JPWO2019058522A1 - Laser processing equipment - Google Patents

Abstract

The laser processing apparatus includes a laser oscillator (2) that oscillates a laser beam (3) that is a pulse laser beam, and an infrared sensor (21) that is a photodetector that receives the pulse laser beam and outputs a detection signal. . The laser processing apparatus includes a first integration circuit (23) that integrates a detection signal when the pulse laser beam is on during operation of the laser oscillator (2), and a pulse laser beam during operation of the laser oscillator (2). And a second integrating circuit (24) for integrating the detection signal when is OFF.

Description

  The present invention relates to a laser processing apparatus for processing a workpiece by irradiation with pulsed laser light.

  There is known a laser processing apparatus that forms a hole in a workpiece by irradiation with pulsed laser light. In the laser processing apparatus, the energy of the pulsed laser beam at a spot that is an area irradiated with the pulsed laser beam may deviate from a specified value, thereby causing deterioration in processing quality. When the energy of the pulsed laser beam is smaller than the specified value, the laser processing apparatus makes the depth of the hole to be formed shallower than the desired depth, the diameter of the hole to be formed becomes smaller than the desired diameter, or is covered. It may cause quality deterioration such as processing scraps remaining on the workpiece. The quality of the laser processing apparatus is such that when the energy of the pulse laser beam is larger than the specified value, the depth of the hole to be formed becomes deeper than the desired depth, or the diameter of the hole to be formed becomes larger than the desired diameter. May cause deterioration.

  The laser processing apparatus can measure the energy of the pulsed laser light applied to the workpiece based on the result of taking out a part of the pulsed laser light traveling to the workpiece and measuring the intensity of the extracted laser light. . The laser processing apparatus calculates the energy of the pulsed laser light based on the result of converting the intensity of the extracted laser light into an electric quantity and integrating the obtained electric signal with an integrating circuit. The laser processing apparatus can stably obtain high processing quality by controlling the oscillation of the pulse laser beam based on the measurement result of the energy of the pulse laser beam.

  In a photodetector that converts the intensity of laser light into an electrical quantity, there may be a temperature drift in which the output fluctuates due to fluctuations in the offset voltage. An offset voltage, which is an error that the output voltage rises or falls due to a change in temperature, can occur in the photodetector. The occurrence of temperature drift affects the calculation accuracy of the energy of the pulse laser beam. With regard to such a problem, Patent Document 1 discloses a technique for correcting output fluctuation due to an offset voltage in a period between pulses. According to the technique of Patent Document 1, the laser processing apparatus integrates the electric signal output from the photodetector that has received the pulsed laser light using an integration circuit. The laser processing device integrates the electrical signal output from the photodetector with the integration circuit when it does not receive the pulse laser beam, and based on the obtained integration signal, the offset voltage for calibration of the photodetector. Calculate the value.

JP 2009-279631 A

  In calculating the offset voltage value, the integrating circuit integrates an electric signal having a minute voltage level in the vicinity of 0 V. Therefore, in order to increase the calculation accuracy of the offset voltage value, it is required to secure an integration time as long as possible. On the other hand, in the technique of Patent Document 1, it is necessary to secure an integration time in the pulse interval. Since the pulse interval becomes shorter as the oscillation frequency of the pulsed laser beam is higher, the technique of Patent Document 1 shortens the integration time that can be secured for calculating the offset voltage value, and the offset voltage value is highly accurate. Calculation becomes difficult. If the calculation accuracy of the offset voltage is lowered, the measurement accuracy of the energy of the pulsed laser beam is also lowered, so that it is difficult to adjust the energy of the pulsed laser beam applied to the workpiece with high accuracy. For this reason, according to the technique of Patent Document 1, it may be difficult for the laser processing apparatus to stably obtain high processing quality due to a decrease in the adjustment accuracy of the energy of the pulse laser beam.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the laser processing apparatus which can obtain high processing quality stably.

  In order to solve the above-described problems and achieve the object, a laser processing apparatus according to the present invention includes a laser oscillator that oscillates pulsed laser light, a photodetector that receives the pulsed laser light and outputs a detection signal, and a laser. A first integration circuit that integrates the detection signal when the pulse laser beam is on during operation of the oscillator, and a second integration that integrates the detection signal when the pulse laser beam is off during operation of the laser oscillator A circuit.

  The laser processing apparatus according to the present invention has an effect that high processing quality can be stably obtained.

The figure which shows the structure of the laser processing apparatus concerning embodiment of this invention The figure which shows the structure of the integral signal calculation apparatus shown in FIG. The block diagram which shows the function structure of the control apparatus shown in FIG. The block diagram which shows the hardware constitutions of the control apparatus shown in FIG. FIG. 2 is a first diagram for explaining the first integrated signal shown in FIG. 2nd figure explaining the 1st integral signal shown in FIG. The figure explaining the operation | movement for correction | amendment of the electrical signal by the laser processing apparatus shown in FIG. The figure explaining the electric signal shown in FIG. The figure explaining the case where the integration time designated by the integration command signal shown in FIG. 2 is made variable. The figure explaining the case where the gain of the amplifier circuit shown in FIG. 1 is made variable

  Hereinafter, a laser processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram showing a configuration of a laser processing apparatus 1 according to an embodiment of the present invention. The laser processing apparatus 1 forms a hole in the workpiece 12 by irradiation with laser light 3 that is pulsed laser light.

  In FIG. 1, an X axis and a Y axis are two axes parallel to the horizontal direction and perpendicular to each other. The Z axis is assumed to be an axis parallel to the vertical direction and perpendicular to the X axis and the Y axis. The workpiece 12 is placed on the upper surface of the table 13 which is a plane parallel to the X axis and the Y axis.

  The laser processing apparatus 1 includes a laser oscillator 2 that oscillates a laser beam 3 that is a pulsed laser beam irradiated onto a workpiece 12. The laser beam 3 is infrared light. The oscillation frequency of the pulse laser beam by the laser oscillator 2 is included in the range of 100 Hz to 10000 Hz. A pulse width that is a period of one pulse in which the laser beam 3 is emitted is included in a range of 1 μsec to 100 μsec. During the operation of the laser oscillator 2, the laser oscillator 2 repeats turning on and off of the laser beam 3. The laser beam 3 being on indicates that the laser oscillator 2 is emitting the laser beam 3. The laser beam 3 being off means that the laser oscillator 2 is not emitting the laser beam 3.

  The partial reflection mirror 4 reflects a part of the laser beam 3 from the laser oscillator 2 and transmits the remaining laser beam 3. In the embodiment, the partial reflection mirror 4 transmits 95% of the laser light 3 from the laser oscillator 2 and reflects 5%. The laser beam 3 transmitted through the partial reflection mirror 4 travels toward the workpiece 12. Of the laser light 3 from the laser oscillator 2, the laser light 14 branched by the reflection at the partial reflection mirror 4 travels toward the integrated signal calculation device 15. The mirrors 5 and 6 reflect the laser light 3 transmitted through the partial reflection mirror 4.

  The scan mirror 8 reflects the laser light 3 from the mirror 6. The galvano scanner 7 is a servo motor that rotationally drives the scan mirror 8. The galvano scanner 7 rotates the scan mirror 8 to displace the incident position of the laser beam 3 on the workpiece 12 in the X-axis direction. The scan mirror 10 reflects the laser light 3 from the scan mirror 8. The galvano scanner 9 is a servo motor that rotationally drives the scan mirror 10. The galvano scanner 9 rotates the scan mirror 10 to displace the incident position of the laser beam 3 on the workpiece 12 in the Y-axis direction.

  The condensing optical system 11 converges the laser light 3 from the scan mirror 10. The condensing optical system 11 includes one or a plurality of condensing lenses. The condensing optical system 11 may be an fθ lens. The condensing position of the laser beam 3 by the fθ lens is a position of fθ obtained by multiplying the focal length f of the condensing optical system 11 by the deflection angle θ of the scan mirrors 8 and 10.

  The table 13 is movable in the X axis direction and the Y axis direction. The workpiece 12 moves with the table 13 in the X-axis direction and the Y-axis direction. In the embodiment, a work piece 12 of 300 mm square is placed on the table 13. The galvano scanners 7 and 9 scan the laser beam 3 in a 50 mm square range on the workpiece 12 on the table 13.

  The laser processing apparatus 1 repeats the movement of the table 13 and the irradiation of the laser beam 3 onto the workpiece 12 to form holes at a plurality of positions on the workpiece 12. The laser processing apparatus 1 forms a hole having a diameter on the order of 10 μm or 100 μm. The laser oscillator 2 turns off the laser beam 3 while moving the table 13. The laser oscillator 2 turns on the laser beam 3 after the table 13 stops at a desired position.

  An optical element other than the partial reflection mirror 4, the mirrors 5 and 6, the scan mirrors 8 and 10, and the condensing optical system 11 may be provided in the optical path in which the laser beam 3 travels in the laser processing apparatus 1. In the laser processing apparatus 1, any of the partial reflection mirror 4, the mirrors 5 and 6, the scan mirrors 8 and 10, the galvano scanners 7 and 9, the condensing optical system 11, and the table 13 may be omitted.

  The laser processing apparatus 1 includes an integrated signal calculation device 15 and a control device 16. The integrated signal calculation device 15 measures the intensity of the laser beam 14 branched by the partial reflection mirror 4. The integrated signal calculation device 15 converts the intensity of the laser light 14 into an electric quantity, and outputs an integrated signal that is a result of integrating the obtained electric signal.

  The control device 16 is connected to the integrated signal calculation device 15 and the laser oscillator 2. The control device 16 obtains the energy value of the laser beam 3 irradiated on the workpiece 12 based on the integration signal input from the integration signal calculation device 15. The control device 16 controls the laser oscillator 2 based on the obtained energy value. The laser processing apparatus 1 can reduce deterioration in processing quality due to a deviation between the energy value of the laser beam 3 for each spot and the specified value by adjusting the number of times the laser beam 3 is emitted for each spot on the workpiece 12. And

  The control device 16 may control the galvano scanners 7 and 9 and the table 13. Here, the details of the control of the galvano scanners 7 and 9 and the table 13 are omitted.

  Next, the configuration and operation of the integral signal calculation device 15 will be described. FIG. 2 is a diagram showing a configuration of the integrated signal calculation device 15 shown in FIG. The integrated signal calculation device 15 includes an infrared sensor 21 that is a photodetector that detects the laser light 14 branched by the partial reflection mirror 4. The infrared sensor 21 receives the laser beam 14 and outputs a detection signal. The infrared sensor 21 outputs an electric signal 31 that is a detection signal having a voltage level corresponding to the intensity of the received laser beam 14. The infrared sensor 21 outputs an electrical signal 31 that is a first electrical signal.

  The integrated signal calculation device 15 includes an amplifier circuit 22 that is an operational amplifier. The amplification circuit 22 amplifies the electrical signal 31 output from the infrared sensor 21 and outputs an amplified electrical signal 32. The amplifier circuit 22 may have a configuration for changing the amplification factor. The amplifying circuit 22 corrects the electric signal 31 by subtracting the offset voltage value 35 for calibration of the infrared sensor 21 and the amplifying circuit 22 from the electric signal 31, and the second electric signal which is the corrected electric signal 31. Amplify. The amplifying circuit 22 amplifies the second electric signal that is the electric signal 31 in which the error due to the offset voltage between the infrared sensor 21 and the amplifying circuit 22 is canceled, and the electric signal 32 that is the amplified second electric signal. Is output.

  The integration signal calculation device 15 includes a first integration circuit 23 and a second integration circuit 24 that integrate the electric signal 32 from the amplification circuit 22. The first integration circuit 23 and the second integration circuit 24 are integration circuits including an operational amplifier that is an amplifier circuit and a capacitor. The first integration circuit 23 and the second integration circuit 24 are connected in parallel.

  The first integration circuit 23 integrates an electric signal 32 that is a detection signal output from the infrared sensor 21 and the amplification circuit 22 for each pulse when the laser oscillator 3 is on during the operation of the laser oscillator 2. The first integration circuit 23 integrates the electric signal 32 in a first integration time designated by the integration command signal 37. The first integration circuit 23 outputs a first integration signal 33 that is proportional to the time integration of the input electrical signal 32. A first integration signal 33 that is an integration result by the first integration circuit 23 represents time integration of the intensity of the laser light 14. The first integration circuit 23 integrates the electric signal 32 for each pulse.

  The second integration circuit 24 integrates an electric signal 32 that is a detection signal output from the infrared sensor 21 and the amplification circuit 22 when the laser beam 3 is off during the operation of the laser oscillator 2. The second integration circuit 24 integrates the electric signal 32 in the second integration time specified by the integration command signal 38. The second integration circuit 24 outputs a second integration signal 34 proportional to the time integration of the input electrical signal 32. A second integration signal 34 that is an integration result of the second integration circuit 24 represents time integration of the offset voltage in the infrared sensor 21 and the amplifier circuit 22. The second integration circuit 24 integrates the electric signal 32 at every pulse interval.

  The integration signal calculation device 15 outputs a first integration signal 33 that is the output of the first integration circuit 23 and a second integration signal 34 that is the output of the second integration circuit 24 to the control device 16. The control device 16 controls the laser light 3 to be oscillated next by using the first integrated signal 33 corrected by the second integrated signal 34. The offset voltage value 35, the integration command signals 37 and 38, and the gain signal 39 from the control device 16 are input to the integration signal calculation device 15.

  FIG. 3 is a block diagram showing a functional configuration of the control device 16 shown in FIG. The control unit 40 is a functional unit that controls each functional unit of the control device 16. The control unit 40 supervises signal exchange between the functional units. The first integration signal input unit 41 is a functional unit that receives the first integration signal 33 from the integration signal calculation device 15. The first integration signal input unit 41 sends the input first integration signal 33 to the control unit 40. The control unit 40 sends the first integration signal 33 to the energy calculation unit 48.

  The second integration signal input unit 42 is a functional unit that receives the second integration signal 34 from the integration signal calculation device 15. The second integration signal input unit 42 sends the input second integration signal 34 to the control unit 40. The control unit 40 sends the second integration signal 34 to the offset voltage calculation unit 43.

  The offset voltage calculation unit 43 is a functional unit that calculates the offset voltage value 35. The offset voltage calculation unit 43 calculates an offset voltage value 35 by multiplying the second integration signal 34 by a coefficient parameter. The offset voltage calculation unit 43 sends the offset voltage value 35 to the control unit 40. The control unit 40 sends the offset voltage value 35 to the offset voltage output unit 44. The offset voltage output unit 44 is a functional unit that outputs an offset voltage value 35 to the amplifier circuit 22 shown in FIG.

  The first integration command output unit 45 is a functional unit that outputs an integration command signal 37 to the first integration circuit 23 shown in FIG. The first integration time is specified by the integration command signal 37. The second integration command output unit 46 is a functional unit that outputs an integration command signal 38 to the second integration circuit 24 shown in FIG. The second integration time is specified by the integration command signal 38.

  The energy calculation unit 48 calculates the energy value of the laser beam 3 that irradiates the spot of the workpiece 12 based on the first integrated signal 33 obtained by integrating the electrical signal 32 with the offset voltage canceled. Part. The energy calculation unit 48 calculates the energy value of the laser beam 3 for each spot by multiplying the first integrated signal 33 by a coefficient parameter. The energy value calculated by the energy calculation unit 48 is appropriately referred to as “actual value”. The energy calculation unit 48 calculates the difference between the prescribed value of the energy of the laser beam 3 and the actual measurement value for each spot. The energy calculation unit 48 sends the difference between the specified value and the actual measurement value to the control unit 40. The control unit 40 sends the difference between the specified value and the actual measurement value to the laser oscillation control unit 47.

  The laser oscillation control unit 47 is a functional unit that controls the oscillation of the laser light 3 by the laser oscillator 2 based on the difference between the prescribed value of energy and the actual measurement value. The laser oscillation control unit 47 generates a control signal 36 for adding irradiation of the laser light 3 when the actual measured value of energy is smaller than the specified value. The laser oscillation control unit 47 determines the number of times of irradiation with the laser light 3 according to the difference between the specified value and the actually measured value. Further, the laser oscillation control unit 47 generates a control signal 36 for turning off the laser beam 3 when it is determined that the actual measured value of energy is larger than the specified value. The laser oscillation control unit 47 outputs a control signal 36 to the laser oscillator 2 shown in FIG.

  The gain signal output unit 49 is a functional unit that generates the gain signal 39 and outputs the gain signal 39 to the amplifier circuit 22 shown in FIG. A gain representing the amplification factor of the amplifier circuit 22 is designated by the gain signal 39.

  The offset voltage storage unit 50 includes a number of data areas corresponding to the number of gains that can be specified by the gain signal 39. The offset voltage storage unit 50 is a functional unit that holds an offset voltage value 35 corresponding to the gain. When the gain is changed and the offset voltage value 35 corresponding to the changed gain is held in the offset voltage storage unit 50, the control unit 40 sets the offset voltage value 35 corresponding to the changed gain. Is read from the offset voltage storage unit 50. The control unit 40 sends the read offset voltage value 35 to the offset voltage output unit 44. The offset voltage output unit 44 outputs an offset voltage value 35 to the amplifier circuit 22 shown in FIG.

  The function by the control device 16 is realized using a hardware configuration. FIG. 4 is a block diagram showing a hardware configuration of the control device 16 shown in FIG. In the embodiment, the hardware configuration of the control device 16 is a microcontroller. The function of the control device 16 is executed on a program analyzed and executed by the microcontroller. Note that some of the functions of the control device 16 may be executed on hardware by wired logic.

  The control device 16 includes a processor 51 that executes various processes, and a memory 52 that stores programs for the various processes. The processor 51 and the memory 52 are connected to each other via a bus 53. The processor 51 expands the loaded program and executes various processes for controlling the laser processing apparatus 1 by the control device 16. The control unit 40, the first integration signal input unit 41, the second integration signal input unit 42, the offset voltage calculation unit 43, the offset voltage output unit 44, the first integration command output unit 45, the second integration signal shown in FIG. The integration command output unit 46, the laser oscillation control unit 47, the energy calculation unit 48, and the gain signal output unit 49 are realized using the processor 51. The offset voltage storage unit 50 is realized using the memory 52.

  Next, the electrical signal 32 output from the amplification circuit 22 and the first integration signal 33 output from the first integration circuit 23 will be described. FIG. 5 is a first diagram for explaining the first integrated signal 33 shown in FIG. The infrared sensor 21 and the amplifier circuit 22 may generate an offset voltage, which is an error in which the output voltage increases or decreases due to a change in temperature. The amplifier circuit 22 may also generate an offset voltage, which is an error that causes the output voltage to rise or fall due to a change in gain. FIG. 5 shows the electric signal 32 when the output drift fluctuates due to the fluctuation of the offset voltage of the infrared sensor 21 and the first integrated signal obtained by integrating the electric signal 32. 33.

  When the offset voltage of the infrared sensor 21 is not generated, when the laser beam 3 is off, the voltage level of the electrical signal 32 is 0 V, which is a reference value. When the offset voltage is not generated in the amplifier circuit 22, the amplifier circuit 22 outputs an electrical signal 32 that does not include fluctuation due to the offset voltage.

  The first integration command output unit 45 shown in FIG. 3 raises the integration command signal 37 before the rise of the pulse of the electrical signal 32. The first integration command output unit 45 causes the integration command signal 37 to fall after the fall of the electrical signal 32. The first integration circuit 23 integrates the electric signal 32 in the time from the rise to the fall of the integration command signal 37.

  The time integration of the electric signal 32 in the first integration circuit 23 corresponds to obtaining the area of the pulse waveform of the electric signal 32. By inputting the electric signal 32 that does not include fluctuation due to the offset voltage, the first integration circuit 23 can obtain an accurate first integration signal 33. The energy calculation unit 48 can calculate an accurate energy value of the pulse laser beam.

  FIG. 6 is a second diagram illustrating the first integrated signal 33 shown in FIG. FIG. 6 shows an electrical signal 32, an integration command signal 37, and a first integration signal 33 when a temperature drift occurs in the infrared sensor 21.

  When the level of the offset voltage of the infrared sensor 21 is a plus level, that is, a level higher than 0 V, the voltage level of the electrical signal 32 when the laser beam 3 is off is shifted to the plus side. When the offset voltage value 35 input to the amplifier circuit 22 is zero, the amplifier circuit 22 outputs an electrical signal 32 whose voltage level is shifted to the positive side. The first integration circuit 23 obtains a first integration signal 33 whose voltage level is shifted to the plus side.

  When the level of the offset voltage of the infrared sensor 21 is a minus level, that is, a level lower than 0 V, the voltage level of the electrical signal 32 when the laser beam 3 is off is shifted to the minus side. When the offset voltage value 35 input to the amplifier circuit 22 is zero, the amplifier circuit 22 outputs an electrical signal 32 whose voltage level is shifted to the minus side. The first integration circuit 23 obtains a first integration signal 33 whose voltage level is shifted to the minus side.

  When the voltage level of the first integration signal 33 is shifted to the plus side or the minus side, it is difficult for the energy calculation unit 48 to calculate the accurate energy value of the laser beam 3. In the embodiment, the amplifier circuit 22 obtains the electric signal 32 in which the fluctuation due to the offset voltage is corrected by subtracting the offset voltage value 35 calculated based on the second integrated signal 34 from the electric signal 31. The first integration circuit 23 can obtain an accurate first integration signal 33 by inputting the electric signal 32 in which the fluctuation due to the offset voltage is corrected. Thereby, the energy calculation unit 48 can calculate an accurate energy value of the laser beam 3.

  Next, the timing of the operation for correcting the electric signal 32 by the laser processing apparatus 1 will be described. FIG. 7 is a diagram for explaining an operation for correcting the electric signal 32 by the laser processing apparatus 1 shown in FIG. FIG. 8 is a diagram for explaining the electrical signal 32 shown in FIG.

  The offset voltage calculation unit 43 calculates an offset voltage value 35 in a period in which the pulse laser beam is off between a period in which the pulse laser beam is on and a period in which the next pulse laser beam is on. The laser processing apparatus 1 performs an operation for correction during a period in which the pulse laser beam is off. After performing the operation for correction, the laser processing apparatus 1 performs the operation for correction between a period when the next pulse laser beam is on and a period when the next pulse laser beam is on. Do. The laser processing apparatus 1 alternately repeats the emission of one pulse laser beam and the operation for correction.

  The laser processing apparatus 1 processes a workpiece 12 by emitting a plurality of pulsed laser beams. The laser beam 14 branched from the pulsed laser beam traveling to the workpiece 12 is continuously input to the infrared sensor 21. When correction is not performed in a period in which the pulse laser beam is off, as indicated by a two-dot chain line in FIG. 8, the deviation between the voltage level of the electrical signal 32 and the reference value increases with time. . The laser processing apparatus 1 performs correction between the period in which the pulse laser beam is on and the period in which the next pulse laser beam is on, so that the voltage of the electric signal 32 is indicated by a solid line in FIG. Deviation between the level and the reference value can be reduced.

  The first integration command output unit 45 switches the integration command signal 37 from OFF to ON before emission of pulsed laser light is started. While the pulse laser beam is emitted, the amplifier circuit 22 outputs an electric signal 32 having a voltage level corresponding to the intensity of the pulse laser beam. After the emission of the pulse laser beam is stopped, the first integration signal 33 is input to the first integration signal input unit 41. The first integration circuit 23 integrates the electric signal 32 at the integration time T11. The integration time T11 is a time from when the integration command signal 37 rises until the input of the first integration signal 33 to the first integration signal input unit 41 is started.

  The first integration signal input unit 41 reads the first integration signal 33 that is an analog signal at the measurement time T12 after the emission of the pulsed laser beam is stopped. Here, reading of the first integration signal 33 at the first integration signal input unit 41 is referred to as measurement of the first integration signal 33. The first integration signal input unit 41 performs analog to digital (AD) conversion for measuring the first integration signal 33.

  At the timing when the measurement of the first integration signal 33 at the first integration signal input unit 41 ends, the first integration command output unit 45 switches the integration command signal 37 from on to off. The first integration circuit 23 releases the electric charge accumulated in the capacitor at the discharge time T13 after the integration command signal 37 is switched from on to off.

  The second integration command output unit 46 switches the integration command signal 38 from OFF to ON at the timing when the measurement of the first integration signal 33 by the first integration signal input unit 41 is started. While the emission of the pulse laser beam is stopped, the amplification circuit 22 outputs an electrical signal 32 corresponding to the level of the offset voltage between the infrared sensor 21 and the amplification circuit 22. Before the emission of the next pulse laser beam is started, the second integration signal 34 is input to the second integration signal input unit 42. The second integration circuit 24 integrates the electric signal 32 at the integration time T21. The integration time T21 is the time from when the integration command signal 38 rises until the input of the second integration signal 34 to the second integration signal input unit 42 is started.

  The second integration signal input unit 42 reads the second integration signal 34 that is an analog signal at the measurement time T22. Here, reading of the second integrated signal 34 at the second integrated signal input unit 42 is referred to as measurement of the second integrated signal 34. The second integration signal input unit 42 performs AD conversion for measuring the second integration signal 34.

  At the timing when the measurement of the second integration signal 34 at the second integration signal input unit 42 ends, the second integration command output unit 46 switches the integration command signal 38 from on to off. The second integration circuit 24 releases the charge accumulated in the capacitor at the discharge time T23 after the integration command signal 38 is switched from on to off.

  If one integration circuit is used for the integration for calculating the energy value of the pulse laser beam and the integration for calculating the offset voltage value 35, the integration is performed after the integration for calculating the energy value of the pulse laser beam. After measurement and discharge, integration for calculating the offset voltage value 35 is started.

  On the other hand, the laser processing apparatus 1 according to the embodiment outputs the electric signal 32 by the second integration circuit 24 in parallel with the measurement of the first integration signal 33 and the discharge of the first integration circuit 23. Enable integration. The laser processing apparatus 1 can start the integration time T21 for calculating the offset voltage value 35 without waiting for the measurement time T12 and the discharge time T13 for the first integration signal 33. Since the laser processing apparatus 1 is provided with the first integration circuit 23 and the second integration circuit 24, it is possible to ensure a longer integration time T21 than when one integration circuit is used. The laser processing apparatus 1 can ensure a long integration time T21 even when the pulse laser beam emission interval is short.

  Integration is performed when the oscillation frequency of the laser oscillator 2 is 10 kHz, the pulse interval is 100 μsec, the integration time T11 is 55 μsec, the measurement times T12 and T22 are 5 μsec, and the discharge times T13 and T23 are 10 μsec. The time T21 can be 45 microseconds. The laser processing apparatus 1 can accurately calculate the offset voltage value 35 by ensuring a long integration time T21.

  The laser processing apparatus 1 may correct the electric signal 32 every time one pulse laser beam is emitted, or correct the electric signal 32 every time a plurality of pulse laser beams are emitted. good.

  Next, a case where the integration time T11 in the first integration circuit 23 is variable will be described. The first integration command output unit 45 may change the integration time T11 specified by the integration command signal 37. The laser processing apparatus 1 may change the integration time T11 according to the oscillation frequency or pulse width of the laser oscillator 2.

  FIG. 9 is a diagram illustrating a case where the integration time T11 specified by the integration command signal 37 shown in FIG. 2 is variable. The first integration command output unit 45 calculates an integration time based on the oscillation frequency or pulse width of the laser oscillator 2. The first integration command output unit 45 switches the integration command signal 37 from OFF to ON before emission of pulsed laser light is started. The first integration command output unit 45 switches the integration command signal 37 from ON to OFF when the integration time T11 has elapsed since the integration command signal 37 was switched from OFF to ON.

  Suppose that the pulse width of the electric signal 32 is 60 μs when the integration time T11 is unchanged at 60 μs. In this case, the integration time T11 is started before the rise of the pulse of the electric signal 32, so that the integration time T11 ends before the pulse of the electric signal 32 falls. For this reason, a part of the pulse of the electric signal 32 is not integrated. The laser processing apparatus 1 according to the embodiment appropriately sets the integration time T11 longer than 60 μsec for the pulse of the electric signal 32. The laser processing apparatus 1 can set the integration time T11 to 110 μsec. Thereby, the laser processing apparatus 1 can avoid the situation where a part of pulse of the electric signal 32 is not integrated.

  Suppose that when the integration time T11 is invariable at 120 μs, two pulses of the electric signal 32 having a pulse width of 20 μs are continuous. In this case, the two pulses of the electric signal 32 are integrated without being separated. The laser processing apparatus 1 according to the embodiment appropriately sets an integration time T11 shorter than 120 μsec for the pulse of the electric signal 32. The laser processing apparatus 1 can set the integration time T11 to 70 μsec. Thereby, the laser processing apparatus 1 can avoid the situation where the two pulses of the electric signal 32 are integrated without being separated.

  The laser processing apparatus 1 has a variable integration time T11 so that a part of the signal in the pulse period is not integrated, or the signal in the plurality of pulse periods is integrated into one integrated signal. Can be avoided. The laser processing apparatus 1 can calculate the amount of energy for each pulse laser beam even when the oscillation frequency or the pulse width changes.

  Next, a case where the gain of the amplifier circuit 22 is variable will be described. The gain signal output unit 49 may change the gain specified by the gain signal 39. The laser processing apparatus 1 may change the gain of the amplifier circuit 22 according to the intensity of the pulsed laser light output from the laser oscillator 2.

  FIG. 10 is a diagram illustrating a case where the gain of the amplifier circuit 22 shown in FIG. 1 is variable. The gain signal output unit 49 sets the gain according to the energy value of the pulse laser beam. The gain signal output unit 49 generates a gain signal 39 including the designation of the gain.

  The amplification circuit 22 corrects the electrical signal 31 by subtracting the offset voltage value 35 from the electrical signal 31, and amplifies the corrected electrical signal 31. The amplifier circuit 22 amplifies the electrical signal 31 from which the offset voltage has been canceled, and outputs the amplified electrical signal 32.

  The level L shown in FIG. 10 represents the upper limit of the voltage level of the first integration signal 33 that can be measured by the first integration signal input unit 41. If the gain is fixed, the voltage level of the first integration signal 33 may exceed the level L because the energy value of the laser light 14 incident on the infrared sensor 21 is high. The laser processing apparatus 1 obtains the first integration signal 33 having a voltage level lower than the level L by lowering the gain of the amplification circuit 22 when the energy value of the pulse laser beam is high. The laser processing apparatus 1 can measure the first integrated signal 33 by the first integrated signal input unit 41. In the example shown in FIG. 10, the gain is set to 10 times when the energy value of the pulsed laser beam is high enough that the voltage level of the first integration signal 33 exceeds the level L. As described above, the laser processing apparatus 1 stores the voltage level of the first integration signal 33 in the input possible range of the control device 16 that is the range from 0 V as the reference value to the level L.

  Further, when the gain is fixed, the signal-to-noise ratio (SNR) of the first integrated signal 33 is lowered because the energy value of the laser light 14 incident on the infrared sensor 21 is low. It can happen. Since the SNR of the first integration signal 33 is reduced, it is difficult to accurately measure the first integration signal 33 by the first integration signal input unit 41. The laser processing apparatus 1 can accurately measure the first integration signal 33 by the first integration signal input unit 41 by increasing the gain of the amplification circuit 22 when the energy value of the pulse laser beam is low. In the example shown in FIG. 10, the gain is set to 20 times when the energy value of the pulse laser beam is low enough to reduce the SNR of the first integrated signal 33. In this way, the laser processing apparatus 1 maintains the voltage level of the first integration signal 33 to such an extent that the decrease in SNR can be suppressed.

  Next, a description will be given of the switching of the gain every time the pulse laser beam is emitted. The gain signal output unit 49 sends the gain signal 39 to the amplifier circuit 22 before the emission of the pulse laser beam is started. The amplifier circuit 22 switches the gain according to the gain signal 39.

  The offset voltage calculation unit 43 changes the coefficient parameter according to the gain in order to avoid fluctuations in the calculation result of the offset voltage value 35 due to the gain change. The energy calculation unit 48 changes the coefficient parameter in accordance with the gain in order to avoid fluctuations in the calculation result of the actual measured value of energy due to the change in gain.

  The offset voltage of the amplifier circuit 22 changes according to the gain. When the gain is changed, the laser processing apparatus 1 corrects the fluctuation in the output of the amplifier circuit 22 due to the offset voltage. When the gain of the amplifier circuit 22 is changed, the second integration command output unit 46 outputs the integration command signal 38 to the second integration circuit 24. The second integration circuit 24 integrates the electric signal 32 when the emission of the pulsed laser beam is stopped, and sends a second integration signal 34 to the second integration signal input unit 42.

  The offset voltage calculation unit 43 calculates the offset voltage value 35 by multiplying the measurement result of the second integration signal 34 by the second integration signal input unit 42 by the coefficient parameter changed according to the gain. Thereby, the offset voltage output unit 44 updates the offset voltage value 35 output to the amplifier circuit 22 when the gain is changed.

  When the processing of the workpiece 12 by the laser processing apparatus 1 is started, the laser oscillation control unit 47 sends a control signal 36 to the laser oscillator 2. The first integration circuit 23 integrates the electrical signal 32 when the pulse laser beam is emitted, and sends a first integration signal 33 to the first integration signal input unit 41. The energy calculation unit 48 calculates the actual measurement value of the energy of the pulsed laser light by multiplying the measurement result of the first integration signal 33 by the first integration signal input unit 41 by the coefficient parameter changed according to the gain. To do.

  Thus, when the gain of the amplifier circuit 22 is changed, the laser processing apparatus 1 updates the offset voltage value 35 and corrects the output of the amplifier circuit 22. Moreover, the laser processing apparatus 1 changes a coefficient parameter according to a gain. Thereby, the laser processing apparatus 1 can calculate an accurate energy value of the pulse laser beam even when the gain is switched.

  Next, gain setting will be described. Even when the control signal 36 instructing oscillation under the same conditions is input to the laser oscillator 2, the intensity of the pulsed laser light output from the laser oscillator 2 may vary from processing to processing. Hereinafter, the condition indicated by the control signal 36 is referred to as a machining condition.

  Before processing, the laser processing apparatus 1 sequentially emits pulsed laser light for each processing condition, and the energy calculation unit 48 calculates the energy value of the pulsed laser light, so that the pulsed laser light in each processing condition is calculated. Measure energy. The laser processing apparatus 1 measures energy while changing the gain designated by the gain signal output unit 49. The gain signal output unit 49 has a gain capable of keeping the voltage level of the first integration signal 33 within the above-described input-capable range and maintaining the voltage level of the first integration signal 33 to an extent that can suppress a decrease in SNR. Select for each processing condition. Thereby, the laser processing apparatus 1 adjusts a gain for every processing condition, and sets the gain suitable for a process.

  Next, holding of the offset voltage value 35 by the offset voltage storage unit 50 will be described. Since the offset voltage of the amplifier circuit 22 changes according to the gain, the laser processing apparatus 1 updates the offset voltage value 35 when the gain is changed during processing.

  When the offset voltage value 35 corresponding to the changed gain is held in the offset voltage storage unit 50, the offset voltage output unit 44 reads the offset voltage value 35 corresponding to the changed gain from the offset voltage storage unit 50. The read offset voltage value 35 is output.

  On the other hand, when the offset voltage value 35 corresponding to the changed gain is not held in the offset voltage storage unit 50, the offset voltage calculation unit 43 calculates the offset voltage value 35 and offsets the calculated offset voltage value 35. The voltage is output to the voltage output unit 44. Further, the offset voltage calculation unit 43 sends the calculated offset voltage value 35 to the offset voltage storage unit 50. The offset voltage storage unit 50 stores the offset voltage value 35 in the data area.

  The laser processing apparatus 1 can save the calculation of the offset voltage value 35 at the time of gain switching by holding the offset voltage value 35 corresponding to each gain that can be set in the amplification circuit 22 in the offset voltage storage unit 50. . The laser processing apparatus 1 can reduce the process required for updating the offset voltage value 35 by switching the gain, and can shorten the time required for the update.

  The laser processing apparatus 1 calculates the offset voltage value 35 for all gains that can be obtained by the amplifier circuit 22 at times other than during processing, and stores the offset voltage value 35 in each data area of the offset voltage storage unit 50. May be. The laser processing apparatus 1 may calculate and store the offset voltage value 35 when the time during which processing is not performed continues for a certain time or more. The laser processing apparatus 1 can omit the calculation of the offset voltage value 35 during processing by holding the offset voltage values 35 for all gains before the next processing is started.

  The offset voltage calculation unit 43 replaces the calculation of the offset voltage value 35 for all gains that can be set in the amplifier circuit 22 with respect to the maximum gain and the minimum gain among the gains that can be set in the amplifier circuit 22. 35 may be calculated. In this case, the offset voltage calculation unit 43 obtains the offset voltage value 35 for gains other than the maximum gain and the minimum gain by linear interpolation between the offset voltage value 35 for the maximum gain and the offset voltage value 35 for the minimum gain. May be. Also in this case, the laser processing apparatus 1 can hold the offset voltage value 35 for all gains.

  Note that some or all of the components of the integrated signal calculation device 15 shown in FIG. 2 may be provided in the control device 16. The energy calculation unit 48 may calculate the energy value using the electric signal 32 when the pulsed laser beam is on instead of the first integration signal 33. The offset voltage calculation unit 43 may calculate the offset voltage value 35 using the electric signal 32 when the pulse laser beam is off, instead of the second integration signal 34.

  According to the embodiment, the laser processing apparatus 1 performs integration for calculating the offset voltage value 35 using the second integration circuit 24 provided separately from the first integration circuit 23. The laser processing apparatus 1 enables the integration of the electric signal 32 by the second integration circuit 24 in parallel with the measurement of the first integration signal 33 and the discharge of the first integration circuit 23, thereby providing an offset voltage value. The integration time T21 for calculating 35 can be increased. The laser processing apparatus 1 can accurately calculate the offset voltage value 35 by ensuring the long integration time T21, and can measure the energy of the pulsed laser light with high accuracy. The laser processing apparatus 1 can adjust the energy of pulsed laser light with high accuracy, and can stably obtain high processing quality. Thereby, the laser processing apparatus 1 has an effect that high processing quality can be obtained stably.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Laser processing apparatus, 2 Laser oscillator, 3,14 Laser beam, 4 Partial reflection mirror, 5,6 Mirror, 7,9 Galvano scanner, 8,10 Scan mirror, 11 Condensing optical system, 12 Workpiece, 13 Table , 15 Integral signal calculation device, 16 control device, 21 infrared sensor, 22 amplification circuit, 23 first integration circuit, 24 second integration circuit, 31, 32 electrical signal, 33 first integration signal, 34 second Integration signal, 35 Offset voltage value, 36 Control signal, 37, 38 Integration command signal, 39 Gain signal, 40 Control unit, 41 First integration signal input unit, 42 Second integration signal input unit, 43 Offset voltage calculation unit 44 Offset voltage output unit 45 First integration command output unit 46 Second integration command output unit 47 Laser oscillation control unit 48 Energy Calculation unit, 49 gain signal output unit, 50 offset voltage storage unit, 51 processor, 52 memory, 53 bus.

Claims (13)

A laser oscillator that oscillates pulsed laser light;
A photodetector that receives the pulsed laser light and outputs a detection signal;
A first integration circuit that integrates the detection signal when the pulsed laser beam is on during operation of the laser oscillator;
A second integrating circuit for integrating the detection signal when the pulsed laser beam is off during operation of the laser oscillator;
A laser processing apparatus comprising:   2. The control device according to claim 1, further comprising a control device that controls the pulsed laser light to be oscillated next by using the output of the first integration circuit corrected by the output of the second integration circuit. Laser processing equipment. The first integration circuit integrates the detection signal for each pulse,
The laser processing apparatus according to claim 2, wherein the second integration circuit integrates the detection signal for each pulse interval. The first integration circuit outputs a first integration signal that is a result of integrating the detection signal from which an offset voltage value for calibration of the photodetector has been subtracted,
4. The laser processing according to claim 2, wherein the control device includes an offset voltage calculation unit that calculates the offset voltage value from a second integration signal that is an integration result of the second integration circuit. 5. apparatus. The photodetector outputs a first electric signal that is the detection signal having a voltage level corresponding to the detected intensity of the pulsed laser beam,
The first integration circuit integrates a second electrical signal, which is the first electrical signal from which the offset voltage value has been subtracted, and outputs the first integration signal,
The controller is
An energy calculator that calculates an energy value of the pulsed laser light based on the first integrated signal;
A laser oscillation control unit for controlling the laser oscillator based on the energy value;
The laser processing apparatus according to claim 4, comprising: The offset voltage calculation unit calculates the offset voltage value in a period between a period in which the pulse laser beam is on and a period in which the next pulse laser beam is on,
In parallel with the measurement of the first integration signal for calculating the energy value and the discharge of the first integration circuit, the second integration circuit integrates the second electric signal. The laser processing apparatus according to claim 5.   The laser processing apparatus according to claim 5, wherein an integration time of the second electric signal in the first integration circuit is variable. An amplifying circuit for amplifying the second electric signal;
The said 1st integration circuit and the said 2nd integration circuit integrate the said 2nd electrical signal amplified by the said amplifier circuit, The one of Claim 5 to 7 characterized by the above-mentioned. Laser processing equipment.   The laser processing apparatus according to claim 8, wherein a gain of the amplification circuit is variable.   The laser processing apparatus according to claim 9, wherein the offset voltage calculation unit updates the offset voltage value when the gain is changed.   The laser processing apparatus according to claim 10, wherein the control device includes an offset voltage storage unit that holds the offset voltage value corresponding to each gain that can be set in the amplifier circuit.   The offset voltage calculation unit calculates the offset voltage value for the maximum gain and the minimum gain among the gains that can be set in the amplifier circuit, and the offset voltage value for the maximum gain and the offset for the minimum gain. The laser processing apparatus according to claim 11, wherein the offset voltage value for a gain other than the maximum gain and the minimum gain is obtained by interpolation with a voltage value.   The laser processing apparatus according to claim 9, wherein the gain is selected based on a measurement result of energy of the pulsed laser light before processing.

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