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:
Sep. 29, 1998
Filed:
Oct. 27, 1997
Akira Ishikawa, Kodaira, JP;
Yoshihiro Shiroishi, Hachioji, JP;
Yuzuru Hosoe, Hino, JP;
Yotsuo Yahisa, Odawara, JP;
Tomoo Yamamoto, Hachioji, JP;
Masukazu Igarashi, Kawagoe, JP;
Akira Osaki, Odawara, JP;
Yoshiki Kato, Tokyo, JP;
Jun Fumioka, Hadano, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A magnetic recording medium includes a non-magnetic substrate, and a magnetic layer provided on the non-magnetic substrate. The value of the product Br.sub.1 .delta. of the residual flux density Br.sub.1 of the magnetic layer determined in a recording direction and the thickness .delta. of the magnetic layer is not less than 5 G.mu.m and not more than 180 G.mu.m; the value of the ratio of Br.sub.1 to the residual flux density Br.sub.2 determined in a direction parallel to the substrate plane and perpendicular to the recording direction, Br.sub.1 /Br.sub.2, is not less than 1.3 and not more than 3; the surface of the non-magnetic substrate has texture grooves therein extending predominantly in the recording direction; and the average roughness factor Ra of the surface of the magnetic layer determined in a direction perpendicular to the substrate plane and perpendicular to the recording direction is not less than 0.3 nm and not more than 1.9 nm. Alternatively, the value of the product Br.delta. of the residual flux density Br of the magnetic layer determined in the recording direction and the thickness .delta. of the magnetic layer is not less than 5 G.mu.m and not more than 80 G.mu.m; and the value of the anisotropic magnetic field H.sub.k of the magnetic recording medium is not less than 7 kOe and not more than 20 kOe.