Browse Prior Art Database

Method of Producing Layer-Normal Bistable Surface-Stabilized Ferroelectric Liquid Crystal Devices

IP.com Disclosure Number: IPCOM000035116D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Lien, ASC: AUTHOR [+2]

Abstract

Disclosed is a method of producing a layer-normal bistable liquid crystal device by first using a rubbing alignment to produce a layer-tilted state. Boundary regions of the liquid crystal are converted to the layer-normal state by heating the boundary regions into the nematic phase, while simultaneously applying an electric field across the liquid crystal.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 2

Method of Producing Layer-Normal Bistable Surface-Stabilized Ferroelectric Liquid Crystal Devices

Disclosed is a method of producing a layer-normal bistable liquid crystal device by first using a rubbing alignment to produce a layer-tilted state. Boundary regions of the liquid crystal are converted to the layer-normal state by heating the boundary regions into the nematic phase, while simultaneously applying an electric field across the liquid crystal.

Using X-ray scattering, it has been proved [1] that only layer- tilted states are obtained in surface-stabilized ferroelectric liquid crystal (SSFLC) de- vices by either rubbing or shearing alignments, which yield a low pretilt angle. A low pretilt and a large layer-tilt angle excludes the possibility of bistable layer-normal ori- entation of a SSFLC device. In a layer-tilted geometry, bistability has been reported [2] when the pretilt angle is as large as the cone angle of the FLC medium. Such high pretilt angles are achieved by using oblique evaporation as an alignment method, which is expensive, unreliable, and unsuitable for inexpensive manufacture. This article describes a fabrication method to achieve layer-normal (LN) bistable SSFLC devices. This method utilizes rubbing alignments so that it is suitable for inexpensive manufacture.

For the first step, we use the conventional method of rubbing alignment to achieve a layer-tilted (LT) state. A typical LT FLC cell has the FLC medium sandwiched between two indium-tin-oxide (ITO)-coated glass plates.

To change the non-bistable LT state into a bistable LN state, the cell is biased a few degrees centigrade below the nematic (or smectic A)-to-smectic C transition temperature. A voltage pulse with suitable amplitude and pulse-width is applied across the FLC medium. At the same time, light from a pulse infrared laser, such as neodymium-doped glass or YAG...