Two-dimensional linear B-scan ultrasound diagnostic apparatus with phase and amplitude tapering

Claim 1

An ultrasound diagnostic apparatus comprising: an array of successively arranged plate-like piezoelectric elements each having a width-to-thickness ratio equal to or smaller than 0.8 and an electromechanical coupling coefficient close to k 33 or k' 33 in the direction of the thickness; a source of clock pulses; a first switching network having a plurality of output terminals connected respectively to said piezoelectric elements to establish access paths between a plurality of input terminals and a group of successively arranged ones of said piezoelectric elements to activate same in response to each of said clock pulses; means for causing said first switching network to establish said access paths such that said group of the activated piezoelectric elements is shifted by at least one piezoelectric element in response to each of said clock pulses; a second switching network having a plurality of output terminals connected to the input terminals of said first switching network and a plurality of input terminals to establish access paths between said input and output terminals thereof; a transmitter having means for generating a train of timing control signals in response to each of said clock pulses and a plurality of amplitude control signals, and a plurality of transmitting channels connected respectively to the input terminals of said second switching network, each of said transmitting channels including an oscillator responsive to a respective one of said timing control signals to generate an ultrasound pulse and an amplitude modulator for modulating the amplitude of said ultrasound pulse in accordance with a respective one of said amplitude control signals; means for causing said second switching network to establish said access paths for application of said ultrasound pulses respectively to said activated piezoelectric elements; a receiver having means for generating a plurality of phase control signals and a plurality of second amplitude control signals, and a plurality of receiving channels connected to said input terminals of said first switching network to receive signals detected by said activated piezoelectric elements, each of said receiving channels having a phase shifter for imparting a phase shift to the detected signal in accordance with a respective one of said phase control signals and an amplitude modulator for modulating the amplitude of the phase shifted signal in accordance with a respective one of said second amplitude control signals; and a display unit responsive to the output signal from said receiver.