• Title/Summary/Keyword: Optically compensated Bend

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Realization of Optically Compensated Bend State using Surface Polymer Stabilization

  • Jeon, E.J.;Kang, B.G.;Kwon, D.W.;Lim, Y.J.;Lee, M.H.;Lee, S.H.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.657-660
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    • 2009
  • Optically compensated bend (OCB) mode has intrinsic characteristics such as wide viewing angle and fast response time. However, in order to operate the OCB mode in bend state, this device needs quick transitions from the initial splay state to bend state. In this paper, we proposed OCB mode with initially bend state using reactive mesogen (RM) monomer for surface polymer stabilization. The device shows continuous reorientation of the LC with applied field and a very fast response time.

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Optically Compensated Bend Cell with Pixel-Isolating Polymer Wall for a Flexible Display Application

  • Lee, Seong-Ryong;Lee, Joong-Ha;Jang, Hong-Jeek;Yoon, Tae-Hoon;Kim, Jae-Chang
    • Journal of Information Display
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    • v.8 no.4
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    • pp.5-9
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    • 2007
  • We demonstrate an optically compensated bend (OCB) cell with pixel-isolating polymer wall. The polymer wall is formed by anisotropic phase separation of LCs and UV-curable polymer. The fabricated cell is initially in ${\pi}-twisted$ state so that it shows uniform and fast bend transition without any transition nucleus. The proposed cell has lower driving voltage than conventional OCB cell. Also, the polymer wall provides mechanical stability, hence preventing distortion of display image from external pressure.

Optically compensated bend cell with pixel-isolating polymer wall for a flexible display application

  • Lee, Seong-Ryong;Lee, Joong-Ha;Jang, Hong-Jeek;Jo, Jin-Seok;Yoon, Tae-Hoon;Kim, Jae-Chang
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.207-210
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    • 2007
  • We fabricated an optically compensated bend cell with pixel-isolating polymer wall. The polymer wall was formed by phase separation of LCs and UVcurable polymer. The fabricated cell had initially ${\pi}-twist$ state. It showed low driving voltage, wide viewing angle and fast response properties. Also, polymer wall provided the mechanical stability preventing distortion of a display image from pressure.

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Study on Electric characteristics of Optically Compensated Bend formed initially bend state by Reactive Mesogen monomer (RM 단분자를 이용한 초기 밴드 상태 OCB 셀의 전기적 특성 연구)

  • Jeon, Eun-Jeong;Kim, Seong-Su;Lim, Young-Jin;Lee, Myoung-Hoon;Lee, Seung-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.04a
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    • pp.49-50
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    • 2008
  • OCB mode has advantages such as fast response time and wide viewing angle. But it has inevitable shortcoming which initial splay state must be changed to bend state. To overcoming this problem, OCB cell filled LC with RM monomer was cured by UV when voltage applied. Through previously mentioned methods, even if electric field is none, bend state was made by stabilized LC director. In this paper, we investigated the electric characteristics of polymer stabilized OCB mode.

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A Novel Fast-Switching LCD with Dual-Domain Bend Mode

  • Satake, Tetsuya;Kurata, Tetsuyuki
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.209-212
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    • 2004
  • A navel fast-switching LCD with dual-domain bend (DDB) mode is described DDB alignment is achieved using antiparallel-rubbed cell filled with chiral-doped LC. Initial alignment is mono-domain 180-degree twist. Tilt direction is controlled by oblique electric field to be counter direction in each domain Twist-to-DDB deformation occurs continuously so that DDB mode does not require high-voltage initialization which is inevitable in Optically Compensated Bend (OCB) mode. DDB gives wide and symmetric viewing angle in contrast to mono-domain bend formed from 180-degree twist showing strong asymmetry.

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Simulation of Liquid Crystals Considering Flow Effect (흐름효과를 고려한 액정의 시뮬레이션)

  • Kim Hoon;Park Woo-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.3
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    • pp.260-266
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    • 2006
  • In this paper, We coupled fluid balance and director balance equation from Ericksen-Leslie's continuum theory and observed the motion of Liquid Crystal molecular. We simulated flow velocity and director distribution in which flow effect is considered in switching on and switching off state. We interpreted the dynamic response characteristic caused by the flow. As the result of the simulation, We could see the flow effect. In the case of Twisted Nematic(TN) cell, this flow caused abnormal twist temporarily 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. In addition, We analyzed the mechanism of the fast response due to flow in the case of Optically Compensated Bend(OCB) cell.

Recent Development of Optically Compensated Bend (OCB) Mode TFT-LCD

  • Wakemoto, Hirofumi;Nishiyama, Kazuhiro;Nakao, Kenji;Takimoto, Akio
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.562-566
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    • 2005
  • Toshiba Matsushita Display Technology (TMD) has firstly succeeded in mass production of OCB (Optically Compensated Bend) mode liquid crystal display panels which have excellent moving picture quality almost the same as CRT. We have newly developed 32 -inch diagonal HD ($1366{\times}768\;pixels$) panels using OCB mode and low temperature p-Si TFT (LTPS) array substrates. High performance of brightness of $600cd/m^2$ and contrast ratio of 600 : 1 was obtained by using pseudo-impulse driving method to insert a black period between continuous two frames, and also by using blinking backlight method. Furthermore, moving picture response time (MPRT) 6.5ms has been obtained by optimization of black insert driving and backlight blinking, without the great sacrifices of contrast ratio and luminance.

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Study on Electro-opt ic Characteristics in the Optically Compensated Splay Cell with UV-curable Reactive Mesogen

  • Kim, Seong-Su;Jeon, Eun-Jeong;Lee, Myong-Hoon;Lee, Seung-Hee
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.327-329
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    • 2008
  • We have studied the optically compensated splay (OCS) mode using reactive mesogen monomer to reduce critical voltage, setting voltage and phase transition time from initial bend to splay state. The high pretilt angle from vertical alignment was formed through the polymerization of UV curable RM monomer at the surfaces. In this way, orientation of the LC with OCS can be achieved without setting voltage.

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A Novel LC Device Associated with Optically Compensated Splay Structure (광학적 자기 보상 스플레이 구조를 갖는 새로운 액정 소자)

  • 김승재;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.536-540
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    • 2004
  • A novel nematic liquid crystal (LC) cell with splay structure exhibiting wide viewing angle, fast response time and high transmittance at the same time has been developed. With rubbed homeotropic alignment in parallel directions, the device shows bend alignment in the absence of vertical electric field. However, with applied high voltage in a pulse form, the LC shows a optically compensated splay (OCS) orientation such that the mid-director is parallel to a substrate and at both surfaces the LCs are aligned vertically in parallel direction. In the device, the birefringence of the cell becomes tunable with applying voltage, i.e., the amount of light passed through the cell can be controlled by controlling the orientation of the LC. Since the OCS cell has a self-compensation structure such that the LC has a mirror symmetry along the mid-director, the device shows a wide viewing angle with only a single domain and a fast response time.