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:
Aug. 10, 1976
Filed:
Nov. 07, 1975
David C Boyd, Corning, NY (US);
Corning Glass Works, Corning, NY (US);
Abstract
This invention relates to soft, low expansion, high durability, high refractive index glasses especially suitable for the production of segments or buttons for multifocal ophthalmic lenses and, in particular, photochromic ophthalmic lenses. The glasses demonstrate refractive indices between about 1.58-1.71, softening points between about 630.degree.-675.degree.C., strain points between about 450.degree.-500.degree.C., good chemical durability, and coefficients of thermal expansion (25.degree.-300.degree.C.) between about 45-60 .times. 10.sup.-.sup.7 /.degree.C. The glasses consist essentially, by weight on the oxide basis, of about 3-7% B.sub.2 O.sub.3, 3-11% Al.sub.2 O.sub.3, 30-60% PbO, and 27-55% SiO.sub.2.