Ultrasound diagnostic apparatus
View Patent ↗An ultrasound diagnostic apparatus according to a present embodiment includes driving pulse generating circuitries and a transmission control circuitry. The transmission control circuitry turns on a switching element of respective driving pulse generating circuitries of the driving pulse generating circuitries to be grounded, and thereby controls so as to make an output impedance of the respective driving pulse generating circuitries become a low impedance. The transmission control circuitry turns off the switching element of the respective driving pulse generating circuitries, and thereby controls so as to make the output impedance become a high impedance by means of a resistance value of the resistance. The transmission control circuitry controls so as to make the output impedance of the respective driving pulse generating circuitries become a lower impedance during a transmission period in which the ultrasound is transmitted than during a reception period in which a reflected wave of the ultrasound is received.
1. An ultrasound diagnostic apparatus that controls transducers each corresponding to a channel of channels that are independent to cause the transducers to transmit and receive an ultrasound, comprising:
a transmission control circuit configured to control each channel of the channels to be a transmission channel which transmits the ultrasound or a non-transmission channel which does not transmit the ultrasound; and
driving pulse generating circuits each including a driving pulse generation source in which one end side of two ends is grounded, each including a resistance connected with the other end side of the driving pulse generation source and with a transducer of the transducers, and each including anti-parallel diodes connected in parallel with the resistance, the driving pulse generation source, the resistance and the transducer being connected in series, and each of the driving pulse generating circuits being configured to apply a driving pulse to the transducer,
the transmission control circuit being configured to:
ground the resistance through the driving pulse generation source, and thereby control so as to make an output impedance of a driving pulse generating circuit corresponding to the non-transmission channel a low impedance, and so as to make an output impedance of a driving pulse generating circuit corresponding to the transmission channel a high impedance by using a resistance value of the resistance, and
control so as to make an output impedance of each of the driving pulse generating circuits as seen from the transducer, during a transmission period in which the ultrasound is transmitted, a lower impedance than during a reception period in which a reflected wave of the ultrasound is received, by placing anti-parallel diodes corresponding to at least the non-transmission channel in an “off” state during the transmission period and making an output impedance of each of driving pulse generating circuits corresponding to at least the non-transmission channel a resistance value of the resistance.
2. The ultrasound diagnostic apparatus according to claim 1 , wherein
the transmission control circuit is further configured to control so as to make the output impedance of each of the driving pulse generating circuits a higher impedance than an impedance in a reception circuit in all channels during the reception period.
3. The ultrasound diagnostic apparatus according to claim 1 , wherein
the transmission control circuit is configured to generate a control signal for forming the driving pulse, and a control signal that distinguishes between the transmission period and the reception period.
4. The ultrasound diagnostic apparatus according to claim 1 , wherein
the resistance, connected in parallel with the anti-parallel diodes, is configured to suppress transmission of a switching noise that is generated by switching between the low impedance and the high impedance to the transducers and a reception circuit.
5. The ultrasound diagnostic apparatus according to claim 4 , wherein
the resistance is configured to suppress distortion of a transmission pulse waveform that is generated by the anti-parallel diodes in a low voltage period.
6. The ultrasound diagnostic apparatus according to claim 1 , further comprising
an ultrasound probe including the transducers.
7. The ultrasound diagnostic apparatus according to claim 1 , wherein
the transmission control circuit is configured to control the transmission channel and the non-transmission channel in accordance with an aperture width.
8. The ultrasound diagnostic apparatus according to claim 1 , wherein
the transmission control circuit is configured to control the transmission channel and the non-transmission channel in accordance with a transmission sound pressure under a harmonic imaging.
9. The ultrasound diagnostic apparatus according to claim 1 , wherein
the transmission control circuit is configured to control so as to make the output impedance of each of the driving pulse generating circuits as seen from the transducer, during the transmission period, the lower impedance than during the reception period, by placing anti-parallel diodes corresponding to the transmission channel in an “off” state during the transmission period.