• Title/Summary/Keyword: NS/NT PDLC

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Study on the Electro-Optic Characteristics Depending on UV Condition in the Normally Scattering(NS)/Normally Transparent(NT) Polymer Dispersed Liquid Crystal Mode (Normally Scattering(NS)/Normally Transparent (NT) 고분자 분산형 액정 모드에서 UV 조건에 따른 전기 광학특성 연구)

  • Kim, M.S.;Seo, Y.H.;Lee, M.H.;Rhee, J.M.;Lee, T.S.;Lee, S.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.1050-1053
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    • 2003

  • Polymer dispersed liquid crystal mode can be classified into two cases, normally scattering mode (NS) and normally transparent (NT) mode according to an initial state. Electro-optic characteristic NS/NT PDLC mode can be improved by controlling the factors to influence the phase separation. In case of NS PDLC mode, we inspected change of a phase separation as a function of curing temperature for the mixture of E7 and NOA65 with different ratios. When the LC concentration is less than polymer such as LC : NOA65 = 40 : 60wt%, the PDLC cell is influenced strongly by the curing temperature. However, when LC concentration is much less than polymer such as LC : NOA65 : 80 : 20wt%, it is influenced slightly by the curing temperature. In case of NT PDLC mode, we observed change of a phase separation as a function of the ratio of the mixture and UV conditions such as curing temperature, UV intensity The cell made with strong UV intensity and curing temperature of $20^{\circ}C$, in case that the ratio of LC to polymer is 70:30wt%, showed good electro-optic characteristics.

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Electro-Optic Characteristics of Polymer Dispersed Liquid Crystal Cell with Transparent State Initially (초기에 투명한 상태인 고분자 분산형 액정셀의 전기 광학 특성)

  • 김미숙;원해경;송성훈;이명훈;이승희
    • Polymer(Korea)
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    • v.28 no.4
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    • pp.298-304
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    • 2004

  • We fabricated a polymer dispersed liquid crystal (PDLC) cell using LC with negative dielectric anisotropy and UV curable monomer exhibiting transparent state initially (called normally transparent (NT)) and studied the electro-optic characteristics. The NT PDLC cell made with the ratio of LC : monomer = 70/30 wt%, curing temperature of 20 $^{\circ}C$ and strong UV intensity of 198 ㎽/$\textrm{cm}^2$ had high contrast ratio and showed good electro-optic characteristics. In this condition, LC is aligned vertically on the substrate due to the vertical alignment layer and the polymer made with the UV exposure does not influence the alignment of the LC much. Therefore, the transmittance at the zero voltage is very high and the scattering state of the cell is good after applying the voltage because LC with negative dielectric anisotropy tries to align perpendicular to the field. And also, the NT PDLC cell showed better viewing angle characteristics than that in the normally scattering (NS) PDLC.

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