Matsushita Electric Industrial Co., Ltd.

Ikuo Matsuda

Shinichi Tanaka

Kazutsugu Kobayashi

Namio Hirose

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.

Growing community of inventors

Hirakata, Japan

Ikuo Matsuda