ULTRASOUND DIAGNOSTIC DEVICE
An ultrasound diagnostic device includes: a transmission pulser that applies a driving pulse output signal to an ultrasonic transducer so as to cause the ultrasonic transducer to irradiate ultrasound; and a trigger signal generator that generates a trigger signal that controls the transmission pulser to output the driving pulse output signal. The trigger signal generator adds, to the trigger signal in a predetermined term after completion of a driving term of the ultrasonic transducer, a plurality of trigger pulses that control an amplitude of an ultrasonic transducer output signal generated upon completion of the driving term so as to attenuate gradually. With this configuration, a free vibration of the ultrasonic transducer in a transient response can be suppressed with the minimum number of circuit materials.
1 . An ultrasound diagnostic device comprising:
a transmission pulser that applies a driving pulse output signal to an ultrasonic transducer so as to cause the ultrasonic transducer to irradiate ultrasound; and
a trigger signal generator that generates a trigger signal that controls the transmission pulser to output the driving pulse output signal;
wherein the trigger signal generator adds, to the trigger signal in a predetermined term after completion of a driving term of the ultrasonic transducer, a plurality of trigger pulses that control an amplitude of an ultrasonic transducer output signal generated upon completion of the driving term so as to attenuate gradually.
2 . The ultrasound diagnostic device according to claim 1 , wherein the trigger pulses cause, in the predetermined term after completion of the driving term of the ultrasonic transducer, the ultrasonic transducer output signal generated upon completion of the driving term to keep a driving period in the driving term while attenuating the amplitude gradually.
3 . The ultrasound diagnostic device according to claim 1 , wherein the trigger pulses cause, in the predetermined term after completion of the driving term of the ultrasonic transducer, the ultrasonic transducer output signal generated upon completion of the driving term to attenuate the amplitude gradually by means of setting at least one of a pulse starting point, a pulse width, the number of pulses and a pulse pause term.
4 . The ultrasound diagnostic device according to claim 1 ,
wherein the driving pulse output signal includes a positive driving pulse and a negative driving pulse, and
the transmission pulser has a first switch that generates the positive driving pulse to the ultrasonic transducer and a second switch that generates the negative driving pulse to the ultrasonic transducer.
5 . The ultrasound diagnostic device according to claim 4 , wherein the trigger signal includes a first trigger signal that controls the first switch and a second trigger signal that controls the second switch.
6 . The ultrasound diagnostic device according to claim 5 , wherein, after completion of the driving term of the ultrasonic transducer, the trigger signal brings the first switch and the second switch into an ON state alternately at 1/2 period of the driving period and shortens time of the ON state gradually per 1/2 period of the driving period.
7 . The ultrasound diagnostic device according to claim 5 , wherein when ON/OFF of the first switch and the second switch changes in the driving term, the trigger signal brings the first switch and the second switch into an OFF state simultaneously.
8 . The ultrasound diagnostic device according to claim 5 , further comprising a switching element for replacing, with each other, the first trigger signal and the second trigger signal to be input to the first switch and the second switch,
wherein pulse inversion harmonic imaging is performed by controlling the switching element.
9 . The ultrasound diagnostic device according to claim 5 , wherein an ON/OFF frequency of the first trigger signal and an ON/OFF frequency of the second trigger signal are lower than a center frequency of the ultrasonic transducer.
10 . The ultrasound diagnostic device according to claim 5 , wherein an ON/OFF frequency of the first trigger signal and an ON/OFF frequency of the second trigger signal are higher than a center frequency of the ultrasonic transducer.