PERFORMANCE OF CONVENTIONAL AND NOVEL DEFORMED HELIX FERROELECTRIC LIQUID-CRYSTAL DISPLAY OPERATING MODES

Fast response times and wide viewing angles are characteristic feature s of the deformed-helix ferroelectric liquid crystal displays (DHF-LCD s) presented in this paper. We first discuss the electrooptics of the DHF effect, emphasizing the large electrically induced changes of bire fringence which occur in DHF-LCDs with large switching angles. Based o n these results a new DHF operating mode is introduced, which allows D HF display cell gaps larger than 5 mu m. A second new type of DHF-LCD operating mode is then presented, which is used for low-tilt-angle DHF materials. This second, double-layer DHF-LCD allows fast, bright, gho st-free, low-voltage operation. Finally, the influence of various FLC material parameters and their temperature dependence on DKF display pe rformance is investigated. It is shown that a pitch below 150nm at roo m temperature is required for high-contrast DHF-LCDs. It is also shown that with suitable driving electronics, operation of DHF-LCDs at vide o rates is possible down to -15 degrees C.