Browsing by Author "Yang, CL"

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A method to determine the higher order polar anchoring coefficients for the non-twisted liquid crystal cells
(2005-08-01)
Hsu, JS
;
Hsieh, MC
;
Yang, CL
;
Liang, BJ
;
Chen, SH
We propose a method to determine the higher order polar anchoring coefficients for the non-twisted liquid crystal cells. The surface anchoring energy density was determined by measuring the phase retardations as a function of applied voltage. We extended the Rapini-Papoular model and obtained the coefficients of the first and the second terms by analyzing the measured phase retardations with the simulated curves for the homogeneous and homeotropic cells. A discussion of the experimental results is given.
Dynamics of 3 pi/2-cell liquid-crystal devices
(2002-06-01)
Yang, CL
;
Chen, SH
;
光電工程學系
;
Department of Photonics
A supertwisted nematic liquid-crystal 3pi/2-cell with fast response and high contrast ratio as prepared. We investigated the dynamic mechanism of the 3pi/2-cell by theoretical analyst,., and numerical calculation. We found that, Unlike the TN [C. Z. van Doom: J. Appl. Phys 46 (1975) 3738: D. W. Berreman: J. Appl. Phys, 46 (1975) 3740] homogeneous [P. J. Bos et al.: SID 83 Dig., 1983, p. 30] and CHLC [S.-H. Chen et al,: Appl. Phys. Lett. 75 ( 1999) 3491] cells, the flow-induced viscous torque helps to Pull back the liquid-crystal molecules after the applied field is switched off and thus accelerates the relaxation process in the super-twisted nematic liquid-crystal 3pi/2-cell. Furthermore. using the liquid crystal of high optical anisotropy, a fast response of 2 ms was obtained.
Dynamics of twisted nematic liquid crystal pi-cells
(2002-05-20)
Chen, SH
;
Yang, CL
;
光電工程學系
;
Department of Photonics
A twisted nematic liquid crystal pi-cell with fast optical response time of 2.2 ms was prepared. We investigated the dynamics of this cell and observed the back-flow-induced optical overshoot phenomena both in homeotropic-to-planar state transition and planar-to-homeotropic state transition. We analyzed the behavior of the director and found that there is a tip-over phenomenon when the field is removed from relatively high voltage (>6 V). More important, the fluid flow effect results in the reverse twist both in the rising process and the decay process. Consequently, the reverse twist increases and decreases the effective phase retardation on the optical rising and decay process, respectively, and thus speeds up the optical response in both stages. (C) 2002 American Institute of Physics.
Multimedia task reliability analysis based on token ring network
(1996)
Chen, DJ
;
Chang, MS
;
Yang, CL
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資訊科學與工程研究所
;
Institute of Computer Science and Engineering