DE202020100793U1 - Vehicle roof window with an interference coating to avoid reflections on display devices - Google Patents

Abstract

Vehicle roof window, comprising an outer window (1) and an inner window (2), which are connected to one another via a thermoplastic intermediate layer (3), on the interior surface (11) of the outer window 1 or on the outer surface (III) of the inner window 2 or an interference coating (4) is arranged within the intermediate layer (3), which contains a plurality of electrically conductive layers and dielectric layers, the interference coating (4) being designed in such a way that the light transmission at a wavelength of 555 nm at an angle of incidence of 0 ° Surface normals is higher than at an angle of incidence of 40 °, and the integral light absorption at an angle of incidence of 0 ° is higher by a factor of at least 2 than at an angle of incidence of 40 °.

Description

The invention relates to a vehicle roof window with an interference coating. The interference coating is intended to reduce or avoid disturbing reflections on display devices such as screens or displays, in particular in the area of the dashboard.

Some automobiles are equipped with vehicle roof windows, which are often simply called "glass roofs". Sunlight can enter the vehicle from above through the vehicle roof window, which leads to a pleasant atmosphere inside the vehicle.

However, the sunlight penetrating through the vehicle roof window can lead to disturbing reflections, which occur in particular on screens, displays or the like, which are increasingly found in the area of the dashboard in modern motor vehicles. There is therefore a need for solutions to avoid such disturbing reflections. The present invention has for its object to provide an improved vehicle roof window with which disturbing reflections on display devices inside the vehicle can be avoided or at least reduced.

The object of the present invention is achieved according to the invention by a vehicle roof window according to claim 1.

The vehicle roof pane according to the invention is a composite pane and comprises an outer pane and an inner pane which are connected to one another via a thermoplastic intermediate layer. The vehicle roof window is intended to separate the interior from the external environment in a roof opening of a vehicle. In the sense of the invention, the inner pane is the pane of the vehicle roof pane facing the vehicle interior. The outer pane is the pane facing the external environment. The vehicle roof window is preferably the vehicle roof window of a motor vehicle, in particular a passenger or truck.

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

The vehicle roof window is provided with an interference coating which is applied to the interior surface of the outer window, to the outer surface of the inner window or to a carrier film which is embedded in the intermediate layer. For example, a PET film with a thickness of 50 nm is suitable as the carrier film.

The interference coating is an electrically conductive coating and is designed as a stack or sequence of thin layers. The interference coating has a plurality of electrically conductive layers, preferably three or four electrically conductive layers. The electrically conductive layers are designed as metal-containing layers, in particular as layers based on silver (silver layers). The conductive layers preferably contain at least 90% by weight of silver, particularly preferably at least 99% by weight of silver, very particularly preferably at least 99.9% by weight of silver. Alternatively, however, other electrically conductive materials can also be provided, for example gold, copper or aluminum, or transparent conductive oxides (TCO) such as indium tin oxide (ITO).

Within the scope of the present invention, the thickness or layer thickness refers to the geometric thickness, not the optical thickness, which results as a product of the refractive index and the geometric thickness.

If a layer is formed on the basis of a material, the layer mainly consists of this material, in particular essentially of this material in addition to any impurities or doping.

One or more dielectric layers are arranged between adjacent conductive layers. Likewise, are above the top conductive layer and below the bottom conductive Layers arranged one or more dielectric layers. The lowest conductive layer is the layer that has the smallest distance from the substrate on which the coating is deposited. The uppermost conductive layer is the layer which has the greatest distance from the substrate.

It has been shown that the disturbing reflections occur in particular at an angle of incidence between 30 ° and 50 °, in particular between 34 ° and 46 °, with respect to the roof normal. Depending on the size of the roof, larger angles of incidence can also occur, which can also lead to disturbing reflections. The interference coating according to the invention is characterized in that it has an angle-dependent light transmission spectrum. The transmission spectrum at an angle of incidence of 0 ° should approximate the eye sensitivity curve as far as possible. The transmission spectrum of the interference coating shifts at other angles of incidence. The interference coating is ideally designed in such a way that the transmission at 555 nm (maximum eye sensitivity curve) is as high as possible at an angle of incidence of 0 ° and as low as possible at an angle of incidence of 40 ° (average angle at which the interference reflex is perceived).

The interference coating has the advantage that the vehicle occupants can still see the outside environment through the roof and that a sufficient amount of light penetrates into the interior at an angle of incidence of 0 °. Due to the reduced transmission at higher angles of incidence, the disturbing reflections on display devices are reduced. The vehicle occupants are less distracted and can read the display device better.

The integral light transmission in the visible spectral range is preferably reduced when the angle changes from 0 ° to 40 °. It has been shown that with the reflection coating according to the invention, reductions by about a factor can be achieved without problems 2nd can be achieved.

The outer pane, the inner pane and the thermoplastic intermediate layer can be clear and colorless, but also tinted or colored. In an advantageous embodiment, the outer pane, the inner pane and / or the intermediate layer are tinted and thus light-absorbing. As a result, the transmission can be reduced further without changing the relative behavior when the angle changes.

In addition to the interference coating, the vehicle roof window can have further coatings, for example an emission-reducing coating (LowE coating) on the interior-side surface of the inner window. The LowE coating preferably has an electrically conductive layer based on a transparent conductive oxide (TCO), in particular based on indium tin oxide (ITO).

The interference coating is applied to one of the surfaces of the two panes facing the intermediate layer, that is to say the inner surface of the outer pane or the outer surface of the inner pane. Alternatively, the interference coating can also be arranged within the thermoplastic intermediate layer, for example applied to a carrier film which is arranged between two thermoplastic connecting films. In one embodiment of the invention, at least 80% of the pane surface is provided with the interference coating according to the invention. In particular, the interference coating is applied to the entire surface of the pane, with the exception of a peripheral edge area and optionally a local area, which, as communication, sensor or camera windows, are intended to ensure the transmission of electromagnetic radiation through the vehicle roof pane and are therefore not provided with the interference coating. The circumferential uncoated edge area has a width of up to 20 cm, for example. It prevents the interference coating from coming into direct contact with the surrounding atmosphere, so that the interference coating inside the windshield is protected against corrosion and damage.

Due to the electrically conductive layers, the interference coating according to the invention has IR-reflecting properties, so that it functions as a sun protection coating, which reduces the heating of the vehicle interior by reflection of the thermal radiation. The reflective coating can also be used as a heating coating when contacted electrically so that a current flows through it that heats the interference coating.

The desired transmission characteristics mentioned above are achieved in particular by the choice of materials and thicknesses of the individual layers. The interference coating can thus be set appropriately.

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 from 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. Preferably, panes with a thickness in the range from 0.8 mm to 5 mm, preferably from 1.4 mm to 2.5 mm are used, for example those with the standard thicknesses 1.6 mm or 2.1 mm. The outer pane and the inner pane can not be independently biased, partially biased or biased. If at least one of the disks should have a prestress, this can be a thermal or chemical prestress.

The vehicle roof window can be bent in one or more directions of space, as is customary for motor vehicle windows, with typical radii of curvature in the range from approximately 10 cm to approximately 40 m. The vehicle roof window can also be flat.

The thermoplastic intermediate layer contains at least one thermoplastic polymer, preferably 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 a thermoplastic film. The thickness of the intermediate layer is preferably from 0.2 mm to 2 mm, particularly preferably from 0.3 mm to 1 mm.

The vehicle roof window can be produced 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 processes, vacuum bag processes, vacuum ring processes, calender processes, vacuum laminators or combinations thereof. The connection of the outer pane and inner pane is usually carried out under the action of heat, vacuum and / or pressure.

The interference coating is preferably applied to a pane surface by physical vapor deposition (PVD), particularly preferably by cathode sputtering (“sputtering”), very particularly preferably by magnetic field-assisted cathode sputtering (“magnetron sputtering”). Instead of applying the interference coating to a pane surface, it can in principle also be provided on a carrier film which is arranged in the intermediate layer, for example between two thermoplastic connecting films.

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 in no way limits the invention.

• 1 einen Querschnitt durch eine Ausgestaltung der erfindungsgemäßen Fahrzeugdachscheibe,
• 2 Transmissionsspektren einer Fahrzeugdachscheibe nach Beispiel 1 bei Einstrahlwinkeln von 0° und 40°.

Show it:

• 1 3 shows a cross section through an embodiment of the vehicle roof window according to the invention,
• 2nd Transmission spectra of a vehicle roof window according to Example 1 at angles of incidence of 0 ° and 40 °.

1 schematically shows an embodiment of the vehicle roof window according to the invention. The vehicle roof window is made up of an outer window 1 and an inner pane 2nd that have a thermoplastic intermediate layer 3rd are interconnected. The outer pane 1 in the installed position faces the external environment, the inner pane 2nd the vehicle interior.

The outer pane 1 has an outside surface I, which faces the external environment in the installed position, and an inside surface II which faces the interior in the installed position. The inner pane also points 2nd an outside surface III on, which faces the external environment in the installed position, and an interior surface IV which faces the interior in the installed position. The outer pane 1 and the inner pane 2nd consist, for example, of soda-lime glass. The outer pane 1 For example, the inner pane has a thickness of 2.1 mm 2nd a thickness of 1.6 mm or 2.1 mm. The intermediate layer 3rd is for example made of a PVB film with a thickness of 0.76 mm.

The interior surface II the outer pane 1 is with an interference coating according to the invention 4th Mistake. Alternatively, the outside surface could III the inner pane 2nd with the interference coating 4th be provided.

The interference coating 4th is a thin-film stack with several electrically conductive layers based on silver and dielectric layers. The desired properties of the interference coating can be achieved by means of a suitable structure with regard to the number, material and geometric thickness of the individual layers 4th realize.

Table 1 shows an embodiment of the interference coating according to the invention 4th shown with the materials and layer thicknesses of the individual layers according to an example 1. Table 1 material Reference numerals Layer thickness example 1 Lime-soda glass 1 2.1 mm SiN 4th 5 nm SiO 60nm SiN 20 nm Ag 14 nm SiN 55 nm SiO 120 nm SiN 55 nm Ag 32 nm SiN 55 nm SiO 120 nm SiN 55 nm Ag 14 nm SiN 20 nm SiO 60 nm SiN 5 nm PVB 3rd 0.76 mm Lime-soda glass 2nd 2.1 mm

The interference coating 4th has three electrically conductive layers based on silver (Ag). A dielectric layer sequence is arranged between adjacent conductive layers and below the lowermost conductive layer and above the uppermost conductive layer. The dielectric layer sequences each comprise a first optically high refractive index layer with a refractive index greater than 1.8, an optically low refractive index layer with a refractive index less than 1.8 and a second optically high refractive index layer with a refractive index greater than 1.8. In the present example, the low-index layers are formed on the basis of silicon oxide (SiO) and the high-index layers on the basis of silicon nitride (SiN).

The SiN and SiO layers can be doped independently of one another, for example with boron or aluminum.

In principle, more or less electrically conductive layers can also be present. Basically, more dielectric layers can also be present. Each dielectric structure, separated from the other dielectric structures by an electrically conductive layer, should include n optically low-index layers with a refractive index less than 1.8 and (n + 1) optically high-index layers with a refractive index greater than 1.8, each alternating are arranged. n is an integer greater than or equal to 1.

If a first layer is arranged above a second layer, this means in the sense of the invention that the first layer is arranged further away from the substrate on which the coating is applied than the second layer. In the sense of the invention, if a first layer is arranged below a second layer, this means that the second layer is arranged further away from the substrate than the first layer. The specified values for refractive indices are measured at a wavelength of 550 nm.

The optically high refractive index layers can alternatively also be formed, for example, on the basis of tin-zinc oxide, silicon-zirconium nitride, zirconium oxide, niobium oxide, hafnium oxide, tantalum oxide, tungsten oxide, titanium oxide or silicon carbide. The optically low-refractive-index layers can alternatively also be formed, for example, on the basis of silicon oxide, aluminum oxide, magnesium fluorite, silicon oxynitride or calcium fluorite.

The light transmission spectrum of a vehicle roof window according to Example 1 is in 2nd shown for different angles of incidence. The spectrum at an angle of incidence of 0 ° is adapted to the sensitivity curve of the human eye with regard to shape and spectral position. At an angle of incidence of 0 °, the maximum is close to 555 nm. It can be seen that the spectrum is clearly shifted into the blue at an angle of incidence of 40 ° compared to an angle of incidence of 0 °. As a result, the transmission at 555 nm (maximum eye sensitivity) is significantly lower. Disturbing light reflections on display devices inside the vehicle, especially in the cockpit area or on the dashboard, which are caused in particular by incident sunlight at angles of incidence of 40 °, are therefore less perceived by the vehicle occupants.

The integral light transmission (light source A, viewing angle 2 °) was 35.6 at an angle of incidence of 0 ° and only 17.9 at an angle of incidence of 40 °.

In another example, instead of the transparent PVB film of the example 1 a tinted PVB film is used (Eastman RB47). This made it possible to further reduce the integral transmission (angle of incidence 0 °: 12.4; angle of incidence 40 °: 5.7), which further enhances the positive effect.

Table 2 shows a further embodiment of the interference coating according to the invention 4th represented with the materials and layer thicknesses of the individual layers according to an example 2. It can be seen that in contrast to example 1 and 1 the interference coating on the outside surface III the inner pane is arranged.

The interference coating 4th has four electrically conductive layers based on silver (Ag). A dielectric layer sequence is arranged between adjacent conductive layers and below the lowermost conductive layer and above the uppermost conductive layer. The dielectric layer sequences shown are common for IR-reflective coatings in the vehicle sector. Table 2 material Reference numerals Layer thickness example 2 Lime-soda glass 1 2.1 mm PVB 3rd 0.76 mm SiN 4th 15 nm SiZrN 8.7 nm ZnO 13 nm NiCr 0.2 nm Ag 10.1 nm ZnO 12 nm ZnSnO 10 nm SiZrN 20.5 nm SiN 20.9 nm ZnO 16 nm NiCr 0.2 nm Ag 30 nm ZnO 14 nm ZnSnO 11 nm SiZrN 23.5 nm SiN 17.2 nm ZnO 15 nm NiCr 0.3 nm Ag 43.3 nm ZnO 16 nm ZnSnO 10 nm SiZrN 35.5 nm ZnO 16 nm NiCr 0.2 nm Ag 20 nm ZnO 11 nm ZnSnO 8 nm SiZrN 12.5 nm Lime-soda glass 2nd 1.6 mm

The transmission spectrum of Example 2 is also approximated to the eye sensitivity curve and has a position which is dependent on the angle of incidence.

The layers based on silicon nitride (SiN) or silicon zirconium nitride (SiZrN) fulfill the function of anti-reflective layers, which reduce the reflection of visible light and thus increase the transparency of the coated pane. The anti-reflective layers can alternatively also be formed, for example, on the basis of aluminum nitride (AIN), tin oxide (SnO) or other silicon-metal mixed nitrides (such as silicon hafnium nitride). The proportion of zirconium in SiZrN is preferably between 15 and 45% by weight, particularly preferably between 15 and 30% by weight.

The layers based on silicon nitride zinc oxide (ZnO) fulfill the function of matching layers which improve the crystallinity of the electrically conductive layers. The adaptation layers improve the surface resistance of the coating. The matching layers preferably contain zinc oxide ZnO _1-δ with 0 δ 0,0 0.01. The zinc oxide is preferably deposited sub-stoichiometrically with respect to the oxygen in order to avoid a reaction of excess oxygen with the silver-containing layer.

The layers based on zinc-tin mixed oxide (ZnSnO) fulfill the function of smoothing layers, which bring about an optimization, in particular smoothing, of the surface for an electrically conductive layer subsequently applied above. An electrically conductive layer deposited on a smoother surface has a higher transmittance with a lower surface resistance. The smoothing layer preferably contains at least one non-crystalline oxide. The oxide can be amorphous or partially amorphous (and thus partially crystalline), but is not completely crystalline. The non-crystalline smoothing layer has a low roughness and thus forms an advantageously smooth surface for the layers to be applied above the smoothing layer. The non-crystalline smoothing layer also brings about an improved surface structure of the layer deposited directly above the smoothing layer. The smoothing layer can contain, for example, at least one oxide of one or more of the elements tin, silicon, titanium, zirconium, hafnium, zinc, gallium and indium. The smoothing layer particularly preferably contains a non-crystalline mixed oxide, in particular tin-zinc mixed oxide (ZnSnO). The mixed oxide preferably has a substoichiometric oxygen content.

The tin content is preferably between 10 and 40% by weight, particularly preferably between 12 and 35% by weight.

The layers based on a nickel-chromium alloy (NiCr) fulfill the function of blocker layers. The blocker layer can also contain niobium, titanium, nickel, chromium and / or alloys thereof. The layer thickness of the blocker layer is preferably from 0.1 nm to 2 nm, particularly preferably from 0.1 nm to 1 nm. A blocker layer immediately below the electrically conductive layer serves in particular to stabilize the electrically conductive layer during a temperature treatment and improves the optical quality the electrically conductive coating. A blocker layer immediately above the electrically conductive layer prevents contact of the sensitive electrically conductive layer with the oxidizing reactive atmosphere during the deposition of the subsequent layer by reactive sputtering.

The dielectric layers can also be doped, for example with aluminum, boron or antimony.

Simpler layer structures are also conceivable. In particular, dielectric layers with a low refractive index need not necessarily be present in the layer structure. For example, the interference coating can be built up from the substrate from the following layers: SiZrN / Ag / SiZrN / Ag / SiZrN / Ag / SiZrN / Ag / SiZrN

The dielectric oxides and nitrides described above can be deposited stoichiometrically, substoichiometrically or superstoichiometrically. For the sake of simplicity, stoichiometry was not given in the examples.

Reference list

(1)

Outer pane

(2)

Inner pane

(3)

thermoplastic intermediate layer

(4)

Interference coating

(I)

outside surface of the outer pane 1

(II)

interior surface of the outer pane 1

(III)

outside surface of the inner pane 2nd

(IV)

interior surface of the inner pane 2nd

Claims (1)

Vehicle roof window, comprising an outer window (1) and an inner window (2), which are connected to one another via a thermoplastic intermediate layer (3), on the interior surface (11) of the outer window 1 or on the outer surface (III) of the inner window 2 or an interference coating (4) is arranged within the intermediate layer (3), which contains a plurality of electrically conductive layers and dielectric layers, the interference coating (4) being designed in such a way that the light transmission at a wavelength of 555 nm at an angle of incidence of 0 ° Surface normals is higher than at an angle of incidence of 40 °, and the integral light absorption at an angle of incidence of 0 ° is higher by a factor of at least 2 than at an angle of incidence of 40 °.

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