ELECTROPHORETIC DISPLAY DEVICE

• US 3,756,693 A
• Filed: 12/20/1971
• Issued: 09/04/1973
• Est. Priority Date: 12/21/1970
• Status: Expired due to Term

• Current Assignee: Isao Ota
• Original Assignee: Isao Ota
• Inventors: Ota, Isao
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): McGraw, V. P.
• Application Number:
  US05/209,729
• Time in Patent Office: 624 Days
• Field of Search: 350/16R 40/52 313/18A,109.5 204/299
• 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
• CPC Class Codes: G03G 17/04 using photoelectrophoresis

Abstract

An electrophoretic display 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, at least one of which is transparent. A colored layer of a desired pattern is provided at the transparent electrode. An electric field is imposed between the pair of electrodes so as to change the optical property such as reflective color or luminescent color of the suspension layer by changing the spatial distribution of the electrophoretic material in the suspending medium electrophoretically.

Claims

1. An electrOphoretic display device 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 first electrode and a second electrode which are spaced from and opposed to each other and are positioned on said two opposite major surfaces of said suspension layer, respectively;

at least one of said first electrode and said second electrode being transparent;

a colored layer having at least one aperture in a desired pattern and positioned at the transparent electrode; and

means coupled to said electrodes for applying an electric field across said suspension layer through said electrodes, said electric field changing the optical property of said suspension layer so as to produce a display of said desired pattern.

2. A device as claimed in claim 1 wherein at least one of said electrodes is in the shape of the desired pattern.

3. A device as claimed in claim 1 wherein at least one of said electrodes has a plurality of segments.

4. A device as claimed in claim 1 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.

5. A device as claimed in claim 1 wherein said colored layer has at least two color-different from each other.

6. A device as claimed in claim 1 wherein said colored layer is luminescent.

7. A device as claimed in claim 1 wherein said colored layer is against said transparent electrode and is between said electrode and said suspension layer.

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

9. A device as claimed in claim 8 wherein said housing has a transparent housing wall covering said transparent electrode.

10. A device as claimed in claim 9 wherein said colored layer is between said transparent electrode and said transparent housing wall.

11. A device as claimed in claim 9 wherein said colored layer is on the outside surface of said transparent housing wall.

12. A device as claimed in claim 1 wherein the reflective color of said electrophoretic suspension layer is changeable by application of said electric field.

13. A device as claimed in claim 5 wherein said suspension layer is divided into a plurality of suspension units which differ in color from each other.

14. A device as claimed in claim 1 wherein said first electrode and second electrode are both transparent and further comprising an additional colored layer, there being a colored layer at both of said electrodes.

15. A device as claimed in claim 1 wherein one of the components of said suspension layer is luminescent, the luminescent color of said suspension layer being changeable by application of said electric field.