JPH0573155A - Drive control circuit for ultrasonic vibrator - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a drive control circuit for an ultrasonic transducer capable of continuously and variably controlling the frequency output over a relatively wide range. [Structure] An oscillator circuit 2 for driving an ultrasonic oscillator 1 and an output adjusting circuit 3 for adjusting the output of the oscillator circuit 2 for the oscillator are provided. The ultrasonic transducer 1 is equipped with a frequency detection sensor 4 that detects the output frequency of the ultrasonic transducer 1. Ultrasonic oscillator 1 for oscillator circuit 2
A frequency variable setting circuit 5 for the use is additionally provided. The frequency variable setting circuit 5 has a frequency variable setting function for continuously variably setting the oscillation frequency of the oscillator circuit 2 according to the output of the frequency detection sensor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator drive control circuit, and more particularly to an ultrasonic vibrator drive control circuit suitable for ultrasonic processing machines such as ultrasonic welders.

[0002]

2. Description of the Related Art Conventionally, various different types of ultrasonic oscillator frequency output control have been developed according to the intended use. Most of these adopt a switching method of switching in stages, and are used in various fields as effective ones.

[0003]

However, in the above prior art, since the output control is stepwise,
There has been an inconvenience that the range of use is limited and the control range for output control is narrow.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a drive control circuit for an ultrasonic transducer, which is capable of improving the disadvantages of the conventional example and continuously and variably controlling the frequency output over a relatively wide range. Is the purpose.

[0005]

According to the present invention, an oscillator circuit for driving an ultrasonic oscillator and an output adjusting circuit for adjusting the output of the oscillator circuit are provided. The ultrasonic transducer is equipped with a frequency detection sensor that detects the output frequency of the ultrasonic transducer. The oscillator oscillating circuit is provided with a frequency variable setting circuit for the ultrasonic oscillator, and this frequency variable setting circuit continuously changes the oscillation frequency of the oscillator oscillating circuit according to the output of the frequency detection sensor. It is configured to have a variable frequency setting function for variably setting. This aims to achieve the above-mentioned object.

[0006]

The adjustment of the vibration amplitude and frequency of the ultrasonic vibrator 1 will be described. First, the output adjustment circuit 3 is operated to send the square wave output to the oscillator oscillation circuit 2, and each unit is adjusted so that the oscillator oscillation circuit 2 performs a predetermined operation. Next, selectively connect the CR oscillator 11 for test,
To set the oscillation frequency f _o, for example 40 [KH _Z]. At the same time, each part of the output adjusting circuit 3 is adjusted so that the oscillator circuit 2 for the oscillator performs a predetermined operation.

[0007] Next, by small increase or decrease the oscillation frequency f _o of the CR oscillator 11, for adjusting the output V _G of the control voltage circuit 53 as the vibrator oscillation circuit 2 is always tuned to the oscillation frequency f _o. Then, after the above adjustment is completed, the changeover switch 10 is connected again to the original frequency detection sensor 4 side,
Set the entire device to the driven state. The amplitude of the ultrasonic transducer 1 is adjusted by the reference voltage value output from the reference value setting circuit 31A in the output adjusting circuit 3 as described above.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The embodiment shown in FIGS. 1 to 4 includes an oscillator circuit 2 for driving an ultrasonic oscillator 1;
An output adjustment circuit 3 that adjusts the output of the oscillator circuit 2 is provided. The ultrasonic transducer 1 is equipped with a frequency detection sensor 4 that detects the output frequency of the ultrasonic transducer 1. The oscillator oscillating circuit 2 is provided with a frequency variable setting circuit 5 for the ultrasonic oscillator 1, and the frequency tunable setting circuit 5 operates in accordance with the output of the frequency detection sensor 4 for the oscillator oscillator circuit 2. It is configured to have a frequency variable setting function that continuously variably sets the oscillation frequency.

The output of the frequency detecting sensor 4 is input to the output adjusting circuit 3 via the changeover switch 10. The change-over switch 10 is equipped with a CR oscillator 11 for outputting a sine wave of a predetermined frequency for testing at the other terminal.

More specifically, the ultrasonic transducer 1
In this embodiment, the PZT element having the capacitance C ₀ is used as the basic tone. Further, the oscillator circuit 2 for the oscillator has a capacitance C _0.
The resistor R ₀ , the fixed inductance L, and the variable inductance L _ie are connected in series to the PZT element. Then, an output pulse of a predetermined cycle of the oscillator circuit 2 for a vibrator is applied to the resistor R ₀ .

The output adjustment circuit 3 is a rectifier 31 for rectifying a predetermined frequency signal sent from the frequency detection sensor 4.
And a comparison amplifier 32 that compares the output of the rectifier 31 with a predetermined reference value (output of the reference value setting circuit 31A) and amplifies and outputs the same, and a Schmitt circuit 33 that converts an input signal into a square wave. A differential circuit 34 that differentiates the output of the Schmitt circuit 33 and a sawtooth signal oscillating circuit 25 based on the output of the differential circuit 34 are provided. Further, the output adjustment circuit 3 includes a comparison circuit 36 for pulse-width modulating the output of the comparison amplifier 32 based on the output of the sawtooth signal oscillation circuit 35, and controls the switching transistor to be turned on / off by the output signal. Causes the output of the DC power supply Vs to have a predetermined duty cycle and a transformer T ₁
It is configured to be applied to the above-described oscillator circuit 2 for a vibrator via the.

That is, the duty cycle of this square wave applied to the output adjusting circuit 3 is controlled by the voltage obtained from the ultrasonic transducer 1 via the frequency detecting sensor 4 as described above. Further, the amplitude control of the square wave is performed by the reference value setting circuit 31 provided in the comparison amplifier 32.
The output level of A is used.

[0013] frequency variable setting circuit 5 is specifically a two Bafaanpu G _1, G ₂ which are connected in series via the resistance element R ₁ shown in FIG. 3, the output stage of the resistance element R ₁ Equipped control field effect transistor (hereinafter,
(Referred to as “FET”) 51, a control voltage circuit 5A for outputting a predetermined control voltage V _G input to the gate of the FET 51, and a secondary of a transformer T connected to the positive input terminal of _one buffer amplifier G _1. And a side coil L ₂ .
The output of the other buffer amplifier G ₂ described above is input to the positive input terminal of the _one buffer amplifier G ₁ via the coil 52 of the inductance component L ₀ . Further, the control voltage circuit 5A is equipped with an F-V conversion circuit 5B for converting the output of the frequency detection sensor 4 described above into a corresponding predetermined voltage value at its signal input stage.

The symbol L _ie indicates the inductance component of the entire coil as seen from the primary side of the transformer T. Also, the symbol V _G
Indicates the output of the control voltage circuit 5A.

Here, in the circuit shown in FIG. 3, the magnitude of the inductance component L _{ie of the} entire coil viewed from the primary side of the transformer T can be freely variably set by the output V _G of the control voltage circuit 5A. Will be explained.

First of all, the total gain G of the two buffer amplifiers G ₁ and G ₂ is G = R ₂ / (R ₁ + R ₂ ) ... where R ₂ is the drain (D) of the field effect transistor 51. The internal resistance r _DS between the source and the source (S) is shown. Then, due to this G, the inductance component L ₀ of the coil 52
By the boot straps, effective inductance L _i as seen from the input side of the G _{1 is, L i = L 0 / (} 1 over G) ..................... If you assign a formula to formula, L _i = L ₀ [1+ (R ₂ / R ₁ )] ...

Next, when the effective inductance L _i is connected to the secondary side of the transformer T, the effective inductance L _ie seen from the primary side is L _ie = L _1- [M ² / (L _i + L ₂ )] = L ₁ [L _i / (L _i + L ₂ )] ... where L ₁ and L ₂ indicate the inductances of the primary and secondary sides of the transformer T, and M is the primary and secondary sides of the transformer T. The mutual inductance between the sides is shown. Further, the coupling between the primary side and the secondary side of the transformer T is set to be thin, the coupling coefficient is set to “k = 1”, and the relation of M ² = L ₁ · L ₂ is used.

Then, from the equation, L _ie / L ₁ = 1 / [1+ (L ₂ / L _i )] = 1 / [1+ (L ₂ / L ₀ ) / (1 + R ₂ / R ₁ )] ... Here, if the internal resistance r _DS between the drain (D) and the source (S) of the field effect transistor 51 is used as R ₂ , then r _DS = R ₀ / [1− (V _G / V _P )] ……… V _P is the pinch-off voltage, and R ₀ is the value of r _DS when “V _G = 0”.

Then, substituting the equation into the equation,

L _ie / L ₁ = 1 / [1+ (L ₂ / L ₀ ) / (1 + r _DS / R ₁ )] = 1 / [1 + L _2/0 / {1 + R _0/1 / (1−V _G / V _P )}] …………………… is obtained. Here, L _2/0 = L ₂ / L ₀ ; R _0/1 = R
Indicates ₀ / R ₁ .

As is apparent from this equation, by changing V _G , L _ie can be changed.

4 and 5 show the experimental results _concerning V _G and L _ie when the values of the electric elements in FIG. 3 are set appropriately. The symbol K indicates a calculated value, and the symbol J indicates an experimental value.

Next, the adjustment of the vibration amplitude and frequency of the embodiment shown in FIG. 1 will be described. First, the output adjustment circuit 3
Is operated to feed the square wave output to the oscillator circuit 2 for the oscillator, and each part is adjusted so that the oscillator circuit 2 for the oscillator performs a predetermined operation. Next, the changeover switch 10 is changed over to selectively connect the CR oscillator 11 for test, and the oscillation frequency f
For example, _o is set to 40 [KH _Z ]. At the same time, each part of the output adjusting circuit 3 is adjusted so that the oscillator circuit 2 for the oscillator performs a predetermined operation.

Next, by small increase or decrease the oscillation frequency f _o of the CR oscillator 11, the oscillator for the oscillation circuit 2 is always adjust the output V _G of the control voltage circuit 5A to tune the oscillation frequency f _o. Then, after the above adjustment is completed, the changeover switch 10 is connected again to the original frequency detection sensor 4 side,
Set the entire device to the driven state. Here, the amplitude of the ultrasonic transducer 1 is adjusted by the reference voltage value output from the reference value setting circuit 31A in the output adjustment circuit 3 as described above.

[0025]

Since the present invention is constructed and functions as described above, according to the present invention, by adjusting the output voltage of the frequency variable setting circuit, the frequency output can be very easily continued over a relatively wide range. It becomes possible to variably control.Therefore, if this is applied to an ultrasonic processing machine such as an ultrasonic welder, the frequency output can be continuously and variably output over a relatively wide range according to the workpiece. Therefore, it is possible to provide an unprecedentedly superior drive control circuit for ultrasonic transducers, which can cope with various processing conditions.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a specific example of an output adjustment circuit in FIG.

FIG. 3 is a block diagram showing a specific example of a frequency variable setting circuit in FIG.

4 to 5 are graphs showing experimental results of changes in the variable inductance component L _ie of the oscillator circuit for an oscillator with respect to changes in the control voltage V _G in FIG. 3.

[Explanation of symbols]

 1: Ultrasonic transducer 2: Oscillator circuit for transducer 3: Output adjustment circuit 4: Frequency detection sensor 5: Frequency variable setting circuit 5A: Control voltage circuit 5B: F-V conversion circuit

Claims (2)

[Claims] 1. An ultrasonic oscillator drive control circuit comprising an oscillator oscillator circuit for driving an ultrasonic oscillator, and an output adjusting circuit for adjusting the output of the oscillator oscillator circuit.
The ultrasonic oscillator is equipped with a frequency detection sensor for detecting the output frequency of the ultrasonic oscillator, and the oscillator oscillating circuit is provided with a frequency variable setting circuit for the ultrasonic oscillator. An ultrasonic oscillator drive control circuit, wherein the setting circuit has a frequency variable setting function for continuously variably setting the oscillation frequency of the oscillator oscillation circuit according to the output of the frequency detection sensor. .. 2. An F-V conversion circuit for converting the detection frequency of the frequency detection sensor into a corresponding voltage by the frequency variable setting circuit, and an output of the frequency detection sensor voltage-converted by the F-V conversion circuit. The drive control circuit for an ultrasonic transducer according to claim 1, further comprising a control voltage circuit that variably sets a variable inductance component of the oscillator circuit for the oscillator using a value as a reference value.