Patent ID: 6320563
Filing Date: 2001-11-20
Classification: G09G

Abstract:
A method of addressing a dual frequency bistable cholesteric liquid crystal material having liquid crystal domains disposed between opposed substrates, wherein one of the substrates has a first plurality of electrodes facing a second plurality of electrodes on the other substrate, and wherein the intersection of the first and the second plurality of electrodes forms a plurality of pixels, the method comprising the steps of:selectively applying high and low frequency voltages to said plurality of pixels, wherein the high frequency voltage drives the material to exhibit one texture so that the liquid crystal domains have a reflectance at one extreme and the low frequency voltage drives the material to exhibit another texture so that the liquid crystal domains have a reflectance at another extreme, wherein the liquid crystal domains are stable after removal of the voltages;adjusting a voltage amplitude value for each said high and low frequency to obtain a desired reflectance which can be at either extreme or somewhere between the two extremes, wherein said desired reflectance is made up of pixels, each said pixel having a first portion of liquid crystal domains at one extreme and another portion of liquid crystal domains at the other extreme; andcumulatively adjusting the desired reflectance by simultaneously applying said high and low frequency voltages in multiple pulses such that switching of the liquid crystal domains is accomplished cumulatively so that the amplitude or the duration of the pulses, or both can be reduced.