DE102011015950A1 - Optical component for smart window of vehicle, has two optically active layer structures of which one is formed as suspended particle device layer structure, and other is formed as polymer dispersed liquid crystal layer - Google Patents

Abstract

The optical component (1) has electrodes (4,5,10,12) that are arranged between transparent support layers (2,3,11) and optically active layer structures (6,13). One of the optically active layer structures (6) is formed as suspended particle device layer structure, and other optically active layer structures (13) is formed as a polymer dispersed liquid crystal layer. The electrodes are formed as lattice made of copper or silver. The transparent support layer is made of plastic, polycarbonate, polymethyl methacrylate or polyethylene terephthalate. An independent claim is included for method for manufacturing optical component.

Description

The invention relates to an optical component, which is reversibly changeable in its transparency and / or color by an electrical potential, according to the closer defined in the preamble of claim 1. The invention also relates to a method for producing such a component.

So-called smart windows are known from the general state of the art. Such smart windows or smart glasses consist essentially of two transparent carrier layers and two transparent electrodes arranged thereon and an active region arranged therebetween.

The active region may be formed, for example, as a polymer layer with dispersed liquid crystals. If a corresponding potential is now applied to the electrodes, then an alignment of the dispersed crystals occurs and thus a transparency of the component. If the electrical potential is switched off, the dispersed liquid crystals will align themselves as desired, as a result of which light entering through the carrier layers is correspondingly scattered and the component becomes opaque. By means of such structures, for example, window panes or other optical components can be switched electrically between full transparency and an opaque, frosted glass-like state. This can be prevented that can be seen through the optical component in certain situations. As an example, with regard to such a device, the German Offenlegungsschrift DE 198 28 630 A1 pointed.

The active region can also be formed as an electrochromic layer structure, for example as in the US Pat DE 695 32 924 T2 described with a viologenous electrochromic layer. Alternative structures for this purpose are for example in the WO 2004/082039 A2 described. The core functionality of such an electrochromic device is essentially that an electrochromic layer or an electrochromic active layer structure is arranged between two electrodes and two transparent carrier layers. By applying a voltage or a potential to the two electrodes, for example, it is possible for metallic or polymeric electrically charged particles (ions) to migrate between the layers, thereby reversibly changing the color and / or transparency of the electrochromic layer.

The problem with such optical components, which are formed either as electrochromic components or as components with dispersed crystals, lies in the fact that, due to the electrochemical system, it is only possible to switch back and forth between transparent and opaque or between two different colors. It would be desirable here a higher flexibility.

Another problem with such optical components lies in the fact that the commonly used transparent electrodes are very sensitive. In particular, a slight bending of the component is already sufficient in order to generate cracks in the transparent electrode and thus adversely affect the functionality. On the one hand, such bending and the associated risk of crack formation can already be achieved by a different expansion behavior of the different materials when the component is heated or cooled, and on the other hand, during assembly. Because of this fragility of the transparent electrodes, comparatively stable and therefore heavy and expensive carrier layers of glass are usually used in order to make the overall structure for storage and assembly so manageable that it can be moved and mounted without the immediate risk of damage. Another reason for the use of glass is that the transparent electrodes usually by temperature-intensive process -. As sputtering - are applied to the substrate and many plastics are not sufficiently temperature resistant. Due to the aforementioned material-specific requirements, a forming of a component semifinished product is possible only within very narrow limits, so that such components are usually designed planar.

For further general state of the art is from the US 5,903,382 a structure is known in which between two carrier layers and electrodes and an electrolyte is introduced. With an appropriate voltage or corresponding potential between the electrodes, active deposition of particles on one of the electrodes occurs, whereby a change in the color and / or the transparency of the structure is achieved. This construction is so far reversible that the particles which have undergone a chemical bond to the electrode migrate back into the solution by reversing the potential and thus change the color and transparency of the structure again. The problem with this design, which uses a metallic lattice as one of the electrodes, is essentially that the electrode is actively involved in the electrochemical process and thereby some erosion of the electrode occurs over time. The electrochemical classification behind this structure also causes in comparison to the above-described components with polymer-dispersed liquid crystals a very slow response, since the electrochemical processes for attaching the substances to the Electrode grid and re-dispersing the same in the solution are relatively tedious and cause very long switching periods.

The object of the present invention is now to provide a fast switching optical component in which a wide range of choices with a compact design can be achieved.

According to the invention this object is achieved by the features mentioned in the characterizing part of claim 1. Further advantageous embodiments of the optical component according to the invention will become apparent from the dependent therefrom dependent claims.

The optical component according to the invention thus has at least two optically active layer structures, of which at least one is designed as a polymer-dispersed liquid crystal layer (PDLC) and at least one other than continuously adjustable with respect to the transparency layer or layer structure. The latter can be configured as an electrochromic layer or layer structure or, alternatively, as an SPD (suspended particle device). The SPD layer is light and dark adjustable between states while the electrochromic layer is adjustable between different colors. The optical component according to the invention thus makes it possible to set the transparency or an opaque state via the polymer-dispersed liquid-crystal layer on the one hand and, on the other hand, independently thereof, a corresponding color through the electrochromic layer or brightness through the SPD layer. This results in a very high flexibility in the active switchable design of the optical component in terms of transparency and / or color or brightness. If further optically active layer structures, in particular further electrochromic or SPD layer structures, are added, then further colors can be set as a mixture or individually. The flexibility with regard to the optical design of the component according to the invention is therefore virtually unlimited. Also conceivable is a three-component structure of PDLC, SPD and electrochromic layer which allows a further improved opacity function and mixture of colors and brightnesses.

In a particularly favorable and advantageous development of the optical component according to the invention, it is also provided that at least one of the electrodes is formed as an inert metallic grid.

Under inert in the sense of the present invention, a metallic lattice is understood, which is not involved in electrochemical processes in the optical component, which thus only fulfills the functionality of an electrode of a capacitor and not, as in the last-mentioned prior art, as electrochemical active component is included. This construction with an electrode made of an inert metallic grid has the advantage that the metallic grid, for example based on silver or copper, can be produced with high conductivity. It can be realized extremely thin, so there is no visual impairment due to the metallic grid. Nevertheless, it has a very high conductivity and its mesh size can easily and easily be adapted to the respective requirements. The metallic grid is very flexible compared to a conductive transparent layer, which offers the decisive advantage that the carrier layers can be designed correspondingly thinner and more flexible. In particular, the component according to the invention makes it possible for the first time to produce the carrier layers from a flexible plastic material, and thus to achieve a high degree of flexibility of the device during assembly. In particular, curved structures can also be realized with the electrical component according to the invention during assembly.

The metallic grid as an electrode also allows better conductivity than the usual transparent electrically conductive layers. This makes it possible to realize a better switchability between the individual states as a further advantage of the component according to the invention. In particular, the degree of transparency can be adjusted much more easily, and smaller electrical powers or potentials are required for switching between full transparency and a colored state. However, the potential required for switching the PDLC layer must be ensured.

Another advantage is that electrical resistance of the structure can be realized by the resistance in the metallic grid of the electrode. In particular, at very low temperatures, as may occur, for example, in roofs of vehicles at correspondingly low ambient temperatures, this is a decisive advantage, since a much faster switching can be realized by the heating of the component according to the invention, as in the previous layer structures, which at Low ambient temperatures react very slowly.

In a preferred embodiment of the optical component according to the invention, it is also provided that the at least one electrode is formed as a grid printed on one of the carrier layers. This preferred structure allows a very simple manufacture of the component according to the invention, since the electrode, for example, over Screen printing method or the like can be applied to one or both of the carrier layers. Thus, carrier layers can be prefabricated with electrodes, which can then be connected to one another via the layer of polymer-dispersed liquid crystals to form the final layer structure simply and efficiently.

Further advantageous embodiments of the invention will become apparent from the remaining dependent claims and will become apparent from the embodiment, which will be described below with reference to the figures.

Showing:

1 a schematic diagram of the structure according to the invention in a first embodiment;

2 a representation of the structure according to 1 in a first state;

3 a representation of the structure according to 2 in a second state; and

4 a schematic diagram of the structure according to the invention in a second embodiment.

In the presentation of the 1 is a schematic diagram of the optical component according to the invention 1 to recognize. This should be designed as a so-called smart glass or smart window. The in 1 shown section consists of a first carrier layer 2 and a second carrier layer 3 , These carrier layers 2 . 3 are as transparent carrier layers 2 . 3 formed and may for example be made of glass, but in particular of plastic materials, such as polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET) or the like. On these two carrier layers 2 . 3 is each an electrode 4 . 5 applied. This can be glued, vapor-deposited or more preferably printed by a screen printing process. The electrodes 4 . 5 consist of metallic lattices, which with a highly conductive metallic material, such as silver, copper or the like, on the carrier layers 2 . 3 are applied. The electrodes 4 . 5 are in the mesh size and the strength of the individual strands of the grid designed so that they ensure sufficient electrical conductivity and also the optical transparency of the component 1 not adversely affect.

Between the electrodes 4 . 5 is an electrochromic layer structure 6 arranged. In the in the 1 to 3 illustrated embodiment, this electrochromic layer structure 6 from an electrochromic layer 7 which may, for example, comprise metallic oxides, typically WO ₃ , MoO ₃ , Nb ₂ O ₅ or the like. As an alternative to these metallic oxides, it is also conceivable to use electrochromic polymers, for example PEDT / PSS or other derivatives of polythiophenes. The electrochromic layer structure 6 also contains an electrolyte 8th , which is preferably in the form of a polymeric gel. This consists of a polymer matrix which has protons or salts, preferably lithium salts. Polymer matrices made of PEO, PMMA or propylene carbonate, for example, which are provided with LiCIO ₄ , LiCF ₃ SO ₃ , LiBF ₄ etc. or H ₃ PO ₄ in the case of proton conduction are known from the prior art. The electrochromic layer structure 6 also has a third layer in the form of an ion reservoir 9 which in turn may typically be formed with metal oxides such as TiO ₂ , CeO ₂ -TiO ₂ or, in the case of anode dyeing, for example in V ₂ O ₅ , NiO _x , IrO _x . Alternatively, metallic complexes such as Prussian blue or conductive electrochromic polymers such as Polyanhlin or polypyrrole can be used.

The further structure of the optical component 1 uses the second carrier layer 3 double, so that on their the electrochromic layer structure 6 opposite side another electrode 10 having in the form of another inert metallic grid. The conclusion of the optical component 1 forms a further carrier layer 11 , which also with an electrode 12 is provided in the form of an inert metallic grid. Between these two electrodes 10 . 12 is then a polymer dispersed liquid crystal layer 13 arranged. This is known per se from the general state of the art. As an example, this is already mentioned at the beginning DE 198 28 630 A1 which describes such a layer in a possible embodiment.

All in all, such an optical component is created 1 , which in the example shown here consists of two subelements 14 . 15 composed. The first subelement 14 includes the carrier layers 2 . 3 , the electrodes 4 . 5 and the electrochromic layer structure 6 , The second subelement 15 includes the carrier layers 3 . 11 , the electrodes 10 . 12 and the polymer-dispersed liquid crystal layer 13 , The carrier layer 3 can of both sub-elements 14 . 15 be shared. Alternatively, it would also be conceivable, instead of a carrier layer 3 insert two separate carrier layers, and then a transparent adhesive, the two sub-elements 14 . 15 to connect with each other.

On the functionality of the optical component 1 should be based on the 2 and 3 shortly received become. In the presentation of the 2 and 3 is a comparable structure as in 1 shown again, the order of the sub-elements 14 . 15 this is done swapped.

In the presentation of the 2 is a first state of the electrochromic layer structure 6 shown with a first potential U ₁ . Electrons come out of the electrode and migrate into the electrochromic layer 7 (or ion storage layer 9 ). There they react and cause a color change. The metal ions designated M + migrate from the ion storage layer 9 in the area of the electrochromic layer 7 (or vice versa) to balance the charge (in this layer). With reversed potential U ₁ , which in 3 is shown, the metallic ions migrate M + in the ion storage 9 , This leads to a change in color and / or transparency in the electrochromic layer structure 6 in a known manner.

The electrodes 10 . 12 can be independently of the electrodes 4 . 5 with an electric potential U ₂ drive. In the polymer-dispersed liquid crystal layer 13 are liquid crystals in the de-energized state (U ₂ = 0) of the electrodes 10 . 12 arranged with evenly distributed in all spatial directions alignments, as in 2 is shown. The component 1 therefore scatters in the area of the sub-element 15 through the transparent carrier layers 3 . 11 incident light so that it appears opaque. In this state, the optical component 1 be used as a screen and also prevents the incidence of heat radiation, for example, in a with such a component 1 equipped vehicle, so that a thermal heating of the same can be significantly reduced. By applying a potential U ₂ , those in the liquid crystal layer become 13 arranged crystals are increasingly aligned with increasing potential, so that they all point increasingly in a spatial direction, as in 3 is indicated. The incident light is then no longer scattered, but passes through the sub-element 15 of the component 1 through, so that at full potential a complete or almost completely transparent subelement 15 arises.

The subelement 15 is therefore switchable by a suitable potential U _{2 in} terms of its transparency. Since the increasing potential of an increasing number of crystals is aligned, the structure in its transparency can be influenced almost arbitrarily, so that not only between a fully transparent and a vollopaken state back and forth can be switched.

In the presentation of the 2 is the combination of an opaque second subelement 15 with a first color of the first subelement 14 represented by the comparatively dark colored electrochromic layer 7 is symbolized. In the presentation of the 3 is at the first subelement 14 another color represented by the lighter colored electrochromic layer 7 is indicated. In addition, the polymer-dispersed liquid crystal layer 13 switched by the application of a potential U ₂ so that the crystals aligned and the second sub-element 15 is transparent. Besides these two in the 2 and 3 shown states can also realize other states, namely the in 2 illustrated state of the first sub-element 14 in combination with the in 3 shown state of the second partial element 14 and vice versa, so that in total in the case of the comparatively simple construction described here, two partial elements 14 . 15 already four different settings are possible. By adding further sub-elements, in particular further sub-elements with electrochromic layer structure, the variability of the colors can be correspondingly increased if these electrochromic layer constructions each represent different colors, so that different colors and mixed colors can be produced.

The production of the first partial element 14 of the optical component 1 may preferably be such that a metallic grid on the transparent support layer 2 . 3 is printed. Subsequently, a coating of a part of the carrier layer takes place 2 with the electrochromic layer 7 For example, by sputtering, with a sol-gel coating, by spraying, Aufspateln, doctoring or by means of a spin coating, depending on the material used. With similar procedure is applied to another part of the printed carrier layer 3 the ion storage layer 9 applied. Subsequently, the two with the electrochromic layer 7 on the one hand and the ion storage layer 9 on the other hand coat and with the metallic lattices as electrodes 4 . 5 printed carrier layers 2 . 3 with the electrolyte 8th connected, preferably by roll calendering.

After in this way the first subelement 14 has been prepared, another such sub-element can be prepared so as to produce the desired number of sub-elements with electrochromic layer structures 6 to realize. By way of example, however, only such a subelement is intended here 14 can be used, as shown in the figures. Now lets on this subelement 14 , and here in particular the. backing 3 this subelement 14 , another electrode 10 imprint in the form of an inert metallic grid as well as on another carrier layer 11 , The subelement 14 with the printed electrode 10 as well as the carrier layer 11 with the printed electrode 12 are then passed through the polymer dispersed liquid crystal layer 13 connected together and complete the sub-element 14 of the optical component 1 so to the overall structure.

Alternatively, an inverse method can be carried out, in which initially the sub-element 15 is produced, to the carrier layer 3 an electrode is printed and then an electrochromic layer 7 or an ion storage layer 9 be applied. Thereafter, it is applied to another part of the carrier layer 3 an electrode printed and then ion storage layer 9 or the electrochromic layer 7 applied. Finally, both with the electrolyte 8th put together, z. B. by roll calendering.

Alternatively, it would of course be conceivable instead of the carrier layer 11 another sub-element in the nature of the sub-element 14 to use, so a structure of two sub-elements 14 with electrochromic layer structures and a subelement arranged therebetween 15 with polymer-dispersed liquid crystal layer 13 to obtain. Alternative arrangements, for example the sub-elements 14 in succession with a final arranged sub-element 15 , of course, would be just as conceivable. In principle, it would also be conceivable, two of the sub-elements 15 to increase the degree of opaqueness even further.

Alternatively, it would also be possible to replace the shared carrier layer 3 the subelements 14 . 15 individually build and flat by means of a transparent adhesive to the optical component 1 to stick together.

Alternatively, it is also possible to use an SPD layer instead of the electrochromic layer.

Another alternative is conceivable in which either the PDLC layer or the electrochromic (EC) layer is switched by applying a suitable potential. This would be z. For example, the states "opaque with color 1" by switching the EC layer or "transparent with color 1" by switching the PDLC layer possible. Without tension, the EC layer is colored and the PDLC layer is opaque.

Likewise, another alternative is denknar, in which either the PDLC layer or an SPD layer is switched by applying a suitable potential. This would be z. As the states "opaque + dark or transparent" by switching the SPD layer or "transparent with dark state" by switching the PDLC layer possible. Without tension, the SPD layer is dark (blue) and the PDLC layer is opaque.

The optical component 1 can be used as described, as a transparent component 1 to be variable in its transparency and / or color. If one of the electrodes 4 . 5 . 10 . 12 is not applied as a grid, but as a continuous reflective layer, for example made of silver, then can also be a reflective component 1 realize, which due to the electrochromic layer structure 6 is variable in its color.

in the presentation of the 4 is shown a further variant in which instead of the complex electrochromic layer structure 6 in the manner described above a single electrochromic layer based on viologens, as described for example in the above DE 695 32 924 T2 are described, can be used.

The structure of the optical component 1 especially when using backing layers 2 . 3 . 11 is made of flexible plastic materials, is very flexible and easy to handle and assemble. The existing in the constructions of the prior art danger that the electrode is damaged when bending of the structure is here largely excluded. The high flexibility of the electrodes 4 . 5 . 10 . 12 allows, for example, a structure of the component 1 , which can be brought into a curved shape during assembly. Alternatively, the optical component 1 z. B. glued to a bent component, welded or secured in any other way. In addition, such a component is compared to the use of relatively heavy and fragile glasses as a support layer 2 . 3 . 11 especially easy. especially when used in vehicles caused by the flexible carrier layers 2 . 3 In addition, a decisive safety advantage, since in the case of an accident does not have to be expected with glass splinters.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19828630 A1 [0003, 0024]
• DE 69532924 T2 [0004, 0040]
• WO 2004/082039 A2 [0004]
• US 5903382 [0007]

Claims (11)

Optical component ( 1 ), which is reversibly changeable in its color and / or transparency by an electrical potential, with transparent carrier layers ( 2 . 3 . 11 ) and between each two electrodes ( 4 . 5 . 10 . 12 ) arranged optically active layer structures ( 6 . 13 ), characterized in that at least three transparent carrier layers ( 2 . 3 . 11 ) are provided, and that at least two optically active layer structures ( 6 . 13 ) between two electrodes ( 4 . 5 . 10 . 12 ) and through one of the carrier layers ( 3 ) are formed separately from each other, wherein at least one of the optically active layer structures as electrochromic layer structure ( 6 ) or formed as an SPD layer structure, and at least one other of the optically active layer structures as a polymer-dispersed liquid crystal layer ( 13 ) is trained. Optical component ( 1 ) according to claim 1, characterized in that the electrochromic layer structure ( 6 ) an electrochromic layer ( 7 ), an electrolyte ( 8th ), as well as an ion storage layer ( 9 ) having. Optical component ( 1 ) according to claim 1 or 2, characterized in that at least one of the electrodes ( 4 . 5 . 10 . 12 ) is formed as an inert metallic grid. Optical component ( 1 ) according to claim 1, 2 or 3, characterized in that the at least one grating formed electrode ( 4 . 5 . 10 . 12 ) Has silver and / or copper. Optical component ( 1 ) according to one of claims 1 to 4, characterized in that one of the electrodes ( 4 . 5 . 10 . 12 ) is formed as a reflective layer. Optical component ( 1 ) according to one of claims 1 to 4, characterized in that all electrodes ( 4 . 5 . 10 . 12 ) are formed as an inert metallic grid. Optical component ( 1 ) according to one of claims 1 to 6, characterized in that at least one of the carrier layers ( 2 . 3 . 11 ) consists of a plastic material, in particular of PC, PMMA or PET, or consists of glass. Optical component ( 1 ) according to one of claims 1 to 7, characterized in that at least one of the electrodes ( 4 . 5 . 10 . 12 ) than on one of the carrier layers ( 2 . 3 . 11 ) is formed on printed grid. Method for producing an optical component ( 1 ) according to one of claims 1 to 8, characterized in that a first optically active layer ( 6 ) between two with electrodes ( 4 . 5 ) printed carrier layers ( 2 . 3 ) and to a first sub-element ( 14 ), preferably by roll calendering, a further optically active layer ( 13 ) between two with electrodes ( 10 . 12 ) printed carrier layers ( 3 . 11 ) and to a further subelement ( 15 ), preferably by roll calendering, optionally with a component ( 1 ) with more than two optically active layers ( 6 . 13 ) further sub-elements ( 14 . 15 ) are produced in this way, according to which all sub-elements ( 14 . 15 ) with optically transparent adhesive flat to the component ( 1 ) are glued. Method for producing an optical component ( 1 ) according to one of claims 1 to 8, characterized in that a first optically active layer ( 6 ) between two with electrodes ( 4 . 5 ) printed carrier layers ( 2 . 3 ) and to a first sub-element ( 14 ), preferably by roll calendering, after which the first subelement ( 14 ) and another carrier layer ( 11 ) or a comparably produced further subelement ( 14 ) each with electrodes ( 10 . 12 ) and with another optically active layer ( 13 ) to the component ( 1 ), preferably by roll calendering, this process being optional for a component ( 1 ) with more than two optically active layers ( 6 . 13 ) is repeated several times. Method for producing an optical component ( 1 ) according to one of claims 9 or 10, characterized in that the first optically active layer has an electrochromic layer structure ( 6 ) of electrochromic layer ( 7 ), an electrolyte ( 8th ), as well as an ion storage layer ( 9 ), where electrodes ( 4 . 5 ) on two carrier layers ( 2 . 3 ), whereupon the structure of the first electrode ( 4 ) and first carrier layer ( 2 ) with the electrochromic layer ( 7 ), while the second electrode ( 5 ) and second carrier layer ( 3 ) with the ion storage layer ( 9 ), whereupon the two coated carrier layers ( 2 . 3 ) with the polymeric electrolyte ( 8th ) to one of the subelements ( 14 ).

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