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. 29, 1989
Filed:
Nov. 20, 1987
Hirotsugu Fukuoka, Hitachi, JP;
Kanji Kawakami, Mito, JP;
Makoto Aihara, Hitachi, JP;
Mitsuo Suda, Hitachi, JP;
Kouji Takeshita, Odawara, JP;
Yukihiro Isono, Odawara, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
DC bias currents are applied to a conducting wire of a thin film magnetic head to be inspected. When the DC bias currents (I.sub.0, I.sub.1, I.sub.2) are supplied to the conducting wire, the impedances (Z.sub.0, Z.sub.1, Z.sub.2) corresponding to the DC bias currents are measured. When a ratio (.vertline.Z.sub.1 -Z.sub.0 .vertline./.vertline.Z.sub.2 -Z.sub.0 .vertline.) corresponding to an overwrite characteristic (OW) reaches to a predetermined value by lapping tip portions of an upper magnetic layer and a lower magnetic layer of the magnetic head, the lapping process of the magnetic head is finished.