An improved equivalent circuit model and the dependence of hysteresis inversion frequency on typical parameters of V‐shaped switching SSFLC cells for both bookshelf and chevron structures

Abstract

An improved equivalent circuit model able to be applied to conventional circuit simulators is presented for optical response prediction and drive circuit design of V‐shaped surface‐stabilised ferroelectric liquid crystal (SSFLC) cells. The model is derived from Moore and Travis' original model. Moreover, the impedance divider induced by the multilayer structure of the liquid‐crystal cells is taken into account, and both polar and non‐polar surface anchoring energy are considered to make the model more preferable. The model is then utilised to investigate the thresholdless switching characteristics for both bookshelf and chevron structures. With the circuit model: (1) the genuine V‐shaped switching occurs only at the hysteresis inversion frequency f _i, and below (above) f _i an anomalous (normal) hysteresis is observed; (2) the genuine V‐shaped switching is only observed when the transmission is plotted as a function of the total applied voltage; (3) f _i increases with increasing conductivity of liquid‐crystal layer (G _LC) and the amplitude of applied voltage, and the function of is almost linear; (4) For small spontaneous polarisation p _s, f _i grows as p _s increases, however, on further increasing p _s, f _i reaches its maxima and then decreases (5) the V‐shaped switching can be observed in both bookshelf and chevron structures, however, f _i is higher for the chevron structure. Results obtained from the circuit model compare favourably with the reported experimental and numerical results.

Keywords:

• surface‐stabilised ferroelectric liquid crystal (SSFLC)
• V‐shaped switching
• hysteresis inversion frequency
• chevron structure
• equivalent circuit model

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 10174057 and 90201011) and the Key Project of Chinese Ministry of Education (No. 2005‐105148).