Optical disc playback system - has screening plate with needle aperture to control input to detector element

摘要

An optical player for use with either video discs or digital audio discs has a light sourcea (1), beam splitter (2), disc (4), photo detector (5) and lens mounted in an actuator (6). Located between the splitter and the detector is a screening plate (9) with a small aperture (8). The system of the tight source splitter and lens provides the functional equivalent of a pair of lenses providing point source focussing. The screening plate (9) with the small aperture provides blocking of components of the reflected tight general from the surface of the disc. This prevents any cross talk between adjacent tracks on the disc. A further version has a selection circuit coupled to the detector stage. ADVANTAGE - Eliminates drop in signal level from disc.