# US 8,570,640 B2 · Electrophoretic display device and method of fabrication thereof

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- Number: US 8,570,640 B2
- Document ID: US8570640B2
- Status: Granted
- Kind: B2
- Application number: 13/221,047
- Filed: 2011-08-30
- Published: 2012-03-01
- Granted: 2013-10-29
- Earliest claimed: 2010-09-01
- Assignees: LG Display Co., Ltd.
- Applicants: Yu-Sok Lim; Young-Jun Yu
- Inventors: Yu-Sok Lim; Young-Jun Yu
- Web page: https://patentgrep.com/patent/US8570640B2

## CPC

- G02F 1/167: by electrophoresis
- G02F 1/1679: Gaskets; Spacers; Sealing of cells; Filling or closing of cells
- G02F 1/1681: having two or more microcells partitioned by walls, e.g. of microcup type
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

Disclosed herein is a method of fabricating an electrophoretic display device for reducing the fabrication cost and simplifying the fabrication process, and the method may include providing a substrate comprising a display region arranged with a plurality of pixels and a non-display region; forming a thin-film transistor on a first substrate; forming a passivation layer on the substrate formed with the thin-film transistor; forming a pixel electrode in the display region on the passivation layer and forming a partition wall in the non-display region; filling an electrophoretic material in a pixel inside the partition wall on the passivation layer; applying a sealing material to an upper portion of the electrophoretic material to form a sealing layer; depositing a transparent conductive material on the sealing layer to form a common electrode; and adhering the protection layer to an upper portion of the common electrode.

## Claims

### Claim 1

A method of fabricating an electrophoretic display device, the method comprising:
providing a substrate including a display region comprising a plurality of pixels and a non-display region at the outside of the display region;
forming a thin-film transistor at each pixel on the substrate;
forming a passivation layer on the substrate to cover the thin-film transistor;
forming a pixel electrode for each pixel and a partition wall between pixels on the passivation layer;
forming an electrophoretic layer in a pixel between partition walls on the passivation layer;
forming a sealing layer at least on an upper portion of the electrophoretic layer;
directly coating a transparent conductive material on the sealing layer to form a common electrode;
directly coating a transparent adhesive agent on an upper surface of the common electrode; and
attaching a protection film to the upper surface of the common electrode by the transparent adhesive agent.

### Claim 2 (depends on 1)

The method of claim 1, wherein the forming the sealing layer forms the sealing layer on an upper portion of the electrophoretic layer and a top surface of the partition walls.

### Claim 3 (depends on 1)

The method of claim 1, further comprising forming an interlayer between the electrophoretic layer and the sealing layer.

### Claim 4 (depends on 3)

The method of claim 3, wherein the interlayer includes Methyl Ethyl Ketone.

### Claim 5 (depends on 1)

The method of claim 1, wherein the forming a pixel electrode and a partition wall comprises:
forming a pixel electrode at each pixel on the passivation layer; and
forming a partition wall between pixels on the passivation layer.

### Claim 6 (depends on 1)

The method of claim 1, wherein the forming a pixel electrode and a partition wall comprises:
forming a partition wall between pixels on the passivation layer; and
forming a pixel electrode at each pixel on the passivation layer.

### Claim 7 (depends on 6)

The method of claim 6, wherein the pixel electrode is further formed on a side surface of the partition wall.

### Claim 8 (depends on 6, 7)

The method of claim 6 or 7, wherein the forming a partition wall comprises:
forming an insulation layer on the passivation layer; and
removing part of the insulation layer corresponding to the pixel using any one of a photolithography process, a mold process, and an imprint process.

### Claim 9 (depends on 1)

The method of claim 1, wherein the electrophoretic material comprises charged white particles and charged black particles.

### Claim 10 (depends on 9)

The method of claim 9, wherein the electrophoretic material further comprises a dispersive medium.

### Claim 11 (depends on 10)

The method of claim 10, wherein the dispersive medium is emulsion polymer or air.

### Claim 12 (depends on 10)

The method of claim 10, wherein the dispersive medium is non-polarized organic medium.

### Claim 13 (depends on 1)

The method of claim 1, wherein the electrophoretic material comprises charged color particles.

### Claim 14 (depends on 1)

The method of claim 1, wherein the forming an electrophoretic layer comprises filling an electrophoretic material between the partition walls using any one of a dropping method, a squeeze method, a casting printing method, a bar-coating printing method, a screen printing method, and a mold printing method.

### Claim 15 (depends on 1)

The method of claim 1, wherein the forming a sealing layer comprises:
applying a sealing material to an upper portion of the electrophoretic layer; and
curing the sealing material.

### Claim 16 (depends on 15)

The method of claim 15, wherein the sealing material is formed of at least one material selected from a group consisting of an acrylic transparent organic resin, an overcoat transparent organic material, and a hybrid transparent organic material.

### Claim 17 (depends on 15)

The method of claim 15, wherein the curing the sealing material comprises irradiating ultraviolet rays on the sealing material.

### Claim 18 (depends on 15)

The method of claim 15, wherein the curing a sealing material comprises applying heat of less than 80° C. to the sealing material.

### Claim 19 (depends on 1)

The method of claim 1, wherein the sealing layer is formed with a thickness of 10 μm or less.

### Claim 20 (depends on 1)

The method of claim 1, wherein the common electrode is comprises a soluble transparent conductive material.

### Claim 21 (depends on 20)

The method of claim 20, wherein the soluble transparent conductive material comprises indium gallium zinc oxide (IGZO) and zinc oxide (ZnO).

### Claim 22 (depends on 1)

The method of claim 1, wherein the common electrode comprises indium tin oxide (ITO) and indium zinc oxide (IZO).

### Claim 23 (depends on 22)

The method of claim 22, wherein the ITO and IZO are deposited by a sputtering method in a room temperature.

### Claim 24 (depends on 1)

The method of claim 1, wherein the common electrode comprises tin oxide (SnO).

### Claim 25 (depends on 24)

The method of claim 24, wherein the SnO is deposited by a chemical vapor deposition (CVD) method.

### Claim 26 (depends on 1)

The method of claim 1, wherein the common electrode comprises carbon nanotubes.

### Claim 27 (depends on 1)

The method of claim 1, wherein the protection film comprises material selected from a group consisting of: a polystyrene (PS) film, a polyethylene (PE) film, a polyethylene naphthalate (PEN) film, and a polyimide (PI) film.

### Claim 28

An electrophoretic display device, the device comprising:
a substrate including a display region comprising a plurality of pixels and a non-display region at the outside of the display region;
a thin-film transistor at each pixel on the substrate;
a passivation layer on the substrate to cover the thin-film transistor;
a partition wall on the passivation layer in the display region to define a pixel;
a pixel electrode at each pixel on the passivation layer and a side surface of the partition wall;
an electrophoretic layer between the partition walls within a pixel;
a sealing layer at least on an upper portion of the electrophoretic layer;
a common electrode on the sealing layer; and
a protection layer formed on the common electrode.

### Claim 29 (depends on 28)

The device of claim 28, wherein the electrophoretic material comprises charged white particles and charged black particles.

### Claim 30 (depends on 28)

The device of claim 28, wherein the electrophoretic material comprises charged color particles.

### Claim 31 (depends on 29, 30)

The device of claim 29 or 30, wherein the electrophoretic material further comprises a dispersive medium.

### Claim 32 (depends on 28)

The device of claim 28, wherein the sealing layer comprises at least one material selected from a group consisting of: an acrylic transparent organic resin, an overcoat transparent organic material, and a hybrid transparent organic material.

### Claim 33 (depends on 28)

The device of claim 28, wherein the common electrode comprises material selected from a group consisting of: indium gallium zinc oxide (IGZO), zinc oxide (ZnO), indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO), and carbon nanotube.

### Claim 34 (depends on 28)

The device of claim 28, wherein the protection film comprises material selected from a group consisting of: a polystyrene (PS) film, a polyethylene (PE) film, a polyethylene naphthalate (PEN) film, and a polyimide (PI) film.

### Claim 35 (depends on 28)

The device of claim 28, further comprising an interlayer between the electrophoretic layer and the sealing layer.

### Claim 36 (depends on 35)

The device of claim 35, wherein the interlayer includes Methyl Ethyl Ketone.