Liquid crystal display cell with fast response and continuous gray scale

Abstract

The invention relates to liquid crystal display cells with fast response and continuous gray scale. The liquid crystal cell is based on a field-sequential color system (“FSC”) and comprises a chiral smectic liquid crystal whose helix pitch is less than thickness of liquid crystal layer placed between two polarizers, as well as a source of voltage applied to electrodes of the cell, wherein the amplitude of the applied voltage is less than the critical voltage amplitude of the helix unwinding. The liquid crystal has one steady state corresponding to twisted helix without applied voltage. In this case, the principal optical axis coincides with the helical axes, but deviates from steady state under the action of a driving voltage, providing thereby an electro-optical response of the display which exhibits gray scale in light transmission or reflection that is continuous, hysteretic-free and non-sensitive to the driving voltage polarity, if the steady orientation of the principle axes is parallel or perpendicular to the light polarization plane and the driving voltage frequency is between 10 Hz and 5 kHz. In embodiments with very short helix pitches, the cells may be free from selective reflection and diffraction in the visible spectral range. Different embodiments of the invention may use ferroelectric liquid crystal, ferroelectric liquid crystal, or antiferroelectric liquid crystal.

Dependencies are inferred from the claim text.