ELECTROPHORETIC DISPLAY DEVICE OF THE LUMINESCENT TYPE

• US 3,792,308 A
• Filed: 06/08/1970
• Issued: 02/12/1974
• Est. Priority Date: 06/08/1970
• Status: Expired due to Term

• Current Assignee: Isao Ota
• Original Assignee: Isao Ota
• Inventors: Ota, Isao
• Primary Examiner(s): Demeo, Palmer C.
• Application Number:
  US05/044,023
• Time in Patent Office: 1,345 Days
• Field of Search: 313/18A,18R,109.5,54,92 178/7.87 315/169TV,150 204/299PE
• US Class Current: 315/150
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: H05B 33/12 Light sources with substantially two-dimensional radiating surfaces
• CPC Class Codes: H05B 33/20 characterised by the chemical or physical composition or the arrangement of the material in which the electroluminescent material is embedded

Abstract

An electrophoretic display and/or recording device of the luminescent type in which a luminescent 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. Said suspension layer includes at least one luminescent component therein and emits luminescent light when radiation flux or electric field is applied thereto. An electric field is imposed across the electrophoretic suspension layer to change the luminescent property of the suspension layer by changing the spatial distribution of the electrophoretic material in the suspending medium elctrophoretically.

Claims

2. A device as claimed in claim 1 wherein said means for brightening said suspension layer is a radiation source for applying radiation flux to said suspension layer.

3. A device as claimed in claim 2 wherein said radiation source is an U.V. light source.

4. A device as claimed in claim 2 wherein said radiation source is included in said suspension layer.

5. A device as claimed in claim 4 wherein said radiation source is a radioactive isotope selected from the group consisting of radium, strontium 90, tritium and promethium 147.

6. A device as claimed in claim 1 wherein said means for brightening said suspension layer is a voltage source for applying an electric voltage between said first electrode and said second electrode so as to brighten said suspension layer.

7. A device as claimed in claim 6 wherein said electric voltage is A.C. voltage.

8. A device as claimed in claim 6 wherein said electric voltage is repeated pulse voltage.

9. A device as claimed in claim 6 wherein said electric voltage is pulsating electric voltage.

10. A device as claimed in claim 1 wherein at least said electrophoretic material is luminescent.

11. A device as claimed in claim 1 wherein there are at least two electrophoretic materials, one of which differs in the charge polarity and luminescent property from the other.

12. A device as claimed in claim 1 wherein there are at least two electrophoretic materials, one of which differs in the electrophoretic mobility and luminescent property from the other.

13. A device as claimed in claim 1 wherein at least said suspending medium is luminescent.

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

15. A device as claimed in claim 14 wherein at least said porous layer is luminescent.

16. A device as claimed in claim 1 wherein said suspension layer further contains a binder for said electrophoretic material.

17. 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 strength.

18. 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 length of time of application.

19. 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 polarity.

20. A device as claimed in claim 1 wherein said suspension layer has the property of being hardenable.

21. A device as claimed in claim 20 wherein said suspension layer has the property of being heat hardenable.

22. A device as claimed in claim 1 wherein said suspension layer has the property of being heat softenable.

23. A device as claimed in claim 1 wherein said means for applying said electric field across said suspension layer through said electrodes also acts as said means for brightening said suspension layer.

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

25. A device as claimed in claim 24 in which said housing has two spaced opposed major housing walls between which said suspension layer and said first electrode and second electrode are positioned and at least one of which walls and said electrode facing toward said one wall are transparent with respect to at least visible light.

26. A device as claimed in claim 24 wherein at least one of said first electrode and second electrode is transparent with respect to at least visible light and said housing has a housing wall which is transparent with respect to at least visible light and covers said transparent electrode.

27. A device as claimed in claim 2 wherein at least one of said first electrode and second electrode is transparent with respect to said radiation flux and another of said first electrode and second is transparent with respect to visible light.

28. A device as claimed in claim 27 further including a housing enclosing said suspension layer, said housing having two spaced opposed major housing walls, at least one of which walls is transparent with respect to said radiation flux and has said one electrode attached therein, another of which walls is transparent with respect to visible light and has said another electrode attached therein.

29. A device as claimed in claim 28 wherein a source of said radiation flux is positioned behind said housing enclosing said suspension layer.

30. A device as claimed in claim 2 further including a housing enclosing said suspension layer, said housing having two spaced opposed major housing walls, at least one of which walls is transparent with respect to said radiation flux and visible light and has one electrode of said first electrode and second electrode attached thereto, said one electrode is transparent with respect to said radiation flux and visible light.

31. A device as claimed in claim 26 wherein at least one of said first electrode and second electrode is in the shape of a given pattern.

32. A device as claimed in claim 26 wherein at least one of said first electrode and second electrode is divided into a plurality of segmental electrodes.

33. A device as claimed in claim 26 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.

34. A device as claimed in claim 26 wherein said suspension layer has a plurality of spacers therein extending transversely thereof so as to form a plurality of suspension units.

35. A device as claimed in claim 25 wherein at least one of said first electrode and second electrode is coated with an insulating layer which is in contact with said suspension layer.

36. A device as claimed in claim 34 wherein said plurality of suspension units have at least two different luminescent colors for each other.

37. A device as claimed in claim 26 wherein said transparent housing wall has mosaic color filters thereon.

38. A device as claimed in claim 28 wherein said one housing wall and said another housing wall consisting essentially of the inner pipe and the outer pipe of a pair of concentric cylindrical pipes, respectively, said inner pipe encloses therein a gas and constitutes said radiation source consisting of a gas discharge lamp capable of emitting said radiation flux.

39. A device for display, comprising a luminescent 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 ahd having a transparent housing wall over said electrode, and a cathode ray vacuum tube having an electron gun therein ahd having said housing closing tHe end of said vacuum tube opposite from said electron gun with the transparent housing wall on the outside of said vacuum tube and with said other major surface of the suspension layer facing toward said electron gun;

and means for applying radiation flux to said suspension layer so as to brighten said suspension layer.