초록 ▼

A miniature piezoelectric transducer element is provided, comprising; (a) a cell element having a cavity; (b) a flexible piezoelectric layer attached to the cell member, the piezoelectric layer having an external surface and an internal surface, the piezoelectric layer featuring such dimensions so a

A miniature piezoelectric transducer element is provided, comprising; (a) a cell element having a cavity; (b) a flexible piezoelectric layer attached to the cell member, the piezoelectric layer having an external surface and an internal surface, the piezoelectric layer featuring such dimensions so as to enable fluctuations thereof at its resonance frequency upon impinging of an external acoustic wave; and (c) a first electrode attached to the external surface and a second electrode attached to the internal surface of the piezoelectric layer. At least one of the electrodes may be specifically shaped so as to provide a maximal electrical output, wherein the electrical output may be current, voltage or power. A preferred shape of the electrodes includes two cores interconnected by a connecting member. The transducer element may function as a transmitter. When used as a transmitter, the electrodes are electrically connected to an electrical circuit including a switching element for modulating the reflected acoustic wave by controllably changing the mechanical impedance of the piezoelectric layer according to the frequency of an electrical message signal arriving from an electronic member, such as a sensor. Third and fourth electrodes may be attached to the piezoelectric layer and the electrical circuit, such that the switching element alternately connects the electrodes in parallel and anti-parallel electrical connections so as to controllably change the mechanical impedance of the piezoelectric layer.

대표청구항 ▼

[ What is claimed is:] [1.] A transducer element for converting acoustic wave energy transmitted through an external fluid medium into electric energy, comprising:(a) a cell member having a cavity;(b) a substantially flexible piezoelectric layer peripherally attached to said cell member so as to iso

[ What is claimed is:] [1.] A transducer element for converting acoustic wave energy transmitted through an external fluid medium into electric energy, comprising:(a) a cell member having a cavity;(b) a substantially flexible piezoelectric layer peripherally attached to said cell member so as to isolate said cavity from the external fluid medium, said cavity containing gas and having a substantially lower acoustic impedance than said external fluid medium, a central portion of said piezoelectric layer not rigidly affixed with respect to said cavity, said piezoelectric layer having an external surface and an internal surface, said piezoelectric layer featuring such dimensions so as to enable fluctuations thereof in-and-out of said cavity at its resonance frequency upon impinging of an acoustic signal transmitted through the external fluid medium, said resonance frequency determined by the physical dimensions of said cavity and said piezoelectric layer wherein the wavelength of the acoustic signal is substantially larger than said dimensions; and(c) a first electrode attached to said external surface and a second electrode attached to said internal surface.