Electrodynamic transducer e.g. loudspeaker, for generating sound waves, has confinement units to confine magnetic field in gap to form bilateral seals in gap for guiding coil and forming pneumatic seal between front and rear faces of dome

摘要

The transducer has an electrodynamic motor with a coil (6) supported by a mandrel (3). The mandrel is connected to a dome (2) suspended from a frame (7) e.g. basket assembly. The coil is disposed in a gap, in which the coil is defined at a centre by an inner magnetic structure (4) and at periphery by an outer magnetic structure (5). Confinement units (11) confine magnetic field in the gap to form tiered bilateral seals (12) in the gap using a ferromagnetic liquid for guiding the coil and forming a pneumatic seal between the front and rear faces of the dome.