Composite pane with electrically controllable functional element and electrically controllable reflection element

Abstract

The invention relates to a composite pane (100) for a projection arrangement, comprising - an outer pane (1) and an inner pane (2) which are connected to one another via a thermoplastic intermediate layer (3), - an electrically controllable functional element (4), which can be switched at least into an opaque state and into a transparent state, and - an electrically controllable reflection element (5), which can be switched at least into a transparent state and at least into a reflective state, wherein the electrically controllable functional element (4) extends over a functional region (F) of the composite pane (100) and the electrically controllable reflection element (5) extends over a projection region (P) of the composite pane (100), wherein the projection region (P) at least partially overlaps with the functional region (F), and the electrically controllable reflection element (5) is arranged in front of the electrically controllable functional element (4) in a view through the composite pane (100), looking from the inner pane (2) to the outer pane (1).

Description

[0001] Composite pane with electrically controllable functional element and electrically controllable reflection element

[0002] The invention relates to a composite pane with an electrically controllable functional element and an electrically controllable reflection element as well as a projection arrangement with the composite pane.

[0003] Windshields for vehicles, particularly motor vehicles such as passenger cars, are typically constructed as laminated glass (laminated safety glass), consisting of an outer pane and an inner pane laminated together via a thermoplastic interlayer. They typically have an opaque masking region, which is formed as a peripheral edge region surrounding a central see-through region. The opaque masking region primarily serves to protect the adhesive used to bond the windshield to the vehicle body from UV radiation. The masking region is typically formed by a black masking print on the surface of the outer pane facing the interlayer.

[0004] Modern vehicles are increasingly being equipped with so-called head-up displays (HUDs). Using a projector, typically located in the dashboard, images are projected onto the windshield's viewable area, reflected there, and perceived by the driver as a virtual image (as seen from the driver's perspective) behind the windshield. This allows important information to be projected into the driver's field of vision, such as the current speed, navigation information, or warnings, which the driver can perceive without having to take their eyes off the road. Head-up displays can therefore significantly contribute to improving road safety.

[0005] It has also been proposed to use the opaque masking area as a display surface for a display system. For this purpose, a display area in the masking area is illuminated by an imaging unit such as a screen. Examples include DE102009020824A1, WO2022073894A1, and W02022073860A1. In this way, displays for the driver that were previously located in the dashboard area can be shown on the windshield itself. Examples of such displays include the driving speed, the time, the engine speed, the navigation system display, information on speed limits (traffic sign recognition), the image from a rear-facing camera, and various status displays on the vehicle's condition. Such display systems in the masking area are also preferably operated with p-polarized radiation to avoid reflection from the glass surfaces and the resulting ghost images.Reflecting the image in front of or within a masking area creates a high-contrast image that is more visually perceptible for vehicle occupants. However, a masking area of ​​sufficient size is required to display the information. This limits the view of the outside environment through the windshield.

[0006] WO 2022 / 214369 relates to a composite pane, in particular for a projection arrangement, comprising: an outer pane, an inner pane, a first masking strip arranged in regions on an outer side or an inner side of the inner or outer pane, an electrically conductive coating, and a reflective layer suitable for reflecting light. The reflective layer is arranged spatially in front of the first masking strip in the viewing direction from the inner pane to the outer pane, wherein the first masking strip overlaps the reflective layer at least in one region. The opaque masking strip ensures improved visibility of the projected image through optical contrast. A disadvantage of this solution is that the view through the composite pane is restricted even when no image is being projected.Especially for vehicle windows, an arrangement of the opaque masking area is therefore typically only suitable in an edge area of ​​the vehicle window in order to ensure unobstructed visibility in the central area of ​​the vehicle window.

[0007] WO 2022 / 228946 relates to a composite pane, in particular for a projection arrangement, comprising an electrochromic functional element arranged between an outer pane and an inner pane, and a partially translucent reflective layer suitable for reflecting light. The reflective layer is arranged spatially in front of the electrochromic functional element in the viewing direction from the inner pane to the outer pane and overlaps with the electrochromic functional element at least in one region. The electrochromic functional element is arranged in an edge region of the outer pane and the inner pane. A disadvantage of this solution is that the reflective layer has light-reflecting properties even when the imaging unit is switched off, which can cause irritation to the user.

[0008] WO 2023 / 213621 relates to a composite pane for a projection arrangement, comprising a first pane, a second pane, a thermoplastic intermediate layer, wherein the first pane is connected to a second pane via an intermediate layer to form a composite pane, and a mirror structure with electrically switchable optical properties. The mirror structure is arranged in front of an opaque masking strip in the viewing direction through the composite pane.

[0009] What all these solutions have in common is that in the display area, visibility through the pane is made difficult due to reflective properties or masking, which limits the view of the outside environment.

[0010] The object of the present invention is therefore to provide an improved composite pane suitable for use in a projection system with a high-contrast image and which allows for a better view of the surroundings when needed. A further object of the invention is to provide a projection system with similar properties.

[0011] The object of the present invention is achieved by a composite pane according to claim 1 and a projection arrangement according to claim 15. Preferred embodiments are evident from the subclaims.

[0012] The invention relates to a composite pane for a projection system. The composite pane comprises an outer pane and an inner pane, which are connected to each other via a thermoplastic intermediate layer. The composite pane also comprises an electrically controllable functional element and an electrically controllable reflection element.

[0013] The electrically controllable functional element can be switched to at least one opaque state and one transparent state. This means that the electrically controllable functional element can be switched to at least two different states that differ in the transmittance for visible light in the wavelength range from 380 nm to 780 nm. The state with a higher transmittance for visible light is referred to as the transparent state, and the state with a lower transmittance for visible light is referred to as the opaque state.

[0014] In an advantageous embodiment, the electrically controllable functional element has further states in addition to the transparent state and the opaque state. These further states have a transmittance for visible light that lies between the transmittance for visible light in the transparent state and the transmittance for visible light in the opaque state. In this way, the transmittance of visible light can be adjusted according to the user's wishes and the visibility conditions. For example, a particularly opaque state can be selected when the laminated pane is exposed to strong sunlight. In a particularly advantageous embodiment, the electrically controllable functional element has several further equidistant states between the opaque state and the transparent state.In this way, the transmittance for visible light can be adjusted according to the needs of the user and the lighting conditions.

[0015] The electrically controllable reflection element can be switched to at least one transparent state and one reflective state. This means that the electrically controllable reflection element can be switched to at least two different states that differ in the reflectance for visible light in the wavelength range from 380 nm to 780 nm. The state with a higher reflectance for visible light is referred to as the reflective state, and the state with a lower reflectance for visible light is referred to as the transparent state. It is understood that in the transparent state, the light transmittance is higher than in the reflective state, and that in the reflective state, the reflectance is higher than in the transparent state.

[0016] In an advantageous embodiment, the electrically controllable reflection element has further states in addition to the transparent state and the reflective state. These further states have a reflectance for visible light which lies between the reflectance for visible light in the transparent state and the reflectance for visible light in the reflective state. In this way, the reflectance for visible light and thus for the radiation of a projector can be adjusted according to the user's wishes and the visibility conditions. For example, when the composite pane is exposed to strong sunlight, a particularly reflective state can be selected. In a particularly advantageous embodiment, the electrically controllable reflection element has several further states equidistant from one another between the reflective state and the transparent state.In this way, the degree of reflection for visible light can be adjusted according to the user's needs and the lighting conditions. According to the invention, the electrically controllable functional element extends over a functional area of ​​the composite pane, which is designed to be switchable between transparent and opaque. The electrically controllable reflection element extends over a projection area of ​​the composite pane, which is designed to serve as a virtual image display for a projection arrangement.

[0017] The outer pane has an outer surface, an interior surface, and a circumferential side edge surface, wherein the interior surface is the surface of the outer pane facing the inner pane, and the outer surface is the surface of the outer pane facing away from the inner pane. Likewise, the inner pane has an outer surface, an interior surface, and a circumferential side edge surface, wherein the outer surface is the surface of the inner pane facing the outer pane, and the interior surface is the surface of the inner pane facing away from the outer pane. The composite pane according to the invention can be part of the boundary of an interior, for example as a windshield in a motor vehicle.In the case where the laminated pane defines an interior space, typically the outside surface of the outer pane faces the outside environment and the inside surface of the inner pane faces the interior space.

[0018] According to the invention, the projection area at least partially overlaps the functional area, and the electrically controllable reflection element is arranged in front of the electrically controllable functional element when viewed through the composite pane, from the inner pane to the outer pane. Viewing through the composite pane, from the inner pane to the outer pane, is understood to mean that the viewing direction is perpendicular to the main surface of the composite pane.

[0019] The fact that the projection area at least partially overlaps with the functional area means that at least a sub-area of ​​the projection area is also a sub-area of ​​the functional area. This sub-area of ​​the projection area, which is simultaneously a sub-area of ​​the functional area, can also be referred to as the area where the projection area overlaps with the functional area. The projection area and the functional area can be identical; the entire functional area can be a sub-area of ​​the projection area; the entire projection area can be a sub-area of ​​the functional area; or the functional area and the projection area can overlap in areas without one being a sub-area of ​​the other. If the projection area is a sub-area of ​​the functional area, only this sub-area of ​​the functional area can be switched to reflectivity.In this embodiment, for example, in the case of a vehicle windshield, the functional area can be arranged in the lower area of ​​the windshield. This allows the entire projection area to display a high-contrast image when needed. On the other hand, the lower area can also be used as a head-up display if the electrically controllable functional element is switched to transparent and the electrically controllable reflective element is switched to a reflective state with partial transparency.

[0020] If the composite pane is part of a projection arrangement, the electrically controllable functional element can, for example, be switched to an opaque state and the electrically controllable reflective element to a reflective state. In this way, an image can be projected onto the composite pane, which is reflected by the electrically controllable reflective element. In the opaque state and in the overlap area with the electrically controllable reflective element, the electrically controllable functional element provides optical contrast by darkening the image, improving visibility of the projected image.

[0021] Alternatively, the electrically controllable reflection element can be switched to the reflective state and the electrically controllable functional element can be switched to the transparent state. In this case, an image can be projected onto the electrically controllable reflection element in the overlap area of ​​the projection area with the functional area, while maintaining sufficient transparency of the pane.

[0022] Alternatively, it is also possible for the electrically controllable reflection element to be switched to the transparent state and the electrically controllable functional element to be switched to the opaque state. This variant is particularly suitable if no image is projected onto the composite pane. This allows the functional area to be darkened, if this is desired for aesthetic reasons, for example. By switching the electrically controllable reflection element to the transparent state, unwanted reflections on the composite pane are avoided in the area where the projection area overlaps with the functional area. This is particularly suitable if the projection area is a sub-area of ​​the functional area or if the projection area and the functional area are identical.Alternatively, it is also possible for the electrically controllable reflective element to be switched to the transparent state, and for the electrically controllable functional element to be switched to the transparent state. In this case, the composite pane allows for a largely unobstructed view through the composite pane.

[0023] The composite pane is therefore versatile and can be switched between the previously mentioned variants as required, depending on whether darkening of the functional area is desired and whether an image is projected onto the electrically controllable reflection element.

[0024] The composite pane according to the invention is particularly suitable for use as a windshield in a vehicle, preferably a passenger car. A windshield typically has an upper edge which, in the installed position, faces the vehicle roof, and an opposite lower edge, also referred to as the engine edge, which, in the installed position, faces the engine compartment. In addition, the windshield has two opposite side edges. The windshield can fundamentally have various shapes, for example a rectangular shape in which the side edges are of equal length and parallel to one another; a trapezoidal shape is also common, in which the lower edge is arranged parallel to the upper edge and in which the lower edge is longer than the upper edge.

[0025] The composite windscreen allows the driver to adjust the available field of vision in confusing traffic situations. When the vehicle is stationary, for example, in a traffic jam or while waiting at a traffic light, the electrically controllable functional element can be briefly switched to the opaque state and the electrically controllable reflective element to the reflective state to project an image onto the electrically controllable reflective element. If necessary, the electrically controllable functional element can also be switched to the opaque state and the electrically controllable reflective element to the reflective state while driving.Particularly in confusing traffic situations, the composite pane can be adjusted so that the viewable area can be enlarged by switching the electrically controllable functional element and the electrically controllable reflective element transparent. Furthermore, the driver can adjust the contrast of the projection in the projection area to the lighting conditions. These are major advantages of the present invention.The electrically controllable functional element typically has an outside surface, an inside surface and a circumferential side edge surface, wherein the outside surface is intended to face the outside environment and the inside surface is intended to face the interior. In the case that the electrically controllable functional element is arranged between the outer pane and the inner pane, the outside surface of the electrically controllable functional element faces the outer pane and the inside surface of the electrically controllable functional element faces the inner pane.

[0026] Likewise, the electrically controllable reflective element typically has an exterior surface, an interior surface, and a peripheral side edge surface, wherein the exterior surface is intended to face the exterior environment and the interior surface is intended to face the interior. In the case where the electrically controllable reflective element is arranged between the outer pane and the inner pane, the exterior surface of the electrically controllable reflective element faces the outer pane, and the interior surface of the electrically controllable reflective element faces the inner pane. It is understood that the interior surface of the electrically controllable functional element faces the exterior surface of the electrically controllable reflective element.

[0027] In an advantageous embodiment, the projection area is a sub-area of ​​the functional area, or the projection area is identical to the functional area. This embodiment has the advantage of allowing dimming of the entire projection area.

[0028] In an advantageous embodiment, the projection area and the functional area are arranged in the edge area of ​​the composite pane. In the areas outside the projection area and the functional area, an unobstructed view through the composite pane is thus possible. If the composite pane is designed as a windshield, the projection area and the functional area are preferably arranged in a lower section of the windshield. The lower section of the windshield refers to the section which is arranged closer to the lower edge than to the upper edge of the windshield. In this case, the projection area is preferably a partial area of ​​the functional area. In this way, an image can then be projected into the lower section of the windshield, and this area can be darkened.The electrically controllable functional element and the electrically controllable reflective element are preferably arranged between the outer pane and the inner pane. The outer pane and the inner pane are connected to one another via the thermoplastic intermediate layer; preferably, the electrically controllable functional element and the electrically controllable reflective element are embedded in the thermoplastic intermediate layer. In general, the thermoplastic intermediate layer is typically formed from one or more thermoplastic films, also called thermoplastic layers.Where the thermoplastic films are in direct contact with one another and are not separated by the electrically controllable functional element and / or the electrically controllable reflective element, they can fuse during lamination in such a way that the original layers are typically no longer recognizable, and instead, a homogeneous thermoplastic intermediate layer is present. In the case where the electrically controllable functional element and the electrically controllable reflective element are embedded in the thermoplastic intermediate layer, the electrically controllable functional element and the electrically controllable reflective element are preferably arranged between at least two layers of thermoplastic material of the intermediate layer, wherein the first thermoplastic layer is bonded to the outer pane and the second thermoplastic layer is bonded to the inner pane.

[0029] In a particularly advantageous embodiment, the electrically controllable functional element and the electrically controllable reflective element are bonded to one another over a surface via a transparent adhesive layer. Typically, the electrically controllable reflective element and the electrically controllable functional element each have an outer surface facing the outer pane and an interior surface facing the inner pane. Bonding the electrically controllable functional element and the electrically controllable reflective element over a surface via the transparent adhesive layer means that the interior surface of the electrically controllable functional element is bonded to the adhesive layer, and the outer surface of the electrically controllable reflective element is bonded to the adhesive layer.This embodiment has the advantage that the electrically controllable functional element and the electrically controllable reflection element are held in a fixed position relative to one another. Furthermore, only one adhesive layer is required in this embodiment, simplifying the manufacturing process. Preferably, the side edges of the electrically controllable functional element and the electrically controllable reflection element are completely surrounded by the thermoplastic intermediate layer. In a particularly advantageous embodiment, a third thermoplastic layer with a recess is arranged between the first thermoplastic layer and the second thermoplastic layer, in which recess the electrically controllable reflection element and the electrically controllable functional element are preferably arranged.The third thermoplastic layer surrounds the electrically controllable functional element and the electrically controllable reflective element in a frame-like manner, similar to a passe-partout, to prevent local height differences in the laminate and unwanted forces acting on the electrically controllable functional element and the electrically controllable reflective element. This compensates for the local thickness difference introduced by the locally limited electrically controllable functional element and the electrically controllable reflective element, making the composite pane more stable and resulting in an improved visual appearance. In one advantageous embodiment, the third thermoplastic layer has a tint.The third thermoplastic layer is advantageously tinted such that, compared to the functional area and / or the projection area, it has a substantially identical tint intensity, relative to the tint of the areas when the functional element and / or the reflective element in the respective area is switched to the transparent state. This makes it possible to ensure similar transparency when viewed through the laminated pane in the projection area and / or functional area and in the area of ​​the windshield that does not coincide with the projection area and / or functional area.

[0030] In an alternative preferred embodiment, a third thermoplastic layer is arranged between the first thermoplastic layer and the second thermoplastic layer. The third thermoplastic layer has a recess in which the electrically controllable functional element is arranged. Furthermore, a fourth thermoplastic layer is arranged between the third thermoplastic layer and the second thermoplastic layer. The fourth thermoplastic layer also has a recess in which the electrically controllable reflection element is arranged. This variant is particularly suitable when each of the elements has its own sealing layer(s) along its circumferential side edge surface. This sealing layer(s) serves to prevent the diffusion of plasticizers into the active layer of the elements.In a further advantageous embodiment, the electrically controllable functional element and the outer pane are bonded to one another via an external adhesive layer, and the electrically controllable reflective element and the inner pane are bonded to one another via an internal adhesive layer. The electrically controllable functional element is preferably bonded to the internal surface of the outer pane via the external adhesive layer, but can alternatively also be bonded to the external surface of the outer pane. If the electrically controllable functional element is attached to the external surface via the adhesive layer, it is preferably protected from external damage, for example, by a transparent protective layer.The electrically controllable reflection element is preferably bonded to the outer surface of the inner pane via the interior-side adhesive layer, but can alternatively also be bonded to the interior-side surface of the inner pane. If the electrically controllable reflection element is attached to the interior-side surface via the adhesive layer, it is preferably protected from external damage, for example, by a transparent protective layer. This embodiment has the advantage that it ensures that the electrically controllable reflection element is arranged parallel to the inner pane and that the electrically controllable functional element is arranged parallel to the outer pane, largely preventing undesired changes in the position of the elements during lamination.In this case, the electrically controllable reflection element and the electrically controllable functional element are each preferably arranged in a thermoplastic film with a recess, and between them a further thermoplastic film without a recess is arranged for separation.

[0031] In an alternative embodiment, the electrically controllable functional element and the electrically controllable reflective element are embedded in the thermoplastic intermediate layer and surrounded by it in a frame-like manner, without the electrically controllable functional element and the electrically controllable reflective element being connected to one another via an adhesive layer. For this purpose, a first thermoplastic intermediate layer can be arranged between the outer pane and the inner pane, starting from the outer pane, followed by a first frame-shaped thermoplastic intermediate layer that surrounds the electrically controllable functional element in the form of a passe-partout, then a third thermoplastic intermediate layer and a fourth thermoplastic intermediate layer that surrounds the electrically controllable reflective element in a frame-like manner in the form of a passe-partout, and finally a fifth thermoplastic intermediate layer that is arranged on the inner pane.In an alternative embodiment, only the electrically controllable reflection element or the electrically controllable functional element is arranged between the outer pane and the inner pane and, for example, embedded in the thermoplastic intermediate layer. Thus, it is possible for the electrically controllable functional element to be arranged between the outer pane and the inner pane, and for the electrically controllable reflection element to be arranged on the interior-side surface of the inner pane. Alternatively, the electrically controllable functional element can be arranged on the exterior surface of the outer pane, and the electrically controllable reflection element can be arranged between the outer pane and the inner pane.

[0032] The layers of the thermoplastic intermediate layer are preferably made of the same material, but can in principle also be made of different materials. The layers or films of the thermoplastic intermediate layer are preferably based on polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), or polyurethane (PU). If a layer or film is based on one material, this means that the layer or film predominantly contains the said material (a proportion of greater than 50 wt.%) and can optionally contain other components, for example, plasticizers, stabilizers, UV or IR absorbers. The thickness of each individual thermoplastic layer is preferably from 0.1 mm to 2 mm, particularly preferably from 0.3 mm to 1 mm.Particularly preferably, the total thickness of the thermoplastic intermediate layer, i.e., the combined thickness of all thermoplastic layers of the intermediate layer, is between 0.2 mm and 5 mm. Most preferably, the thermoplastic intermediate layer has a thickness of 0.38 mm or 0.76 mm. The layers of the thermoplastic intermediate layer can be tinted or untinted.

[0033] In a preferred embodiment, the electrically controllable functional element and the electrically controllable reflective element are arranged between the outer pane and the inner pane. In this way, they are protected from external influences. Particularly in the case where the composite pane defines an interior space, for example, in a windshield in a vehicle, it is advantageous if the electrically controllable functional element and the electrically controllable reflective element are protected from the external environment by the outer pane. If the electrically controllable functional element and the electrically controllable reflective element are arranged between the outer pane and the inner pane, they are also protected from external influences.Alternatively, the electrically controllable reflection element can be arranged on the interior-side surface of the inner pane, whereas the electrically controllable functional element is arranged between the outer pane and the inner pane, preferably embedded in the thermoplastic intermediate layer, i.e., completely enclosed by it. This is particularly advantageous for improving the optical quality of the displayed image, since ghost images are avoided by arranging the reflection element outside the composite pane. In a further alternative embodiment, the electrically controllable functional element and the electrically controllable reflection element are arranged on the interior-side surface of the outer pane or the exterior surface of the inner pane.If the functional element and the reflective element are arranged on the interior-side surface of the outer pane, for example, the electrically controllable functional element is glued to the outer pane and the electrically controllable reflective element is glued to the electrically controllable functional element. If the functional element and the reflective element are arranged on the exterior surface of the inner pane, for example, the electrically controllable reflective element is glued to the inner pane and the electrically controllable functional element is glued to the electrically controllable reflective element. These embodiments have the advantage that the electrically controllable reflective element and the electrically controllable functional element are arranged interchangeably on the exterior surface of the outer pane and on the interior-side surface of the inner pane.In this case, only a thermoplastic intermediate layer consisting of a single thermoplastic film is required to connect the outer pane and the inner pane.

[0034] In a preferred embodiment of the invention, the electrically controllable functional element comprises at least one active layer and two electrically conductive layers. The electrically conductive layers serve as surface electrodes via which electrical contact is made with the active layer. The two surface electrodes are preferably arranged on two carrier films on either side of the active layer, such that the active layer is arranged between the surface electrodes. The surface electrodes are preferably at a constant distance from one another and are particularly preferably arranged substantially parallel to the surfaces of the outer pane and the inner pane; most preferably, the active layer is also arranged substantially parallel to the surfaces of the outer pane and the inner pane.The active layer has variable optical properties with regard to transparency, which can be controlled by an electrical voltage applied to the active layer via the surface electrodes. For the purposes of the invention, electrically controllable optical properties are understood to mean, in particular, properties that are continuously controllable. For the purposes of the invention, the switching state of the electrically controllable functional element refers to the extent to which the optical properties are changed compared to the voltage-free state. A switching state of 0% corresponds to the voltage-free state, a switching state of 100% to the maximum change in the optical properties. By suitable selection of the voltage, all switching states in between can be realized continuously. A switching state of 20%, for example, corresponds to a change in the optical properties by 20% of the maximum change.Electrically controllable optical properties include, in particular, the transmittance of visible light. For example, a switching state of 20% corresponds to a 20% change in the transmittance of visible light between the maximally opaque state and the maximally transparent state.

[0035] In principle, however, it is also conceivable that the electrically controllable optical properties can only be switched between two discrete states. In this case, only two switching states exist, namely 0% and 100% of the voltage. Preferably, however, the electrically controllable optical properties can be switched between more than two discrete states.

[0036] In a preferred first embodiment of the electrically controllable functional element, the electrically controllable functional element is a guest-host functional element. Guest-host functional elements are based on liquid crystal technology. In one possible embodiment, the active layer is designed as a guest-host liquid crystal cell containing dichroic dye compounds (guest) dissolved in liquid crystals (host). The liquid crystal cell is thus arranged as an active layer between the surface electrodes. Applying an electrical voltage to the surface electrodes causes the liquid crystals to align in the electric field. This influences the orientation of the dye compounds, leading to a changed transmittance for visible light.The visible light transmittance of the guest-host liquid crystal cell depends on the orientation of the dye compounds, which in turn is determined by the preferred direction of the liquid crystals, which align when a voltage is applied in an electric field. This allows the guest-host functional element to be switched between an opaque and a transparent state, depending on whether a voltage is applied to the surface electrodes. In contrast to dimmable PDLC functional elements, switching the guest-host functional elements results in only a negligible change in light scattering (translucency). The transmission properties of the guest-host functional element can be adjusted as needed, in particular by the absorption coefficient of the incorporated dye, the thickness of the guest-host liquid crystal cell, and the dye concentration.The transparent state and the opaque state differ in that the transmittance of visible light is lower in the opaque state than in the transparent state, although a certain degree of transmittance may also be present and desired in the opaque state. The skilled person can adjust this as desired depending on the aforementioned parameters. Depending on the cell thickness and the dye concentration, the operating voltage of the guest-host liquid crystal cell can be suitably adjusted. Guest-host functional elements and the liquid crystal cells with dyes that can be used in them are commercially available and known to the skilled person.

[0037] A guest-host functional element is particularly suitable because it is cost-effective and characterized by short switching times. Furthermore, a guest-host functional element is particularly distinguished by the fact that a particularly large difference in the transmittance of visible light can be achieved in the opaque and transparent states.

[0038] In an alternative second embodiment of the electrically controllable functional element, the electrically controllable functional element is an electrochromic functional element. In electrochromic functional elements, the active layer is preferably formed as an active layer sequence between the surface electrodes, which comprises, arranged one above the other in the specified order, an ion storage layer, an electrolyte layer, and an electrochromic layer. The electrochromic layer is the actual carrier of the electrically controllable optical properties. It is an electrochemically active layer whose transmittance for visible light depends on the degree of ion incorporation. The ions (for example, H + -, Li + , N / a + - or K +Ions are stored in the ion storage layer and made available by it. The electrolyte layer spatially separates the electrochromic layer from the ion storage layer and serves to facilitate the migration of ions. If a direct voltage of suitable polarity is applied to the surface electrodes, ions migrate from the ion storage layer through the electrolyte layer into the electrochromic layer, whereupon the optical properties, in particular the transmittance of visible light of the electrochromic layer, change depending on the extent of the migrated ions. If a direct voltage of the opposite polarity is applied to the surface electrodes, the ions migrate back from the electrochromic layer through the electrolyte layer into the ion storage layer, and the optical properties of the electrochromic layer change in the opposite way. If no voltage is applied to the surface electrodes, the current state remains stable.Suitable electrochromic layers contain electrochromic materials, for example, inorganic oxides (such as tungsten oxide or vanadium oxide), complex compounds (such as Prussian blue), or conductive polymers (such as 3,4-polyethylenedioxythiophene (PEDOT) or polyaniline). The electrolyte layer is typically formed as a film of organic or inorganic, electrically insulating material with high ionic conductivity, for example, based on lithium phosphorus oxynitride. The ion storage layer is either permanently transparent (pure ion storage) or exhibits electrochromic behavior opposite to that of the electrochromic layer. An example of a pure ion storage layer is a layer containing a mixed oxide of titanium and cerium; examples of anodic electrochromic ion storage layers are layers containing iridium oxide or nickel oxide.The surface electrodes, which preferably contain or consist of an electrically conductive transparent oxide (in particular indium tin oxide), are preferably applied to transparent films, for example films based on PET or made of PET.

[0039] In a particularly preferred third alternative embodiment of the electrically controllable functional element, the electrically controllable functional element is a dimmable PDLC functional element (PDLC: polymer dispersed liquid crystal). The dimmable PDLC functional element preferably comprises an active layer and a first and a second surface electrode, which are arranged on both sides of the active layer, such that the active layer is arranged between the first and second surface electrodes. The surface electrodes and the active layer are typically arranged substantially parallel to the surfaces of the outer pane and the inner pane. The active layer has variable optical properties that can be controlled by the electrical voltage applied to the active layer via the surface electrodes.

[0040] The active layer comprises liquid crystals in a polymer matrix. Dichroic dye compounds are embedded in the polymer matrix. Applying an electrical voltage to the surface electrodes causes the liquid crystals to align in the electric field. This alignment, for example, results in an ordered state. In the voltage-free state, the liquid crystals then change to a disordered state. However, this alignment behavior when an electric field is applied or in the voltage-free state can also be reversed. The alignment of the liquid crystals preferably has only a minor influence on the transmittance of light through the active layer. The alignment primarily leads to a change in transparency: in the disordered state of the crystals, the active layer scatters light (translucency), and in the ordered state of the crystals, the active layer is transparent, as is common with conventional PDLC elements.However, the alignment of the crystals also leads to a change in the alignment of the dye compounds. In the ordered state of the liquid crystals, the dye compounds are also ordered, resulting in high transparency and a high degree of light transmittance (transparent state). In the disordered state of the liquid crystals, the dye compounds are also disordered, leading to a reduction in light transmittance and transparency (opaque state).

[0041] The transmission properties of the dimmable PDLC functional element can be adjusted as needed, in particular by the absorption coefficient of the incorporated dye, the thickness of the active layer, and the dye concentration. The skilled person can adjust this as desired depending on the aforementioned parameters. Depending, among other things, on the thickness of the active layer and the dye concentration, the operating voltage of the dimmable PDLC functional element can be specifically adjusted. Dimmable PDLC functional elements are commercially available and generally known to the skilled person. The surface electrodes, which preferably contain or consist of an electrically conductive transparent oxide (in particular indium tin oxide), are preferably applied to transparent films, for example films based on or made of PET.Dimmable PDLC functional elements are particularly preferred because they have significantly faster switching times than electrochromic functional elements, but at the same time are less susceptible to pressure damage - such as can occur during lamination of the composite pane - than guest-host functional elements.

[0042] The outer pane and the inner pane are made of an electrically insulating, in particular rigid material. The outer pane and the inner pane preferably contain or consist of glass, particularly preferably of soda-lime glass, as is common for window panes. However, the panes can also be made of other types of glass, for example quartz glass, borosilicate glass, aluminosilicate glass, or of clear plastics, preferably rigid clear plastics, in particular polyethylene, polypropylene, polycarbonate, polymethyl methacrylate, polystyrene, polyamide, polyester, polyvinyl chloride and / or mixtures thereof. The outer pane and the inner pane can be clear or tinted or colored. The outer pane and the inner pane are preferably transparent, particularly if the composite pane is a windshield.

[0043] The thickness of the outer pane and the inner pane can vary widely and thus be adapted to the requirements of the individual case. The outer pane and the inner pane preferably have thicknesses of 0.5 mm to 5 mm, particularly preferably of 1 mm to 3 mm. The size of the panes can vary widely and depends on the application. The composite pane can have any three-dimensional shape. Preferably, the outer pane and the inner pane have no shadow zones so that they can be coated, for example, by cathode sputtering. Preferably, the outer pane and inner pane are flat or slightly or strongly curved in one or more directions of the room.

[0044] In a particularly advantageous embodiment, the electrically controllable reflection element is an electrochemically switchable mirror. The electrochemically switchable mirror preferably comprises an active layer arranged between two surface electrodes, each preferably comprising a carrier film coated with an electrically conductive layer. The electrically conductive layer is preferably a transparent electrically conductive oxide (TCO); more preferably, each layer contains or consists of indium tin oxide. The carrier film is preferably made of transparent plastic, in particular polyethylene terephthalate (PET). The active layer comprises a mirrorable layer, preferably a metallic layer, for example a layer comprising yttrium or a layer comprising an alloy of magnesium and gadolinium. The mirroring layer has reflective properties.The electrochemically switchable mirror also includes a reservoir for protons (hydrogen ions). When a specific electrical voltage is applied to the surface electrodes, the hydrogen ions from the reservoir are introduced into the active layer, where they react with the mirrorable layer, causing it to lose its reflective properties and transform the active layer into a more transparent state. By changing the electrical voltage, the protons can be removed from the active layer, restoring the reflective properties to the active layer, thus transforming it into a more reflective state.

[0045] In an alternative, particularly advantageous embodiment, the electrically controllable reflection element is a mirrorable liquid crystal display. The mirrorable liquid crystal display preferably comprises a layer sequence, wherein the layer sequence comprises at least two layers provided with an electrically conductive coating. The layer sequence preferably comprises at least four, in particular exactly four layers, each provided with an electrically conductive coating. The layers can be, for example, films or glass panes, wherein the thickness of the individual layers is preferably less than 1 mm, particularly preferably less than 0.1 mm. A liquid crystal layer (hereinafter referred to as the active layer) having a helical structure is distributed between every two of the layers.The electrically conductive coatings of the layers serve as a surface electrode and are applied at least to the surface of the layer facing the liquid crystal material. In other words, each active layer is arranged directly adjacent to a surface electrode at its two main surfaces. If the layer sequence comprises four layers, then an active layer is preferably arranged between the first and second layers of the layer sequence, and an active layer is arranged between the third and fourth layers of the layer sequence. The layer sequence with four layers therefore preferably comprises exactly two active layers.

[0046] By applying a voltage to the surface electrodes, the helical structure of the active layer is entangled and the reflectivity is reduced, i.e., the degree of reflection is lowered. Since each active layer has a geometric direction (linear polarization), the layer sequence preferably comprises at least two active layers, with the second active layer rotated by 90° compared to the first active layer, thus achieving geometrically independent reflection. Reflective liquid crystal displays of this type are familiar to those skilled in the art. These are commercially available, for example, from Kent Optronics Inc. (product: Switchable Mirror / Switchable Glass). Reflective liquid crystal displays are characterized by particularly short switching times, which enable rapid switching between the transparent state and the reflective state.

[0047] Preferably, the electrically controllable reflection element, regardless of the type, is a prefabricated electrically controllable reflection element which is designed such that it can be electrically switched into at least one (light) non-reflecting state or a (light-reflecting) state by applying a corresponding operating voltage. Such electrically controllable reflection elements are typically in film form and can be easily laminated into a composite pane.

[0048] The outer pane, the inner pane and / or the thermoplastic intermediate layer may have suitable coatings known per se, for example anti-reflective coatings, non-stick coatings, anti-scratch coatings, photocatalytic coatings, UV-absorbing or reflective coatings or IR-absorbing or IR-reflective coatings such as sunscreen coatings or low-E coatings.

[0049] In an advantageous embodiment, the composite pane comprises an infrared-reflecting coating. The infrared-reflecting coating extends at least over the functional area and, when viewed through the composite pane from the inner pane to the outer pane, is arranged behind the electrically controllable functional element. The infrared-reflecting coating can effectively reflect infrared radiation from the external environment, which could otherwise lead to damage to the electrically controllable functional element.

[0050] In a preferred embodiment, the infrared-reflecting coating also extends over the projection area. This also protects the electrically controllable reflection element from infrared radiation, which could otherwise damage the electrically controllable reflection element.

[0051] In a particularly advantageous embodiment, the infrared-reflecting coating extends over the entire composite pane, with the exception of a frame-shaped edge area of ​​the composite pane. The coating-free edge area serves to protect the coating from corrosion.

[0052] In a preferred embodiment, the infrared-reflecting coating is applied to the interior-facing surface of the outer pane. This allows the electrically controllable functional element to be protected from solar radiation striking the composite pane from the outside. Alternatively, the infrared-reflecting coating is applied to a surface of the electrically controllable functional element facing the outer pane. This allows the electrically controllable functional element to be specifically protected from solar radiation striking the composite pane. This embodiment is advantageous because coating the electrically controllable reflective element is more cost-effective than coating the outer pane.

[0053] The infrared-reflecting coating is preferably a metallic layer, particularly preferably containing silver, gold, copper, nickel and / or chromium or a metal alloy, most preferably silver. In the context of this invention, the light transmittance according to ISO 9050:2003 is referred to as the transmittance. In a further advantageous embodiment, the electrically controllable functional element, in the opaque state, has a transmittance for visible light in a wavelength range from 380 nm to 780 nm of a maximum of 45%, preferably a maximum of 40%, particularly preferably a maximum of 20%, most preferably a maximum of 10%. In this range, it is ensured that the electrically controllable functional element is sufficiently opaque to ensure clear visibility of the projection image through optical contrast.Preferably, the electrically controllable functional element in the transparent state has a transmittance for visible light in a wavelength range from 380 nm to 780 nm of at least 55%, particularly preferably at least 70%, most preferably at least 90%.

[0054] The electrically controllable reflection element is designed, in a reflective state, to reflect visible light in a wavelength range from 380 nm to 780 nm. In the context of this invention, the reflectance describes the proportion of the incident visible light that is reflected, whereby the visible light strikes the composite pane at a defined angle of incidence of 65° to the surface normal. The angle of incidence of the projector radiation is the angle between the incidence vector of the projector radiation and the interior-side surface normal, i.e. the surface normal on the interior-side surface of the inner pane. In the reflective state, the electrically controllable reflection element preferably has a reflectance for visible light of at least 50%, particularly preferably of at least 70%, and in particular of at least 90%.The electrically controllable reflection element preferably has a reflectance for visible light of at most 99%, preferably of at most 95%, in the reflective state. The electrically controllable reflection element preferably reflects p-polarized and s-polarized light in equal proportions, but it can also reflect p-polarized light and s-polarized light to different intensities. The electrically controllable reflection element preferably has a high and uniform reflectance (across different angles of incidence) with respect to p-polarized and / or s-polarized radiation, thus ensuring a high-intensity and color-neutral image representation. The electrically controllable reflection element preferably has a transmittance of visible light of less than or equal to 80%, particularly preferably less than or equal to 50%, in particular less than or equal to 30%, in the reflective state.

[0055] The reflectance is measured at an angle of incidence of 65° to the interior surface normal (surface normal is the vector perpendicular to the interior surface of the laminated pane), which roughly corresponds to the irradiation from conventional projectors / radiation sources in vehicles. The reflectance describes the proportion of the total incident visible radiation that is reflected. It is given as a percentage (based on 100% incident radiation) or as a unitless number from 0 to 1 (normalized to the incident radiation). Plotted as a function of wavelength, it forms the reflection spectrum. In the context of the present invention, the statements regarding the reflectance (or percentages of reflection) compared to p-polarized, unpolarized or s-polarized radiation refer to the reflectance measured at an angle of incidence of 65° to the interior surface normal.The information on the degree of reflection or the reflection spectrum refers to a reflection measurement with a light source (e.g. a projector) that radiates uniformly in the visible spectral range (380 nm to 780 nm) with a standardized radiation intensity of 100%.

[0056] Preferably, the electrically controllable reflection element in the transparent state has a visible light transmittance of greater than or equal to 50%, particularly preferably greater than or equal to 70%, in particular greater than or equal to 90%. Preferably, the electrically controllable reflection element in the transparent state has a visible light reflectance of less than or equal to 30%, particularly preferably less than or equal to 20%, in particular less than or equal to 10%.

[0057] The term p-polarized light refers to light from the visible spectral range that predominantly consists of light exhibiting p-polarization. P-polarized light preferably has a p-polarization light component of >50%, preferably >70%, particularly preferably >90%, and in particular approximately 100%. Similarly, s-polarized light refers to light from the visible spectral range that predominantly consists of light exhibiting s-polarization, with a s-polarization light component of preferably >50%, preferably >70%, particularly preferably >90%, and in particular approximately 100%.

[0058] The electrically controllable reflection element is particularly intended to reflect an image projected by a projector onto the electrically controllable reflection element.

[0059] In a preferred embodiment, the electrically controllable reflection element has a visible light transmittance of at least 50% in the transparent state, particularly preferably at least 70%. Preferably, the electrically controllable reflection element has a visible light transmittance of at most 90% in the transparent state.

[0060] In a preferred embodiment, the composite pane additionally comprises a heating layer which extends at least over the functional area. The heating layer makes it possible to heat the windshield by applying a voltage to it. This makes it possible to heat the electrically switchable functional element. This embodiment is particularly advantageous because the switching behavior of typical electrically controllable functional elements, for example guest-host functional elements, is temperature-dependent. The electrically controllable functional element can thus be heated to quickly reach an optimal operating temperature, which is particularly helpful in cold winter conditions. Particularly preferably, the heating layer also extends over the projection area. In this way, the electrically controllable reflection element can also be heated.

[0061] In a particularly preferred embodiment, the heating layer extends at least over a first heating region of the composite pane, and the functional region is a subregion of the first heating region or the functional region is identical to the first heating region. The heating layer is connected in the first heating region to at least one first busbar and one second busbar in such a way that, when an electrical voltage is applied to the first busbar and the second busbar, a heating current flows through the heating layer in the first heating region.

[0062] Particularly advantageously, the heating layer also extends over a second heating region of the composite pane. It is understood that the second heating region does not overlap with the first heating region. Therefore, the second heating region also does not overlap with the functional region. The heating layer is connected to a third bus bar and a fourth bus bar in the second heating region of the composite pane in such a way that when an electrical voltage is applied to the third bus bar and the fourth bus bar, a heating current flows through the heating layer. In this embodiment, it is possible to heat the first heating region and the second heating region separately. In a particularly preferred embodiment, the second heating region extends over the majority of the composite pane. This means that the first heating region and the second heating region are intended to be heated using electrical energy.In the case of a windshield, the second heating region preferably comprises at least part of the upper part of the windshield. This embodiment makes it possible to heat the first heating region and the second heating region separately. This is particularly advantageous in the case of a trapezoidal composite pane, a shape that is frequently used in windshields, for example. In this case, the upper edge of the windshield is shorter than the lower edge of the windshield. For busbars arranged parallel to the side edges of the windshield, the distance between the first busbar and the second busbar and the distance between the third busbar and the fourth busbar therefore differs. This changes the sheet resistance, which affects the heating behavior.

[0063] Depending on the length of the bus bars and the distance between the bus bars, the applied voltage must be adjusted accordingly for the first heating zone and the second heating zone in order to achieve the desired heating output per area. In cold winter weather, for example, a higher heating output per area can be selected for the first heating zone than for the second heating zone. This ensures that the electrically controllable functional element and the electrically controllable reflection element quickly reach a suitable operating temperature, while at the same time energy costs can be kept low due to the lower heating output per area in the second heating zone. This is particularly advantageous for electric cars to prevent rapid battery discharge.

[0064] The heating layer preferably contains a metal, particularly preferably silver, gold, copper, nickel and / or chromium, or a metal alloy, most preferably silver. The heating layer preferably has a surface resistance of 0.1 ohm / sq. to 6 ohm / sq., preferably of 1 ohm / sq. to 5 ohm / sq., and particularly preferably of 2 ohm / sq. to 4 ohm / sq. Layers with such surface resistances are particularly energy-efficient and are particularly suitable for heating vehicle windows with typical on-board voltages of 12 V to 48 V or in electric vehicles with typical on-board voltages of up to 500 V.

[0065] In a particularly preferred embodiment, the heating layer has infrared-reflecting properties. This makes it possible to combine the advantages of the heating layer with the advantages of an infrared-reflecting coating. Alternatively, it is also possible to use the heating layer and the infrared-reflecting layer as two separate layers. A further aspect of the invention relates to a projection arrangement comprising a composite pane according to the invention and a projector directed onto the projection area so that the radiation from the projector is reflected at the electrically controllable reflection element to generate a display image. The projector thus irradiates the electrically controllable reflection element with visible light, in particular in the wavelength range from 380 nm to 780 nm. The projector preferably faces the interior-side surface of the inner pane.It is understood that when the projector projects an image onto the electrically controllable reflection element, the electrically controllable reflection element is preferably switched to a reflective state. The projector is preferably directed at the entire projection area, but can also be directed at only a portion of the projection area. It is also possible to have multiple projectors directed at different portions of the projection area.

[0066] If the projection arrangement is part of a vehicle, the projector is preferably arranged in the vehicle's dashboard. The image projected by the projector onto the electrically controllable reflective element is reflected into the vehicle interior, for example, into the field of vision of an occupant. Due to the arrangement of the electrically controllable reflective element in front of the electrically controllable functional element, the projected image in the overlap area between the projection area and the functional area can be visually perceived with high contrast, provided the electrically controllable functional element is switched to the opaque state and the electrically controllable reflective element is switched to the transparent state. This allows the use of projectors with lower energy consumption. Compared to projectors for classic head-up displays, the projector's energy consumption can be reduced by up to 20%.

[0067] In principle, the projector can be any conceivable imaging unit suitable for projecting an image. The projector is preferably a display, preferably a liquid crystal (LCD) display, thin film transistor (TFT) display, light-emitting diode (LED) display, organic light-emitting diode (OLED) display, electroluminescent (EL) display, or microLED display. A projector designed as a display is advantageous because displays have a low installation height and can therefore be easily and space-savingly integrated into a vehicle's dashboard. Displays are also characterized by low energy consumption. The radiation from the projector preferably strikes the composite pane in the projection area at an angle of incidence of 55° to 80°, preferably 62° to 77°.

[0068] The composite pane according to the invention can be used, for example, in means of transport for land, air, or water traffic, preferably in motor vehicles, for example as a windshield, rear window, side window, and / or roof window. However, the composite pane according to the invention can also be used as a functional and / or decorative individual piece and as a built-in component in furniture, appliances, and buildings, for example as a window pane in a building.

[0069] Within the scope of the present invention, all embodiments mentioned for individual features can also be freely combined with one another, provided they are not contradictory.

[0070] The invention is explained in more detail below with reference to drawings and exemplary embodiments. The drawings are schematic representations and not to scale. The drawings do not limit the invention in any way.

[0071] They show:

[0072] Fig. 1 is a plan view of an embodiment of a composite pane according to the invention, Fig. 2 is a cross-section through the embodiment of Fig. 1,

[0073] Fig. 3 is a plan view of another embodiment of a composite pane according to the invention,

[0074] Fig. 4 shows a cross section through the embodiment of Fig. 3,

[0075] Fig. 5 is a plan view of a further embodiment of a composite pane according to the invention and

[0076] Fig. 6 shows a cross section through an embodiment of a projection arrangement according to the invention with the composite pane from Fig. 5.

[0077] Fig. 1 shows an embodiment of a composite pane 100 according to the invention. Fig. 2 shows a cross-section through the embodiment of Fig. 1 along a first section line XX'. The composite pane 100 is, for example, a windshield in a passenger car. The composite pane 100 comprises an outer pane 1 with an outside surface I facing the external environment and an interior surface II facing the vehicle interior, and an inner pane 2 with an outside surface III facing the external environment and an interior surface IV facing the vehicle interior, which are connected to one another via a thermoplastic intermediate layer 3.In this embodiment, the composite pane 100 is trapezoidal in shape and has an upper edge O facing the vehicle roof and an opposite lower edge U facing the engine compartment, which can also be referred to as the engine edge, as well as a first side edge S opposite a second side edge S', wherein the first side edge S and the second side edge S' connect the upper edge O and the lower edge U to one another. The inner pane 2 is arranged closer to the vehicle interior than the outer pane 1, and the outer pane 1 is arranged closer to the outside environment than the inner pane 2. The outer pane 1 and the inner pane 2 are made, for example, from soda-lime glass and have a thickness of 2.1 mm. The thermoplastic intermediate layer 3 is made, for example, from polyvinyl butyral (PVB) and has a thickness of 0.76 mm.The thermoplastic intermediate layer 3 preferably comprises several thermoplastic layers, with the reflective element 5 and the functional element 4 being arranged between two thermoplastic layers prior to lamination (not shown here). At least a third frame-shaped thermoplastic layer surrounds the peripheral edge surfaces of the reflective element 5 and the functional element 4. After lamination, the individual thermoplastic layers fuse to form the thermoplastic intermediate layer 3 (see Fig. 2).

[0078] The composite pane 100 also comprises an electrically controllable functional element 4, which can be switched to at least one opaque state and one transparent state, and an electrically controllable reflective element 5, which can be switched to at least one transparent state and one reflective state. The electrically controllable functional element 4 and the electrically controllable reflective element 5 can each be switched to ten different states, for example, with the further states being equidistant from one another between the two extreme states. In the case of the electrically controllable functional element 4, the two extreme states are the state with maximum transmittance and the state with minimum transmittance, and in the case of the electrically controllable reflective element, the state with maximum reflectance and the state with minimum reflectance.

[0079] The electrically controllable functional element 4 extends over a functional region F of the composite pane 100, and the electrically controllable reflection element 5 extends over a projection region P of the composite pane 100. The functional region F and the projection region P extend in a strip-like manner along an edge of the composite pane 100 and are part of an edge region of the composite pane 100 that is adjacent to the lower edge U of the composite pane 100. The electrically controllable functional element 4 is, for example, a guest host functional element that can be switched into the various states of optical transparency by applying a suitable operating voltage. The electrically controllable reflection element 5 is, for example, a liquid crystal display, i.e., an electrically controllable functional film based on liquid crystals that can be switched into the various states by applying a suitable operating voltage.

[0080] The projection area P is a sub-area of ​​the functional area F. The electrically controllable functional element 4 and the electrically controllable reflection element 5 are arranged between the outer pane 1 and the inner pane 2 and, in this embodiment, are bonded to one another via a transparent adhesive layer 6.1. The transparent adhesive layer 6.1 holds the electrically controllable functional element 4 and the electrically controllable reflection element 5 in a fixed position relative to one another. An infrared-reflecting coating 7 is applied to the interior-side surface II of the outer pane 1. The coating 7 is applied over the entire surface with the exception of a frame-shaped edge area that spaces the coating 7 from the edge of the outer pane 1. This coating-free edge area reduces the risk of corrosion, since the edge area of ​​the composite pane 100 is susceptible to moisture penetration.A black print 13 is also applied to the interior-side surface II of the outer pane 1. As is usual with windshields, the black print 13 serves to conceal the adhesive bead usually present. It also protects it from UV radiation. The infrared-reflecting coating 7 is made of silver, for example. The application of the infrared-reflecting coating 7 to the outer pane 1 is merely optional. However, the infrared-reflecting coating 7 can effectively reflect infrared radiation from the external environment, which could otherwise lead to damage to the electrically controllable functional element 4 and the electrically controllable reflective element 5. In this embodiment, the infrared-reflecting coating 7 extends over the entire composite pane 100 with the exception of the frame-shaped edge region.Alternatively, it is also possible for the infrared-reflecting coating 7 to extend only over a part of the composite pane 100, for example only over the functional area F. The infrared-reflecting coating 7 can alternatively also be applied, for example, directly to a surface of the electrically controllable functional element 4 facing the outer pane 1.

[0081] Fig. 3 shows a plan view of a further embodiment of a composite pane 100 according to the invention. Fig. 4 shows a cross-section through the embodiment from Fig. 3 along a section line YY'. The embodiment from Fig. 3 and Fig. 4 differs from the embodiment from Fig. 1 and Fig. 2 in that a heating layer 10 is applied to the interior-side surface II of the outer pane 1, which also functions as an infrared radiation-reflecting coating. The heating layer 10 is formed, for example, on a silver basis. In this embodiment, the heating layer 10 is arranged on the interior-side surface II of the outer pane 1. Alternatively, it is also possible for the heating layer 10 and an infrared-reflecting coating to be present as two separate coatings.For example, it is possible for the heating layer 10 to be arranged on the interior-side surface II of the outer pane 1 and for the infrared-reflecting coating 7 to be arranged on the exterior-side surface III of the inner pane 2. In a further alternative embodiment, the heating layer 10 is arranged only in the functional region F in order to specifically heat the electrically controllable functional element 4 and the electrically controllable reflection element 5. In addition, a first busbar 11.1 and a second busbar 11.2 are connected to the heating layer 10 and form a first heating region A of the composite pane 100. In this embodiment, the first busbar 11.1 is arranged parallel and close to the first side edge S, and the second busbar 11.2 is arranged parallel and close to the second side edge S'. Thus, the first busbar 11.1 and the second busbar 11.2 are arranged in an edge region of the composite pane 100, where they interfere with visibility through the composite pane as little as possible. The electrically controllable functional element 4 is connected to the outer pane 1 via an external adhesive layer 6.2, and the electrically controllable reflective element 5 is connected to the inner pane 2 via an interior adhesive layer 6.3. This embodiment has the advantage that the electrically controllable functional element 4 is fixed in a fixed position parallel to the outer pane 1, and that the electrically controllable reflective element 5 is fixed in a fixed position parallel to the inner pane 2.

[0082] By applying a voltage to the first bus bar 11.1 and the second bus bar 11.2, the composite pane 100 can be heated in the first heating region A. In this embodiment, the functional region F and the projection region P are subregions of the first heating region A. Since the electrically controllable functional element 4 and the electrically controllable reflection element 5 are temperature-sensitive, they can be heated in a targeted manner in this way to achieve an optimal operating temperature. In the embodiment of Fig. 3 and Fig. 4, the first bus bar 11.1 and the second bus bar 11.2 are arranged parallel to the side edges of the composite pane 100. The black print 13 present here also covers the bus bars 11.1, 11.2 in addition to the adhesive bead, thereby improving the optical quality of the composite pane 100 (not shown in Figures 5 and 3 in order to clearly show the bus bars 11.1, 11.2, 12.1, 12.2).

[0083] Fig. 5 shows a plan view of another embodiment of a composite pane 100 according to the invention. This embodiment differs from the embodiment of Fig. 3 and Fig. 4 in that a third busbar 12.1 and a fourth busbar 12.2 are connected to the heating layer 10, wherein the third busbar 12.1 and the fourth busbar 12.2 form a second heating region B. In this embodiment, the second heating region B coincides with most of the view-through area of ​​the windshield. The third busbar 12.1 and the fourth busbar 12.2 are arranged in the lateral edge regions of the composite pane 100. This embodiment makes it possible to heat the first heating region A and the second heating region B separately.In this way, for example, the first heating area A can be heated more strongly than the second heating area B when the vehicle is started in order to quickly establish a suitable operating temperature for the electrically controllable functional element 4 and the electrically controllable reflection element 5 and at the same time keep energy consumption low.

[0084] Fig. 6 shows a cross-section through an embodiment of a projection arrangement according to the invention. The projection arrangement comprises the composite pane 100 from the embodiment of Fig. 5. Shown is a cross-section through the composite pane 100 along a section line ZZ'. In contrast to the embodiment of Figs. 3 and 4, the electrically controllable functional element 4 and the electrically controllable reflection element 5 are connected to one another via an adhesive layer 6.1 and embedded within the thermoplastic intermediate layer 3, instead of being connected to the outer pane 1 and the inner pane 2 via the outer-side adhesive layer 6.2 and the inner-side adhesive layer 6.3. The radiation of the projector 8 is reflected by the electrically controllable reflection element 5 to generate a display image. The projector 8 is, for example, a light-emitting diode display (LED display). The display image is viewed by the observer 9.To operate the projection arrangement, the electrically controllable reflection element 5 is, for example, switched to a reflective state. The electrically controllable functional element 4 is preferably switched to an opaque state to operate the projection arrangement in order to create a contrast with the display image. In this state, the projection arrangement enables information to be presented in the projection area P, for example the driving speed, the time of day, the engine speed, the navigation system display, information on speed limits (traffic sign recognition), the image from a rear-facing camera, and various status displays on the state of the vehicle. Alternatively, the electrically controllable functional element 4 can also be switched to a transparent state to operate the projection arrangement in order to enable a view through the composite pane 100 during operation of the projection arrangement. List of reference symbols.

[0085] (100) Composite pane

[0086] (1) Outer pane

[0087] (2) Inner pane

[0088] (3) thermoplastic intermediate layer

[0089] (4) electrically controllable functional element

[0090] (5) electrically controllable reflection element

[0091] (6.1) Adhesive layer

[0092] (6.2) external adhesive layer

[0093] (6.3) interior adhesive layer

[0094] (7) infrared-reflecting coating

[0095] (8) Projector

[0096] (9) Observer

[0097] (10) Heating layer

[0098] (11.1) first collection manager

[0099] (11.2) second collection manager

[0100] (12.1) third collection manager

[0101] (12.2) fourth collection manager

[0102] (13) Black printing

[0103] (A) first heating area

[0104] (B) second heating area

[0105] (F) Functional area

[0106] (P) Projection area

[0107] (U) Bottom edge of the laminated pane 100

[0108] (O) Upper edge of the laminated pane 100

[0109] (S) first side edge of the laminated pane 100

[0110] (S') second side edge of the composite pane 100

[0111] (I) outside surface of the outer pane 1

[0112] (11) interior surface of the outer pane 1

[0113] (III) outer surface of the inner pane 2

[0114] (IV) interior surface of the inner pane 2 (XX') first cutting line (YY') second cutting line

[0115] (ZZ') third cutting line

Claims

Patent claims 1. A composite pane (100) for a projection arrangement, comprising an outer pane (1) and an inner pane (2) which are connected to one another via a thermoplastic intermediate layer (3), an electrically controllable functional element (4) which can be switched to at least one opaque state and one transparent state, and an electrically controllable reflection element (5) which can be switched to at least one transparent state and one reflective state, wherein the electrically controllable functional element (4) extends over a functional region (F) of the composite pane (100) and the electrically controllable reflection element (5) extends over a projection region (P) of the composite pane (100), wherein the projection region (P) at least partially coincides with the functional region (F), and the electrically controllable reflection element (5) when viewed through the composite pane (100),looking from the inner pane (2) to the outer pane (1), is arranged in front of the electrically controllable functional element (4).

2. Composite pane (100) according to claim 1, wherein the projection area (P) is a partial area of the functional area (F) or is identical to the functional area (F).

3. Composite pane (100) according to claim 1 or 2, wherein the electrically controllable functional element (4) and the electrically controllable reflection element (5) are connected to one another in a planar manner via an adhesive layer (6.1).

4. Composite pane (100) according to one of claims 1 to 3, wherein the electrically controllable functional element (4) is a guest host functional element, electrochromic functional element or a dimmable PDLC functional element.

5. Composite pane (100) according to one of claims 1 to 4, wherein the electrically controllable reflection element (5) is a mirrorable liquid crystal display or an electrochemically switchable mirror.

6. Composite pane (100) according to one of claims 1 to 5, wherein the electrically controllable functional element (4) and the electrically controllable reflection element (5) are arranged between the outer pane (1) and the inner pane (2).

7. Composite pane (100) according to one of claims 1 to 6, comprising an infrared-reflecting coating (7) which extends at least over the functional area (F) and, when viewed through the composite pane (100), from the inner pane (2) to the outer pane (1), is arranged behind the electrically controllable functional element (4).

8. Composite pane (100) according to claim 7, wherein the infrared-reflecting coating (7) is applied to an interior-side surface (II) of the outer pane (1) facing the thermoplastic intermediate layer (3).

9. Composite pane (100) according to claim 7, wherein the infrared-reflecting coating (7) is applied to a surface of the electrically controllable functional element (4) facing the outer pane (1).

10. Composite pane (100) according to one of claims 1 to 9, wherein the electrically controllable functional element (4) in the opaque state has a transmittance for visible light of a maximum of 30%, preferably a maximum of 20%, particularly preferably a maximum of 10%.

11. Composite pane (100) according to one of claims 1 to 10, wherein the electrically controllable reflection element (5) in the reflective state has a reflectance for visible light of at least 20%, preferably at least 40%, particularly preferably at least 50%.

12. Composite pane (100) according to one of claims 1 to 11, comprising a heating layer (10) which extends at least over the functional area (F).

13. Composite pane (100) according to claim 12, wherein the heating layer (10) extends at least over a first heating region (A) of the composite pane (100) and the functional region (F) is a partial region of the first heating region (A) or the functional region (F) is identical to the first heating region (A) and wherein the heating layer (10) is connected to at least a first bus bar (11.1) and a second bus bar (11.2) in such a way that when an electrical voltage is applied to the first bus bar (11.1) and the second bus bar (11.2), a heating current flows through the heating layer (10) in the first heating region (A).

14. Composite pane (100) according to claim 13, wherein the heating layer (10) further extends over a second heating region (B) of the composite pane (100), wherein the heating layer (10) is connected to a third bus bar (12.1) and a fourth bus bar (12.2) in such a way that when an electrical voltage is applied to the third bus bar (12.1) and the fourth bus bar (12.2), a heating current flows through the heating layer (10) in the second heating region (B).

15. Projection arrangement comprising a composite pane (100) according to one of claims 1 to 14 and - a projector (8) directed onto the projection area (P) so that the radiation of the projector (8) is reflected on the electrically controllable reflection element (5) to generate a display image:

Images