Electrophoretic image reproduction process

• US 3,892,568 A
• Filed: 04/17/1970
• Issued: 07/01/1975
• Est. Priority Date: 04/23/1969
• Status: Expired due to Term

• Current Assignee: Isao Ota
• Original Assignee: Isao Ota
• Inventors: Ota, Isao
• Primary Examiner(s): Martin, Jr., Roland E.
• Application Number:
  US05/029,414
• Time in Patent Office: 1,901 Days
• Field of Search: 96/1,1.3 204/180,181,18R
• US Class Current: 430/19
• 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: G03G 17/04 using photoelectrophoresis

Abstract

Electrophoretic image reproduction process is disclosed. In this process, a D.C. voltage is uniformly applied across an electrophoretic suspension layer including a dispersion of at least one electrophoretic material in a finely divided powder form suspended in a suspending medium, whereby said D.C. voltage changes the spatial distribution of said electrophoretic material so as to change an optical reflective property of said electrophoretic suspension layer. An electric field in a given image is then applied to said changed suspension layer, whereby said electrophoretic material stricken by said electric field moves electrophoretically and reproduces said given image on said electrophoretic suspension layer.

Claims

1. AN ELECTROPHORETIC IMAGE REPRODUCTION PROCESS WHICH COMPRISES:

UNIFORMLY APPLYING A D.C. VOLTAGE TO AN ELECTROPHORETIC SUSPENSION LAYER, SAID SUSPENSION LAYER BEING SELECTED FROM THE GROUP CONSISTING OF (1) A SUSPENSION INCLUDING AT LEAST ONE ELECTROPHORETIC MATERIAL SUSPENDED IN A COLORED SUSPENDING MEDIUM WHICH IS CAPABLE OF HIDING SAID AT LEAST ONE ELECTROPHOPHORETIC MATERIALS, (2) A SUSPENSION INCLUDING AT LEAST ONE ELECTROPHORETIC MATERIAL SUSPENDED IN A SUSPENDING MEDIUM HAVING FURTHER A COLORED MATERIAL FORMING A POROUS LAYER THEREIN WHICH IS POROUS TO SAID AT LEAST ONE ELECTROPHORETIC MATERIAL AND IS CAPABLE OF HIDING SAID AT LEAST ONE ELECTROPHORETIC MATERIAL, (3) A SUSPENSION INCLUDING AT LEAST TWO ELECTROPHORETIC MATERIALS SUSPENDED IN A SUSPENDING MEDIUM, ONE OF SAID AT LEAST TWO ELECTROPHERIC MATERIALS DIFFERING IN CHARGE POLARITY AND COLOR FROM THE OTHER ELECTROPHERETIC MATERIAL AND BEING CAPABLE OF HIDING THE OTHER ELECTROPHORETIC MATERIAL, (4) AND A SUSPENSION INCLUDING AT LEAST TWO ELECTROPHORETIC MATERIALS SUSPENDED IN A SUSPENDING MEDIUM, ONE OF SAID AT LEAST TWO ELECTROPHORETIC MATERIALS DIFFERING IN ELECTROPHORETIC MOBILITY AND COLOR FROM THE OTHER ELECTROPHORETIC MATERIAL AND BEING CAPABLE OF HIDING THE OTHER ELECTROPHORETIC MATERIAL, THE AVERAGE SIZE OF SAID ELECTROPHORETIC MATERIAL IN EACH OF SAID SUSPENSIONS BEING FROM 0.1 TO 50 MICRONS, WHEREBY SAID D.C. VOLTAGE CHANGES THE OPTICAL REFLECTIVE COLOR OF SAID ELECTROPHORETIC SUSPENSION LAYER, AND APPLYING AN ELECTRIC FIELD IN A GIVEN IMAGE TO SAID CHANGED ELECTROPHORETIC SUSPENSION LAYER, WHEREBY SAID ELECTROPHORETIC MATERIAL STRUCK BY SAID ELECTRIC FIELD MOVES ELECTROPHORETICALLY IN ACCORDANCE WITH THE DIRECTION OF SAID ELECTRIC FIELD AND REPRODUCES SAID GIVEN IMAGE ON SAID ELECTROPHORETIC SUSPENSION LAYER.

2. An electrophoretic image reproduction process defined in claim 1, wherein said suspension layer comprises at least one electrophoretic material suspended in a suspending medium having further a colored material forming a porous layer therein which is porous to said at least one electrophoretic material and is capable of having said at laest one electrophoretic material pass therethrough and of hiding said at least one electrophoretic material.

3. An electrophoretic image reproduction process defined by claim 2, wherein said suspending medium is colored.

4. An electrophoretic image reproduction process defined by claim 2, wherein there are at least two electrophoretic materials, one of which differs in the charge polarity and an optical reflective color from the other.

5. An electrophoretic image reproduction process defined by claim 2, wherein there are at least two electrophoretic materials, one of which differs in electrophoretic mobility and the optical reflective color from the other.

6. An electrophoretic image reproduction process defined by claim 2, wherein said electric field in a given image is a D.C. field in a reverse polarity to that of said D.C. voltage.

7. An electrophoretic image reproduction process defined by claim 2, wherein said electric field in a given image is an A.C. field.

8. An electrophoretic image reproduction process defined by claim 2, wherein said electrophoretic suspension layer is subjected to said D.C. voltage applied between a first electrode and a second electrode, at least one of which is a roller electrode.

9. An electrophoretic image reproduction process defined by claim 1, wherein said electrophoretic suspension layer is enclosed in a housing having two opposite major housing walls at least one of which is transparent.

10. An electrophoretic image reproduction process defined by claim 9, wherein one of said two opposite major housing walls has a first electrode attached thereto, another transparent housing wall has a second transparent electrode attached thereto, at least one of the first electrode and the second electrode consists of plural electrodes.

11. An electrophoretic image reproduction process defined by claim 9, wherein one of said two opposite major housing walls has a first electrode consisting of a plurality of electrically divided electrodes, another of said two opposite major housing walls has a second electrode attached thereto, at least one of said first electrode and said second electrode is transparent and is attached to said transparent housing wall, said D.C. voltage is applied between said first electrode and said second electrode, said electric field in a given image is applied to said electrophoretic suspension layer by applying a voltage in reverse polarity to that of said D.C. voltage between selected electrodes of said first electrode and said second electrode.

12. An electrophoretic image reproduction process defined by claim 9, wherein one of said two opposite major housing walls has a first electrode consisting of a plurality of strips of electrode material which are parallel to each other, and another of said two opposite major housing walls has a second electrode consisting of a plurality of strips of electrode material which are parallel to each other and are orthogonal to said first electrode strips, at least one of said first electrode and said second electrode is transparent and is attached to said transparent housing wall, said D.C. voltage is applied to said electrophoretic suspension layer by applying a D.C. voltage between said first electrode and said second electrode, said electric field in a given image is applied to said suspension layer by applying a reversed D.C. voltage between selected electrodes of said first electrode and selected electrodes of said second electrode.

13. An electrophoretic image reproduction process defined by claim 1, wherein said reproduced image is erased by uniformly applying a D.C. voltage to said electrophoretic suspension layer.

14. An electrophoretic image reproduction process defined by claim 2, wherein said reproduced image is erased by applying an A.C. voltage to said electrophoretic suspension layer.

15. An electrophoretic image reproduction process defined by claim 1, wherein said electrophoretic suspension layer is in a solid state at room temperature but is in a liquid state above room temperature.

16. An electrophoretic image reproduction process defined by claim 1, wherein said electrophoretic suspension layer is in a solid state at room temperature but can become soft enough for electrophoretic movement of said electrophoretic material, by application of solvent thereto.

17. An electrophoretic image reproduction process defined by claim 1 wherein said suspending medium is heat hardenable.