Patent ID: 6359997
Filing Date: 2002-03-19
Classification: H04R

Abstract:
A loudspeaker comprising:a receiving part (11) having a mandrel (11b) and a basket (11a) a voice coil (16) having an inner periphery and an outer periphery; a diaphragm (13) attached to the basket (11a) and the voice coil (16); and at least one permanent magnet ring (12) made of a magnetic ring material and disposed inside the inner periphery of the voice coil for driving the voice coil, wherein the permanent magnetic ring is magnetized crosswise to the longitudinal axis of the loudspeaker such that a first magnetic pole of the ring material is always closer than a second opposite magnetic pole of the magnetic ring material with respect to the longitudinal axis of the loudspeaker and such that only one of said at least one permanent magnet ring (12) is positioned in any given plane perpendicular to said longitudinal axis of the loudspeaker, whereby magnetic field lines within the ring material are substantially perpendicular to the longitudinal axis of the loudspeaker, wherein the mandrel (11b) is dimensioned for supporting the magnetic ring (12) and arranged such that the mandrel is substantially adjacent only to the inner periphery of the voice coil so that magnetic field lines from the second magnetic pole that pass through the inner periphery and outer periphery of the voice coil form loops that return to the first magnetic pole of the magnetic ring, wherein the portion of substantially all said loops, which extends radially beyond the outer periphery of the voice coil, only passes through air, and possibly the diaphragm, prior to returning to the first magnetic pole of the magnetic ring.