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:
Jan. 25, 2005
Filed:
Mar. 09, 2001
Yoshiaki Ikai, Kawasaki, JP;
Yoshiaki Ikai, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
The present invention implements a servo system which can support changes of the higher resonance frequencies of the actuator with a simple configuration at low cost. The servo system comprises a headwhich at least reads a diska carriagewhich drives the headto the track position of the diska detection circuitwhich detects a positional error with respect to the track from the read output of the head, and the servo control unitwhich controls the carriage such that the head follows up the track according to the positional error, wherein the servo control unitfurther comprises a digital filter for increasing gain so that the open loop characteristic of the tracking servo system by the servo control unit has a gain higher than the open loop gain of the phase cross-over frequency fin a frequency area which is higher than the phase cross-over frequency fbut lower than the higher resonance frequency fof the carriage and where the gain does not becomes OdB or more at a frequency where phase is (−180+360×N)°. Since gain is increased, phase margin is increased.