JP4533733B2 - Laser marking device - Google Patents

Description

  The present invention relates to a laser device, and more particularly, a laser device that controls output of laser light using a Q switch and controls output power of laser light by a driving current of an excitation light source, such as a laser marking device. Regarding improvement.

  FIG. 16 is a diagram showing a schematic configuration example of a conventional laser oscillator. The laser oscillator 11 includes an optical lens 2, a rear mirror 3, a laser crystal 4 as a solid laser medium, a Q switch 5, and an output mirror 6, and excitation light is supplied from a laser diode 23 as an excitation light source.

  The excitation light generated by the laser diode 23 is focused on the laser crystal 4 by the optical lens 2. In the laser crystal 4 optically pumped by the excitation light, stimulated emission of laser light is performed. That is, an inversion distribution of energy levels is formed in the laser crystal 4 excited by the irradiation of the excitation light, and if the emitted light of the laser crystal 4 is incident again on the laser crystal 4 in this state, the laser crystal 4 , Light having the same wavelength and the same phase is newly emitted. In this way, the emitted light of the laser crystal 4 is amplified and laser light is generated. As such a laser crystal 4, for example, YAG doped with neodymium (Nd) ions (garnet crystal made of yttrium and aluminum) or YVO4 (yttrium vanadate) is used.

  The rear mirror 3 is a total reflection type mirror that totally reflects laser light, and the output mirror 6 is a semi-transmission type mirror that reflects most of the laser light and transmits part of it. The rear mirror 3 and the output mirror 6 are arranged opposite to each other to form a resonator optical axis 7 for reciprocating the laser light, and the laser crystal 4 and the Q switch 5 are disposed on the resonator optical axis 7. The excitation light from the optical lens 2 passes through the rear mirror 3 and is focused on the laser crystal 4.

  The Q switch 5 controls laser oscillation by diffracting laser light. The Q switch 5 in the on state deflects the laser light on the resonator optical axis 7 to the outside of the resonator optical axis 7 and transmits the laser light on the resonator optical axis 7 as it is in the off state. For this reason, if the Q switch 5 is turned on, the laser beam on the resonator optical axis 7 is blocked, and laser oscillation can be temporarily stopped. An acousto-optic element (AOM: Acoust Optical Modulator) is used for such a Q switch 5. The acoustooptic device is composed of a vibrator that generates an ultrasonic wave based on an RF signal and a crystal such as a crystal on which a diffraction grating is formed by the ultrasonic wave. That is, the crystal is elastically vibrated by ultrasonic waves to form a diffraction grating in the crystal and diffract the laser light.

FIG. 17 is a timing chart showing an operation example of a conventional laser oscillator. In the figure, (a) shows the drive current Id, (b) shows the Q switch control signal S _Q , and (c) shows the change on the time axis for the output power Po. The drive current Id is the current supplied to the laser diode 23, the Q switch control signal _SQ is the RF signal power supplied to the Q switch 5, and the output power Po is the energy of the laser output light.

  The output power Po is controlled by the drive current Id, and this drive current Id is determined based on user operation or user data. For example, 100% in the figure indicates that the output power of the laser beam is the maximum value.

A control signal _SQ having a binary power level is input to the Q switch 5 and is turned on when the level is high (15 W), and turned off when the level is low (0 W). Accordingly, the period during which the control signal _SQ is at a high level is an output stop period during which the laser beam is not output, and a steep pulse laser beam is output when the control signal _SQ is at a low level. That is, this laser oscillator is ON / OFF controlled by the Q switch 5 so that laser light is output only during the output period.

  As described above, in the conventional laser oscillator, the stop of the laser beam is controlled by turning on / off the Q switch 5. However, actually, even when the Q switch 5 is in the OFF state, the laser light may be slightly leaked, and there is a problem that the laser output cannot be completely stopped.

  Specifically, as shown in FIG. 17, even if the Q switch 5 is held in the on state, a very weak laser beam may be output immediately after the drive current Id is changed. there were. Such a phenomenon is not observed when the drive current Id is decreased, but is observed only when the drive current Id is increased. The power of such leaked laser light is so weak that it does not cause a problem during general use as a laser marking device, but if the workpiece to be irradiated with laser light has extremely high sensitivity, It may be affected.

  FIG. 18 is an explanatory diagram of a thermal lens formed in the laser crystal 4. The laser crystal 4 generates heat when the wavelength of excitation light is converted into laser light, and a temperature gradient is generated inside the laser crystal 4. In general, since the refractive index of a substance changes with temperature, a kind of optical lens 4R called a thermal lens is formed in the laser crystal 4 by this temperature gradient. That is, the resonator optical axis 7 is formed by the rear mirror 3, the output mirror 6, and the thermal lens 4R.

  The laser light leakage phenomenon described above is presumed to be caused by the change in the thermal lens 4R. When the light quantity of the laser diode 23 is changed during the output stop period in which the Q switch 5 is on, the temperature distribution in the laser crystal 4 changes. It takes about 2 to 3 seconds for the temperature distribution to stabilize. During this stabilization period, the laser light on the resonator optical axis has a different profile (path and beam diameter) from that after stabilization. On the other hand, the leakage period of the laser light is about several hundreds of millimeters to 1 second, and coincides with the stabilization period at the order level. Therefore, it is considered that during the stabilization period, part of the laser light is not sufficiently diffracted by the Q switch 5 and the laser light leaks. In particular, when the drive current Id of the laser diode 23 is increased, it is considered that the change of the thermal lens 4R is delayed compared to the change of the energy state in the laser crystal 4, and the laser light is likely to leak.

It is considered that such leakage of laser light can be suppressed by widening the active aperture of the Q switch 5. The diffraction angle of the laser beam in the crystal of the Q switch 5 is not constant, and a region in the crystal where the laser beam can be sufficiently diffracted is called an active aperture. The active aperture can be widened by increasing the control signal S _Q Q-switch 5. Therefore, if increasing the signal power of the control signal S _Q, it is possible to suppress the leakage of the laser beam. However, even when the active aperture is expanded, there is a limit depending on device characteristics. Further, the Q switch 5 has a significant heat generation, and there is a problem that if the control signal _SQ is increased, the amount of heat generation is further increased. Especially, when adopting the air-cooled as a cooling method, it has been difficult to increase the control signal S _Q.

  The present invention has been made in view of the above circumstances, and an object thereof is to suppress leakage of laser light from a laser device during an output stop period in which laser output is interrupted by a Q switch. In particular, it is an object of the present invention to provide a laser apparatus capable of completely stopping laser output without causing laser light to leak even if the power setting is changed during the output stop period.

  It is another object of the present invention to provide a laser device that prevents leakage of laser light when the power setting is changed during the output stop period and shortens the warm-up period until the laser output is enabled thereafter. To do.

  It is another object of the present invention to provide a laser device that does not change the warm-up time even when offset correction or proportional correction is performed on the drive current.

A laser marking device according to a first aspect of the present invention includes an excitation light source that generates excitation light, excitation light source driving means that supplies a drive current to drive the excitation light source, a laser crystal that converts the excitation light into laser light, And a laser oscillator having a Q switch capable of stopping the output of the laser light by diffracting the laser light, and a control signal for stopping the output of the laser light to the Q switch. And a control means for outputting a parameter value associated with the drive current to the excitation light source drive means, and the excitation light source drive means is configured to output the laser light during a period when the output of the laser light is stopped. When the parameter value input from the control means increases, the temperature distribution of the laser crystal is reduced based on the parameter values before and after the increase. The transition period required for the transition is determined, the drive current is increased from the start of the transition period, and the drive current corresponding to the increased parameter value is reached after the transition period has elapsed. Composed.

  In this laser apparatus, when the current setting is steady, the first driving means converts the current setting into the driving current, while when the current setting is increased, the second driving means changes the driving current with an inclination. The driving current converted by the first driving means is reached after a lapse of a predetermined transition period. At this time, the elapsed time is longer than when the drive current is decreased. For this reason, it is possible to suppress leakage of laser light while shortening the warm-up time after changing the drive current. In particular, if a pre-measured period sufficient for preventing leakage of laser light is employed as the transition period, complete stop of the laser light during the output stop period can be realized.

In addition to the above-described configuration, the laser marking device according to the second aspect of the present invention is configured so that the excitation light source driving means has the drive current so that the slope of the current change at the end of the transition period is smaller than the slope at the start. Configured to increase .

  With such a configuration, at the end of the transition period in which the drive current increases and the laser light is likely to leak, the drive current can be changed more slowly than at the start. For this reason, the transition period can be shortened while preventing leakage of laser light. Accordingly, it is possible to shorten the warm-up time after changing the current setting.

A laser marking device according to a third aspect of the present invention includes storage means for holding offset correction data designated by a user in addition to the above-described configuration, and the excitation light source driving means uses the parameter value based on the offset correction data. Offset correction means for offset correction , and when determining the transition period based on the parameter value before and after the increase, the transition period when the increase amount of the parameter value is the same is configured to be the same. The

  The offset correction changes the drive current, but does not affect the increase amount of the drive current. For this reason, if the transition period is determined based on the increase amount of the current setting and the transition period when the increase amount of the current setting is the same, the transition period does not change due to the influence of the offset correction. For this reason, a transition period according to the increase amount of the current setting can be adopted, and even if the offset correction data is changed, the warm-up time when the current setting is subsequently changed is not affected.

In addition to the above configuration, the laser marking device according to the fourth aspect of the present invention outputs an output even when the drive current corresponding to the parameter value after the increase is the maximum value as the transition period with respect to the parameter value before and after the increase. A transition period table associated with a pre-measured period during which the laser beam does not leak during the stop period, and the excitation light source driving means is configured to determine the transition period using the transition period table. The With such a configuration, in the laser device having the offset correction function, the warm-up time is not affected by the offset correction data, and the laser beam can be completely stopped during the output stop period.

A laser marking device according to a fifth aspect of the present invention includes storage means for holding proportion data designated by a user in addition to the above-described configuration, and the excitation light source driving means is configured for the parameter value based on the proportion data. Proportion correction means for correcting the slope of the drive current is provided. With such a configuration, in a laser device having a proportion correction function, the warm-up time is not affected by the proportion correction data, and the laser beam can be completely stopped during the output stop period.

In addition to the above-described configuration, the laser marking device according to the sixth aspect of the present invention includes an operation mode selection means for selecting an arbitrary operation mode from two or more operation modes having different laser output power ranges, and the parameter before and after the increase. and a transition period table for each operating mode that associates the transition period to the value, the pump light source drive means, when determining the transition period based on the parameter values before and after the increase, the same operating mode in The transition period in the case where the increase amount of the parameter value is the same is configured to be the same.

  With such a configuration, in a laser device having an offset correction function, when laser output is performed within the power range of an arbitrary operation mode, the warm-up time is not affected by the offset correction data, and the output stop period The warm-up time can be shortened while completely stopping the laser beam in

  A laser device according to a seventh aspect of the present invention includes standby control means for reducing the drive current to a standby level when the laser output is not performed for a certain period of time in addition to the above configuration, and operates the standby level. It is configured differently for each mode. With such a configuration, the warm-up time can be shortened.

  According to the present invention, leakage of laser light from the laser device can be suppressed during the output stop period in which the laser output is interrupted by the Q switch. In particular, it is possible to provide a laser device capable of completely stopping laser output without causing laser light to leak even if the power setting is changed during the output stop period.

  Moreover, when the power setting is changed during the output stop period, it is possible to provide a laser apparatus that prevents leakage of laser light and shortens the warm-up period until the laser output becomes possible thereafter.

  Further, it is possible to provide a laser apparatus that does not change the warm-up time even when the offset correction or the proportional correction is performed on the drive current.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an example of the configuration of a laser apparatus according to Embodiment 1 of the present invention for irradiating a marking surface of a workpiece (workpiece) with laser light to mark characters and figures. A laser marking device is shown. This laser marking device is composed of a head unit 10 and a controller unit 20. The head unit 10 and the controller unit 20 are housed in different housings, and are connected via an optical fiber cable 15 and signal lines 16 and 17. In addition, a user terminal 50 and a programmable controller (PLC: Programmable Logic Controller) 51 are connected to the controller unit 20.

  The head unit 10 includes a laser oscillator 11, a laser scanner 12, and an fθ lens 13. The excitation light is supplied from the controller unit 20 via the optical fiber cable 15, converted into laser light by the laser oscillator 11, and this laser light is incident on the laser scanner 12. The laser scanner 12 is composed of two galvanometer mirrors, and two-dimensionally scans the laser output light on the marking surface of the workpiece 52. The fθ lens 13 converts the laser light from the laser scanner 12 into parallel light and irradiates the work 52 with it.

The configuration of the laser oscillator 11 is the same as that in FIG. 16, and an air cooling method that does not involve circulation of the cooling medium is adopted as a cooling method. The scanner control signal and Q switch control signal _{S Q,} respectively via a signal line 16 and 17, is supplied from the controller 20.

  The controller unit 20 includes a marking control unit 21, an LD control unit 22, a laser diode 23, and various control data 30 to 33 storage units. The marking control unit 21 receives control signals from the user terminal 50 or the PLC 51, and controls the marking operation on the workpiece 52 based on these control signals. The marking condition DB (database) 30 stores a large number of marking conditions set in advance by the user. Each marking condition includes a power setting Ps, a mark shape, and the like, and an arbitrary marking condition can be designated from the user terminal 50 or the like.

The marking control unit 21 reads the designated marking condition from the marking condition DB 30 and outputs the power setting Ps to the LD control unit 22. Further, the Q switch control signal _SQ and the scanner control signal are generated based on the read mark shape. The Q switch control signal _SQ is an RF signal for on / off control of the laser output. The scanner control signal is a drive signal for driving the galvanometer mirror. These control signals are output to the head unit 10 via the signal lines 16 and 17 based on a trigger signal from the user terminal 50 or the like, and marking is started.

  The LD control unit 22 includes a current setting unit 24 and an LD driving unit 25. The current setting unit 24 refers to the current setting conversion table 31 and obtains the current setting Is from the power setting Ps. The current setting Is is a virtual parameter associated with the output power Po of the laser beam and has a value of 0 to 100%. The LD drive unit 25 generates a drive current Id to be supplied to the laser diode 23 based on the current setting Is.

  The laser diode 23 outputs excitation light having an intensity corresponding to the drive current Id, and the laser oscillator 11 outputs laser light having an output power Po corresponding to the excitation light. Therefore, the LD control unit 22 converts the power setting Ps into the drive current Id and supplies it to the laser diode 23, whereby the output power Po corresponding to the power setting Ps is obtained.

  FIG. 2 is a diagram showing an example of the current setting conversion table 31 of FIG. The current setting conversion table 31 is a data table for converting the power setting Ps to the current setting Is. The current setting Is corresponding to the power setting Ps is determined in advance and is held in the controller unit 20 as the current setting conversion table 31. Has been. In the present embodiment, the power setting Ps is directly converted into the current setting Is. In such a case, the current setting conversion table 31 can be omitted.

  The slope waveform data 32 is waveform data when the drive current Id is increased, and the LD drive unit 25 gradually increases the drive current Id with an inclination according to the waveform data. The transition period table 33 is a data table indicating a period necessary for increasing the drive current Id without leaking laser light, and is referred to when the current setting Is is changed in the current setting unit 24. The transition period is obtained based on the current setting Is before and after the change.

  FIG. 3 is a diagram illustrating an example of the relationship between the current setting Is and the drive current Id. The drive current Id is given as a linear function of the current setting Is, and the change amount of the current setting Is is proportional to the change amount of the drive current Id. The slope and intercept of the temporary function are both positive values. Here, the current setting Is when the output power Po is maximum is 100%, the drive current Id is decreased from this state, and the current setting Is when the laser beam is not output is 0%. The LD driving unit 25 converts the current setting Is into the driving current Id based on the relationship of FIG.

  The LD drive unit 25 supplies the drive current Id obtained from the current setting Is to the laser diode 23 using FIG. 3 when the current setting Is is steady. Even when the current setting Is is changed, if the current setting Is is to be decreased, the drive current Id obtained from the new current setting Is is immediately supplied in the same manner as in the steady state.

  On the other hand, when there is a setting change that increases the current setting Is, the drive current Id is gradually increased using the slope waveform data 32 and the transition period table 33. Specifically, the transition period table 33 is referred to obtain a transition period capable of preventing the leakage of the laser light, and the slope waveform data 32 is referred to and the new drive current Id is reached when the transition period elapses. As described above, the drive current Id is changed with a predetermined inclination. For this reason, when the current setting Is is increased, the transition period is longer than when the current setting Is is decreased, and the drive current Id is changed more gently.

  FIG. 4 is a diagram showing an example of the slope waveform data 32 of FIG. 1. FIG. 4A shows an example in which the slope is changed smoothly, and FIG. An example is shown. In any case, the elapsed time in the transition period is shown on the horizontal axis, and the increase in the drive current Id in the transition period is shown on the vertical axis. Further, the transition period is set to 1, and the increase amount of the drive current Id before and after the setting change is shown as 1.

  In the waveform data of (a), the slope of the drive current Id decreases with time, and the slope in the second half of the transition period is smaller than the slope in the first half of the transition period. Since the leakage of laser light is more likely to occur as the drive current Id increases, the drive current Id is changed according to such a slope waveform to prevent leakage of the laser light and drive in a shorter transition period. The current Id can be increased.

  The waveform data of (b) increases ½ of the total increase amount of the drive current Id at the start of the transition period, and thereafter increases the drive current with a constant slope. That is, as in the case of (a), the slope at the end of the transition period is made smaller than the slope at the start of the transition period, and the drive current Id is increased in a shorter transition period while preventing leakage of laser light. I am letting.

  The LD driving unit 25 uses the slope waveform data 32 by enlarging and reducing the slope waveform data 32 based on the actual transition period and the increase amount of the current setting Is. The transition period of the drive current Id required for preventing the leakage of the laser light varies depending on the drive current Id before and after the change. Therefore, in the present embodiment, the LD driving unit 25 uses the transition period table 33 to obtain the transition period from the current setting Is before and after the setting change. For this reason, the transition period can be shortened according to the combination of the current setting Is.

  FIG. 5 is a diagram showing an example of the transition period table 33 in FIG. The horizontal axis is the current setting Is1 before the setting change, and the vertical axis is the current setting Is2 after the setting change. This figure shows combinations of current settings Is1 and Is2 before and after the change for each case where the transition period is 50 milliseconds, 250 milliseconds, 1000 milliseconds, 3000 milliseconds, and 5000 milliseconds. For example, if the current setting Is1 before the change is 40% and the current setting Is2 after the change is 80%, the transition period is 250 milliseconds. The transition period table 33 is obtained by actually measuring the transition period when the laser light leaks.

  From this figure, it can be seen that the transition period required for preventing the leakage of the laser beam becomes longer as the increase amount (Is2-Is1) of the current setting Is is larger. It can also be seen that when the increase amount of the current setting Is is the same, the transition period becomes longer as the current setting Is2 after the change is larger.

  Steps S101 to S107 in FIG. 6 are flowcharts illustrating an example of the operation of the LD control unit 22. At the start of the flowchart, it is assumed that the power setting is Ps1 and the current setting is Is1. In this state, when the power setting is changed to Ps2, the current setting is also updated to Is2. That is, the current setting unit 24 checks the power setting Ps output from the marking control unit 21. If the power setting Ps has not been changed, the process is terminated (step S101). On the other hand, if the power setting Ps has been changed, a new current setting Is2 is obtained with reference to the current setting conversion table 31 (step S102).

  Next, the current settings Is1 and Is2 before and after the setting change are compared to determine whether the current setting has increased or decreased (step S103). If the current setting is increased, the transition period table 33 is referred to determine the transition period from the current settings Is1 and Is2 before and after the setting change (step S104). Further, the slope waveform data 32 is referred to, and the drive current Id is gradually increased according to the waveform data (steps S105 and S106). On the other hand, if the current setting Is is decreasing, the driving current Id is immediately decreased and a driving current corresponding to the new current setting Is2 is output (step S107).

FIG. 7 is a timing chart showing an example of the operation of the laser marking device of FIG. In the figure, (a) shows the drive current Id, (b) shows the Q switch control signal S _Q , and (c) shows the change on the time axis for the output power Po. In this laser marking device, when the current setting Is is increased, the drive current Id is gradually increased with an inclination. Therefore, even when the power setting Ps is changed when the Q switch 5 is in the OFF state, the laser beam does not leak from the laser marking device.

  In addition to this, the drive current Id is changed based on the slope waveform data 32, and the slope of the drive current Id is reduced with the passage of time during the transition period. For this reason, the drive current Id can be increased in a relatively short transition period.

  In the present embodiment, an example in which the drive current Id is increased using the slope waveform data 32 has been described, but the present invention is not limited to such a case. For example, the LD driving unit 25 performs a calculation process based on the current settings Is1 and Is2 before and after the change, thereby generating a waveform similar to that when the slope waveform data 32 is used, and gradually increasing the drive current Id. Also good.

  In the present embodiment, an example in which the power setting Ps is changed based on the marking condition and the current setting is changed has been described. However, the present invention is not limited to such a case. That is, the present invention can be applied to various cases in which the drive current Id is changed. For example, the present invention can also be applied when changing the drive current Id for current control during stop.

  The current control at the time of stop is intended to extend the life of the laser diode 23, and when the laser output is not performed for a predetermined period, the drive current Id is lowered to the standby level, and the laser diode 23 Is a process of shifting to the standby state. For example, the current setting unit 24 can shift to the standby state by forcibly setting the current setting Is to 0% regardless of the power setting Ps. In this standby state, when a trigger signal is input, the current setting unit 24 returns the current setting Is to the original value. If the present invention is applied to the laser marking device that performs such stop-time current control, it is possible to prevent laser light from leaking when the drive current Id increases at the end of standby.

Embodiment 2. FIG.
In this embodiment, an application example to a laser marking apparatus having an offset correction function will be described.

  FIG. 8 is a block diagram showing an example of the configuration of the laser apparatus according to Embodiment 2 of the present invention, in which the laser marking apparatus is shown. If this laser marking apparatus is compared with the case of FIG. 1 (Embodiment 1), it differs in that the controller unit 20 holds offset correction data 34.

  Steps S201 to S208 in FIG. 9 are timing charts showing an example of the operation of the laser marking device in FIG. 8, and the operation of the LD drive unit 25 is shown. Compared with the case of FIG. 6 (Embodiment 1), the difference is that the offset correction processing in step S203 is performed after referring to the current setting conversion table 31. That is, in the present embodiment, the LD driving unit 25 adds the offset correction data 34 to the current setting Is, and converts the current setting Is after the offset into the driving current Id. By performing such an offset correction process, the output power Po can be offset without changing the power setting Ps in the marking condition. The offset correction data 34 is designated by the user, and the current setting after offset does not exceed 100%.

  In general, in a laser marking device, the output power Po decreases with time, and the marking density decreases. Even in such a case, a desired output power Po can be obtained by rewriting each marking condition in the marking condition DB 30 and increasing the power setting Ps. However, it is not easy to rewrite the power setting Ps for many marking conditions. In such a case, if the offset correction process is used, the output power Po can be increased only by changing the offset correction data 34 without changing each marking condition. The offset correction data 34 is determined by the user by trial and error.

  In the laser marking apparatus having such an offset correction function, there is a problem that the timing of the marking operation is changed by changing the offset correction data 34.

  When a setting change that increases the power setting Ps is performed, a warm-up time determined by the transition period is required before the marking operation can be performed thereafter. However, if the offset correction function is provided, the transition period must be determined based on the current setting Is after offset. For this reason, if the transition period varies depending on the offset correction data 34, the warm-up time also varies. That is, even if the marking conditions are the same, if the offset correction data 34 is different, the warm-up time may not be the same, and the same marking operation may not be performed due to the change in the offset correction data 34. To do.

  For example, when the current setting Is is changed from 40% to 70%, according to FIG. 5, a transition period of 50 milliseconds is required. For this reason, if 50 milliseconds elapses after the power setting Ps is changed, the marking can be started. However, when the offset correction data 34 is raised from 0% to 20%, the setting change corresponds to a setting change from 60% to 90% due to offset correction. In this case, according to FIG. 5, a transition period of 250 msec is required, and the marking cannot be started until 250 msec elapses after the power setting Ps is changed, and the marking operation after the setting change is 200 m. There is a possibility of being delayed by a second.

  That is, if the offset correction data is changed, the warm-up time varies, and the same marking operation as before may not be realized. Such a problem occurs not only when the power setting Ps is changed but also when the standby is completed.

  In the laser marking device according to the present embodiment, such a problem is solved by improving the transition period table 33.

  FIG. 10 is a diagram showing an example of the transition period table 33 in FIG. 8, and shows the relationship between the current settings Is1 and Is2 before and after the setting change and the transition period. The transition period according to the present embodiment is indicated by a solid line, and the transition period of FIG. 5 (Embodiment 1) is indicated by a broken line as a comparative example. When both are compared, it can be seen that the slopes of the characteristics with the same transition period are different.

  The transition period table of FIG. 5 is created based on the transition period required to prevent leakage of laser light. That is, it is created according to the physical characteristics of the laser marking device. On the other hand, the transition period table 33 according to the present embodiment shown in FIG. 8 can prevent the leakage of the laser beam and has a characteristic gradient (ΔIs2 / ΔIs1) with the same transition period. The transition period is determined to be 1. In other words, the laser marking device is created taking into consideration both the physical characteristics of the laser marking device and the influence of offset correction.

  When the power setting Ps is changed, the same offset correction data 34 is added to the current settings Is1 and Is2 before and after the change. In FIG. 8, such an offset correction process corresponds to an operation of moving the same distance in the vertical axis direction and the horizontal axis direction, and the influence of the offset correction appears as a movement in the direction of inclination 1. Therefore, if the slope of the characteristic with the same transition period is 1, even if offset correction is performed, the transition period is not affected. In other words, in the laser marking device according to the present embodiment, the transition period is determined based on the current setting increase amount (Is2-Is1), and is not affected by the values of the current settings Is1, Is2 themselves. Also, it is not affected by offset correction.

  As described above, the larger the current setting Is, the easier the laser light leaks out, and the transition period needs to be lengthened. However, the current setting Is does not exceed 100%. For this reason, in the transition period table 33 according to the present embodiment, the transition period when the current setting Is2 after the setting change is 100% is employed.

  According to the present embodiment, the transition period is determined based on the current setting increase amount (Is2−Is1) using the transition period table 33 in which the slope of the characteristic with the same transition period is 1. For this reason, in the laser marking device capable of performing offset correction, fluctuations in the transition period due to fluctuations in the offset correction data can be prevented, and fluctuations in the warm-up time after the power setting Ps is changed can be prevented. In addition, since the transition period employs a value that does not cause the laser beam to leak when the current setting Is2 after the setting change is 100%, the laser beam leaks regardless of the current setting Is and the offset correction data 34. There is nothing.

Embodiment 3 FIG.
In the present embodiment, an application example to a laser marking apparatus having a proportion correction function will be described.

  FIG. 11 is a block diagram showing a configuration example of a laser device according to Embodiment 3 of the present invention, in which a laser marking device is shown. If this laser marking device is compared with the case of FIG. 8 (Embodiment 2), the controller unit 20 is different in that the proportion correction data 35 is retained.

This laser marking device performs an offset correction process and a proportion correction process when determining the drive current Id. If the current value converted from the current setting Is based on the characteristics shown in FIG. 3 is I (Is), the offset correction data 34 is X, and the proportion correction data 35 is Y, It is given by the formula.
Id = I (Is) + X + Is × Y

  The offset correction process described in the second embodiment corresponds to a process of changing the intercept of the current setting Is-drive current Id characteristic of FIG. On the other hand, the proportion correction process corresponds to a process of changing the inclination of the characteristic. In this manner, by adjusting not only the offset but also the slope of the current setting Is-drive current Id characteristic, the drive current Id can be adjusted with a higher degree of freedom. For this reason, it is possible to cope with various fluctuations in the output power Po caused by changes over time without changing the marking conditions. The proportion correction data 35 is determined by a user through trial and error, and can specify a positive or negative value within a predetermined allowable range.

  In the laser marking apparatus having such a proportion correction function, the same problem as in the case of having the offset correction function occurs. That is, there is a problem that changing the proportion correction data 35 changes the warm-up time and changes the timing of the subsequent marking operation.

  In the laser marking device according to the present embodiment, such a problem is solved by further improving the transition period table 33.

  FIG. 12 is a diagram illustrating an example of the transition period table 33 in FIG. 11, and shows the relationship between the current settings Is1 and Is2 before and after the setting change and the transition period. The transition period according to the present embodiment is indicated by a solid line. Compared to the case of FIG. 10 (Embodiment 2), the characteristics with the same transition period are shifted upward while maintaining the slope at 1. In other words, the leakage of laser light is prevented by increasing the value of the transition period.

  In the transition period table 33 of the second embodiment, the time required when the current setting Is2 after the setting change is 100% is used as the transition period. On the other hand, in the present embodiment, even when the proportion correction data 35 is set to a positive maximum value, the time during which the laser beam is not leaked is used as the transition period. That is, in the transition period table 33 according to the present embodiment, as the transition period, the time required when the current setting Is2 after the setting change is 100% and the proportion correction data 35 is a positive maximum value. Is adopted.

  According to the present embodiment, the transition period is determined based on the current setting increase amount (Is2−Is1) using the transition period table 33 in which the slope of the characteristic with the same transition period is 1. For this reason, in the laser marking device capable of performing offset correction, fluctuations in the transition period due to fluctuations in offset correction data can be prevented. At this time, as the transition period, a value that does not leak the laser beam when the current setting Is2 after the setting change is 100% and the proportion correction data 35 is the maximum positive value is adopted. For this reason, the laser beam does not leak regardless of the current setting Is, the offset correction data 34 and the proportion correction data 35.

Embodiment 4 FIG.
In the present embodiment, a laser marking apparatus that has two or more operation modes with different power ranges and shortens the warm-up time at the time of changing the power setting Ps and at the end of standby will be described.

  In the second and third embodiments, the drive current Id is based on the difference (Id2-Id1) of the drive current before and after the change of the power setting Ps in order to prevent fluctuations in the warm-up time due to the effects of the offset correction process and the proportion correction process. Determine the transition period for the increase. That is, by associating the longest transition period assumed under the conditions with the difference in drive current (Id2-Id1) in advance, it is possible to prevent laser light from leaking and also prevent fluctuations in operation timing. In addition, the transition period as short as possible is realized according to the difference (Id2−Id1) in the drive current.

  However, in such a laser marking device, even when it is used only at a low output power Po, a transition period considering the use at a high output power Po is used, and the warm-up time is longer than necessary. There is a problem of becoming longer.

  As described above, the laser oscillator is likely to leak the laser beam as the output power Po increases, so that a long transition period is required. Therefore, in such a laser marking device, even when it is used only at a low output power Po, the same transition period as that when used at a high output power Po is secured, and the warm-up time becomes long. . On the other hand, it is conceivable to shorten the warm-up time by lowering the maximum value of the output power Po, but in this case, the high output power Po cannot be used.

  In the laser marking device according to the present embodiment, such a problem is solved by improving the current setting conversion table 31.

  FIG. 13 is a block diagram showing a configuration example of a laser marking device according to Embodiment 4 of the present invention. When this laser marking device is compared with the case of FIG. 11 (Embodiment 3), the controller unit 20 includes two current setting conversion tables 31H and 31L and two transition period tables 33H and 33L. Different.

  The current setting conversion table 31H and the transition period table 33H are data tables used in the high power mode, and the current setting conversion table 31L and the transition period table 33L are tables used in the low power mode. That is, one of the current setting conversion tables 31H and 31L is selected by the current setting unit 24 according to the operation mode. Further, either one of the transition period tables 33H and 33L is selected by the LD driving unit 25 according to the operation mode.

  This laser marking apparatus has a high power mode and a low power mode as operation modes, and any one operation mode is selected by the user. In these operation modes, the range of available output power Po is different. Further, the current control during stop is performed in any operation mode, but the current setting Is in the standby state is different for each operation mode.

  FIG. 14 is a diagram showing an example of the current setting conversion tables 35H and 35L in FIG. The user can specify 0 to 100% as the power setting Ps regardless of the operation mode. This power setting range is associated with a current setting Is of 70 to 100% in the current setting table 31H, and is associated with a current setting Is of 0 to 80% in the current setting table 31L. That is, the current setting unit 24 can output 70 to 100% as the current setting Is in the high power mode, and can output 0 to 80% as the current setting Is in the low power mode.

  Moreover, the current setting unit 24 uses a value corresponding to the power setting Ps of 0% as the current setting Is in the standby state when performing the current control at the time of stop. That is, 70% is output as the current setting Is during standby in the high power mode, and 0% is output as the current setting Is during standby in the low power mode. Therefore, the drive current Id in the standby state varies depending on the operation mode.

  FIG. 15 is a diagram illustrating an example of the transition period tables 33H and 33L in FIG. As in the case of the third embodiment, these transition period tables 33H and 33L are created so that the transition period does not vary by the offset process and the proportion correction process. That is, when the transition period is determined based on the increase amount (Is2−Is1) of the current setting Is and the drive current Id after the setting change becomes the maximum as the transition period (that is, the current setting Is2 after the change is The value of 100% is used when the proportion correction data is the maximum).

  The transition period tables 33H and 33L have a shorter transition period since the range of the current setting Is is narrower than in the case of the third embodiment. That is, in the low power mode, since the current setting Is is 80% or less, the transition period at the same setting change time can be further shortened as compared with the case of 0 to 100%. Therefore, the warm-up time at the time of changing the power setting Ps and at the end of the standby can be shortened. In the high power mode, the transition period at the same setting change does not change, but the current setting Is at standby is set to 70%, so that the warm-up time at the end of standby can be shortened.

  According to the present embodiment, the laser marking device has two operation modes having different power ranges. For this reason, it is possible to further shorten the warm-up time while preventing fluctuations in the warm-up time due to the offset correction process and the proportion correction process. Also, the warm-up time at the end of standby can be shortened by making the current setting Is during standby different for each operation mode.

  In the present embodiment, the case where the laser marking device can select either the high power mode or the low power mode has been described. However, the present invention is not limited to such a case. In other words, it is possible to provide three or more current setting conversion tables and three or more transition period tables so that an arbitrary operation mode can be selected from the three or more operation modes.

It is the block diagram which showed one structural example of the laser apparatus by Embodiment 1 of this invention. It is the figure which showed an example of the electric current setting conversion table 31 of FIG. It is the figure which showed an example of the relationship between electric current setting Is and drive current Id. It is the figure which showed an example of the slope waveform data 32 of FIG. It is the figure which showed an example of the transition period table 33 of FIG. 5 is a flowchart showing an example of the operation of the LD control unit 22. 2 is a timing chart showing an example of the operation of the laser marking device in FIG. 1. It is the block diagram which showed one structural example of the laser apparatus by Embodiment 2 of invention. It is a timing chart which showed an example of operation of the laser marking device of Drawing 8. It is the figure which showed an example of the transition period table 33 of FIG. It is the block diagram which showed one structural example of the laser apparatus by Embodiment 3 of this invention. It is the figure which showed an example of the transition period table 33 of FIG. It is the block diagram which showed one structural example of the laser marking apparatus by Embodiment 4 of this invention. It is the figure which showed an example of the current setting conversion tables 35H and 35L of FIG. It is the figure which showed an example of the transition period tables 33H and 33L of FIG. It is the figure which showed the example of schematic structure of the conventional laser oscillator. It is the timing chart which showed the operation example of the conventional laser oscillator. It is explanatory drawing about the thermal lens formed in the laser crystal.

Explanation of symbols

4 Laser crystal 4R Thermal lens 5 Q switch 10 Head unit 11 Laser oscillator 20 Controller unit 21 Marking control unit 22 LD control unit 23 Laser diode 24 Current setting unit 25 LD drive units 31, 31H, 31H Current setting conversion table 32 Slope waveform data 33, 33H, 33L Transition period table 34 Offset correction data 35 Proportion correction data 50 User terminal 52 Work Id Drive current Is, Is1, Is2 Current setting Po Laser output Po Output power Ps Power setting S _Q Q Switch control signal

Claims (7)

An excitation light source that generates excitation light;
Excitation light source driving means for driving the excitation light source by supplying a drive current;
A laser crystal that converts the excitation light into laser light, and a laser oscillator having a Q switch capable of stopping the output of the laser light by diffracting the laser light;
A control means for transmitting a control signal for stopping the output of the laser light to the Q switch, and for outputting a parameter value associated with the drive current to the excitation light source drive means,
When the parameter value input from the control unit increases during the period in which the output of the laser beam is stopped, the excitation light source driving unit determines the temperature of the laser crystal based on the parameter value before and after the increase. Determine the transition period required for the distribution to stabilize, increase the drive current from the start of the transition period, and reach the drive current corresponding to the increased parameter value after the transition period has elapsed laser marking apparatus characterized by causing. 2. The laser marking device according to claim 1, wherein the excitation light source driving unit increases the drive current so that a slope of a current change at the end of the transition period is smaller than a slope at a start time. . Storage means for holding offset correction data specified by the user,
The excitation light source drive means includes offset correction means for offset correction of the parameter value based on offset correction data, and increases the parameter value when determining the transition period based on the parameter value before and after the increase. The laser marking device according to claim 1, wherein the transition periods in the same amount are the same. For the parameter value before and after the increase , the transition period corresponds to a pre-measured period during which the laser beam is not leaked during the output stop period even if the drive current corresponding to the parameter value after the increase is the maximum value With a transition period table attached,
4. The laser marking device according to claim 3, wherein the excitation light source driving unit determines the transition period using the transition period table. A storage means for holding the proportion data specified by the user;
5. The laser marking apparatus according to claim 4, wherein the excitation light source driving means includes proportion correction means for correcting a slope of the driving current with respect to the parameter value based on the proportion data. An operation mode selection means for selecting an arbitrary operation mode from two or more operation modes having different power ranges of laser outputs;
A transition period table for each operation mode in which the transition period is associated with the parameter values before and after the increase ;
When the excitation light source driving means determines the transition period based on the parameter values before and after the increase, the transition period in the same operation mode when the increase amount of the parameter value is the same is made the same. The laser marking device according to claim 3 or 5, wherein When there is no laser output over a certain period of time, equipped with standby control means to reduce the drive current to the standby level,
7. The laser marking device according to claim 6, wherein the standby level is made different for each operation mode.

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