Methods for driving electro-optic displays

Patent metadata

Field	Value
Publication number	US-11462183-B2
Application number	US-202117389886-A
Country	US
Kind code	B2
Filing date	Jul 30, 2021
Priority date	Feb 1, 2012
Publication date	Oct 4, 2022
Grant date	Oct 4, 2022

Abstract

A variety of methods for driving electro-optic displays so as to reduce visible artifacts are described. Such methods include (a) applying a first drive scheme to a non-zero minor proportion of the pixels of the display and a second drive scheme to the remaining pixels, the pixels using the first drive scheme being changed at each transition; (b) using two different drive schemes on different groups of pixels so that pixels in differing groups undergoing the same transition will not experience the same waveform; (c) applying either a balanced pulse pair or a top-off pulse to a pixel undergoing a white-to-white transition and lying adjacent a pixel undergoing a visible transition; (d) driving extra pixels where the boundary between a driven and undriven area would otherwise fall along a straight line; and (e) driving a display with both DC balanced and DC imbalanced drive schemes, maintaining an impulse bank value for the DC imbalance and modifying transitions to reduce the impulse bank value.

First claim

The invention claimed is:

1. A controller associated with an electrophoretic display and configured to carry out a driving method for driving the electrophoretic display, the electrophoretic display having a plurality of pixels each of which can be driven using either a first or a second drive scheme, wherein the first drive scheme is a global complete drive scheme, in which a drive voltage is applied to every pixel, is effected by dividing the pixels of the display into at least two groups, and a different drive scheme is used for each group, the drive schemes differing from each other such that, for at least one transition, pixels in differing groups with the same transition between optical states will not experience the same waveform.

2. The controller according to claim 1 wherein at least one of the pixel groupings and the waveforms used are adjusted between successive image updates using the global complete drive scheme.

3. The controller according to claim 1 wherein the pixels are divided into two groups on a checkerboard grid, with pixels of one parity assigned to a first class and the pixels of the other parity assigned to a second class, the pixels undergoing white-to-white transitions being driven by a waveform which drives the pixel black at an intermediate point, the white-to-white waveforms of the two classes being chosen such that they are offset in time such that the two classes are never in a black state at the same time.

4. The controller according to claim 3 wherein the pixels undergoing white-to-white transitions are driven using a balanced pulse pair waveform comprising two rectangular voltage pulses of equal impulse but opposite polarity, and the waveform for one class of pixels is delayed by the duration of a single pulse relative to the other class of pixels.

5. The controller according to claim 1 wherein said at least one transition comprises at least one mid-gray to mid-gray transition, wherein the two mid-gray levels may be same or different, and two different single rail bounce waveforms are used for differing groups of pixels undergoing this transition, one waveform driving the pixel from the mid-gray level to white and back to mid-gray, while the other waveform drives the pixel the mid-gray level to black and then back to mid-gray.

6. The controller according to claim 1 wherein the division of the pixels into classes is arranged so that at least one transitory monochrome image is displayed during the update.

7. The controller according to claim 6 wherein the at least one transitory monochrome image comprises at least one of a monochrome checkerboard, a company logo, a stripe, a clock, a page number or an Escher print.

8. A controller associated with an electrophoretic display and configured to carry out a driving method for driving the electrophoretic display, the electrophoretic display having a plurality of pixels wherein, in a pixel undergoing a white-to-white transition and lying adjacent at least one other pixel undergoing a readily visible transition, there is applied to the pixel one or more balanced pulse pairs, wherein each balanced pulse pair comprises a pair of drive pulses of opposing polarities such that the net impulse of the balanced pulse pair is substantially zero.

9. The controller according to claim 8 wherein the balanced pulse pairs are applied to at least some pixels undergoing a white-to-white transition and having at least one of its eight neighbors undergoing a not-white-to-white transition.

10. The controller according to claim 9 wherein the proportion of pixels to which the balanced pulse pairs are applied in any one transition is limited to a predetermined proportion of the total number of pixels.

11. A controller associated with an electrophoretic display and configured to carry out a driving method for driving the electrophoretic display, the electrophoretic display having a plurality of pixels wherein, in a pixel undergoing a white-to-white transition and lying adjacent at least one other pixel undergoing a readily visible transition, there is applied to the pixel at least one top-off pulse having a polarity which drives the pixel towards its white state.

12. A controller according to claim 11 wherein the at least one top-off pulse is applied to at least some pixels undergoing a white-to-white transition and having at least one of its eight neighbors undergoing a not-white-to-white transition.

13. A controller according to claim 11 wherein the proportion of pixels to which the at least one top-off pulse is applied in any one transition is limited to a predetermined proportion of the total number of pixels.

Assignees

• E Ink Corp

Inventors

• Amundson Karl Raymond
• Aprea Matthew J
• Crounse Kenneth R
• Harrington Demetrious Mark
• Lin Jason
• Sjodin Theodore A
• Su Chia-Chen

Classifications

• G09G2310/068

  Application of pulses of alternating polarity prior to the drive pulse in electrophoretic displays · CPC title

• G09G3/344 Primary

  based on particles moving in a fluid or in a gas, e.g. electrophoretic devices (electrophoretic devices per se G02F1/167) · CPC title

• G09G2310/062

  Waveforms for resetting a plurality of scan lines at a time · CPC title

• G09G2310/06

  Details of flat display driving waveforms · CPC title

• G09G2320/0209

  Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display · CPC title