Patent 8174490 was granted and assigned to E Ink Corporation on May, 2012 by the United States Patent and Trademark Office.
A pixel of an electrophoretic display is driven from one extreme optical state to a second optical state different from the one extreme optical state by applying to the pixel a first drive pulse of one polarity; and thereafter applying to the pixel a second drive pulse of the opposite polarity, the second drive pulse being effective to drive the pixel to the second optical state.