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. 01, 1979
Filed:
May. 26, 1978
James E Elliott, San Pedro, CA (US);
Lee Mickelson, Long Beach, CA (US);
MCA Discovision, Inc., Universal City, CA (US);
Abstract
An optical transducer having concentric radiant beam detectors for converting a radiant beam to electrical signals including a first axially placed detector with a second detector concentric therewith. In one embodiment, the detectors receive the radiant beam through an amplifying auxiliary lens. Changes in focus differentially affect the magnitude of the beam impinging on the individual detectors, resulting in corresponding changes in the individual detector outputs. A focusing system employing the transducer moves a focusing lens in response to the differential output of the individual detectors. The focusing system can be employed in a video disc reading system so that the video disc scanning beam is always focused precisely at the disc. An electrical difference circuit leading from the photo-detectors generates a driving signal to energize a lens-moving motor for shifting the focusing lens along the axis of the beam.