| 摘要 |
PURPOSE:To prevent a tracking error securely through simple constitution by varying the distance between the horizontal shaft of a pickup arm and a cartridge through a varying means which varies the distance between the horizontal turning shaft of the pickup arm and the cartridge. CONSTITUTION:As the pickup arm turns, a turning disk 17 turns and when a slit 18 faces a photocoupler 19, a photodetecting element (CdS) 21 is irradiated with light from a light emitting element (LED) 20. Once the CdS21 detects the light, the base potential of a transistor (TR) rises and the TR turns on. As a result of the conduction of the TR, a current flows through winding 13 on the collector side of the TR and the movable part 4 of the arm moves toward the cartridge side until it balances with the force of a spring 15 between the movable part 4 and a fixed part 5. As the turning disk 17 further turns, the slit 18 varies in area gradually in its turing direction, the base potential of the TR further rises, and a more current flows through the winding 13 to move the movable part 4 toward the cartridge side, so that the movable part stops where it balances with the force of the spring 15. |
