JPH01235391A - Method and device for supplying laser power source - Google Patents

Abstract

PURPOSE:To make it possible to supply a voltage of a desired waveform by separately controlling generation times of a plurality of DC currents whose voltage levels are different stepwise, and by supplying the sum of the controlled DC voltages to a discharge tube for laser light excitation. CONSTITUTION:When trigger pulses PA-PC generated from a trigger circuit 50, switching elements 41-43 are turned on in correspondence with the on-times of these pulses. As a result of this, there are obtained voltages which are chopped by their corresponding modes respectively depending on an area shown as the (a) area via an element 41, an area shown as the (b) area via an element 42, and an area shown as the (c) area via an element 43. Each of these voltages is added via an addition circuit 60, with the result that these chopped voltages are output from an output terminal 70 as a voltage having the waveform corresponding to their envelope. Accordingly, in a discharge tube for exciting laser light which is supplied with such a voltage, pulse waveform of an excited laser light is determined by tracking to the discharge mode of the discharge tube. Laser light having various pulse waveforms appropriate to such a situation can be led out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laser power supply method and apparatus suitable for use in a laser processing apparatus using a solid-state laser such as a YAG laser.

(Prior Art) FIG. 5 shows two sides of a device generally employed in the past as a power supply device for such a solid-state laser.

That is, as shown in FIG. 5, this device includes a transformer 1 that boosts the input alternating current (AC) voltage as required;
A rectifier circuit 2 consists of a bridge circuit of diodes D1 to D4 and performs full-wave rectification of this boosted AC voltage, and a rectifier circuit 2 consists of a series circuit of a coil L and a capacitor C, and a resistor R and a capacitor C2 to convert the rectified voltage into these. a smoothing circuit 3 for smoothing while charging capacitors C and C2;
The smoothed DC voltage (capacitor charging current rf) is transmitted through the output terminal 4 to a tJ! for laser light excitation of a xenon discharge tube or the like. The voltage is applied to an i-tube (not shown).

Incidentally, as shown in FIG. 6, the voltage applied to this discharge tube, that is, the output voltage through the terminal 4 of the power supply device, increases over time while drawing a saturation curve.
After reaching a required voltage value, for example several kilovolts, the discharge tube is discharged all at once by applying a trigger to the discharge tube. f
In the i-detonator, a flash light is emitted in conjunction with such discharge to encourage excitation of laser light from a solid-state laser device (not shown).

[Problem to be solved by the invention]

For example, when a laser processing device is used for welding, the power can be controlled instantaneously during welding so that the weld area is small and appropriate strength is obtained, and the laser beam pulse waveform can also be arbitrarily converted. It is desirable to be able to do so.

In the case of the above-mentioned conventional power supply device, the output voltage waveform is determined exclusively by the time constant of each element constituting the smoothing circuit 3, so if the input voltage is constant, this The output voltage waveform is also uniquely fixed. Of course, in this case, not only the above-mentioned conversion of the laser beam pulse waveform but also arbitrary power control as a power supply device is not possible.

In order to meet the above requirements for a laser power supply, pulse width modulation technology is incorporated into the power supply, and an arbitrary waveform output voltage waveform is obtained by combining this pulse width modulation technology and an LC filter (smoothing circuit). technology (U.S. Patent 4,276.497, name rLAsERFLAS
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However, in order to create a practically effective voltage waveform that can arbitrarily convert the laser beam pulse waveform, it is still necessary to improve its design, ease of creation, and operability. There are difficulties in terms of (ease of use) etc.

This invention has been made in view of these circumstances, and it is possible to arbitrarily convert a laser light pulse waveform to easily and quickly create a power supply voltage waveform that can be supplied to a discharge tube for laser light excitation. An object of the present invention is to provide a laser power supply method and device.

[Means to solve the problem]

In the present invention, the generation times of a plurality of DC voltages having stepwise different voltage level ranges are individually controlled, and the applied voltages of these controlled DC voltages are supplied to the discharge tube for excitation with laser light.

[Effect]

The DC voltage of the above embodiment can be easily obtained through processing such as dividing an AC voltage using a transformer tap, and rectifying and smoothing each of the divided voltages. Therefore, if each of these DC voltages is individually chopped through each different switching element, for example, in this case, by arbitrarily controlling the pulse width of the trigger pulse applied to each of the above-mentioned switching elements, each of the above-mentioned DC voltages can be chopped. R1 time (output time to the subsequent stage of the switching element)
It is also possible to control each separately as desired.

By adding the DC voltages whose R1 times are controlled in this manner as described above, the voltage waveform becomes an arbitrary shaped waveform corresponding to the control time width for each voltage level range.

〔Example〕

FIG. 1 shows an embodiment of a laser power supply device according to the present invention.

As shown in FIG. 1, this embodiment device boosts the input alternating current (AC) Z pressure as required, and in this example, outputs the output taps 11a, 11b, 12.
a and 12b, 13a and 13b, a transformer 10 that divides into voltage groups set in three voltage level ranges, and diodes D to D SD to D, respectively.
, D to D, first to third rectifier circuits 21 to 23 which flow 11 of the divided output transformer outputs, each of which has a coil L1 and a capacitor C.
1. Coil L2 and capacitor C2, coil L3 and capacitor C3 are connected as shown in the figure, and the above ft4
First to third smoothing circuits 31 that smooth the corresponding rectified voltages of the first to third rectifier circuits 21 to 23, that is, sufficiently reduce ripples (pulsating voltage) included in the rectified voltages.
- 33, each consisting of a thyristor, bipolar power transistor, FET, power MO8FET, etc., and chopping the corresponding smoothed output of the first to third smoothing circuits 31 to 33. switching elements 41 to 43 and these switching elements 4
A trigger circuit 50 that applies different trigger pulses P^, P, PC, whose pulse widths and generation timings are individually controlled, to each of the gate terminals A, B, and C of 1 to 43, and these trigger pulses P , P, , and an adding circuit 60 that adds the voltages of each stage chopped through the corresponding switching elements based on the application of Po, using the backflow prevention effect of the diodes D1 to D4. . The voltage increased by this addition circuit 60 is supplied as the output voltage of the device of this embodiment to a laser beam excitation tube (not shown) via an output terminal 70.

FIG. 2 is a timing chart showing an example of the operation of the apparatus of the embodiment shown in FIG. 1. Hereinafter, the operation of the apparatus of the embodiment will be described in detail with reference to FIG.

Trigger pulses P, P emitted from the trigger circuit 50
, Po basically has a large pulse width corresponding to the switching element used for chopping the low voltage, and conversely, the pulse width of Po corresponds to the switching element used for chopping the high voltage. The width is set small.

Therefore, in this embodiment, each pulse width is set with the following relationship: (pulse width of P)>(pulse width of PB)>(pulse width of PC).

As a result, the switching element used for chopping the voltage on the high side knows which on-duty it is.In other words, the switching element with a long on-duty is used for chopping the voltage on the low side, and the switching element The overall pressure load is reduced. In this example device, based on this premise, the duty ratio of the first to third switching elements 41 to 43 is
Control is performed to obtain any desired waveform as the output voltage waveform.

Now, assuming that the trigger pulses P, P, and Po mentioned above are emitted through the trigger circuit 50 in the manner shown in FIGS. 2(a), (b), and (c), respectively, the ON time of these pulses is In response to this, the first to third switching elements 41 to 43 are turned on, respectively.

As a result, through the first switching element 41,
A voltage is obtained which is chopped in a manner corresponding to the region shown as the affi region in FIG. Through the third switching element 43, voltages are obtained that are chopped in a manner corresponding to the region C in FIG. 2(d), and each of these voltages is are added through the addition circuit 60, so that
These chopped voltages are output from the output terminal 70 as a voltage having a waveform corresponding to the contour line in FIG. 2(d).

Therefore, in a discharge tube for laser light excitation (not shown) to which such a voltage is supplied, the apparent
The discharge is executed in the manner shown in ), and the pulse waveform of the laser light excited thereby also follows the discharge manner of the discharge tube.

As described above, according to the apparatus of this embodiment, the pulse waveform of the excited laser light is the same as the trigger pulses PA and PB emitted from the trigger circuit 50.

These trigger pulses PA, PB, and P are determined by each stop timing and each pulse width of the PC, and the conversion of the laser light pulse waveform is also determined by these trigger pulses PA, PB, and P.

This can be realized arbitrarily and easily by changing factors such as the generation timing and pulse width.

For this reason, even during actual laser processing, it is easy to find the ideal processing value (ideal laser beam pulse waveform) according to changes in the workpiece, etc., and for example, by referring to the welding results etc. By sequentially setting the corresponding trigger pulses starting from the lowest divided voltage, it is possible to easily find and form a delicate voltage waveform that corresponds to the optimum machining value.

Note that the trigger circuit 50, which is the source of the trigger pulse,
The system itself is easily configured based on well-known technology, and can be easily realized, for example, by a well-known variable timing generator or software programming through a microcomputer or the like.

Further, in this embodiment, the switching elements 41 to 43
As described above, each voltage resistance load is reduced, and therefore it becomes possible to use inexpensive elements with low voltage resistance.

Moreover, through these switching elements 41 to 43,
Since the voltage chopping itself is performed in multiple stages (three stages in the embodiment) depending on the voltage level, the stress on the discharge tube is also reduced in a gentle manner.

FIG. 3 shows another embodiment of the laser power supply device according to the present invention.

The embodiment shown in FIG. 3 is suitable for use in a relatively low voltage power supply device, and here the AC F & voltage is extracted from a 3-phase AC (for example, 200V) source without a transformer. , m N pressure waveforms are formed.

That is, as shown in FIG. 3, this device includes a rectifier circuit 110 that includes three pairs of diode arrays and one Schottky barrier diode SKD and rectifies the extracted three-phase AC voltage all at once, and A smoothing circuit 12 consists of a coil, a capacitor, and a resistor connected as shown in FIG.
0, a branch circuit 130 that branches this smoothed DC voltage into three branches in parallel, and a thyristor or bipolar power transistor, as in the embodiment shown in FIG.
FET, power MO8FET, etc., and chop the branched DC voltage separately.
As in the previous embodiment, the switching elements 141 to 143 are connected to the gate terminals A, B, and C of these switching elements 141 to 143, respectively, and each trigger pulse whose pulse width and generation timing is individually controlled is provided. P.A.

The trigger circuit 150 applies the trigger pulses PA, P8.C, and each of the trigger circuits 150 includes a diode for preventing backflow, and a coil, a capacitor, and a resistor connected as shown in the figure. The above first to based on the application of PC
Smoothing circuits 161 to 163 that smooth the corresponding chopper outputs of the third switching elements 141 to 143, and an addition circuit 170 that stacks and adds these smoothed chopper outputs using the backflow prevention effect of diodes. , respectively, and the chopper output J subjected to the stacking and caulking is supplied as the output voltage of the embodiment device to a discharge tube for laser excitation (not shown) via an output terminal 180.

In this way, in the case of the embodiment shown in FIG. 3, the DC voltage obtained through the rectifier circuit 110 and the smoothing circuit 120 is branched by the branch circuit 130, and further connected to the first to third switching elements 141 to 143 and the trigger. circuit 150
After chopping these branch voltages at different timings and at different time intervals, the respective smoothed voltages are accumulated and summed to obtain the voltage supplied to the discharge tube for excitation with laser light. Generation time control for the voltage branched through the first to third switching water elements 141 to 143 and the trigger circuit 150 is performed by the first to third switching elements 41 in the embodiment shown in FIG. 43 and the generation time control for the voltage divided into levels in advance through the trigger circuit 50. In the end, the embodiment shown in FIG. 3 also controls the discharge of the discharge tube. The pulse waveform of the laser beam excited by is the trigger pulses P, PB, and P emitted from the trigger circuit 150.

can be arbitrarily determined depending on the timing of each occurrence and each pulse width.

Incidentally, in the embodiments shown in FIGS. 1 and 3, three stages of DC voltage are formed separately and added. However, the number of stages can be set arbitrarily, and the trigger circuit The type of trigger pulse to be generated from 50 or 150 may also be set each time according to the set number of stages.

In addition, since the chopper output generally applies severe on-off stress to the discharge tube, whether it is the embodiment shown in Fig. 1 or the embodiment shown in Fig. 3, the output If, for example, a smoothing circuit 200 as shown in FIG. 4 is provided at the end and the output voltage is supplied to the discharge tube via this smoothing circuit 200, such stress can be satisfactorily alleviated.

Furthermore, the structure of the DC voltage forming and generating means in each of the above-mentioned embodiments may be arbitrary, and it goes without saying that it is limited to the structure shown in FIG. 1 or FIG.

(Effects of the Invention) As explained above, according to the present invention, it is possible to supply a voltage with an arbitrary waveform to the discharge tube for laser light excitation, and to extract laser light having various pulse waveforms that suit the situation. This also significantly improves energy efficiency.Moreover, in the case of the present invention, the circuit configuration is also simplified, and no complicated meter sieve or the like is required to obtain an arbitrary waveform.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the laser power supply according to the present invention, FIG. 2 is a timing chart showing an example of the operation of the embodiment device shown in FIG. 1, and FIG. 3 is a circuit diagram showing an example of the operation of the embodiment device shown in FIG. FIG. 4 is a circuit diagram showing another embodiment of such a laser power supply device, and FIG. 4 shows an example of a smoothing circuit that is suitable for being added to and connected to the output end of the embodiment device shown in FIG. 1 or 3. FIG. 5 is a circuit diagram showing an example of a conventional laser power supply device, and FIG. 6 is a diagram showing output voltage characteristics of the power supply device shown in FIG. 5. 10...Trans, 21.22.23.110...
Rectifier circuit, 31, 32. 33, 120, 161° 162
．． 163.200...Smoothing circuit, 41.42°43.
141, 142.143... switching element, 50
．． 150...Trigger circuit, 60.170...Addition circuit, 70.180...Output terminal.

Claims (6)

[Claims] (1) A laser power supply method that separately controls the generation time of a plurality of DC voltages with stepwise different voltage level ranges, and supplies the summed voltage of these controlled DC voltages to a discharge tube for excitation with laser light. (2) A DC voltage generation circuit that generates multiple DC voltages with stepwise different voltage level ranges, multiple switching elements that individually chop these generated DC voltages, and a pulse width and a trigger circuit that applies different trigger pulses whose generation timings are individually controlled; and an adder circuit that adds the voltages chopped through each of the switching elements based on the application of these trigger pulses; Laser power supply device that supplies voltage to the discharge tube for laser light excitation. (3) The laser according to claim (2), wherein the pulse width of the trigger pulse is controlled to be shorter as the trigger pulse corresponds to a switching element that chops a higher voltage, depending on the voltage level of the generated DC voltage. Power supply device. (4) The laser power supply device further includes a smoothing circuit for smoothing the voltage added by the adding circuit, and supplies the smoothed voltage to the discharge tube for laser beam excitation. Laser power supply device. (5) A branch circuit that branches DC voltage into multiple parallels, multiple switching elements that chop these branched voltages separately, and separate triggers whose pulse widths and generation timings are individually controlled for these switching elements. a trigger circuit that applies pulses, and an adder circuit that accumulates and adds the voltages chopped through the switching elements based on the application of these trigger pulses to a predetermined value, and applies the accumulated and added voltages to a discharge tube for excitation with laser light. Laser power supply device. (6) The laser power supply device further includes a smoothing circuit for smoothing the voltage added by the adding circuit, and supplies the smoothed voltage to the discharge tube for laser light excitation. The laser power supply device described.