Browsing by Author "Chen, Shu-Hsia"

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Brightness Enhancement with a Fingerprint Chiral Nematic Liquid Crystal
(2011-03-01)
Lee, King-Lien
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Wu, Jin-Jei
;
Chen, Tien-Jung
;
Wu, Yeong-Shiun
;
Chen, Fu-Chen
We demonstrate a brightness enhancement element that can be laminated to a linear polarizer for increasing the optical efficiency of a liquid crystal display device. The device structure is a chiral nematic liquid crystal (CNLC) with a fingerprint texture. For an unpolarized incident light, our experimental results show that the combination of a CNLC film and a conventional linear polarizer can achieve a transmittance of over 50%. The CNLC film increases the optical efficiency of a conventional polarizer by 21.7%. The detailed mechanism of such a CNLC-polarizer system is analyzed. (C) 2011 The Japan Society of Applied Physics
Computer simulation of the similar-Helfrich deformation during the transient planar to planar transition in cholesteric liquid crystals
(2004)
Yao, I-An
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Chen, Shu-Hsia
;
Wu, Jin-Jei
;
光電工程學系
;
Department of Photonics
The three-dimensional dynamic relaxation process in cholesteric liquid crystals with low thickness to pitch ratio ((sic)2) after switching off an electric field have been numerically investigated both for cells with parallel boundaries and for ones with perpendicular boundaries. For cholesteric liquid crystal cells with different surface alignment conditions, our simulation results show that the mechanism of transition from homeotropic to planar state is entirely different. In a cell with parallel boundary conditions, the transition from homeotropic to planar is in a sequence of homeotropic - transient planar-planar. In a cell with perpendicular boundary conditions, the relaxation from homeotropic to planar is in a different sequence of homeotropic - planar. The similar-Helfrich deformation only occurs during the transient planar - planar transition. Based on our simulation results, we can also show that the relaxation from homeotropic to planar in a cell with perpendicular boundary conditions is faster than that in a cell with parallel boundary conditions.
Dynamic behaviors of dual frequency liquid crystals in bistable chiral tilted-homeotropic nematic liquid crystal cell
(2006-07-31)
Hsu, Jy-Shan
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Liang, Bau-Jy
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Chen, Shu-Hsia
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光電工程學系
;
Department of Photonics
The switching behaviors of dual frequency liquid crystals (DFLC) in a bistable chiral tilted-homeotropic nematic (BHN) LC cell are simulated and compared with the observed results. This cell can be switched between tilted-homeotropic state and twisted state under the applied voltage as low as 5 V. The reason for the low switching voltage is attributed to the dielectric anisotropy character of DFLC. The analysis also shows that the switching wave form accelerates the switching behaviors of the directors which results in faster response in BHN LC cell. (c) 2006 American Institute of Physics.
Electro-optical optimization in transflective OCB LCD
(2005)
Xiang, Rui-Jie
;
Yang, Chiu-Lien
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Chen, Chueh-Ju
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Chen, Shu-Hsia
;
光電工程學系
We propose a transflective OCB LCD with wide viewing angle, which is achieved by optimizing the parameters of the wide-band quarter wave plates and compensating films to the electrical-induced bend state of liquid crystal layer. Simulation results show the normalized voltage dependence of transmittance and reflectance overlap completely and the viewing angle is better than the conventional transflective LCD[1].
Fringing-Field Effects on High-Resolution Liquid Crystal Microdisplays
(2005-12-01)
Fan-Chiang, Kuan-Hsu
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Wu, Shin-Tson
;
Chen, Shu-Hsia
;
光電工程學系
;
Department of Photonics
Fringing- field effects on high-resolution liquid crystal microdisplay devices, including the reflection-type liquid-crystal-on-silicon (LCOS) and transmission-type poly-silicon thin-film-transistor liquid crystal displays are simulated by the beam propagation method. The electro-optic performances of six commonly used liquid crystal modes are analyzed by the two-dimensional optical simulator. The vertically aligned (VA) cell exhibits the highest contrast ratio, but its fringing-field effect is severe. A circularly polarized light illuminated LCOS device is presented to eliminate the fringing-field effect of the VA cell. Both simulated and confirming experimental results show that the long-standing problems of poor sharpness, low brightness, and slow transition time of the VA cell can be overcome by using a circularly polarized light.
High aperture ratio TFT array structures for IPS mode with low crosstalks
(2004)
Lin, Jiunn-Shyong
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Chen, Shu-Hsia
;
Yang, Kei-Hsiung
;
光電工程學系
;
Department of Photonics
The replacement of CRT by TFT-LCD in TV application requires the implementation of LC modes with wide viewing angles and excellent video-display quality. IPS mode has been known as an excellent technology to realize wide viewing angles. In this paper, we report the designs of two novel TFT electrode structures that not only increase the aperture ratio but also reduce the crosstalks. We have improved IPS mode in aperture ratio by 1.5 times and effectively reduced the coupling ratio from 4.2% to 2.1%.
Optical system design
(2006-11-16)
Chiang, Kuan-Hsu Fan
;
Zhu, Xinyu
;
Wu, Shin-Tson
;
Chen, Shu-Hsia
This invention discloses an optical system design, which is used in a liquid crystal display apparatus. The optical system design at least comprises a light generation module, a circular polarization module and a liquid crystal light valve, wherein the light generation module is used to generate a light, the circular polarization module is used to modulate the polarization state of the light to a circular polarization state, and the liquid crystal light valve is used to modulate the polarization state of the light, so as to modulate the intensity of the light to show the image. The optical system design is able to solve the problem of fringing-field effects.