AC Field and Frequency-Controlled Electrooptic Switching Using A Pyrimidine Type Ferroelectric Liquid Crystal

Abstract

Abstract The physical contrast ratios (CRs) of an electrooptic switching element using a pyrimidine type ferroelectric liquid crystal (LC) was investigated. The electrooptic response of the element to the AC square wave voltages was shown to be strongly dependent both on the amplitudes and frequencies of the applied voltages. The CR showed a peak at V = 20 volts and at 500 Hz. This behavior was shown to be fairly well correlated to the voltage and frequency dependence of the apparent cone angle which was observed with a polarizing microscope. The element made of this material showed a bistability depending on the surface treatments and the LC layer thickness. Almost all samples, which did not always have the bistability capability, showed that an AC electric field stabilized bistability even though all the tested LC materials have a small but positive dielectric anisotropy of about 0.2.