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:
May. 04, 1999
Filed:
Apr. 18, 1996
Applicant:
Inventors:
Assignee:
AG Technology Co., Ltd., Yokohama, JP;
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
428 641 ; 428 642 ; 428 643 ; 428 644 ; 428 653 ; 4286 / ; 428410 ; 428426 ; 501 55 ; 501 68 ; 501 69 ; 501 70 ; 501 72 ;
Abstract
A glass substrate for magnetic disks, obtained by chemical strengthening treatment of a glass consisting essentially of from 50 to 65 wt % of SiO.sub.2, from 5 to 15 wt % of Al.sub.2 O.sub.3, from 2 to 7 wt % of Na.sub.2 O, from 4 to 9 wt % of K.sub.2 O, from 7 to 14 wt % of Na.sub.2 O+K.sub.2 O, from 12 to 25 wt % of MgO+CaO+SrO+BaO, and from 1 to 6 wt % of ZrO.sub.2.