Patent ID: 7684586

Claim:
A speaker comprising: a diaphragm including an annular principal vibration part, an annular internal support for supporting the internal side of the principal vibration part, and an annular external support for supporting the external side of the principal vibration part; a large-diameter voice coil unit mounted at the outer edge of the principal vibration part of the diaphragm; a small-diameter voice coil unit mounted at the inner edge of the principal vibration part of the diaphragm; a magnetic circuit including a yoke having a magnet fixed thereto and forming a first magnetic gap, where the large-diameter voice coil unit is arranged, and a second magnetic gap, where the small-diameter voice coil unit is arranged; wherein the speaker includes a positioning member fixed to a central area and a peripheral area of the diaphragm and secured to a predetermined site of the magnetic circuit for restricting the positions of the diaphragm relative to the magnetic circuit in a radial direction and an axial direction perpendicular to the radial direction so that the large-diameter voice coil unit and the small-diameter voice coil unit are arranged within the first and second magnetic gaps, respectively; and wherein in the diaphragm, the stiffness of the principal vibration part is less than the stiffness of the internal support and the external support.