• Title/Summary/Keyword: dielectric anisotropy

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Electro-optical Characteristics of a Multi-domain Vertical-alignment Liquid Crystal Display on Homeotropic Photopolymer Layer

  • Hwang, Jeoung-Yeon;Lee, Kyung-Jun;Seo, Dae-Shik
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.511-513
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    • 2002
  • Electro-optical characteristics of new multi-domain vertical-alignment (MVA) liquid crystal displays (LCDs) with negative dielectric anisotropy on a homeotropic photopolymer were studied. Good voltage-transmittance (V-T) curves by the new MVA-LCD on the homeotropic photo-polymer were obtained. Also, the stable response time of MVA-LCD on the homeotropic photopolymer can be achieved. The viewing angle of the new MVA-LCD could be improved by the grating groove with UV exposure and development on the photo-polymer.

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Liquid Crystal Aligning Capabilities on Homeotropic Blending Polyimide Layer (수직 복합 폴리이미드층에서의 액정 배향 특성)

  • Hwang, Jeoung-Yeon;Seo, Dae-Shik;Kim, Jae-Hyung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.11b
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    • pp.337-340
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    • 2001
  • The control of high pretilt angle far nematic liquid crystal (NLC) with negative dielectric anisotropy on the rubbed blending polyimide (homeotropic and homogeneous alignment) surface were studied. High NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-7492 surface was measured and the NLC pretilt angle increases with blending ratio and rubbing strength. However, the NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-150 surface was not varied. The high pretilt angle the NLC using blending polyimide surface can be acheived.

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Pretilt Angle Effects on Electro-Optic Characteristics of the Fringe-Field Switching (FFS) Mode

  • Hong, Seung-Ho;Lim, Kyu-Whan;Kim, Hyang-Yul;Lee, Seung-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.43-44
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    • 2000
  • The fringe-field switching (FFS) display is known to exhibit wide-viewing-angle and high transmittance. We have simulated pretilt effects on electro-optic characteristic of the device when a liquid crystal with positive and negative dielectric anisotropy is used. The results show that asymmetry in contour of luminance and light leakage in the dark state are increased but voltage-dependent transmittance curves remain about the same, as the pretilt angle increases to $10^{\circ}$.

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Wide viewing angle and fast response time using novel vertical-alignment - 1/4 ${\pi}$ cell mode

  • Lee, Jeong-Ho;Seo, Dae-Shik;Kim, Hyang-Yul
    • 한국정보디스플레이학회:학술대회논문집
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    • 2000.01a
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    • pp.9-10
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    • 2000
  • The wide viewing angle and fast response time characteristics of negative dielectric anisotropy nematic liquid crystal (NLC) using a novel vertical-alignment (VA) - 1/4 ${\pi}$ cell mode on a homeotropic alignment layer were investigated. Good voltage-transmittance curves and low driving voltage using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film were obtained. The iso-viewing angle characteristics of NLC using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film can be achieved. The fast response time of 24.4 ms in NLC was successfully measured. The iso-viewing angle, fast response time, and low driving voltage characteristics using the novel VA - 1/4 ${\pi}$ cell mode can be achieved.

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Vertically Aligned Nematics at Polymer interfaces and Its device implications

  • Srinivasarao, Mohan;Park, Jung-Ok;Zhou, Jian
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.558-561
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    • 2005
  • In-situ photopolymerization of alkyl acrylate monomers in the presence of a nematic fluid provides a cellular matrix of liquid crystalline droplets in which the chemical structure of the encapsulating polymer exerts control over the alignment (anchoring) of the liquid crystalline molecules. Control is obtained by variation of the alkyl side chains and through copolymerization of two dissimilar monofunctional acrylates. Two monofunctional acrylates with opposing tendencies on copolymerization provide control over the tunability of anchoring over a wide temperature range. Using various acrylates we show that a uniform vertical alignment can be achieved over a large area. Utilizing this technique and a nematic with negative dielectric anisotropy, we have fabricated highly flexible liquid crytal based devices, with high contrast and fast response time, without using any alignment layer.

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A Study on wide viewing angle and fast response time using new VA-$\pi$ cell mode (새로운 VA-$\pi$ 셀 모드를 이용한 광시야각과 고속 응답에 관한 연구)

  • 서대식;이정호
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.4
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    • pp.332-336
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    • 2000
  • We have developed a novel vertical-alignment(VA) -$\pi$ cell mode that provides a wide viewing angle and fast response times for nematic liquid crystal(NLC) with negative dielectric anisotropy on a homeotropic polymide(PI) surfaces. Good voltage-transmittance curves and low driving voltages were achieved with the new VA-$\pi$ cell mode without a negative compensation film. Iso-viewing angle characteristics using the new VA-$\pi$ cell mode without a negative compensation film was also successfully observed. As well a fast response time of 31.7 ms for a new VA-$\pi$ mode was measured. Consequently the iso-viewing angel fast response time and low driving voltage characteristics using a VA-$\pi$ cell can be achieved.

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Wide Viewing Angle Characteristics Using Novel Vertical-Alignment 1/6$\pi$ Cell Mode (새로운 VA-1/6$\pi$셀 모드를 이용한 광시야각 특성)

  • 황정연;서대식;한은주;김재형
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.10
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    • pp.883-886
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    • 2000
  • We have developed a novel vertical-alignment(VA) - 1/6$\pi$ mode that provides a wide viewing angle for nematic liquid crystal (NLC) with negative dielectric anisotropy on a homeotropic polyimide (PI) surfaces. Good voltage-transmittance curves were achieved with the new VA - 1/6$\pi$ cell model without a negative compensation film. The viewing angle of a new VA -1/6$\pi$ cell without a negative compensation film was wider than that of a conventional VA cell. Finally, the wide viewing angle using the new VA-1/6$\pi$ cell mode can be achieved.

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Electrical Properties of (N-docosyl quinolinium)-TCNQ(1 :2) Charge Transfer Complex Langmuir-Blodgett Films ((N-docosyl quinolinium)-TCNQ(1:2) 전하 이동 착물 Langmuir-Blodgett막의 전기적 특성)

  • 정순욱;정회걸
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.143-146
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    • 1999
  • In this study, Ultra-thin films of (N-ducosyl quinolinium)-TCNQ(1:2) complex were prepared on the hydrophilic substrate by Langmuir-Blodgett(LB) technique. By measure of UV-vis spectra and capacitance, deposition status was confirmed together with the thickness of natural oxidized aluminum film inside a device and dielectric constant of (N-docosyl quinolinium)-TCNQ(1:2) complex. The electrical properties of (N-docosyl 7uin7linium)-TCNQ(1:2) complex were investigated at room temperature. The conductivity of this film measured by the direction uf either vertical or horizontal axis is results in a quite different value.

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Study of wide viewing angle and response time by using new VA-$\pi$ cell mode cell mode (새로운 VA-$\pi$ cell mode cell mode를 이용한 광시야각 및 응답속도에 관한 연구)

  • 이정호;김진호
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.549-552
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    • 1999
  • We have developed an novel vertical-alignment (VA) - $\pi$ cell mode that provides a wide viewing angle and fast response times for negative dielectric anisotropy nematic liquid crystal (NLC) on a homeotropic polyimide (PI) surfaces. We had the good voltage-transmittance curves and low driving voltages were achieved with the novel VA - $\pi$ cell mode without negative compensation film. Iso-viewing angle characteristics using the novel VA - $\pi$ cell mode without negative compensation film of NLC was also successfully observed. As well a fast response time of 31.7ms for the novel VA - $\pi$ cell mode was measured. Consequently, It is seen that by using the novel VA - $\pi$ cell mode the iso-viewing angle, fast response time, and low driving voltage characteristics can be achieved.

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Improvement of viewing angle characteristics using a VA-1/6$\pi$ cell (VA-1/6$\pi$셀을 이용한 시야각 특성의 개선)

  • 황정연;서대식;한은주;김재형
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.515-518
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    • 2000
  • We studied the viewing angle characteristics of a negative dielectric anisotropy nematic liquid crystal (NLC) using the new vertical-alignment (VA)-1/6 cell on a rubbed polyimide (PI) surface. Good voltage-transmittance (V-T)characteristics using the new VA-1/6 cell without a negative compensation film were obtained. The iso-viewing angle characteristics using the new VA-1/6 cell without the negative compensation film can be achieved.

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