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Substrate Treatment for Liquid Crystal Display

IP.com Disclosure Number: IPCOM000074078D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Wagner, PR: AUTHOR

Abstract

Nematic liquid crystal materials tend to align to the nature of the surface on which they are in contact. For an untreated surface, alignment tends to be irregular and results in inhomogeneous optical characteristics in both the turbulent and nonturbulent conditions. Homogeneity may be achieved by rubbing the surface(*). However, rub marks may degrade viewing conditions, particularly in the reflectance mode of device operation.

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Substrate Treatment for Liquid Crystal Display

Nematic liquid crystal materials tend to align to the nature of the surface on which they are in contact. For an untreated surface, alignment tends to be irregular and results in inhomogeneous optical characteristics in both the turbulent and nonturbulent conditions. Homogeneity may be achieved by rubbing the surface(*). However, rub marks may degrade viewing conditions, particularly in the reflectance mode of device operation.

The application of a very thin (several molecular layers at most) layer of a long-chain organic material to the surface of the substrate causes homogeneous alignment of the liquid crystal optic axis relative to the surface and results in improved viewing conditions. The property of molecular alignment of this long- chain organic material relative to the substrate is important, since the liquid crystal alignment is determined by the alignment of the long-chain organic material.

Surfactants are typical of such long-chain organic materials and methods of application include aqueous dipping, exposure to vapor, and melting(**). An example of application by aqueous dipping is as follows: A substrate, such as conductive tin oxide coated glass or metallized glass, is cleaned in a conventional manner, e.g., ultrasonic agitation in aqueous detergent, rinsed in water, and immersed in a 10/-4/ molar solution of octadecylamine hydrochloride. The substrate is then slowly withdrawn from the solution and allo...