JPH01262000A - Amplitude measuring device for ultrasonic vibrator transducer - Google Patents

Abstract

PURPOSE:To always accurately measure the amplitude of an ultrasonic vibrator transducer by providing a high frequency power source connected parallel to the driving power source of the ultrasonic vibrator transducer and a means to measure a current which flows from the high frequency power source to the ultrasonic vibrator transducer. CONSTITUTION:A driving voltage from a driving power source 12 and a voltage for measuring from a high frequency power source 14 are impressed on an ultrasonic vibrator transducer 10 independently and respectively. The ultrasonic vibrator transducer 10 oscillates by the driving voltage, and capacitance changes by oscillation. Thus, a high frequency current to flow from the high frequency power source 14 to the ultrasonic vibrator transducer 10 is amplitude-modulated. The amplitude-modulated high frequency current is detected with a current detector 16 and rectified by a rectifier 18, and the amplitude waveform of the ultrasonic vibrator transducer 10 is obtained through a BPF20. The amplitude of the ultrasonic vibrator transducer 10 can be measured from the amplitude waveform.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to ultrasonic vibrations of medical ultrasonic scalpels, stone destruction devices, ultrasonic observation devices, industrial ultrasonic processing machines, ultrasonic motors, etc. The present invention relates to an amplitude measuring device for an ultrasonic transducer used in a device.

[Conventional technology]

Conventionally, in order to measure the amplitude of an ultrasonic vibrator used in an ultrasonic vibrator, an electrostrictive element, a strain gauge, an acceleration sensor, etc. are attached to the vibrator and the output is monitored, or a magnetic displacement meter, optical Displacement meters, laser Doppler speed meters, etc. were used. A method has also been devised in which the current flowing from the drive power source to the vibrator is detected and the amplitude is measured. Examples of these include JP-A-61-84575, JP-A-51-140526, and USP No. 4,587°95.
No. 8 and Japanese Patent Application No. 62-299239 filed by the applicant of the present application.

[Problem to be solved by the invention]

However, the former method has a problem in that the vibration form of the vibrator changes when a sensor is attached to the vibrator.

Furthermore, in order to mount the sensor so that it does not come off due to vibration, there is also the disadvantage that the device becomes large and expensive.

Furthermore, in the latter method, the relationship between the current flowing from the drive power source to the vibrator and the amplitude changes depending on the drive frequency, so it was not possible to accurately measure the amplitude. Furthermore, the relationship between this current and amplitude often fluctuates due to changes in load.

This invention was made to deal with the above-mentioned circumstances,
The purpose of this is to create an ultrasonic transducer that eliminates the need to attach anything that affects the vibration form, such as a sensor, to the transducer, and that can always accurately measure the amplitude of the ultrasonic transducer even if the drive frequency or load changes. An object of the present invention is to provide an apparatus for measuring the amplitude of .

[Means to solve the problem]

FIG. 1 schematically shows an apparatus for measuring the amplitude of an ultrasonic transducer according to the present invention. 20-30KI+z for ultrasonic transducer 10
A driving power source 12 having a frequency of is connected.

A high frequency power source 14 is connected in parallel to the drive power source 12 . The frequency of the high frequency power source 14 is set to be higher than the frequency of the drive power source 12 and high enough to be separated by a filter, for example, 1 MHz or higher. For this reason, the ultrasonic transducer 10 has a high frequency power source 1 connected to the current from the drive power source 12.
4 flows, but the ultrasonic transducer 10 receives a low frequency (approximately 20 to 30
It is driven according to the voltage of K l1z).

A current detector 16 is connected in series to the high frequency power source 14, and the current flowing from the high frequency power source 14 to the vibrator 10 is detected. The output of the current detector 16 is outputted as an amplitude measurement result via a rectifier 18 and a band pass filter (BPF) 20. The pass band of the BPF 20 is set to the frequency band of the drive power source 12.

[Effect]

The ultrasonic vibrator 10 vibrates with a waveform corresponding to a low frequency drive voltage VL (FIG. 2(a)) from a drive power source 12. FIG. 2(b) shows the high frequency amplitude 11 from the high frequency power source 14.
This is the voltage VH for 111 regular use.

Here, there is a capacitance between the electrodes of the ultrasonic transducer 10, and this value is determined by the cross-sectional area of the transducer and the distance between the electrodes, and when the strain of the ultrasonic transducer 10 is positive (stretched If it is negative (if it is shrinking), it will become larger, and if it is negative (if it is shrinking), it will become smaller. Therefore, the high frequency current iH flowing from the high frequency power source 14 to the vibrator 10 is subjected to amplitude modulation due to the change in capacitance caused by the vibration of the ultrasonic vibrator 10, as shown in FIG. 2(c).

When this amplitude-modulated high-frequency current is detected by a current detector 16 and rectified by a rectifier 18, a signal as shown in FIG. 2(d) is obtained. When this is outputted via the BPF 20, a signal as shown in FIG. 2(e) is obtained, and the amplitude of the ultrasonic transducer 10 can be measured.

With this configuration, the amplitude of the ultrasonic transducer can be accurately measured at all times without attaching anything that affects the vibration form, such as a sensor, to the ultrasonic transducer, even if the drive frequency or load changes. can be measured.

〔Example〕

FIG. 3 shows a first embodiment. The same parts as in FIG. 1 are given the same reference numerals. A low pass filter (LPF) 22 is connected between the ultrasonic transducer 10 and the drive power source 12. A series circuit including a bypass filter (HPF) 24, a current detector 16, and a high frequency power source 14 is connected in parallel to a series circuit including a drive power source 12 and an LPF 22. The center frequency of the HPF 24 is higher than the frequency of the drive power supply 12, and the high frequency power supply 1
It is set lower than the frequency of 4.

The output of the current detector 16 is supplied to a comparator 26 via a rectifier 18 and a BPF 20. A reference signal Vref indicating a desired amplitude (waveform) of the vibrator 10 is inputted to the comparator 26 as a reference signal.

The difference signal output from the comparator 26 is passed through the integrator 28 to a voltage controlled amplifier (VCA) provided in the drive power supply 12.
) 30 is fed back to the control voltage terminal.

According to the first embodiment, the drive voltage from the drive power supply 12;
Each voltage is applied to the ultrasonic transducer 10 independently of the measurement voltage from the high frequency power source 14. The ultrasonic vibrator 10 vibrates due to the driving voltage, and the capacitance changes due to the vibration. As a result, the high-frequency current flowing from the high-frequency power supply 14 to the ultrasonic transducer is amplitude-modulated, and this current is rectified by the rectifier 18 and passed through the BPF 20 to the ultrasonic transducer 1.
An amplitude waveform of 0 is obtained. The measured amplitude waveform is compared with the reference waveform, and the difference between the two is integrated and fed back to the VCA 30, which controls the amplitude of the drive voltage, so that the amplitude of the ultrasonic transducer 10 matches the desired reference waveform. It is maintained.

According to the first embodiment, the amplitude of the ultrasonic transducer can be quantitatively measured by accurately measuring the amplitude of the ultrasonic transducer and controlling the driving of the ultrasonic transducer in feedback according to the measurement result. can be controlled.

Therefore, when this embodiment is applied to a medical ultrasonic scalpel, the incision amount can be adjusted, and when applied to a stone destruction device, the destruction efficiency can be adjusted. Furthermore, since there is no need to install a sensor or the like to the ultrasonic vibrator (=1), the vibration form is prevented from changing in order to measure the amplitude.

FIG. 4 shows a second embodiment. This embodiment is the same as the first embodiment except for the connection point of the current detector 16. That is, the current detector 16 is connected between the ultrasonic transducer 10 and the LPF 22. Current detector 16
The output of is supplied to the rectifier 18 via the HPF 24.

The second embodiment also provides the same effects as the first embodiment.

Note that the present invention is not limited to the above description and can be modified in various ways, for example, feedback control of the drive power source is not necessarily required.

〔Effect of the invention〕

As explained above, according to the present invention, a high frequency current for amplitude measurement is superimposed on a drive current and passed through the ultrasonic transducer, and the amplitude is modulated according to the fluctuation in the capacitance of the ultrasonic transducer due to vibration. By detecting and rectifying this high frequency current,
Vibration waveforms can be measured. Therefore, there is no need to attach anything that affects the vibration form, such as a sensor, to the vibrator. Furthermore, even if the driving frequency or load changes, the amplitude of the ultrasonic transducer can always be accurately measured. Furthermore, by feeding back the measurement results to the drive power source, control such as keeping vibration constant can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an amplitude measuring device according to the present invention;
2(a) to 2(e) are waveform diagrams showing the operation of the amplitude measuring device of FIG. 1, FIG. 3 is a block diagram of the first embodiment of the amplitude measuring device according to the present invention, and FIG. 4 is a waveform diagram showing the operation of the amplitude measuring device of FIG. FIG. 2 is a block diagram of a second embodiment of the amplitude measuring device according to the Japanese company. 10... Ultrasonic transducer, 12... Drive power supply, 14...
- High frequency power supply, 16... Current detector, 18... Rectifier, 20... Band pass filter, 22... Low pass filter, 24... Bypass filter, 26... Comparator, 28... Integrator, 30...voltage control amplifier. Applicant's agent Patent attorney Atsushi Tsuboi

Claims (1)

[Claims] An amplitude measuring device for an ultrasonic transducer, comprising: a high frequency power supply connected in parallel to a drive power supply for the ultrasonic transducer; and means for measuring a current flowing from the high frequency power supply to the ultrasonic transducer.