission of the electroluminescent device is directed into the interior of the vehicle, while the emission beyond the outer pane into the outside environment is prevented by the band stop filter. In such a vehicle window, the electroluminescent device can serve as lighting for the vehicle interior. In this embodiment, the vehicle window is particularly preferably a vehicle roof window.

In a further particularly preferred embodiment, the electroluminescent device comprises a plurality of light-emitting diodes, which are arranged on the (flat) interior-side surface of the outer pane or in recesses in the interior-side surface of the outer pane. The main emission direction of the light-emitting diodes opposite the electrical contacts faces the vehicle interior. The surface of the outer pane on the interior side is preferably provided with an electrically conductive coating, which is structured in particular by insulating lines and ensures the electrical contacting of the light-emitting diodes. Light-emitting diodes are securely fixed on or in the pane surface, for example by using an adhesive or soldering to the conductive coating. The optical bandstop filter is arranged on the outside of the light-emitting diodes, in particular on the outside surface of the outer pane. The envisaged direction of emission of the electroluminescent device is directed into the interior of the vehicle, while the emission beyond the outer pane into the outside environment is prevented by the bandstop filter. The electroluminescent device can be Such a vehicle pane serve as lighting for the vehicle interior. In this embodiment, the vehicle window is particularly preferably a vehicle roof window.

• - auf oder in Ausnehmungen der außenseitigen Oberfläche der Innenscheibe, wobei der Bandfilter in der Zwischenschicht oder auf einer der Oberfläche der Außenscheibe angeordnet ist;
• - innerhalb der Zwischenschicht, beispielsweise auf einer Trägerfolie, wobei der Bandfilter in der Zwischenschicht zwischen der elektrolumineszenten Vorrichtung und der Außenscheibe angeordnet ist; oder
• - auf oder in Ausnehmungen der innenraumseitigen Oberfläche der Außenscheibe, wobei der Bandfilter auf der außenseitigen Oberfläche der Außenscheibe angeordnet ist.

In a further particularly preferred configuration, the electroluminescent device comprises a plurality of light-emitting diodes which are arranged between the outer pane and the inner pane. The main emission direction of the light-emitting diodes opposite the electrical contacts faces the vehicle interior. The optical bandstop filter is arranged on the outside of the light-emitting diodes. The envisaged direction of emission of the electroluminescent device is directed into the interior of the vehicle, while the emission beyond the outer pane into the outside environment is prevented by the band stop filter. The electroluminescent device can also be used in such a vehicle window as lighting for the vehicle interior. In this embodiment, the vehicle window is particularly preferably a vehicle roof window. Specifically, the electroluminescent device may be arranged:

• - On or in recesses of the outside surface of the inner pane, the band filter being arranged in the intermediate layer or on one of the surfaces of the outer pane;
• - within the intermediate layer, for example on a carrier film, the band filter being arranged in the intermediate layer between the electroluminescent device and the outer pane; or
• - On or in recesses of the interior-side surface of the outer pane, the band filter being arranged on the outside surface of the outer pane.

The electrical contacting of the light-emitting diodes is again made, for example, by a structured, electrically conductive coating on the respective surface of the pane or carrier film.

What the above three particularly preferred configurations have in common is that the electroluminescent device is designed as a plurality of light-emitting diodes and is used to illuminate the vehicle interior. The light-emitting diodes are arranged on or in recesses in the interior surface of the outer pane, on or in recesses in the interior surface of the inner pane, on the outside surface of the inner pane or within the intermediate layer. The optical band elimination filter is arranged outside the electroluminescent device. The vehicle window is preferably a vehicle roof window. In these configurations, the light-emitting diodes can also be replaced by light-scattering structures on a pane surface, within a pane or within the intermediate layer, which is illuminated by a light source arranged on the side edge of the pane or the intermediate layer. The light-scattering structures can be produced, for example, by screen printing on a pane surface or carrier film, by producing a roughened area of a pane surface by means of mechanical processing or laser processing, or within a pane by laser processing.

The outer pane and the inner pane are preferably made of glass, in particular of soda-lime glass, which is common for window panes. In principle, however, the panes can also be made of other types of glass (for example borosilicate glass, quartz glass, aluminosilicate glass) or transparent plastics (for example polymethyl methacrylate or polycarbonate). The thickness of the outer pane and the inner pane can vary widely. Discs with a thickness in the range from 0.8 mm to 5 mm, preferably from 1.4 mm to 2.5 mm, are preferably used, for example those with the standard thicknesses of 1.6 mm or 2.1 mm.

The thermoplastic intermediate layer comprises at least one layer of a thermoplastic connecting material, which preferably contains ethylene vinyl acetate (EVA), polyvinyl butyral (PVB) or polyurethane (PU) or mixtures or copolymers or derivatives thereof, particularly preferably PVB. The intermediate layer is typically formed from at least one thermoplastic film. The thickness of the film is preferably from 0.3 mm to 2 mm, the standard thicknesses of 0.36 mm and 0.76 mm being particularly common.

The outer pane, the inner pane and the thermoplastic intermediate layer can be clear and colorless, but also tinted or colored. The outer pane and the inner panes can be unprestressed, partially prestressed or prestressed independently of one another. If at least one of the panes is to have a prestress, this can be a thermal or chemical prestress.

The vehicle window is preferably curved in one or more spatial directions, as is usual for motor vehicle windows, with typical radii of curvature being in the range from about 10 cm to about 40 m. However, the vehicle window can also be flat, for example if it is intended as a window for buses, trains or tractors.

The vehicle window can be manufactured by methods known per se. The outer pane and the inner pane are laminated to one another via the intermediate layer, for example by autoclave methods, vacuum bag methods, vacuum ring methods, calendering methods, vacuum laminators or combinations thereof. The outer pane and inner pane are usually connected under the action of heat, vacuum and/or pressure. If the vehicle pane is bent, the individual panes are subjected to a bending process before lamination, for example by gravity bending, press bending and/or suction bending. The outer pane and the inner pane are preferably bent congruently together (i.e. at the same time and using the same tool) while lying on top of each other, because this means that the shape of the panes is optimally matched to one another for the lamination that takes place later. Typical temperatures for glass bending processes are 500°C to 700°C, for example. This thermal treatment also increases the transparency and reduces the sheet resistance of the reflective coating.

The thin layers of the band-stop filter are preferably applied to a disc surface by physical vapor deposition (PVD), particularly preferably by cathode sputtering ("sputtering"), very particularly preferably by magnetic field-assisted cathode sputtering ("magnetron sputtering"). However, other thin-film methods can also be used, for example chemical vapor deposition (CVD), atomic layer deposition (ALD), vapor deposition or holographic methods. In particular, dielectric superlattices can also be purchased on carrier foils. The coating is preferably applied to one of the panes before lamination and before any bending processes. Instead of applying the reflective coating to a pane surface, it can in principle also be provided on a carrier film that is arranged in the intermediate layer. In principle, however, a band-stop filter can also be applied to an external surface (outside surface of the outer pane, interior-side surface of the inner pane) after the lamination.

The electroluminescent device is placed on one of the disc surfaces or embedded in the interlayer. If light-emitting diodes are to be introduced into recesses in a pane surface, they are produced by drilling, for example by means of laser processing or mechanically. Mounting an electroluminescent device on an external surface is preferably done after lamination, on an internal surface or within the interlayer necessarily before lamination.

The vehicle window of the present invention can be used as a window of a vehicle. The invention also includes a vehicle equipped with a vehicle window according to the invention. The vehicle can be any land vehicle, watercraft or aircraft, is preferably a passenger car, truck or rail vehicle.

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.

• 1 einen Querschnitt durch eine erste Ausgestaltung einer erfindungsgemäße Fahrzeugscheibe,
• 2 einen Querschnitt durch eine zweite Ausgestaltung einer erfindungsgemäße Fahrzeugscheibe,
• 3 einen Querschnitt durch eine dritte Ausgestaltung einer erfindungsgemäße Fahrzeugscheibe,
• 4 einen Querschnitt durch eine vierte Ausgestaltung einer erfindungsgemäße Fahrzeugscheibe,
• 5 einen Querschnitt durch eine Innenscheibe mit einem dielektrischen Übergitter als Bandsperrfilter (nicht als solche beansprucht),
• 6 einen Querschnitt durch eine Innenscheibe mit einem Fabry-Peröt-Interferometer als Bandsperrfilter (nicht als solche beansprucht),
• 7 ein schematisches Transmissionsspektrum eines Bandsperrfilters,
• 8 Transmissionsspektren der erfindungsgemäßen Beispiele 1-3,
• 9 Transmissionsspektren der erfindungsgemäßen Beispiele 1, 4 und 5 und
• 10 Transmissionsspektrum des erfindungsgemäßen Beispiels 6.

Show it:

• 1 a cross section through a first embodiment of a vehicle window according to the invention,
• 2 a cross section through a second embodiment of a vehicle window according to the invention,
• 3 a cross section through a third embodiment of a vehicle window according to the invention,
• 4 a cross section through a fourth embodiment of a vehicle window according to the invention,
• 5 a cross section through an inner pane with a dielectric superlattice as a band stop filter (not claimed as such),
• 6 a cross-section through an inner pane with a Fabry-Perot interferometer as a band stop filter (not claimed as such),
• 7 a schematic transmission spectrum of a band stop filter,
• 8th Transmission spectra of Examples 1-3 according to the invention,
• 9 Transmission spectra of Examples 1, 4 and 5 according to the invention and
• 10 Transmission spectrum of example 6 according to the invention.

1 shows an embodiment of a vehicle window according to the invention. The vehicle pane is a composite pane which is structurally composed of an outer pane 1 and an inner pane 2 which are connected to one another via a thermoplastic intermediate layer 3 . In the installed position, the outer pane 1 faces the outside environment, and the inner pane 2 faces the vehicle interior. The outer pane 1 has an outside surface I, which faces the outside environment in the installed position, and an interior surface II, which faces the interior in the installed position. Likewise, the inner pane 2 has an outside surface III, which faces the outside environment in the installed position, and an interior-side surface IV, which faces the interior in the installed position. The interior surface II of the outer pane 1 and the outside surface III of the inner pane 2 face one another and are connected to one another via the thermoplastic intermediate layer 3 .

The vehicle window is intended as a roof window of a passenger car. It is designed as a so-called privacy roof pane, in which a view from the outside can be prevented by a flat light source radiating outwards. This light source is an electroluminescent film 20 embedded in the intermediate layer 3 . For this purpose, the electroluminescent film 20 is arranged between a first layer of thermoplastic connecting material 3a and a second layer of thermoplastic connecting material 3b. The electroluminescent film 20 is connected to the outer pane 1 via the first layer of thermoplastic connecting material 3a and to the inner pane 2 via the second layer of thermoplastic connecting material 3b.

The outer pane 1 and the inner pane 2 consist, for example, of soda-lime glass. The outer pane 1 has a thickness of 2.1 mm, for example, and the inner pane 2 has a thickness of 2.1 mm or 1.6 mm. Both layers of thermoplastic connecting material 3a, 3b are designed as foils based on PVB with a thickness of 0.76 mm.

The electroluminescent film 20 contains an active layer of material capable of electroluminescence in the manner of an LED or OLED, which is arranged between two carrier films. The carrier foils are, for example, PET foils with a thickness of 50 μm. An electrically conductive coating is arranged as an electrode between each carrier film and the active layer, makes electrical contact and can be connected to the on-board electronics. By applying an electrical voltage to the electrodes, the active layer can be excited to luminescence, which activates the light source. The electroluminescent film 20 emits radiation from the visible spectral range (380 nm to 780 nm). Depending on the configuration of the active layer, radiation can be realized in different colors. In particular, electroluminescent films 20 with the standard colors red (630 nm), green (550 nm) or blue (473 nm) are customary. White or approximately white electroluminescence radiation can also be realized by superimposing different colors or by a very broadband luminescence emission.

In addition to the desired emission direction via the outer pane 1 to the outside of the vehicle, the electroluminescent film 20 also emits radiation in the direction of the inner pane 2 . This would get into the vehicle interior and be perceived as annoying there. In order to prevent radiation beyond the inner pane 2 into the vehicle interior, the outside surface III of the inner pane 2 is provided with a thin-layer coating which acts as an optical band stop filter. Due to the suitable design of the layer structure of the coating, the bandstop filter is matched to the emission spectrum of the electroluminescent film 20, so that it largely blocks the radiation. Thus, the radiation of the electroluminescent film 20 cannot reach the vehicle interior or only with a significantly reduced intensity.

The band stop filter is an interference filter made up of thin layers. In particular, it can be embodied as a so-called dielectric superlattice 40 or as a so-called Fabry-Perot interferometer 50 .

A dielectric superlattice 40 is constructed purely from individual dielectric layers, with optically high-index layers 41 having a refractive index greater than 1.8 and optically low-index layers 42 having a refractive index less than 1.8 being arranged alternately one above the other. Table 1 shows an exemplary structure of the vehicle window 1 with a dielectric superlattice 40 as bandstop filter specifying the materials and layer thicknesses according to three examples 1-3 according to the invention. The superlattice 40 comprises 21 high-index layers of aluminum-doped silicon nitride (Si ₃ N ₄ ) and 20 layers of aluminum-doped silicon oxide (SiO ₂ ). By choosing the layer thicknesses of the dielectric layers 41, 42, the optical properties of the bandstop filter can be set and adapted to the requirements of the specific application.

Table 2 shows an exemplary structure of the vehicle window 1 with a dielectric superlattice 40 as a bandstop filter, specifying the materials and layer thicknesses according to two further examples 4-5 according to the invention.

A Fabri-Peröt interferometer 50 is also constructed from alternating optically high-refractive and optically low-refractive thin layers, with at least some of the optically low-refractive layers being formed as electrically conductive layers 53, while the optically high-refractive layers 51 and the remaining optically low-refractive layers 52 as dielectric layers are formed. Table 3 shows an exemplary structure of the vehicle window 1 with a Fabri-Peröt interferometer 50 as a band stop filter, specifying the materials and layer thicknesses according to a further example 6 according to the invention. The electrically conductive layers 53 are based on silver (Ag) and act in particular as partially transparent mirrors. The high-index dielectric layers 51 are made of aluminum-doped silicon nitride (Si ₃ N ₄ ) and the low-index dielectric layers 52 are made of aluminum-doped silicon oxide (SiO ₂ ). By choosing the layer thickness The optical path length between the conductive layers 53 is adjusted by the dielectric layers 51, 52, as a result of which the optical properties of the bandstop filter can be adapted to the requirements of the specific application. Table 3 layer thickness material Reference sign Example 6 Soda Lime Glass 1 2.1mm PVB 3a 0.76mm (electroluminescent film) 20 PVB 3b 0.76mm TiO ₂ 50 51 30.0nm Ag 53 3.0mm TiO ₂ 51 20.0mm SiO 52 170.5mm TiO ₂ 51 30.0nm Ag 53 3.0mm TiO ₂ 51 20.0mm SiO 52 170.5mm TiO ₂ 51 30.0nm Ag 53 3.0mm TiO ₂ 51 20.0mm SiO 52 170.5mm TiO ₂ 51 30.0nm Ag 53 3.0mm TiO ₂ 51 20.0mm SiO ₂ 52 170.5mm TiO ₂ 51 30.0nm Ag 53 3.0mm TiO ₂ 51 20.0mm SiO ₂ 52 170.5mm TiO ₂ 51 30.0nm Ag 53 3.0mm TiO ₂ 51 20.0mm SiO ₂ 52 170.5mm TiO ₂ 52 19.7mm Soda Lime Glass 2 2.1mm

Alternatively, the band stop filter 40, 50 could also be applied to the surface IV of the inner pane 2 on the interior side. There, however, it would be exposed to external influences to a greater extent, so that this arrangement is less preferred. Alternatively, the band stop filter 40 , 50 could also be embedded on a carrier film in the intermediate layer 3 between the device 20 and the inner pane 2 . However, that would make the structure of the intermediate layer 3 more complex, so that this arrangement is less preferred.

In the figure, the band stop filter 40, 50 is applied to the surface III of the inner pane 2 over the entire surface. Alternatively, however, the surface III can also have an uncoated peripheral edge area in order to prevent contact of the band elimination filter 40, 50 with the surrounding atmosphere. This is particularly advantageous when the bandstop filter is designed as a Fabry-Perot interferometer 50 because of the silver layers that are susceptible to corrosion. Since vehicle windows are usually provided with an opaque masking print in the edge area, the band stop filter 40, 50 for suppressing the luminescence is not necessary there either.

2 shows a further embodiment of a vehicle pane according to the invention with an outer pane 1, an inner pane 2 and a thermoplastic intermediate layer 3. The vehicle pane is intended as a windshield of a passenger car. The intermediate layer 3 is formed from a single PVB film with a thickness of 0.76 mm. In the lower area of the vehicle pane, an electroluminescent film 20 is arranged on the outside surface III of the inner pane 2 and fixed to this surface III, for example, via a thin layer of adhesive. The electroluminescent film 20 is intended to radiate beyond the inner pane 2 into the vehicle interior in order to serve as a display element for the driver. For example, static information can be displayed when the on-board electronics activate the electroluminescent film 20 in response to a sensor signal. For this purpose, a symbol can be displayed which is generated by the shape of the electroluminescent film 20 or by a masking area (for example an opaque cover print on one of the surfaces III, IV of the inner pane 2). Alternatively, it is also possible to structure the electrodes of the electroluminescent film 20 in such a way that the electroluminescent film 20 can be controlled “pixel by pixel” in order to display dynamic information.

In this case, the desired emission direction of the electroluminescent film 20 is directed into the vehicle interior, while emission beyond the outer pane 1 into the outside environment is to be prevented. For this purpose, the interior surface II of the outer pane 1 is provided with a bandstop filter, which in turn can be designed as a dielectric superlattice 40 or as a Fabry-Perot interferometer 50, as in connection with FIG 1 described.

Alternatively, the band stop filter 40, 50 could also be arranged on the outside surface I of the outer pane 1 or within the intermediate layer.

3 shows a further embodiment of a vehicle pane according to the invention with an outer pane 1, an inner pane 2 and a thermoplastic intermediate layer 3, which is formed from a single PVB film with a thickness of 0.76 mm.

The vehicle window is intended as a roof window of a passenger car and is intended to provide a lighting function for the vehicle interior. To this end, the vehicle window is equipped with a plurality of light-emitting diodes 30 . The interior surface II of the outer pane is provided with bores which form recesses for the light-emitting diodes 30 . The interior-side surface II is provided with an electrically conductive coating, which acts as an electrode layer 31 for the light-emitting diodes 30 . The electrode layer 31 is structured by insulation lines in order to ensure the electrical supply lines to the individual light-emitting diodes 30 . The light-emitting diodes 30 are then inserted into the recesses of the interior-side surface II and electrically conductively connected to the electrode layer.

In this case, the desired emission direction of the light-emitting diodes 30 is directed into the interior of the vehicle, while emission beyond the outer pane 1 into the external environment is to be prevented. For this purpose, the outside surface I of the outer pane 1 is provided with a bandstop filter, which in turn can be designed as a dielectric superlattice 40 or as a Fabry-Perot interferometer 50, as in connection with FIG 1 described.

4 shows a further embodiment of a vehicle pane according to the invention with an outer pane 1, an inner pane 2 and a thermoplastic intermediate layer 3. The vehicle pane is an alternative embodiment of the roof pane with a lighting function 3 . The light-emitting diodes 30 are inserted in recesses in the surface IV of the inner pane 2 on the interior side. The band stop filter 40, 50 is arranged on the outside surface III of the inner pane 2. FIG.

Bandstop filter 40, 50 could just as easily be applied to surface II of outer pane 1 on the interior side. An arrangement of the band stop filter 40, 50 on the outside surface I of the outer pane 1 or within the intermediate layer 3 is possible, although less preferred.

5 shows the schematic structure of a bandstop filter in the manner of a dielectric superlattice 40 on an inner pane 2. The superlattice 40 is configured as in Tables 1 and 2.

6 shows the schematic structure of a band stop filter in the manner of a Fabry-Perot interferometer 50 on an inner pane 2. The Fabry-Perot interferometer 50 is configured as in Table 3.

7 shows schematically the transmission spectrum of a band stop filter in the visible spectral range. The bandstop filter has a stopband with low transmission, while there is high transmission outside the stopband. The bandstop filter can therefore block radiation that is in the blocking range. The spectral lasing of the stop band is characterized by the central wavelength λ ₀ (center of the stop band) and the full width at half maximum Δλ (limited by the wavelengths at which 50% of the block depth ΔT) is reached. Since the bandstop filter is based on interference effects, the transmission spectrum adjacent to the stopband is not ideally smooth, but has an oscillating shape. The difference between the transmission value T _max , which occurs at the local transmission maxima adjacent to the stop band, and the smallest transmission value within the stop band (minimum transmission T _min ) is the block depth ΔT. The minimum transmission T _min is a measure of the quality of the band stop filter - the lower the minimum transmission T _min is, the less radiation is let through by the band stop filter. The slope indicates over which spectral range the transmission increases to the maximum transmission at the edges of the stop band.

The properties of the bandstop filter can be adjusted by designing the thin-layer system. The optical thickness of the individual layers has an influence in particular on the central wavelength λ ₀ and the half-width Δλ, while the block depth ΔT, the minimum transmission T _min and the slope can be influenced in particular by the number of layers.

8th shows the transmission spectrum (angle of incidence 0°) of vehicle windows according to Examples 1-3 according to the invention, the layer structure of which is shown in Table 1. A band stop filter is formed by each superlattice 40, with the band stop filters differing in their spectral position. The band elimination filter of Example 1 is tuned to blue radiation around 450 nm, that of Example 2 to green color around 550 nm and that of Example 3 to red color around 560 nm.

9 shows the transmission spectrum (angle of incidence 0°) of vehicle windows according to example 1 according to the invention and examples 5 and 6 according to the invention, the layer structure of which is shown in table 2. A bandstop filter is formed by each superlattice 40, the center wavelength λ ₀ of the examples being identical. However, they differ significantly in their bandwidth Δλ and their block depth ΔT.

The examples make it clear that the optical properties can be set very precisely by designing the thin-film coatings. It is therefore easily possible to design the bandstop filter individually according to the requirements of the application.

10 shows the transmission spectrum (angle of incidence 0°) of the vehicle windows according to example 6 according to the invention, the layer structure of which is shown in table 3. The Fabry-Perot interferometer 50 forms a band stop filter with a blocking range in the blue spectral range around 400 nm. An advantage of the Fabry-Perot interferometer 50 is that it can form further blocking ranges (or areas of reduced transmission), as in the present case seen in the red around 700 nm. As a result, the bandstop filter can be used simultaneously as an IR protective coating, for example.

Reference List

(1)

outer pane

(2)

inner pane

(3)

thermoplastic intermediate layer

(3a)

first layer of thermoplastic bonding material

(3b)

second layer of thermoplastic bonding material

(20)

electroluminescent device: electroluminescent sheet

(30)

electroluminescent device: light emitting diode

(31)

Electrode layer of the light-emitting diodes 30

(40)

Bandstop filter: dielectric superlattice

(41)

optically high-index layer of the dielectric superlattice 40

(42)

optically low index layer of the dielectric superlattice 40

(50)

Bandstop filter: Fabry-Perót interferometer

(51)

optically high-index layer of the Fabry-Peröt interferometer 50

(52)

optically low-index layer of the Fabry-Perót interferometer 50

(53)

electrically conductive layer of the Fabry-Peröt interferometer 50

λ0

Center wavelength of the notch filter

Δλ

Bandstop filter half-width

ΔT

Bandstop filter block depth

min

Minimum transmission of the notch filter

Tmax

Transmission value at the local transmission maxima adjacent to the stop band

(I)

Outside surface of the outer pane 1

(ii)

interior surface of the outer pane 1

(III)

outside surface of the inner pane 2

(IV)

interior surface of the inner pane 2

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016209914 [0002]
• WO 2017203132 [0002]
• WO 2017103426 [0002]
• WO 2017103426 A1 [0005]
• US20150228696A1 [0006]
• WO 2014029536 A1 [0007]
• DE 102017003621 A1 [0008]

Claims (15)

Vehicle pane consisting of an outer pane (1), which has an outside surface (I) and an inside surface (II), and an inner pane (2), which has an outside surface (III) and an inside surface (IV), the inside Surface (II) of the outer pane (1) and the outside surface (III) of the inner pane (2) are connected to one another via a thermoplastic intermediate layer (3), equipped with an electroluminescent device (20, 30) and an optical band-stop filter (40, 50 ) with a restricted region, where - the optical band-stop filter (40, 50) is designed as a thin-layer coating of optically high-index layers with a refractive index greater than 1.8 and optically low-index layers with a refractive index less than 1.8, which are arranged alternately, - the mean wavelength of the radiation emitted by the electroluminescent device (20, 30) is in the blocking range of the optical band-stop filter (40, 50), - the optical band stop filter (40, 50) is arranged in such a way that the emission of the electroluminescent device (20, 30) via the outer pane (1) or the inner pane (2) is blocked and - the full width at half maximum (Δλ) of the stop band of the band stop filter (40, 50) is from 10 nm to 50 nm. vehicle window claim 1 , wherein the optical bandstop filter is designed as a dielectric superlattice (40), all optically high-index layers (41) and all optically low-index layers (42) being dielectric layers. vehicle window claim 2 , wherein the optical thickness of the optically high-index layers (41) is from 10 nm to 30 nm, the optical thickness of the optically low-index layers (42) is from 150 nm to 400 nm and the thin-layer coating has at least five optically high-index layers (41) and at least five optically low index layers (42). vehicle window claim 2 or 3 , wherein the optically high-index layers (41) are based on silicon nitride, silicon-metal mixed nitride or titanium oxide and the optically low-index layers (42) are based on silicon oxide. vehicle window claim 1 , wherein the optical bandstop filter is designed as a Fabry-Perot interferometer (50), wherein at least some of the optically low-index layers are electrically conductive layers (53) and all the optically high-index layers (41) are dielectric layers. vehicle window claim 5 , wherein a dielectric layer sequence consisting of (m+1) optically high-index layers (51) and m optically low-index layers (52) is arranged between adjacent electrically conductive layers (53), m being a natural number greater than or equal to 1. vehicle window claim 5 or 6 , wherein the optical thickness of the optically high-index layers (51) is from 30 nm to 300 nm, the optical thickness of the dielectric optically low-index layers (52) is from 150 nm to 400 nm and the number of electrically conductive layers is at least 3. Vehicle window according to one of Claims 5 until 7 , wherein the optically high-index layers (51) are based on silicon nitride, silicon-metal mixed nitride or titanium oxide, the optically low-index layers (52) are based on silicon oxide and the electrically conductive layers (53) are based on silver. Vehicle window according to one of Claims 1 until 8th , where the sum of half the full width at half maximum of the radiation of the electroluminescent device (20, 30) and the difference between the center wavelength (λ ₀ ) of the band elimination filter (40, 50) and the center wavelength of the radiation of the electroluminescent device (20, 30) is less than half the full width at half maximum (Δλ) of the band elimination filter (40, 50). Vehicle window according to one of Claims 1 until 9 , wherein the electroluminescent device is designed as an electroluminescent film (20) which is arranged between the outer pane (1) and the inner pane (2), and wherein the optical band stop filter (40, 50) is on the outside surface (III) of the inner pane (2 ), is arranged on the interior-side surface (IV) of the inner pane (2) or within the intermediate layer (3) between the electroluminescent film (20) and the inner pane (2). Vehicle window according to one of Claims 1 until 9 , wherein the electroluminescent device is designed as an electroluminescent film (20) which is arranged between the outer pane (1) and the inner pane (2), and wherein the optical band stop filter (40, 50) is on the outside surface (I) of the outer pane (1 ), on the interior-side surface (II) of the outer pane (1) or within the intermediate layer (3) between the electroluminescent film (20) and the outer pane (1). Vehicle window according to one of Claims 1 until 9 , wherein the electroluminescent device comprises a plurality of light-emitting diodes (30) which are arranged on the interior-side surface (IV) of the inner pane (2) or in recesses of the interior-side surface (IV) of the inner pane (2), and wherein the optical bandstop filter ( 40, 50) on the outside surface (I) of the outer pane (1), on the inside surface (II) of the outer pane (1), inside the intermediate layer (3) or on the outside surface (III) of the inner pane (2). is. Vehicle window according to one of Claims 1 until 9 , wherein the electroluminescent device comprises a plurality of light-emitting diodes (30) which are arranged on the interior-side surface (II) of the outer pane (1) or in recesses of the interior-side surface (II) of the outer pane (1), and wherein the optical bandstop filter ( 40, 50) on the outside surface (I) of the outer pane (1). Vehicle window according to one of Claims 1 until 9 , wherein the electroluminescent device comprises a plurality of light-emitting diodes (30) which are arranged between the outer pane (1) and the inner pane (2), and wherein the optical band elimination filter (40, 50) on the outside surface (I) of the outer pane ( 1), on the interior-side surface (II) of the outer pane (1) or within the intermediate layer (3) between the light-emitting diodes (30) and the outer pane (1). Vehicle equipped with a vehicle window according to one of Claims 1 until 14 .

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