Electrooptical display element using a supertwist liquid crystal having specified elastic constants

US5188758A · kind A · utility

Assignee

• MERCK PATENT GESELLSCHAFT MIT BESHRANK TER HAFTUNG · DE

Inventors

• Gunter Baur · Glückstadt, DE
• Bernhard Scheuble · Alsbach, DE
• Waltraud Fehrenbach · Hersbruck, DE

Key dates

• Filing date: May 15, 1989
• Grant date: Feb 23, 1993
• Expiry date: May 15, 2009

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09K19/42
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to an electrooptical display element which can be multiplexed, has two support plates which, with an edging, form a cell containing a pneumatic liquid crystal material with positive dielectric anisotropy, and at least one chiral additive, and has a small surface tilt angle and a twist angle with a value between 150.degree. and 250.degree., wherein the ratio of the elastic constants for bending and twisting K.sub.3 /K.sub.2 of the liquid crystal material and the twist angle are such that when using liquid crystal material with the ratio of the elastic constants K.sub.3 /K.sub.1 for mending and spreading, which is in the order of the maximum possible, the steepness of the characteristic line is approved by the characteristic line is bi-stable or when using liquid crystal material with the ratio of the elastic constants K.sub.3 /K.sub.1 for bending and spreading either small enough or of the smallest order possible, the steepness of the characteristic line is improved but the characteristic line remains stable. The invention furthermore relates to a corresponding supertwist cell.