30 April 2003 Advanced liquid crystal materials with negative dielectric anisotropy for monitor and TV applications
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The Vertically Aligned (VA) technology is one of the newer modes of operation among TFT displays. For VA displays, the liquid crystal is aligned homeotropically and possess a negative dielectric anisotropy (De<0) in order to switch perpendicular to an applied electric field. A new generation of nematic LC materials has been developed which reduces rotational viscosity (g1) but keeps other important parameters unchanged. The switching time parameter, g1/Dn2, is compared with those of previous reference mixtures possessing a range of optical anisotropies. The results show that the new mixtures give a consistent reduction in g1/Dn2 for a wide spread of Dn. Reduction in threshold voltage (V0) is an important goal for the majority of applications and can be achieved by increasing the absolute magnitude of (formula available in paper). However this in turn increases rotational viscosity (g1). The new mixtures overcome this drawback and significantly decrease the values of g1/Dn2 over a wide range of V0. A requirement for TV displays is increased brightness. The result is an increased operating temperature and therefore, higher clearing temperatures of the LC mixtures are demanded, but they lead to higher g1. The new LC components were successful in reducing g1/Dn2 in comparison with the previous standards for a range of clearing points.
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Seung-Eun Lee, Eun-Young Kim, Doo-Jin Kang, Thomas Jacob, Melanie Klasen-Memmer, Matthias Bremer, and Kazuaki Tarumi "Advanced liquid crystal materials with negative dielectric anisotropy for monitor and TV applications", Proc. SPIE 5003, Liquid Crystal Materials, Devices, and Applications IX, (30 April 2003); doi: 10.1117/12.482774; https://doi.org/10.1117/12.482774

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