JP2018089646A - Two-dimensional code marking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve deterioration of display quality of a two-dimensional code generated by a state of a workpiece surface.SOLUTION: A two-dimensional code marking device 1 includes a laser marking part 2, a control part 3 which controls print output of the laser marking part 2, and a reading part 4 which reads a two-dimensional code printed by the laser marking part 2. The reading part 4 includes display quality evaluation means 40 which evaluates display quality of the printed two-dimensional code. The control part 3 acquires reading information output from the display quality evaluation means 40, and controls the print output of the laser marking part 2 so as to improve the display quality based on the reading information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a two-dimensional code marking apparatus using a laser marker.

  A two-dimensional code has information in both horizontal (horizontal) and vertical (vertical), and has a small amount of information and a large amount of information compared to a one-dimensional code (barcode). In general, there are known a stack type in which the cells are stacked vertically and a matrix type in which unit cells called modules form grids (black and white mosaic patterns) in a vertical and horizontal mosaic pattern. Such a two-dimensional code is attached to the surface of a product or a part or the surface of a packaging body that wraps the product or part, so as to integrate the product or part and the information accompanying it.

  A laser marking device is used as a device for applying a two-dimensional code to the surface of a product or a part. The laser marking device prints a two-dimensional code by irradiating the surface of a workpiece with laser light and coloring / deteriorating or processing the irradiated portion.

  As a conventional laser marking device, after printing on the workpiece surface with the laser marking device, the workpiece surface is imaged with a CCD camera, and the output is input to a personal computer to output the CCD camera. Based on the above, there has been proposed one that determines whether or not printing is performed on the surface of a workpiece (see Patent Document 1 below).

JP 2009-214141 A

  When a two-dimensional code is printed on the surface of a workpiece using a laser marking device, the display quality of the printed two-dimensional code may be lowered depending on the state of the workpiece surface. Such deterioration in display quality has problems such as increasing the frequency of occurrence of reading errors and erroneous readings, and some improvement is required. In particular, in the case of a two-dimensional code, information cannot be digitized and written together with the code as in the case of a one-dimensional code. For this reason, improvement of display quality is an important issue in order to ensure information provision by a two-dimensional code.

  On the other hand, the above-described conventional laser marking apparatus can determine the presence or absence of printing and the deviation of printing based on the output of the CCD camera, but until the improvement of the display quality caused by the state of the workpiece surface is improved. Can not. In addition, since the conventional laser marking device inputs the output of the CCD camera to a personal computer as a control unit and determines the print result, the control unit performs a complicated determination process, and the processing load on the control unit is reduced. There is also the problem of growing.

  The present invention has been proposed to address such problems. That is, the two-dimensional code marking device of the present invention improves the deterioration of the display quality of the two-dimensional code caused by the state of the workpiece surface, and reduces the processing burden on the control unit of the laser marking device for this improvement. It is an issue.

  In order to solve such a problem, the present invention has the following configuration.

  A laser marking unit; a control unit that controls printing output of the laser marking unit; and a reading unit that reads a two-dimensional code printed by the laser marking unit, wherein the reading unit displays a printed two-dimensional code. Display quality evaluation means for evaluating the quality, the control unit acquires the read information output from the display quality evaluation means, and based on the read information, the display quality is improved, A two-dimensional code marking device for controlling printing output of the laser marking unit.

It is explanatory drawing which showed schematic structure of the two-dimensional code marking apparatus which concerns on embodiment of this invention. It is explanatory drawing which showed the example of improvement of modulation evaluation. It is explanatory drawing which showed the example of an improvement of axial non-uniformity / grid non-uniformity evaluation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the two-dimensional code marking device 1 includes a laser marking unit 2, a control unit 3, and a reading unit 4.

  The laser marking unit 2 includes a laser light source (laser oscillator), a drive unit that drives the laser light source, a scanner that irradiates the surface of the workpiece W with the laser light emitted from the laser light source, an optical system, and the like. The laser marking unit 2 prints a two-dimensional code on the surface of the workpiece W by two-dimensionally scanning laser light applied to the surface of the workpiece W based on the input printing information (marking data).

  The control unit 3 controls the printing output of the laser marking unit 2, and the laser output adjusting means 3A for adjusting the output of the laser beam emitted from the laser light source and the marking data output to the laser marking unit 2 Marking data correction means 3B for correction is provided.

  The reading unit 4 reads the printed two-dimensional code and outputs read information, and has a function (display quality evaluation means 40) for evaluating the display quality of the two-dimensional code.

  The display quality evaluation means 40 in the reading unit 4 is a function standardized in a two-dimensional code reader, and in the quality evaluation of a matrix symbol two-dimensional code, decoding evaluation, symbol contrast evaluation, modulation evaluation, fixed pattern Functions such as failure evaluation, axis non-uniformity evaluation, grid non-uniformity evaluation, and unused error correction evaluation. Among them, as a function of generating information to be output from the display quality evaluation means 40 of the reading unit 4 to the control unit 3, a symbol contrast evaluation unit 41, a modulation evaluation unit 42, an axis non-uniformity evaluation unit 43, a grid A non-uniformity evaluation unit 44 is provided.

  The symbol contrast evaluation unit 41 is a function that evaluates whether or not light and darkness is sufficiently clear among symbols of a two-dimensional code. In general, the highest reflectance R max and the lowest reflectance R min of the evaluation target part are extracted using a gray scale image, and the difference is defined as a symbol contrast SC (= R max−R min). The symbol contrast evaluation unit 41 outputs the SC value as read information.

  The modulation evaluation unit 42 evaluates whether the reflectance of the bright module and the dark module of the two-dimensional code is in accordance with the standard. The module layout and the optical characteristics of the printing screen, which are outside the grid of the print, are likely to reduce the tolerance between the reflectance of the module and the global threshold, and these are evaluated as modulation MODs. . Modulation MOD has a relationship of MOD = 2 · (abs (R−GT)) / SC, where R is the reflectance of the module closest to the global threshold in the code, GT is the global threshold, and SC is the symbol contrast. (abs () is an absolute value). The modulation evaluation unit 42 reads the value of the modulation MOD and outputs it as information.

  The axis non-uniformity evaluation unit 43 evaluates how much the distance between the center positions of adjacent modules differs between the X axis and the Y axis (horizontal axis and vertical axis). In the matrix type symbol, data modules are arranged in a regular polygon, and the reference decoding algorithm maps the center positions of these modules in order to cut out data. For this reason, the deviation of the center position affects the decoding accuracy. The interval between the center positions of adjacent modules is extracted independently in each axial direction, and the interval is averaged along each axis. Axis non-uniformity AN is expressed as AN = abs (X avg−Y avg) / ((X avg + Yavg) / 2 (where abs (): absolute value, Xavg: X axis adjacent module) (Average value of center position interval, Yavg: Average value of center position interval of adjacent modules on Y axis) Axis non-uniformity evaluation unit 43 outputs the value of AN as read information.

  The grid non-uniformity evaluation unit 44 performs evaluation based on the deviation between the grid intersection extracted from the read two-dimensional code image and the theoretical position of the input print information. As the evaluation value GR, the maximum deviation between the read image and the theoretical position is output as a fraction of the symbol width in the X direction. The grid non-uniformity evaluation unit 44 outputs this value as read information.

  The control unit 3 acquires the read information (evaluation information) output from the display quality evaluation unit 40 described above, and controls the print output of the laser marking unit 2 based on the read information so that the display quality is improved. To do. Therefore, the control unit 3 includes a display quality improvement program for each evaluation item of the display quality evaluation means 40. Specifically, when the rank of the evaluation information output by the symbol contrast evaluation unit 41 is low, the print output is controlled to increase the rank, and the laser output adjustment unit 3A is operated to adjust the laser output to be increased. To do.

  Further, when the rank of the evaluation information output by the modulation evaluation unit 42 is low, the print output is controlled so as to raise this rank. Specifically, the marking data correction means 3B is operated based on the module thickness or thinning information, and the marking data input to the laser marking unit 2 is corrected.

  Further, when the rank of the evaluation information output by the non-axis uniformity evaluation unit 43 or the grid non-uniformity 44 unit is low, the print output is controlled so as to raise these ranks. Specifically, the marking data correction unit 3B is operated based on the grid intersection information to correct the marking data input to the laser marking unit.

  An operation example of the control unit 3 will be described. The control unit 3 operates the laser marking unit 2 to perform a marking operation based on the printing information of the input two-dimensional code. Next, the reading unit 4 is operated to read the printed two-dimensional code, and reading information output by the display quality evaluation unit 40 of the reading unit 4 is acquired.

  For example, when the rank of the evaluation information output by the symbol contrast evaluation unit 41 is low, the control unit 3 performs an output increase adjustment to improve the rank of the symbol contrast evaluation unit 41. Specifically, Low rank detection is performed when, for example, evaluation degradation is detected in two consecutive stages, or when rank degradation is detected with a probability of 1/3 (33%) in multiple evaluations. Whenever it is detected that the rank is low, the output is gradually increased (for example, every 1%). If the output is gradually increased and the rank of the symbol contrast evaluation unit 41 does not improve, an alarm is generated to confirm that the evaluation value is lowered due to the influence of the surface roughness of the workpiece. .

  When the rank of the evaluation information output from the modulation evaluation unit 42 is low, for example, taking a QR code (registered trademark) cut-out symbol as an example, the cell size is 1: 1: 3: 1 as shown in FIG. 1 is basic, but when the workpiece is tilted with respect to laser irradiation, the ratio of the cell sizes may be shifted.

  In such a case, the reference ratio can be marked by correcting the marking data based on the ratio data read by the reading unit 4. For example, if a 2 mm cell is marked at 1.8 mm, it is reduced by a factor of 0.9, so if 2 / 0.9 = 2.22 mm is marked, it can be returned to the reference ratio. it can. Even in such a case, the rank drop is detected when it is detected that the rank is dropped continuously for two times, or the rank is lowered with a probability of 1/3 (33%) in a plurality of evaluations. If it is detected that the rank has dropped and the marking data correction as described above is not improved, there is a backlash in the work holding part, etc. An alarm is generated because there is a possibility that something has not been done.

  When the rank of the evaluation information output from the non-axis uniformity evaluation unit 43 or the grid non-uniformity 44 unit is low, the code may be distorted and marked due to the curvature of the surface of the workpiece. In such a case, marking with less distortion can be performed by treating the difference between the read data of the coordinate value of each cell and the actual marking position as distortion correction data.

  For example, as shown in FIG. 3, when a positional deviation of -0.08 and -0.12 is detected in the range of Y0 to Y-1 on the X1 axis, the average of -0.1 is set. When re-correction data in the range of Y0 to Y-1 on the X1 axis line and positional deviations of -0.08 and -0.02 are detected in the range of Y-1 to Y-2, the average -0.05 is fed back as distortion correction data, for example, as recorrection data in the range of Y-1 to Y-2 on the X1 axis. Alternatively, the marking image itself may be corrected to mark the image distorted in the reverse direction, thereby marking the reference dimension.

  Even in such a case, the rank drop is detected when it is detected that the rank is dropped continuously for two times, or the rank is lowered with a probability of 1/3 (33%) in a plurality of evaluations. If it is detected that the rank has dropped, such as when detected, and if there is no improvement in the correction as described above, the distortion of the marking surface of the workpiece may not be stable, Generate an alarm.

  According to the two-dimensional code marking device 1 described above, it is possible to improve the deterioration of the display quality of the two-dimensional code caused by the state of the workpiece surface, and it is possible to reduce the frequency of occurrence of reading errors and erroneous readings. Further, in the improvement, the processing load on the control unit 2 can be reduced by using the standardized display quality evaluation function provided in the reading unit 4.

  In another embodiment, the laser marking unit 2, the control unit 3, and the reading unit 4 in the two-dimensional code marking device 1 are included in independent devices, and these devices are wired or wireless. It may be a connected two-dimensional code marking system.

  Moreover, in other embodiment, the laser marking part 2 and the control part 3, or the reading part 4 and the control part 3 may be comprised as one apparatus. For example, when the apparatus including the laser marker unit 2 is controlled by a PC or the like, the PC may further include the control unit 3. In this case, a device including the reading unit 4 is connected to the PC by wire or wirelessly.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and the design can be changed without departing from the scope of the present invention. Is included in the present invention. In addition, the above-described embodiments can be combined by utilizing each other's technology as long as there is no particular contradiction or problem in the purpose and configuration.

1: Two-dimensional code marking device, 2: Laser marking part,
3: control unit, 3A: laser output adjusting means, 3B: marking data correcting means,
4: Reading unit, 40: Display quality evaluation means,
41: Symbol contrast evaluation unit, 42: Modulation evaluation unit,
43: Axis non-uniformity evaluation unit, 44: Grid non-uniformity evaluation unit

Claims (4)

A laser marking unit, a control unit for controlling the print output of the laser marking unit, and a reading unit for reading a two-dimensional code printed by the laser marking unit,
The reading unit includes display quality evaluation means for evaluating the display quality of the printed two-dimensional code.
The control unit acquires the read information output from the display quality evaluation unit, and controls the print output of the laser marking unit based on the read information so that the display quality is improved. A two-dimensional code marking device.   2. The two-dimensional code marking device according to claim 1, wherein the control unit adjusts a laser output of the laser marking unit based on symbol contrast evaluation information output by the display quality evaluation unit.   3. The two-dimensional code according to claim 1, wherein the control unit corrects marking data input to the laser marking unit based on module thickness or thinness information output from the display quality evaluation unit. Marking device.   The said control part correct | amends the marking data input into the said laser marking part based on the grid intersection information which the said display quality evaluation means outputs, The any one of Claims 1-3 characterized by the above-mentioned. Two-dimensional code marking device.

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