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. 13, 2009
Filed:
Apr. 20, 2007
Steven Nemshick, Santa Ana, CA (US);
Craig R. Huddleston, Newport Beach, CA (US);
Steven Nemshick, Santa Ana, CA (US);
Craig R. Huddleston, Newport Beach, CA (US);
Western Digital Technologies, Inc., Lake Forest, CA (US);
Abstract
A disk drive is disclosed employing a VCM control loop comprising a voltage detector operable to detect a back EMF voltage across a voice coil of a voice coil motor, a current detector operable to detect a current flowing through the voice coil, and a control voltage generator, responsive to a command input and the detected back EMF voltage, operable to generate a control voltage applied to the voice coil. Control circuitry within the disk drive (a) initializes the control voltage; (b) injects a transient into the VCM control loop and detects a corresponding current flowing through the voice coil; (c) adjusts the control voltage in response to a polarity of the detected current; (d) repeats elements (b) and (c) at least once; and (e) stores an offset value in response to the adjusted control voltage.