Browsing by Author "Yeh, En-Rong"

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Advanced color-reflective dual-frequency cholesteric liquid crystal displays and the driving matrix
(2017-01-01)
Hsiao, Yu-Cheng
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Yeh, En-Rong
;
Lee, Wei
;
影像與生醫光電研究所
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Institute of Imaging and Biomedical Photonics
We propose a novel color-reflective, dual-frequency cholesteric liquid crystal display (DFCLCD) by employing hybrid alignment treatment. The switching voltage is significantly lowered to favor the thin-film transistors used in the current display market and the response time is drastically reduced to the millisecond level while the bistability remains. Test cells with three distinct helical pitches were fabricated to demonstrate the concept of color pixels. The DFCLCD can be directly switched from the bright planar state to the light-scattering state by a low-frequency voltage pulse, and reversibly by a high-frequency pulse. A drive scheme is presented for the advanced color DFCLCD.
Spatial and electrical switching of defect modes in a photonic bandgap device with a polymer-dispersed liquid crystal defect layer
(2014-08-25)
Wu, Po-Chang
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Yeh, En-Rong
;
Zyryanov, Victor Ya.
;
Lee, Wei
;
影像與生醫光電研究所
This paper investigates the spectral properties of a one-dimensional photonic crystal (PC) containing an inhomogeneous polymer-dispersed liquid crystal (PDLC) as a defect layer. Experimental results indicate that the voltage-induced reorientation of LC molecules between the light-scattering and transparent states in the PDLC enables the electrical tuning of the transmittance of defect-mode peaks in the spectrum of the PC/PDLC cell. Specifically, owing to the unique configuration of the spatial distribution of LC droplet sizes in the defect layer, a concept concerning the spatial switching in the wavelength of defect modes is proposed. As a result, the PC/PDLC hybrid cell is suggested as a potential element for realizing an electrically tunable and spatially switchable photonic bandgap device, which is polarizer-free and requires no alignment layers in the fabrication process. (C) 2014 Optical Society of America
Temperature-dependent electrical and dielectric properties of nematic liquid crystals doped with ferroelectric particles
(2016-09)
Hsiao, Yu-Cheng
;
Huang, Sheng-Miao
;
Yeh, En-Rong
;
Lee, Wei
;
影像與生醫光電研究所
We report on the temperature dependence of dielectric properties of nematic liquid crystals impregnated with BaTiO3 (BTO) ferroelectric nanoparticles. The behavior of ion transport at low frequencies is discussed by means of dielectric spectroscopy, which allows the ionic concentration and the relaxation time of electrode polarization to be deduced. The experimental results imply that the ferroelectric nanopartides can not only increase the traveling time of ions between two electrodes but also suppress the buildup of the electric double layers. Verified by the voltage holding ratio of cells containing various contents of BTO nanoparticles, it is obvious that doping BTO into liquid crystals is a low-cost and easy way to improve the device performance. (C) 2015 Elsevier B.V. All rights reserved.
Temperature-dependent electrical and dielectric properties of nematic liquid crystals doped with ferroelectric particles
(2016-09-01)
Hsiao, Yu-Cheng
;
Huang, Sheng-Miao
;
Yeh, En-Rong
;
Lee, Wei
;
影像與生醫光電研究所
We report on the temperature dependence of dielectric properties of nematic liquid crystals impregnated with BaTiO3 (BTO) ferroelectric nanoparticles. The behavior of ion transport at low frequencies is discussed by means of dielectric spectroscopy, which allows the ionic concentration and the relaxation time of electrode polarization to be deduced. The experimental results imply that the ferroelectric nanopartides can not only increase the traveling time of ions between two electrodes but also suppress the buildup of the electric double layers. Verified by the voltage holding ratio of cells containing various contents of BTO nanoparticles, it is obvious that doping BTO into liquid crystals is a low-cost and easy way to improve the device performance. (C) 2015 Elsevier B.V. All rights reserved.