Methods for driving electro-optic displays, and apparatus for use therein

• US 7,193,625 B2
• Filed: 05/23/2003
• Issued: 03/20/2007
• Est. Priority Date: 04/30/1999
• Status: Expired due to Term

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Inventors: Danner, Guy M., Arango, Alexi C., Amundson, Karl R., Zehner, Robert W., Ewing, Jay Britton
• Primary Examiner(s): Shalwala; Bipin
• Assistant Examiner(s): Kovalick; Vincent E.
• Application Number:
  US10/249,973
• Publication Number:
  US 20050270261A1
• Time in Patent Office: 1,397 Days
• Field of Search: 345/30, 345/84, 345/87, 345/89, 345/210, 345/214, 349/10, 349/24, 349/33, 349/34, 349/85, 349/168, 349/175, 359/296
• US Class Current: 345/214
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/02 Addressing, scanning or driving the display screen or processing steps related thereto
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 2310/068 Application of pulses of alternating polarity prior to the drive pulse in electrophoretic displays
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 2320/0214 with crosstalk due to leakage current of pixel switch in active matrix panels
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/2007 Display of intermediate tones
• CPC Class Codes: G09G 3/2011 : by amplitude modulation
• CPC Class Codes: G09G 3/2014 : by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2018 : by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2074 : using sub-pixels
• CPC Class Codes: G09G 3/2077 : by a combination of two or more gradation control methods
• 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
• CPC Class Codes: G09G 3/3453 : based on rotating particles or microelements

Abstract

A method for addressing a bistable electro-optic display having at least one pixel comprises applying an addressing pulse to drive the pixel to a first optical state; leaving the pixel undriven for a period of time, thereby permitting the pixel to assume a second optical state different from the first optical state; and applying to the pixel a refresh pulse which substantially restores the pixel to the first optical state, the refresh pulse being short relative to the addressing pulse.

Claims

1. A method for addressing a bistable electro-optic display having at least one pixel, the method comprising:

applying an addressing pulse to drive the pixel to a first optical state;

leaving the pixel undriven for a period of time, thereby permitting the pixel to assume a second optical state different from the first optical state; and

applying to the pixel a refresh pulse which substantially restores the pixel to the first optical state, the refresh pulse being short relative to the addressing pulse.

2. A method according to claim 1 wherein the refresh pulse has an impulse not greater than about 20 per cent of the impulse of the addressing pulse.

3. A method according to claim 2 wherein the refresh pulse has an impulse not greater than about 10 per cent of the impulse of the addressing pulse.

4. A method according to claim 3 wherein the refresh pulse has an impulse not greater than about 5 per cent of the impulse of the addressing pulse.

5. A method according to claim 1 wherein the difference between the first and second optical states does not exceed about 1 unit of L*.

6. A method according to claim 5 wherein the difference between the first and second optical states does not exceed about 0.5 unit of L*.

7. A method according to claim 6 wherein the difference between the first and second optical states does not exceed about 0.2 unit of L*.

8. A method according to claim 1 wherein a plurality of refresh pulses are applied to the pixel at regular intervals.

9. A method according to claim 1 in which the display is a rotating bichromal member or electrochromic display.

10. A method according to claim 1 in which the display is an electrophoretic display.

11. A method according to claim 10 in which the display is an encapsulated electrophoretic display.

12. A method according to claim 10 in which the display is a polymer-dispersed electrophoretic display comprising a plurality of discrete droplets of an electrophoretic fluid within a continuous phase of a polymeric material.

13. A method according to claim 10 in which the display is a microcell electrophoretic display comprising charged particles and a fluid retained within a plurality of cavities formed in a carrier medium.

14. A method for addressing a bistable electro-optic display having at least one pixel, the method comprising:

applying an addressing pulse to drive the pixel to a first optical state;

leaving the pixel undriven for a period of time, thereby permitting the pixel to assume a second optical state different from the first optical state;

applying to the pixel a refresh pulse which substantially restores the pixel to the first optical state, the refresh pulse being short relative to the addressing pulse, and

after application of the refresh pulse, applying to the display a second addressing pulse which drives the pixel to a third optical state different from the first and second optical states, the impulse applied by the second addressing pulse being the sum of (a) the impulse needed to drive the pixel from the first to the third optical state; and

(b) an impulse equal in magnitude but opposite in polarity to the algebraic sum of the refresh pulses applied to the pixel between the first and second addressing pulses.

15. A method according to claim 14 wherein the second addressing pulse is of constant voltage but variable duration.

16. A method according to claim 14 wherein the display comprises a plurality of pixels and the second addressing pulse comprises a blanking pulse which drives all the pixels of the display to one extreme optical state.

17. A method according to claim 14 in which the display is a rotating bichromal member or electrochromic display.

18. A method according to claim 14 in which the display is an electrophoretic display.

19. A method according to claim 18 in which the display is an encapsulated electrophoretic display.

20. A method according to claim 18 in which the display is a polymer-dispersed electrophoretic display comprising a plurality of discrete droplets of an electrophoretic fluid within a continuous phase of a polymeric material.

21. A method according to claim 18 in which the display is a microcell electrophoretic display comprising charged particles and a fluid retained within a plurality of cavities formed in a carrier medium.

22. A method for addressing a bistable electro-optic display comprising a plurality of pixels, the method comprising:

applying an addressing pulse to each pixel so as to drive a first group of pixels white and a second group of pixels black;

leaving the first and second groups of pixels undriven for a period of time, thereby permitting the first and second groups of pixels to assume optical states different from their white and black optical states;

applying at least one refresh pulse to each pixel, thereby substantially restoring the first and second groups of pixels to their white and black optical states respectively; and

thereafter applying to the display a first blanking pulse which turns all the pixels black and a second blanking pulse which drives all the pixels white, the two blanking pulses being applied in either order, the impulse applied to each of the first group of pixels during the first blanking pulse being the sum of (a) the impulse needed to drive the pixel from white to black; and

(b) an impulse equal in magnitude but opposite in polarity to the algebraic sum of the refresh pulses applied to the pixel between the addressing pulse and the first blanking pulse, and the impulse applied to each of the second group of pixels during the second blanking pulse being the sum of (c) the impulse needed to drive the pixel from black to white; and

(d) an impulse equal in magnitude but opposite in polarity to the algebraic sum of the refresh pulses applied to the pixel between the addressing pulse and the first blanking pulse.

23. A method according to claim 22 in which the display is a rotating bichromal member or electrochromic display.

24. A method according to claim 22 in which the display is an electrophoretic display.

25. A method according to claim 24 in which the display is an encapsulated electrophoretic display.

26. A method according to claim 24 in which the display is a polymer-dispersed electrophoretic display comprising a plurality of discrete droplets of an electrophoretic fluid within a continuous phase of a polymeric material.

27. A method according to claim 24 in which the display is a microcell electrophoretic display comprising charged particles and a fluid retained within a plurality of cavities formed in a carrier medium.

28. A method for addressing a bistable electro-optic display comprising a plurality of pixels, the method comprising:

applying an addressing pulse to each pixel so as to drive a first group of pixels white and a second group of pixels black;

leaving the first and second groups of pixels undriven for a period of time, thereby permitting the first and second groups of pixels to assume optical states different from their white and black optical states;

applying a first refresh pulse having one polarity to the first group of pixels thereby substantially restoring the first group of pixels to the white optical state, the first refresh pulse being short relative to the addressing pulse; and

applying a second refresh pulse having a polarity opposed to said one polarity to the second group of pixels thereby substantially restoring the second group of pixels to the black optical state, the second refresh pulse being short relative to the addressing pulse.

29. A method according to claim 28 in which the display is a rotating bichromal member or electrochromic display.

30. A method according to claim 28 in which the display is an electrophoretic display.

31. A method according to claim 30 in which the display is an encapsulated electrophoretic display.

32. A method according to claim 30 in which the display is a polymer-dispersed electrophoretic display comprising a plurality of discrete droplets of an electrophoretic fluid within a continuous phase of a polymeric material.

33. A method according to claim 30 in which the display is a microcell electrophoretic display comprising charged particles and a fluid retained within a plurality of cavities formed in a carrier medium.