Electrophoretic medium with gaseous suspending fluid

• US 8,129,655 B2
• Filed: 09/03/2003
• Issued: 03/06/2012
• Est. Priority Date: 09/03/2002
• Status: Expired due to Fees

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Jacobson, Joseph M., Whitesides, Thomas H., Zehner, Robert W.
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US10/605,039
• Publication Number:
  US 20040112750A1
• Time in Patent Office: 3,107 Days
• Field of Search: 219/121.54, 219/121.57, 219/121.39, 219/124.34, 219/121.44, 219/121.48, 219/121.59, 219/75, 219/137.63, 219/121.4, 219/121.43, 219/121.52, 204/601, 204/606, 428/400.24, 388 16- 18, 388/901, 388/63, 345/31, 345/107
• US Class Current: 219/121.39
• CPC Class Codes: G02F 1/1671 involving dry toners
• CPC Class Codes: G02F 1/16757 Microcapsules
• CPC Class Codes: G09F 9/372 the positions of the elements being controlled by the application of an electric field

Abstract

An electrophoretic medium (102) comprises a plurality of capsules (104), each capsule comprising an internal phase comprising a plurality of electrophoretically mobile particles (106, 108) in a gaseous suspending medium, and a capsule wall surrounding the internal phase. Various processes for producing such an electrophoretic medium are also described.

Claims

1. An electrophoretic medium comprising a plurality of capsules, each capsule comprising an internal phase comprising a plurality of electrophoretically mobile particles in a gaseous suspending medium, and a capsule wall surrounding the internal phase.

2. An electrophoretic medium according to claim 1 wherein each capsule comprises a single type of electrophoretically mobile particle, each capsule having a pair of substantially planar opposed surfaces differing in area.

3. An electrophoretic medium according to claim 1 comprising two types of particles having differing optical characteristics and differing electrophoretic mobilities.

4. An electrophoretic medium according to claim 3 wherein one type of particle has substantially zero electrophoretic mobility.

5. An electrophoretic medium according to claim 3 wherein the two types of particles bear charges of the same polarity but differ in electrophoretic mobility.

6. An electrophoretic medium according to claim 1 wherein the medium comprises a plurality of bubbles, each containing the electrophoretically mobile particles and the gaseous suspending medium, the bubbles being dispersed in a continuous solid phase.

7. An electrophoretic medium according to claim 1 wherein the gaseous suspending medium comprises carbon dioxide.

8. An electrophoretic display comprising an electrophoretic medium according to claim 1 and at least one electrode disposed adjacent the electrophoretic medium and arranged to apply an electric field to the medium.