Liquid crystal device

Abstract

A liquid crystal device (10) for absorbing and / or scattering a controlled amount of pass-through light, comprising an active layer (12) having a first viewport surface in contact with a first planar electrode (14) and a second viewport surface in contact with a second planar electrode (16), where the active layer (12) comprises at least two side surfaces, where the first viewport surface is in contact with the first planar electrode (14) and the second viewport surface is in contact with the second planar electrode (16). Wherein the first planar electrode (14) comprises a first power supply area (22) for receiving a control voltage for controlling the active layer (12), the second planar electrode (16) comprises a second power supply area (24) for receiving a control voltage, and wherein the first power supply contact device (26) is arranged to be electrically connected to the first power supply area (22), the power supply areas (22, 24) are each associated with one or more side surfaces, and the power supply contact devices (26, 28) are each associated with one or more side surfaces and are arranged to extend along at least a portion of their respective associated side surfaces, and wherein the first power supply contact devices (26, 28) are arranged to be electrically connected to the first power supply areas (22, 24) and the second power supply contact devices (28) are arranged to be electrically connected to the second power supply areas (24). Wherein the first power supply contact device (26) and the second power supply contact device (28) are associated with adjacent side surfaces.

Description

Technical Field

[0001] The invention relates to a liquid crystal device for absorbing and / or scattering a controllable amount of traversing light, comprising an active layer having a first viewport surface and a second viewport surface, wherein the first viewport surface is in contact with a first planar electrode and the second viewport surface is in contact with a second planar electrode, wherein the active layer comprises at least two side surfaces. The invention further relates to a liquid crystal device, in particular a window element, for use in buildings and vehicles, which is energy-efficient and has improved comfort. Background Art

[0002] Dynamic glazing (e.g. solar or privacy glazing) using such liquid crystal devices is based on light absorbing and / or scattering molecules embedded in a liquid crystal host. A mixture of liquid crystal and dye molecules forms an active layer sandwiched between two plates (e.g. glass plates coated with transparent conductive oxides forming planar electrodes) to form a cell. The cell can be switched between an absorbing state and a transparent state by applying an electric field to the active layer via the planar electrodes.

[0003] An electric field is generated by applying an AC voltage to the planar electrodes. The typical frequency used is, for example, between 50 and 60 Hz. The AC voltage is applied to the electrodes by a power supply, which is connected to a power supply contact device that contacts the portion of the planar electrodes that forms the power supply area by a cable. The power supply contact device provides a contact point for electrically contacting the planar electrodes and for distributing the current. This may be necessary because the planar electrodes themselves may not be easy to weld. In addition, the planar electrodes have a resistive characteristic that may require surface contact so that enough control current can be provided to quickly establish a control voltage (control voltage) on the active layer that acts as a dielectric in the capacitor. The power supply contact device may include a plurality of contact surfaces, such as welding or otherwise being fixed to the solder joints of the planar electrodes with electrical contact, particularly along the edge or side of the box.

[0004] In many configurations, one or more boxes are laminated together or sandwiched between protective cover plates. The busbars are arranged on opposite sides of the box relative to each other to achieve a control voltage (steer voltage) that is evenly distributed over the entire area of ​​the viewport. However, the production process of the box complicates the arrangement of the control cables connected to the power supply contact devices. The arrangement of the busbars on opposite sides of the box results in additional wiring steps that must be performed manually and is therefore not suitable for current automatic insulating glass unit (IGU) production lines.

[0005] Electrically, the LC cell acts as a large area RC circuit, whose capacitance depends mainly on the area of ​​the glass window box, the cell gap and the dielectric constant of the LC or active layer. The resistance component depends mainly on the sheet resistance and aspect ratio of the cell, because the resistance component is generated by the sheet resistance of the planar electrodes. Because the LC cells need to be driven by an AC voltage, they are affected by the RC effect of the voltage drop. This results in a lower effective voltage on the cell and therefore a loss of visual transmittance in the bright state. Moreover, the effective distribution of the voltage on the cell will be non-uniform. If the voltage non-uniformity exceeds a certain level, visual artifacts (such as transmittance differences on the viewport of the liquid crystal device) may be observed. Summary of the invention

[0006] In view of the above, the present invention solves the problem of simplifying the automated production process of a liquid crystal device as described above, while maintaining or even improving the uniformity of the operating characteristics of the liquid crystal device over the viewport.

[0007] This problem is solved by a device according to claim 1. Further advantageous embodiments are object of the dependent claims.

[0008] In order to solve this problem, a liquid crystal device for absorbing and / or scattering a controllable amount of passing light includes an active layer having a first viewport surface and a second viewport surface, wherein the first viewport surface is in contact with a first planar electrode and the second viewport surface is in contact with a second planar electrode, wherein the active layer includes at least two side surfaces, wherein the first planar electrode includes a first power supply area for receiving a control voltage for controlling the active layer, and the second planar electrode includes a second power supply area for receiving the control voltage, wherein the first power supply contact device is arranged to be electrically connected to the first power supply area, and the second power supply contact device is arranged to be electrically connected to the second power supply area, wherein the power supply areas are each associated with one or more side surfaces, wherein the power supply contact devices are each associated with one or more side surfaces and are arranged to extend along at least a portion of their respectively associated sides, wherein the first power supply contact device and the second power supply contact device are associated with adjacent side surfaces.

[0009] Since the power supply contact device is thus arranged at a common corner of the liquid crystal device and (incidentally) around the active layer, the cable can be arranged to be led out at this corner. It is no longer necessary to guide the cable over the entire side of the liquid crystal device. This simplifies the production of the liquid crystal device.

[0010] In some embodiments, one or more of the contact devices extend less than 90%, 85%, 80%, 75%, 70%, 65%, 60%, 50%, 40%, 30%, 20%, or 10% of a side of the active layer.

[0011] In this way, if the bus bars are shorter than the sides of the liquid crystal device on which they are arranged, a more uniform voltage and / or current distribution is obtained over the viewport.

[0012] In some embodiments, the first power supply contact device is spaced apart from a side surface associated with the second power supply contact device and / or from the second power supply contact device.

[0013] By this arrangement, a gap is formed between the common corner of the power supply contact devices and the first power supply contact device. This further improves the uniformity of the voltage and / or current distribution over the viewing port.

[0014] In some embodiments, the first planar electrode includes a third powered region and / or the second planar electrode includes a fourth powered region, each portion extending along one of the previously unassociated side surfaces.

[0015] This allows connection to other power supply contact devices, possibly resulting in more uniform operating characteristics of the liquid crystal device.

[0016] In some embodiments, the first power supply contact device extends at least partially over the third power supply region and is in electrical contact therewith, and / or the second power supply contact device extends at least partially over the fourth power supply region and is in electrical contact therewith.

[0017] This allows the power supply contact devices to be arranged at opposite corners of the liquid crystal device, which is less complex to implement and complete than arranging the bus bars on opposite sides of the liquid crystal device. In addition, the uniformity of the control voltage distribution between the planar electrodes is improved, the voltage drop on the viewport surface is reduced, and the optical characteristics (such as the transparent state of the active layer) are improved.

[0018] In some embodiments, the active layer includes at least four side surfaces.

[0019] Liquid crystal devices having four or more sides benefit most from the increased uniformity achievable by the above-described features.

[0020] In some embodiments, one of the powered areas is longer than 1.5 m.

[0021] Liquid crystal devices with very long side surfaces benefit most from the increased uniformity achievable by the above-described features.

[0022] In some embodiments, at least one power supply contact device is discontinuous in that it comprises a plurality of contact surfaces that are not in direct contact with each other.

[0023] This does not exclude electrical contact via eg wiring devices, only direct contact between contact surfaces. The contact surface may mediate between eg wiring and planar electrodes, which wiring may not be easily connected directly to the planar electrodes.

[0024] In some embodiments, contact surfaces of one power supply contact device may be arranged spaced apart from each other, in particular along their associated side faces.

[0025] This allows the voltage distribution to be very uniform at least near the contact surface.

[0026] In some embodiments, the distance between contact surfaces of one or more power supply contact devices varies along their extent. This allows further customization of the control voltage distribution within the liquid crystal device.

[0027] Liquid crystal devices, in particular liquid crystal windows, can be used for sustainable glazing applications in buildings and vehicles, in particular by providing energy savings in lighting, cooling and / or heating, and by positively influencing the life cycle, for example in terms of maintenance, while additionally providing improved thermal and visual comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features and variations of the present invention will be apparent to those skilled in the art, particularly from the accompanying drawings which illustrate exemplary embodiments of the invention. The accompanying drawings show:

[0029] Figure 1 is a top view of a liquid crystal device according to an embodiment of the present invention;

[0030] Figure 2 It is along Figure 1 Line II-II passes through a cross section of the liquid crystal device;

[0031] Figure 3 is a top view of a liquid crystal device according to an embodiment of the present invention;

[0032] Figure 4 is a top view of a liquid crystal device according to an embodiment of the present invention; and

[0033] Figure 5 is a top view of a liquid crystal device having unevenly spaced contact surfaces according to an embodiment of the present invention.

[0034] The drawings contain partially simplified schematic representations. In part, the same reference numerals are used for similar but possibly different elements. Different views of the same element may be scaled differently. Directional indications such as "left", "right", "top", "upper" and "bottom" should be understood with reference to the corresponding drawings and may vary in each representation with respect to the depicted object.

[0035] Furthermore, the elements are not necessarily shown to scale relative to each other, particularly in order to simplify and clearly illustrate their functional relationships. Whenever process steps or elements have enumerated names, such as "first," "second," "third," or "further," these names are used only for distinction and do not imply any order or hierarchy unless otherwise explicitly disclosed.

[0036] exist Figure 1 , 3 , 4 and 5, features that are visible through the transparent portion but are arranged on the surface facing away from the observer are drawn using dashed lines. DETAILED DESCRIPTION

[0037] like Figure 1 and 2 The liquid crystal device 10 shown includes an active layer 12 arranged between a first planar electrode 14 and a second planar electrode 16. The active layer 12 and the planar electrodes 14, 16 are in contact with each other. The first planar electrode 14 is carried on a first transparent carrier 18, and the second planar electrode 16 is carried on a second transparent carrier 20. The active layer 12, the planar electrodes 14, 16 and the transparent carriers 18, 20 are flat, meaning that their range in the extended common plane (common plane of extent) or parallel to the extended common plane is significantly greater than their range perpendicular to the plane. The active layer 12, the planar electrodes 14, 16 and the transparent carriers 18, 20 are stacked together so that they form a viewport 30, the transparency and / or translucency of the viewport can be controlled by a control voltage applied to the planar electrodes 14, 16. When the liquid crystal device 10 is transparent, those surfaces of the active layer 12 that should be seen through are also the surfaces of the active layer 12 in contact with the planar electrodes 14, 16. These surfaces of the active layer 12 can thus be identified as a first viewport surface in contact with the first planar electrode 14 and a second viewport surface in contact with the second planar electrode 16 .

[0038] The other side surfaces of the active layer 12 form side surfaces oriented in other directions, for example, toward Figure 1 In many embodiments, the side surface is oriented perpendicular to the viewport surface. For example, Figure 1 The substantially rectangular liquid crystal device 10 shown may have four side surfaces. The entire side surface may also be referred to as the perimeter of the active layer 12.

[0039] In many embodiments, the active layer 12 may include an optically active material (generally controllable by an electric field applied thereto), such as a liquid crystal. In some embodiments, the active layer 12 may include other materials in addition to the optically active material. For example, the active layer 12 may include a glue component on its side surface that surrounds the optically active material, for example to protect it from external influences such as dust, or to prevent the optically active material, which may be liquid, from flowing out between the transparent carriers 18, 20. The active layer 12 may also include spacers that are arranged to ensure that the distance between the transparent carriers 18, 20 and / or the planar electrodes 14, 16 is uniform across the viewport 30.

[0040] In some embodiments, the planar electrodes 14, 16 can include multiple layers, such as any combination of alignment layers, insulating layers, conductive layers, barrier layers, and / or any other desirable layers.

[0041] The first transparent carrier 18 and the portion of the first planar electrode 14 protrude parallel to the plane of extent on one side surface of the active layer 12 to form a first power supply region 22. The second transparent carrier 20 and the portion of the second planar electrode 16 protrude parallel to the plane of extent on the other side surface of the active layer 12 to form a second power supply region 24. The first power supply contact device 26 is arranged to be in electrical contact with the first planar electrode 14 in the first power supply region 22 to provide a control voltage to the first planar electrode 14. The second power supply contact device 28 is arranged to be in electrical contact with the second planar electrode 16 in the second power supply region 24 to provide a control voltage to the second planar electrode 16.

[0042] The control current flows through the planar electrodes 14, 16 to the active layer 12, which acts as an insulator and / or dielectric, forming a capacitor between the planar electrodes 14, 16. By charging / discharging the capacitor, a control voltage (or more specifically, a control voltage gradient) is established across the electrodes 14, 16 on the active layer 12. The power supply contact devices 26, 28 are each elongated to extend along the power supply areas 22, 24, and thus extend along the planar electrodes 14, 16 and the active layer 12 side. They are arranged to form electrical contact with the power supply areas 22, 24 so that the control current is distributed over their range.

[0043] Due to the rectangular base of the active layer 12, the power supply areas 22, 24 and the power supply contact devices 26, 28 are arranged substantially at right angles relative to each other. In some embodiments, the power supply contact devices 26, 28 can be arranged to encompass any angle between them, in particular an angle between 45° and 135°, between 75° and 105°, between 85° and 95°, or between 89° and 91°.

[0044] The supply areas 22, 24 are arranged on adjacent sides of the active layer 12 to allow a simplified production of the liquid crystal device 10. If the supply contact devices 26, 28 are arranged on adjacent sides of the active layer 12, the production machine for producing the liquid crystal device 10 can be simplified and automated to a higher degree. In particular, this is due to the simplified access to those sides and edges of the active layer 12 which do not have supply areas 22, 24 arranged next to them.

[0045] In the presently described embodiment, the active layer 12 extends in a rectangular manner, forming a rectangular substrate having four side surfaces, wherein its four sides are not covered by one of the planar electrodes 14, 16 and are therefore open for arranging thereon the power supply regions 22, 24. In some embodiments, the active layer 12 may be formed differently, for example with a non-rectangular four-sided substrate, a substrate with more than four open sides, five sides, six or more sides, or one or more non-flat sides (e.g., curved sides, elliptical sides, or rounded sides).

[0046] The first power supply contact device 26 comprises a plurality of first contact surfaces 38 and the second power supply contact device 28 comprises a plurality of second contact surfaces 40. The contact surfaces 38, 40 are electrically connected to the planar electrodes 14, 16 to distribute the control current for generating the control voltage over a larger surface of the planar electrodes 14, 16 than would be possible for a simple solder joint. In this way, the current density and the resistive losses are thus reduced.

[0047] The control voltage is provided to the power supply contact devices 26, 28 via the first cable device 42 and the second cable device 44. The cable devices 42, 44 can be connected (in particular welded) to one or more of the contact surfaces 38, 40. In some embodiments, the cable devices 42, 44 can be provided with a material that allows them to directly contact the planar electrodes 14, 16 and thus become part of the power supply contact devices 26, 28. The cable devices 42, 44 can be further extended to be connected to control devices outside the scope of the present application. In particular, the cable devices 42, 44 can extend along the side surfaces associated with the power supply areas 22, 24 and / or the power supply contact devices 26, 28 to the corners adjacent to the associated side surfaces.

[0048] In some embodiments (one of which is in Figure 3 ), one of the power supply contact devices 26, 28 is, in this embodiment, the second power supply contact device 28, which can be spaced apart from the other (in this embodiment, the first) power supply contact device 26. Therefore, when a corner of the active layer 12 is enclosed between the power supply contact devices 26, 28, one of the power supply contact devices 26, 28 can be arranged closer to the corner than the other.

[0049] In particular, the side surface of the active layer 12 on which the first power supply contact device 26 is arranged can have a length n, wherein the first power supply contact device 26 is separated from the second corner and / or the second power supply contact device 28 by a gap 32 of length g, and the length of the gap 32 can be, for example, between 10% and 80%, between 20% and 70%, or at most 10%, 20%, 30%, 40%, 50% or 60% of n.

[0050] In some embodiments (one of which is Figure 4 ), one or more of the power supply contact devices 26, 28 may have a length of, for example, between 40% and 90%, between 70% and 90%, less than 50%, less than 60%, less than 70%, less than 80%, less than 85% or less than 90% of n. In some embodiments, the power supply contact devices 26, 28 may be arranged adjacent to each other or separated by a minimum gap 32 of less than 5% of n. In addition, supplementary power supply areas, such as a third power supply area 34 and / or a fourth power supply area 36, ​​may be provided to allow the first power supply contact device 26 and / or the second power supply contact device 28 to be arranged.

[0051] In particular, the power supply contact devices 26, 28 can each be arranged at a corner and associated with two side surfaces, each covering a portion of two power supply areas 22, 24, 34, 36. In some embodiments, the arrangement of the power supply contact devices 26, 28 can be asymmetric. For example, in an arrangement including an active layer 12 having five side surfaces, it may be convenient to associate a first power supply contact device 26 with one of the side surfaces and two second power supply contact devices 28 with adjacent side surfaces. Many other such arrangements are possible. It is also possible to have a configuration in which there is a first power supply contact device 26 and one, two or three second power supply contact devices 28 are provided. In addition, it is possible to have a configuration in which, of the five side surfaces, two are associated with the first power supply contact device 26, three are associated with the second power supply contact device 28, or in a different configuration, four are associated with the first power supply contact device 26 and one is associated with the second power supply contact device 28.

[0052] In some embodiments, the first power supply region 22 and / or the second power supply region 24 may protrude on the side surface in a substantially rectangular manner.

[0053] In some embodiments, the active layer 12 can be sandwiched between the first planar electrode 14 and the second planar electrode 16. In some embodiments, multiple active layers 12 can be stacked one on top of another and separated, for example, by transparent carriers 18, 20 of different thicknesses. For example, the outermost transparent carriers 18, 20 can have a larger thickness to provide support to the layers therebetween, while the transparent carriers 18, 20 arranged between the active layers 12 can be thinner to avoid making the liquid crystal device 10 too heavy.

[0054] In some embodiments (one of which is Figure 5 ), when the first power supply contact device 26 includes a plurality of first contact surfaces 38 and / or the second power supply contact device 28 includes a plurality of second contact surfaces 40, it may be helpful not to arrange the contact surfaces 38, 40 at uniform spacing. For example, the spacing between the contact surfaces 38, 40 may decrease as they are further from the angle at which the adjacent associated side surfaces intersect. Figure 5 In the illustrated case, the distance between the contact surface 38 closest to the gap 32 and the next contact surface 38 to its left is greater than the distance between the contact surface 38 to its left, and so on until the last contact surface 38 .

[0055] In order to determine which of the embodiments shown above, for example, is most useful for a particular liquid crystal device 10, and also to determine, for example, the length g of the gap 32, current and voltage distribution simulations can be used, the simulations using FEM (finite element model) representations of the electrical characteristics of the active layer 12, the first planar electrode 14, and the second planar electrode 16. The selection of a particular embodiment may also depend on other factors, for example, an active layer 12 with an aspect ratio far from 1 (e.g., 0.2 or 5) may require a larger gap 32. In addition, relatively large active layers 12 (e.g., those with one side longer than 1 m, 1.5 m, or 2 m) may require a larger gap 32. The selection of a suitable size for the gap 32 may also depend on the electrical characteristics of the active layer 12 and the planar electrodes 14, 16. In particular, the dielectric constant of the active layer 12, the sheet resistance of the conductive coating of which the planar electrodes 14, 16 are made, the cell gap within a specific range, and / or the capacitance or RC constant of the liquid crystal device 10 may all affect which embodiment and what gap size may be most advantageous to use.

[0056] In general, implementations and parameters are chosen to achieve features that are as uniform as possible across viewport 30. Specifically, if features of liquid crystal device 10 across viewport 30 are less than uniform, this will be visible as lighter or darker areas and a generally non-uniform aspect of liquid crystal device 10 in use.

[0057] In some embodiments, all or some of the power supply contact devices 26 , 28 may be shorter than their respective power supply areas 22 , 24 .

[0058] In some embodiments, the first cable device 42 and the second cable device 44 can be formed as a so-called bus bar, connecting only their respective connection surfaces 38, 40 (eg Figure 3 In some embodiments, as shown in FIG. Figure 4 and Figure 5 As shown, the cable arrangements 42, 44 may extend to a common corner where they may be readily connected to external control circuitry.

[0059] In general, the side surface may be limited by the edge of the limit of the side surface that intersects at its position. In some embodiments, the limit of the side surface can be defined by the place where the surface normal gradient value of the side surface exceeds a predetermined threshold. Such a place can be, for example, a straight edge, such as an edge where the surface intersects at a right angle (or any other angle), or a rounded edge, wherein the radius of the rounded edge is less than, for example, 5 mm, 1 mm, or 0.1 mm.

[0060] Optional features of the present invention are indicated by "may." Therefore, there are further embodiments of the present invention and / or embodiments which additionally or alternatively have one or more corresponding features.

[0061] From the combination of features currently disclosed, if necessary, independent features may be selected and used in combination with other features to define the subject matter of the claims while eliminating possible structural and / or functional relationships between the features.

[0062] refer to

[0063] 10 LCD equipment

[0064] 12 Active layer

[0065] 14 First plane electrode

[0066] 16 Second plane electrode

[0067] 18 The first transparent carrier

[0068] 20 second transparent carrier

[0069] 22First power supply area

[0070] 24 Second power supply area

[0071] 26First power supply contact device

[0072] 28 Second power supply contact device

[0073] 30 Viewports

[0074] 32 Gap

[0075] 34Third power supply area

[0076] 36 Fourth power supply area

[0077] 38 first contact surface

[0078] 40 second contact surface

[0079] 42 First Cable Equipment

[0080] 44 Second Cable Equipment

Claims

1. A liquid crystal device (10) for absorbing and / or scattering a controllable amount of passing light, comprising an active layer (12) having a first viewport surface and a second viewport surface, wherein the first viewport surface is in contact with a first planar electrode (14) and the second viewport surface is in contact with a second planar electrode (16), wherein The active layer (12) comprises at least two side surfaces, wherein The first planar electrode (14) comprises a first power supply region (22) for receiving a control voltage for controlling the active layer (12), and the second planar electrode (16) comprises a second power supply region (24) for receiving the control voltage, wherein A first power supply contact device (26) is arranged to be electrically connected to the first power supply area (22), and a second power supply contact device (28) is arranged to be electrically connected to the second power supply area (24), wherein The power supply areas (22, 24) are each associated with one or more side surfaces, wherein the power supply contact devices (26, 28) are each associated with one or more side surfaces and are arranged to extend along at least a portion of the side surfaces to which they are respectively associated, wherein a first power supply contact device (26) and a second power supply contact device (28) are associated with adjacent side surfaces.

2. The liquid crystal device according to claim 1, characterized in that One or more of the contact devices (26, 28) extend less than 90%, 85%, 80%, 75%, 70%, 65%, 60%, 50%, 40%, 30%, 20% or 10% of the length of its associated side surface of the active layer (12).

3. The liquid crystal device according to claim 1 or 2, characterized in that: The first power supply contact device (26) is spaced apart from a side surface associated with the second power supply contact device (28) and / or the second power supply contact device (28).

4. A liquid crystal device according to any one of the preceding claims, characterized in that The first planar electrode (14) comprises a third supply region (34), and / or the second planar electrode (16) comprises a fourth supply region (36), each portion extending along one of the previously unassociated side surfaces.

5. The liquid crystal device according to claim 4, characterized in that The first power supply contact device (26) at least partially extends over the third power supply area (34) and is in electrical contact therewith, and / or the second power supply contact device (28) at least partially extends over the fourth power supply area (36) and is in electrical contact therewith.

6. A liquid crystal device according to any one of the preceding claims, characterized in that The active layer (12) includes at least four side surfaces.

7. A liquid crystal device according to any one of the preceding claims, characterized in that One of the power supply areas is longer than 1.5 m.

8. A liquid crystal device according to any one of the preceding claims, characterized in that At least one of the power supply contact devices is discontinuous in that it comprises a plurality of contact surfaces which are not in direct contact with each other.

9. The liquid crystal device according to claim 8, characterized in that The contact surfaces of one current supply contact device are arranged spaced apart from one another, in particular along their associated side faces.

10. The liquid crystal device according to claim 9, characterized in that The distance between the contact surfaces of one or more of the power supply contact devices varies along their extent.

Images