JPH0439980A - Laser oscillator - Google Patents

Abstract

PURPOSE:To relieve the output power of a power source from its dependence on the voltage of the power source and stabilize the output of laser by detecting AC voltage of the power source and controlling the switching frequency in conformity with the magnitude of fluctuations in a reference signal. CONSTITUTION:When the AC voltage of a power source fluctuates, the fluctuations are detected by a voltage converter 21, a rectifier 22, and a smoothing capacitor 23 and enter an error amplifier 24. As the reference voltage of a reference voltage signal generation circuit 25 enters the error amplifier 24, the differential voltage is input into a switching frequency setting circuit 18 where the circuit 18 increases and reduces the switching frequency by the portion of differential voltage to the reference voltage so as to unify the power and outputs the controlled power. A drive circuit 18 switches a switching device based on the switching frequency and switching on time fixed from an output setting circuit 19, The output power from the switching power source is stabilized so that the output of laser may not depend on the AC voltage of the power source.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser oscillator that generates laser light for cutting, welding, heat treatment, and the like.

2. Description of the Related Art The structure of a typical laser oscillator will be explained with reference to FIG. A discharge tube group l consisting of one or more discharge tubes has an IMi consisting of an anode 2 and a cathode 3 for each discharge tube.
It is equipped with discharge electrodes.

In FIG. 1, two sets of discharge tubes are arranged symmetrically to form a discharge section, each of which is supplied with current from the city voltage line R4. Furthermore, an output mirror 5 and an end mirror 6 are arranged at both ends of the discharge tube group 1 to form an optical resonator. Furthermore, the vicinity of the cathode electrodes 3.3 at both ends of the discharge tube group 1 and the anode electrode 2 at the center are connected by a substantially E-shaped circulation tube body 7 to form a gas circulation path. This circulation pipe body 7 is provided with an air blower IIB for circulating gas and a heat exchanger 9 for cooling the gas. Further, the discharge tube group L includes a discharge starting auxiliary ring 10 or a discharge starting auxiliary tube electrically connected to the anode 2 or the cathode 3 on the outer periphery of the discharge tube between the anode 2 and the cathode 3 for each discharge tube. 10 are provided.

FIG. 5 is a block diagram showing the configuration of a conventional switching high voltage power supply 4. As shown in FIG. After receiving and rectifying the three-phase 200V with the rectifier stack 11, the voltage ripple is reduced with the primary side smoothing capacitor 12, the switching element 13 switches and converts it into a pulse signal, and the power is transmitted to the high frequency transformer 15. The high-frequency transformer 15 transmits power to the secondary side and generates a high voltage on the secondary side, and the high-speed high-voltage rectifier 1
After rectification at 6, smoothing is performed at a high-voltage capacitor 17, and a voltage is applied between the anode 2 and cathode 3 of the discharge tube 1.

On the other hand, the signal of the switching frequency setting circuit (FM circuit) 1B that sets the reference switching frequency and the signal of the output setting circuit 19 (PWM circuit) that determines the switching-on time based on the command from the output command setting circuit 20 are In response, the drive circuit 14 determines the switching on time and switching frequency, generates a drive signal, and sends it to the gate of the switching element 13.

In a laser oscillator configured in this way, the gas flow direction, the discharge direction, and the laser beam oscillation axis are coaxial, so when viewed from the optical axis direction, the discharge and the gain distribution formed by the discharge are concentric. It has good symmetry. Therefore, it is said that the machining performance is good when machining is performed using the output laser light.

Problems to be Solved by the Invention However, there has been a problem in that when the power supply voltage fluctuates, the output power on the secondary side fluctuates accordingly, and the laser output also fluctuates.

The present invention takes into consideration the problems of conventional laser oscillators, and provides a laser oscillator in which even if the power supply voltage fluctuates, the output power on the secondary side does not fluctuate accordingly, and the laser output also does not fluctuate. With the goal.

SUMMARY OF THE INVENTION The present invention provides a discharge group of one or more discharge tubes with a discharge electrode having an anode and a cathode, and a switching high-voltage device having a switching element and supplying power to the discharge tube. a power source, mirrors for laser resonance disposed at both ends of the discharge group, a circulation tube connected to the discharge group near the discharge electrode and forming a gas circulation path together with the discharge group, and the gas circulation In a laser oscillator equipped with a gas supply device that supplies gas as a laser medium to a path, voltage detection detects the voltage of an AC power source of the switching high voltage power source that can adjust the output power by changing the switching on time. The laser oscillator is characterized in that the laser oscillator has means for controlling the output power by changing the switching frequency of the switching element in accordance with the voltage detected by the voltage detecting means.

Operation The present invention is capable of adjusting the output power by changing the switching-on time, and detects the voltage detected by the voltage detection means for detecting the voltage of the AC power supply of the switching high-voltage power supply that supplies power to the discharge group of the laser oscillator. In response to
The output power is controlled by changing the switching frequency of the switching element of the switching high-voltage power supply.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram of a switching high voltage power supply according to an embodiment of the present invention. In the figure, a voltage converter 21 is a means for converting the alternating voltage of an AC AC power source, a rectifier 22 is a means for rectifying the output of the voltage converter 21, and a smoothing capacitor 2
3 is that! It is a means for smoothing the applied voltage. Further, the reference voltage signal generation circuit 25 is a circuit that outputs a predetermined reference voltage, and the error amplifier 24 manually inputs the reference voltage signal and the output signal from the smoothing capacitor 23, and the difference between the two is It is a means of amplifying the

The switching frequency setting circuit (FM) 1B is a means for manually inputting the amplified difference signal and generating a switching frequency signal corresponding to the amplified difference signal. Note that the voltage converter 21
, the rectifier 22, and the smoothing capacitor 23 are examples of voltage detection means. Discharge tube 1, anode 2, cathode 3, rectifier stack 11. Primary side smoothing capacitor 12, switching element 1
3, drive circuit 14, high frequency transformer 15, high speed high voltage rectifier 16, high voltage capacitor 17, output setting circuit 19,
The output command setting circuit 20 is the same as that shown in FIGS. 1 and 5, and therefore a description thereof will be omitted.

Next, the main operations of the present invention will be explained.

Figure 3 shows when the power supply voltage of the switching high voltage voltage R4 swings to the + side with respect to the reference voltage (A), and when the reference voltage is applied (B)
An example of the control signal generated in the drive circuit 14 when the voltage swings to the negative side (C) is shown. As is clear from FIG. 3, when the AC voltage of the power supply decreases, the voltage converter 21
The rectifier 22 and smoothing capacitor 23 detect this. Then, the error amplifier 24 is manually inputted. On the other hand, since the reference voltage of the reference voltage signal generation circuit 25 is inputted to the error amplifier 24, the drop difference thereof is inputted to the switching frequency setting circuit 18. Therefore, the switching frequency setting circuit 18 increases the switching frequency by the voltage drop with respect to the reference voltage and outputs it so that the power remains constant. The drive circuit 14 switches the switching element 13 at its switching frequency and a fixed switching on time from the output setting circuit 19. Further, when the voltage of the AC power source increases, the switching frequency is similarly lowered by the voltage increase relative to the reference voltage, and the output power is controlled to be constant.

Next, FIG. 4 compares the relationship between the variation rate of the AC voltage of the power supply and the variation rate of the output power in the case of using the present invention and the case of the conventional method. As is clear from Fig. 4, by detecting the voltage of the power supply and controlling the switching frequency according to the fluctuation range with respect to the reference signal, the output power from the switching power supply becomes stable, and the laser output Becomes independent of voltage.

In this way, by detecting the AC voltage of the power supply and controlling the switching frequency according to the fluctuation range with respect to the reference signal,
The output power from the power supply does not depend on the voltage of the power supply, and the laser output is also stabilized.

As is clear from the detailed description of the invention, by using the present invention, the laser output does not fluctuate even if the power AC voltage fluctuates, and the reliability of laser processing can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the configuration of an embodiment of the laser oscillator according to the present invention, FIG. 2 is a block diagram showing the circuit configuration of the same embodiment, and FIG. 3 shows the AC voltage of the power supply relative to the reference voltage. Figure 4 is a graph showing the control signals generated in the drive circuit of the same embodiment when the voltage swings to the + side (A), when the reference voltage swings to the - side (B), and when it swings to the - side (C). FIG. 5 is a graph showing the relationship between the variation rate of the power supply voltage and the variation rate of the output power in the case of the invention and the conventional case. FIG. 5 is a block diagram showing the circuit configuration of a conventional laser oscillator. l...discharge tube group, 2...anode, 3...cathode, 4...
...High voltage power supply, 5...Output mirror 6...Terminal mirror 7...Circulation tube body, 8...Blower, 9...Heat exchanger, lO...Discharge start auxiliary ring, 11... Rectifier stack, 12... Primary side smoothing capacitor, 13...
・Switching element, 14... Drive circuit, 15.
...High frequency transformer, 16...High speed high voltage rectifier, 17
...High voltage capacitor, 18...Switching frequency setting circuit, 19...Output setting circuit (PWM circuit), 2
0... Output command setting circuit, 21.22.23... Voltage detection means, 24... Error amplifier. Agent Patent Attorney Matsu 1) Tadashi Michi No. 0: Discharge starting auxiliary ring No. 3 Fig. No. 1 Rainbow 5 originals" Moxibustion! So-〇4t(0n) diagram

Claims (1)

[Claims] A discharge group of one or more discharge tubes each having a discharge electrode having an anode and a cathode, a switching high-voltage power supply having a switching element and supplying power to the discharge tubes, and a switching high voltage power supply provided at both ends of the discharge group. a mirror for laser resonance; a circulation tube connected to the discharge group near the discharge electrode and forming a gas circulation path together with the discharge group; and a gas supplying gas as a laser medium to the gas circulation path. In the laser oscillator, the laser oscillator includes a voltage detection means for detecting the voltage of the AC power supply of the switching high-voltage power supply that can adjust the output power by changing the switching-on time, and the voltage detection means detects the voltage of the AC power supply. A laser oscillator characterized in that the output power of the switching element is controlled by changing the switching frequency of the switching element in accordance with the applied voltage.