Reflective electrophoretic display with laterally adjacent color cells using a reflective panel

• US 6,271,823 B1
• Filed: 09/16/1998
• Issued: 08/07/2001
• Est. Priority Date: 09/16/1998
• Status: Expired due to Term

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Gordon, Joseph Grover II, Hart, Mark Whitney, Swanson, Sally Ann
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Bowers, Benjamin D.
• Application Number:
  US09/154,284
• Time in Patent Office: 1,056 Days
• Field of Search: 345/107, 359/296, 204/450, 204/600
• US Class Current: 345/107
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1677 Structural association of cells with optical devices, e.g. reflectors or illuminating devices

Abstract

An ambient light reflective color electrophoretic display is comprised of a plurality of color pixels; each comprised of at least two electrophoretic cells. Each cell is comprised of a suspension of charged, black or colored light-absorbing pigment particles in a light-transmissive fluid. Each cell is also comprised of a light-transmissive front window, at least one non-obstructing counter electrode, at least one non-obstructing collecting electrode, a light-reflective panel, and a color filter medium. The cells of different colors are in a laterally adjacent relationship to each other and the charged pigment particles are responsive to the electrodes. The filter medium in each cell can be a light-transmissive color filter element or a light-reflective colored surface or the pigment suspension fluid can be colored and serve as the filter medium.

Claims

1. An electrophoretic display having a plurality of cells disposed between a light-transmissive front window and a reflective rear panel, comprising:

multiple pixels each formed by multiple cells in a lateral adjacent arrangement relative to each other, each adjacent cell being between the front window and the reflective rear panel, and each cell containing charged, light-absorbing pigment particles in a light-transmissive fluid;

a non-obstructing collecting electrode to substantially remove pigment particles in the respective cells from the path of light through the cell;

a non-obstructing counter electrode cooperating with the collecting electrode to distribute the pigment particles in the respective cells to substantially block the path of light from the light source; and

a color filtering medium for each respective cell, and wherein in three adjacent cells of each pixel, respectively, the color filter medium is red and the associated particles are cyan, the color filter medium is green and the associated particles are magenta, and the color filter medium is blue and the associated particles are yellow.

2. An electrophoretic display having a plurality of cells disposed between a light-transmissive front window and a reflective rear panel, comprising:

multiple pixels each formed by three cells in a lateral adjacent arrangement relative to each other and each cell being between a light transmissive front window and a light-reflecting rear panel;

each cell containing charged, light-absorbing pigment particles in a light-transmissive fluid;

a non-obstructing collecting electrode to substantially remove pigment particles in the respective cells from the path of light so that light can pass through the cell without significant attenuation;

a non-obstructing counter electrode, cooperating with the collecting electrode to distribute the pigment particles in the respective cells to substantially block the path of light; and

in each pixel, a red color filter element located across the window in a first one of the cells, a blue color filter element located across the window in a second one of the cells, and a green color filter element located across the window in a third one of the cells.

3. An electrophoretic display as claimed in claim 2 wherein the particles are a color that absorbs the color transmitted by the color filter element.

4. An electrophoretic display as claimed in claim 2 wherein the particles are black or colored and wherein the fluid is substantially light-transmitting.

5. An electrophoretic display as claimed in claim 2 wherein the particles are a color complementary to the color of the filter element.

6. An electrophoretic display comprising:

a light-transmissive front window and a parallel, spaced-apart reflective rear panel, the front windows and rear panels defining a group of color cells disposed in a lateral adjacent relationship relative to each other to form a pixel;

a different colored light-transmissive fluid disposed between the front window and the reflective rear panel in each respective cell of the pixel, thereby forming a respective color filter medium for the respective cell;

a suspension including charged, light-absorbing pigment particles in the colored light-transmissive fluid of each cell;

a non-obstructing collecting electrode associated with each cell, which acts to substantially remove pigment particles from the light path so that light traversing the colored fluid can reach the reflective rear panel and emerge from the front window without significant attenuation; and

a non-obstructing counter electrode associated with each cell, which acts to position the pigment particles to substantially block the path of light so that light traversing the colored fluid is significantly attenuated before emerging from the front window, and wherein the respective collecting electrode and the respective counter electrode act in concert for respective cells to thereby position the particles in the respective cells.

7. An electrophoretic display as claimed in claim 6 wherein the particles are a color that absorbs the color transmitted by the colored light-transmissive fluid.

8. An electrophoretic display as claimed in claim 6 wherein the particles are black or colored.

9. An electrophoretic display as claimed in claim 6 wherein the particles are a color complementary to the color of the colored light-transmissive fluid.

10. An electrophoretic display as claimed in claim 6 wherein in three adjacent cells of each pixel, respectively, the colored light-transmissive fluid is red and the associated particles are cyan, the colored light-transmissive fluid is green and the associated particles are magenta, and the colored light-transmissive fluid is blue and the associated particles are yellow.

11. An electrophoretic display having a plurality of cells, each disposed between a light-transmissive front window and a reflective rear panel, a group of cells acting to form a pixel, the display comprising:

a red color fluid cell, a green color fluid cell, and a blue color fluid cell located in lateral adjacency relative to each other;

a suspension in each color fluid cell including charged, light-absorbing pigment particles in the colored fluid, the fluid being a light-transmissive fluid;

non-obstructing collecting electrodes, at least one associated with each color cell, which act to substantially remove pigment particles from the light path so that light can pass through the cell without significant attenuation; and

non-obstructing counter electrodes, at least one associated with each color cell, which act to position the pigment particles to substantially block the path of light so that light is significantly attenuated before emerging from the front window, and wherein the respective collecting electrodes and the respective non-obstructing electrodes act in concert for respective cells to thereby position the particles in the respective cells.

12. An electrophoretic display comprising a plurality of cells having a light-transmissive front window and a reflective rear panel, and wherein a pixel comprises three individual cells, the cells being in lateral adjacency relative to each other:

a) the first cell comprising a suspension of charged pigment particles in a first colored fluid, the first colored fluid serving to act as a first color filter and the pigment particles absorbing the visible light not absorbed by the first colored fluid;

b) the second cell comprising a suspension of charged pigment particles in a second colored fluid, the second colored fluid serving to act as a second color filter and the pigment particles absorbing the visible light not absorbed by the second colored fluid;

c) the third cell comprising a suspension of charged pigment particles in a third colored fluid, the third colored fluid serving to act as a third color filter and the pigment particles absorbing the visible light not absorbed by the third colored fluid; and

wherein

d) each cell includes;

(i) a non-obstructing collecting electrode acting to substantially remove pigment particles from the path of light through the colored fluid so that the color of the fluid is visible to the viewer, and

(ii) a non-obstructing counter electrode cooperating with the collecting electrode to position the pigment particles in the path of light through the colored fluid so that the color of the fluid is not visible to the viewer.

13. A display as claimed in claim 12 wherein the first cell comprises a suspension of charged, black pigment particles in a red fluid, the second cell comprises a suspension of charged, black pigment particles in a green fluid, and the third cell comprises a suspension of charged, black pigment particles in a blue fluid.

14. A display as claimed in claim 12 wherein the first cell comprises a suspension of charged, cyan pigment particles in a red fluid, the second cell comprises a suspension of charged, magenta pigment particles in a green fluid, and the third cell comprises a suspension of charged, yellow pigment particles in a blue fluid.

15. An electrophoretic display comprising a plurality of cells in a lateral adjacent arrangement and containing a suspension of charged, light-absorbing pigment particles in a light-transmissive fluid, each cell comprising:

a light-transmissive front window;

a rear panel having a light-reflective surface;

a respective color filter element associated with the reflective rear panel for each cell;

a non-obstructing collecting electrode, disposed relative to the front window and the reflective rear panel, the collecting electrode acting to substantially remove pigment particles from the path of light so that light can reach and reflect from the rear panel and emerge from the front window without significant attenuation;

a non-obstructing counter electrode acting to position the pigment particles to substantially absorb ambient light traversing the cell and thereby substantially prevent the light from emerging from the front window; and

wherein

the cells each respectively contain a suspension of charged, pigment particles that absorb the color of the light transmitted by the color filter element.

16. A display as claimed in claim 15 wherein the pigment particles are black, and the filter element for respective cells are red, green, and blue.

17. A display as claimed in claim 15 wherein the colors of the filters and the respective colors of the particles are complementary.

18. A display as claimed in claim 15 wherein, in three adjacent cells, respectively, the colored pigment particles are cyan and the associated filter element is red, the colored pigment particles are magenta and the associated filter element is green, and the colored pigment particles are yellow and the associated filter element is blue.

19. A display as claimed in claim 15 wherein the filter elements for respective cells are incorporated as part of the reflective rear panel.

20. A display as claimed in claim 15 wherein the filter elements for respective cells are colored and reflective rear panel elements.