The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 11, 2000
Filed:
Jun. 18, 1998
Paulus Pieter De Wit, Westervoort, NL;
Stephen James Picken, Velp, NL;
Andre Steenbergen, Arnhem, NL;
Martin Bosma, Arnhem, NL;
Akzo Nobel nv, Arnhem, NL;
Abstract
The invention is directed to a liquid crystalline display comprising a display cell containing liquid crystalline material and a retardation layer. The retardation layer comprises a, preferably slightly cross-linked, high-molecular weight material layer and a substrate, wherein the high-molecular weight material has a nematic phase above its Tg and a dynamic viscosity at the working temperature of at least 100 Pa.s. The difference of the Tc of the high-molecular weight material and the Tc of the low-molecular weight material of the display cell (TC.sub.cell) is in the range of -30.degree. C. to +30.degree. C., preferably in the range of -20.degree. C. to +20.degree. C., and more preferably in the range of -10.degree. C. to +10.degree. C.; and the Tg of the high-molecular weight liquid crystalline material is lower than 50.degree. C. It was found that if high-molecular weight material is used with a Tc comparable with that of the, preferably low-molecular weight, liquid crystalline material of the active cell, the temperature dependency of the retardation value of the retardation layer is comparable with that of the active cell. Thus, the retardation value of the retardation layer is comparable with that of the active cell within the temperature range in which displays are used. It was further found that by cross-linking of the high molecular weight liquid crystalline material, the retardation layers according to the invention become less susceptible to pinhole forming and unwanted variation of the twist, and have improved mechanical stability.