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

• US 20080238867A1
• Filed: 03/15/2008
• Published: 10/02/2008
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Maeda, Hiroshi, Shimodaira, Yasuhiro
• Granted Patent: US 8,237,653 B2
• Time in Patent Office: Days
• US Class Current: 345/107
• CPC Class Codes: G09G 2300/0857 Static memory circuit, e.g. flip-flop
• CPC Class Codes: G09G 2320/0214 with crosstalk due to leakage current of pixel switch in active matrix panels
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• 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

An electrophoretic display device includes a pair of substrates, an electrophoretic element that includes electrophoretic particles and that are held between the pair of substrates, and a display portion formed of a plurality of pixels. The display portion includes pixel electrodes, an opposite electrode, a first control line and a second control line. Each of the pixel electrodes is formed in each of the pixels. The opposite electrode is opposed to the plurality of pixel electrodes through the electrophoretic element. The first control line and the second control line are connected to each of the pixels. Each of the pixels includes a pixel switching element, a memory circuit, and a switch circuit. The memory circuit is connected to the pixel switching element. Switching of the switch circuit is performed by an output signal of the memory circuit to switch between a connected state where the pixel electrode is connected to the first control line and a connected state where the pixel electrode is connected to the second control line.

Claims

1. An electrophoretic display device comprising:

a pair of substrates;

an electrophoretic element that includes electrophoretic particles and that is held between the pair of substrates; and

a display portion formed of a plurality of pixels, wherein

the display portion includes;

pixel electrodes, each of which is formed in each of the pixels;

an opposite electrode that is opposed to the plurality of pixel electrodes through the electrophoretic element;

a first control line that is connected to each of the pixels; and

a second control line that is connected to each of the pixels, and wherein

each of the pixels includes;

a pixel switching element;

a memory circuit that is connected to the pixel switching element; and

a switch circuit, switching of which is performed by an output signal of the memory circuit to switch between a connected state where the pixel electrode is connected to the first control line and a connected state where the pixel electrode is connected to the second control line.

2. The electrophoretic display device according to claim 1, further comprising:

a pixel driving portion that is connected through a scanning line and a data line to each of the pixels, wherein the pixel driving portion supplies image data through the corresponding pixel switching element to each of the memory circuits; and

an electric potential control portion that is connected to both the first control line and the second control line and the opposite electrode, wherein the electric potential control portion supplies an voltage, which is applied to each of the pixel electrodes, through the first control line and the second control line to each of the switch circuits, wherein the electric potential control portion supplies the opposite electrode with a rectangular wave that has more than one cycle and that repeats a first electric potential and a second electric potential corresponding to an electric potential supplied to the first control line and an electric potential supplied to the second control line.

3. The electrophoretic display device according to claim 1, wherein each of the memory circuits includes a first output terminal and a second output terminal that output different signals from each other, wherein each of the switch circuits includes a first transfer gate and a second transfer gate, wherein the first transfer gate is connected between the first control line and the pixel electrode, wherein switching of the first transfer gate is performed by an output of the first output terminal, wherein the second transfer gate is connected between the second control line and the pixel electrode, and wherein switching of the second transfer gate is performed by an output of the second output terminal.

4. The electrophoretic display device according to claim 1, wherein each of the switch circuits includes a first transistor that is connected between the first control line and the pixel electrode and a second transistor that is connected between the second control line and the pixel electrode, wherein one of the first transistor and the second transistor is a P-type transistor and the other transistor is an N-type transistor.

5. The electrophoretic display device according to claim 1, wherein each of the memory circuits includes a first output terminal and a second output terminal that output different signals from each other, wherein each of the switch circuits includes a first transistor formed of an N-type transistor and a second transistor formed of an N-type transistor, wherein the first transistor is connected between the first control line and the pixel electrode, wherein switching of the first transistor is performed by an output of the first output terminal, wherein the second transistor is connected between the second control line and the pixel electrode, and wherein switching of the second transistor is performed by an output of the second output terminal.

6. The electrophoretic display device according to claim 1, wherein each of the memory circuits includes a first output terminal and a second output terminal that output different signals from each other, wherein each of the switch circuits includes a first transistor formed of a P-type transistor and a second transistor formed of a P-type transistor, wherein the first transistor is connected between the first control line and the pixel electrode, wherein switching of the first transistor is performed by an output of the first output terminal, the second transistor is connected between the second control line and the pixel electrode, and wherein the second transistor is performed by an output of the second output terminal.

7. The electrophoretic display device according to claim 1, wherein both the first control line and the second control line are a common line to the plurality of pixels.

20. An electronic apparatus comprising the electrophoretic display device according to claim 1.

8. A method of driving an electrophoretic display device that is provided with a pair of substrates, an electrophoretic element that includes electrophoretic particles and that is held between the pair of substrates, and a display portion formed of a plurality of pixels, wherein the display portion includes pixel electrodes, an opposite electrode, a first control line, and a second control line, wherein each of the pixel electrodes is formed in each of the pixels, wherein the opposite electrode is opposed to the plurality of pixel electrodes through the electrophoretic element, wherein the first control line and the second control line are connected to each of the pixels, wherein each of the pixels includes a pixel switching element, a memory circuit, and a switch circuit, wherein the memory circuit is connected to the pixel switching element, wherein the switch circuit is connected between the memory circuit and the pixel electrode and is connected to the first control line and the second control line, the driving method comprising:

inputting an image signal through the corresponding pixel switching element to each of the memory circuits;

supplying a first electric potential and a second electric potential respectively to the first control line and the second control line;

inputting an electric potential from the first control line or the second control line by operating each of the switch circuits on the basis of an output from the corresponding memory circuit; and

inputting a rectangular wave that has more than one cycle and that repeats the first electric potential and the second electric potential to the opposite electrode.

9. The driving method according to claim 8, wherein

a first image signal is input to the memory circuit of each pixel that displays a first gray scale, and a second image signal is input to the memory circuit of each pixel that displays a second gray scale, wherein

in each pixel that displays the first gray scale, the first control line and the pixel circuit are made into a connected state by operating the switch circuit on the basis of an output from the memory circuit that holds the first image signal, and wherein

in each pixel that displays the second gray scale, the second control line and the pixel electrode are made into a connected state by operating the switch circuit on the basis of an output from the memory circuit that holds the second image signal.

10. The driving method according to claim 9, wherein

each of the switch circuit includes a first transfer gate that is connected between the first control line and the pixel electrode and a second transfer gate that is connected between the second control line and the pixel electrode, wherein

the first control line and each of the pixel electrodes are made into a connected state by switching the corresponding first transfer gate to an on state using a low level signal output from a first output terminal of the corresponding memory circuit and a high level signal output from a second output terminal of the corresponding memory circuit, and wherein

the second control line and each of the pixel electrodes are made into a connected state by switching the corresponding second transfer gate to an on state using a high level signal output from the first output terminal and a low level signal output from the second output terminal.

11. The driving method according to claim 9, wherein

each of the switch circuits includes a first transistor, formed of a P-type transistor, that is connected between the first control line and the pixel electrode and a second transistor, formed of an N-type transistor, that is connected between the second control line and the pixel electrode, wherein

the first control line and each of the pixel electrodes are made into a connected state by switching the corresponding first transistor to an on state using a low level signal output from the corresponding memory circuit, and wherein

the second control line and each of the pixel electrodes are made into a connected state by switching the corresponding second transistor to an on state using a high level output from the corresponding memory circuit.

12. The driving method according to claim 9, wherein

each of the switch circuits includes a first transistor and a second transistor, both of which are formed of an N-type transistor, wherein

the first control line is connected through the corresponding first transistor to each of the pixel electrodes and the second control line is connected through the corresponding second transistor to each of the pixel electrodes, wherein

the first control line and each of the pixel electrodes are made into a connected state by switching the corresponding first transistor to an on state using a high level signal output from a first output terminal of the corresponding memory circuit, and wherein

the second control line and each of the pixel electrodes are made into a connected state by switching the corresponding second transistor to an on state using a high level signal output from a second output terminal of the corresponding memory circuit.

13. The driving method according to claim 9, wherein

the switch circuit includes a first transistor and a second transistor, both of which are formed of a P-type transistor, wherein

the first control line is connected through the corresponding first transistor to each of the pixel electrodes and the second control line is connected through the corresponding second transistor to each of the pixel electrodes, wherein

the first control line and each of the pixel electrodes are made into a connected state by switching the corresponding first transistor to an on state using a low level signal output from a first output terminal of the corresponding memory circuit, and wherein

the second control line and each of the pixel electrodes are made into a connected state by switching the corresponding second transistor to an on state using a low level signal output from a second output terminal of the corresponding memory circuit.

14. The driving method according to claim 9, wherein all the pixels are made to have the same gray scale by supplying signals having the same electric potential to the first control line and the second control line.

15. The driving method according to claim 9, wherein

the first control line is made into a high impedance state where the first control line is electrically disconnected and the second control line is supplied with the second electric potential to thereby change at least portion of the pixels of the display portion from the first gray scale to the second gray scale, and wherein

the first control line is supplied with the first electric potential and the second control line is made into a high impedance state where the second control line is electrically disconnected to thereby change at least portion of the pixels of the display portion from the second gray scale to the first gray scale.

16. The driving method according to claim 15, wherein a display image is updated by repeating the operation in which the at least portion of the pixels of the display portion are changed from the first gray scale to the second gray scale and the operation in which the at least portion of the pixels of the display portion are changed from the second gray scale to the first gray scale.

17. The driving method according to claim 15, wherein

between the operation in which the at least portion of the pixels of the display portion are changed from the first gray scale to the second gray scale and the operation in which the at least portion of the pixels of the display portion are changed from the second gray scale to the first gray scale, the first control line and the second control line are made into a high impedance state where the first control line and the second control line are electrically disconnected.

18. The driving method according to claim 9, wherein

after the rectangular wave that repeats the first electric potential and the second electric potential and that has more than one cycle has been input to the opposite electrode, each of the memory circuits, each of the switch circuits and the opposite electrode are made into a high impedance state where each of the memory circuits, each of the switch circuits and the opposite electrode are electrically disconnected.

19. An electrophoretic display device comprising a control portion that executes the driving method according to claim 8.