Electric Wetting Display

Abstract

The present invention generally relates to electro-wetting optical components. In a first aspect of the present disclosure, the above-mentioned problems are solved by the following electro-wetting optical component. The electro-wetting optical component is configured to apply power to a first electrode layer and a second electrode layer to reconfigure a polar liquid and a non-polar liquid on a hydrophobic surface of an insulating layer, the electro-wetting optical component comprising: a first electrode layer stack including a substrate, the first electrode layer, and the insulating layer having a first hydrophobic interface; a second electrode layer stack including a superstrate and the second electrode layer having a second interface less hydrophobic than the first hydrophobic interface; one or more cell walls extending between the first electrode layer stack and the second electrode layer stack; and a second electrode layer stack including a first electrode layer and a second electrode layer having a second interface less hydrophobic than the first hydrophobic interface. a storage space formed between the first hydrophobic boundary surface of the layer stack, the second boundary surface of the second electrode layer stack, and the one or more cell walls defining sides of the storage space, wherein the storage space comprises a polar liquid and a non-polar liquid, the polar liquid and the non-polar liquid being immiscible with each other, each of the one or more cell walls being fixedly attached to the second boundary surface of the second electrode layer stack and extending toward the first electrode layer, and an end face of each of the one or more cell walls facing the opposite side to the first electrode layer stack comprising a hydrophobic surface.

Description

[Technical Field]

[0001] The present invention relates generally to electro-wetting optical components, and more particularly to an electro-wetting optical component configured to apply power to first and second electrode layers to reconfigure polar and non-polar liquids on a hydrophobic surface of an insulating layer, the electro-wetting optical component comprising: a first electrode layer stack including a substrate, a first electrode layer, and an insulating layer having a first hydrophobic interface; a second electrode layer stack including a superstrate and a second electrode layer having a second interface that is less hydrophobic than the first hydrophobic interface; one or more cell walls extending between the first and second electrode layer stacks; and a storage space formed between the first hydrophobic interface of the first electrode layer stack, the second interface of the second electrode layer stack, and the one or more cell walls that define sides of the storage space, the storage space comprising a polar liquid and a non-polar liquid, wherein the polar and non-polar liquids are immiscible with each other.

[0002] The invention further relates to a method for producing such an electrowetting optical component. [Background technology]

[0003] The electrowetting technique is based on changing the effective wettability of the hydrophobic surface of an insulating layer with respect to a polar liquid relative to a non-polar liquid by varying the strength of an electric field applied to the insulating layer. The insulating layer, polar liquid, and non-polar liquid then become part of a capacitor assembly. The capacitor assembly comprises electrodes between which a voltage can be applied to create an electric field across the insulating layer.

[0004] A conventional electro-wetting optical component (also referred to as an electro-wetting component) includes a first electrode layer stack at the bottom. The first electrode layer stack includes a substrate, a first electrode layer, and an electrically insulating hydrophobic layer (or insulating layer) having a hydrophobic surface. The hydrophobic surface is opposite the first electrode layer and forms a boundary between the immiscible polar and non-polar liquids in the storage space. A conventional electro-wetting optical component (also referred to as an electro-wetting component) includes a second electrode layer stack at the top. The second electrode layer stack includes a second electrode layer and a superstrate. The second electrode layer forms a boundary with at least the polar liquid in the storage space. The first electrode layer stack at the bottom of the electro-wetting optical component can be considered a first stack including the first electrode layer. The second electrode layer stack at the top of the electro-wetting optical component can be considered a second stack including the second electrode layer. A storage space containing the polar and non-polar liquids separates the first and second stacks.

[0005] The electro-wetting component thus comprises, at its bottom, a first electrode layer, an electrically insulating hydrophobic layer (i.e., a layer having a hydrophobic surface opposite the first electrode layer), and a liquid mixture comprising at least a polar liquid and a non-polar liquid on its surface. The electro-wetting component then comprises a second electrode layer in contact with at least the polar liquid. In practice, this liquid is contained in a containment space formed, for example, between the cell walls, i.e., between the hydrophobic surface of the insulating layer and the electrode on the superstrate glass plate.

[0006] Such an electro-wetting component is disclosed in U.S. Patent No. 9,274,331 B2, which has the same inventor as the present application. The electro-wetting component disclosed therein is configured to apply power to first and second electrode layers to reconstitute a polar liquid into a non-polar liquid, and includes a first electrode layer stack, a second electrode layer stack, and a cell wall. The first electrode layer stack is disposed at the bottom of the electro-wetting optical component and includes a substrate, a first electrode layer, and an insulating layer having a hydrophobic first interface. The second electrode layer stack is disposed at the top of the electro-wetting optical component and includes a superstrate, a second electrode layer having a second interface less hydrophobic than the first hydrophobic interface, and an insulating layer. The cell wall is disposed to extend between the first and second electrode layer stacks. The space between the first hydrophobic interface and the second interface includes the cell wall and a storage space. The storage space stores immiscible polar and non-polar liquids.

[0007] The cell walls of the electrowetting optical element disclosed in U.S. Patent No. 9,274,331 B2 are fixed to the second boundary surface of the second electrode layer stack. The cell walls extend toward the first electrode layer but are not fixed to the first hydrophobic boundary surface of the first electrode layer stack. The tops (i.e., the unfixed free ends) of the cell walls comprise a hydrophobic surface.

[0008] With this hydrophobic end of the cell wall, non-polar liquids are not attracted to either the hydrophobic end face of the cell wall or the hydrophobic first interface, regardless of whether power is applied to the electrowetting cell. Therefore, non-polar liquids can more easily pass through the slit between the cell wall end face and the first hydrophobic interface. This effectively traps the polar liquid within the containment space, preventing it from diffusing from one cell to the other.

[0009] In general, forming a hydrophobic surface on the top or free end of a cell wall can prevent or reduce the transport of polar liquids from one cell to the other. To fabricate such a hydrophobic structure on the top, an annealing step is required. This annealing step reduces the hydrophilicity of the cell wall side. As a result, nonpolar liquids stick to the cell wall side. This prevents (or reduces) the backflow of nonpolar liquids from the cell wall side to the first hydrophobic interface when the electrowetting cell is switched from a power-on state (a state in which a voltage is applied to the first and second electrode layers) to a power-off state (a state in which no voltage is applied to the first and second electrode layers). As a result, the electrowetting effect becomes less reliable. Summary of the Invention [Problem to be solved by the invention]

[0010] SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above problems and drawbacks of the prior art, and in particular to provide an improved electro-wetting optical component with a more reliable electro-wetting effect.

[0011] It is also an object of the present invention to provide a method for manufacturing such an electrowetting optical component. [Means for solving the problem]

[0012] In a first aspect of the present disclosure, the above-mentioned problems are solved by the following electro-wetting optical component: The electro-wetting optical component is configured to apply power to a first electrode layer and a second electrode layer to reconfigure a polar liquid and a non-polar liquid on a hydrophobic surface of an insulating layer, a first electrode layer stack comprising a substrate, a first electrode layer and an insulating layer having a first hydrophobic interface; a second electrode layer stack comprising a superstrate and a second electrode layer having a second boundary surface that is less hydrophobic than the first hydrophobic boundary surface; one or more cell walls extending between the first and second electrode layer stacks; a storage space formed between a first hydrophobic boundary surface of the first electrode layer stack, a second boundary surface of the second electrode layer stack, and one or more cell walls defining sides of the storage space; Equipped with the storage space includes a polar liquid and a non-polar liquid; Polar and non-polar liquids are immiscible with each other, each of the one or more cell walls is fixedly attached to a second interface of the second electrode layer stack and extends toward the first electrode layer; An end face of each of the one or more cell walls opposite the first electrode layer stack comprises a hydrophobic surface.

[0013] One or more cell walls of the proposed electrowetting optic further comprise an end face facing the first electrode layer stack and a hydrophilic surface that interfaces with the polar and non-polar liquids in the containment space.

[0014] The operating principle of an electrowetting optical element is as follows. When no power is applied, i.e., when the first and second electrodes are in a power-off state (i.e., when no voltage is applied between the first and second electrodes), the system is in its lowest energy state, and the nonpolar liquid does not form a boundary layer between the polar liquid and the hydrophobic surface of the insulating layer. This is because the nonpolar liquid preferentially wets the hydrophobic surface. As a result, the polar liquid is effectively repelled from its interface with the hydrophobic surface. Assuming that the nonpolar liquid is optically absorbing in at least a portion of the visible light range, the optical absorption of the nonpolar liquid creates an obstacle to the incident light entering the system. This results in an electrowetting optical element with reduced optical transparency in at least a portion of the visible light range. When a voltage is applied between the first and second electrodes, an electric field is established between the first electrode and the conductive polar liquid across the combined thickness of the insulator layer and the nonpolar liquid. The force exerted by the electric field changes the system's lowest energy state to one in which the nonpolar liquid (which has low electrical conductivity or is insulating) is pushed next to the polar liquid (which is conductive). If the applied voltage is high enough, the hydrophobic surface becomes preferentially wetted by the polar liquid, which displaces the nonpolar liquid significantly from the hydrophobic surface. Inside the electrowetting cell, the shape of the displaced nonpolar liquid changes from a lenticular liquid film to a contracted droplet. In this state, assuming the polar liquid is substantially non-optically absorbing in the visible range, the rate at which incident light entering the system is absorbed by the nonpolar liquid decreases. This increases the optical transparency of the incident light to the electrowetting optical component.

[0015] When the electrodes are switched from the power-on state to the power-off state by removing the voltage applied between them, the electric field distributed across the insulating layer during the power-on state disappears. The system returns to its lowest energy state. The hydrophobic surface is preferentially wetted by the non-polar liquid in the film. As a result, the polar liquid migrates away from the hydrophobic surface of the insulating layer.

[0016] In both the powered-on and powered-off states, the liquid remains within the cell (especially near the cell walls).

[0017] A set of cell walls that form the boundaries of the cell, together with the first and second electrode stacks, create a storage space. In this disclosure, this storage space is considered to be the smallest element when polar and non-polar liquids exhibit an electrowetting effect. At least one cell (but preferably multiple cells) forms an individual pixel. This pixel is considered to be the smallest element of an addressable display. Thus, in this disclosure, a pixel element includes at least one electrowetting cell. A pixel may include any number of cells greater than one (e.g., an even or odd number).

[0018] A cell wall is formed on the second electrode layer stack (or on the superstrate). Such cell walls are known from previous generations of electrowetting elements and have been disclosed in previous patent applications by the applicant (see background art herein). The height of the cell wall is sufficient to prevent the polar liquid from diffusing and leaking from cell to cell as the cell wall extends from the second electrode layer stack to the first electrode layer stack.

[0019] In known electrowetting components, the tops of the extended cells are made hydrophobic by fabricating them using a process that involves coating the top cell walls with a hydrophobic material followed by an annealing step. However, this annealing step reduces the hydrophilicity of the cell wall sides, which increases their wettability with non-polar liquids at the expense of their wettability with polar liquids, causing the non-polar liquid to stick to the cell wall sides. This results in the hydrophobic surface of the insulating layer being covered by the non-polar liquid in the power-off state, resulting in incomplete coverage and / or a reduced backflow rate of the non-polar liquid over the hydrophobic surface of the insulating layer.

[0020] To solve this, the annealing step may be optimized with other alternative steps or eliminated, but this may have other disadvantages and may reduce efficiency. Another alternative is to restore the hydrophilicity of the lateral surfaces after the annealing step by introducing one or more additional steps into the manufacturing process, but these steps may have other disadvantages and the addition of steps may increase manufacturing complexity, time, and cost.

[0021] The inventors have realized that, to overcome the above drawbacks, the tops of the extended cell walls can be made hydrophilic. Such cell walls improve the electrowetting effect of the electrowetting component and make it stable in a wider range of environments. The hydrophilic tops of such cell walls eliminate the need for the annealing step required in the fabrication of known electrowetting elements. As a result, the hydrophilicity of the side surfaces of the cell walls can be prevented from decreasing. In this way, the electrowetting element is improved and a more reliable electrowetting effect can be achieved.

[0022] In one example, the one or more cell walls are fixedly attached to the second boundary surface, with their free ends extending toward the first electrode layer, and the height of the one or more cell walls when the first and second electrode layers are powered off is greater than the maximum distance between the first electrode layer and the boundary between the polar liquid and the non-polar liquid.

[0023] In the prior art, removing the hydrophobic tops of the cell walls and replacing them with hydrophilic tops facilitates the migration of polar liquids from one cell to another. However, when the cell walls extend substantially along the gap between the first and second electrode layer stacks (more specifically, along the gap between the first and second interfaces), the effect of facilitating the migration of polar liquids from one cell to another is effectively eliminated. When polar liquids migrate into adjacent cells, the ratio of the amount of polar liquid to the amount of non-polar liquid in one cell changes, thus increasing the risk of non-polar liquids flowing into adjacent cells. This results in non-uniform distribution of the non-polar liquid within cells constituting a single pixel and / or across different pixels. If the non-polar liquid is a colored liquid, the non-uniform distribution of the non-polar liquid in the pixel region or the pixel assembly region constituting the display results in non-uniform distribution of color throughout the pixel region and / or the display region.

[0024] In one example, the height of the one or more cell walls extending from the second interface corresponds to the spacing between the first hydrophobic interface and the second interface.

[0025] If the cell walls are made taller, i.e. if the cell walls extend further towards the first interface, the risk of polar liquid migrating from one cell to the other can be avoided or further reduced.

[0026] In one example, an end surface of each of the one or more cell walls that forms the top surface of the cell wall loosely abuts the first hydrophobic interface.

[0027] In one example, an end surface of each of the one or more cell walls forming a top surface of the cell wall abuts the first hydrophobic interface, thereby forming a sealing contact between the top surface of the cell wall and the first hydrophobic interface to encapsulate the polar liquid and the non-polar liquid within the containment space.

[0028] In a preferred embodiment, the cell wall is attached to and forms an integral part of the second boundary surface. The opposite side of the cell wall faces the first boundary surface or layer and has a free end. This free end is adjacent to the first boundary surface. Preferably, this abutment is sealingly formed. In this case, a sealing contact is formed between the top of the cell wall and the first boundary surface. This encapsulates the polar and non-polar liquids within the storage space.

[0029] In one example, one or more cell walls comprise the compressible mixture, and in particular at least the top of the cell wall comprises the compressible mixture.

[0030] Achieving a sealed contact in a wide environment is difficult. Under real, unsimulated conditions, high or low temperatures affect the seal. Making the cell walls partially or completely from a compressible compound improves the seal because the cell walls can be made slightly larger. When the second stack is closed or sandwiched between the cell walls, they are slightly compressed against the first stack, acting as a gasket. In this case, the interface between the top of the cell wall and the first interface can have some imperfections. These imperfections are filled and compensated for by the compression of the cell walls.

[0031] In one example, one or more cell walls contain the expandable mixture, and in particular at least the top of the cell walls contain the expandable mixture.

[0032] Instead of compression, the cell walls (whether in whole or in part) may be configured to expand (e.g., only the tops of the cell walls), and those skilled in the art will understand that such materials or mixtures are suitable.

[0033] In a further example, the expansion of an expandable mixture or the compression of a compressible mixture is achieved by one or more cell walls, or in particular by at least the top part of the cell walls having a porous structure.

[0034] The expansion of the expandable mixture is achieved by one or more cell walls, or at least the top portion of the cell walls, which are specifically configured to absorb polar liquids. The expansion involves preferential absorption of the liquid by chemical solvation within the cell walls.

[0035] Preferably, the effect of the cell walls expanding is achieved (at least in part) by a porous structure or at least a structure that absorbs liquid and expands in volume due to such absorption, such cell walls ensuring improved sealing of the containment space in the presence of absorbed liquid.

[0036] In another example, the porous structure includes pores configured to absorb liquid when one or more cell walls, or in particular at least the top of the cell walls, are immersed in the liquid.

[0037] Preferably, the cell walls are configured to have a height slightly less than the distance between the first and second boundary surfaces, so that the cell walls, or at least their tops, are immersed in the liquid which has an absorbing effect at the cell walls (tops).

[0038] In one example, the liquid bathing one or more cell walls, or particularly at least the top of the cell walls, comprises a polar liquid.

[0039] In one example, the immersion of one or more cell walls, or particularly at least the top of the cell walls, is performed at an elevated temperature of the liquid for a predetermined period of time.

[0040] In one example, each side of the one or more cell walls includes a hydrophilic surface.

[0041] In one example, both the side and end faces of each of the one or more cell walls include a hydrophilic surface.

[0042] In one example, the hydrophilic surfaces of the side and end faces are formed in a continuous layer.

[0043] In a second aspect, a method for manufacturing an electro-wetting optical element is provided, the method comprising applying electrical power to a first electrode layer and a second electrode layer to reconfigure a polar liquid and a non-polar liquid, the method comprising: - providing a second electrode layer stack comprising a superstrate and a second electrode layer having a second interface; - fixedly attaching a cell wall to a second boundary surface of the second electrode layer stack, thereby forming a containment space defined by the second boundary surface and the cell wall; - filling the containment space with a polar liquid and a non-polar liquid; - covering the storage space with a first electrode layer stack comprising a substrate, a first electrode layer and an insulating layer having a first hydrophobic interface; Including, an end face of the cell wall facing the first electrode layer stack includes a hydrophilic surface; The first hydrophobic interface is more hydrophobic than the second interface.

[0044] In a further embodiment, the free ends of the cell walls extend towards the first electrode layer; the height of the cell wall when the first electrode layer and the second electrode layer are powered off is greater than the maximum distance between the first electrode layer and the boundary between the polar liquid and the non-polar liquid; each end surface of the cell wall is in contact with a first hydrophobic boundary surface; A sealing contact is formed between the top surface of the cell wall and the first hydrophobic interface to encapsulate the polar liquid and the non-polar liquid within the containment space.

[0045] All examples described in relation to the first aspect of the invention are also applicable to the second aspect of the invention, and similarly all advantages and further examples of the first aspect are also applicable to the second and other aspects and examples thereof. [Brief explanation of the drawings]

[0046] The present invention will now be described in more detail with reference to the accompanying drawings. [Figure 1]1 is a schematic diagram of a prior art electrowetting optic; [Figure 2] FIG. 1 illustrates the unreliable effects of prior art electrowetting optics. [Figure 3] FIG. 1 illustrates another unreliable effect of prior art electrowetting optics. [Figure 4] 1 is a schematic diagram of an electro-wetting optical element according to a first embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0047] FIG. 1 is a schematic diagram of a prior art electrowetting optical component (also called an electrowetting component). This electrowetting optical component includes bottom and top electrode layer stacks. The bottom electrode layer stack is a first electrode layer stack and is composed of a substrate 12, a first electrode layer 13, and an electrically insulating hydrophobic or insulating layer 14 having a hydrophobic surface 15. The hydrophobic surface 15 forms a boundary with at least one nonpolar liquid 20. The nonpolar liquid 20 can displace a polar liquid 21 from the hydrophobic surface 15 by utilizing the preferential wetting phenomenon of the hydrophobic surface 15. These liquids are immiscible and are stored in a storage space. The storage space defines a cell and is formed by the first bottom stack, the second top stack, and a set of cell walls 16 (where the cell walls are arranged parallel to each other at a fixed distance).

[0048] The second electrode layer 11 of the superstrate 10 and the first electrode layer 13 of the substrate 12 can be formed to apply a voltage to only one cell, but preferably can be continuous to multiple cells as shown in Figure 1. In this way, multiple cells can form a single pixel element that can be addressed independently of each other.

[0049] The electro-wetting optic of FIG. 1 further comprises a second electrode layer stack consisting of a second electrode layer 11 and a superstrate 10. The second electrode layer 11 forms a boundary with at least a polar liquid 21 in the containment space. As shown, the first electrode layer stack at the bottom of the electro-wetting optic may be considered a first stack comprising a first electrode layer. The second electrode layer stack at the top of the electro-wetting optic may be considered a second stack comprising a second electrode layer. A containment space containing a polar liquid and a non-polar liquid separates the second stack from the first stack.

[0050] To define the cells and retain the liquid within the cells of the containment space, the electrowetting optic includes cell walls 16. These cell walls are fixedly attached to one end 17 of the second interface 11 of the second electrode layer stack. The opposite end 19 of the cell wall is not fixedly attached to the first interface 15 of the first electrode layer stack, but is a free, unfixed end 19. This free end has a hydrophobic top 19. A nonpolar liquid 20 is attracted to both the hydrophobic end 19 of the cell wall 16 and the hydrophobic first interface 15 in both the powered-on and powered-off states of the electrowetting cell. As a result, the nonpolar liquid 20 can more easily pass through the slit between the end 19 and the first interface 15. As a result, the polar liquid 21 is efficiently trapped within the containment space and prevented from diffusing from one cell to the other. To provide such a hydrophobic surface on the tops and free ends 19 of the cell walls 16 requires a coating step with a hydrophobic material followed by an annealing step.

[0051] This annealing step reduces the hydrophilicity of the side surface 18 of the cell wall 16. As a result, the non-polar liquid 20 sticks to the side surface 18 of the cell wall 16. This prevents (or slows down) the backflow of the non-polar liquid 20 from the cell wall side surface 18 to the first hydrophobic interface 15 when the electro-wetting component is switched from a powered-on state to a powered-off state of the first and second electrode layers. As a result, the reliability of the electro-wetting effect is reduced. This effect is clearly shown in FIG. 2, where the electro-wetting component is in a powered-off state and no voltage is applied between the first electrode 11 and the second electrode 13. For the most efficient optically absorbing liquid film, when the non-polar liquid 20 is optically absorbing (at least partially) in the visible wavelength range, as shown in the powered-off state of the electro-wetting component in FIG. 1, the non-polar liquid 20 is preferably evenly distributed across the first interface 15 within the cell as a lenticular liquid film. However, in Figure 2, the non-polar liquid 20 in the prior art electro-wetting optical component climbs up the sides of the cell walls 16 because the increased hydrophobicity of the cell walls 16 due to annealing improves the wetting properties of the non-polar liquid 20. As a result, as shown in Figure 2, the distribution of the non-polar liquid 20 on the cell becomes uneven, reducing the reliability and reproducibility of the electro-wetting effect. Because some of the non-polar liquid 20 in the cell climbs up the sides of the cell walls 16, the hydrophobic first interface becomes unevenly covered with optically absorbing non-polar liquid 20, resulting in an undesirable increase in the optical transmittance of the incident light passing through the cell.

[0052] 3 shows a more extreme example of an unreliable electrowetting effect in the power-off state, where most of the non-polar liquid 20 sticks to the cell walls 16. Thus, most of the non-polar liquid 20 is away from the hydrophobic first interface 15. As a result, even if the non-polar liquid 20 is at least partially optically absorbing in the visible light range, incident light passes through the cell largely unobstructed, which is undesirable.

[0053] FIG. 4 illustrates an electro-wetting optical component according to an embodiment of the present disclosure. The electro-wetting optical component is configured to apply power to a first electrode layer 13 and a second electrode layer 11 to reconstitute a polar liquid 21 relative to a non-polar liquid 20 on a hydrophobic interface 15 of an insulating layer 14. The electro-wetting optical component includes a first electrode layer stack including a substrate 12, a first electrode layer 13, and an insulating layer 14 having a first hydrophobic interface 15. The substrate 12 may be made of glass or other substrate material transparent in the visible light range. An interface or layer covers the transparent first electrode layer 13. The interface layer 15, or at least its surface, is preferably made of a fluoropolymer. To enhance adhesion of the fluoropolymer 15 to the insulating layer 14, the substrate 12 is preferably provided with an adhesion-promoting layer. This adhesion-promoting layer is disposed between the fluoropolymer 15 and the insulating layer 14.

[0054] The electrowetting optical component further comprises a second electrode layer stack including a superstrate 10 and a second electrode layer 11 having a second interface that is less hydrophobic than the first interface. Similar to the first substrate 12, the second substrate 10 (also referred to as the superstrate 10) may also be made of glass. The second electrode layer 11 is formed on top of the glass substrate as a transparent electrode. The second electrode layer 11 is made of an electrically conductive material (e.g., indium tin oxide). However, existing organic conductive materials may also be used to appropriately process the second interface, which is less hydrophobic than the hydrophobic interface 15 of the first electrode layer stack.

[0055] The electrowetting optical element may also include one or more cell walls. In this case, a set or plurality of cell walls may define a cell depending on the shape of the cell. These may be cubic, hexahedral, or other suitable shapes. The cell wall 16 extends between the first and second electrode layer stacks. A storage space is formed between the cell wall and the first and second electrode layer stacks. The storage space stores at least an immiscible polar liquid 21 and a non-polar liquid 20.

[0056] The storage space thus contains a polar liquid 21. While the polar liquid 21 may be any suitable liquid, water, glycol, glycerin, or mixtures thereof may be used as the polar liquid in embodiments of the present invention, as they are easily and inexpensively available. In addition to the polar liquid, the cell or storage space further contains a non-polar liquid 20. The polar and non-polar liquids are immiscible and form a polar-non-polar liquid interface. The oil used as the non-polar liquid 20 may be decane or other suitable liquids, such as mineral oil, animal and vegetable oils, high-boiling hydrocarbons, higher fatty acids, silicone liquids, and in particular alkanes such as octane, decane, dodecane, petrolatum, spindle oil, castor oil, olive oil, and liquid paraffin.

[0057] As shown in FIG. 4 , each cell wall is fixedly attached to the second electrode layer 11 of the second electrode layer stack, and its other end 19 is connected to the first electrode layer. The end face 19 of each of the one or more cell walls faces the first electrode layer stack and has a hydrophilic surface. This hydrophobic surface may be formed as a skin of the cell wall 16, and may or may not be continuous with the side surface 18 of the cell wall 16. However, the hydrophilic surface may be continuous with the entire cell wall 16. This results in a monolithic cell wall having hydrophilic properties, with the top 19 and side surface 18 of the cell wall 16 being formed with a hydrophilic surface.

[0058] The tops 19, or free ends, of the cell walls 16 are free and unfixed, at least prior to final assembly of the components, and are hydrophilic. This hydrophilicity causes the polar liquid 21 to tend to diffuse from one wall to the other. As a result, the non-polar liquid 21 tends to migrate to the other wall. This affects the volume ratio of polar to non-polar liquid in each wall, resulting in uneven distribution of the non-polar liquid. This reduces the reliability of the electro-wetting effect. Therefore, to avoid a reduction in the electro-wetting effect, it is desirable for the free ends 19 of the cell walls to form a sealed contact between the top surface of the cell wall and the interface 15 of the first electrode layer stack.

[0059] To form a reliable seal between the top 19 of the cell wall 16 and the boundary surface 15 of the first electrode layer stack, a portion of the cell wall 16, preferably the top 19 (which may be a thin layer formed as a skin on the top and / or the side 18 (or part of the side 18) near the top 19), is preferably made of a material that can expand under certain circumstances. Preferably, the expandable material is a water-absorbent material. A water-absorbent material is a material that can absorb liquid by solvation. This allows the water-absorbent material to expand. This expansion ensures an effective seal between the top 19 of the cell wall 16 and the boundary surface 15. The degree of expansion and swelling can be selected and defined by the amount or location of the water-absorbent material in the cell wall. For example, the cell wall may be made of a combination of water-absorbent and non-water-absorbent materials. In this case, the final absorbency is defined by the ratio of the two materials. However, more preferably, the water-absorbent material is disposed only on the top 19 of the cell wall 16. For example, the water-absorbing material may be positioned at 1, 2, 5, 10, 15, 20, 25, or 30% of the height of the cell walls 16, as viewed from the top. However, the degree of swelling or expansion may be defined by the time the cell walls 16 or their tops 19 are immersed in the liquid. The liquid to be absorbed is preferably a polar liquid 21 present in the storage space. The absorption of the liquid is preferably carried out at an elevated temperature of the liquid. This temperature increase can increase the absorption rate of the material and shorten the time required to reach a predetermined expanded volume. The expanded volume may be predetermined, for example, a volume corresponding to approximately 1, 2, 3, 4, 5, 7, or 10% of the height of the cell walls 16.

[0060] As will be appreciated by those skilled in the art, the present invention may be practiced in other ways than as described in the specific embodiments described above. Obvious variations of the disclosed embodiments and specific design choices will be apparent to those skilled in the art. The scope of the present invention is defined solely by the appended claims.

Claims

1. an electrowetting optic configured to apply power to a first electrode layer and a second electrode layer to reconfigure a polar liquid and a non-polar liquid on a hydrophobic surface of an insulating layer, a first electrode layer stack comprising a substrate, said first electrode layer and said insulating layer having a first hydrophobic interface; a second electrode layer stack comprising a superstrate and said second electrode layer having a second boundary surface that is less hydrophobic than said first hydrophobic boundary surface; - one or more cell walls extending between said first and second electrode layer stacks; a storage space formed between the first hydrophobic boundary surface of the first electrode layer stack, the second boundary surface of the second electrode layer stack and the one or more cell walls defining sides of the storage space; Equipped with the storage space includes a polar liquid and a non-polar liquid; the polar liquid and the non-polar liquid are immiscible with each other; each of the one or more cell walls is fixedly attached to the second interface of the second electrode layer stack and extends toward the first electrode layer; An electrowetting optical component, characterized in that an end face of each of the one or more cell walls opposite the first electrode layer stack is provided with a hydrophilic surface.

2. the one or more cell walls are fixedly attached to the second boundary surface and have free ends extending toward the first electrode layer; 2. The electrowetting optical element of claim 1, wherein the height of the one or more cell walls when the first electrode layer and the second electrode layer are powered off is greater than the maximum distance between the first electrode layer and the boundary between the polar liquid and the non-polar liquid.

3. 3. The electrowetting optical element of claim 1, wherein the height of the one or more cell walls extending from the second boundary surface corresponds to the distance between the first hydrophobic boundary surface and the second boundary surface.

4. 4. The electrowetting optical element of claim 3, wherein an end face of each of said one or more cell walls forming a top surface of said cell wall loosely contacts said first hydrophobic boundary surface.

5. an end surface of each of the one or more cell walls forming a top surface of the cell wall abuts the first hydrophobic boundary surface; 4. An electrowetting optical element as described in any one of claims 1 to 3, characterized in that a sealing contact is formed between the top surface of the cell wall and the first hydrophobic boundary surface to enclose the polar liquid and the non-polar liquid within the storage space.

6. the one or more cell walls comprise a compressible mixture; 6. An electrowetting optical element according to any one of claims 1 to 5, characterized in that in particular at least the top of the cell walls contains a compressible mixture.

7. the one or more cell walls comprise an expandable mixture; 6. An electrowetting optical element according to any one of claims 1 to 5, characterized in that in particular at least the top of the cell walls contains an expandable mixture.

8. 8. An electrowetting optical component according to claim 6 or 7, characterized in that the expansion of the expandable mixture or the compression of the compressible mixture is achieved by the one or more cell walls, or in particular at least the top part of the cell walls, having a porous structure.

9. 8. An electrowetting optical element according to claim 6 or 7, characterized in that the expansion of the expandable mixture is achieved by the one or more cell walls, or by at least the top part of the cell walls, which are particularly adapted to absorb the polar liquid.

10. 10. An electrowetting optical component according to claim 8 or 9, characterized in that the porous structure comprises pores configured to absorb a liquid when the one or more cell walls, or in particular at least the tops of the cell walls, are immersed in the liquid.

11. 11. An electrowetting optical element according to claim 10, wherein the liquid bathing the one or more cell walls, or in particular at least the top of the cell walls, comprises the polar liquid.

12. 12. An electrowetting optical element according to claim 11, wherein the time during which the one or more cell walls, or in particular at least the top of the cell walls, are immersed is a predetermined time at an elevated temperature of the liquid.

13. 13. An electrowetting optical element according to any preceding claim, wherein a side of each of the one or more cell walls comprises a hydrophilic surface.

14. 14. An electrowetting optical element according to any preceding claim, wherein both the side and end faces of each of the one or more cell walls comprise a hydrophilic surface.

15. 15. The electrowetting optical element of claim 14, wherein the hydrophilic surfaces of the side and end faces are formed in a continuous layer.

16. 1. A method of manufacturing an electrowetting optical element configured to apply power to a first electrode layer and a second electrode layer to reconstitute a polar liquid and a non-polar liquid, the method comprising: - providing a second electrode layer stack comprising a superstrate and said second electrode layer having a second interface; - fixedly attaching a cell wall to a second boundary surface of said second electrode layer stack, thereby forming a storage space defined by said second boundary surface and said cell wall; - filling the containment space with a polar liquid and a non-polar liquid; - covering said containment space with a first electrode layer stack comprising a substrate, said first electrode layer and an insulating layer with a first hydrophobic interface; Including, an end face of the cell wall facing the first electrode layer stack includes a hydrophilic surface; The method of claim 1, wherein the first hydrophobic interface is more hydrophobic than the second interface.

17. a free end of the cell wall extending toward the first electrode layer; a height of the cell wall when the first electrode layer and the second electrode layer are powered off is greater than a maximum distance between the first electrode layer and a boundary between the polar liquid and the non-polar liquid; an end surface of each of the cell walls contacts the first hydrophobic boundary surface; 17. The method of claim 16, wherein a sealing contact is formed between the top surface of the cell wall and the first hydrophobic interface to encapsulate the polar liquid and the non-polar liquid within the containment space.

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