JPH04123483A - Laser output controller - Google Patents

Abstract

PURPOSE:To improve transient output response of a laser beam and static output stability by selecting any of a deviation signal between a laser output feedback signal and an output set signal and an output signal of a discharge current setter by a set signal converter according to a switching timing signal output from timing generating means when a control type selecting switch selects an output control, and outputting it to a power source. CONSTITUTION:Timing generating means 16 is composed of a circuit connected to the output unit of an output setter 11 and the output unit of an output detector 9 to calculate the set output value and the detected output value. For example, if the detected output value reaches 80% of the set output value at the time of rising of the output, a signal is output to a set signal converter 140, the converter 140 receives the signal and switches the two input signals. Accordingly, a control system in which a current control is temporarily used at the rise of the output, at the abrupt change of the output set value and the output control is used in a steady state, can be simply realized. Thus, a laser output controller in which transient output response is improved and excellent static output stability is obtained is provided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an output control device for a laser oscillator used in laser processing, etc., and in particular, output control to keep the output constant and current control to keep the discharge current constant. This invention relates to a laser output control device that can perform control by dynamically switching between.

[Prior Art] FIG. 6 is a block diagram showing the configuration of a conventional laser output control device. In the figure, (1) is a laser oscillator, (
2) is a power supply that supplies discharge power (3A).

(3B) is the electrode, (4) is the laser medium gas, and (5) is the electrode that receives power from the power source (2) (3A), (3B).
(6) is a total reflection mirror, (7) is a partial transmission mirror, (8ε is a laser beam oscillated from a laser oscillator (1), and (8a) is extracted from a total reflection mirror (6). A portion of the laser beam (8)σ, (9) is a portion of the laser beam (8)
a) an output detector for inputting and converting it into an electrical signal, (10
) is the output electrical signal of the output detector (9), which is called the laser output feedback signal. (11) is an output setting device for setting the desired laser output, (12) is an error amplifier, (13) is a discharge current setting device for setting the discharge current to be supplied to the discharge (5), and (15) is a control method selection. switch,
(]4) is an error amplifier (12), a discharge current setting device (13)
) and a control method selection switch (15), and its output is connected to the power source (2).

Next, the operation will be explained. In Fig. 6, (1) is a laser oscillator, and electric power supplied from a power source (2) causes a discharge (5) between electrodes (3A) and (3B), filling the laser oscillator (1). The laser medium gas (4) that is present is excited. A total reflection mirror (6) and a partial transmission mirror (7) sandwich this excited laser medium gas (4).
These elements constitute an optical resonator, and a laser beam (8) is oscillated. Laser light (8
) is output to the outside from the partially transmitting mirror (7). On the other hand, part of the laser beam (8) output from the total reflection mirror (6) to the outside
A) is input to an output detector (9), and the second output detector (9) outputs an electric signal proportional to the intensity of the laser beam (8) as a laser output feedback signal (10).

The difference between this laser output feedback signal (lO) and the output signal of the output setter (11) is determined by the error amplifier (12).
The signal is amplified by and output to the setting signal switch (14) as a deviation signal between the two signals.

On the other hand, the control method selection switch (15) is used to select the control method for the laser oscillator (1). For example, when selecting a method for controlling the output of the laser beam (8) at a constant level, turn this switch on ( (hereinafter referred to as ON), and discharge (
5) When selecting a method of controlling the discharge current supplied to the device at a constant level, turn this switch off (hereinafter referred to as OFF)
shall be.

Then, when the control method selection switch (I5) is ON, the setting signal switch (14) selects the input signal from the error amplifier (12) from among the two input signals and outputs it to the power supply (2). . Conversely, the control method selection switch (15
) is OFF, the input signal from the discharge current setter (13) is selected from the two input signals and output to the power source (2).

FIG. 7 is a circuit diagram showing an example of the logic circuit of the setting signal switch (14), in which the control method selection switch (15) is turned ON.
, the output of the inverter (14A) becomes "H" level, the first analog switch (14B) is turned on, and the output of the error amplifier (12) is transmitted to the power supply (2).
As a result, output control is performed. At this time, the second analog switch (14c) is OFF.

When the control method selection switch (I5) is turned OFF, the second
The analog switch (14C) is turned on, and the output of the discharge current setting device (13) is transmitted to the power source (2), and as a result, current control is performed. At this time, the first analog switch (14B) is OFF.

Note that P is a positive power supply and R is a resistance.

Here, a control method for controlling the output to a constant value will be referred to as output control, and a control method for controlling the discharge current to a constant value will be referred to as current control.

In other words, in the case of output control, a signal obtained by amplifying the deviation between the desired output setting value and the output feedback value is sent to the power supply (2).
The power supply (2) supplies a discharge current to the discharge (5) using the signal as a target value.

On the other hand, in the case of current control, the desired discharge current setting value, that is, the output signal of the discharge current setting device (13), is given to the power supply, and the power supply (2) uses the signal as a target value to control the discharge current to a constant value. do.

The above operation will be explained in more detail below.

FIG. 8 is a block diagram showing the power supply (2). In Figure 8, (2A) is a converter section that rectifies alternating current from the commercial power supply (25), (2B) is an LC filter section that smoothes the rectified output of the converter section (two people), and (2C) is a converter section that rectifies alternating current from the commercial power supply (25). (2D) is a high-frequency transformer that insulates the inverter (2D) from the load and boosts the voltage. (2E) is the current detection unit. (2F) is the error amplifier. (2G) is the drive. This is the amplifier section.

First, in the case of current control, the setting signal eREF inputted to the power supply (2) by the operation of the setting signal switch (14) becomes the output signal of the discharge current setting device (13).

On the other hand, the current detection section (2E) outputs a signal e proportional to the discharge current i. These ePB' REFs are input to the error B difference amplification section (2F) and calculated, eFB<e
At the time of REF, the drive amplifier section (2G) and the inverter section (2C) operate to increase the discharge current 1p.

When eFB>eREP, it operates to reduce the discharge current ip. In other words, the FB that becomes e ζe
l? Constant current control is performed as in EF.

Next, in the case of output control, the setting signal eREF input to the power supply (2) becomes the output signal of the error amplifier (12) by the operation of the setting signal switch (I4). That is, the laser output feedback signal (lO) and the output setting device (11
) output signal (hereinafter, this output signal will be referred to as the output setting signal (1
The signal obtained by amplifying the difference between
becomes.

REF In other words, when signal (10) < signal (17), eRE
F>0, and when signal (10)>signal (17), e REP<
It becomes 0.

On the other hand, as in the case of current control, the current detection section (2E) outputs a signal eFB proportional to the discharge current i.

These ePB' REFs are input to the error amplification section (2F) and calculated, and when e < e (at this time,
The signal PB REP (signal (10) < signal (17), e > Q) is applied to the drive amplifier section (2G) in order to increase the REF discharge current i.
, the inverter section (2C) operates, and as a result, the laser output increases, the signal (10) increases, and the signal (10) increases.
) Approach the Tokou signal (17).

Also, when ePB>eREP (at this time, signal (10)
> signal (17), e < 0) is sent to the drive amplifier section (2G) in order to reduce the discharge FP current i.

The inverter section (2C) operates, and as a result, the laser output decreases, the signal (lO) decreases, and the signal (10) decreases.
Approach the Toki signal (17).

In this way, constant output control is performed.

[Problems to be Solved by the Invention] The conventional laser output control device is configured as described above, and can select between output control and current control.

However, in the case of output control, while it is possible to control the output to a constant level, there is a problem in that it is slow to follow sudden changes in the output setting, including when the output rises, due to the limited responsiveness of the current output detector. . Further, in the case of current control, although the responsiveness is good, there is a problem that the output cannot be controlled to be constant when the laser oscillation efficiency deteriorates.

This invention was made to solve the above-mentioned problems, and aims to provide a laser output control device that has good transient output response of laser light and excellent static output stability. purpose.

[Means for Solving Problem a] A laser output control device according to the present invention includes a power source that supplies excitation energy to a laser medium filled in a laser oscillator that outputs laser light and performs feedback control of discharge current. A laser output feedback signal from an output detector that detects the laser output and an output from an output setting device that sets the desired laser output. A timing generating means is provided which performs calculations based on the setting signal and outputs a switching timing signal that determines whether output control or current control is to be performed, and inputs the switching timing signal to the setting signal switch, and when the control method selection switch is activated. When output control is selected, the setting signal switcher selects either the deviation signal between the laser output feedback signal and the output setting signal or the output signal of the discharge current setting device according to the switching timing signal output by the timing generating means. It selects and outputs it to the power supply.

[Operation] In the present invention, the timing generating means performs calculation based on a laser output feedback signal from an output detector that detects laser output and an output setting signal from an output setting device that sets a desired laser output, The setting signal switch outputs a switching timing signal that determines whether to perform output control or current control, and when the control method selection switch selects output control, the setting signal switch changes the laser output according to the switching timing signal output from the timing generation means. One of the deviation signal between the feedback signal and the output setting signal and the output signal of the discharge current setting device is selected and output to the power supply, so the output control that controls the laser output to a constant level and the discharge current to a constant level are performed. Current control can be dynamically switched.

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

FIG. 1 is a block diagram showing a laser output control device according to an embodiment of the present invention. In Figure 1, (1) to (
13) and (15) are the same as the conventional example shown in FIG. (1B) is a timing generation means, which inputs an output feedback signal (10) which is an output signal of an output detector (9) and an output setting signal (17) which is an output signal of an output setting device (11). Here, the output signal of the timing generation means (16) is switched to the timing signal (18).
), which is input to the setting signal switch (140).

Next, FIG. 2 will be explained. FIG. 2 is a block diagram illustrating the inside of the timing generation means (16) in more detail. In FIG. 2, (19A) is the first arithmetic unit, (19B) is the second arithmetic unit, (20^) is the first comparator, (20B) is the second comparator, (2
1) is an OR circuit (logical sum circuit). The output feedback signal (
lO) is connected to the first comparator (2OA) and the second comparator (20B) in FIG. Further, the output setting signal (17), which is the output signal of the output setting device (11) in FIG. 1, is connected to the first computing device (19A) and the second computing device (19B) in FIG. There is. Further, the switching timing signal (1B), which is the output signal of the OR circuit (21) in FIG. 2, is connected to the setting signal switch (14) in FIG.

The operation of an embodiment of the present invention will be described below.

In FIG. 2, the first arithmetic unit (19A) outputs 1Xv11 to vol- for the input output setting signal (17).
An operation such as (k, > 1) is performed. Here, ■ is the first
v1□ represents the input signal of the old first calculator (19A), that is, the output setting signal (17). kl is a constant. Further, the second arithmetic unit (19B) receives the input output setting signal (1
7), v −k x v l 2 < k2
<1). Here, vol represents the output signal of the second arithmetic unit (19B), and v1□ represents the input signal, that is, the output setting signal (17). k2 is a constant.

Next, the first comparator (2OA) receives two input signals V. 1 and the output feedback signal (10) (hereinafter referred to as vfB), vol〉■
When vo1≦vfBB, the binary signal “L” is output, and when vo1≦vfBB, “H” is output.

On the other hand, the second comparator (20B) outputs “H” when v02≧vrB for the two input signals V and vfH.
", and outputs "L" when vol<vrB.

Next, the OR circuit (21) connects the second comparator (2O
A) and the output of the second comparator (20B) are logically summed to output a binary signal, which becomes the switching timing signal (18).

In other words, to summarize the above operations, when vfB≦■ or ■o1≦vfB, the switching timing signal (18)
becomes "H", and in the case of vol and vfB and small vol, the switching timing signal (18) becomes "L". (From the above equation, vol is vol.) Next, the operation of the setting signal switch (140) in FIG. 1 will be explained. As in the conventional example, the setting signal switch (140) selects which of the two input signals (the output signal of the error amplifier (12) and the discharge current setting signal which is the output signal of the discharge current setting device (13)). or select one, then turn on the power (2)
).

In FIG. 1, the switching timing signal (18) is “H2
When vfB≦vo2 or vo1≦vf
When B, the setting signal switch (140)
Depending on the signal, one of the two input signals is the discharge current setter (
13) and outputs it to the power supply (2). That is, the device shown in FIG. 1 performs current control at this time. Conversely, when the switching timing signal (18) is "Lo",
That is, when V O2 < V rB < vol, the setting signal switch (140) selects the input signal from the error amplifier (12) from the two input signals by this "L" signal and switches the input signal to the power supply ( 2) Output to. That is, the apparatus shown in FIG. 1 performs output control at this time.

FIG. 3 is a time chart representing the above-mentioned operation. In FIG. 3(a), the solid line indicates the output feedback signal vfB, and the broken line indicates the output setting signal (17). Further, the upper and lower dashed lines of the output setting signal (17) indicate vol and V, respectively. 2 is shown. In FIG. 3, when laser oscillation starts at time 10, time to~1
1, the switching timing signal (18) becomes "H" because vfB≦vo2.

That is, current control is performed during this period. time t1
Since 11vo2<vrB<vol during 't2, the switching timing signal (18) becomes "L". That is,
During this time, output control is performed. Next, when the output setting signal (17) suddenly changes at time t2, the switching timing signal (18
) becomes "H' again, and current control is performed. Then,
After time t, vo2<vrB<vol, the switching timing signal (18) changes to "L", and output control is performed. The above operation is shown in FIGS. 3(b) and 3(c).

As explained above, this timing generation means (1B) includes the output section of the output setting device (11) and the output detector (9).
It is connected to the output section of the output section, and further consists of a circuit that can calculate the set output value and the detected output value. When the output value reached, it is output as a signal to the setting signal switch (140), and the setting signal switch (140)
) receives this signal and switches between two input signals. Therefore, as shown in FIG. 3, a control method can be easily implemented in which current control is temporarily used at the rise of the output or a sudden change in the output set value, and output control is used in a steady state. Therefore, a laser output control device with good transient output response and excellent static output stability can be obtained.

In addition, in FIG. 1, the control method selection switch (15)
As in the conventional example, the control method of the laser oscillator is selected, but the operation of the embodiment of the present invention described above is as follows.
It becomes effective only when the control method selection switch (15) is ON, that is, when the output till am is selected. In other words, the setting signal switch (140) uses the switching timing signal (
18) is provided with a logic circuit (141) that is effective. Conversely, when the control method selection switch (15) is OFF, the switching timing signal (18) becomes invalid and current control is performed as in the conventional example.

To explain this according to FIG. 4, when the switch (15) is ON, the input (2) of the AND circuit (14E) is "
H", and the switching timing signal (18) can pass through the AND circuit (14E) (valid). At this time, the OR circuit (
14F), current control is performed when the switching timing signal (18) is "H", and output control is performed when it is "Lo".

When the switch (I5) is OFF, the AND circuit (14B
) input (2) becomes “L”, and the switching timing signal (
18) cannot pass through the AND circuit (14E) (invalid)
.

At this time, the current is controlled by the operation of the OR circuit (14F).

In the embodiment shown in FIG. 1, the timing generation means (1B) includes the first and second arithmetic units (1
9A), (19B), first and second comparators (
20A), (20B), and an OR circuit (21), as shown in FIG. Second and third A/D converters (22A), (22B) and (
22C), a data bus (23), and a microcomputer (24), and the operation shown in FIG. 2 described above can be realized by replacing the software of the microcomputer, and the same effect can be obtained.

[Effects of the Invention] As explained above, in the present invention, the timing generation means is based on the laser output feedback signal from the output detector that detects the laser output and the output setting signal from the output setting device that sets the desired laser output. It performs calculations and outputs a switching timing signal that determines whether to perform output control or current control, and when the control method selection switch selects output control, the setting signal switcher outputs a switching timing signal that determines whether to perform output control or current control. , the deviation signal between the laser output feedback signal and the output setting signal and the output signal of the discharge current setting device are selected and output to the power supply, so the output control that controls the laser output constant and the discharge current constant. It is possible to dynamically switch between current control and current control. Therefore, it is possible to obtain a laser output control device with good transient output response and excellent static output characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a laser output control device according to an embodiment of the present invention, FIG. 2 is a detailed diagram of the timing generation means portion of FIG. 1, and FIG. 3 is a block diagram of the laser output control device of FIG. 1. FIG. 4 is a time chart diagram showing the control operation; FIG. 4 is a circuit diagram showing an example of the logic circuit of the setting signal switcher shown in FIG. 1;
The figure is a detailed diagram showing another embodiment of the timing generation means in Figure 1, Figure 6 is a block diagram showing a conventional laser output control device, and Figure 7 is a diagram of the logic circuit of the setting signal switcher in Figure 6. A circuit diagram showing an example, FIG. 8 is a block diagram of the power supply portion of FIG. 6. In the figure, (1) is a laser oscillator, (2) is a power supply, (
3A) and (3B) are electrodes, (4) is a laser medium gas, (5) is a discharge, (6) is a total reflection mirror, (7) is a partial transmission mirror, (8) and (8a) are laser beams, (9) is the output detector, <10> is the laser output feedback signal, (1
1) is an output setting device, (12) is an error amplifier, (13) is a discharge current setting device, (14) is a setting signal switcher, (15)
1 is a control method selection switch, (16) is a timing generation means, (17) is an output setting signal, and (18) is a switching timing signal. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Patent Attorney Muneharu Sasaki

Claims (1)

[Claims] A power supply that supplies excitation energy to a laser medium filled in a laser oscillator that outputs laser light and performs feedback control of discharge current, an output detector that detects laser output and outputs it as a laser output feedback signal, and a desired an output setting device that outputs an output setting signal for setting a laser output; a discharge current setting device that outputs a discharge current setting signal for setting a desired discharge current; and the laser output feedback signal and the output setting signal. and a deviation signal from the discharge current setting device and an output signal of the discharge current setting device,
a setting signal switch whose output is connected to the power source; a control method selection switch connected to the setting signal switch and selecting either output control or current control; and timing generation means for outputting a switching timing signal that determines whether output control or current control is to be performed by performing calculations based on the control method selection switch, and the setting signal switching device is configured to generate a switching timing signal when the control method selection switch selects output control. 1. A laser output control device characterized by performing an operation of selecting and outputting one of two input signals according to a switching timing signal outputted by a generating means.