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:
May. 31, 2005
Filed:
Mar. 31, 2003
Applicants:
Norman D. Gardner, Aliso Viejo, CA (US);
Robert P. Ryan, Mission Viejo, CA (US);
Inventors:
Norman D. Gardner, Aliso Viejo, CA (US);
Robert P. Ryan, Mission Viejo, CA (US);
Assignee:
Western Digital Technologies, Inc., Lake Forest, CA (US);
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B005/596 ;
U.S. Cl.
CPC ...
Abstract
A disk drive is disclosed employing an offset-nulling amplifier for detecting a back EMF voltage of a voice coil motor (VCM) in a velocity mode servo control system. The offset-nulling amplifier comprises a differential amplifier, an input stage for swapping the polarity of the input voltage at a periodic interval, and an output stage comprising a single-ended amplifier having an input switched at the periodic interval between the positive and negative outputs of the differential amplifier.