Active matrix displays having high contrast values

US6482479B1 · kind B1 · utility

Assignee

• CLARIANT INTERNATIONAL LTD · CH

Inventors

• Hans-Rolf Dubal · Königstein, DE
• Toshiaki Nonaka · Kakegawa, JP
• Rainer Wingen · Hattersheim, DE

Key dates

• Filing date: Jul 26, 2000
• Grant date: Nov 19, 2002
• Expiry date: Dec 18, 2020

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09K2323/00
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

An active matrix display comprises a chiral smectic liquid crystal mixture which has the phase sequence I&#8212;N*&#8212;SmC*, a spontaneous polarization in the operating temperature range of <40 nC/cm2 and a pitch of >10 &mgr;m at at least one temperature in the nematic or cholesteric phase and comprises at least one compound each from at least two of the substance classes (A), (B) and (C) and one or more compounds from substance class (D):(A): compounds comprising two rings which are directly linked to one another and are selected from phenylene-1,4-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl and pyridazine-2,5-diyl with the proviso that at least one of these rings is a nitrogen heterocycle;(B): compounds comprising three rings selected from phenylene-1,4-diyl, two of the rings being directly linked to one another and the third ring being linked to one of the other two rings via an &#8212;OC(&boxH;O)&#8212; or &#8212;C(&boxH;O)&#8212;group, with the proviso that at least one of the three rings is fluorophenylene-1,4-diyl or ortho-difluorophenylene-1,4-diyl;(C): compounds comprising three rings which are directly linked to one another and are selected from phenylene-1,4-diyl, pyr…