JPH03124082A - Controlling apparatus for high-frequency power supply for co2 gas laser - Google Patents

Abstract

PURPOSE:To surely ignite a discharge tube by a method wherein, at a start, an output of a changeover circuit, a discharge voltage and an output of a power setting circuit are changed over from a voltage control operation to a power control operation by means of a feedback control operation. CONSTITUTION:In a control apparatus of a high-frequency power supply for CO2 gas laser use, a changeover circuit 38 is not operated at a start. When an output of a waveform setting circuit 33 rises, a first delay circuit 36 counts a set time, executes a voltage feedback operation and surely ignites a discharge tube at the start. When an output of the circuit 36 counts up the set time and rises, changeover switches of the circuit 38, a discharge voltage and a power setting circuit 41 are changed over. Then, an output of a power detection circuit ls input to an inverted terminal of an error amplification circuit 34 and an output of a power setting circuit 53 of the circuit 41 is input to a non-inverted terminal; a power feedback control operation is executed to prevent an overshoot and a damping from being caused at a rise of a waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method and apparatus for controlling a high-frequency power source for an RF-excited CO2 gas laser, and in particular to voltage feedback control at the time of start and steady state after start, and power feed control. control, and laser power feedback control.

Conventional technology Conventional feedback control of a high-frequency power supply for an RF-excited CO2 gas laser involves the output of a power setting circuit that sets the magnitude of the laser output, and the output of a power detection circuit that detects the magnitude of the high-frequency output or the laser power. The output of the laser sensor (war detection circuit) that detects the magnitude was input to an error amplifier circuit, and the output of the error amplifier circuit was input to an attenuator.

The configuration of the RF excitation oscillator is shown in Figure 3 below, and the conventional RF
The configuration of the excited CO2 gas laser device is shown in Figure 4, and the RF
A control block diagram of the high frequency power supply for the excited CO2 gas laser device is shown in FIG.

First, Figure 3 shows the configuration of a general high-speed axial flow type RF excitation oscillator, in which metal parallel plate electrodes 3 and 4 are provided in close contact with the outer periphery of a discharge tube 2 made of a dielectric material such as glass. There is. The parallel plate electrodes 3 and 4 receive the output from the high frequency power source 1,
For example, 13.56 MHz, 2.5 KW, and 2 to 3 KV are supplied. A discharge 5 occurs in the discharge space within the discharge tube 2 sandwiched between the parallel plate electrodes 3.4 in the direction shown by the arrow.

Fixedly placed at both ends of the discharge space. A rear mirror (total reflection mirror) 6 and an output mirror (partial reflection mirror) 7 form an optical resonator, and a laser output 8 is extracted from the output mirror 7.

Laser gas 9 is circulating in air pipe 10, and discharge 5
The laser gas 9 whose temperature has been increased by a blower 12 that circulates the laser gas is cooled by a heat exchanger 11 .

The high frequency power source 1 in FIG. 3 corresponds to the RF power source 13 in FIG. 4.
The output of the power supply 13 is transmitted via a coaxial cable 14 to a matching box 15 for matching with a load.

The output of the matching box 15 is connected to the coupling capacitors 16 to 16 provided to balance the parallel load.
18, and discharge tubes 19-21 are connected to coupling capacitors 16-18.

Referring to FIG. 5, the output of the oscillation circuit 23 passes through a switch circuit 24 and is then input to an attenuation circuit 25 that controls the magnitude of the RF output.

The output of the attenuation circuit 25 is input to a preamplifier 26, and the output of the preamplifier 26 is input to a driver 27. The output of the driver 27 is input to an amplifier circuit 28 using a vacuum tube or the like, and the output of the amplifier circuit 28 is input to a tuning circuit (tank circuit) 2.
9 is input. The output of the tuning circuit 29 is the power detection circuit 3
After passing through 0, it is output from the coaxial cable connector 31 to the outside.

Further, the output of the starting circuit 32 is input to a pulse mode or CW mode waveform setting circuit 33.
A signal in which the pulse frequency and pulse width in the pulse mode are set, or the energization and output period in the cw mode is output from.

The switch circuit 24 opens and closes in conjunction with the output of the waveform setting circuit 33, and when the switch circuit 24 is open, the RF ratio output is instantaneously cut off and turned off.

The output of the power setting circuit 35 that sets the RF ratio output magnitude, that is, the magnitude of the laser output, is input to the non-inverting terminal of the error amplification circuit 34. On the other hand, the output of the power detection circuit 3o is input to the inverting terminal of the error amplification circuit 34, and the output of the error amplification circuit 34 is input to the attenuation circuit 25. Attenuation circuit 25
The input varies from O to 5V, etc., and the higher the input, the greater the RF output, controlling the RF ratio output.

Problems to be Solved by the Invention In a control device for a high frequency power supply for an RF-excited CO2 gas laser, the discharge starting voltage of the discharge tube of the RF-excited CO2 gas laser is higher and lower than the discharge starting voltage of the discharge tube of the DC-excited CO2 gas laser. , 0 If the laser power is lowered, the discharge tube may not ignite reliably. In addition, when feedback control is performed using a laser power detection circuit that detects the magnitude of laser power at the rise of the pulse mode or CW mode waveform, the response delay of the detection signal of the laser power detection circuit is 25 m.
Since it is extremely slow at about 5ec, the output of this laser power detection circuit and the output of the power setting circuit are compared and amplified by the error amplifier circuit, so the output of the error amplifier circuit that feeds back causes large overshoot and damping, and the laser The output also generates large overshoot and damping at each waveform rise.

Further, during steady state after starting, as mentioned above, if the laser power is low, the discharge tube may misfire. Similarly, during normal operation after starting, the power supply voltage etc. may fluctuate instantaneously.
At this time, when feedback control is performed using the laser power detection circuit, as described above, the response delay of the detection signal of the laser power detection circuit is extremely slow at 25 m5ec, which causes a large ripple in the peak value of the laser output.

The present invention eliminates the conventional drawbacks, ensures reliable ignition of the discharge tube, eliminates overshoot and damping at the rising edge of the waveform, and prevents the discharge tube from misfiring even during steady state after starting. The present invention provides feedback control of a high-frequency power source for an RF-excited CO2 gas laser in which ripples do not occur in the peak value of the laser output due to disturbances.

Means for Solving the Problems In order to solve the above problems, a control device for a high frequency power source for a CO2 gas laser according to the present invention provides a pulse mode or C
a waveform setting circuit that sets the waveform of the W mode; a first delay circuit; a voltage detection circuit that detects the discharge tube discharge voltage; a power detection circuit that detects the magnitude of high-frequency power; a first start switching circuit that switches the output of the detection circuit and the power detection circuit; a discharge voltage and power setting circuit that sets the discharge voltage of the discharge tube and the magnitude of the laser power; and an error amplification circuit that performs feedback control. and inputting the output of the waveform setting circuit to the first delay circuit, and inputting the output of the first delay circuit to the first delay circuit.
input to the start switching circuit and the discharge voltage and power setting circuit, input the output of the voltage detection circuit and the output of the power detection circuit to the first start switching circuit, and input the output of the voltage detection circuit and the output of the power detection circuit to the first start switching circuit; The output of the switching circuit at start and the discharge voltage,
The output of the power setting circuit is input to the error amplifier circuit.

Further, the output of the first delay circuit is connected to a second start switching circuit, and the output of the power detection circuit and the output of the laser power detection circuit that detects the magnitude of the laser power are connected to the second start switching circuit. The output of the second start switching circuit and the output of a power setting circuit for setting the magnitude of laser power are input to the error amplifier circuit.

Further, a third start switching circuit switches outputs of the voltage detection circuit, the power detection circuit, the laser power detection circuit, the voltage detection circuit, the power detection circuit, and the laser power detection circuit. and the first delay circuit, the second delay circuit, the discharge voltage and power setting circuit, and the error amplification circuit, and the output of the voltage detection circuit and the output of the power detection circuit. , the output of the laser power detection circuit is input to the third start switching circuit, and the output of the first delay circuit is input to the second delay circuit, the third start switching circuit, and the discharge voltage. , the output of the second delay circuit is input to the third start switching circuit, and the output of the third start switching circuit is connected to the discharge voltage and power setting circuit. The output is input to the error amplification circuit.

Further, a discharge voltage state detection control circuit that compares the output of the voltage detection circuit with a reference value and outputs a voltage feedback switching signal, the power detection circuit, the voltage detection circuit, and the A first steady-state switching circuit that switches the output of the power detection circuit and the voltage detection circuit, the discharge voltage and power setting circuit, and the error amplification circuit, and the output of the discharge voltage state detection control circuit and , inputting the output of the power detection circuit and the output of the voltage detection circuit to the first steady state switching circuit, and inputting the output of the first steady state switching circuit and the discharge voltage.

The output from the power setting circuit is input to the error amplifier circuit.

Further, a power injection state detection control circuit that compares the output of the power detection circuit with a reference value and outputs a power feedback signal, the laser power detection circuit, the power detection circuit, and the a second steady-state switching circuit for switching the outputs of the laser power detection circuit and the power detection circuit; the power setting circuit; and the error amplification circuit; The output of the laser power detection circuit and the output of the power detection circuit are input to the second steady-state switching circuit, and the output of the second steady-state switching circuit and the output of the power setting circuit are connected to each other according to the error. It is input to an amplifier circuit.

Further, a discharge state detection control circuit incorporating the discharge voltage state detection control circuit and the power injection state detection control circuit, the laser power detection circuit, and the power detection circuit;
the voltage detection circuit; a third steady state switching circuit that switches between the output of the laser power detection circuit, the output of the power detection circuit, and the output of the voltage detection circuit during steady state after starting; and the discharge voltage; It includes a power setting circuit and the error amplification circuit, and the discharge state detection circuit includes an output of the laser power detection circuit, an output of the power detection circuit,
The output of the voltage detection circuit is inputted to the third steady state switching circuit, and the output of the third steady state switching circuit and the output of the discharge voltage and power setting circuit are inputted to the error amplifier. It is what it is.

action In the above means, at the start, the discharge voltage.

The discharge voltage setting circuit of the power setting circuit sets a discharge voltage equal to or higher than the discharge starting voltage of the discharge tube, voltage feedback control is performed for the time set by the first delay circuit T1, and then power feedback control is performed at the time of start. Since switching is performed using a switching circuit, the discharge tube is reliably ignited. The magnitude of the high frequency output during power feedback control, that is, the magnitude of the laser power, is determined by the power setting circuit of the discharge voltage and power setting circuit after a time set by the first delay circuit.

In addition, power feedback control is performed for the time set by the second delay circuit, and then switched to laser power feedback control by the start switching circuit, so open neatness and damping do not occur at the rising edge of the waveform. do not.

In addition, during steady state after start, the discharge state detection control circuit
When the voltage is slightly higher than the discharge starting voltage of the discharge tube, the voltage feedback control is used, or when fluctuations occur due to instantaneous disturbances, the control is switched to the power feedback control, and from the laser power feedback control to the steady state switching circuit. As a result, the discharge tube does not misfire,
Moreover, ripples do not occur in the peak value of the laser output due to disturbances. In this way, the output of the detection circuit that is input to the start switching circuit causes ■ Voltage feed bank control (hereinafter referred to as VFR) → Power feedback control (hereinafter referred to as PFB), and ■ PFB → Laser power feedback control (hereinafter referred to as PFB). (hereinafter referred to as laser PFB), (1) or VFB-+PFB, and →laser power can be switched in the feedback control at the time of start.

Further, by the output of the detection circuit inputted to the steady state switching circuit and the start switching circuit, the steady state feedback control can be switched from (1) PPB-+VFB to (2) laser PFB+PFB or (2) from laser PFB to VFB or PFB.

Naturally, the combination of the above-mentioned feedback control ■~■ at the time of start and feedback control ■~■ during steady state, that is, ■ After VFB-PFB control at start, PFB at steady state
4-4VFB ■ PFB at start → After laser PFB control, during steady state,
Laser PFB44PFB, ■ VFB at start → PFB → After laser PFB control,
During steady state, feedback control can also be performed in combination with laser PFB→VFB or PFB.

Embodiment FIG. 1 is a control block diagram of a high frequency power source for an RF-excited CO2 gas laser device of the present invention, and FIG. 2 is a waveform diagram of the main part of FIG. 1.

Components in FIGS. 1 and 2 that are the same as those in FIG. 5 are given the same numbers.

The main waveform diagrams of FIG. 1 and FIG. 2 will be compared and explained.

For explanation, see VFB-PFB → Laser P at start.
After FB control, the case of laser PFB +VFB or PFB during steady state will be explained.

First, in FIG. 1, when the output of the waveform setting circuit 33 as shown in FIG. 2 (a) rises, the first delay circuit 36 counts a set time. During this time, Figure 2 (b)
Voltage feedback control is performed as shown in 54 and 57 in FIG. 2(d) to ensure ignition of the discharge tube at the time of start. The start switching circuit 38 includes a power detection circuit 30.
, the output of the voltage detection circuit 42 , and the output of the laser power detection circuit 43 are inputted to the selector switch 4 .
4. 45 and the changeover switch 5 of the steady state changeover circuit 40
Since 0°51 is not operating, the output of the voltage detection circuit 42 is input to the inverting terminal of the error amplification circuit 34.

On the other hand, the discharge voltage and the output from the discharge voltage setting circuit 52 of the power setting circuit 41 are input to the non-inverting terminal of the error amplifier circuit 34. Since the output of the first delay circuit 36 is "L", the output of the AND element 63 of the discharge voltage and power setting circuit 41 is "L", and the changeover switch 64 is not operated. The output of the first delay circuit 36 in FIG. 4 is shown in FIG.
When the set time counts up and rises as shown in b), the output of the first delay circuit 36 is input to the second delay circuit 37, the changeover switch 44, and the AND element 63, and the output of the AND element The other terminal is inverter element 6
5 is "H", the output of the AND element 63 becomes "H", the output of the AND element 63 is input to the changeover switch 64, and the changeover switch 4464 is switched.

When the changeover switch 44.64 is switched, the error amplifier circuit 3
The output of the power detection circuit 30 is input to the inverting terminal of 4,
On the other hand, the discharge voltage and the output of the power setting circuit 53 of the power setting circuit 41 are input to the non-inverting terminal of the error amplifier circuit 34, and the power Performs feedback control to prevent open neatness and damping at the rise of the waveform. Then, the time set in the second delay circuit 37 is counted, and when the count up, the output of the second delay circuit 37 is inputted to the changeover switch 45 and the discharge state detection control circuit 39, and the output of the error amplification circuit 34 is inverted. The output of the laser power detection circuit 34 is input to the terminal.

On the other hand, at this time, the output of the laser power setting circuit 53, which is the same as that during power feedback control, is input to the non-inverting terminal of the error amplifier circuit 34, and as shown in FIG.
Laser power feedback control is performed as shown in 66. The output of the second delay circuit 37 may not be input to the discharge state detection control circuit 39.

After the output of the second delay circuit 37 rises as shown in FIG. 2(C),
Laser power feedback control is performed as shown in 66, and the discharge state detection control circuit 39 will be explained here. In the comparator circuit C146, the voltage detection circuit 42
The output of the comparator circuit C146 is compared with a reference value that sets a voltage slightly higher than the discharge starting voltage of the discharge tube, and when the discharge voltage becomes lower than the reference value in steady state, the output of the comparator circuit C146 becomes "H" and the control It is input to circuit V48. The output of the control circuit V48 is the changeover switch 50 and the inverter element 6.
5, the changeover switch 50 operates, and the output of the inverter element 65 becomes "L", so the output of the AND element 63 becomes "L".

When the output of the AND element 63 becomes L'', the selector switch 64
is switched to the output side of the discharge voltage setting circuit 52, and the output of the discharge voltage setting circuit 52 is input to the non-inverting terminal of the error amplifying circuit 34. On the other hand, when the changeover switch 50 is operated, the inverting terminal of the error amplifying circuit 34 is inputted. The output of the voltage detection circuit 42 is input, and the laser power feedback control is switched to the voltage feedback control only during the period when the control circuit V48 is "H". The timing of the voltage feedbank control at this time is shown at 58 in FIG. 2(d) to prevent the discharge tube from losing arc.

The comparator circuit 0146 and the control circuit V48 constitute a discharge voltage state detection control circuit. In addition, the comparator circuit C247 compares the output of the power detection circuit 30 or a value obtained by differentiating the output of the power detection circuit 30 with a reference value for setting a reference power value or a reference ripple value. When the power value is lower than the power value or the ripple value is higher than the reference value, the output of the comparator circuit C247 becomes "H" and is input to the control circuit P49.

The output of the control circuit P49 is input to the changeover switch 51,
The changeover switch 51 operates, the output of the power detection circuit 30 is input to the inverting terminal of the error amplification circuit 34, and the control circuit P
49 switches from laser power feedback control to power feedback control only during the "H" period. At this time, the output of the laser power setting circuit 53 is input to the non-inverting terminal of the error amplification circuit 34.

In addition, the timing of power feedback control at this time is shown in 60, 61, and 62 of Fig. 5 (e), and there are three instantaneous fluctuations in the power supply voltage, etc., and in contrast, instantaneous power fluctuations occur. Feedback control is performed and compensation is performed so that the set power is achieved.

In laser power feedback control, the response of the laser power detection circuit is as slow as 25 m5ec, so it is not possible to compensate for instantaneous power fluctuations, for example, power fluctuations of 0.1 m5ec to l Q m5ec.

The comparator circuit C247 and the control circuit P49 constitute a power injection state detection control circuit. Note that the first delay circuit 36 in FIG. 1 is used for ignition of the discharge tube.

The ignition of the discharge tube can also be ensured by replacing the discharge detection circuit with a discharge detection circuit that detects discharge. Further, the input of the start switching circuit 38 is switched by the first delay circuit 36 so that only the output of the voltage detection circuit 42 and the output of the power detection circuit 30 are input.
The magnitude of the laser output may be controlled only by power feedback control while ensuring the ignition of the discharge tube.

In addition, if the lowest high frequency output and lowest laser power are used to reliably ignite the discharge tube, the input of the start switching circuit 38 is changed to the output of the power detection circuit 30 and the laser power detection circuit 43.
The first delay circuit 36 may be used to switch only the output of , to prevent damping of the waveform rising portion and occurrence of overshoot, and then perform laser power feedback control.

Here, the first delay circuit 36 has a set time (1 to 3 m5ec) of the first delay circuit 36 during voltage feed bank control.
Unlike, it is about 25m5ec and 1. This is the same value as T2 of the second delay circuit 37.

Also, regarding the steady state switching circuit 40, if the magnitude of the laser output is controlled only by power feedback control,
The input of the steady state switching circuit 40 may be the output of the voltage detection circuit 42.

In addition, if the lowest high frequency output and lowest laser power are used to reliably ignite the discharge tube, the input of the switching circuit 40 during steady state is the output of the power detection circuit 30, and if there is no instantaneous fluctuation, the laser power feedback control is performed. good. Regarding the combination of the type of output of the detection circuit inputted to the start switching circuit 38 and the type of output of the detection circuit inputted to the steady state switching circuit 40, as can be seen from the explanation of each of the two types above (effects). ) combinations listed in the last part of ■～■
become.

Further, the voltage detection circuit 42 generally delimits the discharge voltage with a capacitor and detects the delimited discharge voltage and high frequency output.

Further, a control method and a device thereof comprising a delay circuit, a start switching circuit, a steady state switching circuit, a state detection control circuit, a setting circuit, an error amplification circuit, and a detection circuit according to the present invention provide When a factor that requires bank control occurs, a detection circuit for that factor can be provided based on the same concept, and applications can be developed.

Effects of the Invention As described above, according to the present invention, the ignition of the discharge tube is ensured at the time of start, and the occurrence of overshoot and damping at the rising portion of the waveform can be prevented. In addition, the arc of the discharge tube does not occur even in a steady state after starting, it is possible to compensate for instantaneous fluctuations, and no ripples occur in the peak value of the laser output.

[Brief explanation of drawings]

Fig. 1 is a control block diagram of the high frequency power supply for the RF pumped C02 gas laser device of the present invention, Fig. 2 is a signal waveform diagram of the main parts, Fig. 3 is a perspective view of a general RF pumped oscillator, and Fig. 4 is A configuration diagram of a conventional RF-excited CO2 gas laser device, and FIG. 5 is a control block diagram thereof. 36...First delay circuit, 37...Second delay circuit, 38...Start switching circuit,
39...discharge state detection control circuit, 40...
... Steady state switching circuit, 41... Discharge voltage, power setting circuit.

Claims (11)

[Claims] (1) In a control device for a high-frequency power source for a CO_2 gas laser, which injects high-frequency power into a discharge tube and generates laser light from gas excited by the high-frequency discharge,
a waveform setting circuit for setting a waveform in pulse mode or CW mode; a first delay circuit; a voltage detection circuit for detecting the discharge tube discharge voltage; a power detection circuit for detecting the magnitude of high-frequency power; , a first start switching circuit that switches the outputs of the voltage detection circuit and the power detection circuit, a discharge voltage and power setting circuit that sets the discharge voltage of the discharge tube and the magnitude of the laser power, and feedback control. an error amplification circuit, the output of the waveform setting circuit is input to the first delay circuit, and the output of the first delay circuit is input to the first start switching circuit and the discharge voltage and power settings. The output of the voltage detection circuit and the output of the power detection circuit are input to the first start switching circuit, and the output of the first start switching circuit and the discharge voltage and power settings are input to the circuit. A control device for a high frequency power source for a CO_2 gas laser, characterized in that the output of the circuit is inputted to the error amplification circuit, and at the time of start, voltage feedback control is switched to power feedback control. (2) Control of the high frequency power source for CO_2 gas laser according to claim 1, characterized in that a discharge detection circuit for detecting ignition and discharge of the discharge tube is used in place of the first delay circuit. Device. (3) The output of the first delay circuit is input to the second start switching circuit, and the output of the power detection circuit and the output of the laser power detection circuit that detects the magnitude of laser power are input to the second start time switching circuit. The output of the second start switching circuit and the output of the power setting circuit that sets the magnitude of the laser power are input to the error amplifier circuit, and at the start, power feedback control is performed. A control device for a high frequency power source for a CO_2 gas laser according to claim 1, characterized in that the control device switches to laser power feedback control. (4) Claim 1 characterized in that the output of the power detection circuit and the output of the laser power detection circuit are configured to have the same value at a high frequency output of a certain set magnitude. Alternatively, the control device for a high frequency power source for a CO_2 gas laser according to item 3. (5) Third start switching for switching outputs of the voltage detection circuit, the power detection circuit, the laser power detection circuit, the voltage detection circuit, the power detection circuit, and the laser power detection circuit. circuit, the first delay circuit, the second delay circuit, the discharge voltage and power setting circuit, and the error amplification circuit, and the output of the voltage detection circuit and the output of the power detection circuit. and the output of the laser power detection circuit are input to the third start switching circuit, and the output of the first delay circuit is input to the second delay circuit T_2, the third start switching circuit, and the third start switching circuit. a discharge voltage and a power setting circuit; an output of the second delay circuit is input to the third start switching circuit;
The output of the start switching circuit and the output of the discharge voltage and power setting circuit are input to the error amplifier circuit, and at the start, voltage feedback control is switched to power feedback control, and power feedback control is switched to laser power feedback control. A control device for a high frequency power source for a CO_2 gas laser according to any one of claims 1 to 4, characterized in that the control device is configured to switch. (6) a discharge voltage state detection control circuit that compares the output of the voltage detection circuit with a reference value and outputs a voltage feedback switching signal; the power detection circuit; and the voltage detection circuit; The output of the discharge voltage state detection control circuit includes a first steady state switching circuit that switches the outputs of the power detection circuit and the voltage detection circuit, the discharge voltage and power setting circuit, and the error amplification circuit. and inputting the output of the power detection circuit and the output of the voltage detection circuit to the first steady state switching circuit, and inputting the output of the first steady state switching circuit and the discharge voltage and power setting circuit. The output of the discharge voltage state detection control circuit is inputted to the error amplification circuit, and the power feedback control and the voltage feedback control are switched in accordance with the state of the output of the discharge voltage state detection control circuit during steady state. A control device for a high frequency power source for a CO_2 gas laser according to any one of items 1 to 5. (7) a power injection state detection control circuit that compares the output of the power detection circuit with a reference value and outputs a power feedback signal; the laser power detection circuit; the power detection circuit; a second steady-state switching circuit that switches outputs of the laser power detection circuit and the power detection circuit, the power setting circuit, and the error amplification circuit, the output of the power injection state detection control circuit; The output of the laser power detection circuit and the output of the power detection circuit are input to the second steady state switching circuit, and the output of the second steady state switching circuit and the output of the power setting circuit are input to the second steady state switching circuit. Claims 1 to 3 are characterized in that the laser power feedback control and the power feedback control are switched according to the state of the output of the steady state power injection state detection control circuit which is input to the error amplification circuit. 7. A control device for a high frequency power source for a CO_2 gas laser according to any one of Item 6. (8) a discharge state detection control circuit incorporating the discharge voltage state detection control circuit and the power injection state detection control circuit; the laser power detection circuit; and the power detection circuit;
the voltage detection circuit; a third steady state switching circuit that switches between the output of the laser power detection circuit, the output of the power detection circuit, and the output of the voltage detection circuit during steady state after starting; and the discharge voltage; comprising a power setting circuit and the error amplification circuit, the output of the discharge state detection circuit, the output of the laser power detection circuit, and the output of the power detection circuit;
inputting the output of the voltage detection circuit to the third steady state switching circuit; inputting the output of the third steady state switching circuit and the output of the discharge voltage and power setting circuit to the error amplifier; Claims 1 to 7 are characterized in that during steady state, laser power feedback control, power feedback control, and voltage feedback control are switched according to the state of the output of the discharge state detection control circuit.
A control device for a high frequency power source for a CO_2 gas laser according to any one of Items 1 to 9. (9) At the start, the voltage feedback control is switched to the power feedback control after the time set by the first delay circuit, and in the subsequent steady state, the power feedback control and the voltage feedback control are switched to the power feedback control by the discharge voltage state detection control circuit. 9. A control device for a high-frequency power source for a CO_2 gas laser according to any one of claims 1 to 8, characterized in that the control device is configured to switch according to the state of the output. (10) At the start, power feedback control is switched to laser power feedback control after the time set by the first delay circuit, and then during steady state, laser power feedback control and power feedback control are switched to the power injection state detection control. A control device for a high frequency power source for a CO_2 gas laser according to any one of claims 1 to 9, characterized in that the control device is configured to switch according to the state of the output of the circuit. (11) At the start, switch from voltage feedback control to power feedback control after the time set by the first delay circuit, and then from power feedback control to laser power feedback control after the time set by the second delay circuit. After switching, during a steady state thereafter, laser power feedback control, power feedback control, and voltage feedback control are switched according to the state of the output of the discharge state detection control circuit. A control device for a high frequency power source for a CO_2 gas laser according to any one of items 1 to 10.