Focusing piezoelectric ultrasonic medical diagnostic system

• US 4,276,491 A
• Filed: 10/02/1979
• Issued: 06/30/1981
• Est. Priority Date: 10/02/1979
• Status: Expired due to Term

• Current Assignee: Ausonics International Pty., Limited
• Original Assignee: Ausonics Pty., Limited
• Inventors: Daniel, Keith P.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US06/081,272
• Time in Patent Office: 637 Days
• Field of Search: 310/334-337, 310/371, 310/367, 310/366, 310/317, 128/660
• US Class Current: 310/317
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/13 Tomography A61B8/10, A61B8/12 take precedence; tomography for radiation diagnosis A61B6/02
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01S 15/8952 using discrete, multiple frequencies
• CPC Class Codes: G10K 11/32 characterised by the shape of the source

Abstract

There is disclosed an ultrasonic piezoelectric transducer consisting of two separate transducer elements bonded together. The individual elements may be similar or different in size, thickness, and/or material. The material which bonds the two elements together may serve as one electrode, and two other electrodes coat the outer surfaces of the two individual elements. By switching the electrodes which are connected to the transmit and receive circuits of an ultrasonic medical scanning apparatus, the single transducer may be used for imaging with high resolution at one frequency, and for pulse Doppler velocity measurements at a different frequency. The two elements may be driven individually or in combination, in order to achieve different operating frequencies and focusings.

Claims

1. An ultrasonic medical diagnostic system comprising a first transducer element;

a second transducer element;

electrodes coating the front and back surfaces of both of said transducer elements, with the back electrode of said first transducer element and the front electrode of said second transducer element being bonded together;

means for controlling pulse echo operation at one frequency, with relatively low penetration and high resolution, by applying an energizing signal across the front and back electrodes of one of said transducer elements; and

means for controlling Doppler operation at another lower frequency, with relatively high penetration and low resolution, by applying an energizing signal across the front electrode of said first transducer element and the back electrode of said second transducer element.

2. An ultrasonic medical diagnostic system in accordance with claim 1 wherein both of said transducer elements are curved and have mating radii of curvature.

3. An ultrasonic medical diagnostic system in accordance with claim 1 wherein said first transducer element has a diameter larger than of said second transducer element.

4. An ultrasonic medical diagnostic system in accordance with claim 1 wherein said first and second transducer elements have the same thickness.

5. An ultrasonic medical diagnostic system in accordance with claim 1 wherein said first and second transducer elements have different thicknesses.