Time-resolved sign-dependent switching in a hybrid aligned nematic liquid crystal cell

Copyright © 2008 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is the published version of an article published in New Journal of Physics Vol. 10, article 083045. DOI: 10.1088/1367-2630/10/8/083045An optical waveguide technique is used to determine the director tilt profile across a hybrid aligned nematic (HAN) liquid crystal cell, in which the optical response is dependent on the sign of the applied voltage. Two physical models are shown that fit the equilibrium experimental data, but with alternative explanations for this sign dependence. Models with either a flexoelectric coefficient of 2.25×10−11 C m−1 or a bound surface charge of 12.2 μC m−2 are shown that fit this equilibrium data. In an attempt to resolve this degeneracy sign-dependent switching data are analysed. However, neither model can explain these switching data, which are affected by slow transients of ~100 ms which are believed to be due to the motion of free ions in the liquid crystal. From the form of these slow transients, it is suggested that the equilibrium position of the ions is next to a cell substrate

Dependence of the lateral ion transport on the driving frequency in nematic liquid crystal displays

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10-4: Ion Currents in In-Plane Switching Liquid Crystal Displays.

In liquid crystal (LC) devices where the electrode structure has a microscopic pattern, as in In-Plane-Switching (IPS), ion transport is essentially two-dimensional. In this paper we report the measurements of ion transport currents in IPS devices. The time dependency of these currents is explained qualitatively. 1

P-33: The Non-uniform Theory Simulations of the Continuous Director Rotation Mode of FLCD’s

We introduce the theoretical model of LC material with the phase sequence I-N *-SmC * as a material having suitable properties for multimedia applications (fast speed, high contrast and full grey scale capabilities). We present the structure and investigate the switching and the optical response of the device taking into account material and technological parameters. We explain the mechanism of the continuous switching mode and prove the ability of using grey levels. 1

3-dimensional ion transport in liquid crystals

One-dimensional ion transport has been studied in the past decade because of the importance of image retention and voltage holding ratio. Ions inside a liquid crystal (LC) disturb the expected optical behavior of LC molecules when the applied voltage is higher than the LC threshold. In LC devices with complex electrode patterns, interesting ionic effects occur. Advanced and reliable simulation programs are a necessary to investigate this. This paper describes the theory and results of a Monte Carlo 3D ion transport simulation program for LC devices