Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1993-02-11
1995-04-25
Dougherty, Thomas M.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310321, 310334, H01L 4108
Patent
active
054102057
ABSTRACT:
A transducer for transmitting and receiving ultrasonic energy at more than one frequency includes first and second electrostrictive layers mechanically coupled together such that ultrasonic vibrations in one layer are coupled into the other layer. The first electrostrictive layer is laminated between upper and middle electrical contact layers, and the second electrostrictive layer is laminated between middle and lower electrical contact layers. A bias voltage arrangement selectively produces within the first and second electrostrictive layers electric fields oriented in opposite directions or electric fields oriented in the same direction. When the electric fields are oriented in opposite directions, the transducer has a first resonance frequency. When the electric fields are oriented in the same direction, the transducer has a second resonance frequency. By selecting the number of electrostrictive layers in a transducer and by selecting the thicknesses of different layers, a transducer having two or more different desired resonance frequencies may be produced.
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Dougherty Thomas M.
Hewlett--Packard Company
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