Color display device

• US 8,964,282 B2
• Filed: 05/01/2013
• Issued: 02/24/2015
• Est. Priority Date: 10/02/2012
• Status: Active Grant

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: E Ink California, LLC (E Ink Holdings Incorporated)
• Inventors: Wang, Ming, Li, Yu, Du, Hui, Zhang, Xiaojia, Lin, Craig
• Primary Examiner(s): Ben, Loha
• Application Number:
  US13/875,145
• Publication Number:
  US 20140092466A1
• Time in Patent Office: 664 Days
• Field of Search: 359/228, 359/253, 359/296, 345/107, 345/212, 345/690, 204/450, 204/600
• US Class Current: 359/296
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1685 Operation of cells; Circuit arrangements affecting the entire cell
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type
• CPC Class Codes: G09G 2310/068 Application of pulses of alternating polarity prior to the drive pulse in electrophoretic displays
• CPC Class Codes: G09G 3/34 by control of light from an independent source
• CPC Class Codes: G09G 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167

Abstract

The present invention provides a solution for a highlight or multicolor display device, in which each display cell can display high quality color states. More specifically, an electrophoretic fluid is provided which comprises three types of pigment particles, having different levels of size, threshold voltage or charge intensity.

Claims

1. A driving method for an electrophoretic display comprising an electrophoretic fluid which is sandwiched between a common electrode and a layer of pixel electrodes, wherein the electrophoretic fluid comprises a first type of pigment particles, a second type of pigment particles and a third type of pigment particles, all of which are dispersed in a solvent or solvent mixture, wherein:

(a) the first type of pigment particles and the second type of pigment particles carry opposite charge polarities;

(b) the third type of pigment particles has the same charge polarity as the second type of pigment particles but has an intensity lower than that of the second type of pigment particles; and

(c) the second type of pigment particles has a threshold voltage,

the method comprises driving an area corresponding to a pixel electrode from a color state of the first type of pigment particles to a color state of the third type of pigment particles by applying a voltage potential difference which is the same as, or lower than, the threshold voltage of the second type of pigment particles.

2. The method of claim 1, wherein the first and second types of pigment particles are white and black, respectively.

3. The method or claim 1, wherein the third type of pigment particles is non-white and non-black.

4. The method of claim 3, wherein the third type of pigment particles is of a color selected from the group consisting red, green, blue, yellow, cyan and magenta.

5. The method of claim 1, wherein the third type of pigment particles has a charge level less than about 50% of the charge intensity of the first type or second type of pigment particles.

6. The method of claim 1, wherein the third type of pigment particles is larger than the first and the second types of pigment particles.

7. The method of claim 6, wherein the third type of pigment particles is about 2 to about 50 times larger than the first or second type of pigment particles.

8. The method of claim 1, further comprising applying a shaking waveform before the area corresponding to the pixel electrode is driven to the color state of the first type of pigment particles.

9. The method of claim 8, wherein the shaking waveform consists of a pair of opposite driving pulses being repeated for many cycles.

10. The method of claim 9, wherein each of the driving pulses is applied for not more than half of the time required for driving the area corresponding to the pixel electrode from a full black state to a full white state.

11. The method of claim 1, wherein when the color state of the third type of pigment particles is seen at a viewing side, the first and second types of pigment particles gather at the side opposite to the viewing side resulting in an intermediate color between colors of the first and second types of pigment particles.