Patent ID: 6784968
Filing Date: 2004-08-31
Classification: G09G

Abstract:
A method of addressing a bistable nematic device formed by two cell walls enclosing a layer of nematic or long pitch cholesteric liquid crystal material with electrode structures carried by the walls to form a series of row electrodes on one wall and a series of column electrodes on the other wall to form a matrix of intersecting regions or pixels with a wall surface treatment on at least one wall providing a molecular alignment permitting the molecules at or adjacent the wall to align into two different stable states upon application of appropriate unipolar voltage pulses, the method comprising the steps of:applying a row waveform to each row in a sequence whilst simultaneously applying one of two data waveforms to each column electrode whereby each pixel can be independently switched between two bistable states; the row waveform having a period of at least two time slots and at least two unipolar pulses for switching the device to a first state, at least two unipolar pulses for switching the device to a second state; both data waveforms having a period of at least two time slots with a unipolar pulse in each time slot, with at least one data waveform shaped to combine with the row waveform to cause a switching to one latched state; whereby each pixel can be addressed to latch into one of said two stable states to collectively provide a desired display, with a substantially net zero dc voltage applied to the device.