Patent ID: 6829366
Filing Date: 2004-12-07
Classification: H04R

Abstract:
A magnetic circuit comprising:an annular magnet magnetized in the axial direction of the magnetic circuit; an annular stacked plate disposed on the magnet and including first and second annular plates; and a yoke facing the inner circumferential surface of the stacked plate across a cylindrical space, wherein upper and lower magnetic gaps are provided at two axially separated positions in the cylindrical space; the inner circumferential portions of the first and second annular plates are deformed downward and upward, respectively, in the axial direction such that the inner circumferential surface of the stacked plate faces the lower and upper magnetic gaps; and the remaining portions of the first and second annular plates, extending outward from the deformed inner circumferential portions in the radial direction of the magnetic circuit, are stacked on the magnet.