| 摘要 |
PURPOSE:To keep a magnetic circuit gap uniform at an assembling time and improve the set position precision of a voice coil or the like by forming a recessed part in a pole part of a yoke and using its side wall face as the positioning guide for the outside peripheral end of an edge. CONSTITUTION:A recessed part 13 where the edge is clipped is formed in a pole part 12 of a yoke 11, and a side wall face 13a of the recessed part 13 is constituted to become the positioning guide for the outside peripheral end of the edge. When a packing 22 is set to the recessed part 13 and the edge 14 is placed on it, the outside peripheral end of the edge 14 is guided and positioned by the side wall face 13a and is set in a correct position. Next, a packing 21 is placed, and a projecting part 20 of a top plate 18 is fitted strongly to the side wall face 13a, and the projecting part 20 presses and clips the edge 14 set through packings 21 and 22. Since the side wall face 13a is used as a reference face for attaching work when the projecting part 20 of the top plate 18 is fitted strongly to the side wall face 13a, a magnetic circuit gap 19 is kept uniform.
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