ELECTROPHORETIC DISPLAY DEVICE

• US 3,668,106 A
• Filed: 04/09/1970
• Issued: 06/06/1972
• Est. Priority Date: 04/09/1970
• Status: Expired due to Term

• Current Assignee: Isao Ota
• Original Assignee: Isao Ota
• Inventors: Ota, Isao
• Primary Examiner(s): Mack, John H.
• Assistant Examiner(s): Prescott, A. C.
• Application Number:
  US05/026,874
• Time in Patent Office: 789 Days
• Field of Search: 204/180,181,299 96/1A
• US Class Current: 358/305
• 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
• CPC Class Codes: H01J 29/10 Screens on or from which an image or pattern is formed, picked up, converted or stored

Abstract

An electorphoretic display and/or recording device in which an electrophoretic suspension layer including a dispersion of at least one electrophoretic material in a finely divided powder form suspended in a suspending medium is interposed between a pair of electrodes. An electric field is imposed across the electrophoretic suspension layer to change the optical reflective property of the suspension layer by changing the spatial distribution of the electrophoretic material in the suspending medium electrophoretically.

Claims

2. A device as claimed in claim 1 wherein said suspension layer includes at least two electrophoretic materials, one of which differs in the charge polarity and optical reflective property from the other.

3. A device as claimed in claim 1 wherein said suspension layer includes at least two electrophoretic materials, one of which differs in electrophoretic mobility and the optical reflective property from the other.

4. A device as claimed in claim 1, wherein said suspending medium is colored.

5. A device as claimed in claim 1 further comprising a porous layer inserted in said suspending medium.

6. A device as claimed in claim 1 wherein at least one of said first electrode and second electrode is in the shape of a given pattern.

7. A device as claimed in claim 1 wherein said suspension further contains a binder for said electrophoretic material, which binder is at least partially soluble in said suspending medium.

8. A device as claimed in claim 1, wherein said suspending medium is a hardenable material.

9. A device as claimed in claim 1 wherein said suspending medium is heat hardenable.

10. A device as claimed in claim 1 wherein said suspending medium is heat softenable.

11. A device as claimed in claim 1 wherein said suspending medium is solvent softenable.

12. A device as claimed in claim 1 wherein said means for applying an electric field includes means for controlling said electric field with respect to at least one property selected from the group consisting of strength, length of time of application and polarity.

13. A device as claimed in claim 1 further including a housing enclosing said suspension layer.

14. A device as claimed in claim 13 wherein at least one of said first electrode and second electrode is in the shape of a given pattern.

15. A device as claimed in claim 14 further comprising a conductive lead extending out of said housing.

16. A device as claimed in claim 13, wherein said suspension layer has a plurality of spacers therein extending transversely thereof.

17. A device as claimed in claim 13, wherein at least one of said first electrodes and second electrodes is coated with an insulating layer whis is in contact with said suspension layer.

18. A device as claimed in claim 13 in which said housing has two spaced opposed major housing walls between which said suspension layer and said electrodes are positioned, and at least one of which walls is transparent.

19. A device as claimed in claim 13 wherein at least one of said first electrode and second electrode is transparent and the housing has a transparent housing wall covering said transparent electrode.

20. A device as claimed in claim 19 wherein said first electrode covers the whole of one surface of said suspension layer, and said second electrode covers the whole of the other surface of said suspension layer.

21. A device as claimed in claim 19 wherein at least one of said first electrode and second electrode is in the shape of a given pattern.

22. A device as claimed in claim 19 wherein at least one of said first electrode and second electrode is divided into a plurality of segmental electrodes.

23. A device as claimed in claim 19 wherein said first electrode consists of a plurality of strips of electrode material which are parallel to each other, and said second electrode consists of a plurality of strips of electrode material which are parallel to each other and are orthogonal to said first electrode strips.

24. A device as claimed in claim 13 wherein said housing has two opposite major walls, and one of said electrodes forms one of said two opposite major housing walls.

25. A device for display, comprising an electrophoretic suspension layer having a suspending medium and at least one electrophoretic material in a finely divided powder form suspended in said suspending medium, said suspension layer having two opposite major surfaces, a transparent electrode positioned on one of said major surfaces of said suspension layer, a housing having said suspension layer enclosed therein and having a transparent housing wall over said electrode, and a cathode ray vacuum tube having an electron gun therein and having said housing closing the end of said vacuum tube opposite from said electron gun with the transparent housing wall on the outside of the vacuum tube and with said other major surface of the suspension layer facing toward said electron gun.