Temperature effect on Bistable Chiral Tilted-Homeotropic Nematic Liquid Crystal Cells

• Main Authors: Min-Hsuan Huang, 黃旻暄
• Other Authors: Jy-Shan Hsu
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/76170879330058183104

碩士 === 中原大學 === 應用物理研究所 === 98 === Abstract In this thesis, we analyze the influence of temperature on BHN-LCD, including the appearance, stability and switching processes through the temperature effect on the liquid crystal MLC-2048. In the first part of the thesis, we derive the birefringence and order parameter of MLC-2048 by measuring the phase retardation as a function of temperature in the lab-made homogeneous LC cells. Then using the order parameter which decreases as the temperature increases, we have the relationships between temperature and the elastic constants, rotational and shear viscosities. The dielectric constant and corresponding cross frequency are obtained by measuring the capacitances as functions temperature and the frequencies of the applied voltages in the homogeneous and vertically aligned cells. Finally, we used the disclination lines in wedge cells to calculate the pitches which increase when the temperature rises. In the second part of the thesis, the switching response time between two states decrease and the appearance of the BHN LC cell changes color slightly when the temperature increases. However, the stability of the Twisted state decreases. By analyzing the energy barriers between two stable states through the LC parameters as functions of temperature in the simulation, we conclude that the reason for the instability of Twisted state are because the energy barriers decrease and are unbalanced as the temperature rises.