| 摘要 |
PURPOSE:To obtain a signal pickup device capable of performing stable control operation by detecting operations in the tracking direction and the time base correcting direction of a cantilever with a pair of coils and feeding back velocity components to a circuit for the tracking control operation and the time base correcting operation. CONSTITUTION:A permanent magnet 4 for the tracking control operation and the time base correcting operation is attached to the rear part of a cantilever 3. Detecting coils 11 and 12 which face the permanent magnet 4 with a gaps between them are arranged in front positions, which are tracking coils 6 and 7 with an elastic supporting body 5 between them, symmertrically with respect to the axial direction of the cantilever 3. Voltages having polarities opposite to each other are generated in detecting coils 11 and 12 if the cantilever 3 is displaced in the direction of an arrow BR, and they are fed back to a tracking-direction driving circuit throgh a differential amplifier 13. Voltages having the same polarity are generated in detecting coils 11 and 12 if the cantilever 3 is displaced in the direction of an arrow CF, they are added and are fed back to a time base correcting-direction driving circuit through an amplifier 14. |
