폴리머 네트워크가 형성된 TN 액정셀의 고속응답 특성
Fast Switching of a Polymer-networked Twisted Nematic Liquid Crystal Cell
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본 논문에서는 광학적으로 비등방성인 폴리머를 이용하여 90° TN(Twisted Nematic) 액정셀의 응답시간을 향상시키는 방법을 제안하였다. 액정과 비등방성 폴리머를 일정 비율로 혼합하여 TN 액정셀에 주입한 뒤 UV를 조사하여 폴리머 네트워크를 형성시킴으로써 투과율에 영향을 주지 않고 응답시간을 향상시킬 수 있다. 폴리머 네트워크가 형성되지 않은 TN 액정셀의 turn-off 시간이 16 ms인데 반해 제안된 방법에서는 액정과 비등방성 폴리머의 혼합 비율이 3, 5, 10 wt%로 증가할 때 12, 11, 9 ms로 고속 turn-off가 구현될 수 있다. 또한, turn-off 동작 시 TN 액정셀에서 발생하였던 delay time과 backflow가 폴리머 네트워크의 형성에 의해 크게 개선됨을 확인하였다.
Abstract
We propose a method to enhance the response time of a twisted nematic liquid crystal (TN-LC) cell using an anisotropic polymer. Polymer networks are formed by the phase separation between a LC and a UV-curable polymer. A TN-LC cell is exposed to UV light after the mixture of LC and anisotropic polymer is injected into the TN-LC cell. As a result, turn-off time of a TN-LC cell can be decreased remarkably without any loss of the transmittance. The turn-off time of a TN-LC cell with pure LC was 16 ms, but those of polymer networked TN-LC cells were 12, 11, and 9 ms when the concentration of the polymer was 3, 5, and 10 wt%, respectively. Moreover, by virtue of the polymer network, the backflow effect and the delay time generated during the turn-off process disappeared.
참고문헌 (18)
- S. T. Wu, "Reflective Liquid Crystal Displays" (2001), Wiley
- S. T. Wu, "Fundamentals of Liquid Crystal Devices" (2006), Wiley
- S. Nagata, "Capacitively coupled driving of TFT-LCD", Proc. SID Int. Symp. Dig. Tech. Pap, pp.242~245 (1989)
- J. L. West, "Stressed liquid crystals for electrically controlled fast shift of phase retardation", Proc. SID Int. Symp. Dig. Tech. Pap, pp.1469~1472 (2003)
- P. J. Bos, "The π-cell, a fast liquid-crystal optical switching device", Mol. Cryst. Liq. Cryst, 113, pp.329~339 (1984)
- C. Y. Xiang, "A fast response, three-electrode liquid crystal device", Jpn. J. Appl. Phys, 42, pp.763~765 (2003)
- C. Y. Xiang, "The electro-optic properties of a vertically aligned fast response liquid crystal display with three-electrode driving", J. Phys, 37, pp.994~997 (2004)
- J. L. West, "Fast birefringent mode stressed liquid crystal", Appl. Phys. Lett, 86 (2005)
- J. S. Gwag, "Electrically tilted liquid crystal display mode for high speed operation", Jpn. J. Appl. Phys, 45, pp.7047~7049 (2006)
- C. Y. Huang, "Fast switching of polymer-stabilized liquid crystal pi cells", Appl. Phys. Lett, 90 (2007)
- J. I. Baek, "Fast turn-off switching of a liquid crystal cell by optically hidden relaxation", Proc. SID Int. Symp. Dig. Tech. Pap, pp.1846~1849 (2008)
- K. H. Kim, "Quasi-impulsive driving for high-speed operation of a homogeneous aligned LC cell with 3-electrode structure", Proc. SID Int. Symp. Dig. Tech. Pap, pp.673~676 (2009)
- J.-I. Baek, "Fast in-plane switching of a liquid crystal cell triggered by a vertical electric field", Jpn. J. Appl. Phys, 48 (2009)
- J.-I. Baek, "Fast switching of vertical alignment liquid crystal cells with liquid crystalline polymer networks", Jpn. J. Appl. Phys, 48 (2009)
- C. Z. van Doorn, "Dynamic behavior of twisted nematic liquid-crystal layers in switched fields", Jpn. J. Appl. Phys, 46, pp.3738~3745 (1975)
- F. Nakano, "Dynamic properties of twisted nematic liquid crystal cells", Jpn. J. Appl. Phys, 19, pp.659~663 (1980)
- C. H. Gooch, "The optical properties of twisted nematic liquid crystal structures with twist angles ≤ 90", J. Phys. D: Appl. Phys, 8, pp.1575~1584 (1975)
- 김기한, "꼬인 네마틱 액정 셀의 Normally Black 모드 광학설계", 한국광학회지, 19(1), pp.48~53 (2008), 한국광학회