Driving methods for variable transmission electro-phoretic media

Patent metadata

Field	Value
Publication number	US-2020004099-A1
Application number	US-201916446845-A
Country	US
Kind code	A1
Filing date	Jun 20, 2019
Priority date	Jun 28, 2018
Publication date	Jan 2, 2020
Grant date	—

Abstract

A method of driving a variable transmission film is provided and a variable transmission device including the film and a controller configured to drive the film. The film may include a layer of electrophoretic material and at least one electrode, the electrophoretic material including a fluid containing a plurality of charged particles capable of moving through the fluid upon application of an electric field by the at least one electrode. The method may include applying a first voltage waveform to the film at an initial optical state and applying a second voltage waveform having a lower frequency and shorter pulse duration than the first voltage waveform to switch the film to a final optical state, wherein the film has a higher percent transmission at the initial optical state than the final optical state.

First claim

We claim:

1 . A method of driving a variable transmission film comprising a layer of electrophoretic material and at least one electrode, the electrophoretic material comprising a fluid containing a plurality of charged particles capable of moving through the fluid upon application of an electric field by the at least one electrode, the method comprising:
applying a first voltage waveform to the film having an initial optical state; and applying a second voltage waveform having a lower frequency and shorter pulse duration than the first voltage waveform to switch the film to a final optical state, wherein the film has a higher percent transmission at the initial optical state than the final optical state.

2 . The method according to claim 1 , wherein the first and second voltage waveforms each have a frequency from 1 to 10 Hz.

3 . The method according to claim 1 , wherein the first voltage waveform has a frequency of 10 Hz.

4 . The method according to claim 1 , wherein the second voltage waveform has a frequency of 2 Hz.

5 . The method according to claim 1 , wherein the first voltage waveform has a greater frequency than the second voltage waveform.

6 . The method according to claim 1 , wherein the first and second voltage waveforms each have an amplitude from 20 to 150 V.

7 . The method according to claim 1 , wherein the first and second voltage waveforms each have an amplitude from 60 to 120 V.

8 . The method according to claim 1 , wherein the first and second voltage waveforms have an amplitude of 90 V.

9 . The method according to claim 1 , wherein the first and second voltage waveform each have a pulse duration less than or equal to 1500 ms.

10 . The method according to claim 1 , wherein the first and second voltage waveform each have a pulse duration less than or equal to 1000 ms.

11 . The method according to claim 1 , wherein the first and second voltage waveform each have a pulse duration less than or equal to 500 ms.

12 . The method according to claim 1 , wherein the percent transmission of the film in the final optical state is less than or equal to 1.5%.

13 . The method according to claim 1 , wherein the electrophoretic material is encapsulated.

14 . A variable transmission device comprising:
at least one electrode; a layer of electrophoretic material comprising a fluid containing a plurality of charged particles capable of moving through the fluid upon application of an electric field by the at least one electrode; a controller connected to a power source and the at least one electrode, the controller being configured to drive the variable transmission film according to the method of claim 1 .

15 . The variable transmission film of claim 14 , wherein the electrophoretic material is encapsulated.

Assignees

• E Ink Corp

Inventors

• Widger Peter Carsten Bailey
• Harris George G
• Paolini Jr Richard J
• Breen Craig Alan

Classifications

• G02F1/167

  by electrophoresis · CPC title

• G02F1/1685 Primary

  Operation of cells; Circuit arrangements affecting the entire cell · CPC title

• G09G3/344

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

• G02F1/16757

  Microcapsules · CPC title