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:
Apr. 29, 2008
Filed:
Jan. 12, 2006
Takehiko Hamaguchi, Kanagawa, JP;
Hideaki Maeda, Kanagawa, JP;
Kazuaki Usui, Kanagawa-ken, JP;
Kazuhisa Shishida, Kanagawa, JP;
Takashi Konishi, Kanagawa, JP;
Takehiko Hamaguchi, Kanagawa, JP;
Hideaki Maeda, Kanagawa, JP;
Kazuaki Usui, Kanagawa-ken, JP;
Kazuhisa Shishida, Kanagawa, JP;
Takashi Konishi, Kanagawa, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
Embodiments of the invention provide optimum servo patterns for perpendicular magnetic recording method. In one embodiment, a burst field of servo patterns is composed of burst-signal parts in each of which a constant frequency occurs successively and zero-signal parts each of which has been demagnetized to a state of zero-magnetization, and the total magnetization of the burst field is made approximately 0. The zero signal portions are formed by shutting off a write current at a time during an operation to record servo patterns on a disk initialized to a state of zero-magnetization. The total magnetization of all servo patterns is made approximately 0 by encoding an address mark field and a track code field of servo patterns by a phase shift method.