Fast switching electro-optical devices using banana-shaped liquid crystals

Abstract

The invention is directed to liquid crystal display and electro-optical devices having faster switching times, a wider viewing angle, continuous gray level, improved transmittance of the clear state, approximately no threshold voltage and low power consumption. The aspects of the invention are achieved by a liquid crystal device comprising an orthogonal nematic, smectic or columnar liquid crystal phase, which is uniaxial in absence of electric field, but becomes biaxial when electric field is applied normal to the director (in between electrodes for planar alignment, or in-plane electric field in case of homeotropic alignment). This electric field induced biaxiality (EFIB) mode is provided using any dielectric orthogonal nematic, smectic or columnar bent-core liquid crystal phase. The nature of the switching is dielectric (not piezoelectric) and does not involve variation of layer spacing variation, so as to be mechanically much more stable than prior systems. The high switching speed combined with a large change in the effective birefringence and constant optical axis of the liquid crystal materials provide useful features in various applications, such as liquid crystal television, beam steering, spatial light modulators, and a variety of other applications.