Reverse driving pulses in electrophoretic displays

Patent metadata

Field	Value
Publication number	US-9697778-B2
Application number	US-201414277107-A
Country	US
Kind code	B2
Filing date	May 14, 2014
Priority date	May 14, 2013
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

An electrophoretic medium comprises a fluid and at least one species of particles disposed, When a first addressing impulse is applied to the medium, the first species of particles move in one direction relative to the electric field, but when a second addressing impulse, larger than the first addressing impulse, is applied to the medium, the first species of particles move in the opposed direction relative to the electric field.

First claim

The invention claimed is:

1. A method of driving an electrophoretic medium comprising a fluid and at least a first species of particles disposed in the fluid, the method comprising:
(a) applying a first addressing impulse to the medium, thereby causing the first species of particles to move in one direction relative to the electric field; and
(b) applying a second addressing impulse, larger than the first addressing impulse but having the same polarity, to the medium, thereby causing the first species of particles to move in the opposed direction relative to the electric field;
wherein the electrophoretic medium comprises second and third species of particles having colors different from the first species of particles and from each other, the second and third species of particles bearing charges of opposite polarities and the first species of particles bearing a charge of the same polarity as the third species of particles, the method comprising:
(a) applying the first addressing impulse in one direction, thereby causing one surface of the electrophoretic medium displays the color of the third species of particle;
(b) applying first addressing impulse in the opposed direction, thereby causing said one surface of the display to display a mixture of the colors of the first and second particles;
(c) applying the second addressing impulse in said one direction, thereby causing said one surface to display a mixture of the colors of the first and third particles; and
(d) applying the second addressing impulse in the opposed direction, thereby causing said one surface to display the color of the second particles.

2. The method according to claim 1 wherein the fluid is colored and the electrophoretic medium comprises a second species of particles having a color different from the first species of particles, and wherein the second species of particles move in the same direction relative to the electric field under both the first and second addressing impulses.

3. The method according to claim 1 further comprising applying to the medium a third addressing impulse greater than the second addressing impulse, thereby causing the first, second and third particles all to travel in the same direction relative to the electric field.

4. The method according to claim 1 wherein step (b) is effected by applying to electrophoretic medium a waveform comprising a series of short voltage pulses of one polarity, each except the last of the short voltage pulses being followed by a longer voltage pulse of the opposite polarity.

Assignees

• E Ink Corp

Inventors

• Telfer Stephen J
• Bull Stephen
• Bouchard Alain
• Herb Craig A
• Ladavac Kosta
• Lattes Ana L
• Morrison Jennifer M
• Paolini Jr Richard J
• Regan Michael Thomas
• Slominski Luke M
• Yezek Lee
• Crounse Kenneth R
• Kruse J Ryan
• Hoogeboom Christopher L
• Feick Jason D
• Miller David Darrell

Classifications

• G09G2310/068

  Application of pulses of alternating polarity prior to the drive pulse in electrophoretic displays · CPC title

• G02F2001/1678

  characterised by the composition or particle type · CPC title

• G02F1/167

  by electrophoresis · CPC title

• G09G2310/06

  Details of flat display driving waveforms · CPC title

• G09G3/344 Primary

  based on particles moving in a fluid or in a gas, e.g. electrophoretic devices (electrophoretic devices per se G02F1/167) · CPC title