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:
Jan. 08, 1980
Filed:
Sep. 14, 1978
Applicant:
Inventors:
William E Barnette, Levittown, PA (US);
Fred W Spong, Lawrenceville, NJ (US);
Assignee:
RCA Corporation, New York, NY (US);
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04N / ; G11B / ; G11B / ;
U.S. Cl.
CPC ...
358128 ; 1791 / ; 318662 ; 361280 ; 324 / ;
Abstract
A non-contact type, capacitance distance sensing probe having one or two electrodes disposed about one end of an objective lens system in an optical video disc system is used with a focus control servo loop to maintain focus of a light beam on the surface of a reflective disc record despite undesirable axial displacements of the surface when the record is rotated. The two electrode probe is balanced to provide immunity to variations in the impedance of the external circuit which grounds the disc.