BENDING WAVE PANEL LOUDSPEAKERS

摘要

A bending wave loudspeaker having a panel -form acoustic radiator and an electromagnetic actuator coupled to drive the radiator in bending to produce an acoustic output, the actuator comprising a magnet assembly comprising a magnet mounted to a substantially planar pole piece, a coil assembly comprising a substantially planar voice coil mounted on a substantially planar rigid substrate, means suspending the substrate adjacent to the magnet assembly whereby the magnet lies adjacent to the voice coil with an air gap between the voice coil and the magnet, and wherein the substrate is mounted to or is integral with the radiator whereby the actuator can drive the radiator. The magnet assembly may comprise an annular magnet and a disc- like pole piece and the substrate may be disc-like. The loudspeaker may comprise coupling means connected between the substrate and the radiator and the coupling means may be annular and concentric with and positioned adjacent to the voice coil. Preferably the coupling means is positioned on the substrate substantially in line with the resultant of the electromagnetic force. From another aspect, the invention is a bending wave loudspeaker actuator as described above. From a further aspect, the invention is panel-form vehicle trim comprising a loudspeaker as described above. From a still further aspect, the invention is a greetings card comprising a loudspeaker as described above, and having a self-supporting leaf forming the radiator.