Sri International

Hewlett-packard Company

David A Wilson

James L Buxton

Philip S Green

J Fleming Dias

John D Larson

Donald J Burch

S David Ramsey, Jr

Amin M Hanafy

John F Holzemer

H Edward Karrer

The acoustic imaging transducer described herein incorporates an acoustic stack contained in an alumina housing which also provides structure for electrically connecting the transducer array elements to system signal processing electronics.

Acoustic imaging transducer

An ultrasonic imaging system (50) has an array (52) of transducer elements (54-1 through 54-21) for receiving ultrasonic signals reflected from within an inhomogeneous object (16) being examined. The system (50) has a means (80, 84, 88, 94) connected to generate an image in response to the ultrasonic signals. A cross-correlator (70) is connected to compare the signals received by the transducer elements (54-1 through 54-21). An output addressing circuit (130) is connected to inhibit or otherwise modify gain of selected ones of the signals based on the comparison to reduce multipath ultrasonic wave interference, refraction or obstruction image distortion or degradation. A preferred ultrasonic imaging array (52) for this purpose and for time delay image distortion correction has a plurality of segmented, annular transducer elements (54-2 through 54-21). The elements (54-2 through 54-21) are formed as sectors of circles with substantially equal arc lengths. A digital signal processing circuit for the system (50) has a plurality of dual port RAMs (66-1 through 66-21) as delay lines and a cross-correlator (70) including an output addressing circuit (130) controlled by a microcomputer (128). The output addressing circuit (130) generates addresses for output of information from the dual port RAM delay lines (66-1 through 66-21) to accomplish time delay correction and elimination or other gain modification of ultrasonic signals with multipath interference, refraction or obstruction.

Ultrasonic imaging system with correction for velocity inhomogeneity and

This ultrasonic imaging apparatus has an array (44, 52 or 100) of transducer elements (44, 50 or 104) for transmitting ultrasonic signals having a first predetermined center frequency (fc1) into an object (12) to be analyzed through use of the transmitted signals reflected from within the object. A means (150, 116-1 through 116-X and 120-1 through 120-X) is connected to transmit the ultrasonic signals from the array (44, 52 or 104) in a stepped array mode. A means (150, 116-1 through 116-X and 120-1 through 120-X) is connected to transmit the ultrasonic signals from the array (44, 52 or 104) in an angle scanning mode. There is a means (150, 128-1 through 128-X) for focusing the transmitted signals at a desired depth within the object (12). The reflected signals sensed by the apparatus have a second center frequency (fc2) less than the first center frequency (fc1) as a result of signal attenuation by the object (12). There is a means connected to select between the stepped array transmission mode and the angle scanning transmission mode for operating the array elements based on the second center frequency (fc2). Varying the operating mode of the apparatus on this basis gives improved image resolution over a wider operating range than with prior art systems.

Frequency controlled hybrid ultrasonic imaging arrays

An ultrasonic imaging apparatus has an array (10 or 100) of transducer elements (14 or 104) for transmitting ultrasonic signals into an object (12) to be analyzed through use of the transmitted signals reflected from the object and sensed by the apparatus. The transmitted signals have a first predetermined center frequency. The reflected signals sensed by the apparatus have a second center frequency less than the first center frequency as a result of signal attenuation by the object. A means (70, 62 or 150, 152-1 through 152-X) is connected to select a number of transducers (14 or 104) in the array (10 or 100) for transmitting and/or receiving the ultrasonic signals based on the second center frequency. Adjusting the number of transmitting and/or receiving transducers (14 or 104) with changes in frequency produced by signal attenuation gives improved image resolution under a wider variety of use conditions than with prior art ultrasonic imaging apparatus.

Frequency varied ultrasonic imaging array

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Palo Alto, CA, United States of America

David A Wilson