JP6048124B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus that detects the position of a processing object by detecting an edge (outer shape) using image analysis.

As a general laser processing apparatus, one that performs edge detection by image analysis is known.
For example, Patent Document 1 describes that an edge position (an outer shape position of an object to be processed) is detected by irradiating illumination light from a plurality of directions to correct a position shift of the object to be measured (substrate).
Japanese Patent Application Laid-Open No. 2004-26883 also discloses that the outer shape of the object to be measured is detected on the basis of an image captured by performing illumination with a backlight from behind the object to be measured.
Furthermore, Patent Document 3 describes that image measurement of a reference sphere is performed in a state where a reflector is provided behind a calibration jig (reference sphere). In this case, the illumination light from above the reference sphere is scattered by the reflector disposed behind, so that the edge of the reference sphere can be clearly identified. Therefore, it is described that the offset position can be accurately calculated.

Japanese Patent No. 3795820 Japanese Patent No. 431474 Japanese Patent No. 4791118

However, when performing edge detection by image analysis, it is difficult to accurately determine the edge due to the wrapping of illumination light, and it is difficult to accurately detect the position of the workpiece.
Further, when a backlight as shown in Patent Document 2 is applied to, for example, a laser processing apparatus, there is a risk of damaging the backlight when observing at a processing position, and observation is performed at a position other than the processing position. In this case, it is necessary to confirm the exact relative position between the processing position and the observation position, and workability is reduced.
Further, even when a reflector is provided as in Patent Document 3, it is necessary to dispose the reflector close to the object to be processed in order to avoid the wraparound of illumination light. In addition, when a reflector is disposed behind the object to be processed, the reflector may become dirty or the reflector may be damaged when the object to be processed is processed. In this case, since the reflectance of the illumination light by the reflecting plate is reduced, the brightness difference (contrast) of the obtained image becomes small, and the determination of the edge position of the processing object may become unstable. For this reason, it becomes impossible to grasp | ascertain the position of a process target object correctly, and it may lead to the fall of the process precision of a process target object.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a laser processing apparatus capable of detecting the position of a processing object with high accuracy in edge detection by image analysis.

The present invention detects the position of a workpiece by laser irradiation means for irradiating a workpiece with a laser beam, stage means movable while holding the workpiece, and edge detection using image analysis. A laser processing apparatus including an edge detection unit, wherein the edge detection unit includes an imaging unit for capturing an image, an illumination unit that illuminates an imaging range of the imaging unit, and an object to be processed between the imaging unit. A reflecting plate that is disposed in a state of interposing, reflecting the illumination light of the illuminating means and irradiating the object to be processed from behind, and a reflecting surface cleaning capable of arranging the surface of the reflecting plate in the imaging range on a new surface and mechanism, and an image processing means for detecting an edge position of the workpiece from an image obtained by the imaging means, the reflecting surface cleaning mechanism, by moving the reflecting plate It has the serial fresh surface is constituted by a moving mechanism arranged in the imaging range of the imaging unit, characterized in Rukoto.

  In the laser processing apparatus of the present invention, the reflectance of the illumination light by the reflector can be maintained by replacing the surface portion on which the dirt or the like of the reflector is attached by the reflecting surface cleaning mechanism, and the image is captured. It is possible to prevent the luminance of the part other than the processed object of the image from being lowered. As a result, a high-contrast image can be obtained, and the position of the processing object can be detected with high accuracy.

In this case, the surface portion contamination of the reflector is attached retracts moved from the imaging range, by arranging a new surface dirt do not adhere to the imaging range, to maintain the reflectance of illumination light by the reflection plate Can do.
The reflecting surface cleaning mechanism can also be configured by a cleaning mechanism that wipes off dirt adhering to the reflecting plate.

  The laser processing apparatus of the present invention is provided with alignment mark drawing means for forming an alignment mark on the reflector for each alignment adjustment, and the position of the latest alignment mark formed by the alignment mark drawing means and the image processing The processing position of the processing object is calculated based on the edge position of the processing object detected by the means.

  Since the alignment mark is configured to be engraved directly on the reflector itself every alignment adjustment, even if the reflector is moved, a new alignment mark can be formed on the surface of the reflector after movement. The alignment mark serving as a measurement reference is always arranged at the same position. Therefore, the position of the alignment mark serving as a measurement reference can be corrected with high accuracy for each adjustment.

Further, the alignment mark drawing unit may be configured to form the alignment mark by the laser irradiation unit.
In this case, the alignment mark is disposed immediately below the irradiation position of the laser beam. For this reason, since the alignment mark formation position and the laser beam irradiation position are always arranged at the same position, correcting the alignment mark position with high accuracy will correct the laser processing position with high accuracy. By calculating the relative position between the alignment mark and the edge position, high-accuracy machining can be performed.

  According to the present invention, it is possible to detect the position of a workpiece with high accuracy in edge detection by image analysis.

It is a whole lineblock diagram showing the laser processing device concerning the present invention. It is a schematic diagram explaining the moving mechanism of a reflecting plate, (a) is a side view, (b) is a top view. It is a schematic diagram explaining the cleaning mechanism of a reflecting plate, (a) is a side view, (b) is a top view. The microscope image of an alignment mark is shown. It is a figure explaining the result of the edge determination performed using the reflecting plate, (a) is the image | photographed image before image processing, (b) detects the edge by binarizing the image of (a) (C) is an image showing the second result of binarizing the image of (a) and detecting an edge. It is a figure explaining the result of the edge determination performed without using a reflecting plate, (a) is a photographed image before image processing, (b) is an image obtained by binarizing the image of (a). An image showing the detected first result, and (c) is an image showing the second result of binarizing the image of (a) and detecting the edge. It is a whole block diagram which shows other embodiment of the laser processing apparatus which concerns on this invention.

Hereinafter, an embodiment of a laser processing apparatus according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the laser processing apparatus 100 according to the present embodiment is an apparatus that processes a workpiece w by irradiating the workpiece w with a laser beam L, and laser irradiation means 1 that irradiates the workpiece w with the laser beam L. A stage unit 2 that is movable while holding the processing object w, an edge detection unit 3 that detects the position of the processing object w by edge detection using image analysis, and a control unit 4 that controls these. Is provided.

The laser irradiation means 1 includes, for example, a laser light source 11 that oscillates a laser beam L at a constant repetition frequency, a beam adjustment unit 12 that adjusts the spread of the laser beam L, and a condensing beam that condenses the laser beam L in a spot shape. The lens 13 is provided, and the workpiece w is irradiated with the laser beam L through the mirrors m1 to m3.
As the laser light source 11, a light source capable of irradiating laser light with a wavelength of 190 nm to 1100 nm can be used. For example, in this embodiment, a laser light source that can oscillate and emit laser light with a wavelength of 355 nm is used.

  The stage means 2 has a mechanism that can translate the workpiece w in each direction of xyz. Specifically, an x-axis stage unit 21x that can move in the x direction parallel to the horizontal plane and a y axis direction that is provided below the x-axis stage unit 21x and is perpendicular to the x direction and parallel to the horizontal plane. A possible y-axis stage unit 21y and a z-axis stage unit 21z provided below the y-axis stage unit 21y and movable in a direction perpendicular to the horizontal plane are provided. Moreover, the stage control part 22 which controls these stage parts 21x-21z is provided.

  The edge detection unit 3 is arranged in a state in which the processing object w is interposed between the imaging unit 31 for image capturing, the illumination unit 32 for illuminating the imaging range A of the imaging unit 31, and the imaging unit 31. A reflecting plate 33 that reflects the illumination light S and irradiates the workpiece w from behind, a moving mechanism 34 that moves the reflecting plate 33 in the horizontal direction, and a cleaning mechanism 35 that wipes off dirt on the surface of the reflecting plate 33. And image processing means 36 for detecting the edge position of the processing object w from the image obtained by the imaging means 31.

For the imaging means 31, an imaging device such as a CCD camera can be used. The imaging unit 31 is provided above the workpiece w and the reflector 33. Further, the imaging range of the imaging means 31 is set to a part of the reflector 33 as indicated by reference numeral A in FIGS. 2B and 3B. Further, the imaging focus position of the imaging means 31 and the processing focus position of the laser beam L are provided so as to coincide with each other.
A light source such as a halogen lamp or LED illumination can be used as the illumination unit 32 that illuminates the imaging range A of the imaging unit 31. The illuminating means 32 is configured to illuminate the processing object w from the coaxial direction with the irradiation direction of the laser beam L via the mirror m4, and the laser beam L and the illumination light. The irradiation direction of S and the shooting direction of the imaging means 31 are provided so as to coincide.

  The reflection plate 33 is formed of glass, plastic film, ceramics, or the like, and is fixed on the moving mechanism 34. Further, the surface of the reflection plate 33 is finished so as to regularly reflect the illumination light S, and the illumination light S can be irradiated from behind the workpiece w.

  The moving mechanism 34 rearranges the surface of the reflecting plate 33 in the imaging range A of the imaging means 31 on the new surface. For example, as shown by an arrow θ1 in FIG. 2B, a stage that rotates and moves the reflecting plate 33. Can be configured. Further, as shown by arrows X1 and Y1 in FIG. 3B, the reflecting plate 33 can be configured by a stage that horizontally moves in the x direction and the y direction.

  The cleaning mechanism 35 includes a cleaning unit 37 formed of cloth, paper, or the like. For example, as shown in FIGS. 2A and 3A, the cleaning mechanism 35 cleans the surface of the reflection plate 33 outside the imaging range A. By bringing the portion 37 into contact, the cleaning portion 37 comes to slide on the surface of the reflector 33 when the moving mechanism 34 is driven, so that dirt attached to the surface can be removed. It is like that. In addition, as shown to Fig.3 (a), the cleaning part 37 can be set as the structure which contacts the reflecting plate 33 only at the time of use, and in the example shown in FIG. 3, as shown with a dashed-two dotted line, it is unused. Sometimes it can be evacuated.

In the laser processing apparatus 100, the alignment mark drawing means referred to in the present invention forms an alignment mark P on the surface of the reflection plate 33 by the laser irradiation means 1, as shown in FIGS. 2 (b) and 3 (b). And is controlled by the control means 4.
The alignment mark P indicates a processing reference position (origin) in the laser processing apparatus 100. Based on the position of the alignment mark P, the laser beam L and the stage means 2 are controlled, and the processing object w is processed. Is done.
In the laser processing apparatus 100, the alignment mark P is disposed immediately below the irradiation position of the laser beam L.

A method for detecting the edge (outer shape) of the workpiece w using the laser processing apparatus 100 shown in FIG. 1 will be described.
(Alignment mark detection)
First, the workpiece w is retracted out of the processing range of the laser beam L by the stage portions 21x and 21y. Further, the z stage unit 21 z is moved so that the processing focal position of the laser beam L and the imaging focal position of the imaging means 31 are aligned with the surface of the reflection plate 33. Then, the luminance within the imaging range A (only the reflection plate 33) is determined by the image processing unit 36, and the light amount of the illuminating unit 32 is adjusted so as to have a preset luminance.
Next, for example, a cross-shaped alignment mark P as shown in FIG. 4 is processed on the surface of the reflection plate 33 by the laser irradiation unit 1, and the imaging range A including the alignment mark P is imaged by the imaging unit 31. Then, image processing such as binarization processing is performed on the obtained image (FIG. 4), and the position of the alignment mark P is detected.
After storing the position of the alignment mark P, the reflecting plate 33 is moved by the moving mechanism 34 so that the alignment mark P, processing marks, and other dirt attached to the reflecting surface 33 are not reflected in the imaging range A. Thus, the new surface of the reflector 33 is arranged in the imaging range A. At this time, a new surface can be formed by removing the dirt adhering to the surface of the reflection plate 33 by the cleaning mechanism 35.

(Edge detection)
The workpiece w is placed within the processing range of the laser beam L by the stage portions 21x to 21z. That is, the stage portions 21x to 21z are moved so that the processing focal position of the laser beam L and the imaging focal position of the imaging means 31 are aligned with the surface of the processing object w.
Next, the brightness of the portion other than the processing target w in the imaging range A (the portion of the reflecting plate 33) is determined by the image processing unit 36, and the light amount of the lighting unit 32 is adjusted so as to have a preset brightness. After that, the imaging range A is shot. Then, the obtained image (for example, FIG. 5A) is subjected to image processing such as binarization processing as shown in FIGS. 5B and 5C, and the edge position (outer shape position) of the workpiece w is processed. ) Is detected.
Thereby, the movement amount accompanying the edge detection is calculated with respect to the position of the alignment mark P stored in advance, and the relative position between the alignment mark P and the edge position is stored.

(processing)
Using the position of the alignment mark P obtained from the image analysis result as a reference, the machining position determined by the relationship between the position of the alignment mark P and the relative position of the edge position of the workpiece w is calculated, and based on the result. Then, the laser beam L and the stage portions 21x to 21z are controlled to process the workpiece w into a desired shape.
Further, the reflectance of the surface decreases due to the reflecting plate 33 becoming dirty, etc., and the brightness of the portion other than the processing target w within the imaging range A (the portion of the reflecting plate 33) is determined by the image processing means 36. If the adjustment does not achieve a preset brightness, the new surface of the reflecting plate 33 is arranged so that a processing mark or the like generated during laser irradiation does not appear in the imaging range A. Thereby, since the reflectance of the illumination light S by the reflecting plate 33 can be maintained, the next processing object w can be processed continuously.

(Alignment adjustment)
The moving mechanism 34 is driven to place the new surface of the reflecting plate 33 in the imaging range A of the imaging means 31. Then, a new alignment mark P is formed on the surface of the reflection plate 33 by the laser irradiation means 1 and the position of the latest alignment mark P is detected. Further, the detected position of the latest alignment mark P is stored, and the workpiece w is processed using the position of the latest alignment mark P as a reference.
The alignment adjustment is not necessarily performed for each workpiece w. The position of the processing reference (position of the alignment mark P) of the laser processing apparatus 100 by performing alignment adjustment at regular intervals with reference to the limit set values such as the number of processing objects w to be processed and the usage period set in advance. Can be calibrated.

  In the laser processing apparatus 100 of the present embodiment, the reflectance of the illumination light S by the reflecting plate 33 can be maintained by replacing the surface portion of the reflecting plate 33 with the dirt attached thereto with a new surface, and the captured image is captured. It can prevent that the brightness | luminance of parts other than the process target object w falls. As a result, a high-contrast image can be obtained, and the position of the workpiece w can be detected with high accuracy.

  Further, since the alignment mark P is directly engraved on the reflection plate 33 itself every alignment adjustment, a new alignment mark P is added to the surface of the moved reflection plate 33 even if the reflection plate 33 is moved. Therefore, it is possible to correct the alignment mark P, which is a reference for measurement, so that it is always placed at the same position when taking an image.

  In the present embodiment, since the alignment mark P is directly formed on the reflection plate 33 by the laser irradiation means 1, the alignment mark P is arranged immediately below the laser beam L. For this reason, at the time of alignment adjustment, the formation position of the alignment mark P and the irradiation position of the laser beam L are always arranged at the same position. Therefore, correcting the position of the alignment mark P with high accuracy corrects the laser processing position with high accuracy, and accurate calculation of the relative position between the alignment make P and the edge position enables high-precision processing. It becomes possible.

  In the above-described embodiment, the reflection mechanism that cleans the surface of the reflecting plate 33 by both the moving mechanism 34 that moves the reflecting plate 33 and the cleaning mechanism 35 in which the cleaning unit 37 contacts the surface of the reflecting plate 33. Although the surface cleaning mechanism is configured, the reflection surface cleaning mechanism may be configured by configuring the cleaning mechanism 35 to be movable with respect to the reflection plate 33. Further, it is possible to configure the reflection surface cleaning mechanism only by the moving mechanism 34 without providing the cleaning mechanism 35. Even with the moving mechanism 34 alone, it is possible to cope by moving the reflecting plate 33 and sequentially replacing the surface portion where the dirt or the like of the reflecting plate 33 is adhered to the new surface. What is necessary is just to replace | exchange for another reflecting plate 33. FIG.

Next, an experiment was performed to confirm the effect of the present invention.
Using the laser processing apparatus 100 shown in FIG. 1, the presence / absence of the reflection plate 33 and the difference in the image analysis result by the backlight method when the cylindrical workpiece w was photographed were confirmed.
FIG. 5A shows a part of an image of the processing object w photographed using the reflecting plate 33, and the results of binarization processing for this image are shown in FIGS. 5B and 5C. FIG. 6A shows a part of an image of the processing object w photographed without using the reflector 33. The result of binarization processing for this image is shown in FIGS. 6B and 6C. Shown in
The “+” mark shown in FIGS. 5B and 5C and FIGS. 6B and 6C indicates the position of the edge detected by the image processing means 36. In addition, the image obtained by each method was measured 30 times, and the detected edge position data is shown in Table 1.

  As shown in Table 1, when the reflector 33 is used, detection can be performed with higher accuracy than when the reflector is not used or the backlight method, and the edge detection position is ± 0. Detection was possible with an accuracy of 5 μm or less. On the other hand, when the image is taken without using the reflector, as shown in FIGS. 6B and 6C, a recognition error is caused in which the position where the edge detection position is greatly different is determined as the edge. The result was unstable.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, a galvano scanner 38 including two galvanometer mirrors m5 and m6 and an f-θ lens 14 may be configured to scan the laser beam L as in the laser processing apparatus 200 shown in FIG. it can.

DESCRIPTION OF SYMBOLS 1 Laser irradiation means 2 Stage means 3 Edge detection means 4 Control means 11 Laser light source 12 Beam adjustment part 13 Condensing lens 14 f- (theta) lens 21x-21y Stage part 22 Stage control part 31 Imaging means 32 Illumination means 33 Reflecting plate 34 Movement Mechanism 35 Cleaning mechanism 36 Image processing means 37 Cleaning unit 38 Galvano scanner 100 Laser processing apparatus A Imaging range L Laser beam P Alignment mark S Illumination light w Processing object m1-m6 Mirror

Claims (5)

Laser irradiation means for irradiating a workpiece with a laser beam, stage means movable while holding the workpiece, edge detection means for detecting the position of the workpiece by edge detection using image analysis, The edge detection unit includes a processing object interposed between the imaging unit, an illumination unit that illuminates an imaging range of the imaging unit, and the imaging unit. A reflecting plate that is arranged in a state and reflects the illumination light of the illuminating means to irradiate the object to be processed from behind, a reflecting surface cleaning mechanism that can arrange the surface of the reflecting plate in the imaging range on a new surface, Image processing means for detecting an edge position of the object to be processed from an image obtained by the imaging means ,
The reflecting surface cleaning mechanism, the laser processing apparatus characterized that you have been configured by a moving mechanism arranged in the imaging range of the imaging unit the new surface by moving the reflector. The laser processing apparatus according to claim 1, wherein the reflection surface cleaning mechanism includes a cleaning mechanism that wipes off dirt adhering to the reflection plate. Laser irradiation means for irradiating a workpiece with a laser beam, stage means movable while holding the workpiece, edge detection means for detecting the position of the workpiece by edge detection using image analysis, The edge detection unit includes a processing object interposed between the imaging unit, an illumination unit that illuminates an imaging range of the imaging unit, and the imaging unit. A reflecting plate that is arranged in a state and reflects the illumination light of the illuminating means to irradiate the object to be processed from behind, a reflecting surface cleaning mechanism that can arrange the surface of the reflecting plate in the imaging range on a new surface, Image processing means for detecting an edge position of the object to be processed from an image obtained by the imaging means,
The reflecting surface cleaning mechanism, it features a, Relais chromatography The processing apparatus which is constituted by a cleaning mechanism for wiping the dirt adhered to the reflecting plate. Alignment mark drawing means for forming an alignment mark on the reflector for each alignment adjustment is provided, and the latest alignment mark position formed by the alignment mark drawing means and the workpiece detected by the image processing means of on the basis of the edge position, the laser machining apparatus according that it is configured to calculate the 請 Motomeko 1 you wherein in any one of 3 the processing position of the workpiece.   The laser processing apparatus according to claim 4, wherein the alignment mark drawing unit is configured to form the alignment mark by the laser irradiation unit.