• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.48-53
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• 2008

We propose an optical configuration to compensate dispersion characteristics in the dark state of normally black twisted nematic (NB-TN) liquid crystal display (LCD). We employed a half-wave plate (HWP) and a +A plate to achieve the superior dark state. By using the parameter space diagram (PSD) method, we could obtain the optimum values of parameters and the high contrast-ratio over 500 : 1 could be obtained. Furthermore, excellent dispersion characteristics were also obtained in the bright state. We could confirm the performance of the proposed structure using both the numerical calculations and the experiments.

• Information Display
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• v.5 no.5
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• pp.4-9
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• 2004

최근 비오이 하이디스에서는 무제한의 광시야각과 시야각에 따른 색변화가 최소화된 선명한 색 특성을 갖는 Advanced FFS(Fringe Field Switching) 기술을 개발하였다. 이 기술은 resin 기술적용(평탄화에 의한 고개구율)없이 종래의 FFS 기술에서 액정의 전기 광특성을 최적화하는 새로운 디자인 룰을 찾아내어 실현하였다. 진보된 화소 개념은 전극의 모서리 구조, 전극 간격/폭, 칼라 필터의 블랙 마트릭스(BM)와 전극 간격등의 key parameters들의 최적화에 의해 달성되었고 액정 셀 내의 모서리와 전기장등이 액정을 미세하게 조정할 수 있도록 있게 된 것이다. 이러한 진보된 설계 개념은 모든 FFS 제품에 반영되어 개발되었다. 뿐만 아니라 12.1" XGA 제품에서 투과율이 22% 증가하고 흑백 대비비(Contrast Ratio)는 33% 증가한 600 : 1의 세계 최고 사양을 갖는 제품을 개발하게 되었다. 특히 태블릿과 노트북용 TFT- LCD 모듈에서 단일 도메인(Single Domain) 모드로도 White상태에서 시야각에 따른 색변화가 0.02 이하의 특성을 갖고 180도/180도의 무제한 시야각을 갖고 있다. Advanced FFS 기술의 브랜드 이름과 슬로건으로 'Viewiz'와 'Vision Magic'을 정하여 마케팅 중이며 세계적인 Top Tier 고객에 제품을 판매 중이고, 2004년 3분기에는 태블릿 시장에서 점유율 70%로 1위를 차지하였다.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.468-471
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• 2001

A novel method to measure the cell gap of a single-polarizer reflective twisted nematic liquid crystal (TN LC) cell by using a rotating polarizer technique is proposed. By rotating an LC cell, we can measure the cell gap of an LC cell as well as the wavelength dependence of retardation under the condition that the twist angle is known.

• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.235-239
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• 2001

In this paper, we propose an optical configuration of a reflective AFLC display mode using a half-wave AFLC cell in which inplane tilt angle is $22.5^{\circ}C$. To check the validity of our design, we fabricate a reflective half-wave AFLC cell of which the in-plane tilt angle is $24.9^{\circ}C$, and measure viewing angle and visible spectra characteristics. In the results, the half-wave AFLC cell in the reflective configuration exhibits wide viewing-angle as well as high brightness and contrast. trast.

• Journal of the Korean Chemical Society
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• v.48 no.5
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• pp.499-503
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• 2004

We designed and synthesized compounds which have negative dielectric anisotropy (N type) for VA-LCD mode. Due to the large dipole moments toward the minor axis of molecule and anisotropy of polarizability, they can be used as N type LC. F atom and NCS group and propyl group were introduced as substituents on bicyclohexylbenzene core unit and alkyl chains (propyl~heptyl) were introduced on terminal part. All of the synthesized compounds showed negative dielectric anisotropy as expected.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.140-141
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• 2005

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.162-165
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• 2002

We propose an optical configuration for a transflective display mode using a transflective film and a half-wave AFLC cell whose in-plane tilt angle is 22.5。. It provides high brightness and high contrast in the reflective mode as well as in the transmissive mode.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1512-1517
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• 2012

In this paper, we proposed the novel hybrid guest-host liquid crystal display using the negative charged black particles in order to improve the low contrast ratio. We designed patterned electrode in order to switch the charged particle to the opposite electrode and improved the electro-optical characteristics by optimize the mixture of guest materials. In Comparison with the Heilmeier Guest-Host mode, proposed hybrid guest-host structure showed 80% reduction of transmittance in dark state, and the performance was examined by comparing contrast ratio.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.206-209
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• 2004

We investigated response characteristics of liquid crystal display(LCD) with different operating mode of nematic liquid crystals (NLCs) such as $45^{\circ}$twist nematic (TN), $67.3^{\circ}$TN and ECB(electrical controlled birefringence) on a rubbed polyimide (PI) surface. The three kinds of LCD operating mode obtain stable EO performance. Low transmittances of the $45^{\circ}$TN and $67.3^{\circ}$TN cell on the rubbed PI surface were achieved by using low cell gap d. The fast response time of ECB cell among the three kinds of LCD operating mode was measured.

• Journal of IKEEE
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• v.27 no.4
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• pp.512-517
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• 2023

In this study, we propose a liquid crystal-based polarization control technology that can control polarization by adjusting the voltage applied to the liquid crystal, and apply it to a Closed-circuit Television (CCTV) to transmit only the desired angle of polarized light. CCTV with conventional polarizing films cannot control polarization because they focus on backlight compensation, so light reflected from the water surface or highlights reflected from vehicles interfere with subject identification. However, the Vertical Alignment mode allows the polarization to be adjusted electrically, so that only the polarized light at the user's desired angle is transmitted, eliminating reflected highlights. The images obtained using this technique are optimized by computer software. Liquid crystal polarization panels, which can electrically control the polarization angle, transmittance, and polarization rate, have been applied to polarized image monitoring device to improve subject identification in conventional CCTV.