Ferroelectric liquid-crystal systems having three or more chiral additives with different signs of the helical twist in the cholesteric phase

US5594575A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Claus Escher · Mühltal, DE
• Hans-Rolf Dubal · Königstein, DE
• Takamasa Harada · Oberursel, DE
• Wolfgang Hemmerling · Pocking, DE
• Gerhard Illian · Frankfurt am Main, DE
• Ingrid Muller · Niedernhausen, DE
• Mikio Murakami · Kakegawa, JP
• Dieter Ohlendorf · Liederbach, DE
• Rainer Wingen · Hattersheim, DE

Key dates

• Filing date: May 2, 1995
• Grant date: Jan 14, 1997
• Expiry date: May 2, 2015

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/141
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Ferroelectric liquid-crystal systems having high spontaneous polarization, in particular >35 nC cm.sup.-2, and good orientation properties in the ferroelectric phase, in particular the S.sub.C * phase, contain at least three different optically active compounds, preferably as dopes in a base mixture which is not itself optically active and has a nematic phase above the smectic phase. The optically active compounds are selected so that they do not all induce a helix of the same rotation sense in the nematic phase. Their relative concentrations are selected so that the total resultant pitch of the helix throughout the cholesteric phase is not less than 10 .mu.m.