JPH0439978A - Laser oscillator - Google Patents

Abstract

PURPOSE:To stabilize output power from a switching power source by detecting a terminal to terminal voltage of a primary side capacitor of a switching high voltage power source and controlling switching on time in conformity with the magnitude of fluctuations in a reference signal. CONSTITUTION:A voltage detector 21 detects a terminal to terminal voltage of a primary side smoothing capacitor 12 of a switching high voltage power source and inputs the detected value into an error amplifier 22. As the reference voltage of a reference voltage signal generation circuit 24 is input into the amplifier 22, differential voltage enters an output setting circuit 28. The circuit 28 controls the switching on time of a switching low voltage power source by the differential voltage to the reference voltage so that the power may be fixed and output. A drive circuit 23 switches a switching device 25 based on a switching frequency fixed from a switching frequency setting circuit 29. Therefore, the output power from the switching voltage power source does not rely on the terminal to terminal voltage of the primary side capacitor of the switching high voltage 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 1 consisting of one or more discharge tubes is provided with a set of discharge electrodes consisting of an anode 2 and a cathode 3 for each discharge tube.

In FIG. 1, two sets of discharge tubes are arranged symmetrically to form a discharge section, and a current is supplied to each from a high voltage power supply 4. 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. Further, 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 includes a blower 8 that circulates the gas and a heat exchanger 9 that cools the gas.
is installed. 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. 8 is a block diagram showing the configuration of a conventional switching high voltage voltage R4. After rectifying the three-phase signal 200 in the rectifier stack 11, the voltage level is reduced by the primary smoothing capacitor 12, and the switching element 13 converts the signal into a pulse signal, which transmits the power 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, which is rectified by a high-speed high-voltage rectifier 16, smoothed by a high-voltage capacitor 17, and then connected between the anode 2 and cathode 3 of the discharge tube l. A voltage is applied.

On the other hand, the signal of the switching-on time setting circuit 18 that sets the reference switching-on time and the output command setting circuit 2
Output setting circuit 19 that determines the switching frequency based on the command from 0. (FM circuit), 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 voltage between the terminals of the smoothing capacitor on the primary side fluctuates, the output power on the secondary side fluctuates accordingly, and the laser output also fluctuates.

The present invention has been developed in consideration of such problems with conventional laser oscillators, and even if the voltage between the terminals of the smoothing capacitor on the primary side fluctuates, the output power on the secondary side does not change accordingly, and the laser output The object of the present invention is to provide a laser oscillator that does not fluctuate.

Means for Solving the Problems The present invention provides a discharge group of one or more discharge tubes with a discharge electrode having an anode and a cathode, a switching high voltage 1iR for supplying power to the discharge tubes, and a mirrors for laser resonance disposed at both ends of the group; a circulation pipe connected to the discharge group near the discharge electrode and forming a gas circulation path together with the discharge group; A laser oscillator equipped with a gas supply device for supplying a gas, the laser oscillator having a rectifying means, a smoothing capacitor, and a switching element on the upstream side of the switching high-voltage power supply that can adjust the output power by changing the switching frequency. Further, the primary side smoothing capacitor of the switching high voltage power supply has voltage detection means for detecting the voltage between its terminals, and the maximum switching of the switching high voltage power supply is determined in response to the voltage detected by the voltage detection means. The laser oscillator is characterized in that its output power is controlled by changing the switching-on time of the switching element using a switching frequency that is twice or more of the laser oscillator frequency.

The present invention also provides 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 for 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. A laser oscillator equipped with a supply device includes a rectifying means, a smoothing capacitor, and a switching element on the upstream side of the switching high-voltage power supply that can adjust the output power by changing the switching frequency, and further includes a rectifier, a smoothing capacitor, and a switching element. The primary side smoothing capacitor of the power supply has a voltage detection means for detecting the voltage between its terminals, and in response to the voltage detected by the voltage detection means, the switching frequency is twice or more of the maximum switching frequency of the switching high voltage power supply. The laser oscillator is characterized in that the output power of the switching element is controlled by changing the switching frequency of the switching element, with H being the lower limit operating frequency of the switching frequency.

The present invention is a primary side smoothing capacitor of a switching high voltage power supply that supplies power to a discharge group of a laser oscillator, which can adjust the output power by changing the switching frequency, and detects the voltage between its terminals. In response to the voltage detected by the voltage detection means, the switching-on time of a switching element provided upstream of the switching high-voltage power supply is varied with a switching frequency of at least twice the maximum switching frequency of the switching high-voltage power supply. Then, the output power control is performed.

The present invention also provides a smoothing capacitor on the primary side of a switching high-voltage power supply that supplies power to a discharge group of a laser oscillator, which can adjust the output power by changing the switching frequency, and detects the voltage between its terminals. In response to the voltage detected by the voltage detection means, the switching frequency of the switching element provided on the upstream side of the switching high-voltage power supply is set to a lower limit operating frequency of at least twice the maximum switching frequency of the switching high-voltage power supply. The output power control is performed by changing the output power as follows.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing one embodiment of the present invention. In the same figure, as is clear when compared with FIG. 8, a switching low voltage power supply mainly consisting of a rectifier 27 as an example of rectifying means, a smoothing capacitor 26, and a switching element 25 is connected to the upstream side of the switching high voltage power supply 4. .

On the other hand, the primary side smoothing capacitor 1 of the switching high voltage power supply
A voltage detector 21 as an example of voltage detection means is connected to 2 and detects the voltage between its terminals. Further, the detected voltage is induced into the error amplifier 22. The error amplifier 22 compares the reference voltage of the reference voltage signal generation circuit 240 with the detected voltage, amplifies the error, and outputs it to the output setting circuit 2B (PWM circuit) of the switching low voltage power supply. The output setting circuit 28 is a circuit that controls switching-on time. Further, the switching frequency setting circuit 29 in the switching low voltage power supply is a circuit that outputs a fixed switching frequency setting value. The drive circuit 23 manually inputs the switching-on time setting value generated by the output setting circuit 28 and the fixed switching frequency setting value from the switching frequency setting circuit 29, and based on these, the switching element 25 in the switching low-voltage power supply is designed to be controlled.

Note that the switching frequency at this time is more than twice the maximum switching frequency of the switching high voltage power supply.

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

Figure 3 shows the case where the voltage between the terminals of the primary smoothing capacitor 12 of the switching high voltage power supply 4 is on the positive side with respect to the reference voltage (A), the case where it is at the reference voltage (B), and the case where it is on the negative side ( C), drive circuit 2 in the switching low voltage power supply
An example of the control signal generated in 3 is shown below. As is clear from FIG. 3, when the voltage between the terminals of the primary smoothing capacitor 12 of the switching high voltage power supply decreases, the voltage detector 21 detects it. Then, the error amplifier 22 is manually inputted. On the other hand, since the reference voltage of the reference voltage signal generation circuit 24 is inputted to the error amplifier 22, the difference in drop is inputted to the output setting circuit 28. Therefore, the output setting circuit 28 extends the switching-on time of the switching low-voltage power supply by the voltage drop with respect to the reference voltage so that the power becomes constant and outputs the power.

The drive circuit 23 switches the switching element 25 using its switching time and the fixed switching frequency from the switching frequency setting circuit 29. Furthermore, when the voltage between the terminals of the primary smoothing capacitor 12 of the switching high-voltage power supply increases, the switching-on time of the switching low-voltage power supply is similarly controlled by the voltage increase relative to the reference voltage to keep the output power constant.

Next, FIG. 4 compares the relationship between the variation rate of the voltage between the terminals of the primary side smoothing capacitor 12 of the switching high-voltage power supply 4 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 this figure 4,
By detecting the voltage between the terminals of the primary side capacitor 12 of the switching high-voltage power supply 4 and controlling the switching on time 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 stable during switching. It becomes independent of the voltage between the terminals of the primary side smoothing capacitor 12 of the high voltage power supply.

In this way, by detecting the voltage between the terminals of the primary smoothing capacitor 12 of the switching high-voltage power supply and controlling the switching-on time of the switching low-voltage power supply according to the fluctuation width with respect to the reference signal, the output power from the switching high-voltage power supply can be adjusted. Primary side smoothing capacitor 12 of switching high voltage power supply
The laser output is also stabilized without depending on the voltage between the terminals.

Another embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a block diagram showing one embodiment of the present invention. In the same figure, as is clear when compared with FIG. 8, a switching low-voltage power supply mainly consisting of a rectifier 27 as an example of rectifying means, a smoothing capacitor 26, and a switching element 25 is connected to the upstream side of the switching high-voltage power supply 4. There is. On the other hand, a voltage detector 21 as an example of voltage detection means is connected to the primary side smoothing capacitor 12 of the switching high voltage power supply, and detects the voltage between its terminals. Further, the detected voltage is induced into the error amplifier 22. The error amplifier 22 includes a reference voltage signal generation circuit 240
The reference voltage and the detected voltage are compared, and the error is amplified and output to the output setting circuit 30 (FM circuit) of the switching low voltage power supply. Its output setting circuit 30
is a circuit that controls the switching frequency. Furthermore, the switching-on time setting circuit 31 in the switching low-voltage power supply is a circuit that outputs a fixed switching-on time setting value. The drive circuit 23 manually inputs the switching-on frequency (1a) generated by the output setting circuit 30 and the fixed switching-on time setting value from the switching-on time setting circuit 31, and controls the switching in the switching low-voltage power supply based on this. The output power of the switching element 254 is controlled by changing the switching frequency of the switching element 25 with the lower limit operating frequency of the switching frequency set to twice or more the maximum switching frequency of the switching high voltage power supply. is being carried out.

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

Figure 6 shows a case where the voltage between the terminals of the primary smoothing capacitor 12 of a switching high voltage r1.4 swings to the + side with respect to the reference voltage (A), a case where the voltage swings to the - side at the reference voltage (B), and a case where the voltage swings to the - side with respect to the reference voltage (A). In case (C), an example of the control signal generated by the drive circuit 23 in the switching low-voltage power supply is shown. As is clear from FIG. 6, when the voltage across the terminals of the primary side smoothing capacitor 12 of the switching high voltage power supply decreases, the voltage detector 2
1 detects it. Then, the error amplifier 22 is manually inputted. On the other hand, since the reference voltage of the reference voltage signal generation circuit 24 is input to the error amplifier 22, the difference in voltage drop is input to the output setting circuit 30. Therefore, the output setting circuit 30
The switching frequency of the switching low-voltage power supply is increased by the voltage drop relative to the reference voltage so that the power is constant. The drive circuit 23 drives the switching element 2 at its switching frequency and the fixed switching on time from the switching on time setting circuit 31.
Switching 5. Also, one of the switching high voltage power supplies
When the voltage between the terminals of the next-side smoothing capacitor 12 increases, the switching frequency of the switching low-voltage power supply is similarly controlled to be lowered by the voltage increase relative to the reference voltage so that the output power is constant.

Next, FIG. 7 compares the relationship between the variation rate of the voltage between the terminals of the primary side smoothing capacitor 12 of the switching high-voltage power supply 4 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 this figure 7,
By detecting the voltage between the terminals of the primary side capacitor 12 of the switching high voltage power supply R4 and controlling the switching frequency according to the fluctuation width with respect to the reference signal, the output power from the switching power supply becomes stable, and the laser output is adjusted to the switching high voltage. It becomes independent of the voltage between the terminals of the primary side smoothing capacitor 12 of the power supply.

In this way, by detecting the terminal r:I voltage of the primary side smoothing capacitor 12 of the switching high-voltage power supply and controlling the switching frequency of the switching low-voltage power supply according to the fluctuation range with respect to the reference signal, the output power from the switching high-voltage power supply can be controlled. is the primary side smoothing capacitor 1 of the switching high voltage power supply
The laser output is also stabilized without depending on the voltage between the two terminals.

As is clear from the detailed explanation of the invention, by using the invention, the laser output does not fluctuate even if the voltage across the terminals of the primary side smoothing capacitor fluctuates, significantly improving the reliability of laser processing. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing the configuration of an embodiment of the laser oscillator according to the invention, Fig. 2 is a Bucock diagram showing the circuit configuration of the same embodiment, and Fig. 3 is a primary side of a switching high-voltage power supply. Occurs in the drive circuit in the switching low-voltage power supply when the voltage between the terminals of the smoothing capacitor swings to the positive side with respect to the reference voltage (A), at the reference voltage (B), and when it swings to the negative side (C). FIG. 4 is a graph showing the control signals of the switching high voltage power supply in the case of the present invention and in the conventional case.
A graph showing the relationship between the variation rate of the voltage between the terminals of the next-side smoothing capacitor and the variation rate of the output power, FIG. 5 is a block diagram showing the circuit configuration of another embodiment of the laser oscillator according to the present invention, and FIG. 6 The voltage between the terminals of the primary smoothing capacitor of a switching high-voltage power supply swings to the + side with respect to the reference voltage (A), at the reference voltage (B), and when it swings to the - side (C).
) is a graph showing the control signal generated in the drive circuit in the switching low-voltage power supply, and Figure 7 shows the fluctuation rate of the voltage between the terminals of the primary side smoothing capacitor of the switching high-voltage power supply and the output for the case of the present invention and the conventional case. FIG. 8 is a graph showing the relationship between power fluctuation rates and is a block diagram showing the circuit configuration of a conventional laser oscillator. 1... Discharge tube group, 2... Anode, 3... Cathode, 4...
...High voltage power supply, 5...Output mirror 6...Terminal mirror 7...Circulation pipe body, 8...Blower, 9...Heat exchanger, lO...Discharge start auxiliary ring, 11 ... Rectifier stack, 12... Any-order smoothing capacitor, 13... Switching element, 14... Drive circuit, 15...
High frequency transformer, 16...High speed high voltage rectifier, I7...
・High voltage capacitor, 18... Open setting circuit when switching on, 19... Output setting circuit (FM circuit), 2o・
. . . Output command setting circuit, 21 . . . Voltage detection means, 22
...Error amplifier, 23.. Switching low voltage power supply drive circuit, 24.. Reference voltage signal generation circuit, 25.
...Switching low voltage power supply switching element, 26...
・Smoothing capacitor, 27... Rectifier means, ', 28...
・Switching low voltage power supply output setting circuit (PWM circuit),
29...Switching low voltage power supply switching frequency setting circuit, 30...Output setting circuit (FM circuit'#J), 3
1...Switching-on time setting circuit. Agent Patent Attorney Matsu 1) Tadashi Michi No. 0: Discharge starting auxiliary ring No. 0: Discharge starting auxiliary ring no.閤t7s-1h /l II &('10) Fig. 8]b 7

Claims (2)

[Claims] (1) A discharge group of one or more discharge tubes equipped with a discharge electrode having an anode and a cathode, a switching high-voltage power supply that supplies power to the discharge tubes, and a laser resonance installed at both ends of the discharge group. a circulation pipe body connected to the discharge group near the discharge electrode and forming a gas circulation path together with the discharge group; and a gas supply device for supplying gas as a laser medium to the gas circulation path. A laser oscillator comprising: a rectifying means, a smoothing capacitor, and a switching element on the upstream side of the switching high-voltage power supply capable of adjusting the output power by changing the switching frequency; The next-side smoothing capacitor has a voltage detection means for detecting the voltage between its terminals, and the switching frequency is set to at least twice the maximum switching frequency of the switching high-voltage power supply in response to the voltage detected by the voltage detection means. , by changing the switching on time of the switching element,
A laser oscillator characterized by controlling its output power. (2) A discharge group of one or more discharge tubes equipped with a discharge electrode having an anode and a cathode, a switching high-voltage power supply that supplies power to this discharge tube, and a laser resonance installed at both ends of the discharge group. a circulation pipe body connected to the discharge group near the discharge electrode and forming a gas circulation path together with the discharge group; and a gas supply device for supplying gas as a laser medium to the gas circulation path. A laser oscillator comprising: a rectifying means, a smoothing capacitor, and a switching element on the upstream side of the switching high-voltage power supply capable of adjusting the output power by changing the switching frequency; The next-side smoothing capacitor has a voltage detection means for detecting the voltage between its terminals, and in response to the voltage detected by the voltage detection means, the switching frequency is set to at least twice the maximum switching frequency of the switching high voltage 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 as the lower limit operating frequency.