• Polymer(Korea)
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• v.35 no.5
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• pp.493-498
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• 2011

Reactive mesogens were used to prepare photo-cured liquid crystal films in which orientations of liquid crystal molecules were preserved by crosslinked networks of cured reactive mesogens. The molecular orientations of liquid crystal mixtures of photo-reative mesogens and non-reactive nematic liquid crystals were studied and compared before and after curing reactions. The effects of temperature and the amount of the non-reactive nematic liquid crystal in the mixture on birefringence of the liquid crystal films were investigated. It was found that optical compensation films with different birefringence could be prepared by controlling the amount of the nematic liquid crystals in the reactive mesogen mixtures.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.194-198
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• 1991

네마틱 액정셀에 사각전압펄스를 가하며 액정의 splay 변형시간을 조사하였다. 광학적 방법으로 복굴절 신호의 오름시간과 네팀시간을 측정하였으며 외부전압과 두께를 변화시키면서 신호 형태와 반응시간의 변화를 관찰하였다. 그 결과는 Leslie-Ericksen의 식으로 근사적으로 분석할 수 있으며 이로부터 점성 계수를 구할 수 있다.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.32-34
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• 2001

본 연구에서는 액정디스플레이의 전기광학특성 분석에 사용되고 있는 두 가지 모델링 방법인 벡터접근법과 텐서접근법에서, 각각의 지배방정식을 시뮬레이션 함으로써 두 접근법의 결과를 비교 및 분석하였다. 이를 위하여 1차원적 시뮬레이션과 함께 측면전장효과 및 disclination line등의 영향을 모두 고려하기 위해 3차원적 액정분자배열 분포를 동일한 조건에 대하여 시뮬레이션 하였다. 두 접근방법에 대한 동적 특성은 단위화소 내의 국부 점에서 많은 차이를 보임을 확인하였으며, 이에 따라 네마틱액정의 방향자에 대한 네마틱 대칭성이 고려된 텐서접근법이 물리적으로 의미가 있으며 실제 현상도 명확하게 설명할 수 있음을 확인하였다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2004.06a
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• pp.85-88
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• 2004

광 정보 처리 특성을 극대화하기 위해 실시간 동작이 가능한 공간 광 변조기를 사용하며 그중 액정 화면은 기존의 공간 광 변조기에 비해 가격이 저렴하고 특히 꼬인 네마틱 액정 화면 공간 광 변조기는 전기 신호에 따라 광을 변조 할 수 있다는 원리에 의해 여러 가지 이론과 설계 방법이 연구되었으며 기본 매개 변수들을 효과적으로 계산하는 방법이 계속 발표되었다. 본 논문에서는 원형 편광 된 광을 꼬인 네마틱 결정을 갖는 공간 광 변조기에 투사 시켜서 검광기에 통과한 세기 분포를 관찰하여 이상 굴절 축의 회전 방향을 결정하는 방법을 제안하였으며, 존스 행렬을 사용하여 수학적 타당성을 부여하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.911-917
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• 1998

In this paper, we have investigated the generation of pretilt angle for nematic liquid crystal (NLC) in a cell with oblique non-polarized ultraviolet(UV) light irradiation polyimide (PI) surface. It was found that the monodomain alignment of the NLC is obtained with an angle of incidence of 70∼85。 on PI surface. It is considered that the monodomain alignment of NLC is attributed to anisotropic of NLC is about 3。 with and angle of incidence of 70∼75。. Finally, we observed that the voltage-transmittance, response time, and voltage-holding-ratio(VHR) characteristics of photo-aligned twisted nematic(TN)-LCD with and angle of incidence of 85。 on PI surface were almost same compared to rubbing -treated TN-LCD.

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.11a
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• pp.123-123
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• 2000

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.461-466
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• 1997

In this paper, we developed the new non-rubbing liquid crystal (LC) alignment techniques in the cell with slanted non-polarized ultraviolet (UV) light irradiation on polyimide (PI) film. It is shown that the uniform alignment for nematic (N) LC is obtained by using slanted non-polarized UV light irradiation on PI surface. We successfully obtained that the pretilt angle of NLC is generated about 3.3 degree in the cell with slanted non-polarized UV light irradiation with 70 degree on PI surface, for the first time. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecular and the PI, which is broken the polymer by slanted non-polarized UV irradiation. Therefore, we concluded that the uniform LC alignment is attributed to anisotropic dispersion force due to photo depolymerization with slanted non-polarized UV light irradiation on PI surface.

• Electrical & Electronic Materials
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• v.9 no.3
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• pp.265-269
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• 1996

We have studied the effect of the mesogenic core of nematic liquid crystals (NLCs) for polar (out-of-plane tilt) anchoring strength and surface order parameter on rubbed polyimide (PI) surfaces. The order of polar anchoring strength for NLCs on rubbed PI surfaces is 5CB > PCH5 > CCH5. From the above results, we suggest that the polar anchoring strength depends on the polarizability of the NLCs. The surface order parameter for NLCs is 5CB > PCH5 > CCH5 on rubbed PI surfaces. We conclude that the polar anchoring strength is strongly related to the surface order parameter on rubbed PI surfaces.

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.876-880
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• 1997

In this paper we investigated the transcription of liquid crystal (LC) alignment method by using memory effect of nematic(N) LCon polymide(PI) surface with side chain as for non-rubbing alignment techniques. That the monodomain alignment of aligned NLC is observed by microscope textures in the cells on PI surface with side chain. We obtained that the pretilt angle of NLC are generated about 3.7$^{\circ}$on PI surface. We suggest that the LC alignment by using transcription alingnment method is attributed to memory effect of NLC on PI surface.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.161-168
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• 2008

We propose a novel bistable nematic liquid crystal cell, which has a dual-frequency liquid crystal material and pixel-isolating polymer wall formed by an anisotropic phase separation of a mixture of liquid crystals and UV-curable pre-polymers. The proposed cell has two stable states of left- and right-handed ${\pi}$-twist. The switching between the two states is achieved by using a sequential waveform of low and high frequencies. A transmissive bistable liquid crystal display is designed, which achieves high contrast ratio by using the proposed cell and optical films.