Register error detection device, printing device, coating device, register error detection method, and register error detection program

Abstract

This register error detection device 30 includes a printing element identification part 33 that identifies a predetermined printing element printed on a moving printed material. The printing element identification part 33 identifies at least one printing element on the basis of color information of the printing element. The register error detection device 30 further includes: a relative distance calculation unit 39 that calculates the relative distance, along the movement direction, of two printing elements including the printing element identified on the basis of the color information; and a register error detection unit 41 that detects a register error on the basis of the relative distance.

Description

Alignment error detection device, printing device, coating device, alignment error detection method, alignment error detection program 【0001】 The present disclosure relates to a technology for detecting an alignment error of a printing target or a coating target. 【0002】 A rotary press, which is a printing device that prints on a moving web, includes a plurality of printing units and sequentially prints each color such as cyan (C), magenta (M), yellow (Y), and black (K). Aligning the positions of the printing plates of each color is called "aligning the registration". For this purpose, as a technique, it is known to detect an alignment error, which is a misalignment of the printing plates of each color, and adjust the feeding speed of each part of the web and the rotational speed of the plate cylinder around which the printing plates of each color are wound so as to reduce the error. 【0003】 In Patent Document 1, for detecting an alignment error, each printing unit prints a registration mark at a predetermined position. The registration marks of each color are printed on the web at regular intervals, and adjacent registration marks are simultaneously detected by a mark sensor having two light detection elements arranged at the same intervals. The relative distance between these simultaneously detected registration marks and the deviation from the expected value are detected as an alignment error, and alignment control is performed to reduce it. 【0004】 In the so-called overprinting in which primary printing and secondary printing are performed on the same web, in the printing device of Patent Document 1, the registration marks of each color are printed at different positions in the primary printing and the secondary printing. At this time, by making the interval between the registration mark of the last color of the primary printing and the registration mark of the first color of the secondary printing coincide with the interval between the light detection elements of the mark sensor, the alignment error between the primary printing and the secondary printing can be detected. 【0005】 In Patent Document 2, the registration marks of each color are printed at equal intervals within a strip-shaped area extending in the moving direction of the web, and a cut mark is printed outside the strip-shaped area. By acquiring the rotational angle of the plate cylinder when the mark sensor detects the cut mark and calculating the rotational angle of the plate cylinder when the mark sensor detects the registration mark, the relative distance along the moving direction of the web between the cut mark and the registration mark can be calculated. 【0006】Japanese Patent Publication No. 2014-177019 Japanese Patent Publication No. 2022-85530 【0007】 In Patent Document 1, to prevent the mark sensor from misdetecting patterns or information other than marks, a time period during which each mark passes through the detection area of ​​the mark sensor is set as a gate, and marks can only be detected within the gate. Therefore, when there is a large registration error between the primary and secondary printing, such as during the initial printing of secondary printing, the register mark of the last color in the primary printing or the register mark of the first color in the secondary printing may fall outside the gate, making it impossible to detect the registration error. 【0008】 Patent Document 2 states that it is necessary to pre-print cut marks, and that a mark sensor is required in which a detection element for detecting cut marks and a detection element for detecting register marks are spaced apart in a direction perpendicular to the direction of movement of the rolled paper. 【0009】 This disclosure is made in light of these circumstances, and its purpose is to provide a technology that can effectively detect registration errors. 【0010】 To solve the above problems, a registration error detection device according to one aspect of the present disclosure includes a printing element identification unit that identifies a predetermined printing element printed on a moving workpiece. The printing element identification unit identifies at least one printing element based on the color information of the printing element. The registration error detection device further includes a relative distance calculation unit that calculates the relative distance along the direction of movement of two printing elements, including the printing element identified based on the color information, and a registration error detection unit that detects a registration error based on the relative distance. 【0011】 In this embodiment, registration errors can be detected by calculating the relative distance between printed elements using the color information of the printed elements. Therefore, even large registration errors can be handled, reference marks do not need to be printed in advance, and detection elements for cut mark detection do not necessarily need to be provided. Thus, registration errors can be detected effectively. 【0012】Another aspect of the present disclosure is a coating apparatus. This apparatus comprises a registration error detection device and a coating unit. The registration error detection device includes a coating element identification unit that identifies a predetermined coating element coated on a moving workpiece. The coating element identification unit identifies at least one coating element based on the color information of the coating element. The registration error detection device further includes a relative distance calculation unit that calculates the relative distance along the direction of movement of two coating elements, including the coating element identified based on the color information, and a registration error detection unit that detects a registration error based on the relative distance. The coating unit coats the coating element onto the workpiece. 【0013】 A further aspect of the present disclosure is a registration error detection method. This method includes the steps of: identifying a predetermined print element printed on a moving workpiece, by identifying at least one print element based on the color information of the print element; calculating a relative distance along the direction of movement of two print elements, including the print element identified based on the color information; and detecting a registration error based on the relative distance. 【0014】 A further aspect of the present disclosure is a registration error detection program. The program causes a computer to perform the following steps: identify a predetermined printing element printed on a moving workpiece, by identifying at least one printing element based on the color information of the printing element; calculate the relative distance along the direction of movement of two printing elements, including the printing element identified based on the color information; and detect a registration error based on the relative distance. 【0015】 Furthermore, any combination of the above components, as well as any representations thereof converted into methods, apparatus, systems, recording media, computer programs, etc., are also included in this disclosure. 【0016】 According to this disclosure, registration errors can be effectively detected. 【0017】This is a schematic diagram showing the configuration of a printing apparatus according to the first embodiment of this disclosure. This is a diagram showing the positional relationship of the register marks. This is a diagram showing the configuration of the printing unit. This is a block diagram showing the configuration of the registration error detection device in Figure 1. This is a schematic diagram showing how multiple register marks printed on a moving web are detected. This is a schematic diagram showing a printing unit that performs secondary printing for overprinting. This is a schematic diagram showing how multiple patterns printed on a moving web are detected. This is a schematic diagram showing the configuration of a coating apparatus according to the second embodiment of this disclosure. This is a block diagram showing the configuration of the registration error detection device in Figure 8. 【0018】 The following describes in detail the forms for implementing this disclosure (hereinafter also referred to as embodiments) with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc., are denoted by the same reference numerals, and redundant descriptions are omitted. The scale and shape of the illustrated parts are set for convenience in order to simplify the description and are not to be interpreted restrictively unless otherwise specified. The embodiments are illustrative and do not limit the scope of this disclosure in any way. Not all features or combinations thereof presented in the embodiments are necessarily essential to this disclosure. For convenience, embodiments are presented by breaking them down into components for each function and / or group of functions that realize them. However, one component in an embodiment may actually be realized by a combination of multiple separate components, and multiple components in an embodiment may actually be realized by a single integrated component. 【0019】[First Embodiment] Figure 1 schematically shows the configuration of a printing apparatus 10 according to the first embodiment of the present disclosure. The printing apparatus 10 includes a first printing unit 11A that prints black (K), a second printing unit 11B that prints cyan (C), a third printing unit 11C that prints magenta (M), a fourth printing unit 11D that prints yellow (Y), and a registration error detection device 30. Hereinafter, the first printing unit 11A to the fourth printing unit 11D will be collectively referred to as the printing unit 11. Note that the printing colors of each printing unit 11 are not limited to those above, and any printing colors can be assigned to each printing unit 11 in any order. Furthermore, five or more printing units may be provided in order to print more colors. 【0020】 The first printing unit 11A includes a first plate cylinder 13A, a first impression cylinder 17A, a first drive motor 19A, a first encoder 21A, and a first mark sensor 23A. The second printing unit 11B includes a second plate cylinder 13B, a second impression cylinder 17B, a second drive motor 19B, a second encoder 21B, and a second mark sensor 23B. The third printing unit 11C includes a third plate cylinder 13C, a third impression cylinder 17C, a third drive motor 19C, a third encoder 21C, and a third mark sensor 23C. The fourth printing unit 11D includes a fourth plate cylinder 13D, a fourth impression cylinder 17D, a fourth drive motor 19D, a fourth encoder 21D, and a fourth mark sensor 23D. Hereinafter, the first to fourth plate cylinders 13A to 13D will be collectively referred to as plate cylinder 13, the first to fourth impression cylinders 17A to 17D will be collectively referred to as impression cylinder 17, the first to fourth drive motors 19A to 19D will be collectively referred to as drive motor 19, the first to fourth encoders 21A to 21D will be collectively referred to as encoder 21, and the first to fourth mark sensors 23A to 23D will be collectively referred to as mark sensor 23. 【0021】 The printing apparatus 10 prints on a web 50, which is a roll of paper, as the substrate. Each printing unit 11 is installed along the direction of movement of the web 50. The web 50 is guided by guide rollers 25 arranged along its movement path, and the plate cylinder 13 and impression cylinder 17 of each printing unit 11 sequentially print the patterns of each color corresponding to the printing plate wrapped around the plate cylinder 13. 【0022】The printing cylinder 13 has a mark printing section 15. Figure 2(a) shows the positional relationship of the first register marks 53A to the fourth register marks 53D when there is no registration error, and Figure 2(b) shows the positional relationship when there is a registration error. In Figure 2(a), the reference mark 52 is also shown. The reference mark 52 is printed simultaneously with the register mark 53A by the mark printing section 15 of the printing unit 11A that prints the first color of the primary print when overprinting is performed on the same web 50. The reference mark 52 may also indicate the cutting position of the web 50 after printing is complete, and is also called a cut mark. In order to distinguish it from the reference mark or first reference mark specified by the printing element identification section 33 described later, the reference mark 52 is also appropriately called the second reference mark 52. 【0023】 The first register mark 53A is printed at a predetermined first position on the mark printing section 15 of the first plate cylinder 13A. The second register mark 53B is printed at a predetermined second position on the mark printing section 15 of the second plate cylinder 13B. The third register mark 53C is printed at a predetermined third position on the mark printing section 15 of the third plate cylinder 13C. The fourth register mark 53D is printed at a predetermined fourth position on the mark printing section 15 of the fourth plate cylinder 13D. Hereinafter, the first to fourth register marks 53A to 53D will be collectively referred to as register marks 53 as appropriate. Also, the first to fourth positions on which the register marks 53 are printed will be collectively referred to as mark positions as appropriate. 【0024】In Figure 2(a), where there is no registration error, each register mark 53 is printed at a spacing L1 in the correct position along the direction of movement of the web 50 (up and down direction in Figure 2). That is, the relative distance between the first position where the first register mark 53A is printed and the second position where the second register mark 53B is printed, the relative distance between the second position where the second register mark 53B is printed and the third position where the third register mark 53C is printed, and the relative distance between the third position where the third register mark 53C is printed and the fourth position where the fourth register mark 53D is printed are all equal to the spacing L1. In Figure 2(b), where there is a registration error, the register marks 53 are printed offset from their correct positions. In the example shown, the second register mark 53B is offset from its correct position. In this case, the relative distance between the first register mark 53A and the second register mark 53B is smaller than the correct L1, and this difference is the registration error. Similarly, the relative distance between the second register mark 53B and the third register mark 53C is greater than the normal L1, and this difference also constitutes the registration error. 【0025】 During the initial printing, the mark printing section 15 of the printing unit 11A prints the reference mark 52 in the same color as the register mark 53A. While the register marks 53A to 53D are printed at equal intervals within a strip-shaped region 51 extending in the direction of movement of the web 50 (up and down direction in Figure 2), the reference mark 52 is printed outside the strip-shaped region 51. Furthermore, the reference mark 52 and the register mark 53A, which are printed simultaneously, are printed at the same position along the direction of movement of the web 50. In other words, as shown in the figure, the bottom edge of the rectangular reference mark 52 and the bottom edge of the right-angled triangle register mark 53A are on the same straight line. 【0026】In the illustrated example, the mark printing unit 11A printed the reference mark 52 during the primary printing, but the mark printing units 15 of the other printing units 11B to 11D may also print the reference mark 52. The printing unit for printing the reference mark 52 may be provided separately from the mark printing unit 15 for printing the register mark 53. Furthermore, the reference mark 52 can be printed at any position outside the strip-shaped area 51. Therefore, the reference mark 52 and the register mark 53 do not have to be in the same position along the direction of movement of the web 50 as shown in the illustration. In addition, if the purpose of the reference mark 52 is to detect registration errors during overprinting, it needs to be printed before the secondary printing, but if the purpose is to detect registration errors during normal printing, it may be printed together with the register mark 53 during normal printing. Furthermore, the reference mark 52 may be pre-printed on the web 50 before the primary printing. 【0027】 Returning to Figure 1, the circumference of each plate cylinder 13 is the same, and each printing unit 11 prints one pattern of each color by rotating each plate cylinder 13 once, and printing is done continuously by repeating this process. As shown in Figure 2(a), in each printing cycle, the mark printing section 15 of each plate cylinder 13 prints each register mark 53 at intervals of L1. 【0028】 Each plate cylinder 13 is rotationally driven by an individual drive motor 19. During the printing operation of the printing device 10, each drive motor 19 is electrically synchronized, and each plate cylinder 13 rotates at the same rotational speed. In other words, the printing device 10 is configured using a sectional drive system. Each drive motor 19 is equipped with an encoder 21 on its mechanical shaft. 【0029】 The encoder 21 is an incremental encoder. For each rotation of the printing cylinder 13, the encoder 21 outputs a predetermined number of A-phase and B-phase pulse signals, and one Z-phase pulse signal. The A-phase and B-phase pulse signals are counted by a counter, and the count value is reset by the Z-phase pulse signal. The phase (rotation position) of the printing cylinder 13 is detected by the count value of the pulse signals. Note that the encoder 21 can be of any type as long as it can detect the phase of the printing cylinder 13, and an absolute serial encoder may also be used. 【0030】Figure 3 shows the configuration of the printing unit 11. The mark sensor 23 is provided downstream of the plate cylinder 13 of the same printing unit 11. The mark sensor 23 has a plurality of photodetectors T1 and T2. In the mark sensors 23B to 23D, the upstream first photodetector T1 and the downstream second photodetector T2 are arranged at an interval L1. Therefore, if adjacent register marks 53A to 53D are printed at the correct positions with an interval L1, these register marks 53A to 53D will be detected by each photodetector T1 and T2 at approximately the same timing. As a result, when the detection time is limited by a gate, the signals detected by the photodetectors T1 and T2 can be used in the calculation of the registration error. Note that in this embodiment, it is not necessarily required to use a gate. For example, the method described in Patent Document 2 can be used for the calculation of the registration error using a gate. The mark sensors 23B to 23D may have only one photodetector. Alternatively, the mark sensors 23B to 23D may have multiple photodetectors, and one photodetector may be used for the processing described later. Below, an example in which the mark sensors 23B to 23D use the first photodetector T1 will be described. 【0031】In the mark sensor 23A of the first color printing unit 11A, the photodetectors T1 and T2 are arranged spaced apart in a direction perpendicular to the direction of movement of the web 50. The first photodetector T1, acting as a register mark detection unit, detects the register marks 53A to 53D within the strip-shaped region 51 in Figure 2, while the second photodetector T2, acting as a reference mark detection unit, detects the reference mark 52 outside the strip-shaped region 51 in Figure 2. The reference value for the distance between the first photodetector T1 and the second photodetector T2 is L1, but this is adjusted according to the distance between the register mark 53A and the reference mark 52 in Figure 2. That is, if the distance between the register mark 53A and the reference mark 52 is less than the reference value L1, the distance between the first photodetector T1 and the second photodetector T2 is shortened, and if the distance between the register mark 53A and the reference mark 52 is greater than the reference value L1, the distance between the first photodetector T1 and the second photodetector T2 is lengthened. If the distance between the register mark 53A and the reference mark 52 is less than L1, the distance between the first photodetector T1 and the second photodetector T2 may remain at the reference value L1. That is, by tilting the mark sensors 23B to 23D, in which the distance between the photodetectors T1 and T2 is L1, at an appropriate angle, the distance between the photodetectors T1 and T2 in the direction perpendicular to the direction of movement of the web 50 can be made to match the distance between the register mark 53A and the reference mark 52. Therefore, the mark sensors 23B to 23D can be used as mark sensor 23A without changing their configuration. 【0032】 Figure 4 is a block diagram showing the configuration of the registration error detection device 30. This configuration is implemented hardware-wise using the CPU, memory, and other LSIs of any computer, and software-wise using programs stored in memory. Here, we show the functional blocks realized through the cooperation of these components. 【0033】 The registration error detection device 30 comprises a control unit 31 and a storage unit 49. The control unit 31 comprises a printing element identification unit 33, a reference selection unit 35, a rotation angle acquisition unit 37, a relative distance calculation unit 39, a registration error detection unit 41, and a registration error correction unit 43. The storage unit 49 is a general-purpose memory that stores information related to the control of the control unit 31. 【0034】The print element identification unit 33 identifies a predetermined print element printed on the moving web 50 based on detection by the first photodetector T1 of the mark sensor 23. In this example, the print element identification unit 33 identifies a register mark 53 printed at a predetermined mark position on the web 50 as a print element. 【0035】 Here, the first photodetector T1 has the function of detecting the color of the printed elements printed on the web 50. The printed element identification unit 33 identifies at least one printed element based on the color information of that printed element. In this example, the printed element identification unit 33 designates a register mark 53 of a predetermined color from among the register marks 53 as the first reference mark. 【0036】 Referring to Figure 5, an example of the identification process by the print element identification unit 33 will be explained. Figure 5 is a schematic diagram showing how multiple register marks 53 printed on a moving web 50 are detected by the first photodetector T1. Register marks 53A' to 53D' were printed by the printing units 11A to 11D in the primary printing performed before the secondary printing. As explained in Figure 2, the interval between register marks 53A' to 53D' is L1. Register mark 53A was newly printed by the printing unit 11A in the secondary printing. Register mark 53A, which is the first color register mark of the secondary printing, should be printed at an interval L1 from 53D', which is the last color register mark of the primary printing. However, there is a large registration error between the primary and secondary printing when the secondary printing is started. Let this registration error be e, and the interval between register marks 53A and 53D' is L1 + e. 【0037】Figure 5 shows the RGB values ​​as color information for each register mark 53. These RGB values ​​are examples. The first photodetector T1 acquires the color information for each register mark 53 along with the waveform of each register mark 53. The printing element identification unit 33 designates a register mark 53A' of a predetermined color from among a plurality of register marks 53, each composed of a different color, as the first reference mark 54. The printing element identification unit 33 may designate any of the register marks 53 as the first reference mark 54. Furthermore, the printing element identification unit 33 may designate the first reference mark 54 in response to input from the operator of the printing device 10. 【0038】 Returning to Figure 4, the reference selection unit 35 selects whether the second reference mark 52, as described in Figure 2, is detected by the second photodetector T2, which acts as the reference mark detection unit of the mark sensor 23A, to be used as the reference mark by the relative distance calculation unit 39, which will be described later. If the second reference mark 52 is detected by the second photodetector T2, the reference selection unit 35 selects the second reference mark 52 as the reference mark to be used in the calculation by the relative distance calculation unit 39. On the other hand, if the second reference mark 52 is not detected, the reference selection unit 35 selects the first reference mark 54 as the reference mark to be used in the calculation by the relative distance calculation unit 39. The calculation process of the relative distance calculation unit 39 will be described later. 【0039】The rotation angle acquisition unit 37 acquires the rotation angle of the printing cylinder 13 when the mark sensor 23 detects the reference mark selected by the reference selection unit 35. Specifically, if the reference mark selected by the reference selection unit 35 is the first reference mark 54, the rotation angle acquisition unit 37 acquires the rotation angle of the printing cylinder 13A when the photodetector T1 of the mark sensor 23A detects the register mark 53A' designated for the first reference mark 54. Also, if the reference mark selected by the reference selection unit 35 is the second reference mark 52, the rotation angle acquisition unit 37 acquires the rotation angle of the printing cylinder 13A when the photodetector T2 of the mark sensor 23A detects the second reference mark 52. These rotation angles may be stored in the storage unit 49 when the mark sensor 23 detects the register mark 53 or the second reference mark 52, and may be read from the storage unit 49 by the rotation angle acquisition unit 37. 【0040】 The relative distance calculation unit 39 calculates the relative distance between the reference mark selected by the reference selection unit 35 and the register mark 53 along the direction of movement of the web 50. As shown in Figure 5, if the reference mark selected by the reference selection unit 35 is the first reference mark 54, the relative distance calculation unit 39 calculates the relative distance L along the direction of movement of the web 50 between the register mark 53A' designated for the first reference mark 54 and the other register marks 53A. In this example, the relative distance calculation unit 39 calculates the relative distance based on the rotation angle acquired by the rotation angle acquisition unit 37 and the rotation position of the mark printing unit 15 on the printing cylinder 13A. 【0041】 Referring to Figure 6, a specific example of the processing of the rotation angle acquisition unit 37 and the relative distance calculation unit 39 will be explained. Figure 6 schematically shows a printing unit 11A that performs secondary printing of overprinting. The register marks 53A' to 53D', 53A, and the intervals between them are as explained in Figure 5. Below, an example in which the second reference mark 52 is used as the reference mark for the calculation of the relative distance calculation unit 39 will be explained, but the same applies when the first reference mark 54 is used. 【0042】First, the rotation angle acquisition unit 37 acquires the rotation angle θs of the plate cylinder 13A when the second light detection element T2 of the mark sensor 23A detects the second reference mark 52'. Subsequently, based on the rotational position of the mark printing unit 15 on the plate cylinder 13A that can be detected by the encoder 21A of the printing unit 11A, the rotation angle θa of the plate cylinder 13A when the register mark 53A newly printed by the mark printing unit 15 is detected by the mark sensor 23A is obtained by calculation. As shown in the figure, if the moving distance of the web 50 from the printing point P to the detection area of the mark sensor 23A is La, θa is expressed as θa = La / r using the radius r of the plate cylinder 13A. 【0043】 The relative distance calculation unit 39 calculates the relative distance L along the moving direction of the web 50 between the reference mark 52' and the register mark 53A based on the rotation angle θs acquired by the rotation angle acquisition unit 37 and the rotation angle θa obtained by calculation. The relative distance L is the distance that the web 50 moves while the plate cylinder 13A rotates from the phase θs to θa, and is obtained by L = r(θa - θs). And the registration error e between the first printing and the second printing is obtained by e = L - 4L1 = r(θa - θs) - 4L1 = La - rθs - 4L1. In this formula, La, r, and L1 are constants known to the printing unit 11A, and the only unknown is θs. Since this θs is based on the detection result of the reference mark 52' of the second light detection element T2 without a gate, the registration error e between the first printing and the second printing can be calculated without using a gate. 【0044】 Returning to FIG. 4, the registration error detection unit 41 detects the presence or absence of a registration error based on the relative distance L calculated by the relative distance calculation unit 39. For example, the registration error detection unit 41 may determine that there is no registration error when the registration error e calculated as described above is smaller than a predetermined threshold, and determine that there is a registration error when it is greater than or equal to the predetermined threshold. 【0045】The registration error correction unit 43 corrects the registration error calculated by the relative distance calculation unit 39. The registration error correction unit 43 outputs a correction signal to the drive motor 19 or sideray (not shown) of the printing unit 11 where the registration error has occurred. The drive motor 19 or sideray drives the plate cylinder 13 so that the registration error is corrected based on the correction signal. The drive motor 19 corrects the registration error in the direction of movement of the web 50, and the sideray corrects the registration error in the width direction perpendicular to the direction of movement of the web 50. 【0046】 In the example described above, the print element identification unit 33 identified a register mark 53 printed on the web 50 as a print element. However, the print element identification unit 33 may also identify print elements other than the register mark 53 printed on the web 50. Referring to Figure 7, another example of the identification process by the print element identification unit 33 will be described. Figure 7 is a schematic diagram showing how multiple patterns 55 printed on a moving web 50 are detected by the first photodetector T1. The photodetector T1 detects the multiple patterns 55 along a detection line 57 that is aligned with the direction of movement of the web 50. 【0047】 The pattern 55 changes in color tone in a predetermined repeating pattern along the detection line 57. Figure 7 shows an example of an RGB pattern. The same numbers in the RGB pattern indicate that they are the same RGB pattern. As shown in Figure 7, the RGB pattern of the pattern 55 changes in the order "2→3→4→5→4→3→2" along the direction of movement of the web 50. The print element identification unit 33 may identify areas such as the pattern 55, where the color tone changes in a predetermined pattern along the direction of movement of the web 50, as print elements. 【0048】In this example, the first light detection element T1 of the mark sensor 23 may be movable along a detection line 57 in a direction orthogonal to the moving direction of the web 50 in order to appropriately detect a pattern of the color tone of the pattern 55 or the like. Further, in this example, the first light detection element T1 of the mark sensor 23 may sequentially send information on the color tone along the detection line 57 to the print element identification unit 33, and the print element identification unit 33 may identify it as a color tone pattern. In this example, the print element identification unit 33 may specify any one of the plurality of identified print elements as the first reference mark 54. Thereby, the relative distance calculation unit 39 can calculate the relative distance along the moving direction of the web 50 between the two print elements as described above. 【0049】 As described above, the misregistration detection device 30 according to the present embodiment includes a print element identification unit 33 that identifies a predetermined print element printed on a moving printed material. The print element identification unit 33 identifies at least one print element based on the color information of the print element. The misregistration detection device 30 further includes a relative distance calculation unit 39 that calculates a relative distance along the moving direction between two print elements including the print element identified based on the color information, and a misregistration detection unit 41 that detects a misregistration based on the relative distance. 【0050】 Thereby, the misregistration detection device 30 can detect a misregistration by calculating the relative distance between print elements using the color information of the print elements, so that it can cope with a large misregistration, and it is not necessary to print a reference mark in advance, and it is not always necessary to prepare a detection element for detecting a cut mark. Therefore, a misregistration can be effectively detected. 【0051】Furthermore, in the registration error detection device 30, the printing element identification unit 33 identifies a register mark 53 printed at a predetermined mark position on the printed material as a printing element, and may designate a register mark 53 of a predetermined color as the first reference mark 54. The relative distance calculation unit 39 may calculate the relative distance between the reference mark 54 and the register marks 53 other than the first reference mark 54 along the direction of movement. As a result, the registration error detection device 30 can designate a register mark 53 of a predetermined color as the first reference mark 54 and calculate the relative distance between that first reference mark 54 and the other register marks 53, thereby effectively detecting registration errors. 【0052】 Furthermore, the registration error detection device 30 may further include a second photodetector T2 as a reference mark detection unit that detects a second reference mark 52 printed at a predetermined reference position other than the band-shaped region 51 that includes the mark position and extends in the direction of movement, and a reference selection unit 35 that selects whether the relative distance calculation unit 39 will use the first reference mark 54 or the second reference mark 52 as the reference mark depending on whether the second reference mark 52 is detected or not. As a result, the registration error detection device 30 can calculate the relative distance using the second reference mark 52 when the second reference mark 52 is detected, and using the first reference mark 54 when the second reference mark 52 is not detected, so that it can appropriately detect registration errors depending on the situation. 【0053】 Furthermore, in the registration error detection device 30, the printing element identification unit 33 may identify areas on the printed material where the color tone changes in a predetermined pattern along the direction of movement as printing elements. This allows for effective detection of registration errors without printing register marks 53 or the like. 【0054】[Second Embodiment] Figure 8 schematically shows the configuration of a coating apparatus 110 according to the second embodiment of the present disclosure. The coating apparatus 110 comprises a coating unit 111 and a registration error detection device 130. The coating unit 111 intermittently coats a workpiece 150 that has been previously intermittently coated with a first coating material 151 with a second coating material 153. The coating unit 111 comprises a transport roller 125, an encoder 113, a coating section 115, an edge detection sensor 121, and a pattern detection sensor 123. Examples of workpieces 150 include flat materials such as paper, cloth, film, foil, and rubber. 【0055】 The transport roller 125 transports the object to be coated 150 in the direction of movement (the direction schematically shown by the arrow in Figure 8). The coating unit 111 may be equipped with multiple transport rollers 125, but Figure 8 shows only one transport roller 125. The object to be coated 150 is guided by guide rollers 127 arranged along its movement path. The encoder 113 detects the position of the object to be coated 150 in the direction of movement. Figure 8 shows an example in which the encoder 113 is provided on the guide roller 127. The encoder 113 may be provided on the mechanical shaft of the drive motor that rotates the transport roller 125, for example, similar to the encoder 21 in the first embodiment. The encoder 113 can be of any type as long as it can detect the position of the object to be coated 150 in the direction of movement, and may be an incremental encoder or an absolute serial encoder. The encoder 113 outputs information about the position of the object to be coated 150 in the direction of movement to the registration error detection device 130. 【0056】 The coating unit 115 coats the object to be coated 150 at a predetermined position in the direction of movement of the object to be coated 150. The coating method by the coating unit 115 is not particularly limited. The coating method may be, for example, a roll coater or a die coater. If the coating method is a roll coater, the coating unit 115 includes a roll and uses the roll to transfer the coating liquid to the object to be coated 150. If the coating method is a die coater, the coating unit 115 includes a slit die and supplies pressurized coating liquid through the slit die to directly apply the coating liquid to the object to be coated 150. 【0057】The edge detection sensor 121 detects the edges of the first coating 151, which has been intermittently applied to the surface of the workpiece 150 in each direction of movement. Based on the position of the first coating 151 detected by the edge detection sensor 121, the coating unit 115 determines the position for applying the second coating 153. The coating unit 115 forms the second coating 153 at a position that overlaps with at least a portion of the first coating 151 that has been formed on the surface of the workpiece 150. 【0058】 The pattern detection sensor 123 detects predetermined coating elements contained in the first coating 151 and the second coating 153 (hereinafter also simply referred to as "coating") integrally formed on the surface of the workpiece 150. Specifically, the pattern detection sensor 123 detects the surface of the workpiece 150 along a predetermined detection line that is aligned with the direction of movement of the workpiece 150. The workpiece 150, together with the coating formed on its surface, changes color in a predetermined repeating pattern along the detection line. The pattern detection sensor 123 detects a predetermined color change pattern contained in the coating along the direction of movement of the workpiece 150 and outputs it to the registration error detection device 130. 【0059】 Figure 9 is a block diagram showing the configuration of the registration error detection device 130. This configuration is implemented hardware-wise using the CPU, memory, and other LSIs of any computer, and software-wise using programs stored in memory. Here, we show the functional blocks realized through the cooperation of these components. 【0060】 The registration error detection device 130 comprises a control unit 131 and a storage unit 149. The control unit 131 comprises a coating element identification unit 133, a reference position generation unit 137, a relative distance calculation unit 139, a registration error detection unit 141, and a registration error correction unit 143. The storage unit 149 is a general-purpose memory that stores information related to the control of the control unit 131. 【0061】The coating element identification unit 133 identifies the coating elements included in the coating applied to the moving object to be coated 150 based on detection by the pattern detection sensor 123. Here, the pattern detection sensor 123 has the function of detecting the color of the coating elements applied to the object to be coated 150. The coating element identification unit 133 identifies at least one coating element based on the color information of that coating element. 【0062】 The color tone of the coated object changes in a predetermined repeating pattern along the direction of movement of the object to be coated 150. The coated element identification unit 133 may identify the portion of the coated object where the color tone changes in a predetermined pattern along the direction of movement of the object to be coated 150 as a coated element. The method by which the coated element identification unit 133 identifies coated elements may be the same as the method by which the printed element identification unit 33 identifies printed elements in the first embodiment. 【0063】 The reference position generation unit 137 acquires the position of the object to be coated 150 in the direction of movement when the pattern detection sensor 123 detects the coating element, based on information from the encoder 113. 【0064】 The relative distance calculation unit 139 calculates the relative distance along the direction of movement of two coated elements, including a coated element identified by the coated element identification unit 133 based on color information. In this example, the relative distance calculation unit 139 calculates the relative distance based on the position of the object to be coated 150 acquired by the encoder 113 and another position of the object to be coated 150 acquired by the encoder thereafter. 【0065】 The registration error detection unit 141 detects the presence or absence of registration error based on the relative distance calculated by the relative distance calculation unit 139. The registration error correction unit 143 corrects the registration error calculated by the relative distance calculation unit 139. 【0066】 Configurations not described in this embodiment can be configured in the same way as in the first embodiment. Specifically, by replacing "printing" with "coating" in each configuration and description of the first embodiment, these can be understood as each configuration and description of this embodiment. 【0067】Furthermore, the coating apparatus 110 according to this embodiment may further include configurations related to the register mark 53 and the second reference mark 52 in the first embodiment. That is, the coated element may include marks corresponding to the register mark 53 and the second reference mark 52, and the pattern detection sensor 123 may be capable of detecting these marks. In that case, the control unit 131 may further include a configuration corresponding to the reference selection unit 35. However, since the coating apparatus 110 is not suitable for coating high-resolution marks, etc., compared to the printing apparatus 10, it is more effective to identify the coated element based on the color tone pattern of the coated object as described above. 【0068】 As described above, the coating apparatus 110 according to this embodiment comprises a registration error detection device 130 and a coating unit 111. The registration error detection device 130 includes a coating element identification unit 133 that identifies predetermined coating elements coated on a moving object to be coated 150. The coating element identification unit 133 identifies at least one coating element based on the color information of the coating element. The registration error detection device 130 further includes a relative distance calculation unit 139 that calculates the relative distance along the direction of movement of two coating elements, including the coating element identified based on the color information, and a registration error detection unit 141 that detects a registration error based on the relative distance. The coating unit 111 coats the coating elements onto the object to be coated 150. 【0069】 As a result, the coating apparatus 110 can detect registration errors by calculating the relative distance between coated elements using the color information of the coated elements. Therefore, it can handle large registration errors, does not require pre-printing of reference marks, and does not necessarily require the provision of detection elements for cut mark detection. Thus, registration errors can be detected effectively. 【0070】 The present invention has been described above based on embodiments. The embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications also fall within the scope of the present invention. 【0071】In the first embodiment, a web 50, which is a roll of paper, was exemplified as the substrate to be printed on, but the printing device 10 can print on any substrate. For example, it may be a sheet made of any material, or the surface of a solid of any shape, such as a container or product. 【0072】 In the first embodiment, the control unit 31 of the registration error detection device 30 does not need to include a reference selection unit 35. In this case, the relative distance calculation unit 39 calculates the relative distance between the first reference mark 54 and the register mark 53 along the direction of movement of the web 50. Also in this case, the mark sensor 23A does not need to have a second photodetector T2, and the second reference mark 52 does not need to be printed on the web 50. 【0073】 The first photodetector T1 in the first embodiment and the pattern detection sensor 123 in the second embodiment do not necessarily have a function to detect color, and in each embodiment, a separate sensor for color detection may be used. 【0074】 The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. Hardware resources include, for example, processors, ROMs, RAMs, and various integrated circuits. Software resources include, for example, operating systems and application programs. 【0075】 This disclosure relates to a technique for detecting registration errors in printed or coated materials. 【0076】 10 Printing device, 11 Printing unit, 30 Registration error detection device, 33 Printing element identification unit, 35 Reference selection unit, 39 Relative distance calculation unit, 41 Registration error detection unit, 51 Strip-shaped area, 52 Second reference mark, 53 Register mark, 54 First reference mark, 110 Coating device, 111 Coating unit, 130 Registration error detection device, 133 Coating element identification unit, 139 Relative distance calculation unit, 141 Registration error detection unit, 150 Workpiece to be coated.

Claims

1. A registration error detection device comprising: a printing element identification unit that identifies predetermined printing elements printed on a moving substrate; the printing element identification unit further comprises: a relative distance calculation unit that identifies at least one printing element based on the color information of the printing element; a relative distance calculation unit that calculates the relative distance between two printing elements, including the printing element identified based on the color information, along the direction of movement; and a registration error detection unit that detects a registration error based on the relative distance.

2. The registration error detection device according to claim 1, wherein the printing element identification unit identifies a register mark printed at a predetermined mark position on the printed material as the printing element, and designates the register mark of a predetermined color as a reference mark, and the relative distance calculation unit calculates the relative distance between the reference mark and the register marks other than the reference mark along the direction of movement.

3. The registration error detection device according to claim 2, further comprising: a reference mark detection unit that detects a second reference mark printed at a predetermined reference position other than a band-shaped region extending in the direction of movement including the position of the reference mark, when the reference mark is designated as a first reference mark; and a reference selection unit that selects whether the relative distance calculation unit will use the first reference mark or the second reference mark as the reference mark, depending on whether the second reference mark is detected or not.

4. The registration error detection device according to claim 1, wherein the printing element identification unit identifies a location on the printed material in which the color tone changes in a predetermined pattern along the direction of movement as the printing element.

5. A printing apparatus comprising: a registration error detection device according to any one of claims 1 to 4; and a printing unit for printing the printing elements on the material to be printed.

6. A coating apparatus comprising a registration error detection device and a coating unit, wherein the registration error detection device includes a coating element identification unit for identifying predetermined coating elements coated on a moving workpiece, the coating element identification unit further includes a relative distance calculation unit for identifying at least one coating element based on the color information of the coating element, calculating the relative distance along the direction of movement of two coating elements including the coating element identified based on the color information, and a registration error detection unit for detecting a registration error based on the relative distance, and the coating unit for coating the coating elements onto the workpiece.

7. A method for detecting a registration error, comprising the steps of: identifying a predetermined printing element printed on a moving substrate, wherein at least one printing element is identified based on the color information of the printing element; calculating a relative distance along the direction of movement of two printing elements, including the printing element identified based on the color information; and detecting a registration error based on the relative distance.

8. A registration error detection program for causing a computer to perform the following steps: identifying predetermined printed elements printed on a moving substrate, including identifying at least one printed element based on the color information of the printed element; calculating the relative distance between two printed elements, including the printed element identified based on the color information, along the direction of movement; and detecting a registration error based on the relative distance.

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