Browsing by Author "Hsieh, Pao-Ju"

Now showing 1 - 3 of 3

Evaluation of Kerr constant of blue-phase liquid crystals by measuring off-axis retardation in vertical electric field cells
(2011-09-20)
Hsieh, Pao-Ju
;
Chen, Huang-Ming Philip
;
光電工程學系
;
Department of Photonics
Because of the nonuniform electric field of the in-plane-switching cell in the thickness direction, an accurate and efficient way for evaluating the Kerr constant of blue-phase liquid crystal (BPLC) needs to be developed. This study demonstrates a method for evaluating the Kerr constant by measuring the off-axis-induced retardation (R(th)) change in normal vertical field cells using a commercial polarimeter. The angle-dependent behavior of the R(th) change is observed as an electric-tunable positive C retarder. In this paper, a sigmoid fitting model has been chosen for calculating the Kerr constant for considering the very small intrinsic birefringence of the BPLC. (C) 2011 Optical Society of America
Gray-scale, low color shift cholesteric liquid crystal displays
(2007)
Wu, Keng-Jui
;
Hsieh, Pao-Ju
;
Chen, Huang-Ming Philip
;
光電工程學系
;
Department of Photonics
Cholesteric Liquid Crystals (CLCs) have severe blue shift when applied voltage. Lack of gray scale also hinders their display application. In this study, the value of CLC hosts' dielectric anisotropic (Delta epsilon) was varied by mixing negative and positive nematic LCs. Based on this method, the color shift (Delta E*ab) was greatly improved from 49.89 to 10.80.
Hysteresis-free polymer-stabilised blue phase liquid crystals comprising low surface tension monomers
(2015-02-01)
Hsieh, Pao-Ju
;
Chen, Huang-Ming Philip
;
分子醫學與生物工程研究所
;
光電工程學系
;
顯示科技研究所
Partial replacement of fluoroacrylates in the monomer composition is able to reduce the free energy of polymer-stabilised blue phase liquid crystal (PSBPLC) due to their low surface tension. The ease of blue phase platelet texture formation is observed under fast cooling and short annealing time before ultraviolet irradiation. The peak driving voltages are dramatically decreased from 9% to 16% in the resulting PSBPLCs. In addition, the hysteresis is completely suppressed in the PSBPLC containing 3FM-M1. The other PSBPLC containing fluoroacrylates retain very small hysteresis (oV<0.8V) regardless the fluorine atom numbers. In comparison with current PSBPLCs, the fluoroacrylates serve as mesophase enhancer not only to promote the blue phase formation but also to improve the electro-optical properties.