Patent US 4,287,768

Beam deflection delay time data of (L.times.M) data bits are stored in a read-only memory from which each datum is retrieved successively when the ultrasound beam is deflected to a given angle and repeatedly accumulated in a digital adder through a latching circuit connected between the output and input of the adder, where L is the number of discrete steps of deflection angle and M is a binary number representing the total delay time of piezoelectric transducers. The successively latched data is distributed to respective programmable counters for presetting the count values thereof to store therein respective delay time data. High frequency count pulses are supplied to the counters after the latter has been preset for delivery of carry outputs to the associated piezoelectric transducers. Beam convergence delay time data is also stored in a second memory from which each datum is retrieved for each transducer element and accumulated so that a tapered configuration of binary differential numbers is created and added to the beam deflection delay time data for converging the ultrasound beam.