Electrophoretic display panel with selective character addressability

• US 5,467,107 A
• Filed: 09/28/1994
• Issued: 11/14/1995
• Est. Priority Date: 10/01/1993
• Status: Expired due to Fees

• Current Assignee: AU Optronics Corporation
• Original Assignee: Anixa Biosciences, Inc. (f/k/a ITUS Corporation)
• Inventors: Lewit, Edward, DiSanto, Frank J., Krusos, Denis A.
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Saras, Steven J.
• Application Number:
  US08/313,987
• Time in Patent Office: 412 Days
• Field of Search: 345/48, 345/49, 345/50, 345/84, 345/85, 345/80, 345/87, 345/210, 345/105, 345/107, 241/20, 359/296, 359/54
• US Class Current: 345/107
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 3/3446 with more than two electrodes controlling the modulating element

Abstract

An electrophoretic display includes a plurality of groups of intersecting row and column electrodes, and a plurality of parallel anode electrode segments disposed in spaced relation within a fluid-tight envelope containing a suspension of pigment particles in a dielectric fluid. Each respective group of row and column electrodes and a corresponding anode segment are indicative of a character line of displayed text. The display includes a line control system operable in a partial erase mode to partially erase a character line having a character thereof selected for erasure and operable in a rewriting mode to rewrite to the character line all characters not selected for erasure. The line control system is operable to alternate sequentially between the two modes until the selected character is simply erased or replaced entirely with a new character.

Claims

1. An electrophoretic display apparatus having a selectively erasable display including a plurality of character lines, said display apparatus being capable of allowing a user to erase at least one character in one of said character lines which has been written to said display without having to completely re-write every character in said character line, comprising:

a fluid-tight envelope having a portion thereof which is at least partially transparent;

an electrophoretic fluid contained within said envelope, said fluid having pigmented particles suspended therein, and a plurality of row and column electrodes passing through said envelope and said fluid;

a plurality of anode segments passing through said envelope, wherein each character line of said display is defined by at least one of the anode segments and by a corresponding group of row and column electrode intersections;

line control means operable in a partial erasure mode to apply a first potential bias of a given polarity between an anode segment corresponding to a selected character line and a corresponding group of row and column intersections, said first potential bias being applied for a first given duration of time sufficient to cause said pigment particles to move relative to said intersections and partially erase said selected character line, said line control means being further operable in a rewriting mode to apply a second potential bias of an opposite polarity between said anode segment and said group of row and column intersections for a second given duration of time sufficient to partially rewrite every character of said selected character line except for at least one character selected for erasure, and said line control means being further operable to sequentially apply said first and second potential biases until said at least one of said characters selected for erasure is no longer displayed.

2. The apparatus according to claim 1, wherein each character line is defined by a single anode segment, wherein the length and width of said anode segment are substantially equal to the length and width of a character line.

3. The apparatus according to claim 1, wherein said given polarity of said first potential is negative.

4. The apparatus according to claim 3, wherein said line control means is adapted to apply said first potential by supplying a negative voltage to an anode segment of the selected character line while supplying a negative voltage to column electrodes corresponding to said at least one of said characters selected for erasure.

5. The apparatus according to claim 3, wherein said line control means is adapted to apply said second potential by supplying a first positive voltage to an anode segment of the selected character line while supplying a second positive voltage to the column electrodes corresponding to said at least one of said characters selected for erasure.

6. The apparatus according to claim 5, wherein said line control means is adapted to place cathode lines corresponding to said at least one of said characters selected for erasure at 0 volts while applying said second potential.

7. A method of selectively erasing at least one character written on a character line of an electrophoretic display, said display including at least one character line defined by a group of row and column electrode intersections and by at least one corresponding anode electrode segment, said at least one character line having a plurality of characters wherein at least one of said characters is selected for erasure, and an electrophoretic suspension layer disposed between said row and column electrodes and said anode segment, comprising the steps of:

(a) partially erasing all of said characters of said at least one character line including said at least one of said characters selected for erasure;

(b) rewriting to said at least one character line all of said characters except said at least one character selected for erasure;

(c) repeating steps (a) and (b) until said at least one of said characters selected for erasure is no longer visible on said display.

8. The method according to claim 7, wherein said partially erasing step comprises applying a potential bias of a given polarity between the at least one anode segment and row and column electrode corresponding to said at least one character line for a period of time sufficient to cause pigment particles to move relative to said intersections and to thereby partially erase said character line.

9. The method according to claim 8, wherein said given polarity is negative.

10. The method according to claim 9, wherein said partial erasing step comprises applying a negative voltage to the at least one anode segment.

11. The method according to claim 7, wherein said rewriting step comprises applying a potential bias of an opposite polarity between the at least one anode segment and selected row and column intersections of said at least one character line for a period of time sufficient to at least partially rewrite said characters of said at least one character line not selected for erasure, said selected row and column intersections corresponding to said characters not selected for erasure.

12. The method according to claim 11, wherein said rewriting step comprises applying a first positive voltage to the at least one anode segment of the at least one character line while applying a second positive voltage to the column electrodes corresponding to said characters of the at least one character line not selected for erasure.

13. The method according to claim 12, wherein the second voltage is equal to or greater than said first voltage.

14. The method according to claim 11, wherein a zero voltage is applied to column electrodes corresponding to said at least one character selected for erasure during said rewriting step.

15. The method according to claim 7, further comprising the step of gradually replacing said character selected for erasure with a new character after each partial erasing step.

16. The method according to claim 7, wherein said replacing step comprises applying a potential bias of an opposite polarity between the at least one anode segment and row and column intersections of said at least one character line corresponding to said selected character for erasure for a period of time sufficient to partially replace said selected character for erasure with a new character.

17. An electrophoretic display for allowing a user to first write an image defined by a plurality characters to said display and then erase at least one of said characters without completely re-writing said entire image, comprising:

a fluid-tight envelope having a portion thereof which is at least partially transparent;

an electrophoretic fluid contained within said envelope, said fluid having pigmented particles suspended therein;

a plurality of groups of intersecting row and column electrodes, each group being indicative of a character line which defines a portion of an image to be displayed, said groups being disposed within said envelope;

a plurality of parallel anode electrode segments, each respective one of said anode segments being positioned within said envelope adjacent a corresponding one of said groups; and

means operable in a partial erase mode to address said anode electrode segments to partially erase a character line and operable in a rewriting mode to rewrite all characters of said character line except for at least one character selected for erasure, said means being sequentially operable until only said character selected for erasure is no longer visible on said display.

18. The display according to claim 17, wherein each of said groups and said anode segments are fabricated from ITO deposited on a glass sheet.

19. The display according to claim 17, wherein each character line is defined by a plurality of anode segments.