JPH10193152A - Laser processing equipment - Google Patents

Abstract

(57) [Problem] To prevent erroneous laser processing from being performed on the basis of variations in processing positions and melted and scattered substances adhering to the surface or side surface of a workpiece due to laser processing. I do. A laser beam oscillation is controlled at a timing corresponding to the number of pulses of a movement amount signal M from an encoder 21a attached to an XY table 21. The light source 12 for detection
The presence / absence of a workpiece is detected by using the detection light from 2 and a corresponding detection signal P1 is generated. Then, the comparison / timing circuit 242 determines whether or not the rising interval of the P1 falls within a range in which an error is added to the time corresponding to the predetermined number of pulses of the movement amount signal M, and the following is determined according to the result. Control of the count start timing of the movement amount signal M, which is the basis for generating the laser cutting trigger of the dam bar.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus capable of processing a desired processing position at a high speed.
In particular, the present invention relates to a laser processing apparatus suitable for cutting and removing a dam bar of a semiconductor device.

[0002]

2. Description of the Related Art Processing using pulsed laser light includes processing methods such as cutting, drilling, and welding.
It is used in manufacturing processes in various fields such as semiconductor devices. Among them, as a prior art relating to a laser processing apparatus or a laser processing method suitable for cutting and removing a dam bar of a semiconductor device, there are those described in JP-A-5-277765 and JP-A-6-142968.

In the prior art described in Japanese Patent Application Laid-Open No. Hei 5-277765 (hereinafter referred to as a first prior art), the amount of movement of a processing table is measured, and the amount of movement of the processing table and the oscillation of pulsed laser light are measured. Are synchronized in consideration of the time required for laser light oscillation, and thereby a target processing position (in this case, a dam bar of a semiconductor device) is irradiated with laser light to perform processing. Here, the position of the dam bar to be removed is registered in advance in the main controller or the like as a program.

The prior art described in Japanese Patent Application Laid-Open No. 6-142968 (hereinafter referred to as a second prior art) is a detection optical system (light detecting means) arranged substantially coaxially with the optical axis of a processing optical system. In the above, the presence or absence of material in the workpiece, that is, the arrangement of the leads near the dam bar is optically detected based on the switching between light and dark, the detection signal is rectangularized, and the rectangular signal is further delayed by a predetermined delay. This is to control the oscillation of the pulse laser light based on the signal given the time and the delay time. That is, when the dam bar of the semiconductor device is cut by this method, the arrangement state of the leads is directly visually detected, and the irradiation of the pulse laser light is immediately performed using the data. Accordingly, the dam bars are sequentially cut only by moving the optical axis of the laser beam (hereinafter, referred to as the laser optical axis) with respect to the workpiece, and the processing can be performed reliably and at high speed.

[0005]

According to the first prior art, in order to synchronize the amount of movement of the processing table with the oscillation of the pulsed laser light in consideration of the time required for the laser light oscillation, a target The laser beam can be irradiated at a high speed and reliably to the processing position to be processed. In semiconductor devices, pins (leads) are generally at equal pitches, but are often deformed due to lead frame manufacturing errors, distortion due to temperature history when molding with resin, external force due to handling, and other causes. When cutting and removing the dam bar, the pitch is often not always equal. Actually, the pitch variation between adjacent leads is about several μm,
Since several tens of leads are arranged on each side of the package, the total displacement of the leads is several hundred μm. In the first prior art, the position of the dam bar to be removed is registered in advance, but such a method cannot cope with the fact that the leads are not at the same pitch as described above. In the worst case where manufacturing errors and deformations accumulate and the errors increase, there is even a possibility of damaging a part of the lead frame to be left.

On the other hand, according to the second prior art, a desired processing position can be processed at high speed not only when the processing positions are at equal intervals but also when they are not at equal intervals. Can be handled to some extent even if the pitches are not equal pitch but are irregularly arranged. However, during the laser processing, the molten scattered matter (spatter) generated by the laser processing adheres to the lead surface and the side surface thereof. The reflected light of the detection light is scattered, the amount of light reflected from the lead decreases, and it is erroneously recognized that the detection position has passed through the edge of the lead (entered a slit where no lead exists). There is a possibility that pulse laser light for processing is erroneously irradiated based on the detected light thus detected. In other words, the level of the detection signal that has changed due to the molten deposit is generated as a square wave signal (binarization).
There is no problem if the threshold level is higher than the threshold level, but if the threshold level is lower than the threshold level, the output rectangular wave signal is not only on the edge of the lead, but also on the surface and side of the lead. Since it is also generated (erroneously detected) in synchronism with the adhered molten and scattered matter, the pulse laser light is also oscillated (erroneously oscillated) by the erroneously detected rectangular wave signal. This erroneous oscillation causes a problem that erroneous irradiation is performed on an erroneous position other than the predetermined laser processing position and laser processing is performed. Further, there is a possibility that the detection light is reflected by the molten scattered matter attached to the side surface of the lead portion, and a laser beam is erroneously irradiated with reference to a position other than the lead portion.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-speed processing of a desired processing position where a workpiece exists, not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals. By providing a laser processing apparatus capable of preventing erroneous laser processing from being performed on the basis of variations in (for example, lead pitch) and melted and scattered substances adhering to the surface or side surface of a workpiece due to laser processing. is there.

[0008]

According to the present invention, there is provided a laser oscillator for oscillating a pulsed laser beam, and a processing optic for guiding the laser beam to a processing position of a workpiece. System, transport means for moving the workpiece, travel distance detecting means for detecting the travel distance of the transport means and generating a travel signal according to the travel distance, and counting the travel signal and counting the count value Trigger signal generating means for generating a trigger signal in response to the control signal, and control means for controlling the oscillation of the laser light so that a predetermined processing position of the workpiece is irradiated with the laser light at a timing based on the trigger signal. In a laser processing apparatus that processes a workpiece by the laser light, a detection light generating unit that irradiates a detection light to the vicinity of the processing position, and determines whether the workpiece is present based on reflected light of the detection light. Detecting means for generating a corresponding detection signal and generating a corresponding detection signal; and a waveform cycle comparing means for comparing whether the waveform cycle of the detection signal falls within a range obtained by adding a preset error width to the waveform cycle of the trigger signal. And a trigger signal timing control means for controlling the counting start timing of the movement signal in accordance with the result of the comparison by the waveform cycle comparing means.

In the present invention configured as described above, basically, the movement signal generated by the movement amount detecting means is counted, and a trigger signal is generated by the trigger signal generating means in accordance with the counted value. The control means controls the oscillation of the laser light at a timing based on the trigger signal so that a predetermined processing position of the workpiece is irradiated with the laser light.
For example, when cutting a dam bar of a semiconductor device, the cycle determined by the lead pitch and the feed speed of the transfer means and the cycle of the trigger signal should be set to be the same. However, in practice, variations occur in the lead pitch as described above, or molten scattered matter adheres,
According to the present invention, the period of the trigger signal that fluctuates due to the change can be changed as follows.

First, detection light is radiated from the detection light generation means to the vicinity of the processing position, and the detection means detects the presence or absence of a workpiece near the processing position based on the reflected light of the detection light, and generates a corresponding detection signal. generate. Then, the waveform cycle comparing means compares whether or not the waveform cycle of the detection signal falls within a range obtained by adding a preset error width to the waveform cycle of the trigger signal. Timing control means controls the count start timing of the movement signal. In other words, if the waveform period of the detection signal falls within the above range, it is determined that there is no adhesion of the molten scattered matter on the lead surface or side surface, and the counting start timing of the movement signal is determined according to the period of the detection signal. Then, the oscillation timing of the trigger signal is corrected, and a predetermined processing position of the workpiece is irradiated with laser light at a timing based on the trigger signal.

As described above, by correcting the oscillation timing of the trigger signal based on the amount of movement of the transporting means on the basis of the detection signal, even if there is a variation in the position to be processed such as the lead pitch, it is appropriate. It is possible to irradiate a laser beam to a proper position, and it is also possible to avoid accumulating the variation error.

If the waveform period of the detection signal does not fall within a range obtained by adding a preset error width to the waveform period of the trigger signal, the waveform period comparing means may melt the lead surface or side surface. It is determined that there is an attached matter such as a flying matter. In this case, since the detection signal itself is incorrect, the correction based on the detection signal is not performed, and the laser is moved to a predetermined processing position of the workpiece at the timing based on the trigger signal based on the movement amount of the transporting means. Irradiate light. As a result, when melted splatters adhere to the surface or side surface of a workpiece such as a lead, there is a problem that the oscillation timing of a trigger signal is controlled in accordance with an erroneous detection signal caused by the melted splatters. The laser beam is prevented from being erroneously irradiated.

Therefore, according to the present invention, not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals, it is possible not only to process the desired processing position where the workpiece exists but also at high speed. Incorrect laser processing is performed based on the variation in the position to be processed, for example, the lead pitch variation is accumulated and the lead to be cut is cut off, or the workpiece surface or It is possible to prevent erroneous laser processing from being performed based on the melted and scattered substances adhering to the side surface, for example, irradiating a lead portion to be left with laser light.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. However, in the following,
The removal of the dam bar of an IC package having pins at equal intervals will be mainly described.

As shown in FIG. 1, a laser processing apparatus according to the present embodiment is provided with a laser oscillator 10 composed of a laser head 11, a processing head 12, and a laser power supply 13, and a work (IC package) 1, which is mounted on a horizontal plane. Inside (within XY plane)
And a control unit 25 having a main controller 23 and a trigger unit 24. The XY table 21 is a transport unit for moving the laser head 11 and the processing head 12 in the vertical direction (Z-axis direction). . The main controller 23
Movement of XY table 21 in horizontal plane and Z table 2
2 to automatically or manually control the vertical movement operation and the oscillation operation of the laser oscillator 10.

The laser power supply 13 comprises a stabilized power supply 130, a capacitor section 131, a switch section 132, and a laser controller 26. An alternating current is supplied to the laser power supply 13 from an alternating current power supply 133, and the alternating current is converted to a direct current by the stabilized power supply 130 in accordance with a voltage value commanded by the laser controller 26, and supplied to the capacitor unit 131. The charge supplied to the capacitor unit 131 at the above voltage value is supplied to the switch unit 132,
The switch unit 132 operates in accordance with a trigger signal for instructing the pulse width and pulse frequency of the pulsed laser light input from the laser controller 26, and the electric charge is stored in the laser excitation flash lamp 1 provided in the laser head 11.
11 is supplied. The flash lamp 111 emits light due to the pulsed electric charge, thereby exciting the oscillation medium and pulsating the pulsed laser light.

The laser head 11 shown in FIG. 1 has a built-in beam shutter 112. The beam shutter 112 turns ON / OFF the pulse laser light emitted from the laser oscillator 10 by opening and closing,
The irradiation of the pulse laser beam to the work 1 is controlled. That is, when processing the work 1, the beam shutter 112 is used.
To open the beam shutter 11
Close 2. The operation time of the beam shutter 112 is about 100 to 300 msec. Further, the ON / OFF control of the beam shutter 112 is performed by the laser controller 26, but can be performed by the main controller 23 via the laser controller 26.

The processing head 12 is provided with a detection light generator 126 (see FIG. 4), which will be described later, and a photosensor 125 as detection means. A detection signal from the photosensor 125 is input to the trigger unit 24,
Outputs a trigger signal P to a laser controller 26 (described later) in the laser power supply 13 in response to a command from the main controller 23. On the other hand, a rotary encoder (hereinafter, simply referred to as an encoder) 21a as a moving amount detecting means is attached to the XY table 21, and a moving amount signal (pulse signal) M corresponding to the moving amount of the XY table 21 from the encoder 21a. Is input to the comparison / timing circuit 242 of the trigger unit 24 (see FIG. 2).
However, the movement amount signal M is a signal corresponding to the movement amount of the XY table 21, and is not affected by the movement speed.

As shown in FIG. 2, the trigger unit 24 includes a comparator 241 constituted by an operational amplifier as a binarizing means, and a comparator / comparison as a waveform period comparing means.
A timing control circuit 242 and a delay circuit 243 are provided.

Further, as shown in FIG. 3, the laser controller 26 includes an input / output unit 260, a central processing unit 261,
A trigger circuit 262 is provided. Trigger circuit 262
Is transmitted from the main controller 23 to the central processing unit 2 in synchronization with the rise of the trigger signal P from the trigger unit 24.
A trigger signal T having a pulse width designated by 61 is generated, and this trigger signal T is input to the switch unit 132. The voltage value of the electric charge supplied to the capacitor unit 131 is
The data is input from the input / output unit 260 to the central processing unit 261, and the central processing unit 261 instructs the stabilized power supply 130. Thereafter, the laser light oscillates according to the above-described process.

Further, as shown in FIG.
2, a bending mirror 120 having a high reflectance characteristic with respect to the wavelength of the pulse laser light, and a condensing lens 121 for condensing the pulse laser light are provided. The same is true. In the present embodiment, in addition to the above configuration, a detection light source 122, a dichroic mirror 123, an imaging lens 124, a target 125a, and a photosensor 125 are added. Among them, the photo sensor 125 is attached to an opening formed in the target 125a. Of the above,
The detection light source 122, the dichroic mirror 123, and the imaging lens 124 constitute a detection light generator 126.

The basic functions of the processing head 12 will be described below. First, a beam of pulsed laser light output from the laser head 11 is
At 0, the direction is changed, and the light is condensed by the condenser lens 121 and irradiated onto the work 1. The light emitted from the light source 122 for detection is changed in direction by the dichroic mirror 123, passes through the bending mirror 120, and
The light is condensed at 21 and becomes detection light near the laser processing portion on the work 1. The light reflected on the surface of the work 1 passes through the bending mirror 120 and the dichroic mirror 123, is collected by the imaging lens 124, and
This corresponds to 25a. Part of the reflected light hitting the target 125a is input to the photo sensor 125 through the opening.

At this time, if the image on the surface of the work 1 is formed at the position of the photo sensor 125 by combining the condenser lens 121 and the imaging lens 124,
An image on the work 1 is stopped down by the imaging lens 124 and formed at the position of the target 125a, for example, as shown in FIG.

In FIG. 5, the dam bar 2 connecting adjacent leads and the vicinity thereof are imaged, and the slits on the resin mold 6 side among the portions 3 and 4 where no leads exist (hereinafter referred to as slit portions) are shown. Only the part 4 is filled with the resin at the time of molding the IC package. However, the center line of the dam bar 2 is located on the center line of the image, the X axis and the Y axis are determined as shown in the figure, and detection and processing are performed while scanning in the X axis direction. Further, a part of the light of this image is detected by the photo sensor 125, and an opening 125b is provided at a position indicated by a hatched portion in the figure, and the photo sensor 125 is installed in the opening 125b. Opening 125b
Is a position slightly displaced from the center line of the image to the opposite side of the resin mold 6 and a position displaced from the center of the image by a distance L in the positive direction of the X-axis.

In the above state, the opening 125b is moved in the positive direction of the X axis (that is, the work 1 is moved in the negative direction of the X axis).
Is moved), the photo sensor 125 can detect the presence or absence of the lead portion 5, that is, the portion where the lead 5 exists and the slit portion 3 based on brightness.

The operation of the laser processing apparatus having the above configuration will be described. First, a work 1 having a shape as shown in FIG.
(The lead frame of the IC package including the dam bars 2a, 2b, 2c, 2d,...) Is moved by the XY table 21 at a constant speed v in the negative direction of the X axis, for example.
An image formed on the target 125a by reflected light from the work 1 moves in the positive direction of the X axis. However,
The photo sensor 125 is connected to the opening 12 of the target 125a.
5b, the change in the detection signal, which is the output from the photosensor 125, is high at the lead 5 and low at the slit 3, as shown in FIG. However, the detection signal here is assumed to have a high output when the light is strong and a low output when the light is weak. Also,
If the lead portion 5 and the slit portion 3 of the work 1 are arranged at a constant pitch, the detection signal is output as a waveform of a fixed period by moving the XY table 21 at a constant speed. Are not arranged at the same pitch, the detection signal is detected as a waveform having a time change proportional to the change in pitch.

Next, the waveform of the detection signal detected as described above is input to the comparator 241 of the trigger unit 24 and binarized. That is, the detection signal input from the photo sensor 125 to the comparator 241 is binarized based on a predetermined threshold indicated by a broken line S in FIG.
2 is input.

Next, the comparison timing control circuit 242 and the subsequent processing will be described with reference to the dam bars 2a to 2a shown in FIG.
A description will be given with reference to FIG. First, the first
For the disconnection of the dam bar 2a, the comparator 241
A signal P2 is generated at the timing of the first rising edge R1 of the output P1 from the controller, a delay time tD commanded by the May controller 23 is given by the delay circuit 243, and the delay time tD is input to the laser controller 26 as the trigger signal P, as described above. Pulsed laser light is oscillated by a simple process. That is, after a predetermined delay time tD from R1, pulsed laser light oscillation is performed, and the first dam bar 2a is cut. Further, the comparison / timing control circuit 242 starts measuring the time CSP1 until the second rising R2 of the output P1 from the comparator 241. Further, the counting is started from the pulse of the movement amount signal M from the encoder 21a immediately after the first rising R1 of the output P1 from the comparator 241, and the pulse number TEP corresponding to the distance of the preset lead pitch (based on the design value) is set. Is counted, the next signal P2 is generated, a delay time tD is given by the delay circuit 243, and the signal is input to the laser controller 26 as the trigger signal P, and the pulsed laser light is oscillated by the process described above.
Thereby, the second dam bar 2b is cut. Further, the comparison / timing control circuit 242 starts measuring the time CSP2 until the third rising R3 of the output P1 from the comparator 241.

Here, the time required to count the distance of a preset lead pitch (based on a design value) is defined as EPP1, and a time error e caused by a shift in the lead pitch is added to or subtracted from the time EPP1. , Within its range (EP
Compare whether CSP1 is within P1 ± e)
The determination is made by the timing control circuit 242. As a result, if the CSP1 is within the above range, it is determined that there is no adhesion of the melted scattered matter on the surface or the side surface of the lead portion 5, and the pulse of the movement amount signal M immediately after the second rising R2 of P1. Start counting.

When the number of pulses of the movement amount signal M has counted the number of pulses TEP corresponding to the distance of the preset lead pitch (based on the design value), the next signal P2
Is generated, a delay time tD is given by the delay circuit 243, and the delay time tD is input to the laser controller 26 as the trigger signal P, and a pulsed laser beam is oscillated by the process described above. Thereby, the third dam bar 2c is cut. In the same manner as described above, measurement of the time CSP3 until the fourth rise R4 of the output P1 from the comparator 241 is started in the comparison / timing control circuit 242.

However, on the lead surface near the third dam bar 2c, a molten scattered material 100a as shown in FIG.
In the case where (shown by oblique lines in the figure) has adhered, as shown in FIG. 8, the output P1 from the comparator 241 changes, and the third rising edge R3 becomes R3 *, and C3
SP2 will be longer than the design value. This is because the light emitted from the detection light source 122 to the work 1 is largely reflected on the relatively flat surface.
In the place where the molten scattered matter 100a shown in (a) is attached to the lead portion 5, the reflected light is irregularly reflected or the reflected light proceeds to a place outside the aperture of the condenser lens 121, and the photo sensor 12
This is because the amount of light entering 5 decreases. In this case, the CSP2 does not fall within the range (EPP2 ± e) in which the time error e is added to the time EPP2 required to count the distance of the preset lead pitch (based on the design value). . Thus, CSP2 within the above range
When the comparison / timing control circuit 242 determines that is not within the range, the third rising R3 of P1 is incorrect, so this R3 is not used, and the moving amount used for cutting the third dam bar 2c is not used. At the same time when the pulse number TEP of the signal M is counted up, the pulse number counting of the next movement amount signal M is started.

Then, the pulse number of the movement amount signal M is
When the number of pulses TEP corresponding to the distance of the preset lead pitch (based on the design value) is counted, the next signal P2 is generated, a delay time tD is given by the delay circuit 243, and the trigger signal P is given to the laser controller 26. The laser beam is input and pulsed laser light is oscillated by the process described above. Thereby, the fourth dam bar 2d is cut. Further, measurement of the time CSP4 until the next rise R4 of the output P1 from the comparator 241 is started in the comparison / timing control circuit 242.

However, FIG. 6 shows the vicinity of the fourth dam bar 2d.
In the case where the molten scattered matter is not attached as in (a),
The output P1 (R4) from the comparator 241 shown in FIG.
Does not change like R3 *. Therefore, the CSP3 from the third rising R3 * to the fourth rising R4
Will be shorter. In this case, the CSP
3, the CSP3 * calculated by the following formula, for example, CSP3 * = (CSP2 + CSP3) / 2... The comparison / timing control circuit 242 determines whether the time is within the range in which the time error e is taken into account. Based on this determination, the movement amount signal M
Start counting the number of pulses. Hereinafter, the dam bar after the fifth is sequentially cut through the same procedure. Although the rising intervals of the past two P1s are averaged in Expression (1), an average of the past three or more P1s may be taken.

According to the present embodiment as described above,
In the timing circuit 242, the rising interval of the output P1 from the comparator 241 is within a range (EPP1 ± e, etc.) in which an error is added to the time taken to count the distance of the preset lead pitch (based on the design value). (CSP1, CSP2,...) Are compared and determined, and according to the result, the dam bars 2a, 2
Since the count (pulse number TEP) start timing of the movement amount signal M that triggers the laser cutting of b,... is controlled, it is possible to irradiate the laser beam to an appropriate position even if the lead pitch varies. In addition, accumulation of the variation error is avoided, and furthermore, even when the melted scattered matter 100a or the like adheres to the surface or side surface of the lead portion 5, the laser beam is prevented from being erroneously irradiated due to the adhesion. Is done.

[0035]

According to the present invention, the waveform cycle comparing means compares and determines whether or not the waveform cycle of the detection signal falls within a range obtained by adding a preset error width to the waveform cycle of the trigger signal. Since the counting start timing of the movement signal is controlled in accordance with the result, even if the position to be processed (for example, the lead pitch) varies, it is possible to irradiate the laser beam to an appropriate position, and furthermore, the variation error Is prevented from accumulating, and even if the melted or scattered material adheres to the surface or side surface of the work piece (for example, the lead portion), the laser light is prevented from being erroneously irradiated due to this. Is done.

Therefore, according to the present invention, not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals, it is possible not only to process the desired processing position where the workpiece exists but also at high speed. Incorrect laser processing is performed based on the variation in the position to be processed, for example, the lead pitch variation is accumulated and the lead to be cut is cut off, or the workpiece surface or It is possible to prevent erroneous laser processing from being performed based on the melted and scattered substances adhering to the side surface, for example, irradiating a lead portion to be left with laser light.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser processing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a trigger unit in the laser processing apparatus of FIG. 1;

FIG. 3 is a diagram illustrating a configuration of a laser controller in the laser processing apparatus of FIG. 1;

FIG. 4 is a schematic diagram of a configuration inside a processing head in the laser processing apparatus of FIG. 1;

FIG. 5 is a diagram illustrating an example of an image formed at a position of a target in FIG. 4;

6A and 6B are diagrams for explaining a detection signal from the photo sensor of FIG. 4, wherein FIG. 6A is a diagram showing a lead frame shape of an IC package, and FIG. 6B is a detection signal as an output from the photo sensor; FIG. 6 is a diagram after binarizing.

FIG. 7: The detection signal is binarized by a comparator,
FIG. 4 is a diagram illustrating a situation output to a timing control circuit.

FIG. 8 is a diagram illustrating a comparison timing control circuit and subsequent processing.

[Description of Signs] 1 Work (IC package) 2 Dam bar 2a First dam bar 2b Second dam bar 2c Third dam bar 2d Fourth dam bar 3,4 Slit part 5 Lead part 6 Resin mold 10 Laser oscillator 11 Laser head Reference Signs List 12 processing head 13 laser power supply 21 XY table 21a (rotary) encoder 22 Z table 23 main controller 24 trigger unit 25 control unit 26 laser controller 120 bending mirror 121 condensing lens 122 light source for detection 123 dichroic mirror 124 imaging lens 125 photo Sensor 125a Target 125b Opening 126 Detected light generator 130 Stabilized power supply 131 Capacitor section 132 Switch section 133 AC power supply 241 Comparator ( Digitizing means) 242 compares timing control circuit 243 delay circuits

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshiaki Shimomura 650, Kandamachi, Tsuchiura-shi, Ibaraki Pref.Hitachi Construction Machinery Co., Ltd. (72) Inventor Shigeyuki Sakurai 650, Kandamachi, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Inside the Tsuchiura Plant of Shikisha Company (72) Inventor Tsuyoshi Nishigaki 650 Kandamachi, Tsuchiura City, Ibaraki Prefecture Hitachi Construction Machinery Co., Ltd. Inside the Tsuchiura Plant of Shikisha Company (72) Yasushi Minomoto 650 Kamikachicho, Tsuchiura City, Ibaraki Prefecture Ring Co., Ltd.

Claims (1)

[Claims] A laser oscillator that oscillates pulsed laser light; a processing optical system that guides the laser light to a processing position of the workpiece; a transport unit that moves the workpiece; Moving amount detecting means for detecting a moving amount and generating a moving signal according to the moving amount; trigger signal generating means for counting the moving signal and generating a trigger signal according to the counted value; Control means for suppressing oscillation of the laser light so that a predetermined processing position of the workpiece is irradiated with the laser light at a timing based on the laser light, wherein the laser processing apparatus processes the workpiece with the laser light. Detection light generating means for irradiating detection light near the processing position; detection means for detecting presence or absence of the workpiece based on reflected light of the detection light and generating a corresponding detection signal; A waveform cycle comparing means for comparing whether or not the waveform cycle of the detection signal falls within a range obtained by adding the determined error width to the waveform cycle of the trigger signal, and according to a comparison result by the waveform cycle comparing means. And a trigger signal timing control means for controlling a timing to start counting the movement signal.