JPS5886149A - Drive circuit of ultrasonic probe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to refreshing the 5CS path of a vibrator made of piezoelectric material in an ultrasonic tomography device.

In an ultrasonic tomography device, increasing the power of the ultrasonic waves emitted into the living body increases the reflected echoes and increases the noise-to-noise ratio of the image, which is effective in brightening the image. The present invention achieves the above object by modifying the principle circuit of the vibrator. The present invention will be explained below in comparison with a conventional example.

Figure 1 shows a conventional probe-driving circuit. Here, 1 is a thyristor, 2 and 3 are resistors, 4 is a capacitor 5 is an inductor, and 6 is a vibrator made of a piezoelectric material, which constitutes the main part of the probe. Incidentally, the inductor 5 forms a resonant circuit together with the pendulum 6, and is designed to intensify the ultrasonic waves sent out from the transducer 6.In addition, the capacitor t4 connects the power supply through the resistors 2 and 3 when the thyristor 1 is in the off state. It is more charged and stores charge. The time setting # of the first charging path of the resistor 2 and the capacitor 4 is set to a value such that the capacitor is fully charged during the repetition time of transmitting ultrasonic waves from the probe, that is, while the thyristor 1 is in the cutoff foreshadowing. I have chosen it.

When a pulse voltage is applied to the gate of the thyristor 1 to make it conductive, the voltage at the terminal of the capacitor 1 is applied to the vibrator 6.

Figure 2 shows the voltage waveforms of each part of this and nothing, (1) is the gate voltage of thyristor 1, (2) is the output voltage waveform of drive circuit γ, and (3) is the voltage waveform of oscillator 6 in Figure 1. This is the voltage waveform that is actually applied.

In this case, the next thyristor I is used as a switching element.
When a pulse voltage is applied to the gate of Fi and the gate becomes conductive, it cannot be brought into a continuous state as long as current flows. Therefore, the thyristor 1 remains conductive until the charge on the capacitor is discharged and the conduction current becomes almost zero. This rounding 1. Figure 2 (3
) The value of voltage V shown in ) cannot be made too large.

The present invention improves this drawback by focusing on the fact that field-effect power transistors or bipolar transistors can be controlled even when current is flowing.
There are nine pieces using this as a switching element. In other words, by using a switching element that can be controlled in a controlled manner during conduction, by closing the switching element, applying voltage to the transducer, and bringing the switching element into a disconnected state after a certain period of time T has elapsed, the probe can be detected. It is a round thing that increases the ultrasonic power emitted from the child.

Next, an embodiment based on the invention is shown in FIG. 3'. The same figure shows a round metal circuit using a field effect power transistor 7 transistor 8 as a switching element, and the voltage waveforms of each part are shown in FIG. The voltage waveform is shown in (2), and the voltage waveform applied to the vibrator is shown in (3).

Here, the pulse voltage $T applied to the gate of the field effect power transistor 8 is set approximately equal to the half period of the pulse) & applied to the vibrator. That is, when a pulse voltage (2) is applied to the gate, the field effect transistor 8Fi enters the open state, causing the vibrator 6 to become in the running state after half a cycle of t'. In this way, the voltage applied to the transducer 6 (the voltage of the voltage applied to the transducer 6 becomes much larger than that of the conventional example, and the sound output from the probe) can be increased. This is because the conventional example uses step drive, whereas the present invention has a component corresponding to the resonant ridges of the vibrator as a fundamental wave.

As an example, an array type probe made by adhering 32 11$ 0.4 mm piezoelectric elements with a resonance cycle of 2.4 MHz to rubber with barium ferrite mixed therein was used as a probe. When the driving circuit 9 according to the present invention is applied, the sound pressure of the emitted ultrasonic waves can be increased by 70% by 11 degrees compared to the conventional driving circuit.

As explained above, by using the drive circuit according to the present invention, the ultrasonic output of the probe can be greatly increased compared to the conventional one, and the effect is significant.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a configuration example of a conventional drive circuit, FIG. 2 is a voltage waveform diagram of each part in FIG. 11 above, FIG. 3 is a circuit diagram showing an embodiment of the present invention, and FIG. It is a voltage waveform diagram of each part of the same part. 1...Thyristor, 2.3-...Resistor, Number...Fundensor, 5...Inductor, 6...Resonator,)...
・Drive circuit, 8... Field effect power transistor, 9・
...Drive circuit. Medium 1 Illustration 2 Illustration

Claims (1)

[Claims] An ultrasonic drive circuit I comprising a piezoelectric vibrator and an inductor, a charge charged in a capacitor is applied to the vibrator through a switching element, and the conduction time of the switching element is detected as described above. This is a super-touch drive circuit characterized by a vibration of 1/8 of the resonance period of the touch.