JP3486469B2 - Drive device for piezoelectric vibrator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for driving a piezoelectric vibrator such as a Langevin type ultrasonic piezoelectric vibrator used in an ultrasonic treatment apparatus for surgery.

[0002]

2. Description of the Related Art A general Langevin type ultrasonic transducer 1
Are configured as shown in FIG. That is, a structure in which a piezo element (piezoelectric element) 2 and an electrode 3 are alternately superposed on each other to form a laminated body, and the laminated body is sandwiched between a vibration amplification horn 4 and a backing block 5 and tightened with a bolt 6 is used. Has become. A cable 7 for supplying a driving voltage is connected to each electrode 3. FIG. 8 shows the configuration of the drive circuit of the ultrasonic transducer 1 by electrical symbols. The ultrasonic transducer 1 indicated by the electric symbol is connected to the driving oscillation source 8 also indicated by the electric symbol.

By the way, this type of ultrasonic transducer 1 is
There is a physically determined resonance frequency fr, and when a drive signal corresponding to this resonance frequency fr is given, it has the property of vibrating most efficiently. An equivalent circuit near the resonance frequency fr is as shown in FIG. That is, in the series resonance circuit represented by the resonance component by the coil component (L) and the capacitor component (C), which are the characteristics of mechanical vibration, and the resistance component (R) representing the mechanical load, the piezo element 2 and the electrode 3 are connected. The braking capacitor component (Cd) composed of is connected in parallel. Only the current flowing in the series resonant circuit is converted into ultrasonic vibration. Therefore, driving at the resonance point of the series resonance circuit results in the most efficient vibration.

From the above, the condition for vibrating the ultrasonic vibrator 1 most efficiently is the frequency at which the coil component (L) and the capacitor component (C) in the figure resonate, that is, fr = 1.
This is to give a voltage of / (2π√ (LC)). The equivalent circuit under this condition is as shown in FIG. The current flowing through the resistance component (R) in FIG. 9B is converted into vibration energy.

However, the coil component (L) and the capacitor component (C) slightly change depending on load conditions applied to the tip of the ultrasonic vibrator 1, environmental conditions such as temperature, and changes with time. For this reason, when the load applied to the ultrasonic transducer 1 is likely to vary depending on the usage state, such as with an ultrasonic scalpel or an ultrasonic welding machine, for example, in the ultrasonic scalpel, a hard tissue, a soft tissue, or a fine treatment is performed. From a large amount of emulsified suction from
When the load condition is not constant, somehow
It is necessary to give a controlled drive voltage by following the fluctuations of L and C, that is, the fluctuations of the resonance frequency fr.

In order to realize this, paying attention to the phase relationship between the voltage applied to the ultrasonic piezoelectric vibrator and the current flowing at that time, the method of feeding back the current signal to oscillate, and the position of each phase signal A method of performing PLL (Phase Lock Loop) control by the phase difference is known. Figure 10
FIG. 10A shows a principle diagram of a PLL control system in which the oscillation source 8 is track-driven by a PLL control circuit 9.
(B) shows the admittance characteristic in the vicinity of the resonance frequency of the piezoelectric vibrator 1. In the figure, fr is the resonance frequency point. In the method shown in FIG. 10, the capacitor component (Cd)
Since the current component icd flowing through causes a phase shift, it operates at a frequency of fr ', which leads to a reduction in vibration efficiency. That is, the current icd becomes a reactive current that is not converted into vibration.

In order to solve this problem, FIG. 11 (A)
As shown in FIG. 2, a method of adding a coil Ld in parallel to the piezoelectric vibrator 1 has been proposed (Japanese Patent Laid-Open No. 2-2656).
81 gazette). According to this, the capacitor component (C
By setting the value of the inductive component of the coil Ld so that the current component icd flowing in d) is canceled by the current iLd flowing in the previous coil Ld, it becomes possible to operate at the frequency of fr. The admittance characteristics at that time are shown in FIG.
It is shown in (B).

Here, the value (Ld) of the inductive component of the inductor coil to be added is fr = 1 / (2π√ (Ld · C
It should be set so as to satisfy d)). That is, the physical capacitor component (Cd) of the piezoelectric vibrator and the additional coil component (Ld) cause parallel resonance at the frequency fr to cancel the current icd component, which has been a problem in the past. . As a result, it becomes possible to supply the drive voltage of the resonance frequency fr that gives the most efficient vibration to the ultrasonic transducer.

[0009]

However, it has been known that the above-mentioned method has the following points to be improved. By following the combination of the matching coil and the PLL control circuit 9, the resonance frequency follow-up drive can be realized.
Since the coil component (Ld) is determined by the braking capacitor component (Cd) or the resonance frequency fr, if it is desired to use piezoelectric vibrators having different shapes and sizes, or if the same vibrator is used at different frequencies. If it is desired to operate with fr ″, it is necessary to prepare a number of different Ld values in accordance with the operation.

The present invention has been made in view of the above problems, and an object thereof is to always reliably drive a piezoelectric vibrator at its resonance point and easily cope with diversifying operations and the like. Another object of the present invention is to provide a piezoelectric vibrator driving device that can be used.

[0011]

According to the present invention, there is provided a piezoelectric vibrator for vibrating a piezoelectric element, an oscillation source for applying a high frequency drive voltage to the piezoelectric vibrator, and a piezoelectric vibrator connected in parallel to the piezoelectric vibrator. A correction capacitor for correcting the phase component flowing through the first and second current detecting means for detecting the current value of the first current flowing through the piezoelectric vibrator, and the current value of the second current flowing through the correction capacitor. Second current detecting means for detecting, comparing means for comparing the current values respectively detected by the first and second current detecting means, a current value of the detected first current and the second current value. The first calculation means whose gain is controlled based on the output of the comparison means so that the current values of the currents are equal, and the first current and the second current which are equalized based on the first calculation means. Second performance to synthesize the phases of And means, based on said second operation means is a piezoelectric vibrator of the driving device and a control means for controlling the oscillation frequency of the high frequency drive voltage outputted from the oscillation source.

[0012]

According to the piezoelectric vibrator driving device having the above-described structure, the currents respectively flowing in the correction capacitors provided in parallel with the piezoelectric vibrator are adjusted to the same value by the gain adjustment by comparison, and the phase combination of these is performed. The oscillation frequency is controlled so that the high-frequency drive voltage applied to the piezoelectric vibrator from the piezoelectric vibrator is driven at the resonance point of the piezoelectric vibrator.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultrasonic treatment apparatus for surgery using a piezoelectric vibrator drive device according to an embodiment of the present invention will be described with reference to FIGS. The surgical handpiece 10 used in this ultrasonic therapy apparatus is configured as shown in FIG. The surgical handpiece 10 has a built-in ultrasonic transducer 11. Further, a cord (cable) 12 for supplying an ultrasonic wave drive signal to the ultrasonic transducer 11, a suction tube 13 for sucking the crushed tissue, and a water supply tube 14 for supplying a liquid are connected to the handpiece 10. There is. The cord 12, the suction tube 13, and the water supply tube 14 each have a connector group 15 as a relay connection unit that is detachably coupled to each other at an intermediate portion thereof. Then, these are the cleaning section 16 located on the handpiece 10 side and the unclean section 17 (12 ', set on the apparatus main body 21 side, which will be described later), with the relay section as a boundary.
13 ', 14'). Here, both the separable clean portion 16 and the unclean portion 17 are respectively coupled by individual connectors, but as shown in FIG. 3, the cord and the connecting portion of the tubes are connected by an integrated connector means 18. You can also use it.

The surgical handpiece 10 is attached to the apparatus main body 2
The state of being connected to 1 is shown in FIG. In addition to a drive power source, which will be described later, a water supply device, a suction device, and the like are incorporated in the device body 21. 22 is a reservoir bottle of physiological saline supplied by the water supply device, and 23 is a waste liquid tank for receiving the waste liquid sucked by the suction device. An operation panel 24 is provided on the front surface of the apparatus body 21. A caster 25 is provided on the apparatus main body 21 so that it can be moved.

According to the above construction, the handpiece 10 and the tubes 12, 13, 1 are prepared for the preparation for surgery.
The clean section 16 of 4 is sterilized in advance in a state of being integrally set at the surgical site, while the apparatus main body 21 side has separately sterilized tubes 12 'of the unclean section 17. 13 'and 14' are set in the connector or pump of the apparatus main body 21. Then, when used, a simple operation of connecting the relay section by the connector group 15 or the connector means 18 by simply connecting the both is performed.
Therefore, setup is possible in a short time.

Next, the ultrasonic transducer 11 of the surgical handpiece 10 will be described. As shown in FIG. 4 and FIG. 5, this is a piezoelectric vibrator called Langevin type, and is a laminated body in which a plurality of piezo elements (piezoelectric elements) 31 and electrodes 32 are alternately stacked in order to form a laminated body. Is sandwiched between the vibration amplifying horn 33 and the backing block 34 and tightened with the bolt 35. A flexible wiring member 36 that communicates with the cord 12 for supplying a driving voltage is connected to each electrode 32. The flexible wiring member 36 is, for example, a printed circuit board having a structure in which a copper foil or the like is bonded to an extremely thin insulating film of polyimide having a thickness of 40 μm to 120 μm.
The cord 12 and the electrode 32 are connected to each other, and a drive voltage having an ultrasonic frequency is supplied from the cord 12 to the electrode 32. Code 12
The electrical connection between the electrode 32 and the flexible wiring member 36 may be, for example, soldering.

When there are a plurality of electrodes 32, the connection positions of the respective flexible wiring members 36 to the respective electrodes 32 are displaced in the circumferential direction as shown in FIG. It can be compactly arranged without doing.

By the way, the vibration of the piezoelectric element 31 group whose thickness changes in the thickness direction upon receiving the voltage of the ultrasonic frequency is expanded by the horn 33 to the target amplitude (about 300 μmp · p at maximum). To be done. During this vibration,
Since the electrode 32 vibrates in the thickness direction of the piezoelectric element 31,
The electrode 32 also simply vibrates at the ultrasonic frequency in the thickness direction of the vibrator 11. On the other hand, since the cord 12 is installed in a state where the elasticity is small, it is conceivable that if the cord 12 receives the vibration, it cannot be absorbed and the connecting portion thereof is damaged or peeled off. However, here, there is an extremely thin flexible wiring member 36 having a thickness of 40 μm to 120 μm between them, and since this flexible wiring member 36 has a small mass and is flexible, the vibration of the electrode 32 is attenuated while receiving the vibration. -Absorbs and prevents a failure such as breakage or peeling at a soldered portion with the cord 12 or the electrode 32.
Therefore, the electrical connection strength between the cord 12 or the electrode 32 and the flexible wiring member 36 is secured, and soldering or the like is sufficient as the connecting means. Further, since the flexible wiring member 36 is thin, the outer diameter of the portion of the handpiece 10 can be reduced, which leads to downsizing of the handpiece 10.

On the other hand, the oscillator drive circuit of the ultrasonic therapy apparatus is constructed as shown in FIG. The ultrasonic transducer 11 has a resonance frequency fr that is physically determined, and when a drive signal corresponding to this resonance frequency fr is applied, it vibrates most efficiently. The equivalent circuit under these conditions is a circuit in which a resistor R and a capacitor Cd are arranged in parallel, as is known from the above. In the equivalent circuit of the ultrasonic transducer 11, a correction capacitor Cc is connected in parallel with an oscillation source 40 that generates an ultrasonic signal. Reference numeral 41 is a first sensor (detection means) that detects a drive current to the ultrasonic transducer 11, and 42 is a second sensor (detection means) that detects a current flowing through the capacitor Cc. Oscillator 40
The oscillation frequency is adjusted by a PLL (phase lock loop) control circuit 43. PLL control circuit 43
Controls the oscillation frequency of the oscillation source 40 according to the phase difference between the voltage applied to the ultrasonic transducer 11 detected by the voltage sensor 44 and the current flowing at that time. Reference numeral 45 is a comparison circuit for comparing the magnitude of the current value I ₁ of the ultrasonic transducer 11 and the magnitude of the current value I ₂ of the correction capacitor Cc, and 46 is a variable gain amplifier circuit, which are provided for each sensor 4
The first calculating means adjusts at least one of the detected currents so that the magnitudes of the current values detected by the detecting means 1, 42 are equal. Reference numeral 47 is an arithmetic circuit for synthesizing the phases of the current values detected by the detecting means of the sensors 41 and 42, and constitutes a second arithmetic means.

In this structure, first, the oscillation source 40 is
A frequency voltage different from the resonance frequency of the ultrasonic transducer 11 is generated. At this time, since the portion corresponding to the resistance R of the ultrasonic transducer 11 is outside the series resonance circuit of the coil component L and the capacitor component C in FIG. 9A described above, the value of the resistance R is ideally. Grows infinitely. Therefore, at the above frequency, the current detected by the first sensor 41 becomes equal to the current iCd flowing through the capacitor Cd. further,
The second sensor 42 detects the current iCc flowing through the correction capacitor Cc. Each of these currents iCd, iCc
Have the same phase, and their magnitude is C
It is inversely proportional to the values of d and Cc.

The magnitudes of the current iCd and the current iCc are compared by the comparison circuit 45, and by the combination, iCd = k · iCc
The calculation processing for setting the variable gain amplifier circuit 46 so that If the capacitors Cd and Cc have the same value, k = 1 is sufficient. The result of the phase combination of this signal, that is, the calculation of the vector difference of iCd−k · iCc becomes the ir component, so the phase component θI
Then, using the voltage phase component θV from the voltage sensor 44, the PLL control circuit 43 performs the PLL control so that the phase difference becomes zero, whereby the resonance point drive becomes possible.
This state is shown in the admittance characteristic diagram of FIG.

According to the above, even if the type of the ultrasonic transducer 11 changes and the value of the capacitor component Cd changes, the value of the capacitor component Cd can be canceled by simply changing the gain k. It is not necessary to prepare the conventional coil Ld according to the type of the ultrasonic transducer 11, and therefore the expandability is excellent.

FIG. 1C is a modified example of the above-described embodiment, and the ultrasonic oscillator 11 and the drive circuit 51 side separated by the transformer 52 also have the above-mentioned configuration. It can be applied. In this case, assuming that the winding ratio of the transformer 52 is n, the value of the gain k may be set so that 1 / n · I ₁ = k · I ₂ . <Appendix> (1) Piezoelectric vibrator, an oscillation source for applying a high frequency drive voltage to the piezoelectric vibrator, a correction capacitor connected in parallel to the piezoelectric vibrator, and a current detecting unit for detecting a current flowing in the piezoelectric vibrator. 1 detecting means, 2nd detecting means for detecting the current flowing through the correction capacitor, and 1st adjusting at least one of the detected currents so that the magnitude of the current value detected by each detecting means becomes equal. A second means for synthesizing the phases of the respective current signals detected by the calculating means and the detecting means.
And a control circuit for controlling the oscillation source so as to drive the piezoelectric vibrator at a resonance point by using the output of the second calculating means. . (2) Piezoelectric vibrator, oscillation source for applying high frequency drive voltage to the piezoelectric vibrator, correction capacitor connected in parallel to the piezoelectric vibrator, and first detection for detecting current flowing in the piezoelectric vibrator Means, second detecting means for detecting the current flowing through the correction capacitor, and first calculating means for adjusting at least one of the detected currents so that the magnitudes of the current values detected by the respective detecting means are equal. A second phase combining the respective current signals detected by the respective detecting means
And a control circuit for performing PLL control to drive the piezoelectric vibrator at the resonance point by using the phase difference between the output of the second calculation means and the voltage of the oscillation source. Piezoelectric vibrator drive device. (3) The piezoelectric vibrator driving device according to item 1, wherein the piezoelectric vibrator is resonantly driven by positively feeding back the output of the second arithmetic means to the oscillation source. (4) The piezoelectric vibrator driving device according to any one of items 1, 2, and 3, wherein the arithmetic means is a variable gain amplifier circuit. (5) The piezoelectric vibrator drive device according to any one of items 1, 2, and 3, wherein the second arithmetic means is a differential amplifier circuit.

(6) In the ultrasonic operation system, a handpiece for performing ultrasonic operation, an apparatus main body, a cable for supplying an electric signal to a piezoelectric vibrator in the handpiece, the handpiece and an operation part. And a suction tube for sucking and removing the crushed tissue treated by the handpiece. These cables and tubes are set on the device body side and the handpiece side. It has a means to relay and connect them. According to this, the tubes on the handpiece side can be set in the handpiece in the clean area, and the tubes can also be set in advance in the main body side in the unclean area. Then, at any time, the tubes can be joined at the relay portion. Generally, in a surgical operation, an operator, an operating table, a patient, and a surgical instrument are in an area called a clean area, and it is necessary to keep a sterile condition. On the other hand, the device main body and the area around it are called the dirty area, and it is necessary to clearly distinguish them from the clean area before, but without connecting the operation of connecting various cables and tubes to the clean area during surgery, make it easier.

(7) A handpiece, a piezoelectric vibrator provided in the handpiece, a code for supplying an ultrasonic wave drive signal to the piezoelectric vibrator, an electrode of the piezoelectric vibrator, and the code are flexible. It was connected via a wiring member.
According to this, the ultrasonic drive signal supplied from the cord is transmitted to the flexible wiring member. The flexible wiring material supplies an ultrasonic wave drive signal to the piezoelectric vibrator. At this time, since the piezoelectric vibrator vibrates ultrasonically, the electrodes also vibrate at the same time, and therefore, the vibration is also transmitted to the flexible wiring material, but the vibration is absorbed and attenuated there and is not transmitted to the cord. In addition, it is important to design the ultrasonic scalpel handpiece compact because it is easier to handle and smaller in size, and can withstand long-term use. However, the space between the electrode and the tube connecting portion becomes an obstacle to reducing the diameter of the handpiece. Furthermore, although the handpiece is used repeatedly, the electrode vibrates in the radial direction along with the vibration of the piezo element, and the copper wire with less elasticity is soldered to it, which may cause long-term use. There is a problem that the soldered copper wire may break or the solder may peel off. The item of the sixth item solves the above problems and can easily cope with diversifying operations.

[0026]

As described above, according to the present invention, the piezoelectric vibrator can always be reliably driven at its resonance point, and it is possible to easily cope with diversifying operations. Further, it is possible to flexibly cope with, for example, surgical operations that are diversified and sophisticated, and it is possible to easily cope with version upgrades.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a piezoelectric vibrator driving device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a surgical handpiece according to an embodiment of the present invention.

FIG. 3 is a perspective view of a modified example of the surgical handpiece according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a configuration of a piezoelectric vibrator according to an embodiment of the invention.

FIG. 5 is a plan view of the same piezoelectric vibrator.

FIG. 6 is a perspective view showing a state where the surgical handpiece is connected to the apparatus main body.

FIG. 7 is a structural explanatory view of a general Langevin type ultrasonic transducer.

FIG. 8 is a circuit diagram of an electrical configuration of the general Langevin type ultrasonic transducer.

FIG. 9 is an equivalent circuit diagram of the Langevin type ultrasonic transducer.

FIG. 10 is a principle diagram of a PLL control system.

FIG. 11 is a principle diagram of another PLL control method.

[Explanation of symbols]

10 ... Surgery handpiece, 11 ... Ultrasonic transducer, 12
... cord (cable), 13 ... suction tube, 14 ... water supply tube, 15 ... connector group, 16 ... clean section, 17 ...
Filthy part, 18 ... Connector means, 21 ... Device body, 31 ...
Piezoelectric element (piezoelectric element), 32 ... Electrode, 33 ... Vibration amplification horn, 34 ... Lining block, 36 ... Flexible wiring member, R ... Resistor, Cd ... Capacitor, Cc ... Correction capacitor, 40 ... Oscillation source, 41 ... 1st sensor (detection means), 42 ... 2nd sensor (detection means), 43 ... PL
L (phase lock loop) control circuit, 44 ... Voltage sensor, 45 ... Comparison circuit, 46 ... Amplifier circuit, 47 ... Operation circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B06B 1/06 A61B 18/00 H04R 3/00

Claims (2)

(57) [Claims] 1. A piezoelectric vibrator, an oscillation source for applying a high-frequency drive voltage to the piezoelectric vibrator, a correction capacitor connected in parallel to the piezoelectric vibrator and correcting a phase component flowing in the piezoelectric element, First current detecting means for detecting a current value of a first current flowing through the piezoelectric vibrator; second current detecting means for detecting a current value of a second current flowing through the correction capacitor; And comparing means for comparing the current values detected by the second current detecting means, and the comparing means so that the detected current value of the first current and the detected current value of the second current are equal. A first calculation means whose gain is controlled based on the output of the second calculation means, a second calculation means for combining the phases of the first current and the second current which are equalized based on the first calculation means, Based on the second computing means, The piezoelectric vibrator driving apparatus characterized by comprising control means for controlling the oscillation frequency of the serial oscillation source. 2. An oscillation source for supplying a drive voltage for driving a piezoelectric resonator to a resonance point, and a first detection for detecting a first current branched from a current path of the drive voltage and flowing through the piezoelectric vibrator. Means and second detecting means for detecting a second current flowing through the correction capacitor for correcting the phase component of the first current flowing through the piezoelectric vibrator by branching from the current path of the drive voltage. , The first current and the second current are adjusted to the same current value, and the phase of the drive voltage is corrected by using a phase component obtained by calculating a vector difference between these adjusted current values. A drive device for a piezoelectric vibrator, comprising: a control unit that drives a child at a resonance point.