Apparatus for ultrasonic scanning

Claim 1

Ultrasonic scanning apparatus operable for emission of an ultrasonic transmission pulse and operable during a reception phase for receiving echo pulses from varying scanning depths, during each scanning operation, said apparatus having an ultrasonic applicator comprising a plurality of ultrasonic transducer elements spatially adjacently arranged in a surface, reception means for association with the transducer elements, and control means controlling focussing of the transducer elements to varying scanning depths by connecting respective corresponding sets of said transducer elements with said reception means in accordance with predeterminable surface patterns, characterized by the following relationships which prevent switching clicks occurring in the reception phase upon switching of surface patterns from reaching the ultrasonic transducer elements as noise echoes: (a) said reception means comprising reception lines connecting with the respective ultrasonic transducer elements; and said reception means having a series connection of a buffer amplifier (18, 19, 20, etc.), an input switch (S3, S31, S32) and an output switch (S4, S41, S42) inserted at least in the reception line of each transducer element (W1, W2, W3, etc.); (b) each buffer amplifier (18, 19, 20, etc.) being arranged in such manner that its input is connected to the input switch (S3, S31, S32) at the transducer element (W1, W2, W3, etc.); (c) said control means comprising a control installation for the input and output switch of each buffer amplifier which closes the input switch (S3, S31, S32) of the buffer amplifier in the time between emission of a transmission pulse and reception of echo pulses and only subsequently also closes the output switch (S4, S41, S42) for the actual reception of echo pulses, (d) said control installation providing means whereby the switching click respectively generated upon closing the input switch (S3, S31, S32) cannot disturb the transducer elements since the closing of the input switch ensues outside of the actual reception phase, and (e) said buffer amplifier providing means whereby the closing of the output switch (S4, S41, S42) in the reception phase is not disruptive because such closing only occurs at the output of the respective buffer amplifier so that switching clicks are blocked with respect to the transducer elements by means of the buffer amplifiers.