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. 16, 1977
Filed:
Mar. 18, 1976
David A Krohn, Southbridge, MA (US);
Robert E Graf, Southbridge, MA (US);
Emil W Deeg, Woodstock, CT (US);
American Optical Corporation, Southbridge, MA (US);
Abstract
An ophthalmic glass lens having a compressively-stressed surface zone after ion exchanging which is at least 120 microns in depth, formed from an alkali metal oxide silicate glass comprising by weight about 4 to about 15 percent sodium oxide and about 3 to about 15 percent potassium oxide. There is a compressively-stressed surface layer having a strength of at least 25,000 psi. The total amount of sodium, potassium and other alkali metal oxides is up to about 20 percent. The total amount of zinc oxide, lanthanum oxide, magnesium oxide, and calcium oxide is about 8 to 15 percent, and there is about 3 to about 15 percent phosphorus pentoxide. An ion exchange process takes place at a temperature either above or below the strain point of conventional ophthalmic crown glass to produce satisfactory physical properties in the ophthalmic glass lens.