Patent ID: 6894668
Filing Date: 2005-05-17
Classification: G02F,G09G

Abstract:
1. A method of writing pixels in a cholesteric liquid crystal display having opposing rows and columns of electrodes and cholesteric liquid crystal material disposed between said rows and columns of electrodes, the cholesteric liquid crystals having a plurality of reflective states, comprising the steps of: a) in a first preparation step, applying row and column voltage pulses, all pulses having the same minimum voltage and the same maximum voltage with a duty cycle of approximately 50% and adjusting the relative phase of the row and column voltage pulses to provide a bipolar field with a duty cycle varying from 90% to 100% across the cholesteric material and sufficient to produce a field that causes the cholesteric material to be in a homeotropic state; b) in a second holding-selection step, applying row and column voltage pulses and with the same minimum and maximum voltages, adjusting the duty cycles of the row and column voltage pulses to be the same and adjusting the relative phase between the row and column pulses of selected ON pixels to write ON data into the selected ON pixels and adjusting the relative phases of selected OFF pixels to be in phase to write OFF data into the selected OFF pixels; and c) in a third evolution step applying row and column voltage pulses at the same minimum and maximum voltages with substantially the same duty cycle and with different relative phases to cause the pixels to evolve to a written reflective state.