Electrophoretic display with dual mode switching

• US 7,038,670 B2
• Filed: 02/14/2003
• Issued: 05/02/2006
• Est. Priority Date: 08/16/2002
• Status: Expired due to Fees

• Current Assignee: E Ink California, LLC (E Ink Corporation)
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Liang, Rong-Chang, Chung, Jerry
• Primary Examiner(s): Shankar, Vijay
• Assistant Examiner(s): DHARIA, PRABODH M
• Application Number:
  US10/367,098
• Publication Number:
  US 20040032389A1
• Time in Patent Office: 1,173 Days
• Field of Search: 345/107, 345/108, 345/84, 345/85, 345/111, 345/204, 345/105, 359/296, 359/298, 359/254, 359/265, 428/379, 428/323, 523/200, 523/374, 430/108.21, 313/582, 313/498, 349/86, 349/92, 349/117, 349/188, 106/31.64, 427/214, 364/4, 364/5, 364/7, 364/8, 204/600
• US Class Current: 345/204
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/16762 having three or more electrodes per pixel
• CPC Class Codes: G02F 1/1677 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 1/1681 having two or more microcells partitioned by walls, e.g. of microcup type
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• 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 relates to an improved EPD which comprises both the traditional up/down switching and the in-plane switching modes. The monochrome EPDs of the present invention are capable of displaying highlight color of choice which is different from the text. For example, white background, blue text, and red highlight can be shown in any selected areas of the display. Furthermore, the full color EPDs of the present invention are capable of displaying high contrast images of high color saturation. Both high quality black and white states are possible in the full color displays of the present invention. The EPDs of the present invention do not need complex circuitry design, and are compatible with low cost and high yield roll-to-roll manufacturing processes. The EPD cells of the present invention may have opaque partition walls, or a black matrix top surface of the partition walls or a combination thereof.

Claims

1. An electrophoretic display comprising an array of electrophoretic cells wherein each of said electrophoretic cells comprises

a) a top layer comprising a top electrode,

b) a bottom layer comprising a bottom electrode and at least one in-plane electrode,

c) opaque partition walls,

d) a cell background, and

e) an electrophoretic composition filled therein which electrophoretic composition comprises charged pigment particles of the same color and carrying the same charge polarity dispersed in a dyed dielectric solvent or solvent mixture,

whereby the charged pigment particles are capable of moving in a vertical or planar direction.

2. The electrophoretic display of claim 1 wherein said opaque partition walls are white.

3. The electrophoretic display of claim 1 wherein said opaque partition walls are gray.

4. The electrophoretic display of claim 1 wherein said opaque partition walls are formed from a composition comprising a UV curable material and a filler, dye or pigment.

5. The electrophoretic display of claim 4 wherein said filler is selected from the group consisting of silica, ZnO, TiO₂, BaSO₄, CaCO₃ and polymer particles.

6. The electrophoretic display of claim 4 wherein said filler is silica or polymer particles.

7. The electrophoretic display of claim 4 wherein said filler is in the amount of 1–

20% by weight of the composition.

8. The electrophoretic display of claim 7 wherein said filler is in the amount of 2–

10% by weight of the composition.

9. The electrophoretic display of claim 1 wherein said opaque partition walls are formed from a composition comprising a radiation curable material and a latent light scattering material.

10. The electrophoretic display of claim 9 wherein said latent light scattering material is a material that is compatible with the radiation curable material before curing but becomes incompatible after curing.

11. The electrophoretic display of claim 9 wherein said latent light scattering material is a thermally or photochemically triggered gas-releasing material.

12. The electrophoretic display of claim 11 wherein said thermally or photochemically triggered gas-releasing material is selected from the group consisting of CO₂ producing carboxylic acids, bicyclic lactones or heterocycles;

CO producing ketones or bicyclic adducts;

SO and SO₂ producing sulfones, sulfonyloxy compounds or heterocycles;

N₂ producing azoalkanes, azides, diazomethanes, N-nitroso compounds, diazo, triazo or tetraazo heterocycles;

COS producing xanthates and O₂ producing endoperoxides.

13. The electrophoretic display of claim 11 wherein said thermally or photochemically triggered gas-releasing material is a phenol, tropolone, pyridine, pyrazine, pyrrole or a halogenated derivative thereof.

14. The electrophoretic display of claim 1 wherein said opaque partition walls are colored.

15. The electrophoretic display of claim 1 wherein the inside surface of the partition walls of an electrophoretic cell is of the same color as that of the electrophoretic composition in said electrophoretic cell.

16. The electrophoretic display of claim 15 wherein the two sides of a partition wall are of different colors.

17. The electrophoretic display of claim 1 wherein each of said electrophoretic cells displays the color of the charged pigment particles, the color of the dielectric solvent or solvent mixture, or the color of the cell background.

18. The electrophoretic display of claim 1 wherein each of said electrophoretic cells is sealed with a sealing layer formed from a sealing composition having a specific gravity lower than that of the electrophoretic composition.

19. The electrophoretic display of claim 1 wherein each of said electrophoretic cells is sealed with a sealing layer which is hardened in situ.