METHODS FOR DRIVING ELECTRO-OPTIC DISPLAYS, AND APPARATUS FOR USE THEREIN

• US 20050219184A1
• Filed: 06/24/2005
• Published: 10/06/2005
• Est. Priority Date: 04/30/1999
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: E Ink Holdings Incorporated
• Inventors: Au, Joanna, Knaian, Ara N., Zehner, Robert W., Zalesky, Jonathan L., Gates, Holly G., Arango, Alexi C., Amundson, Karl R.
• Granted Patent: US 7,312,794 B2
• Time in Patent Office: Days
• 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 a plurality of pixels, each of which is capable of displaying at least three gray levels, the 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.

2. A method according to claim 1 further comprising receiving a temperature signal representing the temperature of at least one pixel of the display and generating said output signal dependent upon said temperature signal.

3. A method according to claim 2 wherein said look-up table stores multiple values for each transition from an initial gray level to a final gray level, said multiple values representing the values required for a specific transition at a specific temperature.

4. A method according to claim 3 further comprising interpolating between adjacent values for a transition when the temperature signal indicates a temperature intermediate the temperatures to which said adjacent values relate.

5. A method according to claim 2 wherein said look-up table stores functions of temperature, and wherein said output signal is generated by calculating the value of the relevant function at the temperature indicated by said temperature signal.

6. A method according to claim 1 wherein said output signal represents the period of time for which a substantially constant drive voltage is to be applied to said pixel.

7. A method according to claim 6 wherein said pixel is driven in a scan comprising a plurality of sub-scan periods and said output signal represents determines during which of said sub-scan periods a drive voltage is to be applied to said pixel.

8. A method according to claim 1 wherein said output signal comprises at least one polarity bit representing the polarity of the impulse necessary to convert the initial state of said one pixel to the desired final state thereof.

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

10. A method according to claim 9 wherein the display is an encapsulated electrophoretic display.

11. 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.

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

13. A method of driving an electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, the 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, said output signal representing the period of time for which a substantially constant drive voltage is to be applied to said pixel.

14. A device controller for controlling a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, said controller comprising:

storage means arranged to store both a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level, and data representing at least an initial state of each pixel of the display;

input means for receiving an input signal representing a desired final state of at least one pixel of the display;

calculation means for determining, from the input signal, the stored data representing the initial state of said pixel, and the look-up table, the impulse required to change the initial state of said one pixel to the desired final state; and

output means for generating an output signal representative of said impulse.

15. A controller according to claim 14 wherein said output means generates a signal representing the time for which a substantially constant drive voltage is to be applied to said pixel.

16. A controller according to claim 14 wherein said output signal comprises at least one polarity bit representing the polarity of said impulse.

17. A method of driving a bistable electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, the 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 output signal representing the period of time for which a substantially constant drive voltage is to be applied to said pixel.

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

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

20. A method according to claim 17 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.

21. A method according to claim 17 wherein the display is a passive matrix display.

22. A device controller for controlling an electro-optic display having a plurality of pixels, each of which is capable of displaying at least three gray levels, said controller comprising:

storage means arranged to store both a look-up table containing data representing the impulses necessary to convert an initial gray level to a final gray level, and data representing at least an initial state of each pixel of the display;

input means for receiving an input signal representing a desired final state of at least one pixel of the display;

calculation means for determining, from the input signal, the stored data representing the initial state of said pixel, and the look-up table, the impulse required to change the initial state of said one pixel to the desired final state; and

output means for generating an output signal representative of said impulse, said output signal representing the period of time for which a substantially constant drive voltage is to be applied to said pixel.

23. A driver circuit comprising:

output lines arranged to be connected to drive electrodes of an electro-optic display;

first input means for receiving a plurality of (n+1) bit numbers representing the voltage and

polarity of signals to be placed on the drive electrodes; and

second input means for receiving a clock signal,

the driver circuit being arranged such that, upon receipt of the clock signal, the driver circuit displays the selected voltages on its output lines.