Substrate of electrowetting device, fabrication method and electrowetting device

Abstract

This invention discloses a lower substrate, a fabrication method, and an electrowetting device, relating to the field of electrowetting display technology. The lower substrate of the electrowetting device includes a substrate with multiple pixel grids. A current-guiding structure is disposed within each pixel grid, having a first side and a second side. The thickness of the current-guiding structure gradually decreases from the first side to the second side. The current-guiding structure has a sloped structure, and the thickness of the ink fluid within the pixel grid gradually increases along the sloped structure. Thus, when a gradually increasing voltage is applied to the ink fluid within the pixel grid, the ink fluid will preferentially open from the thinner areas and then gradually contract to the thicker areas, forming a process where the ink fluid opening ratio gradually increases to saturation. This improves the controllable range of the opening ratio, enhances the consistency of ink fluid movement within the pixel grid, suppresses abrupt changes in ink fluid movement, and better achieves grayscale control in the electrowetting display device.

Description

Technical Field

[0001] This invention relates to the field of electrowetting display technology, and particularly to a substrate, preparation method, and electrowetting device for an electrowetting device. Background Technology

[0002] Electrowetting display is a display technology based on the electrowetting phenomenon, which refers to the change in the wettability of a liquid on a solid surface under the influence of an electric field.

[0003] Display devices based on electrowetting technology have a lower substrate. In related technologies, multiple stepped guide blocks are fabricated on the lower substrate using photoresist or conductive adhesive through photolithography. The ink fluid thickness is the same at the stepped guide blocks, but the ink fluid thickness is thicker within the pixel grid except at the stepped guide blocks. During the use of the electrowetting device, when an input voltage is applied, the ink fluid will open from the stepped guide block position. When the voltage increases, some thicker ink fluid may not open. If the voltage is further increased, the ink fluid that did not open will undergo a jump, that is, the ink fluid will open rapidly, and the opening ratio will increase by at least 30% at once. This rapid increase in the ink fluid opening greatly affects the grayscale control capability of the electrowetting device, thus significantly reducing the display effect of the electrowetting device. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a lower substrate for an electrowetting device, which can effectively improve the display effect of the electrowetting device.

[0005] The present invention also proposes a method for preparing a lower substrate for use in the above-mentioned electrowetting device and an electrowetting device.

[0006] The lower substrate of the electrowetting device according to a first aspect embodiment of the present invention includes:

[0007] A substrate having multiple pixel grids, each pixel grid having a flow guiding structure, the flow guiding structure having a first side and a second side, the thickness of the flow guiding structure gradually decreasing from the first side to the second side.

[0008] The lower substrate of the electrowetting device according to an embodiment of the present invention has at least the following beneficial effects: a current-guiding structure is provided within the pixel grid of the substrate. The current-guiding structure has a sloping structure, and the thickness of the ink fluid within the pixel grid gradually increases along the sloping structure. Thus, when a gradually increasing voltage is applied to the ink fluid within the pixel grid, the ink fluid within the pixel grid will preferentially open from the area where the ink fluid is thinner, and then gradually contract to the area where the ink fluid is thicker, forming a process in which the opening ratio of the ink fluid gradually increases to saturation. Here, the controllable range of the opening ratio can be increased to 5% to 75%. By adopting a current-guiding structure with a sloping structure, the uniformity of the movement of the ink fluid within the pixel grid is improved, the movement jump of the ink fluid is suppressed, and grayscale control of the electrowetting display device is better realized.

[0009] According to some embodiments of the present invention, the first and second sides of the flow guiding structure are arranged along a diagonal direction of the pixel grid.

[0010] According to some embodiments of the present invention, the height of the first side portion is less than the height of the pixel grid.

[0011] According to some embodiments of the present invention, the height ratio of the first side of the flow guiding structure to the pixel grid is 0.6 to 0.8.

[0012] According to some embodiments of the present invention, the second side of the flow guiding structure has a cutout.

[0013] According to some embodiments of the present invention, there is a gap between the periphery of the flow guiding structure and the grid wall of the pixel grid.

[0014] According to some embodiments of the present invention, the width of the gap is 3µm to 8µm.

[0015] According to a second aspect of the present invention, a method for fabricating a lower substrate for an electrowetting device is provided, the method comprising the steps of:

[0016] A flow guiding structure as described in the first aspect embodiment is provided within the pixel grid of the substrate of the lower substrate.

[0017] The preparation method according to the embodiments of the present invention has at least the following beneficial effects: by introducing nanoimprinting technology, 3D changes in the flow guiding structure can be realized to form a flow guiding structure with a slope structure in the pixel grid. In this way, when the voltage of the electrowetting device increases or decreases, its grayscale control (the opening ratio of the ink fluid in the pixel grid increases or decreases) can be well displayed.

[0018] According to some embodiments of the present invention, the step of providing the current guiding structure within the pixel grid of the substrate of the lower substrate includes the following steps:

[0019] A current-guiding structure is provided, and multiple current-guiding structures are fabricated on the dielectric layer of the substrate using a nanoimprinting process;

[0020] A hydrophobic insulating layer is formed by coating the dielectric layer with a hydrophobic insulating material.

[0021] A pixel grid is set up, and pixel walls are formed on the hydrophobic insulating layer by a coating, exposure and development process. The pixel walls are formed in the interval area between adjacent flow guiding structures and each flow guiding structure is individually surrounded. The pixel walls surrounding the flow guiding structures form the pixel grid.

[0022] An electrowetting device according to a third aspect embodiment of the present invention includes:

[0023] The lower substrate of the electrowetting device as described in the first aspect embodiment above.

[0024] Since the electrowetting device has all the technical solutions of the lower substrate of the electrowetting device of the first aspect embodiment described above, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0027] Figure 1 This is a schematic diagram of the structure of an electrowetting device according to an embodiment of the present invention;

[0028] Figure 2 for Figure 1 A schematic diagram of the lower substrate of the electrowetting device is shown.

[0029] Figure 3 This is a schematic diagram of the flow guiding structure according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram illustrating the structural relationship between the pixel grid and the flow guide block according to an embodiment of the present invention;

[0031] Figure 5 A graph showing the ink fluid aperture ratio of electrowetting devices in related technologies;

[0032] Figure 6 This is a graph showing the ink fluid aperture ratio of an electrowetting device according to an embodiment of the present invention.

[0033] Figure 7 This is a flowchart of a preparation method according to an embodiment of the present invention.

[0034] Figure label:

[0035] 1. Lower substrate, 2. Upper substrate, 3. Separator frame, 4. Polar liquid, 5. Ink fluid, 6. Substrate, 7. First electrode film, 8. Dielectric layer, 9. Grid wall, 10. Conducting structure, 11. Second electrode film, 12. Spacer post, 13. First side, 14. Second side, 15. Cutout, 16. Gap, 17. Hydrophobic insulating layer. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0038] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. Where "first" and "second" are mentioned, they are only for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0039] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0040] Electrowetting display is a display technology based on the electrowetting phenomenon, which refers to the change in the wettability of a liquid on a solid surface under the influence of an electric field.

[0041] Display devices based on electrowetting technology have a lower substrate. In related technologies, multiple stepped guide blocks are fabricated on the lower substrate using photoresist or conductive adhesive through photolithography. The ink fluid thickness is the same at the stepped guide blocks, but the ink fluid thickness is thicker within the pixel grid except at the stepped guide blocks. During the use of the electrowetting device, when an input voltage is applied, the ink fluid will open from the stepped guide block position. When the voltage increases, some thicker ink fluid may not open. If the voltage is further increased, the ink fluid that did not open will undergo a jump, that is, the ink fluid will open rapidly, and the opening ratio will increase by at least 30% at once. This rapid increase in the ink fluid opening greatly affects the grayscale control capability of the electrowetting device, thus significantly reducing the display effect of the electrowetting device.

[0042] Therefore, some embodiments of the present invention provide a lower substrate for an electrowetting device and a method for its fabrication, as detailed in the following figures. Figures 1 to 7 The lower substrate of the electrowetting device is shown in the diagram.

[0043] Reference Figure 1 and Figure 2 As shown, the electrowetting device provided in the third aspect embodiment of the present invention includes a lower substrate 1, an upper substrate 2, a partition frame 3, a polar liquid 4, and an ink fluid 5. The lower substrate 1 is parallel to the upper substrate 2 and is located below the upper substrate 2. The partition frame 3 is disposed between the lower substrate 1 and the upper substrate 2, and its two ends are respectively connected to the lower substrate 1 and the upper substrate 2. The partition frame 3, together with the lower substrate 1 and the upper substrate 2, defines a receiving cavity for receiving the polar liquid 4 and the ink fluid 5.

[0044] Reference Figure 1 and Figure 2 As shown, the lower substrate 1 of the electrowetting device provided in the first aspect embodiment of the present invention includes a substrate 6, which is a glass carrier. A first electrode film 7 and a dielectric layer 8 are sequentially disposed on the upper surface of the substrate 6 from bottom to top. Multiple pixel grids are disposed on the substrate 6, with grid walls 9 connecting to the upper surface of the dielectric layer 8. Multiple flow-guiding structures 10 are formed on the dielectric layer 8 using nanoimprint lithography, with one flow-guiding structure 10 corresponding to each pixel grid. The function of the flow-guiding structures 10 is to create a height difference in the ink fluid 5 within the pixel grid and to guide the opening direction of the ink fluid 5. A hydrophobic insulating layer 17 is disposed above the dielectric layer 8. The function of the hydrophobic insulating layer 17 is to protect the dielectric layer 8 and prevent it from being corroded by the polar liquid 4.

[0045] It should be noted that the upper substrate 2 includes a second electrode film 11, which is located on the side close to the lower substrate 1. The electrowetting device also includes a spacer post 12, which is disposed between the lower substrate 1 and the upper substrate 2. One end of the spacer post 12 is connected to the second electrode film 11, and the other end is connected to the grid wall 9 of the pixel grid, so as to play a supporting and separating role.

[0046] It is understandable that each pixel cell contains an ink fluid 5. When the first electrode film 7 and the second electrode film 11 output gradually increasing voltage, the ink fluid 5 located in the pixel cell will form an opening in the thinner area. Starting from the opening, it will open towards the thicker area of ​​the ink fluid 5 in the pixel cell. As the voltage gradually increases, the opening ratio of the ink fluid 5 gradually increases to saturation.

[0047] Reference Figure 3 As shown, the flow guiding structure 10 has a first side portion 13 and a second side portion 14. The thickness of the flow guiding structure 10 gradually decreases from the first side portion 13 to the second side portion 14, so that the thickness of the ink fluid 5 located within the pixel grid gradually increases from the first side portion 13 to the second side portion 14. Specifically, the first side portion 13 and the second side portion 14 are arranged diagonally within the pixel grid, and the opening of the ink fluid 5 within the pixel grid opens along the diagonal direction of the pixel grid.

[0048] It should be noted that the arrangement of the first side 13 and the second side 14 is not limited to the above-described arrangement. In some embodiments, the first side 13 and the second side 14 can be arranged adjacently or oppositely. Such arrangements can ensure that the thickness of the ink fluid 5 within the pixel grid gradually increases from the first side 13 to the second side 14, thereby achieving a linear increase in the opening ratio of the ink fluid 5 with increasing voltage and avoiding abrupt changes in the ink opening ratio. The arrangement should be determined according to actual production needs.

[0049] It should be noted that the height of the first side portion 13 is less than the height of the pixel grid. When the output voltage is applied, the ink fluid 5 gathers within the pixel grid from the opening towards the edge of the pixel grid to form pixels for displaying patterns. If the height of the first side portion 13 is greater than the height of the pixel grid, there will be no ink fluid 5 above the first side portion 13, and the ink fluid 5 will be too far from the grid walls 9, affecting pixel formation and degrading the display effect of the electrowetting device.

[0050] Understandably, the height ratio of the first side portion 13 to the pixel grid is between 0.6 and 0.8. When the height ratio is within this range, the opening ratio of the ink fluid 5 performs better. When the height ratio is less than 0.6, the thickness of the first side portion 13 is too small, and the ink fluid 5 above the first side portion 13 is relatively thick, which easily leads to abrupt changes in ink fluid movement. When the height ratio is greater than 0.8, the thickness of the first side portion 13 is too large, and the ink fluid 5 above the first side portion 13 is relatively thin, which also easily leads to abrupt changes in ink fluid movement. Therefore, the preferred solution is that the height ratio of the first side portion 13 to the pixel grid is between 0.6 and 0.8.

[0051] It should be noted that the second side 14 has a notch 15. The thickness of the ink fluid 5 at the notch 15 is the depth of the pixel grid. The ink fluid 5 is thicker here. When the ink fluid 5 opens from the opening to the notch 15, the ink fluid 5 gathers at the notch 15, resulting in a better pixel display effect.

[0052] Reference Figure 1 and Figure 4 As shown, there is a gap 16 between the periphery of the flow guiding structure 10 and the grid wall 9 of the pixel grid. This design ensures that the ink fluid 5 is not constrained by the capillary force of the pixel wall when it separates, allowing the ink fluid 5 to open from the upper left corner with 100% certainty. The principle is that the ink fluid 5 at the gap 16 is thicker, and as the voltage increases, the ink fluid 5 at the gap 16 is less likely to open. Instead, the ink fluid 5 will preferentially open from the first side 13, effectively improving the controllability of the ink fluid 5 opening.

[0053] It should be noted that the width of the gap 16 ranges from 3µm to 8µm. When the gap 16 is less than 3µm, the flow guiding structure 10 is closer to the pixel grid wall 9 and is easily constrained by the capillary force of the pixel wall; when the gap 16 is greater than 8µm, the flow guiding structure 10 is farther from the pixel grid wall 9, affecting the display effect.

[0054] Reference Figure 5 and Figure 6 As shown, in Figure 5 In the related technology, the flow guiding structure 10 lacks a slope structure, causing the opening ratio of the ink fluid 5 to jump with increasing voltage, affecting the grayscale control effect of the electrowetting device; Figure 6 In this invention, the flow guiding structure 10 has a slope structure, and the opening ratio of the ink fluid 5 increases linearly with the increase of voltage, which suppresses the movement jump of the ink fluid 5 and better realizes the gray level control of the electrowetting device.

[0055] Reference Figure 7 The second aspect of the present invention provides a preparation method for preparing a lower substrate 1 of an electrowetting device. The preparation method includes, but is not limited to, the following steps:

[0056] Step S100: A flow guiding structure 10 as described in the first aspect embodiment is provided in the pixel grid of the substrate 6 of the lower substrate 1.

[0057] Understandably, by setting the current-guiding structure 10 with a slope structure, the grayscale control (increase or decrease in aperture ratio) of the electrowetting device can be well displayed when the voltage increases or decreases.

[0058] It should be noted that step S100 includes, but is not limited to, the following steps:

[0059] Step S1001: Set the current guiding structure 10. Multiple current guiding structures 10 are fabricated on the dielectric layer 8 of the substrate 6 by nanoimprinting process.

[0060] Step S1002: A hydrophobic insulating layer 17 is formed by coating the dielectric layer 8 with a hydrophobic insulating material.

[0061] Step S1003: Set a pixel grid. Pixel walls are formed on the hydrophobic insulating layer 17 by a coating, exposure and development process. The pixel walls are formed in the interval area between adjacent flow guiding structures 10 and surround each flow guiding structure 10 individually. The pixel walls surrounding the flow guiding structure 10 enclose and form the pixel grid.

[0062] Understandably, by introducing nanoimprinting technology, 3D changes in the flow guiding structure 10 can be achieved to form a flow guiding structure 10 with a slope structure within the pixel grid.

[0063] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A lower substrate of an electrowetting device, characterized in that, The application relates to a substrate provided with a plurality of pixel cells, each pixel cell being provided with a flow guide structure having a first side and a second side, the thickness of the flow guide structure gradually decreasing from the first side to the second side, and a gap between the periphery of the flow guide structure and the cell wall of the pixel cell. The first side and the second side of the flow guide structure are arranged along a diagonal direction of the pixel cell. The height of the first side is less than the height of the pixel cell.

2. The lower substrate of an electro wetting device according to claim 1, wherein The height ratio of the first side of the flow guide structure to the height of the pixel cell is 0.6 to 0.

8.

3. The lower substrate of an electro wetting device according to claim 2, wherein, The second side of the flow guide structure has a cutout.

4. The lower substrate of an electro wetting device according to claim 3, wherein The width of the gap is 3 to 8 microns.

5. The lower substrate of an electro wetting device according to claim 2, wherein, The preparation method comprises the following steps:

6. The lower substrate of an electro wetting device according to claim 1, wherein, arranging the flow guide structure in the pixel cell of the substrate of the lower substrate; 7. A method of manufacturing, for manufacturing a lower substrate of an electrowetting device according to any one of claims 1 to 6, characterized in that, arranging the flow guide structure in the pixel cell of the substrate of the lower substrate comprises the following steps: arranging the flow guide structure, and manufacturing a plurality of flow guide structures on the dielectric layer of the substrate by a nano-imprinting process; 8. The method of claim 7, wherein, arranging a hydrophobic insulation layer, and coating a hydrophobic insulation material on the dielectric layer to form the hydrophobic insulation layer; arranging a pixel cell, and forming a pixel wall body on the hydrophobic insulation layer by a glue-coating, exposure and development process, the pixel wall body being formed in the interval region between adjacent flow guide structures and individually surrounding each flow guide structure, the pixel wall body surrounding the flow guide structure being enclosed to form the pixel cell. The application further relates to a lower substrate of an electrowetting device comprising any one of the above-mentioned substrates. ​ 9. An electro wetting device, characterized in that ​

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