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. 02, 2000
Filed:
Jun. 23, 1998
Izuo Horai, Odawara, JP;
Hitachi Electronics Engineering Co., Ltd., Tokyo, JP;
Abstract
A magnetic disk testing method is provided, which comprises a surface defect test step of detecting, as defect data, the size of surface defect of a magnetic disk, the continuity thereof, the number thereof and the position thereof by testing magnetic disks optically and a classification step of classifying the magnetic disks to first magnetic disks, second magnetic disk and third magnetic disks on the basis of the defect data obtained in the surface defect test step. The first magnetic disks have surface defects which do not provide any problem on electric characteristics and are to be qualified through a subsequent certification test, the second magnetic disks require a further certification test for determining whether or not the surface defects thereof provide a problem on electric characteristics and the third magnetic disks have electric characteristics which are to be clearly disqualified without necessity of a further certification test, wherein the first magnetic disks are decided as qualified and the second magnetic disks are objects for the certifying test.