Patent ID: 6735322
Filing Date: 2004-05-11
Classification: H04R

Abstract:
A speaker comprising:a first magnet disposed at a mid position of a voice coil bobbin while surrounding the circumferential outer surface of said voice coil bobbin mounted on a vibrating plate; a first voice coil wound on the circumferential outer surface of said voice coil bobbin at a position where said voice coil bobbin faces one end of said first magnet with a predetermined gap being interposed therebetween; a second voice coil wound on the circumferential outer surface of said voice coil bobbin at a position where said voice coil bobbin faces the other end of said first magnet with a predetermined gap being interposed therebetween; a center pole, disposed within said voice coil bobbin, for developing two magnetic fields in a state that said first and second voice coils are located between said one and other ends of said first magnet; and at least one couple of dampers for supporting said voice coil bobbin at positions such that said voice coil bobbin is axially vibratory, said positions being located on both sides of and symmetrical with respect to those portions of said voice coil bobbin which are respectively wound with said first and second voice coils, wherein a magnetic circuit is disposed completely inside a casing;further comprising: at least one third magnet disposed on the front or rear side of said first magnet; and at least one third voice coil wound on the circumferential outer surface of said voice coil bobbin at a location thereof facing the end of said third magnet which is opposite to the end thereof closer to said first magnet, said third voice coil facing the end of said third magnet which is opposite to the end thereof closer to said first magnet in a state that a predetermined gap is present therebetween.