Patent ID: 7166952

Claim:
A piezoelectric device the body of which is a single layer of piezoelectric material shaped so as to have a multiplicity of separate, distinct piezoelectric portions disposed in two generally planar groups that extend along, one on each side of, a nominal median plane through the whole body, which groups are thus spatially separated by and face each other across that median plane, with the result that any piezoelectric portion dimension change in the group on one side of the median plane will tend to bend the device normal to the median plane in the opposite direction to the same-sense piezoelectric portion dimension change in the group on the other side of that median plane, wherein the body is shaped as a ring, part ring or annulus, or as a disk, and the shape is corrugated such that the corrugations are straight across the body, and thus generally radial, or are at some angle to the theoretical radii, and are either straight or alternatively slightly curved into arcs.