Reflective electrophoretic display with laterally adjacent color cells using an absorbing panel

• US 6,225,971 B1
• Filed: 09/16/1998
• Issued: 05/01/2001
• 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:
  US09/154,114
• Time in Patent Office: 958 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, white or colored light-scattering 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-absorbing 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. Alternatively, the pigment suspension fluid itself or the pigment particles themselves can be colored and serve as the filter medium.

Claims

1. An electrophoretic display comprising:

a light-transmissive front window and a parallel, spaced-apart light-absorbing black rear panel, the front window and rear panel defining a plurality of cells disposed in a lateral adjacent relationship relative to each other, the cells being grouped into threes with each group of three forming a pixel;

wherein each cell contains charged, light-scattering substantially white particles in a light-transmissive fluid;

a color filter element across the front window of each cell, the filter elements for the three cells in a pixel being of different colors from one another, said different colors being red, green and blue;

a non-obstructing collecting electrode for each cell to substantially remove particles from the path of light through the cell so that light can reach the light absorbing black rear panel, thereby causing the cell to appear black; and

a non-obstructing counter electrode, cooperating with the collecting electrode for each cell to distribute the particles in the cell to substantially scatter and reflect the light that enters the cell, thereby causing the cell to have the color of its filter element.

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

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

each cell containing charged, light-scattering 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 reach the light-absorbing rear panel without significant scattering or reflection;

a non-obstructing counter electrode, cooperating with the collecting electrode to distribute the pigment particles in the respective cells to substantially scatter and reflect the light that enters the respective cells; and

a color filter element for each respective cell, the respective filter element located across the window of each respective cell;

and wherein in three adjacent cells of each pixel, respectively, the color filter element is red and its associated light-absorbing rear panel is cyan, the color filter element is green and its associated light-absorbing rear panel is magenta, and the color filter element is blue and its associated light-absorbing rear panel is yellow.

3. An electrophoretic display as claimed in claim 2 wherein the particles are substantially white and the fluid is substantially light-transmitting.

4. An electrophoretic display comprising:

a light-transmissive front window and a parallel, spaced-apart light-absorbing 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 light-absorbing 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-scattering 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 can pass through the colored fluid and reach the light-absorbing rear panel without significant scattering or reflection; and

a non-obstructing counter electrode associated with each cell, which acts to position the pigment particles to substantially scatter and reflect the light so that light entering the cell and travelling through the colored fluid is significantly reflected back through the front window before reaching the light-absorbing rear panel, 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.

5. An electrophoretic display as claimed in claim 4 wherein the particles are substantially white and the fluid is substantially light-transmitting.

6. An electrophoretic as claimed in claim 4 wherein the light-absorbing rear panel is a color that absorbs the color transmitted by the colored fluid.

7. An electrophoretic display as claimed in claim 4 wherein the color of the light-absorbing rear panel is black.

8. An electrophoretic display as claimed in claim 4 wherein the color of the light-absorbing rear panel is complementary to the color of light transmitted by the colored fluid.

9. An electrophoretic display as claimed in claim 4 wherein in three adjacent cells of each pixel, respectively, the colored light-transmissive suspension fluid is red and its associated light-absorbing rear panel is cyan, the colored light-transmissive suspension fluid is green and its associated light-absorbing rear panel is magenta, and the colored light-transmissive suspension fluid is blue and its associated light-absorbing rear panel is yellow.

10. An electrophoretic display comprising a plurality of cells, each disposed between a light-transmissive front window and a light-absorbing rear panel, a group of cells acting to form a pixel 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-scattering 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 colored fluid and reach the light-absorbing rear panel without significant scattering and reflection; and

non-obstructing counter electrodes, at least one associated with each color cell, which act to position the pigment particles to substantially scatter and reflect the light so that light travelling through the colored fluid is significantly reflected back through the front window before reaching the light-absorbing rear panel, the collecting electrodes and the counter electrodes in each respective cell acting in concert to thereby position the particles in the respective cells.

11. An electrophoretic display as claimed in claim 10 wherein the light-absorbing rear panel is black or a color complementary to the color of the light-transmissive suspension fluid.

12. An electrophoretic display as claimed in claim 10 wherein in three adjacent cells of each pixel, respectively, the colored light-transmissive suspension fluid is red and its associated light-absorbing rear panel is cyan, the colored light-transmissive suspension fluid is green and its associated light-absorbing rear panel is magenta, and the colored light-transmissive suspension fluid is blue and its associated light-absorbing rear panel is yellow.

13. An electrophoretic display comprising a plurality of cells having a light-transmissive front window and a light-absorbing 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, light-scattering pigment particles in a first colored fluid, the first colored fluid serving to act as a first color filter and the pigment particles scattering the visible light not absorbed by the first colored fluid;

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

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

d) each cell including;

(i) a non-obstructing collecting electrode acting to substantially remove pigment particles from the path of light, so that light can pass through the colored fluid and reach the light-absorbing rear panel without significant scattering or reflection, and

(ii) a non-obstructing counter electrode acting to position the pigment particles in the path of light, so that light entering the cell and traveling through the colored fluid is substantially scattered and reflected back through the front window before reaching the light-absorbing rear panel, the collecting electrode and the counter electrode acting in concert for respective cells to thereby position the particles in the respective cells.