JPH02290281A - Apparatus for driving ultrasonic converter - Google Patents

Abstract

PURPOSE:To efficiently drive an ultrasonic converter by mounting a means controlling a matching means on the basis of the output of an impedance detection means to change the output impedance of a drive circuit. CONSTITUTION:A switch 51 is turned ON not only to drive a vibrator 21 by the low constant current set on the basis of the reference voltage V0 of a current value setting circuit 44 but also to start a generator 49 to subject the vibrator 21 to frequency scanning on the basis of the reference sweep signal due to a VCO 50. The vibrator 21 is driven by the constant current even during scanning by the current value setting circuit 44, a differential amplifier 42 and a VCA 24. When a current value is preset to ¦I0¦, impedance ¦Z¦ can be detected. When the vibrator 21 is subjected to frequency scanning, the impedance ¦Z¦ becomes min. at a resonance point fr and voltage ¦V¦ also becomes min. and it can be detected whether an ultrasonic converter is connected.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an ultrasonic transducer driving device.

[Conventional technology]

Various devices using ultrasonic transducers have been proposed in the past, such as surgical ultrasonic scalpels, ultrasonic processing devices, and the like. In such an ultrasonic device,
When driving an ultrasonic transducer, it is desirable in terms of drive efficiency to match the impedance between the drive circuit and the ultrasonic transducer.

For example, as shown in FIGS. 9A and 9B, when using the ultrasonic transducer 1 with oscillating rods 2 and 3 having different lengths fastened to their tips, according to the inventor's experiments, FIG. The impedance of is approximately 175 of the impedance of FIG. 9A. Therefore, when driving these with the same drive circuit, if the output impedance of the drive circuit is matched to one of the oscillation rods 2 or 3, when the other oscillation rod 3 or 2 is connected and used. Impedance matching cannot be achieved, and drive efficiency deteriorates significantly.

As a solution to such problems, for example, Japanese Patent Application Laid-open No. 6
3-162086, impedance is reduced by switching the secondary side tap (on the transducer circuit side) of a coupling transformer that electrically couples the transducer and the drive circuit based on the vibration amplitude of the ultrasonic transducer. A system has been proposed that is adapted to respond to changes in

Problem to be solved by the invention C] However, in the ultrasonic device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 63-162086, the criterion for switching the matching depends on the amplitude of the ultrasonic transducer. Therefore, there is a problem that impedance matching is broken. In other words, since the amplitude of the vibrator is proportional to the current flowing into it, the impedance of the vibrator circuit is 2.
If the current value is doubled, in this conventional example, in order to equalize the current value, the secondary side tap of the coupling transformer is switched to double the step-up ratio, and twice the voltage is applied to the ultrasonic transducer. . However, in this case, the impedance of the resonator circuit as seen from the primary side of the coupling transformer is 174 times higher because the winding ratio of the coupling transformer is 1:2, so the impedance of the resonator circuit is doubled. Also, the impedance of the load on the drive circuit side is 172. As a result, impedance matching is disrupted, making it impossible to drive the ultrasonic transducer efficiently.

In addition, in the above conventional example, the taps are switched on the secondary side of the coupling transformer, that is, on the transducer circuit side, so when applied to a medical ultrasonic device such as an ultrasonic scalpel, for example, When a switching circuit or a control circuit is inserted into a so-called patient circuit, there is a problem in that it is necessary to consider insulation in terms of electrical safety such as withstand voltage and leakage current.

Another method is to measure the impedance of the ultrasonic transducer to be driven in advance, and manually perform impedance matching when driving, but in this case, the matching may be incorrect due to incorrect operation. There is a problem in that the drive circuit may be overloaded and the drive circuit may fail.

This invention was made by focusing on these conventional problems, and it is possible to automatically optimize the impedance matching between the ultrasonic transducer and its drive circuit, thereby ensuring that the ultrasonic transducer is always efficient. It is an object of the present invention to provide an ultrasonic transducer drive device suitably configured to drive well.

[Means and operations for solving the problem] In order to achieve the above object, the present invention provides the following steps to optimize the matching between the drive circuit and the ultrasonic transducer serving as its load.
a matching means for changing the output impedance of the drive circuit; a means for detecting the impedance of the ultrasonic transducer; and a matching means for detecting the impedance of the ultrasonic transducer; and means for controlling the matching means to change the output impedance of the drive circuit.

That is, in this invention, as the basic configuration is shown in FIG. 1, the output of the drive circuit 11 is supplied to the ultrasonic transducer 13 via the matching transformer 12 as variable matching means. The matching transformer 12 is provided with taps 14-1 and 14-2 on its primary side for switching the number of turns of the primary winding, and an impedance detection rail 15 for detecting the impedance of the ultrasonic transducer 13. is connected, and based on the impedance of the ultrasonic transducer 13 detected by this impedance detection circuit 15, the optimum driving conditions for the ultrasonic transducer 13 are set via a setting circuit 16 and a relay 17 that constitute a control means. The output impedance of the drive circuit 11 is changed by switching the taps 14-1 and 14-2 to match the ultrasonic transducer 13.

With this configuration, impedance matching between the ultrasonic transducer 13 and its drive circuit 11 can be automatically optimized, and the ultrasonic transducer 13 can be driven efficiently at all times.

〔Example] FIG. 2 is a block diagram showing an embodiment of the present invention.

In this embodiment, the voltage phase and current phase of the drive signal of the ultrasonic transducer having the ultrasonic transducer 21 are detected, and the resonance point tracking circuit 2
2, tracking control (PLL control) is performed so that the drive signal frequency becomes the resonance frequency.

The output of the resonance point tracking circuit 22 is supplied to a sine wave filter 23 and converted into a sine wave drive signal, and then passed through a voltage control amplifier (VCA) 24 whose amplification factor can be changed and a power amplifier 25 for matching. It is supplied to the primary side of the transformer 26.

The matching transformer 26 includes two primary windings 27-1 and 27-2 that can be connected in series and parallel, and one secondary winding 28. −
2 are connected in series and parallel by a relay 29, and an ultrasonic transducer 21 is connected to the secondary winding 28.
A correction inductor 30 for canceling the braking capacity of the vibrator 21 is connected in parallel thereto. In this embodiment, the winding ratio of the winding 27-1.272.28 is i:t:
2, the winding ratios of the secondary side and the secondary side are switched between 1=1 and 1:2.

The voltage applied to the vibrator 21 via the power amplifier 25 is detected by a voltage divider of a resistor group 31 connected in parallel to the primary side of the matching transformer 26, and its output is supplied to a differential amplifier 32 to remove common mode noise. do it like this.

Furthermore, the current flowing through the vibrator 21 is detected by a current sensor 33 connected in series to the primary side of the matching transformer 26.
The output is supplied to a differential amplifier 34 to remove common mode noise.

The voltage detection signal obtained from the differential amplifier 32 is supplied to a comparator 35 and an absolute value detection circuit 36, respectively,
The comparator 35 detects the voltage phase signal θ9, and the absolute value detection circuit 36 detects the absolute value IVI of the voltage detection signal. Similarly, the current detection signal obtained from the differential amplifier 34 is supplied to a comparator 37 and an absolute value detection circuit 38, respectively. to be detected.

The voltage phase signal θ obtained from the converter 35 is supplied to the resonance point tracking circuit 22, and is also sent to the resonance point detection circuit 39 in order to sweep the drive signal frequency of the vibrator 21 and detect the resonance point, as will be described later. The current phase signal θ1 obtained from the converter 37 is supplied to the resonance point detection circuit 39 and also to the resonance point tracking circuit 22 via the switch 40.

Further, the absolute value IVI of the voltage detection signal obtained from the paired value detection circuit 36 is supplied to one input terminal of the voltage comparator 41, and the absolute value III of the current detection signal obtained from the absolute value detection circuit 3 is a differential It is supplied to one input terminal of amplifier 42.

A predetermined set voltage ■ is applied to the other manual terminal of the voltage comparator 41.
2 is supplied and compared with the absolute value IVI of the voltage detection signal, and the output is latched by the relay control circuit 43 to control the relay 29. Further, a setting signal from a current value setting circuit 44 is supplied to the other input terminal of the differential amplifier 42, and the difference between the current detection signal and the absolute value Ml is detected, and based on the output, the difference is zero. By controlling the amplification factor of the VCA 24 so that the oscillator 21 is always driven with a constant current corresponding to the setting signal. Note that the output of the resonance point detection circuit 39 is supplied to the control circuit 45.

The current value setting circuit 44 includes a reference voltage ■ for setting a low constant current at startup. , a variable resistor 46 for setting a constant current that drives the vibrator 21 with a predetermined amplitude in the resonance point tracking operation, and the variable resistor 46. a switch 47 for selecting the voltage of the oscillator 46; and a switch 4 for zeroing the control voltage of the VCA 24 to stop the vibration of the vibrator 21.
8.

On the other hand, in order to sweep the drive signal frequency of the vibrator 21, a generator 49 generates a sawtooth voltage signal.
is provided, and its output is supplied to a voltage controlled oscillator (VCO) 50 to generate a reference sweep signal whose frequency changes, which is then supplied to the resonance point tracking circuit 22 via the switch 40.

In addition, switch 40, relay control circuit 43, switch 4
7.4B, the operation of the generator 49 and other parts is controlled by a control circuit 45, and the control circuit 45 is provided with a switch 51 for starting and stopping the apparatus.

The operation of this embodiment will be explained below with reference to the flowchart shown in FIG.

When the switch 51 is in the OFF state, the switch 40 is at vC0.
50, the switch 47 is ON and the switch 48 is OFF, and the matching transformer 26 has a relay 29 so that the winding ratio between the primary side and the secondary side thereof is 1:1.

In this state, the switch 51 is turned ON, and first the vibrator 21 is driven with a low constant current set by the reference voltage v0 of the current value setting circuit 44, and the generator 49 is started to
Transducer 2l based on reference sweep signal by CO 50
to perform a frequency scan. In other words, the resonance point tracking circuit 2
2 to the output of VCO 50, vco so
By scanning the output frequency of the generator 49 using the output of the generator 49, the PLL oscillation frequency is scanned.

Here, since the vibrator 21 is driven with a constant current by the current value setting circuit 44, the differential amplifier 42, and the VCA 24 even during scanning, the current value can be determined as II0]. This impedance +21 becomes the minimum at the resonance point f when the vibrator 21 is frequency scanned, so IV
I also reaches its minimum at the resonance point f, as shown in FIGS. 4A and 4B correspondingly to the 1-characteristics in the ultrasonic transducer shown in FIGS. 9A and 9B. Therefore, if IVI is compared with the set voltage V2 in the comparator 41, when the comparator 4l operates during scanning, an ultrasonic transducer with a small +Zl is connected, and when the comparator 4l does not operate, an ultrasonic transducer with a large IZI is connected. It is detected that an ultrasound transducer is connected.

When it is detected that an ultrasonic transducer with a small impedance IZ1 is connected, next turn the switch 48 to OFF.
N, the control voltage of the VCA 24 is set to zero, the output of the power amplifier 25 is stopped, and in this state, the relay 29 is operated based on the above impedance detection result latched in the relay control circuit 43, thereby achieving matching. By switching the winding ratio of the transformer 26 to 1=2, the output impedance on the drive circuit side is changed to match the impedance of the connected ultrasonic transducer. After that, switch 48 is turned OFF, generator 49 is restarted, and VCO 5
While frequency scanning the vibrator 2 based on the reference sweep signal of 0, the resonance point detection circuit 39 detects the resonance point where the phase difference between them is zero based on the voltage phase signal θ and the current phase signal θ1. .

After the resonance point is detected, the Suinochi 40
is connected to the comparator 37 to lock the resonance point tracking operation, and when locked in, the switch 47 is turned off to drive the vibrator 21 with the current value set by the variable resistor 46, that is, with the set amplitude.

Note that if it is detected that an ultrasonic transducer with a large impedance IZ1 is connected and the winding ratio of the matching transformer 26 can remain at 1:1, the resonance point detection circuit 39 detects the resonance point during the scan. is detected, so after the resonance point is detected without rescanning, the switch 40 is connected to the comparator 37 and a lock-in operation is started.

As described above, according to this embodiment, the magnitude of the dynamic impedance of the vibrator 2l is detected, the matching is automatically optimized, and driving can be started. In addition, even if the transducer 21 is the same in an ultrasonic scalpel or an ultrasonic processing machine, but the shape of the probe connected to the tip is different, and the impedance changes significantly, matching is automatically optimized. This allows the ultrasonic transducer to be driven efficiently at all times. In addition, matching is optimized by switching the taps on the secondary side of the matching transformer 26, so when applied to medical ultrasound equipment such as ultrasound scalpels, a switching circuit or control circuit is installed in the so-called patient circuit. There is no need to insert a circuit, and therefore it is extremely effective in terms of electrical safety such as withstand voltage and leakage current.

FIG. 5 is a block diagram showing the configuration of an example of an ultrasonic scalpel device equipped with an ultrasonic transducer driving device according to the present invention.

In this embodiment, a hand bead 55 is used in which a short probe 57 and a long probe 58 having different lengths, that is, different impedances, are selectively coupled to the same Lange-Evan type vibrator 56. The oscillator 56 is the 2nd part of the munching transformer 59.
It is connected to the next side and driven based on the output of the PLL 60.

The matching transformer 59 has two primary windings 61-1.
and 6l-2, and one secondary winding 62, and has a relay and its control circuit, etc. whose primary and secondary winding ratios are similar to those shown in FIG. 63 to switch. Note that a correction inductor 64 for canceling the braking capacity of the vibrator 56 is connected in parallel with the vibrator 56.

The PLL 60 includes a phase comparator (CPC) 65, a charge pump 66 that converts its digital output into an analog signal, a loop filter 67, and a voltage controlled oscillator (VC
O) 68, and the output of the charge pump 66 is supplied to the VCO 68 as a control voltage via a loop filter 67. The output of the VC0 68 is supplied to a filter 69, and is also frequency-divided by a frequency dividing circuit 70 and sent to the filter 69, thereby converting the rectangular wave drive signal output from the VCO 69 into the resonant frequency component of the vibrator 56. The drive signal is converted into a sine wave drive signal to prevent wasteful heat generation within the vibrator 56.

In this example, a switched capacitor filter (SCF) whose cutoff frequency can be changed by inputting an external clock is used as the filter 69. In this way, if an SCF is used as the filter 69, even if the oscillation frequency of the vCO 68 changes, the magnitude and phase rotation of the filter output waveform will not fluctuate, and as a result, constant current control and P
The influence on the LL operation is reduced, making it possible to perform ideal rectangular wave to sine wave conversion, and when scanning the drive signal frequency of the vibrator 56 and detecting its impedance, only the fundamental wave component is used. can be used to accurately determine it.

The output of the filter 69 is supplied to the primary side of the matching transformer 59 via a voltage control amplifier circuit (VCA) 71 whose amplification factor can be changed, a buffer amplifier 72, a switch circuit 73, and a power amplifier 74. In this way, the matching transformer 59 separates the circuit system of the vibrator 56 and its drive circuit system for electrical isolation, and also provides electrical insulation between the power amplifier 74 and the vibrator 56 serving as a load, as will be described later. Try to match.

The voltage applied to the vibrator 56 via the power amplifier 74 and the current flowing to the vibrator 56 are detected by voltage/current detection having a voltage detection resistor group and a current sensor similar to those shown in FIG. 2 on the primary side of the matching transformer 59. circuit 7
5 and supplies these voltage detection signals and current detection signals to differential amplifiers 76 and 77, respectively. In this way, the voltage detected by the voltage/current detection circuit 75. By supplying current to differential amplifiers 76 and 77 to obtain voltage detection signals and current detection signals, high voltage and
It can effectively solve the problem of common mode noise when detecting a large current at a low voltage, and even if the positive and negative connections of the output of the power amplifier 74 are reversed, it is not an output type in which one of the outputs is grounded. Even if the voltage and current signals are present, each voltage and current signal can be detected stably.

The voltage detection signal obtained from the differential amplifier 76 is sent to the comparator 7
8 and the absolute value detection circuit 79, and the voltage phase signal θ, is supplied to the comparator 78 and the absolute value detection circuit 79.
The absolute value IVI of the voltage detection signal is detected at . Similarly, the current detection signal obtained from the differential amplifier 77 is supplied to a comparator 80 and an absolute value detection circuit 81, respectively. The value IN is detected.

The voltage phase signal θ, obtained from the comparator 78 is supplied to the phase detector 82 and also to the PC 6 configuring the PLL 60.
The current phase signal θ1 obtained from the comparator 80 is supplied to the phase detector 82 and is also supplied to the reference input terminal R of the PC 65 via the switch circuit 83. Further, the absolute value ■1 of the voltage detection signal obtained from the absolute value detection circuit 79 is determined by the voltage comparator 8.
4 and compares it with a predetermined set value, and its output is supplied to a phase detector 82.

In this way, in the phase detector 82, the voltage comparator 8
4, the voltage phase signal θ9 from the comparator 78, and the current phase signal θ from the comparator 80.
6 is approximately equal to the resonant frequency of the vibrator 56, and based on the output, a current phase signal θ1 in the switch circuit 83 and a reference signal θ from an oscillator to be described later are detected. ．． ．． ．． In addition to controlling the switching operation with f, the lighting of the light emitting diode 85 is controlled to display whether or not the PLL 60 has shifted to the resonance point tracking operation.

Further, the absolute value IVI of the voltage detection signal obtained from the absolute value detection circuit 79 is also supplied to a voltage comparator 86 for detecting the impedance I71 and compared with a predetermined set value,
Based on the output, lighting of the light emitting diodes 87 and 88 for short probes and long probes is controlled, and matching switching operation in the select circuit 63 is controlled. Here, a predetermined setting value in the voltage comparator 86 is set to a boundary value that allows the short probe 57 and the long probe 58 to be distinguished.

The phase detector 82 includes, for example, three D as shown in FIG.
-Flip-flop (D-FF) 89. 90 and 9l, and an OR gate 92, and a comparator 78
The voltage phase signal θ9 obtained from the comparator 80 is supplied to the D terminal of the D-FF 89,
1 is supplied to the clock input terminal of the D-FF89. The Q output and Q output of this DFF89 are respectively supplied to the clock input terminal of D-FF90 and the clock input terminal of D-FF91, and the Q outputs of these D-FF90 and 9l are supplied to the OR gate 92 and the switch circuit and a control signal for the light emitting diode 85.

Note that the D input terminals of D-FF90 and 9l are connected to VC.
Apply C. Further, the voltage comparator 84 is configured with an op-amp, and supplies the absolute value IVI of the voltage detection signal obtained from the absolute value detection circuit 79 to its inverting input terminal, and applies a set voltage vse to its non-inverting input terminal. , and supplies its output to the clear terminals of D-FF 90 and 9l.

Note that the output of the OR gate 92 is supplied to the control circuit 93, and the output from the control circuit 93 is DI'F.
A reset signal is supplied to the clear terminal of 89.

In FIG. 5, the absolute value III of the current detection signal obtained from the absolute value detection circuit 81 is supplied to the inverting input terminal of the differential amplifier circuit 94. A setting signal from a current value setting circuit 95 is supplied to the non-inverting input terminal of the differential amplifier circuit 94, and based on the output thereof, the vibrator 56 is always driven with a constant current corresponding to the setting signal. , the amplification factor of the VCA 71 is controlled via the limiter circuit 96. The current value setting circuit 95 includes a variable resistor 97 for setting the output amplitude.
and a variable resistor 98 for setting low constant current drive, which are selected based on a signal from the control circuit 93, and the variable resistor 98 for setting low constant current drive is selected at the time of startup.
In the resonance point tracking operation, the output of the output amplitude setting variable resistor 97 is supplied to the differential amplifier circuit 94. In this way, the absolute value [1 of the current detection signal obtained from the absolute value detection circuit 81 and the setting signal from the current value setting circuit 95 are compared in the differential amplifier circuit 94, and the output of the VCA 71 is determined based on the output thereof. By controlling the signal voltage input to the buffer amplifier 72 and the power amplifier 74 by controlling the amplification factor 11, the vibrator 56 is always controlled by the current value setting circuit 95 even when the impedance changes due to load fluctuations of the hand piece 55. The handpiece 55 can be driven with a constant current corresponding to a setting signal from the handpiece 55, and the amplitude of the handpiece 55 can be made constant.

A trigger output circuit 99 is connected to the control circuit 93 so that a trigger signal is generated under the control of the control circuit 93. This trigger signal is supplied to a generator 100 to generate a sawtooth wave, which is supplied to an oscillator 101, which outputs a reference signal θ7. , to occur. This reference signal θrsr is supplied to the R input terminal of the PC 65 constituting the PLL 60 via the switch circuit 83 under the control of the phase detector 82 as described above. Further, the trigger signal from the trigger output circuit 99 is supplied to the counter 102 for counting, and when the count value exceeds a set value, the switch circuit 73 is turned OFF and the hand piece 55 is detected to be abnormal and is used for probe checking. The light emitting diode 103 is turned on. Note that this counter 102 is reset by a reset signal from the control circuit 93.

On the other hand, the output of the loop filter 67 constituting the PLL 60 is also supplied to a low pass filter (LPF) 104 to remove spike-like noise contained in the control voltage of the VC0 68. The output of the LPF104 is supplied to the window converter 105, which monitors the output frequency range of the VCO 68 and outputs a reset signal to the control circuit 93 when it is out of a predetermined range. That is, the oscillation frequency of ν0068 changes depending on the control voltage from the loop filter 67, but when the PLL 60 is removed from the resonance point tracking control of the vibrator 56, the oscillation frequency of ν0068 is saturated at its highest or lowest oscillation frequency. .

Therefore, in order to detect this unlock state, VC0
The control voltage of 68 is monitored by the window comparator 105. Here, the control voltage supplied to VC0 68 is:
The signal is smoothed to some extent by the loop filter 67, but if, for example, an edge trigger type PC 65 is used in the PLL 60 and the loop characteristics are made to be high-speed to some extent by designing the loop filter 67, the VC
Spiked noise leaks into the control voltage supplied to the O68 at the edge comparison portion of the two input signals of the PC65. Since this spike-like noise adversely affects the operation of the window converter 105, in this example, the LPF 104 is inserted as described above to remove the spike-like noise.

The control circuit 93 also includes an ON/OFF state for the vibrator 56.
A footswitch 106 for controlling OFF is connected, and the operation of each of the above parts is controlled based on the signal from this footswitch 106, the signal from the phase detector 82 mentioned above, and the slope signal from the window converter 105. At the same time, the operation of the suction unit 107 for removing the tissue excised by the ultrasonic scalpel, cooling the probe of the hand piece 55, and the water supply unit 108 for washing away the excised site is controlled.

The operation of this ultrasonic scalpel device will be explained below.

When the foot switch 106 is in the OFF state, the switch circuit 73 is OFF, and the switch circuit 83 is connected to supply the output of the oscillator 101 to the R input terminal of the PC 65 of the PLL 60.

When the foot switch 106 is turned on, the control circuit 93 obtains a start signal, resets the phase detector 82 and the counter 102, and selects the low constant current drive setting variable resistor 98 of the current value setting circuit 95. and its output is supplied to the differential amplifier circuit 94. Further, the switch circuit 73 is turned on, and the trigger output circuit 99 is activated to generate a trigger signal from the trigger output circuit 99. As a result, the reference signal θra whose frequency changes according to the output of the generator 100 is transmitted from the oscillator lot to the PLL 60 via the switch circuit 83.
r is supplied, so that the PLL 60 changes the drive signal frequency of the vibrator 56 to a reference signal θ.r. ．． ．． Scan to lock on f.

Here, since the vibrator 56 is driven and controlled with a low constant current set by the variable resistor 98 of the current value setting circuit 95,
The voltage applied to the vibrator 56 is proportional to its impedance, and therefore the voltage applied to the vibrator 56 changes by scanning in a manner similar to the frequency characteristic of its impedance.

This change in drive voltage is detected by the voltage comparator 8 via the voltage/current detection circuit 75, differential amplifier 76, and absolute value detection circuit 79.
4 and 86, and in the first scan,
Based on the comparison result with a predetermined setting value in the voltage comparator 86, the selection circuit 63 selects the Manning transformer 59.
The connection of the primary winding is switched, thereby changing the output impedance on the drive circuit side to a value corresponding to the probe coupled to the handpiece 55, and eliminating munching with the handpiece 55. The light emitting diode 87 or 88 corresponding to the probe lights up.

In addition, in the second scan, the voltage detection signal IVI from the voltage comparator 84 is lower than the set voltage V SET (see FIG. 6), that is, the frequency of the reference signal θrar is near the resonance frequency of the hand bead 55, and the impedance is set. An enable signal is output to the phase detector 82 when the value becomes equal to or less than the value. In the phase detector 82, when the enable signal is output from the voltage comparator 84 and the phase difference between the voltage phase signal θV from the comparator 78 and the current phase signal θ1 from the comparator 80 becomes zero, The output becomes H level and is held, thereby switching the switch circuit 83 and supplying the current phase signal θ from the comparator 80 to the R input terminal of the PC 65, and the light emitting diode 85 lights up to reach the resonance point. A message indicating that the tracking operation has started is displayed. At the same time, a current value setting circuit 95 is passed through a control circuit 93 based on the output of the phase detector 82.
The output amplitude setting variable resistor 97 is selected, and its output is supplied to the differential amplifier circuit 94. Therefore, from now on, the hand bead 55 will be driven and controlled with a predetermined current set by the variable resistor 97 so that the phases of the voltage phase signal θ9 and the current phase signal θ always match. In addition, by shifting to the resonance point tracking operation, the control circuit 93 connects the suction unit l-107 and the water supply unit 1.
A drive signal is supplied to 08 to perform each operation. The above operation is canceled by turning off the foot switch 106. Note that this operation of shifting to resonance point tracking is performed even when the output impedance is not switched by the select circuit 63 in the first scan.

Here, when the resonance point is not detected by the second scan, the oscillation frequency of VC0 6B is locked to the reference signal θrat from the oscillator 101 and rises or falls, and the oscillation frequency of the VC0 6B rises or falls, and the oscillation frequency of the VC0 6B rises or falls outside the predetermined frequency range in the window converter 105. When this is detected, a recent signal is output to the control circuit 93. As a result, a signal is sent from the control circuit 93 to the trigger output circuit 99 to output a trigger again, and the above resonance point detection operation is repeated. The number of times the trigger signal is output from the trigger output circuit 99, that is, the number of times the drive signal frequency is scanned, is counted by a counter 102, and when it reaches a predetermined value, the switch 106 is turned on, for example, once.
If the drive signal frequency cannot be locked into the resonance frequency even after scanning the drive signal frequency 10 times, it is assumed that the resonance point of the hand bead 55 does not exist within the predetermined frequency range, and at that point the switch circuit 73 is activated by the output of the counter 102.
is turned off and the drive of the vibrator 56 is stopped, and
The light emitting diode 103 lights up to indicate an abnormality in the hand bead 55. Thereby, it is possible to effectively prevent the danger caused by the handpiece 55 continuing to be driven in an abnormal state.

According to the above-mentioned ultrasonic scalpel device, since the connected probe is automatically determined and the corresponding matching is made appropriate, the hand bead 55 can be driven efficiently at all times.

In addition, it is possible to reliably shift to the resonance point tracking operation, and even if the tracking operation is unlocked, it can be restarted, and it is also possible to detect abnormalities in the handpiece 55. Furthermore, by combining a general constant current drive circuit, constant amplitude operation can be performed and the frequency characteristics of impedance can be detected in a simple manner, allowing accurate and reliable detection of resonance points. be able to. Furthermore, since the voltage applied to the vibrator 56 and the current flowing through the vibrator 56 are detected differentially, common mode noise can be effectively removed, and the desired voltage can be detected regardless of the output format of the power amplifier 74. This allows the circuitry around the power amplifier that generates high voltage to be lifted from ground, and the leakage current to ground in the transducer circuit, that is, the patient circuit, can be significantly reduced. can.

What? In the above ultrasonic scalpel device, the vibrator 56
Although the voltage applied to the oscillator and the current flowing through the vibrator are detected on the primary side of the matching transformer 59, they can also be detected on the secondary side of the matching transformer 59. Further, the amplitude set by the output amplitude setting variable resistor 97 of the current value setting circuit 95 is determined by a maximum value setting circuit 110 that sets the maximum value and minimum value of the amplitude of the short probe 57, respectively, as shown in FIG. and a minimum value setting circuit 111, and a maximum value setting circuit 112 and a minimum value setting circuit 113 that respectively set the maximum value and minimum value of the amplitude of the long probe 5B.
It is also possible to set these by connecting them to the variable resistor 97 and switching them by the relay 114 based on the output of the voltage comparator 86 that calculates the impedance. In this way, the probe 57.
Even if the resistance of 58 is different, it can be easily accommodated.

Furthermore, in the above ultrasonic scalpel device, the impedance of two types of probes 57 and 58 is determined and the output impedance on the drive circuit side is changed, but it is not possible to change the output impedance of the drive circuit side for three or more types of probes. It is also possible to optimize the matching by determining the output impedance of the drive circuit and changing the output impedance of the drive circuit accordingly. In this case, for example, as shown in FIG. Two or more relays 117-1. 117-2 to its relay contact 1
181.118-2 may be selectively switched.

In addition, in order to protect the relay contact that switches the primary winding of the matching transformer 59, in addition to reducing the output to the vibrator 56 to zero at the time of switching as explained in FIG. CI? A spark killer consisting of a circuit or the like may be inserted between the contacts. Furthermore, in addition to determining the probe and matching the impedance, it is also possible to change the driving frequency and set the water supply amount, etc., depending on the probe.

Furthermore, the present invention is not limited to ultrasonic scalpel devices, but can be effectively applied to drive circuits for ultrasonic transducers used in ultrasonic processing devices and other ultrasonic devices.

[Effects of the Invention] As described above, according to the present invention, there is provided a matching means for changing the output impedance of a drive circuit to normalize matching with an ultrasonic transducer serving as a load, and an impedance of the ultrasonic transducer. and the matching means is controlled so that the output impedance of the drive circuit becomes the optimum driving condition for the ultrasonic transducer based on the output of the impedance detection means. Impedance matching between the ultrasonic transducer and its drive circuit can be automatically optimized, and the ultrasonic transducer can be driven efficiently at all times.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of this invention, FIG. 2 is a block diagram showing an embodiment of this invention, and FIGS. 3 and 4A.
, B is a flowchart explaining its operation and a diagram showing the frequency characteristics of the driving voltage, and FIG. 5 is a block diagram showing the configuration of an example of an ultrasonic scalpel device equipped with an ultrasonic transducer driving device according to the present invention. , FIG. 6 is a diagram showing the configuration of an example of the phase detector shown in FIG. 5, FIG. 7 is a diagram showing a modification of the current value setting circuit, and FIG. 8 is a diagram showing a matching transformer and its switching means. FIGS. 9A and 9B are diagrams illustrating a conventional technique. Fig. 1 1l - Drive circuit l2 - Matching transformer 13 - Ultrasonic transducer 14-1.14-2 - Tap 15-
-Impedance detection circuit 16-・Setting circuit 17・-Relay 1111-
τ-11” Figure 8 Figure 9

Claims (1)

[Claims] 1. In order to optimize the matching between the drive circuit and the ultrasonic transducer serving as its load, a matching means for changing the output impedance of the drive circuit, a means for detecting the impedance of the ultrasonic transducer; and means for controlling the matching means to change the output impedance of the driving circuit so as to provide optimum driving conditions for the ultrasonic transducer based on the output of the impedance detecting means. Transducer drive device.