Piezoelectric structures
First Claim
1. 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.
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Accused Products
Abstract
An equivalent to the spatial separation either side of a nominal median plane that is inherent in a bimorph (with one piezoelectric layer on one side, and the second on the other side of the plane) is attained by structurally shaping the cross-section of a simple, single piezoelectric layer (11) such that it has a multiplicity of piezoelectric portions arranged in two generally-planar groups one either side of a median plane, so that any dimension change undergone by a portion on one side of that plane will tend to bend the whole device in the opposite direction to the same sense dimension change undergone by a portion on the other side of that plane. The simple, single layer acts as though it were a bimorph if elongate and beam-like, bending along its length, one end moving up/down, or back/forth, relative to the other but with any need for an internal, electrode.
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Citations
19 Claims
- 1. 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.
- 2. A piezoelectric device that is a generally planar single-layer arcuate strip-like body having overall a broken annular shape, the body being physically shaped in a direction along its arcuate length so as to have corrugations extending across the strip, these corrugations forming separate, distinct piezoelectric-portion groups extending along and 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 strip normal to the median plane across its length in the opposite direction to the same sense piezoelectric portion dimension change in the group on the other side of that median plane.
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11. A method of operating 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,
the method comprising activating the group of portions on one side of the median plane and the group of portions on the opposite side of the median plane to undergo a change in dimensions which is in an opposite sense for the two groups of portions, without clamping the device along the direction in which the portions extend, so that the piezoelectric device bends normal to the median plane along the direction in which the portions extend.
Specification