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收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

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Author: search.filters.author.Chen, SHSubject: search.filters.subject.liquid crystals

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Now showing 1 - 5 of 5
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    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.
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    Crucial effects of polar alignment symmetry on the dynamical behaviors of quasi-homeotropic liquid crystal cells
    (2002-08-01)
    Hsieh, CY
    ;
    Chen, SH
    ;
    光電工程學系
    ;
    Department of Photonics
    We present an interesting transient electro-optical phenomenon including double optical bounce during the rising period of a quasi-homeotropic liquid crystal (QHLC) cell with an asymmetrical polar-alignment boundary condition. The unique optical behavior of the QHLC cell is produced by the flow effect together with the complicated alignment condition of the substrates, which is a combination of the deviation of azimuthal alignment and the asymmetrical polar alignment. We have found that the symmetrical characteristic of polar alignment plays a critical role in the dynamical behavior of the QHLC cell. Furthermore, our simulation results show that the double optical-bounce phenomenon appears even when the difference between the top and bottom tilt angles is only 0.1degrees. The experimental results and numerical calculation are described in this paper.
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    Electrically switching bistability of a chiral quasi-homeotropic liquid crystal device with low driving voltage
    (2003-11-01)
    Hsieh, CY
    ;
    Chen, SH
    ;
    光電工程學系
    ;
    Department of Photonics
    We report a new electrically switching bistable chiral quasi-homeotropic liquid crystal device with low driving voltage. This device is operated from the initial twisted-homeotropic state to either +90degrees or -270degrees twisted static state showing dark and bright transmittances, respectively, using different switching processes. The critical applied voltage to achieve the switching bistability of our device is only 4.3 V, which is approximately twice its threshold voltage for Freedericksz transition. In addition, the switching characteristics of this device with different driving waveforms are also investigated in this paper.
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    Influence of Frank elastic constant anisotropy on optical pattern formation using nematic liquid crystal films
    (2004-09-01)
    Hsu, HK
    ;
    Lai, YC
    ;
    Chen, SH
    ;
    光電工程學系
    ;
    Department of Photonics
    We investigate the influence of the Frank elastic constant anisotropy on optical pattern formation using nematic liquid crystal (NLC) films in one-feedback-mirror systems. The governing diffusion-like equation for the parallel planar-aligned and the vertical-aligned NLC films with an externally biasing quasi-static electric field under the hard boundary assumption is derived. The intrinsic Frank elastic constant anisotropy induces the anisotropy of the diffusion length, which results in the anisotropic distribution of the threshold intensity for optical pattern formation. The effects of the elastic constant anisotropy on optical pattern formation are studied for the first time and the obtained numerical results can reasonably explain the optical patterns that are formed.
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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.