Patent ID: 7873179

Claim:
A speaker, comprising: a magnetic circuit; a diaphragm, a part of which is located in a magnetic gap formed in the magnetic circuit; a ring-shaped first voice coil formed on a first vibrating surface of the diaphragm; a ring-shaped second voice coil which is formed on a second vibrating surface of the diaphragm, the second vibrating surface being an opposite surface to the first vibrating surface, and which is electrically conducted with the first voice coil; and an edge firmly fixed on an outer margin of the first vibrating surface and operable to support the diaphragm in such a manner that enables vibration, wherein the first voice coil is formed so as to be located inside of an inner circumference of the edge and also within the magnetic gap, and the second voice coil is formed so as to have at least a part of an outermost circumference thereof located outside of the inner circumference of the edge and also within the magnetic gap.