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:
Oct. 13, 1987
Filed:
Nov. 13, 1985
Dorrel R Silvy, Elbert, CO (US);
Todd D Baumann, Berthoud, CO (US);
Roger R Bracht, Colorado Springs, CO (US);
Optotech, Inc., Colorado Springs, CO (US);
Abstract
A focus initialization system adapted for use with an optical data recording system. Focus initialization is performed while a tracking servo loop is in an open loop mode, and an objective lens is fixedly positioned along a tracking axis. With a focus servo system in an open loop mode, the objective lens is cyclically driven along a focus axis about a neutral position and between offset positions. Displacement of the offset positions from the neutral position is increased with each successive cycle. After the objective lens has been positioned at each peak offset position, the focus servo loop is closed and track crossings resultant from eccentricity of the servo tracks on the record carrier are counted. Focus capture is recognized when at least a predetermined number of track crossings are counted during a predetermined time period. If less than the predetermined number of track crossings are counted during the predetermined time period, the focus servo loop is opened and the objective lens is driven to a successive offset position.