JP3119822B2 - Discharge current supply method and discharge current supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load in a high impedance state, for example, a discharge current supply method for starting discharge between discharge electrodes and supplying a discharge current, a discharge current supply device,
Further, the present invention relates to an optical fiber fusion splicing device using the same. The present invention can be used not only for optical fiber fusion splicing but also for a device that applies a high voltage to a load and discharges, such as a dust collector, an electrostatic coating, and a discharge tube.

[0002]

2. Description of the Related Art A high voltage is required to initiate a discharge between electrodes. However, in a sustained discharge after the occurrence of dielectric breakdown and the start of the discharge, the discharge starting voltage and the discharge sustaining voltage for each cycle of the AC discharge become low.
Conventionally, in order to obtain a high voltage of several tens of kV necessary for starting the first discharge, a DC high voltage generating circuit is connected to the secondary side of the step-up transformer, and the voltage between the discharge electrodes is gradually increased to obtain a high voltage. I was Such prior art is described in IEICE Technical Report, C.
S80-188 (1980), Yoshio Kashima, Fumihiro Nihei,
"Splicing of optical fibers by high-frequency trigger method",
p. 67-72, JP-B-61-22555, JP-B-62-40948, and JP-B-2-5000.

FIG. 16 is a block diagram of the prior art.
FIG. 17 is a circuit diagram showing an example of the DC high voltage generation circuit diagram shown in FIG. FIG. 18 is a waveform diagram schematically showing a voltage waveform between discharge electrodes and a discharge current waveform. In the figure, 2 is a capacitor, 3 is a discharge electrode, 20 is a DC power supply,
22 is a transformer, 24 and 25 are switching transistors, 26 and 27 are diodes, 80 is a DC high voltage generation circuit, 81 is a high resistance for charging, 91 and 92 are diodes, 9
3 is a capacitor, 100 is a voltage waveform between discharge electrodes, 10
1 is a discharge current waveform.

[0004] The DC power supply 20 has an emitter terminal of a pair of switching transistors 24 and 25 and one of the transformers 22.
Connected to the center tap on the next side. The collector terminals of both transistors 24 and 25 are connected to transformer 22 respectively.
Are connected to the terminals at both ends of the primary side. Both transistors 2
Diodes 26 and 27 are connected in anti-parallel between the collector and emitter terminals of 4, 25, respectively. Transformer 22
Are connected to the discharge terminal 3 via the capacitor 2
Is connected, and the DC high-voltage generation circuit 80 is also connected. One terminal of a high-resistance resistor 81 is connected to the DC high-voltage generating circuit 80, and the other terminal of the high-resistance resistor 81 is connected to a connection point between the capacitor 2 and the discharge electrode 3. A drive driver (not shown) is connected to each base terminal of both transistors 24 and 25.

[0005] 20 kHz to 40 kHz via a driver
When the switching transistors 24 and 25 are alternately turned on and off at a frequency in the range of z, for example, a high frequency equivalent to 20 kHz, an AC voltage is generated on the secondary side of the transformer 22. Since the discharge electrode 3 is in a high impedance state before the start of discharge, no discharge current flows. However, during this time, the DC high-voltage generating circuit 80 receives the AC voltage, applies a DC voltage to both ends of the capacitor 2 via the charging high-resistance 81, causes a minute current to flow through the capacitor 2, and causes 10 to several dozen cycles. The capacitor 2 is charged over the period. At this time, the voltage waveform 100 between the discharge electrodes in FIG. 18 rises stepwise.

A multiple voltage rectifier is used as the DC high voltage generating circuit 60. The above-mentioned Japanese Patent Publication Sho 62-4094
FIG. 4 of Japanese Patent Publication No. 8 discloses a specific circuit of a DC high voltage generating circuit as shown in FIG. An anode terminal of a diode 91 is connected to a connection point between one terminal on the secondary side of the transformer 22 shown in FIG. 16 and the capacitor 2, and one terminal of the capacitor 93 and an anode terminal of the diode 92 are connected to this cathode terminal. The other terminal of the capacitor 93 is connected to the second terminal of the transformer 22 shown in FIG.
This circuit is connected to the other terminal on the next side, and the cathode terminal of the diode 92 is connected to the charging high resistance 81 shown in FIG.

[0007] By charging the capacitor 2, the transformer 22
When the sum of the secondary side output voltage and the charging voltage of the capacitor 2 exceeds the trigger voltage between the discharge electrodes 3, that is, the first discharge start voltage, the dielectric breakdown occurs as shown in a voltage waveform 100 between the discharge electrodes in FIG. Is generated to start a discharge, a gas discharge is generated between the discharge electrodes 3, and a discharge current starts to flow as shown in a discharge current waveform 101 in FIG. Once the discharge is started, the discharge is performed every half cycle of the AC voltage at a voltage significantly lower than the initial discharge start voltage. At this time, a series resonance current flows from the transformer 22 through a series circuit of the leakage inductance component of the transformer 22 and the capacitor 2.

When the discharge current supply device is used as a fusion splicing device for optical fibers, fusion splicing of optical fibers is performed using energy generated by air discharge between the discharge electrodes 3. Adjust the set value of the discharge current, for example, when removing the coating material of the optical fiber, reduce the discharge current and heat at a relatively low temperature, and when performing fusion splicing, increase the discharge current. Thus, heating at a relatively high temperature becomes possible.

As described above, in the conventional discharge current supply device, in order to start the discharge, the DC high voltage generating circuit 80 is used.
And the discharge circuit itself is complicated and large.

[0010] In addition, regarding the adjustment and stabilization of the discharge current, the above-mentioned article describes that pulse width control and control by a dropper method were performed. On the other hand, Japanese Patent Publication No. 62-40948 discloses that the discharge current is adjusted by changing the conduction period of the switching transistor, feedback is performed based on the integrated value of the discharge current, and the discharge current is controlled by controlling the conduction period. Is described as stabilizing.

However, there has been a problem that it is difficult to adjust and stabilize the discharge current over a wide range. In the case of using a DC-DC converter,
There is a problem that the number of parts is increased, such as the necessity of a transformer for a converter, and the scale of the device is increased.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple and small-scale discharge current supply method and a discharge current generation method for generating a dielectric breakdown and starting discharge. It is an object of the present invention to provide a current supply device and an optical fiber fusion splicing device using the same.

[0013]

According to a first aspect of the present invention, an AC output of an AC voltage generator having a series resonance circuit in which an inductance element and a capacitance element are connected in series in an equivalent circuit is connected to a capacitor in series. In the method of supplying a discharge current supplied to a connected discharge electrode, the frequency of the AC voltage is set to a series resonance frequency of the series resonance circuit or a frequency in the vicinity thereof such that breakdown occurs between the discharge electrodes and discharge is started. The AC output of the AC voltage generator causes an insulation breakdown between the discharge electrodes to start the discharge, and controls the discharge current by changing the frequency of the AC voltage after the start of the discharge. Things.

According to a second aspect of the present invention, in the method for supplying a discharge current according to the first aspect, the AC voltage generating section comprises:
A DC power source is switched by a drive pulse to generate an AC voltage, and the discharge current is controlled by changing the drive frequency of the drive pulse after the start of discharge and changing the frequency of the AC voltage. It is.

According to a third aspect of the present invention, in the discharge current supply method according to the second aspect, the discharge current is controlled by changing the pulse width of the drive pulse after the start of the discharge. is there.

According to a fourth aspect of the present invention, there is provided the discharge current supply method according to any one of the first to third aspects,
The AC output of the AC voltage generator is clamped and supplied to the discharge electrode in a high impedance state.

According to a fifth aspect of the present invention, in the discharge current supply method according to any one of the first to third aspects,
An AC output of the AC voltage generator is supplied to the discharge electrode in a high impedance state via a high resistance.

According to a sixth aspect of the present invention, there is provided a discharge current supply method according to any one of the first to fifth aspects,
Supplying the AC output of the AC voltage generator to the discharge electrode having a resistor connected in series via the capacitor, and changing the resistance value of the resistor to change the internal impedance of the circuit as viewed from the discharge electrode. It is characterized by the following.

According to a seventh aspect of the present invention, there is provided a method for supplying a discharge current according to any one of the first to sixth aspects,
By setting the frequency of the AC voltage to the series resonance frequency or a frequency close to the series resonance frequency, the dielectric breakdown occurs and the discharge is started.

According to an eighth aspect of the present invention, in the discharge current supply method according to any one of the first to sixth aspects,
By changing the frequency of the AC voltage so as to approach the series resonance frequency, the dielectric breakdown is generated and the discharge is started.

According to a ninth aspect of the present invention, in the discharge current supply method according to the eighth aspect, the frequency of the AC voltage is changed from a frequency higher than the series resonance frequency to approach the series resonance frequency. This causes the dielectric breakdown to occur, and the discharge is started.

According to a tenth aspect of the present invention, an AC output of an AC voltage generator having a series resonance circuit in which an inductance element and a capacitance element are connected in series in an equivalent circuit is supplied to a discharge electrode in which a capacitor is connected in series. In the discharge current supply device, the frequency of the AC voltage is set to the series resonance frequency of the series resonance circuit or a frequency in the vicinity thereof such that breakdown occurs between the discharge electrodes and discharge is started. An AC output of the generating unit causes a dielectric breakdown between the discharge electrodes to start a discharge, and further includes a control unit that controls a discharge current by changing a frequency of the AC voltage after the start of the discharge. It is.

According to an eleventh aspect of the present invention, in the discharge current supply device according to the tenth aspect, the AC voltage generator generates an AC voltage by switching a DC power supply by a drive pulse. The control unit controls the discharge current by changing the drive frequency of the drive pulse after the start of the discharge and changing the frequency of the AC voltage.

According to a twelfth aspect of the present invention, in the discharge current supply device of the eleventh aspect, the control unit controls the discharge current by changing the pulse width of the drive pulse after the start of the discharge. It is a feature.

According to a thirteenth aspect of the present invention, in the discharge current supply device according to any one of the tenth to twelfth aspects, the output of the AC voltage generating section is clamped to the discharge electrode in a high impedance state. It has a supply means.

According to a fourteenth aspect of the present invention, in the discharge current supply device according to the thirteenth aspect, a unidirectional conduction circuit is connected in parallel with the discharge electrode.

According to a fifteenth aspect of the present invention, in the discharge current supply device according to the fourteenth aspect, the unidirectional conduction circuit has a series connection circuit of a diode and a resistor. .

According to a sixteenth aspect of the present invention, in the discharge current supply device according to any one of the tenth to twelfth aspects, a high-resistance bypass resistor is connected in parallel to the capacitor. It is.

According to a seventeenth aspect of the present invention, in the discharge current supply device of the sixteenth aspect, there is provided a means for disconnecting the bypass resistor from at least one terminal of the capacitor after the start of discharge. is there.

According to an eighteenth aspect of the present invention, in the discharge current supply device according to any one of the tenth to seventeenth aspects, the AC voltage generator has a step-up transformer. .

According to a nineteenth aspect of the present invention, in the discharge current supply device according to any one of the tenth to eighteenth aspects, the output of the AC voltage generating section has a resistor connected in series via the capacitor. It is connected to the discharge electrode, and the internal impedance of the circuit viewed from the discharge electrode changes due to the variable resistance value of the resistor.

According to a twentieth aspect of the present invention, in the discharge current supply device according to the nineteenth aspect, the resistor comprises one or a plurality of resistors, and on-off switch means is connected to both ends of at least one of the resistors. It is characterized by that.

According to a twenty-first aspect of the present invention, in the discharge current supply device according to any one of the tenth to twentieth aspects, the frequency of the AC voltage is set to the series resonance frequency or a frequency near the series resonance frequency. This causes the dielectric breakdown to occur, and the discharge is started.

According to a twenty-second aspect of the present invention, in the discharge current supply device according to any one of the tenth to twenty-first aspects, the frequency of the AC voltage changes so as to approach the series resonance frequency. The discharge is started by causing the dielectric breakdown.

According to a twenty-third aspect of the present invention, in the discharge current supply device according to the twenty-second aspect, the frequency of the AC voltage changes from a frequency higher than the series resonance frequency to approach the series resonance frequency. This causes the dielectric breakdown to occur, and the discharge is started.

According to a twenty-fourth aspect of the present invention, there is provided an optical fiber fusion splicing apparatus for fusion splicing an optical fiber by air discharge generated between discharge electrodes.
It has the discharge current supply device of any one of the above, It is characterized by the above-mentioned.

According to a twenty-fifth aspect of the present invention, there is provided an optical fiber fusion splicing apparatus for fusion splicing an optical fiber by air discharge generated between discharge electrodes.
A discharge current supply device according to any one of (1) to (3).

[0038]

[0039]

[0040]

According to the first aspect of the present invention, a discharge electrode in which an AC output of an AC voltage generator having a series resonance circuit in which an inductance element and a capacitance element are connected in series in an equivalent circuit is connected to a capacitor in series. In the method of supplying a discharge current supplied to the AC power supply, a frequency of an AC voltage is set to a series resonance frequency of the series resonance circuit or a frequency near the same so that a dielectric breakdown occurs between the discharge electrodes and a discharge is started. Since the AC output of the voltage generating section causes dielectric breakdown between the discharge electrodes to start the discharge, it is not necessary to add a complicated configuration, and the discharge can be easily started with a simple configuration. Since the discharge is started at the resonance frequency at the time of no load, the discharge start state is stabilized. Further, since the discharge current is controlled by changing the frequency of the AC voltage after the start of the discharge, the input voltage allowable range of the power supply and the settable range of the discharge current are widened.

According to the second aspect of the present invention, the AC voltage generating section generates an AC voltage by switching a DC power supply by a drive pulse, and changes the drive frequency of the drive pulse after the start of discharge. Since the discharge current is controlled by changing the frequency of the AC voltage, the allowable range of the input voltage of the power supply and the settable range of the discharge current are widened.

According to the invention of claim 3, according to claim 2,
In the invention described in the above, since the discharge current is controlled by controlling the discharge current by also changing the pulse width of the drive pulse after the start of the discharge, the input voltage allowable range of the power supply and the settable range of the discharge current are reduced. Become wider.

According to the fourth aspect of the present invention, since the output of the AC voltage generator is clamped and supplied to the discharge electrode in the high impedance state, the discharge is performed even if the power supply voltage in the AC voltage generator is relatively low. Can be started.

According to the fifth aspect of the present invention, since the output of the AC voltage generator is supplied to the discharge electrode in the high impedance state via the high resistance, the power supply voltage in the AC voltage generator is relatively low. Can also initiate a discharge.

According to the sixth aspect of the present invention, the output of the AC voltage generating section is supplied to the discharge electrode having a resistor connected in series via a capacitor, and the output of the AC voltage generator is viewed from the discharge electrode by changing the resistance value of the resistor. Since the internal impedance of the circuit is changed, the discharge current can be supplied over a wide range and stably.

According to the seventh aspect of the invention, by setting the frequency of the AC voltage to the series resonance frequency or a frequency close to the series resonance frequency, the dielectric breakdown occurs and the discharge is started. It is not necessary to add a complicated configuration, and the discharge can be started with a simple configuration.

According to the eighth and ninth aspects of the present invention, the frequency of the AC voltage is changed so as to approach the series resonance frequency, thereby causing a dielectric breakdown and starting the discharge. For example, it is not necessary to add a complicated configuration, and discharge can be started with a simple configuration.

According to the tenth aspect of the present invention, the AC output of the AC voltage generating section having a series resonance circuit in which an inductance element and a capacitance element are connected in series in an equivalent circuit is a discharge electrode in which a capacitor is connected in series. In the discharge current supply device supplied to the, the frequency of the AC voltage is set to the series resonance frequency of the series resonance circuit or a frequency in the vicinity thereof such that breakdown occurs between the discharge electrodes and discharge is started, Since the AC output of the AC voltage generating unit causes the dielectric breakdown between the discharge electrodes and starts the discharge, it is not necessary to add a complicated configuration, and the discharge can be started with a simple configuration. Since the discharge is started at the resonance frequency at the time of no load, the discharge start state is stabilized. Further, since the discharge current is controlled by changing the frequency of the AC voltage after the start of the discharge, the input voltage allowable range of the power supply and the settable range of the discharge current are widened.

According to the eleventh aspect, the AC voltage generating section switches the DC power supply by the drive pulse to generate an AC voltage, and the control section changes the drive frequency of the drive pulse to change the drive frequency. Since the discharge current is controlled by changing the frequency of the AC voltage, the allowable range of the input voltage of the power supply and the settable range of the discharge current are widened.

According to the twelfth aspect of the present invention, the control unit controls the discharge current by changing the pulse width of the drive pulse after the start of the discharge. Becomes wider.

According to the thirteenth aspect of the present invention, since there is provided means for clamping the output of the AC voltage generator and supplying it to the discharge electrode in a high impedance state, the power supply voltage in the AC voltage generator is relatively low. Discharge can also be started.

According to the fourteenth aspect of the present invention, since the unidirectional conduction circuit is connected in parallel with the discharge electrode, it can be clamped using an existing capacitor and the configuration is simplified.

According to the fifteenth aspect of the present invention, the configuration of the unidirectional conduction circuit is simplified because it has a series connection circuit of a diode and a resistor.

According to the sixteenth aspect of the present invention, since the high-resistance bypass resistor is connected in parallel to the capacitor, the discharge can be started even if the power supply voltage in the AC voltage generator is relatively low.

According to the seventeenth aspect of the present invention, since the means for disconnecting the bypass resistor from at least one terminal of the capacitor after the start of the discharge is provided, the adverse effect on the discharge can be eliminated.

According to the eighteenth aspect of the present invention, since the AC voltage generator has the step-up transformer, discharge can be started even if the power supply voltage in the AC voltage generator is relatively low.

According to the nineteenth aspect, the output of the AC voltage generator is connected to the discharge electrode having a resistor connected in series via a capacitor, and the resistance of the resistor is variable. Since the internal impedance of the circuit varies, the discharge current can be supplied over a wide range and stably.

According to a twentieth aspect of the present invention, in the discharge current supply device according to the twenty-first aspect, the resistor comprises one or more resistors, and on-off switch means is connected to both ends of at least one resistor. Therefore, the resistance value can be easily changed.

According to the twenty-first aspect, when the frequency of the AC voltage is set to the series resonance frequency or a frequency close to the series resonance frequency, dielectric breakdown occurs and discharge is started. For example, it is not necessary to add a complicated configuration, and discharge can be started with a simple configuration.

According to the invention described in claims 22 and 23,
Since the frequency of the AC voltage changes so as to approach the series resonance frequency, dielectric breakdown occurs and discharge starts, so there is no need to add a complicated configuration such as a high-voltage DC voltage, and a simple configuration is used. Discharge can be started.

According to a twenty-fourth aspect of the present invention, there is provided an optical fiber fusion splicing apparatus for fusion splicing an optical fiber by air discharge generated between discharge electrodes. According to the invention according to claim 25, since the discharge current supply device according to
An optical fiber fusion splicing apparatus for fusion splicing optical fibers by air discharge generated between discharge electrodes.
Since the discharge current supply device described in 2 or 23 is provided, the same operation as the invention described in each of the above-mentioned claims is achieved, and the optical fiber can be fusion-spliced.

[0062]

[0063]

[0064]

FIG. 1 is a schematic block diagram of a first embodiment of the present invention. FIG. 2 is a diagram illustrating the operation of this embodiment. The horizontal axis in FIG. 2 is the frequency, and the vertical axis is the output voltage at the discharge electrode. FIG. 3 is a waveform diagram schematically showing a voltage waveform between discharge electrodes and a discharge current waveform. In the figure, the same parts as those in FIG. 1 is an AC voltage generating section, 4 is a frequency switching control section, 5 is an AC power supply, 6 is an inductance element, 7 is a capacitance element, 10 is a no-load resonance characteristic, 11 is a load resonance characteristic, and 15 is a discharge electrode. Voltage waveform between 16
Is a discharge current waveform.

In FIG. 1, the inside of AC voltage generating section 1 is represented as an equivalent circuit. An inductance element 6 is connected in series to the AC power supply 5, and a capacitance element 7 is connected in parallel to the inductance element 6, and the parallel connection point simultaneously serves as an output terminal of the AC voltage generation unit 1. This output terminal is connected to the discharge electrode 3 via the capacitor 2. The AC power supply 5
The frequency can be switched by the frequency switching control unit 4.

The inductance element 6 is realized by a choke coil, but depending on the frequency of the AC power supply used,
It can be realized only by the self-inductance of the line itself. Further, when a transformer is used as described later with reference to FIG. 4, it can be realized by the leakage inductance of the transformer.
Alternatively, these may be used in combination. Further, the capacitance element 7 is realized by a capacitor, but may be realized by a stray capacitance, or may be used in combination.

The discharge electrode 3 is initially in a high impedance state before the start of discharge. Therefore, the load of the AC power supply 5 is
Substantially inductance element 6 and capacitance element 7
Only in series. Therefore, when the frequency of the AC power supply 5 is set at or near the series resonance frequency f ₁ of the inductance element 6 and the capacitance element 7 and an AC voltage is supplied, a large series voltage is applied to the output terminal of the AC voltage generation unit 1. A resonance voltage occurs. This resonance voltage is
The voltage is divided by the series connection circuit of the capacitor 2 and the discharge electrode 3 and applied to the discharge electrode 3, and the absolute value of the peak of the resonance waveform gradually increases as shown in the voltage waveform 15 between the discharge electrodes in FIG.

Before the start of discharge, as shown in the resonance characteristic 10 at no load in FIG. 2, the output voltage at the discharge electrode 3 has a peak voltage V ₁ (f ₁ ) at the series resonance frequency f ₁ at no load. Take. The voltage and circuit constants of the AC power supply 5 are set so that the dielectric breakdown occurs at and near the series resonance frequency f ₁ when no load is applied and discharge starts. When an AC voltage is supplied by setting the frequency of the AC power supply 5 to the series resonance frequency f ₁ at no load or a frequency in the vicinity thereof, several cycles of the resonance waveform elapse as shown in a voltage waveform 15 between the discharge electrodes in FIG. Thereafter, air discharge starts, and a discharge current flows as indicated by a discharge current waveform 16 in FIG. Although the discharge is started at a positive voltage in FIG. 3, the start of the discharge is not related to the voltage polarity, so that the discharge may be started at a negative voltage.

When electric discharge starts due to occurrence of dielectric breakdown,
The load between the discharge electrodes 3 is in a low impedance load state. As a result, the capacitance of the capacitor 2 is added in parallel to the capacitance element 7. Therefore, the load of the AC power supply 5 is composed of the capacitance element 7 and the capacitor 2.
Are connected in series and a series resonance circuit of the inductance element 6. Therefore, after the start of discharge, the output voltage at the discharge electrode 3 has a peak voltage V ₂ (f ₂ ) at the series resonance frequency f ₂ at the time of load, as in the resonance characteristic 11 under load in FIG. Series resonance frequency f under load
₂ is lower than the series resonance frequency f ₁ at no load.
In addition, since the discharge current flows through the discharge electrode 3, the Q of the series resonance circuit decreases, so that the peak voltage V ₂ (f ₂ ) becomes lower than the peak voltage V ₁ (f ₁ ) before the start of discharge.

When the frequency of the AC power supply 5 maintains the series resonance frequency f ₁ at no load, the output voltage V ₂ (f ₁ ) is higher than the peak voltage V ₂ (f ₂ ) as shown in FIG. Become smaller. At this time, the value of the discharge current also decreases,
If this is enough, there is no need to switch the frequency,
The frequency switching control unit 4 need not be used.

However, at the output voltage V ₂ (f ₁ ), if the value of the discharge current is smaller than the desired set value, the frequency switching control unit 4 changes the frequency of the AC power supply 5 to the series resonance under load. by switching a frequency close to the frequency f _2, it is possible to increase the discharge current. At this time,
By switching to the series resonance frequency f ₂ at the time of load,
During sustain discharge, the output voltage becomes maximum, and a large discharge current is obtained. The frequency of the AC power supply 5 is switched so that a desired discharge current is obtained. That is, the output voltage can be changed by changing the frequency, and the discharge current can be controlled. The variable range of the frequency is
Series resonance frequency f ₁ the following range when no load series resonance frequency f ₂ or more under load is suitable.

Conversely, even with the output voltage V ₂ (f ₁ ), if the discharge current is greater than the desired set value, the frequency may be switched to a higher value. However, since the resonance characteristic 11 under load has a gentle slope near the series resonance frequency f ₁ before the start of discharge, it is difficult to greatly reduce the discharge current. In such a case, the output voltage is reduced by a method such as lowering the voltage of the AC power supply 5.

As described above, the output voltage can be controlled by changing the frequency. In order to maintain the discharge, the output voltage is naturally higher than the discharge start voltage and the discharge sustaining voltage for each cycle during the continuous discharge period of the AC discharge.

To switch the frequency of the AC power supply 5, for example, two AC power supplies having different frequencies may be prepared in advance, and the AC power supply may be switched by a manual switch after the start of discharge. In this case, the start of the discharge is detected by the operator, but when the means for detecting the discharge light is used, it can be automatically detected. Alternatively, the frequency may be switched by detecting that a predetermined time has elapsed after turning on the AC power by using a timer.

As the AC voltage generating section 1, a switching transistor can be used as in the prior art described with reference to FIGS. 16 to 18, and the start of discharge can be detected by detecting a discharge current. . An embodiment having such a specific means will be described below.

FIG. 4 is a block diagram of a second embodiment of the present invention. In the figure, the same parts as those in FIG. 16 and FIG. 21 is a switching unit and 23 is an oscillation unit. This embodiment is different from the first embodiment described with reference to FIGS.
1 illustrates an AC voltage generator 1. By switching the frequency of the drive pulse for driving the switching transistors 24 and 25, the frequency of the AC voltage is switched, and the AC voltage is boosted by the transformer 22.

The DC power supply 20, switching unit 21, transformer 22, and oscillating unit 23 correspond to the AC voltage generating unit 1 in FIG. FIG. 4 shows only the capacitance element 7, but the inductance element 6 in FIG.
2, and the capacitance element 7 is realized by the stray capacitance of the transformer 22. Of course, a desired resonance characteristic may be obtained by adding a choke coil and a capacitor.

The switching section 21 intermittently turns on and off the DC power supply 20 at the frequency of the driving pulse from the oscillation section 23 to convert the DC power supply 20 into an AC voltage, and boosts the voltage through the transformer 22.
An AC voltage is supplied to a series circuit of the capacitor 2 and the discharge electrode 3.

That is, the oscillation section 23 generates a pulse signal. The drive frequency of this pulse signal is controlled by the frequency switching control unit 4. The pulse signals are alternately input from the oscillation unit 23 to the base terminals of the switching transistors 24 and 25,
5 is driven according to the input pulse signal. When the switching transistor 24 turns on the current to one of the primary windings divided by the center tap in accordance with the pulse signal, the switching transistor 25 is turned on by the oscillating unit 23. The current to the other side of the winding is turned off, and this operation is repeated alternately. As will be described later, when performing pulse width control, there is a period in which both switching transistors 24 and 25 are both off.

The ON / OFF operation is repeated in response to the pulse signal output from the oscillation section 23. As a result, an AC voltage is supplied to the primary side of the transformer 22. This AC voltage is boosted by the transformer 22. The secondary winding of the transformer 22 is connected to the discharge electrode 3 via the capacitor 2.
Is connected to the other end of the discharge electrode 3, and the boosted AC voltage is supplied to the discharge electrode 3 via the capacitor 12.

The frequency switching control by the frequency switching control unit 4 before the start of discharge will be specifically described with reference to FIGS. 5 to 7. FIG. 5 is a waveform diagram of an example of an output pulse signal of the oscillation unit shown in FIG. The horizontal axis in FIG. 5 is time, and the vertical axis is voltage. FIG. 6 is a diagram illustrating the operation when the waveform of FIG. 5 is used. The horizontal axis in FIG. 6 is the frequency, and the vertical axis is the output voltage at the discharge electrode. FIG.
FIG. 3 is a waveform diagram illustrating an outline of a voltage waveform between discharge electrodes and a discharge current waveform.

The frequency switching control section 4 gives a discharge start command to the oscillation section 23 of FIG. 4 at time t ₀ as shown in FIG. As shown in FIG. 5, the driving frequency of the pulse signal outputted from the oscillation section 23, from f _H, it decreases toward the frequency f ₁ at a certain predetermined change characteristic. At the same time, the pulse width of the pulse signal output from the oscillator 23 also increases from zero to a predetermined pulse width with another predetermined change characteristic. The above-mentioned change characteristic is, for example, that the capacitor C
It can be realized by controlling the drive frequency of the pulse signal and the pulse width of the pulse signal with the output of the time constant circuit including the resistor R and the resistor R.

[0083] the driving frequency of the pulse signal is initially relatively higher than f _H, as the gradually over time, f from f _H
So that close to the f ₁ through _M. At the same time, the pulse width of the pulse signal is initially zero, and gradually increases from zero toward a predetermined pulse width over time. As a result, in FIG.
After = 0, the absolute value of the voltage peak value between the discharge electrodes 3 gradually increases. Peak voltage value between the discharge electrodes, the series resonance frequency f ₁ or the vicinity, discharge starts when it reaches the peak voltage level. The period from the output of the discharge start command to the start of the discharge is about 1 to 100 ms as shown in FIG.

Note that at least one of the driving frequency and the pulse width of the pulse signal may be changed as described above. Further, instead of continuously changing, discrete discrete values may be gradually changed. After the start of the discharge, at least one of the drive frequency and the pulse width of the pulse signal is controlled, and adjusted to control the discharge current flowing between the discharge electrodes.

In the first embodiment described with reference to FIG. 1 to FIG. 3, the dielectric breakdown occurs at and near the series resonance frequency f ₁ at the time of no load, and the discharge is started.
After having set the voltage and circuit constants of the AC power supply 5, and the frequency of the AC power source 5 before the start of discharge was set to a frequency of the series resonance frequency f ₁ or the vicinity of the no-load. Also in this embodiment, the frequency of the AC power supply 5 before the start of discharge can be set in the same manner.

However, as described with reference to FIGS. 5 to 7, by controlling the driving frequency and the pulse width of the pulse signal before the start of the discharge, the voltage fluctuation of the AC power supply 5 and the surrounding area where the discharge is performed are controlled. less affected by such changes in the environment, ensures breakdown will be able to start it occurs discharge at the series resonance frequency f ₁ and the vicinity of the no-load. Further, the AC power supply 5 before the start of discharge
Is changed from a frequency higher than the no-load series resonance frequency f ₁ so as to approach, and the connection with the current control after the start of discharge having the under-load series resonance frequency f ₂ is good.

The output pulse signal of the oscillating unit shown in FIG. 5 corresponds to the switching transistors 24 and 2 shown in FIG.
5 is an output pulse signal input to one base terminal, and the other base terminal outputs a similar output pulse signal shifted by a half cycle of each pulse cycle during a low level period of the output pulse signal. .

As a concrete means of the switching section 21,
Various configurations can be employed. The illustrated one uses the conventional switching transistors 24 and 25 described with reference to FIG. 16 and is connected to a transformer 22 having a center tap. In addition, a half-bridge type inverter configuration described in Japanese Patent Publication No. 61-22555 cited as a prior art, a configuration using a reverse conducting thyristor for a switching element, and a Japanese Patent Publication No. Sho 62-40 are disclosed.
No. 948 discloses a half-wave inverter configuration.

The switching unit 21 shown in FIG.
A self-excited type in which on / off control is performed by a drive signal supplied from the switching unit 21 is not necessary, and the oscillation unit 23 is not required, and a switching frequency is autonomously determined inside the switching unit 21. The switching transistors 24 and 25 are merely examples as switching elements, and FETs are also suitable.

Note that, depending on the specific configuration of the switching unit 21, the configuration of the transformer 22 may need to be slightly changed, for example, without a center tap or having an auxiliary winding. Although a step-up transformer is used as the transformer 22, the transformer 22 may be omitted when a voltage required for discharging is immediately obtained in the switching unit 21 and the transformer is not required for performing the switching operation. .

As the oscillating section 23, an unstable multivibrator whose oscillation frequency is determined by the product of the resistance value and the capacitance value can be used, and two capacitors having different capacitance values are switched or two resistors having different resistance values are switched. The oscillation frequency can be switched by switching. Also,
A voltage-controlled oscillation circuit (VCO) can be used, and the frequency of the oscillation section can be switched by switching the control voltage.

In the second embodiment, the driving pulse output from the oscillating section 23 is subjected to pulse width modulation (PW
In the case of the M) signal, since the output voltage can be changed by changing the pulse width, in other words, the duty ratio, the discharge current can also be adjusted by changing the duty ratio. In particular, when the output voltage is V ₂ (f ₁ ) and the discharge current value is still larger than the desired set value, the discharge current can be further reduced by reducing the duty ratio.

FIG. 8 is a block diagram of the third embodiment of the present invention. In the figure, the same parts as those in FIG. 16, FIG. 1, and FIG. Reference numeral 30 denotes a current detection unit. In this embodiment, a current detector 30 for detecting the start of discharge is provided in the second embodiment described with reference to FIG.

The current detecting section 30 comprises a secondary terminal of the transformer 22 which is grounded and to which the capacitor 2 is not connected, and a discharge electrode 3 which has an electrode to which the capacitor 2 is not connected. And the discharge electrode 3
The current flowing through is detected. When the discharge is started due to the occurrence of dielectric breakdown, a discharge current flows. Therefore, the frequency switching control unit 4 detects, for example, that the absolute value of the detected current has exceeded a predetermined value, and The frequency is switched so that the discharge current has a desired set value. Therefore,
The start of discharge can be automatically detected. The current detection unit 30 can be realized, for example, by rectifying and smoothing a voltage applied to a resistor having a small resistance value.

The operation from the start of discharge to the continuous discharge and the setting operation of the discharge current value during the continuous discharge are described in FIG.
1 to 3 according to the first embodiment described with reference to FIGS.
The operation is the same as that of the second embodiment described with reference to FIG.

FIG. 9 is a block diagram of a fourth embodiment of the present invention. In the figure, the same parts as those in FIGS. 16, 1, 4, and 8 are denoted by the same reference numerals, and description thereof is omitted. 35 is a control unit. This embodiment is obtained by expanding the function of the frequency switching control unit 4 in the third embodiment described with reference to FIG. 8, and also performing feedback control of the discharge current. The control unit 35 is illustrated.

The control section 35 sets the oscillation frequency of the oscillating section 23 to be at or near the series resonance frequency f ₁ at no load as long as no discharge current is detected. In a state where the discharge current is detected, the frequency or the pulse width of the pulse width modulation (PWM) type driving pulse output from the oscillation unit 23 is controlled so that the value of the discharge current becomes a desired set value. .

When the discharge current starts to be detected, if the discharge current is smaller than the set value, the frequency of the drive pulse is reduced, and is changed so as to approach the resonance frequency f ₂ at the time of load. As a result, the output voltage increases, so that the discharge current increases and approaches the set value. When the set value is exceeded, the frequency of the drive pulse is increased, and consequently, the output voltage decreases, so that the set current is maintained.

When the discharge current when the discharge current starts to be detected is larger than the set value, the pulse width of the drive pulse is narrowed, in other words, the duty ratio is reduced. As a result, the energy supplied to the secondary side decreases, so that the discharge current decreases and approaches the set current. When the discharge current falls below the set value, the width of the drive pulse is increased, consequently, the energy supplied to the secondary side increases, and the set current is maintained. It is desirable that the pulse width of the driving pulse be set to be about 50% in the maximum width and the duty ratio before and after the start of the oscillation.

The feedback by the above-described frequency / pulse width control is performed by using the control unit 35, whereby
In addition to setting the frequency of the drive pulse to the frequency required for starting the discharge, it is possible to control the discharge current to be constant.

When a battery is used as the DC power supply 20, the output of the DC power supply decreases with use time.
There is a possibility that operating characteristics may change or a desired discharge current may not be obtained. Therefore, the voltage of the DC power supply 20 may be detected, and the pulse width of the drive pulse may be made closer to the maximum width according to the decrease in the voltage. Such a measure for reducing the output of the DC power supply can be applied to the second embodiment described with reference to FIG.

In the third and fourth embodiments described above, the setting of the discharge current value, the discharge current setting and the discharge are performed on the premise of the configuration of the first and second embodiments described with reference to FIGS. The current feedback control and the like have been described. However, even if the circuit has an AC voltage generating section having a series resonance characteristic as in the prior art described with reference to FIGS. 16 to 18, if the series resonance frequency of this circuit is f ₂ , the series The resonance characteristic is the same as the resonance characteristic 11 under load in FIG. Therefore, by the same frequency control and pulse width control, the setting of the discharge current value and the feedback control of the discharge current can be performed. In this case, the frequency of the driving pulse is f ₂ before the start of discharge.
Alternatively, it is desirable to set in the vicinity.

Also, the configuration of the first and second embodiments described with reference to FIGS. 1 to 7 can be changed.
This will be described below. However, even on the premise of the following embodiment, the setting of the discharge current value described with reference to FIGS.
Feedback control of the discharge current is possible.

FIG. 10 is a schematic configuration diagram of a fifth embodiment of the present invention. FIG. 11 is a waveform diagram schematically showing a voltage waveform between discharge electrodes and a discharge current waveform. In the figure, the same parts as those in FIG. 16 and FIG. 40 is a diode, 41 is a resistor, 45 is a voltage waveform between discharge electrodes, and 46 is a discharge current waveform. A series circuit of a diode 40 and a resistor 41 is connected in parallel with the discharge electrode 3 in the first embodiment described with reference to FIG. The series circuit of the capacitor 2 and the diode 40 and the resistor 41 forms a clamp circuit.

The discharge electrode 3 is initially in a high impedance state before the start of discharge. Further, the resistor 41 is a current limiting resistor and has a relatively large resistance value. Therefore, the AC power supply 5
Is substantially only a series connection of the inductance element 6 and the capacitance element 7. When the frequency of the AC power supply 5 is set to or near the series resonance frequency f ₁ of the inductance element 6 and the capacitance element 7 and an AC voltage is supplied, a large series resonance voltage is applied to the output terminal of the AC voltage generator 1. Occurs.

When the series resonance voltage is in the forward direction with respect to the diode 40, the diode 40 and the resistor 41
, A small amount of current flows through the capacitor 2 to perform unidirectional charging. When the series resonance voltage is in the opposite direction with respect to the diode 40, the voltage in the same direction charged in the capacitor 2 is added to the series resonance voltage generated at the output terminal of the AC voltage generation unit 1, and the discharge electrode 3 will be applied.

Therefore, the voltage waveform applied to the discharge electrode 3 like the voltage waveform 45 between the discharge electrodes in FIG. 11 is a sine-wave AC waveform whose lower limit is clamped to almost zero potential. Then, the absolute value of the peak of the AC waveform gradually increases, and after a lapse of several cycles, insulation is broken and air discharge starts, and a discharge current flows as shown by a discharge current waveform 46 in FIG.

When a discharge is started due to the occurrence of dielectric breakdown,
The load between the discharge electrodes 3 is in a low impedance load state. As a result, the capacitance of the capacitor 2 is added in parallel to the capacitance element 7. Since the resistance of the resistor 41 is relatively large, the influence is small. Therefore, the load of AC power supply 5 is a series resonant circuit of inductance element 6 and capacitance element 7 and capacitor 2 connected in parallel. Therefore, after the start of the discharge, as in the case of the first embodiment, the output voltage at the discharge electrode 3 is,
Peak voltage V at the series resonance frequency f ₂ during a load
_{Take 2} (f ₂ ).

By providing the clamp circuit, when the dielectric breakdown occurs and discharge is started, the amplitude of the capacitor 2 can be increased by a half-wave of the resonance voltage. In the case of the first embodiment, In comparison, even if the voltage of the AC power supply 5 is low, discharge can be started. In a device having a switching unit for converting a DC power supply into an AC power, discharge can be started even if the voltage of the DC power supply is low. When a unit having a step-up transformer is used as the AC voltage generation unit 1, the step-up ratio can be reduced.

As the diode, a diode in which a plurality of diodes are connected in series may be used in consideration of the withstand voltage. Also, it is not necessary to be a diode, and a unidirectional conductive circuit such as a unidirectional element or a composite circuit including a unidirectional element that allows a current to flow in the forward direction and does not flow a current in the reverse direction may be used. .
Although the clamp circuit of FIG. 10 is a positive clamper, the polarity of the diode 40 may be reversed and a negative clamper may be used.
Alternatively, a bias voltage source of a predetermined voltage may be inserted in series with the diode 40 to serve as a base clamper and a peak clamper. The clamp circuit is for adding a DC component to a waveform having no DC component. The clamp circuit is capable of starting discharge by adding the DC component, and is also capable of stably starting discharge. I just need.

Although the resistance value of the resistor 41 is relatively large, it has a slight adverse effect during discharge. Therefore, after the start of discharge, the resistor 41 may be separated from the capacitor 2 by a switch (not shown).

A specific example will be described. The capacitance of the capacitor 2 can be set to 20 to 100 pF, the series resonance frequency at the time of no load before the start of discharging can be set to 10 to 300 kHz, and the resistance value of the resistor 41 can be set to 10 kΩ to 100 MΩ. As a more preferable first example, the capacitance of the capacitor 2 is set to 2
When the value in the range of 0 to 40 pF is set to about 30 pF as a typical example and the series resonance frequency at the time of no load before the start of discharge is about 100 kHz, the resistance value of the resistor 41 is set to about 10
MΩ. As a more preferable second example, the capacitor 2
Is about 60 pF, and the series resonance frequency at the time of no load before the start of discharge is about 60 kHz, and the resistance value of the resistor 41 is about 1 MΩ.

FIG. 12 is a schematic configuration diagram of a sixth embodiment of the present invention. In the figure, the same parts as those in FIG. 16 and FIG. 50 is a high resistance for bypass. In contrast to the first embodiment described with reference to FIG.
Is connected. The output terminal of the AC voltage generator 1 is connected to the discharge electrode 3 via this parallel circuit.

The discharge electrode 3 is initially in a high impedance state before the start of discharge. The resistance value of the high resistance 50 for bypass is considerably large. Therefore, the load of the AC power supply 5 is
Substantially inductance element 6 and capacitance element 7
Only in series. The frequency of the AC power supply 5
When the series resonance frequency f _{1 of the} inductance element 6 and the capacitance element 7 is set at or near this and an AC voltage is supplied, a large series resonance voltage is generated at the output terminal of the AC voltage generation unit 1. This resonance voltage is divided by the above-described series connection circuit of the parallel circuit and the discharge electrode 3 and applied to the discharge electrode 3, and the peak of the resonance waveform gradually rises as in a voltage waveform 15 between the discharge electrodes in FIG. Absolute value rises and after several cycles of resonance waveform, air discharge starts,
The discharge current flows as the discharge current waveform 16 in FIG.

When the discharge is started due to the occurrence of dielectric breakdown,
The load between the discharge electrodes 3 is in a low impedance load state. As a result, the capacitance of the capacitor 2 is added in parallel to the capacitance element 7. Since the high resistance for bypass 50 has a high impedance, this effect is slight. Therefore, the load of AC power supply 5 is a series resonant circuit of inductance element 6 and capacitance element 7 and capacitor 2 connected in parallel. Therefore, after the start of discharge, as in the case of the first embodiment, the output voltage at the discharge electrode 3 has a peak voltage at the series resonance frequency f ₂ under load, as in the resonance characteristic 11 under load in FIG. Take V ₂ (f ₂ ).

By adding the high resistance 50 for bypass, the capacitor 2 can be bypassed when the dielectric breakdown occurs and the discharge is started, so that the AC power supply 5 can be bypassed compared with the first embodiment. Discharge can be started even when the voltage is low. In a device having a switching unit for converting a DC power supply into an AC power, discharge can be started even if the voltage of the DC power supply is low. AC voltage generator 1
When using a device having a step-up transformer,
The boost ratio can be reduced.

Although the high resistance 50 for bypass is a high resistance, it has a slight adverse effect during discharge. Therefore, after the start of discharge, the capacitor 2 is turned on by a switch (not shown).
May be separated from the

A specific example will be described. The capacitance of the capacitor 2 can be set to 20 to 100 pF, the series resonance frequency at the time of no load before starting discharge is set to 10 to 300 kHz, and the resistance value of the bypass resistor 50 can be set to 10 kΩ to 100 MΩ. As a more preferred first example, the capacitance of the capacitor 2 is set to a value in the range of 20 to 40 pF, typically 3
When the series resonance frequency at the time of no load before the start of discharge is about 100 kHz, the resistance value of the bypass resistor 50 is about 10 MΩ. As a more preferable second example, the capacitance of the capacitor 2 is set to about 60 pF,
The series resonance frequency at no load before discharge starts
kHz, the resistance of the bypass resistor 50 is set to about 1
MΩ.

As described above, since the bypass resistor 50 has a high resistance, it is necessary to determine the resistance value in consideration of the insulation resistance of the wiring board or the like when actually manufacturing the device. It is also possible to design so that the bypass resistor 50 can be realized by the insulation resistance of the capacitor 2 or the insulation resistance of the capacitor 2.

FIG. 13 is a block diagram of the seventh embodiment of the present invention. In the figure, the same parts as those in FIGS. 16, 1, 4, 8, and 9 are denoted by the same reference numerals, and description thereof is omitted.
Reference numeral 60 denotes a resistance unit. This embodiment differs from the fourth embodiment described with reference to FIG. 9 in that the resistor 60 is inserted on the low potential electrode side of the discharge circuit to expand the function of the control unit 35. By making the resistance value of the unit 60 variable, the discharge current is set, and further, the feedback control is performed. First, before describing the seventh embodiment, a description will be given of the operation principle of supplying a discharge current stably over a wide range by making the resistance of the discharge circuit variable.

FIG. 14 shows a conventional discharge circuit, and FIG.
Is a discharge circuit in which the resistance in the discharge circuit is variable. In the figure,
16 and FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. 65 is a current limiting resistor, 70 is an insertion resistor, and 71 is a resistor insertion switch. Although an example using the AC power supply 5 is shown, the following description is the same for a DC power supply.

In the conventional discharge circuit shown in FIG. 14, the output of the AC power supply 5 is the internal resistance of the power supply and the like and the current limiting resistance 65.
Is connected to the discharge electrode 3. The impedance of the internal resistance of the power supply or the like slightly changes. Accordingly, the change range of the internal impedance of the circuit viewed from the discharge electrode 3 was within a certain narrow range. Therefore, in the conventional method, since the output voltage changes within the internal impedance change range, the changeable range of the discharge current is limited by the change range of the internal impedance.

Generally, in the discharge circuit, the discharge current is controlled by changing the output voltage of the AC power supply 5. Therefore, in order to reduce the discharge current, it is necessary to lower the output voltage. However, the output voltage drops,
When the voltage approaches the sustaining voltage at the discharge electrode, the discharge becomes unstable, and in some cases, the discharge stops.

That is, in order to perform stable discharge,
The current must be adjusted so that the output voltage always has a margin with respect to the sustaining voltage. However, in the conventional method, since the change range of the internal impedance is narrow, the adjustable range of the discharge current is also narrow. Further, in order to reduce the discharge current, the internal impedance must be increased. However, the power loss is large, which causes a problem that the efficiency is deteriorated.

In the discharge circuit shown in FIG. 15, an insertion resistor 70 is inserted on the low potential side of the discharge electrode 3 in the discharge circuit, and a resistance insertion switch 71 is connected in parallel with this. As the resistance insertion switch 71, a manual switch may be used, but a photocoupler type FET switch that can be electrically insulated from the control side is preferable.

When setting a low discharge current in this discharge circuit, the resistor insertion switch 71 is turned off so that the insertion resistor 70 is connected to the low voltage side of the discharge electrode 3. As a result, the internal impedance seen from the discharge electrode increases, and the output voltage has a margin with respect to the sustaining voltage, so that a lower discharge current can be stably obtained. When setting a high discharge current, the resistor insertion switch 71 is turned on to bypass the insertion resistor 70. Thereby, the internal impedance seen from the discharge electrode 3 can be reduced and a higher discharge current can be obtained, so that the efficiency is improved.

As described above, when the discharge current is small, the insertion resistor 70 is inserted into the circuit, and when the discharge current is large, the insertion resistor 70 is bypassed to change the change range of the internal impedance as viewed from the electrode. The range in which the discharge current can be set well can be widened.

The operation of this discharge circuit will be described. When a high voltage is generated by the AC power supply 1, dielectric breakdown occurs between the discharge electrodes 3, and a discharge current flows in the circuit. At this time, it is desirable that the resistor insertion switch 71 be kept on. The output voltage is V _out , the resistance value of the current limiting resistor 65 is R, and the impedance between the discharge electrodes 3 during steady discharge is r _g . Assuming that a discharge current flowing in the circuit is I, the discharge current I is represented by the following equation. I = V _out / (R + r _g ) Here, if the discharge current I is reduced, the output voltage V
_It is necessary to lower _out , and the discharge becomes unstable in this state because it approaches the discharge sustaining voltage. Discharge current I
When the resistance insertion switch 71 is turned off and the insertion resistor 70 is inserted into the circuit, when the resistance value of the insertion resistor 70 is r, the discharge current I ′ is expressed by the following equation. . I ′ = V _out / (R + r + r _g ) That is, while maintaining the output voltage V _out , the insertion resistance 70
Can be reduced by one step as compared with the discharge current I before insertion.

When it is necessary to increase the discharge current reduced by one step in a step with the insertion resistor 70 inserted, the output voltage _Vout may be increased. For example, when a constant current control method of detecting a discharge current and performing feedback control of the discharge current is used, the output voltage increases to be equal to the discharge current I before the insertion resistor 70 is inserted.

As described above, since the output voltage has a margin with respect to the sustaining voltage, the stability of the discharge is increased with a small discharge current. That is, by increasing the internal impedance of the circuit as viewed from the electrode, a lower discharge current can be stably obtained, and as a result, the setting range of the discharge current is widened.

Further, a more efficient discharge can be performed by preparing a plurality of insertion resistors 70 and selecting one of them or making them variable so as to set the resistance value more finely. it can. In this case, the resistor insertion switch 71 may be omitted. Further, it is also possible to change the resistance value of the insertion resistor 70 based on the detected discharge current, and to perform feedback control of the discharge current by changing the resistance value.

Returning to FIG. 13, the operation of the seventh embodiment of the present invention will be described. The resistor section 60 includes a parallel circuit of the insertion resistor 70 and the resistor insertion switch 71 described with reference to FIG. The current limiting resistor 65 is not shown. The current limiting resistor 65 may be included in the resistor section 60.
Since the current detection unit 30 is connected to the ground side, the resistance unit 60 is inserted between the current detection unit 30 and the low potential side of the discharge electrode.

In this embodiment, the resistance value of resistance section 60 is reduced before the start of discharge where no discharge current is detected. When the discharge current when the discharge current starts to be detected is larger than the set value, the pulse width of the drive pulse is narrowed, in other words, the duty ratio is reduced, and the resistance value of the resistor unit 60 is increased. As a result, the internal impedance increases stepwise, so that the discharge current decreases and approaches the set current. When the discharge current falls below the set value, the width of the drive pulse is widened, and as a result, the output voltage increases, so that the set current is maintained. The frequency may be controlled at the same time.

By controlling the resistance section 60 by the control section 35 which performs feedback by frequency / pulse width control, the setting range of the discharge current can be expanded efficiently and.

In the case where a battery is used as the DC power supply 20, when a decrease in DC voltage is detected, the resistance of the resistor section 60 may be switched so as to lower the resistance value manually or automatically. The measures to reduce the output of the DC power supply are as follows.
It can be applied to other embodiments.

The method of changing the internal impedance of the discharge circuit described with reference to FIGS.
It is not necessary to assume the configuration of the first and second embodiments described with reference to FIG. 7 and the like. In the conventional technology described with reference to FIG. 16 to FIG.
The present invention can also be applied to a discharge circuit using a DC high-voltage power supply.

[0137]

As is clear from the above description, according to the present invention, a means for initiating discharge does not require a complicated circuit configuration, thereby reducing the number of parts.
There is an effect that a discharge current supply device having a small configuration can be realized. Further, a voltage conversion circuit such as a DC-DC converter is not required, and in this respect, there is an effect that the discharge current supply device can be downsized. In addition, there is an effect that the discharge can be started even if the power supply voltage in the AC voltage generator is relatively low. When used for an optical fiber fusion splicing device, there is an effect that the fusion splicing device can be downsized.

When the discharge current is set by changing the drive frequency and / or pulse width of the drive pulse, there is an effect that the allowable range of the input voltage of the power supply and the settable range of the discharge current are widened. . When used for fusion splicing of optical fibers, the heating temperature can be easily adjusted.
Heating can be performed at a relatively low temperature by reducing the discharge current, and when performing fusion splicing, heating can be performed at a relatively high temperature by increasing the discharge current.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation of the first exemplary embodiment of the present invention.

FIG. 3 is a waveform diagram schematically illustrating a voltage waveform between discharge electrodes and a discharge current waveform according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a second embodiment of the present invention.

FIG. 5 is a waveform diagram of an example of an output pulse signal of an oscillation unit according to the second embodiment of the present invention.

FIG. 6 is a diagram illustrating an operation of the second exemplary embodiment of the present invention.

FIG. 7 is a waveform diagram schematically illustrating a voltage waveform between discharge electrodes and a discharge current waveform according to the second embodiment of the present invention.

FIG. 8 is a block diagram of a third embodiment of the present invention.

FIG. 9 is a block diagram of a fourth embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a fifth embodiment of the present invention.

FIG. 11 is a waveform diagram schematically showing a voltage waveform between discharge electrodes and a discharge current waveform according to a fifth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a sixth embodiment of the present invention.

FIG. 13 is a block diagram of a seventh embodiment of the present invention.

FIG. 14 is a conventional discharge circuit diagram.

FIG. 15 is a discharge circuit diagram in which the resistance in the discharge circuit is variable.

FIG. 16 is a block diagram of a conventional technique.

17 is a circuit diagram showing one example of a DC high voltage generation circuit diagram shown in FIG. 16;

FIG. 18 is a waveform diagram showing an outline of a voltage waveform between discharge electrodes and a discharge current waveform according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... AC voltage generating part, 3 ... Discharge electrode, 4 ... Frequency switching control part, 5 ... AC power supply, 6 ... Inductance element, 7 ... Capacitance element, 10 ... Resonance characteristics at no load, 11 ...
Resonance characteristics under load, 23 ... oscillator, 30 ... current detector,
35 ... control unit, 40 ... diode, 41 ... resistance, 50 ...
High resistance for bypass, 60: resistance part, 65: current limiting resistance, 7
0: insertion resistance, 71: resistance insertion switch.

──────────────────────────────────────────────────の Continued on the front page (31) Priority claim number Japanese Patent Application No. 7-236549 (32) Priority date September 14, 1995 (September 14, 1995) (33) Priority claim country Japan (JP) (72) Inventor Kazuo Iizuka 7-31, Omorinishi, Ota-ku, Tokyo Sumitomo Opcom Co., Ltd. (72) Inventor Masumi 7-31, Omorinishi, Ota-ku, Tokyo Sumitomo Opcom Corporation (56) References JP-A-2-179366 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 9/06

Claims (25)

(57) [Claims] 1. A discharge current supply method for supplying an AC output of an AC voltage generator having a series resonance circuit in which an inductance element and a capacitance element are connected in series in an equivalent circuit to a discharge electrode connected in series with a capacitor. The frequency of the AC voltage is set to a series resonance frequency of the series resonance circuit or a frequency in the vicinity thereof such that breakdown occurs between the discharge electrodes and discharge starts, and the discharge is performed by the AC output of the AC voltage generation unit. A discharge current supply method, characterized in that dielectric breakdown occurs between electrodes to start discharge, and that the discharge current is controlled by changing the frequency of the AC voltage after the start of discharge. 2. The method according to claim 1, wherein the AC voltage generator is configured to generate a AC voltage by switching a DC power supply with a driving pulse, and to change a driving frequency of the driving pulse after the start of discharge to change a frequency of the AC voltage. The discharge current supply method according to claim 1, wherein the discharge current is controlled by: 3. The discharge current supply method according to claim 2, wherein the discharge current is controlled by changing the pulse width of the drive pulse after the start of the discharge. 4. The method according to claim 1, wherein the AC output of the AC voltage generator is clamped and supplied to the discharge electrode in a high impedance state. 5. The discharge current supply according to claim 1, wherein the AC output of the AC voltage generator is supplied to the discharge electrode in a high impedance state via a high resistance. Method. 6. An internal circuit as viewed from the discharge electrode by supplying an AC output of the AC voltage generator to the discharge electrode having a resistor connected in series via the capacitor, and changing a resistance value of the resistor. The discharge current supply method according to claim 1, wherein the impedance is changed. 7. The discharge according to claim 1, wherein the frequency of the AC voltage is set to the series resonance frequency or a frequency near the series resonance frequency, thereby causing the dielectric breakdown and starting the discharge. 2. The method for supplying a discharge current according to claim 1. 8. The discharge according to claim 1, wherein the frequency of the AC voltage is changed so as to approach the series resonance frequency, thereby causing the dielectric breakdown and starting the discharge. The discharge current supply method in the section. 9. The discharge is started by changing the frequency of the AC voltage from a frequency higher than the series resonance frequency so as to approach the series resonance frequency. A discharge current supply method according to claim 8. 10. A discharge current supply device in which an AC output of an AC voltage generator having a series resonance circuit in which an inductance element and a capacitance element are connected in series in an equivalent circuit is supplied to a discharge electrode connected in series with a capacitor. The frequency of the AC voltage is set to the series resonance frequency of the series resonance circuit or a frequency in the vicinity thereof such that breakdown occurs between the discharge electrodes and discharge is started, and the AC output of the AC voltage generation unit sets the frequency. A discharge current supply device comprising: a control unit that controls the discharge current by changing the frequency of the AC voltage after the start of discharge by causing dielectric breakdown between the discharge electrodes and starting the discharge. 11. The AC voltage generating section switches a DC power supply by a drive pulse to generate an AC voltage, and the control section changes the drive frequency of the drive pulse after the start of discharge to change the AC voltage. The discharge current supply device according to claim 10, wherein the discharge current is controlled by changing the frequency of the discharge current. 12. The discharge current supply device according to claim 11, wherein the control unit controls the discharge current by changing the pulse width of the drive pulse after the start of the discharge. 13. The discharge current supply according to claim 10, further comprising means for clamping an output of the AC voltage generation unit and supplying the output to the discharge electrode in a high impedance state. apparatus. 14. The discharge current supply device according to claim 13, wherein a unidirectional conduction circuit is connected in parallel with said discharge electrode. 15. The discharge current supply device according to claim 14, wherein the unidirectional conduction circuit has a series connection circuit of a diode and a resistor. 16. The discharge current supply device according to claim 10, wherein a high-resistance bypass resistor is connected in parallel to said capacitor. 17. The discharge current supply device according to claim 16, further comprising means for disconnecting the bypass resistor from at least one terminal of the capacitor after starting discharge. 18. The discharge current supply device according to claim 10, wherein the AC voltage generator has a step-up transformer. 19. An output of an AC voltage generating unit is connected to the discharge electrode having a resistor connected in series via the capacitor, and the resistance of the resistor is variable, so that the output of the circuit is viewed from the discharge electrode. The discharge current supply device according to any one of claims 10 to 18, wherein the impedance changes. 20. The discharge current supply device according to claim 19, wherein the resistor comprises one or a plurality of resistors, and on-off switch means is connected to both ends of at least one of the resistors. 21. The discharge according to claim 10, wherein the discharge is started by generating the insulation breakdown by setting the frequency of the AC voltage to the series resonance frequency or a frequency near the series resonance frequency. The discharge current supply device according to claim 1. 22. The method according to claim 10, wherein the discharge is started by generating the insulation breakdown by changing the frequency of the AC voltage so as to approach the series resonance frequency. Item 7. The discharge current supply device according to Item 1. 23. The method according to claim 23, wherein the frequency of the AC voltage changes from a frequency higher than the series resonance frequency to approach the series resonance frequency, thereby causing the insulation breakdown and starting the discharge. The discharge current supply device according to claim 22. 24. An optical fiber fusion splicing device for fusion splicing an optical fiber by aerial discharge generated between discharge electrodes, comprising the discharge current supply device according to any one of claims 10 to 21. An optical fiber fusion splicer, comprising: 25. An optical fiber fusion splicing device for fusion splicing an optical fiber by air discharge generated between discharge electrodes, comprising the discharge current supply device according to claim 22 or 23. Optical fiber fusion splicer.