Patent ID: 6636612
Filing Date: 2003-10-21
Classification: H04R

Abstract:
A speaker, comprising:a casing having an inner surface and an outer surface; a pole piece within the casing, having an outer surface, and an inner surface defining a venting passage therethrough, a substantially annular gap being defined between the inner surface of the casing and the outer surface of the pole piece; a substantially circular magnet structure in the annular gap, being radially polarized so as to have a first polarity on an inner surface and a second polarity on an outer surface, so as to create a line of magnetic flux following a loop sequentially from the outer surface of the magnet structure to the casing, from the casing to the pole piece, and from the pole piece to the inner surface of the magnet structure, the casing, the pole piece and the magnet structure being mounted to one another to form a magnet assembly which defines an annular coil gap with the path of the loop being across the coil gap; a diaphragm; a suspension mechanism having a first portion attached to the magnet assembly and a second portion attached to the diaphragm so as to mount the diaphragm to the suspension mechanism, the suspension mechanism allowing for travel of the diaphragm relative to the magnet assembly, the diaphragm and the suspension mechanism jointly defining at least part of an enclosure; an electric coil located in the coil gap and having a portion connected to the diaphragm so that an electric current in the coil causes movement of the diaphragm, movement of the diaphragm causing movement of air through the venting passage between the enclosure and externally of the magnet assembly, the travel of the diaphragm being at least 0.1 times a diameter of the diaphragm; and an anti-rocking member having a first portion connected to the magnet assembly and a second portion connected to the diaphragm to limit rocking of the diaphragm relative to the magnet assembly.