| 摘要 |
PROBLEM TO BE SOLVED: To make the center of gravity of a movable part coincide with the center of the actual driving force. SOLUTION: A focus coil 33f and tracking coils 33t are mounted on a coil base 31 with their center positions coincided with each other in the coil thickness direction; and, the focus coil 33f is arranged in the magnetic gap 5g of a magnetic circuit containing one magnet which is magnetized in two poles in the focus direction F.
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