Methods for driving electro-optic displays

Abstract

Methods for driving electro-optic displays, especially bistable displays, include (a) using two-part waveforms, the first part of which is dependent only upon the initial state of the relevant pixel; (b) measuring the response of each individual pixel and storing for each pixel data indicating which of a set of standard drive schemes are to be used for that pixel; (c) for at least one transition in a drive scheme, applying multiple different waveforms to pixels on a random basis; and (d) when updating a limited area of the display, driving “extra” pixels in an edge elimination region to avoid edge effects.

1 . A method of driving an electro-optic display having a plurality of pixels using a drive scheme which defines the waveform to be applied to each pixel for each transition from an initial gray level to final gray level, and wherein, for at least one transition in the drive scheme, multiple waveforms are provided in the drive scheme, and these multiple waveforms are applied to pixels undergoing the relevant transition on a random basis, so that different pixels undergoing the same transition experience different waveforms. 
     
     
         2 . A method according to  claim 1  further comprising the step of changing, at intervals, which of the multiple waveform is used for which said at least one transition at a particular pixel. 
     
     
         3 . A method according to  claim 1  further comprising tracking the DC imbalance at each pixel and making the selection from among the multiple waveforms to reduce the accumulated DC imbalance. 
     
     
         4 . A method according to  claim 1  wherein multiple waveforms are provided for each transition in the drive scheme, and any specific pixel uses the same waveform for each transition. 
     
     
         5 . A method according to  claim 1  wherein the selection from among the multiple waveforms is made so that a fixed image is always or intermittently visible in the background of the display.