Electrowetting display screen and preparation method

Abstract

The invention relates to the technical field of electrowetting display, and discloses an electrowetting display screen and a preparation method.The electrowetting display screen comprises a first substrate assembly, a second substrate assembly, a sealing rubber frame, polar liquid and non-polar liquid, and the first substrate assembly comprises a first substrate, a first electrode layer and a hydrophobic insulating layer which are sequentially connected; the second substrate assembly comprises a second substrate, a second electrode layer and a pixel wall which are connected in sequence, the pixel wall is provided with a plurality of pixel cavities, and each pixel cavity is provided with a cavity opening opposite to the second electrode layer; one end, far away from the second electrode layer, of the pixel wall is provided with a modified area, and the modified area is at least partially located in the pixel cavity and has oleophobicity; the sealing rubber frame is connected between the second substrate and the hydrophobic insulating layer and is arranged outside the pixel wall in a surrounding manner; the pixel cavity is filled with the polar liquid and the non-polar liquid; the modified area is in contact with the hydrophobic insulating layer; or a gap is formed between the modified area and the hydrophobic insulating layer and is configured to prevent the non-polar liquid from passing through, so that the display effect can be improved.

Description

Technical Field

[0001] This invention relates to the field of electrowetting display technology, specifically to an electrowetting display screen and its preparation method. Background Technology

[0002] Electrowetting display devices are mainly based on the electrowetting effect. By applying an external voltage, the liquid filling the device is deformed and displaced, thereby enabling the ink to spread and shrink within the device.

[0003] In related technologies, inks typically exhibit a randomly broken, open edge-shrinking pattern. This pattern can easily lead to uneven pixel openings and uneven distribution of light-transmitting areas, thus affecting the display effect. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes an electrowetting display screen that can improve the display effect.

[0005] The present invention also proposes a method for preparing the above-mentioned electrowetting display screen.

[0006] An electrowetting display screen according to a first aspect of the present invention includes a first substrate assembly, a second substrate assembly, a sealing frame, a polar liquid, and a non-polar liquid. The first substrate assembly includes a first substrate, a first electrode layer, and a hydrophobic insulating layer connected in sequence. The second substrate assembly includes a second substrate, a second electrode layer, and a pixel wall connected in sequence. The pixel wall has a plurality of pixel cavities, each pixel cavity having an opening spaced apart from the second electrode layer. A modified region is provided at one end of the pixel wall away from the second electrode layer, the modified region being at least partially located within the pixel cavity and configured to be oleophobic. The sealing frame is connected between the second substrate and the hydrophobic insulating layer and surrounds the pixel wall. Both the polar liquid and the non-polar liquid fill the pixel cavity. The modified region is in contact with the hydrophobic insulating layer; or a gap is provided between the modified region and the hydrophobic insulating layer, the gap being configured to block the passage of the non-polar liquid.

[0007] The electrowetting display screen according to embodiments of the present invention has at least the following beneficial effects: By setting a modified region at one end of the pixel wall away from the second electrode layer, there are two ways to set the modified region and the hydrophobic insulating layer: the modified region is in contact with the hydrophobic insulating layer, so that the modified region and the hydrophobic insulating layer can block the passage of non-polar liquids; or there is a gap between the modified region and the hydrophobic insulating layer, and the gap is configured to block the passage of non-polar liquids. By setting the modified region at least partially in the pixel cavity and configuring it to be oleophobic, compared with the edge contraction mode of random breakage and opening of non-polar liquids in related technologies, the edge contraction mode of random breakage and opening is prone to uneven pixel opening, easy fluctuation of light transmittance, and more noise. However, the modified region of the present application embodiment has the characteristic of being repellent to non-polar liquids. The modified region and the hydrophobic insulating layer can form a confined structure. This confined structure will force the ink to uniformly contract towards the center of the pixel under the action of the electric field, which helps to obtain a uniform and regular pixel opening shape, reduces visual noise, improves the regularity of the displayed image, and improves the overall display effect of the electrowetting display screen. In addition, the confined structure can also prevent polar liquids from flowing between the modified region and the hydrophobic insulating layer, which helps the electrowetting display screen to have a more complete aperture ratio-voltage curve and a higher aperture ratio limit, enabling it to display more gray levels and smoother gray level transitions, further improving the overall display effect of the electrowetting display screen.

[0008] According to some embodiments of the present invention, the pixel wall has a side surface located within the pixel cavity and an end face facing the hydrophobic insulating layer; the side surface includes a first sub-surface and a second sub-surface distributed and connected along a first direction, the first direction being the direction of the second electrode layer toward the cavity opening; the first sub-surface is connected to the surface of the second electrode layer, and the second sub-surface is connected to the end face; the modified region includes the second sub-surface.

[0009] According to some embodiments of the present invention, when the nonpolar liquid is in a spread state, the depth of the nonpolar liquid along the first direction is less than or equal to the length of the second sub-surface along the first direction.

[0010] According to some embodiments of the present invention, the modified region further includes an end face.

[0011] According to some embodiments of the present invention, the second substrate assembly includes an oleophobic layer coated on the modified region.

[0012] According to some embodiments of the present invention, the width of the gap is ≤5 micrometers.

[0013] According to some embodiments of the present invention, the sealing frame is formed by the solidification of a mixture of several support balls and adhesive, wherein the diameter of the support balls is greater than or equal to the distance between one end of the pixel wall facing the second electrode layer and the second electrode layer.

[0014] According to a second aspect of the present invention, a method for fabricating an electrowetting display screen in any of the above embodiments is applied. The method includes: providing a first substrate assembly and a second substrate assembly; selecting a target region at one end of a pixel wall away from a second electrode layer, the target region being at least partially located within a pixel cavity; modifying the target region to obtain an oleophobic modified region; filling each pixel cavity with a polar liquid and a non-polar liquid; connecting the second substrate and a hydrophobic insulating layer through a sealing frame so that the modified region contacts the hydrophobic insulating layer; or having a gap between the modified region and the hydrophobic insulating layer, the gap being configured to block the passage of the non-polar liquid.

[0015] According to some embodiments of the present invention, the target area is modified by: modifying the target area using ultraviolet ozone radiation; or, modifying the target area using plasma surface modification; or, coating the target area with an oleophobic layer.

[0016] According to some embodiments of the present invention, connecting a second substrate and a hydrophobic insulating layer via a sealing frame includes the following steps: mixing a plurality of support balls with adhesive to form a mixed adhesive; the diameter of the support balls is greater than or equal to the distance between the end of the pixel wall facing away from the second electrode layer and the second electrode layer; applying the mixed adhesive to the surface of the second substrate and surrounding the outer periphery of the pixel wall to form a sealing frame with an outlet after curing; covering the side of the first substrate assembly with the hydrophobic insulating layer onto the sealing frame; and filling the outlet with sealant to seal the outlet.

[0017] 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

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 An exploded view of the electrowetting display screen provided in an embodiment of the present invention is shown; Figure 2 This diagram illustrates the structure of an electrowetting display screen with a non-polar liquid in a spreading state, as provided in an embodiment of the present invention. Figure 3 This diagram illustrates the structure of an electrowetting display screen with a non-polar liquid in a contracted state, as provided in an embodiment of the present invention. Figure 4 It shows Figure 3 A schematic diagram of the screen display of the CEC wettability display with pixels turned on; Figure 5 A partial structural schematic diagram of the electrowetting display screen provided in an embodiment of the present invention is shown; Figure 6A schematic flowchart of the preparation method provided in an embodiment of the present invention is shown.

[0019] Figure label: Electrowetting display screen 100; first substrate assembly 110; first substrate 111; first electrode layer 113; hydrophobic insulating layer 115; second substrate assembly 130; second substrate 131; second electrode layer 133; pixel wall 135; pixel cavity 1351; cavity opening 1361; modified area 1353; first sub-surface 1355; second sub-surface 1357; end face 1359; sealing frame 150; support ball 151; liquid outlet 153; polar liquid 170; non-polar liquid 190; first direction X. Detailed Implementation

[0020] 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.

[0021] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0022] 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. The use of "first" and "second" in the description is merely 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.

[0023] 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.

[0024] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0025] Please see Figures 1 to 3 This application provides an electrowetting display screen 100, including a first substrate assembly 110, a second substrate assembly 130, and a sealing frame 150.

[0026] The first substrate assembly 110 includes a first substrate 111, a first electrode layer 113 and a hydrophobic insulating layer 115 connected in sequence, that is, the first electrode layer 113 can be connected to the surface of the first substrate 111 and the hydrophobic insulating layer 115 can be connected to the surface of the first electrode layer 113.

[0027] The second substrate assembly 130 includes a second substrate 131, a second electrode layer 133, and a pixel wall 135 connected in sequence. That is, the second electrode layer 133 is connected to the surface of the second substrate 131, and the pixel wall 135 can be connected to the surface of the second electrode layer 133.

[0028] Both the first substrate 111 and the second substrate 131 can be transparent substrates, such as glass substrates or other transparent substrates. The first electrode layer 113, the second electrode layer 133, the hydrophobic insulating layer 115 and the pixel wall 135 can all be made of transparent materials, as can be found in the prior art, and will not be described in detail here.

[0029] The pixel wall 135 has a plurality of pixel cavities 1351, each pixel cavity 1351 having an opening 1361 spaced apart from the second electrode layer 133. Polar liquid 170 and non-polar liquid 190 are both filled within the pixel cavity 1351. The polar liquid 170 can be water or other conductive liquids, and the non-polar liquid 190 can be ink or other non-conductive liquids. It should be noted that the polar liquid 170 and non-polar liquid 190 are immiscible.

[0030] A sealing frame 150 is connected between the second substrate 131 and the hydrophobic insulating layer 115 to connect the first substrate assembly 110 and the second substrate assembly 130. The sealing frame 150 surrounds the pixel wall 135 to encapsulate the pixel wall 135 within the inner ring of the sealing frame 150.

[0031] As an example, the sealing frame 150 is generally annular, and the two opposite ends of the sealing frame 150 along the axial direction are respectively bonded to the second substrate 131 and the hydrophobic insulating layer 115 to surround the packaging space. The pixel wall 135 can be located in the packaging space, and the end of the pixel wall 135 with the cavity 1361 can be opposite to the hydrophobic insulating layer 115.

[0032] The first substrate assembly 110 has a hydrophobic insulating layer 115 on one side of the pixel wall 135 with a cavity 1361, so as to cover the cavity 1361.

[0033] As an example, the second substrate assembly 130 may further include a sealing frame, which may be attached to the surface of the second electrode layer 133 or the surface of the second substrate 131, and the sealing frame may surround the outer periphery of the pixel wall 135. The end of the sealing frame away from the second substrate 131 may be bonded to the hydrophobic insulating layer 115, thereby encapsulating the pixel wall 135 within the sealing frame.

[0034] It should be noted that, based on the hydrophobic insulating layer 115's affinity for nonpolar liquid 190 and the polar liquid 170's properties (i.e., oleophilic and hydrophobic properties), within the pixel cavity 1351, the nonpolar liquid 190 typically spreads and adsorbs onto the hydrophobic insulating layer 115 (e.g., ...). Figure 2 As shown); and under the action of an electric field, the nonpolar liquid 190 will shrink on the hydrophobic insulating layer 115 (as shown). Figure 3 (As shown).

[0035] The hydrophobic insulating layer 115 can be made of fluororesin or other hydrophobic insulating materials.

[0036] The first electrode layer 113 and the second electrode layer 133 have opposite polarities, that is, one of the first electrode layer 113 and the second electrode layer 133 is a positive electrode and the other is a negative electrode, so as to form an electric field after energization.

[0037] The pixel wall 135 has a modified region 1353 at the end away from the second electrode layer 133. There are two ways to arrange the modified region 1353 and the hydrophobic insulating layer 115: the modified region 1353 is in contact with the hydrophobic insulating layer 115, so that the modified region 1353 and the hydrophobic insulating layer 115 are in contact with each other and can block the passage of non-polar liquid 190; or there is a gap between the modified region 1353 and the hydrophobic insulating layer 115, and the gap is configured to block the passage of non-polar liquid 190. The modified region 1353 is at least partially located within the pixel cavity 1351 and is configured to be oleophobic. Thus, compared to the edge-shrinking mode of random breakage and opening of non-polar liquids in related technologies, which easily leads to uneven pixel openings, fluctuating light transmittance, and high noise, the modified region 1353 in this embodiment has the characteristic of repelling non-polar liquid 190. The modified region 1353 and the hydrophobic insulating layer 115 can cooperate to form a confinement structure. This confinement structure forces the ink to uniformly shrink towards the pixel center under the action of an electric field (i.e., centripetal shrinkage, such as...). Figure 3 and Figure 4 As shown, this helps to obtain a uniform and regular pixel opening shape, reduces visual noise, improves the regularity of the displayed image, and enhances the overall display effect of the electrowetting display screen 100.

[0038] In addition, the confinement structure can also prevent polar liquid 170 from crossing the wall between modified region 1353 and hydrophobic insulating layer 115 (i.e., non-polar liquid 190 from one pixel cavity 1351 into another adjacent pixel cavity 1351), which helps the electrowetting display screen 100 to have a more complete aperture ratio-voltage curve and a higher aperture ratio limit, enabling it to display more gray levels and smoother gray level transitions, further improving the overall display effect of the electrowetting display screen 100.

[0039] Specifically, in the electrowetting display of the related technology, the pixel wall is usually far from the first substrate assembly, the pixel cavity is a semi-open space, and the non-polar liquid has the conditions to flow arbitrarily between the pixel cavities.

[0040] The non-polar liquid 190 inside the pixel cavity 1351 ruptures by overcoming the interfacial tension of the liquid with the help of an electric field. Affected by multiple factors such as electric field and interfacial tension, there is a threshold voltage (i.e., a certain voltage value must be reached before it can open). The non-polar liquid 190 is prone to breaking through the wall under high voltage, resulting in poor grayscale display effect. In this application, the pixel cavity 1351 is in a fully enclosed space. The confined structure restricts the possibility of ink overflowing. The edge of the non-polar liquid 190 is fixed by the pixel wall 135, i.e., the contact angle is fixed. The center and edge of the non-polar liquid 190 form a capillary pressure difference due to the difference in the radius of curvature. This pressure difference, the vertical electric field of the upper and lower electrodes, and the oleophobicity of the modified region 1353 can work together to drive the non-polar liquid 190 to shrink towards the pixel center. As the step voltage gradually increases, the grayscale transition is smoother. There is no threshold voltage, and it can open at low voltage. The non-polar liquid 190 cannot overflow at high voltage, and the voltage tolerance limit is higher. Thus, a more complete aperture ratio-voltage curve and a higher aperture ratio limit can be obtained, which can display more grayscale levels and smoother grayscale transition.

[0041] It should be noted that the pixel wall 135 can be formed by the intersection of several sub-pixel walls, and the intersection of several sub-pixel walls can surround several pixel cavities 1351. Each sub-pixel wall can have a modified region 1353 at the end away from the second electrode layer 133, that is, the pixel cavity 1351 has a modified region 1353 around the cavity opening 1361.

[0042] In some embodiments, the pixel wall 135 has a side surface located within the pixel cavity 1351 and an end face 1359 at one end facing the hydrophobic insulating layer 115.

[0043] The side surface may include a first sub-surface 1355 and a second sub-surface 1357 distributed along a first direction. The first sub-surface 1355 and the second sub-surface 1357 may be connected to each other. The first sub-surface 1355 may be connected to the surface of the second electrode layer 133, and the second sub-surface 1357 may be connected to the end face 1359. The first direction is the direction of the second electrode layer 133 toward the cavity opening 1361. The first direction is parallel or approximately parallel to the thickness direction of the electrowetting display screen 100.

[0044] The modified region 1353 may include a second sub-face 1357, so that only the second sub-face 1357 on the side can be set to be oleophobic, which helps to prevent the second sub-face 1357 from forming a confined structure by cooperating with the hydrophobic insulating layer 115.

[0045] The end of the second sub-surface 1357 away from the second electrode layer 133 along the first direction can be in contact with or separated from the hydrophobic insulating layer 115, so that a confined structure can be formed between the second sub-surface 1357 and the hydrophobic insulating layer 115.

[0046] In some embodiments, the nonpolar liquid 190 is in a spread state (e.g. Figure 2 As shown, the depth of the nonpolar liquid 190 along the first direction is less than or equal to the length of the second sub-surface 1357 along the first direction. Therefore, when the nonpolar liquid 190 is in a spread state, its edges can completely contact the second sub-surface 1357. This helps the nonpolar liquid 190 to better achieve centripetal contraction under the confined structure and electric field, switching from a spread state to a contraction state (as shown). Figure 3 and Figure 4 As shown), this can prevent the ink from contacting the first sub-surface 1355, which would cause the ink in that part to randomly break open and shrink under the action of the electric field.

[0047] The nonpolar liquid 190 is in a spreading state, which can refer to the state in which the nonpolar liquid 190 is spread out when the first electrode layer 113 and the second electrode layer 133 are not energized.

[0048] In some embodiments, the modified region 1353 also includes the end face 1359 of the pixel wall 135, so that the end region of the pixel wall 135 can be modified as a whole without avoiding the end face 1359, thus reducing the difficulty of modification; in addition, since the end face 1359 also has the property of repelling the non-polar liquid 190, the situation of the non-polar liquid 190 crossing the wall between the end face 1359 and the hydrophobic insulating layer 115 (i.e., the non-polar liquid 190 entering an adjacent pixel cavity 1351 from one pixel cavity 1351) can be improved.

[0049] It should be noted that the end of the second sub-surface 1357 away from the second electrode layer 133 along the first direction and the end face 1359 are approximately on the same plane, that is, the end face 1359 can be in contact with or spaced apart from the hydrophobic insulating layer 115.

[0050] In some embodiments, the modified region 1353 can be a region that has undergone modification treatment, and the modification treatment can be a plasma surface modification process, ultraviolet ozone radiation method, etc.

[0051] In some embodiments, the second substrate assembly 130 may further include an oleophobic layer, which may be coated on the modified region 1353, thereby making the modified region 1353 oleophobic, and the structure of the oleophobic layer is more stable and the preparation process is simpler.

[0052] The oleophobic layer can be a Teflon layer, a fluoropolymer (Hyflon) layer, a fluorosilane layer, or other oleophobic layers. The oleophobic layer can also be a transparent layer.

[0053] In some embodiments, the width of the gap between the modified region 1353 and the hydrophobic insulating layer 115 is ≤5 micrometers, that is, the distance between the end of the pixel wall 135 facing the hydrophobic insulating layer 115 and the hydrophobic insulating layer 115 is ≤5 micrometers, so that the gap can block the non-polar liquid 190.

[0054] Please see Figure 1 , Figure 2 and Figure 5 In some embodiments, the sealing frame 150 may consist of a plurality of support balls 151 (e.g., Figure 1 The mixture (shown) and glue are mixed to form a solidified adhesive. The diameter of the support ball 151 is greater than or equal to the distance between the end of the pixel wall 135 facing away from the second electrode layer 133 and the second electrode layer 133, thereby ensuring that a confined structure can be formed between the modified region 1353 and the hydrophobic insulating layer 115.

[0055] Specifically, the sealing frame in related technologies is usually a solid structure. The solid sealing frame connects the upper and lower substrates by adhesive bonding. However, since the height of the pixel wall along the first direction is usually very small, only tens of micrometers, the manufacturing difficulty of a sealing frame with a height of only tens of micrometers is very high. Therefore, the modified area and the hydrophobic insulating layer are either too far apart to form a confined structure, or the height of the pixel wall needs to be increased to allow the modified area and the hydrophobic insulating layer to contact or be spaced apart, but this increases the thickness of the electrowetting display.

[0056] The sealing frame 150 in this application is formed by dispensing a mixed adhesive. The height of the sealing frame 150 along the first direction is approximately affected by the diameter of the support ball 151. Compared with a solid sealing frame, the support ball 151 is easier to produce and can flexibly match the height of the pixel wall 135 without increasing the height of the pixel wall 135. This reduces the thickness of the electrowetting display screen 100, shrinks the size of the electrowetting display screen 100, and ensures that the modified region 1353 is infinitely close to the hydrophobic insulating layer 115, so that a confined structure can be formed between the modified region 1353 and the hydrophobic insulating layer 115.

[0057] The support ball 151 can be made of silicon (such as silica) or other materials. It supports the second substrate 131 and the hydrophobic insulating layer 115, and provides a carrier for the adhesive. Because the adhesive is viscous, using a spherical support ball 151 helps to more stably position it in the desired location during dispensing, reducing positional shifts. The adhesive is used to bond the second substrate 131, the support ball 151, and the hydrophobic insulating layer 115, thus connecting and fixing them together. The adhesive can be any commonly used in the field of electrowetting display screens 100, and this application is not limited to any particular type.

[0058] The distance between the end of the pixel wall 135 facing away from the second electrode layer 133 and the second electrode layer 133 is the height of the pixel wall 135 along the first direction.

[0059] Understandably, when the diameter of the support ball 151 is equal to the height of the pixel wall 135 along the first direction, the modified region 1353 is in approximately contact with the hydrophobic insulating layer 115. When the diameter of the support ball 151 is greater than the height of the pixel wall 135, there is a gap between the modified region 1353 and the hydrophobic insulating layer 115.

[0060] It should be noted that when the diameter of the support ball 151 is greater than the height of the pixel wall 135, the diameter of the support ball 151 needs to be controlled to ensure that the width of the gap between the modified region 1353 and the hydrophobic insulation is ≤5 micrometers.

[0061] This application also provides a preparation method, which can be applied to the electrowetting display screen in any of the above embodiments. The preparation method includes steps S010, S020, S030, S040 and S050.

[0062] Step S010: Provide a first substrate assembly and a second substrate assembly.

[0063] The specific structures of the first substrate assembly and the second substrate assembly can be referred to the above-described structural embodiment of the electrowetting display screen, and will not be repeated here.

[0064] As an example, the fabrication steps of the first substrate assembly may include the steps of: (1) providing a first substrate; (2) depositing a first electrode layer on the surface of the first substrate by a process such as electrode sputtering; and (3) spin-coating a hydrophobic insulating layer on the surface of the first electrode layer.

[0065] The fabrication steps of the second substrate assembly may include the following steps: (1) providing a second substrate; (2) depositing a second electrode layer on the surface of the second substrate by processes such as electrode sputtering; (3) spin-coating photoresist on the surface of the second conductive layer; (4) etching the photoresist to form a pixel wall with a plurality of pixel cavities; wherein, etching the photoresist may refer to the exposure and development of the photoresist under a photolithography machine through a mask, that is, the pixel wall may be formed by photoresist.

[0066] The hydrophobic insulating layer in this embodiment does not require a secondary modification process, which helps to avoid damage to the hydrophobic insulating layer, ensures the reliability of the electrowetting display screen, and extends the service life of the electrowetting display screen. Furthermore, since the hydrophobic insulating layer does not require a secondary modification process, the manufacturing process of the electrowetting display screen is simplified, and the manufacturing cost is reduced.

[0067] Specifically, in related technologies, photoresist is typically spin-coated onto a hydrophobic insulating layer to form pixel walls. However, since the hydrophobic insulating layer and photoresist are not mutually wettable, it is difficult to spin-coat photoresist onto the hydrophobic insulating layer. Therefore, a modification process (e.g., etching the hydrophobic insulating layer using a plasma etching machine) is required to make the hydrophobic insulating layer more hydrophilic, facilitating the spin-coating of photoresist. However, because the hydrophobic insulating layer has undergone a modification process and has good hydrophilicity, this can affect the flow of polar liquids. Therefore, a secondary modification process (e.g., high-temperature reflow process) is required to restore the hydrophobicity of the hydrophobic insulating layer. In other words, related technologies require two modification processes for the hydrophobic insulating layer, which can easily cause irreparable defects in the hydrophobic insulating layer, affecting the reliability and lifespan of the electrowetting display, and leading to complex fabrication methods and increased manufacturing costs.

[0068] In this embodiment, the pixel wall is set on the second electrode layer (i.e., photoresist for preparing the pixel structure is spin-coated on the second electrode layer), eliminating the need to spin-coat photoresist on the hydrophobic insulating layer. This eliminates the need for primary and secondary modification processes of the hydrophobic insulating layer, simplifies the fabrication process of the electrowetting display, reduces manufacturing costs, and ensures the reliability and service life of the electrowetting display.

[0069] Step S020: Select the end of the pixel wall furthest from the second electrode layer as the target area; The target region is located at least partially within the pixel cavity, and the target region generally includes the second sub-face and end face in the above embodiments.

[0070] There can be a dividing line between the target area and other non-target areas to facilitate the identification of the target area; or the non-target areas can be covered with a film such as adhesive tape to expose the target area; or the range of the target area can be roughly judged by workers based on experience during the subsequent modification process.

[0071] Step S030: Modify the target area to obtain a modified area with oleophobic properties.

[0072] Step S040: Fill each pixel cavity with polar liquid and non-polar liquid.

[0073] Step S050: Connect the second substrate and the hydrophobic insulating layer through a sealing frame so that the modified region is in contact with the hydrophobic insulating layer; or there is a gap between the modified region and the hydrophobic insulating layer, the gap being configured to block the passage of non-polar liquids.

[0074] Thus, the modified region has the property of repelling non-polar liquids. The modified region and the hydrophobic insulating layer can form a confined structure. This confined structure forces the ink to shrink uniformly toward the center of the pixel under the action of the electric field, which helps to obtain a uniform and regular pixel opening shape, reduces visual noise, improves the regularity of the display image, and improves the overall display effect of the electrowetting display screen.

[0075] In addition, the confined structure can also prevent polar liquids from flowing between the modified region and the hydrophobic insulating layer, which helps the electrowetting display screen to have a more complete aperture ratio-voltage curve and a higher aperture ratio limit, enabling it to display more gray levels and smoother gray level transitions, further improving the overall display effect of the electrowetting display screen.

[0076] Specifically, in the electrowetting display of the related technology, the pixel walls are usually far apart from the first substrate components, the pixel cavity is a semi-open space, and the non-polar liquid has the conditions to flow freely between the pixel cavities.

[0077] The rupture of non-polar liquid within a pixel cavity relies on an electric field to overcome the interfacial tension of the liquid. Influenced by multiple factors such as the electric field and interfacial tension, a threshold voltage exists, making it prone to "wall-breaking" at high voltages, resulting in poor grayscale display. In contrast, the pixel cavity of this application is in a fully enclosed space. The confined structure restricts the possibility of ink "wall-breaking," and the edge of the non-polar liquid is fixed by the pixel wall, i.e., the contact angle is fixed. A capillary pressure difference is formed between the center and edge of the non-polar liquid due to the difference in curvature radius. This pressure difference, the vertical electric field of the upper and lower electrodes, and the oleophobicity of the modified area can synergistically drive the non-polar liquid to contract towards the pixel center. This contraction occurs gradually with the stepped voltage, resulting in a smoother grayscale transition. There is no threshold voltage; the liquid can open at low voltage, while the non-polar liquid cannot break through the wall at high voltages, exhibiting a higher voltage tolerance limit. This allows for a more complete aperture ratio-voltage curve and a higher aperture ratio limit, enabling the display of more grayscale levels and smoother grayscale transitions.

[0078] When filling polar and non-polar liquids, the polar liquid can be filled into each pixel cavity first, followed by the non-polar liquid. Filling methods can include inkjet printing, micro-piston pump technology, or other methods.

[0079] In some embodiments, step S030 may include the step of modifying the target area using ultraviolet ozone radiation.

[0080] The method of modifying the target area using ultraviolet ozone radiation is relatively simple, has high modification efficiency, short process cycle, good uniformity of the modified area, and is environmentally friendly.

[0081] As an example, when modifying a target area using ultraviolet ozone radiation, the second substrate assembly can be placed in the chamber of an ultraviolet ozone device, and the target area can be placed in the irradiation area of ​​the ultraviolet light source. The ultraviolet light source is then turned on to irradiate the target area, causing the photosensitizer in the target area to undergo photolysis, which destroys the photoresist crosslinking structure of the target area. Furthermore, the oxygen in the chamber generates ozone under the irradiation of ultraviolet light, and the ozone further oxidizes and decomposes the photoresist. Oxygen-containing polar groups are introduced into the target area. These oxygen-containing polar groups have hydrophilic and oleophobic characteristics, thereby modifying the target area into an oleophobic modified area.

[0082] Ultraviolet ozone radiation is a common modification process in this field. The above example is only for illustrative purposes. The specific steps can be referred to the existing technology and will not be repeated here.

[0083] In some embodiments, step S030 may include the step of modifying the target area using a plasma surface modification process.

[0084] Plasma surface modification technology can create a more stable oleophobic modified zone in the target area.

[0085] As an example, when using plasma surface modification technology to modify the target area, the second substrate assembly can be placed in the chamber of the plasma device, and fluorine-containing gas (such as CF4, C2F6) can be injected into the chamber. The fluorine-containing gas is ionized to generate plasma. The target area is bombarded by the plasma, and the fluorine-containing active particles react with the surface of the target area during the plasma bombardment, introducing fluorine-containing oleophobic functional groups such as -CF3, so as to modify the target area to have oleophobic properties.

[0086] Plasma surface modification is a common modification process in this field. The above example is only for illustrative purposes. The specific steps can be referred to the existing technology and will not be repeated here.

[0087] In some embodiments, step S030 may include the step of: applying an oleophobic coating to the target area.

[0088] In this embodiment, by coating the target area with an oleophobic layer to obtain an oleophobic modified region, the structure of the oleophobic layer is more stable, extending the service life of the electrowetting display.

[0089] In some embodiments, connecting the second substrate and the hydrophobic insulating layer via a sealing frame may include the following steps: (1) Mix several support balls with glue to form a mixed glue; the diameter of the support ball is greater than or equal to the distance between the end of the pixel wall facing the second electrode layer and the second electrode layer.

[0090] (2) Apply the mixed adhesive to the surface of the second substrate and surround it around the periphery of the pixel wall to form an outlet (e.g., after curing) Figure 5 The sealing frame of the liquid outlet 153 shown.

[0091] (3) Cover the side of the first substrate assembly with the hydrophobic insulating layer onto the sealing frame.

[0092] (4) Fill the outlet with sealant to seal the outlet.

[0093] Thus, the sealing frame in this application is formed by dispensing a mixed adhesive. The height of the sealing frame along the first direction is approximately affected by the diameter of the supporting ball. Compared to a solid sealing frame, the supporting ball is easier to produce and can flexibly match the height of the pixel wall without increasing the height of the pixel wall. This reduces the thickness of the electrowetting display and the size of the electrowetting display, while ensuring that the modified area is infinitely close to the hydrophobic insulating layer, so that a confined structure can be formed between the modified area and the hydrophobic insulating layer. For details, please refer to the above-described structural embodiment of the sealing frame of the electrowetting display, which will not be repeated here.

[0094] In this process, when filling the pixel wall with non-polar liquid, an overfill is required to ensure that the non-polar liquid completely fills the pixel cavity and guarantees the display effect. The outlet is used to allow excess non-polar liquid to drain out of the encapsulation space. The number of outlets can be one, two, or more. The location of the outlets can be flexibly set according to requirements, and this application does not impose any limitations.

[0095] UV-curable sealants can be used to improve production efficiency. UV-curable sealants are adhesives that cure under ultraviolet light.

[0096] The encapsulation process of the first substrate assembly covering the second substrate assembly is as follows: the second substrate assembly is laid flat with the pixel cavity opening facing upwards. The side of the first substrate assembly with the hydrophobic insulating layer is covered onto the pixel wall. During the pressing process, pressure is applied to the first substrate assembly, and excess non-polar liquid flows out from the liquid outlet, which is then sealed with sealant.

[0097] During the encapsulation process, the process of applying downward pressure to the first substrate assembly is as follows: a first pressure is applied to the edge farther from the liquid outlet, and excess non-polar liquid is squeezed to the center of the pixel wall; a second pressure is applied to the center of the first substrate assembly, and the second pressure can be greater than the first pressure to prevent the phenomenon of central bulging of the electrowetting display during the encapsulation process. At this time, excess non-polar liquid will continue to be squeezed to the liquid outlet; downward pressure is applied to the first substrate assembly at the liquid outlet to bond and encapsulate the first substrate assembly and the second substrate assembly.

[0098] In the electrowetting display screen 100 and its manufacturing method provided in this application embodiment, a modified region 1353 is provided at one end of the pixel wall 135 away from the second electrode layer 133. There are two configuration methods between the modified region 1353 and the hydrophobic insulating layer 115: the modified region 1353 contacts the hydrophobic insulating layer 115, thereby blocking the passage of non-polar liquid 190; or a gap exists between the modified region 1353 and the hydrophobic insulating layer 115, and this gap is configured to block the passage of non-polar liquid 190. The modified region 1353 is at least partially disposed within the pixel cavity 1351 and configured as follows: The modified region 1353 of this embodiment is oleophobic. Compared to the edge-shrinking pattern of random breakage and opening of non-polar liquids in related technologies, which easily leads to uneven pixel openings, fluctuating light transmittance, and increased noise, the modified region 1353 in this embodiment has the characteristic of repelling non-polar liquid 190. The modified region 1353 and the hydrophobic insulating layer 115 can form a confinement structure. This confinement structure forces the ink to uniformly shrink towards the pixel center under the action of an electric field, helping to obtain a uniform and regular pixel opening shape, reducing visual noise, improving the regularity of the displayed image, and enhancing the overall display effect of the electrowetting display screen 100. Furthermore, the confinement structure can also prevent polar liquid 170 from flowing between the modified region 1353 and the hydrophobic insulating layer 115, helping the electrowetting display screen 100 to have a more complete aperture ratio-voltage curve and a higher aperture ratio limit, enabling it to display more gray levels and smoother gray-scale transitions, further improving the overall display effect of the electrowetting display screen 100.

[0099] 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, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electrowetting display screen, characterized in that, include: The first substrate assembly includes a first substrate, a first electrode layer, and a hydrophobic insulating layer connected in sequence. The second substrate assembly includes a second substrate, a second electrode layer, and a pixel wall connected in sequence. The pixel wall has a plurality of pixel cavities, each of which has an opening spaced apart from the second electrode layer. The end of the pixel wall away from the second electrode layer has a modified region, which is at least partially located within the pixel cavity and configured to be oleophobic. A sealing frame is connected between the second substrate and the hydrophobic insulating layer, and surrounds the pixel wall; Both polar and non-polar liquids are filled into the pixel cavity; The modified region is in contact with the hydrophobic insulating layer; Alternatively, there may be a gap between the modified region and the hydrophobic insulating layer, the gap being configured to block the passage of the nonpolar liquid.

2. The electrowetting display screen according to claim 1, characterized in that, The pixel wall has a side located inside the pixel cavity, and has an end face at one end facing the hydrophobic insulating layer; The side surface includes a first sub-surface and a second sub-surface distributed and connected along a first direction, the first direction being the direction of the second electrode layer toward the cavity opening; the first sub-surface is connected to the surface of the second electrode layer, and the second sub-surface is connected to the end face; the modified region includes the second sub-surface.

3. The electrowetting display screen according to claim 2, characterized in that, When the nonpolar liquid is in a spread state, the depth of the nonpolar liquid along the first direction is less than or equal to the length of the second sub-surface along the first direction.

4. The electrowetting display screen according to claim 2, characterized in that, The modified region also includes the end face.

5. The electrowetting display screen according to claim 1, characterized in that, The second substrate assembly includes an oleophobic layer coated on the modified region.

6. The electrowetting display screen according to claim 1, characterized in that, The width of the gap is ≤5 micrometers.

7. The electrowetting display screen according to claim 1, characterized in that, The sealing frame is formed by the solidification of a mixture of several support balls and glue. The diameter of the support balls is greater than or equal to the distance between the end of the pixel wall facing the second electrode layer and the second electrode layer.

8. A preparation method, characterized in that, The method of preparing the electrowetting display screen according to any one of claims 1 to 7 comprises: The first substrate assembly and the second substrate assembly are provided; The end of the pixel wall away from the second electrode layer is selected as the target region, and the target region is at least partially located within the pixel cavity; The target area is modified to obtain the modified area with oleophobic properties; The polar liquid and the non-polar liquid are filled into each of the pixel cavities; The second substrate and the hydrophobic insulating layer are connected by the sealing frame so that the modified region is in contact with the hydrophobic insulating layer; or a gap is provided between the modified region and the hydrophobic insulating layer, the gap being configured to block the passage of the non-polar liquid.

9. The preparation method according to claim 8, characterized in that, The modification treatment of the target area includes: modifying the target area using ultraviolet ozone radiation; or modifying the target area using plasma surface modification process; or coating the target area with an oleophobic layer.

10. The preparation method according to claim 8, characterized in that, The step of connecting the second substrate and the hydrophobic insulating layer through the sealing frame includes the following steps: Several support balls are mixed with glue to form a mixed adhesive; the diameter of the support balls is greater than or equal to the distance between the end of the pixel wall facing away from the second electrode layer and the second electrode layer; The mixed adhesive is applied to the surface of the second substrate and disposed around the outer periphery of the pixel wall to form the sealing adhesive frame with a liquid outlet after curing. The side of the first substrate assembly with the hydrophobic insulating layer is covered by the sealing frame; The outlet is filled with sealant to seal it.

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