Liquid Crystal Mixtures with Low Birefringence for Active-Matrix LCD

Abstract

The liquid crystal (LC) mixtures with fused ring systems such as Decahydronaphthalenes and Tetrahydronaphthalenes for reflective or transflective active-matrix liquid crystal display (AM-LCD) have higher durability than LC mixtures with ester-components. These LC mixtures also have some problems such as low nematic-isotropic transition temperature T NI and high driving voltage. The improvement for driving voltage was carried out by using Tetrahydronaphthalene-component with moderate birefringence Dn and large dielectric anisotropy De. However, It was difficult to obtain LC mixtures with sufficiently low driving voltage, because of low T NI and the comparatively high Dn of tetrahydronaphthalene.We have improved these problems by introducing some newly developed LC components and optimization. We obtained the LC mixtures with low Dn and low driving voltage; less than 0.075 of Dn and about 4 V or less of driving voltage. These LC mixtures have high durability with stable nematic phase at low temperature.

Ferroelectric Liquid Crystal Material with Low Birefrigence

“…Nematic liquid crystal (NLC) materials with low birefringence (Δn ~ 0.05-0.1) have been used in activematrix displays since 1984 [1]. The point is that with decreasing of birefringence, a reduction in the chromatic aberrations of the NLC based electro-optical cells has been achieved [2][3][4][5]. The derivatives of cyclohexyl-cyclohexanes, perfluorinated derivatives of aromatic compounds and derivatives of trans-1,3dioxanes are usually used as components of NLC materials with low birefringence [3].…”