液晶与显示, 2013, 28 (2): 173, 网络出版: 2013-04-15
液晶可调电容器的研究
Liquid Crystal Tunable Capacitor
液晶可调电容器 有效介电常数 平行排列向列相 混合排列向列相 liquid crystal tunable capacitor effective dielectric constant parallel aligned nematic hybrid aligned nematic
摘要
在外加电压作用下, 液晶的有效介电常数会发生变化, 导致液晶盒电容的改变, 由于液晶盒本身可以看作是一个电容器, 因此随着外加电压的不同其电容是可调的。基于液晶弹性理论和变分原理, 理论推导强锚泊平行排列和混合排列向列相液晶盒电容的解析表达式, 数值模拟得到了液晶盒的电容-电压曲线。通过数据分析, 两种液晶盒的电容特性存在一定的区别, 尤其在较低电压时为了获得较大范围的可调液晶电容器, 平行排列盒选择弹性常数κ较小且介电各向异性γ较大的液晶材料; 而混合排列盒选择弹性常数κ较大且介电各向异性γ较大的液晶材料。高压时两盒的选择是一致的。
Abstract
The effective dielectric constant of liquid crystal filled in this cell will change under an external applied voltage, which can result in the variation of the capacitance in liquid crystal cell. Because liquid crystal cell itself may be seen as a capacitor, its capacitance is tunable with different external applied voltages. Based on liquid crystal elasticity theory and variational principles, the analytical expressions of the capacitance in strong anchoring parallel aligned nematic (PAN) and hybrid aligned nematic (HAN) liquid crystal cell are deduced theoretically. The capacitance-voltage curves of these two cells are also obtained by numerical simulation. From the data analysis, there exist some differences for the capacitance characteristics between the two types of cells, especially in the case of low voltage. To obtain the wide range tunable capacitance, the liquid crystal material with the smaller elastic constant and the larger dielectric anisotropic constant should be chose for PAN cell; however, for HAN cell, the situation is reversed. When a high voltage is applied to the liquid crystal cell, the choice of liquid crystal material for two types of cells is consistent.
崔文静, 邢红玉, 叶文江, 张志东. 液晶可调电容器的研究[J]. 液晶与显示, 2013, 28(2): 173. CUI Wen-jing, XING Hong-yu, YE Wen-jiang, ZHANG Zhi-dong. Liquid Crystal Tunable Capacitor[J]. Chinese Journal of Liquid Crystals and Displays, 2013, 28(2): 173.