METHODS FOR DRIVING ELECTRO-OPTIC DISPLAYS
An electro-optic display, having at least one pixel capable of achieving any one of at least four different gray levels including two extreme optical states, is driven by displaying a first image on the display, and rewriting the display to display a second image thereon, wherein, during the rewriting of the display, any pixel which has undergone a number of transitions exceeding a predetermined value without touching an extreme optical state, is driven to at least one extreme optical state before driving that pixel to its final optical state in the second image.
1 . A method for driving an electro-optic display having a plurality of pixels, the pixels being driven with a pulse width modulated waveform capable of applying a plurality of differing impulses to each pixel, the method comprising:
(a) storing data indicating whether application of a given impulse to a pixel will produce a gray level higher or lower than a desired gray level;
(b) detecting when two adjacent pixels are both required to be in the same gray level; and
(c) adjusting the impulses applied to the two pixels so that one pixel is below the desired gray level, while the other pixel is above the desired gray level.
2 . A method according to claim 1 wherein the pixels are divided into two groups such that each pixel has at least one neighbor of the opposite group, and different drive schemes are used for the two groups.
3 . A method according to claim 1 wherein the electro-optic display comprises an electrochromic or rotating bichromal member electro-optic medium.
4 . A method according to claim 1 wherein the electro-optic display comprises an encapsulated electrophoretic medium.
5 . A method according to claim 4 wherein the electro-optic display comprises a microcell electrophoretic medium.