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:
Oct. 15, 1996
Filed:
Aug. 31, 1995
Reinhard Kassner, Alfeld, DE;
Deutsche Spezialglas A.G., Grunenplan, DE;
Abstract
The invention relates to a glass of high refractive index suitable for the close-vision part of multifocal, in particular phototropic multifocal, spectacle lenses. The glass has a composition (in % by weight, based on oxide) of: SiO.sub.2 28-40; B.sub.2 O.sub.3 0-8.5; Li.sub.2 O 0-1; Na.sub.2 O 0-2.5; K.sub.2 O 0-5; CaO 0-6; SrO 0-6; BaO 6-12; ZnO 9-16; PbO 32-40; TiO.sub.2 0.3-7; ZrO.sub.2 0.4-5; .SIGMA. Li.sub.2 O+Na.sub.2 O+K.sub.2 O 0-5, and a refractive index n.sub.e of 1.66-1.81, an expansion coefficient .alpha..sub.20-300 of 5.7-6.8.times.10.sup.-6 K.sup.-1, a softening point of 650.degree.-700.degree. C. and a glass transition temperature Tg of 520.degree.-560.degree. C.