# US 2014/0192400 A1 · Fine pixel pitch electrophoretic display

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- Number: US 2014/0192400 A1
- Document ID: US20140192400A1
- Status: Published application
- Kind: A1
- Application number: 13/736,485
- Filed: 2013-01-08
- Published: 2014-07-10
- Earliest claimed: 2013-01-08
- Assignees: Invent Research LLC
- Applicants: Invent Research LLC
- Inventors: Akihiro MOCHIZUKI; Madis-Marius VAHTRE; Laura PAIT
- Web page: https://patentgrep.com/patent/US20140192400A1

## CPC

- G02F 1/167: by electrophoresis
- G02F 1/0102: {Constructional details, not otherwise provided for in this subclass}
- G02F 1/172: {based on a suspension of orientable dipolar particles, e.g. suspended particles displays}
- G02F 1/0027: {Ferro-electric materials}
- 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

High display duty ratio and fast optical response electrophoretic display technology is presented by using an anti-ferroelectric coupling torque. The invention also consequently enables fine pixel pitch resolution by introducing photo lithography based switching element preparation method. Newly introduced casting film method for optical switching element preparation enables extremely fine size of switching element based on current well-established flat panel display volume manufacturing process.

## Claims

### Claim 1

An electrophoretic display comprising:
a top substrate;
a bottom substrate; and
a display medium comprising anti-ferroelectric particles and disposed between the top and bottom substrates.

### Claim 2 (depends on 1)

The electrophoretic display of claim 1, further comprising electrodes that are configured to apply to the display medium a first voltage to induce spontaneous polarization in the anti-ferroelectric particles.

### Claim 3 (depends on 2)

The electrophoretic display of claim 2, wherein the electrodes are configured to apply to the display medium a second voltage that is lower than the first voltage to cancel the spontaneous polarization and to drive the anti-ferroelectric particles at a high frequency.

### Claim 4 (depends on 1)

The electrophoretic display of claim 1, wherein the bottom substrate includes a TFT array and a color filter array.

### Claim 5 (depends on 1)

The electrophoretic display of claim 1, wherein the display medium comprises a photolithographic polymer.

### Claim 6 (depends on 1)

The electrophoretic display of claim 1, wherein the display medium comprises a fluid supporting the anti-ferroelectric particles.

### Claim 7

An electrophoretic display comprising:
a top substrate;
a bottom substrate; and
a cast and patterned photolithographic polymer film that is disposed between the top and bottom substrates and comprises ferroelectric or anti-ferroelectric particles.

### Claim 8 (depends on 7)

The electrophoretic display of claim 7, wherein different color materials are applied to top and bottom surfaces of the polymer film.

### Claim 9 (depends on 8)

The electrophoretic display of claim 8, wherein the different color materials are applied to the top and bottom surfaces of the polymer film by flexo printing.

### Claim 10 (depends on 7)

The electrophoretic display of claim 7, further comprising a TFT array and a color filter array.

### Claim 11

A method of preparing an electrophoretic display, comprising:
mixing ferroelectric or anti-ferroelectric particles with a photolithographic polymer;
casting the photolithographic polymer mixed with the particles to form a cast photolithographic polymer layer;
placing the cast polymer layer on a first substrate comprising electrodes;
performing a photolithographic pattering on the cast polymer layer; and
placing a second substrate on the first substrate so that the patterned cast polymer layer is disposed between the first and second substrates.

### Claim 12 (depends on 11)

The method of claim 11, further comprising printing a color material on a top or bottom surface of the cast polymer layer;

### Claim 13 (depends on 12)

The method of claim 12, wherein the color material is printed by flexo printing.

### Claim 14 (depends on 11)

The method of claim 11, further comprising filling a space between the first and second substrates with a thixotropic fluid.

### Claim 15 (depends on 11)

The method of claim 11, wherein the photolithographic pattering comprises using the electrodes on the first substrate as a photo mask to form self-aligned pattern of the cast polymer layer.

### Claim 16

A method of preparing an electrophoretic display, comprising:
micro-milling an oxide to form ferroelectric or anti-ferroelectric particles;
mixing the ferroelectric or anti-ferroelectric particles with a fluid;
preparing a cell comprising a first substrate and a second substrate; and
inserting the fluid mixed with the particles into the cell.

### Claim 17 (depends on 16)

The method of claim 16, wherein the micro-milling of the oxide comprises forming a polymer layer including the oxide and micro-milling the polymer layer.

### Claim 18 (depends on 16)

The method of claim 16, wherein the micro-milling of the oxide comprises drilling the oxide.

### Claim 19 (depends on 16)

The method of claim 16, wherein the micro-milling of the oxide comprises ball-milling the oxide.