JPH02274240A - Drive circuit for ultrasonic oscillator - Google Patents

Abstract

PURPOSE:To restrain negative pressure and raise only positive pressure even when output is raised by superimposing pulses on the pulses of the positive cycle in the basic frequency of drive pulses applied to an oscillator, and applying negative cycle pulses of a higher frequency than the basic frequency. CONSTITUTION:A trigger pulse signal is inputted from a trigger circuit 16 to a positive pulse generation circuit 17 and a negative pulse generation circuit 18. The pulse of positive polarity from the positive pulse generation circuit 17 is added to the pulse of negative polarity from the negative pulse generation circuit 18 in an adder 19, thereby obtaining a complex drive pulse 14. This complex pulse 14 is applied to an ultrasonic wave oscillator 21 through an application circuit 20. Namely, a high frequency of negative polarity is superimposed on the pulse of positive polarity generating a ultrasonic wave. According to the aforesaid construction, the complex drive pulse 14 adjusts the position (a), width (b) and depth (c) of the negative polarity pulse, thereby enabling obtaining an ultrasonic waveform 15 not generating negative pressure and free from an incidental vibration.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a drive circuit for an ultrasonic transducer, and more specifically, to a drive circuit for an ultrasonic transducer, and more specifically, to a treatment target such as a stone formed in the body. The generated ultrasonic shock waves are focused from outside the body,
The present invention relates to a drive circuit for an ultrasonic transducer in an ultrasonic treatment device for treating stones, tumors, etc.

[Prior Art] Conventionally, an ultrasonic treatment device that generates an ultrasonic shock wave outside the body and focuses it on a stone formed inside the body to destroy the stone is disclosed in Japanese Patent Application Laid-Open No. 145131/1983. , and the patent application No. 62-9497 previously proposed by the applicant.
No. 3, Japanese Patent Application No. 62-67519, etc., are already well known.

In this type of ultrasonic treatment device, an ultrasonic shock wave generator, which is generally formed by arranging a large number of ultrasonic vibrators made of piezoelectric elements in a spherical mosaic pattern, is heated by an ultrasonic propagating liquid such as water. Contact human body surfaces, kidneys, bladder through a filled water bag.

f+I'j is configured to focus ultrasonic shock waves toward stones formed in the gallbladder, bile duct, etc., and crush them. The ultrasonic shock wave is generated by applying a pulsed voltage to an ultrasonic transducer, and the position of the stone is confirmed using an ultrasonic sight 71111 device or the like.

Next, an example thereof will be explained with reference to FIG. 7. This ultrasonic treatment apparatus includes an observation means (position detection means) for detecting the position of a stone in the body, a positioning signal generation means 4, a focal point movement means 7, Shock wave generating means 11 for crushing stone 1 is constructed.

The observation means includes an ultrasonic viewing device 711 + device 2 that emits ultrasonic waves to the human body 10 to detect the location of the stone 1 in the body, and displays the location of the stone based on a detection signal from this device on a screen such as a CRT. (R
has been completed.

The positioning signal generating means 4 provides an indication marker or the like at a target point on the screen of the display device 3, and outputs a control signal to the focus moving means 7 so that the focus of the rock crushing shock wave is placed at the position of the indication marker. do.

The focus moving means 7 moves the water bag 5 and the ultrasonic shock wave generator 6 described below using a numerically controlled robot or the like in accordance with the positioning signal to focus the lithotripsy shock wave on the stone. The shock wave generator 6 has a large number of ultrasonic transducers 8 made of piezoelectric elements arranged and fixed in a mosaic manner on the front surface of a mounting plate 9 formed into a spherical shape, and the front shock wave generation surface is A water bag 5 made of soft resin or the like and having liquid injection and pressure control means is arranged between the ultrasonic shock wave generator 6 and the human body 10. The bag 5 is filled with a shock wave transmission liquid such as water.

As is well known, the shock wave generating means 11 is formed of an ultrasonic transducer drive circuit that generates a pulse voltage and applies the same voltage to the ultrasonic transducers, and each ultrasonic transducer 8 is driven by the circuit to generate ultrasonic waves. is starting to occur.

The above is the entire configuration of the ultrasonic treatment device.

Furthermore, if the affected area to be treated is an Ihrf ulcer or the like, heating treatment is performed by focusing ultrasonic waves.

[Problems to be Solved by the Invention] By the way, in the conventional ultrasonic treatment device of this kind as described above, since the ultrasonic waves are focused to perform treatment, the focus point of the ultrasonic waves is not correct. Negative pressure is generated along with pressure. That is, in the living body located at the focal point of the ultrasound,
So-called cavitation (cavity phenomenon) occurs. When an attempt is made to generate a large output of ultrasonic waves for treatment at a focal point, this cavitation causes the negative pressure to increase as the positive pressure increases, and there is a fear that normal living tissue may be destroyed.

That is, FIGS. 6(A) and 6(B) show the pulse voltage waveform 12 of the single drive pulse applied to the ultrasonic vibrator 8 of the shock wave generating means 11 of the ultrasonic treatment apparatus, and the resulting ultrasonic waves generated. As shown in waveform 13, parasitic vibration of the ultrasonic wave occurs after the applied pulse width T. The negative cycle portion of this parasitic vibration shown by diagonal lines generates negative pressure, which is thought to have an adverse effect on living organisms.

The occurrence of this parasitic vibration varies depending on the resonance sharpness Q of the ultrasonic transducer, but it can be considered that it occurs in most cases. Generally, the larger the Q, the larger the parasitic vibration tends to be.

Therefore, in order to eliminate the above-mentioned conventional drawbacks, the present applicant first proposed a means for suppressing negative pressure by applying drive voltages of different frequencies to the ultrasonic transducer (Japanese Patent Application No.
149037). However, this method has the disadvantage that the device becomes complicated and large.

The purpose of the present invention is to suppress negative pressure, increase only positive pressure, and generate highly focused and powerful ultrasonic shock waves in order to solve the problems with conventional ultrasonic treatment devices as described above. An object of the present invention is to provide a drive circuit for an ultrasonic transducer that is highly safe for living organisms and has high conversion efficiency.

[Means and effects for solving the problem] The ultrasonic transducer drive circuit according to the present invention superimposes the basic frequency pulse on the positive cycle pulse of the fundamental frequency of the driving pulse applied to the ultrasonic transducer. It is characterized in that a negative cycle pulse with a frequency higher than the frequency is applied.

[Example] The present invention will be explained below with reference to illustrated embodiments.

First, before explaining the present invention in detail, the basic principle of the present invention will be explained with reference to FIGS. 1(A) and 2(B) and FIG. 2. FIGS. 1A and 1B show the waveform 14 of the composite drive pulse voltage applied to the ultrasonic transducer by the drive circuit of the present invention, and the waveform 1 of the ultrasonic wave generated as a result.
5, and FIG. 2 shows the basic circuit of the drive circuit of the present invention.

The present invention suppresses the generation of negative pressure that has an adverse effect on living organisms and prevents the generation of the conventional parasitic vibrations described above. To this end, the fundamental frequency ( = resonant frequency), and a negative cycle pulse having a higher frequency than the fundamental frequency is superimposed on the positive cycle pulse. That is, harmonics of negative polarity are superimposed on the pulse of positive polarity that generates ultrasonic waves. In this way, the composite drive pulse 14 shown in FIG. 1(A), which is a specific example, does not produce parasitic vibration by adjusting the width and depth C of the negative polarity pulse. An ultrasonic waveform 15 without generation of negative pressure can be obtained.

As shown in FIG. 2, the W water circuit that generates the composite drive pulse 14 generates the positive pulse by inputting a trigger pulse from the circuit 16 to the positive pulse generating circuit 17 and the negative pulse generating circuit 18. The positive polarity pulse output from the circuit 17 and the negative polarity pulse output from the upper 52 negative pulse generation circuit 18 are added by one adder, thereby generating the composite drive pulse 14 in FIG. 1(A). This is applied to the ultrasonic transducer 21 through the application circuit 20.

FIG. 3 shows an ultrasonic transducer drive circuit according to a first embodiment of the present invention actually constructed based on the above basic circuit,
This is a case where a linear power amplifier circuit is used. That is, the basic pulse generator 2 is connected to the non-inverting input terminal of the first operational amplifier 26.
The positive polarity vibrator driving pulse generated in step 2 is inputted, and the negative polarity pulse generated by the harmonic pulse generator 23 is inputted to the inverting input terminal through the resistor 24. This first operational amplifier 26 connects its output terminal and inverting input terminal to a resistor 25.
The composite driving pulse 14 is output from the output terminal of the adder connected to the adder, and is inputted to the non-inverting input terminal of the second operational amplifier 27. The inverting input terminal of the second operational amplifier 27 is connected to the ultrasonic vibrator 3 made of a piezoelectric element.
0 end, and the output end is NPN type and P
It is connected to each base of NP type output transistors 28 and 29. The emitters of both transistors 28 and 29 are connected to one end of the ultrasonic transducer 30, the collector of one transistor 28 is connected to the positive terminal of the positive power supply 31, and the collector of the other transistor 29 is connected to the positive terminal of the positive power supply 31. connected to the negative terminals of the negative power supplies 32, respectively, and both power supplies 31
．． The negative and positive electrodes of 32 are connected to the other end of the ultrasonic transducer.

In the drive circuit of the first embodiment configured as described above, the ultrasonic transducer 30 is driven by the anti-contact drive pulse whose power is amplified by the transistors 28 and 29, and an ultrasonic output that does not generate parasitic vibration is generated. be able to.

Further, FIGS. 4 and 5 respectively show a second embodiment and a third embodiment of the present invention, in which a composite drive pulse 14 is applied to the ultrasonic transducer 30 by switching drive.
is applied.

That is, the drive circuit of the second embodiment shown in FIG. A composite drive pulse voltage is created by the switch means 33, and this is applied to the output transformer 3.
6 and applied to the ultrasonic transducer 30 on the secondary side.

Further, in the drive circuit of the third embodiment shown in FIG. 5, the basic pulse 22A of positive polarity is applied to the output transformer 36 by the switch means 33, and the positive/negative basic pulse 22A is applied to the secondary side of the transformer 36 via the positive/negative changeover switch means 34,35. The ultrasonic transducer 30 is connected to the transducer. In the third embodiment configured in this way, the output transformer 36 to which the positive basic pulse 22A is applied by the switch means 33
By switching the positive/negative switch means 34 and 35 on the secondary side of the switch and adding the negative polarity pulse 23A to the basic pulse 22A, a composite drive pulse is applied to the ultrasonic transducer 30, and the ultrasonic transducer 30 is free from parasitic vibrations. Generates ultrasonic output that does not cause

[Effects of the Invention] As explained above, according to the present invention, even if the output is increased to increase treatment efficiency, negative pressure is suppressed and only positive pressure can be increased, so cavitation at the focal point can be prevented from occurring. To provide an ultrasonic transducer drive circuit for an ultrasonic treatment device, which has no fear of destroying normal tissues in a living body, ensures safety to the living body, has high conversion efficiency, and can perform treatment efficiently. I can do it.

[Brief explanation of drawings]

FIGS. 1(A) and 1(B) are a waveform diagram of a composite drive pulse applied to an ultrasonic transducer and a waveform diagram of an ultrasonic wave generated by the ultrasonic transducer, which illustrate the basic principle of the present invention. FIG. 2 is a basic circuit diagram of an ultrasonic transducer drive circuit of the present invention, FIG. 3 is a drive circuit diagram of an ultrasonic transducer showing the first embodiment of the present invention, and FIGS. 4 and 5 are , a drive circuit diagram of an ultrasonic transducer showing the second and third embodiments of the present invention, respectively. FIG. 7 is a waveform diagram of the ultrasonic waves generated by the transducer. FIG. 7 is a schematic diagram showing the overall configuration of the ultrasonic wave treatment device.

Claims (1)

[Claims] (1) In an ultrasonic treatment device that focuses ultrasonic waves generated outside the body by an ultrasonic shock wave generator having an ultrasonic transducer toward a treatment site inside the body, the ultrasonic shock waves are applied to the ultrasonic transducer. 1. A drive circuit for an ultrasonic transducer, characterized in that a negative cycle pulse having a frequency higher than the fundamental frequency is applied superimposed on a positive cycle pulse having a fundamental frequency of the driving pulse.