METHODS FOR DRIVING ELECTROPHORETIC DISPLAYS USING DIELECTROPHORETIC FORCES

• US 20110193840A1
• Filed: 04/22/2011
• Published: 08/11/2011
• Est. Priority Date: 07/20/1995
• Status: Abandoned Application

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Jacobson, Joseph M., Paolini, Richard J. JR., McCreary, Michael D., Whitesides, Thomas H., Arango, Alexi C., Amundson, Karl R.
• Application Number:
  US13/092,634
• Publication Number:
  US 20110193840A1
• Time in Patent Office: Days
• US Class Current: 345/208
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1676 Electrodes
• CPC Class Codes: G02F 1/1681 having two or more microcells partitioned by walls, e.g. of microcup type
• CPC Class Codes: G02F 2001/1678 characterised by the composition or particle type
• CPC Class Codes: G02F 2201/12 electrode
• CPC Class Codes: G09G 3/34 by control of light from an independent source

Abstract

A dielectrophoretic display has a substrate having walls defining a cavity, the cavity having a viewing surface and a side wall inclined to the viewing surface. A fluid is contained within the cavity; and a plurality of particles are present in the fluid. There is applied to the substrate an electric field effective to cause dielectrophoretic movement of the particles so that the particles occupy only a minor proportion of the viewing surface.

Claims

1. A method for operating a dielectrophoretic display, the method comprising:

providing a dielectrophoretic medium comprising a fluid and a plurality of at least one type of particle within the fluid;

applying to the medium an electric field having a high amplitude, low frequency component and a low amplitude high frequency component, thereby causing the particles to undergo electrophoretic motion and producing a first optical state; and

applying to the medium an electric field having a low amplitude low frequency component and a high amplitude high frequency component, thereby causing the particles to undergo dielectrophoretic motion and producing a second optical state different from the first optical state.

2. A method according to claim 1 wherein the low frequency components have frequencies not greater than about 10 Hz and the high frequency components have frequencies of at least about 100 Hz.

3. A method according to claim 1 wherein the components have substantially the form of square waves or sine waves.

4. A method according to claim 1 wherein the at least one type of particle is formed from an electrically conductive material.

5. A method according to claim 4 wherein the at least one type of particle is formed from a metal or carbon black.

6. A method according to claim 1 wherein the substrate comprises at least one capsule wall so that the dielectrophoretic display comprises at least one capsule.

7. A method according to claim 6 wherein the substrate comprises a plurality of capsules, the capsules being arranged in a single layer.

8. A method according to claim 1 wherein the substrate comprises a continuous phase surrounding a plurality of discrete droplets of the fluid having the at least one type of particle therein.

9. A method according to claim 1 wherein the substrate comprises a substantially rigid material having the at least one cavity formed therein, the substrate further comprising at least one cover member closing the at least one cavity.