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. 20, 1987
Filed:
Oct. 17, 1985
W Ray Dakin, Huntington Beach, CA (US);
John F Browne, Laguna Niguel, CA (US);
Optical Disc Corporation, Cerritos, CA (US);
Abstract
A focus control system with a novel gain control circuit for continually varying the gain of the focus error signal based on the optical characteristics of the medium. As those optical characteristics change to decrease the amount of light available to the focus error detector, the gain of the focus error signal is increased so that the overall gain of the servo loop and the overall response of the servo to a focus error remains constant. This is accomplished by monitoring the optical characteristics of the medium which affect the focus error detector. In a multiple detector system, the outputs of all of the detectors are summed together. The resultant signal is a reflectivity or a transparency signal and is used in a novel circuit for controlling the servo gain.