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:
Feb. 06, 1990
Filed:
May. 04, 1987
Keith A Bates, Lafayette, CO (US);
Russell A Budd, Longmont, CO (US);
Millard A Habegger, Boulder, CO (US);
Mark L Rhoades, Longmont, CO (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Error correction in a feedback servo system. The feedback servo loop in, for example, a head positioning circuit in an optical disk data recording and retrieval system is provided with means for forcing the feedback signal to zero when the head is positioned at best focus as determined by a peak in the laser monitoring diode. The head in such a system must be dynamically maintained at a best focus position but, through use and transporting, the alignment of the head position error detecting system can be disturbed. In some cases, the loop circuit parameters may drift from their original values. To correct for errors introduced from such causes, the head is positioned at best focus and the focus error (head position error) signal is sensed. A correction system forces the sensed value to zero, e.g, by adjusting the gain of amplifiers used in the feedback loop.