Electrophoretic device, method of driving electrophoretic device, and electronic apparatus

• US 7,679,599 B2
• Filed: 02/16/2006
• Issued: 03/16/2010
• Est. Priority Date: 03/04/2005
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated, Seiko Epson Corporation (Seiko Group)
• Inventors: Kawai, Hideyuki
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Edwards; Carolyn R
• Application Number:
  US11/354,835
• Publication Number:
  US 20060197738A1
• Time in Patent Office: 1,489 Days
• Field of Search: 345/107, 345 98-100, 359/296, 359/297
• US Class Current: 345/107
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/207 by domain size control G09G3/3637 takes precedence
• CPC Class Codes: G09G 3/344 based on particles moving in a fluid or in a gas, e.g. electrophoretic devices electrophoretic devices per se G02F1/167

Abstract

The electrophoretic device of the present invention obtains a plurality of different optical characteristics by changing a proportion of number of pixel electrodes supplied with a first voltage and a number of pixel electrodes supplied with a second voltage. The transition of the optical characteristics accompanied by the changes of the proportion is previously obtained as an actual measurement value. The preferable proportion displaying the desired optical characteristic is calculated based on the actual measurement value.

Claims

1. An electrophoretic device comprising:

an electrophoretic dispersion liquid that includes a liquid dispersion medium and electrophoretic particles;

a plurality of pixel electrodes; and

a voltage supply device that separately supplies a plurality of said pixel electrodes with a first voltage or a second, voltage according to a proportion “

x”

, the proportion “

x”

being a proportion of a number of pixel electrodes supplied with the first voltage and a number of pixel electrodes supplied with the second voltage, wherein

for each of a plurality of values of the proportion “

x”

, a measured value R is obtained by measuring an actual optical characteristic in advance, and

when an image is displayed, a modified proportion “

x”

corresponding to a desired optical characteristic of the image is calculated based on the measured value R and the modified proportion “

x”

is used by the voltage supply device.

2. An electrophoretic device according to claim 1, wherein

based on a function R=f(x) representing the relationship of said proportion “

x” and

the measured value R of said optical characteristic, an inverse function x=f<sup>−

1</sup>(R) is obtained in advance, and when an image is displayed, the modified proportion “

x”

corresponding to the desired optical characteristic is calculated by substituting said desired optical characteristic as a value R by the inverse function x=f<sup>−

1</sup>(R).

3. An electrophoretic device according to claim 1, wherein said electrophoretic particles comprise a plurality of types of particles having different optical characteristics.

4. An electrophoretic device according to claim 1, wherein said electrophoretic dispersion liquid is encapsulated in a microcapsule.

5. An electrophoretic device according to claim 1, wherein said pixel electrodes are arranged in matrix form.

6. An electrophoretic device according to claim 1, having a common electrode, and said pixel electrode and said common electrode are formed on a same substrate.

7. Electronic apparatus comprising the electrophoretic devices according to claim 1.

8. A method of driving an electrophoretic device, said electrophoretic device comprising:

an electrophoretic dispersion liquid that includes a liquid dispersion medium and electrophoretic particles;

a plurality of pixel electrodes; and

a voltage supply device that separately supplies a plurality of said pixel electrodes with a first voltage or a second voltage,

and the method comprising;

when a proportion “

x”

is defined as a proportion of a number of pixel electrodes supplied with the first voltage and a number of pixel electrodes supplied with the second voltage, obtaining a measured value R for each of a plurality of values of the proportion “

x”

, by measuring an actual optical characteristic in advance, and

when displaying an image, calculating a modified proportion “

x”

corresponding to a desired optical characteristic based on said measured value R, and supplying said first voltage or said second voltage from said voltage supply device to a plurality of said pixel electrodes corresponding to said modified proportion “

x”

.

9. A method of driving an electrophoretic device according to claim 8 wherein:

obtaining a function R=f(x) representing the relationship of said proportion “

x” and

the measured value R of said optical characteristic; and

preparing an inverse function x=f<sup>−

1</sup>(R) of the function R=f(x); and

when displaying an image, calculating the modified proportion “

x”

corresponding to a desired optical characteristic R using the inverse function x=f<sup>−

1</sup>(R), and supplying said first voltage or said second voltage from said voltage supply device to said plurality of pixel electrodes according to said calculated modified proportion “

x”

.

10. Electronic apparatus comprising the electrophoretic devices according to claim 8.