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. 23, 1999
Filed:
Mar. 24, 1997
Hideki Ohmori, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An AGC circuit is used for read channels of a disk storage apparatus, by controlling a level of a reading output of a head to be kept constant. This AGC circuit has a gain control amplifier and a feedback circuit for digitally feeding back an output thereof. A maximum current value of a current type D/A converter is varied for every zone in zone bit recording. A gain adjusting time of the AGC circuit can be therefore minimized in each zone. A GAP length in the respective zones can be thereby reduced, and a storage capacity is increased. A maximum current value of the current type D/A converter is varied in a read/write area and a data surface servo area on a disk storage medium. It is therefore feasible to minimize the gain adjusting time of the AGC circuit in each of the servo area and the read/write area. The current type D/A converter is set so that a plus-side maximum current value is different from a minus-side maximum current value. The operation is therefore speeded up when increasing a gain, and the gain adjusting time of the AGC circuit can be minimized.