| 摘要 |
PURPOSE:To raise the utilization efficiency of a magnetic flux in a magnetic gap, and to obtain a high driving sensitivity as an actuator, by attaching a magnetic material to a part which exists in the magnetic gap of a movable part of the actuator, and utilizing the quality by which the magnetic material concentrates the magnetic flux. CONSTITUTION:By attaching a magnetic material piece 8, a magnetic flux in a magnetic gap 7-a is attracted to the magnetic material piece 8 by the quality for concentrating the magnetic flux of the magnetic material piece 8 has, a high magnetic flux density is generated in the vicinity of the magnetic material piece 8 and the high magnetic flux density is supplied to a part which is used for tracking driving of a tracking coil 4, and the utilization efficiency of the magnetic flux for the tracking driving can be raised. Also, by placing the magnetic material piece 8 in the magnetic gas 7-a, the effect for narrowing the magnetic gap 7-a is given artificially, and the total quantity of the magnetic flux in the magnetic gap 7-a can be increased, and the driving sensitivity of an actuator can be improved.
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