Ferroelectric liquid crystal with positive dielectric anisotropy, chevron structure and grey scale

US5353136A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Claus Escher · Mühltal, DE
• Hans-Rolf Dubal · Königstein, DE
• Takamasa Harada · Oberursel, DE
• Gerhard Illian · Frankfurt am Main, DE
• Mikio Murakami · Kakegawa, JP
• Dieter Ohlendorf · Liederbach, DE

Key dates

• Filing date: Dec 13, 1991
• Grant date: Oct 4, 1994
• Expiry date: Dec 13, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/1416
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A method of driving a ferroelectric liquid crystal element which enlarges the effective cone angle. A ferroelectric liquid crystal is held between two substrates such that the helix is suppressed and a chevron layer structure is present. The ferroelectric material has a positive dielectric anisotropy. A first pulse is applied which causes switching from one state to the other, and a subsequent smaller AC pulse is applied which does not cause switching. The second pulse voltage control the effective cone angle, enabling grey scale.