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

• US 7,688,297 B2
• Filed: 02/27/2006
• Issued: 03/30/2010
• Est. Priority Date: 04/30/1999
• Status: Expired due to Fees

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Knaian, Ara N., Zehner, Robert W., Au, Joanna F., Zalesky, Jonathan L., Gates, Holly G., Arango, Alexi C., Amundson, Karl R.
• Primary Examiner(s): Shalwala; Bipin
• Assistant Examiner(s): KOVALICK, VINCENT E
• Application Number:
  US11/307,887
• Publication Number:
  US 20060139311A1
• Time in Patent Office: 1,492 Days
• Field of Search: 345/36, 345/48, 345/63, 345/89, 345/204, 345/210, 345/690
• US Class Current: 345/89
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• 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 2310/0286 Details of a shift registers arranged for use in a driving circuit
• 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 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat 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 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• 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 3/2011 : by amplitude modulation
• CPC Class Codes: G09G 3/2018 : by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2081 : with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• 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 5/10 : Intensity circuits
• CPC Class Codes: G09G 5/18 : Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12

Abstract

A bistable electro-optic display has a plurality of pixels, each of which is capable of displaying at least three gray levels. The display is driven by a method comprising: storing a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level; storing data representing at least an initial state of each pixel of the display; receiving an input signal representing a desired final state of at least one pixel of the display; and generating an output signal representing the impulse necessary to convert the initial state of said one pixel to the desired final state thereof, as determined from said look-up table. The invention also provides a method for reducing the remnant voltage of an electro-optic display.

Claims

1. A method of driving a bistable electro-optic display having at least one pixel with two extreme optical states, the method comprising:

(a) driving the pixel from an initial gray level to one extreme optical state different from the initial gray level; and

(b) driving the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

wherein the display comprises a plurality of pixels divided into first and second groups, and wherein, in step (a), the first group of pixels are driven to one extreme optical state and the second group of pixels are driven to the opposed extreme optical state.

2. A method according to claim 1 wherein step (b) is effected by driving the pixel from the one extreme optical state to the opposed extreme optical state and thereafter driving the pixel to the final gray level.

3. A method according to claim 1 wherein step (b) is effected by driving the pixel from the one extreme optical state to the opposed extreme optical state, thereafter driving the pixel back to the one extreme optical state and thereafter driving the pixel to the final gray level.

4. A method according to claim 1 wherein the display is an electrophoretic display.

5. A method according to claim 4 wherein the display is an encapsulated electrophoretic display.

6. A method according to claim 1 wherein the display is a microcell display comprising charged particles and a suspending fluid retained within a plurality of cavities formed in a carrier medium.

7. A method according to claim 1 wherein the display is a passive matrix display.

8. A method of driving a bistable electro-optic display having at least one pixel with two extreme optical states, the method comprising:

(a) driving the pixel from an initial gray level to one extreme optical state different from the initial gray level; and

(b) driving the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

wherein the pixel has at least four gray levels, namely a white extreme optical state, a light gray optical state, a dark gray optical state darker than the light gray optical state, and a black extreme optical state, and wherein step (b) is carried out such that, when the final gray level is a light or dark gray optical state, the last drive pulse to a specific gray level is always in the same direction.

9. A method according to claim 8 wherein the display comprises a plurality of pixels divided into first and second groups, and wherein step (b) is carried out such that, when the final gray level is a light or dark gray optical state, the last drive pulse to a specific gray level is in opposite directions for the first and second groups of pixels.

10. A method according to claim 8 wherein the last drive pulse to the dark gray level has a polarity which tends to drive the pixel from its black to its white extreme optical state, while the last drive pulse to the light gray level has a polarity which tends to drive the pixel from its white to its black extreme optical state.

11. A method according to claim 8 wherein the last drive pulse to the dark gray level has a polarity which tends to drive the pixel from its white to its black extreme optical state, while the last drive pulse to the light gray level has a polarity which tends to drive the pixel from its black to its white extreme optical state.

12. A method according to claim 8 wherein the display is an electrophoretic display.

13. A method according to claim 12 wherein the display is an encapsulated electrophoretic display.

14. A method according to claim 8 wherein the display is a microcell display comprising charged particles and a suspending fluid retained within a plurality of cavities formed in a carrier medium.

15. A method of driving a bistable electro-optic display having at least one pixel with two extreme optical states, the method comprising:

(a) driving the pixel from an initial gray level to one extreme optical state different from the initial gray level; and

(b) driving the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

wherein the drive pulses are arranged so that, once the pixel has been driven from one extreme optical state towards the opposed extreme optical state by a pulse of one polarity, the pixel does not receive a drive pulse of the opposite polarity until it has reached the opposed extreme optical state.

16. A method according to claim 15 wherein the display is an electrophoretic display.

17. A method according to claim 16 wherein the display is an encapsulated electrophoretic display.

18. A method according to claim 15 wherein the display is a microcell display comprising charged particles and a suspending fluid retained within a plurality of cavities formed in a carrier medium.

19. A method of driving a bistable electro-optic display having at least one pixel with two extreme optical states, the method comprising:

(a) driving the pixel from an initial gray level to one extreme optical state different from the initial gray level; and

(b) driving the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

wherein the drive pulses are arranged so that, for any sequence of transitions of the pixel beginning and ending in one extreme optical state, the algebraic sum of the currents passed through the pixel is essentially zero.

20. A method according to claim 19 wherein the display is an electrophoretic display.

21. A method according to claim 20 wherein the display is an encapsulated electrophoretic display.

22. A method according to claim 19 wherein the display is a microcell display comprising charged particles and a suspending fluid retained within a plurality of cavities formed in a carrier medium.

23. A bistable electro-optic display having at least one pixel with two extreme optical states, and a display controller for applying electric field to the pixel and thereby changing the optical state thereof from an initial gray level to a final gray level, the display controller being arranged to:

(a) drive the pixel from the initial gray level to one extreme optical state different from the initial gray level; and

(b) drive the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

the display comprising a plurality of pixels divided into first and second groups, and wherein the display controller is arranged to effect (a) by driving the first group of pixels to one extreme optical state and the second group of pixels to the opposed extreme optical state.

24. A display according to claim 23 wherein the display controller is arranged to effect (b) by driving the pixel from the one extreme optical state to the opposed extreme optical state and thereafter driving the pixel to the final gray level.

25. A display according to claim 24 wherein the display controller is arranged to effect (b) by driving the pixel from the one extreme optical state to the opposed extreme optical state, thereafter driving the pixel back to the one extreme optical state and thereafter driving the pixel to the final gray level.

26. A display according to claim 23 which is an electrophoretic display.

27. A display according to claim 26 which is an encapsulated electrophoretic display.

28. A display according to claim 23 which is a microcell display comprising charged particles and a suspending fluid retained within a plurality of cavities formed in a carrier medium.

29. A display according to claim 23 which is a passive matrix display.

30. A bistable electro-optic display having at least one pixel with two extreme optical states, and a display controller for applying electric field to the pixel and thereby changing the optical state thereof from an initial gray level to a final gray level, the display controller being arranged to:

(a) drive the pixel from the initial gray level to one extreme optical state different from the initial gray level; and

(b) drive the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

wherein the pixel has at least four gray levels, namely a white extreme optical state, a light gray optical state, a dark gray optical state darker than the light gray optical state, and a black extreme optical state, and wherein the display controller is arranged to carry out (b) such that, when the final gray level is a light or dark gray optical state, the last drive pulse to a specific gray level is always in the same direction.

31. A display according to claim 30 comprising a plurality of pixels divided into first and second groups, and wherein the display controller is arranged to carry out (b) such that, when the final gray level is a light or dark gray optical state, the last drive pulse to a specific gray level is in opposite directions for the first and second groups of pixels.

32. A display according to claim 30 wherein the display controller is arranged to provide a last drive pulse to the dark gray level with a polarity which tends to drive the pixel from its black to its white extreme optical state, and to provide a last drive pulse to the light gray level with a polarity which tends to drive the pixel from its white to its black extreme optical state.

33. A display according to claim 30 wherein the display controller is arranged to provide a last drive pulse to the dark gray level with a polarity which tends to drive the pixel from its white to its black extreme optical state, and to provide a last drive pulse to the light gray level with a polarity which tends to drive the pixel from its black to its white extreme optical state.

34. A display according to claim 30 which is an electrophoretic display.

35. A display according to claim 34 which is an encapsulated electrophoretic display.

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

37. A bistable electro-optic display having at least one pixel with two extreme optical states, and a display controller for applying electric field to the pixel and thereby changing the optical state thereof from an initial gray level to a final gray level, the display controller being arranged to:

(a) drive the pixel from the initial gray level to one extreme optical state different from the initial gray level; and

(b) drive the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

wherein the display controller is arranged to provide drive pulses such that, once the pixel has been driven from one extreme optical state towards the opposed extreme optical state by a pulse of one polarity, the pixel does not receive a drive pulse of the opposite polarity until it has reached the opposed extreme optical state.

38. A display according to claim 37 which is an electrophoretic display.

39. A display according to claim 38 which is an encapsulated electrophoretic display.

40. A display according to claim 37 which is a microcell display comprising charged particles and a suspending fluid retained within a plurality of cavities formed in a carrier medium.

41. A bistable electro-optic display having at least one pixel with two extreme optical states, and a display controller for applying electric field to the pixel and thereby changing the optical state thereof from an initial gray level to a final gray level, the display controller being arranged to:

(a) drive the pixel from the initial gray level to one extreme optical state different from the initial gray level; and

(b) drive the pixel from the one extreme optical state to a final gray level different from the one extreme optical state,

wherein the display controller is arranged to provide drive pulses such that, for any sequence of transitions of the pixel beginning and ending in one extreme optical state, the algebraic sum of the currents passed through the pixel is essentially zero.

42. A display according to claim 41 which is an electrophoretic display.

43. A display according to claim 42 which is an encapsulated electrophoretic display.

44. A display according to claim 41 which is a microcell display comprising charged particles and a suspending fluid retained within a plurality of cavities formed in a carrier medium.