JP2649428B2 - 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 laser, and more particularly to a laser device that increases the efficiency of a high-voltage power supply and stabilizes an output current.

2. Description of the Related Art FIG. 3 shows a configuration example of a conventional gas laser device. The gas laser medium is supplied through a supply duct 5 by a blower 4 into a laser resonator 3 in which an output mirror 1 and a total reflection mirror 2 are mounted, and is excited by discharge by discharge electrodes 6 and 7 to output laser light. The gas laser medium whose temperature has risen in the laser resonator 3 is recovered from the laser resonator 3 through the exhaust duct 8, cooled by the cooler 9, and supplied again into the laser resonator 3 through the air supply duct 5.

The high voltage applied to the discharge electrodes 6 and 7 is, for example, a DC power supply 1
The output voltage of 0 is converted into a high-frequency AC voltage by alternately intermittently switching the semiconductor switching elements in the inverter circuit 11, which is boosted by the high-frequency boost transformer 12 and rectified and smoothed by the high-voltage rectifier diode 13 and the smoothing capacitor 14. High voltage DC was generated.

Problems to be Solved by the Invention Generally, discharge voltage-current characteristics in a gas laser device are as follows.
It shows a characteristic that the voltage drops from a discharge starting voltage of 30 to 50 kV to a discharge sustaining voltage of about half of the voltage with a small current, and the voltage decreases as the current further increases. If the current is further increased from this state, the discharge sustaining voltage drops sharply, leading to arc discharge in which the discharge current further increases, and the discharge current becomes unstable and the output of the laser beam fluctuates. For this reason,
In the conventional high-voltage power supply, the primary coil 12 of the step-up transformer 12 is used.
After lowering the magnetic coupling between a and the secondary coil 12b, a tertiary coil 12c having a degree of coupling with the secondary coil 12b larger than the primary coil 12a is provided to detect a voltage change generated in the secondary coil 12b. Was. For this reason, the secondary coil 1
Since the efficiency of power transmission to 2b is low and a large amount of primary current needs to flow, a large-capacity element must be used as a semiconductor switch element in the inverter circuit 11. Further, since the coupling ratio between the primary coil 12a and the tertiary coil 12c is not zero, the tertiary coil 12c may erroneously detect a change in the magnetic flux in the step-up transformer 12 due to the primary current fluctuation. As a result, the secondary voltage fluctuation at the time of transition to arc discharge cannot be detected, and the discharge in the laser resonator shifts to arc discharge, causing a problem that the discharge current becomes unstable.

The present invention solves such a conventional problem, and provides a gas laser device capable of increasing the efficiency of a high-voltage power supply of a gas laser device, stabilizing an output current, and easily performing control. The purpose is to do.

Means for Solving the Problems In order to achieve the above object, the present invention provides a high-voltage power supply configured to include a low-voltage AC power supply capable of changing an effective voltage, a step-up transformer, and a rectifier circuit. Is
The primary coil is wound inside and the secondary coil is wound outside to form a coaxial winding, and a first electrode having a dimension including at least a rectangle having the same diameter as the outer diameter of the secondary coil and its axial length is formed on the axis of the secondary coil. They are arranged in parallel and at a distance greater than the outer diameter of the secondary coil with a dielectric insulator interposed therebetween.

According to the present invention, a grounded second electrode having at least the same outer dimensions as the first electrode is disposed on the opposite side of the first electrode from the secondary coil, and the distance between the first and second electrodes is increased by the secondary coil. The distance between the first electrode and the first electrode is at most one tenth, and a dielectric having a dielectric constant at least twice that of the dielectric insulator interposed between the two coils and the first electrode is interposed between the two. At least 100 k between the first and second electrodes.
The connection is made with a resistance of Ω or more.

According to the present invention, the effective voltage of the low-voltage AC power supply is changed by an output signal of a comparison amplifier for input-comparing a voltage generated at both ends of the resistor and a reference signal voltage.

According to the present invention, with the above configuration, the entire secondary coil of the step-up transformer becomes one virtual electrode connected to a power supply that outputs the same voltage waveform as the secondary coil output voltage, and the secondary coil and the dielectric insulator A capacitor is formed by the first electrode and the first electrode. By detecting a voltage between terminals of a resistor connected to the capacitor, a change in the output voltage of the secondary coil can be detected.

According to the present invention, the secondary coil, the dielectric insulator, the first electrode, the dielectric, and the second electrode form two series capacitors, and an AC voltage is applied to the two capacitors. In each case, a divided voltage inversely proportional to the capacitance of the capacitor is generated, so that a change in the output voltage of the secondary coil can be accurately detected. The partial pressure ratio at this time is
It is inversely proportional to the distance between the first and second electrodes, and proportional to the dielectric constant of the dielectric material interposed between the electrodes. Since the two capacitors are not affected by the magnetic flux generated by the primary coil of the step-up transformer and depend only on the output voltage of the secondary coil, it is possible to accurately detect the voltage fluctuation of the discharge load. it can.

The present invention also sets the detection voltage at the time of the glow discharge as a reference voltage because the discharge load is reduced to half or less when the discharge load is in the arc discharge state as compared with the glow discharge state. An abnormality in the discharge state is detected by comparing and calculating the voltage between the terminals of the resistor connected to the second electrode. When an abnormality is detected, the effective current of the AC voltage input to the step-up transformer is reduced, the output current of the high-voltage power supply is reduced, the discharge is returned to the original glow discharge, and after returning to the glow discharge, the original output current is returned again. Up to As a result, it is possible to stabilize the laser light output while keeping the fluctuation of the discharge current small.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a boosting transformer in one embodiment of the present invention, and FIG. 2 shows a circuit configuration in one embodiment of the present invention.

In FIG. 2, reference numeral 21 denotes a low-voltage DC power supply obtained by rectifying and smoothing a commercial AC voltage of, for example, 200 V. 22 is a low voltage DC power supply
Inverter circuit (low-voltage AC power supply) for converting the output of 21 to low-voltage AC, low-voltage transformer for boosting the output of inverter circuit 22, high-voltage rectifier diode for rectifying high-frequency AC voltage, and 25 rectified A smoothing capacitor for smoothing a direct current, and a laser resonator 26 for outputting a laser beam.
27 and 28 are capacitors formed near the secondary coil of the step-up transformer 23, 29 is a resistor connected to the connection point of the capacitors 27 and 28, 30 is a low voltage rectifier diode, 31 is a comparator, 32
Is a reference voltage source, 33 is an AND gate, and 34 is a semiconductor switch element drive signal source.

In FIG. 1, a step-up transformer 23 is a ferrite core.
A primary coil 36 is wound inside one leg 35a of the base 35, and a secondary coil 37 having an outer diameter of 100 mm is wound outside the primary coil 36 at an insulating distance from the primary coil 36. The ferrite core 35 is fixed to the core holders 40a and 40b in a transformer container 39 filled with an insulating oil 38 as a dielectric insulator so that the legs 35a are oriented vertically. A glass epoxy plate 41, which is a dielectric having a thickness of about 1 mm and processed into a rectangular shape slightly larger than the vertical and horizontal dimensions of the projected shape of the secondary coil 37, is disposed in the transformer container 39. Transformer container facing parallel to the axis of coil 37
It is fixed to the inner wall surface 39a of 39 via ceramic insulators 42 and 43. The glass epoxy plate 41 is coated with copper on both sides to form a first electrode 44 and a second electrode 45, so that the distance between the first electrode 44 and the secondary coil 37 is uniformly about 100 mm to 150 mm. It is fixed to. The thickness of the glass epoxy plate 41 is limited to at most one tenth of the distance between the first electrode 44 and the secondary coil 37, and the dielectric constant of the
At least twice the dielectric constant of

As a result, the capacitor 27 shown in FIG. 2 is formed by the insulating oil 38 interposed between the secondary coil 37 and the first electrode 44,
The capacitor 28 is formed by the glass epoxy plate 41 interposed between the first electrode 44 and the second electrode 45. And the second
As shown in the figure, 100 k is applied between the first and second electrodes 44 and 45.
The resistor 29 of Ω is connected, and the second electrode 45 and the other end of the resistor 29 are both grounded. If the resistor 29 has a resistance value of about 100 kΩ or less, the discharge time constant by the resistor 29 is shorter than the charge stored in each of the capacitors 27 and 28, and the voltage waveform is not proportional to the output voltage of the secondary coil. The value of 29 should be at least 100 kΩ or more.

The first electrode 44 is connected to one input of the comparator 31 via the low voltage rectifier diode 30, and the other input of the comparator 31 is connected to the reference voltage source 32. The semiconductor switch element in the inverter circuit 22 is driven by a signal from the semiconductor switch element drive signal source 34,
An AND gate 33 that uses the output of 31 as a control signal is relayed.

Next, the operation of the above embodiment will be described. In FIG. 2, a low-voltage DC power supply 21 rectifies and smoothes a commercial power supply and outputs a low-voltage DC to an inverter circuit 22. The inverter circuit 22 generates an AC voltage by intermittently switching the semiconductor switch element in the inverter circuit 22 with a signal from the semiconductor switch element drive signal source 34, and changes the AC frequency by changing the cycle of the intermittent cycle, thereby connecting the same. The effective voltage is changed by changing the time. The high-frequency voltage output from the inverter circuit 22 is boosted by the step-up transformer 23, the output of the secondary coil 37 is rectified by the high-voltage rectifier diode 24, smoothed by the smoothing capacitor 25, and discharged by the discharge electrodes 26a, Applied to 26b.

The voltage applied to the capacitors 27 and 28 connected in series is
The output voltage of the secondary coil 37 of the step-up transformer 23, which is an AC voltage, is drooped by the load current flowing through the laser resonator 26, and the effective voltage matches the discharge voltage. In this embodiment, the shared voltage of the series capacitors 27 and 28 is about 100 to 1 depending on the distance between the first and second electrodes 44 and 45, the insulating oil 38 which is a dielectric insulator, and the dielectric constant of the glass epoxy plate 41. A low voltage proportional to the discharge voltage is generated in the capacitor 28 at a ratio of 200: 1. The voltage generated by the reference voltage source 32 is
26 is set so as to be adjusted to about 90% of the voltage shared by the capacitor 28 when the discharge state of the glow discharge is normal. Capacitor
Since the shared voltage of 28 becomes an AC voltage, it is rectified to DC by the low voltage rectifier diode 30 and then input to the comparison calculator 31. The resistor 29 is connected to the comparator 28 from the capacitor 28 that is the signal source.
It determines the input resistance to the comparator 31 and protects the comparator 31 when an abnormal voltage is generated in the first and second electrodes 44 and 45. The comparison calculator 31 generates a positive voltage when the voltage of the DC signal rectified by the low-voltage rectifier diode 30 is higher than the voltage of the reference voltage source 32, but has a zero voltage when the voltage is lower. The AND gate 33 opens the gate when the gate signal from the comparator 31 has a positive voltage and passes the pulse signal from the semiconductor switch element drive signal source 34, but closes the gate when the gate signal has a zero voltage. Therefore, when the discharge in the laser resonator 26 becomes an arc discharge and the voltage drops, the comparator 31 detects a voltage lower than the reference voltage source 32 and outputs a zero voltage, and the AND gate 33 closes the gate. Thus, the output from the semiconductor switch element drive signal source 34 is prevented from being transmitted to the inverter circuit 22, and the discharge current of the laser resonator 26, which has become arc discharge, is cut off. In addition,
Since the voltage applied to the capacitors 27 and 28 depends not on the current flowing through the primary coil 36 but on the voltage generated in the secondary coil 37, no malfunction occurs due to the waveform of the current flowing through the primary coil 36. Also, a primary coil 36 and a secondary coil 37
It is not necessary to reduce the degree of coupling between the step-up and the step-up to generate a leakage magnetic flux, so that the power transfer efficiency of the step-up transformer 23 is high.

As described above, according to the embodiment, the boosting transformer 23
A capacitor is formed by the secondary coil 37, the insulating oil 38, and the first electrode 44.
27, the first electrode 44, the glass epoxy plate 41, and the second electrode 45 form the capacitor 28, and the first electrode 44 and the second electrode
The resistor 29 is connected to the electrode 45, the second electrode 45 is grounded, and the voltage between the terminals of the resistor 29 is used as one input of the comparator 31. The other input of the comparator 31 is connected to a reference voltage source. 32, the signal from the semiconductor switch element drive signal source 34 to the semiconductor switch element of the inverter circuit 22 is controlled through the AND gate 33 by the output of the comparator 31. , The fluctuation of the output voltage of the secondary coil 37 can be accurately detected, and the inverter circuit 22 can be appropriately controlled, thereby increasing the efficiency of the high-voltage power supply of the gas laser device and stabilizing the output current. Control can be facilitated.

As described above, according to the gas laser device of the present invention, the high-voltage power supply is configured to include the low-voltage AC power supply capable of changing the effective voltage, the step-up transformer, and the rectifier circuit. The primary coil is wound inside and the secondary coil is wound outside to form a coaxial winding, and a first electrode having a size including at least a rectangle having the same size as the outer diameter of the secondary coil and its axial length is provided.
Since a dielectric insulator is interposed in parallel with the axis of the secondary coil and at a distance equal to or greater than the outer diameter of the secondary coil, the step-up transformer detects the voltage fluctuation of the secondary coil. There is no need to wind a tertiary coil, and erroneous detection due to fluctuations in the primary current can be prevented. Further, since it is not necessary to reduce the degree of coupling between the primary coil and the secondary coil to generate the leakage magnetic flux, it is possible to increase the power transmission efficiency of the step-up transformer.

The present invention also provides a grounded second electrode having at least the same external dimensions as the first electrode, which is disposed on the opposite side of the first electrode from the secondary coil, and wherein the distance between the first and second electrodes is a secondary coil. The distance between the first coil and the first electrode is at most one-tenth, and the dielectric material has a dielectric constant at least twice that of the dielectric insulator interposed between the secondary coil and the first electrode. And a distance of at least 10 between the first and second electrodes.
Since the connection is made with a resistance of 0 kΩ or more, two series capacitors are formed by the secondary coil, the dielectric insulator, the first electrode, the dielectric, and the second electrode. Can be accurately detected.

According to the present invention, the effective voltage of the low-voltage AC power supply is changed by the output signal of the comparison amplifier that compares the voltage generated at both ends of the resistor with the reference signal voltage.
It is possible to accurately detect fluctuations in the output voltage of the secondary coil and perform appropriate control, improve the efficiency of the high-voltage power supply of the gas laser device, and stabilize the output current to achieve a stable laser output. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a step-up transformer of a gas laser device according to one embodiment of the present invention. FIG. 2 is a circuit configuration diagram of a high-voltage power supply of the gas laser device according to one embodiment of the present invention.
FIG. 1 is a schematic configuration diagram showing an example of a conventional gas laser device. 21 …… Low voltage DC power supply, 22 …… Inverter circuit (Low voltage AC power supply), 23 …… Step-up transformer, 24 …… High voltage rectifier diode, 25 …… Smoothing capacitor, 26 …… Laser resonator,
27,28 …… Capacitor, 29 …… Resistance, 30 …… Low voltage rectifier diode, 31 …… Comparator, 32 …… Reference voltage source, 33…
... AND gate, 34 ... Semiconductor switch element drive signal source, 35 ... Ferrite core, 36 ... Primary coil, 37 ...
Secondary coil, 38 ... Insulating oil, 39 ... Transformer container, 40a,
40b …… Core holder, 41… Glass epoxy board, 42,43…
... ceramic insulator, 44 ... first electrode, 45 ... second electrode.

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

Claims (3)

(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 is capable of changing an effective voltage. A low-voltage AC power supply, a step-up transformer, and a rectifier circuit, wherein the step-up transformer has a coaxial winding in which a primary coil is wound inside and a secondary coil is wound outside,
At least a first electrode having a dimension including a rectangle having the same size as the outer diameter of the secondary coil and its axial length is placed in parallel with the axis of the secondary coil and at a distance equal to or greater than the outer diameter of the secondary coil. A gas laser device, wherein a dielectric insulator is interposed, and the first electrode is connected to a ground potential with a resistance of at least 100 kΩ or more. 2. A step-up transformer having a grounding second electrode having at least the same outer dimensions as the first electrode.
The distance between the first electrode and the second electrode is set to be at most 1/10 of the distance between the secondary coil and the first electrode, and the distance between the first electrode and the second electrode is A dielectric having a dielectric constant of at least twice the dielectric constant of a dielectric insulator interposed between the secondary coil and the first electrode is interposed between the second electrode and the first electrode. 2. The gas laser device according to claim 1, wherein a resistance of at least 100 kΩ is connected between the second electrode and the second electrode. 3. An effective voltage of a low-voltage AC power supply is changed by an output signal of a comparison amplifier having a voltage generated at both ends of a resistor as an input at one end and a reference signal voltage as an input at the other end. The gas laser device according to (2).