Transient Dielectric Study of Bistable Reflective Cholesteric Displays and Design of Rapid Drive Scheme

Transient dielectric measurement is used to study the transitions among the planar, focal conic, and homeotropic states of cholesteric liquid crystals. If the initial state is the field-induced homeotropic state, at low bias fields, the liquid crystal transforms to the planar state in a sequence of homeotropic-transient planar-planar; at high bias fields, the liquid crystal transforms to the focal conic state. The homeotropic-transient planar transition is on the order of 1 ms while the homeotropic-focal conic transition is on the order of 100 ms. Large hysteresis is observed in the transitions between the homeotropic and the focal conic state. Based on the rapid homeotropic-transient planar transition and the hysteresis effect in the focal conic-homeotropic transition, we have designed a drive scheme which can address bistable reflective cholesteric displays at the speed of one Line per millisecond.