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. 12, 1992
Filed:
Sep. 25, 1989
James C McDonald, Black Forest, CO (US);
Gregory V Hofer, Colorado Springs, CO (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A method for obtaining focus capture in an optical disk drive having a focus servo system with a servo loop and operable in open and closed loop modes, including: opening the servo loop and operating the servo system in the open-loop mode; scanning an objective lens about a focus axis with respect to an optical disk at a calibration velocity; peak detecting focus error signals produced while the lens is scanned at the calibration velocity to determine a peak focus error signal value; storing a calibration threshold value as a function of the peak focus error signal value; scanning the objective lens about the focus axis at a focus capture velocity; comparing the focus error signal values produced while the lens is scanned at the focus capture velocity to the calibration threshold value; and closing the servo loop and operating the focus servo system in the closed-loop mode when the focus error signal values reach the calibration threshold value.