Materials aspects of thermally addressed smectic and cholesteric liquid crystal storage displays

Abstract

New improved materials for smectic liquid crystal storage displays are described which have the advantages of image generation at lower laser power, independence of image generation over a wider range of laser scanning speeds, improved contrast, and near ambient temperature (24°C) storage. The electric erase characteristics, laser writing speeds, and contrast are demonstrated to be dramatically dependent on both the smectic liquid crystal and added dopants. Local electric erase is observed only for smectic liquid crystals having a nematic phase or incipient nematic range. Better contrast and a wider range of laser writing speeds are obtained when dopants are added which are soluble in the isotropic phase and insoluble in the smectic phase. Enhanced contrast (higher scattering center density) obtained by adding certain dopants is considered to result from enhanced nucleation in the bulk and stabilization of singularities resulting therefrom by reduction of the associated core and strain energies.