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. 20, 2007
Filed:
Feb. 23, 2005
Tetsuo Ueda, Kanagawa, JP;
Kazuyuki Ishibashi, Kanagawa, JP;
Satoshi Ishii, Kanagawa, JP;
Masaaki Noguchi, Kanagawa, JP;
Tetsuo Ueda, Kanagawa, JP;
Kazuyuki Ishibashi, Kanagawa, JP;
Satoshi Ishii, Kanagawa, JP;
Masaaki Noguchi, Kanagawa, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
Embodiments of the invention are directed to detecting an abnormality in head flying height. In one embodiment, an AGC controller establishes the gain of the reproduced signal through gain adjustment using the servo AGC of the servo signal. A digital filter performs filtering processing by use of the obtained gain data g and the gain data of previous sectors. A comparative judgment section obtains filtered gain data G from the digital filter and compares the gain data G with a reference value CRITERIA to determine whether the flying height is normal or abnormal. If the gain G is larger than the reference value CRITERIA, then the data write operation is inhibited. The filter parameters of the digital filter are programmable parameters which can be set and changed.