JPH1197769A - Laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an expected laser output stably by minutely regulating the temperature of cooling water fed to a laser oscillation section stably. SOLUTION: A cooling-water supply section 24 is composed of a tank 26, in which pure water CW is stored, and a pump 28 and pipings 30, 32, 34, 36 circulating pure water CW between the tank 26 and a laser oscillation section 10, and cooling water such as pure water CW is circulated and fed to the laser oscillation section 10. A temperature regulating mechanism for regulating the temperature of pure water CW is installed to the cooling-water supply section 24. The temperature regulating mechanism is constituted of a cooling section 42 mounted between the pipings 34, 36, an electric heater 44 set up into the tank 26, a temperature sensor 46 fitted on its midway of the piping 32, and a temperature control section 48 for controlling the electric-conduction heat- generating operation of the electric heater 44 in response to an output signal TS from the temperature sensor 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0010]

The present invention relates to a water-cooled laser device.

[0020]

2. Description of the Related Art FIG. 10 shows a configuration of a laser cooling mechanism in a conventional solid-state laser device.

As shown, a tank 100 for storing cooling water, for example, pure water CW, and a laser oscillation unit 102 are connected to a pipe 1.
04, 105, 106, 107, a pump 108 and a heat exchanger 110. Pure water CW pumped from the tank 100 by the pump 108 is connected to the pipe 1
The laser light is supplied to the laser oscillation unit 102 through the laser oscillators 104 and 105. In the laser oscillation section 102, the pure water CW absorbs heat from the excitation light source and the laser medium, so that the water temperature rises somewhat. The pure water CW discharged from the laser oscillating unit 102 is introduced into the secondary water passage of the heat exchanger 110 through the pipe 106.

The heat exchanger 110 is a water-cooled heat exchanger (water-
Water heat exchanger), the primary side of which is a pipe 112,
114, for example, circulating water FW in the facility
(Not shown). The in-facility circulating water FW from the circulating water supply source has a lower water temperature than the pure water CW, is introduced into the primary side water channel of the heat exchanger 110 through the pipe 112, and After being subjected to heat exchange with the secondary side cooling water (pure water CW), the heat exchanger 110
Is discharged from the primary side water channel and returned to the circulating water supply source through the pipe 114.

An electromagnetic valve 116 is provided in one of the city water pipes, for example, in the middle of the pipe 112. While the electromagnetic valve 116 is open, the in-facility circulating water FW is supplied to the primary side water channel of the heat exchanger 110, and the heat between the primary side and the secondary side as described above in the heat exchanger 110. The replacement is performed, and the secondary side cooling water (pure water CW) is cooled. When the solenoid valve 116 closes,
The supply of the in-facility circulating water FW to the heat exchanger 110 is cut off,
The heat exchange or cooling operation in the heat exchanger 110 is interrupted. The open / closed state of the solenoid valve 116 is determined by the temperature control unit 11.
8.

The pure water CW cooled to a predetermined temperature in the heat exchanger 110 returns to the tank 100 through the pipe 107.
A temperature sensor 120 for detecting the temperature of the pure water CW is provided in the tank 100.
An electric signal (water temperature detection signal) ES indicating the temperature of W is output. The temperature control unit 118 receives the water temperature detection signal ES from the temperature sensor 120, and matches the water temperature detection signal ES with a set value, that is, maintains the temperature of the pure water CW in the tank 100 at the set temperature. Solenoid valve 116
Open / close control.

FIG. 11 shows another configuration of the laser cooling mechanism in the conventional solid-state laser device.

In this system, an evaporation (vaporization) type heat exchanger 122 is disposed in the tank 100, and the heat exchanger 122
A refrigeration cooler 124 provided outside the tank 100 is connected via piping 126 and 128. Heat exchanger 122
Has a built-in evaporator, and a cooler (refrigerator) 124 has a built-in compressor, condenser and the like.

The liquid refrigerant from the cooler 124 is supplied to the pipe 12
6, it is introduced into the evaporator in the heat exchanger 122, where it evaporates by removing heat from the surroundings (pure water CW) and changes to a gaseous state. The gaseous refrigerant from the heat exchanger 122
The refrigerant is led through 8 to a compressor in a cooler 124, where it is compressed into a high-temperature, high-pressure refrigerant gas. Next, the high-temperature and high-pressure refrigerant gas is led to a condenser, where it releases heat to the surroundings and returns to a liquid refrigerant.

The temperature control section 130 receives the water temperature detection signal ES from the temperature sensor 120 in the tank 100, and adjusts the water temperature of the pure water CW in the tank 100 so that the water temperature detection signal ES matches the set value. The operation (on / off) of the cooler 124, particularly the compressor, is controlled so as to adjust to the set temperature.

[0110]

In this type of solid-state laser device, in order to obtain a stable laser output, it is necessary to maintain the temperature of the cooling water supplied to the laser oscillation section 102 at a set temperature with high accuracy. is there.

In this regard, in the system of FIG. 10, the temperature of the pure water CW is adjusted depending on whether the primary side cooling water FW flows through the heat exchanger 110 (whether or not the flow is stopped). There is a principle limitation in speeding up and refinement of the image.

Also, in the system shown in FIG. 11, the temperature of the pure water CW is adjusted depending on whether or not the refrigerant is supplied to the heat exchanger 122, and the same limitation is imposed on the speeding up and the miniaturization of the cooling cycle. . Further, in the case of a refrigeration cycle, frequent repetition of ON / OFF is not preferable in terms of the safety operation of the system.

As described above, in the conventional solid-state laser device,
Cooling water (pure water CW) in a manner that controls the operating rate of heat exchange between the cooling water (pure water CW) and a cooling medium at a lower temperature.
Since the switching of the flow of the cooling medium (on / off) and the start of heat exchange involve inertia (time delay), one cooling cycle for cooling water (pure water CW) Inevitably, the down time between cooling cycles will be longer. For this reason, the cooling operation is intermittent, and fine and stable temperature control cannot be expected. Therefore, it is difficult to control the temperature to the set temperature with high accuracy.

By using an inverter for controlling the operation of the compressor in the refrigerator, continuous (proportional) control of the refrigeration cycle becomes possible. However, this method has a problem that the device becomes complicated and expensive.

The present invention has been made in view of the above-mentioned problems of the prior art, and the temperature of cooling water supplied to a laser oscillation section is finely and stably controlled in a continuous manner to stabilize an intended laser output. It is an object of the present invention to provide a laser device which is obtained.

Another object of the present invention is to provide a laser device capable of performing fine and stable temperature adjustment with a simple configuration.

Further, it is another object of the present invention to provide a laser device capable of performing fine and stable temperature control with low noise.

[0190]

In order to achieve the above object, a first laser device according to the present invention comprises a laser oscillating section for generating a laser beam, and a cooling device for circulating a cooling medium to the laser oscillating section. Water supply means, cooling means for cooling the cooling medium outside the laser oscillation section, electric heating means for heating the cooling medium by generating heat by energizing outside the laser oscillation section, and A temperature sensor for detecting a temperature, and a temperature for controlling an energization period per unit time of the electric heating means in accordance with an output signal of the temperature sensor so that a temperature of the cooling medium supplied to the laser oscillation unit matches a set temperature. And an adjusting means.

[0200] In the second laser device of the present invention, in the configuration of the first laser device, the temperature adjusting means compares the output signal of the temperature sensor with a reference value corresponding to the set temperature. Comparing means for generating an error signal indicating the comparison error; pulse width controlling means for outputting a conduction control pulse having a pulse width corresponding to the magnitude of the error signal from the comparing means at a constant frequency; And an energization control means for controlling on / off of energization in the electric heating means according to an energization control pulse from the means.

[0210] Also, in the third laser device of the present invention, in the configuration of the first laser device, the temperature adjusting means may compare an output signal of the temperature sensor with a reference value corresponding to the set temperature. Comparing means for generating an error signal representing the comparison error; voltage-frequency converting means for outputting a frequency pulse whose frequency changes in accordance with the voltage level of the error signal from the comparing means; A monostable multivibrator that outputs an energization control pulse having a constant pulse width in response to a frequency pulse from the means; and an on / off control of energization in the electric heating means in response to the energization control pulse from the monostable multivibrator. Power supply control means for controlling turning off.

[0220] Also, in the fourth laser device of the present invention, in the configuration of the second or third laser device, the energization control means may include a switch means connected between the electric heating means and an AC power supply. A zero-crossing detecting means for detecting a timing at which an AC voltage from the AC power supply crosses a zero level; and the zero-crossing detecting signal from the zero-crossing detecting signal from the zero-crossing detecting means immediately after the start of an ON period defined by the energization control pulse. Switching control means for switching the switch means from the off state to the on state, and for switching the switch means from the on state to the off state at the end of the on period.

A fifth laser device according to the present invention is characterized in that, in the structure of any one of the first to fourth laser devices, the cooling means performs the cooling operation continuously without interruption. .

A sixth laser device according to the present invention, in the configuration of any one of the first to fifth laser devices, wherein the cooling means comprises the cooling medium and a cooling medium of a different system having a lower temperature than the cooling medium. And a heat exchange means for causing a heat exchange between the first and second cooling media to lower the temperature of the cooling medium.

[0250]

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 main part of a solid-state laser processing apparatus according to an embodiment of the present invention.

In this solid-state laser processing apparatus, a laser excitation light source such as an excitation lamp
The laser medium, for example, the YAG rod 14 is arranged in a reflection barrel (not shown) in a chamber 16 made of, for example, an acrylic resin. Y outside chamber 16
On the optical axis of the AG rod 14, a pair of optical resonator mirrors 1
8, 20 are arranged facing each other in parallel with the rod 14 interposed therebetween.

When the excitation lamp 12 is turned on by the lamp current I supplied from the laser power supply unit 22, the light energy excites the YAG rod 14 and the light emitted from both end faces of the YAG rod 14 is reflected by the optical resonator mirror 18,
The laser light L after being amplified by repeating reflection between 20
The light exits the output mirror 18 as B. The laser beam LB that has passed through the output mirror 18 is directed to a processing point of a workpiece (not shown) via a mirror (not shown) or via an incidence unit, an optical fiber, and an emission unit (not shown). Irradiation is aimed at.

Cooling water, for example, pure water CW, whose temperature is controlled by a cooling water supply unit 24 described later, is sent to a cooling water inlet 16a of the chamber 16, and the pure water CW in the chamber 16 causes the excitation lamp 12 and the YAG rod 14 to pass therethrough. The pure water CW flows through the surrounding water channel and is returned to the cooling water supply unit 24 from the cooling water discharge port 16 b of the chamber 16. The pure water CW whose temperature has been controlled in this manner is supplied to the excitation lamp 12 and the YA of the laser oscillation unit 10.
By being supplied to the G rod 14, the laser oscillation efficiency is increased and the laser output is stabilized.

[0300] The cooling water supply unit 24 in this embodiment includes a tank 26 for storing pure water CW and a pump 2 for circulating the pure water CW between the tank 26 and the laser oscillation unit 10.
8, a pipe 30, 32, 34, 36 and a cooling unit 42.

The pure water CW pumped out of the tank 26 by the pump 28 is supplied to the chamber 16 of the laser oscillation section 10 through the pipes 30 and 32. And chamber 1
The pure water discharged from 6 is collected in the tank 26 through the pipes 34 and 36.

[0320] In the tank 26, an ion exchange resin 38 and a filter 40 are arranged in a state of being submerged in pure water CW. The pure water CW collected in the tank 26 via the pipe 36 is first introduced into the ion exchange resin 38, where unnecessary ions are removed, and the purity is restored. Pure water CW that has flowed out of the ion exchange resin 38 is filtered by the filter 4 in the tank.
, The dust and organic matter are removed therefrom and then discharged to the outside of the tank 26 (the pipe 30).

This solid-state laser processing apparatus has a temperature adjustment mechanism for precisely and stably keeping the temperature of the pure water CW supplied to the laser oscillation section 10 at a set temperature. In this embodiment, the temperature control mechanism includes a cooling unit 42 provided between the pipes 34 and 36 and a tank 26.
An electric heater 44 provided in the inside, a temperature sensor 46 provided in the middle of the pipe 32, and a temperature controller (controller) for controlling the energizing and heating operation of the electric heater 44 in accordance with an output signal TS from the temperature sensor 46 ) 48.

In order to lower the temperature of the pure water CW discharged or recovered from the laser oscillating unit 10 to an appropriate water temperature, the cooling unit 42 is provided between the pure water CW and the primary cooling medium CM having a lower temperature. The heat exchanger 50 includes a heat exchanger 50 that performs heat exchange, and a cooler 52 that supplies the primary-side cooling medium CM to the heat exchanger 50. The primary side cooling medium CM may be city water or facility circulating water in the case of a water-cooled type, and a refrigerant gas (hydro-fluorocarbon: HF) in the case of an evaporative or refrigerated type.
C or hydrochlorofluorocarbon: HC
FC etc.).

The cooler 52 incorporates an electromagnetic (open / close) valve in the case of a water-cooled type, and incorporates a compressor and a condenser in the case of a refrigeration type. While the power of the laser processing apparatus is turned on, the cooler 52 continuously supplies the primary-side cooling medium CM to the heat exchanger 50 without interruption, and therefore, the cooling unit 42 performs its cooling operation continuously without interruption. .

The temperature control mechanism of this embodiment controls the temperature of the pure water CW in the cooling water supply unit 24 by using both the cooling by the cooling unit 42 and the heating by the electric heater 44. For this reason,
The cooling power in the cooling unit 42 is set to be stronger than that of the conventional device that does not perform heating.

The electric heater 44 has an element that generates heat when energized, for example, a heating wire. In this embodiment, the tank 26
The heating wire may be accommodated in a closed case made of an insulating material having high thermal conductivity, for example, ceramic.

The temperature sensor 46 is composed of, for example, a thermocouple or a thermistor, and outputs an electric signal (water temperature detection signal) TS representing the temperature of the pure water CW flowing in the pipe 32. In addition to the temperature sensor 46, sensors such as a conductivity sensor 54 and a pressure sensor (not shown) are also attached to the pipe 32.

The temperature control unit 48 receives the water temperature detection signal TS from the temperature sensor 46, and compares the water temperature detection signal TS with a reference value corresponding to the set temperature, as described later, and responds to the comparison error. The power supply period of the electric heater 44 per unit time is controlled by a pulse width modulation method.

FIG. 2 shows an example of a circuit configuration of the temperature control section 48. The temperature control unit 48 compares a temperature detection signal TS from the temperature sensor 46 with a predetermined reference value to generate an error signal indicating a comparison error between the temperature detection signal TS and the comparison unit 60.
A pulse width control (PWM) circuit 62 for outputting an energization control pulse having a pulse width corresponding to the magnitude of the obtained error signal at a constant frequency (for example, 5 Hz);
An energization control unit 64 that controls ON (energization) / OFF (non-energization) of the electric heater 44 according to an energization control pulse from the circuit 62 is provided.

The comparing section 60 includes a proportional amplifier circuit 66, a differentiating circuit 68, an adding circuit 70, a reference value generator 72, and a comparing circuit 7.
4. It is composed of an integrating circuit 76 and an adding circuit 78.

The input temperature detection signal TS is proportionally amplified by the proportional amplification circuit 66 and differentiated by the differentiation circuit 68. The output signal of both circuits 66 and 68 is added by the addition circuit 70 to obtain a corrected temperature detection signal. The signal TS ′ is input to one input terminal of the comparison circuit 74. Comparison circuit 74
The reference value KS from the reference value generator 72 is input to the other input terminal. This reference value KS is determined by the laser oscillation unit 1
It has a voltage level corresponding to the set temperature for the pure water CW immediately before being supplied to zero.

[0430] The comparing circuit 74 is provided with two input signals TS 'and KS.
Are compared, and the comparison error or difference [K
When S-TS '] is positive (that is, when KS>TS'), an intermediate error signal δ representing the magnitude of the comparison error is output.

Note that the comparison error or difference [KS-T
When S ′] is negative (when KS <TS ′), nothing is output from the comparison circuit 74. That is, pure water CW
When the water temperature exceeds the set temperature, the comparison circuit 74 does not output the intermediate error signal δ, so that the energization control section 64 in the subsequent stage does not energize the electric heater 44 to generate heat.

The intermediate error signal δ from the comparison circuit 74 is input to one input terminal of the addition circuit 78 and is also input to the integration circuit 76, and the output signal of the integration circuit 76 is input to the other input terminal of the addition circuit 78 Is done. As a result, the adding circuit 78 outputs a voltage signal obtained by adding the integral value Σδ to the intermediate error signal δ as a normal error signal ΔE.

The PWM circuit 62 includes, for example, a saw-tooth wave generating circuit for generating a saw-tooth wave signal having a constant frequency,
A comparator for comparing a voltage level of the error signal ΔE from 0 with a voltage level of the sawtooth signal and generating a binary signal or a pulse having an H level or an L level according to the magnitude relation thereof; In. The pulse output from the comparator of the PWM circuit 62 is supplied to the base terminal of the switching transistor 80 as a conduction control pulse CP. As described later, the H-level period of the energization control pulse CP defines an energization period within a unit cycle of the electric heater 44, and thus defines an energization period per unit time.

The switching transistor 80 and the photocoupler 82 connected in series to the switching transistor 80
2 is transmitted to the power supply control unit 64. That is, when the energization control pulse CP is at the H level,
The transistor 80 is turned on, the light emitting diode 82a emits light in the photocoupler 82, and the phototriac 82b
Is turned on. When the energization control pulse CP is at the L level, the transistor 80 is turned off and the photocoupler 82
Inside, the light emitting diode 82a does not emit light and the phototriac 82b is turned off.

The power supply controller 64 detects the triac 86 connected between the electric heater 44 and the commercial AC power supply 84 and the timing at which the AC voltage V from the AC power supply 84 crosses the zero level at a frequency of 50 Hz or 60 Hz. The triac 86 is turned on / off in response to the energization control pulse CP from the PWM circuit 62 and the zero cross detection signal ZS from the zero cross detection circuit 88.
And a switching control circuit 90 for switching off state.

The switching control circuit 90 monitors the logic level of the energization control pulse CP through the on / off state of the phototriac 82b, and turns on the triac 86 while the pulse CP is at the H level to turn on the electric heater. 4
4 is energized.

More precisely, immediately after the pulse CP goes to the H level, the zero-cross detection circuit 88 first detects the AC voltage V
Is detected (ie, when the first zero-crossing detection signal ZS is generated), the switching control circuit 90
Supplies an ON control signal RG to the gate terminal of the triac 86 to turn on the triac 86. When the triac 86 is turned on, the AC voltage V (electric power) from the AC power source 84 is supplied to the electric heater 44 via the triac 86.
And the electric heater 44 is energized to generate heat.

Thereafter, when the pulse CP falls from the H level to the L level, in response to this, the switching control circuit 90 stops supplying the ON control signal RG. As a result, the triac 86 is automatically switched to the off state at the zero cross point immediately after the triac 86. When the triac 86 is turned off, the supply of the AC voltage V from the AC power supply 84 is cut off, and the heating of the electric heater 44 is interrupted.

[0520] When the energization control pulse CP goes to the H level again, the energization and heat generation of the electric heater 44 is resumed by the same switching control as described above, and when the pulse CP returns to the L level, the electric heater 44 is subjected to the same switching control as described above. Heating of the electricity stops. The heating of the electric heater 44 stops.

In this manner, the electric heater 44 is energized and generates heat in accordance with the pulse width of the energization control pulse CP given at a constant frequency (5 Hz), so that the heating operation of the electric heater 44 with respect to the pure water CW in the tank 26 is performed. Is performed continuously without interruption by the PWM control method.

FIG. 3 shows the operation of the temperature control mechanism of the present embodiment, for example, when the operation of the electric heater 44 is started from a state in which the temperature of the pure water CW is considerably lower than the set temperature. The waveforms of the respective parts are shown. In FIG.
(A) is the waveform of the energization control pulse output from the PWM circuit 62, (B) is the waveform of the AC voltage V supplied from the commercial AC power supply 84, (C) is the waveform of the energization in the electric heater 44, (D)
Is a waveform of the error signal ΔE obtained from the comparison unit 60, and (E) is a waveform of the actual temperature of the pure water CW detected by the temperature sensor 46.

As described above, in the solid-state laser processing apparatus of this embodiment, the cooling section 42 for cooling the pure water CW in the cooling water supply section 24 for supplying the laser oscillation section 10 with the pure water CW.
And an electric heater 44 for heating the pure water CW.
Performs the continuous operation of the open loop type, while causing the electric heater 44 to perform the continuous operation of the closed loop type (feedback type). In particular, for the electric heater 44, the temperature sensor 46 and the temperature control unit 48 variably control the energizing time per unit cycle and, consequently, the energizing time per unit time by the PWM control method, so that the energizing time per unit time can be quickly and precisely adjusted. The heating value or Joule heat is variably controlled. As a result, the temperature of the pure water CW in the cooling water supply unit 24 is adjusted to the set temperature with high accuracy.

The pure water CW whose temperature has been adjusted to the set temperature with high precision is supplied to the laser oscillation section 10 so that the pump lamp 12 and the Y
The AG rod 14 can operate stably at a predetermined temperature, and the laser beam LB having an intended laser output can be stably obtained from the laser oscillation unit 10. As a result, good processing quality can be obtained in laser processing (for example, welding, marking, cutting, etc.) on the workpiece.

Further, in this embodiment, the energization control section 64 is provided with energization switching means including a triac 86, and a zero cross detection circuit 88 for detecting the timing of the zero cross point of the power supply voltage V is provided. In the control, the power supply start and end times of the electric heater 44 are adjusted to the zero cross point of the power supply voltage V. As a result, it is possible to effectively prevent or reduce the occurrence of switching noise from the energization switching means (triac 86). Therefore, stable operation of the control circuit in the vicinity can be ensured, and also in this respect, high-quality laser processing can be guaranteed.

FIG. 4 shows an energization waveform by a phase control method as a comparative example regarding the above-described energization switching control. In this method, the effective (average) current value is controlled by variably controlling the energization start timing ta for each cycle of the AC power supply voltage. However, in this method, switching is generally performed in the abdomen of the AC voltage waveform (a period in which the absolute value of the voltage is relatively high), so that a surge current is likely to occur, and there is a problem of generation of noise.

[0590] On the other hand, the zero-cross
In the switching method, as shown in FIG. 5, switching is always performed near a node of the AC voltage waveform or near a zero crossing point (at which point the voltage becomes zero), so that the problem of surge current and noise can be solved.

In the temperature control section 48 of the present embodiment, the comparison section 60 is provided with a proportional amplification circuit 66, a differentiation circuit 68 and an integration circuit 76, so that rapid adjustment and precision adjustment can be performed by so-called PID control. That is, pure water C
A rapid change in the water temperature of W can be quickly responded to by the operation of the differentiation circuit 68, and in the steady state, the integration circuit 76
, The temperature of the pure water CW can be made as close as possible to the set temperature.

Next, another feature of the present invention will be described. In the temperature control unit 48 described above, the PWM circuit 62 generates the power supply control pulse CP for controlling the power supply period of the electric heater 44 per unit time.

According to another embodiment of the present invention, the PWM
Instead of the circuit 62, a combination of a voltage-frequency converter 90 and a monostable multivibrator 92 as shown in FIG. 6 is used.

The voltage-frequency converter 90 is a circuit that outputs a pulse train (FS) whose frequency changes in accordance with the voltage level of the input analog signal (δE). As shown in FIG. It has input / output characteristics such that the higher the voltage level of δE), the higher the frequency of the output pulse (FS). Monostable multivibrator 92
Generates an output pulse (CP ′) having a constant pulse width in response to the rise of the input pulse (FS). The output pulse CP ′ from the monostable multivibrator 92 is given to the energization control unit 64 as an energization control pulse.

In this embodiment, for example, comparison section 60
As shown in FIG. 8, when the voltage level of the error signal δE from the input signal increases (that is, when the temperature difference or error between the pure water CW and the set temperature increases), the frequency pulse output from the voltage-frequency converter 90 is increased. The frequency of FS increases, and the number (pulse rate) of energization control pulses CP ′ output from the monostable multivibrator 92 per unit time increases.

If the error in the water temperature is further increased, the energization control pulse CP ′ from the monostable multivibrator 92 is connected. At this time, the energizing switching means (triac 86) is clamped in the on state, and the electric heater 4
At 4, the current is left flowing. That is, when the actual water temperature is too low with respect to the set temperature, the electric current is supplied to the electric heater 44 without any current flow, and the amount of heat generation or heating power of the electric heater 44 per unit time becomes maximum.

By combining such a voltage-frequency converter 90 and a monostable multivibrator 92, a simpler and lower-cost energization control pulse generation circuit can be configured.

In the above embodiment, the cooling section 42 is provided in the middle of the pure water recovery pipes 34, 36. However, as shown in FIG. 9, the heat exchanger 50 of the cooling unit 42 may be arranged in the tank 26. Further, the cooling means in the present invention is not limited to a heat exchange type cooling means for exchanging heat between two cooling media as in the above-described embodiment. For example, an air cooling fan or a Peltier effect element may be used. It is possible.

In the above embodiment, the electric heater 44 is submerged in the tank 26. However, it is also possible to arrange electric heating means outside the tank 26 to heat the pure water CW in the tank through the tank wall. . Alternatively, piping (for example, 30)
It is also possible to arrange an electric heating means around the heater and heat the pure water CW while flowing through the pipe (30). The heating means is not limited to the heating wire, and a resistance heating element such as a PTC element can be used.

As the cooling medium for laser cooling in the present invention, pure water CW is merely an example, and any cooling medium (liquid, gas) can be used. The method and configuration of the laser oscillation unit can be arbitrarily modified and selected.

The present invention is preferably applied to a solid-state laser device, particularly a solid-state laser processing device such as a YAG laser processing device, but can also be applied to other types of laser devices.

[0710]

As described above, according to the laser apparatus of the present invention, in order to control the temperature of the cooling medium supplied to the laser oscillation section, the cooling means and the electric heating means are used in combination, and the electric heating means generates heat. The temperature of the cooling medium is made to match the set temperature by controlling the temperature of the cooling medium by the feedback method, so that the temperature can be precisely and stably adjusted by a simple and low-cost configuration, and the laser output according to the setting can be stabilized. Obtainable.

Also, at the time of energization switching for the electric heating means, the start and end points of energization are set to the zero cross point of the AC voltage, so that it is possible to effectively prevent the generation of noise and to achieve stable operation. Can be guaranteed.

Also, a circuit for obtaining an energization control pulse for defining an energization period per unit time of the electric heating means can be realized with a simpler and lower cost configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of a solid-state laser processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration example of a temperature control unit in the solid-state laser processing apparatus according to the embodiment.

FIG. 3 is a waveform chart showing waveforms of respective units for explaining an operation of a temperature control unit in the embodiment.

FIG. 4 is a waveform chart showing the operation of a phase control method as a comparative example for controlling the energization switching of the electric heater.

FIG. 5 is a waveform diagram showing the operation of the zero-cross switching system according to the present invention for controlling the energization switching of the electric heater.

FIG. 6 is a block diagram illustrating a configuration of an energization control pulse generation circuit according to another embodiment.

7 is a diagram showing input / output characteristics of a voltage-frequency conversion circuit used in the pulse generation circuit of FIG.

FIG. 8 is a waveform chart showing an operation of the pulse generation circuit of FIG. 6;

FIG. 9 is a block diagram illustrating a configuration of a main part of a solid-state laser device according to a modification.

FIG. 10 is a block diagram showing a typical configuration of a laser cooling mechanism in a conventional solid-state laser device.

FIG. 11 is a block diagram showing another configuration of a laser cooling mechanism in a conventional solid-state laser device.

[Explanation of symbols]

 Reference Signs List 10 laser oscillation section 22 laser power supply section 24 cooling water supply section 26 tank 30, 32, 34, 36 pipe 42 cooling section 44 electric heater 46 temperature sensor 48 temperature control section 60 comparison section 62 PWM circuit 64 conduction control section 86 triac 88 zero cross Detection circuit 90 Switching control circuit

Claims (6)

[Claims] A laser oscillator that generates a laser beam; a cooling medium supply unit that circulates a cooling medium to the laser oscillation unit; a cooling unit that cools the cooling medium outside the laser oscillation unit; An electric heating means for heating the cooling medium by generating heat by energizing outside the laser oscillation section; a temperature sensor for detecting a temperature of the cooling medium; and setting a temperature of the cooling medium supplied to the laser oscillation section. A laser device comprising: a temperature control unit that controls an energization period per unit time of the electric heating unit according to an output signal of the temperature sensor so as to match a temperature. 2. A comparison means for comparing an output signal of the temperature sensor with a reference value corresponding to the set temperature to generate an error signal representing the comparison error, and an error from the comparison means. Pulse width control means for outputting an energization control pulse having a pulse width corresponding to the magnitude of a signal at a constant frequency, and controlling on / off of energization in the electric heating means in accordance with the energization control pulse from the pulse width control means 2. An electric power supply control means, comprising:
3. The laser device according to 1. 3. A comparison means for comparing the output signal of the temperature sensor with a reference value corresponding to the set temperature to generate an error signal representing the comparison error, and an error from the comparison means. Voltage-frequency conversion means for outputting a frequency pulse whose frequency changes according to the voltage level of the signal; and an energization control pulse having a constant pulse width in response to the frequency pulse from the voltage-frequency conversion means. 2. A monostable multivibrator, comprising: an energization control unit that controls on / off of energization in the electric heating unit according to an energization control pulse from the monostable multivibrator. Laser device. 4. The power supply control means includes: switch means connected between the electric heating means and an AC power supply; zero cross detection means for detecting a timing at which an AC voltage from the AC power supply crosses a zero level; Immediately after the start of the on-time defined by the energization control pulse, the switch means is switched from the off state to the on state in response to the zero-cross detection signal from the zero-cross detection means,
The laser device according to claim 2, further comprising: a switching control unit configured to switch the switch unit from an on state to an off state when the on-time ends. 5. The laser device according to claim 1, wherein said cooling means performs the cooling operation continuously without interruption. 6. The cooling means includes a heat exchange means for causing heat exchange between the cooling medium and a cooling medium of a different system lower than the cooling medium to lower the temperature of the cooling medium. The laser device according to claim 1.