WO2022028054A1 - Electrowetting display device structure and packaging method therefor - Google Patents

Abstract

Disclosed are an electrowetting display device structure and a packaging method thereof. The electrowetting display device structure comprises an upper substrate and a lower substrate which are oppositely disposed; the upper substrate sequentially comprises a first substrate, a first electrode, and conductive pixel walls along a direction towards the lower substrate; the conductive pixel walls define pixel grids; the lower substrate sequentially comprises a second substrate, a second electrode, and a hydrophobic insulating layer along a direction towards the upper substrate; an adjusting region is formed between the upper substrate and the lower substrate; the adjusting region is filled with polar liquid and non-polar liquid which are immiscible; and end portions of the conductive pixel walls extend into the non-polar liquid. According to the present invention, by disposing the conductive pixel walls on the upper substrate, defects caused by surface modification and high-temperature backflow of the material of a hydrophobic insulating layer can be avoided, and the original characteristics of the surface of the hydrophobic insulating layer are completely ensured to be not damaged, thereby improving the reliability of an electrowetting optical device.

Description

Electrowetting display device structure and packaging method thereof technical field

The present invention relates to the technical field of electrowetting, and in particular, to an electrowetting display device structure and a packaging method thereof.

Background technique

Electrowetting: Electrowetting (EW) refers to changing the wettability of the droplet on the substrate by changing the voltage between the droplet and the hydrophobic dielectric layer, that is, changing the contact angle to deform the droplet. , the phenomenon of displacement. The electrowetting display is a reflective display device based on the electrowetting principle, which reflects the external light source through inks with different colors, thereby realizing a full-color display effect. Electrowetting displays have the advantages of low energy consumption, wide color gamut, high response, high contrast, and visual health, so they are considered to be one of the mainstream display technologies in the future. In recent years, the demand for foldability and convenience of display devices has been increasing, and research on flexible display devices has also increased. The pixel structure in electrowetting devices is driven by soft materials such as oil and water. Electrowetting display devices have natural advantages and potential in the field of flexibility.

Referring to FIG. 1, the basic structure of the electrowetting device consists of two upper and lower substrates and two immiscible polar liquids 10' and a non-polar solution 9' filled in a sealed cavity formed by opposing the two substrates. The lower substrate contains The structure includes a lower support plate 4', a first electrode 5', a hydrophobic insulating layer (or an insulating layer coated with a hydrophobic material on the surface) 6', and a pixel wall 7'. The upper substrate includes an upper support plate 1', a second electrode 2', a sealant frame 3', and a support column structure 8'. The pixel grid area enclosed between the pixel walls is the display area. The hydrophobicity of the material of the pixel wall 7' is lower than that of the hydrophobic insulating layer 6', and the pixel wall 7' is suitable for the polar liquid 10' and the non-polar solution 9. ', so that the wettability of the polar liquid 10' on the surface of the pixel wall 7' is better, so that the non-polar solution 9' can be filled in each pixel grid and the hydrophilicity of the pixel wall 7' can be controlled. The non-polar liquid 9' in each pixel is isolated. The materials used in the electrowetting device are generally transparent materials, except that the non-polar solution 9' is mostly colored opaque materials or materials with low light transmittance, where the light transmittance of the material generally depends on the application direction of the electrowetting device. The preparation process for the above-mentioned flexible electrowetting device structure is to coat a hydrophobic insulating layer 6 on the lower support plate 4' with the first electrode 5' by methods such as spin coating, screen printing, slit coating, etc. '. Then a layer of photoresist is coated on the surface of the hydrophobic insulating layer 6' to prepare pixel walls, but because the surface energy of the hydrophobic insulating layer 6' is very low and has a very low contact angle hysteresis, such as Teflon AF1600, the advancing contact angle is 124±2 °, the receding contact angle is 113±2°, so it is difficult to coat a uniform photoresist film on the surface of the hydrophobic insulating layer 6'. The method used by most electrowetting devices at present is to change the hydrophilicity of the surface of the hydrophobic insulating layer 6' by plasma modification to make it easier to coat the photoresist on its surface. After the surface modification, the contact angle hysteresis of the hydrophobic insulating layer 6' increases, the surface adhesion increases, and it is easier for photoresist to form a film on its surface. After the photoresist film formation, curing, photolithography, and development are completed, in order to restore the hydrophobicity of the modified surface of the hydrophobic insulating layer 6', it is necessary to reflow the fresh fluororesin material at the bottom of the hydrophobic insulating layer 6' by heating at a high temperature. to the surface, and reflow the fluororesin material with poor surface hydrophobicity to the bottom, and at the same time restore the flatness of the surface at high temperature to restore the hydrophobicity of the surface of the hydrophobic insulating layer 6'.

It can be seen that the current traditional electrowetting devices need to involve the modification of the surface of the hydrophobic insulating layer 6' in the preparation process, so as to ensure that the photoresist is more easily coated on the surface of the hydrophobic layer to form a uniform film, so the pixel wall 7' is After completion, a high temperature reflow method needs to be used to restore the hydrophobicity of the surface of the hydrophobic insulating layer 6'. By heating the modified film above the melting point, components with low surface energy in the film move from the bulk to the surface, and components containing oxygen atoms move from the surface to the bulk, which results in the exposure of fresh hydrophobic groups on the surface , the hydrophobicity is restored. However, high temperature reflow cannot completely restore the hydrophobicity of the hydrophobic insulating layer 6' to the properties before modification, which will lead to an increase in the hysteresis angle. This causes problems with shrinking and spreading of the non-polar solution 9' during device opening and closing. At the same time, the temperature of high-temperature reflow is relatively high, and the lower support plate 4' is easily affected by high temperature and deforms and bends, thereby affecting the bending performance of the flexible electrowetting display device. The operation of high temperature reflow is also likely to cause deformation of the structure of the pixel wall 7', thereby affecting the optoelectronic performance and stability of the device. The surface of the hydrophobic insulating layer covered by the pixel wall 7' is different from the surface of the hydrophobic insulating layer 6' exposed in the cavity. , and impurities remaining in the development process of the pixel wall 7' can cause the failure of the electrowetting device.

In addition, in order to prevent the short circuit of the device caused by the interlayer flow during the bending process of the traditional electrowetting device, a support column structure 8' is usually set on the upper support plate 1'. Due to the limitation of process accuracy, the positioning of the packaging is easily caused by the dislocation of the support column structure 8' and the pixel wall 7', which affects the flatness of the upper and lower substrates, and thus affects the performance stability and yield of the device.

SUMMARY OF THE INVENTION

The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the present invention proposes an electrowetting display device structure and a packaging method thereof, which can avoid the defects caused by surface modification of the hydrophobic insulating layer material and high temperature reflow, and completely ensure that the original characteristics of the surface of the hydrophobic insulating layer are not damaged. , in order to improve the reliability of electrowetting optics.

The technical scheme adopted by the present invention is:

In a first aspect of the present invention, an electrowetting display device structure is provided, comprising an upper substrate and a lower substrate disposed opposite to each other, and the upper substrate sequentially includes a first substrate, a first electrode and a lower substrate along a direction toward the lower substrate. A conductive pixel wall, the conductive pixel wall encloses a pixel grid, the lower substrate sequentially includes a second substrate, a second electrode and a hydrophobic insulating layer along the direction toward the upper substrate, the upper substrate and the lower substrate An adjustment area is formed therebetween, the adjustment area is filled with mutually immiscible polar liquid and non-polar liquid, and the end of the conductive pixel wall protrudes into the non-polar liquid.

The above-mentioned hydrophobic insulating layer may be a single layer, for example, formed of a material having hydrophobic insulating properties; it may also be constituted by disposing a hydrophobic layer on the insulating layer, for example, coating a hydrophobic material on the insulating layer.

According to the electrowetting display device structure of some embodiments of the present invention, the first substrate and the second substrate are flexible substrates.

According to the electrowetting display device structure of some embodiments of the present invention, a sealant frame is disposed between the upper substrate and the lower substrate. In some embodiments, the sealant frame is a flexible sealant frame.

According to the electrowetting display device structure of some embodiments of the present invention, the material of the sealant frame is pressure-sensitive adhesive.

According to the electrowetting display device structure of some embodiments of the present invention, the first electrode and the second electrode are connected with a power supply component. The way of connecting the power supply components can be that the first electrode and the second electrode are independently connected to different power supply components, and by controlling the power supply components connected to the first electrode, the on-off state of the first electrode is controlled, and then the power supply components connected to the first electrode are controlled. The conductive pixel wall controls the switching state of the second electrode by controlling the power supply component connected to the second electrode, thereby controlling the wettability of the hydrophobic insulating layer, thereby realizing the switching of the pixel; it can also be through the circuit of the same power supply component. The control of the first electrode and the second electrode is realized in the middle, and the driving of the device is further realized.

A second aspect of the present invention provides a method for encapsulating the above-mentioned electrowetting display device structure, comprising the following steps:

Take the upper substrate, and fill the polar liquid in the pixel grid;

Filling a non-polar liquid above the polar liquid, the liquid level of the non-polar liquid is higher than the height of the conductive pixel wall;

The substrate is removed, and a sealant frame is arranged on the lower substrate, the sealant frame has an opening, and the lower substrate is covered above the upper substrate;

applying pressure to the lower substrate so that excess non-polar liquid flows out of the opening;

The opening is sealed.

According to the encapsulation method of the electrowetting display device structure according to some embodiments of the present invention, the process of applying pressure to the lower substrate includes: first applying a first pressure to a central area of the lower substrate, and then applying a first pressure to a center area of the lower substrate. A second pressure is applied to the surrounding area, and the first pressure is greater than the second pressure.

According to some embodiments of the present invention, the encapsulation method of the electrowetting display device structure further includes the step of volatilizing part of the polar liquid before the step of filling the non-polar liquid over the polar liquid.

According to the encapsulation method of the electrowetting display device structure according to some embodiments of the present invention, the method of volatilizing part of the polar liquid is any one of heating, vacuum evaporation, and adding a volatile solvent to volatilize.

According to the encapsulation method of the electrowetting display device structure according to some embodiments of the present invention, the volatile solvent includes at least one of ethylene glycol and methanol.

The beneficial effects of the embodiments of the present invention are:

The embodiment of the present invention provides an electrowetting display device structure, which cancels the traditional method of constructing a pixel wall structure on a hydrophobic insulating layer, avoids the influence of high temperature reflow on the substrate, and the hydrophobic insulating layer does not need to be formed and cured after film formation. The surface modification and recovery treatment are then carried out to completely ensure that the original characteristics of the surface of the hydrophobic insulating layer are not destroyed, maintain the hydrophobic characteristics of the surface of the hydrophobic insulating layer, and keep the surface hysteresis angle of the hydrophobic insulating layer to a minimum, which is conducive to the opening of the pixels of the electrowetting device. And the closing process improves the reliability of electrowetting optical devices, and at the same time separates and shrinks the non-polar solution through the conductive pixel walls and electrodes, solving the problem that the pixel wall structure is built on the surface of the hydrophobic insulating layer and destroys its original characteristics. risk of device failure. In addition, since the conductive pixel wall is arranged on the upper substrate in the embodiment of the present invention, the surface structure of the hydrophobic insulating layer is not damaged, so impurities will not remain on the surface of the hydrophobic insulating layer due to the developing process of the conductive pixel wall, which reduces the failure risk of the device. . In addition, in the electrowetting display device structure of the embodiment of the present invention, the conductive pixel wall is directly connected to the first electrode, and the first electrode is energized, so that the conductive pixel wall can freely cut the non-polar liquid, and the conductive pixel wall also acts as a support. The role of the column replaces the pixel wall and support column structure in the traditional electrowetting device, avoiding the traditional electrowetting device that requires the precise alignment of the pixel wall and the support column structure and the dislocation of the support column structure and the pixel wall. For the problem of the influence of bending stability, the present invention can realize the bonding package without precise alignment, can realize self-support, improve the bending performance and yield of the device, and has certain advantages in flexibility, in addition to opening the first electrode The non-polar liquid can be separated, and the non-polar liquid shrinks and reduces a certain spreading area, so the threshold value of the applied voltage required by the second electrode of the lower substrate will be correspondingly reduced, which reduces the threshold voltage to a certain extent, and realizes the device. faster response.

Description of drawings

1 is a schematic structural diagram of a conventional electrowetting device;

FIG. 2 is a schematic structural diagram of the electrowetting display device according to the first embodiment of the present invention;

3 is a schematic diagram of separation of non-polar liquids in an electrowetting display device structure when the first electrode of the upper substrate is opened;

4 is a schematic diagram of shrinkage of a non-polar liquid when the second electrode of the lower substrate in the electrowetting display device structure is opened;

5 is a schematic diagram of a pixel opening process of an electrowetting display device structure;

Fig. 6 is the filling schematic diagram of polar liquid and non-polar liquid;

FIG. 7 is a schematic diagram of the arrangement of the sealant frame of the lower substrate;

FIG. 8 is a schematic diagram of encapsulation of the upper substrate and the lower substrate.

detailed description

The concept of the present invention and the technical effects produced will be clearly and completely described below with reference to the embodiments, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts are all within the scope of The scope of protection of the present invention.

The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to 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, only used to explain the present invention, and should not be construed as a limitation of the present invention.

In the description of the present invention, it should be understood that the azimuth description, such as the azimuth or position relationship indicated by up, down, front, rear, left, right, etc., is based on the azimuth or position relationship shown in the drawings, only In order to facilitate the description of the present invention and simplify the description, it is not indicated or implied that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present invention.

In the description of the present invention, if it is described that the first and the second are only for the purpose of distinguishing technical features, it should not be understood 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.

In the description of the present invention, unless otherwise clearly defined, words such as setting, installation, connection should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

Referring to FIG. 2 , the electrowetting display device structure according to the first embodiment of the present invention is shown, including an upper substrate 10 and a lower substrate 20 . The upper substrate 10 sequentially includes a first substrate 11 , a first electrode 12 and a conductive pixel wall 13 along the direction toward the lower substrate 20 . In this embodiment, the first substrate 11 is a flexible substrate, and the flexible substrate can be exemplified by PEN (poly ethylene phthalate) or flexible glass, the first electrode 12 is an ITO electrode, the conductive pixel wall 13 encloses a pixel grid, the conductive pixel wall 13 is made of conductive photoresist, and the conductive pixel wall 13 is used as the pixel electrode and the first pixel. An electrode 12 is directly conductive. The lower substrate 20 sequentially includes a second substrate 21 , a second electrode 22 and a hydrophobic insulating layer 23 along the direction toward the upper substrate 10 . In this embodiment, the second substrate 21 is a flexible substrate, and the second electrode 22 is an ITO electrode. An adjustment area is formed between the upper substrate 10 and the lower substrate 20 , the adjustment area is filled with the polar liquid 30 and the non-polar liquid 40 that are immiscible with each other, and the end 14 of the conductive pixel wall 13 extends into the non-polar liquid 40 , but not in contact with the hydrophobic insulating layer 23 of the lower substrate 20 , that is, there is a distance between the conductive pixel wall 13 and the hydrophobic insulating layer 23 , and the distance is smaller than the average thickness of the non-polar liquid 40 , the end 14 of the conductive pixel wall 13 A non-polar liquid region 41 is formed between the hydrophobic insulating layer 23 . In the energized state, the conductive pixel wall 13 (with a certain degree of hydrophilicity) has the characteristics of the equipotential body, so that the thinner non-polar liquid region 41 under it is subjected to a greater electric field strength, resulting in the non-polarity The non-polar liquid in the liquid region 41 is preferentially broken and moved, so as to achieve the effect of display pixel segmentation. Referring to FIG. 3, a schematic diagram of the separation of the non-polar liquid in the open state of the first electrode of the upper substrate in the electrowetting display device structure is shown, When the first electrode 12 is open (ie, when it is energized), the non-polar liquid at the thin non-polar liquid region 41 under the conductive pixel wall 13 is ruptured and separated, and the conductive pixel wall 13 also acts on the upper and lower substrates of the device. The support function prevents the device from collapsing, and the non-polar liquid 40 is divided in advance due to the electric field, which reduces the threshold voltage required for the non-polar liquid 40 to shrink, and reduces the threshold voltage for pixel turn-on, thereby improving the device response speed. Referring to FIG. 4, there is shown a schematic diagram of the shrinkage of the non-polar liquid in the open state of the second electrode of the lower substrate in the electrowetting display device structure. In the open state of the second electrode 22 (ie, when energized), the second electrode 22 is applied to A certain voltage, according to the principle of electrowetting, the voltage causes the change of the surface tension, and the non-polar liquid 40 is pushed to one pass, thereby realizing the optical switch.

The driving method of the above electrowetting display structure is as follows: the first electrode 12 is connected to the conductive pixel wall 13, and the electric field of the conductive pixel wall 13 is directly affected by the first electrode 12. Referring to FIG. 5, the electrowetting display structure is shown. Pixel turn on process. When no voltage is applied, referring to FIG. 2 , the first electrode 12 and the second electrode 22 are in a pixel-off state, and the non-polar liquid 40 is in a spreading state. When a voltage is applied to the first electrode 12, the first electrode 12 is in an open state. Referring to FIG. 3, the surface wettability of the conductive pixel wall 13 changes, the electric field at the bottom of the conductive pixel wall 13 becomes stronger, and the polar liquid 30 flows toward the conductive pixel. The non-polar liquid region 41 at the bottom end of the wall 13 accumulates, thereby causing the non-polar liquid 40 to rupture. After the non-polar liquid 40 is ruptured and separated, a certain driving voltage is applied to the second electrode 22 . Referring to FIG. 4 , the surface tension of the hydrophobic insulating layer 23 of the lower substrate 20 changes due to the change in wettability, so that the non-polar liquid 40 changes in surface tension. shrink, thereby enabling electrowetting optical switches. When the opening process of the pixel is completed, the voltage of the second electrode 22 is removed, the hydrophobicity of the hydrophobic insulating layer 23 is restored, the non-polar liquid 40 is re-spread, the pixel area is closed, and finally the voltage of the first electrode 12 is removed. , at this time, the wettability of the conductive pixel wall 13 is restored, the non-polar liquid 40 spreads again, fills the non-polar liquid area 41 , and the pixel is turned off.

An embodiment of the present invention also provides a method for encapsulating the above electrowetting display structure, comprising the following steps:

(1) Preparation of the upper substrate 10 : the first electrode 12 is prepared on the first substrate 11 . The electrode film forming technology is widely used in industrial production and will not be repeated here. A layer of photoresist material is coated on the surface of the first electrode 12 to prepare the conductive pixel wall 13, and the coating methods include but are not limited to slit coating, spin coating, screen printing, flexible printing and other methods. The surface of the resist is covered with a mask, exposed by ultraviolet light, and finally obtained by developing a conductive pixel wall 13, and the conductive pixel wall is surrounded by a pixel grid.

The upper substrate 10 is turned upside down (the side with the conductive pixel walls 13 is facing upward), and the pixel grids surrounded by the conductive pixel walls 13 are filled with a polar liquid 30. In this embodiment, the polar liquid 30 is a polar electrolyte solution. The horizontal height of the polar liquid 30 is lower than the height of the conductive pixel wall 13 , so as to facilitate the subsequent filling of the non-polar liquid 40 .

(2) Referring to FIG. 6, continue to fill the non-polar liquid 40 above the polar liquid 30. The level of the non-polar liquid 40 is higher than the height of the conductive pixel wall 13, so as to ensure that the capacity of the non-polar liquid 40 is suitable for the electric It is sufficient to wet the display structure.

(3) Preparation of the lower substrate 20: the second electrode 22 is prepared on the second substrate 21 by using the existing means, and the hydrophobic insulating layer 23 is coated with a solution of a hydrophobic material by spin coating, dip coating, screen printing, flexographic printing, etc. The surface of the second electrode 22 is finally cured in a high temperature environment.

After the non-polar liquid 40 is filled, the lower substrate 20 needs to be covered on the upper substrate 10 to complete the encapsulation process. The problem to be paid attention to during the encapsulation process is how to avoid residual air bubbles in the electrowetting display structure. Aiming at this problem, the embodiment of the present invention proposes the following methods:

Referring to FIG. 7 , a sealant frame 50 is disposed on the hydrophobic insulating layer of the lower substrate 20 , the material of the sealant frame 50 can be a pressure-sensitive adhesive material, and the sealant frame 50 has at least one opening 51 , as shown in FIG. 6 , at 4 There are openings 51 at different positions, the purpose is to allow excess non-polar liquid to flow out through the openings 51 during the packaging process;

Referring to FIG. 8 , the lower substrate 20 is then covered on the upper substrate 10 , the upper substrate 10 and the lower substrate 20 are kept horizontal, and then pressure is applied to the lower substrate 20 , and the excess non-polar liquid 40 is removed from the sealant frame 50 . The openings flow out, then seal the openings with encapsulating materials such as UV acrylate, and finally press and dry to complete the encapsulation of the entire device.

In some embodiments, the process of applying pressure to the lower substrate 20 is as follows: first, a relatively large first pressure 61 is applied to the central area of the lower substrate 20 . Due to the uneven force on the lower substrate 20 , the central area of the lower substrate 20 will contact the non-polarity first. liquid 40, and then apply a small second pressure 62 to the surrounding area of the lower substrate 20, the lower substrate 20 is less deformed, the contact area with the non-polar liquid 40 increases, and the excess non-polar liquid 40 passes through the sealant frame 50 openings flow out. After the lower substrate 20 is completely in contact with the non-polar liquid 40, the opening is sealed with ultraviolet acrylate or the like, and finally the entire device is packaged by pressing and drying.

In some embodiments, in step (1), the level of the filled polar liquid 30 is made lower than the height of the conductive pixel wall 13 by volatilizing part of the polar liquid. Ways to volatilize part of the polar liquid include but are not limited to heating, vacuum evaporation, and volatilization by adding a volatile solvent. Since the volatilization process is carried out simultaneously on the entire liquid surface, when part of the polar liquid is volatilized, the entire liquid surface is still horizontal. The method of adding a volatile solvent to volatilize, for example, can add some organic solvents such as ethylene glycol or methanol with higher volatility than the polar electrolyte solution to the polar electrolyte solution, and volatilize the polar electrolyte solution without violent volatilization. In this way, the amount of liquid level drop can be precisely controlled by controlling the content of the added volatile solvent. After the volatilization process is completed, no organic components will remain in the polar electrolyte solution.

Claims (10)

1. An electrowetting display device structure is characterized in that it comprises an upper substrate and a lower substrate arranged oppositely, and the upper substrate sequentially includes a first substrate, a first electrode and a conductive pixel wall along a direction toward the lower substrate, The conductive pixel wall forms a pixel grid, the lower substrate sequentially includes a second substrate, a second electrode and a hydrophobic insulating layer along the direction toward the upper substrate, and an adjustment is formed between the upper substrate and the lower substrate The adjustment region is filled with mutually immiscible polar liquid and non-polar liquid, and the end of the conductive pixel wall protrudes into the non-polar liquid.
2. The electrowetting display device structure according to claim 1, wherein the first substrate and the second substrate are flexible substrates.
3. The electrowetting display device structure according to claim 1, wherein a sealant frame is disposed between the upper substrate and the lower substrate.
4. The electrowetting display device structure according to claim 3, wherein the material of the sealant frame is pressure-sensitive adhesive.
5. The electrowetting display device structure according to any one of claims 1 to 4, wherein a power supply component is connected to the first electrode and the second electrode.
6. A method for encapsulating an electrowetting display device structure according to any one of claims 1 to 5, characterized in that it comprises the following steps:

   Take the upper substrate, and fill the polar liquid in the pixel grid;

   Filling a non-polar liquid above the polar liquid, the liquid level of the non-polar liquid is higher than the height of the conductive pixel wall;

   The substrate is removed, and a sealant frame is arranged on the lower substrate, the sealant frame has an opening, and the lower substrate is covered above the upper substrate;

   applying pressure to the lower substrate so that excess non-polar liquid flows out of the opening;

   The opening is sealed.
7. The method for encapsulating an electrowetting display device structure according to claim 6, wherein the process of applying pressure to the lower substrate comprises: first applying a first pressure to a central area of the lower substrate, and then applying pressure to the lower substrate. A second pressure is applied to the surrounding area of the lower substrate, and the first pressure is greater than the second pressure.
8. The method for encapsulating an electrowetting display device structure according to claim 6, wherein before the step of filling the non-polar liquid above the polar liquid, it further comprises the step of volatilizing part of the polar liquid.
9. The method for encapsulating an electrowetting display device structure according to claim 8, wherein the method of volatilizing part of the polar liquid is any one of heating, vacuum evaporation, and volatilization by adding a volatile solvent.
10. The method for encapsulating an electrowetting display device structure according to claim 9, wherein the volatile solvent comprises at least one of ethylene glycol and methanol.

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