Method for producing a composite panel for a holographic head-up display, and composite panel
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SAINT GOBAIN SEKURIT FRANCE
- Filing Date
- 2024-06-05
- Publication Date
- 2026-04-22
AI Technical Summary
The production of composite windshields with integrated holographic elements for head-up displays is hindered by optical errors due to delamination, leading to increased manufacturing costs and rejects, limiting design flexibility and installation options.
A method involving thermal welding of substrate and cover films surrounding the holographic recording medium before cutting, ensuring the holographic recording medium is completely embedded between the two polymer films, preventing micro-mechanical damage and subsequent delamination, and using a thermoplastic intermediate layer to laminate the composite pane.
This approach prevents optical impairments caused by delamination, allowing for cost- and time-efficient production of high-quality composite panes with increased design variability and reduced manufacturing rejects.
Smart Images
Figure EP2024065500_19122024_PF_FP_ABST
Abstract
Description
[0001] Method for producing a composite pane for a holographic head-up display, and composite pane
[0002] The present invention lies in the technical field of pane manufacturing and relates to a method for producing a composite pane for a holographic head-up display, as well as a composite pane for a holographic head-up display produced by the method according to the invention.
[0003] Modern automobiles are increasingly being equipped with so-called head-up displays (HUDs). Using a projector, typically located in the dashboard, images are projected onto the HUD area of the windshield, 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 or navigation and warning information, 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.
[0004] With the head-up displays described above, the optical principle that the angles of incidence and reflection of the light striking and reflected from the windshield are always the same must be taken into account. This adversely limits the design of the windshield and its installation options. One solution to this problem is the integration of hologram elements into the windshield. These do not reflect light, but rather diffract the incident light according to the recorded hologram. Such hologram elements advantageously contain a hologram created by holographic exposure of a holographic recording medium in such a way that the function of an optical mirror is implemented for a specific wavelength and angle of incidence of the incident light.This mirror function of the hologram allows any information from an imaging projector to be projected onto an image plane, visible to the viewer in a specific spatial area, commonly referred to as the "eye box." Since the holographic mirror function is actually based on the diffraction of light, the optical law applicable to reflection, according to which the angle of incidence corresponds to the angle of reflection, is not applicable. This has the advantage that the eye box can also be positioned outside of areas where secondary images (ghost images) caused by reflection from the laminated glass are visible. Furthermore, there is greater variability in the installation situation of windshields, which can also be installed very flat in a vehicle.
[0005] Hologram elements with mirror-like holograms laminated between the individual panes of a windshield can be used for head-up displays. Mirror-like holograms, also known as "reflection holograms," are well known to those skilled in the art and are widely described in the patent literature, see, for example, DE102017212451A1, WO 2012 / 156124A1, and US 2019 / 0056596A1. The holograms of a holographic head-up display are typically designed to respond only to light within a narrow wavelength and angular range emitted by an internally arranged projector.
[0006] Windshields generally consist of two panes, typically made of glass, that are firmly bonded (laminated) to one another via an intermediate layer containing at least one region of a thermoplastic. Holographic optical elements with a mirror function are typically provided in film form and laminated into the composite pane. A well-known procedure involves covering a polymer substrate film with a holographic recording medium (photopolymer) applied to one surface with a polymer cover film. This effectively protects the holographic recording medium between the two polymer films from mechanical and chemical influences.The stack of two polymer films with holographic recording media is laminated between the two glass panes of the windshield, with a connecting layer of a thermoplastic typically placed on either side of the stack of polymer films. Thus, the two polymer films with the recording medium in between are embedded in the thermoplastic.
[0007] In practice, it has been shown that when laminating windshields with integrated polymer films with holographic recording media, optical defects can occur due to delamination, which ultimately increases the proportion of rejects and thus the manufacturing costs of the windshields.
[0008] CN 114660695 A discloses a composite pane with a holographic film laminated between two thermoplastic foils. Also shown is the arrangement of base layers on both sides of the holographic film. In contrast, the object of the present invention is to avoid the aforementioned disadvantages and to provide an improved composite pane for a projection arrangement with a HUD area, which can be manufactured in industrial series production in a time- and cost-efficient manner and with high optical quality. In particular, this should be possible in a simple manner using existing and possibly only slightly modified production facilities.
[0009] These and other objects are achieved according to the invention by a method for producing a composite pane and a composite pane according to the independent patent claims. Advantageous embodiments of the invention are set out in the subclaims.
[0010] According to the invention, a method for producing a composite pane, preferably a laminated glass pane, for a projection arrangement with a holographic HUD region is shown.
[0011] The "HUD area" refers to an area of the composite pane intended to be illuminated with the light (image) of a projector in a projection arrangement, so that a head-up display image can be displayed in the HUD area. The HUD area is therefore arranged in an area of the composite pane that is at least partially transparent, with a light transmittance (according to ISO 9050:2003) of preferably at least 50%, particularly preferably at least 70%. If the composite pane is, for example, a windshield in a car, the HUD area is an area through which a viewer (e.g., the driver) can see the road.
[0012] The composite pane has a circumferential edge, which particularly preferably comprises an upper edge and a lower edge, as well as two side edges running between them with a left and a right side edge (when looking at the composite pane from the inside). The upper edge refers to the edge which is intended to point upwards in the installed position. The lower edge refers to the edge which is intended to point downwards in the installed position. The upper edge is often also referred to as the roof edge and the lower edge as the engine edge. The composite pane can have any suitable geometric shape and / or curvature. The composite pane comprises an outer pane and an inner pane which are firmly connected to one another by an intermediate layer containing two or more connecting layers made of a thermoplastic material.The intermediate layer can be divided into various connecting layers made of a thermoplastic material, whereby the connecting layers made of a thermoplastic material can also be bonded (fused) to one another. Even with an intermediate layer made of several (fused) connecting layers, areas of the intermediate layer that correspond to the respective connecting layers can be individualized, at least conceptually. The intermediate layer preferably extends over the entire surface of the composite pane, i.e., is arranged flatly between the outer pane and the inner pane.
[0013] A holographic recording medium is embedded (preferably completely) in the intermediate layer and in thermoplastic material and is located between a substrate film made of a polymer material and a cover film made of a polymer material. The polymer material(s) of the substrate and cover film can in principle be chosen arbitrarily, provided that they are thermally weldable (i.e. by heating above a (highest or respective) melting temperature) so that the substrate and cover film or regions thereof can be firmly bonded to one another by the action of externally applied heat. In other words, the polymer material(s) of the substrate and cover film can be bonded to one another in a material-to-material manner by thermal melting and subsequent cooling. The polymer material(s) of the substrate film and cover film are preferably different from the thermoplastic material of the connecting layers.
[0014] In the holographic recording medium, at least one holographically active zone with a mirror function realized by light diffraction for at least one wavelength and at least one angle of incidence can be created by holographic exposure (holographic recording), which typically comprises a light beam and a reference beam. The holographically active zone corresponds to the area of the recording medium that has been provided with a hologram by holographic exposure. Typically, the mirror function of the hologram is implemented in the hologram for a narrow wavelength range and a small range of the angle of incidence of the incident light. These properties depend on the specific conditions of the light beam and reference beam during the recording of the hologram. This is well known to the person skilled in the art and is not necessary for understanding the invention, so it need not be discussed in detail here.
[0015] The holographic recording medium is a material suitable for recording a hologram with a mirror function. Suitable materials for this purpose are known to those skilled in the art. Typically, the holographic recording medium contains or consists of a photopolymer.
[0016] The holographic recording medium can have a single holographically active zone (i.e., a single hologram) in one region of the holographic recording medium or multiple holographically active zones (i.e., multiple holograms) in different regions of the holographic recording medium. The holographic recording medium can be provided with at least one hologram with a mirror function, i.e., with at least one holographically active zone, by holographic exposure before or after integration into the composite pane. Preferably, but not necessarily, the holographic exposure of the holographic recording medium to generate at least one hologram with a mirror function takes place before the integration of the holographic recording medium into the composite pane. The at least one holographically active zone contains a hologram (i.e., holographic recording) and can also be referred to as a hologram element.
[0017] The method according to the invention for producing a composite pane for a projection arrangement with a HUD area comprises the following steps, which are carried out, for example, in the specified order according to alphabetical sequence, whereby the sequence of the steps can also be different or steps can be carried out simultaneously:
[0018] Step a)
[0019] Producing a first stacking sequence, comprising a substrate film made of a thermally weldable polymer material (polymer film), wherein a holographic recording medium is arranged flatly on a surface of the substrate film, wherein at least one holographically active zone with a mirror function for at least one wavelength and at least one angle of incidence can be produced or has already been produced in the holographic recording medium by holographic exposure, a cover film made of a thermally weldable polymer material (polymer film), which is arranged on the substrate film, wherein the holographic recording medium is arranged between the substrate film and the cover film.
[0020] Step b)
[0021] Thermally welding the substrate and cover foils of the first stacking sequence in an area (preferably completely) surrounding the at least one holographically active zone, thereby creating a thermally welded connection area. In the thermally welded connection area, the substrate foil and cover foil are bonded together. The substrate foil and cover foil are bonded together only in an area where no holographic recording medium is located. In other words, there is no holographically active recording medium between the substrate foil and cover foil in the thermally welded connection area.
[0022] Step c)
[0023] Cutting the first stacking sequence with the thermally welded connection area to a predetermined (or predeterminable) size. The predetermined size results from the specific characteristics of the composite pane and can be selected according to the circumstances.
[0024] Step d)
[0025] Providing an outer pane and an inner pane, as well as at least two connecting layers made of a thermoplastic material, typically in film form.
[0026] Step e)
[0027] Arranging the first stacking sequence with a thermally welded connecting region between the outer pane and the inner pane and between the at least two connecting layers to form a second stacking sequence, wherein the HUD region is formed by the at least one holographically active zone of the holographic recording medium. One connecting layer of the at least two connecting layers is arranged between the first stacking sequence and the inner pane, and the other connecting layer of the at least two connecting layers is arranged between the first stacking sequence and the outer pane, so that the first stacking sequence is embedded in thermoplastic on both sides. Step f)
[0028] Laminating the second stack sequence to produce the composite pane.
[0029] Preferably, step b) for thermally welding the substrate and cover foil of the first stacking sequence takes place before or at the same time as step c) for cutting the first stacking sequence with thermally welded connection area to a predetermined size.
[0030] As experiments by the inventors have shown, by thermally welding the substrate and cover foil in the connecting region surrounding the holographic recording medium or the at least one holographically active zone, optical impairment of the composite pane in the region of the holographic recording medium, caused by delamination, can advantageously be avoided. Without being bound to any theory, it is currently assumed that without thermally welding the substrate and cover foil in the connecting region before cutting the first stacking sequence, the mechanical action during cutting of the first stacking sequence will cause micromechanical damage to the substrate and cover foil, which causes delamination and subsequently produces undesirable optical defects in the composite pane.The present invention thus advantageously demonstrates a new way to easily prevent optical defects caused by delamination in the area of the substrate and cover foil. This is a major advantage of the present invention.
[0031] In one embodiment, the first stacking sequence is cut to a predetermined size before the thermal welding of the substrate and cover foils of the first stacking sequence, i.e., step c) is performed before step b). This procedure has beneficial effects in terms of avoiding optical defects due to delamination of the composite pane.
[0032] In one embodiment, the first stacking sequence is cut to a predetermined size and the substrate and cover films of the first stacking sequence are thermally welded together simultaneously, i.e., steps b) and c) are performed simultaneously. This can be done, for example, using a hot cutting tool, such as a hot cutting knife. Not only is the first stacking sequence cut, but during cutting, the substrate and cover films are thermally welded together by the hot cutting tool, particularly in the cutting area (cutting edges). This embodiment is particularly preferred due to its time and cost efficiency. Optical defects due to delamination of the composite pane can be reliably and safely avoided.
[0033] In one embodiment, the first stacking sequence is cut to a predetermined length after the thermal welding of the substrate and cover foils of the first stacking sequence, with the first stacking sequence being cut within the bonding region or on a side of the bonding region facing away from the at least one holographically active zone. This approach also reliably and safely prevents optical defects due to delamination of the composite pane. While this embodiment is advantageous, it is less time-efficient than the immediately preceding embodiment.
[0034] The two polymer films of the first stacking sequence are thermally welded in a connecting region which (preferably completely) surrounds the holographic recording medium or the at least one holographic-active zone. The connecting region preferably completely surrounds the holographic recording medium or the at least one holographic-active zone. In other words, the holographic recording medium or the at least one holographic-active zone is preferably completely embedded between the substrate film and the cover film and surrounded exclusively by material from the substrate film and cover film. Machines and methods commonly used in the series production of laminated panes can be used particularly advantageously for this purpose (e.g. plotters for introducing wires into PVB layers by heating). The circumferential connecting region is particularly advantageously a circumferential edge region of the first stacking sequence (orof substrate and cover film).
[0035] In one embodiment, the substrate and cover films contain or consist of polyethylene terephthalate (PET), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polyamide (PA), polyvinyl chloride (PVC), and / or cellulose triacetate (TAC), preferably polycarbonate (PC). The polymer materials of the substrate and cover films can be the same or different. These materials can be bonded together by thermal welding. For example, the thickness of a polymer film is between 20 and 100 μm. The size of the substrate and cover films depends on the specific characteristics of the laminated pane and must be selected accordingly.
[0036] In principle, the size and shape of the at least one holographically active zone (i.e., hologram) are independent of the size and shape of the holographic recording medium, provided that the holographically active zone is formed in the holographic recording medium and therefore cannot be larger than the holographic recording medium. In one embodiment, an area occupied by the holographically active zone is smaller than an area occupied by the holographic recording medium on the substrate film. This has the particular advantage that the holographically active zone, which defines the HUD region, can have significantly smaller dimensions than the holographic recording medium. For example, the holographically active zone can have typical dimensions for a HUD region, such as210 x 210 mm for a HUD area in the application "Augmented Reality", or 50 x 150 mm for a smaller field of view in which only a small amount of information is to be displayed.
[0037] The holographic recording medium, however, can also completely cover an optically transparent see-through area of the composite pane (e.g., a windshield). This has the advantage that the edge of the holographic recording medium lies outside the see-through area of the composite pane, thus avoiding a potentially visually disruptive edge of the recording medium. Accordingly, in an advantageous embodiment, the holographic recording medium completely covers an optically transparent see-through area of the composite pane. The size of the two polymer films of the substrate and cover film is accordingly large enough, for example, to completely cover an optically transparent see-through area of the composite pane.
[0038] In principle, the size and shape of the holographic recording medium are independent of the size and shape of the substrate foil or cover foil.
[0039] In one embodiment, the holographic recording medium completely covers the substrate foil except for a peripheral edge zone, which is thermally welded into the composite pane in the connection area. In one embodiment, the size and shape of the holographic recording medium are significantly smaller than the size and shape of the substrate foil or cover foil.
[0040] In one embodiment, the substrate and cover foils are of the same size, although their size may also be different from each other as long as it is ensured that the holographic recording medium (as seen vertically through the substrate foil) is completely covered by the cover foil.
[0041] In one embodiment of the method according to the invention, a further connecting layer made of a thermoplastic material is provided, typically in film form, which is provided with an internal cutout. To produce the second stacking sequence, the first stacking sequence is arranged within the cutout of the further connecting layer so that it surrounds the first stacking sequence in the manner of a passe-partout (frame). By virtue of the further connecting layer, which surrounds the first stacking sequence in a frame-like manner, the effect of mechanical forces on the first stacking sequence during lamination of the second stacking sequence to produce the composite pane can be at least largely avoided.
[0042] When laminating the second stacking sequence, at least one connecting layer of the at least two connecting layers made of a thermoplastic material is arranged between the first stacking sequence and the inner pane and at least one further connecting layer of the at least two connecting layers made of a thermoplastic material is arranged between the first stacking sequence and the outer pane.
[0043] In one embodiment, a minimum thickness of the connecting layer of the at least two connecting layers, which is located between the first stacking sequence and the inner pane, is less than a minimum thickness of a further connecting layer of the at least two connecting layers, which is located between the first stacking sequence and the outer pane. In other words, the at least one connecting layer between the first stacking sequence and the inner pane is thinner than the at least one further connecting layer between the first stacking sequence and the outer pane. Preferably, the at least one connecting layer between the first stacking sequence and the inner pane has a minimum thickness in the range from 0.05 mm to less than 0.38 mm, and the at least one connecting layer between the first stacking sequence and the outer pane has a minimum thickness in the range from 0.38 mm to 1 mm.In particular, the at least one connecting layer between the first stacking sequence and the outer pane can have a standard thickness of 0.38 mm or 0.76 mm, which is common in the automotive sector for windshields.
[0044] As layers, bonding layers are generally flat and extended. For the purposes of the present invention, the term "thickness" refers to the dimension of a bonding layer perpendicular to the flat extension or area of the bonding layer. For the purposes of the invention, thickness is considered to be the smallest or smallest thickness (i.e., dimension) perpendicular to the surface of the bonding layer, which applies in particular to wedge-shaped bonding layers whose thickness is variable. It is understood that a bonding layer can always have a constant or constant thickness.
[0045] The invention further extends to a composite pane produced by the method according to the invention for a projection arrangement with a HUD area (H).
[0046] The composite pane comprises an inner pane and an outer pane, which are firmly connected to one another by an intermediate layer containing at least two connecting layers made of a thermoplastic. Embedded in the intermediate layer is a first stacking sequence comprising a substrate film made of polymer material with a holographic recording medium applied thereto and a cover film made of a polymer material arranged on the substrate film. The holographic recording medium is arranged between the substrate film and the cover film. At least one holographically active zone with a mirror function can be produced or is produced in the holographic recording medium by holographic exposure, wherein the HUD region (H) is formed by the at least one holographically active zone.The substrate film and the cover film are bonded together by thermal welding in a connection area that surrounds (preferably completely) the holographically active zone.
[0047] The laminated pane is intended to separate the interior from the exterior environment in an opening in a surrounding structure, e.g. in a window opening in a vehicle. The outer pane is arranged closer to the exterior environment than the inner pane. The two panes each have an exterior and an interior surface and a circumferential side edge running between them. The exterior surface refers to the main surface which is intended to face the exterior environment in the installed position. The interior surface refers to the main surface which is intended to face the interior in the installed position. The interior surface of the outer pane and the exterior surface of the inner pane face each other and are connected to one another by the intermediate layer.Other common designations are "Side I" for the outside surface of the outer pane, "Side II" for the inside surface of the outer pane, "Side III" for the outside surface of the inner pane and "Side IV" for the inside surface of the inner pane.
[0048] The two panes of the composite pane can, in principle, have any chemical composition known to those skilled in the art. The two panes preferably contain or consist of glass, particularly preferably flat glass, float glass, quartz glass, borosilicate glass, soda-lime glass, or aluminosilicate glass. It is also conceivable for the two panes to contain or consist of a clear plastic, preferably a rigid clear plastic, in particular polyethylene, polypropylene, polycarbonate, polymethyl methacrylate, polystyrene, polyamide, polyester, polyvinyl chloride, and / or mixtures thereof.
[0049] In a preferred embodiment of the invention, the laminated pane contains or consists of glass. The thickness of each individual pane of the laminated pane can vary widely and be adapted to the requirements of the individual case. Preferably, panes with standard thicknesses of 0.5 mm to 25 mm are used, and more preferably, 0.5 mm to 5 mm. The size of the panes can vary widely and depends on their use. The laminated pane can have any three-dimensional shape and can be planar or curved in one or more spatial directions.
[0050] The two panes of the composite pane are firmly bonded to one another by an intermediate layer, wherein the intermediate layer contains two or more bonding layers made of a thermoplastic, corresponding to the bonding layers typically provided in film form that are used to laminate the composite pane. In particular, the intermediate layer can also contain a bonding layer made of a thermoplastic that surrounds the stacking sequence of substrate film and cover film with the holographic recording medium in between in a frame-like manner. It is understood that the bonding layers provided in film form fuse during lamination, so that the resulting bonding layers of the composite pane can also be bonded (fused) to one another, with a bonding layer made of thermoplastic being present on both sides of the stacking sequence.
[0051] Each connecting layer made of a thermoplastic material preferably contains or consists of polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), polyethylene terephthalate (PET), or mixtures or copolymers or derivatives thereof, particularly preferably PVB.
[0052] In one embodiment, the composite pane contains an acoustically damping layer. This typically comprises at least two outer polymer layers and at least one inner polymer layer located between them, wherein the inner polymer layer has greater plasticity or elasticity than the outer polymer layers. This results in an acoustically damping layer that has a softer core, while the stiffness of the layer structure increases from the core to the edge. The inner polymer layer has, for example, a thickness of 0.05 mm to 0.40 mm and the outer polymer layers have, for example, a thickness of 0.20 mm to 0.60 mm. Acoustically damping layers are known in the art, see, for example, WO 2017 / 055470 A1, so there is no need to go into them in more detail here.
[0053] In one embodiment, the laminated pane contains an infrared radiation (IR)-reflecting layer, an infrared radiation (IR)-absorbing layer, a UV radiation (UV)-reflecting layer, a UV radiation (UV)-absorbing layer, and / or an electrically heatable coating. Such layers are known in the art and are used as standard, e.g., in vehicle windows, so further explanation is unnecessary.
[0054] The two panes of the laminated pane and / or the intermediate layer or one or more connecting layers of the intermediate layer can be clear and colorless, but also tinted or colored.
[0055] For the purposes of this invention, "transparent" means that the total transmission of the laminated pane complies with the legal requirements of the European Union for windshields and front side windows and preferably has a visible light transmittance of more than 70%, and in particular more than 75%. For rear side windows, roof windows, and rear windows, "transparent" can also mean 10% to 70% light transmission. Accordingly, "opaque" means a light transmission of less than 15%, preferably less than 5%, and in particular 0%.
[0056] In the composite windshield, the HUD area is formed by at least one holographically active zone of the holographic recording medium. Thus, the holographically active zone serves as a holographic mirror for the incident light with a specific wavelength and angle of incidence, i.e., for the image projected onto the HUD area. Since these optical processes are based on diffraction, the angles of incidence and reflection do not have to be equal, which allows for a wide variety of possible composite windshield shapes and installation situations, especially for very flat windshields. The composite windshield is preferably a motor vehicle windshield.
[0057] The holographically active zone of the holographic recording medium is designed to "mirror" an image projected onto the holographically active zone by a projector. The light suitable for the hologram can be generated by conventional HUD projectors. The HUD projector can be, for example, a liquid crystal display (LCD), a thin-film transistor (TFT), a light-emitting diode (LED), an organic light-emitting diode (OLED), or an electroluminescent (EL) display. It can also contain laser diodes, particularly those using MEMS technology to control the laser light.
[0058] As is common with HUDs and projection devices based on similar technology, the projector irradiates light in the visible wavelength range from 380 nm to 780 nm, provided that the hologram has a mirror function at the wavelength and angle of incidence used.
[0059] The diffraction efficiency refers to the proportion of radiation diffracted ("reflected") in the holographically active zone to the total incident radiation. It is expressed as a percentage (relative to 100% incident radiation) or as a unitless number from 0 to 1 (normalized to the incident radiation). The diffraction efficiency is advantageously in the range of 1 to 50%, especially in the range of 5 to 20%.
[0060] The at least one holographically active zone preferably extends over a maximum of 50%, particularly preferably a maximum of 40%, and in particular a maximum of 20%, of the surface area of the composite pane. As already explained, the HUD region is arranged in a region of the composite pane that is at least partially transparent, with a light transmittance (according to ISO 9050:2003) of preferably at least 50%, particularly preferably at least 70%. In a car windshield, the HUD region is a region of the windshield through which a viewer (e.g., the driver) can see the road. Particularly preferably, the at least one holographically active zone is arranged in a (main) viewing area of the composite pane (zone A).
[0061] The composite pane produced by the method according to the invention can be part of a projection system, whereby the HUD area of the composite pane can be illuminated by a projector. The projector projects light onto the HUD area (i.e., onto the holographically active zone), which is then "mirrored."
[0062] The projector preferably faces the interior-side surface of the inner pane. If the laminated pane is installed (for example, as a windshield in a vehicle), the projector illuminates the HUD area from within the vehicle interior. If the projection system is part of a vehicle, the projector is preferably located in the vehicle's dashboard. The light projected by the projector onto the HUD area of the laminated pane is diffracted into the vehicle interior, for example, into the field of vision of an occupant.
[0063] Known processes for producing a composite pane can be used to laminate the composite pane. For example, so-called autoclave processes can be carried out at an elevated pressure of approximately 1 bar to 15 bar and temperatures of 100°C to 145°C for approximately 2 hours. Known vacuum bag or vacuum ring processes, for example, operate at approximately 200 mbar and 130°C to 145°C. The two panes can also be pressed into a composite pane in a calender between at least one pair of rollers. Systems of this type are known for producing composite panes and usually have at least one heating tunnel upstream of a pressing unit. The temperature during the pressing process is, for example, between 40°C and 150°C. Combinations of calender and autoclave processes have proven particularly successful in practice. Alternatively, vacuum laminators can be used.These consist of one or more heatable and evacuatable chambers in which the first pane and the second pane can be laminated within, for example, approximately 60 minutes at a reduced pressure of 0.01 mbar to 800 mbar and temperatures of 80°C to 170°C. This is well known to those skilled in the art, so it need not be discussed in detail here.
[0064] Furthermore, the invention extends to the use of the composite pane according to the invention in buildings or in means of transport for land, air, or water traffic, in particular in motor vehicles, for example as a windshield, rear window, side windows, and / or roof window. According to the invention, the use of the composite pane in motor vehicles is preferred, particularly preferably as a windshield or roof window.
[0065] The various embodiments of the invention can be implemented individually or in any combination. In particular, the features mentioned above and explained below can be used not only in the specified combinations, but also in other combinations or on their own, without departing from the scope of the present invention. In particular, features of the composite pane according to the invention apply analogously to the inventive method for producing the composite pane. Similarly, features of the inventive method apply analogously to the composite pane according to the invention.
[0066] The invention is explained in more detail below using exemplary embodiments, with reference to the accompanying figures. They show, in simplified form and not to scale:
[0067] Figure 1 shows an embodiment of the composite pane according to the invention in a
[0068] top view,
[0069] Figure 2 shows a projection arrangement with an embodiment of the
[0070] Composite pane from Figure 1 in a cross-sectional view according to section line A- A',
[0071] Figure 3 is an enlarged view of a region of the composite pane containing the HUD region H in the projection arrangement of Figure 2 in a cross-sectional view, Figure 4A is a first stacking sequence of holographic medium and substrate and cover foil in a plan view,
[0072] Figure 4B shows the first stacking sequence of Figure 4A in a cross-sectional view along section line B-B',
[0073] Figure 5 is a flowchart of the method according to the invention,
[0074] Figure 6 shows a second stacking sequence containing the first stacking sequence, as well as slices and connecting layers.
[0075] Figures 1 to 6 illustrate by way of example the composite pane 1 according to the invention and its production. Figure 1 shows an embodiment of the composite pane 1, which is a windshield for a vehicle. The composite pane 1 is shown in a plan view, looking onto an interior-side surface IV of the composite pane 1. Figure 2 shows an embodiment of the composite pane 1 as a component of a projection arrangement 100 according to the invention in a cross-sectional view, wherein the projection arrangement 100 is installed in a vehicle. The cross-sectional view of Figure 2 corresponds to the section line AA' of the composite pane 1, as indicated in Figure 1. Figure 3 shows an enlarged section of the projection arrangement 100 from Figure 2, wherein the enlarged section shows a region of the composite pane 1 which contains the HUD region H.Figures 4A and 4B show a stacking sequence 6 with a holographic recording medium between the substrate and cover foil in a plan view (Figure 4A) and a cross-sectional view along section line BB'. Figure 5 shows a flow diagram of the method according to the invention. Figure 6 illustrates a second stacking sequence 19 containing the first stacking sequence 6, as well as the two disks 2, 3 and the connecting layers 18, 18', 18".
[0076] The composite pane 1 has an upper edge and a lower edge as well as two side edges connecting the upper and lower edges (all of this together forms a circumferential edge of the composite pane 1). The lower edge (also called the engine edge) of the composite pane 1 refers to the edge which faces the ground in the installed position. The upper edge (also called the roof edge) of the composite pane 1 refers to the edge which faces the vehicle roof in the installed position in a vehicle. The composite pane 1 comprises an outer pane 2, an inner pane 3 and an intermediate layer 4 arranged between the outer pane 2 and the inner pane 3. The outer pane 2 has an outer surface I facing away from the intermediate layer 4 and an interior surface II facing the intermediate layer 4. The inner pane 3 has an outer surface III facing the intermediate layer 4 and an interior surface IV facing away from the intermediate layer 4.The outer surface I of the outer pane 2 is simultaneously the surface of the composite pane 1 facing the external environment 13, and the interior surface IV of the inner pane 3 is simultaneously the surface of the composite pane 1 facing the interior 12 of the vehicle. The composite pane 1 has, for example, a shape and curvature typical for windshields.
[0077] The outer pane 2 and the inner pane 3 are each made of glass, preferably thermally toughened soda-lime glass, and are transparent to visible light. The outer pane 2 has a thickness of 2.1 mm, for example, and the inner pane 3 has a thickness of 1.5 mm, for example.
[0078] An opaque masking layer 5 is applied to the interior-side surface II of the outer pane 2. The masking layer 5 extends along the circumferential edge of the composite pane 1 and is applied in the edge region 7 directly adjacent to the lower edge of the composite pane 1. The masking layer 5 is opaque and prevents the view of structures arranged on the inside or outside of the composite pane 1, for example, an adhesive bead for bonding the composite pane 1 to a vehicle body. The masking layer 5 consists of an electrically non-conductive material conventionally used for black printing, for example, a black-colored, baked screen printing ink.
[0079] The composite pane 1 has a HUD area H, which is intended to display a head-up display image for a driver or passenger of the vehicle. The HUD area H is arranged in the view-through area of the composite pane 1, so that an image projected onto the HUD area H can be perceived by an observer as if it were appearing behind the composite pane 1 (i.e., in the external environment 13).
[0080] The HUD area H is formed by a holographically active zone 8, which is embedded between a substrate film 15 and a cover film 16, for example, made of polycarbonate. The holographic recording medium 17 containing the holographically active zone 8, as well as the substrate film 15 and cover film 16, together form a first stacking sequence 6. Thus, the holographically active zone 8 implements a mirror function for light of a narrow wavelength range incident at a specific angle, corresponding to the hologram recorded in the holographically active zone 8. The holographically active zone 8 is designed, for example, to diffract incident light with a diffraction efficiency in the range of 5 to 20%.
[0081] A projector 10 is arranged on a dashboard 14 of the vehicle, which projects a virtual image in the form of visible radiation (light) 11 onto the HUD area H of the composite pane 1. The angle of incidence a1 is the angle at which the radiation 11 of the projector 10 strikes the holographically active zone 8 (see Figure 3). The HUD area H irradiated by the projector 10 is indicated by a dashed trapezoidal area in the composite pane 1 in Figure 1. The radiation 11 of the projector 10 is diffracted at the holographically active zone 8, and the diffracted radiation 1T is visually perceived by an observer (e.g., the driver of the vehicle). The diffraction angle a2 differs from the angle of incidence a1, but can also be the same.Advantageously, the diffraction angle a2 and the incident angle a1 are different, whereby the diffraction angle a2 is preferably selected such that no secondary images (ghost images) are visible in the observer's eye box.
[0082] The projector 10 irradiates the HUD area H of the composite pane 1 , creating a HUD image (head-up display image) for the viewer.
[0083] In one embodiment of the method according to the invention for producing the composite pane 1, the first stacking sequence 6 is first produced from the substrate film 15 comprising the holographic recording medium 17 and the cover film 16 disposed thereon. In the holographic recording medium 17, the holographically active zone 8 with a mirror function for at least one wavelength and at least one angle of incidence has already been created by holographic exposure (step a). The holographic recording medium 17 is located between the substrate film 15 and the cover film 16.
[0084] Subsequently, the substrate film 15 comprising the holographic recording medium 17 and the cover film 16 are thermally welded in an area surrounding the holographically active zone 8, whereby a thermally welded connecting area 9 is produced (step b).
[0085] Figure 4A shows the first stacking sequence 6 with the holographic recording medium between the substrate film 15 and the cover film 16 in a top view. Figure 4B shows a cross-sectional view of the first stacking sequence 6 along the section line BB'. The cross-sectional view of Figure 4B clearly shows the substrate film 15 and the cover film 16, which are thermally welded together in the connecting region 9. The holographic recording medium 17 is completely embedded between the substrate film 15 and the cover film 16.
[0086] The plan view of Figure 4A shows that the connecting region 9 created by thermal welding is completely circumferential and edge-mounted. The holographic recording medium 17 has a holographically active zone 8, here with a rectangular shape, for example, whose area is smaller than the area of the holographic recording medium 17. The HUD region H is formed by the holographically active zone 8. The area occupied by the holographically active zone 8 is smaller than an area occupied by the holographic recording medium 17. Although not shown, the area of the holographic recording medium 17 could completely cover an optically transparent see-through area of the composite pane 1, so that no potentially optically disturbing edge lies in the see-through area.The holographic recording medium 17 completely covers the substrate film 15 except for a peripheral edge zone, which here corresponds to the thermally welded connection area 9.
[0087] Then, the stacking sequence 6 with thermally welded connecting area 9 of substrate film 15 and cover film 16 is cut to a predetermined size (step c).
[0088] As can be seen in Figure 6, the outer pane 2 and the inner pane 3, as well as two connecting layers 18, 18' made of a thermoplastic material (in film form), are provided. Preferably, the first stacking sequence 6 is inserted into the cutout 20 of a further connecting layer 18" (in film form), which surrounds the first stacking sequence 6 in a frame-like manner, like a passe-partout. Thus, the first stacking sequence 6 is inserted into a cutout 20 of the further connecting layer 18" (step d).The first stacking sequence 6 with thermally welded connecting region 9 of substrate film 15 and cover film 16, which is arranged in the cutout 20 of a further connecting layer 18", is arranged between the outer pane 2 and the inner pane 3 and between the two connecting layers 18, 18' to form a second stacking sequence 19 (see Figure 6), wherein the HUD region (H) is formed by the holographically active zone 8 of the holographic recording medium 17 (step e).
[0089] Then, the second stack sequence 19 is laminated, thereby producing the composite pane 1 (step f).
[0090] By the above method, a composite pane 1 for a projection arrangement 100 with a HUD area (H) is produced, which comprises an inner pane 3 and an outer pane 3, which are firmly connected to one another by an intermediate layer 4 containing three connecting layers 18, 18', 18" made of a thermoplastic material. The three connecting layers 18, 18', 18" made of a thermoplastic material are provided in film form before lamination and fuse together during lamination, but can also be individualized, at least conceptually, after lamination.
[0091] Embedded in the intermediate layer 4, and in particular in the thermoplastic material, is the first stacking sequence 6 comprising substrate film 15 and cover film 16, with the intermediate holographic recording medium 17, into which the holographically active zone 8 with a mirror function for at least one wavelength and at least one angle of incidence is inscribed. Substrate film 15 and cover film 16 are thermally welded in the connection area 9, which can be seen on the finished composite pane 1.
[0092] Advantageously, the thickness of the connecting layer 18 made of a thermoplastic material, which is located between the first stacking sequence 6 and the inner pane 3, is smaller than the thickness of the further connecting layer 18' made of a thermoplastic material between the first stacking sequence 6 and the outer pane 2. For example, the thickness of the connecting layer 18 made of a thermoplastic material, which is located between the first stacking sequence 6 and the inner pane 3, is in a value range of 0.05 mm to less than 0.38 mm, and the thickness of the connecting layer 18' made of a thermoplastic material, which is located between the first stacking sequence 6 and the outer pane 2, is in a value range of 0.38 mm to 1 mm.The composite pane 1 can have further layers (not shown), in particular an acoustically dampening layer, an IR-reflecting and / or IR-absorbing layer, a UV-reflecting and / or UV-absorbing layer, - an electrically heatable layer.
[0093] From the above, it can be seen that the invention provides an improved method for producing a composite pane, which can prevent optical impairment of the composite pane in the region of the holographic recording medium caused by delamination. The composite pane can be manufactured cost- and time-efficiently using industrially used production equipment, and the production of the composite pane can be easily implemented using common manufacturing processes.
[0094] Reference symbol
[0095] 1 composite pane
[0096] 2 outer pane
[0097] 3 inner pane
[0098] 4 Intermediate layer
[0099] 5 Masking layer
[0100] 6 first stacking sequence
[0101] 7 Edge area of the composite pane
[0102] 8 holographically active zone
[0103] 9 Connection area
[0104] 10 projectors
[0105] 11 Radiation of the projector
[0106] 11 ' diffracted radiation
[0107] 12 Interior
[0108] 13 external environment
[0109] 14 Dashboard
[0110] 15 Substrate film
[0111] 16 Cover film
[0112] 17 Recording medium
[0113] 18, 18', 18" connecting layer made of thermoplastic material
[0114] 19 second stacking sequence
[0115] 20 Excerpt
[0116] 100 projection arrangement
[0117] H HUD area a1 Incident angle a2 Diffraction angle
[0118] I outside surface of the outer pane 2
[0119] II Interior surface of the outer pane 2
[0120] III outer surface of the inner pane 3
[0121] IV Interior surface of the inner pane 3
[0122] AA' section line
[0123] BB' cutting line
Claims
Patent claims 1. A method for producing a composite pane (1) for a projection arrangement (100) with a HUD region (H), comprising the following steps: a) producing a first stacking sequence (6) containing a substrate film (15) made of a polymer material with a holographic recording medium (17) applied thereto, wherein at least one holographically active zone (8) with a mirror function can be produced or is produced in the holographic recording medium (17) by holographic exposure, a cover film (16) made of a polymer material, which is arranged on the substrate film (15), wherein the holographic recording medium (17) is arranged between the substrate film (15) and the cover film (16), b) thermally welding the substrate film (15) and the cover film (16) of the first stacking sequence (6) in a region surrounding the at least one holographically active zone (8), thereby producing a thermally welded connecting region (9),c) cutting the first stacking sequence (6) with the thermally welded connecting region (9) to a predetermined size, d) providing an outer pane (2) and an inner pane (3), as well as at least two connecting layers (18, 18') made of a thermoplastic material, e) arranging the first stacking sequence (6) with the thermally welded connecting region (9) between the outer pane (2) and the inner pane (3) and between the at least two connecting layers (18, 18') to form a second stacking sequence (19), wherein the HUD region is formed by the at least one holographically active zone (8), f) laminating the second stacking sequence (19).
2. Method for producing a composite pane (1) according to claim 1, in which the cutting of the first stacking sequence (6) to a predetermined size and the thermal welding of the substrate film (15) and cover film (16) of the first stacking sequence (6) take place simultaneously, in particular by inserting a hot cutting tool.
3. A method for producing a composite pane (1) according to claim 1, wherein the cutting of the first stacking sequence (6) to a predetermined size takes place after the thermal welding of the substrate film (15) and cover film (16) of the first stacking sequence (6), wherein the cutting of the first stacking sequence (6) takes place within the connection area (9) or on a side of the connection area (9) facing away from the holographically active zone (8).
4. A method for producing a composite pane (1) according to claim 1, wherein the cutting of the first stacking sequence (6) to a predetermined size takes place before the thermal welding of the substrate film (15) and cover film (16) of the first stacking sequence (6).
5. Method for producing a composite pane (1) according to one of claims 1 to 4, in which a further connecting layer (18") made of a thermoplastic material with an internal cutout (20) is provided, wherein the first stacking sequence (6) is arranged within the cutout (20) of the further connecting layer (18") during the formation of the second stacking sequence (19).
6. Method for producing a composite pane (1) according to one of claims 1 to 5, in which a minimum thickness of a connecting layer (18) of the at least two connecting layers (18, 18'), which is located between the first stacking sequence (6) and the inner pane (3), is less than a minimum thickness of a further connecting layer (18') of the at least two connecting layers (18, 18'), which is located between the first stacking sequence (6) and the outer pane (2).
7. A method for producing a composite pane (1) according to claim 6, wherein the connecting layer (18) between the first stacking sequence (6) and the inner pane (3) has a minimum thickness in the range from 0.05 mm to less than 0.38 mm and the further connecting layer (18') between the first stacking sequence (6) and the outer pane (2) has a minimum thickness in the range from 0.38 mm to 1 mm.
8. Composite pane (1) for a projection arrangement (100) with a HUD area (H), produced by the method according to one of claims 1 to 7, which comprises: an inner pane (3) and an outer pane (2) which are firmly connected to one another by an intermediate layer (4) containing at least two connecting layers (18, 18') made of a thermoplastic material, embedded in the intermediate layer (4) a first stacking sequence (6), which comprises: a substrate film (15) made of a polymer material with a holographic recording medium (17) applied thereto, wherein in the holographic recording medium (17) at least one holographic-active zone (8) with a mirror function can be produced or is produced by holographic exposure, wherein the HUD area (H) is formed by the at least one holographic-active zone (8), and a cover film (16) made of a polymer material, which is arranged on the substrate film (15), wherein the holographic recording medium (17) is arranged between the substrate film (15) and the cover film (16), wherein the substrate film (15) and the cover film (16) are materially connected to one another in a connecting region (9) surrounding the holographic-active zone (8).
9. Composite pane (1) according to claim 8, wherein an area occupied by the holographically active zone (8) is smaller than an area occupied by the holographic recording medium (17).
10. Composite pane (1) according to claim 8 or 9, wherein the holographic recording medium (17) completely covers an optically transparent see-through area of the composite pane (1). 1 1. Composite pane (1) according to one of claims 8 to 10, wherein the holographic recording medium (17) completely covers the substrate film (15) except for a peripheral edge region which is thermally welded in the peripheral connecting region (9).
12. Composite pane (1) according to one of claims 8 to 11, in which a smallest thickness of a connecting layer (18) of the at least two connecting layers (18, 18'), which is located between the first stacking sequence (6) and the inner pane (3), is less than a thickness of a further connecting layer (18') of the at least two connecting layers (18, 18'), which is located between the first stacking sequence (6) and the outer pane (2).
13. Composite pane (1) according to one of claims 8 to 12, wherein the substrate film (15) and the cover film (16) contain or consist of a polymeric material selected from polyethylene terephthalate (PET), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polyamide (PA), polyvinyl chloride (PVC) and / or cellulose triacetate (TAC).
14. Composite pane (1) according to one of claims 8 to 13, further comprising one or more of the following layers: an acoustically damping layer, an IR-reflecting and / or IR-absorbing layer, - a UV-reflecting and / or UV-absorbing layer, an electrically heatable layer.
15. Use of the composite pane (1) according to one of claims 8 to 14 in buildings or in means of transport for traffic on land, in the air or on water, in particular in motor vehicles, for example as a windscreen, rear window, side windows and / or roof window.