JP2023007738A - Laser control device and laser pulse cutting-out method - Google Patents

Abstract

To provide a laser control device which can improve energy utilization efficiency of laser pulse.SOLUTION: A laser oscillator outputs pulse laser beam LP0. The pulse laser beam LP0 enters a cutting-out optical system. The cutting-out optical system has property for starting cutting-out of a part LP1 of laser pulse of the pulse laser beam LP0 when a certain operating delay time tdo has elapsed after a cutting-out command chp is inputted. A laser control device outputs the cutting-out command chp to the cutting-out optical system at a point before a laser pulse rising point t2, and outputs the cutting-out command chp so that the point when only the operating delay time tdo has elapsed after outputting the cutting-out command is later than the laser pulse rising point t2.SELECTED DRAWING: Figure 4

Description

The present invention relates to a laser control device and a laser pulse cutting method.

2. Description of the Related Art There is known a laser processing apparatus that uses a laser beam to drill a hole in a printed circuit board or the like (see Patent Document 1). The laser processing apparatus disclosed in Patent Document 1 includes a laser oscillator that outputs a pulsed laser beam and an acoustooptic modulator that cuts out a portion of the laser pulse. After the rise of the laser pulse, a part is cut out from the laser pulse by giving a cutting command to the acousto-optic modulator. The cut laser pulse is incident on the object to be processed, and the remaining laser pulse is input to the beam damper.

JP 2017-159317 A

In a cutting optical system such as an acousto-optic modulator, an operation delay occurs from when a cutting command is input to when a laser pulse is actually cut out. Therefore, the energy of the laser pulse is wasted during the period from the rise of the laser pulse to the input of the cutting command and the period from the input of the cutting command to the actual cutting. In other words, the utilization efficiency of the laser pulse energy is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser control device and a laser pulse cutting method capable of increasing the energy utilization efficiency of laser pulses.

According to one aspect of the invention,
a laser oscillator that outputs a pulsed laser beam;
a cutting optical system having a characteristic of starting to cut out a part of the laser pulse of the pulsed laser beam when a certain operation delay time has passed after the pulsed laser beam is incident and a cutting command is input; A laser control device for controlling
The cutting command is output to the cutting optical system at a time before the rising time of the laser pulse, and the time when the operation delay time elapses from the time when the cutting command is output is the time when the laser pulse rises. A laser control device is provided for outputting the cut-out command after the rising time.

According to another aspect of the invention,
A laser pulse cutting method for outputting a laser pulse from a laser oscillator and making it enter a cutting optical system to cut out a part of the laser pulse,
The extraction optical system has a characteristic of starting extraction of a part of the laser pulse after a certain operation delay time has passed since the extraction command is input,
The cutout command is output to the cutout optical system at a time before the rise of the laser pulse, and the rise of the laser pulse is reached at the time when the operation delay time has elapsed from the time when the cutout command was output. A laser pulse segmentation method is provided for outputting the segmentation command after the point in time.

When the cutout command is output under the above conditions, the time from the rise of the laser pulse to the start of cutout becomes shorter than the operation delay time. Therefore, the energy utilization efficiency of the laser pulse can be improved.

FIG. 1 is a schematic diagram of a laser processing machine equipped with a laser control device according to one embodiment. FIG. 2 is a chart showing an example of relationship information stored in a storage unit. FIG. 3 is a graph showing another example of relationship information stored in the storage unit. 4A and 4B are timing charts of the oscillation command trg, the laser pulse LP0, the cutting command chp, and the laser pulse LP1 when the laser control devices according to the present embodiment and the comparative example operate, respectively. FIG. 5 is a flow chart showing a procedure for extracting a laser pulse pulse executed by the laser control device according to the present embodiment. FIG. 6 is a flow chart showing the procedure for determining the pulse output delay time td. FIG. 7 is a schematic diagram of a laser processing machine equipped with a laser control device according to another embodiment. FIG. 8 is a timing chart of the oscillation command trg, the laser pulse LP0, the path selection command sel, the cutting command chp, and the laser pulses LP1 and LP2 when operating the laser control device according to another embodiment.

A laser control device and a laser pulse cutting method according to an embodiment will be described with reference to FIGS. 1 to 6. FIG.

FIG. 1 is a schematic diagram of a laser processing machine equipped with a laser control device 40 according to this embodiment. This laser processing machine is used, for example, for drilling a printed circuit board.

The laser oscillator 10 receives the oscillation command trg from the laser control device 40 and outputs a pulse laser beam. As the laser oscillator 10, for example, a gas laser oscillator such as a carbon dioxide laser oscillator is used. A pulsed laser beam output from a laser oscillator 10 is split into two paths by a beam splitter 11 . A partially reflecting mirror, for example, is used as the beam splitter 11 .

One of the two pulsed laser beams split by the beam splitter 11 passes through the irradiation optical system 12 and the aperture 13 and enters the extraction optical system 14 , while the other enters the photodetector 20 . The irradiation optical system 12 changes at least one of the spread angle and beam diameter of the pulse laser beam. A beam expander, for example, is used as the irradiation optical system 12 . Aperture 13 shapes the beam cross section of the pulsed laser beam.

The photodetector 20 outputs a detection signal det while the laser pulse is incident. As the photodetector 20, for example, a photovoltaic element or the like capable of high-speed response is used. A detection signal det output from the photodetector 20 is input to the laser control device 40 .

The cutting optical system 14 cuts out a portion on the time axis from the incident laser pulse LP0 based on a cutting command chp input from the laser control device 40, and generates a laser pulse LP1 used for processing. A certain operation delay occurs from the time when the cutting command chp is input until the laser pulse LP1 is cut out. The time from the input of the extraction command chp to the extraction of the laser pulse LP1 is defined as an operation delay time tdo. A portion of the laser pulse LP 0 other than the laser pulse LP 1 enters the beam damper 15 . A laser pulse LP1 cut out from the laser pulse LP0 propagates along the machining path. For example, an acousto-optic modulator (AOM) is used as the cutting optical system 14 .

The laser pulse LP1 extracted by the extraction optical system 14 is incident on the workpiece 60 via the folding mirror 16, the scanning optical system 17, and the lens 19. FIG. The scanning optical system 17 swings the advancing direction of the pulse laser beam in two-dimensional directions based on the control signal sig 1 from the laser control device 40 . As the scanning optical system 17, for example, a galvanometer scanner including a pair of movable mirrors 18X and 18Y is used. The lens 19 converges the pulsed laser beam whose traveling direction is changed by the scanning optical system 17 onto the surface of the object 60 to be processed. As the lens 19, for example, an fθ lens is used. By operating the scanning optical system 17 , the pulse laser beam can be made incident on an arbitrary position within a partial area (scan area) on the surface of the object 60 to be processed.

The object 60 to be processed is, for example, a printed circuit board, and is horizontally held on the stage 30 . The moving mechanism 31 moves the stage 30 in two mutually orthogonal directions parallel to the horizontal plane based on the control signal sig2 from the laser control device 40 . By moving the stage 30 , any region within the surface of the workpiece 60 can be arranged within the scan area that can be scanned by the scanning optical system 17 .

A laser control device 40 controls the laser oscillator 10 , the cutting optical system 14 , the scanning optical system 17 and the moving mechanism 31 . Functions for controlling these are realized by a combination of software and hardware. The laser control device 40 includes a storage unit 41 that stores programs and various data for realizing these functions. The functions of the laser control device 40 will be briefly described below. Note that detailed functions of the laser control device 40 will be described later with reference to the timing chart of FIG. 4A and the flow charts of FIGS.

Various parameters that define laser irradiation conditions are input from the input device 50 to the laser control device 40 . The parameters that define the laser irradiation conditions include the pulse repetition frequency f of the pulse laser beam output from the laser oscillator 10, the pulse width (hereinafter referred to as the original pulse width pw0), and the laser pulse LP1 extracted from the laser pulse LP0. pulse width, etc. As the input device 50, for example, a keyboard, a touch panel, a pointing device, a communication device, a reading device for removable media, and the like are used.

The laser controller 40 receives the detection signal det from the photodetector 20 and detects rising and falling edges of the laser pulse. An oscillation command trg is output to the laser oscillator 10 based on the information defining the pulse repetition frequency f and the original pulse width pw0. For example, the rise and fall of the oscillation command trg correspond to the commands to start and stop oscillation, respectively, and the time from the rise to the fall corresponds to the original pulse width pw0. The frequency for outputting the oscillation command trg corresponds to the pulse repetition frequency f.

Furthermore, the delay time from the time when the oscillation command trg is output to the time when the rise of the laser pulse is detected is measured. This delay time is referred to as "pulse output delay time td". The laser control device 40 further stores relational information in which the pulse repetition frequency f and the original pulse width pw0 are associated with the pulse output delay time td in the storage unit 41 .

FIG. 2 is a table showing an example of relationship information stored in the storage unit 41. As shown in FIG. A pulse output delay time td is associated with each combination of the pulse repetition frequency f and the original pulse width pw0. For example, when the pulse repetition frequency f=f ₁ and the original pulse width pw0= _pw1 , the pulse output delay time td= _td11 .

FIG. 3 is a graph showing another example of relationship information stored in the storage unit 41. As shown in FIG. The horizontal axis represents the pulse repetition frequency f, and the vertical axis represents the pulse output delay time td. The curve in the graph shows the relationship between the pulse repetition frequency f and the pulse output delay time td when the original pulse width pw0 is constant. The pulse output delay time td is defined as a function of the pulse repetition frequency f under the condition that the original pulse width pw0 is constant. The definition formula of this function is stored in the storage unit 41 .

In the example shown in FIG. 3, when the original pulse width pw0 is constant, the pulse output delay time td decreases as the pulse repetition frequency f increases. When the pulse repetition frequency f is constant, the pulse output delay time td becomes shorter as the original pulse width pw becomes longer.

The laser control device 40 (FIG. 1) outputs the cutting command chp after a certain period of time has passed since the oscillation command trg was output. The time from outputting the oscillation command trg to outputting the cutout command chp is called “cutout command delay time tdc”. The laser control device 40 calculates the cutting command delay time tdc based on the pulse output delay time td and the like.

The laser control device 40 further outputs a control signal sig1 to the scanning optical system 17 to position the incident position of the pulse laser beam. Furthermore, the control signal sig2 is output to the moving mechanism 31 to move the workpiece 60 .

FIG. 4A is a timing chart of the oscillation command trg, laser pulse LP0, cutting command chp, and laser pulse LP1. At time t0, the laser control device 40 outputs an oscillation command trg. For example, the rise of the oscillation command trg corresponds to the command to start oscillation, and the fall corresponds to the command to end oscillation. The elapsed time from the rise to the fall of the oscillation command trg corresponds to the original pulse width pw0.

The laser oscillator 10 outputs a laser pulse LP0 (time t2) after a certain period of time has passed since the rise of the oscillation command trg (time t0). The elapsed time from the rise of the oscillation command trg to the rise of the laser pulse LP0 corresponds to the pulse output delay time td (FIGS. 2 and 3). When oscillation command trg falls (time t6), the intensity of laser pulse LP0 begins to fall, and then laser pulse LP0 completely falls (time t7).

The laser control device 40 outputs the cutout command chp at the time (time t1) after the cutout command delay time tdc has elapsed since the rise of the oscillation command trg (time t0). The rising edge of the cutting command chp corresponds to the cutting start command, and the falling edge (time t4) corresponds to the cutting end command. The elapsed time from the rising edge to the trailing edge of the cutting command chp is defined as a cutting pulse width pw1.

Due to the operation delay of the extraction optical system 14 (FIG. 1), extraction from the laser pulse LP0 is started at the time (time t3) after the operation delay time tdo has elapsed since the rise of the extraction command chp (time t1). Pulse LP1 rises. Similarly, at the time (time t5) after the operation delay time tdo has elapsed from the fall of the cutting command chp (time t4), the cutting of the laser pulse LP0 is finished and the laser pulse LP1 falls.

FIG. 5 is a flow chart showing a procedure for extracting a laser pulse pulse executed by the laser control device according to the present embodiment.

First, the laser control device 40 controls the pulse repetition frequency f and the original pulse width pw0 (FIG. 4A) of the pulse laser beam to be output from the laser oscillator 10, and the related information stored in the storage unit 41 (FIGS. 2 and 3). ), the pulse output delay time td (FIG. 4A) is calculated (step SA1). Information designating the pulse repetition frequency f and the original pulse width pw0 is input in advance from the input device 50 (FIG. 1) to the laser control device 40 .

Based on the pulse output delay time td calculated in step SA1 and the operation delay time tdo of the cutting optical system 14, the laser control device 40 outputs the cutting command chp from the output time point (time t0) of the oscillation command trg. A cutting instruction delay time tdc (FIG. 4A) up to time (time t1) is calculated (step SA2). For example, the cutting command delay time tdc is longer than the value obtained by subtracting the operation delay time tdo from the pulse output delay time td (td−tdo<tdc) and is shorter than the pulse output delay time td (tdc<td). Then, the cutting instruction delay time tdc is determined.

After that, or in parallel, a control signal sig1 is output to the scanning optical system 17 and a control signal sig2 is output to the moving mechanism 31 so that the laser pulse is incident on the target position of the workpiece 60. (Step SA3).

The laser control device 40 outputs an oscillation command trg to the laser oscillator 10 (step SA4). After that, it waits until the cutting instruction delay time tdc passes (step SA5). When the cutting instruction delay time tdc has passed. The laser control device 40 determines whether or not the positioning of the incident position of the laser pulse by the scanning optical system 18 and the moving mechanism 31 has been completed (step SA6).

If the positioning has not been completed, the oscillation command trg is stopped after the time corresponding to the original pulse width pw0 has elapsed since the oscillation command trg was output (step SA13).

When the positioning is completed, the laser control device 40 outputs a cutting command chp to the cutting optical system 14 (step SA7). After that, it waits until the time corresponding to the cut-out pulse width pw1 (FIG. 4A) elapses (step SA8). After waiting, the cutting command chp is stopped (step SA9). Specifically, the cutting command chp is lowered. After that, the oscillation command trg is stopped (step SA10). More specifically, when the original pulse width pw0 has passed since the output of the oscillation command trg, the oscillation command trg is lowered.

It is determined whether or not the machining of all points to be machined on the object 60 has been completed (step SA11). When the machining of all points to be machined is completed, the process is terminated. If unprocessed points to be processed remain, the laser control device 40 controls the scanning optical system 18 and the moving mechanism 31 (step SA12). It should be noted that the moving mechanism 31 does not need to be driven when the object 60 does not need to be moved.

After step SA12 or step SA13, the process waits for a time corresponding to the pulse repetition frequency f (step SA13). This waiting time starts from the time when the oscillation command trg is output at step SA4. After waiting for a period of time corresponding to the pulse repetition frequency f, an oscillation command trg is output (step SA4), and the procedures after step SA5 are repeated. As a result, the waveforms of the oscillation command trg, the laser pulses LP0 and LP1, and the cutting command chp shown in FIG. 4A are repeated at a constant frequency. It should be noted that the cutting command chp is not output in a cycle in which positioning is not completed.

Next, a method of determining the pulse output delay time td (FIGS. 2 and 3) stored in the storage section 41 (FIG. 1) will be described with reference to FIG. FIG. 6 is a flow chart showing the procedure for determining the pulse output delay time td.

First, the values of the pulse repetition frequency f and the original pulse width pw0 are determined (step SB1). These values are input from the input device 50 . The laser control device 40 outputs an oscillation command trg to the laser oscillator 10 under the conditions of the pulse repetition frequency f and the original pulse width pw0 determined in step SB1 (step SB2). When the laser pulse LP0 (FIG. 1) rises, the detection signal det from the photodetector 20 is input to the laser controller 40. FIG. A delay time from the output of the oscillation command trg to the reception of the detection signal det is measured (step SB3).

When a plurality of predetermined laser pulses LP0 are output, the average value of the measured delay times from the output of the oscillation command trg to the reception of the detection signal det is calculated (step SB4). This average value corresponds to the pulse output delay time td. The pulse output delay time td is stored in the storage section 41 in association with the pulse repetition frequency f and the original pulse width pw0 determined in step SB1 (step SB5).

Next, the excellent effects of this embodiment will be described in comparison with the comparative example shown in FIG. 4B.
FIG. 4B is a timing chart of the oscillation command trg, laser pulse LP0, cutting command chp, and laser pulse LP1 in the comparative example. In the comparative example, the cutout command chp is output at the time (time t1) after a constant cutout command delay time tdc1 has elapsed since the rise of the laser pulse LP0 was detected (time t2). At the point in time (time t3) when the operation delay time tdo has passed since the output of the cutting command chp, cutting from the laser pulse LP0 is started, and the laser pulse LP1 rises.

The laser energy during the time until the laser pulse LP1 rises in the laser pulse LP0 is wasted. In the comparative example, the time tw during which the laser energy is wasted is longer than the operation delay time tdo of the cutting optical system 14 .

On the other hand, in the above-described embodiment, the cutting command chp is output before the rising edge of the laser pulse LP0 (time t2). It is shorter than the operation delay time tdo of the output optical system 14 . Therefore, it is possible to reduce the amount of laser energy that is wastefully discarded and increase the utilization efficiency of the laser pulse LP0.

Furthermore, in the above-described embodiment, the pulse output delay time td is stored in the storage unit 41 for each pulse repetition frequency f and original pulse width pw0. Even if the pulse width pw0 is changed, in step SA2 (FIG. 5), the cutting command delay time tdc can be calculated using an appropriate pulse output delay time td according to the actual machining conditions. can.

If the pulse output delay time td corresponding to the pulse repetition frequency f and the original pulse width pw0 used for actual machining is not stored in the storage unit 41, the pulse output delay time td is set according to the procedure shown in FIG. can ask. When the pulse output delay time td corresponding to the pulse repetition frequency f and the original pulse width pw0 used for actual machining is not stored in the storage unit 41, the already stored pulse output delay time td is used. The pulse output delay time td may be obtained by performing an interpolation calculation using .

Next, a modification of the above embodiment will be described.
In the above embodiment, the relational information (FIGS. 2 and 3) that associates both the pulse repetition frequency f and the original pulse width pw0 with the pulse output delay time td is stored in the storage unit 41 (FIG. 1). there is For example, if the pulse output delay time td hardly changes even when the original pulse width pw0 is changed, the pulse output delay time td may be related only to the pulse repetition frequency f. Conversely, when the pulse output delay time td hardly changes even when the pulse repetition frequency f is changed, the pulse output delay time td may be related only to the original pulse width pw0.

Next, a laser pulse extraction method based on the procedure of the laser control device 40 (FIG. 1) according to the above embodiment will be described.

As shown in FIG. 4A, the extraction optical system 14 (FIG. 1) has the characteristic of starting to extract a portion of the laser pulse LP0 at the time when the operation delay time tdo has passed since the extraction command chp was input. have. A cutting command chp is output to the cutting optical system 14 at a time before the rising time of the laser pulse LP0. At this time, the cutout command chp is output so that the time when the operation delay time tdo has passed since the time when the cutout command chp was output is after the rising time of the laser pulse LP0.

By controlling the output timing of the cutout command chp in this way, it is possible to reduce the amount of laser energy that is wastefully discarded and increase the utilization efficiency of the laser pulse LP0.

Next, a laser control device according to another embodiment will be described with reference to FIGS. 7 and 8. FIG. Hereinafter, descriptions of configurations common to the embodiments described with reference to FIGS. 1 to 6 will be omitted.

FIG. 7 is a schematic diagram of a laser processing machine equipped with a laser control device according to this embodiment. In the embodiment shown in FIG. 1, there is one machining path. On the other hand, in this embodiment, there are two machining paths. The cutting optical system 14 directs the laser pulse LP1 cut out from the laser pulse LP0 to one machining path, and directs the laser pulse LP2 to the other machining path. A folding mirror 16, a scanning optical system 17, a lens 19, a stage 30, and a moving mechanism 31 are arranged on each of the two processing paths.

A route selection command sel is input from the laser control device 40 to the cutting optical system 14 in addition to the cutting command chp. A path selection command sel instructs a machining path to be selected from two machining paths. The cutting optical system 14 cuts out laser pulses toward the instructed machining path.

FIG. 8 is a timing chart of the oscillation command trg, laser pulse LP0, path selection command sel, cutting command chp, and laser pulses LP1 and LP2. As in the embodiment shown in FIG. 4A, the laser pulse LP0 rises at the time (time t2) after the pulse output delay time td has elapsed from the rise of the oscillation command trg (time t0). The laser control device 40 outputs the first clipping command chp at the time when the clipping command delay time tdc has passed since the rise of the oscillation command trg (time t1). At this time, the path selection command sel selects the path of the laser pulse LP1. Therefore, the laser pulse LP1 is extracted from the laser pulse LP0 at the time (time t3) when the operation delay time tdo has passed since the first extraction command chp was output.

After the laser pulse LP1 falls (time t5), the laser control device 40 switches the path selection command sel to select the machining path of the laser pulse LP2 (time t6). Further, a second cutting command chp is output (time t7). At the point in time (time t8) when the operation delay time tdo has passed since the output of the second extraction command chp, the laser pulse LP2 is extracted from the laser pulse LP0. After the laser pulse LP2 falls (time t10), the output of the oscillation command trg is stopped (time t11). Further, the path selection command sel is switched to select the path of the laser pulse LP1 (time t12).

Next, the excellent effects of the embodiment shown in FIGS. 7 and 8 will be described. Also in this embodiment, since the first cutting command chp is output before the rise of the laser pulse LP1, it is possible to reduce the wasted laser energy and improve the utilization efficiency of the laser pulse LP0.

It goes without saying that each of the above-described embodiments is an example, and partial substitutions or combinations of configurations shown in different embodiments are possible. Similar actions and effects due to similar configurations of multiple embodiments will not be sequentially referred to for each embodiment. Furthermore, the invention is not limited to the embodiments described above. For example, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

10 Laser oscillator 11 Beam splitter 12 Irradiation optical system 13 Aperture 14 Extraction optical system 15 Beam damper 16 Folding mirror 17 Scanning optical system 18X Movable mirror 18Y Movable mirror 19 Lens 20 Photodetector 30 Stage 31 Moving mechanism 40 Laser controller 41 Storage unit 50 Input device 60 Workpiece trg Oscillation command chp Extraction command det Detection signal sel Path selection command sig1, sig2 Control signal

Claims (4)

a laser oscillator that outputs a pulsed laser beam;
a cutting optical system having a characteristic of starting to cut out a part of the laser pulse of the pulsed laser beam when a certain operation delay time has passed after the pulsed laser beam is incident and a cutting command is input; A laser control device for controlling
The cutting command is output to the cutting optical system at a time before the rising time of the laser pulse, and the time when the operation delay time elapses from the time when the cutting command is output is the time when the laser pulse rises. A laser control device for outputting the cut-out command so as to be after the rise time. The laser oscillator outputs the laser pulse in synchronization with an input of an oscillation command,
moreover,
outputting the oscillation command to the laser oscillator;
storing relational information that associates at least one of the pulse repetition frequency and pulse width commanded by the oscillation command with the pulse output delay time;
Based on the pulse output delay time and the operation delay time obtained from at least one of the pulse repetition frequency and the pulse width commanded by the oscillation command and the relationship information, the pulse output delay time is shorter than the pulse output delay time and the determining the cutting command delay time to be longer than the value obtained by subtracting the operation delay time from the pulse output delay time;
2. The laser control device according to claim 1, wherein the cut-out command is output to the cut-out optical system with a delay from the output time point of the oscillation command based on the determined cut-out command delay time. moreover,
receiving a detection signal from a photodetector that detects the laser pulse output from the laser oscillator;
measuring the delay time from the output of the oscillation command to the input of the detection signal, obtaining the pulse output delay time based on the measured value of the delay time;
3. The apparatus according to claim 2, wherein the relationship between at least one of the repetition frequency and pulse width of the pulse instructed by the oscillation command and the pulse output delay time obtained based on the measured value of the delay time is stored as the relationship information. A laser controller as described. A laser pulse cutting method for outputting a laser pulse from a laser oscillator and making it enter a cutting optical system to cut out a part of the laser pulse,
The extraction optical system has a characteristic of starting extraction of a part of the laser pulse after a certain operation delay time has passed since the extraction command is input,
The cutout command is output to the cutout optical system at a time before the rise of the laser pulse, and the rise of the laser pulse is reached at the time when the operation delay time has elapsed from the time when the cutout command was output. A laser pulse cutting method for outputting the cutting command so as to be later than the point in time.

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