Patterned electrode structure for electrowetting device

Abstract

The present invention provides a pattern electrode structure for an electrowetting device laminated between a substrate and a dielectric layer of the electrowetting device, the pattern electrode structure comprising: a first branch electrode formed in a direction perpendicular to any plane perpendicular to a plane defined by the pattern electrode structure; and a base pattern electrode formed in a lower region of a lower end of the first branch electrode and connected to an electrode connection portion configured to receive a voltage, in which a sum of a pitch between the first branch electrode and the base pattern electrode and a width of the base pattern electrode is greater than a diameter of a droplet to be removed, therefore, the phenomenon that liquid drops stop at the tail end of the pattern and do not drop in the structure using the vertical pattern is prevented.

Description

Technical Field

[0001] The present invention relates to an electrode structure to which a pattern structure utilizing an electrowetting phenomenon is applied. Background Art

[0002] The electrowetting phenomenon refers to the phenomenon that the contact angle between a solid and an electrolyte changes due to the potential difference between the solid and the electrolyte.

[0003] This phenomenon can be used to control the surface tension of a droplet placed on an electrode coated with an insulator, thereby controlling the deformation / movement of microfluids below the microliter (μl) unit.

[0004] In addition, since a separate external driver is not required to operate the application product, the application product can be lightweight. Since the insulator applied to the electrode restricts the flow of current, the electric power consumption is low and the response speed is fast. Therefore, the electrowetting phenomenon has attracted much attention in various industrial fields.

[0005] Examples of the use of electrowetting in industry include new generation electronic devices that operate differently from previous technologies, such as Lab-on-a-chip, fluidic lenses and displays.

[0006] In addition, electrowetting devices can be used to move, deform and remove droplets formed on glass. Therefore, electrowetting devices can be installed on vehicle windshields, rearview mirrors, cameras, etc. to remove rain and dew.

[0007] The present invention relates to a self-cleaning technology using the electrowetting phenomenon.

[0008] Figure 1 A basic electrowetting self-cleaning device is shown, in which an electrode layer 10, a dielectric layer 30, and a water-repellent layer 40 are stacked on glass 20 as a substrate.

[0009] The type of the substrate 20 is not limited, but in order to mount the substrate 20 on a product that transmits visible light, such as a camera, the substrate 20 may use transparent glass.

[0010] The electrode layer 10 is a transparent electrode pattern layer and needs to be located at the lower end of the dielectric layer, and the performance of the electrode layer 10 improves as the conductivity increases.

[0011] The electrode layer 10 does not necessarily need to be transparent, but in order to install the electrode layer 10 on a product that transmits visible light, a transparent electrode is required. As representative materials, oxide-based ITO, polymer-based PEDOT:PSS, oxide-polymer composite materials (FTO), etc. can be used.

[0012] The performance can be improved due to the high dielectric constant and thin thickness of the dielectric layer 30. The durability and life are improved due to the high dielectric breakdown strength and low defects of the dielectric layer 30. As the dielectric layer 30 becomes more uniform, more homogenous, and more continuous, the deviation in performance and durability is reduced.

[0013] The dielectric layer 30 may be configured as a single layer or a multi-layer. As a representative material, an oxide / nitride-based material such as SiO 2 、TiO 2 、Al 2 O 3 、CeO 2 , HfO 2 、ZrO 2 , ZnO, SiON and Si 3 N 4 , and polymer-based materials such as polyparaxylene-C, cycloolefin polymer (COP) and polymethyl methacrylate (PMMA). As a deposition method, wet processes (spraying, spin coating, inkjet, etc.) and dry processes (electron beam, sputtering, CVD, etc.) can be used.

[0014] If the outermost layer of the dielectric layer has a sufficiently large contact angle, the water-repellent layer 40 is not an essential element and may be omitted.

[0015] A fluorine compound is used as a representative material, and a coating process is performed by a method such as electron beam spin coating.

[0016] When a voltage is applied to a transparent electrode on the glass surface of an electrowetting device, the contact angle of a droplet around the electrode changes.

[0017] The droplets around the electrodes may move in response to changes in the polarity of the voltage applied to the electrodes, or oscillate in response to changes in the magnitude of the voltage.

[0018] According to the Lippmann-Young equation, the contact angle changes greatly when the following three conditions are met.

[0019] - Dielectric coating material with high dielectric constant and thin thickness

[0020] -Hydrophobic coating materials have low interfacial tension (= large contact angle)

[0021] - Applied voltage is high

[0022] The behavior of a droplet on the surface of an electrowetting device varies depending on the frequency and / or magnitude of the applied voltage.

[0023] That is, when DC voltages with different polarities are applied to two adjacent electrodes, Figure 2 As shown, the droplet is dragged due to the attraction between electrodes with opposite polarity to the droplet, causing the droplet to move.

[0024] In addition, if a half-wave rectified current with a phase difference of 180 degrees is continuously applied to two adjacent electrodes, the droplet repeatedly shrinks and expands in opposite polarity directions. Figure 3 As shown, oscillation occurs and the adhesion to the bottom surface decreases.

[0025] That is, when an external force is applied to a droplet, the droplet can easily move in the direction of the external force (adhesion force reduction + gravity = dripping).

[0026] Figure 4 An example of an electrode pattern structure is shown. The electrode pattern structure includes a first electrode portion and a second electrode portion. The first electrode portion includes a first electrode connection portion 111, a first base pattern electrode 112, and a first branch electrode 113. The second electrode portion includes a second electrode connection portion 121, a second base pattern electrode 122, and a second branch electrode 123.

[0027] Generally, a liquid droplet on an electrowetting surface is moved in the length direction of the branch electrodes by applying an alternating current (AC) to induce oscillation, under the influence of gravity.

[0028] Therefore, a vertical pattern is usually used to minimize the dripping distance and time. However, if a comb-like vertical pattern structure is used when an AC voltage is applied, the droplets will stagnate at the end of the pattern and will not drip further.

[0029] The information disclosed in the above background art is only for helping understanding the background of the present invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0030] Therefore, in view of the above, an object of the present invention is to provide a pattern electrode structure for an electrowetting device that can prevent a droplet from stagnating at a pattern end without dripping in a structure using a vertical pattern, thereby making the self-cleaning performance more effective.

[0031] As a preferred embodiment, a pattern electrode structure for an electrowetting device is stacked between a substrate and a dielectric layer of the electrowetting device, and includes: a first branch electrode formed in a direction perpendicular to any plane perpendicular to the plane defined by the pattern electrode structure; and a base pattern electrode formed in a region below a lower end of the first branch electrode and connected to an electrode connection portion configured to receive a voltage, wherein the sum of a spacing between the first branch electrode and the base pattern electrode and a width of the base pattern electrode is greater than a diameter of a droplet to be removed.

[0032] Particularly, a sum of an interval between the first branch electrode and the base pattern electrode and a width of the base pattern electrode may be greater than 1.93 mm.

[0033] In addition, the first branch electrodes and the base pattern electrodes may have different polarities.

[0034] In addition, the pattern electrode structure may further include second branch electrodes which are alternately formed with the first branch electrodes in a width direction of the pattern electrode structure and have polarities different from those of the first branch electrodes.

[0035] Meanwhile, the width of the lower end of the first branch electrode becomes smaller toward the end portion.

[0036] Specifically, the lower end of the first branch electrode may include a bent portion.

[0037] Alternatively, the lower end of the first branch electrode may include a cutting-edge portion.

[0038] In addition, the patterned electrode structure may further include a hydrophobic coating layer stacked on the electrode structure, wherein the hydrophobic coating layer is partially stacked on the electrode structure.

[0039] Specifically, the height of the lower end of the hydrophobic coating layer may be equal to or lower than the height of the lowermost end of the first branch electrode and higher than a point spaced downward from the lowermost end of the first branch electrode by a distance corresponding to the radius of the droplet to be removed.

[0040] As another preferred embodiment, a pattern electrode structure for an electrowetting device is stacked between a substrate and a dielectric layer of the electrowetting device, and includes: a first branch electrode formed in a direction perpendicular to any plane perpendicular to the plane defined by the pattern electrode structure; and a base pattern electrode formed in a region below the lower end of the first branch electrode and connected to an electrode connection portion configured to receive a voltage, wherein the width of the lower end of the first branch electrode becomes smaller toward the end.

[0041] In addition, the first branch electrodes and the base pattern electrodes may have different polarities.

[0042] In addition, the pattern electrode structure may further include second branch electrodes which are alternately formed with the first branch electrodes in a width direction of the pattern electrode structure and have polarities different from those of the first branch electrodes.

[0043] In addition, the lower end of the first branch electrode may include a bent portion.

[0044] Alternatively, the lower end of the first branch electrode may include a tip portion.

[0045] Meanwhile, the patterned electrode structure may further include a hydrophobic coating layer stacked on the electrode structure, wherein the hydrophobic coating layer is partially stacked on the electrode structure.

[0046] Specifically, the height of the lower end of the hydrophobic coating layer may be equal to or lower than the height of the lowermost end of the first branch electrode and higher than a point spaced downward from the lowermost end of the first branch electrode by a distance corresponding to the radius of the droplet to be removed.

[0047] In electrowetting glass, when a droplet stays in a specific narrow space and oscillates or moves repeatedly in place, the periodic change in voltage causes charges and ions to move in the droplet, and the charges and ions are concentrated in a specific location, causing burning due to exceeding the yield voltage of the dielectric layer on the glass surface.

[0048] However, according to the present invention, the droplets can be directed to a region to which a low or non-periodic voltage is applied, thereby preventing the dielectric layer from being burned.

[0049] Therefore, according to the present invention, the working life of the electrowetting glass can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 , Figure 2 and Figure 3 is a diagram for explaining a general electrowetting device.

[0051] Figure 4 is a view showing a pattern structure of an electrowetting device.

[0052] Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 and Fig.13 It is a view for explaining the limitation of the technology according to the related art pattern structure.

[0053] Fig.14 This is a view showing a part of the pattern structure of the electrowetting device of the present invention.

[0054] Fig.15 and Fig.16 is a diagram showing the behavior of a droplet with respect to the droplet size according to the present invention.

[0055] Fig.17 , Fig.18 and Fig.19 is a view used to explain the behavior of droplets according to the pattern shape.

[0056] Fig. 20 , Fig.21 , Fig. 22 and Fig.23 It is a view showing a part of an application example of the pattern structure of the electrowetting device of the present invention.

[0057] Fig.24 and Fig.25 is used to explain more specifically Fig. 20 View of the example in .

[0058] Fig.26 , Fig. 27 , Fig.28 and Fig.29 It is shown separately Figure 20 to Figure 23 A view of other behaviors of droplets in the application examples.

[0059] Fig.30 , Fig.31 , Fig.32 and Fig.33 It is shown separately Figure 20 to Figure 23 A view of other behaviors of droplets in the application examples.

[0060] Fig.34 It is shown Fig. 20 View of additional application examples of pattern shapes in . DETAILED DESCRIPTION

[0061] Hereinafter, embodiments of the present invention will be described in detail with reference to exemplary drawings, and the present invention is not limited to the embodiments described herein because these embodiments as examples can be implemented in various forms by those skilled in the art to which the present invention pertains.

[0062] In order to fully understand the present invention, its operating advantages and objectives to be achieved by implementing the present invention, reference should be made to the accompanying drawings to illustrate exemplary embodiments of the present invention and the contents disclosed therein.

[0063] Furthermore, in the description of the present invention, when it is determined that the description of the well-known prior art will unnecessarily obscure the subject matter of the present invention, the repeated description thereof will be reduced or omitted.

[0064] Figure 4 is a view illustrating a pattern structure of an electrowetting device, Figures 5 to 13 It is a view for explaining the limitation of the technology according to the related art pattern structure.

[0065] The present invention is to prevent the phenomenon that, in a structure using a vertical pattern, liquid droplets accumulate at the end of the vertical pattern and cannot drip.

[0066] Figures 5 to 7 The case where the size of the droplet D spans two or less electrodes is shown. Figure 5 and Figure 6 The droplet D is shown spanning the first branch electrode 113 and the second branch electrode 123 , and a balanced relationship between the forces is shown. Figure 7 The behavior of an actual droplet D when an AC voltage is applied in this case is shown.

[0067] Figures 8 to 10 The case where the size of the droplet D spans three or more electrodes is shown. Figure 8 and Fig. 9 The droplet D is shown to span the first branch electrode 113 and two second branch electrodes 123 disposed on opposite sides, and a balanced relationship between the forces is shown. Fig.10 The behavior of an actual droplet D when an AC voltage is applied in this case is shown.

[0068] As described above, in the case where a droplet stays at a specific position for a long period of time without moving, insulation breakdown of the insulation layer may occur by applying a high potential difference between the droplet and a driving electrode disposed under the insulation layer for a long period of time.

[0069] The insulation breakdown occurs after the smoke appears and leads to the separation of the insulation layer and the overall separation.

[0070] An insulating layer with a high dielectric breakdown strength may be applied. However, since the dielectric breakdown strength and the dielectric constant are inversely proportional to each other, the cleaning performance will be significantly deteriorated as the dielectric constant decreases.

[0071] Therefore, it is advantageous to prevent a droplet from getting stuck in a particular location for a long period of time.

[0072] Fig.11 and Fig.12 Shows the situation where the droplet is stuck and not moving.

[0073] Fig.11 It is shown that the droplet D reaches the end (ie, the lower end) of the first branch electrode 113 , the droplet D is stuck at the end position of the first branch electrode 113 , and the droplet D repeatedly moves at a fixed position.

[0074] Fig.12 The droplet straddling the end of the first branch electrode 113 is shown, and repeatedly moves at a fixed position due to polarity switching (AC) before the droplet leaves the first branch electrode 113. When W (lower electrode width) < Φ (droplet diameter), the occurrence rate increases.

[0075] Fig.13The case where the size of the droplet spans more than three electrodes is shown. The droplet on the left moves downward along the first branch electrode 113 and is stuck at the end position (oscillating in place) due to the termination of the first branch electrode 113. The droplet on the right moves downward along the second branch electrode 123 and moves repeatedly due to polarity switching (alternating current) before the droplet leaves the first branch electrode 113. In the case where W (lower end electrode width) < Φ (droplet diameter), the incidence increases.

[0076] This droplet stuck situation occurs when the droplet crosses two electrodes adjacent to each other in the up-and-down direction.

[0077] When a voltage is applied to the upper electrode in a state where the droplet cannot completely leave the upper electrode (branch electrode), an electric attraction force is generated in the upward direction, so that the droplet appears to repeat, oscillate, or get stuck in the up and down directions.

[0078] The droplet is stuck because it cannot completely leave the upper electrode when it is dragged toward the lower electrode. There are three reasons for this.

[0079] 1) Due to the size of the patterned electrode, the droplet cannot leave the upper electrode even when it is dragged toward the lowermost end.

[0080] 2) Since the electric attraction of the lower electrode is weak (electric attraction magnitude issue), the droplet cannot be sufficiently dragged downward.

[0081] 3) Before the droplet leaves the upper electrode through the electrical attraction of the lower electrode (applied frequency issue), the attraction of the upper electrode is generated.

[0082] The present invention aims to solve the problem of pattern electrode size to prevent droplets from getting stuck at the ends of branch electrodes.

[0083] Fig.14 This is a view showing a part of the pattern structure of the electrowetting device of the present invention.

[0084] In the following, reference will be made to Fig.14 A pattern electrode structure for an electrowetting device according to an embodiment of the present invention is described.

[0085] In the electrowetting self-cleaning device of the present invention, the electrode layer 10, the dielectric layer 30 and the water-repellent layer 40 are stacked on the glass 20. The water-repellent layer 40 may be a hydrophobic coating.

[0086] like Figure 4As shown, the pattern structure of the electrowetting device of the present invention includes a first electrode portion and a second electrode portion. The first electrode portion includes a first electrode connecting portion 111, a first base pattern electrode 112 and a first branch electrode 113. The second electrode portion includes a second electrode connecting portion 121, a second base pattern electrode 122 and a second branch electrode 123.

[0087] The pattern structure shown may be a quadrilateral as a whole, but may also be a circle or an ellipse as a whole. That is, the overall shape is irrelevant to the subject matter of the present invention.

[0088] In addition, the pattern electrode structure of the present invention performs self-cleaning by receiving an AC voltage to cause droplets to oscillate and drop on the electrode. The plane defined by the overall structure needs to be a plane perpendicular to the horizontal plane, or needs to be a plane inclined at a predetermined angle.

[0089] The first electrode connection part 111 and the second electrode connection part 121 are connected to a power source to receive a voltage. The first base pattern electrode 112 and the second base pattern electrode 122 are connected to the first electrode connection part 111 and the second electrode connection part 121, respectively, and define the periphery of the entire pattern electrode structure. That is, a predetermined area of ​​the periphery is formed by the first base pattern electrode 112, and the remaining area of ​​the periphery is formed by the second base pattern electrode 122.

[0090] The first branch electrodes 113 and the second branch electrodes 123 are respectively branched from the first base pattern electrode 112 and the second base pattern electrode 122 and arranged in one direction on the electrode structure, which is a direction perpendicular to any plane perpendicular to the electrode structure.

[0091] In addition, the first branch electrodes 113 and the second branch electrodes 123 are alternately arranged in the width direction.

[0092] Fig.14 A portion of the pattern electrode structure of the present invention is shown, and a portion including lower ends or tips of branch electrodes and a base pattern electrode disposed below the branch electrodes is shown.

[0093] Here, the width of the first branch electrode 113 is W 1 The width of the second branch electrode 123 is represented by W 2 The width of the second base pattern electrode 122 is represented by W 2b express.

[0094] As shown, the width direction of the branch electrodes and the width direction of the base pattern electrode are different from each other.

[0095] In addition, the distance between the first branch electrode 113 and the second branch electrode 123 is G 0The distance between the first branch electrode 113 and the second base pattern electrode 122 is represented by G 1b The diameter of the droplet D is represented by Φ d express.

[0096] In this case, the present invention is characterized in that the width W of the second base pattern electrode 122 is 2b and the distance G between the first branch electrode 113 and the second base pattern electrode 122 1b The sum (W 2b +G 1b ) is larger than the diameter of the droplet to be removed Φ d .

[0097] W 2b +G 1b >Φ d

[0098] refer to Fig.15 (where the size of the droplet D spans across the two following electrodes) and Fig.16 (wherein the size of the droplet D spans more than three electrodes), in the process of designing the pattern electrode under such conditions, when the droplet spans the end of the first branch electrode 113 and the second base pattern electrode 122, the droplet will fall on the second base pattern electrode 122 and will not get stuck on the first branch electrode 113.

[0099] Table 1 below shows the droplet radius relative to the droplet volume.

[0100] Table 1

[0101]

[0102] More specifically, referring to Table 1, on a surface having a contact angle of 115 degrees, the minimum volume of a droplet that does not slide naturally is 3 μl. In the present invention, the range of the droplet to be removed is 0.2 μl to 3 μl.

[0103] refer to Fig.17 , the diameter of the droplet Φ d The range is as follows.

[0104] 0.658~0.782mm≤Φ d ≤1.748~1.93mm

[0105] Due to the need to meet W 2b +G 1b >Φ d , so W 2b +G 1b Need to be greater than Φ d The maximum value of W 2b +G 1b>1.93mm.

[0106] As described above, the conditions for the width of the second base pattern electrode 122 and the interval between the second base pattern electrode 122 and the first branch electrode 113 for preventing the liquid drop from stagnating at the lower portion have been derived.

[0107] Next, whether or not a droplet stagnates at the lower portion depending on the shape of the branch electrode will be described.

[0108] Figures 17 to 19 is a view used to explain the behavior of droplets according to the pattern shape.

[0109] In the above embodiment, the end of the branch pattern is a straight line shape. Due to the angled shape of the edge of the end, when the droplet reaches the edge of the end, as shown, the droplet is reset to the end of the first branch electrode 113 or repeatedly moves when moving to a position where the symmetry ratio between the first branch electrode 113 and the second branch electrode 123 is uniform.

[0110] Even if the sagging occurs intermittently, in the case where the droplet cannot leave the first branch electrode 113 , the same behavior as described above occurs.

[0111] Fig.17 and Fig.18 The behaviors in are the most frequent, but it is difficult to specify the location of the droplets due to the diversity in the behaviors.

[0112] Therefore, the present invention also provides an application example in which the shape of the distal end of the first branch electrode 113 is changed.

[0113] Figure 20 to Figure 23 1 is a view showing a part of an application example of a pattern structure of an electrowetting device of the present invention. Fig.24 and Fig.25 is used to explain more specifically Fig. 20 View of the example in .

[0114] The end of each first branch electrode has a shape in which the width decreases toward the end.

[0115] Fig. 20 The tip of the first branch electrode 213 - 1 in FIG. 1 has a shape that is convexly rounded toward the second base pattern electrode. Fig.21 The ends of the first branch electrodes 213-2 in FIG. 1 have a shape in which two curved lines extending from two opposite sides are connected to each other. That is, the shape has a curved portion.

[0116] Fig. 22 and Fig.23 A tip of each of the first branch electrodes has an inclined pointed shape. Fig. 22The ends of the first branch electrodes 213-3 have a symmetrical shape, and Fig.23 The end of the first branch electrode 213-4 has an asymmetrical shape. That is, the shape has a pointed portion.

[0117] like Fig.24 and Fig.25 As shown, the shape of the tip of each first branch electrode can guide the droplet to a specific position, that is, the tip or the end center of the first branch electrode.

[0118] Furthermore, when the droplet reaches the center of the end of the first branch electrode, the droplet area shapes on the first branch electrode and the lower second base pattern electrode are asymmetrical, so that a stronger electrical attraction is applied to the droplet toward the second branch electrode 223-1, 223-2, 223-4 or 223-4.

[0119] Figure 26 to Figure 29 It is shown in Figure 20 to Figure 23 Application example: View of a large droplet when the droplet size spans more than three electrodes.

[0120] When a droplet slides along the second branch electrode 223-1, 223-2, 223-3 or 223-4, the droplet receives a stronger downward electrical attraction because the area of ​​the second branch electrode 223-1, 223-2, 223-3 or 223-4 where the droplet is located in the up and down directions is larger when the droplet reaches the end.

[0121] Figures 30 to 33 It is shown in Figure 20 to Figure 23 In the example of the application of FIG. 1 , another behavior of a large droplet is shown when the size of the droplet spans more than three electrodes. That is, this situation corresponds to the situation where the droplet slides along the first branch electrode.

[0122] At the position where the droplet reaches the end, the direction of the force changes according to the area distribution of the first branch electrodes 213-1, 213-2, 213-3 and 213-4 and the second branch electrodes 223-1, 223-2, 223-3 and 223-4 where the droplet is located.

[0123] That is, based on the horizontal center line of the droplet, the area of ​​each second branch electrode 223-1, 223-2, 223-3 and 223-4 below the horizontal center line is designed to be larger than the area above the horizontal center line, so that the droplet can receive a stronger downward electrical attraction.

[0124] Next, Fig.34 It is shown Fig. 20 A view of additional application examples of pattern shapes in FIG.

[0125] In the prior art, a hydrophobic coating is applied to the front surface of the electrowetting glass, so that the electrowetting glass has a contact angle of more than 110 degrees at all positions. In contrast, in the present invention, the hydrophobic coating is excluded at a specific position, so that the droplet moves to the specific position through the attraction generated by the energy difference of the solid surface.

[0126] The exclusion of the hydrophobic coating can be performed by performing masking during the coating process. In the case of wet coating using an inkjet method, the hydrophobic coating can be applied to a selected location by using a process device.

[0127] In the prior art, it is difficult to specify the position of the droplet on the end structure of the electrode pattern, and even if the hydrophobic coating is selectively applied, the effect is limited. Figure 20 to Figure 23 In the case of the pattern structure shown with curved lines and gradient straight lines at the ends, droplets can be directed to specific locations, thereby maximizing the effect of the selective hydrophobic coating.

[0128] That is, since the droplets moving through the selective hydrophobic coating completely leave the base electrode, the droplets do not oscillate, and no charge or ion behavior and concentration inside the fluid occurs. Therefore, no surface burning occurs.

[0129] When the lowermost end of the first branch electrode 213 - 1 coincides with the center of the droplet, the droplet D reaches the lowermost position.

[0130] Therefore, the lower end of the hydrophobic coating 40-1 should be equal to or lower than the lowermost end of the first branch electrode 213-1. When the droplet reaches the lowermost end, the lower end of the hydrophobic coating 40-1 should not be equal to or lower than the lowermost end of the droplet.

[0131] Therefore, the height of the lower end of the hydrophobic coating layer should be equal to or lower than the height of the lowest end of the first branch electrode 213-1, and should be higher than the distance Φ from the lowest end of the first branch electrode 213-1 downward. d / 2 distance point.

[0132] The above-mentioned size and shape of the pattern and the hydrophobic layer according to the present invention can prevent the phenomenon that the droplets stagnate at the end of the pattern without dripping, thereby more effectively improving the self-cleaning performance.

[0133] Although the present invention has been described with reference to the exemplary drawings, it is obvious to those skilled in the art that the present invention is not limited to the aforementioned embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the examples of changes or modifications fall within the scope of the claims of the present invention, and the scope of the present invention should be interpreted based on the appended claims.

Claims

1. A pattern electrode structure for an electrowetting device, which is stacked between a substrate and a dielectric layer of the electrowetting device, the pattern electrode structure comprising: A plurality of first branch electrodes are formed along a direction perpendicular to any plane perpendicular to the plane defined by the pattern electrode structure; and a plurality of base pattern electrodes formed in a region below a lower end of each of the plurality of first branch electrodes and connected to an electrode connection portion configured to receive a voltage; The sum of the interval between each of the plurality of first branch electrodes and each of the plurality of base pattern electrodes and the width of each of the plurality of base pattern electrodes is greater than the diameter of the droplet to be removed.

2. The pattern electrode structure according to claim 1, wherein: A sum of a spacing between each of the plurality of first branch electrodes and each of the plurality of base pattern electrodes and a width of each of the plurality of base pattern electrodes is greater than 1.93 mm.

3. The pattern electrode structure according to claim 1, wherein: The plurality of first branch electrodes and the plurality of base pattern electrodes have different polarities.

4. The pattern electrode structure according to claim 3, further comprising: A plurality of second branch electrodes are formed alternately with the plurality of first branch electrodes in the width direction of the pattern electrode structure, and polarities of the plurality of second branch electrodes are different from polarities of the plurality of first branch electrodes.

5. The pattern electrode structure according to claim 1, wherein: The width of the lower end of each first branch electrode becomes smaller toward the end portion.

6. The pattern electrode structure according to claim 5, wherein: A lower end of each of the first branch electrodes includes a bent portion.

7. The pattern electrode structure according to claim 5, wherein: The lower end of each first branch electrode includes a tip portion.

8. The pattern electrode structure according to claim 5, further comprising: a hydrophobic coating layer stacked on the electrode structure, Wherein, the hydrophobic coating is partially laminated on the electrode structure.

9. The pattern electrode structure according to claim 8, wherein: The height of the lower end of the hydrophobic coating is equal to or lower than the height of the lowermost end of each first branch electrode and is higher than a point spaced downward from the lowermost end of each first branch electrode by a distance corresponding to the radius of a droplet to be removed.

10. A pattern electrode structure for an electrowetting device, which is stacked between a substrate and a dielectric layer of the electrowetting device, the pattern electrode structure comprising: A plurality of first branch electrodes are formed along a direction perpendicular to any plane perpendicular to the plane defined by the pattern electrode structure; a plurality of base pattern electrodes formed in a region below a lower end of each of the plurality of first branch electrodes and connected to an electrode connection portion configured to receive a voltage; and a hydrophobic coating layer stacked on the electrode structure, Wherein, the hydrophobic coating is partially laminated on the electrode structure.

11. The pattern electrode structure according to claim 10, wherein: The width of the lower end of each first branch electrode becomes smaller toward the end portion.

12. The pattern electrode structure according to claim 11, wherein: The plurality of first branch electrodes and the plurality of base pattern electrodes have different polarities.

13. The pattern electrode structure according to claim 12, further comprising: A plurality of second branch electrodes are formed alternately with the plurality of first branch electrodes in the width direction of the pattern electrode structure and have polarities different from those of the plurality of first branch electrodes.

14. The pattern electrode structure according to claim 11, wherein: A lower end of each of the first branch electrodes includes a bent portion.

15. The pattern electrode structure according to claim 11, wherein: The lower end of each first branch electrode includes a tip portion.

16. The pattern electrode structure according to claim 10, wherein: The height of the lower end of the hydrophobic coating is equal to or lower than the height of the lowermost end of each first branch electrode and is higher than a point spaced downward from the lowermost end of each first branch electrode by a distance corresponding to the radius of a droplet to be removed.

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