FUNCTIONAL ELEMENT WITH ELECTRICALLY CONTROLLED OPTICAL PROPERTIES

Description

[0001] The invention relates to a functional element with electrically controllable optical properties, a method for step-like switching of the functional element and a composite pane comprising such a functional element.

[0002] To protect the driver and other passengers from glare, conventional motor vehicles are equipped with mechanical sun visors. These are mounted on the vehicle roof in a foldable or sliding manner and can be folded down or closed as needed to prevent or at least reduce the glare for the driver or passenger.

[0003] Windshields and roof windows are also known that incorporate a sun visor in the form of a functional element with electrically adjustable optical properties, particularly with electrically adjustable transmission or scattering behavior. This allows the driver to control the transmission behavior of the glazing with regard to solar radiation, making conventional mechanical sun visors unnecessary. This reduces the weight of the vehicle and frees up space in the roof area. In addition, electrically adjusting the sun visor is more convenient for the driver. Particularly with large panoramic glass windows in the roof area, there is a need to variably control the transmission of the window. Depending on the position of the sun, it may be necessary to dim only parts of the window or to make the entire surface opaque to provide privacy when the vehicle is parked.

[0004] Possible electrically switchable functional elements for the realization of adjustable sun visors are electrochromic functional elements, PDLC functional elements ( polymer dispersed liquid crystal ) , SPD functional elements ( suspended particle device ) and electroluminescent functional elements. The mode of operation of such functional elements is known to those skilled in the art. The functional elements mentioned generally comprise two carrier films, on each of which a surface electrode is arranged, with an active layer being introduced between the carrier films directly adjacent to the surface electrodes. The optical properties of the active layer change depending on the electrical voltage applied to the surface electrodes. In order to achieve a gradual or section-by-section change in the optical properties, a locally or section-by-section different voltage must be applied to the surface electrodes, i.e. the electrical contact must be adapted accordingly.

[0005] Electrical contacting of electrically controllable functional elements is typically achieved via bus bars, which are applied to the surface electrodes at the edge of the functional element and provide electrical contact. By connecting the bus bars to an external voltage source, for example, via flat conductors attached to the bus bars, a voltage is applied to the surface electrodes and the active layer of the functional element is switched. The smaller the area of the individually electrically controllable areas, the more complex and detailed the electrical contacting becomes.

[0006] EP 2416385 A1 relates to a multilayer back contact foil and a method for connecting solar cells by means of the same.

[0007] EP 1840449 A1 describes a light panel comprising a glass substrate, an electrically conductive coating and a plurality of LEDs, wherein the LEDs are electrically contacted via conductor tracks in the electrically conductive coating and two bus bars are arranged on the same edge of the light panel.

[0008] WO 2020 / 083563 A1 and WO 2020 / 083562 A1 disclose composite panes with segment-like switchable electrically controllable functional elements with a first group of busbars that electrically contact the segments introduced into the first surface electrode and at least one second busbar that electrically contact the second surface electrode.

[0009] The present invention is based on the object of providing a switchable functional element with electrically controllable optical properties, which has an improved electrical control with step-wise switchability.

[0010] The object of the present invention is achieved by a functional element with electrically controllable optical properties according to independent claim 1. Preferred embodiments emerge from the subclaims.

[0011] The functional element according to the invention comprises an active layer between a first surface electrode and a second surface electrode. The active layer has adjustable optical properties that can be controlled via the voltage applied to the surface electrodes. The surface electrodes are applied to carrier films. The surface electrodes, the active layer, and the carrier films are typically arranged substantially parallel to one another. The surface electrodes are electrically conductively connected to bus bars, via which the functional element can be connected to an external voltage source. The active layer is arranged flatly between the first surface electrode and the second surface electrode. The functional element comprises a plurality of side edges, with a first bus bar and a second bus bar being arranged on at least one first side edge.The first bus bar makes electrically conductive contact with the first surface electrode, while the second bus bar makes electrically conductive contact with the second surface electrode. The first carrier film comprises at least one first cutout, within which the material of the first carrier film with the first surface electrode located thereon has been removed. The second bus bar is attached to the surface of the first carrier film facing away from the active layer and the first surface electrode. The second bus bar passes through the first cutout and electrically contacts the second surface electrode in this area. There is no active layer in the area of the first cutout, and the second bus bar is directly electrically contacted with the second surface electrode. The first bus bar runs on the surface of the second carrier film facing away from the active layer and the second surface electrode.The second carrier film comprises at least one second cutout within which the material of the second carrier film and the second surface electrode located thereon has been removed. The first bus bar extends through the second carrier film in the region of the second cutout and makes electrical contact with the first surface electrode. There is no active layer in the region of the second cutout and the first bus bar is directly electrically contacted with the first surface electrode in this region. At least one of the bus bar is divided into at least a first section and at least a second section. Thus, the first bus bar is divided into at least a first section and at least a second section and / or the second bus bar is divided into at least a first section and at least a second section. The sections of the first bus bar can be controlled independently of one another.The same applies to the sections of the second bus bar.

[0012] Preferably, adjacent sections of a bus bar are separated from one another by dividing lines, with the electrical conductivity of an insulator present in the region of the dividing lines and no electrical current flowing between adjacent sections of the bus bar. In this way, specific areas of the functional element can be controlled. The bus bars can be initially applied along at least one side edge and then divided into at least two sections, eliminating the need to apply the sections individually.

[0013] The functional element according to the invention enables simplified electrical contacting of the surface electrodes in the edge region. The bus bars are applied to the surfaces of the carrier foils facing away from the surface electrodes and penetrate the nearest carrier foil locally in the area of the recesses in order to be electrically contacted on the surface electrode located further away from the respective bus bar. In this way, the first bus bars and the second bus bars can be attached together to a first side edge. This reduces the number of side edges where contact must be made.

[0014] The division of one or both bus bars into electrically separated sections enables the active layer to be selectively switched section by section, with the selectively switchable regions of the active layer lying within the regions of the surface electrodes in which a voltage is applied via the bus bars. For the targeted control of individual regions of the functional element, the opposing poles of a voltage source are connected to the respective sections of the bus bars of the first surface electrode and the second surface electrode, depending on the desired circuit pattern of the active layer. A first pole of the voltage source is connected to sections of the second bus bars, while the opposite pole of the voltage source is connected to sections of the first bus bars that are contacted in the region of the regions of the first surface electrode to be controlled.An electrical potential difference between the surface electrodes therefore only exists in those areas of the functional element where the corresponding areas of the first surface electrode are connected to the voltage source. Accordingly, the active layer of the functional element is only switched in these areas. The targeted control of the segments of the first surface electrode to which a voltage is to be applied is achieved, for example, via an external control unit.

[0015] The first recesses and the second recesses are arranged alternately with one another. Thus, there is at least one first recess and at least two second recesses, or at least two first recesses and at least one second recess, to ensure an alternating arrangement along the first side edge. Preferably, there are at least two first recesses and at least two second recesses, which are arranged alternately with one another along the first side edge. An alternating arrangement of the recesses enables targeted control of all surface areas of the functional element, with the precision thereof increasing with the increasing number of first and second recesses.

[0016] The functional element has a plurality of side edges, particularly preferably four side edges. However, the functional element can also comprise more than four side edges. At least two side edges of the functional element are essentially opposite one another in pairs. In an embodiment with four side edges, this results in two pairs of two opposite side edges each. The opposite side edges of a functional element can run parallel to one another or not parallel to one another. The side edges do not have to be straight, but often have a bend. The length of opposite side edges can differ from one another. For example, the functional element can have a trapezoidal outline. In a preferred embodiment, the functional element has a plurality of side edges, for example four side edges.

[0017] In a preferred embodiment of the functional element, at least one further first bus bar and / or second bus bar is arranged at least on a second side edge. At least one further bus bar results in a more uniform voltage distribution, so that the switching process of the functional element is improved. To ensure a homogeneous voltage distribution, bus bars are arranged in particular on opposite side edges of the functional element. Particularly preferably, a first bus bar and a second bus bar are arranged on at least one second side edge, with the bus bars being contacted with the associated surface electrode via first recesses and second recesses.The first and second recesses are arranged along the second side edge analogously to the described possible arrangements on the first side edge, wherein within a functional element the arrangement on the first side edge can differ from the arrangement on the second side edge.

[0018] The invention allows a first bus bar and a second bus bar to be mounted together on one side edge of the functional element. This allows other side edges of the functional element to be kept free of bus bars if necessary. This is advantageous, for example, if the functional element does not extend over the entire surface of the glazing and one edge of the functional element lies within the view-through area of the glazing. A second bus bar is omitted from this side edge for the sake of an attractive appearance.

[0019] Preferably, the functional element has a first bus bar and a second bus bar along each of the first side edge, the second side edge, the third side edge, and the fourth side edge. In this way, the most homogeneous switching behavior possible can be achieved in all areas of the functional element when switched simultaneously. On the other hand, a stepwise switching of the functional element allows for very precise control of individual areas.

[0020] In one possible embodiment, the first surface electrode and / or the second surface electrode comprise at least one dividing line that divides the functional element into independently switchable regions, also called segments. The dividing line can also be referred to as an insulation line and effects an electrical separation of the individual segments of the surface electrode from one another. In the sense of the invention, a dividing line is understood to be a linear region within a surface electrode which is not electrically conductive and which extends over the entire thickness of the surface electrode. A dividing line between the individual segments of a surface electrode ensures that no current flows via any segment of the coating other than the controlled segment. The width of the segments of a surface electrode is defined by the distance between one or more dividing lines that limit the width of the segment.The width of a segment is measured along the direction in which the shortest corresponding section of the busbar runs.

[0021] The at least one dividing line preferably runs in a straight, wavy, or meandering manner between two opposite side edges of the functional element. However, other cutting patterns with one or more dividing lines are also conceivable.

[0022] The segments of the surface electrodes are preferably arranged substantially parallel to one another, wherein the segments extend continuously from one side edge of the functional element to an opposite side edge.

[0023] The number of segments within the surface electrodes can vary depending on the application of the glazing and is usually between 2 and 20, preferably between 3 and 10.

[0024] The electrical connection of the bus bars to an external power source is achieved by suitable connecting cables, such as foil conductors. Suitable external control elements for controlling the individual segments are known to those skilled in the art.

[0025] The electrical control of the functional element is achieved, for example, using buttons, rotary controls, or sliders, which are integrated, for example, into the instrument panel of a vehicle. However, a control button, such as a capacitive button, can also be integrated into the composite pane. Alternatively, the functional element can also be controlled using contactless methods, such as by recognizing gestures, or based on the state of the pupil or eyelid, as determined by a camera and suitable evaluation electronics.

[0026] The at least one separating line is incorporated into the surface electrodes in such a way that the segments of the surface electrode are electrically insulated from one another. The individual segments are connected to the voltage source independently of one another via the individual sections of the busbars, so that they can be controlled separately. This allows different areas of the functional element to be switched independently. Particularly preferably, the segments are arranged horizontally in the installed position. This allows the height of the non-transparent area of the functional element to be controlled by the user. The term "horizontal" is to be interpreted broadly here and refers to a propagation direction that runs between the side edges of the laminated pane, for example, the side edges of a windshield or a roof pane.The dividing lines don't necessarily have to be straight, but can also be slightly curved, preferably adapted to any curvature of the nearest window edge, especially essentially parallel to the front roof edge of a windshield. Vertical insulation lines are also conceivable.

[0027] The dividing lines have a width of, for example, 5 µm to 500 µm, in particular 20 µm to 200 µm. The width of the segments, i.e., the spacing between adjacent dividing lines, can be selected by the person skilled in the art according to the requirements of the individual case.

[0028] The separation lines can be introduced by laser ablation, mechanical cutting, or etching during the manufacturing of the functional element. Already laminated multilayer films can also be subsequently segmented using laser ablation.

[0029] The bus bars are connected to the surface electrodes, for example, as strips of an electrically conductive material or electrically conductive prints. The bus bars are preferably designed as electrically conductive prints comprising silver.

[0030] The functional element can be embodied as a PDLC element, an SPD functional element, an electrochromic element, or an electroluminescent element, whereby the composition of the active layer differs depending on the type of functional element. The aforementioned functional elements and their structure are known to those skilled in the art.

[0031] Preferably, the functional element is an electrochromic functional element and the active layer is thus an electrochromic layer. The active layer of an electrochromic functional element is an electrochemically active layer. The transmission of visible light depends on the degree of ion incorporation into the active layer, with the ions being provided, for example, by an ion storage layer between the active layer and a surface electrode. The transmission can be influenced by the voltage applied to the surface electrodes, which causes the ions to migrate. Suitable functional layers contain, for example, at least tungsten oxide or vanadium oxide. Electrochromic functional elements are known, for example, from WO 2012007334 A1, US 20120026573 A1, WO 2010147494 A1 and EP 1862849 A1.

[0032] In a further embodiment, the functional element is a PDLC functional element ( polymer dispersed liquid crystal ) .The active layer of a PDLC functional element contains liquid crystals embedded in a polymer matrix. If no voltage is applied to the surface electrodes, the liquid crystals are randomly aligned, which leads to strong scattering of the light passing through the active layer. If a voltage is applied to the surface electrodes, the liquid crystals align in a common direction, and the light transmission through the active layer is increased. Such a functional element is known, for example, from DE 102008026339 A1.

[0033] In a further embodiment, the functional element is an SPD functional element ( suspended particle device). This contains an active layer comprising suspended particles, wherein the absorption of light by the active layer can be changed by applying a voltage to the surface electrodes. The change in absorption is based on the alignment of the rod-like particles in the electric field when an electrical voltage is applied. SPD functional elements are known, for example, from EP 0876608 B1 and WO 2011033313 A1.

[0034] In the case of an electroluminescent functional element, the active layer contains electroluminescent materials, particularly organic electroluminescent materials, whose luminescence is stimulated by applying a voltage. Electroluminescent functional elements are known, for example, from US 2004227462 A1 and WO 2010112789 A2. The electroluminescent functional element can be used as a simple light source or as a display with which any desired image can be shown.

[0035] The first bus bars and the second bus bars comprise an electrically conductive structure, preferably containing silver, and have a thickness of 5 µm to 40 µm.

[0036] The bus bars are designed to be connected to an external voltage source so that an electrical potential difference exists between the first surface electrode and the second surface electrode.

[0037] The bus bars can be attached in particular by laying on, printing on, soldering or gluing.

[0038] In a preferred embodiment, the bus bars are formed as a printed and fired-in conductive structure. The printed bus bars contain at least one metal, preferably silver. The electrical conductivity is preferably achieved via metal particles contained in the bus bar, particularly preferably via silver particles. The metal particles can be located in an organic and / or inorganic matrix such as pastes or inks, preferably as a fired screen printing paste with glass frits. The layer thickness of the printed bus bars is preferably from 5 µm to 40 µm, particularly preferably from 8 µm to 20 µm, and most preferably from 10 µm to 15 µm. Printed bus bars with these thicknesses are technically simple to implement and have an advantageous current-carrying capacity.

[0039] Alternatively, the bus bars are formed as strips of electrically conductive foil. The current bus bars then contain, for example, at least aluminum, copper, tinned copper, gold, silver, zinc, tungsten and / or tin or alloys thereof. The strip preferably has a thickness of 10 µm to 500 µm, particularly preferably 30 µm to 300 µm. Bus bars made of electrically conductive foils with these thicknesses are technically simple to produce and have advantageous current-carrying capacity. The strip can be electrically conductively connected to the surface electrode, for example via a solder compound, an electrically conductive adhesive or an electrically conductive adhesive tape, or by direct application. To improve the conductive connection, a silver-containing paste, for example, can be arranged between the surface electrode and the bus bar.

[0040] The first surface electrode and the second surface electrode are each formed by an electrically conductive layer. These electrically conductive layers contain at least one metal, a metal alloy, or a transparent conductive oxide, preferably a transparent conductive oxide, and have a thickness of 10 nm to 2 µm. The surface electrodes are preferably transparent. Transparent here means permeable to electromagnetic radiation, preferably electromagnetic radiation with a wavelength of 300 nm to 1,300 nm, and in particular to visible light. Electrically conductive layers according to the invention are known, for example, from DE 20 2008 017 611 U1, EP 0 847 965 B1, or WO2012 / 052315 A1. They typically contain one or more, for example, two, three, or four electrically conductive, functional individual layers.The functional individual layers preferably contain at least one metal, for example silver, gold, copper, nickel and / or chromium, or a metal alloy. The functional individual layers particularly preferably contain at least 90 wt.% of the metal, in particular at least 99.9 wt.% of the metal. The functional individual layers can consist of the metal or the metal alloy. The functional individual layers particularly preferably contain silver or a silver-containing alloy. Such functional individual layers have particularly advantageous electrical conductivity with simultaneous high transmission in the visible spectral range. The thickness of a functional individual layer is preferably from 5 nm to 50 nm, particularly preferably from 8 nm to 25 nm. In this thickness range, advantageously high transmission in the visible spectral range and particularly advantageous electrical conductivity are achieved.

[0041] In principle, the surface electrodes can be formed by any electrically conductive layer that can be electrically contacted.

[0042] The functional element is preferably provided as a multilayer film with two outer carrier films. In such a multilayer film, the surface electrodes and the active layer are arranged between the two carrier films. By outer carrier film, we mean that the carrier films form the two surfaces of the multilayer film. The functional element can thus be provided as a laminated film that can be advantageously processed. The functional element is advantageously protected from damage, in particular corrosion, by the carrier films. The multilayer film contains, in the specified order, at least a first carrier film, a first surface electrode, an active layer, a second surface electrode, and a second carrier film.

[0043] The first carrier film and / or the second carrier film preferably contain at least one polymer that does not completely melt in the autoclave process, preferably polyethylene terephthalate (PET). The first and second carrier films particularly preferably consist of a PET film. This is particularly advantageous with regard to the stability of the multilayer film. However, the carrier films can also contain, for example, ethylene vinyl acetate (EVA) and / or polyvinyl butyral (PVB), polypropylene, polycarbonate, polymethyl methacrylate, polyacrylate, polyvinyl chloride, polyacetate resin, casting resins, acrylates, fluorinated ethylene propylenes, polyvinyl fluoride and / or ethylene tetrafluoroethylene. The thickness of each carrier film is preferably from 0.1 mm to 1 mm, particularly preferably from 0.1 mm to 0.2 mm. The carrier films according to the invention are preferably transparent.The surface electrodes are preferably arranged on a surface of the carrier film, i.e., on exactly one of the two sides of the carrier film (i.e., on its front side or its back side). The carrier films are aligned in the layer stack of the multilayer film such that the surface electrodes are arranged adjacent to the active layer.

[0044] For the purposes of the invention, electrically controllable optical properties are understood to mean properties that are continuously controllable, but equally also those that can be switched between two or more discrete states.

[0045] In addition to the active layer and the surface electrodes, the functional element can of course have other known layers, for example barrier layers, blocking layers, anti-reflection layers, protective layers and / or smoothing layers.

[0046] Functional elements in the form of multilayer films are commercially available. The functional element is typically cut from a larger multilayer film in the desired shape and size. This can be done mechanically, for example, with a knife. In an advantageous embodiment, the cutting is done using a laser. It has been shown that the side edge is more stable in this case than with mechanical cutting. With mechanically cut side edges, there is a risk of the material shrinking, which is visually noticeable and adversely affects the aesthetics of the pane.

[0047] In an advantageous embodiment, the functional element has an edge seal. The edge seal covers the entire side edge of the functional element and, in particular, prevents the diffusion of chemical components of the thermoplastic intermediate layer, such as plasticizers, into the active layer. At least along the lower edge of the functional element, which is visible in windshields, and preferably along all side edges, the edge seal is formed by a transparent, colorless adhesive or a transparent, colorless adhesive tape. For example, acrylic- or silicone-based adhesive tapes can be used as edge seals. The transparent, colorless edge seal has the advantage that the edge of the functional element is not disruptively noticeable when viewed through. Such an edge seal is preferably also used for invisible side edges.

[0048] The invention further relates to a composite pane comprising at least one functional element according to the invention, a thermoplastic intermediate layer, a first pane, and a second pane. The thermoplastic intermediate layer comprises a first thermoplastic composite film arranged between the functional element and the first pane, and a second thermoplastic composite film arranged between the functional element and the second pane. In this way, the functional element can be securely integrated into the composite pane via the thermoplastic intermediate layer.

[0049] The first pane and the second pane of the composite pane according to the invention represent the inner pane and the outer pane when the composite pane is installed in a motor vehicle or in a building.

[0050] The functional element is integrated via the intermediate layer between the first pane and the second pane of the composite pane. The intermediate layer comprises a first thermoplastic composite film that connects the functional element to the first pane, and a second thermoplastic composite film that connects the functional element to the second pane. Typically, the intermediate layer is formed by at least the first and second thermoplastic composite films, which are arranged flat on top of one another and laminated together, with the functional element being inserted between the two layers. The areas of the composite films that overlap with the functional element then form the areas that connect the functional element to the panes.In other areas of the pane, where the thermoplastic composite films are in direct contact with each other, they may fuse during lamination to such an extent that the two original layers may no longer be recognizable and a homogeneous intermediate layer is present instead.

[0051] A thermoplastic composite film can, for example, be formed from a single thermoplastic film. A thermoplastic composite film can also be formed from sections of different thermoplastic films whose side edges are joined together. In addition to a first thermoplastic composite film or a second thermoplastic composite film, further thermoplastic composite films can also be present. These can also be used, if necessary, to embed additional films comprising functional layers, for example, infrared-reflecting layers or acoustically dampening layers.

[0052] The thermoplastic composite films can also contain tinted or colored areas. Such films are obtainable, for example, by coextrusion. Alternatively, an untinted film section and a tinted or colored film section can be combined to form a thermoplastic composite film. The tinted or colored area can be homogeneously colored or tinted, i.e., have a location-independent transmission. However, the tint or coloring can also be inhomogeneous; in particular, a transmission gradient can be realized.

[0053] In one possible embodiment, the laminated pane is a windshield of a motor vehicle. The windshield comprises an upper edge and a lower edge as well as two side edges running between the upper edge and the lower edge. The upper edge refers to the edge which is intended to point upwards towards the vehicle roof in the installed position. The upper edge is usually referred to as the roof edge or front roof edge. The lower edge refers to the edge which is intended to point downwards towards the vehicle's hood in the installed position. The lower edge is generally referred to as the engine edge.

[0054] Windshields have a central field of vision, the optical quality of which is subject to stringent requirements. This central field of vision must exhibit high light transmission (typically greater than 70%). This central field of vision is specifically the field of vision referred to by experts as field of vision B, field of vision B, or zone B. Field of vision B and its technical requirements are defined in Regulation No. 43 of the Economic Commission for Europe of the United Nations (UN / ECE) (ECE-R43, "Uniform Provisions Concerning the Approval of Safety Glazing Materials and Their Installation on Vehicles"). Field of vision B is defined in Annex 18.

[0055] In one possible embodiment of the windshield, the functional element represents a sun visor and is arranged above the central field of vision (field of vision B). This means that the functional element is arranged in the area between the central field of vision and the front roof edge of the windshield. The functional element does not have to cover the entire area, but is positioned entirely within this area and does not protrude into the central field of vision. In other words, the functional element is closer to the upper edge of the windshield than the central field of vision. Thus, the transmission of the central field of vision is not impaired by the functional element, which is positioned in a similar position to a classic mechanical sun visor when folded down.

[0056] The interlayer in the central field of vision of the windshield is clear and transparent. This ensures that visibility through the central field of vision is not restricted, allowing the windshield to be used as a windshield. A transparent thermoplastic interlayer is defined as a layer with a light transmission in the visible spectral range of at least 70%, preferably at least 80%. The transparent interlayer is present at least in field of vision A, and preferably also in field of vision B, according to ECE-R43.

[0057] The windshield is preferably intended for a motor vehicle, particularly preferably for a passenger car.

[0058] In one possible embodiment, a region of the thermoplastic intermediate layer, via which the functional element is connected to the outer pane or the inner pane, is tinted or colored. The transmission of this region in the visible spectral range is thus reduced compared to a non-tinted or tinted layer. The tinted / tinted region of the thermoplastic intermediate layer thus reduces the transmission of the windshield in the area of the sun visor. In particular, the aesthetic impression of the functional element is improved because the tint results in a more neutral appearance that is more pleasant to the observer.

[0059] In a further preferred embodiment of the composite pane according to the invention, it is used as a roof pane of a motor vehicle. The roof pane comprises a front roof edge adjacent to the vehicle's windshield, a rear roof edge facing the rear window, and two side edges running along the vehicle doors between the front and rear roof edges. The functional element is designed as a large-area shading element for the roof pane, with the functional element being arranged over an area of at least 80% of the entire viewable area of the roof pane, preferably at least 90%, for example 100%, of the entire viewable area.

[0060] The busbars located at the edges of the composite pane used as a roof pane or windshield are concealed by the opaque masking print typically used in the edge area of the pane. If the functional element is used as a sun visor in a windshield, the edge of the functional element adjacent to the view-through area of the windshield generally remains free of masking print.

[0061] In a preferred embodiment, the functional element, or more precisely the side edges of the functional element, is surrounded all around by a thermoplastic frame film. The frame film is frame-like with a recess into which the functional element is inserted. The thermoplastic frame film can be formed by a thermoplastic film into which the recess has been cut out. Alternatively, the thermoplastic frame film can also be composed of several film sections around the functional element. In a preferred embodiment, the intermediate layer is thus formed from a total of at least three thermoplastic composite films arranged flat on top of one another, with the frame film having a recess as the middle layer in which the functional element is arranged.During production, the thermoplastic frame film is positioned between the first and second thermoplastic composite films, with the side edges of all thermoplastic films preferably overlapping. The thermoplastic frame film preferably has approximately the same thickness as the functional element. This compensates for the local thickness difference of the composite pane, which is introduced by the locally limited functional element, thus preventing glass breakage during lamination. If the functional element is incorporated into the composite pane over a large area, a frame film can be omitted.

[0062] The side edges of the functional element visible through the laminated glass are preferably arranged flush with the thermoplastic frame film, so that there is no gap between the side edge of the functional element and the associated side edge of the thermoplastic frame film. This applies in particular to the lower edge of a functional element such as a sun visor on a windshield, where this edge is typically visible. This makes the boundary between the thermoplastic frame film and the functional element visually less noticeable.

[0063] Automotive glazing, particularly windshields, rear windows, and roof windows, usually has a peripheral masking print made of opaque enamel, which serves in particular to protect the adhesive used to install the pane from UV radiation and to visually conceal it. This peripheral masking print is preferably used to also conceal the edges of the functional element located in the edge region of the glazing. The bus bars and the necessary electrical connections are also attached in the area of the masking print. In this way, the functional element is advantageously integrated into the appearance of the composite pane. Preferably, at least the pane used as the outer pane has such a masking print; particularly preferably, both the first pane and the second pane (inner pane and outer pane) are printed, so that visibility from both sides is prevented.

[0064] The functional element may also have recesses or holes, for example, in the area of so-called sensor windows or camera windows. These areas are intended for the installation of sensors or cameras whose functionality would be impaired by an adjustable functional element in the beam path, such as rain sensors.

[0065] The functional element is preferably arranged across the entire width of the composite pane, minus a border area on both sides with a width of, for example, 2 mm to 20 mm. The functional element is also preferably spaced from the upper edge by, for example, 2 mm to 20 mm. The functional element is thus encapsulated within the intermediate layer and protected from contact with the surrounding atmosphere and corrosion.

[0066] The first thermoplastic composite film and the second thermoplastic composite film and optionally also the thermoplastic frame film preferably contain at least polyvinyl butyral (PVB), ethylene vinyl acetate (EVA) and / or polyurethane (PU), particularly preferably PVB.

[0067] The thickness of each thermoplastic composite film and the frame film is preferably from 0.2 mm to 2 mm, particularly preferably from 0.3 mm to 1 mm, in particular from 0.3 mm to 0.5 mm, for example 0.38 mm.

[0068] The first pane and the second pane are preferably made of glass, particularly preferably soda-lime glass, as is common for window panes. However, the panes can also be made of other types of glass, such as quartz glass, borosilicate glass, or aluminosilicate glass, or of rigid, clear plastics, such as polycarbonate or polymethyl methacrylate. The panes can be clear, tinted, or colored. If the laminated pane is used as a windshield, it should have sufficient light transmission in the central viewing area, preferably at least 70% in the main viewing area A according to ECE-R43.

[0069] The firstThe pane, the second pane and / or the intermediate layer may have further suitable coatings known per se, for example anti-reflective coatings, non-stick coatings, anti-scratch coatings, photocatalytic coatings or sun protection coatings or low-E coatings.

[0070] The thickness of the first and second panes can vary widely and thus be adapted to the requirements of the individual case. The first and second panes preferably have thicknesses of 0.5 mm to 5 mm, particularly preferably 1 mm to 3 mm.

[0071] The invention also comprises a method for switching a functional element according to the invention, wherein a first electrical voltage U 1 is applied at least between a first section of the first bus bar and a first section of the second bus bar. The first electrical voltage U 1 corresponds to the switching voltage of the functional element, i.e. the voltage at which the functional element completely switches to the active state. A complete transition to the active state can be recognized by the fact that no further change in the optical properties of the functional element occurs when the applied voltage is further increased. A second electrical voltage U 2 , the magnitude of which is lower than the magnitude of the voltage U 1 , is applied between a second section of the first bus bar and a second section of the second bus bar.Thus, in a second region of the functional element, which is assigned to the second section of the first bus bar and the second section of the second bus bar, no complete transition to the active state occurs. In contrast, in the first region of the functional element, which is assigned to the first section of the first bus bar and the first section of the second bus bar, a complete transition to the active state occurs. The first region in the active state thus borders on the second region in the partially activated state, creating a visually appealing progression of the optically controllable properties of the functional element.

[0072] Preferably, a third region of the functional element, which is contacted by a third section of the first busbar and a third section of the second busbar, borders the second region of the functional element, which is assigned to the second section of the first busbar and the second section of the second busbar. to these If no voltage is applied to the third area, the second area in the partially activated state forms a visually appealing transition between the fully activated first area and the inactive third area.

[0073] In a preferred embodiment of the method, the second electrical voltage U 2 is increased to the magnitude of the first electrical voltage U 1 after a variably definable period of time, whereby the second region is also fully activated. Particularly preferably, thereafter or simultaneously, a third voltage U 3 is applied between a third section of the first busbar and a third section of the second busbar, the magnitude of which is lower than the magnitude of the voltage U 1 . In a third region of the functional element in which the voltage U 3 is applied, a partial switching process of the functional element thus also takes place. For the observer of the functional element, the switching process appears as a wave-like propagation of the active region of the functional element.

[0074] Particularly preferably, the method according to the invention for switching the functional element according to the invention comprises the following steps: a) a first electrical voltage U 1 is applied between an n-th section of the first bus bar and an n-th section of the second bus bar, which corresponds to the switching voltage of the functional element, b) a second electrical voltage U 2 is applied between an (n+1)-th section of the first bus bar and an (n+1)-th section of the second bus bar, c) the electrical voltage between the (n+1)-th section of the first bus bar and the (n+1)-th section of the second bus bar is increased to the amount of the first electrical voltage U 1, d) a second electrical voltage U 2 is applied between an (n+2)-th section of the first bus bar and an (n+2)-th section of the second bus bar, e) steps c) and d) are repeated until a first electrical voltage U 1 is applied between all sections of the first bus bar and the associated sections of the second bus bar.

[0075] The nth section and the (n+1)th section of a bus bar may or may not be adjacent to each other. If the functional element comprises more than one first bus bar and / or more than one second bus bar, the nth section and the (n+1)th section of a bus bar may also be located on different side edges of the functional element. In this way, depending on the arrangement of the sections and the order in which they are controlled, a gradual switching of the functional element can occur, whereby a gradient can either be maintained or the functional element can be gradually transitioned from an inactive to an active state.

[0076] In particular, the second electrical voltage U 2 is between 10% and 80% of the first electrical voltage U 1 , preferably between 20% and 50% of the first electrical voltage U 1 . Within these ranges, partial switching of the active layer is particularly favored. The change in the optical properties is, on the one hand, clearly visible and easily distinguishable from the inactive region of the functional element, and, on the other hand, significantly weaker than in the fully activated region of the functional element.

[0077] Applying a voltage to areas of the functional element and correspondingly monitoring the voltage profiles can be accomplished using control units known to those skilled in the art. Excessive charging or discharging of the functional element should be prevented to prevent long-term damage to the active layer. To prevent this, the voltage is preferably not applied constantly; instead, the status of each area is monitored by measuring the open-circuit voltage between the busbar sections of the corresponding area. The open-circuit voltage should be kept approximately constant.

[0078] The invention is explained in more detail 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. They show: Figures 1a-e different views of a functional element according to the invention, Figures 2a-2ba composite pane comprising a functional element according to the invention, Figures 3a-3b the functional element of the composite pane according to the invention Figures 2a-2b and Figures 4a-4c schematic representations of the switching processes of a composite pane according to the invention.

[0079] Figures 1 a to 1 eshow a functional element 5 according to the invention comprising four side edges 4.1, 4.2, 4.3, 4.4. The functional element 5 is a multilayer film with electrically controllable optical properties, consisting of an active layer 11 between two surface electrodes 12, 13 and two carrier films 14, 15. The active layer 11 is an electrochromic layer that changes its color depending on the electrical voltage applied to the surface electrodes, whereby the optical properties can be controlled. The carrier films 14, 15 are made of PET and have a thickness of, for example, 0.125 mm. The carrier films 14, 15 are provided with an ITO coating facing the active layer 11 with a thickness of approximately 100 nm, which forms the first surface electrode 12 and the second surface electrode 13. The surface electrodes 12, 13 can be connected to the on-board electrical system via bus bars 18, 19 and connecting cables not shown.The bus bars 18, 19 are divided into sections 18.n, 19.n by means of dividing lines 16, which can be controlled individually via connecting cables. Figure 1a shows a top view of the first carrier film 14 of the functional element 5. Along the side edges 4.1, 4.2, 4.3 and 4.4 of the functional element 5, first cutouts 10.1 are introduced into the first carrier film 14, wherein in the region of the first cutouts 10.1, the first carrier film 14 and the first surface electrode 12 located thereon are removed. The active layer 11 is also removed in this region, so that the second surface electrode 13 is exposed. Along the side edges 4.1, 4.2, 4.3, 4.4, a second busbar 19 is attached circumferentially to the surface of the first carrier film 14 facing away from the first surface electrode 12, wherein said second busbar 19 extends through the first cutouts 10.1 in the region of the first cutouts and makes electrically conductive contact with the second surface electrode 13. Figure 1bshows a top view of the second carrier film 15 of the functional element 5 according to Figure 1a . The second carrier film 15 has second recesses 10.2 extending circumferentially along the side edges 4.1, 4.2, 4.3, 4.4, which are arranged alternately with the first recesses 10.1 of the first carrier film 14. A first busbar 18 is arranged circumferentially along the side edges 4.1, 4.2, 4.3, 4.4 on the surface of the second carrier film 15 facing away from the second surface electrode 13. The busbar 18 extends through the second recesses 10.2 in the region of the latter and makes electrically conductive contact with the first surface electrode 12. Figure 1c shows a cross section of the functional film 5 along the section line AA' according to Figure 1a , while in Figure 1d a cross section along the section line BB' of the Figure 1a is shown. In Figure 1eA view of the functional foil 5 in plan view of the side edge 4.3 is shown. The functional element 5 is provided with a first busbar 18 and a second busbar 19 around its perimeter, which allows a particularly uniform switching process of the functional element 5 to be generated.

[0080] Figures 2a and 2b show an embodiment of a composite pane 20 according to the invention as a roof pane, wherein in Figure 2a a top view is shown and Figure 2b a cross-section along the section line CC' of the Figure 2ashows. The roof window comprises a first pane 1, which serves as the outer pane, and a second pane 2 as the inner pane. The inner pane is the pane facing the vehicle interior, while the outer pane faces the vehicle's surroundings. The first pane 1 and the second pane 2 are connected to one another via an intermediate layer 3. The first pane 1 is made of clear soda-lime glass with a thickness of 2.1 mm. The second pane 2 is made of soda-lime glass with a thickness of 1.6 mm and is tinted grey. The tinted inner glass contributes to the attractive appearance of the window, also for the vehicle occupants when looking through the roof window. The composite pane as a roof window has a front roof edge D facing the windshield when installed, and a rear roof pane D' facing the rear window when installed.

[0081] The roof pane is equipped with a functional element 5 as a large-area shading device, wherein the functional element 5 is an electrochromic functional element embedded in the intermediate layer 3. The intermediate layer 3 comprises a total of three thermoplastic composite films 6, 7, 8, each formed from a thermoplastic film with a thickness of 0.38 mm made of PVB. The first thermoplastic composite film 6 is connected to the first pane 1, and the second thermoplastic composite film 7 is connected to the second pane 2. The intermediate thermoplastic frame film 8 has a cutout into which the functional element 5 is inserted with a precise fit, i.e., flush on all sides. The third thermoplastic layer thus forms a kind of passe-partout for the functional element 5, which is thus encapsulated all around in thermoplastic material and thus protected.The thermoplastic composite films 6, 7, 8 optionally have a tint, whereby one or more of the films can be fully or partially tinted. Depending on the thickness of the functional element 5 and the resulting thickness difference compared to the area without the functional element 5, the frame film 8 can be omitted. This also depends on the complexity of the pane bending of the composite pane. In general, it can be stated that a frame film can be omitted if the thickness differences between areas with and without the functional element are small, as well as if the bending is low.

[0082] Optionally, an additional thermoplastic composite film (not shown) can be applied adjacent to the outer pane (first pane 1). Carrier films with functional layers, such as a carrier film with an infrared-reflecting coating, can be integrated over the additional thermoplastic composite film. The infrared-reflecting coating is oriented toward the first pane 1 (outer pane) and serves to reduce heating of the passenger compartment due to solar radiation.

[0083] The roof pane has a circumferential cover print 9, which conceals both the bonding of the composite pane to the vehicle body and the electrical contacting of the surface electrodes of the functional element 5. The circumferential peripheral cover print 9 is formed by an opaque enamel on the interior-side surfaces (facing the interior of the vehicle in the installed position) of the first pane 1 and the second pane 2. The distance of the functional element 5 to the front roof edge D, the rear roof edge D', and the side edges of the roof pane is smaller than the width of the cover print 9, so that the side edges 4.1, 4.2, 4.3, and 4.4 of the functional element 5 are concealed by the cover print 9. The electrical connections are also expediently located in the area of the cover print 9 and thus advantageously concealed.

[0084] For the thermoplastic composite films 6, 7 and the thermoplastic frame film 8, a so-called "high-flow PVB" is preferably used, which exhibits greater flow properties compared to standard PVB films. This allows the layers to flow more smoothly around the functional element 5, creating a more homogeneous visual impression and making the transition from the functional element 5 to the frame film 8 less noticeable. The "high-flow PVB" can be used for all or just one or more of the thermoplastic films 6, 7, 8 in direct contact with the functional element 5.

[0085] Figures 3a and 3b show the functional element 5 of the composite pane 20 according to Figures 2a and 2b before integration of the functional element 5 into the composite pane 20, whereby the electrical contacting of the functional element 5 with bus bars 18, 19 is also visible. Figure 3a shows a top view of the functional element 5 onto the first carrier film 14, while Figure 3bshows a top view of the second carrier film 15. The functional element 5 essentially corresponds to the Figures 1a-1edescribed. In contrast, at least in the first surface electrode 12, dividing lines are introduced. Two of these dividing lines 16 run continuously between the first side edge 4.1 and the fourth side edge 4.4, which are opposite one another and divide the first surface electrode 12 into independently switchable regions 17. The first surface electrode 12 has, for example, dividing lines 16 each with a width of 200 µm, which are introduced by means of a laser process. The dividing lines 16 electrically insulate the regions 17 from one another. The number of regions 17 can be freely selected depending on the application or customer request. The dividing lines 16 are preferably introduced to divide the regions 17 into the first surface electrode 12, the second surface electrode 14, and the active layer 11. The first busbar 18 and the second busbar 19 are divided by dividing lines 16 into sections 18.n of the first busbar 18 and sections 19.n of the second bus bar 19. The dividing lines 16 are each introduced into the second bus bar 19 between adjacent first cutouts 10.1 to divide the second bus bar 19. Between adjacent second cutouts 10.2, dividing lines 16 are each introduced into the first bus bar 18. Thus, within each cutout 10 there is an electrically independently controllable section 18.n, 19.n of a bus bar 18, 19. Thus, within the areas 17, individual sub-areas can also be controlled independently of one another, with a sharp demarcation between the areas 17 and a flowing progression between active and inactive areas of the functional element within the areas.

[0086] Figures 4a, 4b and 4cshow exemplary schematic views of the switching operations of a functional element 5, wherein areas 17 are successively switched from an inactive to an active state by applying a voltage to the corresponding sections of the bus bars. Figures 4a and 4b show a flowing progression of the electrically controllable optical properties between adjacent areas 17. According to Figure 4c dividing lines 16 are provided between the areas 17 so that a sharp separation of the areas is visible. List of reference symbols:

[0087] 1First pane 2Second pane 3Intermediate layer 4.1, 4.2, 4.3, 4.4Side edges of the functional element 5Functional element with electrically controllable optical properties 6First thermoplastic composite film 7Second thermoplastic composite film 8Thermoplastic frame film 9Cover print 10Recesses 10.1First recesses 10.2Second recesses 11Active layer of the functional element 5 12First surface electrode of the functional element 5 13Second surface electrode of the functional element 5 14First carrier film 15Second carrier film 16Separation lines 17Areas 18First bus bars 19Second bus bars 20Composite pane Dfront roof edge of the composite pane D'rear roof edge of the composite pane Sside edges of the composite pane A-A', B-B', C-C' cutting line

Claims

1. Functional element (5) having electrically controllable optical properties with a plurality of side edges (4.1, 4.2, 4.3, 4.4) at least comprising a first carrier film (14) having a first flat electrode (12) and a second carrier film (15) having a second flat electrode (13) and an active layer (11) arranged flat between the first flat electrode (12) and the second flat electrode (13), wherein - a first bus bar (18) and a second bus bar (19) are arranged on at least one first side edge (4.1), - the first carrier film (14) has at least one first recess (10.1) and the second carrier film (15) has at least one second recess (10.2), and wherein - the first bus bar (18) is arranged on the surface of the second carrier film (15) facing away from the second flat electrode (13) and in the region of the at least one second recess (10.2) passes through the latter and contacts the first flat electrode (12) electrically conductively, - the second bus bar (19) is arranged on the surface of the first carrier film (14) facing away from the first flat electrode (12) and in the region of the at least one first recess (10.1) passes through the latter and contacts the second flat electrode (13) electrically conductively, and - the at least one first bus bar (18) is divided into at least one first section (18.1) and at least one second section (18.2), which can be controlled independently of one another and / or the at least one second bus bar (19) is divided into at least one first section (19.1) and at least one second section (19.2), which can be controlled independently of one another, and - the first recesses (10.1) and the second recesses (10.2) are arranged alternatingly with respect to one another.

2. Functional element (5) according to Claim 1, wherein at least one further first bus bar (18) and / or second bus bar (19) is arranged at least on a second side edge (4.2) of the functional element (5).

3. Functional element (5) according to Claims 1 or 2, wherein a first bus bar (18) and a second bus bar (19) are each arranged on the first side edge (4.1), the second side edge (4.2), the third side edge (4.3) and the fourth side edge (4.4).

4. Functional element (5) according to any one of Claims 1 to 3, wherein the first flat electrode (12) and / or the second flat electrode (13) comprise at least one separating line (16) which divides the functional element (5) into regions (17) which can be switched independently of one another.

5. Functional element (5) according to any one of Claims 1 to 4, wherein the active layer (11) is an electrochromic layer.

6. Functional element (5) according to any one of Claims 1 to 5, wherein the first bus bars (18) and the second bus bars (19) comprise an electrically conductive structure, preferably containing silver, and have a thickness of 5 µm to 40 µm.

7. Functional element (5) according to any one of Claims 1 to 6, wherein the first flat electrode (12) and the second flat electrode (13) contain at least one metal, a metal alloy, or a transparent conductive oxide, preferably a transparent conductive oxide, and have a thickness of 10 nm to 2 µm.

8. Composite pane (20) at least comprising a functional element (5) according to any one of Claims 1 to 7, a thermoplastic intermediate layer (3), a first pane (1) and a second pane (2), wherein the thermoplastic intermediate layer (3) has a first thermoplastic composite film (6) which is arranged between the functional element (5) and the first pane (1), and a second thermoplastic composite film (7) which is arranged between the functional element (5) and the second pane (2).

9. Method for switching a functional element (5) according to any one of Claims 1 to 7, wherein a first electrical voltage U1, which corresponds to the switching voltage of the functional element (5), is applied at least between a first section (18.1) of the first bus bar (18) and a first section (19.1) of the second bus bar (19), and a second electrical voltage U2, the absolute value of which is lower than the absolute value of the voltage U1, is applied between a second section (18.2) of the first bus bar (18) and a second section (19.2) of the second bus bar (19).

10. Method according to Claim 9, wherein the second electrical voltage U2 is increased to the absolute value of the first electrical voltage U1, and a third voltage U3, the absolute value of which is lower than the absolute value of the voltage U1, is preferably applied between a third section (18.3) of the first bus bar (18) and a third section (19.3) of the second bus bar (19).

11. Method according to Claims 9 or 10, wherein a) between an n-th section (18.n) of the first bus bar (18) and an n-th section (19.n) of the second bus bar (19), a first electrical voltage U1 is applied which corresponds to the switching voltage of the functional element (5), b) a second electrical voltage U2 is applied between an (n+1)-th section (18.n+1) of the first bus bar (18) and a (n+1)-th section (19.n+1) of the second bus bar (19), c) the electrical voltage between the (n+1)-th section (18.n+1) of the first bus bar (18) and the (n+1)-th section (19.n+1) of the second bus bar (19) is increased to the absolute value of the first electrical voltage U1, d) a second electrical voltage U2 is applied between an (n+2)-th section (18.n+2) of the first bus bar (18) and an (n+2)-th section (19.n+2) of the second bus bar (19), e) the steps c) and d) are repeated until a first electrical voltage U1 is applied between all sections of the first bus bar (18) and the associated sections of the second bus bar (19).

12. Method according to any one of Claims 9 to 11, wherein the second electrical voltage U2 is between 10% and 80% of the first electrical voltage U1, preferably between 20% and 50% of the first electrical voltage U1.