Inducing Cholesteric-Texture Changes by Means of Two-Frequency Addressable Liquid Crystal Material

Abstract

Cholesteric material of suitable pitch can show brillant reflection colours if arranged in a planar Grandjean state. In the fingerprint state forward scattering prevails. With a light-absorbing background these two states provide the basis for a display with storage properties. Two-frequecy addressable materials provide a convenient way of switching between the two states. In addition they allow the generation of dynamic scattering in a limited frequency range. In the present work the textures are studied by means of light reflection. It is shown that the dynamic scattering mechanism leads to different characteristic textures as compared to switching by electric torques alone. Furthermore, the angular distribution of reflected light in the Grandjean state is studied for various preparation conditions. It is found that roughly half of the reflected light leaves under non-specular angles on average with a deviation of about 25 degrees. Driving conditions for a working multiplexed matrix display are given.