Patent ID: 7224813

Claim:
A loudspeaker, comprising: a support; a sound-generating element mounted relative to the support for vibration in a vibration direction to generate sound; and an electro-active device coupled to the sound-generating element for vibrating the sound-generating element in response to an electrical signal, the electro-active device comprising a continuous electro-active member having two ends between which ends the member extends along, and curves in a helix around, a minor axis, which minor axis extends in a curve around a major axis parallel to the vibration direction of the sound-generating element, the continuous electro-active member being arranged with electrodes to bend around the minor axis on activation in response to application of the electrical signal to the electrodes, and coupled together such that bending of the continuous electro-active member causes concomitant rotation of the continuous electro-active member around the minor axis adding incrementally along the minor axis, which rotation causes concomitant relative displacement of the two ends of the continuous electro-active member along the major axis.