Speaker and magnetic loop used for the speaker

一种扬声器，具有：由中心板、配置在中心板的下面和上面并在互相磁性相斥的方向被磁化的第1磁铁和第2磁铁、配置在第1磁铁下面的底板、轭铁构成的磁回路；音圈；振动板；与振动板的外周部接合的边缘部；以及框架，在磁回路中，还具有配置在第2磁铁上面的顶板，第2磁铁和顶板是环状，第2磁铁和顶板的内径及外径大致相等，且第2磁铁和顶板的外径比中心板的外径较小，在中心板的上面具有对第2磁铁定位用的凸部。利用本发明的结构，能提供既小型、又有足够驱动力的扬声器。 A loudspeaker comprising a magnet circuit comprising a center plate, first and second magnets disposed respectively on a lower surface and an upper surface of the center plate and magnetized to be repulsive with each other, an under plate disposed to a lower surface of the first magnet, and a yoke. It further comprises a voice coil, a diaphragm, an edge coupled with the outer circumferential edge of the diaphragm, and a frame. The above-described magnet circuit further comprises a top plate disposed on an upper surface of the second magnet. Both of the second magnet and the top plate have a ring shape, the inner and the outer diameters of the two items being substantially the same. An outer diameter of the second magnet and the top plate is smaller than that of the center plate, and the center plate is provided on the upper surface with a protrusion for positioning of the second magnet. A compact loudspeaker having a sufficient driving force can be provided in accordance with the present invention.