TWO-DIMENSIONAL LINEAR B-SCAN ULTRASOUND DIAGNOSTIC APPARATUS WITH PHASE AND AMPLITUDE TAPERING

摘要

An ultrasound diagnostic apparatus includes a linear array of piezoelectric transducers or plates with a width-to-thickness ratio of less than 0.8 and a control circuit which includes a transmitter and a receiver. The transmitter comprises a plurality of transmitting channels each including a local oscillator for generating an ultrasonic pulse in response to a clock signal. The plurality of such ultrasonic pulses are applied through a switching network to a selected group of successively arranged piezoelectric transducers to transmit a beam of ultrasonic energy into a human body. Each of the ultrasonic pulses is phase shifted and amplitude modulated with respect to the ultrasonic pulses of the other transmitting channels to provide phase and amplitude taper which results in a narrow width beam through the depth of the body. The ultrasonic energy returned from discontinuities between different tissues is detected by the activated transducers and applied through the switching network to the receiver in which each of the return signals is phase shifted and amplitude modulated with respect to the other signals to provide an output signal which is displayed on a cathode ray tube screen.