Film for selectively adjusting the opacity and sun protection of a window

Abstract

film (100) with a plurality of layers, wherein the plurality of layers comprises, - a first active layer (113) which is configured to change a scattering level by means of a change of state, with which light in the first active layer (113) is controlled; - a second active layer (123) which is configured to change, by means of a change of state, the transmittance with which light passes through the second active layer (123); and - Electrode layers (111, 112, 121, 122, 115, 125, 116) arranged such that states of the first active layer (113) and states of the second active layer (123) can be changed separately from each other; where - the majority of layers comprise a first outer electrode layer (111) arranged on a first side of the first active layer (113); - the majority of layers comprise a second outer electrode layer (122) which is arranged on a second side of the second active layer (123); - the second side of the second active layer (123) is turned away from the first side of the first active layer (113); - the majority of layers comprise at least one middle electrode layer (112, 121, 115, 125, 116) that is arranged between the first active layer (113) and the second active layer (123); - the first outer electrode layer (111) and the at least one middle electrode layer (112, 121, 115, 125, 116) are arranged to generate a first electric field over the first active layer (113) in order to change a state of the first active layer (113); - the second outer electrode layer (122) and the at least one middle electrode layer (112, 121, 115, 125, 116) are arranged to generate a second electric field over the second active layer (123) in order to change a state of the second active layer (123); and - comprising at least one middle electrode layer (112, 121, 115, 125, 116) a common electrode layer for generating the first and second electric fields.

Description

[0001] The invention relates to a film with which a window, in particular a window of a vehicle, can be selectively clouded and / or provided with sun protection.

[0002] A vehicle has windows through which sunlight can enter the vehicle's interior, which can be disturbing to the vehicle's occupants under certain circumstances (e.g., on hot days). Furthermore, outsiders can see into the vehicle's interior through the vehicle's windows, which can compromise the privacy of the vehicle's occupants.

[0003] JP H11-38 455 A discloses glass in which both the transmission and the light scattering can be varied by electrical means. For this purpose, the glass has a first active layer for varying the degree of scattering and a second active layer for varying the transmission. In one embodiment, the states of the first active layer and the states of the second active layer can be changed separately.

[0004] US 2013 / 0 214 562 A1 discloses a film-coated glass that can be used, for example, for sunroofs in vehicles, and whose transmission can be adjusted electrically. For this purpose, the film contains, among other things, two electrically controllable film structures, between which movable particles are located, by means of which the light transmission and / or light scattering between the film structures can be varied.

[0005] DE 10 2011 015 950 A1 describes an optical component whose color and / or transparency can be reversibly changed by an electrical potential. It comprises two transparent carrier layers and at least two optically active layer structures arranged between two electrodes each. At least one of the layer structures is designed as a polymer-dispersed liquid crystal layer (PDLC), and at least one other layer structure is designed as an electrochromic layer whose transparency can be continuously adjusted. The optical component thus makes it possible to adjust the transparency or an opaque state via the PDLC on the one hand, and to adjust a corresponding color independently via the electrochromic layer on the other.

[0006] This document addresses the technical problem of providing a film for a window, in particular for a window of a vehicle, which enables solar protection and privacy protection to be provided in a selective manner.

[0007] The object is achieved by the independent claims. Advantageous embodiments are described, inter alia, in the dependent claims.

[0008] According to one aspect, a film comprising a plurality of layers is described. When viewed horizontally, the layers are arranged one above the other. Light incident on a first side of the film (e.g., on the top side) thus passes through the plurality of layers to exit the film again on a second side (opposite the first side) of the film (e.g., on the bottom side).

[0009] The plurality of layers (or the film) comprises a first active layer which is configured to change a degree of scattering by means of a change in the state of the first active layer, with which degree of scattering light is controlled in the first active layer. Light arriving on a first side of the first active layer can, for example, have parallel light rays. A certain proportion of these parallel light rays can then be controlled in the first active layer so that the light on the second side of the first active layer has fewer parallel light rays than on the first side. The extent of the reduction in parallel light rays can depend on the degree of scattering. The scattering of light within the first active layer typically leads to a clouding of the film, so that a user no longer has a clear view through the film.

[0010] The plurality of layers (or the film) comprises a second active layer which is configured to change the transmittance with which light passes through the second active layer by changing its state. Light arriving on a first side of the second active layer can have a certain energy. A certain proportion of this energy can be absorbed by the second active film and / or reflected by the second active film, so that the light emerging on the second side of the second active layer has a reduced energy. The extent of the reduction in light energy depends on the transmittance. The second active layer can thus lead to a darkening and / or a color change of the film.

[0011] The plurality of layers (or the film) further comprises electrode layers arranged such that states of the first active layer and states of the second active layer can be changed separately from one another.

[0012] The plurality of layers (or the film) comprises a first outer electrode layer arranged on a first side of the first active layer. Furthermore, the plurality of layers (or the film) comprises a second outer electrode layer arranged on a second side of the second active layer. The second side of the second active layer and the first side of the first active layer face away from one another. Furthermore, the plurality of layers (or the film) comprises at least one middle electrode layer arranged between the first active layer and the second active layer. The electrode layers can each comprise, for example, a transparent conducting oxide (TCO) layer.

[0013] The first outer electrode layer and the at least one middle electrode layer are configured to generate a first electric field across the first active layer to change a state of the first active layer (e.g., to switch the first active layer from the cloudy state to the clear state or vice versa). For this purpose, the electrode layers can be connected to a voltage and / or current source.

[0014] The second outer electrode layer and the at least one middle electrode layer are configured to generate a second electric field above the second active layer to change a state of the second active layer (e.g., to switch the second active layer from the darkened state to the bright state or vice versa). For this purpose, the electrode layers can be connected to a voltage and / or current source.

[0015] Thus, a film can be provided that can be selectively clouded (e.g. to provide privacy protection) and / or darkened (e.g. to provide sun protection).

[0016] In particular, the first active layer can have a cloudy state and a clear state, wherein the scattering degree in the cloudy state is higher, in particular by a factor of 2 or more, than the scattering degree in the clear state. Thus, the first active layer can be switched back and forth between a cloudy state (in which the view through the film is obscured) and a clear state (in which a substantially clear view through the film is possible) by controlling the electrode layers.

[0017] The scattering efficiency of the first active layer is typically higher in the cloudy state, in particular by a factor of 2 or more, than the scattering efficiency of the second active layer (in any given state). In other words, the second active layer preferably causes little or no light scattering, so that the clouding of the film is substantially achieved only by the first active layer. Thus, a strict separation between clouding and darkening of the film can be achieved.

[0018] Furthermore, the first active layer is preferably designed such that the transmittance (in particular the total transmittance, i.e. the transmittance for parallel light and for diffuse light) of the first active layer in the cloudy state and the transmittance (in particular the total transmittance, i.e. the transmittance for parallel light and for diffuse light) of the first active layer in the clear state deviate from one another by less than a predefined deviation threshold value of in particular 20%, 10% or less. In other words, the first active layer is preferably designed such that no substantial darkening occurs due to the first active layer (in particular no substantial change in the darkening). A strict separation can thus be made between clouding and darkening of the film.

[0019] The second active layer can have a darkened state and a bright state, wherein the transmittance in the darkened state is lower, in particular by a factor of 2 or more, than the transmittance in the bright state. Thus, the second active layer can be switched between a darkened state (with reduced transparency) and a bright state by controlling electrode layers, for example, to provide sun protection when needed.

[0020] The transmittance of the second active layer is typically lower in the darkened state, in particular by a factor of 2 or more, than the transmittance of the first active layer (in any state of the first active layer). In other words, the first active layer typically does not cause any substantial darkening of the film. Thus, a strict distinction can be made between clouding and darkening of the film.

[0021] Furthermore, the second active layer is preferably designed such that the degree of scattering in the bright state deviates by less than a predefined deviation threshold, in particular 20%, 10%, or less. In other words, the second active layer preferably does not cause any substantial (change in) light scattering. Thus, a strict separation between clouding and darkening of the film can be achieved.

[0022] The first active layer can therefore switch between high parallel light transmission on the one hand (in the clear state) and high diffuse light transmission on the other (in the opaque state). The degree of scattering or haze (i.e. the ratio of diffuse light transmission to parallel light transmission, or the proportion of diffuse light transmission to the total light transmission) is substantially increased, e.g. from approx. 2% (in the clear state) to more than 90% (in the opaque state). The total light transmission (i.e. the sum of diffuse light transmission and parallel light transmission) remains substantially unchanged. Using the second layer, the total light transmission can be varied without (in any state) having a significant proportion of diffuse light transmission. Typically, the proportion of diffuse light transmission of the second layer is 2% or less in the bright state and in the darkened state.

[0023] The first active layer may comprise, for example, a polymer dispersed liquid crystal (PDLC) or other LC (i.e., liquid crystal) layer. On the other hand, the second active layer may comprise, for example, an electrochromic, an electrophoretic, a liquid crystal, and / or a suspended particle device (SPD) layer.

[0024] The at least one middle electrode layer can comprise a common electrode layer for generating the first and second electric fields. In particular, the film can comprise only one common middle electrode layer (e.g., only one common TCO layer). The first electric field is then generated by the first outer electrode layer relative to the common middle electrode layer. Furthermore, the second electric field is then generated by the second outer electrode layer relative to the common middle electrode layer. By combining the middle electrode layers, the costs and thickness of the film can be reduced.

[0025] Alternatively, the at least one middle electrode layer can comprise a carrier layer (e.g., a PET layer). An electrode layer facing the first active layer (e.g., a TCO layer) can then be arranged on a first side of the carrier layer, and an electrode layer facing the second active layer (e.g., a TCO layer) can then be arranged on a second side of the carrier layer. The use of a common carrier layer for electrically separated middle electrode layers for the two active layers enables a compact film structure.

[0026] According to another aspect, a system for adjusting a switchable window or a switchable transparent surface is described. The system comprises a window (or a transparent surface) with a film described in this document. Furthermore, the system comprises a control unit configured to control the active layers of the film to selectively switch the window (or surface) to a clear and bright state; to a dim and bright state; and to a clear and darkened state. Thus, privacy protection and / or sun protection can be provided in a flexible manner.

[0027] According to a further aspect, a vehicle (in particular a road vehicle, e.g. a passenger car, a truck or a motorcycle) is described which comprises the film or the system described in this document.

[0028] It should be noted that the devices and systems described in this document can be used both alone and in combination with other devices and systems described in this document. Furthermore, any aspects of the devices and systems described in this document can be combined in a variety of ways. In particular, the features of the claims can be combined in a variety of ways.

[0029] The invention will be described in more detail below using exemplary embodiments. Fig. 1a, Fig. 1b, and Fig. 1c exemplary layer structures of a protective film for a window; and Fig. 2 a block diagram of a system for changing the state of a window.

[0030] As stated at the beginning, this document deals with the selective provision of solar shading and privacy protection in or on a window, in particular in or on a window for a vehicle. In this context, the Fig. 1a, Fig. 1b, Fig. 1c different layer structures of a film 100 that can be used to provide such protection.

[0031] The film 100 comprises two different active layers 113, 123. The different active layers 113, 123 can be controlled by electric fields, wherein a first electric field can be generated above the first active layer 113 by a first voltage source 114 (with a first voltage U1). For this purpose, the first active layer 113 is arranged between two first electrode layers 111, 112, and the first voltage source 114 is configured to apply the first voltage between the two first electrode layers 111, 112. In an analogous manner, a second voltage U2 can be applied between two second electrode layers 121, 122 by a second voltage source 124, wherein the second active layer 123 is located between the second electrode layers 121, 122.

[0032] The first active layer 113 is configured to change the degree of light scattering in the film 100. In particular, the first active layer 113 can be switched between a clear state and a cloudy state. In the clear state, light passes through the first active layer 113 without substantial scattering. On the other hand, in the cloudy state, light is substantially controlled in the first active layer 113, so that the film 100 becomes cloudy and a user can no longer see clearly through the film 100.

[0033] On the other hand, the first active layer 113 preferably absorbs or reflects little or no light. In other words, the energy of the light passing through the first active layer 113 remains substantially unchanged. Furthermore, the first active layer 113 is preferably such that light incident on the first active layer 113 passes substantially completely through the first active layer 113 (and is not reflected).

[0034] Consequently, the first active layer 113 can be used to cloud the film 100 and thus provide privacy protection without causing substantial darkening. The first active layer 113 can, for example, comprise a PDLC (polymer dispersed liquid crystal) or, more generally, an LC (liquid crystal) layer.

[0035] The second layer 123 is designed to change a transmittance for light. In particular, the second layer 123 can have a bright state and a darkened state, wherein switching between the two states can be achieved by controlling the second electrode layers 121, 122. In the bright state, the second layer 123 is transparent and allows incident light to pass through substantially completely (and without scattering). On the other hand, in the darkened state, the second layer 123 substantially attenuates incident light, so that the film 100 is darkened. The second layer 123 can, for example, have an electrochromic, an electrophoretic, a liquid crystal, and / or an SPD (suspended particle device) layer. The second layer 123 can thus be used to provide efficient sun protection.

[0036] The film 100 can thus comprise a first active layer 113, in which a significant change in the parallel light transmission occurs through the layer 113, but only a slight change in the total light transmission. The first active layer 113 thus enables switching between a highly scattering (cloudy) and a slightly scattering (clear) state. The film 100 can further comprise a second active layer 123, in which the parallel light transmission remains proportional to the total light transmission, but in which the total light transmission can be changed. The second active layer 123 thus enables a general darkening / color change without light scattering / clouding.

[0037] A first layer complex comprising the first electrode layers 111, 112 and the first active layer 113, and a second layer complex comprising the second electrode layers 121, 122 and the second active layer 123 can be bonded together via an adhesive layer 103 (e.g. a PVB layer) to provide a film 100 comprising both the first active layer 113 and the second active layer 123, wherein the active layers 113, 123 can each be controlled individually or separately.

[0038] Fig. 2 shows a system 200 comprising an input unit 202, via which a user's input can be recorded. The system 200 further comprises a window with two panes 203, 204, between which the film 100 is arranged. The film 100 can be connected to the panes 203, 204 via adhesive layers 101, 102. This can be used, for example, to provide laminated safety glass for a vehicle. Furthermore, the system 200 comprises a control unit 201, which is configured to control the active layers 113, 123 of the film 100 depending on a user input. By combining the two active layers 113, 123, four different states can be set via an input: • a normal state in which the first active layer 113 is in the clear state and the second active layer 123 is in the bright state; • a light-protection state in which the first active layer 113 is in the clear state and the second active layer 123 is in the darkened state; • a privacy state in which the first active layer 113 is in the dim state and the second active layer 123 is in the bright state; and • a combined light protection and privacy state in which the first active layer 113 is in the cloudy state and the second active layer 123 is in the darkened state.

[0039] By combining different active layers 113, 123, selective light protection and privacy protection can be provided.

[0040] The electrode layers 111, 112, 121, 122 typically comprise a carrier layer (e.g., a PET (polyethylene terephthalate) layer) on which a transparent electrode (e.g., a TCO (transparent conducting oxide) layer) is arranged. The layer structure of a film 100 with multiple active layers 113, 123 can be simplified by using, for example, a common carrier layer 105 for the middle electrode layers 112, 121 between directly adjacent active layers 113, 123. This is shown in Fig. 1b. In particular, Fig. 1b shows that an electrode 115 for the first active layer 113 is arranged on a first side of a common carrier layer 105, and an electrode 125 for the second active layer 123 is arranged on a second side. This allows the cost and thickness of a film 100 to be reduced.

[0041] A further simplification and cost reduction is achieved by using a common central electrode layer 116 for the first active layer 113 and for the second active layer 123, so that the first electric field is generated by a voltage between the first outer electrode layer 111 and the central electrode layer 116 and so that the second electric field is generated by a voltage between the second outer electrode layer 12 and the central electrode layer 116.

[0042] By integrating the active layers 113, 123 into a common film 100, the complexity of a glass lamination process can be reduced. Furthermore, by reducing the number of layers and interfaces, the optical quality can be increased (e.g., higher light transmission and / or lower haze). Furthermore, by combining the central electrode 116, the contacting and cabling effort can be reduced.

[0043] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and figures are intended only to illustrate the principle of the proposed devices and systems.

Claims

[1] A film (100) having a plurality of layers, wherein the plurality of layers comprises - a first active layer (113) configured to change a degree of scattering by means of a change in state, with which light is controlled in the first active layer (113); - a second active layer (123) which is configured to change a transmittance with which light passes through the second active layer (123) by a change of state; and - electrode layers (111, 112, 121, 122, 115, 125, 116) arranged such that states of the first active layer (113) and states of the second active layer (123) can be changed separately from one another; where - the plurality of layers comprises a first outer electrode layer (111) arranged on a first side of the first active layer (113); - the plurality of layers comprises a second outer electrode layer (122) arranged on a second side of the second active layer (123); - the second side of the second active layer (123) faces away from the first side of the first active layer (113); - the plurality of layers comprises at least one middle electrode layer (112, 121, 115, 125, 116) arranged between the first active layer (113) and the second active layer (123); - the first outer electrode layer (111) and the at least one middle electrode layer (112, 121, 115, 125, 116) are configured to generate a first electric field across the first active layer (113) to change a state of the first active layer (113); - the second outer electrode layer (122) and the at least one middle electrode layer (112, 121, 115, 125, 116) are configured to generate a second electric field above the second active layer (123) in order to change a state of the second active layer (123); and - the at least one middle electrode layer (112, 121, 115, 125, 116) comprises a common electrode layer for generating the first and second electric fields. [2] Film (100) according to claim 1, wherein - the first active layer (113) has a cloudy state and a clear state; - the degree of scattering in the cloudy state is higher, in particular by a factor of 2 or more, than the degree of scattering in the clear state. [3] Film (100) according to claim 2, wherein - the degree of scattering in the cloudy state is higher, in particular by a factor of 2 or more, than the degree of scattering of the second active layer (123); and / or - the first active layer (113) is designed such that the transmittance in the cloudy state and the transmittance in the clear state differ from each other by less than a predefined deviation threshold value of in particular 20%, 10% or less. [4] Film (100) according to one of the preceding claims, wherein - the second active layer (123) has a darkened state and a bright state; and - the transmittance in the darkened state is lower, in particular by a factor of 2 or more, than the transmittance in the bright state. [5] Film (100) according to claim 4, wherein - the transmittance in the darkened state is lower, in particular by a factor of 2 or more, than the transmittance of the first active layer (113); and / or - the second active layer (123) is designed such that the degree of scattering in the bright state differs from one another by less than a predefined deviation threshold value of, in particular, 20%, 10% or less. [6] Film (100) according to one of the preceding claims, wherein - the first active layer (113) comprises a polymer dispersed liquid crystal layer or a liquid crystal layer; and / or - the second active layer (123) comprises an electrochromic, an electrophoretic, a liquid crystal and / or a suspended particle device layer. [7] Film (100) according to one of the preceding claims, wherein - the at least one middle electrode layer (112, 121, 115, 125, 116) comprises a carrier layer (105); - an electrode layer (115) facing the first active layer (113) is arranged on a first side of the carrier layer (105); and - an electrode layer (125) facing the second active layer (123) is arranged on a second side of the carrier layer (105). [8] System (200) for adjusting a switchable window (203, 204), the system (200) comprising - a window (203, 204) with a film (100) according to one of the preceding claims; - a control unit (201) which is arranged to control the active layers (113, 123) of the film (100) in order to selectively - to switch to a clear and bright state; - to switch to a dim and bright state; and - to switch in a clear and darkened state.

Images