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:
Aug. 26, 1980
Filed:
Oct. 31, 1977
Fred W Spong, Lawrenceville, NJ (US);
RCA Corporation, New York, NY (US);
Abstract
For playback of a disc record information track, in which regions of a light reflective surface overlaid with a layer of light absorptive material alternate with regions of said light reflective surface free of said overlying absorptive material, light of a constant intensity is focused on the information track as the disc is rotated. The focused light is of insufficient intensity to effect ablation of the remaining absorptive material, but is of a frequency at which the overlaid regions of the coated disc exhibit an anti-reflection condition. A photodetector, positioned to receive light reflected from the information track as the pits pass through the path of the focused light, develops a signal representative of the recorded information.