Driving methods for variable transmission electro-phoretic media

Patent metadata

Field	Value
Publication number	US-11143930-B2
Application number	US-201916446845-A
Country	US
Kind code	B2
Filing date	Jun 20, 2019
Priority date	Jun 28, 2018
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

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 disposed between two light-transmissive electrodes, the electrophoretic material comprising a fluid containing a plurality of charged particles capable of moving through the fluid upon application of an electric field between the two light-transmissive electrodes, the method comprising:
applying a first voltage waveform having a frequency from 1 to 10 Hz 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, the frequency of the second voltage waveform being 1 Hz or greater,
wherein the variable transmission film has a higher percent transmission at the initial optical state than the final optical state, when viewed through the variable transmission film.

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

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

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

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

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

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

8. 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.

9. 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.

10. 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.

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

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

13. A variable transmission device comprising:
two light-transmissive electrodes;
a layer of electrophoretic material disposed between the two light-transmissive electrodes, the electrophoretic material comprising a fluid containing a plurality of charged particles capable of moving through the fluid upon application of an electric field between the two light-transmissive electrodes;
a controller connected to a power source and the two light-transmissive electrodes, the controller being configured to drive the variable transmission film according to the method of claim 1 .

14. The variable transmission device of claim 13 , wherein the electrophoretic material is encapsulated.

15. The variable transmission device of claim 13 , further comprising a light-transmissive substrate.

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

• G02F1/16757

  Microcapsules · 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