| 摘要 |
1. An ultrasonic imaging apparatus comprising a transducer device made up of a fixed elongate row of transducer elements (11) and apt to be activated for transmitting an ultrasonic beam (12) by converting pulsed signals sent from a transmitter (232), each transducer element (11) being supplied with a transmitter signal having a predetermined position in time, characterized in that the transmitter contains : a) A multiplier (152) for obtaining the product of a pulse (162) by a pulse sequence (161) at the transmitter frequency ; b) A first multiplexer (146) connected to one input of the multiplier, the multiplexer inputs (148) being supplied with a plurality of pulse sequences at the transmitter frequency at a predetermined phase angle and offset from one another by a fraction of a period of the transmitted signal, the multiplexer responding to a first control signal (144) for supplying a first input of the multiplier with a selected pulse sequence having a suitable phase angle ; c) A second multiplexer (145) connected to a second multiplier input, the multiplexer inputs (147) being supplied with a plurality of pulses which are delayed by varying amounts relative to a reference signal and the duration of which covers a number of pulses of a pulse sequence at the transmitted frequency, the second multiplexer responding to a second control signal (143) for supplying a second multiplier input with a chosen pulse having a suitable delay relative to the reference signal, and d) A signal-shaping device (153) connected to the multiplier output and adapted to derive from the multiplier output signal a transmitting pulse (165) containing a sine wave at the transmitted frequency, the pulse being supplied to a component (11) of the ultrasonic converter system. |
