Position correction device, position correction method, and program for laser printing device

Abstract

To easily correct a printing deviation caused by temperature drift, deformation of a printing object due to thermal effects from thermal conversion of laser light and the like.SOLUTION: A position correction device for a laser printing device includes: a first determination unit that determines a center point of a reference mark of a printing object; a laser printing instruction unit that instructs the laser printing device to form a laser mark with the center point of the reference mark as the center on the printing object; a second determination unit that determines the center point of the laser mark formed on the printing object; a correction amount calculation unit that calculates a correction amount so as to align the center point of the laser mark with the center point of the reference mark on the basis of the deviation between the center point of the reference mark by the first determination unit and the center point of the laser mark by the second determination unit; and a control unit that calculates a correction amount every time each segmented image of the input image that is laser-printed on the printing object is laser-printed and corrects the position of the segmented image that is laser-printed on the basis of the calculated correction amount.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a position correction device, a position correction method, and a program for a laser printing device. [Background technology]

[0002] Generally, when laser printing is performed on a printing target such as polycarbonate using a laser printing device, the printing position is adjusted so that the laser printing is performed at a predetermined position on the printing target.

[0003] However, even after adjustment has been performed once, the temperature of the laser marking device increases over time as the device is used, and the temperature environment changes from the time of adjustment due to the influence of temperature drift of the galvano scanner and the like.

[0004] Fig. 30 is a graph illustrating the effect of temperature drift of a galvanometer scanner, with the horizontal axis representing time (minutes) and the vertical axis representing the temperature drift amount (mm). Fig. 30 also shows the temperature drift in the X-axis direction and the temperature drift in the Y-axis direction.

[0005] As shown in Figure 30, the amount of temperature drift of the galvanometer scanner increases over time. That is, even after the position where laser marking is performed has been adjusted once, it will gradually deviate from the set position over time.

[0006] As long as this deviation is small enough to be ignored, there is no problem. However, if the deviation exceeds, for example, 0.2 mm, it becomes visible and cannot be ignored.

[0007] FIG. 30 shows that due to the temperature drift of the galvanometer scanner, the deviation in the X-axis direction becomes 0.2 mm or more 240 minutes after the cold start of the device, exceeding the allowable value.

[0008] Patent Document 1 discloses laser processing that reduces deviations in processing position caused by temperature changes in a laser processing device and a method for correcting the deviations in processing position.

[0009] Patent Document 1 discloses a technology for correcting the machining position deviation for each factor by setting in advance temperature measurement points and correction coefficients corresponding to area drift (deviation in a uniform direction) and scale drift (shrinkage), etc. Specifically, temperature sensors are installed on the scan mirror and the mirror mount, and the correction angles of the scan mirror and the mirror mount are grasped based on the temperatures of the scan mirror and the mirror mount measured by the temperature sensors.

[0010] Therefore, if an encoder for detecting the angles of these mirrors is provided in addition to the temperature sensor described above, the mirror angles can be grasped, making it possible to control the mirror angles according to the correction angle. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2005-40843 A Summary of the Invention [Problem to be solved by the invention]

[0012] However, installing a temperature sensor on the oscillating scan mirror and mirror mount, and installing an encoder, requires replacement of parts, which is extremely costly, and increases the cost of the laser marking device.

[0013] In addition, it is not easy to determine where on the oscillating scan mirror or mirror mount to set the temperature sensor in order to measure the temperature that is effective for correction. In other words, it is difficult to determine the optimal temperature measurement position itself, and there is a risk that the temperature drift will not be directly proportional to the temperature change. In this case, even if a temperature sensor is installed, high-precision correction cannot be expected.

[0014] Furthermore, when characters or figures printed by a laser printer are superimposed on figures or images printed by a printer such as a color printer, if the printer and the laser printer are independent devices, the inclination and size change of the figures or images caused by the printer are also added to the temperature drift of the laser printer. In this case, the misalignment cannot be eliminated by simply correcting the temperature drift.

[0015] In addition, when printing on a target object with a laser printing device, the target object itself is deformed due to the thermal effects of the laser light being converted into heat. The amount of deformation varies depending on the type and thickness of the material of the target object, the size of the printing area, etc., but when precise printing is required, the amount of deformation cannot be ignored.

[0016] As described above, even if a temperature sensor and encoder are installed in the laser printing device at great expense, it is not possible to accurately correct printing misalignment over time due to temperature drift. In addition, when laser printing by the laser printing device is superimposed on a figure or image printed by a printing device separate from the laser printing device, the printing misalignment due to temperature drift in the laser printing device will be superimposed on the printing misalignment due to the printing device, and the object to be printed itself will deform due to the thermal effects of the laser light being converted into heat, making it even more difficult to correct the misalignment.

[0017] An object of the present invention is to provide a position correction device, a position correction method, and a program for a laser marking device that solves the above-mentioned problems. [Means for solving the problem]

[0018] One aspect of the present invention is a position correction device for correcting the position of a laser marking device with respect to a printing object, the position correction device including a first determination unit that determines a center point of a reference mark provided in advance on the printing object, a laser marking instruction unit that instructs the laser marking device to form a laser mark on the printing object centered on the center point of the reference mark determined by the first determination unit, a second determination unit that determines the center point of the laser mark formed on the printing object by the laser marking device in response to the instruction, and a center point of the reference mark determined by the first determination unit and a laser marking instruction unit that instructs the laser marking device to form a laser mark on the printing object centered on the center point of the reference mark determined by the first determination unit. a correction amount calculation unit that calculates a deviation from the center point of the laser mark determined by the first judgment unit and calculates a correction amount for matching the center point of the laser mark with the center point of the reference mark based on the deviation; and a control unit that divides an input image to be laser-printed on the printing target into a predetermined number of divided images, calculates the correction amount using the first judgment unit, the laser printing instruction unit, the second judgment unit, and the correction amount calculation unit each time each divided image is laser-printed, and corrects the positions of the divided images to be laser-printed based on the calculated correction amount.

[0019] One aspect of the present invention is the position correction device described above, wherein the amount of correction includes at least one of a direction of correction, an amount of expansion / contraction, an amount of rotation, and an amount of distortion.

[0020] One aspect of the present invention is a position correction device as described above, wherein the laser printing instruction unit instructs the laser printing device to form laser marks of the same shape but with different magnifications on the printing target each time each divided image is laser printed.

[0021] One aspect of the present invention is a position correction device as described above, wherein the laser printing instruction unit instructs the laser printing device to form laser marks of different shapes on the printing target each time each divided image is laser printed.

[0022] One aspect of the present invention is a position correction device as described above, wherein the laser printing instruction unit instructs the laser printing device to form a new laser mark on the printing object at a position shifted by a predetermined position from the laser mark already formed on the printing object each time each divided image is laser printed.

[0023] One aspect of the present invention is a position correction device further comprising an imaging unit that images the printing target to obtain a first image, wherein the laser printing instruction unit instructs the laser printing device to form a new laser mark on the printing target near an end of each divided image, and the correction amount calculation unit obtains a positional relationship between the new laser mark and a reference mark from the first image and uses the obtained positional relationship to calculate the correction amount for each divided image.

[0024] One aspect of the present invention is a position correction device as described above, in which the number of divisions of the input image is determined in advance so that the correction amount for matching the center point of each laser mark with the center point of the corresponding reference mark can be updated within the amount of thermal deformation of the printing target itself due to the thermal effect of laser light being converted into heat, which is an amount of thermal deformation that does not result in visible shading lines at the boundaries between the divided images.

[0025] One aspect of the present invention is a position correction device in which, when performing position correction for each divided image, the control unit calculates the size of the gap between the divided image previously laser-printed and the divided image to be laser-printed this time based on an updated amount of position correction from the position correction amount of the divided image previously laser-printed, and performs image completion processing to fill the gap between the divided image previously laser-printed and the divided image to be laser-printed this time using an image of the calculated gap size.

[0026] One aspect of the present invention is a position correction method for a laser marking device, the method including a first determination step in which a processor determines a center point of a reference mark provided in advance on a printing object, a laser marking instruction step in which the processor instructs the laser marking device to form a laser mark on the printing object centered on the center point of the reference mark determined in the first determination step, a second determination step in which the processor determines the center point of the laser mark formed on the printing object by the laser marking device in response to the instruction, and a correction amount calculation step of determining a deviation from the center point of the laser mark determined in the second determination step, and calculating a correction amount for matching the center point of the laser mark with the center point of the reference mark based on the deviation; and a control step of the processor dividing an input image to be laser-printed on the printing target into a predetermined number of divided images, calculating the correction amount through the first determination step, the laser-printing instruction step, the second determination step, and the correction amount calculation step each time each divided image is laser-printed, and correcting the positions of the divided images to be laser-printed based on the calculated correction amount.

[0027] One aspect of the present invention is a program that causes a processor to realize: a first judgment function that judges a center point of a reference mark provided in advance on a printing target; a laser printing instruction function that instructs the laser printing device to form, on the printing target, a laser mark centered on the center point of the reference mark determined by the first judgment function; a second judgment function that judges the center point of the laser mark formed on the printing target by the laser printing device in response to the instruction; a correction amount calculation function that determines a deviation between the center point of the reference mark determined by the first judgment function and the center point of the laser mark determined by the second judgment function, and calculates a correction amount for matching the center point of the laser mark with the center point of the reference mark based on the deviation; and a control function that divides an input image to be laser-printed on the printing target into a predetermined number of divided images, calculates the correction amount using the first judgment function, the laser printing instruction function, the second judgment function, and the correction amount calculation function each time each divided image is laser-printed, and corrects the position of the divided image to be laser-printed based on the calculated correction amount. Effect of the Invention

[0028] According to the present invention, it is possible to obtain an effect that printing misalignment can be corrected without replacing parts of the laser marking device or installing new parts, and without causing a huge increase in cost. [Brief description of the drawings]

[0029] [Figure 1] 1 is a diagram showing a relationship between a position correction device to which a position correction method according to a first embodiment of the present invention is applied and a laser printing device. [Diagram 2] 1 is a perspective view showing the outer shape of a laser printing device in which a printing position is corrected by a position correction device; [Diagram 3] 1 is a block diagram showing an example of an electronic circuit configuration of a position correction device that implements a position correction method according to a first embodiment of the present invention. [Figure 4A] FIG. 2 is a plan view showing an example of a print target on which a color image and a reference mark are printed. [Figure 4B] 4B is a diagram for explaining laser marks formed by a laser marking device on the printing target shown in FIG. 4A. FIG. [Diagram 5] 10 is a flowchart showing an example of the operation of the position correction device. [Figure 6] 1 is a conceptual diagram showing an example of a laser mark formed by a combination of a plurality of line segments. [Figure 7] 1 is a conceptual diagram showing an example of a laser mark formed by a combination of a plurality of line segments. [Figure 8] 1 is a conceptual diagram showing an example of a laser mark formed by a combination of a plurality of line segments. [Figure 9] FIG. 1 is a conceptual diagram illustrating an example of a laser mark having an outline formed by dashed lines. [Figure 10] 7A to 7C are diagrams showing, in stages, how laser marks having the same shape as a reference mark are formed on a printing target according to a second embodiment of the present invention. [Figure 11] 11A to 11C are diagrams showing, for comparison with FIG. 10, a step-by-step process in which a laser mark having a different shape from a reference mark is formed on a printing target. [Figure 12] 10A and 10B are conceptual diagrams showing examples of the positional relationship between a reference mark and a laser mark, both of which are circular. [Figure 13] FIG. 13 is a plan view showing an example of a reference mark in the third embodiment of the present invention. [Figure 14] FIG. 13 is a diagram showing the concept of determining the position of a laser mark by binarization performed in a fourth embodiment of the present invention. [Figure 15] FIG. 13 is a diagram showing the concept of determining the position of a laser mark by processing using RGB conversion and synthesis performed in a fifth embodiment of the present invention. [Figure 16] FIG. 13 is a diagram for explaining an example of additive synthesis. [Figure 17] 13 is a flowchart showing an example of the operation of the position correction device according to the sixth embodiment of the present invention. [Figure 18] FIG. 23 is a diagram showing an example of divided images of an input image according to the sixth embodiment of the present invention. [Figure 19]FIG. 23 is a diagram showing an example of creating laser drawing data according to the sixth embodiment of the present invention. [Figure 20] FIG. 23 is a diagram showing an example of creating laser drawing data according to the sixth embodiment of the present invention. [Figure 21] FIG. 23 is a diagram showing an example of creating laser drawing data according to the sixth embodiment of the present invention. [Figure 22] 13A to 13C are diagrams showing examples of laser marks according to a sixth embodiment of the present invention. [Figure 23] FIG. 23 is a diagram showing an example of filling gaps between divided images according to the sixth embodiment of the present invention. [Figure 24] 13A to 13C are diagrams illustrating an example of laser marking according to the sixth embodiment. [Diagram 25] 13A to 13C are diagrams illustrating an example of laser marking according to the sixth embodiment. [Figure 26] 13A to 13C are diagrams illustrating an example of laser marking according to the sixth embodiment. [Figure 27] 13A to 13C are diagrams illustrating an example of laser marking according to the sixth embodiment. [Figure 28] 13A to 13C are diagrams illustrating an example of laser marking according to the sixth embodiment. [Figure 29] 13 is a diagram showing a state in which the center point of a circular reference mark and the center point of a rectangular laser mark coincide with each other. FIG. [Diagram 30] 1 is a graph illustrating the effect of temperature drift of a galvanometer scanner. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, a position correction device to which a position correction method according to each embodiment of the present invention is applied will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as the actual ones. Even when the same part is shown, the dimensions and ratios of each part may be shown differently depending on the drawing. In this specification and each drawing, elements similar to those described above with respect to the previous drawings are given the same reference numerals, and detailed descriptions are omitted as appropriate.

[0031] (First embodiment) FIG. 1 is a diagram showing the relationship between a position correction device to which a position correction method according to a first embodiment of the present invention is applied and a laser printer.

[0032] The position correction device 10 is a device for correcting the printing position of the laser printer 100 with respect to the printing target.

[0033] The position correction device 10 may be provided outside the laser marking device 100 as shown in FIG. 1(a), or may be built into the laser marking device 100 as shown in FIG. 1(b).

[0034] FIG. 2 is a perspective view showing the outer shape of the laser printer 100 in which the printing position is corrected by the position correction device 10. As shown in FIG.

[0035] 2 shows a case where a laser printing device 100 (e.g., LP450 manufactured by Toppan Printing Co., Ltd.) is installed adjacent to a color printing device 115 (e.g., eP600 manufactured by Toppan Printing Co., Ltd.), but the laser printing device 100 and the color printing device 115 may be installed separately. In the example shown in FIG. 2, the position correction device 10 is provided built into the laser printing device 100 as in FIG. 1(b), but the position correction device 10 may be provided outside the laser printing device 100.

[0036] The laser printer 100 performs printing and marking on a printing object using a laser. The printing object is, for example, a card or a page of a booklet (for example, a booklet for a passport). The material of the printing object is, for example, plastic or paper. The plastic material is, for example, polycarbonate. For such a printing object, the color printer 115 may color print the CMY components using a color ribbon, and the laser printer 100 may mark the K component using a laser. The color printing may be done by printing pigment or dye ink. Printing with invisible ink may also be added. The invisible ink may be fluorescent ink or infrared absorbing ink.

[0037] In this case, for example, an image expressing personal data such as a face photo or an ID number can be separated into CMY and K components, overlaid on the color-printed CMY components, and the K component can be laser-marked, making it difficult to tamper with. Also, an image of only the K component can be printed by laser.

[0038] A pulsed laser can be used as the laser of the laser marking device 100. The laser can be a solid-state laser. The solid-state laser can be a semiconductor laser. Specific examples of the laser oscillation wavelength are 1064 nm or 532 nm. The laser marking device 100 can have one or more built-in lasers. The energy per pulse of the pulsed laser is preferably 0.1 mJ or more. The energy of one pulse can be adjusted depending on the material of the marking target. The pulse period can be 1 KHz or more and 1 MHz or less. The intensity of the marking can be modulated by this pulse period.

[0039] FIG. 3 is a block diagram showing an example of the electronic circuit configuration of a position correction device that implements the position correction method according to the first embodiment of the present invention.

[0040] In order to correct the printing position by the laser printing device 100, the position correction device 10 has, as its electronic circuitry, a CPU 12, a memory interface 14, a communication interface 15, an imaging unit 16, for example a camera, and a memory 20, which are connected to each other by a bus 11.

[0041] The memory 20 stores a reference mark center point determination program 21, a laser printing instruction program 22, a laser mark center point determination program 23, a correction amount calculation program 24, and a laser printing device control program 25. These programs 21 to 25 may be pre-stored in the memory 20, or may be read from an external recording medium 13 such as a memory card via the memory interface 14 and stored in the memory 20.

[0042] In addition to such an area that cannot be rewritten by the user, the memory 20 also has a writable data area 29 as an area for storing rewritable data.

[0043] CPU 12 is a calculation device. CPU 12 can be implemented as an IC chip. CPU 12 may be implemented with an f-ary vector calculation circuit. CPU 12 may be an FPGA. CPU 12 may include a GPU. CPU 12 controls the operation of each part of the circuit according to each program 21-25 stored in memory 20 so that software and hardware work together. Based on the calculation results by CPU 12, control signals are sent from communication interface 15 to laser printing device 100 to control the operation of laser printing device 100.

[0044] The communication interface 15 communicates with the laser printing device 100. The communication interface 15 and the laser printing device 100 can be connected via a serial cable, an optical cable, wirelessly, etc. Digital data can also be used for communication between the communication interface 15 and the laser printing device 100.

[0045] FIG. 4A is a plan view showing an example of a print target on which a color image and a reference mark are printed.

[0046] In addition to the color image shown as a facial photograph in the figure, the print target T is provided with a reference mark P in advance by a color printing device 115 such as the eP600.

[0047] The shape of the reference mark P can be a concentric circle shape, such as a double circle shape shown in Fig. 4A. In this case, the center of the concentric circles is the center point of the reference mark P.

[0048] The color of the reference mark P can be a pure color or a mixed color. The color of the reference mark P can also be formed as a single color or multiple colors.

[0049] The shapes of the reference marks P may be different. The reference marks P may be formed as a continuous line or as an interrupted line such as a dashed line or a dotted line. The line width of the reference marks P may be constant or may have multiple sections with different widths.

[0050] Considering that the reference mark P will be detected using template matching in OpenCV, it is preferable to provide at least three reference marks P on one printing target T. Accordingly, Fig. 4A shows an example in which three reference marks P, that is, reference marks P1, P2, and P3, are provided on one printing target T. Furthermore, it is preferable that the positional relationship between these three reference marks P1, P2, and P3 is such that a straight line connecting the reference mark P1 and the reference mark P2 is perpendicular to a straight line connecting the reference mark P2 and the reference mark P3.

[0051] Therefore, in the following, we will explain an example in which three reference marks P1, P2, and P3 are provided on one printing object T, and the straight line connecting reference mark P1 and reference mark P2 is perpendicular to the straight line connecting reference mark P2 and reference mark P3.

[0052] The imaging unit 16 captures an image of the printing target T, and outputs the image acquired by the imaging to the memory 20.

[0053] The reference mark center point determination program 21 determines the center points of all the reference marks P provided in advance on the printing object T, i.e., the center points of each of the reference marks P1, P2, and P3, based on the image output to the memory 20. The positions of the determined center points can be expressed by coordinates on the printing object T.

[0054] The laser printing instruction program 22 outputs the coordinates of each of the center points of the reference marks P1, P2, and P3 determined by the reference mark center point determination program 21 to the laser printing device 100, and instructs the laser printing device 100 to form a laser mark S on the printing object T with the center point of each of the reference marks P1, P2, and P3 as the center.

[0055] In response to this instruction, the laser marking device 100 irradiates the marking object T with a laser so as to form a laser mark S centered on the central points of the reference marks P1, P2, and P3.

[0056] FIG. 4B is a diagram for explaining laser marks formed by the laser marking device 100 on the printing target T shown in FIG. 4A.

[0057] By irradiating the laser by the laser marking device 100, the laser marks S1, S2, and S3 are formed on the printing object T by the laser irradiated so as to be centered on the central points of the reference marks P1, P2, and P3.

[0058] 4B, since the reference mark P has a double circle shape, the shape of the laser mark S is a cross shape from the viewpoints of making it easy to distinguish it from the reference mark P and making it easy to detect the center point. However, this shape of the laser mark S is just one example, and it may be a shape other than a cross shape as long as it is easy to distinguish it from the reference mark P and makes it easy to detect the center point.

[0059] It is preferable that the laser mark S is larger in both length and width than the reference mark P, that is, the width and length of the laser mark S are larger than those of the reference mark P. This makes it possible to easily distinguish the laser mark S from the reference mark P even if the center point of the reference mark P and the center point of the laser mark S coincide with each other.

[0060] In addition, the color of the laser mark S is not particularly limited, but it is desirable to set the color of the laser mark S to a different color from that of the reference mark P so that the laser mark S can be easily distinguished from the reference mark P. Therefore, for example, the color of the laser mark S can be a dark achromatic color. Specifically, the dark achromatic color can be black or gray.

[0061] In this way, by making not only the shape but also the color of the laser mark S different from that of the reference mark P, it becomes easier to distinguish between the reference mark P and the laser mark S.

[0062] However, even if the laser printing device 100 irradiates a laser so as to form a laser mark S whose center point coincides with the center point of the reference mark P, the center point of the reference mark P and the center point of the laser mark S do not coincide with each other due to the temperature drift and the like mentioned above.

[0063] Figure 4B shows an example in which, even though the laser printing device 100 irradiates the laser so that the center point of the laser mark S1 formed for the reference mark P1 coincides with the center point of the reference mark P1, the center point of the laser mark S2 formed for the reference mark P2 is shifted from the center point of the reference mark P2, and the center point of the laser mark S3 formed for the reference mark P3 is shifted from the center point of the reference mark P3,

[0064] The imaging unit 16 captures an image of the printing target T on which the laser marks S1, S2, and S3 are formed, and outputs the image acquired by imaging to the memory 20.

[0065] The laser mark center point determination program 23 determines the center points of all the laser marks S formed on the printing target T by the laser marking device 100, i.e., the laser marks S1, S2, and S3, from the image output to the memory 20. Then, it outputs the coordinates of the center points of each of the laser marks S1, S2, and S3.

[0066] The correction amount calculation program 24 calculates the deviations d1, d2, d3 between the center points of the reference marks P1, P2, P3 determined by the reference mark center point determination program 21 and the center points of the laser marks S1, S2, S3 determined by the laser mark center point determination program 23.

[0067] The deviations d1, d2, and d3 can be vector information including the magnitude and direction of deviation between the center point of each of the reference marks P1, P2, and P3 and the center point of each of the laser marks S1, S2, and S3. These deviations d1, d2, and d3 are caused by the positioning failure of the laser marking device 100 due to the above-mentioned temperature drift, etc.

[0068] In Figure 4B, the deviation d1 between the center point of the reference mark P1 and the center point of the corresponding laser mark S1, the deviation d2 between the center point of the reference mark P2 and the center point of the corresponding laser mark S2, and the deviation d3 between the center point of the reference mark P3 and the center point of the corresponding laser mark S3 are shown enlarged outside the printing object T.

[0069] The correction amount calculation program 24 further calculates a correction amount for matching the center point of each laser mark S1, S2, S3 with the center point of the corresponding reference mark P1, P2, P3 based on the magnitude and direction of the deviations d1, d2, d3. The correction amount can include the correction direction, the amount of expansion / contraction, the amount of rotation, the amount of distortion (e.g., aspect ratio), etc., either alone or in combination.

[0070] For example, as illustrated in FIG. 4B, when three reference marks P1, P2, and P3 are provided on one printing object T, the correction amount calculation program 24 calculates a correction amount that may include direction, amount of expansion / contraction, amount of rotation, amount of distortion (e.g., aspect ratio), etc. based on the magnitude and direction of the deviations d1, d2, and d3.

[0071] The laser printer control program 25 transmits the calculated correction amount to the laser printer 100 via the communication interface 15, and controls the printing operation of the laser printer 100 based on the correction amount.

[0072] As a result, the laser printer 100 performs laser printing on the printing target T in a state in which the printing position has been corrected based on the correction amount.

[0073] The position correction device 10 performs the following for each printing object T: determination of the center point of the reference mark P by the reference mark center point determination program 21, formation of the laser mark S by the laser printing instruction program 22, determination of the center point of the laser mark S by the laser mark center point determination program 23, calculation of the correction amount by the correction amount calculation program 24, and control of the laser printing device 100 by the laser printing device control program 25. That is, the position correction device 10 corrects the printing position by the laser printing device 100 every time before the laser printing device 100 prints on a new printing object T.

[0074] Next, an example of the operation of the position correction device 10 configured as above will be described.

[0075] FIG. 5 is a flowchart showing an example of the operation of the position correction device 10.

[0076] In the description of this operation example, the printing target T is, as an example, a booklet for a passport (hereinafter, referred to as a "passport booklet"). Therefore, the position correction device 10 operates according to the flow illustrated in Fig. 5 every time a passport booklet is transported to the laser printing device 100. Three reference marks P1, P2, and P3 are printed on the transported passport booklet, as illustrated in Fig. 4A.

[0077] In the position correction device 10, the image of the printing target T is captured by the imaging unit 16, and the image acquired by the imaging is output to the memory 20. Based on this image, the center points of all the reference marks P provided in advance on the printing target T, i.e., the center points of the reference marks P1, P2, and P3, are determined by the reference mark center point determination program 21. The positions of the determined center points are represented by coordinates on the printing target T (ST1).

[0078] Next, the coordinates of the center points of the reference marks P1, P2, and P3 are output to the laser printing device 100 by the laser printing instruction program 22, and the laser printing device 100 is instructed to form a laser mark S centered on the center points of the reference marks P1, P2, and P3.

[0079] In response to this instruction, the laser printer 100 irradiates the marking object T with a laser so as to form a laser mark S whose center point coincides with the center points of the reference marks P1, P2, and P3 (ST2).

[0080] As a result, laser marks S1, S2, and S3 corresponding to the reference marks P1, P2, and P3 are formed on the passport booklet. However, even if the laser printer 100 irradiates the laser to form a laser mark S whose center point coincides with the center point of the reference mark P, the center points of the reference marks P1, P2, and P3 do not coincide with the center points of the corresponding laser marks S1, S2, and S3 due to the above-mentioned temperature drift, etc.

[0081] The printing target T on which the laser marks S1, S2, and S3 are formed is imaged by the imaging unit 16, and the image acquired by imaging is output to the memory 20.

[0082] Based on this image, the center point of each of the laser marks S1, S2, and S3 is determined by the laser mark center point determination program 23, and the coordinates of the center point of each of the laser marks S1, S2, and S3 are output (ST3).

[0083] Next, the correction amount calculation program 24 determines the deviations d1, d2, d3 between the center points of the reference marks P1, P2, P3 and the center points of the corresponding laser marks S1, S2, S3 (ST4).

[0084] The correction amount calculation program 24 further calculates the correction amount for matching the center points of the laser marks S1, S2, S3 with the center points of the corresponding reference marks P1, P2, P3 based on the magnitude and direction of the deviations d1, d2, d3 (ST5).

[0085] The correction amount is transmitted to the laser printing device 100 via the communication interface 15 by the laser printing device control program 25. As a result, the laser printing device 100 performs laser printing on the printing object T while being controlled based on the correction amount (ST6).

[0086] In this manner, the laser printing by the laser printer 100 is controlled, and the laser printing is performed at the correct position on the printing object T (for example, the correct place on the passport booklet) (ST7).

[0087] When the laser printing in ST7 is completed and the next passport booklet is transported to the laser printing device 100 (ST8: Yes), the process returns to step ST1, and the operations of steps ST1 to ST7 are performed on the next passport booklet, and the laser printing is performed in the correct position on the printing object T.

[0088] When laser printing on all passport booklets is completed (ST8: No), the process ends.

[0089] As described above, according to the position correction device 10 to which the position correction method according to the first embodiment of the present invention is applied, the printing position of the laser printing device 100 is corrected for each printing object T immediately before laser printing. This minimizes the influence of printing misalignment that occurs over time, and enables correct laser printing at the correct position, thereby making it possible to stabilize the printing quality.

[0090] Moreover, this correction does not require replacement of parts of the laser printer 100 or installation of new parts, and can therefore be achieved at low cost.

[0091] Thus, according to the first embodiment of the present invention, it is possible to realize accurate position correction for the laser printing device 100 without changing the hardware of the laser printing device 100, and without incurring significant cost, by using the software built into the position correction device 10.

[0092] Second embodiment A second embodiment of the present invention will now be described. Here, the same reference numerals are used for the components already described, and the description will be omitted.

[0093] The second embodiment relates to a technique for reducing the influence of the reference mark P and the laser mark S on the design of the printing object T. For this reason, in the second embodiment, the laser marking device control program 25 causes the laser marking device 100 to form a laser mark S having the same outer shape as the reference mark P but a different size from the reference mark P.

[0094] As a result, for example, if the size of the reference mark P is larger than the size of the laser mark S, when the center point of the reference mark P and the center point of the laser mark S are approximately aligned, the laser mark S is formed inside the reference mark P. Therefore, even if both the reference mark P and the laser mark S are formed, they are seen as if they were only one mark. Therefore, even if the reference mark P and the laser mark S are formed on the printing object T, the effect of reducing the impact of the deterioration of the design of the printing object T due to the formation of the reference mark P and the laser mark S is achieved.

[0095] For example, as illustrated in FIG. 4A, if three reference marks P1, P2, and P3 are formed on the printing object T, when laser marks S1, S2, and S3 are formed by the laser printing device 100, a total of six marks will be formed on the printing object T, which may result in a reduction in the design of the printing object T.

[0096] However, according to this embodiment, when the center point of the reference mark P and the center point of the laser mark S are approximately aligned, the reference mark P and the corresponding laser mark S appear as if they were a single mark. Therefore, when three reference marks P1, P2, and P3 are formed on the printing object T, even though a total of six marks are formed, only three marks are recognized, thereby reducing the impact of degrading the design of the printing object T.

[0097] Furthermore, in this embodiment, the laser marking device control program 25 can cause the laser marking device 100 to form, on the printing object T, a laser mark S formed by a combination of a plurality of line segments.

[0098] 6, 7, and 8 are conceptual diagrams showing examples of a laser mark S formed by combining a plurality of line segments.

[0099] FIG. 6 shows an example of a laser mark S that is formed by arranging multiple solid lines of different lengths in parallel at regular intervals so that it appears circular overall.

[0100] FIG. 7 shows an example of a laser mark S that is formed by arranging a plurality of line segments of equal length in parallel at regular intervals so that the overall shape appears to be a rectangle.

[0101] FIG. 8 shows an example of a laser mark S formed by arranging a plurality of solid lines of different lengths in parallel at regular intervals so that the overall shape appears to be a diamond.

[0102] Furthermore, in this embodiment, the laser printer control program 25 can also cause the laser printer 100 to form, on the printing object T, a laser mark S having an outline formed by a dashed line or a dotted line.

[0103] FIG. 9 is a conceptual diagram showing an example of a laser mark S having an outline formed by a dashed line.

[0104] 9 shows an example of a laser mark S that appears as a circle with its outer diameter (outline) formed by a dashed line. It will be clear to one skilled in the art that the dashed line can also be replaced by a dotted line.

[0105] 6, 7, 8, and 9 can be realized by the laser printing instruction program 22 causing the laser printing device 100 to print in a hatching pattern instead of in a solid color. By not using a solid color, the laser mark S can be made less noticeable on the printing object T, which has the effect of further reducing the impact of the formation of the laser mark S on the design of the printing object T.

[0106] The effects achieved by this embodiment will be described with reference to FIGS.

[0107] FIG. 10 is a diagram showing, in stages, how a laser mark S having the same shape as a reference mark P is formed on a printing target T according to the second embodiment of the present invention.

[0108] FIG. 11 is a diagram showing, for comparison with FIG. 10, a step-by-step process in which a laser mark S having a different shape from the reference mark P is formed on the printing target T.

[0109] 10(a) shows a print target T on which the CMY components of a facial photograph and three reference marks P1 to P3 have been color-printed by a color printing device 115. The reference marks P1 to P3 are all circular, but have different sizes (radii), with the reference marks P2 being the largest, followed by P1 and P3.

[0110] Fig. 10(b) shows the printing target T on which laser marks S1-S3 have been formed by the laser marking device 100 from the state of Fig. 10(a). The shapes of the laser marks S1-S3 are circular, the same as the reference marks P1-P3. Furthermore, the outlines of the laser marks S1-S3 are formed by dashed lines, as shown in Fig. 9. Fig. 10(c) shows the printing target T on which the K component has been printed by the laser marking device 100 from the state of Fig. 10(b).

[0111] In the state of FIG. 10(b), three laser marks S1-S3 are formed in addition to three reference marks P1-P3. Therefore, in the state of FIG. 10(b) and FIG. 10(c), a total of six marks are formed on the printing target T. However, if the center points of the reference marks P1, P2, and P3 and the center points of the laser marks S1, S2, and S3 are approximately aligned, the laser marks S1-S3 are formed inside the corresponding reference marks P1-P3 and as dashed lines, so they are not noticeable. As a result, even though six marks are formed on the printing target T, they appear as if there are only three marks.

[0112] FIG. 11(a) is the same as FIG. 10(a).

[0113] Fig. 11(b) also shows the printing target T on which laser marks S1-S3 have been formed by the laser printing device 100 from the state of Fig. 11(a), but the shape of the laser marks S1-S3 is a cross shape made up of solid lines as shown in Fig. 4B. Fig. 11(c) shows the printing target T on which the K component has been printed by the laser printing device 100 from the state of Fig. 11(b).

[0114] 10(b), three laser marks S1 to S3 are formed in addition to the three reference marks P1 to P3. The three laser marks S1 to S3 are in the shape of a cross made up of solid lines, and can be distinguished from the corresponding reference marks P1 to P3. As a result, six marks consisting of the three reference marks P1 to P3 and the three laser marks S1 to S3 are recognized on the printing object T. This may result in a decrease in the design quality of the printing object T.

[0115] However, according to this embodiment, as described with reference to Fig. 10, the reference marks P and the laser marks S, which require a minimum of six marks in total, can be made to appear as if only three marks are visible, thereby reducing the impact of loss of design of the printing object T. Furthermore, the laser marks S can be made less noticeable by forming them as discontinuous lines such as dashed lines.

[0116] Incidentally, when the reference mark P and the laser mark S have the same shape, and the center point of the reference mark P is slightly offset from the center point of the laser mark S, it may be difficult to determine whether the laser mark S is an outer circle or an inner circle of the reference mark P by commonly used pattern matching. This will be explained with reference to FIG.

[0117] FIG. 12 is a conceptual diagram showing an example of the positional relationship between a reference mark P and a laser mark S, both of which are circular.

[0118] 12A shows the positional relationship when the center point of the reference mark P coincides with the center point of the laser mark S. In this case, the laser mark S is formed concentrically with the reference mark P.

[0119] 12(b) shows the positional relationship when the center point of the reference mark P is slightly offset from the center point of the laser mark S. In this case, the laser mark S is not formed concentrically with the reference mark P, and it is difficult to determine whether the laser mark S is the outer circle or the inner circle of the reference mark P by commonly used pattern matching.

[0120] In such a case, by using color-converted image data for the reference mark P and performing specific achromatization, it becomes easy to determine whether the laser mark S is the outer circle or the inner circle of the reference mark P.

[0121] (Third embodiment) A third embodiment of the present invention will be described. Again, the same reference numerals are used for the same components as those already mentioned, and the description thereof will be omitted.

[0122] The third embodiment also relates to a technique for reducing the influence of the reference mark P and the laser mark S on the design of the print object T. For this reason, in the third embodiment, the reference mark P is printed on the print object T by the color printing device 115 at the boundary of the print object T so as not to stand out.

[0123] FIG. 13 is a plan view showing an example of a reference mark P in the third embodiment of the present invention.

[0124] That is, in this embodiment, the reference mark P printed on the printing object T is formed by a vertex d1 at the boundary of a rectangular shape formed by dotted lines surrounding the printing object T, and four points d2 to d5 surrounding the vertex d1, as shown in Figure 12(a) and Figure 12(b), which is an enlarged partial view of Figure 12(a).

[0125] In this case, the vertex d1 located at the center of the four points d2 to d5 corresponds to the center point of the reference mark P. Of the four points d2 to d5 surrounding the vertex d1, two points (points d2 and d3 in the case shown in FIG. 13(b)) are located on two perpendicular sides of the rectangular shape, and the other two points (points d4 and d5 in the case shown in FIG. 13(b)) are located on the extensions of each of these two sides.

[0126] In this way, by forming the reference mark P with a plurality of points d1 to d5, it is possible to make the reference mark P less noticeable.

[0127] As described above, according to this embodiment, the reference mark P printed on the printing object T can be made inconspicuous, thereby reducing the impact of loss of design of the printing object T.

[0128] Furthermore, by combining this embodiment with the second embodiment, it is possible to obtain a combined effect of the effect achieved by this embodiment and the effect achieved by the second embodiment.

[0129] (Fourth embodiment) A fourth embodiment of the present invention will now be described. Here, the same reference numerals are used for the components already mentioned, and the description thereof will be omitted.

[0130] In this embodiment, a color filter is applied to the imaging unit 16, and the image is further binarized, so that the position of the laser mark S is determined with high accuracy.

[0131] In this embodiment, the imaging unit 16 uses a specific color filter to image the printing object T on which a magenta circular reference mark P (e.g., reference marks P1, P2, P3) is printed simultaneously with the personal data in CMY, and the image obtained by imaging is output to the memory 20.

[0132] FIG. 14 is a diagram showing the concept of determining the position of a laser mark by binarization performed in the fourth embodiment of the present invention.

[0133] For simplicity, only one reference mark P1 and one laser mark S1 are shown in Fig. 14. However, in the following description, it is assumed that three reference marks P1, P2, and P3 are printed on the printing target T, and three laser marks S1, S2, and S3 are formed accordingly.

[0134] As shown in FIG. 14(a), the laser mark center point determination program 23 determines the center points of the magenta circular reference marks P1, P2, and P3 based on the image captured by the imaging unit 16 and output to the memory 20, and outputs the coordinates of each center point.

[0135] The correction amount calculation program 24 calculates the distortion of the printing target T from the positional relationship of the center points of the reference marks P1, P2, and P3.

[0136] The laser printing instruction program 22 instructs the laser printing device 100 to form circular laser marks S1, S2, and S3 of the K component centered on the center points of the magenta circular reference marks P1, P2, and P3 on the printing target T. At this time, the laser printing device 100 does not output the coordinates of the center points of the reference marks P1, P2, and P3, but outputs coordinates corrected in accordance with the distortion calculated by the correction amount calculation program 24. This allows the laser printing device 100 to form the circular laser marks S1, S2, and S3 with high accuracy centered on the center points of the reference marks P1, P2, and P3, as exemplified in FIG. 14(b).

[0137] Next, the imaging unit 16 images the printing target T through a color filter (in this case, a red (R) filter is preferable, but a blue (B) filter is also acceptable) other than a color component (in this case, green (G) component) that is not included in the color of the reference marks P1, P2, and P3 (in this case, magenta), and outputs the image obtained by imaging to the memory 20, as illustrated in Figure 14(c).

[0138] In this image, circular magenta reference marks P1, P2, and P3 with a small density difference and circular K-component laser marks S1, S2, and S3 with a large density difference are observed against the background color red (R).

[0139] The laser mark center point determination program 23 converts this image into gray and binarizes it, as shown in FIG. 14(d), to extract only the black laser marks S1, S2, and S3.

[0140] Based on the results of this extraction, the correction amount calculation program 24 calculates the correction amounts for correcting color-related deviations, such as expansion and contraction of the laser marks S1, S2, and S3.

[0141] The laser marking device control program 25 transmits the calculated correction amount to the laser marking device 100 via the communication interface 15, and controls the operation of the laser marking device 100 based on the correction amount.

[0142] As a result, the laser printer 100 performs laser printing on the printing target T in a state in which the printing position has been corrected based on the correction amount.

[0143] In this manner, the position correction device according to this embodiment can control the operation of the laser marking device 100 so that laser marking is performed at the correct position on the printing object T.

[0144] Although the above description is for the case where the color of the reference mark P is magenta (M), the color of the reference mark P can also be cyan (C). When the color of the reference mark P is cyan (C), the imaging unit 16 can use a blue (B) color filter to obtain the same effect. The imaging unit 16 can also use a green (G) color filter, but this is not preferred because the color of the reference mark P has a small amount of green (G) components in cyan (C), narrowing the setting range of the binarization threshold.

[0145] Moreover, the color of the reference mark P can be yellow (Y). When the color of the reference mark P is yellow (Y), the same effect can be obtained by using a red (R) or green (G) color filter for the imaging unit 16.

[0146] Fifth embodiment A fifth embodiment of the present invention will be described below. Here, the same reference numerals are used for the components already mentioned, and the description will be omitted.

[0147] In this embodiment, unlike the fourth embodiment, a specific filter is not used in the imaging unit 16, but the captured color image is subjected to processing including RGB conversion and synthesis to accurately determine the position of the laser mark S.

[0148] In this embodiment, the imaging unit 16 images the printing object T on which a magenta circular reference mark P (e.g., reference marks P1, P2, P3) is printed simultaneously with the personal data in CMY, and the image obtained by imaging is output to the memory 20.

[0149] FIG. 15 is a diagram showing the concept of laser mark position determination by processing using RGB conversion and synthesis performed in the fifth embodiment of the present invention.

[0150] 15, for the sake of simplicity, only one reference mark P1 and one laser mark S1 are shown, as in Fig. 14. However, in the following description, it is assumed that three reference marks P1, P2, and P3 are printed on the printing target T, and three laser marks S1, S2, and S3 are formed accordingly.

[0151] As shown in Figure 15(a), the laser mark center point determination program 23 determines the center points of the magenta circular reference marks P1, P2, and P3 based on the image captured by the imaging unit 16 and output to the memory 20, and outputs the coordinates of each center point.

[0152] The correction amount calculation program 24 calculates the distortion of the printing target T from the positional relationship of the center points of the reference marks P1, P2, and P3.

[0153] The laser printing instruction program 22 instructs the laser printing device 100 to form laser marks S1, S2, and S3 centered on the center points of the magenta circular reference marks P1, P2, and P3 on the printing target T. Here, the laser marks S1, S2, and S3 are circular K components with different sizes from the reference marks P1, P2, and P3.

[0154] At this time, the laser printing device 100 does not output the coordinates of the center points of the reference marks P1, P2, and P3, but outputs coordinates of the center points corrected according to the distortion calculated by the correction amount calculation program 24. This allows the laser printing device 100 to form laser marks S1, S2, and S3, which are different in size from the reference marks P1, P2, and P3, with high accuracy, centered on the center points of the reference marks P1, P2, and P3, as exemplified in Fig. 15(b).

[0155] Next, the imaging unit 16 captures an image of the printing target T on which the laser marks S1, S2, and S3 are thus formed, and outputs the image acquired by imaging to the memory 20.

[0156] The laser mark center point determination program 23 converts this image to RGB as shown in FIG. 15(c), and then additively combines (adds color components) it with the image obtained in FIG. 15(a), as shown in FIG. 15(d).

[0157] FIG. 16 is a diagram for explaining an example of additive synthesis.

[0158] For example, as illustrated in FIG. 15(b), when RGB conversion is performed on each of the CMY color components of a printing target T on which laser marks S1, S2, and S3 corresponding to reference marks P1, P2, and P3 are formed, and the resulting result is as shown in FIG. 16.

[0159] 16, it is optimal to use magenta or yellow for the color marks, but even if a cyan mark is used, there is no practical problem since a sufficient density difference can be obtained between the cyan mark and the black laser mark. Alternatively, by adding further processing such as binarization, it becomes possible to perform more reliable position determination processing for the laser marks S1, S2, and S3.

[0160] As a result of such additive synthesis, as shown in FIG. 15(e), the densities of the color reference marks P1, P2, and P3 become extremely low, and only the black laser marks S1, S2, and S3 are extracted.

[0161] This enables the laser mark center point determination program 23 to easily determine the center points of the laser marks S1, S2, and S3.

[0162] According to this embodiment, as described above, it is possible to measure the position information of the adjacent color reference mark P and laser mark S, and perform the necessary deformation for the K component to perform highly accurate alignment.

[0163] Furthermore, by distinguishing colors, it is possible to set the reference mark P in close proximity while maintaining the position measurement accuracy of marks such as the reference mark P and the laser mark S, enabling high-precision positioning without compromising the design.

[0164] Based on the results of this extraction, the correction amount calculation program 24 calculates the correction amounts for correcting color-related deviations, such as expansion and contraction of the laser marks S1, S2, and S3.

[0165] The laser marking device control program 25 transmits the calculated correction amount to the laser marking device 100 via the communication interface 15, and controls the operation of the laser marking device 100 based on the correction amount.

[0166] As a result, the laser printer 100 performs laser printing on the printing target T with the printing position corrected based on the correction amount.

[0167] In this manner, the position correction device according to this embodiment can control the operation of the laser marking device 100 so that laser marking is performed at the correct position on the printing object T.

[0168] Sixth embodiment A sixth embodiment of the present invention will now be described. Here, the same reference numerals are used for the components already mentioned, and the description will be omitted.

[0169] When printing on a printing target with the laser printing device 100, the printing target itself is deformed due to the thermal effect of the laser light being converted into heat. The amount of deformation varies depending on the type and thickness of the material of the printing target, the size of the printing area, etc., but when precise printing is required, the amount of deformation cannot be ignored. The sixth embodiment relates to a technique for solving this problem.

[0170] FIG. 17 is a flowchart showing an example of the operation of the position correction device 10 according to the present embodiment.

[0171] In the description of this operation example, as in the description of the operation example of Fig. 5 described above, the printing object T is a passport booklet. Therefore, the position correction device 10 operates according to the flow illustrated in Fig. 17 every time a passport booklet is transported to the laser printing device 100. Three reference marks P1, P2, and P3 are printed on the transported passport booklet, as illustrated in Fig. 4A.

[0172] The position correction device 10 divides image data (input image) transmitted to and received by the laser printing device 100 into a predetermined number of parts. Here, as illustrated in Fig. 18, the position correction device 10 divides the input image G0 into three divided images G1, G2, and G3 (ST101).

[0173] Next, the position correction device 10 sequentially sets each of the divided images G1, G2, and G3 as a target divided image and executes the processes from step ST102 to step ST104.

[0174] In step ST102, the above-mentioned processes from step ST1 to step ST5 in Fig. 5 are performed on the target divided image. As a result, a correction amount for matching the center points of the laser marks S1, S2, and S3 with the center points of the corresponding reference marks P1, P2, and P3 is calculated for the target divided image.

[0175] In step ST103, the position correction device 10 creates laser drawing data based on the calculated correction amount from the target divided image (updating the target divided image). An example of creating laser drawing data is shown in Fig. 19 to Fig. 21.

[0176] In the example of creating the laser drawing data in FIG. 19, as shown in FIG. 19(a), the center points of the laser marks S1, S2, and S3 are shifted from the center points of the reference marks P1, P2, and P3 in the lower right direction in the figure. The position correction device 10 corrects the target divided image data based on the correction amount of the shift in the lower right direction in the figure. In the example of FIG. 19(b), the divided image G2 is the target divided image, and the data of the target divided image G2 is corrected so that the position of the target divided image G2 is moved based on the correction amount to eliminate the shift. By this correction, the position of the corrected target divided image G2' becomes the position when the center points of the laser marks S1, S2, and S3 coincide with the center points of the corresponding reference marks P1, P2, and P3. The position correction device 10 creates the laser drawing data of the target divided image G2' from the target divided image G2'. In the example of FIG. 19(c), the target divided image G2' is made into rectangular data so that it can be actually laser scanned.

[0177] In the example of creating the laser drawing data in FIG. 20, as shown in FIG. 20(a), the center points of the laser marks S1, S2, and S3 are inclined in the CW direction (clockwise rotation direction) from the center points of the reference marks P1, P2, and P3. The position correction device 10 corrects the target divided image data based on the correction amount of the inclination in the CW direction. In the example of FIG. 20(b), the divided image G2 is the target divided image, and the data of the target divided image G2 is corrected so that the position of the target divided image G2 is rotated in the counterclockwise rotation direction based on the correction amount to eliminate the inclination. With this correction, the position of the corrected target divided image G2' becomes the position when the center points of the laser marks S1, S2, and S3 coincide with the center points of the corresponding reference marks P1, P2, and P3. The position correction device 10 creates the laser drawing data of the target divided image G2' from the target divided image G2'. In the example of FIG. 20(c), the target divided image G2' is converted into rectangular data so that it can actually be laser scanned.

[0178] In the example of creating the laser drawing data in FIG. 21, as shown in FIG. 21(a), the center points of the laser marks S1, S2, and S3 spread outward from the center points of the reference marks P1, P2, and P3. The position correction device 10 corrects the target divided image data based on the correction amount of the outward spread. In the example of FIG. 21(b), the divided image G2 is the target divided image, and the data of the target divided image G2 is corrected so that the target divided image G2 is reduced based on the correction amount to eliminate the spread. By this correction, the position of the corrected target divided image G2' becomes the position when the center points of the laser marks S1, S2, and S3 coincide with the center points of the corresponding reference marks P1, P2, and P3. The position correction device 10 creates the laser drawing data of the target divided image G2' from the target divided image G2'. In the example of FIG. 21(c), the target divided image G2' is made into square data so that it can be actually laser scanned.

[0179] In step ST104, the laser drawing data of the target divided image is sent to the laser printing device 100, and the laser printing device 100 performs laser printing of the laser drawing data of the target divided image on the printing target T. As a result, the target divided image is laser printed at the correct position on the printing target T.

[0180] In step ST105, it is determined whether or not there is a next divided image. If there is a next divided image, the next divided image is treated as the target divided image and the processes from step ST102 to step ST104 are executed. On the other hand, if all divided images have been treated as the target divided images and the processes from step ST102 to step ST104 have been executed, it is determined that there is no next divided image, and the process proceeds to step S106.

[0181] Step ST106 is the same as step ST8 in Fig. 5. When the next passport booklet is transported to the laser printer 100 (ST106: Yes), the process returns to step ST101, and the operations from step ST101 to step ST105 are performed on the next passport booklet as well, and laser printing is performed on the correct position on the printing target T for each target divided image.

[0182] When laser printing on all passport booklets is completed (ST106: No), the process ends.

[0183] The above-mentioned steps ST101, ST103-ST105 are realized by the laser marking device control program 25 as an example of this embodiment. Specifically, steps ST101, ST103-ST105 are realized by the CPU 12 as the control unit of the position correction device 10 executing the laser marking device control program 25 stored in the memory 20. The above-mentioned steps ST102 (ST1-ST5) and step ST106 (ST8) are the same as those in the first embodiment.

[0184] As described above, according to the position correction device 10 to which the position correction method according to the sixth embodiment of the present invention is applied, the printing position of the laser printing device 100 is corrected for each target divided image for each printing object T immediately before laser printing. Therefore, even if the printing object itself is deformed due to the thermal effect of the laser light being converted into heat, the influence of printing deviation that occurs over time can be minimized, and correct laser printing can be performed in the correct position, thereby making it possible to stabilize the printing quality.

[0185] Moreover, this correction does not require replacement of parts of the laser printer 100 or installation of new parts, and can therefore be achieved at low cost.

[0186] Thus, according to the sixth embodiment of the present invention, it is possible to realize accurate position correction for the laser printing device 100 without changing the hardware of the laser printing device 100, and without incurring significant cost, by using the software built into the position correction device 10.

[0187] In the sixth embodiment, laser marks are drawn near the reference mark as many as the number of target divided images (as many as the number of divisions of the input image). Therefore, by drawing laser marks of the same shape with different magnifications, it is possible to easily distinguish from laser marks that have already been drawn. Alternatively, by drawing laser marks of different shapes or drawing a new laser mark at a position shifted from the already drawn laser marks by a predetermined position, it is also possible to easily distinguish from laser marks that have already been drawn.

[0188] Fig. 22(a) is an example of drawing laser marks of the same shape but different magnification ratios. In Fig. 22(a), laser marks S1, S2, and S3 of the same shape (circle) but different magnification ratios are drawn inside a reference mark P when the number of divisions of an input image is 3.

[0189] Fig. 22(b) is an example of drawing laser marks of different shapes. In Fig. 22(b), laser marks of different shapes (circle, square, triangle) S1, S2, S3 are drawn inside the reference mark P when the division number of the input image is 3.

[0190] In the sixth embodiment, when the input image is divided into many parts, many laser marks are arranged near the reference mark. In this case, the image captured by the imaging unit 16 includes complicated figures, making it difficult to distinguish between the laser marks, and there is a possibility that errors may increase when calculating the correction amount for matching the center point of each laser mark with the center point of the corresponding reference mark. To address this issue, the position correction device 10 may provide a new laser mark near the end of each divided image, obtain the positional relationship between this new laser mark and the reference mark by imaging, and use the obtained positional relationship to calculate the correction amount. Alternatively, multiple reference marks may be placed close to the ends of each divided image, and the positional relationship between the center of the reference mark corresponding to each divided image and a new laser mark placed near the end may be imaged to calculate the correction amount. When using this method, it is desirable that the multiple reference marks are printed on the same plate with the same ink. They may also be printed in different colors using the same printing device. The shapes of the reference marks may be the same or different. Auxiliary marks may also be placed between the reference marks.

[0191] In the sixth embodiment, different position corrections are performed on each divided image to make the center point of each laser mark coincide with the center point of the corresponding reference mark. Therefore, a visible shading line may appear at the boundary between divided images as a result of drawing each divided image. This results in aesthetic quality degradation. To address this issue, the number of divisions of the input image may be determined in advance so that the amount of correction for matching the center point of each laser mark with the center point of the corresponding reference mark can be updated while the amount of deformation (thermal deformation amount) of the printing target itself caused by the thermal effect of the laser light being converted into heat is small (amount of thermal deformation amount at which shading lines do not appear).This makes it possible to suppress the occurrence of shading lines.

[0192] The amount of thermal deformation varies greatly depending on the type and thickness of the material of the printing target. In addition, when the drawing area is large, the amount of heat accumulated in the printing target increases, so it is important to adopt a division number that matches the printing conditions. Here, as the division number increases, the impact of productivity deterioration increases, such as an increase in the time required for laser mark printing and correction calculation. To address this issue, when performing position correction for each divided image, the position correction device 10 may calculate the size of the gap between the previous target divided image and the current target divided image based on the update amount of position correction from the amount of position correction of the previous target divided image, and fill the gap between the previous target divided image and the current target divided image using an image with the calculated gap size.

[0193] FIG. 23 is an example of filling a gap between target divided images. As illustrated in FIG. 23, the gap between the drawn target divided image G1' and the target divided image G2' is complemented by copying the lines at the end of the target divided image G2' on the target divided image G1' side. When performing position correction on the current target divided image G2, the position correction device 10 calculates the size of the gap (the number of lines required to fill the gap) between the previous target divided image G1' and the current target divided image G2' based on the update amount of position correction from the previous position correction amount of the target divided image G1. The position correction device 10 copies the lines at the end of the target divided image G2' on the target divided image G1' side by the calculated gap size, and adds the copies to the end of the target divided image G2' on the target divided image G1' side, thereby generating a target divided image G2' in which the gap with the target divided image G1' is complemented. The position correction device 10 creates laser drawing data for the target divided image G2' from the complemented target divided image G2'. By drawing the laser drawing data of this target divided image G2', there is no gap with the target divided image G1', and deterioration in aesthetic quality can be prevented.

[0194] 24 to 28 are examples of laser printing according to the sixth embodiment. The examples of laser printing in Figs. 24 to 28 are for a first image G10, which is a CMY line pattern, and a test image for testing the color expression of cyan is printed by selectively concealing only the magenta and yellow parts with black using a second image G20. At this time, as printing progresses, it is considered that the printing object itself will deform due to the thermal effect of the laser light being converted into heat. Here, an example will be described in which the printing object stretches in the sub-scanning direction as printing progresses.

[0195] In the case of alignment only before printing starts as in the first embodiment described above, if the printing target extends in the sub-scanning direction during printing, the amount of misalignment in the sub-scanning direction accumulates, and the pitch of the drawn lines gradually becomes misaligned. As a result, it becomes impossible to selectively cover only the magenta and yellow parts with black, and it is not possible to accurately create a test image for testing the color expression of cyan.

[0196] However, according to the sixth embodiment, as shown in Fig. 25, the second image G20 is divided into three divided images G21, G22, and G23, and the divided images G21, G22, and G23 are aligned with each other to prevent the accumulation of deviations in the extending sub-scanning direction and prevent the pitch of the drawn lines from becoming misaligned. This allows for the accurate creation of a test image for testing the color expression of cyan. The idea of ​​preventing the accumulation of deviations is also effective for deviations in angle, size, and distortion.

[0197] In Fig. 26, the divided image G21 is printed as a target divided image after being subjected to position correction with respect to the first image G10. In this position correction in Fig. 26, the positions of the laser marks S1, S2, and S3 are corrected so that their center points coincide with the center points of the corresponding reference marks P1, P2, and P3.

[0198] Next, in Fig. 27, after the divided image G21 is printed, the divided image G22 is corrected in position as a target divided image with respect to the first image G10 and then printed. In the position correction in Fig. 27, the positions of the laser marks S11, S21, and S31 are corrected so that their center points coincide with the center points of the corresponding reference marks P1, P2, and P3.

[0199] Next, in Fig. 28, after the divided image G22 is printed, the divided image G23 is corrected in position as a target divided image with respect to the first image G10 and then printed. In this position correction in Fig. 28, the positions of the laser marks S12, S22, and S32 are corrected so that their center points coincide with the center points of the corresponding reference marks P1, P2, and P3.

[0200] 26 to 28, by aligning each of the divided images G21, G22, and G23, the accumulation of deviation in the extending sub-scanning direction is suppressed, and it is possible to prevent the pitch of the drawing lines from becoming mismatched. This makes it possible to create a test image for testing the color expression of cyan with high accuracy.

[0201] Although the best mode for carrying out the present invention has been described above with reference to the attached drawings, the present invention is not limited to such a configuration. Within the scope of the technical idea of ​​the invention defined in the claims, a person skilled in the art may conceive of various modifications and alterations, and it is understood that such modifications and alterations also belong to the technical scope of the present invention.

[0202] For example, a typical example of the shape of the reference mark P and the laser mark S is a circle, but the shapes of the reference mark P and the laser mark S are not limited to a circle, and they can be any shapes different from each other.

[0203] FIG. 29 is a diagram showing a state in which the center point of a circular reference mark P and the center point of a rectangular laser mark S coincide with each other.

[0204] As shown in FIG. 29, the reference mark P may be a red circle and the laser mark S may be a rectangle.

[0205] Furthermore, in the present invention, pattern matching can be applied as necessary, but the algorithm is not particularly limited; for example, when using OpenCV, if the imaging lighting is stable and there is no disturbance, SSD (sum of squares of pixel value differences (squared error)) can be used, or in an environment where the imaging lighting is disturbed, NCC (normalized cross correlation) can be used, and any other appropriate method can be used. [Explanation of symbols]

[0206] 10...Position correction device 11 Bus 12 CPU 13. External recording media 14. Memory Interface 15 Communication Interface 16 Imaging unit 20. Memory 21. Reference mark center point judgment program 22 Laser printing instruction program 23 Laser mark center point judgment program 24. Correction amount calculation program 25 Laser printer control program 29. Writeable data area 100 Laser printer 115 Color printing device

Claims

1. A position correction device for correcting a position of a laser printer relative to a printing target, comprising: a first determination unit that determines a center point of a reference mark provided in advance on the printing target; a laser marking instruction unit that instructs the laser marking device to form a laser mark centered on the center point of the reference mark determined by the first determination unit, on the marking target; a second determination unit that determines a center point of a laser mark formed on the printing target by the laser marking device in response to the instruction; a correction amount calculation unit that calculates a deviation between a center point of the reference mark determined by the first determination unit and a center point of the laser mark determined by the second determination unit, and calculates a correction amount for causing the center point of the laser mark to coincide with the center point of the reference mark based on the deviation; a control unit that divides an input image to be laser-printed on the printing target into a predetermined number of divided images, and calculates the amount of correction by the first determination unit, the laser-printing instruction unit, the second determination unit, and the correction amount calculation unit each time each divided image is laser-printed, and corrects the positions of the divided images to be laser-printed based on the calculated correction amounts; A position correction device comprising:

2. The correction amount includes at least one of a direction of correction, an amount of expansion / contraction, an amount of rotation, and an amount of distortion. The position correction device according to claim 1 .

3. the laser printing instruction unit instructs the laser printing device to form laser marks of the same shape but with different magnifications on the printing target every time each divided image is laser-printed; The position correction device according to claim 1 .

4. the laser printing instruction unit instructs the laser printing device to form a laser mark having a different shape on the printing target every time each divided image is laser printed. The position correction device according to claim 1 .

5. the laser printing instruction unit instructs the laser printing device to form a new laser mark on the printing target at a position shifted by a predetermined position from a laser mark already formed on the printing target every time each divided image is laser printed. The position correction device according to claim 1 .

6. An imaging unit that captures an image of the printing target to obtain a first image, the laser printing instruction unit instructs the laser printing device to form a new laser mark on the printing target near an end of each divided image; the correction amount calculation unit obtains a positional relationship between the new laser mark and a reference mark from the first image, and uses the obtained positional relationship to calculate the correction amount for each divided image. The position correction device according to claim 1 .

7. The number of divisions of the input image is determined in advance so that the amount of thermal deformation of the printing target itself due to the thermal effect of the laser light being converted into heat can be updated to a correction amount for matching the center point of each laser mark with the center point of the corresponding reference mark within the amount of thermal deformation in which no visible shading lines appear at the boundaries between the divided images. The position correction device according to claim 1 .

8. when performing position correction for each divided image, the control unit calculates a size of a gap between the divided image previously laser-printed and the divided image to be laser-printed this time based on an update amount of position correction from an amount of position correction for the divided image previously laser-printed, and executes an image complementation process for filling the gap between the divided image previously laser-printed and the divided image to be laser-printed this time using an image of the calculated gap size. The position correction device according to claim 1 .

9. 1. A position correction method for a laser printing device, comprising: A first determination step in which a processor determines a center point of a reference mark provided in advance on a printing target; a laser printing instruction step in which the processor instructs the laser printing device to form a laser mark on the printing target, the laser mark being centered on the center point of the reference mark determined in the first determination step; a second determination step in which the processor determines a center point of a laser mark formed on the target by the laser marking device in response to the instruction; a correction amount calculation step in which the processor determines a deviation between the center point of the reference mark determined in the first determination step and the center point of the laser mark determined in the second determination step, and calculates a correction amount for matching the center point of the laser mark with the center point of the reference mark based on the deviation; a control step in which the processor divides an input image to be laser-printed on the printing target into a predetermined number of divided images, and each time each divided image is laser-printed, calculates the correction amount through the first determination step, the laser-printing instruction step, the second determination step, and the correction amount calculation step, and corrects the positions of the divided images to be laser-printed based on the calculated correction amounts; A position correction method including:

10. A first determination function for determining a center point of a reference mark provided in advance on a printing target; a laser printing instruction function for instructing the laser printer to form a laser mark on the printing target, the laser mark being centered on the center point of the reference mark determined by the first determination function; a second determination function for determining a center point of a laser mark formed on the target by the laser marking device in response to the instruction; a correction amount calculation function that calculates a deviation between a center point of the reference mark determined by the first determination function and a center point of the laser mark determined by the second determination function, and calculates a correction amount for making the center point of the laser mark coincide with the center point of the reference mark based on the deviation; a control function of dividing an input image to be laser-printed on the printing target into a predetermined number of divided images, and calculating the amount of correction by the first determination function, the laser-printing instruction function, the second determination function, and the correction amount calculation function each time each divided image is laser-printed, and correcting the position of the divided image to be laser-printed based on the calculated amount of correction; A program that causes a processor to realize the above.

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