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:
Jul. 27, 1999
Filed:
Sep. 30, 1996
Jason D Gregg, Edmond, OK (US);
Timothy T Walker, Edmond, OK (US);
Seagate Technology, Inc., Scotts Valley, CA (US);
Abstract
Apparatus and method for detecting servo defects in a disc drive, the servo defects providing false indications of the position of a disc drive head with respect to a selected track. During use of a position error signal (PES) to position the head with respect to the selected track, the PES comprising a sequence of PES samples, the disc drive determines a first difference term as a selected combination of a first set of PES samples. A second, subsequent difference term is also generated as a selected combination of a second set of PES samples, the second set of PES samples including at least one PES sample which does not appear in the first set of PES samples. The magnitudes of the first and second difference terms are compared to a predetermined threshold, and a servo defect is detected at such time that both the first and second difference terms exceed the predetermined threshold and the first difference term exceeds the second difference term. Additionally, at such time that the first difference term exceeds the predetermined threshold and the second, subsequent difference term does not, the disc drive determines whether a servo defect flag has previously been set indicative of the presence of a servo defect, and if the servo defect flag has not been previously set, the drive identifies the presence of a servo defect and sets the servo defect flag.