Patent ID: 6671385
Filing Date: 2003-12-30
Classification: H04R

Abstract:
A loudspeaker comprising:a frame; a magnetic circuit supported by said frame and comprising a first magnet, a second magnet disposed in opposing relation to said first magnet, said first magnet and said second magnet being magnetized to be magnetically repulsive to each other, a first plate disposed between said first and second magnets, a second plate disposed on a side of said first magnet opposite said first plate, and a yoke disposed in opposing relation to an outer circumferential surface of said first plate, such that a magnetic gap is defined between said yoke and said outer circumferential surface of said first plate; a voice coil bobbin having a coil kept in said magnetic gap; a diaphragm connected to said voice coil bobbin; and an edge part coupled with an outer circumferential edge of said diaphragm; wherein said magnetic circuit further comprises a third plate disposed on a side of said second magnet opposite said first plate, each of said second magnet and said third plate having a ring shape, said second magnet and said top plate having substantially equal inner diameters and substantially equal outer diameters, said outer diameters of said second magnet and said third plate being smaller than an outer diameter of said first plate; and wherein a protrusion projects from said first plate in a direction away from said first magnet for positioning of said second magnet.