JP2707356B2 - Gas laser device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser device such as a carbon dioxide gas laser, and more particularly to a gas laser device in which a high-voltage power supply is reduced in size and output control is facilitated.

2. Description of the Related Art FIG. 4 shows a configuration example of a conventional gas laser device. 4th
In the figure, 1 is a laser resonator, 2 is an output mirror, 3 is a total reflection mirror, 4a and 4b are discharge electrodes, 5 is a discharge part of a gas laser medium in the laser resonator 1, 6 is a blower, and 7 is a cooler , 8 is an air supply duct, and 9 is an exhaust duct. Reference numeral 10 denotes a commercial power supply, 11 denotes a high-voltage transformer, 12 denotes a high-voltage rectifier diode, 13 denotes a high-voltage resistor, and 14 denotes a control vacuum tube.

Next, the operation of the conventional example will be described. The gas laser medium is supplied through a gas supply duct 8 by a blower 6 into a laser resonator 1 in which an output mirror 2 and a total reflection mirror 3 are mounted, and is excited by discharge by discharge electrodes 4a and 4b to output a laser beam. The high voltage for discharging and exciting the gas laser medium is obtained, for example, by boosting a 200 V commercial power supply 10 with a high-voltage transformer 11 and rectifying it with a high-voltage rectifier diode 12.
The current and voltage were controlled by 13 and the control vacuum tube 14.

Generally, the discharge voltage-current characteristics of this type of gas laser device change from a discharge starting voltage of 30 to 50 kV to a discharge sustaining voltage of about half thereof, and the voltage decreases as the current further increases. It shows the characteristics of In the conventional high-voltage power supply, the high-voltage transformer 11 has a constant voltage characteristic, and the difference from the discharge voltage is borne by the high-voltage resistor 13 and the control vacuum tube 14. As a result, in order to boost the commercial voltage from 10 to several tens of kV, a large-sized high-voltage transformer with a large turns ratio, a high-pressure vacuum tube with large dimensions to obtain a required insulation distance, and the like must be used. There is a problem that the power supply becomes large.

In addition, since current control is performed using the control vacuum tube 14 located on the high-voltage circuit, insulation between the control circuit and the high-voltage circuit is required, and the control circuit is frequently damaged due to noise in the high-voltage circuit. There was a point.

The present invention solves such a conventional problem, and can reduce the size of a high-voltage power supply of a gas laser device, prevent damage to a control circuit due to high-voltage noise, and facilitate output control. It is an object to provide a gas laser device.

Means for Solving the Problems In order to achieve the above object, the present invention provides a high-voltage power supply comprising a low-voltage AC power supply capable of changing an effective voltage, a step-up transformer, and a rectifier circuit. A capacitor is connected in parallel with the rectifier circuit between the secondary output terminal and the rectifier circuit, or the secondary coil winding of the step-up transformer is covered with a dielectric material having electrical insulation.
The secondary coil has a distributed capacitance, and the series resonance frequency of the capacitance obtained by multiplying the capacitance value of the distributed capacitance of the parallel capacitor or the secondary coil of the boost transformer by the square of the turn ratio of the boost transformer and the leakage inductance of the boost transformer is: This is 1.7 to 2.3 times the upper limit of the output frequency of the low-voltage AC power supply.

Operation According to the present invention, the winding ratio of the windings of the step-up transformer can be reduced by the above configuration, so that the step-up transformer can be downsized. Further, since the control of the high-voltage power supply can be controlled on the low-voltage side of the primary side of the step-up transformer, the control circuit can be prevented from being damaged by high-voltage noise, and the output can be easily controlled.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of an embodiment of the present invention, wherein 21 is a laser resonator, 22 is an output mirror, and 23 is a total reflection mirror. 24a,
24b is a discharge electrode, 25 is a discharge part of the gas laser medium in the laser resonator 21, 26 is a blower, 27 is a cooler, 28 is an air supply duct, and 29 is an exhaust duct. Also, 30 is a low-voltage DC power supply, 31 is an inverter circuit serving as a low-voltage AC power supply,
Four semiconductor switch elements 31a connected in full bridge
~ 31d. Reference numeral 32 denotes a step-up transformer having a primary coil and a secondary coil insulated, and an inverter circuit 31 is connected to the primary side thereof. 33 is a high-frequency high-voltage capacitor connected in parallel to the secondary side of the step-up transformer 32, and 34 is a rectifier circuit connected in parallel with the capacitor 33. Reference numeral 35 denotes a smoothing capacitor connected in parallel to the rectifier circuit 34. Both ends of the smoothing capacitor 35 are connected to the discharge electrodes 24a and 24b.

The turns ratio of the step-up transformer 32 is about one half of the required voltage, and the capacitance value of the capacitor 33 is the series resonance of the leakage inductance of the step-up transformer 32 and the capacitance value of the capacitor 33 multiplied by the square of the transformer turns ratio. Frequency is the inverter circuit 31
Is set to be about twice the upper limit value of the AC frequency output from.

Next, the operation of the above embodiment will be described. The gas laser medium is supplied into the laser resonator 21 through the air supply duct 28 by the blower 26, and is excited by causing a glow discharge between the discharge electrodes 24a and 24b to emit laser light.
The oscillated laser light is amplified and reciprocated between the output mirror 22 and the total reflection mirror 23, and is finally extracted from the output mirror 22 to the outside. The gas laser medium whose temperature has risen in the laser resonator 21 is recovered through the exhaust duct 29, cooled by the cooler 27, and sent again into the laser resonator 21 through the air supply duct 28 by the blower 26.

The output of the low-voltage DC power supply 30 generates an AC voltage by alternately turning on and off the semiconductor switch elements 31a and 31c and 31b and 31d of the inverter circuit 31, and changes the AC frequency according to the cycle of the turn-on and turn-off. Changes the effective voltage. The AC that has been boosted to a high voltage by the boost transformer 32 is rectified by the rectifier circuit 34, becomes a high-voltage DC smoothed by the smoothing capacitor 35, and is applied to the discharge electrodes 24a and 24b of the laser oscillator 21.

The frequency characteristic of the primary impedance of the step-up transformer 32 with respect to the output frequency of the inverter circuit 31 on the primary side of the step-up transformer 32 has a minimum value as shown in FIG. A frequency appeared, which coincided with the series resonance frequency of the leakage inductance of the step-up transformer 32 and the capacitance of the secondary-side capacitor 33 multiplied by the square of the transformer turns ratio. Further, as a result of measuring the output voltage characteristics on the secondary side of the step-up transformer 32, as shown in FIG. 3A, the output voltage at the time of no load has an output frequency near the resonance frequency, that is, the impedance has a minimum value due to series resonance. The maximum value is shown at the point where .times..times..times..times..times..times..times..times..times. The characteristic of the maximum output current is shown in FIG.
The ratio between the output frequency of 31 and the series resonance frequency is from 1 / 1.7 to 1 /
It was found that a large output current was obtained up to 2.3.

As a result, the step-up transformer
Assuming that the series resonance frequency of the capacitance twice as large as the turns ratio of 32 and the leakage inductance of the step-up transformer 32 is 1.7 times to 2.3 times the upper limit of the output frequency of the inverter circuit 31, the turns ratio of the turns of the step-up transformer 32 is as follows. The ratio can be reduced to about one half of the primary / secondary voltage ratio, and the step-up transformer 32 can be made smaller than a conventional transformer having a high voltage output and a large coil size. Further, the high voltage output on the secondary side of the step-up transformer 32 can be controlled by the low voltage side on the primary side of the step-up transformer 32 and is isolated from the high voltage side by the step-up transformer 32. Damage to the control circuit can be prevented. The output on the high voltage side is connected to the inverter circuit 31.
Can be controlled by the intermittent frequency and the energizing time of the power supply, so that the output can be easily controlled.

The present invention also includes a capacitor 33 (not shown).
Instead, the secondary coil winding of the step-up transformer 32 can be realized by coating the secondary coil with a dielectric material having electrical insulation so as to provide the secondary coil with a distributed capacitance.
That is, about twice the intermittent frequency of the inverter circuit 31 (1.
The dielectric constant and the coating thickness of the dielectric material covering the secondary coil winding may be determined so that the primary impedance of the step-up transformer 32 is minimized at a frequency of 7 to 2.3 times. The frequency at this time is the series resonance frequency of the capacitance obtained by multiplying the secondary winding distribution ratio by the square of the transformer winding ratio and the leakage inductance of the step-up transformer 32. The required voltage is the same as in the embodiment shown in FIG. Since the step-up transformer 32 can be configured with a turns ratio of about half of the ratio, and the high-voltage output of the step-up transformer 32 can be controlled on the low-voltage side of the primary side, the same effect as in the above embodiment can be obtained. be able to.

As described above, according to the gas laser device of the present invention, the winding turns ratio of the step-up transformer is reduced to about one half of the primary / secondary voltage ratio.
And the size of the step-up transformer can be reduced. In addition, since the output of the high-voltage power supply can be controlled on the low-voltage side of the primary side of the step-up transformer without using a high-voltage element such as a vacuum tube, damage to the control circuit due to high-voltage noise can be prevented. , Output can be easily controlled.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a gas laser device showing one embodiment of the present invention, FIG. 2 is a graph showing a frequency characteristic of a phase and a primary impedance of a step-up transformer in one embodiment of the present invention, and FIG. 3 is a graph showing frequency characteristics of a voltage generated when no load is applied to the step-up transformer according to the embodiment of the present invention.
FIG. B is a graph showing the frequency characteristic of the maximum current of the high-voltage power supply in one embodiment of the present invention, and FIG. 4 is a schematic configuration diagram showing an example of a conventional gas laser device. 21 ... laser resonator, 22 ... output mirror, 23 ... total reflection mirror,
24a, 24b discharge electrode, 25 discharge part of gas laser medium, 26 blower, 27 cooler, 28 air supply duct,
29 exhaust duct, 30 low-voltage DC power supply, 31 inverter circuit (low-voltage AC power supply), 31a-31d semiconductor switch element, 32 step-up transformer, 33 high-frequency high-voltage capacitor, 34 …… Rectifier circuit, 35 …… Smoothing capacitor.

Continuing on the front page (72) Inventor Shuzo Yoshizumi 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Inventor Shigeki Yamane 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (2)

(57) [Claims] 1. A gas laser apparatus for generating a laser beam by exciting a gas laser medium in a laser resonator by discharge of a discharge electrode connected to a high voltage power supply, wherein the high voltage power supply changes an effective voltage. A low-voltage AC power supply, a step-up transformer, and a rectifier circuit, wherein a capacitor is connected in parallel with the rectifier circuit between a secondary output terminal of the step-up transformer and the rectifier circuit, and a leakage inductance of the step-up transformer is provided. And a series resonance frequency of a capacity obtained by multiplying the capacity of the capacitor by the square of the turn ratio of the step-up transformer is 1.7 to 2.3 times the upper limit of the output frequency of the low-voltage AC power supply. 2. A gas laser device for generating a laser beam by exciting a gas laser medium in a laser resonator by discharging a discharge electrode connected to a high voltage power supply, wherein the high voltage power supply changes an effective voltage. A low-voltage AC power supply, a step-up transformer, and a rectifier circuit, wherein a secondary coil winding of the step-up transformer is covered with a dielectric material having electrical insulation to have a distributed capacitance, The series resonance frequency of the capacitance obtained by multiplying the dielectric constant and coating thickness of the secondary coil of the boosting transformer by the square of the turns ratio of the boosting transformer and the leakage inductance of the boosting transformer is the output frequency of the low-voltage AC power supply. A gas laser device characterized in that the upper limit value is set to be 1.7 to 2.3 times.