• 한국광학회지
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• 제22권1호
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• pp.23-29
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• 2011

쌍안정 카이랄 스플레이 네마틱 액정표시소자는 스플레이 상태와 $-\pi$ 꼬인 상태를 쌍안정 상태로 사용하는 메모리 액정표시소자이다. 셀 갭/피치의 값이 0.25일 경우 완전한 쌍안정 상태를 갖지만, $-\pi$ 꼬인 상태에서 스플레이 상태로 전이시키기 위하여 fringe 전계를 인가할 경우 픽셀영역은 전계의 왜곡에 의해서 완전한 스플레이 상태가 아니라 $-\pi$ 꼬인 상태를 부분적으로 유지하게 된다. 본 논문에서는 화소영역에서 두 안정한 상태가 공존하지 않는 $-\pi$ 꼬인 상태를 어두운 상태로 사용하는 반사형 쌍안정 카이랄 스플레이 네마틱 액정표시소자를 제안한다. 제작된 반사형 액정표시소자는 30:1의 고명암비를 나타냈으며, 응답속도는 수직전압 8 V, fringe 전압 12 V의 구동 전압으로 각각 쓰기 응답시간이 950 ms, 리셋 응답시간이 450 ms였다. 또한 제안된 셀은 +C 광학 보상 필름을 사용하여 좌우 방향에서 $180^{\circ}$의 광시야각을 나타냈다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.489-492
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• 2005

We report new polymer stabilized ferroelectric liquid crystal (PSFLC) cells with mechanical stability which is achievable by introducing photospacers in the cells. It was found that the mechanical st ability of the PSFLC cell was effected by introduction of photo spacers. We analyzed the dependence of mechanical stability and memory property on the density of photospacers in the PSFLC cell. The stability and memory properties of PSFLC Cells depending on photospacer density are discussed. 1. Introduction Recently, flexible displays have attracted much attention because they have remarkable advantages: thinner, lighter, non-breakable and conformable features. Flexible displays have various potential applications such as e-book and e-paper displays utilizing the distinct features. E-book and E-paper displays demand very low power consumption, so that bistable memory liquid crystal modes are required in case of flexible plastic LCDs for those application. Three kinds of memory LC modes have been developed; bistable nematic, bistable cholesteric and bistable FLC. Among them SSFLC as one of bistable FLC has big advantages such as low driving voltage, wide view angle and fast response time, SSFLC cells are, however, very weak against mechanical shock. Polymer stabilized FLC (PSFLC) has been developed to overcome the poor mechanical stability of SSFLC. PSFLC was known to have network structure that FLCs are oriented with smectic layer ordering in polymer network. The polymer network stabilizes the FLC orientation, which leads to improvement of mechanical stability of PSFLCD. A lot of studies have been done for the application of PSFLC to flexible $LCDs.^{[1{\sim}12]}$ However, it should be noted that PSFLC does not have sufficient mechanical stability for the particular applications such as smart card LCD, where LCD is highly bendable.Bead spacer was mainly used to maintain cell gap of conventional PSFLCDs. But the spacer density of it is not locally uniform in the cell, so that it is generally difficult that the PSFLCDs with bead spacers show sufficient mechanical stability. In order to more improve the mechanical stability of PSFLCDs, we introduced photospacers into PSFLCDs. In this paper, we describe the improvement of mechanical stability by introducing photospacers into PSFLCDs.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.555-558
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• 2003

The bistability in a chiral-splay nematic liquid crystal cell, which is obtained by adding a chiral additive to a splay cell, is proposed. In this paper, we describe a new horizontal way of switching between the two states of the bistable chiral-splay cell, one state being characterized by a non-twisted director field with splay, the second state showing a director-field with $180^{\circ}C$ twist.

• Journal of Information Display
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• 제12권4호
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• pp.195-198
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• 2011

Proposed herein is a flexible bistable chiral splay nematic display mode with an enhanced memory retention time under external distortion. By adopting the polymerized reactive-mesogen structure mixed in a liquid crystal layer, local anchoring energy is generated on the boundary between the polymer structures, and the relaxation from the ${\pi}$-twisted state to the initial splay state could be interrupted. As a result, the memory retention time becomes significantly longer, and the stability against the external distortion is enhanced.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.476-479
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• 2005

We developed a plastic bistable LCD based on the suspension of sub-micron ferroelectric particles in a cholesteric liquid crystal. 2.5 inch $160{\times}160$ pixel display with enhanced contrast and improved electro-optical characteristics was achieved. The display is extremely light and possesses good flexibility, demonstrating multifold bending in a radius about 1.5 cm.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.215-217
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• 2009

The authors propose a novel dual mode liquid crystal display (LCD) which has both dynamic and memory operating LCD modes. The mode uses a horizontal switching and bistable chiral splay nematic (BCSN) LCD. The proposed dual mode does not require pixeldivision and has a higher aperture ratio and resolution than the previously proposed dual mode. Experimental results of the memory and dynamic mode show a high contrast ratio of over 100:1.

• 한국광학회지
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• 제10권4호
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• pp.279-282
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• 1999

본 논문에서는 LCD의 어두운 상태의 특성을 보완하기 위해 광대역 λ/4 보상판을 사용하여 단일 편광판 모드 반사형 쌍안정 TN LCD를 설계·제작하였다. 단일 편광판 모드에서 광대역 λ/4 보상판의 필요성을 이론적인 계산과 실험을 통해 확인하였고, 시험적ㅇ로 제작한 단일 편광판 모드 반사형 쌍안정 TN LCD는 기존 구조의 반사형 쌍안정 TN LCD와의 비교에서 더욱 밝은 디스플레이 특성을 나타내었다. 본 실험에서 우리는 10:1의 콘트라스트를 얻었다.

• 한국광학회지
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• 제11권2호
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• pp.130-134
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• 2000

본 논문에서는 명암대비와 밝기를 높일 수 있는 반사형 쌍안정 TN셀의 광학 조건을 최적화 하였다. 세 파장(450 nm, 550nm, 650nm)의 광 특성에 미치는 영향을 살펴보았다. 그 결과 편광판 각도를 다른 광학 파라미터보다 더욱 정밀하게 제어해야 하며, dΔn 값이 밝은 상태의 색 특성에 영향을 미침을 알 수 있었다. 광대역 Ν4 필름을 사용해서 반사형 쌍안정 TN셀을 제작해 10.6:1이라는 명암대비를 얻었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1525-1528
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• 2006

So far, monostable and bistable LCD modes have independently been researched and developed. We introduce a novel liquid crystal display device that and be operated ad memory mode ad well ad dynamic mode. This device has a unique texture of splay, ${\pi}$ twist and bend states with applied voltages and is operated as a memory mode or dynamic mode by selective switching of two states among them. We also demonstrate electro-optical characteristics of the transmissive dual mode.

• Journal of Information Display
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• 제10권4호
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• pp.184-187
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• 2009

A liquid crystal device with switchable dynamic and memory modes was investigated and developed. The proposed device reveals the splay, $\pi$-twist, and bend states via selective switching among them. In the dynamic mode, the device is operated in the bend state, which exhibits a wide viewing-angle and a fast-response-time due to its self-compensated bend structure and flow-accelerated fast response time, respectively. In the memory mode, the permanent memory characteristics in the splay and $\pi$-twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed.