KR100520899B1 - Calibrating method of marking for lazer marking system - Google Patents

Abstract

The present invention discloses a marking correction method of a laser marking system. The marking correction method of the disclosed laser marking system includes the steps of: (a) assigning observation target chips to each vision camera; (b) matching the coordinates of each vision camera and laser marker; (c) marking a first symbol at each chip or a position corresponding to each chip, observing a first symbol selected by a corresponding vision camera, and teaching one point of the symbol as a reference point; (d) observing the first symbol and the reference point of the chip with a corresponding vision camera and marking each chip with a second symbol based on the reference point; (e) observing a second symbol on the selected chip and teaching a comparison point of the symbol; And (f) detecting the marking error in each cell by detecting the position of the comparison point from the reference point on each chip.

Description

Marking correction method of laser marking system {Calibrating method of marking for lazer marking system}

The present invention relates to a marking correction method of a laser marking system using a vision camera, and more particularly, to a marking correction method of a laser marking system for correcting in consideration of a previously stored marking error while photographing a marking object.

1 is a schematic plan view of a typical leadframe strip. Referring to the drawings, a single strip 10 is equipped with a plurality of chips 12, and letters and / or numbers are displayed on the surface of each chip 12 to distinguish these chips 12 by production lot. . In this case, a laser marker device, which will be described later, which uses a laser beam, is used as the equipment used for marking. Here, reference numeral 14 denotes a mark used to align strips as a recognition tag.

The marking process using the laser marker on the strip 10 tends to be an automatic process including the handling of the strip 10 to improve the marking efficiency.

2 is a schematic diagram of a typical laser marking system.

Referring to the drawings, the laser marking system extracts a strip supply magazine 20 loaded with a plurality of strips 10 and one strip 10 from the magazine 20 and aligns them with the horizontal carriage 22. A loader 30, a prevision camera 40 measuring the alignment of the strip 10, and a step motor 50 for transferring the strip 10 on the horizontal carrier 22 in one direction. And a laser marker 60 for marking characters on a plurality of chips on the strip 10 transferred downward, a post vision camera 70 for imaging the marking on the marked strip 10, and the marking. And an unloader 80 for unloading the strip 10 into the strip recovery magazine 90.

The strip 10 placed on the horizontal carriage 22 by the loader 30 is imaged by the prevision camera 40. The strip 10 is formed with a identification tag (strip itself or an etching line) on one side of the strip 10 so that the alignment state can be easily determined. By the pre-vision camera 40, only the aligned strips 10 are guided to the next marking process, and the misaligned strips 10 are bypassed and loaded again into the strip feed magazine 20 or Discarded.

The arm 52 moves the step motor 50 so that the strip 10 on the horizontal carriage 22 is positioned below the predetermined position, that is, under the prevision camera 40, the laser marker 60, and the post vision camera 70. Driven by

3 is a view showing a schematic configuration of a laser marker. Referring to FIG. 3, the laser marker 60 includes a laser oscillator 61, a galvano scanner 63 that scans a laser beam in a predetermined region in the XY direction, and an incident laser beam over the entire processing region. And an f-theta lens 64 for forming a focal spot of the same size. Reference numerals 63a and 63b reflect laser beams incident as x and y mirrors, respectively, and each mirror is connected to a drive driver (not shown) and changes its angle in accordance with an input command.

The strip 10 in which predetermined characters are marked by the laser marker 60 is transferred under the post vision camera 70 which is the next process. The post vision camera 70 photographs the strip 10 to determine the marking quality so that the incorrectly marked strip is bypassed, and the correctly marked strip is loaded into the strip recovery magazine 90 by the unloader 80.

4 is a plan view illustrating a general tray 16 and chips c located therein. Referring to FIG. 4, the tray 16 is divided into cells into which each chip c enters such that a plurality of chips c are located. Since the size of the cell is somewhat larger than the size of the chip, the chip in each cell may move when the tray 16 is transferred. Therefore, when marking each chip in the tray 16 with a laser marker, the marking positions are different for each chip if the respective chips are not aligned. Therefore, if the marking position is not constant, it does not give the consumer confidence in the quality of the chip itself, and causes complaints.

When marking the chips on the strip, it is possible to observe and mark only the misalignment of the strip with a prevision camera.However, when marking chips in the tray, the marking quality is marked when the chips are misaligned in each cell. There is a problem of significantly lowering.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a marking correction method of a laser marking system that detects an alignment error of each chip and performs marking in consideration of a marking error at each chip position. will be.

In order to achieve the above object, the marking correction method of the laser marking system of the present invention includes a laser marker for marking while observing chips loaded in each cell of a tray with at least one vision camera, and a post for detecting a marked error. In the marking correction method of a laser marking system having a vision camera,

(a) assigning observation target chips to each vision camera;

(b) matching coordinates of each of the vision camera and the laser marker;

(c) marking a predetermined first symbol at each chip or a position corresponding to each chip, observing a first symbol selected by a corresponding vision camera, and teaching one point of the symbol as a reference point;

(d) observing the first symbol and the reference point of the chip with a corresponding vision camera and marking each chip with a second symbol based on the reference point;

(e) observing a second symbol on the selected chip and teaching a comparison point of the symbol; And

(f) detecting the marking error in each cell by detecting the position of the comparison point from the reference point on each chip.

The step (a) may include: (a1) attaching marking paper to a surface of the tray or a plate having the same shape and placing the marking paper under the plurality of vision cameras;

(a2) marking a point within each cell with the laser marker; And

(a3) assigning a vision camera for observing each cell by finding the point with the vision camera;

The method of claim 2,

The one point of step (a2) is preferably the center point of the cell.

In step (b),

(b1) marking an outer edge point of the cell area with respect to the center point with the laser marker; And

(b2) detecting the position of the edge points with a corresponding vision camera to match the coordinate system of the laser marker with the coordinate system of the corresponding vision camera.

In step (c), the edge of the first symbol is pointed to a pointing device while viewing the first symbol on a display.

Step (e) is characterized in that the step of pointing the edge of the second symbol with a pointing device while viewing the second symbol on the display connected to the post vision camera.

On the other hand, the present invention

(g) disposing a tray on which the chips to be marked are stacked below the vision camera;

(h) observing the selected chip with the vision camera and teaching one point of the chip as a marking reference point;

(i) imaging each chip with a corresponding vision camera to calculate an alignment error of each chip; And

(j) correcting and marking the marking error and the alignment error on the basis of the marking reference point of each chip.

In the step (h), it is preferable to point the edge of the chip to a pointing device while viewing the chip on a display.

In step (i),

(i1) imaging each chip; And

(i2) comparing the picked-up image with a standard image and measuring x, y deviation and tilt angle of the marking reference point of the picked-up image from the marking reference point of the standard image.

Hereinafter, with reference to the accompanying drawings will be described in detail the marking correction method of the laser marking system in a preferred embodiment of the present invention.

5 is a view schematically showing the configuration of a laser marking system to which a marking correction method according to a preferred embodiment of the present invention is applied, and the same components as those of the conventional invention have the same names, and detailed descriptions thereof will be omitted.

The laser marking system 160 A tray supply magazine 120 in which a plurality of trays 110 are loaded, a loader 130 which draws out one tray 110 from the magazine 120 and aligns the horizontal tray 122; A step motor 150 for transferring the tray 110 on the horizontal transfer table 122 in one direction, a laser marker 160 for marking characters on each chip in a cell of the tray 110 transferred downward; And a post vision camera 170 for capturing the marking on the marked tray 110 and an unloader 180 for unloading the marked tray 110 into the tray recovery magazine 190. In addition, the laser marking system includes a control unit for controlling the loader 130, the prevision camera 140, the step motor 150, the laser marker 160, the post vision camera 170, and the unloader 180 ( 100) is provided.

The post vision camera 170 is a CCD camera. A charge coupled device (CCD) is a photoelectric conversion sensor that converts light into an electrical signal. The intensity of light entering the lens (not shown) in front of the camera 170 is first recorded in the CCD. At this time, the light of the captured image is separated into different colors by the RGB color filter attached to the CCD. The separated colors are converted into electrical signals by the hundreds of thousands of light sensors (corresponding to the pixels) that make up the CCD. The analog signal from the CCD is converted into digital signals of 0 and 1, and an image signal is produced and output. The post vision camera 170 receives the light from the tray 110 to generate an electrical image signal. The image signal captured by the camera is transmitted to the control unit 100.

FIG. 6 is a diagram schematically illustrating a configuration of the laser marker of FIG. 5.

Referring to FIG. 6, the laser marker 160 may emit light from a laser oscillator 161, a galvano scanner 163, an f-theta lens 164, and a plurality of chips c in the tray 110, which is a marking object. The galvano scanner according to the vision camera 165 for receiving the light and generating an electric image signal, the light 167 for irradiating light to the tray 110, and the position information of the chip from the vision camera 165. A controller (not shown) for adjusting the x mirror 163a and y mirror 163b of 163 is provided.

The galvano scanner 163 has an x mirror 163a and a y mirror 163b and a motor (not shown) for driving them, respectively, and adjusts the positions of the mirrors to scan the laser beam in a predetermined area in the XY direction. Let's do it.

The f-theta lens 164 causes the incident laser beam to form a focal spot having the same size with respect to the entirety of the marking object 110.

The vision camera 165 uses the same CCD camera as the post vision camera 170, and preferably one or more images to capture the entire surface of the tray 110 in a direction perpendicular to the conveyance direction of the tray 110. Is preferably disposed. Thus, the number of vision cameras used depends on the size of the tray and the field of view of the camera. For example, when the length of the tray in the longitudinal direction (the length of the tray feed direction) is 320 mm, the length of the tray in the vertical direction is 150 mm, and the vision camera has a field of view of 100 x 100 mm, the vision camera may be By placing two or four in the direction perpendicular to the transfer direction, the tray can be transferred four or two times with a stepper motor to capture the front of the tray with a vision camera.

On the other hand, it is preferable to observe the marking state while moving the tray 110, which is arranged and conveyed in one of the post vision cameras 170 in the vertical direction.

The calibration method of the laser marking system of the present invention using the laser marking system will be described in detail.

7A and 7B show a flowchart of a marking correction method of a laser marking system according to an exemplary embodiment of the present invention.

First, it is checked whether a marking error in each cell is calculated (step 10).

If it is determined that the marking error is calculated in the tenth step, when using a plurality of vision cameras 165, for example, four vision cameras 165, the chips observed by each vision camera 165 are allocated (step 11). ).

FIG. 8 is a flowchart illustrating one embodiment 11A of the eleventh step shown in FIG. 7A.

Referring to FIG. 8, first, a marking sheet (not shown) is attached to a tray 110 or a surface of a plate (not shown) having the same shape as the tray and disposed below the vision camera 165 (step 30). The marking paper uses a paper printed with black on a white paper, and is preferably arranged so that the surface of the marking paper is located at the focal length of the f-theta lens 164.

Subsequently, the laser marker 160 marks one point, for example, the center point of each cell (step 32).

Then, the vision camera 165 locates the center point and determines the vision camera 165 for observing each cell (step 34).

After the eleventh step, the coordinate system of each vision camera 165 and the coordinate system of the laser marker 160 coincide (step 12). This is a process of matching these coordinates because the units of the coordinates viewed by the vision camera 165 and the coordinates viewed by the laser marker 160 are different.

FIG. 9 is a flowchart describing one embodiment 12A of the twelfth step shown in FIG. 7A.

Referring to FIG. 9, the laser marker 160 marks a point on a rectangular edge of an area corresponding to a cell based on the center point of step 32 (step 42). At this time, the edge point is marked by the coordinate system of the laser marker 160.

Subsequently, the position of the outer point of the selected cell is detected by the coordinate system of the corresponding vision camera 165 and compared with the coordinate system of the laser marker 160 in step 42 (step 44).

After the twelfth step, after marking the first symbol S1 at a position corresponding to each chip, the pointing device is observed while observing the first symbol S1 selected by the corresponding vision camera 165 on a display (not shown). The edge of the first symbol S1 is pointed at (not shown) to be the reference point P1 (see FIG. 10). That is, the reference point P1 is taught to the vision camera 165 (step 13).

Subsequently, while observing each cell with the corresponding vision camera 165, the first symbol S1 and the reference point P1 are found and the second symbol S2 is marked based on the reference point P1 (step 14).

After finishing the marking process, the tray 110 or the plate is conveyed downward of the post vision camera 170 and is preferably observed one by one by the post vision camera 170 moving in the vertical direction to the tray conveying direction. The operator observes one of these chips on the display and points the point P2 of the second symbol S2 with the pointing device to teach the comparison point P2 to the post vision camera 170 (step 15). .

Subsequently, the reference point P1 and the marking reference point P2 of each cell are detected by the post vision camera 170 to measure the position of the comparison point P2 from the reference point P1, and then the deviation between the two predetermined points is determined. The marking error is calculated and stored in the memory (step 16). The marking error stored in the memory is corrected by adjusting the x mirror 163a and the y mirror 163b of the galvano scanner 163 to correct the marking error.

The marking error calculation process is applicable when the chips are uniformly arranged in each cell of the tray 110 or when the chips are formed on the strip. Alignment error should be measured and corrected.

Subsequently, the tray 110 in which the chips are loaded in the cell is disposed at the same position as in the thirty step (step 17).

Subsequently, it is determined whether the marking reference point should be newly designated (step 18). On the other hand, when using the marking error in each cell previously stored in the memory in step 10, step 18 is performed.

If it is determined in step 18 that a new marking reference point is specified, the vision camera 165 is pointed at a point of the chip, for example, one edge point P3, by the pointing device while looking at the chip selected by the vision camera 165 on the display. ) To the marking reference point P3 (step 19) (see Fig. 11).

Subsequently, each chip is imaged by the vision camera 165 to calculate an alignment error of each chip (step 20). If it is determined in step 18 that the previously stored marking reference point P3 is used, step 20 is performed.

FIG. 12 is a flowchart for explaining an embodiment 20A of the twentieth step shown in FIG. 7B.

Referring to FIG. 12, first, the position of each chip is captured by the vision camera 165 (operation 50).

Subsequently, the standard image of the chip (dotted line shown in FIG. 12) is compared with the measured image of each chip (solid line shown in FIG. 12), and is compared from one point P0 of the standard image corresponding to the marking reference point P3. The x, y deviation (dx, dy) of the marking reference point (P3) and the measured tilt angle (θ) of the chip is measured (step 52).

After the twentieth step, the marking error of the corresponding cell calculated in step 32 and the alignment error of each chip calculated in step 52 are corrected and marked based on the marking reference point P3 of each chip (step 21). . That is, in consideration of the above errors, the x mirror 163a and the y mirror 163b of the galvano scanner 163 are adjusted and marked on each chip.

In the above embodiment, a method of marking each chip in a cell of a tray has been described, but it is of course applicable to a method of detecting marking correction of each chip even when marking each chip formed on a strip.

In addition, in the above embodiment, the marking correction method in the marking system using a plurality of vision cameras has been described, but it is also applicable to the case where a width of a tray or a strip is observed by one vision camera.

As described above, according to the calibration method of the laser marking system according to the present invention, the marking error in each cell and the alignment error of each chip are measured, and the galvano scanner is adjusted to correct these errors, thereby contributing to the improvement of the marking quality. have.

Although the present invention has been described with reference to the embodiments with reference to the drawings, this is merely exemplary, it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined only by the appended claims.

1 is a schematic plan view of a typical leadframe strip.

2 is a schematic diagram of a typical laser marking system.

3 is a diagram schematically illustrating a configuration of the laser marker of FIG. 2.

4 is a diagram illustrating a typical tray and chips located therein.

5 is a view schematically showing the configuration of a laser marking system to which a marking correction method according to an exemplary embodiment of the present invention is applied.

FIG. 6 is a diagram schematically illustrating a configuration of the laser marker of FIG. 5.

7A and 7B are flowcharts of a calibration method of a laser marking system according to a preferred embodiment of the present invention.

FIG. 8 is a flowchart for explaining an embodiment of the eleventh step shown in FIG. 7A.

FIG. 9 is a flowchart for explaining an embodiment of the twelfth step shown in FIG. 7A.

FIG. 10 is a diagram illustrating measuring marking error in each cell. FIG.

It is a figure explaining measuring the alignment error of a chip.

12 is a flowchart for explaining an embodiment of the twentieth step shown in FIG. 7B.

* Description of Signs of Major Parts of Drawings *

10: strip 12: chip

14: Dog Tag 20,120: Supply Magazine

22,122: horizontal feeder 30,130: loader

40: prevision camera 50,150: stepper motor

60,160: laser marker 61,161: laser oscillator

63,163: Galvano Scanner 63a, 163a: x mirror

63b, 163b: y mirror 64,164: F-theta lens

100: control unit 110: tray

165: vision camera 167: light

Claims (10)

In the marking correction method of the laser marking system comprising a laser marker for marking while observing the chips stacked in each cell of the tray with at least one vision camera, and a post vision camera for detecting the marked error, (a) assigning observation target chips to each vision camera; (b) matching coordinates of each of the vision camera and the laser marker; (c) marking a predetermined first symbol at each chip or a position corresponding to each chip, observing a first symbol selected by a corresponding vision camera, and teaching one point of the symbol as a reference point; (d) observing the first symbol and the reference point of the chip with a corresponding vision camera and marking each chip with a second symbol based on the reference point; (e) observing a second symbol on the selected chip and teaching a comparison point of the symbol; And (f) detecting the marking error in each cell by detecting the position of the comparison point from the reference point on each chip. The method of claim 1, In step (a), (a1) attaching marking paper to a surface of the tray or a plate having the same shape and placing the marking paper under the plurality of vision cameras; (a2) marking a point within each cell with the laser marker; (a3) assigning a vision camera for observing the respective cells by finding the point with the vision camera; marking correction method of a laser marking system, comprising: The method of claim 2, The one point is a marking correction method of the laser marking system, characterized in that the center point of the cell. The method of claim 3, wherein In step (b), (b1) marking an outer edge point of the cell area with respect to the center point with the laser marker; And (b2) detecting a position of the edge points with a corresponding vision camera to match a coordinate system of the laser marker with a coordinate system of the corresponding vision camera. The method of claim 1, In the step (c), while marking the first symbol on a display, the marking correction method of the laser marking system, characterized in that pointing to the edge of the first symbol. The method of claim 1, In the step (e), while marking the second symbol on the display connected to the post vision camera, the marking correction method of the laser marking system, characterized in that for pointing the edge of the second symbol. The method of claim 4, wherein (g) disposing a tray on which the chips to be marked are stacked below the vision camera; (h) observing the selected chip with the vision camera and teaching one point of the chip as a marking reference point; (i) imaging each chip with a corresponding vision camera to calculate an alignment error of each chip; And (j) correcting and marking the marking error and the alignment error on the basis of the marking reference point of each chip; marking correction method of the laser marking system further comprising. The method of claim 7, wherein In the step (g), the marking correction method of the laser marking system, characterized in that for placing the tray in the position of the plate of the step (a1). The method of claim 7, wherein In the step (h), the marking of the laser marking system, characterized in that for pointing the edge of the chip with a pointing device while viewing the chip on the display. The method of claim 7, wherein In step (i), (i1) imaging each chip; And (i2) comparing the picked-up image with a standard image and measuring x, y deviations and tilt angles of the marking reference point of the picked-up image from the marking reference point of the standard image; Marking correction method of marking system.