JP2549129Y2 - Laser power supply - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser power supply for driving a lamp for exciting a laser.

[0002]

2. Description of the Related Art A laser power supply of this type is used for a solid-state laser such as a YAG laser. FIG. 3 shows a circuit configuration of a conventional laser power supply of this type. In this laser power supply, for example, a commercial three-phase alternating current (R, S, T) of 200 V is input to the three-phase input terminal. The input commercial three-phase alternating current is supplied to the three-phase
The voltage is increased to 00V. The three-phase AC boosted by the three-phase transformer 100 is input to a three-phase full-wave rectifier circuit 102 having six thyristors SR1 to SR6 connected in a three-phase bridge,
Here, it is converted to direct current. The DC output from the three-phase full-wave rectifier circuit 102 is charged to a capacitor 106 via the reactor 104 to a predetermined charging voltage.

[0003] The capacitor 106 has a transistor 1
08 and the excitation lamp 112 via the diode 110
Are connected in series. When the transistor 108 is turned on while the capacitor 106 is charged to a predetermined charging voltage, the capacitor 106 is discharged, and the discharge current flows through the excitation lamp 112 as the lamp current IR, and the lamp 112 is turned on. When the lamp 112 is turned on, the light energy excites the YAG rod 114 and causes laser oscillation. Laser light LB emitted from both end surfaces of the YAG rod 114 by laser oscillation is repeatedly reflected between the output mirror 116 and the reflection mirror 118, amplified, and then output through the output mirror 116.

A resistor 1 is connected in parallel with the capacitor 106.
A discharge circuit including the transistor 20 and the transistor 122 is connected. This discharge circuit discharges the capacitor 106 when the charge voltage of the capacitor 106 exceeds a set value, and lowers the charge voltage to the set value.

[0005]

Generally, this type of laser power supply device is housed in a housing in combination with a laser oscillation section to constitute a unit type laser device. Since such a housing also accommodates a cooling unit such as a pump or a tank that supplies cooling water to the laser oscillation unit, the weight of the entire laser device unit becomes considerable. In the conventional laser power supply device as described above, the transformer 100 is particularly heavy, and the transformer 100 weighs approximately 200 kg. When the transformer 100 is heavy as described above, the housing for housing the transformer is also strong and heavy, and the total weight of the laser unit may exceed 1 ton. If the laser device unit is so heavy, it is difficult to move it.If the laser device unit is installed on the mezzanine floor of a factory and connected to a portable laser emitting unit using an optical fiber, the members supporting the device unit and the middle The two-story structure had to be solid.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a laser power supply device which realizes a light weight and a small size and drives and drives a pumping lamp for laser oscillation with high efficiency. .

[0007]

In order to achieve the above object, a first laser power supply device according to the present invention supplies a lamp current to an excitation lamp that irradiates a laser medium with light energy for laser oscillation. A first rectifier circuit that converts commercial AC into DC, an inverter circuit that converts the DC output from the first rectifier circuit into a high-frequency AC, and a power supply that is output from the inverter circuit. A transformer for boosting a high-frequency AC, current detecting means for detecting a primary or secondary current of the transformer, and controlling a switching operation of the inverter circuit based on a current measurement value obtained from the current detecting means. Inverter control means, a second rectifier circuit for converting high-frequency AC output from the transformer into DC, and the excitation circuit as viewed from the second rectifier circuit. A capacitor that is connected in parallel with the pump and charges the DC output from the second rectifier circuit, a switching element connected between one terminal of the capacitor and one terminal of the excitation lamp, and the switching element Control means for controlling on / off of the capacitor, and discharging the capacitor by turning on the switching element, and a capacitor discharging means for supplying the discharge current to the excitation lamp as the lamp current. .

A second laser power supply device of the present invention is a laser power supply device for supplying a lamp current to an excitation lamp that irradiates a laser medium with light energy for laser oscillation. A rectifier circuit, an inverter circuit for converting the DC output from the first rectifier circuit to a high-frequency AC, a transformer for boosting the high-frequency AC output from the inverter circuit, and a primary side of the transformer. Or a current detecting means for detecting a current on the secondary side, an inverter controlling means for controlling a switching operation of the inverter circuit based on a current measurement value obtained by the current detecting means, and a high-frequency AC output from the transformer. A second rectifier circuit for converting DC to DC, a switching element connected in series with the excitation lamp as viewed from the second rectifier circuit, and Control means for controlling on / off of the switching element, wherein the direct current output from the second rectifier circuit is converted into a predetermined waveform by a predetermined switching operation and supplied to the excitation lamp as the lamp current. .

[0009]

In the first laser power supply, commercial AC is converted into DC by a first rectifier circuit, and DC output from the first rectifier circuit is converted into high-frequency AC by an inverter circuit. Then, the high-frequency AC output from the inverter circuit is boosted by the transformer and then converted into DC by the second rectifier circuit, and the DC output from the second rectifier circuit is supplied to a lamp lighting capacitor, Charge. After the capacitor is charged to a predetermined voltage, the capacitor discharging means discharges the capacitor at a predetermined timing, whereby the discharge current is supplied to the excitation lamp as a lamp current, and the lamp is turned on. Since the switching operation of the inverter circuit is controlled by the feedback control (for example, PWM control) by the current detection means and the inverter control means, the charging current is supplied to the capacitor stably and efficiently. Since the transformer passes high-frequency alternating current, it may be light and small.

In the second laser power supply, commercial AC is converted into DC by a first rectifier circuit, and DC output from the first rectifier circuit is converted into high-frequency AC by an inverter circuit. Then, the high-frequency AC output from the inverter circuit is boosted by the transformer and then converted into DC by the second rectifier circuit. The DC output from the second rectifier circuit is converted into a predetermined waveform by the switching means, and the lamp is converted to a predetermined waveform. An electric current is supplied to the excitation lamp, and the lamp is turned on. Also in this laser power supply device, the switching operation of the inverter circuit is controlled by the feedback control (for example, PWM control) by the current detection means and the inverter control means, so that the lamp current is supplied to the excitation lamp stably and efficiently. Further, since the transformer passes high-frequency alternating current, it may be light and small.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a configuration of a laser power supply for a YAG laser according to a first embodiment of the present invention. In this laser power supply, a three-phase input terminal 10 is connected to an input terminal of a three-phase full-wave rectifier circuit 12 formed by bridge-connecting six diodes D1 to D6. An output terminal of the three-phase full-wave rectifier circuit 12 is connected to an input terminal of an inverter circuit 16 via a capacitor 14 for smoothing. The inverter circuit 16 comprises four switching transistors TR1 to TR4 connected in a bridge, and the transistors TR1 and TR3 and the transistors TR2 and TR4 in response to the inverter drive signals Fa and Fb from the drive circuit 52.
Are sufficiently higher than the commercial frequency (for example, 1 k
(Hz).

The output terminal of the inverter circuit 16 is the transformer 1
8, the secondary coil of the transformer 18 is connected to the input terminal of a single-phase full-wave rectifier circuit 20, which is a bridge connection of four diodes D7 to D10.
The output terminal of the single-phase full-wave rectifier circuit 20 is connected to both terminals of a lamp lighting capacitor 22. This capacitor 22 is connected in series to an excitation lamp 28 via a lamp lighting transistor 24 and a diode 26. Further, a discharging circuit including a resistor 30 and a transistor 32 is connected in parallel with the capacitor 22. A YAG rod 34 is located adjacent to the excitation lamp 28,
An output mirror 36 and a reflection mirror 38 are arranged facing both end surfaces of the AG rod 34. The excitation lamp 28 and the YAG rod 34 are cooled by cooling water from a laser cooling unit (not shown).

The laser power supply unit is also provided with control units 40 to 50 for controlling the above-described units. The lighting control unit 40 turns on the lamp lighting transistor 24 and discharges the capacitor 22 while the capacitor 22 is charged to a predetermined charging voltage. When the capacitor 22 discharges, the discharge current flows through the excitation lamp 28 as the lamp current IR, and the lamp 28 is turned on. Lamp 28
Is turned on, the light energy excites the YAG rod 34 to cause laser oscillation. The laser light LB emitted from both end surfaces of the YAG rod 34 by the laser oscillation is repeatedly reflected between the output mirror 36 and the reflection mirror 38, amplified, and then output through the output mirror 36.

The charging voltage detecting circuit 42 includes a capacitor 22
, That is, the capacitor charging voltage, and the voltage detection value is given to the charge / discharge control unit 44. When the charge voltage of the capacitor 22 exceeds the set value, the charge / discharge control unit 44 turns on the transistor 32 through the drive circuit 45 and sets the capacitor 22 to the resistance 30
And the discharging circuit of the transistor 32 discharges the charge voltage to the set value.

The primary circuit of the transformer 18 is provided with a current sensor 46 composed of, for example, a Hall CT. Based on an output signal from the current sensor 46, a measured value of the primary current is obtained by a current value measuring circuit 48. Can be Current value measurement circuit 48
Is supplied to the charge / discharge control unit 44.

The charge / discharge control unit 44 includes a charge voltage detection circuit 4
A charge signal is sent to the inverter control unit 50 so as to charge the capacitor 22 to a predetermined charge voltage based on the charge voltage detection value from Step 2. The inverter control unit 50 generates high frequency (1 kHz) inverter control signals fa and fb for the inverter circuit 16 according to the charge signal from the charge / discharge control unit 44. The drive circuit 52 amplifies the inverter control signals fa and fb from the inverter control unit 50 to obtain inverter drive signals Fa and Fb, and the transistor T of the inverter circuit 16 is controlled by the inverter drive signals Fa and Fb.
R1 to TR4 are switched and driven. Further, the inverter control unit 50 controls the inverter control signals fa and f based on the current detection value from the current value measurement circuit 48 so that the charging current Ic for the capacitor 22 flows through the constant current control.
b is subjected to pulse width modulation, and when an abnormal current flows, control such as stopping the operation of the inverter circuit 16 is performed to protect the switching element.

In the laser power supply device having such a configuration, for example, a 200 V commercial three-phase alternating current (R, S, T) input from the input terminal 10 is converted into a direct current by the three-phase full-wave rectifier circuit 12. The DC from the three-phase full-wave rectifier circuit 12 is converted by the inverter circuit 16 into a high-frequency AC of, for example, 1 kHz. The high-frequency AC is boosted to, for example, 500 V by the transformer 18 and then input to the rectifier circuit 20. Is converted to DC, and the DC charges the capacitor 22. Since the transformer 18 passes high-frequency alternating current from the inverter circuit 16, a light and small transformer is sufficient even when performing high-output laser oscillation. Generally, it is considered that the weight of the transformer is reduced in inverse proportion to the magnitude of the AC frequency. Therefore, when the inverter frequency is set to 1 kHz, the weight of the transformer is reduced to about 1/20 as compared with the case where commercial AC (50 or 60 Hz) is passed through the transformer as it is (conventional method). Can be. Therefore, a transformer that used a transformer weighing approximately 200 kg in the past can be replaced with a transformer weighing more than 10 kg, and the entire power supply device, and thus the entire laser device, can be significantly reduced in size and weight. The movement and installation of the device unit are facilitated.

FIG. 2 shows a configuration of a laser power supply device according to a second embodiment. In the figure, parts having the same configuration and function as those in FIG. 1 are denoted by the same reference numerals. While the laser power supply according to the first embodiment generates a high-output pulse or oscillates a repetitive pulse, the laser power supply according to the second embodiment is capable of continuous oscillation. .

In the laser power supply device shown in FIG. 2, the output terminal of the single-phase full-wave rectifier circuit 20 has a smoothing capacitor 60,
Switching transistor 62, coil 6 for smoothing
4, connected to an electrode terminal of the excitation lamp 28 via a capacitor 66 and a diode 68. Coil 64
The diode 70 connected in parallel with the capacitor 66 with the interposed therebetween constitutes a return circuit for returning the electromagnetic energy stored in the coil 64.

The PWM control signal SA from the switching controller 72 is provided at the base of the switching transistor 62.
Is provided as a switching control signal via the drive circuit 74. The switching transistor 62 is turned on and off at a high frequency by the PWM control signal SA, so that a DC current having a pulse width modulated chopper waveform is obtained at its collector terminal. The DC current having the chopper waveform passes through the smoothing coil 64 and the capacitor 66 to be converted into a DC current having an envelope waveform corresponding to the pulse width, and this DC current is supplied to the excitation lamp 28 via the diode 68 as the lamp current IR. Supplied.

A circuit through which the lamp current IR flows is provided with a current sensor 76 composed of, for example, a toroidal coil. Based on an output signal of the current sensor 76, a current value measuring circuit 78 obtains a current measurement value of the lamp current IR. The switching control unit 72 receives the current measurement value from the current value measurement circuit 78, and performs PWM control by a feedback method such that the current measurement value follows a preset reference current waveform.

In this laser power supply device, the input commercial three-phase alternating current (R, S, T) is converted into a three-phase full-wave rectifier circuit 12.
Is converted to a direct current, and this direct current is once converted into a high-frequency alternating current of 1 kHz by the inverter circuit 16, for example.
The high-frequency AC is boosted by the transformer 18 and then converted to DC by the single-phase rectifier circuit 20. This DC is controlled to an arbitrary waveform by PWM control by the switching transistor 62 and is supplied to the excitation lamp 28 as a lamp current IR. I am trying to supply. As described above, also in this laser power supply device, since the transformer 18 passes the high-frequency AC from the inverter circuit 16, it can be constituted by a light and small transformer, and the entire laser power supply device, Significant weight reduction of the whole device can be realized.

Although the three-phase commercial AC is input in the above-described embodiment, a single-phase commercial AC may be input.
In the above embodiment, the inverter control is performed by the PWM control method, but a variable frequency control method may be used. Further, the switching element is not limited to a transistor, and may be an IGBT, an FET, or the like. Furthermore, the power supply device of the present invention is not limited to the YAG laser, but can be applied to any laser device using an excitation lamp.

[0024]

As described above, according to the laser power supply device of the present invention, the commercial AC is temporarily converted to DC, and this DC is converted into high-frequency AC by an inverter circuit that performs switching operation by a feedback control method. This high-frequency alternating current is boosted by a transformer and then converted to direct current, and the direct current is used to drive the lamp through a lamp lighting capacitor or switching means, so that the charging current or the lamp current can be stabilized and efficiently. Supply and use a lightweight and compact transformer,
The entire power supply can be significantly reduced in weight and size.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a laser power supply device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a laser power supply device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration of a conventional laser power supply device.

[Explanation of symbols]

 Reference Signs List 12 three-phase full-wave rectifier circuit 16 inverter circuit 18 transformer 20 single-phase full-wave rectifier circuit 22 lamp lighting capacitor 24 lamp lighting transistor 28 excitation lamp 40 lighting control unit 50 inverter control unit 62 switching transistor 72 switching control unit

Continuation of front page (56) References JP-A-63-157679 (JP, A) JP-A-1-185598 (JP, A) JP-A-3-76176 (JP, A) JP-A-63-69428 (JP) JP-A-63-157679 (JP, A) JP-A-1-223789 (JP, A) JP-A-2-140984 (JP, A) JP-A-3-16416 (JP, A) 4-56375 (JP, A) JP-A-4-234181 (JP, A) JP-A-63-181388 (JP, A)

Claims (2)

(57) [Scope of request for utility model registration] 1. A laser power supply for supplying a lamp current to an excitation lamp for irradiating a laser medium with light energy for laser oscillation on a laser medium, comprising: a first rectifier circuit for converting commercial AC to DC; An inverter circuit that converts the DC output from the rectifier circuit into a high-frequency AC; a transformer that boosts the high-frequency AC output from the inverter circuit; and detects a primary or secondary current of the transformer. Current detection means; inverter control means for controlling a switching operation of the inverter circuit based on a current measurement value obtained from the current detection means; and second rectifier for converting high-frequency AC output from the transformer into DC. A circuit that is connected in parallel with the excitation lamp as viewed from the second rectifier circuit and charges the DC output from the second rectifier circuit; Includes a capacitor, and a control means for controlling the on and off of the switching elements connected to said switching element between the one terminal of the excitation lamp and one terminal of said capacitor,
A laser power supply device comprising: capacitor discharging means for turning on the switching element to discharge the capacitor and supplying the discharge current to the excitation lamp as the lamp current. 2. A laser power supply for supplying a lamp current to an excitation lamp for irradiating a laser medium with laser light energy to a laser medium, comprising: a first rectifier circuit for converting a commercial alternating current into a direct current; An inverter circuit that converts the DC output from the rectifier circuit into a high-frequency AC; a transformer that boosts the high-frequency AC output from the inverter circuit; and detects a primary or secondary current of the transformer. Current detection means; inverter control means for controlling a switching operation of the inverter circuit based on a current measurement value obtained from the current detection means; and second rectifier for converting high-frequency AC output from the transformer into DC. A switching element connected in series with the excitation lamp as viewed from the second rectifier circuit; and an on / off switch of the switching element. And a switching means for converting the DC output from the second rectifier circuit into a predetermined waveform by a predetermined switching operation and supplying the same as the lamp current to the excitation lamp. Characteristic laser power supply.