| 摘要 |
An ultrasonic device for dynamic variation of the receiving focal position of a prescribable number of ultrasonic transducer elements has connected downstream of each ultrasonic transducer element a receiving channel with a time-delay circuit (2) for the received ultrasonic echo signal. For the purpose of switching over between different prescribed time-delay values (T1, T2, ... Tn), the time-delay circuit (2) is connected to a control device (14). A section of the time-delay circuit (2) is provided in duplicate, so that a first and a second subcircuit (2A, 2B) are available for forming the time-delayed ultrasonic echo signal. A cross-fading circuit (13) is provided, which ensures that the second subcircuit (2B) is respectively faded in in the receiving channel when the first subcircuit (2A), which is in the faded-out state, is switched over by the control device (14) to another time-delay value (T1, T2, ... Tn), and vice versa. The advantage of the ultrasonic device is saving in time when switching over between the different focal positions of the ultrasonic device. Furthermore, when isolation amplifiers are used, it is possible to prevent transmission of switch clicks to the respectively activated subcircuit (2A, 2B). <IMAGE>
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