Printing machine

Abstract

To provide a printer which can print a printing pattern at a normal position on a print sheet.SOLUTION: A printer comprises a printing part which prints a printing pattern and a register mark for registration on a printing object which is transported by a cylinder with colors including a reference color. The cylinder 14 is provided with machine reference marks 19A, 19B. The printer comprises: imaging means which images a printing object printed by the printing part so as to include the machine reference marks 19A, 19B and the register mark; and indexing means which indexes a position of the reference color register mark in a transport direction on the basis of a distance between the machine reference marks 19A, 19B and at least the reference color register mark of the register marks that have been imaged by the imaging means.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a printing press having a printing unit that prints a print pattern and a registration mark for registration in the same color as the print pattern on a printing medium. [Background technology]

[0002] In printing by such a printing machine, registration marks for registration are printed in the margins at both ends in the width direction of the printing paper, which is the printing object, in a number corresponding to the number of printing units used. For example, in the following Patent Document 1, each registration mark is composed of a first registration mark group and a second registration mark group. The first registration mark group is composed of registration marks of each color including the reference color (black) (four in FIG. 3A). The second registration mark group is composed of the same number as the first registration mark group and all of the registration marks are of the reference color (black) (four in FIG. 3A). The second registration mark group is set at a position shifted in parallel by a predetermined distance in a direction (left-right direction) perpendicular to the arrangement direction (top-bottom direction) of the first registration mark group, and at the same intervals as the intervals of the first registration marks in the same direction (top-bottom direction) as the arrangement direction (top-bottom direction) of the first registration mark group.

[0003] In register adjustment, an image of the printing paper on the impression cylinder being conveyed is captured by an imaging means (in-line camera), and the positions of the four color register marks in the first register mark group and the four same color (black) register marks in the second register mark group are obtained from the captured image. Based on the obtained positions, the inter-mark distances between the register mark of the reference color in the first register mark group and the register marks of the other three colors, and the inter-mark distances between the register mark of the reference color in the second register mark group and the register marks of the other reference colors are calculated. If the calculated distances differ from the preset distances, the register adjustment device of the plate cylinder is driven and controlled to eliminate the difference, thereby adjusting the in-plane register. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6030732 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the first place, it is not clear whether the distance on the printing paper calculated from the captured image is objectively correct. In particular, since it is assumed that the installation accuracy of the imaging means and the mechanical vibration of the printing press affect the calculation accuracy of the distance (especially the distance in the conveying direction), if the installation accuracy of the imaging means decreases or the mechanical vibration of the printing press increases, the reliability of the calculated distance decreases.

[0006] In addition, the distance between the reference color registration mark and the edges (front edge and left and right edges) of the printing paper is calculated from the captured image, and if this calculated distance differs from a preset distance, the printing position of the printing pattern on the printing paper can be aligned by driving and controlling the circumferential registration adjustment device of the plate cylinder to eliminate the difference.

[0007] However, even in this case, as in the above case, it is not possible to know whether the distance on the printing paper calculated from the captured image is objectively correct.

[0008] Furthermore, when the distance between the reference color register mark calculated from the captured image and the edges of the printing paper (the front edge and the left and right edges) differs from the preset distance, it is not possible to determine whether the cause is a misalignment of the reference color register mark relative to the impression cylinder, or a misalignment of the printing paper relative to the impression cylinder. Therefore, it may not be possible to select an appropriate solution. That is, when the cause is the former, it is sufficient to address the issue by controlling the drive of the registration adjustment device of the plate cylinder, but when the latter, unlike the former, it may be necessary to adjust the side needles, front stop, etc., leaving room for improvement.

[0009] The present invention has been made to solve such problems, and an object of the present invention is to provide a printing machine capable of printing a print pattern in a regular position on a printing object. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the printing press of the present invention has a printing unit that prints a printing pattern and a registration mark for alignment in colors including a reference color on a printing object transported by a cylinder, the cylinder is provided with a mechanical reference mark, and the printing press is characterized in that it is equipped with an imaging means that images the printing object printed by the printing unit so as to include the mechanical reference mark and the registration mark, and an indexing means that indexes the position in the transport direction of the reference color registration mark based on the distance in the transport direction between the mechanical reference mark imaged by the imaging means and at least a reference color registration mark among the registration marks.

[0011] According to the above configuration, the position of the reference color registration mark in the transport direction is calculated based on the distance in the transport direction between the machine reference mark provided on the cylinder and the reference color registration mark, so the position of the registration mark relative to the cylinder can be calculated objectively and correctly, and the print pattern can be printed in the correct position on the printing object.

[0012] In the printing press according to the present invention, the machine reference mark may be provided on the outer peripheral surface of the cylinder or on an extended surface of the outer peripheral surface.

[0013] As described above, by providing the mechanical reference mark on the outer surface of the cylinder or on the extended surface of the outer surface, the position of the mechanical reference mark can be detected as accurately as the position of the reference color registration mark printed on the printing object transported on the outer surface of the cylinder.

[0014] In addition, the printing press according to the present invention may be configured so that the machine reference marks are provided in a pair spaced apart in the transport direction, and the printing press is equipped with a correction coefficient calculation means for comparing a calculated value of the distance in the transport direction between one machine reference mark and the other machine reference mark imaged by the imaging means with an actual measured value of the distance between the one machine reference mark and the other machine reference mark, and calculating a correction coefficient according to the difference, and the correction coefficient calculated by the correction coefficient calculation means may be used for correction when calculating the distance in the transport direction between the machine reference mark imaged by the imaging means and a registration mark of the reference color.

[0015] According to the above configuration, the correction coefficient calculated by the correction coefficient calculation means is used to correct the distance in the transport direction between the machine reference mark imaged by the imaging means and the reference color registration mark, thereby making it possible to accurately calculate the distance from the captured image.

[0016] In addition, the printing press of the present invention may be configured so that the printing section includes a pre-printing unit and a post-printing unit that prints on the print object printed by the pre-printing unit, and the imaging means includes a pre-printing side imaging means that images the pre-printed surface of the print object and a post-printing side imaging means that images the post-printed surface of the print object, and an adjustment means that compares the distance in the transport direction between the machine reference mark and the reference color register mark of the pre-printing unit from the image captured by the pre-printing side imaging means and the distance in the transport direction between the machine reference mark and the reference color register mark of the post-printing unit from the image captured by the post-printing side imaging means, and adjusts the phase of the transport direction of the pre-printing unit and the post-printing unit based on the difference.

[0017] According to the above configuration, the distance in the transport direction between the pre-printing unit's mechanical reference mark and the reference color registration mark from the image captured by the pre-printing side imaging means is compared with the distance in the transport direction between the pre-printing unit's mechanical reference mark and the reference color registration mark from the image captured by the rear-printing side imaging means, and the phase of the transport direction of the pre-printing unit and the rear-printing unit is adjusted based on the difference, thereby enabling the printing patterns printed on the pre-printing surface and the rear-printing surface of the printed object to be aligned.

[0018] In the printing press according to the present invention, the machine reference mark may be configured to have the same shape as the registration mark.

[0019] According to the above configuration, the machine reference mark is configured to have the same shape as the registration mark, so that the influence of the difference in shape can be ignored, and the machine reference mark can be easily detected.

[0020] In addition, in the printing press according to the present invention, a notch may be formed in the cylinder so as to be recessed radially inward from the outer circumferential surface of the cylinder, and the machine reference mark may be provided in the notch.

[0021] According to the above-described configuration, by providing a mechanical reference mark in the cutout portion formed in the body, the cutout portion can be effectively utilized as a space for providing the mechanical reference mark. Effect of the Invention

[0022] According to the present invention, the position of the reference color register mark in the transport direction is determined based on the distance in the transport direction between the machine reference mark on the cylinder and the reference color register mark, so a printing press can be provided that can print a print pattern in the correct position on the printing object. [Brief description of the drawings]

[0023] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3]3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] 1A and 1B show a member having a mechanical reference mark, in which (a) is a plan view and (b) is a side view. [Figure 6] FIG. 4 is an explanatory diagram showing an imaging area of ​​an in-line camera relative to an impression cylinder. [Figure 7] 1A is an explanatory diagram for explaining the calculation of the vertical distance between the machine reference mark on the gripping side and the reference color register mark on the pre-printed surface, and FIG. 1B is an explanatory diagram for explaining the calculation of the vertical distance between the machine reference mark on the gripping side and the reference color register mark on the post-printed surface. [Figure 8] FIG. 1A is an explanatory diagram for explaining the calculation of the left-right distance between the left edge of the printing paper and the mark, and FIG. 1B is an explanatory diagram for explaining the calculation of the left-right distance between the right edge of the printing paper and the reference color registration mark. [Figure 9] FIG. 2 is a block diagram showing a control configuration for performing registration in a printing press. [Figure 10] 11 is a flowchart of the first half of a process for performing registration. [Figure 11] 13 is a flowchart of the second half for performing registration. [Figure 12] FIG. 13 is an explanatory diagram showing another embodiment in which a mechanical reference mark is provided on the outer peripheral surface of the impression cylinder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A printing press performing registration according to an embodiment of the present invention will be described below with reference to the drawings.

[0025] The printing press includes a paper stack 1, a paper feed unit 3 for feeding printing paper, which is a printing object, one by one from the paper stack 1 by a feeder device 2, a pre-printing printing unit 4 for printing in four colors on the printing paper fed from the paper feed unit 3, an inversion device 5 capable of inverting the printing paper printed by the pre-printing printing unit 4, a post-printing printing unit 6 for further printing in four colors on the printing paper that has been inverted by the inversion device 5 or the printing paper that has not been inverted, and a paper discharge unit 7 for transporting and discharging the printed paper after printing. The printing press further includes a first inline camera (CCD image sensor, RGB camera, etc.) 8 for capturing an image of the printing paper printed by the pre-printing printing unit 4, and a second inline camera (CCD image sensor, RGB camera, etc.) 9 for capturing an image of the printing paper printed by the post-printing printing unit 6. The first inline camera 8 is a pre-printing side imaging means, and the second inline camera 9 is a post-printing side imaging means. The imaging means is made up of the pre-printing side imaging means and the post-printing side imaging means. In the following description, the paper stack 1 side is the front side, the paper discharge section 7 side is the rear side, and the direction perpendicular to the conveying direction of the printing paper (the direction across the paper surface) is the left-right direction (or width direction).

[0026] The paper feed section 3 is equipped with a front-stop mechanism (not shown) for aligning the start end (front end) of the print paper in the transport direction by contacting the start end (front end) of the print paper and temporarily blocking the transport of the print paper, and a needle (horizontal needle) mechanism (not shown) for moving the print paper to one end in the horizontal direction to align the position of the left-right (widthwise) end of the print paper. The paper feed section 3 is also equipped with a front-stop detection means (detection sensor, not shown) for detecting the position of the start end (front end) of the print paper in the transport direction aligned by the front-stop mechanism, and a needle detection means (detection sensor, not shown) for detecting the position of the left-right end of the print paper aligned by the needle (horizontal needle) mechanism. Based on the detection results of both detection means, it is possible to determine whether the posture of the aligned print paper in the transport direction and width direction is normal (whether it is within an acceptable range). The print paper aligned to the normal position in the paper feed section 3 is held in the correct position by a transport drum described later and transported to the printing section 4. Furthermore, if the printing paper is detected by both of the detection means as not being in the correct position, it is held in a position shifted from the correct position on the transport drum, which will be described later, and transported to the printing unit 4.

[0027] The pre-printing printing section 4 includes four printing units 4A, 4B, 4C, and 4D that print the print pattern and four registration marks 10, 11, 12, and 13 in four process colors Y (yellow), M (magenta), C (cyan), and K (black, also called black). The post-printing printing section 6 includes four printing units 6A, 6B, 6C, and 6D that print the print pattern and four registration marks (not shown) in four process colors Y (yellow), M (magenta), C (cyan), and K (black, also called black), just like the pre-printing printing section 4. In addition, when the image is not inverted, the post-printing may be printed in a color different from that of the pre-printing printing section 4, that is, a special color that is a color other than the four process colors (including gold, silver, fluorescent colors, etc.).

[0028] Each printing unit 4A is equipped with a plate cylinder (not shown) around which a plate is wound, a rubber blanket cylinder (not shown, also called a blanket cylinder) to which ink from the plate cylinder is transferred, an impression cylinder (not shown) that presses the printing paper against the rubber blanket cylinder to transfer the ink on the rubber blanket cylinder to the printing paper, a feed cylinder (not shown) that is arranged at the front end in the transport direction to transfer the printing paper to the impression cylinder of printing unit 4A, and a transfer cylinder (not shown) that is arranged between the impression cylinders to transfer the printing paper from the impression cylinder of the previous printing unit to the impression cylinder of the next printing unit. The feed cylinder, impression cylinder and transfer cylinder are collectively referred to as transport cylinders.

[0029] The conveying cylinder has two notches formed in the circumferential direction so as to be recessed from the outer circumferential surface of the conveying cylinder toward the radially inward direction, and each notch has a plurality of grippers, each consisting of a claw and a claw base for clamping and holding the front end of the printing paper, spaced apart in the left-right direction. Figures 2 to 4 show an impression cylinder 14 configured as a double cylinder, and a notch 15 is formed in each of two circumferential directions of the impression cylinder 14, covering almost the entire area in the left-right width direction. This notch 15 has a bottom wall 15A located on the radially inner side, and a pair of front and rear side walls 15B, 15C extending from the front and rear ends of the bottom wall 15A toward the radially outward direction. A plurality of grippers 16, each consisting of a claw 16A and a claw base 16B, are provided within this notch 15. The claw 16A is attached to a rotating shaft 18 rotatably supported by a support member 17 fixed to the bottom wall 15A.

[0030] Each of the cutouts 15 is provided with a mechanical reference mark 19 used to determine the position of the reference color register mark 13 in the transport direction, which will be described later. A pair of the mechanical reference marks 19 are provided at a distance in the width direction of the impression cylinder 14. The mechanical reference marks 19 are also provided on the extended surface of the outer circumferential surface of the impression cylinder 14. More specifically, the mechanical reference marks 19 are provided on each of a pair of left and right members 20 detachably fixed to each of the cutouts 15. More specifically, the member 20 has a narrow arc-shaped outer surface 20A that has substantially the same curvature as the outer circumferential surface of the impression cylinder 14 and is formed on the extended surface of the outer circumferential surface, and the mechanical reference mark 19 is provided on this outer surface 20A. By providing the mechanical reference mark 19 on the extended surface of the outer circumferential surface of the impression cylinder 14, the position of the mechanical reference mark 19 can be detected with the same accuracy as the position of the reference color register mark 13 printed on the print medium transported on the outer circumferential surface of the impression cylinder 14. Therefore, the distance between the machine reference mark 19 and the registration mark 13 of the reference color can be calculated with high accuracy. Also, by providing the machine reference mark 19 on the member 20 installed in the notch 15, the notch 15 can be effectively used as a space for providing the machine reference mark 19. The member 20 has a jaw side machine reference mark 19A at one end of the outer surface 20A, which is closer to the jaw base 16B, and a trailing side machine reference mark 19B at the other end. Also, in the left-right direction of the impression cylinder 14, the left jaw side machine reference mark 19A and the right jaw side machine reference mark 19A are located at approximately the same position in the circumferential direction of the impression cylinder 14, and the left tail side machine reference mark 19B and the right tail side machine reference mark 19B are also located at approximately the same position in the circumferential direction of the impression cylinder 14. The leading edge side machine reference mark 19A and the trailing edge side machine reference mark 19B are formed in substantially the same shape (square) as the register marks 10, 11, 12, and 13. By forming the machine reference mark 19 in substantially the same shape as the register marks 10, 11, 12, and 13, the effect of differences in shape on detection accuracy can be ignored.

[0031] Each member 20 is disposed adjacent to one of the claws 16A between adjacent claws 16A in the width direction so as to avoid interference with the claws of the paper feed cylinder or the transfer cylinder when the printing paper is transferred. Each member 20 is formed in a narrow shape whose length in the width direction is very short compared to its length in the conveying direction, and is screwed to the bottom wall 15A of the cutout portion 15 so that the arc-shaped outer surface 20A fits along the outer circumferential surface 14A of the impression cylinder 14 (see FIG. 4). The color of the machine reference mark 19 is preferably the same as or close to the reference color (also called black or black). The color of the outer surface of each member 20 is preferably white or close to white. In addition, K1 shown in Figure 4 indicates the actual measured distance between position H1 of the gripping side machine reference mark 19A and position H2 of the tail side machine reference mark 19B on side A, which is one printed surface, for each of the machine reference marks 19 on the right and left sides, and K2 indicates the actual measured distance between position H1 of the gripping side machine reference mark 19A and position H2 of the tail side machine reference mark 19B on side B, which is the other printed surface.

[0032] In addition, each printing unit 4A is equipped with a registration device, and as shown in Figure 9, the registration can be adjusted by driving the registration device 22 of the printing unit of the color that is out of registration based on a signal from the control unit 21.

[0033] As shown in Figure 6, the imaging area (rectangular area) 23 captured by the first inline camera 8 and the second inline camera 9 is set to a slightly larger area so as to include the rectangular printing paper 24 having a leading end 24A, a trailing end 24B, a left end 24C, and a right end 24D within it, and is captured over a range that includes the left and right jaw side mechanical reference marks 19A, 19A of the member 20 located on the leading end side (jaw side) of the printing paper 24 in the transport direction, the left and right tail side mechanical reference marks 19B, 19B of the member 20 located on the trailing end side (tail side) of the printing paper 24 in the transport direction, and the left and right registration marks 10, 11, 12, 13. The register marks 10, 11, 12, and 13 printed on the pre-printed surface of the printing paper 24 are square and printed in the order of Y (yellow), M (magenta), C (cyan), and K (black, also called black) at intervals in the vertical direction from the top side in the vertical direction (the front side in the conveying direction). Three square marks 25, 26, and 27 of the same shape and size in K (black, also called black) are printed on the left side in the horizontal direction of the three register marks 10, 11, and 12 from the first register mark 10 to the third register mark 12 of the four color register marks 10, 11, 12, and 13. These three marks 25, 26, and 27 are printed to check the vertical direction of the printed printing paper and may be omitted.

[0034] 1, the first inline camera 8 is attached to a box 28 arranged at the upper front surface of the first printing unit 6A in the post-printing printing section 6 in order to capture an image of the printed paper immediately after printing on the impression cylinder of the fourth printing unit 4D in the pre-printing printing section 4 from diagonally above. The second inline camera 9 is attached to the upper front surface of a box 29 arranged at the upper front end of the paper discharge section 7 in order to capture an image of the printed paper immediately after printing on the impression cylinder of the fourth printing unit 6D in the post-printing printing section 6 from diagonally above.

[0035] A control block diagram for performing registration in a printing press is shown in Fig. 9. The control unit 21 includes an image capture area acquisition means 30 for acquiring image information of the image capture area 23 obtained by imaging with the first inline camera 8 and the second inline camera 9, an indexing means 31 for indexing the positions (centers of gravity) of the machine reference marks 19, 19 and the register marks 10, 11, 12, 13 from the image information acquired by the image capture area acquisition means 30, and a correction coefficient calculation means 32 for calculating a correction coefficient for correcting the distance between the marks derived from the positions (centers of gravity) indexed by the indexing means 31.

[0036] The correction coefficient calculation means 32 compares the vertical distance between the jaw side machine reference mark 19A and the tail side machine reference mark 19B on one side (left side) determined by the determination means 31 with the vertical distance K1 (see FIG. 4) between the jaw side machine reference mark 19A and the tail side machine reference mark 19B on one side (left side) that is obtained by actual measurement in advance, and calculates a correction coefficient according to the difference if there is a difference. The correction coefficient can also be calculated using the distance K2 (see FIG. 4). The correction coefficient is calculated in the same manner for the machine reference mark on the other side (right side). That is, the vertical distance between the jaw side machine reference mark 19A and the tail side machine reference mark 19B on the other side (right side) determined by the indexing means 31 is compared with the vertical distance K1 (see FIG. 4) between the jaw side machine reference mark 19A and the tail side machine reference mark 19B on the other side (right side) that is obtained by actual measurement in advance, and if there is a difference, a correction coefficient according to the difference is calculated. There are cases where the correction coefficient calculated on the left side and the correction coefficient calculated on the right side are not the same due to trapezoidal distortion of the captured image, etc. In that case, a value derived from the correction coefficients on the left and right sides and the horizontal positions of the registration marks by linear interpolation, etc. may be used as the correction coefficient. Note that only the correction coefficient calculated using the jaw side machine reference mark 19A and the tail side machine reference mark 19B on one side (left side) may be used. In the vertical registration, this correction coefficient is used for correction when calculating the vertical distance from the captured image.

[0037] As the correction coefficient, in addition to the correction coefficient for the top-bottom direction, a correction coefficient for the left-right direction is also calculated at the same time. That is, the left-right distance between the two gripping side mechanical reference marks 19A, 19A (or between the two trailing side mechanical reference marks 19B, 19B) in the same cutout portion 15 derived from the image information of the imaging area 23 acquired by the imaging area acquisition means 30 is compared with the left-right distance between the left and right mechanical reference marks acquired in advance by actual measurement, and if there is a difference, a correction coefficient according to the difference is calculated. In the left-right registration, this correction coefficient is used for correction when calculating the left-right distance from the captured image.

[0038] Next, the registration of the pre-printed surface and the post-printed surface will be described with reference to Figs. 7(a) and (b). In the pre-printed surface shown in Fig. 7(a), the indexing means 31 identifies the left-side reference color register mark 13 from the acquired image of the imaging area 23, and indexes the center of gravity 13G of the reference color register mark 13, and indexes the center of gravity 19G of the left-side gripping side machine reference mark 19A. Then, the control unit 21 calculates the first distance L1 in the top-bottom direction from the center of gravity 13G of the reference color register mark 13 to the center of gravity 19G of the gripping side machine reference mark 19A, taking into account (including) the correction coefficient. In addition, the indexing means 31 indexes the centers of gravity 10G, 11G, and 12G of the other color register marks 10, 11, and 12, respectively. The control unit 21 then calculates the relative distances of the centers of gravity 10G, 11G, and 12G to the center of gravity 13G of the reference color registration mark 13, taking into account (calculating) the correction coefficient. The same is done for the right side. The control unit 21 then judges whether the calculated first distance L1 and each relative distance are within a predetermined allowable range, and if it judges that they are outside the allowable range, it controls the registration device so as to bring them within the allowable range. This makes it possible to print the print pattern in the correct position on the printing paper.

[0039] In addition, the indexing means 31 identifies the left-hand reference color register mark 13 from the image of the captured image area 23 on the rear printing surface in FIG. 7(b) and indexes the center of gravity 13G of the reference color register mark 13, and indexes the center of gravity 19G of the left-hand gripping side machine reference mark 19A. The control unit then calculates the second distance L2 in the vertical direction from the center of gravity 13G of the reference color register mark 13 to the center of gravity 19G of the gripping side machine reference mark 19A, taking into account (incorporating) the correction coefficient. The indexing means 31 also indexes the centers of gravity 10G, 11G, and 12G of the other color register marks 10, 11, and 12, respectively, and the control unit 21 calculates the respective relative distances of the centers of gravity 10G, 11G, and 12G to the center of gravity 13G of the reference color register mark 13, taking into account (incorporating) the correction coefficient. The same is done for the right side. Then, the control unit 21 judges whether the calculated second distance L2 and each relative distance are within a predetermined allowable range, and if it judges that they are out of the allowable range, it controls the registration device so that they are within the allowable range. Furthermore, the indexing means 31 calculates the difference between the first distance L1 and the second distance L2. If there is a difference, it adjusts the registration in the vertical direction so that the difference is equal to or less than the allowable value. This makes it possible to print the print pattern in the correct position on the pre-printed surface and the post-printed surface of the printing paper. In the above-mentioned registration, the registration device is controlled so that the first distance L1 and the second distance L2 are each within a predetermined allowable range, but the registration device may be controlled so that the difference between the first distance L1 and the second distance L2 is within a predetermined allowable range.

[0040] As shown in Fig. 8(a), the control unit 21 calculates a third distance W1 from the left end 24C of the printing paper 24 to the center of gravity 27G of the trailing mark 27 of the three marks 25, 26, 27, taking into account (incorporating) the correction coefficient. As shown in Fig. 8(b), the control unit 21 may calculate a fourth distance W2 from the right end 24D of the printing paper 24 to the center of gravity 13G of the reference color registration mark 13, taking into account (incorporating) the correction coefficient. If the calculated third distance W1 or fourth distance W2 differs from a preset correct distance, the notification means is driven to notify the operator. In this case, since it is highly likely that the side guide is the cause, confirmation information of the side guide may also be notified.

[0041] Furthermore, the control unit 21 calculates the vertical distance between the gripping side machine reference mark 19A and the front end 24A of the printing paper 24 at each of the left and right positions of the two gripping side machine reference marks 19A, 19A from the acquired image of the imaging area 23, taking into account (incorporating) the correction coefficient, and if the calculated distance differs from a preset correct distance, it drives the notification means to notify the operator. In this case, since it is highly likely that the front stop or the reversing device is the cause, the confirmation information for the front stop and the reversing device may be notified together.

[0042] Next, the registration in the printing press having the above configuration will be described with reference to the flowcharts in Figures 10 and 11. Here, only the first distance (first distance L1) and the second distance (second distance L2) will be described, and in particular, the case where the registration device is controlled so that the difference between the first distance L1 and the second distance L2 falls within a predetermined allowable range will be described.

[0043] When the printing press starts operating, first, the first inline camera 8 starts capturing images of the machine reference marks and the register marks on the pre-printed surface (step S1). It is determined whether the images of the machine reference marks and the register marks have been captured (step S2), and if it is determined that the images have been captured, the correction coefficients are calculated by the correction coefficient calculation means 32 described above (step S3).

[0044] Next, as described above, the first distance in the vertical direction from the machine reference mark 19 to the reference color register mark 13 is calculated from the captured image with the correction coefficient taken into account (step S4). It is determined whether the first distance has been calculated (step S5), and if so, the second inline camera 9 starts capturing images of the machine reference mark and register mark on the later printed surface (step S6). It is determined whether images of the machine reference mark and register mark have been acquired (step S7), and if it is determined that the images have been acquired, the correction coefficient calculation means 32 calculates the correction coefficient (step S8).

[0045] Next, as described above, the second distance in the vertical direction from the machine reference mark 19 to the reference color registration mark 13 is calculated from the captured image by taking into account (incorporating) the correction coefficient (step S9). It is determined whether the second distance has been calculated (step S10), and if so, the difference between the first distance and the second distance, i.e., the misregistration amount between the front and back of the reference color, is calculated (step S11). It is determined whether this misregistration amount is equal to or less than the allowable value (step S12). If the misregistration amount is equal to or less than the allowable value, it is determined that no registration adjustment is necessary, and control ends.

[0046] If it is determined that the misregistration amount exceeds the allowable value, it is determined whether or not register adjustment is possible (step S13). In other words, if the misregistration amount exceeds the maximum register adjustment amount, a message indicating that register adjustment is impossible is displayed (step S14), and the registration adjustment ends. After displaying that register adjustment is impossible, the operator instructs the control unit 21 on the subsequent processing. If it is determined in step S13 that register adjustment is possible, register adjustment is performed (step S15), and the process returns to step S1 and the same processing is performed again.

[0047] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0048] In the above embodiment, a printing machine having eight printing units is shown, but a printing machine having any number of printing units greater than or equal to two may be used. Also, while a printing machine capable of double-sided printing is shown, a printing machine capable of single-sided printing may be used.

[0049] In addition, in the above embodiment, for the register marks 10, 11, and 12 of colors other than the reference color register mark 13, the relative distances to the reference color register mark 13 are calculated, but as with the reference color register mark 13, it is also possible to calculate the distance in the transport direction from the machine reference mark 19 and the left-right distance from the left and right edges of the printing paper 24.

[0050] In the above embodiment, K (also called black) is used as the reference color, but a color other than K (also called black) can also be used as the reference color.

[0051] In the above embodiment, two machine reference marks 19 (the leading edge side machine reference mark 19A and the trailing edge side machine reference mark 19B) are provided in the circumferential direction, but if no correction using a correction coefficient is performed, only one machine reference mark 19 may be provided. Also, two machine reference marks spaced apart in the left-right direction are provided in the cutout portion 15, but one machine reference mark may be provided at any one position in the left-right direction.

[0052] In the above embodiment, the machine reference mark 19 is provided in the notch 15 of the impression cylinder 14, but it may be provided at a location other than the notch 15. For example, as shown in Fig. 12, the left and right leading edge machine reference marks 19A, 19A may be provided on the outer peripheral surface 14A of the impression cylinder 14 at the front end side (leading edge side) in the transport direction of the printing paper 24 and located outside the left and right ends (24C, 24D) of the printing paper 24, and the left and right trailing edge machine reference marks 19B, 19B may be provided on the outer peripheral surface 14A of the impression cylinder 14 at the rear end side (trailing side) in the transport direction of the printing paper 24 and located outside the left and right ends (24C, 24D) of the printing paper 24. In Fig. 12, the machine reference mark 19 is provided on the outer peripheral surface 14A of the impression cylinder 14, but it may be provided at a location other than the outer peripheral surface 14A. For example, left and right jaw side machine reference marks 19A, 19A and left and right tail side machine reference marks 19B, 19B may be provided on bearers 14B, 14B (see FIG. 12) provided at both axial ends of the impression cylinder 14, spaced apart in the conveying direction. [Explanation of symbols]

[0053] 1...paper stacking tray, 2...feeder device, 3...paper supply section, 4...printing section, 4A, 4B, 4C, 4D...printing unit, 5...reversing device, 6...printing section, 6A, 6B, 6C, 6D...printing unit, 7...paper discharge section, 8...first inline camera, 9...second inline camera, 10, 11, 12, 13...register marks, 10G, 11G, 12G, 13G...center of gravity, 14...impression cylinder, 14A...outer peripheral surface, 14B...bearer, 15...notch portion, 15A...bottom wall, 15B, 15C...side wall, 16...gripper, 16A...claw, 16B...claw base, 17...support member, 18...rotating Axis, 19...machine reference mark, 19A...grip side machine reference mark, 19B...tail side machine reference mark, 19G...center of gravity, 20...member, 20A...outer surface, 21...control section, 22...registration device, 23...imaging area, 24...printing paper, 24A...front end, 24B...rear end, 24C...left end, 24D...right end, 25, 26, 27...mark, 27G...center of gravity, 28, 29...box, 30...predetermined area acquisition means, 31...indexing means, 32...correction coefficient calculation means, H1, H2, H3, H4...position, K1, K2...distance, L1, L2...distance, W1, W2...distance

Claims

1. A printing press having a printing unit that prints a print pattern and a registration mark for registration in colors including a reference color on a printing object conveyed by a cylinder, The cylinder is provided with machine reference marks; an imaging means for imaging a printing object printed by the printing unit so as to include the machine reference mark and the register mark; and an indexing means for indexing a position in the transport direction of the register mark of the reference color based on a distance in the transport direction between the machine reference mark imaged by the imaging means and at least a register mark of a reference color among the register marks.

2. 2. The printing press according to claim 1, wherein the machine reference mark is provided on an outer peripheral surface of the cylinder or an extension of the outer peripheral surface.

3. 3. The printing press according to claim 1, further comprising a correction coefficient calculation means for comparing a calculated value of a distance in the transport direction between one machine reference mark imaged by the imaging means and the other machine reference mark with an actual measured value of the distance between the one machine reference mark and the other machine reference mark, and calculating a correction coefficient according to the difference therebetween, and using the correction coefficient calculated by the correction coefficient calculation means for correction when calculating the distance in the transport direction between the machine reference mark imaged by the imaging means and the registration mark for the reference color.

4. 4. The printing press according to claim 1, wherein the machine reference mark is configured to have the same shape as the registration mark.

5. A printing press according to any one of claims 1 to 4, characterized in that a cutout portion is formed in the cylinder so as to be recessed radially inward from the outer peripheral surface of the cylinder, and the machine reference mark is provided in the cutout portion.

Images