KR101101518B1 - Electrophoretic display device and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an electrophoretic display device and a method of manufacturing the same, wherein the electrophoretic display device includes a first substrate having a first electrode made of a transparent material and made of a light transmissive material; A second substrate disposed at a position opposite to the first substrate and having a second electrode formed thereon; A partition wall disposed between the first substrate and the second substrate to divide a space between the first substrate and the second substrate to provide a plurality of cell spaces; And two or more display units disposed in the cell space and exhibiting different colors. The electrophoretic display device according to the present invention has a uniform spacing and a shape of the display unit injected into the cell space, so that image stability and uniformity are excellent, and light efficiency is excellent.

Electrophoretic display, display unit, microcapsules, colored particles, rotating body, bulkhead

Description

Electrophoretic display device and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophoretic display device and a manufacturing method thereof, and more particularly, to an electrophoretic display device having excellent image stability and uniformity and excellent light efficiency and a method of manufacturing the same.

In response to today's information society, which requires a new paradigm, a major transformation is required in the way information is delivered and shared. In order to meet this, as the flexible display, the development of the technology of electronic paper, which has a bendable advantage, is being accelerated, and the development of the electronic paper technology is entering the commercial development stage.

Electronic paper is cheaper to produce than conventional flat display panels, and can be driven with very little energy because it does not require background lighting or continuous recharging like a normal screen. In addition, the electronic paper is very sharp, has a wide viewing angle, and has a memory function that does not completely disappear even in the absence of power. These great advantages make electronic papers suitable for a wide range of applications, including e-books with paper-like sides and moving illustrations, self-renewable newspapers, reusable paper displays for mobile phones, disposable TV screens and electronic wallpaper. It has a huge potential market.

Technical approaches for electronic paper implementation include liquid crystal method, organic EL, reflective film reflective display, electrophoresis, electrochromic method, and mechanical reflective light.

Electrophoretic phenomena can be divided into dry and wet methods.

The dry electronic paper display device charges a collision due to enclosing two kinds of particles having different colors and charging characteristics between transparent substrates having electrodes formed on one surface thereof, and applying voltage to the electrodes of the upper and lower plates, thereby causing the particles to strike each other. The charged particles are formed.

An image is displayed by moving an particle by giving an electric field to a particle group charged from electrodes of upper and lower plates having different electric potentials. At this time, the electronic paper display includes one or more pixels separated from each other by the partition wall.

In such a dry electronic paper display device manufacturing method, the process of injecting particles into the pixel is very important for the stability and uniformity of the image. To this end, the ratio of the absolute amount to which the particles are injected and the relative amount of the particles must be uniform for each pixel.

That is, in the case of injecting particles having different types of black and white, the absolute amount of particles to be injected into the pixel should be uniform for each pixel, and the ratio of the relative amounts of the black and white particles to be injected into the pixel should be uniform for each pixel.

The spray coating method is the most common method of particle injection, in which particles are sprayed in a particle applicator and injected into a cell. Since the spray method is injected at random rather than opposed to a specific cell, the distance between the spray nozzle of the particle spreader and the partition wall of the lower substrate is spaced apart by several tens of centimeters.

In particular, as shown in FIG. 1, the charged particles sprayed from the nozzle may be laminated on the barrier rib upper surface, in which case there is a problem in that adhesion failure occurs when the barrier rib upper surface and the upper substrate are bonded. In order to solve this problem, a separate process is required to remove the particles located above the bulkhead.

Arrangement of particles displaying an image is an important factor determining stability and uniformity of an image, and various studies have been conducted on this.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide an electrophoretic display device having excellent image stability and uniformity and excellent light efficiency and a method of manufacturing the same.

In order to solve the above problems, an aspect of the present invention has a first electrode of a transparent material, a first substrate made of a light transmissive material; A second substrate disposed at a position opposite to the first substrate and having a second electrode formed thereon; A plurality of partition walls disposed between the first substrate and the second substrate to divide the space between the first substrate and the second substrate to provide a plurality of cell spaces; And two or more display units disposed in the cell space and displaying different colors.

The display unit may be of three types representing red, green, and blue, respectively.

The display units may be of three types representing green, purple and yellow, respectively.

The display units may be of two kinds each representing a color having a complementary color relationship.

The display unit may be spherical, oval or cylindrical.

The display unit may be a microcapsule encapsulated with a fluid liquid in which charged color particles are dispersed.

The microcapsule may include black particles having different charging characteristics from charged color particles.

The display unit may be a rotating body having two display areas colored in different colors and exhibiting different charging characteristics.

The two display areas may include a first display area colored with one color selected from the group consisting of red, green, and blue, and a second display area colored with white.

The plurality of barrier ribs may be made of one material selected from the group consisting of polycarbonate, polyethylene terephthalate, polyether sulfone, and polyimide.

Another aspect of the invention includes forming a plurality of partitions to divide a space on a first substrate to provide a cell space; Arranging at least two display units representing different colors in the cell space; And attaching a second substrate to the cell space and the upper portion of the display unit such that the second substrate is disposed to face the first substrate.

Forming a plurality of partitions on the first substrate may include forming a resin layer on the first substrate; And it may include the step of pressing with a stamp in which the embossed and intaglio patterns are formed on the resin layer.

The disposing two or more display units in the cell space may be performed by injecting a display unit into the open cell space by closing a part of the cell space and opening a part of the cell space.

Placing two or more display units in the cell space may include injecting one display unit of the same color into an open cell space by closing a portion of the cell space and opening a portion of the cell space; And closing a cell into which the one display unit is injected, and partially opening the cell to which the one display unit is injected to inject another kind of display unit having a different color from the one display unit into the open cell space. .

The closing and opening of the cell space may use a filter having a plurality of pores corresponding to the cell space.

In the electrophoretic display device according to the present invention, two display units having different colors are arranged in a cell space formed by a partition wall. Accordingly, the spacing and shape of the display unit injected into the cell space are uniform for each cell, thereby providing excellent image quality by removing spots and spots on the screen. In addition, since the spacing between the cells is constant, the electrophoretic display device realizing an optimized response speed can be realized by minimizing the distribution of driving voltage between the cells and the electric field gradient in the cells.

In addition, since the binder layer for fixing the display unit is not used or minimized, unnecessary voltage drop and parasitic capacitance can be reduced.

A large portion of the display unit is shielded by a binder or partially consumed light to solve the problem of relatively low light efficiency.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

2 is a cross-sectional view illustrating an electrophoretic display device according to an exemplary embodiment of the present invention. Referring to FIG. 2, the electrophoretic display according to the present embodiment includes a first substrate 20 having a first electrode made of a transparent material and made of a light transmissive material; A second substrate 10 disposed at a position opposite to the first substrate and having a second electrode formed thereon; A partition wall 30 disposed between the first substrate 20 and the second substrate 10 to divide a space between the first substrate 20 and the second substrate 10 to provide a plurality of cell spaces; And two or more display units 40 disposed in the cell space and representing different colors.

The first substrate 20 has a first electrode (not shown) of a transparent material, is made of a light transmissive material, the second substrate 10 is disposed at a position opposite to the first substrate, and the second electrode is formed. do. The first substrate 20 and the second substrate 10 is preferably made of a flexible material of the glass substrate or flexible plastic type.

In addition, a voltage is applied to the display unit 40 by electrodes (not shown) included in the first substrate 20 and the second substrate 10. Although not shown separately, the electrode may be provided with adjusting means for adjusting the magnitude and direction of the voltage applied to the display unit.

The electrode is formed of a conductive material, and may be an electrode material commonly used in the art, and may include, for example, a conductive polymer such as polythiopine or polyaniline, or metal particles such as silver or nickel. Printed conductors such as polymer films, printed conductors such as graphite or conductive carbon materials, or polymer films containing conductive oxides such as indium tin oxide, and the like. Preferably, indium tin oxide (ITO: Indium-Tin-Oxide) is used as the transparent electrode.

The partition wall 30 is disposed between the first substrate 20 and the second substrate 10 to divide the space between the first substrate 20 and the second substrate 10 to provide a plurality of cell spaces. In the present invention, the space between the partition walls is defined as a cell space.

Two or more display units 40 having different colors are disposed in the cell space. In the present embodiment, three cell spaces in which three display units 41, 42, and 43 representing red (R), green (G), and blue (B) are arranged form one pixel. The reflected red, green, and blue light are mixed to display one color.

The type of display unit showing different colors is not particularly limited. The type of display unit representing different colors may be determined according to the color to be implemented. Although not shown, three cells in which three display units each representing cyan, magenta, and yellow are disposed may be implemented in the form of one pixel.

In addition, the number of cells constituting one pixel is not limited. For example, two cells in which two display units representing colors having complementary colors are arranged may be implemented in the form of one pixel.

In one embodiment of the present invention, the display unit 40 may be a microcapsule filled with a flowable liquid in which charged color particles are dispersed.

3 is an enlarged cross-sectional view of the microcapsule 40a. Referring to FIG. 3, in the microcapsule 40a, a fluid liquid 40a-4 in which charged color particles 40a-2, which are moved by electrophoresis, is dispersed is encapsulated by the capsule outer wall 40a-1. . In addition, the charged color particles 40a-2 and black particles 40a-3 having different charging characteristics are dispersed together in the flowable liquid 40a-4. In the present invention, "color" means all colors having saturation except black and white.

The color of the microcapsules 40a is realized by the color particles 40a-2 contained therein. The color particles 40a-2 may be red, green, and blue, respectively, whereby the color represented by the microcapsules is determined.

When voltage is applied to the microcapsules by electrodes (not shown) included in the first substrate 20 and the second substrate 10, the charged color particles 40a-2 are emergency or descending, and thus emergency The light of the color of the color particles is reflected to display the color. In other words, if all of the red, green, and blue color particles fly, white color is expressed by additive mixing. If only red or green color particles fly, red or green color is expressed, respectively. In an emergency, black is expressed. In addition, various colors may be expressed according to the magnitude of the applied voltage.

As the color particles, those known in the art may be used, and for example, pigments, polymers, lake pigmented pigments, inorganic materials, and the like may be used. In addition, the black particles are not limited thereto, but are preferably carbon black.

The shape of the microcapsules 40a is not particularly limited and may be, for example, spherical, elliptical or cylindrical.

In general, the height of the partition wall 30 is formed higher than the particle diameter of the microcapsules 40a. However, the microcapsules 40a may be pressed down over time according to the flowable liquid 40a-4 and the capsule outer wall 40a-1 included therein. In this case, the width of the cell space may be larger than the particle diameter of the microcapsule 40a.

In addition, the height of the partition wall formed at the outermost part may be greater than the height of the adjacent partition wall, and the height of the partition wall positioned inside may be smaller than the particle diameter of the microcapsule 40a. Accordingly, a partition formed on the upper substrate and the outermost part may be attached to implement an electrophoretic display device having a large area. This is because the area of the electrophoretic display device is implemented according to the highest partition and the first substrate attached thereto.

In addition, in another embodiment of the present invention, the display unit 40 may be a rotating body (twist ball) having two display areas colored in different colors and exhibiting different charging characteristics.

4 is an enlarged cross-sectional view of the rotating body 40b. Referring to FIG. 4, the rotating body 40b is colored in different colors and has two display regions 40b-1 and 40b-2 showing different charging characteristics. The two display regions may be divided into a first display region 40b-1 colored with a color representing a color and a second display region 40b-2 colored with white. When -1) is positively charged, the second display area 40b-2 is negatively charged, and the rotor (not shown) included in the first substrate 20 and the second substrate 10 is rotated. When voltage is applied to 40b), the rotating body 40b rotates according to the magnitude and direction of the voltage, and colors are displayed by colored colors in two display areas.

The first display area 40b-1 may be colored with one color selected from the group consisting of red, green, and blue, whereby the color represented by the rotating body 40b may be determined. In addition, various colors may be expressed according to the magnitude of the applied voltage.

As a method of forming the first and second display areas by electrically and optically treating the rotating body 40b having two display areas, methods known in the art may be used. For example, a method of applying a centrifugal force to the rotating body after putting the rotating body into the rotating disk having two coloring liquids can be used.

The shape of the rotating body is not particularly limited and may be, for example, spherical, elliptical or cylindrical.

5 shows a cylinder-shaped rotating body 40c. The rotating body 40c has two display regions 40c-1 and 40c-2, which are colored in different colors and exhibit different charging characteristics.

The surface of the rotor may be coated with a fluid to facilitate rotation.

For structural stability, the height of the partition wall 30 is preferably larger than the diameter of the rotating body. In addition, the cell space may include an electrically insulating transparent material so that the rotating body can easily rotate.

The material of the partition wall 30 is not particularly limited as long as it is a flexible material. For example, acrylic, epoxy, urethane, or polyester may be used. More specifically, polycarbonate (PC), polyethylene terephthalate (PET), polyether sulfone (PES), polyimide, or the like may be used.

The electrophoretic display device according to the present invention arranges two display units having different colors in the cell space formed by the partition wall. Accordingly, the spacing and shape of the display unit injected into the cell space may be uniform for each cell, thereby improving image quality by removing spots and spots on the screen.

In addition, since the binder layer for fixing the microcapsule, which is the display unit, may be omitted or minimized, unnecessary voltage drop and parasitic capacitance may be reduced.

Hereinafter, a manufacturing process of an electrophoretic display device according to an exemplary embodiment of the present invention will be described. 6 to 8 are cross-sectional views illustrating a manufacturing process of an electrophoretic display device according to an exemplary embodiment of the present invention.

A manufacturing process of an electrophoretic display device may include forming a plurality of partitions to divide a space on a first substrate to provide a cell space; Disposing a display unit in the cell space; And attaching a second substrate over the cell space and the display unit so as to face the first substrate.

First, a method of forming a plurality of partitions 30 on the first substrate 10 will be described. The first substrate 20 and the second substrate 10 of the electrophoretic display shown in FIG. 2 are the second substrate 20 and the first substrate 10, respectively, in FIGS. 6 to 8 for explaining a manufacturing process. Is indicated.

6 and 7 are cross-sectional views illustrating a method of forming a plurality of partition walls according to an embodiment of the present invention. As shown in FIG. 6, after the resin layer 30a is formed on the first substrate 10, the resin layer 30a may be compressed and formed using a stamp 50 having embossed and intaglio patterns. In this case, a pattern corresponding to the pattern of the stamp 50 is formed in the resin layer 30a. That is, as shown in FIG. 6, the resin layer 30a corresponding to the embossed pattern of the stamp 50 is compressed, and the resin layer 30a corresponding to the engraved pattern of the stamp 50 has a plurality of partitions 30. ), Thereby forming a cell space between the partition walls 30.

FIG. 7A illustrates a cross-sectional view of the first substrate 10 on which the partition wall 30 is formed, and FIG. 5B illustrates a top plan view of the first substrate 10 on which the partition wall is formed. As shown in Figs. 7A and 7B, a rectangular cell is formed in this embodiment.

The height of the partition 30 may be higher than the particle diameter of the display unit 40.

The width of the cell space may be greater than the particle diameter of the display unit 40 disposed in the cell, the height of the partition wall located at the outermost portion is greater than the height of the adjacent partition wall, the height of the partition wall located inside the display unit It may be formed smaller than the particle size of.

In this case, the stamp 50 may be subjected to self-assembled monolayer (SAM) coating. When the SAM 50 is coated on the stamp 50, when the stamp 50 is pressed onto the resin layer 30a, the stamp 50 and the resin layer 30a that are pressed together may be easily separated from each other.

The resin layer 30a is not particularly limited as long as it is a flexible material as described above. For example, acrylic, epoxy, urethane, or polyester may be used. More specifically, polycarbonate (PC), polyethylene terephthalate (PET), polyether sulfone (PES), polyimide, or the like can be used.

On the other hand, when the thermosetting epoxy material is used as the resin layer 30a, in order to be able to form the partition 30 more efficiently, the imprinting process can be dualized.

That is, the stamp 50 and the resin layer 30a are thermally compressed for 30 minutes within a temperature range where the viscosity of the resin layer 30a becomes the lowest (for example, about 100 ° C.), and then maintained in a compressed state. After curing the resin layer 30a by raising the temperature to a temperature range (for example, about 180 ° C.) where the resin layer 30a can be cured, a method of separating the stamp 50 and the resin layer 30a is described. It is available.

By using this method, the pattern formed on the stamp 50 can be transferred to the resin layer 30a more efficiently, and the shape of the pattern transferred to the resin layer 30a at the time of separation or after separation, that is, the partition wall, can be efficiently transferred. Can be maintained.

As described above, since the partition wall is manufactured by the imprinting process, various cell shapes and sizes can be adjusted. 7C shows a top plan view when a hexagonal cell is formed.

In addition, in the case of injecting the microcapsules into the cell, the shape of the capsule can be changed according to the frame inside the cell as time passes, and ultimately the shape of the capsule can be adjusted.

Although not shown, a method of forming a partition wall providing a cell space is not particularly limited as long as it is a method of forming a pattern. For example, laser patterning, lithography, or a sand blast method using a photosensitive resin may be used. .

Next, a method of arranging two or more types of display units 40 in the cell space formed on the first substrate 10 will be described.

8A to 8E are cross-sectional views illustrating a method of arranging the display unit 40 according to an embodiment of the present invention. As shown in FIGS. 8A to 8C, part of the cell space may be closed and part of the cell space may be opened to inject the display unit 40 into the open cell space.

More specifically, the filter 60 having a plurality of pores corresponding to the cell space may be positioned on the first substrate 10, and the display unit 40 may be injected into the open cell space through the filter 60. have.

For example, a method of injecting three types of display units 40 representing red, green, and blue will be described. First, as shown in FIG. 8A, the filter 60 is disposed on the first substrate 10 on which the plurality of partition walls 30 are formed. At this time, some of the pores of the filter are closed, some are open, and the open voids and the display unit 41 showing red color are arranged to coincide with the cell space to be injected. Thereafter, the red display unit 41 is deposited on the filter 60. As shown in the drawing, a plurality of display units are stacked at random. Thereafter, the swaying motion to the left and right on the first substrate 10, the red display unit 41 is injected into the cell space through the air gap of the filter.

Next, as shown in FIG. 8B, the filter 60 is disposed on the first substrate 10 such that the open void of the filter coincides with the cell space into which the display unit 42 showing green is to be injected. Subsequently, as described above, the green display unit 42 is deposited on the filter 60, and the movement of the left and right sides is applied on the first substrate 10 so that the green display unit 42 is injected into the cell space. .

Next, as shown in FIG. 8C, the filter 60 is disposed on the first substrate 10 such that the open void of the filter coincides with the cell space into which the display unit 43 showing blue is injected. Thereafter, the capsule 43 showing blue is injected into the cell space in the same manner.

FIG. 8D is a cross-sectional view showing a first substrate on which a display unit showing red, green, and blue is disposed in the cell space after the filter is removed, and FIG. 8E is a red, green, and blue color in the cell space after the filter is removed. It is an upper plan view which shows the 1st board | substrate with which the display unit shown is arrange | positioned.

Next, the second substrate 20 is attached to the cell space and the upper portion of the display unit 40 so as to face the first substrate 10. As a result, as shown in FIG. 2, an electrophoretic display device is manufactured.

The display unit 40 may be a microcapsule or a rotating body, and details thereof are as described above.

In the method of manufacturing an electrophoretic display device according to the present invention, since the display unit may be arranged on a plane by the partition wall, the use of the binder may be minimized or the binder may not be used. Accordingly, unnecessary voltage drop and parasitic capacitance can be prevented. In addition, since a large portion of the display unit is shielded or partially consumed by the binder can solve the problem of relatively low light efficiency.

In addition, since the cell into which the display unit is injected is manufactured by using an imprint method, the gap between the cells can be partitioned in advance. Accordingly, the distance between the display units can be adjusted, and the amount of display units injected can be made uniform.

In addition, since the spacing between the cells is constant, the electrophoretic display device implementing the optimized response speed may be realized by minimizing the distribution of the driving voltage between the cells and the electric field gradient in the cells.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

1 is a cross-sectional view showing a spray particle applying method according to the prior art.

2 is a cross-sectional view schematically illustrating an electrophoretic display device according to an exemplary embodiment of the present invention.

3 is an enlarged cross-sectional view of a display unit according to an exemplary embodiment of the present invention.

4 is an enlarged cross-sectional view of a display unit according to another embodiment of the present invention.

5 is an enlarged cross-sectional view of a display unit according to still another embodiment of the present invention.

6 to 8 are cross-sectional views illustrating a manufacturing process of an electrophoretic display device according to an exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: second substrate (or first substrate) 20: first substrate (or second substrate)

30: partition 40, 41, 42, 43: display unit

50: stamp 60: filter

Claims (15)

delete delete delete delete delete delete delete delete delete delete Forming a plurality of partitions to divide the space on the first substrate to provide cell space; Arranging at least two display units in which part of the cell space is closed and part is open to display different colors in the cell space using a filter having a plurality of voids corresponding to the cell space; And And attaching a second substrate on the cell space and the display unit so as to face the first substrate. The method of claim 11, Forming a plurality of partitions on the first substrate Forming a resin layer on the first substrate; And And compressing the stamp with a stamp having embossed and engraved patterns formed on the resin layer. delete The method of claim 11, Arranging two or more display units in the cell space Injecting one kind of display unit displaying the same color into the open cell space by closing a part of the cell space and opening a part of the cell space; And And closing a cell into which the one display unit is injected and opening a part of the display unit to inject another kind of display unit having a color different from that of the one display unit into the open cell space. Method of manufacturing an electrophoretic display device. delete

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