JPS6244077A - Power source for repetitive discharge - Google Patents

Abstract

PURPOSE:To shorten the rising time of a discharge current of a discharge tube by connecting a series circuit of a reactor and load switching means through power source switching means with a DC power source, and supplying a pulse current to the tube. CONSTITUTION:Power source switching means 22 conducts or stops an electric energy of a DC power source 21 with a load side under the control of a controller 27. When the switching means 21 is closed under the condition that load switching means 24 is closed, a DC voltage is fed, for example, to a reactor as current converting means 23. Then, the means 24 interrupts when a DC current arrives at the sufficient value to fire a discharge tube 26 to feed the DC current to the tube 25 connected in parallel with the means 24 so that discharge and lighting take place. When this DC current arrives at a certain upper limit value, the means 22 is first interrupted, the means 24 is then conducted to stop feeding a discharge current to the tube 26.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a power supply device that repeatedly supplies a discharge current in a pulsed manner to a discharge tube, and is particularly suitable when the discharge tube is an excitation lamp for oscillating a solid-state laser for machining.

[Prior art and its problems]

Current solid state lasers for processing are mostly limited to those using Nd:YAG as a laser medium because of their good oscillation stability and relatively large output. Laser medium Nd: YAG is an optical crystal called yttrium aluminum garnet (YJIsO+z) containing Nd at a weight ratio of about 1% at, and is formed into a rod shape. Both ends are mirror polished and an anti-reflective coating is applied on top. The side surfaces are made into a frosted glass shape so that the excitation light is easily absorbed by the entire YAG rod. Note that the YAG rod absorbs light of 500 to 800 nm, becomes in a so-called excited state, and oscillates a laser beam of around 1.06μ. The output form is usually a continuously repeated normal pulse. This is laser light that is concentrated in a pulsed manner over a short period of time, and has a high energy density to improve so-called sharpness. This continuously repeated normal pulse is obtained by lighting the excitation lamp in a pulsed manner, that is, as a flash lamp, and controlling the laser output waveform by electrically controlling the lamp lighting time width and lamp current value. There are normal pulses that repeat at low speed and normal pulses that repeat at high speed. Specifically, for low-speed repetition, the pulse width is 0.1
ms to 10 ms, and the pulse repetition frequency is about 50 pulses per second or less. The output level reaches a peak output value of 10 to 20KI4 with an average output value of 400W. For high-speed repetition, the pulse width is 0.1 to 20
m5, the pulse repetition frequency is from 100 to 200 pulses/second (pps) < leprosy. At the output level, the average output value is 400W, and the peak output value is I
Become KW. As flash lamps, straight discharge tubes using xenon (Xe) gas or krypton (Kr) gas are widely used from the viewpoints of long life, reliability, and ease of use. Due to the difference in the emission spectra of the two, differences in laser output efficiency occur depending on the magnitude of the discharge current density of the lamp, the lighting pulse width, etc. For this reason, these are used differently depending on the purpose. For the above-mentioned low-speed repetitive pulses, discharge tubes using xenon (Xe) gas are common, but for high-speed repetitive pulses, discharge tubes using krypton (Kr) gas are more efficient. It seems to be in good condition. Now, in the above-mentioned normal pulse, especially one with so-called high-speed repetition of 100 pps or more,
In order to repeatedly blink a lamp at a high speed, it is necessary to speed up the rise time of the discharge of the lamp and shorten the extinguishing time of the discharge. Traditionally, electrical energy is stored through a resistor in a large capacitor bank, and a trigger voltage is applied via a trigger transformer to a wire wound around the lamp using a switch such as a thyristor, and the induced electromagnetic field is used to The method used was to ionize the gas molecules in the lamp, causing an electrical discharge in the lamp. However, the current waveform obtained by such discharge is an impulse-like waveform with a slow rise, and it is impossible to repeat the fast lamp blinking of 100 pps or more as described above. Therefore, the laser beam oscillated by such optical excitation has a limitation in power density, and has the disadvantage that sharp processing force cannot be obtained.

[Purpose of the invention]

An object of the present invention is to solve the problems of the conventional ones as described above, and to speed up the rise time of the discharge current of an excitation lamp as a discharge tube, and to shorten the extinguishing time of the discharge. It is an object of the present invention to provide a power supply device for repeated discharge which makes the rise and fall steep.

[Key points of the invention]

The main point of the present invention for achieving the above-mentioned object is that it is configured as follows. In the block diagram showing the basic configuration of the present invention shown in FIG. 1, schematically, a power supply device 10 receives power from a DC power supply 21 and supplies a pulsed DC current to a discharge tube 26 intermittently. Causes electrical discharge. For example, in the case of a laser power supply device, the discharge tube is an excitation lamp for solid-state laser oscillation, and a laser medium (not shown) is irradiated with intense flashing light according to the discharge, and a normal pulse is output. Laser light will be oscillated. DC power supply 21 outputs DC voltage. Power opening/closing means 2
Under the control of the control device 27, 2 conducts or blocks the electrical energy of the DC power supply 21 in order to supply it to the load side. First, when the power supply switching means 21 is closed under the condition that the load switching means 24 (to be described later) is closed, the DC voltage is sent to the current converting means 23, such as an steering wheel. Then, the DC voltage is converted by the reactor 23 into a DC current that rapidly increases with a slope determined by its inductance and the DC voltage that is the output of the DC power supply 21. Next, the load switching means 24, which performs conducting and blocking operations in the same manner after the control of the control device 270, performs a blocking operation when the DC current reaches a value sufficient to light up the discharge tube 26. Direct current is transmitted to the load side switching means 24.
The liquid flows into the discharge tube 26 connected in parallel with the discharge tube 26, and the discharge is lit. Then, when this DC current value reaches a certain upper limit,
Based on the command from the control device 27, first the power supply opening/closing means 2
2 enters the blocking state, and then when the discharge time continues for a certain period of time, the load switching means 24 conducts conduction and stops the discharge current from flowing into the discharge tube 26. Further, the rectifying element 25 has a function of circulating the current of the discharge tube 26 to a circuit including the reactor 23 and the load switching means 24 when the power supply switching means 22 is in a blocking state. Further, the rectifying element 29 has a function of preventing the current from the discharge tube 26 from flowing back to the handle 23 . Then, after a certain period, the power supply opening/closing means 22 becomes conductive and returns to the initial state, and the process is repeated in the same manner. The current detector 28 transmits the above-mentioned current detection signal to the control device 27 to determine the timing leg between blocking the load switching means 24 and blocking the power supply switching means 22.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the present invention applied to an excitation lamp for solid-state laser oscillation for processing. This will be explained with reference to FIG. FIG. 2 is a power supply device including an excitation lamp, and FIG. 3 is a time chart and current waveform diagram of the operation of the main elements. In FIG. 2, 20 is an AC power supply, and l is a power supply rectifier circuit, which is composed of a transformer circuit IA, a rectifier circuit IB, and a smoothing circuit IC. 2 is a DC chipper device, which is composed of a thyristor with a forced commutation circuit and a GTO thyristor. 3 is a reactor which has a function of converting DC voltage into DC current. Reference numeral 4 denotes the above-mentioned switchgear for supplying current to the accelerator 3, which, like the DC chopper device 2, is composed of a forced commutation circuit-equipped cyrisk or a GTO cyrisk. In addition, when a thyristor is used to open and close a DC power supply with a forced commutation circuit, once current flows through the anode and cathode, the gate of the thyrisk loses its control function, so there is a method to stop the current externally. It has the function of performing commutation by taking the following steps. In other words, forced commutation is performed by flowing a current larger than the forward current in the reverse direction from an external energy source. In addition, GTO Thyrisk has basically the same structure as a normal thyristor, but unlike Thyrisk, the anode current must be transferred to another part by an auxiliary commutation device or circuit in order to turn off. It can be turned off by flowing current, has fast opening and closing operations, and is mainly used for direct current switching. 5.6 is a diode, and in terms of function, the former is called a freewheel diode, and the latter is called a block diode. 7 is a control device, which includes a DC chopper device 2. It controls the conduction period and blocking period of the switching device 4, and has the function of generating a current waveform required by the excitation lamp 8, which will be described later. for that,
The control device 7 detects the current flowing through the switchgear 4 and controls the DC chopper device 2 . In addition to operating the opening/closing device 4, the controller also performs an operation to start the trigger circuit 12, which will be described later. Note that the control device 7 is equipped with setting elements related to the generated current pulse, such as current, pulse width, and frequency. 11 is a simmer circuit, which has the following functions. In other words, as mentioned above, it is necessary to speed up the rise time of the discharge of the excitation lamp and shorten the extinguishing time of the discharge. Normally, it operates in a so-called simmer mode in which the battery is discharged with a current of about 100 mA. Using an excitation lamp in this simmer mode not only shortens the discharge rise time, but also reduces this start-up shock and extends the life of the excitation lamp, especially when the repetition rate is very fast. It is effective for In conclusion, 8 is an excitation lamp and 9 is a resistor. In addition, 12 is a trigger circuit, 13 is a trigger transformer, and 20K is used as a trigger for discharge by the current generated in the previous stage.
A high voltage pulse of approximately V is generated based on a command from the control device 7 described above. Next, the operation of the circuit described above will be described based on FIGS. 2 and 3. As mentioned above, the excitation lamp 8 has
Shimmer circuit 11. A simmer current is flowing through the resistor 9. On the other hand, the DC chopper device 2. When the opening/closing device 4 is closed, the DC chopper 2° reactor 3. A direct current flows through the switchgear 4. This will be explained with reference to FIG. Figure 3 (a
) is the DC chopper device 2, and FIG. 3(b) is the switchgear 4.
2 is a flowchart showing conduction (ON) and blocking (OFF) states, respectively. In addition, FIG. 3 (C1 is the current flowing through the switchgear 4, FIG. 3(d) is the current flowing through the beam handle 3, and FIG. 3 (EL is the current flowing through the excitation lamp 8) is a current waveform diagram showing the current flowing through the excitation lamp 8 with respect to time. During the time T, ~↑1 in Figure 3+a) and (b), both the DC chopper device 2 and the switching device 4 are in a conductive state, so the DC chopper device 2.Reactor 3.Switching device 4
As shown in FIG. 2C, a current is generated in the circuit including the current that linearly increases over time with a slope approximately determined by the output voltage of the power supply rectifier circuit 1 and the inductance of the axle 3. When this current reaches a predetermined current value 1a sufficient to light up the excitation lamp 8, the switching device 4 is blocked based on the operation command of the control device 7 which detects the movement of this current. . At the same time, that is, at time T, the current flowing through the switchgear 4 becomes zero, and the current that has been flowing until now is transferred to the excitation lamp 8 and increases with a steep rise. At this point, the excitation lamp 8 is turned on. The rise time of this current is determined by the current blocking time of the switching device 4, and is extremely short, ranging from several μs to several tens of μs. Further, the trigger circuit 12 is activated by the control device 7 in synchronization with time T1, and a high voltage pulse is generated via the trigger transformer 13 to trigger the discharge. Next, the DC chopper device 2. The circuit including the reactor 3° diode 6 and the excitation lamp 8 has a voltage that is approximately determined by the difference between the output voltage of the power rectifier circuit 1 and the discharge voltage of the excitation lamp 8 (the former is larger) and the inductance of the reactor 3. With a gentler slope, the current increases more linearly. When this current reaches a predetermined value Ib at time T2, the DC chopper device 2 is blocked based on an operation command from the control device 7 that has detected this at time T1.
The current flowing through the excitation lamp 8 during ~T2 is as shown in Figure 3 (e
It becomes like l. Next, after time T, reactor 3. diode 6
, excitation lamp8. The current flowing through the circuit including the diode 5 decreases with a slope approximately determined by the discharge voltage of the excitation lamp 8 and the inductance of the axle 3, starting at time TI with a pulse width T. At time T, after a time corresponding to , the switching device 4 becomes conductive based on an operation command from the control device 7. At that moment, the discharge voltage of the excitation lamp 8 is 200
Since the current is as high as ˜500 V, the current that has been flowing through the excitation lamp 8 will automatically be transferred to the circuit including the switchgear 4, exhibiting a steep drop, and the excitation lamp 8 will turn off. The current waveform of the excitation lamp 8 at times T and -T3 is shown in FIG.
As shown in e), the rise and fall are extremely steep, which meets the purpose. From time T, the reactor 3. The current in the circuit including switchgear 4 and diode 5 decreases as shown in the section of time T, ~T, in Figure 3 (C1, (dl). Note that time a is the extra time required for the first rise. Then, at time T, when the DC chopper device 2 becomes conductive based on the operation command of the control device 7, the reactor 3
．． The current flowing through the switchgear 4 increases with the same slope as at time T3-T. And said! When the point a is reached, the opening/closing device 4 is blocked by an operation command from the control device 7. At this moment, at time T4, the current Ia flows into the excitation lamp 8 with a steep rise, and the next lighting is performed. Regarding the current of the excitation lamp 8, this time T4 is equal to the time T4.
This corresponds to I, and is repeated in the same manner at the period Tp thereafter. However, time T. ~T4 is the first rising time T0~T
, shorter (the same applies hereinafter). Note that the trigger pulse is generated by the trigger circuit 12 only at the beginning, and each subsequent discharge is performed by the discharge path formed by the above-mentioned simmer current. In addition, during the interval between time T and T, a current shown in FIG. It can be seen that some loss occurs as the output energy from 1 circulates through this circuit, and in this sense, diode 5 is called a freewheeling diode. Control device 7
It is assumed that the timing at which conduction occurs due to the command is determined by the period T. However, this conduction timing may also be determined by the current value flowing through the switchgear 4 reaching Ic of C1, fdl in FIG. It has the function of blocking current, and in that sense is called a block diode.In addition, a thyristor is provided in place of the power rectifier circuit 1 and DC chopper device 2 in Fig. 2, and the phase of the AC voltage applied to the load is changed by this thyristor. The same characteristics can be obtained even if the current is controlled by so-called phase control, which continuously controls the power supplied to the load by changing the angle. [Effects of the Invention] With the above configuration and operation, the When applied to the excitation lamp of solid-state laser oscillation for processing,
This invention has the following superior effects compared to conventional ones. That is, first, current flows into the reactor in a short-circuited state, and then current is supplied to the excitation lamp, so that a sufficient discharge current can flow with a smaller power supply than in the conventional CL discharge circuit. Further, in order to speed up the rise time of the discharge current of the excitation lamp and shorten the extinguishing time of the discharge, the current waveform can be made to have an extremely steep rise and fall. Therefore, it is possible to repeat fast lamp blinking of 100 pp/s or more, and the continuous pulse-like strong light energy generated by this excites the atoms in the laser medium, causing population inversion, and the laser amplification effect. Emits light rays. The laser beam oscillated in this way has a very high power density, and a sharp machining force can be obtained.

[Brief Description of the Drawings] Fig. 1 is a block circuit diagram showing the basic configuration of the present invention, Fig. 2 is a block circuit diagram of an embodiment according to the present invention, and Fig. 3 is a block circuit diagram showing the basic configuration of the present invention.
The figures are a time chart and a current waveform diagram showing the operation of an embodiment according to the present invention. Symbol explanation 1: [source rectifier circuit, 2: DC chopper device, 3: reactor, 4: switchgear, 5.6: diode, 7.277 control device, 8: excitation lamp, 10. IOA: Power supply, 11 circuits, 1
2: Trigger circuit, 20: AC power supply, 21: DC power supply, 2
2: Power switching means, 23: Current converting means, 24: Load switching means, 25: Rectifying element, 26: Discharge tube, 28: Current detector. +OA is released by 11! I

Claims (1)

[Claims] 1) A series circuit of a reactor and a load switching means is connected to a DC power source via a power switching means, and a freewheel diode is provided to form a return path for the current of the reactor when the power switching means is turned on. It is connected in parallel to the series circuit, and a backflow prevention block/block is connected to the load switching means.
Discharge tubes are connected in parallel through diodes, and the power switching means is controlled on/off to adjust the current of the reactor, and the load switching means is controlled to guide the current of the reactor to the discharge tube in a pulsed manner. A power supply device for repeated discharge characterized by being provided with a control device for on/off control.