KR20110139436A

KR20110139436A - Electrophoretic display device and method for manufacturing the same

Info

Publication number: KR20110139436A
Application number: KR1020100059535A
Authority: KR
Inventors: 권오남; 임유석
Original assignee: 엘지디스플레이 주식회사
Priority date: 2010-06-23
Filing date: 2010-06-23
Publication date: 2011-12-29

Abstract

According to an aspect of the present invention, an electrophoretic display device capable of improving contrast ratio by increasing reflectance includes: a lower array including a pixel electrode; An upper plate facing the lower array and including a common electrode; A partition wall forming a plurality of pixels between the lower array and the upper plate and forming at least one color subpixel and at least one mono subpixel in each pixel; A color electrophoretic dispersed solution filled in the one or more color sub-pixels and including colored charged particles, white charged particles, and a dielectric solvent; And a monoelectrophoretic dispersion liquid filled in the at least one mono sub pixel and including white charged particles, black charged particles, and a dielectric solvent.

Description

Electrophoretic Display Device and Method for Manufacturing The Same

The present invention relates to an electrophoretic display, and more particularly, to a color electrophoretic display and a manufacturing method thereof.

The electrophoretic display device refers to a device for displaying an image using an electrophoretic phenomenon in which colored charged particles move by an electric field applied from the outside. Herein, the electrophoresis phenomenon refers to a phenomenon in which charged particles move in a liquid by a coulomb force when an electric field is applied to an electrophoretic dispersion liquid in which charged particles are dispersed in a liquid.

Such an electrophoretic display device has bistable stability, so that the original image can be preserved for a long time even if the applied voltage is removed. That is, the electrophoretic display device is particularly suitable for the field of the e-book which does not require the rapid replacement of the screen because it can maintain a constant screen for a long time even without applying a voltage continuously. In addition, unlike the liquid crystal display device, the electrophoretic display device does not have a dependency on a viewing angle and has an advantage of providing an image that is comfortable to the eye to the extent that it is similar to paper.

When a color image is to be displayed using such an electrophoretic display device, a color filter is generally used. 1 is a view showing the structure of a conventional electrophoretic display device capable of realizing a color image.

As shown in FIG. 1, an electrophoretic display device 100 for realizing a color image may be formed between opposingly bonded first and second substrates 110 and 120 and the first and second substrates 11 and 36. An electrophoretic film 130 interposed therebetween, and a color filter layer 140 formed on a lower front surface of the second substrate 120 and configured of a color filter pattern of red, green, and blue, Is formed.

The electrophoretic film 130 may include a first and second adhesive layers 132 and 136 made of a transparent material, and a common electrode 134 made of a transparent conductive material positioned between the first and second adhesive layers 132 and 136. And a plurality of microcapsules 138 having an electrophoretic dispersion. In this case, the electrophoretic dispersion includes positively charged particles and negatively charged particles.

In the conventional electrophoretic display device 100, the charged particles included in the microcapsules 138 move by electrophoresis to implement color images.

However, compared with the electrophoretic display device displaying a black and white image, such a conventional electrophoretic display device consumes more light due to the color filter, so that the amount of light that eventually enters the eye is reduced and the reflectance is low. This causes a problem that the contrast ratio is lowered.

In addition, in the conventional electrophoretic display device, not only the color filters for implementing the color image need to be aligned with the respective electrodes, but also there is a problem in that additional costs are generated due to the color filter fabrication.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide an electrophoretic display device and a method of manufacturing the same, which can improve a contrast ratio by increasing a reflectance.

Another object of the present invention is to provide an electrophoretic display device and a method of manufacturing the same, which can implement color images with various gray levels.

Another object of the present invention is to provide an electrophoretic display device and a method of manufacturing the same, which can reduce manufacturing cost.

In accordance with an aspect of the present invention, an electrophoretic display device includes: a lower array including a pixel electrode; An upper plate facing the lower array and including a common electrode; A partition wall forming a plurality of pixels between the lower array and the upper plate and forming at least one color subpixel and at least one mono subpixel in each pixel; A color electrophoretic dispersed solution filled in the one or more color sub-pixels and including colored charged particles, white charged particles, and a dielectric solvent; And a monoelectrophoretic dispersion liquid filled in the at least one mono sub pixel and including white charged particles, black charged particles, and a dielectric solvent.

According to another aspect of the present invention, there is provided a method of manufacturing an electrophoretic display device, including: manufacturing a lower array including a plurality of pixel electrodes; Forming a partition on the lower array to form a plurality of pixels, a plurality of color sub pixels constituting each pixel, and a plurality of mono sub pixels; Filling the color subpixels with colored charged particles, white charged particles, and a first dielectric solvent, and filling the mono subpixels with white charged particles, black charged particles, and a second dielectric solvent; And attaching an upper plate including a common electrode to the lower array.

According to the present invention, since the color filter is not used, the reflectance can be increased, and thus the contrast ratio can be improved.

In addition, in the present invention, since each sub-pixel is composed of a color sub-pixel composed of colored particles and white particles, and a mono sub-pixel composed of white particles and black particles, the white particles included in the colored particles and the mono sub-pixel of the colored sub-pixels. And by controlling the black charged particles there is an effect that can implement a color image of various gradations.

In addition, according to the present invention, since the color filter is not used, the color filter does not need to be aligned, and the cost of manufacturing the color filter can be reduced, resulting in a reduction in the manufacturing cost of the electrophoretic display device. It works.

1A is a cross-sectional view of a general color electrophoretic display device.
2 is an exploded perspective view of an electrophoretic display device according to an exemplary embodiment of the present invention.
3 is a cross-sectional view taken along AA of FIG. 2.
4 is a sectional view taken along line BB of FIG.
5 illustrates a method of implementing color using an electrophoretic display device according to an exemplary embodiment of the present invention.
6A through 6D are cross-sectional views illustrating a manufacturing process of an electrophoretic display device according to an exemplary embodiment of the present invention.
7A to 7E are cross-sectional views showing the manufacturing process of the lower array shown in FIG. 6A.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing embodiments of the present invention, when a structure is described as being formed "on" or "below" another structure, this description is intended to provide a third term between these structures as well as when the structures are in contact with each other. It is to be interpreted as including even if the structure is interposed. However, where the term "immediately above" or "immediately below" is used, it is to be construed that these structures are limited to being in contact with each other.

2 is an exploded perspective view of an electrophoretic display device according to an exemplary embodiment of the present invention, FIG. 3 is a sectional view taken along the line A-A of FIG. 2, and FIG. 4 is a sectional view taken along the line B-B of FIG. 2.

As shown in FIGS. 2 to 4, the electrophoretic display device 150 according to an embodiment of the present invention includes: an upper plate 310 including a common electrode 312; A lower array 200 including a plurality of pixel electrodes 220; Barrier ribs 330 forming a plurality of pixels between the lower array and the upper plate and forming at least one color sub pixel and at least one mono sub pixel in each pixel; A color electrophoretic dispersion 320 filled in the color sub-pixels and including colored charged particles, white charged particles, and a dielectric solvent; And an electrophoretic dispersion 360 filled in the mono sub pixel and including white charged particles, black charged particles, and a dielectric solvent.

The colored charged particles 322 to 326 and the white charged particles 362 filled in the color subpixels 412 by the voltages applied to the common electrode 312 and the plurality of pixel electrodes 220 are formed in the dielectric solvent 328. ), And the white charged particles 362 and the black charged particles 364 filled in the mono sub pixel 418 are moved in the dielectric solvent 328, whereby a color image is realized. It is displayed through the top plate 310.

The upper plate 310 includes a base film 311 and a common electrode 312 formed thereon. The base film 311 is made of glass or plastic, and the common electrode 312 is made of indium tin oxide (ITO) or indium zinc oxide (IZO). The base film 311 and the common electrode 312 should be transparent for image display.

The lower array 200 corresponds to a TFT substrate 210 in which thin film transistors (TFTs) are formed for each sub-pixel (color sub-pixels and mono sub-pixels), and corresponding to the TFTs (T). Pixel electrodes 220 formed on the TFT substrate 210.

The TFT substrate 210 includes a gate line (not shown) and a data line (not shown) intersected on the substrate 211. The substrate 211 may be a glass substrate, but a plastic substrate or a metal substrate may be used as the substrate 211 in order for the electrophoretic display 150 to have flexibility. Since the board | substrate 211 is located on the opposite side to the surface where an image is displayed, it does not need to be transparent. The gate line and the data line are single films made of silver (Ag), aluminum (Al), or alloys thereof having low resistivity, or in addition to these single films, chromium (Cr) having excellent electrical characteristics, The multilayer film may further include a film made of titanium (Ti) or tantalum (Ta).

A gate insulating film 213 made of a nitride film (SiNx) or the like is positioned between the gate line and the data line. A TFT (T) is formed at each intersection of the gate line and the data line.

The TFT (T) includes a gate electrode 212a branched from a gate line, a semiconductor layer 214 formed on a gate insulating film 213 in a portion corresponding to the gate electrode 212a, and a source electrode branched from the data line. 215a and a drain electrode 216. The source electrode 215a and the drain electrode 216 are spaced apart from each other on the gate insulating layer 213 and the semiconductor layer 214, and partially overlap the semiconductor layer 214. Although not shown, the TFT (T) further has an ohmic contact layer between the source electrode 215a and the semiconductor layer 214, and between the drain electrode 216 and the semiconductor layer 214, respectively. It may include.

A protective layer 217 made of a nitride film (SiNx) or the like is formed on the entire surface of the substrate 211 including the TFT (T), and each sub-pixel (color sub-pixel and mono sub) is formed on the protective layer 217. The pixel electrode 220 corresponding to the pixel) is formed. The pixel electrode 220 is connected to the drain electrode 216 of the corresponding TFT (T) through a contact hole H formed in the protective layer 217. Copper, aluminum, ITO, or the like may be used to manufacture the pixel electrode 220, and nickel and / or gold may be further stacked thereon.

When the gate signal is supplied to the gate electrode 212a of the TFT (T) through the gate line, the TFT (T) is turned on or off in response to the gate signal so that the data voltage supplied through the data line corresponds. To be applied to the pixel electrode 220.

The partition wall 330 is formed between the lower array 200 and the upper plate 310 to form a plurality of pixels 400, or one or more color sub pixels 412, 414, and 416 in the plurality of pixels 400. And one or more mono sub pixels 418.

The partition wall 330 is formed on the lower array 200. Specifically, the partition wall 330 is formed in the direction of the upper plate 310 in the region between the pixel electrodes 220 of the lower array 200.

The partition wall 330 may be a “first partition wall” forming a boundary between neighboring pixels 400, color sub-pixels 412, 424, and 416 and mono sub-pixels 418 neighboring each other in one pixel. And a “third partition wall” formed at the outermost portion of the lower array 200.

In one embodiment, a plurality of pixels 400 are formed by the first partition wall, and three color subpixels 412, 424, 416 and three mono subpixels 418 in each pixel by the second partition wall. Are formed.

In this case, the partition wall 330 may be formed such that the size ratio of the color sub pixels 412, 424, 416 and the mono sub pixel 418 is 2: 3, and one color sub pixel 412, 424, 416 is included. May operate in conjunction with one mono sub pixel 418 or may also operate in conjunction with one or more mono sub pixels.

The partition wall 330 is formed through a photolithography or mold printing process.

The color electrophoretic dispersion 320 is filled in the color subpixels 412, 414, and 416 formed by the partition wall 330. The color electrophoretic dispersion 320 includes colored charged particles, white charged particles, and Dielectric solvents.

In one embodiment, the first color subpixel 412 includes a first color electrophoretic dispersion 320 comprising a first colored charged particle 322, a white charged particle 362, and a dielectric solvent 328. The second color sub-pixel 414 is filled with a second color electrophoretic dispersion 320 including a second colored charged particle 324, a white charged particle 362, and a dielectric solvent 328, The third color subpixel 416 may be filled with a third color electrophoretic dispersion 320 including a third colored charged particle 326, a white charged particle 362, and a dielectric solvent 328.

In this case, the first colored charged particles 322 are red or cyan, the second colored charged particles 324 are green or magenta, and the third colored charged particles 326. May be Blue or Yellow.

Meanwhile, the monoelectrophoretic dispersion 360 is filled in the mono subpixel 418 formed by the partition wall 330, and the white charged particles 362, the black charged particles 364, and the dielectric solvent 328 are filled in the mono subpixel 418. It includes.

In one embodiment, the dielectric solvent 328 included in the color electrophoretic dispersion 320 and the monoelectrophoretic dispersion 360 is preferably transparent to ensure reflective brightness. Examples thereof include water, alcohol solvents, ester solvents, ketone solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated solvents, and the like, and these materials may be used alone or as a mixture. The dielectric solvent 328 may further include a surfactant. The dielectric solvent 328 may be selected to have a low viscosity in terms of ensuring high mobility of each charged particle.

In addition, the black charged particles 364 may be, for example, a polymer or a colloid colored with a black dye such as aniline black or carbon black. The white charged particles 362 may be, for example, a polymer or colloid colored with a white dye such as titanium dioxide or antimony trioxide. If necessary, charge control agents, dispersants, lubricants and the like may be further added in addition to these dyes.

In addition, the colored charged particles 322, 324, 326 and the white charged particles 362 included in the color sub pixels 412, 414, and 416 may be charged with opposite polarities, and may be charged to the mono sub pixel 418. The included white charged particles 362 and the black charged particles 364 may also be charged with opposite polarities.

Hereinafter, a method of implementing color using an electrophoretic display device according to an exemplary embodiment of the present invention will be described with reference to FIG. 5.

First, when white is to be realized, as illustrated in FIG. 5A, the white charged particles 362 of the first to third color sub-pixels 412, 414, and 416 are driven to face the upper plate 310. White, and the white charged particles 362 of all the mono sub-pixels 418 are driven to move toward the upper plate 310.

Next, to implement black, as shown in FIG. 5B, the colored charged particles 322, 324, and 326 of the first to third color sub-pixels 412, 414, and 416 are driven to drive the colored charged particles 322, 324, and 326. Black is realized by moving in the direction of the upper plate 310 and driving the black charged particles 364 of all the mono sub-pixels 418 in the direction of the upper plate 310.

In order to implement a specific color, the colored charged particles filled in at least one of the first to third color sub pixels 412, 414, and 416 are driven, and the white charged particles 362 of all the mono sub pixels 418 are driven. ) And the black charged particles 364 may be driven to drive a specific color. In this case, by adjusting the positions of the white charged particles 362 and the black charged particles 364 of the mono sub pixel 418, a specific color may be implemented in 16 gray levels.

For example, when the red color is to be implemented, as shown in FIG. 5C, the colored charged particles 322 of the first color sub-pixel 412 including the red colored charged particles 322 are formed on the top plate ( Driving to move toward the direction 310, driving the white charged particles 362 to move toward the upper plate 310 for the remaining color sub-pixels 414 and 416, and white charged particles of all the mono sub-pixels 418. By appropriately adjusting the positions of the 362 and the black charged particles 364, various shades of red are realized. In this case, when the white charged particles 362 of the mono sub pixel 418 are driven to move in the direction of the upper plate 310, a bright red color is realized, and the black charged particles 364 are driven to move in the direction of the upper plate 310. Allow red color to be implemented.

As described above, when the white charged particles 362 of the three color subpixels 412, 414, and 416 and the three mono subpixels 418 are driven to realize white color, the reflectance becomes approximately 45% or more. When driving the colored charged particles 322, 324, 326 of the three color sub-pixels 412, 414, 416 and driving the black charged particles 364 of the three mono sub-pixels 418, a black color is realized. Since the reflectance is 7% or less, the present invention can provide a contrast ratio of 6: 1 or more.

Although not shown in FIGS. 2 to 4, the electrophoretic display device 150 according to the present invention is disposed on the partition wall 330 to prevent leakage of the color electrophoretic dispersion 320 and the monoelectrophoretic dispersion 360. The sealing unit may further include.

Hereinafter, a manufacturing process of an electrophoretic display device according to an exemplary embodiment of the present invention will be described.

6A through 6D are cross-sectional views illustrating a manufacturing process of an electrophoretic display device according to an exemplary embodiment of the present invention.

As shown in FIG. 6A, the lower array 200 including the pixel electrode 220 formed on the TFT substrate 211 is manufactured.

In this case, the lower array 200 may be manufactured according to the process illustrated in FIG. 7. Specifically, as shown in FIG. 7A, after depositing a metal film (not shown) on the substrate 211, the metal film is selectively patterned through a photolithography process and an etching process to form a gate line (not shown) and the A gate electrode 212a branched from the gate line is formed.

Subsequently, as shown in FIG. 7B, a gate insulating film 213 is formed on the substrate 211 including the gate line and the gate electrode 212a by using a nitride film SiNx, and is formed on the gate insulating film 213. After sequentially forming a semiconductor layer (not shown) and an impurity layer (not shown), the impurity layer and the semiconductor layer are selectively patterned by a photolithography process and an etching process to form a semiconductor layer 214 and an ohmic contact layer (not shown). Form a).

Subsequently, as illustrated in FIG. 7C, a metal material (not shown) for forming a data line is deposited on the substrate 211 including the semiconductor layer 214 and the ohmic contact layer, and then a photolithography process and an etching process are performed. Selective patterning is performed to form a data line (not shown), a source electrode 215a branched from the data line, and a drain electrode 216 spaced apart from the source electrode 215a.

Through this process, a TFT, which is a switching element composed of the source electrode 215a, the drain electrode 216, the active layer 214, and the gate electrode 212a, is formed.

Subsequently, as shown in FIG. 7D, a protective layer 217 is formed on the entire surface of the substrate 211 on which the TFT is formed, and the protective layer 217 is selectively patterned to expose a portion of the drain electrode 216. Forming a contact hole (H).

Subsequently, as shown in FIG. 7E, a metal material (not shown) made of a transparent conductive material such as ITO or IZO is deposited on the protective layer 217 including the contact hole H. The lower array 200 is manufactured by selectively patterning a material through a photolithography process and an etching process to form a pixel electrode 220 electrically connected to the drain electrode 216.

Referring to FIG. 6B again, the partition wall 330 is formed on the lower array 200.

In this case, the partition wall 330 may include a first partition wall for forming a plurality of pixels, a second partition wall for forming one or more color subpixels and one or more mono subpixels in the plurality of pixels, and a lower array 200. It includes a third partition wall formed in the outermost.

The partition wall 330 may be formed through a photolithography or a mold imprinting process.

In an embodiment, in order to improve contrast and black reflectivity of the electrophoretic display device, the partition wall 330 may be made of a material to which black dyes such as aniline black and carbon black are added. Optionally, these surfaces may be dyed with black dye after the partition wall 330 is formed.

Next, as shown in FIG. 6C, the color electrophoretic dispersion 320 is filled in the color subpixels 412, 414, and 416 formed by the partition wall 330, and monoelectrophoresis is performed on the mono subpixel (not shown). Fill the dispersion (not shown).

In one embodiment, the color electrophoretic dispersion 320 includes colored charged particles 322, 324, 326, white charged particles 362, and a dielectric solvent 328, wherein the monoelectrophoretic dispersion is white charged Particles (not shown), black charged particles (not shown), and dielectric solvents (not shown).

Specifically, the first color subpixel 412 is filled with a first color electrophoretic dispersion 320 including a first colored charged particle 322, a white charged particle 362, and a dielectric solvent 328. The two color subpixel 414 is filled with a second color electrophoretic dispersion 320 comprising a second colored charged particle 324, a white charged particle 362, and a dielectric solvent 328, and a third color subpixel. 416 is filled with a third color electrophoretic dispersion 320 comprising a third colored charged particle 326, a white charged particle 362, and a dielectric solvent 328.

On the other hand, when the color electrophoretic dispersion is filled in the color subpixels and the monoelectrophoretic dispersion is filled in the mono subpixels, each of the color electrophoretic dispersions and the monoelectrophoretic dispersions is 2 to prevent the electrophoretic dispersions from overflowing and mixing with each other. It can be filled over time.

Specifically, firstly, each of the three color sub-pixels is filled with a color electrophoretic dispersion including some of the colored charged particles, the white charged particles, and some of the dielectric solvent, and each of the three mono sub-pixels is charged with white charged particles and black charged particles. And a monoelectrophoretic dispersion comprising some of the dielectric solvent.

Secondly, each of the three color sub-pixels is filled with the remainder of the dielectric solvent, and each of the three mono sub-pixels is filled with the remainder of the dielectric solvent.

Next, as shown in FIG. 6D, the upper plate 310 manufactured by forming the common electrode 312 on the base film 311 is attached to the lower array 200. In this case, the upper plate 310 is attached in such a manner that the common electrode 212 faces the lower array 200. At this time, for adhesion, an adhesive layer (not shown) may be interposed between the common electrode 312 and the partition wall 330 of the upper plate 310.

In one embodiment, the base film 311 may be formed of, for example, polyethylene terephthalate (PET), the common electrode 312 may be formed of ITO or IZO, the top plate 310 is It can be attached via a roll lamination process.

Although not shown, a process of forming a sealing part (not shown) for preventing the leakage of the electrophoretic dispersion 320 on the electrophoretic dispersion 320 and the partition wall 330 may be further included. Specifically, the sealing part may be formed by applying a sealing agent on the electrophoretic dispersion 320 and the partition wall 330 and then performing a phase separation and a hardening process.

Those skilled in the art to which the present invention pertains will understand that the above-described present invention can be implemented in other specific forms without changing the technical spirit or essential features.

Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

150: electrophoretic display 200: lower array
220: pixel electrode 310: top plate
312: common electrode 330: partition wall
412, 414, 416: color sub pixel 418: mono sub pixel

Claims

A lower array including pixel electrodes;
An upper plate facing the lower array and including a common electrode;
A partition wall forming a plurality of pixels between the lower array and the upper plate and forming at least one color subpixel and at least one mono subpixel in each pixel;
A color electrophoretic dispersed solution filled in the one or more color sub-pixels and including colored charged particles, white charged particles, and a dielectric solvent; And
And a monoelectrophoretic dispersion liquid filled in the at least one mono sub-pixel and including white charged particles, black charged particles, and a dielectric solvent.

The method of claim 1, wherein the color sub-pixel,
A first color sub-pixel filled with a first color electrophoretic dispersion comprising first colored charged particles, white charged particles, and a dielectric solvent;
A second color sub-pixel filled with a second color electrophoretic dispersion comprising a second colored charged particle, a white charged particle, and a dielectric solvent; And
And a third color sub-pixel filled with a third color electrophoretic dispersion containing a third colored charged particle, a white charged particle, and a dielectric solvent.

The method of claim 1,
The color sub pixel includes first to third color sub pixels.
The first color sub-pixel includes colored charged particles of any one of red and cyan,
The second color sub-pixel includes colored charged particles of any one of green or magenta.
The third color sub-pixel is electrophoretic display device, characterized in that the colored charged particles of any one of blue (Blue) or yellow (Yellow).

The method of claim 1,
And the partition wall is formed in the upper plate direction in a region between the pixel electrodes.

The method of claim 1,
White charged particles of all color sub-pixels and white charged particles of all mono sub-pixels are driven to realize white.
Colored charged particles of all color sub-pixels and black charged particles of all mono sub-pixels are driven to realize black.
And at least one of colored charged particles filled in at least one of the color sub-pixels, and white charged particles and black charged particles of the mono sub-pixels to drive a gray scale of a specific color.

The method of claim 1,
The size of the color sub-pixel and the mono sub-pixel has a ratio of 2: 3 electrophoretic display device.

(a) fabricating a bottom array comprising a plurality of pixel electrodes;
(b) forming a partition on the lower array to form a plurality of pixels, a plurality of color sub pixels constituting each pixel, and a plurality of mono sub pixels;
(c) filling the color subpixels with colored charged particles, white charged particles, and a first dielectric solvent, and filling the mono subpixels with white charged particles, black charged particles, and a second dielectric solvent; And
(d) attaching an upper plate including a common electrode to the lower array.

The method of claim 7, wherein step (c)
(c1) filling the colored subpixels with colored charged particles, white charged particles, and a portion of the first dielectric solvent, and filling the mono subpixels with the white charged particles, black charged particles, and the second dielectric solvent. Filling in part; And
(c2) filling the remainder of the first dielectric solvent in the color sub-pixels and filling the remainder of the second dielectric solvent in the mono sub-pixels.

The method of claim 7, wherein
In the step (b), the barrier rib is formed using a photolithography or mold printing process.

The method of claim 7, wherein
In the step (d), the upper plate is attached by using a roll lamination process (Roll Lamination) manufacturing method of an electrophoretic display device.