JP2000114619A - Laser marking device - Google Patents

Abstract

(57) [Summary] [Problem] To always enable laser marking with a constant quality. An X stage on which a glass plate W is placed.
And a laser marker 12 that irradiates a laser on the surface of the glass plate W on the X stage 10 to mark the surface of the glass plate W.
A CCD camera 14 for taking an image of a marking portion formed on the surface of the camera and inputting the image, an image processing device 16 for processing the image input by the camera 14, and a processing result by the device, for example, A control device for feedback-controlling the laser output emitted from the oscillation section of the laser marker based on the correlation of the laser output;

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser marking device, and more particularly to a laser marking device for controlling a marking portion to be marked by irradiating a laser with high precision.

[0002]

2. Description of the Related Art Conventionally, direct marking of a product name, a lot number and the like on the surface of various products has been performed. One of the ways to make such markings is
2. Description of the Related Art A method is known in which a laser is applied to a product surface with a laser marking device to directly mark codes such as characters, symbols, marks, and bar codes.

[0003] When marking the surface of a product with this laser marking device, it is extremely important to control the laser output at the time of marking with high accuracy in order to always keep the marking portion formed on the surface at a constant quality. .

[0004]

However, in the conventional laser marking device, the laser output at the time of the marking is measured off-line or on-line by a power meter of the irradiation light itself from the laser oscillation section, and the measurement result is fed back. Therefore, there is a problem that a marking portion of a constant quality cannot always be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and a laser marking apparatus capable of always obtaining a marking part of a constant quality when irradiating a laser on the surface of an object. The task is to provide

[0006]

According to the present invention, there is provided a mounting table for mounting an object, and a laser oscillating means for irradiating a laser on the surface of the object on the mounting table to mark the surface. In a laser marking device, an imaging unit that captures an image of a marking portion formed on the surface of the object and inputs the image, an image processing unit that processes an image input by the imaging unit, and the image processing unit And a control unit for performing feedback control of the laser output emitted from the laser oscillation unit based on the processing result of the above.

That is, in the present invention, a laser (oscillation means) irradiates the surface of a product (object), and the laser output (power) for marking the surface is marked by the laser. Characters, symbols, marks, codes, etc. are input as images, and feedback control is performed based on the results of processing the images, so that the actual marking results can be reflected in the control. Thus, it is possible to always form the marking portion with a constant quality.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing a schematic configuration of a laser marking device according to a first embodiment of the present invention.

The laser marking apparatus according to the present embodiment has an X stage (mounting table) 1 on which a glass plate (object) W is mounted.
0, and a laser marker (laser oscillating means) 12 for irradiating the surface of the glass plate W on the X stage 10 with a laser to mark the surface, and formed on the surface of the glass plate W. CC that captures marking parts (characters, symbols, marks, codes, etc.) and inputs the images
A D camera (imaging means) 14 and an image processing apparatus (personal computer) for processing an image inputted by the CCD camera 14
And a control device 18 for performing feedback control of a laser output emitted from the oscillation section 12A of the laser marker 12 based on a processing result by the processing device 16.

The laser marker 12 has an oscillator 12
The YAG laser is oscillated from A, and the CCD camera 14 has a pixel of about 50 μm and can capture a monochrome image in a field of view of about 25 mm × 20 mm.

An illumination unit 20 having a half mirror is mounted on the front surface of the CCD camera 14. That is, as shown in FIG.
Is attached to the X-axis direction operating unit 22 such that the optical axis of the light receiving unit 14A is parallel to the surface of the glass plate W,
The illumination unit 20 is disposed in front of the light receiving unit 14A. The illumination unit 20 is coaxial epi-illumination, and illuminates the surface of the glass plate W by transmitting the illumination light from the LED (light source) 24 disposed above and reflecting from the surface. A half mirror 26 that reflects light in the direction of the arrow and makes the light incident on the light receiving unit 14A is provided.

Therefore, the illuminating unit 20 is operated in the X-axis direction (horizontal direction) integrally with the CCD camera 14 by the X-axis operating unit 22. And this CCD camera 14
At the time of marking, the user retreats to the position shown in FIG. 2, moves to the position shown in FIG. 1 after marking, and inputs an image.

As described above, the CCD camera 14 is turned sideways so that the surface of the glass plate W located below can be imaged, and the X-axis operating unit 22 can move forward and backward in the direction of the arrow. Therefore, normally, the height H from the glass plate W to the laser oscillation unit 12A is moved below the oscillation unit 12A, which is only about 100 mm, so that an image can be input from the surface of the glass plate W. I have.

The image processing device 16 includes the CCD
An image input board for inputting an image captured by the camera 14, an image processing board for executing image processing to be described later on the input image, a laser output, a line width, a dot size, and a color created in advance. And a memory (not shown) in which data for various objects (glass, metal, resin, etc.) relating to the respective correlations are stored.

In the present embodiment, in the image processing device 16, the actual line width of the marking portion, the line width of the marking portion obtained in advance, and the laser A target current value is calculated based on the correlation with the value of the operation current corresponding to the output, and a control signal corresponding to the current value is output to the control device 18, whereby the output of the laser marker 12 is output. Control.

FIG. 3 shows that the laser marker 12 is 10A.
6 is a graph showing an example of a correlation between a line width and a current value when a line is marked on a glass plate by operating with a current near (Amperes).

From this graph, when operating at 10.0 A, marking can be performed with a line width of about 50 μm, and when this is changed to a current value of 0.5 A unit and 15.0 A, about 70 μm is obtained.
It can be seen that the line width changes by about 20 μm when the width is changed by 5A.

In the present embodiment, the laser marker 12 is used in accordance with the flowchart of FIG.
Feedback control is performed. This is called laser marker 1
The case where a bar code is marked on the glass plate W by the method 2 will be described as an example.

First, as shown in FIG. 2, with the CCD camera 14 retracted to a predetermined position, the laser marker 12
Is set to a target current value, and a laser beam is emitted from the oscillation unit 12A onto the glass plate to mark a line (bar) (step 1).

Next, the laser irradiation is stopped, the CCD camera 14 is moved to the position shown in FIG. 1, the linear marking portion is picked up by the camera 14, an image is input, and the image data is taken into the image processing device 16. (Step 2). Note that a monochrome (black and white) image is input here,
As for the image to be processed as follows, if the CCD camera 14 is not monochrome but color, the output of G alone is sufficient.

In the image processing device 16, the image data taken in to remove noise at the time of input is smoothed (step 3), and then the data is binarized using a predetermined threshold to form a binary image. (Step 4). Next, paying attention to the thickness of the barcode based on the binary image,
The line width of the thin bar is measured, and it is compared whether or not the line width exceeds an allowable value (step 5). If the value exceeds the allowable value, the current value to be corrected to be within the range is
Power calculation is performed using the correlation shown in FIG. 3 (step 6), the current value is output to the control device 18, and feedback control is performed on the laser output at the time of the next marking.

That is, when the thickness of the bar exceeds the allowable value and is too thick, the current value of the laser is lowered. Control to increase the current value is performed. If the line width does not fall within the target line width even with the predetermined current value, a warning is issued because there is a possibility that a problem such as deterioration of the laser lamp has occurred.

Next, a second embodiment according to the present invention will be described.

The laser marking apparatus according to the present embodiment calculates the laser power based on the correlation between the current value and the color of the marking part input with the image when performing the feedback control when the marking target is an iron plate. Except for the above, it is substantially the same as the first embodiment.

FIG. 5 shows the relationship between the change in the current value of the laser marker 12 and the marking color (color of the marking portion) when laser marking is performed on the shadow mask (iron plate). This is, for example, experimentally obtained by actually marking with reference to 15A.

Here, the marking colors R, B and G are represented by 256 (8-bit) gradations. And
It is also determined in advance that each allowable value of R, B, and G is between 235 and 255.

Therefore, for example, when a shadow mask is operated by operating the laser marker at 15A to make a mark, the marking portion turns light gray. At this time, R = 23
6, if G = 240 and B = 238, there is no problem because it is within the above-mentioned allowable value.

However, when the current value is increased by 2 A, the surface is oxidized to a brownish color. At this time, R = 200,
Since G = 100 and B = 50, which deviate from the allowable values, it can be seen that power correction is necessary.

In the case of correcting the power, as shown in FIG. 5, a change in the marking color from white to brown is expected to have a current value change of about 1A. Then, if it does not fall within the permissible range, the laser output is corrected and controlled by making adjustments such that the marking is further reduced by 0.5 A.

The control according to the present embodiment is based on an example in which a shadow mask (not shown) is placed on the X stage 10 in FIG. 1 in place of the glass plate W and numbers are marked on the surface. The flow is shown in the flowchart of FIG. 6 corresponding to FIG.

That is, in this embodiment, the LED light source is set to white, a color image is input by the color CCD camera 14, and the output of G is binarized by considering it as a monochrome image output (step 4). Here, if the binarization cannot be performed, that is, if the marking portion does not have a certain area or more, a warning is issued because the current value is insufficient (steps 5 and 6). If the binarization is completed in step 5, the RGB density is compared with an allowable value in step 7, and the first and second colors are substantially changed in steps 8 and 9.
The same processing as steps 6 and 7 of the embodiment is performed.

As described above, the comparison of the RGB density with the allowable value in step 7 is performed by performing image processing on the smoothed image data by the image processing device 16 to calculate the RGB density and setting the density to the allowable value. As a result, each of the RGB colors is 8
If the bit expression is 235 or more, normal
If it is less than the predetermined value, an instruction to reduce the current value is output to the control device 18 so as to perform the marking by reducing the power.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, in the above-described embodiment, the case where marking and image input are performed separately has been described. However, the present invention is not limited to this, and the CCD camera 14 is located at a position that does not overlap the laser irradiation unit.
, And marking and image input may be performed simultaneously while moving the object, or conversely, the laser marker 12 and the CCD camera 14 may be moved together.

If there is room in the CCD camera, the CCD camera may be used in a vertical orientation with the optical axis vertical. Further, even when the projector is used in the horizontal direction, the LED may not be provided if the surroundings are sufficiently bright.

In the first embodiment, the case where the calculation of the laser power is performed based on the correlation with the line width of the marking portion has been described. However, the present invention is not limited to this. May be performed based on the correlation with the size (diameter or area).

[0038]

As described above, according to the present invention,
Laser marking can always be performed on a marking portion of a constant quality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a laser marking device according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing an enlarged main part of the laser marking device.

FIG. 3 is a graph showing an example of a correlation between an operation current and a line width of a marking portion.

FIG. 4 is a flowchart showing the operation of the first embodiment.

FIG. 5 is a graph showing an example of a correlation between an operation current and a color of a marking portion.

FIG. 6 is a flowchart showing the operation of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... X stage 12 ... Laser marker 12A ... Oscillation part 14 ... CCD camera 16 ... Image processing device 18 ... Control device 20 ... Illumination part 22 ... X-axis operation part 24 ... LED 26 ... Half mirror

Claims (6)

[Claims] 1. A laser marking apparatus comprising: a mounting table on which an object is mounted; and a laser oscillating means for irradiating a laser on the surface of the object on the mounting table to mark the surface. An imaging unit that captures an image of a marking portion formed on the surface of the device and inputs the image; an image processing unit that processes an image input by the imaging unit; and a processing result obtained by the image processing unit. Control means for feedback-controlling the laser output emitted from the laser oscillation means. 2. A laser marking apparatus according to claim 1, wherein the processing result of said image processing means is a line width of a marking portion to which an image has been input. 3. The laser marking apparatus according to claim 1, wherein the processing result by the image processing means is a dot size of a marking portion to which an image has been input. 4. The laser marking apparatus according to claim 1, wherein the processing result by the image processing means is a color of a marking portion input with an image. 5. The light source according to claim 1, wherein the image pickup means has a light receiving portion whose optical axis is parallel to a surface of the object, and a light source disposed above and in front of the light receiving portion. Illuminating means having a half mirror for transmitting the illumination light from and illuminating the surface of the object to be imaged and causing the reflected light from the surface to be incident on the light receiving portion is provided. A laser marking device, wherein an imaging means is integrally movable in a horizontal direction. 6. The imaging device according to claim 5, wherein said imaging means is a CCD.
A laser marking device, being a camera, wherein the light source is an LED.