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.
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references
Yang D K, Wu S T. Fundamentals of Liquid Crystal Devices [M]. Chichester: John Wiley & Sons Ltd, 2006: 274.[2] Morris S W. Measurements of the elastic constants of a liquid crystal [D]. Vancouver: University of British Columbia, 1985.[3] Welford K R, Miners F, Sambles J R. A new technique for determining the dielectric constants of a nematic liquid crystal [J]. J. Phys. D: Appl. Phys., 1988, 21: 1320-1325.[4] 温庆祥, 黄锡珉, 何林, 等. C-V法液晶弹性常数的测定 [J]. 液晶与显示, 1993, 1(1): 73-78. [5] 孔祥建, 荆海, 黄霞, 等. 一种改进的C-V方法对向列相液晶弹性常数k11、k33测量的理论研究 [J]. 液晶与显示, 2007, 22(5): 587-590.[6] 崔文静, 邢红玉, 张艳君, 等. 挠曲电效应对向列相液晶盒电容的影响 [J]. 数值计算与计算机应用, 2012, 33(2): 142-150.[7] 崔文静, 邢红玉, 张艳君, 等. 混合排列向列相液晶盒电容特性研究 [J]. 液晶与显示, 2012, 27(5): 608-612.[8] Nastishin Y A, Polak R D, Shiyanovskii S V, et al. Nematic polar anchoring strength measured by electric field techniques [J]. J. Appl. Phys., 1999, 86(8):4199-4213.[9] Nie X Y, Lin Y H, Wu T X, et al. Polar anchoring energy measurement of vertically aligned liquid-crystal cells [J]. J. Appl. Phys., 2005, 98(1): 013516.[10] 谢毓章. 凝聚态物理学丛书:液晶物理学[M]. 北京: 科学出版社, 1998: 110-112.[11] 谢毓章. 凝聚态物理学丛书: 液晶物理学[M]. 北京: 科学出版社, 1998: 28-38, 105-107.[12] Sugimura A, Luckhurst G R, Ou-yang Z-C. Director deformation of a twisted chiral nematic liquid crystal cell with weak anchoring boundaries [J]. Phys. Rev. E, 1995, 52(1): 681-689.