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Proceedings Paper

Exploring motion reversal in polymer cholesteric liquid crystal devices
Author(s): T. Z. Kosc; C. J. Coon; G. V. Babcock; K. L. Marshall; A. Trajkovska-Petkoska; S. D. Jacobs
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Paper Abstract

Polymer cholesteric-liquid-crystal (PCLC) flakes suspended in a fluid are used as the active medium in a novel particle-based, electro-optic technology. The motion of PCLC flakes is controlled with an electric field so that PCLC flake devices are brightly reflective in their "off" state and appear dark when an electric field is applied, causing the flakes to reorient 90°. Basic devices using a mildly conductive host fluid such as propylene carbonate are not bistable, and flakes relax to their original position within tens of seconds to minutes after the electric field is removed. We seek to control flake orientation by designing waveforms that follow the initial drive voltage. Shaped pulses were investigated to accelerate flake relaxation. The optimal pulse for motion reversal was found to be a 1.5-s sawtooth pulse with a 3-V amplitude. We also examined the use of holding voltages, which follow the driving voltage, but have amplitudes a fraction of the driving-voltage magnitude. The holding voltage prevents flakes from relaxing, while saving on power consumption. Cells driven at several volts were found to retain their brightness with the application of a holding voltage between 0.4 to 0.5 V.

Paper Details

Date Published: 15 September 2006
PDF: 9 pages
Proc. SPIE 6332, Liquid Crystals X, 633209 (15 September 2006); doi: 10.1117/12.678053
Show Author Affiliations
T. Z. Kosc, Univ. of Rochester (United States)
C. J. Coon, Univ. of Rochester (United States)
G. V. Babcock, Univ. of Rochester (United States)
K. L. Marshall, Univ. of Rochester (United States)
A. Trajkovska-Petkoska, Univ. of Rochester (United States)
S. D. Jacobs, Univ. of Rochester (United States)
The Institute of Optics, Univ. of Rochester (United States)

Published in SPIE Proceedings Vol. 6332:
Liquid Crystals X
Iam-Choon Khoo, Editor(s)

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