JP2645066B2 - Ultrasonic pulse drive circuit and ultrasonic calculus crushing device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasonic calculus crushing apparatus for crushing a calculus from outside the body using the energy of an ultrasonic vibrator and a pulsed ultrasonic vibrator. The present invention relates to an ultrasonic pulse driving circuit to be driven.

(Prior Art) In recent years, attempts have been made to crush stones in a body in a non-contact manner by energy generated from an ultrasonic transducer. This is an alternative to the calculus crushing device utilizing the shock wave energy due to electric discharge, which has recently been put into practical use, and has attracted attention due to features such as miniaturization, low cost, and no need for consumables.

FIG. 3 shows the structure of a conventional ultrasonic calculus breaking device. The crushing transducer 31 is composed of a plurality of transducer groups each having the same spherical surface, and an ultrasonic probe 32 for imaging is provided at the center thereof. Normally, imaging probe over body surface 34
After matching the calculus 33 with the focus of the crushing energy by the ultrasonic image obtained from the
And crushing is performed.

At this time, the ultrasonic probe 32 can move back and forth,
If the calculus 23 is at a deep position, the calculus 23 is retracted to the front. Conversely, if the calculus 23 is at a shallow position, the calculus 23 is used closer to the body surface 24 to improve the quality of the ultrasonic image.

On the other hand, the ultrasonic piezoelectric vibrator is most efficiently driven,
When a circuit is formed for the purpose of obtaining a large output, a method of connecting an inductance in series or parallel in accordance with the capacitance of the piezoelectric vibrator so as to resonate at the resonance frequency of the piezoelectric vibrator to be used is used. FIG. 4 shows the configuration of a conventional ultrasonic pulse drive circuit. When a gate waveform as shown in FIG. 5A is applied to the switching transistor 42, the switching transistor 41 is switched from the inductance 42 during the switch-on time. current flows through the drain-source of off-the counter electromotive force is generated in the inductance 42 at the same time, as in the FIG. 5 (b), a large voltage generated than the DC voltage V _H applied to the inductance 42. Thereafter, the drain waveform attenuates and vibrates at a resonance frequency determined by the value of L of the inductance 42 and the value of the capacitance of the ultrasonic vibrator 44.

The wiring that connects the switching transistor 41 through the ultrasonic transducer 44 and the coupling capacitor 43 is generally made using a connector, and an overvoltage is applied to the switching transistor 42 due to forgetting to install the connector, disconnection, poor contact, etc. May occur. That is, since the output voltage of the circuit is determined depending on the load capacity, there is a problem that in a no-load state, an overvoltage is generated such that the switching transistor 41 is destroyed.

(Problems to be Solved by the Invention) It is an object of the present invention to provide a supersonic transducer that can prevent a superconductor and an overvoltage from being caused by forgetting to attach a connector for connecting an ultrasonic vibrator, disconnection, and poor contact, thereby preventing damage to a switching transistor. An object of the present invention is to provide an ultrasonic pulse driving circuit and an ultrasonic calculus breaking device using the same.

[Constitution of the Invention] (Means for Solving the Problems) The present invention relates to a switching transistor, an inductance connected to an ultrasonic vibrator, and a means for absorbing an overvoltage connected in parallel with the ultrasonic vibrator. The present invention provides an ultrasonic pulse drive circuit characterized by having: and an ultrasonic calculus breaking device using the same.

(Operation) According to the present invention, an overvoltage generated in a no-load state due to forgetting to attach a connector, disconnection, poor contact, or the like is absorbed,
In addition, it is possible to stop the generation of the next pulse output.

(Example) An example of the present invention is shown in FIG.

Also in this embodiment, the crushing transducer 1 is composed of a plurality of ultrasonic transducers as in the conventional example, and each of the transducers is driven by the high-voltage pulser 3. An ultrasonic probe for image 2 is provided at the center of the crushing transducer 1 and is movable back and forth as in the conventional example, and extracts an ultrasonic image in a living body.

The probe 2 is connected to a position detection circuit 4 composed of a gear, a potentiometer, and the like, and sends a signal corresponding to a relative position between the crushing transducer 1 and the probe 2 to a controller 5. The controller 5 is A / D.CP
For example, when the probe 2 is at the position A, the vibrator group 1b in a portion that is in the shade of the probe 2 when viewed from the geometric focus 6 based on a signal from the position detection circuit 4 when the probe 2 is at the position A.
Is calculated. Then, in response to the high voltage pulse 3 for driving the shaded vibrator group 1b, a signal for setting the output to 0 is sent. This makes the oscillator that actually releases the crushing energy
Only the portion 1a becomes unnecessary, and unnecessary energy reflected by the probe 2 disappears. For this reason, irradiation to other normal tissues can be prevented, and excessive output can be suppressed. Further, if the probe 2 is at the position B, almost no crushing energy can be prevented, so that all the vibrators are driven in the same manner, and calculus can be crushed with the maximum energy.

In this embodiment, the controller performs on / off control, but of course, control of intermediate values of high and low may be performed. The same effect can be obtained even when the position of the ultrasonic probe is other than the center. Further, it is possible not only to stop the output in the shaded portion but also to increase the other output and control the pressure at the focal point to be constant.

FIG. 2 is a circuit diagram showing an embodiment of a pulse drive circuit for driving an ultrasonic transducer.

During normal operation, similarly to the conventional example, while the switching transistor 21 is turned on by a trigger input, through inductance 22, current flows from the DC voltage source V _H,
By turning off the switching transistor 1 instantaneously, a back electromotive force is generated in the inductance 22 and a high voltage pulse is supplied to the vibrator 24.

If the connection cable to the vibrator 24 is broken for any reason, the output will be in a no-load state and the moment the switching transistor 21 is turned off,
An overvoltage is about to occur at the drain terminal. But,
The overvoltage absorbing element 28 instantaneously absorbs the overvoltage, and as a result, the occurrence of the overvoltage that destroys the switching transistor 21 is suppressed. The overvoltage absorbing element 28 is
A minute discharge gap is used, and the interval of the discharge gap is controlled.
Is set within the drain withstand voltage. When the overvoltage absorbing element 28 absorbs the overvoltage by the discharging action, a discharging current flows through the overvoltage absorbing elements 28 and 29 instantaneously. This current is detected by the current detector 29 and latched by the latch circuit 51. By applying this latch signal to the gate 52, the trigger input from the next time onward is prohibited, and the occurrence of overvoltage is suppressed. At the same time, the notification circuit 53 notifies the occurrence of disconnection abnormality in the pulse drive circuit.

In this embodiment, only one switching transistor is shown. However, in order to set a large output voltage, the switching transistors can be connected in series in two or three stages to increase the withstand voltage. In this case, the discharge starting voltage of the overvoltage absorbing element may be set higher by that amount.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, it is safe and reliable because an overvoltage does not occur in the output due to forgetting to attach a connector to the ultrasonic vibrator, disconnection of the cable, or poor contact, and does not destroy the switching transistor in the output stage. A pulse drive circuit can be provided. This method is particularly effective for a circuit that requires a voltage as large as possible, such as a calculus breaking device using ultrasonic waves, and can be used when the output voltage must be set to near the withstand voltage limit of the switching transistor.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a pulse drive circuit of the present invention, and FIGS. 3 to 5 are diagrams showing a conventional example. DESCRIPTION OF SYMBOLS 1 ... Crushing transducer, 2 ... Ultrasonic probe for imaging, 3 ... High-voltage pulser, 4 ... Position detection circuit, 5
... Controller, 6 Focus, 21 Switching transistor, 22 Inductance, 23 Coupling capacitor, 24 Ultrasonic transducer, 25 Damping resistor, 26 Bias circuit, 27 Gate signal, 28 ……
Overvoltage absorption element, 29 …… Current detector.

Claims (4)

(57) [Claims] 1. An ultrasonic pulse drive circuit comprising: a switching transistor; an inductance connected to the ultrasonic vibrator; and means for absorbing an overvoltage connected in parallel with the ultrasonic vibrator. 2. The ultrasonic pulse driving circuit according to claim 1, further comprising means for detecting a current flowing through the means for absorbing the overvoltage and prohibiting a trigger input for driving the switching transistor. 3. The ultrasonic pulse driving circuit according to claim 1, further comprising means for detecting a current flowing through the means for absorbing the overvoltage, and notifying an abnormality. 4. A crushing transducer comprising a plurality of ultrasonic transducers, a plurality of ultrasonic pulse driving circuits for driving the crushing transducer, and an image ultrasonic probe formed inside the crushing transducer. In the ultrasonic calculus crushing apparatus having the ultrasonic pulse driving circuit, a switching transistor, an inductance connected to the ultrasonic vibrator, and a means for absorbing overvoltage connected in parallel with the ultrasonic vibrator, An ultrasonic calculus breaking device characterized by having: