JP3756726B2 - Ultrasonic transducer drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic transducer driving device, and more particularly to an ultrasonic transducer driving device characterized by a control portion for driving to follow the resonance frequency of the ultrasonic transducer.
[0002]
[Prior art]
In general, it is desirable to drive an ultrasonic transducer used in an ultrasonic scalpel for surgical operation, an ultrasonic processing apparatus, or the like at or near its fundamental resonance frequency. Further, when the resonance frequency of the ultrasonic transducer is no longer present due to load conditions, temperature, damage to the transducer, etc., it is necessary to prohibit driving the ultrasonic transducer and to warn the operator.
[0003]
Therefore, as shown in, for example, Japanese Patent Laid-Open No. 7-313937, a PLL (phase control) configured with an analog circuit that controls the drive frequency of the vibrator to coincide with the resonance frequency in an ultrasonic vibrator drive device. (Loop) method of vibrator driving and a method of confirming whether or not the driving frequency is within a predetermined range, and stopping the drive in the case of an abnormality and notifying the abnormality are disclosed.
[0004]
However, the PLL system configured with an analog circuit requires a plurality of transmission sources in order to drive a vibrator having a plurality of types of resonance frequencies, and is configured with an analog circuit. There have been problems such as changes in characteristics and the need to adjust the circuit with a variable resistor or the like.
[0005]
Therefore, in recent years, resonance frequency tracking has been performed with a PLL system (hereinafter referred to as a digital PLL) configured by a digital circuit using a DDS (direct digital synthesizer) and an UP / DOWN counter to solve the above problem. Yes.
[0006]
FIG. 6 is a block diagram of a feedback circuit in the digital PLL 92 in the conventional ultrasonic coagulation / cutting device 91. The detection circuit 101 detects the voltage and current of the ultrasonic output signal, and the phase signal θv ( Voltage phase signal) and θI (current phase signal) are input to the phase comparator 102.
[0007]
The phase comparator 102 detects the phase difference between the voltage phase signal and the current phase signal, and outputs a control signal (hereinafter referred to as a phase difference +/− signal) for raising and lowering the output frequency, and the UP / DOWN counter 103 receives the control signal. Input a control signal.
[0008]
The UP / DOWN counter 103 outputs an actually output frequency (hereinafter referred to as a drive frequency setting signal) based on the initial setting frequency signal from the CPU 104 and the phase difference +/− signal from the phase comparator 102.
[0009]
The DDS 105 actually outputs a sine wave based on the drive frequency setting signal. This sine wave is transmitted to the vibrator 109 in the handpiece 108 via the power amplifier 106 and the detection circuit 101, and the tip of the handpiece 108 performs ultrasonic vibration to make a coagulation incision of the tissue.
[0010]
Further, the monitoring circuit 110 monitors the drive frequency setting signal, checks whether the difference from the initial setting frequency signal is within a predetermined range, and if it is outside the predetermined range, the PLL unlock signal Is transmitted to the CPU 104, and the driving of the ultrasonic coagulation / cutting device 91 is stopped.
[0011]
FIG. 7 shows an equivalent circuit of a general vibrator and an inductor Lb of the output circuit of the ultrasonic coagulation / cutting device 1. An equivalent circuit of the vibrator is represented by a series circuit of Ca, La, and R and a parallel circuit of Cb. Usually, the oscillation circuit includes a matching coil Lb for canceling the braking capacity component of the vibrator.
[0012]
FIG. 8 shows the electrical characteristics of the equivalent circuit of FIG. The vertical axis represents impedance Z and phase θ, and the horizontal axis represents frequency.
[0013]
In FIG. 8, F1 is a first anti-resonance frequency, Fr is a resonance frequency, and F2 is a second anti-resonance frequency.
[0014]
Usually, when the vibrator is ultrasonically driven, PLL driving is performed so that the driving frequency is tracked to the resonance frequency Fr.
[0015]
In addition, when the resonance frequency Fr no longer exists due to the abnormality of the vibrator, the drive frequency deviates from a predetermined range (PLL lockable range). Conventionally, this has been monitored and the driving of the ultrasonic coagulation / cutting device 91 has been stopped.
[0016]
[Problems to be solved by the invention]
However, in the driving of such an ultrasonic transducer, the current phase signal cannot be detected in a situation where the impedance Z generated for a moment becomes high, and the driving frequency changes instantaneously, and is out of a predetermined range. Therefore, there is a problem that the CPU 104 is recognized as abnormal and the apparatus stops.
[0017]
In other words, it is known that when the tissue is grasped by the handpiece 108, the impedance Z and phase θ characteristics have high impedance and the change becomes dull as shown in FIG.
[0018]
Conventionally, in the UP / DOWN counter 103, since the drive frequency setting signal is raised and lowered at a ratio of 1: 1 with respect to the output from the phase comparator 102, the state in which the impedance Z is high and the change is slow is instantaneous. However, if it occurs, the current phase signal cannot be detected as described above, so that there is a problem that the resonance frequency cannot be tracked, the drive frequency is changed outside a predetermined displacement, the abnormality is recognized, and the apparatus is stopped.
[0019]
The present invention has been made in view of the above circumstances, and even in a situation where the impedance Z increases even for a moment, the drive signal is reliably tracked to the resonance frequency, and the ultrasonic transducer is damaged. An object of the present invention is to provide an ultrasonic transducer driving apparatus that can recognize an abnormality and stop the apparatus when an abnormality occurs due to the above.
[0020]
[Means for Solving the Problems]
The first ultrasonic transducer driving apparatus of the present invention includes an ultrasonic transducer drive signal generating means for generating a drive signal for driving the ultrasonic transducer in accordance with a drive frequency setting signal, and the ultrasonic transducer Phase signal detection means for detecting the voltage phase signal and current phase signal of the drive signal supplied to the ultrasonic transducer from the drive signal generation means, and the voltage phase signal and current detected by the phase signal detection means A phase difference magnitude detecting means for detecting the magnitude of the phase difference between the voltage phase and the current phase of the drive signal based on the phase signal in accordance with a predetermined clock; and a predetermined value detected by the phase difference magnitude detecting means. Phase difference data storage means for storing the phase difference data related to the magnitude of the phase difference according to the clock for the past predetermined number of times, and the phase difference data for the past predetermined number of times stored in the phase difference data storage means Based on the average value and a predetermined initialization frequency signals, the ultrasonic transducer generates a frequency variable data for the frequency control by the PLL drive, on the basis of the frequency variable data, the drive frequency setting signal Driving frequency setting signal generating means for generating and PLL driving the ultrasonic transducer, and detecting a difference between the driving frequency setting signal output from the driving frequency setting signal generating means and a predetermined initial setting frequency signal, And a monitoring unit that outputs a signal for canceling the PLL driving by the driving frequency setting signal generating unit when the difference reaches a predetermined range.
[0021]
The second ultrasonic transducer driving apparatus of the present invention includes an ultrasonic transducer drive signal generating means for generating a drive signal for driving the ultrasonic transducer in accordance with a drive frequency setting signal, and the ultrasonic transducer Phase signal detection means for detecting the voltage phase signal and current phase signal of the drive signal supplied to the ultrasonic transducer from the drive signal generation means, and the voltage phase signal and current detected by the phase signal detection means A phase difference signal frequency dividing means for performing a predetermined frequency dividing process on the phase difference signal with respect to the phase signal, the phase difference signal subjected to the frequency dividing process in the phase difference signal frequency dividing means, and a predetermined initial setting frequency signal; based on the ultrasonic transducer to generate a frequency variable data for the frequency control by the PLL drive, on the basis of the frequency variable data, the ultrasonic transducer to generate the drive frequency setting signal The difference between the drive frequency setting signal generating means for LL driving and the drive frequency setting signal output from the drive frequency setting signal generating means and a predetermined initial set frequency signal is detected, and the difference reaches outside the predetermined range. The monitoring means for outputting a signal for releasing the PLL drive by the drive frequency setting signal generating means, and at the time of the PLL drive and when the PLL drive is released based on the detection result of the monitor means Phase difference frequency ratio changing means for changing the frequency division ratio in the phase difference frequency means.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0023]
1 to 3 relate to the first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of the ultrasonic surgical apparatus, FIG. 2 is a block diagram showing the configuration of the ultrasonic coagulation / cutting apparatus of FIG. FIG. 3 is an explanatory diagram for explaining the operation of the frequency change setting circuit of FIG.
[0024]
As shown in FIG. 1, the ultrasonic surgical apparatus according to the present embodiment provides ultrasonic output from the ultrasonic coagulation / cutting apparatus 1 that performs ultrasonic output, the handpiece 2 that performs treatment, and the ultrasonic coagulation / cutting apparatus 1. And a foot switch 3 to be controlled.
[0025]
As shown in FIG. 2, the handpiece 2 is provided with a vibrator 4, and the vibrator 4 is amplified by a power amplifier 12 having a driving frequency based on the output of the digital PLL 11 of the ultrasonic coagulation / cutting device 1. The drive signal is driven through the detection circuit 13.
[0026]
The detection circuit 13 detects the voltage and current supplied to the vibrator 4 and generates phase signals θv (voltage phase signal) and θI (current phase signal).
[0027]
The digital PLL 11 detects the direction (+/−) and the magnitude of the phase difference between θv and θI and generates a phase difference +/− signal, a phase comparator 21, a frequency change setting circuit 22, UP / A DOWN counter 23 and a DDS (Direct Digital Synthesizer) 24 are included.
[0028]
The frequency change setting circuit 22 is configured by a DSP (digital signal processor), and receives the phase difference +/− signal output from the phase comparator 21 as an enable signal and counts the clock to thereby determine the magnitude of the phase difference. The phase difference signal magnitude detection unit 22a to detect, the first to third data storage units 22b, 22c, and 22d that store the past three results of the phase difference signal magnitude detection unit 113a, and the first to third data It comprises a change value calculation unit 22e that calculates the change value of the startup frequency by averaging the values of the storage units 22b, 22c, and 22d and outputs a pulse signal (UP / DOWN count signal) according to the calculation result.
[0029]
The UP / DOWN counter 23 detects the edge of the output (UP / DOWN count signal) from the frequency change setting circuit 22 based on the initial set frequency signal transmitted from the CPU 25, and for one pulse of the UP / DOWN count signal. Then, the drive frequency setting signal is generated by changing the drive frequency by a predetermined frequency change.
[0030]
The DDS 24 outputs a sine waveform corresponding to the drive frequency setting signal.
[0031]
That is, the digital PLL 11 generates an UP / DOWN count signal for changing the drive frequency setting signal in the frequency change setting circuit 22 based on the output of the phase comparator 21, and passes through the UP / DOWN counter 23. Control is performed so that the drive frequency output from the DDS 24 tracks the resonance frequency.
[0032]
In addition, the monitoring circuit 26 monitors whether or not the difference between the drive frequency signal applied to the vibrator 4 and the initial setting frequency signal is within a predetermined range, and the difference is outside the predetermined range. Then, a PLL non-lock signal is transmitted to the CPU 25.
[0033]
FIG. 3 shows the operation in the frequency change setting circuit 22 in the digital PLL 11 of the present embodiment.
[0034]
As described above, the frequency change setting circuit 22 is configured by a DSP, and receives a clock, an initial setting frequency signal from the CPU 25, and a phase difference +/− signal from the phase comparator 21.
[0035]
The phase difference magnitude detection unit 13a in the frequency change setting circuit 22 inputs the phase difference − (+) signal shown in FIG. 3B as an enable, and counts the clock shown in FIG. Thus, the magnitude of the phase difference-signal is detected (the count result is Cn shown in FIG. 3B).
[0036]
The detected data Cn is stored in the first data storage unit 22b, and the data (Cn-1, Cn-2) stored in the first and second data storage units 22b, 22c until then is stored in the second and second data storage units 22b, 22c, respectively. The third data storage units 22c and 22d are stocked.
[0037]
The change value calculation unit 22e averages the three phase difference magnitude detection unit results (Cn, Cn-1, Cn-2) that are stored in the circuit, and generates a pulse signal for the average. As a result, an output UP (DOWN) count signal is obtained.
[0038]
UP (DOWN) count signal = (Cn + Cn-1 + Cn-2) / 3
Cn: The clock count number UP / DOWN counter 23 while the phase difference +/− signal is “L” is based on the initial setting frequency signal transmitted from the CPU 25, and with respect to one pulse of the above UP / DOWN count signal. The drive frequency setting signal is changed by a predetermined change (FIG. 3C).
[0039]
Based on the above, the DDS 24 performs frequency tracking by changing the frequency of the output sine waveform.
[0040]
By taking the average with the past data in the above calculation, a large frequency change of the drive frequency that causes a non-PLL lock does not occur due to an instantaneous impedance change.
[0041]
In addition, when a high impedance state has always occurred due to breakage of the vibrator 4 or the like, a non-PLL lock state is established.
[0042]
In other words, when using an ultrasonic transducer, when driving near the resonance frequency, even if the instantaneous impedance Z is high, the frequency does not change instantaneously and the ultrasonic transducer is damaged. An ultrasonic coagulation / cutting device appropriately configured to recognize an abnormality and to stop the apparatus in the event of an abnormality due to, for example, can be realized.
[0043]
FIG. 4 is a block diagram showing a configuration of an ultrasonic coagulation / cutting device according to the second embodiment of the present invention.
[0044]
Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0045]
As shown in FIG. 4, in the second embodiment, a PLL lock / unlock signal that is an output of the monitoring circuit 26 is added to the input of the frequency change setting circuit 22.
[0046]
Then, during the resonance frequency tracking (at the time of PLL locking) and at the time of non-tracking (at the time of non-PLL locking), the number of data that takes the average value in the change value calculation unit 22e is changed.
[0047]
When the PLL is locked, the change value of the drive frequency is calculated by taking the average of the three data (Cn, Cn-1, Cn-2) of the first to third data storage units 22b-22d.
[0048]
However, when the PLL is not locked, the data Cn of the first data storage unit 22b is used as the change value of the drive frequency setting signal as it is.
[0049]
Thereby, at the time of PLL lock, even if a state with a high instantaneous impedance occurs, the PLL lock is stable. On the other hand, at the time of non-PLL lock, a faster frequency change can be caused, and the abnormal state can be detected immediately by the CPU 25.
[0050]
FIG. 5 is a block diagram showing a configuration of an ultrasonic coagulation / cutting device according to the third embodiment of the present invention.
[0051]
Since the third embodiment is almost the same as the first embodiment, only different points will be described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0052]
In the first and second embodiments, the phase difference +/− signal is enabled, the clock is counted, an operation using the DSP is performed, and the number of UP / DOWN count signal pulses of the operation result is UP / DOWN. The frequency tracking control is performed by outputting to the counter. In this embodiment, as shown in FIG. 5, the counter 31 is used instead of the frequency change setting circuit 22, and the phase difference +/− signal is divided. Then, an UP / DOWN count signal is generated.
[0053]
In the case of the present embodiment, as in the first and second embodiments, the magnitude of the phase difference +/− signal is not reflected in the UP / DOWN count signal (the result is obtained regardless of whether the phase difference is large or small). However, by dividing the phase difference +/− signal, the number of pulses of the UP / DOWN count signal with respect to the phase difference +/− signal pulse number can be reduced. For this reason, even when noise occurs in θv and θI, the influence on the change in the driving frequency can be reduced.
[0054]
Further, by changing the frequency dividing ratio from 4 frequency division to 2 frequency division according to the PLL locked / non-locked state, when the PLL is locked, the UP / DOWN count signal is set to 1 with respect to the number of 4 pulses of the phase difference +/− signal. When the pulse or PLL is not locked, one UP / DOWN count signal is output for the number of phase difference +/- 2 pulses.
[0055]
Then, the UP / DOWN counter 23 changes the drive frequency setting signal by 1 Hz with respect to one pulse of the UP / DOWN count signal. Thereby, the effect equivalent to 1st and 2nd embodiment can be acquired cheaply.
[0056]
In addition, the response of the entire internal circuit of the ultrasonic coagulation / cutting device 1 is delayed, which is useful for preventing oscillation of the entire circuit.
[0057]
【The invention's effect】
As described above, according to the present invention, even when the impedance Z increases momentarily, the drive signal is reliably tracked to the resonance frequency, and an abnormality is recognized in the event of an abnormality due to damage to the ultrasonic transducer. There is an effect that can be stopped.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an ultrasonic surgical apparatus according to a first embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of an ultrasonic coagulation / cutting apparatus of FIG. Explanatory drawing explaining the effect | action of a frequency change setting circuit [FIG. 4] The block diagram which shows the structure of the ultrasonic coagulation incision apparatus based on the 2nd Embodiment of this invention [FIG. 5] 3rd Embodiment of this invention FIG. 6 is a block diagram showing the configuration of a conventional ultrasonic coagulation / cutting device. FIG. 7 shows an equivalent circuit of a general load (vibrator) and an output circuit. 8 is a first characteristic diagram showing the characteristics of the equivalent circuit of FIG. 7. FIG. 9 is a second characteristic chart showing the characteristics of the equivalent circuit of FIG.
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic coagulation incision apparatus 2 ... Handpiece 3 ... Foot switch 11 ... Digital type PLL
DESCRIPTION OF SYMBOLS 12 ... Power amplifier 13 ... Detection circuit 21 ... Phase comparator 22 ... Frequency change setting circuit 22a ... Phase difference signal magnitude detection part 22b ... 1st data storage part 22c ... 2nd data storage part 22d ... 3rd data storage part 22e ... Change value calculation unit 23 ... UP / DOWN counter 24 ... DDS
25 ... CPU
26. Monitoring circuit

Claims (2)

An ultrasonic transducer drive signal generating means for generating a drive signal for driving the ultrasonic transducer in accordance with the drive frequency setting signal;
Phase signal detection means for detecting a voltage phase signal and a current phase signal of the drive signal supplied to the ultrasonic vibrator from the ultrasonic vibrator drive signal generation means ;
Phase difference magnitude detection for detecting the magnitude of the phase difference between the voltage phase and the current phase of the drive signal in accordance with a predetermined clock based on the voltage phase signal and the current phase signal detected by the phase signal detection means. Means,
Phase difference data storage means for storing the phase difference data relating to the magnitude of the phase difference according to a predetermined clock detected by the phase difference magnitude detection means for the past predetermined number of times;
A frequency for performing frequency control by PLL driving of the ultrasonic transducer based on an average value of the phase difference data for a predetermined number of times stored in the phase difference data storage means and a predetermined initial setting frequency signal generates variable data, and the frequency variable data on the basis of, the drive frequency setting signal generating means for generating the drive frequency setting signal to PLL drives the ultrasonic vibrator,
A difference between the drive frequency setting signal output from the drive frequency setting signal generation means and a predetermined initial setting frequency signal is detected, and when the difference reaches outside a predetermined range, the drive frequency setting signal generation means Monitoring means for outputting a signal for releasing the PLL drive by
An ultrasonic transducer driving device comprising: An ultrasonic transducer drive signal generating means for generating a drive signal for driving the ultrasonic transducer in accordance with the drive frequency setting signal;
Phase signal detection means for detecting a voltage phase signal and a current phase signal of the drive signal supplied to the ultrasonic vibrator from the ultrasonic vibrator drive signal generation means ;
Phase difference signal frequency dividing means for performing a predetermined frequency division process on the phase difference signal between the voltage phase signal and the current phase signal detected by the phase signal detecting means;
Based on the phase difference signal subjected to frequency division processing by the phase difference signal frequency dividing means and a predetermined initial setting frequency signal , frequency variable data for performing frequency control by PLL driving of the ultrasonic transducer is obtained. generated, and the frequency variable data on the basis of, the drive frequency setting signal generating means for generating the drive frequency setting signal to PLL drives the ultrasonic vibrator,
A difference between the drive frequency setting signal output from the drive frequency setting signal generation means and a predetermined initial setting frequency signal is detected, and when the difference reaches outside a predetermined range, the drive frequency setting signal generation means Monitoring means for outputting a signal for releasing the PLL drive by
Based on the detection result of the monitoring means, a phase difference frequency ratio changing means for changing a frequency dividing ratio in the phase difference frequency means at the time of PLL driving and at the time of releasing the PLL drive;
An ultrasonic transducer driving device comprising:

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