Methods for driving electrophoretic displays using dielectrophoretic forces

• US 7,999,787 B2
• Filed: 08/31/2005
• Issued: 08/16/2011
• Est. Priority Date: 07/20/1995
• Status: Expired due to Fees

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Inventors: Jacobson, Joseph M., Paolini, Richard J. Jr., McCreary, Michael D., Whitesides, Thomas H., Arango, Alexi C., Amundson, Karl R.
• Primary Examiner(s): Lefkowitz; Sumati
• Assistant Examiner(s): PHAM, TAMMY T
• Application Number:
  US11/162,188
• Publication Number:
  US 20060038772A1
• Time in Patent Office: 2,176 Days
• Field of Search: None
• US Class Current: 345/108
• 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 first frequency, thereby causing the particles to undergo electrophoretic motion and producing a first optical state; and

applying to the medium an electric field having a second frequency higher than the first frequency, thereby causing the particles to undergo dielectrophoretic motion and producing a second optical state different from the first optical state,

wherein the second frequency electric field has a larger magnitude than the first frequency electric field.

2. A method according to claim 1 wherein the dielectrophoretic medium comprises a single type of electrically charged particle in a fluid.

3. A method according to claim 1 wherein the dielectrophoretic medium comprises two different types of electrically charged particles is a fluid, the two different types of particles bearing charges of opposite polarity.

4. A method according to claim 1 wherein the dielectrophoretic medium comprises a continuous phase surrounding a plurality of droplets of the fluid.