US 4,396,895 AGranted

Multiple resonant electromechanical filters using edge-mode vibration of a long piezoelectric plate

AssigneeTohoku Metal Industries, Ltd.

InventorsHiroshi Shimizu, Yuji Iseki, Hiroshi Watanabe

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Abstract

A multimode piezoelectric mechanical filter using edge-mode piezoelectric transducers, each comprising a semi-infinite or long piezoelectric plate polarized in the thickness direction, and a pair of exciting electrodes formed on the plate at an end portion thereof. Input and output edge-mode transducers are supported at their other ends together with optional resonator elements. The transducer and/or resonator elements are mechanically coupled with one another by a coupling rod at their end portions opposite the support to transmit the edge-mode vibration from one to the other. All of the transducers and resonator elements may be disposed in a common plane and may be integrally formed by punching a single piezoelectric plate to form a monolithic type mechanical filter. In such monolithic type filter, coupling rods are also integrally formed with the transducers and resonators. Alternatively, the transducer regions and/or resonator regions are separated and defined by a slit or slits formed in a large square piezoelectric plate, the bottom portion of each slit being usable as the mechanical coupling.

Claims37

Dependent claims

A multiple resonant mechanical filter using edge-mode vibration of a long piezoelectric plate comprising:

an input resonator/transducer element which has a first long piezoelectric plate means polarized in its thickness direction and having a width determined by a predetermined resonance frequency, first and second exciting electrode means formed on an end portion of said first long piezoelectric plate means to excite said first piezoelectric plate means to vibrate in an edge mode, and first and second input terminal means connected with said first and second exciting electrode means, respectively;
an output resonator/transducer element which has a second long piezoelectric plate means polarized in its thickness direction and having a width determined by a predetermined resonance frequency, first and second output electrode means formed on an end portion of said second long piezoelectric plate means to take out a signal corresponding to edge-mode vibration of said second piezoelectric plate means, and first and second output terminal means connected with said first and second output electrode means, respectively;
means for mechanically coupling said input resonator/transducer element and said output resonator/transducer element to transmit the edge-mode vibration from said input resonator/transducer element to said output resonator/transducer element;
means for electrically connecting said second input terminal means and said second output terminal means;
and
means for supporting said first and second piezoelectric plate means at the other end portions thereof.

3 more elements

Dependencies are inferred from the claim text.