Drive schemes for gray scale bistable cholesteric reflective displays utilizing variable frequency pulses

A method of addressing a bistable cholesteric liquid crystal material having incremental reflectance properties disposed between opposed substrates, wherein one substrate has a first plurality of electrodes deposited thereon facing the other substrate which has a second plurality of electrodes disposed thereon, the intersection of the first and second plurality of electrodes forming a plurality of pixels, the addressing method comprising:

• applying a predetermined number of pulses to the first plurality of electrodes within a set period of time, each said pulse applied to the first electrodes having a different duration drive period within said set period of time;
• applying said predetermined number of pulses to the second plurality of electrodes, which is the same number of pulses as applied to said first plurality of electrodes, within said set period of time, each said pulse applied to the second electrodes also having said different duration drive periods within said set period of time;
• and
• selectively associating one of two amplitude values with at least one of said predetermined number of pulses applied to the electrodes to generate a desired incremental reflectance the each of the pixels, wherein said desired incremental reflectance is determined by which one of said amplitude values is associated with which one of said different duration drive periods.