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. 27, 2012
Filed:
Jul. 13, 2008
Applicants:
Matthew J. Janssen, Corvallis, OR (US);
Timothy Wagner, Corvallis, OR (US);
Inventors:
Matthew J. Janssen, Corvallis, OR (US);
Timothy Wagner, Corvallis, OR (US);
Assignee:
Hewlett-Packard Development Company, L.P., Houston, TX (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B 7/00 (2006.01);
U.S. Cl.
CPC ...
Abstract
An optical disc is rotated using a spindle motor of an optical disc device, at no more than 600 revolutions per minute (RPM). The spindle motor has at least three coil groups, where each coil group has one or more coils. While the optical disc is rotating, at least one of the coil groups generates a back electromagnetic force (EMF) signal. The back EMF signal is used to determine marking positions on the optical disc. An optical beam is used to mark the optical disc at the determined marking positions.