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. 29, 1996
Filed:
Jul. 07, 1994
Applicant:
Inventor:
Ichiro Hayashi, Yokohama, JP;
Assignee:
AG Technology Co., Ltd., Yokohama, JP;
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
428141 ; 428410 ; 428338 ; 428220 ; 428 641 ; 428 642 ; 428 643 ; 428 644 ; 428 653 ; 4286 / ; 4286 / ; 369280 ; 360135 ; 346137 ;
Abstract
A glass substrate for a magnetic disk having an inner peripheral edge and an outer peripheral edge, wherein the surface of at least the inner peripheral edge is treated by etching to have a surface roughness such that, as measured by a three dimensional scanning electron microscope at randomly selected at least four places with a reference length of 240 .mu.m and a cut-off wavelength of arithmetic mean roughness (Ra) of 80 .mu.m, the mean value of arithmetic mean roughness (Ra) is from 1.0 to 6.0 .mu.m, and the mean value of the number of peaks is within a range of from 8 to 30.