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:
Mar. 12, 1985
Filed:
Sep. 24, 1981
Shinichi Tanaka, Kyoto, JP;
Ikuo Matsuda, Hirakata, JP;
Namio Hirose, Hirakata, JP;
Kazutsugu Kobayashi, Takatsuki, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
In an optical signal reproducing apparatus for a conventional disc phonograph record, the groove of said record is irradiated with the light beam from a direction that varies cyclically at a constant frequency in a plane. Said plane includes both the tangential velocity vector of the groove and a normal line to the surface of the groove. At the moment that the light beam irradiates the surface of the groove from a perpendicular direction, the reflected light beam traces back the same path as that of the irradiating light beam. When a photo-detector is limited by a slit to detect only the reflected light beam tracing back the same path as the irradiating light beam, the photo-detector detects light pulses which are pulse-phase-modulated by the slope angle of the surface of the groove. The recorded signal can be reproduced by demodulating said pulse-phase-modulated pulses.