PHYSICS AND ELECTRONIC MODEL OF DEFORMED HELIX FERROELECTRIC LIQUID-CRYSTAL DISPLAYS

An electronic equivalent circuit is shown to completely describe both the electrical as well as the electrooptical properties of deformed helix ferroelectric (DHF) liquid crystal displays (LCDs). The static and the dynamic performance of DHF-LCDs are modeled using an equivalent circuit. The agreement between modeled gray-scale performance of DHF-LCDs and experiments is excellent. Several driving schemes derived from the equivalent circuit provide the full gray scale and render DHF-LCDs video-compatible at voltages below 13 V. Moreover, de-free and thus ghost-image-free operation of DHF-LCDs is shown to be feasible with minimal loss of brightness. Capacitive coupling is shown to decrease the switching time of DHF-LCDs from 30 mu s to 6 mu s.