Patent ID: 7317810

Claim:
A speaker, comprising: a magnetic circuit which includes at least three layered magnets, wherein a first magnet of a first layer and a third magnet of a third layer are arranged in the magnetic directions which repel each other; the direction of polarity of a second magnet of a second layer is arranged perpendicularly to the direction of polarity of said first magnet of the first layer and third magnet of the third layer; a voice coil is wound around a center of a bobbin which is arranged to oppose an inner diameter of said second magnet of the second layer formed in a shape of a ring or a polygonal frame; and approximately the same vibration systems composed of a diaphragm and an edge are connected to both the top and bottom ends of said bobbin so that said vibration system that is symmetrical with respect to a center axis perpendicular to the direction of a center axis of said voice coil is provided.