| 摘要 |
PURPOSE:To obtain stable restoring force with less secular change by arranging two permanent magnets while the poles having same polarity are opposed, fitting one permanent magnet to the 2nd movable part and fixing the other permanent magnet to a base via a yoke and arranging a tracking drive coil around the yoke. CONSTITUTION:The permanent magnet 9 is fixed to the 2nd movable part 3 so that the magnetizing direction is in the tracking direction, the other permanent magnet 10 is fixed to the base 12 via the yoke 11 and the drive coil is arranged around the yoke 11. The magnetizing directions of the two permanent magnets 9, 10 are matched in a direction in parallel with the tracking direction and the same poles are opposed, then a repulsive force is generated, but the 2nd movable part is turned only around the shaft and not parted. When the movable part is turned around the shaft 4 and is about to be parted from one pole, then the distance between the other poles is shortened, the repulsive force is increased to inhibit the approaching. Thus, a restoring force going to be a balanced prescribed position is exerted to the two permanent magnets 9, 10. |
