JP4020559B2 - Ultrasonic transducer drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic transducer driving apparatus suitable for an ultrasonic surgical apparatus using a Langevin type ultrasonic transducer.
[0002]
[Prior art]
Conventionally, various apparatuses such as a surgical ultrasonic scalpel, an ultrasonic cleaning machine, and an ultrasonic processing apparatus using an ultrasonic vibrator have been developed. The ultrasonic transducer used in such an ultrasonic device is preferably driven at its resonance frequency in order to increase efficiency.
[0003]
For example, in Japanese Patent No. 2691011 (hereinafter referred to as Document 1), an oscillation circuit that oscillates at a fundamental frequency serving as a reference for resonance point driving and a means for feeding back a drive signal of an ultrasonic transducer are provided, and the fundamental frequency is set when oscillation starts. A technique for facilitating activation of oscillation by driving an ultrasonic transducer with a signal and driving the ultrasonic transducer with a feedback signal after activation is disclosed.
[0004]
Japanese Patent Publication No. 9-247713 (hereinafter referred to as “Document 2”) discloses a drive circuit technique in which an ultrasonic transducer is reliably driven at a resonance point by using a PLL (phase synchronization rope). Has been.
[0005]
In Japanese Patent Laid-Open No. 7-313937 (hereinafter referred to as “Document 3”), an ultrasonic transducer driving device detects whether or not an oscillation frequency is within a predetermined range to detect an abnormality, and The technology to notify is disclosed.
[0006]
[Problems to be solved by the invention]
Documents 1 and 2 track the resonance point using a PLL in order to drive the ultrasonic transducer at the resonance point. The PLL performs feedback control using only the phase signal or only the vibration detection signal. For this reason, if the resonance point tracking control with such a single feedback signal is disabled, the driving of the ultrasonic transducer cannot be maintained.
[0007]
FIG. 13 and FIG. 14 are for explaining such a problem.
[0008]
As shown in FIG. 13, a matching coil 2 is connected in parallel to the ultrasonic transducer 1 in order to cancel the braking capacity of the ultrasonic transducer 1.
[0009]
  FIG. 14 is a graph showing the impedance characteristics of the circuit of FIG. 13 with the frequency on the horizontal axis and the phase difference between impedance or voltage and current on the vertical axis. FIG. The mechanical load is normal and the figure14(B) has shown the state where load is too large.
[0010]
In FIG. 14, fr indicates the resonance frequency of the ultrasonic transducer 1, and high-efficiency driving is possible by driving the ultrasonic transducer 1 at the frequency fr. At this resonance frequency fr, the voltage phase and current phase supplied to the ultrasonic transducer 1 are the same phase, and before and after the resonance frequency fr, the phase difference changes up and down around 0 °.
[0011]
In the proposals of Documents 1 and 2, the resonance point is tracked by making the phase difference zero by a PLL circuit. When the load of the ultrasonic transducer 1 is normal, as shown in FIG. 14A, the change rate of the phase difference Δθ is large, so that the resonance point tracking control by the PLL circuit is easy. However, when the load on the ultrasonic transducer 1 is too large, as shown in FIG. 14B, the rate of change of the phase difference Δθ is small, so that resonance point tracking control is difficult. In other words, the proposals in Documents 1 and 2 have a problem that resonance point tracking may become impossible due to load fluctuations.
[0012]
In Reference 3, the abnormal state of the drive circuit and the ultrasonic transducer is monitored depending on whether or not the oscillation frequency is within a predetermined range. However, even when the ultrasonic transducer fails, the oscillation frequency may be within a predetermined range, and an abnormality may not be detected even if the impedance is unstable. Even if the oscillation frequency becomes a value outside the predetermined range, an abnormality may not be detected even when the oscillation frequency returns to a value within the predetermined range in a short time.
[0013]
By the way, when an ultrasonic transducer is applied to an ultrasonic surgical apparatus, a probe for transmitting the vibration to a living tissue is connected to the ultrasonic transducer. And an ultrasonic transducer | vibrator is built and used in the handpiece which an operator uses.
[0014]
By the way, even when an abnormality occurs in the ultrasonic vibration, conventionally, it is impossible to identify whether the ultrasonic vibrator is abnormal or the probe is abnormal. Thus, for example, a method of detecting an abnormality by preparing a dummy probe for inspection and testing when the abnormality occurs by replacing the probe with a dummy probe for inspection has been considered. However, this method requires a probe replacement operation and is extremely complicated.
[0015]
In addition, since an ultrasonic surgical apparatus is required to be sterilized, autoclave sterilization under high-temperature steam is performed. During this sterilization process, water vapor may enter the handpiece. Since the ultrasonic vibrator cannot be driven in a state where water vapor has entered the handpiece, it is necessary to check whether water vapor has entered the handpiece before use. there were.
[0016]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an ultrasonic transducer driving apparatus capable of reliably driving a resonance point even when the load state of the ultrasonic transducer changes greatly. And
[0017]
It is another object of the present invention to provide an ultrasonic transducer driving apparatus that can reliably detect abnormality of an ultrasonic transducer without requiring complicated work.
[0018]
It is another object of the present invention to provide an ultrasonic transducer driving apparatus that can reliably identify an abnormal part of a handpiece including an ultrasonic transducer.
[0019]
[Means for Solving the Problems]
  An ultrasonic transducer driving device according to claim 1 of the present invention is based on an ultrasonic transducer driving oscillator that drives an ultrasonic transducer, and phase information of a drive signal that is supplied from the oscillator to the ultrasonic transducer. A first control circuit for controlling the oscillator;Based on the drive voltage and drive current of the drive signal supplied from the oscillator to the ultrasonic transducer,Monitoring means for detecting the impedance of the ultrasonic transducer;Based on the impedance of the ultrasonic transducer detected by the monitoring means, so that the impedance of the ultrasonic transducer is minimized.The oscillatorOscillation frequencyAnd a selection means for switching and selecting one of the first control circuit and the second control circuit based on the detection result of the impedance,
  An ultrasonic transducer driving apparatus according to a third aspect of the present invention is based on an ultrasonic transducer driving oscillator that drives an ultrasonic transducer and phase information of a drive signal that is supplied from the oscillator to the ultrasonic transducer. A control circuit that controls the oscillator to a resonance frequency of the ultrasonic transducer; and a monitoring unit that detects an impedance of the ultrasonic transducer;SaidInformation corresponding to control of the control circuitObtain sequentiallyHolding means to holdWhen,Based on the detection result of the impedance,Selection means for switching and selecting the information held in the holding means in place of the phase information and supplying the information to the control circuit to control the oscillator is provided.
[0020]
In the first aspect of the present invention, the ultrasonic transducer is driven by a drive signal from an ultrasonic transducer driving oscillator. The first control circuit controls the oscillator based on the phase information of the drive signal. The second control circuit controls the oscillator based on the voltage and current of the drive signal. The monitoring means monitors the impedance of the ultrasonic transducer, and selects which of the first and second control circuits controls the oscillator based on the impedance detection result.
[0021]
According to a third aspect of the present invention, the ultrasonic transducer is driven by a drive signal from an ultrasonic transducer driving oscillator. The control circuit controls the frequency of the oscillator to the resonance frequency of the ultrasonic transducer based on the phase information of the drive signal. The holding means holds information corresponding to the control of the control circuit. The monitoring unit monitors the impedance of the ultrasonic transducer, and selects which of the control circuit and the holding unit controls the oscillator based on the impedance detection result.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing a configuration of an ultrasonic transducer driving apparatus, and FIG. 2 is a flowchart for explaining the operation thereof.
[0023]
In FIG. 1, an ultrasonic transducer 3 to which a probe is connected is driven by a drive and detection circuit 7 to generate ultrasonic vibrations. The oscillation circuit 4 generates a frequency signal for driving the ultrasonic transducer 3 based on a signal from the switching unit 14 described later, and outputs the frequency signal to a voltage controlled amplifier (hereinafter referred to as VCA) 5. The VCA 5 amplifies the input frequency signal to a voltage based on the control signal from the differential amplifier circuit 9 and outputs the amplified signal to a power amplifier circuit (hereinafter referred to as AMP) 6. The AMP 6 amplifies the input frequency signal to power that can drive the ultrasonic transducer 3 and outputs the amplified signal to the drive and detection circuit 7.
[0024]
The drive and detection circuit 7 drives the ultrasonic transducer 3 based on the output of the AMP 6 and detects the voltage and current applied to the ultrasonic transducer 3. The drive and detection circuit 7 outputs the phase θV and θI of the voltage and current applied to the ultrasonic transducer 3 to the phase difference detection circuit 10 and converts the absolute values | V | and | I | of the voltage and current to | Z | (Impedance) Output to the minimum value detection circuit 11 and output the voltage and current values to the state detection circuit 12 The drive and detection circuit 7 outputs the absolute value | I | of the current to the differential amplifier circuit 9.
[0025]
The setting signal generator 8 generates a setting signal for setting the amplitude of the ultrasonic transducer 3 and outputs the setting signal to the differential amplifier circuit 9. The differential amplifier circuit 9 compares the setting signal with the absolute value of the current from the drive and detection circuit 7 and outputs a control signal based on the difference to the VCA 5. These VCA 5, AMP 6, drive and detection circuit 7 and differential amplifier circuit 9 constitute a constant current control loop that controls the amplitude of the ultrasonic transducer 3 to be constant.
[0026]
The phase difference detection circuit 10 detects the phase difference between the input phases θV and θI and outputs a phase difference signal to the switching unit 14. Also, the | Z | minimum value detection circuit 11 detects a minimum value of the magnitude of the impedance from the input absolute values | V | and | I |, and outputs a minimum value signal based on the detection result to the switching unit 14. .
[0027]
For example, the | Z | local minimum value detection circuit 11 controls the oscillation circuit 4 (not shown) to oscillate at the resonance frequency f0 of the ultrasonic transducer 3, and stores the magnitude of the impedance as | Z | 0. To do. Next, the | Z | local minimum value detection circuit 11 slightly increases the oscillation frequency, stores the magnitude of the impedance at that time as | Z | +, and further decreases the oscillation frequency slightly below the resonance frequency f0. The magnitude of the impedance at that time is stored as | Z | −. | Z | The minimum value detection circuit 11 can control the oscillation frequency of the oscillation circuit 4 by setting the frequency that gives the impedance having the smallest value among these three impedances to the resonance frequency f0. Yes.
[0028]
Various methods of changing the frequency for detecting the minimum value of the | Z | minimum value detection circuit 11 are conceivable, and the number of changes is not limited to three. | Z | By using the minimum value signal from the minimum value detection circuit 11, it is possible to drive by tracking the minimum value of the impedance.
[0029]
The state detection circuit 12 monitors the magnitude of the impedance of the ultrasonic transducer 3 based on the voltage and current values from the drive and detection circuit 7 and detects the load state. The state detection circuit 12 controls the switching unit 14 based on the detection result, and generates an alarm by the alarm generation circuit 13 when the load increases to a predetermined value or more. The alarm generation circuit 13 is controlled by the state detection circuit 12 to generate an alarm.
[0030]
When the detection result of the state detection circuit 12 indicates that the load is within the normal range, the switching unit 14 provides the phase difference signal from the phase difference detection circuit 10 to the oscillation circuit 4. When it is indicated that the magnitude of the load is abnormally large, the minimum value signal from the | Z | minimum value detection circuit 11 is supplied to the oscillation circuit 4.
[0031]
Next, the operation of the embodiment configured as described above will be described with reference to the flowchart of FIG.
[0032]
The frequency signal from the oscillation circuit 4 is amplified by the VCA 5 and AMP 6 and then applied to the drive and detection circuit 7. The drive and detection circuit 7 drives the ultrasonic transducer 3 based on the input frequency signal. The drive and detection circuit 7 supplies the absolute value | I | of the current supplied to the ultrasonic transducer 3 to the differential amplifier circuit 9, and the differential amplifier circuit 9 outputs the absolute value | I | A signal based on the difference is supplied to the VCA 5 to control the amplification factor of the VCA 5. As a result, a constant current control loop is formed, and the amplitude of the ultrasonic transducer 3 is controlled to be constant.
[0033]
In addition, the drive and detection circuit 7 supplies the phase difference detection circuit 10 with the phases θV and θI of the voltage and current supplied to the ultrasonic transducer 3. The phase difference detection circuit 10 detects a phase difference between voltage and current, and supplies a phase difference signal to the oscillation circuit 4 via the switching unit 14. If the magnitude of the load on the ultrasonic transducer 3 is within the normal range, the phase difference signal from the phase difference detection circuit 10 is given to the oscillation circuit 4 by the switching unit 14, and the oscillation circuit 4 The oscillation frequency is changed so that becomes zero. Thus, the resonance frequency of the ultrasonic transducer 3 is tracked, and the ultrasonic transducer 3 is driven at the resonance point.
[0034]
The voltage and current values from the drive and detection circuit 7 are also supplied to the state detection circuit 12. The state detection circuit 12 monitors the magnitude of the impedance from the voltage and current values, and detects the load state. Now, it is assumed that the impedance of the load increases from a predetermined value. Then, the state detection circuit 12 detects that the load has increased abnormally, causes the alarm generation circuit 13 to generate an alarm, and causes the switching unit 14 to select the output of the | Z | minimum value detection circuit 11.
[0035]
The absolute value | V |, | I | of the voltage and current supplied to the ultrasonic transducer 3 from the drive and detection circuit 7 is given to the | Z | local minimum value detection circuit 11. In step S1 in FIG. 2, the | Z | local minimum value detection circuit 11 causes the oscillation circuit 4 to output an oscillation output of the frequency f0 and stores the impedance | Z | 0 at that time. Next, the | Z | local minimum value detection circuit 11 increases the oscillation frequency to obtain the impedance | Z | + in step S2, and further decreases the oscillation frequency to obtain the impedance | Z |-in step S3. To do. | Z | The minimum value detection circuit 11 outputs a minimum value signal for resetting the oscillation frequency giving the smallest impedance as the resonance frequency f0.
[0036]
When the load impedance increases abnormally, the minimum value signal from the | Z | minimum value detection circuit 11 is supplied to the oscillation circuit 4 via the switching unit 14. As a result, the oscillation circuit 4 tracks the minimum value of the impedance and determines the oscillation frequency. Since the impedance becomes a minimum value at the resonance point, the ultrasonic transducer 3 is driven at the resonance point even when the load increases.
[0037]
In the impedance minimum value tracking type control, it is necessary to execute a plurality of scans to detect the minimum value, the tracking control requires a long time, and is less stable than the PLL control. Therefore, when the magnitude of the impedance returns to the normal range, the state detection circuit 12 controls the switching unit 14 to provide the phase detection signal to the oscillation circuit 4 to return to PLL control.
[0038]
As described above, in this embodiment, when the load of the ultrasonic transducer 3 increases, the impedance increases, and the change width of the phase difference between the voltage and the current decreases, and the PLL control becomes impossible. , By detecting the increase in the load by monitoring the magnitude of the impedance and switching from the PLL control to the impedance minimum value tracking type control, the ultrasonic transducer 3 is reliably driven at the resonance point regardless of the fluctuation of the load. can do. That is, even when the load state changes significantly, stable driving at the resonance point can be maintained, and a safe surgical apparatus or the like can be provided.
[0039]
FIG. 3 is a block diagram showing a configuration of an ultrasonic transducer driving apparatus according to the second embodiment of the present invention.
[0040]
This embodiment is different from the first embodiment in that the switching unit 14 and the | Z | minimum value detection circuit 11 are omitted and a frequency holding circuit 51 is added. The frequency holding circuit 51 sequentially acquires and holds information related to the oscillation frequency from the oscillation circuit 4, and oscillates information on the frequency held at normal time when a detection result indicating an abnormal increase in load is given from the state detection circuit 12. The oscillation frequency of the oscillation circuit 4 is fixed by giving to the circuit 4.
[0041]
Next, in the embodiment configured as described above, the oscillation frequency is controlled based on the phase difference detection signal when the load of the ultrasonic transducer 3 is normal, as in the first embodiment. is there.
[0042]
In the present embodiment, during such normal operation, the frequency holding circuit 51 sequentially holds information regarding the oscillation frequency of the oscillation circuit 4. When the state detection circuit 12 detects a load abnormality due to an increase in impedance, the frequency holding circuit 51 gives the information on the normal oscillation frequency held to the oscillation circuit 4, and the oscillation frequency of the oscillation circuit 4 is added to this oscillation frequency. To fix.
[0043]
Thereby, the resonance point drive of the ultrasonic transducer 3 is maintained. In addition, it is possible to prevent normal PLL control from being disabled and the oscillation frequency of the oscillation circuit 4 to diverge to a frequency significantly different from the resonance frequency.
[0044]
When the load returns to the normal value, the state detection circuit 12 cancels the fixed control of the oscillation frequency by the frequency holding circuit 51 and returns to the PLL control based on the phase difference signal.
[0045]
As described above, in this embodiment as well, as in the first embodiment, even if the load state of the ultrasonic transducer greatly fluctuates, the control by the PLL is temporarily supplemented while substantially tracking the resonance point. The resonance point drive of the ultrasonic transducer can be maintained.
[0046]
In the present embodiment, the information about the oscillation frequency is held. However, the output control value of the phase difference detection circuit 10 is held, and when the load becomes abnormally large, the held control value is used. The oscillation circuit 4 may be controlled.
[0047]
FIG. 4 is a block diagram showing a configuration of an ultrasonic transducer driving apparatus according to the third embodiment of the present invention. In FIG. 4, the same components as those of FIG. In this embodiment, notification to the user is made possible when an abnormality occurs.
[0048]
The tracking control circuit 15 receives a feedback signal such as a voltage and a current value from the drive and detection circuit 7, and controls the oscillation frequency of the oscillation circuit 4 based on the feedback signal. The tracking control circuit 15 is configured by, for example, the phase difference detection circuit 10 in the first embodiment, and performs resonance point tracking control for setting the oscillation frequency of the oscillation circuit 4 to the resonance frequency.
[0049]
The frequency change detection circuit 16 is supplied with the oscillation signal of the oscillation circuit 4 and detects a change in the oscillation frequency. The drive voltage change detection circuit 17 is supplied with the output of the differential amplifier circuit 9 and detects a change in the drive voltage of the ultrasonic transducer 3.
[0050]
The frequency change detection circuit 16 and the drive voltage change detection circuit 19 detect an abnormality of the device from the change of the oscillation frequency or the change of the drive voltage, respectively, and if an abnormality has occurred in the device, an alarm generation circuit 18 is configured to generate an alarm.
[0051]
Various methods can be considered as a method for determining abnormality by the frequency change detection circuit 16 and the drive voltage change detection circuit 19. For example, the frequency change detection circuit 16
(1) An abnormality may be determined when the frequency changes more than a predetermined frequency difference with respect to a predetermined oscillation frequency fr.
(2) The magnitude of the frequency change may be differentiated, and the result may be determined as abnormal if the result exceeds a predetermined threshold.
[0052]
Further, the drive voltage change detection circuit 17 can also determine abnormality by a similar method.
[0053]
When an abnormality is detected by the frequency change detection circuit 16 or the drive voltage change detection circuit 17, the alarm generation circuit 18 generates an alarm and stops the operation of the tracking control circuit 15.
[0054]
Next, the operation of the embodiment configured as described above will be described.
[0055]
When the ultrasonic transducer 3 is operating normally, the tracking control circuit 15 performs resonance point tracking control by controlling the oscillation frequency of the oscillation circuit 4 based on the feedback signal. Further, the differential amplifier circuit 9 performs constant current control by controlling the output of the VCA 5 based on the absolute value | I | of the current of the ultrasonic transducer 3 and the setting signal.
[0056]
During normal operation of the ultrasonic transducer 3, the frequency of the drive signal of the ultrasonic transducer 3 is stable at a frequency within a predetermined range by resonance point tracking control. Further, the drive current of the ultrasonic transducer 3 is controlled to be substantially constant in accordance with a load variation applied to a handpiece (not shown) constituted by the ultrasonic transducer 3 and a probe (not shown). The drive voltage of the vibrator 3 changes so that the drive current is substantially constant. In this case, the change range of the drive voltage is substantially stable within a predetermined range.
[0057]
Here, it is assumed that an abnormality occurs due to a failure of the ultrasonic transducer 3 or a crack in the probe. Then, the feedback signal input to the tracking control circuit 15 becomes unstable, and the resonance point tracking control and the constant current drive control become unstable operations. That is, due to the unstable control of the tracking control circuit 15, the oscillation frequency of the oscillation circuit 4 fluctuates more than a predetermined frequency width, for example. In addition, the control voltage generated by the differential amplifier circuit 9 also varies more than a predetermined voltage width.
[0058]
The frequency change detection circuit 16 detects an abnormality in the oscillation frequency of the oscillation circuit 4, and the drive voltage change detection circuit 17 detects an abnormal fluctuation in the control voltage of the differential amplifier circuit 9. The frequency change detection circuit 16 and the drive voltage change detection circuit 17 notify the alarm generation circuit 18 that an abnormality has been detected. Thereby, the alarm generation circuit 18 notifies the user that an abnormality has occurred in the ultrasonic transducer 3 or the probe. The alarm generation circuit 18 stops the tracking control by the tracking control circuit 15. Thereby, abnormal divergence of the oscillation frequency of the oscillation circuit 4 is prevented.
[0059]
Thus, in the present embodiment, the abnormal state of the vibration system can be detected at an early stage to notify the user and the abnormal state can be avoided.
[0060]
5 to 7 relate to a fourth embodiment of the present invention, FIG. 5 is an explanatory diagram showing a general configuration of an ultrasonic surgical apparatus, FIG. 6 is an explanatory diagram for explaining a resonance frequency, and FIG. Is a flowchart for explaining the operation. The configuration of this embodiment is the same as that of the first embodiment. The present embodiment facilitates the determination of the failure part.
[0061]
The drive device 20 has the same configuration as that obtained by removing the ultrasonic transducer 3 from FIG. The foot switch (referred to as FSW) 21 is for turning on and off the ultrasonic output from the ultrasonic transducer 3 (see FIG. 4). The ultrasonic transducer 3 is accommodated in the holding case 22. A probe 23 including a treatment portion is fastened to the distal end of the holding case 22 with a screw. These holding case 22 and probe 23 constitute a hand piece.
[0062]
By the way, the resonance frequency when the probe and the ultrasonic transducer 3 are in a normal state is different from the resonance frequency when a failure occurs in the probe or the ultrasonic transducer 3. In FIG. 6, the horizontal axis indicates the frequency, the resonance frequency range fr ± Δf in a normal state when the probe is connected to the ultrasonic transducer is indicated by a thick arrow, and the probe is connected to the ultrasonic transducer 3. The resonance frequency range fn ± Δfn in a non-existing state is indicated by a bold line. Further, the resonance frequency when at least one of the probe and the ultrasonic transducer 3 is broken is indicated by ◯. As shown in FIG. 6, the resonance frequency at the time of failure is in a range outside the thick line, for example, frequencies f ′ and f ″.
[0063]
The frequency change detection circuit 16 (see FIG. 4) in the present embodiment stores the characteristics of FIG. 6, detects in which frequency band the oscillation frequency of the oscillation circuit 4 exists, and the detection result. Can be output to the alarm generation circuit 18.
[0064]
Next, the operation of the embodiment configured as described above will be described with reference to the flowchart of FIG.
[0065]
Now, it is assumed that a procedure such as surgery is performed with the probe 23 connected to the tip of the holding case 22 in which the ultrasonic transducer 3 is built. The frequency change detection circuit 16 monitors the oscillation frequency of the oscillation circuit 4. When the resonance point drive of the ultrasonic transducer 3 is normally performed, the oscillation frequency detected by the frequency change detection circuit 16 is a value within the frequency range fr ± Δf of FIG.
[0066]
Here, it is assumed that the ultrasonic transducer 3 cannot be driven (step S11). The oscillation frequency of the oscillation circuit 4 fluctuates, and the frequency change detection circuit 16 detects that the oscillation frequency has reached a value such as the frequencies f ′ and f ″ in FIG. 6 and notifies the alarm generation circuit 18 accordingly. The alarm generation circuit 18 notifies the user that the ultrasonic transducer 3 cannot be driven.
[0067]
The user removes the probe from the ultrasonic transducer 3 in step S12. Next, the user operates the foot switch 21 to resume driving the ultrasonic transducer 3. If the reason why the ultrasonic transducer 3 cannot be driven normally is that the probe is abnormal and the ultrasonic transducer 3 is normal, the oscillation frequency of the oscillation circuit 4 is within the frequency range fn of FIG. It takes a value within ± Δfn. When the frequency change detection circuit 16 detects that the oscillation frequency of the oscillation circuit 4 is within this range (step S14), the frequency change detection circuit 16 outputs a detection result to the alarm generation circuit 18 so that the user can be detected by a probe failure. In addition to presenting that sound wave drive has become impossible, the user is presented for probe replacement.
[0068]
Conversely, if the oscillation frequency of the oscillation circuit 4 is not within the frequency range fn ± Δfn, the frequency change detection circuit 16 determines that a failure has occurred in the ultrasonic transducer 3 and indicates this. An alarm is generated in the alarm generation circuit 18. The alarm generation circuit 18 prompts replacement of the ultrasonic transducer in step S16.
[0069]
Thus, in the present embodiment, it is possible to easily determine whether the broken part of the handpiece is a probe or an ultrasonic transducer. This eliminates the need for a test probe, allows the work using the test probe to be omitted, and makes it possible to significantly improve workability. In other words, when various abnormalities occur, it is possible to easily specify the type and location of the abnormalities, and to provide a surgical apparatus and the like that can take appropriate measures at an early stage.
[0070]
8 and 9 relate to a fifth embodiment of the present invention, FIG. 8 is a block diagram showing an ultrasonic transducer driving apparatus according to the fifth embodiment, and FIG. 9 is generated in the ultrasonic transducer. An equivalent circuit showing leakage resistance, FIG. 10 is a graph for explaining the operation. This embodiment corresponds to a case where moisture remains in the handpiece due to autoclave sterilization.
[0071]
In FIG. 8, the handpiece 30 houses an ultrasonic transducer. The ultrasonic transducer is driven by a signal from the drive circuit 32. The frequency control circuit 33 outputs a frequency instruction signal to the drive circuit 32. The drive circuit 32 is configured to drive the ultrasonic transducer at a resonance point based on the input instruction signal. The detection circuit 31 detects a drive signal applied to the ultrasonic transducer by the drive circuit 32 and outputs it to the determination circuit 34.
[0072]
The detection circuit 31 feeds back a feedback signal based on the detection result to the drive circuit 32. Thereby, the amplitude of the drive signal is controlled to be constant and the frequency is controlled to the resonance frequency.
[0073]
The determination circuit 34 determines the state of the handpiece 30 based on the detection result from the detection circuit 31 and outputs the determination result to the control circuit 35. The control circuit 35 outputs display data based on the determination result to the display panel 36 so that the display of the determination result is displayed on the screen. The control circuit 35 also controls the frequency control circuit 33.
[0074]
Next, the operation of the embodiment configured as described above will be described with reference to the graph of FIG. FIG. 10A shows the frequency characteristics of the impedance in a normal state with the horizontal axis representing frequency and the vertical axis representing impedance. FIG. 10B shows frequency along the horizontal axis and impedance along the vertical axis. The characteristic of impedance when leakage resistance occurs inside the case is shown.
[0075]
Now, it is assumed that moisture remains in the case by autoclaving the handpiece with high-temperature steam. In this case, as shown by the equivalent circuit in FIG. 9, leakage resistance is generated in parallel in the ultrasonic transducer.
[0076]
Therefore, in this state, the ultrasonic transducer cannot be driven normally. Therefore, the determination circuit 34 detects a decrease in impedance due to the leakage resistance. Compared with the normal impedance shown in FIG. 10A, the abnormal impedance shown by the solid line in FIG. 10B is lowered. As is clear from the comparison with the broken line (normal impedance) in FIG. 10B, in the vicinity of the resonance point, the difference in impedance between the normal time and the abnormal time is small, and at the antiresonance points (f1, f2). The difference in impedance is large.
[0077]
Therefore, in order to reliably detect the presence of the leakage resistance, it is desirable to make a determination at a frequency at which the normal impedance is high, for example, f1 and f2 which are anti-resonance points. Alternatively, since the impedance characteristic near the resonance frequency has a large difference between solids and may change depending on the load applied to the handpiece, the impedance is normalized by applying a frequency ftest away from the resonance frequency, for example, a frequency of 1 kHz. The accuracy is further improved by comparing with the value.
[0078]
After autoclave sterilization, the frequency control circuit 33 is controlled by the control circuit 35 to set the oscillation frequency of the drive circuit 32 to f1, f2, or ftest in FIG. The detection circuit 31 outputs the voltage and current value of the drive signal for the ultrasonic transducer to the determination circuit 34. The determination circuit 34 obtains the impedance at the oscillation frequency f1, f2, or ftest. The determination circuit 34 determines the presence or absence of leakage resistance by comparing the impedance at the normal time with the impedance at the oscillation frequency f1, f2, or ftest. The determination circuit 34 outputs the determination result to the control circuit 35.
[0079]
When the determination result indicates that there is leakage resistance, the control circuit 35 displays a display indicating that water remains in the handpiece on the screen of the display panel 36 and is in an unusable state. Display.
[0080]
As described above, in the present embodiment, by detecting a decrease in impedance due to leakage resistance, it is detected that moisture that has entered the case of the handpiece remains, and an abnormal state is notified to the user. can do.
[0081]
11 and 12 relate to a sixth embodiment of the present invention, FIG. 11 is a block diagram showing an ultrasonic transducer driving apparatus according to the sixth embodiment, and FIG. 12 is a waveform memory 47 in FIG. It is a wave form diagram for demonstrating the waveform data memorize | stored in. In the present embodiment, the ultrasonic transducer can be stably driven by digitization.
[0082]
In FIG. 11, the ultrasonic transducer 40 to which the probe is connected is driven by a drive and detection circuit 41 to generate ultrasonic vibration. The configurations of the drive and detection circuit 41, the AMP 42, and the phase comparison circuit 45 are the same as those of the drive and detection circuit 7, the AMP 6, and the phase difference detection circuit 10 of FIG.
[0083]
In the present embodiment, the drive signal is generated from the waveform memory 47. The A / D converter 43 receives the absolute value | I | of the drive current from the drive and detection circuit 41, converts it into a digital signal, and outputs it to the digital comparator 44. The control circuit 49 generates output setting data for setting the amplitude of the ultrasonic transducer 40 and outputs it to the digital comparator 44. The digital comparator 44 corresponds to the differential amplifier circuit 9 of FIG. 1, compares the output setting data with the absolute value of the current from the A / D converter 43, and performs address designation of the waveform memory 47 based on the difference. It is like that.
[0084]
On the other hand, the phase comparison circuit 45 compares the voltage phase and current phase of the drive signal and outputs the comparison result to a DDS (direct digital synthesizer) 46. The DDS 46 is a digital oscillation circuit that generates a frequency signal based on the comparison result of the phase comparison circuit 45, and outputs an oscillation output as an address instruction of the waveform memory 47.
[0085]
The waveform memory 47 is provided with an address designation from the digital comparator 44 and an address instruction from the DDS 46, and outputs the stored waveform data to the D / A converter 48. The waveform memory 47 stores waveform data for one period having a plurality of types of amplitudes.
[0086]
FIG. 12 shows three types of waveform data stored in the waveform memory 47. These three types of waveform data have different amplitudes. The waveform memory 47 outputs the type of waveform data based on the address designation from the digital comparator 44 among the three types of waveform data. Further, the waveform data from the waveform memory 47 is output at a frequency based on an address instruction from the DDS 46.
[0087]
The D / A converter 48 converts the input waveform data into an analog sine wave signal and outputs it to the AMP 42 as a drive signal. The control circuit 49 can display various setting information on the screen of the display panel 50.
[0088]
Next, the operation of the embodiment configured as described above will be described.
[0089]
Waveform data from the waveform memory 47 is converted into an analog signal by the D / A converter 48, amplified by the AMP 42, and then supplied from the drive and detection circuit 41 to the ultrasonic transducer 40. The drive and detection circuit 41 gives the phase θV and θI of the voltage and current supplied to the ultrasonic transducer 40 to the phase comparison circuit 45 and gives the absolute value | I | of the current to the A / D converter 43.
[0090]
The A / D converter 43 converts the absolute value | I | of the input current into a digital signal and outputs the digital signal to the digital comparator 44. On the other hand, the control circuit 49 generates output setting data for determining the amplitude of the ultrasonic output and outputs it to the digital comparator 44. The digital comparator 44 uses the data based on the difference between the two inputs as a waveform to specify the address. Output to the memory 47. From the waveform memory 47, waveform data having an amplitude based on the address designation is read out.
[0091]
In this way, the amplitude of the output waveform data from the waveform memory 47 is controlled, and constant current control for making the amplitude of the ultrasonic output constant is achieved by digital processing.
[0092]
On the other hand, the phase comparison circuit 45 outputs a signal based on the phase difference between the voltage and current to the DDS 46. The DDS 46 generates a frequency signal based on the phase difference and outputs it as an address instruction of the waveform memory 47. The waveform memory 47 reads waveform data at a frequency based on the input frequency signal. As a result, the frequency of the waveform data output from the waveform memory 47 changes so that the phase difference is zero. Thus, resonance point tracking control for driving the ultrasonic transducer 40 at the resonance frequency is performed.
[0093]
As described above, in the present embodiment, since both frequency control and constant current control can be digitized, stable ultrasonic driving with less adjustment and no variation is possible.
[0094]
[Appendix]
(1) an ultrasonic vibrator driving oscillator for driving an ultrasonic vibrator;
A first control circuit for controlling the oscillator based on phase information of a drive signal supplied from the oscillator to the ultrasonic transducer;
A second control circuit for controlling the oscillator based on a driving voltage and a driving current of a driving signal supplied from the oscillator to the ultrasonic transducer;
Monitoring means for detecting the impedance of the ultrasonic transducer;
An ultrasonic transducer driving apparatus comprising: selection means for switching and selecting one of the first control circuit and the second control circuit based on the detection result of the impedance.
[0095]
(2) The ultrasonic transducer driving apparatus according to appendix 1, further comprising notification means for notifying the control circuit selected by the selection means.
[0096]
(3) an ultrasonic vibrator driving oscillator for driving the ultrasonic vibrator;
A control circuit for controlling the oscillator to a resonance frequency of the ultrasonic vibrator based on phase information of a drive signal supplied from the oscillator to the ultrasonic vibrator;
Monitoring means for detecting the impedance of the ultrasonic transducer;
Holding means for holding information corresponding to the control of the control circuit based on the detection result of the impedance;
An ultrasonic transducer driving apparatus, wherein the oscillator is controlled by switching and selecting one of the control circuit and the holding unit based on the detection result of the impedance.
[0097]
(4) The ultrasonic transducer driving apparatus according to item 3, further comprising notification means for notifying that the oscillator is controlled by the holding means.
[0098]
(5) The ultrasonic transducer driving apparatus according to appendix 1, wherein the second control circuit is a control circuit that controls the oscillator so that an impedance of the ultrasonic transducer is minimized.
[0099]
(6) An ultrasonic vibrator driving oscillator for driving the ultrasonic vibrator, a control circuit for controlling the oscillator to be driven at a resonance frequency of the ultrasonic vibrator, and a frequency variation of the oscillator with respect to a predetermined time. An ultrasonic transducer driving apparatus comprising: a frequency change detecting means for detecting; and a notifying means for notifying the detection result.
[0100]
(7) In the vibrator driving device of the ultrasonic surgical apparatus, a control circuit for controlling the driving voltage so as to keep the driving current of the ultrasonic vibrator constant based on a driving signal supplied to the ultrasonic vibrator; An ultrasonic transducer drive apparatus comprising: drive voltage change detection means for detecting fluctuations of the drive voltage controlled by the control circuit with respect to a predetermined time; and notification means for notifying the detection result.
[0101]
(8) An ultrasonic vibrator driving oscillator for supplying a drive signal to the ultrasonic vibrator, a frequency control means for controlling the oscillation frequency of the oscillator, and a resonance frequency of the ultrasonic vibrator in which the control means is predetermined. An ultrasonic transducer driving apparatus comprising: a detecting unit that detects an impedance of the ultrasonic transducer when the frequency is controlled to a predetermined frequency different from that; and a determining unit that compares the detection result with a predetermined value. .
[0102]
(9) The ultrasonic transducer driving apparatus according to item 8, further comprising notification means for notifying the detection result.
[0103]
【The invention's effect】
As described above, according to the present invention, it is possible to reliably drive the resonance point even when the load state of the ultrasonic transducer changes greatly, and without requiring a complicated operation, the ultrasonic transducer can be driven. It is possible to reliably detect the abnormality, and to specify the abnormal part of the handpiece including the ultrasonic transducer with certainty.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an ultrasonic transducer driving apparatus according to a first embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the first embodiment;
FIG. 3 is a block diagram showing a configuration of an ultrasonic transducer driving apparatus according to a second embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration of an ultrasonic transducer driving apparatus according to a third embodiment of the present invention.
FIG. 5 is an explanatory diagram showing a general configuration of an ultrasonic surgical apparatus to which a fourth embodiment of the present invention is applied.
FIG. 6 is an explanatory diagram for explaining a resonance frequency.
FIG. 7 is a flowchart for explaining the operation of the fourth embodiment;
FIG. 8 is a block diagram showing an ultrasonic transducer driving apparatus according to a fifth embodiment of the present invention.
FIG. 9 is an equivalent circuit showing leakage resistance generated in the ultrasonic transducer.
FIG. 10 is a graph for explaining the operation of the fifth embodiment;
FIG. 11 is a block diagram showing an ultrasonic transducer driving apparatus according to a sixth embodiment.
12 is a waveform diagram for explaining waveform data stored in a waveform memory 47 in FIG. 11;
FIG. 13 is an equivalent circuit diagram for explaining problems of the conventional example.
FIG. 14 is a graph for explaining problems in the conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 3 ... Ultrasonic vibrator, 4 ... Oscillation circuit, 5 ... VCA, 6 ... AMP, 7 ... Drive and detection circuit, 9 ... Differential amplification circuit, 10 ... Phase difference detection circuit, 11 ... | Z | Minimum value detection circuit , 12 ... state detection circuit, 13 ... alarm generation circuit, 14 ... switching unit.

Claims (4)

An ultrasonic transducer driving oscillator for driving the ultrasonic transducer;
A first control circuit for controlling the oscillator based on phase information of a drive signal supplied from the oscillator to the ultrasonic transducer;
Monitoring means for detecting the impedance of the ultrasonic transducer based on the drive voltage and drive current of the drive signal supplied from the oscillator to the ultrasonic transducer ;
A second control circuit for controlling the oscillation frequency of the oscillator based on the impedance of the ultrasonic transducer detected by the monitoring means so that the impedance of the ultrasonic transducer is minimized ;
An ultrasonic transducer driving apparatus comprising: selection means for switching and selecting one of the first control circuit and the second control circuit based on the detection result of the impedance.   2. The ultrasonic transducer driving apparatus according to claim 1, further comprising notification means for notifying the control circuit selected by the selection means. An ultrasonic transducer driving oscillator for driving the ultrasonic transducer;
A control circuit for controlling the oscillator to a resonance frequency of the ultrasonic vibrator based on phase information of a drive signal supplied from the oscillator to the ultrasonic vibrator;
Monitoring means for detecting the impedance of the ultrasonic transducer;
Holding means for holding sequentially obtaining information corresponding to the control of the control circuit,
Selection means for switching and selecting the information held in the holding means instead of the phase information based on the detection result of the impedance and supplying the information to the control circuit to control the oscillator. Ultrasonic vibrator drive device. 4. The ultrasonic transducer driving apparatus according to claim 3, further comprising notification means for notifying that the oscillator is controlled based on information held in the holding means.

Images