JP2009123833A - Laser diode power supply device for laser beam machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reasonably rapidly set up an LD drive current to a set current value, in a laser diode power supply device for a laser beam machine. <P>SOLUTION: This laser diode power supply device 12 includes, as main components: a constant current source circuit 70 for supplying a desired constant current to a load circuit; an inductance coil 72 connected between the constant current source circuit 70 and an LD array 30; a switching element 74 connected to the constant current source circuit 70 in series to the inductance coil 72, and connected in parallel to the LD array 30; a switching element 76 connected in parallel to the switching element 74 and in series to the LD array 30; and an LD drive control part 78 controlling the switching elements 74 and 76. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser diode power supply device for driving a laser diode (LD) used in a laser processing machine.

  Conventionally, a laser diode (LD) is often used as an excitation light source for optically exciting an active medium such as a YAG laser or a fiber laser. Recently, an LD is also used as a laser oscillation source for generating laser light for processing.

  Usually, in order to obtain high output, an LD-type excitation light source or laser oscillation source used in a laser processing machine arranges a large number of LDs in a one-dimensional direction or a two-dimensional direction and emits all of them simultaneously. Such an LD array is electrically connected, for example, in the vertical direction with LDs in each column in series, and in the horizontal direction, LD series circuits in all columns are connected in parallel. Need.

  Conventional laser diode power supply devices in the field of laser processing are configured as a constant current source circuit that can supply an LD drive current necessary for laser oscillation of a load LD with a required output at a constant current. And a capacitor for accumulating electric power, a charging circuit for charging the capacitor to a set voltage, and an output switching element connected between the capacitor and a load (LD). When generating a normal or long-pulse processing laser beam, the switching element is turned on or switched only during a pulse output time, and is maintained in an off state while no pulse is output.

  As described above, the conventional laser diode power supply device discharges the capacitor by turning on or switching the output switching element, and uses the discharge current as the LD drive current. However, the LD has wiring inductance and inter-terminal capacitance, and the capacitor discharge current (LD drive current) is reduced under the condition that many LDs (LD array) connected in series and parallel must all emit light simultaneously. The rise is slow, so the rise of the laser output is also slow. Therefore, in laser processing (for example, laser welding) that requires a fast rise of the pulse laser, the rise of the LD drive current is accelerated by setting the charging voltage of the capacitor to a sufficiently high value. However, such a technique for forcibly raising the LD drive current with high voltage power has a problem that it becomes difficult to control the constant current, so that a high-speed and stable rise characteristic cannot be obtained.

  The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a laser diode power supply device for a laser beam machine capable of raising the LD drive current to a set current value without difficulty at high speed. And

  In order to achieve the above object, a laser diode power supply apparatus according to a first aspect of the present invention is a laser diode (LD) of an excitation light source for optically exciting an active medium in a laser oscillator in a laser processing machine. A constant current source circuit for supplying a desired constant current to a load circuit, an inductance coil connected between the constant current source circuit and the laser diode, and A first switching element connected in series with the inductance coil with respect to the constant current source circuit and connected in parallel with the laser diode, and the first switching element is turned on while the laser diode is not emitting light When the laser diode is caused to emit light, the first switching element is held off. And a drive control unit.

  In the above apparatus configuration, while the laser diode does not emit light, the current output from the constant current source circuit flows through the inductance coil and the first switching element in the ON state, and the inductance coil is supplied with power in the form of electromagnetic energy. Is stored. When the LD drive control unit switches the first switching element from the on state to the off state in order to cause the laser diode to emit light, the current from the inductance coil passes through the laser diode side in parallel with the first switching element in the load circuit. As the LD drive current flows, the laser diode oscillates (emits light). Since the current flowing in the inductance coil is supplied and the laser diode is energized, the LD drive current can be raised quickly without difficulty.

  A laser diode power supply apparatus according to a second aspect of the present invention is a laser diode power supply apparatus that drives a laser diode (LD) of an excitation light source in order to optically excite an active medium in a laser oscillator in a laser processing machine. A constant current source circuit for supplying a desired constant current to the load circuit, an inductance coil connected between the constant current source circuit and the laser diode, and the inductance for the constant current source circuit A first switching element connected in series with the coil and connected in parallel with the laser diode; an LD drive current measuring unit for measuring a current value of an LD drive current flowing through the laser diode; and the laser diode While not emitting light, the first switching element is kept in an on state, and the laser diode emits light. Has said LD driving current current measurement values obtained from the unit measurement preset reference value or LD drive control unit for the first switching element is a switching operation so as to follow the reference waveform when to.

  In the above apparatus configuration, while the laser diode does not emit light, the current output from the constant current source circuit flows through the inductance coil and the first switching element in the ON state, and the inductance coil is supplied with power in the form of electromagnetic energy. Is stored. In order to cause the laser diode to emit light, the LD drive control unit switches the first switching element from the ON state to the switching operation, so that the current from the inductance coil is changed between the branch of the first switching element and the laser diode in the load circuit. The laser diode oscillates (emits light) as it branches off from the branch. Since the current flowing in the inductance coil is supplied and the laser diode is energized, the LD drive current can be raised at high speed in accordance with the reference value or reference waveform without difficulty in the current feedback control.

  A laser diode power supply apparatus according to a third aspect of the present invention is a laser diode power supply apparatus that drives a laser diode (LD) of an excitation light source to optically excite an active medium in a laser oscillator in a laser processing machine. A constant current source circuit for supplying a desired constant current to the load circuit, an inductance coil connected between the constant current source circuit and the laser diode, and the inductance for the constant current source circuit A first switching element connected in series with a coil and connected in parallel with the laser diode; a laser output measuring unit for measuring a laser output of a laser beam oscillated and output from the laser oscillator; and the laser While the diode does not emit light, the first switching element is held in an on state, and the laser diode is turned on. Has a LD drive control unit for the first switching element is a switching operation so as to follow the laser output measured value preset reference value or the reference waveform obtained from the laser output measuring unit when to light.

  In the above apparatus configuration, while the laser diode does not emit light, the current output from the constant current source circuit flows through the inductance coil and the first switching element in the ON state, and the inductance coil is supplied with power in the form of electromagnetic energy. Is stored. In order to cause the laser diode to emit light, the LD drive control unit switches the first switching element from the ON state to the switching operation, so that the current from the inductance coil is changed between the branch of the first switching element and the laser diode in the load circuit. The laser diode oscillates (emits light) as it branches off from the branch. Since the current flowing in the inductance coil is supplied and the laser diode is energized, the LD drive current can be raised at high speed according to the reference value or reference waveform without difficulty in the laser output feedback control.

  In a preferred embodiment of the present invention, the LD drive control unit controls the switching of the first switching element by a pulse width modulation method.

  In another preferred embodiment, a second switching element is connected in parallel with the first switching element and in series with the laser diode, and while the LD drive control unit does not cause the laser diode to emit light, the second switching element is connected. When the switching element is held in the off state and the laser diode is caused to emit light, the second switching element is held in the on state. With this configuration, since the second switching element in the off state cuts off the current while the laser diode is not emitting light, it is possible to reliably prevent undesired current injection into the laser diode.

  In another preferred embodiment, one or more diodes are connected in a forward direction with respect to the current flowing through the first switching element in parallel with the laser diode and in series with the first switching element. In this configuration, fluctuations in the load voltage before and after the light emission of the laser diode can be reduced, and the rise of the LD drive current can be more stably speeded up.

  In the laser diode power supply device of the present invention, preferably, the constant current source circuit is connected between a capacitor for storing power, a charging circuit for charging the capacitor to a preset reference voltage, and the capacitor and the inductance coil. The third switching element, a main current measurement unit for measuring the current value of the main current flowing through the inductance coil, and the current measurement value obtained from the main current measurement unit coincides with a preset reference value And a main current controller for switching the third switching element.

  In the laser diode power supply device of the present invention, a large number of laser diodes are spatially arranged in a one-dimensional direction or a two-dimensional direction, and the plurality of laser diodes are electrically connected in series and / or in parallel according to the arrangement pattern. This is particularly advantageous when driving an LD array connected to, and when generating laser light having a pulse waveform.

  Furthermore, the present invention can also be suitably applied to a laser diode power supply device that drives a laser diode (LD) for oscillating and outputting laser light for laser processing.

  According to the laser diode power supply device of the present invention, the LD driving current can be started up to the set current value without difficulty by the above-described configuration and operation, and the processing capability and processing quality in the laser processing machine can be increased. Can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a configuration of a fiber laser processing machine as an example to which the laser diode power supply device of the present invention can be suitably applied. The fiber laser processing machine includes a fiber laser oscillator 10, a laser diode power supply device 12, a laser incident unit 14, a fiber transmission system 16, a laser emitting unit 18, a processing table 20, and a main control unit 25.

  The fiber laser oscillator 10 includes an oscillation optical fiber (hereinafter referred to as “oscillation fiber”) 22, an electro-optical excitation unit 24 that irradiates one end surface of the oscillation fiber 22 with pumping excitation light MB, and an oscillation fiber. 22 and a pair of optical resonator mirrors 26 and 28 that are optically opposed to each other via 22.

The electro-optic excitation unit 24 includes an LD array 30 serving as an excitation light source and a condensing optical lens 32. The LD array 30 is formed by arranging a large number of current injection type LDs spatially in a one-dimensional direction or a two-dimensional direction, and electrically connecting the many laser diodes in series and / or in parallel according to the arrangement pattern. (FIG. 2), light is emitted by the LD drive current I _LD from the laser diode power supply device 12, and the laser beam MB for excitation is oscillated and output. The optical lens 32 condenses and enters the excitation laser beam MB from the LD array 30 onto one end surface of the oscillation fiber 22. The optical resonator mirror 26 disposed between the LD array 30 and the optical lens 32 transmits the excitation laser beam MB incident from the LD array 30 side and transmits the oscillation light beam incident from the oscillation fiber 22 side of the resonator. It is configured to totally reflect on the optical axis.

  Although not shown, the oscillation fiber 22 has a core doped with, for example, rare earth element ions as a light emitting element, and a clad surrounding the core coaxially. The core is used as an active medium, and the clad is used as the propagation of excitation light. The light path. The excitation laser beam MB that has entered the oscillation fiber 22 from one end face of the oscillation fiber 22 as described above propagates in the oscillation fiber 22 in the axial direction while being confined by total reflection at the cladding outer peripheral interface. By crossing the core many times inside, the rare earth element ions in the core are photoexcited. In this way, an oscillating light beam having a predetermined wavelength is emitted in the axial direction from both end faces of the core, and this oscillating light beam travels back and forth between the optical resonator mirrors 26 and 28 and is resonantly amplified. A fiber laser beam FB having the predetermined wavelength is extracted from the optical resonator mirror 28.

  In the optical resonator, the optical lenses 32 and 34 collimate the oscillating light beam emitted from the end face of the oscillation fiber 22 into parallel light and pass the collimated light to the optical resonator mirrors 26 and 28. The oscillating light beam reflected and returned by is condensed on the end face of the oscillating fiber 22. The excitation laser beam MB that has passed through the oscillation fiber 22 passes through the optical lens 34 and the optical resonator mirror 28 and is then folded back toward the side laser absorber 38 by the folding mirror 36. The fiber laser light FB output from the optical resonator mirror 28 passes straight through the folding mirror 36 and then passes through the beam splitter 40 before entering the laser incident portion 14.

The beam splitter 40 reflects a part (for example, 1%) of the incident fiber laser beam FB to a predetermined direction, that is, a light receiving element for power monitoring, for example, a photodiode (PD) 42 side. A condenser lens 44 that condenses the reflected light from the beam splitter 40 or the monitor light R _FB may be disposed in front of the photodiode (PD) 42.

The photodiode (PD) 42 photoelectrically converts the monitor light R _FB from the beam splitter 40 and outputs an electric signal (laser output measurement signal) S _FB representing the laser output (peak power) of the fiber laser light FB. This signal S _FB is sent to the laser diode power supply device 12. The laser diode power supply device 12 uses the laser output measurement signal S _FB from the photodiode (PD) 42 as a feedback signal when performing real-time power feedback control.

  The fiber laser beam FB that has entered the laser incident portion 14 is first folded in a predetermined direction by the vent mirror 46, and then condensed by the condenser lens 50 in the incident unit 48 to be transmitted by an optical fiber for transmission in the fiber transmission system 16 ( (Hereinafter referred to as “transmission fiber”). The transmission optical fiber 52 is made of, for example, an SI (step index) fiber, and transmits the fiber laser light FB incident in the incident unit 48 to the emission unit 54 of the laser emission unit 18.

  The emission unit 54 includes a collimator lens 56 that collimates the fiber laser light FB emitted from the end surface of the transmission fiber 52 into parallel light, and a condensing lens 58 that condenses the parallel fiber laser light FB at a predetermined focal position. And the fiber laser beam FB is condensed and applied to the processing point W of the workpiece 60 placed on the processing table 20.

  The main control unit 25 is composed of, for example, a microcomputer, and controls and controls each part in the fiber laser processing machine. In particular, the main control unit 25 supplies set values to the laser diode power supply device 12 and performs timing control as described later. .

In this fiber laser processing machine, when, for example, laser welding is performed on the workpiece 60 on the table 20, an LD drive current I _LD having a pulse waveform is supplied from the laser diode power supply device 12 to the LD array 30. In the laser oscillator 10, the excitation laser beam MB having a pulse waveform is supplied from the LD array 30 to the oscillation fiber 22, and the fiber laser beam FB having a pulse waveform is oscillated and output from the fiber laser oscillator 10. The fiber laser beam FB having the pulse waveform is condensed and irradiated onto the processing point W of the workpiece 60 through the laser incident part 14, the fiber transmission system 16 and the laser emitting part 18. At the processing point W, the material to be processed is melted by the energy of the fiber laser beam FB having a pulse waveform, and solidifies after the pulse irradiation to form a nugget.

In this fiber laser processing machine, the LD drive current I _LD supplied from the laser diode power supply device 12 to the LD array 30 can be raised at a high speed as will be described later, so that the rising speed of the excitation laser beam MB and thus the fiber laser beam FB The rising speed is high, which can improve the penetration characteristics in laser welding.

  FIG. 2 shows the configuration of the laser diode power supply device 12 in this embodiment. The laser diode power supply device 12 includes, as main components, a constant current source circuit 70 for supplying a desired constant current to the load circuit, and an inductance connected between the constant current source circuit 70 and the LD array 30. A coil 72, a switching element 74, which is a first switching element connected in series with the inductance coil 72 to the constant current source circuit 70 and in parallel with the LD array 30, and in parallel with the switching element 74 And a switching element 76 as a second switching element connected in series with the LD array 30, and an LD drive control unit 78 for controlling the switching elements 74 and 76.

  The constant current source circuit 70 includes a commercial AC power supply 80, a charging circuit 82, a capacitor 84, a switching element 86, a flywheel diode 88, a current sensor 90, a current measurement circuit 92, and a main current control unit 94.

Here, the charging circuit 82 converts commercial alternating current from the commercial alternating current power supply 80 into direct current and charges the capacitor 84 to a set voltage. The capacitor 84 stores the power for driving the LD as a charge charge (electrostatic energy). The switching element 86 as the third switching element performs a switching operation so as to discharge the capacitor 80 and to flow a desired discharge current or main current I _C to the load circuit side under the control of the main current control unit 94. The flywheel diode 88 is for continuing to flow the main current I _C through the load circuit while the switching element 86 is temporarily turned off. The current sensor 90 is composed of, for example, a Hall element and detects the main current I _C in a non-contact manner. Current measuring circuit 92 receives the output signal of the current sensor 90 a current measurement of the primary current I _C (e.g. current effective value) is calculated, and the main current control unit 94 of the main current measured value SI _C as a feedback signal give. The main current control unit 94, as taken from the main current control unit 94 the main current measured value SI _C matches the predetermined reference value, the switching control of the switching element 86, for example, pulse width modulation (PWM) .

  A current reference value used for feedback control of the main current control unit 94 is given from the main control unit 25. The main control unit 25 also provides a voltage setting value for charging the capacitor 80 by feedback control in the charging circuit 82.

In this laser diode power supply device 12, one or a plurality of voltage drop diodes 96 are connected between the nodes N _a and N _{b of} the load circuit in parallel with the LD array 30 and in series with the switching element 74. It is connected in the forward direction with respect to the flowing current. The number of diodes 96 connected in series is preferably the same as or close to the number of LDs connected in series in each column of the LD array 30. The main current I _S output from the constant current source circuit 70 always flows through the inductance coil 72. In the subsequent load circuit, the first branch J ₁ including the diode array 96 and the first switching element 74 and / or Alternatively, the second branch J ₂ including the switching element 76 and the LD array 30 is diverted or selectively flowed.

More specifically, while the LD array 30 is not emitting light, the switching element 74 of the first branch J ₁ is held in the ON state under the control of the LD drive control unit 78, and the second branch J ₂ The switching element 76 is kept off. In this case, the LD drive current I _LD is not supplied to the second branch J ₂ , and the main current I _S from the inductance coil 72 flows through the first branch J ₁ as it is as the bypass current I _B.

When the LD array 30 is caused to emit light, the switching element 76 of the second branch J ₂ is kept in the ON state and the switching element 74 of the first branch J ₁ under the control of the LD drive control unit 78. The switching operation is performed. In this case, a part of the main current I _S from the inductance coil 72 flows through the second branch J ₂ as the LD drive current I _LD and the rest flows through the first branch J ₁ as the bypass current I _B. The current sensor 98 provided in the second branch J ₂ is formed of, for example, a current transformer, and detects the LD drive current I _LD by a non-contact method. The current measurement circuit 100 calculates the measured value (for example, current effective value) of the LD drive current I _LD based on the output signal of the current sensor 98, and gives the measured current value SI _LD to the LD drive control unit 78 as a feedback signal. .

The LD drive control unit 78 performs switching control of the switching element 74 of the first branch J ₁ so that the LD drive current I _LD flowing through the second branch J ₂ follows a preset reference value or reference waveform. Alternatively, the laser output measurement signal S _FB from the power monitor unit [44, 42] (FIG. 1) is used as a feedback signal so that the laser output measurement signal S _FB follows a preset reference value or reference waveform. It is also possible to perform switching control of the switching element 74. A current reference value or a reference waveform used for such current feedback control or power feedback control is supplied from the main control unit 25. The timing for switching the states of the switching elements 74 and 76 is also instructed from the main control unit 25 to the LD drive control unit 78.

  A power transistor such as an FET or an IGBT may be used for each switching element 74, 76, 84 in the laser diode power supply device 12.

  FIG. 3 shows the state or waveform of each part in the laser diode power supply device 12 (FIG. 2) when the laser beam MB for excitation having a pulse waveform is oscillated and output from the LD array 30.

In this case, before the start of the pulse (time point ts), the switching element 86 of the constant current source circuit 70 shown in FIG. 2 continues to perform the switching operation constantly under constant current control, and the switching element of the first branch J _{1 in} the load circuit. 74 is held in the on state, and the switching element 76 of the second branch J ₂ is held in the off state. As a result, all the main current I _C flowing through the inductance coil 72 flows as it is as the bypass current I _B through the first branch J _1, and the power corresponding to the current value of the main current I _C is in the inductance coil 72 in the form of electromagnetic energy. Can be stored.

3, the switching element 76 of the second branch J ₂ shown in FIG. 2 is switched from the off state so far to the on state, and the switching element 74 of the first branch J ₁ is on so far. Switch from state to switching operation. As a result, the main current I _C flowing through the inductance coil 72 is shunted into the first branch J ₁ and the second branch J ₂ in the load circuit, and the current flowing through the second branch J ₂ , that is, LD driving. The current value or current waveform of the current I _LD is defined by the switching control of the LD drive control unit 78 for the switching element 74.

For example, when the current feedback control loop is activated, the switching element 74 performs a switching operation in a PWM manner so that the current waveform of the LD drive current I _LD follows the reference waveform. In this case, a part of the main current I _C that has been flowing through the inductance coil 72 before the rise of the LD drive current I _LD moves from the first branch J ₁ to the second branch J ₂ as the LD drive current I _LD. The load voltage between the nodes N _a and N _b is not much different before and after the start of the pulse. For this reason, the LD drive current I _LD can be raised at a high speed at a set speed without difficulty. Although not shown, the LD array 30 may be provided with a bias current supply circuit that supplies a bias current in the vicinity of the threshold current value of the LD drive current I _LD .

As an example, in the conventional laser diode power supply device, the rise time of the LD drive current is about 100 μsec, whereas in the laser diode power supply device 12 of this embodiment, the rise time of the LD drive current I _LD is increased to about 2 μsec. can do.

As described above, when the LD driving current I _LD having a pulse waveform flows through the second branch J ₂ , all the LDs constituting the LD array 30 are energized all at once, and the excitation laser beam MB having the pulse waveform oscillates. Is output.

Then, at the pulse end point t ₂ in FIG. 3, the switching element 76 in the second branch J ₂ shown in FIG. 2 is switched from the previous on state to the off state, and at the same time, the switching element 74 in the first branch J _1. Switches from the previous switching operation to the ON state. In this way, each part returns to the same state as before the start of the pulse.

As described above, the control of the main current I _C in the constant current source circuit 70 of FIG. 2 and the control of the LD drive current I _LD in the load circuit are performed independently during the pulse period (ta to tb) of FIG. Thus, the pulse waveform control can be performed freely and finely.

As a modification, as shown in FIG. 4, during the pulse period (ta to tb), the load circuit holds the switching element 76 of the second branch J _{2 in} the ON state and switches the first branch J ₁ . It is also possible to hold the element 74 in the OFF state and perform a switching operation for controlling the LD drive current I _LD of the switching element 86 in the constant current source circuit 70. In this case, the main current control unit 94 switches the switching element 86 by, for example, the PWM method so that the current measurement value SI _C (SI _LC ) obtained by the current measurement circuit 92 follows the reference waveform supplied from the main control unit 25. You may control.

In the example of FIG. 4, in order to increase the degree of freedom in the waveform control for the LD drive current I _LD, the peak value of the LD drive current I _LD is set to be smaller than the steady-state value of the primary current I _C. As another modification, the degree of freedom of waveform control is reduced, but the peak value of the LD drive current I _LD can be matched to the steady value of the main current I _C. Furthermore, as another modification, the main current control unit 94 uses the laser output measurement signal S _FB from the power monitor unit [44, 42] (FIG. 1) as a feedback signal, so that a constant current of the LD drive current I _LD is obtained. It is also possible to perform control or waveform control.

As another modification, in order to simplify the apparatus configuration, the switching element 76 of the second branch J ₂ , the current sensor 98 for current monitoring, and the current measuring circuit 100 are omitted from the load circuit, and FIG. It is also possible to adopt an apparatus configuration as shown. In this case, the LD drive control unit 78 holds the switching element 74 of the first branch J _{1 in} the on state while the LD array 30 is not emitting light, and sets the switching element 74 to the off state when causing the LD array 30 to emit light. Hold. Then, towards the constant current source circuit 70, while not fire the LD array 30 controls the main current I _C, it may control the LD driving current I _LD when emit LD array 30. It is preferable to reduce the voltage drop of the diode 96 provided in the first branch J ₁ as much as possible so that the main current I _C is not shunted to the second branch J ₂ while the switching element 74 is in the ON state. .

  Although the above-described embodiment relates to a fiber laser processing machine, the present invention can also be applied to a laser diode power supply device used in another laser processing machine.

  For example, as shown in FIG. 6, the laser diode power supply device 12 of the above embodiment can be applied to a YAG laser processing machine as it is. In this YAG laser processing apparatus, a YAG rod 104 is arranged between optical resonator mirrors 26 and 28 in a YAG laser oscillator 102, and an LD array 30 is used as an excitation light source for optically pumping the YAG rod 104. In use, the LD array 30 is driven by the laser diode power supply 12. The excitation laser beam MB generated by the excitation LD array 30 is condensed and incident on one end face of the transmission optical fiber 108 by the condenser lens 106, propagates through the optical fiber 108, and is emitted from the other end face. The YAG rod 104 is incident on one end surface through the collimator lens 110, the condensing lens 112, and the optical resonator mirror 26. The YAG laser beam YB oscillated and output from the YAG laser oscillator 102 is irradiated to the processing point W of the workpiece 60 through the vent mirror 114 and the laser emitting unit 18 as a processing laser beam.

  As another example, as shown in FIG. 7, a laser beam LB for processing is directly generated by an LD array 30, and the laser beam LB for processing is passed through an optical fiber 116 for transmission at a desired processing location. The laser diode power supply device 12 of the present invention can also be applied to an LD laser processing machine that performs processing. In FIG. 7, the condensing lens 118 condenses and enters the laser beam LB oscillated and output from the LD array 30 onto one end surface of the optical fiber 116. The commutator lens 120 causes the laser beam LB emitted radially from the other end surface of the optical fiber 116 to enter the vent mirror 114 as parallel light.

  The laser diode power supply device of the present invention can be applied not only to laser welding but also to a laser processing machine that performs laser marking, drilling, cutting, and the like.

  The laser diode power supply device of the present invention is particularly suitable for driving the LD array as in the above embodiment, but may be used for driving a single LD.

It is a figure which shows the structure of the fiber laser processing machine to which the laser diode power supply device in one Embodiment of this invention is applied. It is a circuit diagram which shows the structure of the laser-diode power supply device in embodiment. It is a figure which shows the state or waveform of each part for demonstrating the effect | action of the laser diode power supply device in embodiment. It is a figure which shows the modification of an effect | action of the laser-diode power supply device in embodiment. It is a circuit diagram which shows the structure of the laser diode power supply device by one modification of embodiment. It is a figure which shows the structure of the YAG laser processing machine using the laser diode power supply device of this invention. It is a figure which shows the structure of the LD laser processing machine using the laser diode power supply device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fiber laser oscillator 12 Laser diode power supply device 30 LD array 70 Constant current source circuit 72 Inductance coil 74 1st switching element 76 2nd switching element 78 LD drive control part 82 Charging circuit 84 Capacitor 86 3rd switching element 90, 98 Current sensor 92,100 Current measurement circuit 94 Main current control unit 96 Diode 100 Main control unit 102 YAG laser oscillator 116 Optical fiber

Claims (18)

A laser diode power supply for driving a laser diode (LD) of an excitation light source to optically excite an active medium in a laser oscillator in a laser processing machine,
A constant current source circuit for supplying a desired constant current to the load circuit;
An inductance coil connected between the constant current source circuit and the laser diode;
A first switching element connected in series with the inductance coil and connected in parallel with the laser diode with respect to the constant current source circuit;
A laser diode having an LD drive control unit that holds the first switching element in an on state while the laser diode is not emitting light, and holds the first switching element in an off state when the laser diode is caused to emit light Power supply. A laser diode power supply for driving a laser diode (LD) of an excitation light source to optically excite an active medium in a laser oscillator in a laser processing machine,
A constant current source circuit for supplying a desired constant current to the load circuit;
An inductance coil connected between the constant current source circuit and the laser diode;
A first switching element connected in series with the inductance coil and connected in parallel with the laser diode with respect to the constant current source circuit;
An LD driving current measuring unit for measuring a current value of an LD driving current flowing through the laser diode;
The first switching element is kept on while the laser diode is not emitting light, and when the laser diode is caused to emit light, a current measurement value obtained from the LD drive current measuring unit is a preset reference value or reference A laser diode power supply unit comprising: an LD drive control unit configured to switch the first switching element so as to follow the waveform. A laser diode power supply for driving a laser diode (LD) of an excitation light source to optically excite an active medium in a laser oscillator in a laser processing machine,
A constant current source circuit for supplying a desired constant current to the load circuit;
An inductance coil connected between the constant current source circuit and the laser diode;
A first switching element connected in series with the inductance coil and connected in parallel with the laser diode with respect to the constant current source circuit;
A laser output measuring unit for measuring the laser output of the laser light oscillated and output from the laser oscillator;
While the laser diode is not emitting light, the first switching element is kept in an ON state, and when the laser diode is caused to emit light, a laser output measurement value obtained from the laser output measurement unit is set to a preset reference value or reference A laser diode power supply unit comprising: an LD drive control unit configured to switch the first switching element so as to follow the waveform.   4. The laser diode power supply device according to claim 2, wherein the LD drive control unit performs switching control of the first switching element by a pulse width modulation method. 5. A second switching element is connected in parallel with the first switching element and in series with the laser diode;
The LD drive control unit holds the second switching element in an off state while the laser diode is not emitting light, and holds the second switching element in an on state when the laser diode is caused to emit light. The laser diode power supply device according to any one of 1 to 4.   6. The diode according to claim 1, wherein one or a plurality of diodes are connected in parallel to the laser diode and in series with the first switching element in a forward direction with respect to a current flowing through the first switching element. A laser diode power supply device according to claim 1. The constant current source circuit is
A capacitor for storing power,
A charging circuit for charging the capacitor to a preset reference voltage;
A third switching element connected between the capacitor and the inductance coil;
A main current measuring unit for measuring a current value of a main current flowing through the inductance coil;
The main current control part which performs a switching operation of the 3rd switching element so that the current measurement value obtained from the main current measurement part may coincide with a preset reference value. The laser diode power supply device described in 1.   A number of the laser diodes are spatially arranged in a one-dimensional direction or a two-dimensional direction, and the plurality of laser diodes are electrically connected in series and / or in parallel according to the arrangement pattern. The laser diode power supply device according to any one of the above.   The laser diode power supply device according to any one of claims 1 to 8, wherein a drive current having a pulse waveform is supplied to the laser diode in order to oscillate the laser oscillator. A laser diode power supply device for driving a laser diode (LD) for oscillating and outputting laser light for laser processing,
A constant current source circuit for supplying a desired constant current to the load circuit;
An inductance coil connected between the constant current source circuit and the laser diode;
A first switching element connected in series with the inductance coil and connected in parallel with the laser diode with respect to the constant current source circuit;
A laser diode having an LD drive control unit that holds the first switching element in an off state while the laser diode is not emitting light, and holds the first switching element in an on state when the laser diode is caused to emit light Power supply. A laser diode power supply device for driving a laser diode (LD) for oscillating and outputting laser light for laser processing,
A constant current source circuit for supplying a desired constant current to the load circuit;
An inductance coil connected between the constant current source circuit and the laser diode;
A first switching element connected in series with the inductance coil and connected in parallel with the laser diode with respect to the constant current source circuit;
An LD driving current measuring unit for measuring a current value of an LD driving current flowing through the laser diode;
The first switching element is kept on while the laser diode is not emitting light, and when the laser diode is caused to emit light, a current measurement value obtained from the LD drive current measuring unit is a preset reference value or reference A laser diode power supply unit comprising: an LD drive control unit configured to switch the first switching element so as to follow the waveform. A laser diode power supply device for driving a laser diode (LD) for oscillating and outputting laser light for laser processing,
A constant current source circuit for supplying a desired constant current to the load circuit;
An inductance coil connected between the constant current source circuit and the laser diode;
A first switching element connected in series with the inductance coil and connected in parallel with the laser diode with respect to the constant current source circuit;
A laser output measuring unit for measuring a laser output of the laser beam oscillated and output from the laser diode;
While the laser diode is not emitting light, the first switching element is kept in an ON state, and when the laser diode is caused to emit light, a laser output measurement value obtained from the laser output measurement unit is set to a preset reference value or reference A laser diode power supply unit comprising: an LD drive control unit configured to switch the first switching element so as to follow the waveform.   The laser diode power supply device according to claim 11 or 12, wherein the LD drive control unit performs switching control of the first switching element by a pulse width modulation method. A second switching element is connected in parallel with the first switching element and in series with the laser diode;
The LD drive control unit holds the second switching element in an off state while the laser diode is not emitting light, and holds the second switching element in an on state when the laser diode is caused to emit light. The laser diode power supply device according to any one of 10 to 13.   15. The diode according to claim 10, wherein one or a plurality of diodes are connected in parallel to the laser diode and in series with the first switching element with respect to a current flowing through the first switching element. A laser diode power supply device according to claim 1. The constant current source circuit is
A capacitor for storing power,
A charging circuit for charging the capacitor to a preset reference voltage;
A third switching element connected between the capacitor and the inductance coil;
A main current measuring unit for measuring a current value of a main current flowing through the inductance coil;
The main current control part which performs switching operation of the 3rd switching element so that the current measurement value obtained from the main current measurement part may coincide with a preset reference value. The laser diode power supply device described in 1.   17. A plurality of laser diodes spatially arranged in a one-dimensional direction or a two-dimensional direction, and the plurality of laser diodes are electrically connected in series and / or in parallel according to the arrangement pattern. The laser diode power supply device according to any one of the above.   18. The laser diode power supply device according to claim 10, wherein a drive current having a pulse waveform is supplied to the laser diode in order to cause the laser diode to oscillate.

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