Patent ID: 8422724

Claim:
A loudspeaker including a frame, a drive unit, and a membrane; the membrane having an inner edge, an outer edge which is suspended from the frame, and a membrane body which is between the inner and outer edges and extends around the drive unit; the drive unit having a stationary part secured to the frame and a translatable part secured to the inner edge of the membrane; the membrane body including a dished portion which, has a depth that increases from said inner and outer edges towards a base region of the dished portion located between said edges, wherein the base region of the dished portion is a face in the membrane body located at the deepest part of the dished portion; wherein the loudspeaker includes a circular stiffening element which extends around the drive unit, wherein the circular stiffening element is located on the outwardly dished side of the dished portion of the membrane body and is attached to the membrane body at the base region of the dished portion, thereby stiffening the membrane body at the base region of the dished portion, so as to reinforce the membrane against deformation in the base region; wherein the stiffening element, when viewed in cross-section, includes a “v” shaped corrugation with flat faces at each side of the corrugation.