Methods and apparatus for driving electro-optic displays
First Claim
1. A method for driving an electro-optic display having a plurality of pixels each capable of achieving at least four different gray levels including two extreme optical states, the method comprising applying to each pixel capable of achieving at least four different gray levels a waveform comprising a reset pulse sufficient to drive the pixel to or close to one of its extreme optical states followed by a set pulse sufficient to drive the pixel to a final gray level different from said one extreme optical state, wherein the reset pulses are chosen such that the image on the display immediately prior to the set pulses is substantially an inverse monochrome projection of the final image following the set pulses, and wherein the set pulse applied to at least one pixel causes that pixel to assume a final gray level different from both extreme optical states of that pixel.
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Abstract
Waveforms for driving electro-optic displays, especially bistable electro-optic displays, are modified by one or more of insertion of at least one balanced pulse pair into a base waveform; excision of at least one balanced pulse pair from the base waveform; and insertion of at least one period of zero voltage into the base waveform. Such modifications permit fine control of gray levels.
398 Citations
26 Claims
- 1. A method for driving an electro-optic display having a plurality of pixels each capable of achieving at least four different gray levels including two extreme optical states, the method comprising applying to each pixel capable of achieving at least four different gray levels a waveform comprising a reset pulse sufficient to drive the pixel to or close to one of its extreme optical states followed by a set pulse sufficient to drive the pixel to a final gray level different from said one extreme optical state, wherein the reset pulses are chosen such that the image on the display immediately prior to the set pulses is substantially an inverse monochrome projection of the final image following the set pulses, and wherein the set pulse applied to at least one pixel causes that pixel to assume a final gray level different from both extreme optical states of that pixel.
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13. A method for driving an electro-optic display having at least one pixel capable of achieving at least two different gray levels, the method comprising, in order:
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bringing the pixel to a first gray level; allowing the pixel to remain at the first gray level for a first dwell time less than a predetermined interval; driving the pixel to a second gray level using a first waveform; returning the pixel to the first gray level; allowing the pixel to remain at the first gray level for a second dwell time greater than the predetermined interval; driving the pixel to the second gray level using a second waveform, wherein the first and second waveforms differ from each other by at least one of the following; (a) insertion of at least one balanced pulse pair; and (b) excision of at least one balanced pulse pair; where “
balanced pulse pair”
denotes a sequence of two pulses of opposite polarity such that the total impulse of the balanced pulse pair is essentially zero,and wherein, following the excision of the at least one balanced pulse pair, other elements of the base waveform are shifted in time to occupy the period formerly occupied by the or each excised balanced pulse pair, and a period of zero voltage is inserted at a point in time different from that occupied by the or each excised balanced pulse pair. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification