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:
Mar. 30, 1993
Filed:
Aug. 02, 1991
James C McDonald, Bellvue, CO (US);
Gregory V Hofer, Loveland, CO (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
An apparatus for attenuating optical crosstalk induced components of a focus error signal in an optical disk drive of the type having a grooved optical disk with servo tracks and tracking and focus servo systems controlled by a digital signal processor. A calibration operation is performed whenever a new disk is inserted into the track. During the calibration operation, the disk is scanned about a tracking axis at a track crossing frequency greater than the focus servo system bandwidth. The focus error signals produced when the disk is scanned are filtered about a pass band including the track crossing frequency. Crosstalk values equal to values of the filtered focus error signals are determined as a function of corresponding values of the tracking error signals, and are stored in memory. A correction operation is performed while reading and writing data on the disk. During the correction operation, the crosstalk values are read from memory as a function of corresponding values of the tracking error signals, and summed with the focus error signals.