| 摘要 |
PURPOSE:To reduce the resonance due to the deviation between the exerting point of a driving force and the gravity center of the moving part by cancelling the moment at the gap inner side around the gravity center by the moment at the gap outside around the gravity center in the operating part of a tracking coil. CONSTITUTION:Tracking coils 73, 74 of the same shape are arranged side by side along the winding direction of the focusing coil 72 and have two each of operating parts whose winding direction is perpendicular to the winding direction of the focusing coil 72. Moreover, the moment of the driving force by the exerting parts 73a, 74a at the inside placed in the gap around the gravity center G is cancelled by the moment by the driving force of the exerting parts 73b, 74b at the outside placed at the outside of the gap around the gravity center G. Thus, the moment around the gravity center G is eliminated at the drive in the tracking direction (t) and the production of high-order resonance due to it is prevented.
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