JP2004148379A - System and method for laser marking - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser marking system and method capable of reducing cost while pursuing miniaturization and shortening of operation time. <P>SOLUTION: The optical axis of a CCD camera 2 is arranged in accordance with the optical axis of a laser beam source 3. A control unit 9 corrects a marking position on a workpiece 8 through image pickup of the workpiece 8 by the CCD camera 2, while controlling galvanomirrors 4a, 4b in each designated position. Then, after marking a marking information on the workpiece 8 by controlling the galvanomirrors 4a, 4b, the confirmation of marking information is carried out through the image pickup of the workpiece 8 by the CCD camera 2, while controlling the galvanomirrors 4a, 4b in each designated position. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser marking system and a laser marking method mainly including a laser marking apparatus that performs marking by two-dimensionally scanning the surface of an object to be marked with a laser beam emitted from a laser light source. .
[0002]
[Problems to be solved by the invention]
Conventionally, the galvano mirror is used to mark the marking information such as preset characters, symbols, figures, etc. on the workpiece, which is the object to be marked, by two-dimensionally scanning the laser beam emitted from the laser light source using a galvanometer mirror. Scanning laser marking devices are provided.
[0003]
This type of laser marking apparatus is generally incorporated in a production line such as a factory and used to mark marking information on a conveyed workpiece. In this case, when the conveyed work is positioned in the marking area of the laser marking device, it may be displaced from the normal reference position or may be positioned with an inclination on the XY plane. In such a case, even if marking information set in advance is marked at a preset position, there is a problem in that the marking information marked on the actual workpiece causes a displacement or an inclination.
Therefore, a camera for confirming the position of the workpiece is arranged, a deviation from the reference position of the workpiece is detected from the image data obtained by this camera, and the coordinate data of the laser marking device is corrected according to the deviation amount. Yes.
[0004]
On the other hand, if the marking information is not marked for some reason on the workpiece that has been subjected to marking processing by the laser marking device, it will be shipped as it is or defective marking will not be detected at an early stage. It may be generated in large quantities. For this reason, it is necessary to prevent the occurrence of defective products by detecting whether or not the marking information is correctly marked on the workpiece.
In order to prevent such a problem, a camera for visual inspection is arranged, and a marking error of the workpiece is found based on image data from the camera.
[0005]
However, when such a conventional laser marking device is incorporated in a transport line, a camera for position confirmation is disposed upstream with respect to the transport direction, and a laser marking device is disposed downstream thereof. Further, a laser marking system is configured by disposing a camera for appearance inspection downstream thereof. For this reason, there exists a problem that the whole system will enlarge very much and cost will increase.
[0006]
However, there is a configuration shown in Japanese Patent Application Laid-Open No. 11-156666 for the purpose of downsizing the apparatus. This is intended to reduce the size of the apparatus by using a single camera as both a lead part type and front / back discrimination before marking processing and an appearance inspection camera after marking.
[0007]
However, in Japanese Patent Laid-Open No. 11-156666, the actual marking processing position and the standby position for observation with the camera are set at different positions, and these positions are mechanically moved. Yes. Moreover, the actual situation is that the position adjustment is not performed at the standby position.
[0008]
By the way, in the marking operation, the marking position with respect to the workpiece is often important, and it is desirable to accurately mark the designated position of the workpiece. However, in the configuration of Japanese Patent Application Laid-Open No. 11-156666, position adjustment is performed. If it is going to be done, it will be done by mechanical adjustment. For this reason, in order to improve positional accuracy, it becomes a mechanically large thing, and the enlargement of a device and the cost increase are caused.
[0009]
Furthermore, since the thing of Unexamined-Japanese-Patent No. 11-156666 is a structure which performs an observation operation simultaneously during a marking process, it is necessary to make a marking area | region and an observation area | region into a different place inevitably. In particular, if such a configuration is to be adopted for a conventional transport line, the cameras and laser marking devices are arranged in a line. Therefore, before marking, the workpiece must be transported and stopped in the observation area of the camera before marking, and after the marking is completed, the workpiece must be transported again from the marking area to the observation area for observation. Become. For this reason, the conveyance position with respect to the observation area before and after the marking process may be different, and if this position accuracy is to be performed with high accuracy, it is mechanically complicated. In addition, since the conveying device is returned to the original position after the marking is completed, the processing time is lost when viewed from the whole marking system, and the efficiency is deteriorated.
[0010]
In particular, in workpieces marked with a laser marking device, very small marking information is often marked on small objects such as chip parts. In this case, the position accuracy greatly affects the The problem becomes even more serious.
[0011]
On the other hand, as shown in Japanese Patent Laid-Open Nos. 06-090052 and 04-253585, a camera is placed so that the optical axis is the same as the optical axis from the laser light source, and the workpiece before marking is placed. There is a configuration for confirming the position and correcting the marking data.
Further, as disclosed in Japanese Patent Application Laid-Open No. 09-220686, there is a configuration in which an appearance inspection of a workpiece after marking is performed by arranging a camera so as to be the same light source as the optical axis from the laser light source.
According to such a configuration, it is possible to confirm the placement position of the workpiece without moving the workpiece, or to perform inspection after marking, so that it seems that high correction accuracy or inspection accuracy can be obtained. It is.
[0012]
However, in such a configuration, when imaging with a camera, visible light having a wavelength band different from the wavelength band of the laser light from the laser light source is used. It becomes blurred and accurate image data cannot be obtained. For this reason, there exists a fault which cannot perform adjustment of a marking position or confirmation of a marking state systematically.
[0013]
The present invention has been made in view of the above circumstances, and a first object thereof is to reduce the cost while reducing the size and working time, and a second object is to adjust the marking position and to perform marking. An object of the present invention is to provide a laser marking system and a laser marking method capable of improving the accuracy of state confirmation.
[0014]
[Means for Solving the Problems]
The present invention two-dimensionally scans laser light emitted from a laser light source by a scanning means based on marking coordinate data corresponding to marking information, and the laser light scanned by the scanning means is a predetermined marking region. Provided with a laser marking device provided with a control means for performing marking by condensing with a converging lens on the surface of an object to be marked located at the surface, and provided with an imaging means for imaging the object to be marked located in the marking area A correction unit that calculates a deviation amount of the marking target object with respect to a preset reference position based on the position of the marking target object imaged by the imaging unit, and corrects the marking coordinate data based on the deviation amount. And providing the storage means for storing the deviation amount, the control means includes the correction means. After marking is performed on an object to be marked located in the marking area based on the corrected coordinate data for marking, the object to be marked marked by the imaging unit is imaged, and the marked object to be marked When comparing the image data of the object with reference image data set in advance, one of the image data of the marked object to be marked or the reference image data is stored in the storage means. The comparison is made after correction based on the quantity (Claim 1).
[0015]
According to such a configuration, the imaging unit for position adjustment before marking the object to be marked can be made the same as the imaging unit for determining the marking defect after marking. One is sufficient, and it is possible to reduce the cost by simplifying the configuration of the entire system, and it is not necessary to move the object to be marked, so that the marking work time can be shortened.
[0016]
In addition, when marking defect determination is performed by comparing the image data of the marking target object after marking imaged by the imaging means and the reference image data, one image data is corrected based on the amount of deviation. Since it is executed, the accuracy of marking defect determination can be improved.
[0017]
An optical path branching unit for branching an optical path is provided between the laser light source and the scanning unit, and the imaging unit is configured so that an optical axis from the optical path branching unit to the scanning unit coincides with an optical axis of the laser light source. The converging lens is provided with an achromatic lens for preventing chromatic aberration, and the imaging means is configured integrally with a laser marking device (claim 2).
[0018]
According to such a configuration, since the optical axis of the laser light source and the optical axis of the imaging unit coincide with the optical axis from the optical path branching unit to the scanning unit, the imaging unit is configured integrally with the laser marking device. However, it is possible to reduce the size and to image the object to be marked from directly above, and to image the object to be marked with high accuracy.
[0019]
By the way, when imaging the object to be marked by the imaging means, since visible light having a wavelength band different from the wavelength band of the laser light from the laser light source is used, the image formation through the converging lens is blurred due to chromatic aberration. Since the achromatic lens is used as the converging lens, it is possible to prevent the influence of chromatic aberration when visible light passes through the converging lens and obtain accurate image data.
[0020]
In the present invention, the laser beam emitted from the laser light source is two-dimensionally scanned in a focused state on the surface of the object to be marked located in a predetermined marking area based on the marking coordinate data corresponding to the marking information. In the laser marking method of performing marking by
In a state in which the object to be marked is located in the marking area, the object to be marked is imaged by the imaging means, and the object to be marked with respect to a reference position set in advance based on the image data of the imaged object to be marked A deviation amount is calculated, the marking coordinate data is corrected based on the deviation amount, marking is performed on the marking target object based on the corrected marking coordinate data, and the marking target is processed by the imaging unit. The object is imaged again, and the image data of the marked object to be marked, which is imaged by the imaging means, is compared with the reference image data set in advance. Based on one of the image data of the marked object to be marked or the reference image data corrected based on It is characterized in that to determine the defective marking by (claim 3).
According to such a method, it is possible to perform a series of operations of imaging for correction at the time of marking, marking, and imaging for inspection after marking without moving the object to be marked located in the marking area. Therefore, only one imaging means is necessary.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a laser marking system. In FIG. 1, the laser marking system is composed of a laser marking device 1 and a CCD camera 2 as imaging means. The CCD camera 2 is constructed integrally with the laser marking device 1.
[0022]
First, the laser marking device 1 will be described. Laser light of a predetermined wavelength is emitted from the laser light source 3, and the laser light is deflected by an X-direction scanning galvanometer mirror 4a and a Y-direction scanning galvanometer mirror 4b as scanning means. These galvanometer mirrors 4a and 4b are configured to scan the laser beam two-dimensionally within a predetermined marking area by adjusting the angles thereof by motors 5a and 5b.
[0023]
The fθ lens 6 that is a converging lens converges the laser light that is two-dimensionally scanned by the galvanometer mirrors 4a and 4b onto the workpiece 8 that is the object to be marked. In this case, the fθ lens 6 is formed of an achromatic lens that does not cause chromatic aberration when visible light passes.
[0024]
The control device 9, which is a control means, a correction means, and a storage means, is composed mainly of a CPU. When generating a plurality of coordinate data from marking information such as characters, symbols, and figures to be marked, and marking the workpiece 8 Sequentially outputs drive signals corresponding to a plurality of coordinate data for driving the galvanometer mirrors 4a and 4b to the motors 5a and 5b.
[0025]
The laser marking device 1 is configured as described above, and the laser light irradiated onto the work 8 placed on the belt conveyor 7 via the fθ lens 6 is based on the drive signal from the control device 9. By scanning two-dimensionally with the galvanometer mirrors 4a and 4b, it is possible to mark characters, symbols, figures and the like on the workpiece 8 in a predetermined marking area.
[0026]
On the other hand, the CCD camera 2 integrally formed with the laser marking device 1 is provided so as to have the same optical axis as the optical axis of the laser light source 3. That is, a cold mirror 10 as an optical path branching unit is interposed in the optical path from the laser light source 3 to the galvanometer mirrors 4a and 4b, and the optical axis of the CCD camera 2 is bent by the cold mirror 10, It coincides with the optical axis from the laser light source 3 toward the galvanometer mirrors 4a and 4b.
[0027]
Next, the operation of the above configuration will be described.
First, marking information such as characters, symbols and figures to be marked on the workpiece 8 is set by setting means such as a console of the control device 9. At this time, marking speed, marking line width, laser power, font size, and the like are also set as marking parameters.
[0028]
Then, the teaching operation by the laser marking device 1 is executed in a state where the sample workpiece 8 is placed at the reference position on the belt conveyor 7. The reference position is a position where the workpiece 8 is conveyed by the belt conveyor 7 in the marking area of the laser marking device 1, and the workpiece 8 is always positioned at the reference position. In this case, the teaching operation of the laser marking device 1 may be basically performed once, but is performed again when the workpiece 8 is changed or when the placement position of the workpiece 8 is changed from the original reference position. To do.
[0029]
FIG. 2 shows a teaching operation by the laser marking device 1. In FIG. 2, as a first step, the galvanometer mirrors 4a and 4b are moved to designated positions (S101). This designated position is a position where the optical axis of the laser light source 3 is the center of the reference position set as described above. In such a positional relationship, the visual field of the CCD camera 2 is the center position of the reference position. Is a predetermined range centered at.
[0030]
Next, the position of the corner of the workpiece 8 is detected by the CCD camera 2, and the coordinates are set to (X, Y) (S102). This coordinate corresponds to the pixel position of the CCD camera 2.
Next, control is performed so that the optical axis of the laser light source 3 by the galvanometer mirrors 4a and 4b is moved in the X direction by + α mm from the designated position (S103), and then the corner position of the workpiece 8 is detected again. The coordinates are set to (X ′, Y) (S104). In this case, since the number of pixels (X′−X) corresponds to αmm, one pixel of the CCD camera 2 corresponds to α / (X′−X) mm in the X direction.
[0031]
Subsequently, after controlling the galvanometer mirrors 4a and 4b so that the coordinate center is moved in the Y direction by + β mm from the designated position (S105), the position of the corner of the workpiece 8 is detected, and the coordinates are set. (X, Y ′) is assumed (S106). In this case, since the number of pixels (Y′−Y) corresponds to βmm, one pixel of the CCD camera 2 corresponds to β / (Y′−Y) mm in the Y direction.
[0032]
Then, correction parameters α / (X′−X) and β / (Y′−Y) are obtained based on (X, Y), (X ′, Y ′), α, and β obtained as described above. Calculate and save (S107). These correction parameters are required when obtaining coordinate data corresponding to the pixel position imaged by the CCD camera 2 during the marking operation described later.
[0033]
Next, the marking position is registered. That is, at the time of teaching described above, since the sample work 8 is displayed on the console screen of the control device 9, the position where marking information is desired to be marked is confirmed while checking the screen. When the marking position is determined, the position is registered.
[0034]
Next, the marking information is test-printed on the sample workpiece 8, and the image data of the marked workpiece 8 is stored as reference image data in a storage means (not shown).
As described above, when the registration of the correction parameter, the marking position, and the reference image data is completed, the marking can actually be performed on the workpiece 8.
[0035]
FIG. 3 shows a marking operation by the control device 9. In FIG. 3, when the work 8 is conveyed to a predetermined reference position by the belt conveyor 7, a print trigger is given to the control device 9. Then, in response to the input of the print trigger (S201: YES), the control device 9 controls the galvanometer mirrors 4a and 4b to designated coordinates (S202). The designated coordinates are positions where the optical axis of the laser light source 3 is the center of the reference position, and the visual field of the CCD camera 2 is a predetermined range centered on the designated position.
[0036]
Next, after detecting the position of the workpiece 8 by the CCD camera 2 (S203), the coordinate shift (lateral shift and inclination) of the marking position is calculated from the shift amount between the detected workpiece position and the previously registered workpiece position. (S204). In this case, the actual numerical value (mm) of the lateral deviation can be obtained by multiplying the lateral deviation amount (number of bits) by the correction parameter obtained by teaching.
[0037]
When the marking position for the workpiece 8 is thus determined, actual marking is executed (S205). That is, the control device 9 performs marking on the workpiece 8 based on the corrected coordinate data, and controls the galvanometer mirrors 4a and 4b while driving the laser light source 3 to thereby determine a predetermined position on the workpiece 8. Then, the laser beam is scanned two-dimensionally in a focused state by the fθ lens 6. Thereby, since the part which the laser beam condensed on the surface of the workpiece | work 8 is heated intensively, predetermined marking information can be marked on the surface of the workpiece | work 8. FIG.
[0038]
When the marking is completed, the control device 9 positions the galvanometer mirrors 4a and 4b so as to have the designated coordinates (S206), and then images the workpiece 8 again by the CCD camera 2, and the CCD camera. Marking failure is determined based on the image data from 2 (S207). If the marking is defective (S208: NO), it is determined as NG (S209). At this time, since the light source of the CCD camera 2 is general visible light, chromatic aberration occurs when passing through the fθ lens 6, but in this embodiment, an achromatic lens is used as the fθ lens 6. Therefore, chromatic aberration when visible light passes through the fθ lens 6 can be prevented, and marking information on the workpiece 8 can be imaged with high accuracy.
[0039]
As a method of judging marking failure, the position, inclination, size of marking information marked on the workpiece 8 or the line width of characters, symbols, figures, etc. constituting the marking information, depending on the marking information and marking parameters set. And a method for judging such chipping by comparing a reference pattern with image data (a method of tracing an actual marking pattern), and a preset work among image data picked up by the CCD camera 2 The part of the image data in the predetermined range where the above marking information is marked was extracted, and marking was applied to the area above the predetermined amount because the amount of received light on the workpiece surface and other received light amount existed How to determine (simply determine whether the workpiece is marked or not Law) there is.
[0040]
In particular, in the present embodiment, when performing the above-described determination operation, the control device 9 calculates and stores the deviation amount with respect to the reference placement position from the image data obtained by the marking process. It is possible to accurately determine the marking defect by correcting the image data obtained later by the amount of deviation and comparing the corrected image data with the reference image data registered in advance.
The reference image data may be corrected based on the amount of deviation, and the marking defect determination may be performed by comparing the corrected reference image data with the image data obtained by the marking process.
[0041]
According to such an embodiment, the control device 9 obtains a correction parameter by imaging the workpiece 8 located in the marking area with the CCD camera 1 and corrects the marking position based on the correction parameter. Since marking is performed on the workpiece and the workpiece 8 located in the marking area is imaged by the CCD camera 2 to confirm after marking, the imaging before marking and after marking is performed by one CCD camera 2. It can be performed. Therefore, unlike the conventional configuration in which separate imaging means are required before and after marking, the entire laser marking system is not increased in size, and the laser marking system is reduced in size and the work time is shortened. Cost reduction can be achieved.
[0042]
Moreover, when the marking defect determination is performed by comparing the image data of the workpiece 8 after marking imaged by the CCD camera with the reference image data, it is executed after correcting one of the image data based on the shift amount. Since it did in this way, the precision of marking defect discrimination | determination can be improved.
[0043]
Further, since the optical axis of the CCD camera 2 is made to coincide with the optical axis of the laser light source 3, the entire laser marking system can be further reduced in size, and the workpiece 8 can be imaged from directly above, and imaging data can be captured. Can improve the accuracy. In addition, since an achromatic lens is used as the fθ lens 6 interposed in the optical axis of the CCD camera 2, even if visible light is used as the light source of the CCD camera 2, the image formed on the CCD camera 2 is blurred. The coordinates of the workpiece 8 and the marking information can be read with high accuracy.
[0044]
The present invention is not limited to the above embodiment, and the CCD camera 2 may be provided independently of the laser marking device 1.
[0045]
【The invention's effect】
As is clear from the above description, according to the laser marking system and laser marking method of the present invention, the imaging object to be marked is imaged before and after marking by one imaging means. Thus, it is possible to reduce the cost while reducing the size and working time.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an entire system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a teaching operation by a control device. FIG. 3 is a flowchart showing a marking operation by a control device.
1 is a laser marking device, 2 is a CCD camera (imaging means), 3 is a laser light source, 4a and 4b are galvanometer mirrors (scanning means), 6 is an fθ lens (converging lens), 8 is a workpiece (object to be marked), Reference numeral 9 denotes a control device (control means, correction means, storage means), and 10 denotes a cold mirror (optical path branching means).

Claims (3)

The laser beam emitted from the laser light source is scanned two-dimensionally by the scanning unit based on the marking coordinate data corresponding to the marking information, and the laser beam scanned by the scanning unit is positioned in a predetermined marking area. A laser marking device provided with a control means for performing marking by condensing light on the surface of the marking object by a converging lens;
Imaging means for imaging an object to be marked located in the marking area;
Correction means for calculating a deviation amount of the marking target object with respect to a preset reference position based on the position of the marking target object imaged by the imaging means, and correcting the marking coordinate data based on the deviation amount; ,
Storage means for storing the deviation amount,
The control means performs marking on the marking target object positioned in the marking area based on the marking coordinate data corrected by the correction means, and then sets the marking target object marked by the imaging means. When comparing the image data of the marked object to be marked with the reference image data set in advance, one of the image data of the marked object to be marked or the reference image data is A laser marking system, wherein the comparison is performed after correction based on the amount of deviation stored in the storage means. Optical path branching means for branching an optical path between the laser light source and the scanning means;
The imaging unit is provided so that an optical axis from the optical path branching unit to the scanning unit coincides with an optical axis of the laser light source,
The converging lens is composed of an achromatic lens for preventing chromatic aberration,
The laser marking system according to claim 1, wherein the imaging unit is configured integrally with a laser marking device. Marking is performed by two-dimensionally scanning the surface of the object to be marked located in a predetermined marking area based on the coordinate data for marking corresponding to the marking information with laser light emitted from the laser light source. In the laser marking method to
In a state where the object to be marked is located in the marking area,
The object to be marked is imaged by the imaging means,
Calculate the amount of deviation of the marking target object with respect to a preset reference position based on the imaged image data of the marking target object, correct the marking coordinate data based on the amount of deviation,
Marking the object to be marked based on the corrected coordinate data for marking,
Image the object to be marked again with the imaging means,
Comparing image data of a marked object to be marked imaged by the imaging means with reference image data set in advance,
In this comparison, the marking defect is judged by comparing one of the image data of the marked object to be marked or the reference image data after correction based on the amount of deviation. Laser marking method.

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