JPH01204509A - Ultrasonic wave oscillator - Google Patents

Abstract

PURPOSE:To attain the excitation in always tracking the resonance frequency of the vibrator by providing two sets of oscillating/drive sections, exciting alternately the vibrator with a prescribed frequency difference by a frequency close to the resonance frequency of the vibrator, detecting the amplitude of the vibrator for each case so as to adjust the oscillated frequency. CONSTITUTION:The two sets or the oscillating/drive sections 7A, 7B excite the vibrator X1 alternately at a prescribed period decided by an oscillator 8 in frequencies if1, f2 close to the resonance frequency f0 of the vibrator X1 and having a prescribed frequency difference. Then the amplitude of the vibrator X1 for each period is detected by a vibration sensor X3, sample and hold circuits 10A, 10B hold the amplitude at each period, the values are compared by a comparator CP, resulting in adjusting the oscillated frequency of oscillators 5A, 5B of the oscillating/drive sections 7A, 7B. Thus, the vibrator X1 is excited in tracking with the resonance frequency f0 of the vibrator X1 at all times.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an ultrasonic oscillator with stable oscillation frequency.

(Issue B to be solved by the prior art and the invention) Various types of ultrasonic oscillators have been proposed. , or the vibrator may be destroyed.

(Means for Solving the Problems) An object of the present invention is to improve the above-mentioned drawbacks and provide an ultrasonic oscillator with a stable oscillation frequency.

In order to achieve the above object, the present invention oscillates at a frequency close to the resonant frequency of the vibrator with a certain frequency difference,
and a first and second oscillating/driving section for driving the vibrator; a control section that alternately operates the second oscillation/drive section at a predetermined period; a detection section that detects the vibration of the vibrator and obtains a signal indicating the magnitude of the amplitude; The first oscillation/drive section holds the output of the detection section corresponding to the operation period of the second oscillation/drive section. a second holding section; Invention of an ultrasonic oscillator comprising: a comparison section that compares the output of the second holding section and adjusts the oscillation frequencies of the first and second oscillation/drive sections according to the comparison result. This is the gist of the report.

(Function) In the present invention, two sets of oscillating/driving sections are provided, and the vibrators are alternately excited at a frequency close to the resonant frequency of the vibrator with a certain frequency difference, and the vibrator in each case is Since the oscillation frequency is adjusted by detecting the amplitude of the oscillator, it is possible to always perform excitation that follows the resonant frequency of the oscillator, and if the resonant frequency of the oscillator shifts, the excitation efficiency will decrease. , the vibrator will not be destroyed.

(Example) Next, an example of the present invention will be described. It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements may be made without departing from the spirit of the present invention.

FIG. 1 shows a Bronk diagram of an ultrasonic oscillator used in the present invention. In FIG. 1, 4 is an oscillator that generates an ultrasonic frequency signal, and 3 is a rectangular Q that is inverted from the output of oscillator 4.

A conversion circuit such as a flip-flop or multi-by-break that creates the output, 2A and 2B are the Q of conversion circuit 3.
, a photocoupler that inputs the Q output, and an IA
, IB is the Q of the conversion circuit 3 from the photocoupler 2A, 213
, a signal corresponding to the σ output is given, and a low voltage voltage fiV
+, a driver that operates at Vz (e.g. 12V),
The sources and drains of Q, , Q, are connected in series with each other, and are connected between the high voltage voltage BVs and the circuit ground, and the gate is connected to the driver IA.

The MOS-FET, X, as a switching element to which a drive signal is applied from IB is a vibrator connected between the connection point of MOS-FETs Q, , Q and the circuit ground.

Next, the operation will be explained. The oscillator 4 generates an ultrasonic frequency signal, the conversion circuit 3 creates mutually inverted rectangular Q, 'r:i outputs, and operates on low voltage electric [V+, Vz] via photocouplers 2A and 2B. 2 M connected in series between the high-voltage power supply and the circuit ground.
OS-FET Q.

Q2 and excites the vibrator X1 connected between the connection point of the two MOS-FETs Q, , Q and the circuit ground. That is, when MOS-FET Ql is on and MOS-FET (h is off), the high voltage tA V
The oscillator X is charged from s, and the MOS-FET Q
When l is off and MOS-FET Q is on, the charge in the resonator X is discharged, and by matching the repetition period, that is, the oscillation period of the oscillator 4, with the resonant frequency of the resonator Xl, the resonator Sound waves are generated.

FIG. 2 shows an embodiment of the ultrasonic oscillator of the present invention.

In the figure, 7A and 7B are respectively oscillating circuits mainly composed of circuit parts excluding the vibrator X shown in Figure 1.
It is a driving section, in which oscillators 5A and 5B correspond to oscillator 4 in FIG. 1, and amplifier 6A.

6B is the conversion circuit 3 and photocoupler 2A shown in FIG.

2B, Driver LA, IB, MO3FET Ql.

It corresponds to Q2. Note that the oscillation/drive section 7A.

7B can start/stop oscillation and adjust the oscillation frequency by a signal applied from the outside. In addition, the oscillation/drive sections 7A and 7B oscillate at a frequency that approximates the resonant frequency of the vibrator X1 with a certain frequency difference, and the vibrator x1
are designed to be driven alternately.

The output signal of the oscillator 8 is applied to the terminals that control the start/stop of oscillation of the oscillation/drive sections 7A and 7B, and switching operations are performed alternately at a cycle longer than the oscillation cycle of the oscillators 5A and 5B. ing. On the other hand, a vibration sensor xt is provided facing the vibrator X1, and its output is amplified, rectified, and smoothed via an amplifier AP, a diode D, and a capacitor C, and is input to sample-and-hold circuits IOA and IOB, respectively. It has become so. Furthermore, the outputs of the sample-and-hold circuits 10A and IOB are compared by a comparator CP, and the output of the comparator CP is applied to the terminals that control the oscillation cycles of the oscillators 5A and 5B of the oscillation/drive sections 7A and 7B. It is now possible to Note that the sample timing in the sample-and-hold circuit 10A and IOB is determined by a timing circuit 9 connected to the output side of the oscillator 8.
This is done by A and 9B. In addition, the third
The figure shows a sample-and-hold circuit 10A, an integrated circuit suitable for configuring an IOB (for example, T L 1.591
) is the internal configuration of

Next, the operation will be explained. Two sets of oscillation/drive sections 7A,
7B, the resonant frequency of the vibrator XI.

A frequency f that approximates and has a certain frequency difference from each other
,,f, alternately excites the oscillator X1 at a predetermined period determined by the oscillator 8, and the oscillator
, is detected by the vibration sensor X2, the amplitude values for each period are held in the sample-and-hold circuits 10A and 10B, and the values are compared by the comparator CP, and the oscillation/drive unit 7A, Adjust the oscillation frequency of oscillators 5A and 5B of 7B.

Figure 4 shows the relationship between the excitation frequency and the amplitude of the vibrator X1, and shows the characteristic that a peak occurs near the resonance frequency f. f0 is the oscillation/drive section 7A.

In the state located between the oscillation frequencies f and fz of 7B,
The values held in the sample-and-hold circuit 10A,] and OB will be almost the same, the output of the comparator CP will not change, and the oscillation frequency will be maintained as it is, assuming that it is appropriate. The frequency f is the oscillation/drive section 7
A, 7B oscillation frequency r.

When f is higher than f, the value held in the sample-and-hold circuit 10B becomes larger than the value held in the sample-and-hold circuit 10A, and as a result, the output of the comparator CP changes in one direction, It works to raise the oscillation frequency f, r of the oscillation/drive sections 7A, 7B, and conversely, as shown in (c), the resonance frequency "." is higher than the oscillation frequency f, fa of the oscillation/drive sections 7A, 7B. In the low state, the value held in the sample-and-hold circuit 10A becomes larger than the value held in the sample-and-hold circuit OB, and as a result, the output of the comparator CP is in the opposite direction to that at the time of ψ. The oscillation/drive section 7A changes to
, 7B to lower the oscillation frequencies r, , f.

Due to this operation, the resonant frequency f of the vibrator Xl is always
0 can be performed, and if the resonant frequency of the vibrator X1 shifts, the excitation efficiency will decrease or
This will prevent I from destroying it.

In addition, as a specific numerical value, the resonance frequency r.

is 50 k fiz, the oscillation frequency r, , r,
It has been experimentally confirmed that a frequency difference Δf of 50 to 200 Hz and a period of 10 to 20 m5 for the oscillator 8 are appropriate, but the frequency difference is not limited thereto.

(Effects of the Invention) According to the present invention as described above, two sets of oscillating/driving sections are provided, and the vibrator is alternately excited at a frequency close to the resonant frequency of the vibrator with a certain frequency difference, Since the oscillation frequency is adjusted by detecting the amplitude of the vibrator in each case, it is possible to always perform excitation that follows the resonant frequency of the vibrator, and when the resonant frequency of the vibrator shifts, This has the effect of preventing the excitation efficiency from decreasing and the vibrator from being destroyed.

[Brief explanation of the drawing]

Figure 1 is an example of an ultrasonic oscillator used in the present invention,
FIG. 3 is a configuration diagram of an ultrasonic oscillator according to the present invention, FIG. 3 is an example of the internal configuration of a sample-and-hold integrated circuit, and FIGS. 4 and 5 are operation explanatory diagrams. Xl...Resonator Q, Q□...MOS-FET IA, IB...Driver 2A, 2B...Photocoupler 3...Conversion circuit 4... ...Oscillators 5A, 5B...Oscillators 6A, 6B...Amplifiers 7A, 7B...Oscillation/drive section 8...Oscillators 9A, 9B...Timing circuit 10A, IOB...・Sample and hold circuit X2
... Vibration sensor AP ... Amplifier D ... Diode C ... Capacitor CP ... Comparator patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Michi Takayama, husband (1 other person) Figure 1

Claims (1)

[Claims] A first and a second oscillator that oscillate at a frequency that approximates the resonant frequency of the oscillator with a certain frequency difference, and that drive the oscillator.
an oscillating/driving unit, a control unit that alternately operates the first and second oscillating/driving units at a predetermined period, and a detection unit that detects the vibration of the vibrator to obtain a signal indicating the magnitude of the amplitude. Department and
Compare the outputs of the first and second holding sections with first and second holding sections that hold the outputs of the detection section corresponding to the operating periods of the first and second oscillation/drive sections. and a comparison section that adjusts the oscillation frequencies of the first and second oscillation/drive sections according to the comparison results.