Dynamically variable electronic delay lines for real time ultrasonic

Abstract

A dynamically variable electronic delay line for real time ultrasonic imaging systems is disclosed so as to controllably phase the signals associated with an array of electro-mechanical transducer elements and thereby enable the selective scanning and dynamic focusing of a target. A controllable variable electronic time delay apparatus is coupled to each of the electromechanical transducer elements of the array and in one embodiment thereof constitutes an electronic memory having separate write-in and read-out addressing capabilities. The signals associated with a respective ultrasonic transducer element are fed in at selected write-in addresses and subsequently read-out and extracted after an initial time delay interval. The write-in and read-out address pointers of the memory are continuously sequenced during operation of the device and the time delay interval is a function of the difference between the addresses, as well as the clock rate. The initial delay can be varied by instantaneously modifying either the write-in or the read-out address pointer during the sequencing thereof, such modification being defined as an 'edit-splice' technique. In other embodiments of the invention, the time delay apparatus could comprise a multiple cell memory or register in which a plurality of signals from an associated transducer element are stored and subsequently read-out after an initial time delay, which delay can be changed either by varying the effective length of the shift register or by varying the clock rate at which the shift register advances the signals stored therein, or through an 'edit-splice' technique as above-described.