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. 17, 1999
Filed:
Mar. 17, 1997
Applicant:
Inventors:
Assignee:
Hoya Corporation, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
428141 ; 428212 ; 4286 / ; 4286 / ; 4286 / ; 428900 ; 428 655 ; 360135 ;
Abstract
There is provided a magnetic recording medium comprising a nonmagnetic substrate (10, 20), at least one magnetic layer (30) having an upper surface (30a), and a protection layer (40) made of zirconia and having an upper surface (40a). The upper surface (30a) has a surface roughness of 3 nm or smaller defined by maximum height (R.sub.max) while the upper surface (40a) has a surface roughness ranging from 5 nm to 60 nm. When a distance Zi indicates a degree of irregularities of the upper surface (40a) of the protection layer (40), a standard deviation of the heights Zi is 5.7 nm or smaller.