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:
Nov. 30, 1999
Filed:
Mar. 18, 1997
Hidekazu Honda, Odawara, JP;
Koichi Ono, Hiratsuka, JP;
Haruhiko Hosokawa, Kanagawa-ken, JP;
Katsuhiro Tsuneta, Odawara, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A magnetic disk device of embedded-servo type is capable of performing dummy operation for suppressing waveform degradation of signal reproduced by magnetic heads at a high speed with high reliability. When a waveform deformation occurs in a No.0 head, a controller changes over the No.0 head to a No.1 head operating normally, whereupon a cylinder portion for which dummy operation is to be performed is sought on the basis of the servo information supplied from the No.1 head. The cylinder portion destined for the dummy write operation contains servo information at timing positions that are the same for the individual magnetic heads. When passing of the No.1 head over the cylinder portion is confirmed, the No.1 head is changed over to the No.0 head for performing dummy write operation for suppressing the waveform deformation of the reproduce signal outputted from the No.0 head. Before the timing for succeeding information, the No.1 head is restored-by issuing a head change command signal. Because the seek operation is realized exclusively by the magnetic head suffering no abnormality, the dummy write operation for preventing waveform deformation of the reproduced signal outputted from the No.0 head can be realized without fail.