| 摘要 |
PROBLEM TO BE SOLVED: To apply large magnetic force to a gap by improving the utilization efficiency of a magnet. SOLUTION: In a flange part 116B on the rear end side of a frame 116, a first plate 210 is arranged on the back side and continuously, a first magnet 220 magnetized in the axial direction of a center pole part 122C, a second plate 230, a second magnet 240 oppositely magnetized to the first magnet 220 and a base flange part 122A of a yoke 122 are successively arranged in the axial direction of the center pole part 122C. Besides, this magnetic circuit is surrounded with a magnetic shield cover 250. On the other hand, a third magnet 260 and a third plate 270 oppositely magnetized to the first magnet 220 are provided on the front side of the flange part 116B of the frame 116. Then, a voice coil 118 is arranged in a gap part 130A corresponding to the second plate 230.
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