Influence of the Flow Effect on the Dynamics of Liquid Crsytal Displays
|關鍵字:||液晶;液晶顯示器;動態響應;流動效應;反應速度;Liquid Crystal;Liquid Crystal Display;LCD;Flow Effect;Dynamics;response time|
The flow of liquid crystal is an essential part to the study of the dynamics of liquid crystal devices. In this work, we investigated the influence of the flow effect on the dynamics behavior of liquid crystal cells. Employing the Ericksen-Leslie theory, we analyzed the transient behavior of several liquid crystal modes by computer simulation. It was found that the optical bounce phenomenon of the transmittance-time curve which originally occurred in twisted nematic liquid crystal cells also appears in the rising period of pure homeotropic and chiral-homeotropic liquid crystal cells. In this work we successfully modeled this optical bounce and found this phenomenon is caused by the flow-induced twist. After analyzing the transient director behavior, we also examined the difference between the optical bounce of the twisted nematic cell and that of homeotropic-like cells. The simulation results agree with the experiments. From the information provided by computer simulation, we found that the response time of homeotropic-like cells can be improved by a larger twist elastic constant with little or no influence on the original static electro-optical properties. The dynamics of the twisted nematic cells were then analyzed. The effects of the chiral dopant in twisted nematic cells were also discovered. It was found that the finite pitch can reduce the optical bounce effect and improves the response time. Based on the observation of the transient transmittance of the pure homeotropic cell, we also predicted the existence of two stable states in the homeotropic liquid crystal cell. Furthermore, from this prediction, we demonstrated a new bistable liquid crystal device which can operate between tree states.
|Appears in Collections:||Thesis|