• Title/Summary/Keyword: Twisted Nematic

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Electro-Optical and Switching Behavior of In-plane Switching Twisted Nematic Liquid Crystal Display

  • Kimura, Munehiro
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.1092-1095
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    • 2003
  • A driving mechanism and excellent features for an in-plane switching twisted nematic liquid crystal mode (IT mode) that could possibly improve the viewing-angle and color shift characteristics and the cell gap error tolerance is proposed. .It is important that the surface azimuthal anchoring strength of the liquid crystal cell differs at the upper and lower substrates. Furthermore. as a rubbing-free LCD. amorphously aligned in-plane switching twisted nematic mode (a-IT mode) is also demonstrated.

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High-brightness and wide-view transflective liquid crystal display with two in-cell imprinted optical films in an inverse-twisted-nematic geometry

  • Na, Jun-Hee;Cho, Seong-Min;Lee, Sin-Doo;Lim, Yong-Woon
    • Journal of Information Display
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    • v.12 no.1
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    • pp.11-15
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    • 2011
  • An inverse-twisted-nematic (ITN) transflective (TRF) liquid crystal (LC) display, where two imprinted optical films (IOFs) with surface microstructures are embedded was developed. One of the IOFs serves as an in-cell patterned retarder with multioptic axes, and the other behaves as a viewing-angle enhancement film. In the presence of an applied voltage, the surface microstructures on the IOFs provide the spontaneous twist of the LC from a vertically aligned state to a $90^{\circ}$ twisted-nematic (TN) state in the transmissive part, and to a $45^{\circ}$ TN state in the reflective part. The developed ITN TRF LC display exhibits high transmission and reflectance, fast response, and wide-viewing characteristics, along with achromaticity.

Analysis on the Flow Effect of the Twisted Nematic liquid Crystals (Twisted Nematic(TN) 액정에서의 흐름효과 해석)

  • Kim, Hoon;Park, Woo-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.76-78
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    • 2005
  • We coupled fluid balance equation and director balance equation from Ericksen-Leslie's continuum theory and observed the motion of Twisted Nematic (TN) Liquid Crystals. We simulated flow velocity distribution and director distribution. We interpreted the dynamic response characteristic caused by the flow. As the result of the simulation, We could see the flow effect. And this flow caused abnormal twist to 4msec in switching off state. We could prove that this abnormal twist is a direct cause of optical bounce phenomenon known well until now with the result of simulation.

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Study on transmittance improvement of 90 twisted nematic liquid crystal display driven by fringe-electric frield (Fringe 전기장 구동 Twisted Nematic 액정 디스플레이의 투과율 향상 연구)

  • Ryu, Je-Woo;Lee, Ji-Youn;Lim, Young-Jin;Jeon, Yeon-Mun;Lee, Seung-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.06a
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    • pp.446-447
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    • 2006
  • We investigated the electro-optic characteristics of a fringe-field driven twisted nematic (TN) display using a LC with negative dielectric anisotropy depending on electrode structures. The fringe-field driven TN mode known to exhibit wide viewing angle and excellent color characteristics over a wide viewing range and high transmittance. However, when the electrode width and distance between them is large enough, the transmittance is lower than the conventional vertical field-driven TN mode. By narrowing the electrode width and distance, the transmittance reaches the same value of the conventional TN mode.

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A Study on the Characteristics of Novel Pseudo-TN IPS Mode LC Cell (새로운 Pseudo-TN IPS 모드 액정 셀에 대한 특성 해석 연구)

  • 윤형진;윤석인;윤상호;원태영
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.8
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    • pp.59-65
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    • 2004
  • In this paper, we propose Pseudo-TN IPS mde(Pseudo-Twisted Nematic In-Plane Switching mode) based on IT(In-plane switching Twisted nematic) mode that increase contrast ratio from improving optical characteristics and analyze the characteristics of Pseudo-TN IPS uude. Optical transmittance is 25% higher for the PTN-IPS mode than for the IT mode. Because aperture ratio of the PIN-IPS is increased. And the control of Liquid Crystal for adjusting optical transmittance is more easier than IT mode, because optical transmittance variation is linear with applying voltage. Contrast ratio is 8% lower for the PTN-IPS mode than for the IT mode in the horizontal direction. But, Contrast ratio is 20% higher for the PTN-IPS mode than for the IT mode in the vertical direction. It has also cell gap margin and many benefits of IT mode, this may be used very well in the future LC Cell design.

A Study on Fast Response Time for Twisted Nematic Liquid Crystal Display

  • Lee, Kyung-Jun;Jeon, Yong-Je;Hwang, Jeoung-Yeon;Seo, Dae-Shik;Jeon, Youn-Hak;Nam, Sang-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.04b
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    • pp.121-123
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    • 2002
  • Fast response characteristics of twisted nematic liquid crystal display (TN-LCD) cell with different nematic liquid crystals (NLCs) and cell gap on a rubbed polyimide (PI) surface were studied. High transmittance and fast response time of the TN-LCD on the rubbed PI surface were achieved by using high birefringence ($\Delta$ n) and low cell gap. It is considered that the transmittance and response time of the TN-LCD on the rubbed PI surface decreased as $\Delta$ nd decrease.

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Polarity Effects of Dielectric Anisotropy on Electro-Optical Characteristics of Fringe Field Twisted Nematic Mode

  • Shin, Sung-Sik;Jhun, Chul-Gyu;Kim, Woo-Young
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.288-288
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    • 2009
  • We have studied polarity effects of dielectric anisotropy effects on electro-optical characteristics of a twisted nematic mode driven by fringe electric field, which has wide viewing angle characteristics. Our device is designed as normally black mode between parallel polarizers. The perfect polarization conversion of incident light, which passes through a polarizer, is achieved, when it passes through the twisted liquid crystal (LC) layer. If an electric field is applied, the LC molecules with a positive (or negative) dielectric anisotropy rotate parallel (or perpendicular) to the horizontal component of a fringe electric field as increasing transmittance. From the calculated results, enhanced transmittance of the fringe field-twisted nematic (FF-TN) mode with positive dielectric anisotropy of + 8.2 can be obtained.

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Consideration into method of deciding upon extraordinary axis direction in Twisted-Hematic LC ($90^{\circ}C$꼬인 네마틱 액정 ($90^{\circ}C$ Twisted-Nematic LC)의 이상 굴절 축($n_e$ axis) 방향 결정 방법에 대한 고찰)

  • 조규보;신창목;서동환;배장근;김수중
    • Proceedings of the IEEK Conference
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    • 2002.06b
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    • pp.267-270
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    • 2002
  • LCD is not very expensive and according to the principle that twisted-nematic LCD can modulate by electric signal, lots of researches been developed about many of theory, methods of design and calculating parameters effectively. In 1999 J. A. Davis et ai. proposed the method of deciding upon extraordinary and ordinary axis direction, which is based on Blazing Effect, inspect into changes of diffraction patterns. But in laboratory, it is difficulty to observe 5th or 6th diffraction pattern, and not clear in mathematical. In this paper, illuminating circular polarized beam been to TN LCD (twisted-nematic LCD), we found extraordinary axis direction with inspecting into maximum intensity distribution appeared in the side of analyzer Using Jones matrix method, we endowed with mathematical propriety.

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Study on Electro-optic Characteristics of Fringe-field Switching Twisted Nematic Mode using a Liquid Crystal with Negative Dielectric Anisotropy (유전율 이방성이 음인 액정을 이용한 Fringe-field Switching Twisted Hematic 모드의 전기광학 특성 연구)

  • 송일섭;신성식;이종문;이승희
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.5
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    • pp.530-535
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    • 2004
  • We have studied 90$^{\circ}$ twisted nematic mode switching by fringe electric field(F-TN mode) using a liquid crystal (LC) with negative dielectric anisotropy. In the device, two polarizers are parallel each other, electrodes exist only on bottom substrate, and one of rubbing direction is coincident with polarizer axis. Therefore, the cell shows a black state before a voltage is applied. With a bias voltage generating fringe-electric field, the LC twists perpendicular to fringe electric field such that the LCs are almost homogeneously aligned except near the bottom surface since the negative type of the LC is used. Consequently, the new device exhibits much wider viewing angle than that of the conventional TN mode due to in-plane switching and relatively high transmittance since the LC director above whole electrode area aligns parallel to the polarizer axis.

Carbon Nanotube Effects on Physical Properties of Liquid Crystal and Electro-Optic Characteristics of Twisted Nematic Liquid Crystal Cell (카본나노튜브가 액정의 물성과 Twisted Nematic 액정 셀의 전기광학 특성에 미치는 영향)

  • Jeon, S.Y.;Jeong, S.J.;Jeong, S.H.;Shin, S.H.;An, K.H.;Lee, S.E.;Lee, S.H.;Lee, Y.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.04a
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    • pp.41-42
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    • 2006
  • Carbon nanotubes (CNTs) effects on physical properties of the liquid crystal and twisted nematic (TN) liquid crystal (LC) cells have been investigated. The minute doping of CNTs reduces rotational viscosity of the LC, and thus switching time of the TN cells is improved, especially in grey scale response time. In addition, the dielectric anisotropy and birefringence are not affected by such a small amount of CNT-doping and thus voltage-dependent transmittance remains the same.

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