| 摘要 |
PURPOSE:To turn a pickup arm while keeping the horizontal balance of the arm in excellent way, by arranging a pair of more driving coils, at the position in the relation of 180 deg. around the rotating center of the pickup arm, and cooperating with a magnet. CONSTITUTION:The arm is mechanically driven from a rest position of the arm 5 to almost center of a disc, and then led-in by an electromagnetic system. The electromagnetic driving system consists of a moving magnet fitted to a rotary shaft S, a yoke 23, and a base plate fitted to an arm stand (not shown) between the magnet 20 and the yoke 23. The base plate is provided with moving coils 15a, 25b part by 180 deg. and a speed detection coil 26 at the position of 90 deg.. The magnet 20 is magnetized toward the thickwise direction to be arranged with alternate magnetic poles circumferentially. Thus, the attracting force between the coils 25a, 25b and the magnet 20 is cancelled and a disc is turned while keeping the horizontal balance in good condition. |
