Ultrasonic transducer having two or more resonance frequencies
February 11, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2589403 3093760 3401377 3462746 Variable acoustic wave energy transfer-characteristic control device Ultrasonic probe Fresnel focussed imaging system Front surface matched piezoelectric ultrasonic transducer array with wide field of view Apparatus and method for suppressing mass/spring mode in acoustic imaging transducers Acoustic electric transducer with shield of controlled thickness InventorApplicationNo. 016373 filed on 02/11/1993US Classes:310/328, With mechanical energy coupling means310/321, Combined with resonant structure310/334Acoustic wave type generator or receiverExaminersPrimary: Dougherty, Thomas M.Foreign Patent References
International ClassH01L 041/08AbstractA 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.Other References
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