| 摘要 |
PURPOSE:To make the constitution of servo systems of focus and tracking easy and noncontactually reproduce the signal faithfully by detecting the two directions perpendicular to modulated groove walls through focus detection in a stereo record of 45-45 system. CONSTITUTION:In an optical pickup part 24, the output light of a laser oscillator 5 is divided to beams 6 and 7 for left and right channels with a splitter 8. The respective beams are focused at the respective walls of the modulated grooves 4 of a stereo record by lenses 9, 10. Each of the reflected light is sent to signal detectors 17, 18 by splitters 15, 16, whereby the reproduction of the signals is accomplished. In this case, focus erros are detected by the detectors 13, 14 from part of the reflected light and the signals of the difference and sum are obtained in a matrix circuit 19. These are then passed through LPFs 20, 21 to obtain the driving signals for servo systems 22, 23 of tracking and focus, by which the position of the pickup part 24 is controlled. |
