Multifunction printer and multifunction printing method

Abstract

To provide a composite printing machine and a composite printing method which can match printing pitch of an inkjet printing with printing pitch of a gravure printing accurately and efficiently, where the composite printing machine is provided with an inkjet printing unit and a gravure printing unit.SOLUTION: A composite printing machine comprises: an inkjet printing unit 20 that prints a pattern and a mark for pitch adjustment; a gravure printing unit 30 that prints the pattern; a detecting part 41 that detects the mark for pitch adjustment; an in-feed roll 12 and a suction roll 24 which are tension adjustment parts that adjust tension of a web W related to the inkjet printing unit 30; and a control part that controls the printing pitch. The control part calculates inkjet printing pitch on the basis of the mark for pitch adjustment detected by the detecting part 41, and makes the tension adjustment part adjust tension of the web W, on the basis of a pitch deviation which is a difference between the gravure printing pitch and the inkjet printing pitch, and controls the inkjet printing pitch.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006]

[0001] The present invention relates to a composite printing machine and a composite printing method.

Background Art

[0002] Conventionally, as a printing machine for performing multicolor printing, a composite printing machine has been developed that includes a gravure printing device capable of performing high-quality printing using a plate cylinder and an inkjet printing device capable of performing printing at low cost without using a plate cylinder (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, a mark sensor senses a pattern registration mark printed first by inkjet printing and a pattern registration mark printed later by gravure printing, and controls the rotational speed of the plate cylinder of the gravure printing to perform pattern registration. <00​​​​​The present invention has been made in view of the above circumstances, and aims to provide a composite printing machine and a composite printing method that can accurately and efficiently match the printing pitch of inkjet printing and gravure printing in a composite printing machine equipped with an inkjet printing unit and a gravure printing unit. [Means for solving the problem]

[0007] To achieve the above objective, the multifunction printer according to the first aspect of this invention is: An inkjet printing unit that prints images and pitch adjustment marks printed for each image onto the web using inkjet printing, A gravure printing unit that prints an image onto the aforementioned web by gravure printing, A detection unit for detecting the pitch adjustment marks, A tension adjustment unit for adjusting the tension of the web printed by the inkjet printing unit, It comprises a control unit that controls the printing pitch, The tension adjustment unit is, The system includes an infeed roll positioned upstream of the inkjet printing unit and transporting the web to the inkjet printing unit, and a suction roll positioned downstream of the inkjet printing unit and transporting the web printed by the inkjet printing unit to a downstream process. The control unit, Based on the pitch adjustment marks detected by the detection unit, the inkjet printing pitch, which is the printing pitch of the inkjet printing unit, is calculated. Without changing the rotation speed of the plate cylinder of the gravure printing unit, The inkjet printing pitch is controlled by adjusting the tension of the web being transported by the inkjet printing unit by controlling the rotational speed of the infeed roll and the suction roll of the tension adjustment unit based on the pitch deviation amount, which is the difference between the gravure printing pitch, which is the printing pitch of the gravure printing unit, and the inkjet printing pitch.

[0009] A composite printing method according to a second aspect of this invention is: A pitch adjustment mark printing step involves printing the image and pitch adjustment marks, which are printed for each image, onto the web using inkjet printing. A pitch deviation calculation step that detects the pitch adjustment marks and calculates the inkjet printing pitch, and calculates the pitch deviation amount which is the difference between the gravure printing pitch, which is the printing pitch of the gravure printing unit that prints the image on the web by gravure printing, and the inkjet printing pitch. Without changing the rotation speed of the plate cylinder of the gravure printing unit, The method includes a pitch control step, which controls the inkjet printing pitch by adjusting the tension of the web related to the inkjet printing, by controlling the rotational speed of an infeed roll positioned upstream of the inkjet printing unit and transporting the web to the inkjet printing unit, and a suction roll positioned downstream of the inkjet printing unit and transporting the web printed by the inkjet printing unit to a downstream process, based on the amount of pitch deviation. [Effects of the Invention]

[0010] According to the composite printing press and composite printing method of the present invention, pitch matching is performed by controlling the tension related to inkjet printing based on the print pitch calculated by detecting pitch adjustment marks printed with an inkjet printer, using the print pitch of gravure printing as a reference. This makes it possible to perform pitch matching accurately and efficiently. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a multifunction printer according to Embodiment 1 of the present invention. [Figure 2] This is a front view showing the configuration of a gravure printing unit according to Embodiment 1. [Figure 3] This is a functional block diagram of the control unit according to Embodiment 1. [Figure 4]It is a flowchart showing the pitch control flow according to Embodiment 1. [Figure 5] It is a diagram showing examples of patterns and alignment marks. [Figure 6] It is a functional block diagram of the control unit according to Embodiment 2. [Figure 7] It is a flowchart showing the pitch control flow according to Embodiment 2. [Figure 8] It is a flowchart showing the pitch control flow according to a modification example. [Figure 9] It is a functional block diagram of the control unit according to Embodiment 3. [Figure 10] It is a flowchart showing the pitch control flow according to Embodiment 3.

Modes for Carrying Out the Invention

[0012] Hereinafter, a composite printing machine and a composite printing method including an inkjet printing device and a gravure printing device according to an embodiment of the present invention will be described while referring to the drawings.

[0013] (Embodiment 1) As shown in the schematic diagram of FIG. 1, the composite printing machine 1 according to the present embodiment includes an unwinding device 11 that unwinds a web W in a roll state, an infeed roll 12 that sends the web W unwound from the unwinding device 11 to the printing machine, an inkjet printing unit 20 that performs inkjet printing on the web W sent from the unwinding device 11, an intermediate feed roll 13 that conveys the inkjet printed web W to the gravure printing unit 30, a gravure printing unit 30 that performs gravure printing on the web W conveyed from the intermediate feed roll 13, an outfeed roll 14 that conveys the gravure printed web W to the winding device 15, a winding device 15 that winds up the printed web W, detection units 41 and 42 that detect marks for pitch alignment and registration, and a control unit 50 (not shown).

[0014] Web W is a long-length printing medium. The material of Web W is not particularly limited, but Web W in this embodiment is a plastic film such as biaxially oriented polypropylene (OPP) or polyethylene terephthalate (PET), which are commonly used in food packaging films, etc. As a plastic film, Web W is prone to expansion and contraction due to the influence of ambient temperature, tension fluctuations, etc., and generally has the characteristic of being prone to defects such as misregistration and pitch misalignment.

[0015] The unwinding device 11 is a device that feeds the web W, which is set in a roll state, to the inkjet printing unit 20.

[0016] The infeed roll 12 transports the web W unwound from the unwinding device 11 to the inkjet printing unit 20. The infeed roll 12 is equipped with a drive device and transports the web W at a set feed speed.

[0017] The inkjet printing unit 20 includes a pre-coat section 21, a pre-coat drying section 22, an inkjet printing section 23, a suction roll 24, and an inkjet printing drying section 25.

[0018] The pre-coat section 21 applies a pre-coat liquid to the coated surface of the web W unwound from the unwinding device 11 to form a pre-coat layer on the coated surface.

[0019] The pre-coat drying section 22 is located downstream of the pre-coat section 21 with respect to the conveying direction of the web W. The pre-coat drying section 22 dries the pre-coat liquid applied to the coated surface of the web W in the pre-coat section 21.

[0020] The inkjet printing unit 23 is positioned downstream of the pre-coat drying unit 22 with respect to the transport direction of the web W. The inkjet printing unit 23 is equipped with multiple print heads 231 that print for each color. The inkjet printing unit 23 forms an image by depositing ink ejected from the print heads 231 onto the coated surface of the web W (more specifically, the pre-coat layer formed on the coated surface).

[0021] The inkjet printing unit 23 according to this embodiment is equipped with four print heads 231 and prints a pattern in four colors: cyan (C), magenta (M), yellow (Y), and black (K), as well as a registration mark RM (color contact mark) on the web W. The registration mark RM is used to detect and correct misalignment in the printing of each color.

[0022] The inkjet-printed web W is transported to the downstream inkjet printing drying section 25 by a suction roll 24. Since the suction roll 24 transports the web W by suction, the web W can be transported stably without contacting the printed surface. Furthermore, by adjusting the rotation speed of the infeed roll 12 and the suction roll 24, the tension of the web W passing through the inkjet printing section 23 can be controlled.

[0023] In the inkjet printing drying unit 25, the ink on the surface of the web W is dried as the web W passes through the interior. The dried web W is then discharged from the inkjet printing drying unit 25.

[0024] The detection unit 41 is connected to the control unit 50 and is located downstream of the inkjet printing drying unit 25. In this embodiment, the detection unit 41 is a scanning head that detects the registration mark RM printed on the web W using an inkjet printer and transmits a detection signal to the control unit 50. The control unit 50 calculates the pitch of the inkjet-printed pattern (hereinafter referred to as the inkjet printing pitch Pi) from the detection time of the registration mark RM and the feed speed of the web W.

[0025] The intermediate feed roll 13 is positioned downstream of the inkjet printing unit 20 and transports the inkjet-printed web W to the gravure printing unit 30. The intermediate feed roll 13 is equipped with a drive mechanism and transports the web W at a set feed speed.

[0026] The gravure printing unit 30 includes a gravure printing section 31 for printing images and other designs, and a gravure printing drying section 32 for drying the printed ink. The gravure printing unit 30 according to this embodiment has one gravure printing section 31 and performs white printing. This makes it possible to print white images, which are difficult to print with sufficient density using inkjet printing, using gravure printing. Therefore, it is possible to reduce the time and cost required to produce plates other than white, and to perform high-quality printing.

[0027] Figure 2 shows a detailed configuration of the gravure printing unit 30, including the gravure printing section 31. As shown in Figure 2, the gravure printing section 31 comprises a plate cylinder 311, a finisher roll 312, an impression cylinder 313, an ink pan 314, and a doctor blade 315.

[0028] In the gravure printing section 31 of the gravure printing unit 30, the ink from the plate cylinder 311 is transferred to the web W to print the image. The plate cylinder 311 is a roll with an image corresponding to the printing color of the gravure printing section 31 engraved on its outer surface, and rotates by the driving force of a drive unit (motor) not shown. An encoder for measuring the rotation angle of the plate cylinder 311 is installed on the rotation axis of the plate cylinder 311.

[0029] The detection unit 42 is connected to the control unit 50 and is located downstream of the gravure printing unit 31. The detection unit 42 in this embodiment is a scanning head that detects the registration mark RM (hereinafter also referred to as registration mark RMi) printed on the web W using inkjet technology and the registration mark RM (hereinafter also referred to as registration mark RMg) printed using gravure technology, and transmits a detection signal to the control unit 50. The control unit 50 calculates the amount of misregistration based on the received detection signal.

[0030] The outfeed roll 14 is positioned downstream of the gravure printing unit 30. The outfeed roll 14 transports the web W printed by the inkjet printing unit 20 and the gravure printing unit 30 to the winding device 15.

[0031] The winding device 15 is a device that winds up the web W that has been fed out by the outfeed roll 14.

[0032] As shown in Figure 3, the control unit 50 includes a control unit 51, a storage unit 52, a display unit 53, and an input unit 54.

[0033] The control unit 51 consists of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and controls the operation of the entire multifunction printer 1. The control unit 51 also controls pitch misalignment, registration misalignment, etc. between inkjet printing and gravure printing based on the registration mark RM detected by the detection units 41 and 42.

[0034] The control unit 51 implements the various functions of the control unit 51 shown in Figure 3 by loading various operation programs and data stored in the ROM, memory unit 52, etc. of the control unit 51 into RAM and operating the CPU.

[0035] The control unit 51 includes a sensor information acquisition unit 511 that acquires detection information of the registration mark RM detected by the detection units 41 and 42, a calculation unit 512 that calculates the pitch deviation amount and registration deviation amount from the acquired sensor information, a pitch control unit 513 that adjusts the print pitch based on the calculated pitch deviation amount, and a registration control unit 514 that adjusts the registration deviation based on the calculated registration deviation amount.

[0036] The memory unit 52 is a non-volatile memory such as a hard disk or flash memory, and stores a program that calculates the pitch deviation and registration deviation from information such as the time when the registration mark RM is detected by the detection units 41 and 42 and the feed speed of the web W.

[0037] The display unit 53 is a display device provided in the control unit 50, and is, for example, a liquid crystal monitor. The display unit 53 displays information such as the calculated pitch deviation, registration deviation, and adjustment values ​​(control variables) based on each deviation.

[0038] The input unit 54 is an input device for inputting various settings and other values ​​for the multifunction printer 1. The input unit 54 is a keyboard, touch panel, mouse, etc., provided on the control unit 50.

[0039] Next, a composite printing method, including a method for controlling the printing pitch in the composite printing machine 1 according to this embodiment, will be described with reference to the flowchart in Figure 4.

[0040] When the operation of the multifunction printer 1 begins, the web W is unwound from the unwinding device 11 and sent to the inkjet printing unit 20 by the infeed roll 12. Then, the image stored in the storage unit 52 is inkjet printed onto the web W. Generally, the data for the image printed by inkjet printing is created by converting vector data image data input from various applications, etc., into raster data. Then, the inkjet printing unit 23 ejects ink from the print head 231 based on the created raster data and prints the image onto the web W.

[0041] In the inkjet printing unit 23, as a pitch adjustment mark printing step, the above-mentioned pattern is printed, and the registration mark RM is also printed (step S11). The registration mark RM is an indicator for detecting misalignment of the printing position that occurs in multicolor printing, and is printed by the inkjet printing unit 23 and the gravure printing unit 31 (Figure 5).

[0042] Furthermore, the registration mark RM is a pitch adjustment mark indicating the printing pitch, and as shown in Figure 5, it is printed for each print pitch, i.e., for each pattern. The registration mark RM is printed in the inkjet printing unit 23 and the gravure printing unit 31, respectively. In this embodiment, in order to detect the printing pitch related to inkjet printing (inkjet printing pitch Pi), it is printed at least in the inkjet printing unit 23.

[0043] The registration mark RMi used to detect the inkjet printing pitch Pi can be any color printed in the inkjet printing process, but for example, it is preferable to use the registration mark RMi printed in the first color closest to the infeed roll 12. This makes it possible to measure the inkjet printing pitch Pi with minimal influence from tension fluctuations, twisting, etc., associated with the transport of the web W.

[0044] The web W, on which the CMYK four-color pattern has been printed in the inkjet printing section 23, is transported to the inkjet drying section 25 by the suction roll 24. After the ink on the surface of the web W has dried in the inkjet drying section 25, it is sent from the inkjet printing unit 20 to the gravure printing unit 30.

[0045] Next, as a pitch deviation calculation step, the sensor information acquisition unit 511 of the control unit 51 controls the detection unit 41 located between the inkjet printing unit 20 and the gravure printing unit 30 to detect the registration mark RMi printed on the web W (step S12). The calculation unit 512 calculates the inkjet printing pitch Pi based on the timing of detection of the registration mark RMi and the feed speed of the web W (step S13). The feed speed of the web W may be a speed preset as the feed speed of the composite printer 1, or a measured value may be used. The measured value is, for example, a value measured based on the measurement value of an encoder installed on the infeed roll 12 that transports the web W to the inkjet printing unit 23.

[0046] Furthermore, the calculation unit 512 calculates the pitch of the gravure-printed image (hereinafter referred to as the gravure printing pitch Pg) based on the plate cylinder diameter of the gravure printing unit 31, which has been pre-input and stored in the storage unit 52 (step S14). The gravure printing pitch Pg is calculated based on the circumference length calculated from the diameter of the plate cylinder 311, the material of the web W, the tension applied to the web W, etc. The gravure printing pitch Pg only needs to be calculated once when the operation of the composite printing press 1 starts, so thereafter, the value of the gravure printing pitch Pg that has been calculated and stored in the storage unit 52 can be used. Alternatively, the gravure printing pitch Pg may be read from a table that has been pre-stored in the storage unit 52 as a value corresponding to the set plate cylinder diameter, the material of the web W, the tension applied to the web W, etc.

[0047] Furthermore, the calculation unit 512 calculates the difference between the inkjet printing pitch Pi calculated in step S13 and the gravure printing pitch Pg calculated in step S14 as the pitch deviation amount (step S15).

[0048] Next, as a pitch control step, the pitch control unit 513 of the control unit 51 controls the inkjet printing pitch Pi based on the calculated pitch deviation amount (step S16). Specifically, the inkjet printing pitch Pi is controlled by adjusting the feed direction length of the pattern printed by the inkjet printing unit 20.

[0049] The control unit 51 measures the feed speed of the web W based on the measurement value obtained from the measurement unit 121 (not shown), which is an encoder for the infeed roll 12 that transports the web W to the inkjet printing unit 20. The pitch control unit 513 then adjusts the ink ejection timing by multiplying the number of pulses from the measurement unit 121, which indicates the feed speed of the web W, by a predetermined coefficient. The predetermined coefficient is set based on the amount of pitch deviation. This allows the relationship between the feed speed of the web W and the ink ejection timing to be adjusted, thereby adjusting the length of the image printed on the web W in the feed direction.

[0050] As described above, the print pitch adjustment in this embodiment is performed by adjusting the inkjet print pitch Pi based on the gravure print pitch Pg. Therefore, since the print pitch of the inkjet print unit 23 can be adjusted based on the print pitch of the gravure print unit 31, which can print with a more stable pitch, the print pitch can be easily and accurately controlled.

[0051] The inkjet-printed web W is transported from the inkjet printing unit 20 to the gravure printing unit 30 by the intermediate feed roll 13. The gravure printing unit 31 prints the image onto the web W using gravure printing. The gravure printing unit 31 prints the image in white. In addition, the gravure printing unit 31 prints the registration mark RMg along with the image (step S17).

[0052] The detection unit 42, located downstream of the gravure printing unit 31, detects the inkjet-printed registration mark RMi and the gravure-printed registration mark RMg from the web W after gravure printing. Based on this, the calculation unit 512 calculates the amount of misregistration between the inkjet print and the gravure print (step S18).

[0053] A known method can be used to calculate the amount of misregistration. For example, the registration mark RMi printed by the inkjet printing unit 23 and the registration mark RMg printed by the gravure printing unit 31 are set to be printed at a predetermined interval (e.g., 20 mm), and two sensors provided in the detection unit 42, which is a scanning head, are arranged at the same interval as the registration marks RMi and RMg. The amount of misregistration can then be calculated based on the timing difference in when each sensor of the detection unit 42 detects the registration marks RMi and RMg, and the feed speed of the web W.

[0054] The registration control unit 514 performs registration control based on the calculated misregistration amount (step S19). Registration control is performed, for example, by adjusting the phase angle of the plate cylinder motor that rotates the plate cylinder 311 of the gravure printing unit 31. More specifically, the intermediate feed motor that drives the intermediate feed roll 13 and the plate cylinder motor that drives the plate cylinder 311 rotate in synchronous control. When misregistration is detected from the calculated misregistration amount, the registration control unit 514 shifts the phase angle of the plate cylinder motor to correspond to the misregistration amount. This allows for adjustment of the feed direction position of the gravure printed image while suppressing the effect on the tension of the web W of the inkjet printing unit 23, thereby aligning the registration between inkjet printing and gravure printing.

[0055] After passing through the detection unit 42, the web W is transported to the gravure printing drying unit 32. By passing through the gravure printing drying unit 32, the ink transferred to the web W by gravure printing is dried. The dried web W is sent to the winding device 15 by the outfeed roll 14 and wound up by the winding device 15.

[0056] The aforementioned print pitch control and registration control are performed for each print pitch of the image and continue until printing is complete.

[0057] As described in detail above, according to the combined printing press 1 of this embodiment, in a combined printing press 1 that combines an inkjet printing unit 20 and a gravure printing unit 30, the length of the image printed by the inkjet printing unit 20 in the feeding direction is adjusted based on the printing pitch of the gravure printing. Specifically, the length of the image in the feeding direction is adjusted by controlling the ink ejection timing by multiplying the feed speed of the web W by a predetermined coefficient. Therefore, pitch control can be performed more efficiently compared to when the length of the image in the feeding direction is controlled using a mechanical tension adjustment device. Furthermore, since the pitch adjustment is performed based on the printing pitch of gravure printing, which has a more stable printing pitch, pitch control can be performed with high precision.

[0058] Furthermore, for example, when adjusting the inkjet printing pitch Pi using a dancer roll, intermediate feed roll 13, etc., installed between the inkjet printing unit 20 and the gravure printing unit 30, the tension fluctuations affect not only the inkjet printing section 23 but also the gravure printing section 31, causing the gravure printing pitch Pg to fluctuate. Consequently, further tension adjustment becomes necessary, and it takes time for the pitch control to converge. In contrast, with the pitch control by pattern adjustment according to this embodiment, no fluctuations occur in the gravure printing pitch Pg, thus improving the convergence of the pitch control.

[0059] Furthermore, by performing registration control and print pitch control independently, accurate registration and print pitch control can be achieved for both inkjet and gravure printing.

[0060] In this embodiment, a registration mark RMi printed in a predetermined color on the inkjet printing unit 23 is used as a pitch adjustment mark, but the invention is not limited to this. For example, a registration mark RMi printed on the web W for each color print head 231 of the inkjet printing unit 23 may be used, and a coefficient multiplied by the feed speed for each color to be printed may be set to control the feed direction length of the image. This makes it possible to independently adjust the pitch of inkjet printing and gravure printing, as well as the pitch of each color in gravure printing, thereby enabling higher quality printing.

[0061] In this embodiment, scanning heads are used as detection units 41 and 42 for detecting the registration mark RM, but the invention is not limited to this, and cameras may be used instead. Specifically, the combined printer 1 is equipped with a camera instead of a scanning head. The image analysis unit of the control unit 50 analyzes the image of the registration mark RMi captured by the camera, which is the detection unit 41, and calculates the inkjet printing pitch Pi based on the detection time of the registration mark RMi, the feed speed of the web W, etc. The control unit 51 calculates the gravure printing pitch Pg based on the circumference of the plate cylinder of the gravure printing unit 31, etc., and calculates the amount of pitch misalignment based on the inkjet printing pitch Pi and the gravure printing pitch Pg, and controls the printing pitch. Alternatively, the image analysis unit of the control unit 50 may analyze the images of the registration marks RMi and RMg captured by the camera, which is the detection unit 42, to detect misalignment between inkjet printing and gravure printing. This makes it possible to detect misalignment and printing pitch misalignment using a general-purpose camera.

[0062] Furthermore, in this embodiment, registration control and print pitch control are performed using a registration mark RM, but this is not limited to this. For example, the inkjet printing unit 23 may print a pitch alignment mark PM that is different from the registration mark RM, and the control unit 51 may perform print pitch control using the pitch alignment mark PM. The form of the pitch alignment mark PM is not particularly limited. Also, the pitch alignment mark PM may be a mark printed for the purpose of measuring the print pitch, or it may be a mark with another purpose, such as a mark indicating the cutting position of the web W.

[0063] (Embodiment 2) In the above-described embodiment 1, the ink ejection timing was adjusted by multiplying the measured feed speed of the web W by a predetermined coefficient. However, the print pitch can also be controlled by adjusting the feed direction length of the image related to inkjet printing using other methods. This embodiment describes a method for controlling the print pitch by adjusting the image data related to inkjet printing.

[0064] In this embodiment, the method for adjusting the length of the pattern feed direction differs from that of Embodiment 1. However, the configuration of the other parts of the composite printer 1' is the same as that of the composite printer 1 in Embodiment 1, so the same reference numerals are used and detailed explanations are omitted.

[0065] Figure 6 is a functional block diagram of the control unit 50' according to this embodiment. As shown in Figure 6, the control unit 51' of the control unit 50' includes a pattern data adjustment unit 515, which adjusts the pattern data to be printed by the inkjet printing unit 23.

[0066] The following describes a composite printing method, including a method for controlling the printing pitch in the composite printing machine 1' according to this embodiment, with reference to the flowchart in Figure 7. Similar to Embodiment 1, the web W unwound from the unwinding device 11 is transported to the inkjet printing unit 20 by the infeed roll 12.

[0067] Next, in the pitch adjustment mark printing step, the inkjet printing section 23 of the inkjet printing unit 20 prints a CMYK four-color pattern and a registration mark RMi, which is a pitch adjustment mark, onto the web W (step S21). Then, the web W is transported by the suction roll 24 to the inkjet printing drying section 25, and after being dried in the inkjet printing drying section 25, it is sent to the gravure printing unit 30.

[0068] Next, as a pitch deviation calculation step, the sensor information acquisition unit 511 of the control unit 51' controls the detection unit 41 located between the inkjet printing unit 20 and the gravure printing unit 30 to detect the registration mark RMi printed on the web W (step S22). The calculation unit 512 calculates the inkjet printing pitch Pi, which is the printing pitch of the inkjet printing unit 23, based on the timing of detection of the registration mark RMi and the feed speed of the web W (step S23). The feed speed of the web W may be a speed preset as the feed speed of the composite printer 1', or a measured value may be used. The measured value is, for example, a value measured based on the measurement value of an encoder installed on the infeed roll 12 that transports the web W to the inkjet printing unit 23.

[0069] Furthermore, the calculation unit 512 calculates the gravure printing pitch Pg based on the plate cylinder diameter of the gravure printing unit 31, which has been pre-input and stored in the storage unit 52 (step S24). The gravure printing pitch Pg is calculated based on the circumference length calculated from the diameter of the plate cylinder 311, the material of the web W, the tension applied to the web W, etc. The gravure printing pitch Pg only needs to be calculated once at the start of operation of the composite printing press 1', so thereafter, the value of the gravure printing pitch Pg that has been calculated and stored in the storage unit 52 can be used. Alternatively, the gravure printing pitch Pg may be read from a table pre-stored in the storage unit 52 as a value corresponding to the set plate cylinder diameter, the material of the web W, the tension applied to the web W, etc.

[0070] Furthermore, the calculation unit 512 calculates the difference between the inkjet printing pitch Pi calculated in step S23 and the gravure printing pitch Pg calculated in step S24 as the pitch deviation amount (step S25).

[0071] Next, in the pitch control step, the pattern data adjustment unit 515 of the control unit 51' controls the inkjet printing pitch Pi by adjusting the feed direction length of the pattern to be printed by the inkjet printing unit 20 based on the calculated pitch deviation amount (step S26).

[0072] Specifically, the pattern data adjustment unit 515 modifies the data to adjust the feed length of the pattern to be printed by the inkjet printing unit 23 based on the pitch deviation amount calculated in step S25. For example, if the inkjet printing pitch Pi is longer than the gravure printing pitch Pg, the pattern data adjustment unit 515 modifies the data so that the raster data of each color pattern stored in the storage unit 52 is reduced in the feed direction. Also, if the inkjet printing pitch Pi is shorter than the gravure printing pitch Pg, the pattern data adjustment unit 515 modifies the data so that the raster data of each color pattern stored in the storage unit 52 is enlarged in the feed direction. Then, the pattern data adjustment unit 515 controls the inkjet printing unit 23 to print the pattern based on the modified pattern data.

[0073] As described above, the print pitch control in this embodiment is performed by adjusting the inkjet print pitch Pi based on the gravure print pitch Pg. Therefore, since the print pitch of the inkjet print unit 23 can be adjusted based on the print pitch of the gravure print unit 31, which can print at a more stable pitch, the print pitch can be easily and accurately controlled.

[0074] The inkjet-printed web W is transported from the inkjet printing unit 20 to the gravure printing unit 30 by the intermediate feed roll 13. Then, as in Embodiment 1, registration control is performed between the inkjet printing and gravure printing based on the inkjet-printed registration mark RMi and the gravure-printed registration mark RMg (step S27).

[0075] The web W, which has been inkjet and gravure printed, is sent to the winding device 15 by the outfeed roll 14 and wound up by the winding device 15. The aforementioned print pitch control and registration control are performed for each print pitch of the image and continue until printing is complete.

[0076] As described above, the combined printer 1' according to this embodiment adjusts the inkjet printing pitch Pi by modifying the data of the image printed by the inkjet printing unit 23 based on the amount of pitch deviation. This makes it possible to adjust the length of the image in the feeding direction while maintaining an appropriate ink ejection timing for the feed speed of the web W during inkjet printing. Therefore, it is possible to print more detailed images compared to when the ink ejection timing is controlled based on the measured value of the encoder.

[0077] Furthermore, by performing registration control and print pitch control independently, accurate registration and print pitch control can be achieved for both inkjet and gravure printing.

[0078] In this embodiment, the control unit 51' modifies the rasterized data used for inkjet printing based on the pitch deviation amount, but it is not limited to this. For example, the control unit 51' may adjust the feed direction length of the image data before rasterization input to the multifunction printer 1' based on the calculated pitch deviation amount, and then convert the adjusted image data into raster data for printing with the inkjet printing unit 23. This allows for print pitch control by adjusting the feed direction length of the image using the original image data, making it possible to perform more detailed and high-quality printing compared to adjusting the feed direction length of the rasterized data.

[0079] In this embodiment, the registration mark RMi for pitch adjustment is printed in a predetermined color of the inkjet printing unit 23, but this is not limited to this. For example, the registration mark RMi printed on the web W for each color print head 231 of the inkjet printing unit 23 may be used to adjust the pattern data for each color to be printed and control the length of the pattern in the feed direction. This makes it possible to adjust the pitch of inkjet printing and gravure printing, as well as the pitch of each color of gravure printing independently, thereby enabling higher quality printing.

[0080] (modified version) In Embodiments 1 and 2 described above, the printing pitch control and registration control in the combined printing press 1,1' during printing operation were mainly assumed. However, printing pitch control and registration control can also be performed as initial registration at the start of printing. The method for initial registration according to the present invention will be described below with reference to the flowchart in Figure 8.

[0081] First, as an initial setup, the web W is placed on the unwinding device 11, and various setting data, inkjet printing data, etc. are input from the input unit 54, etc. (step S31). Next, the multifunction printer 1 is operated, and as an inkjet registration mark printing step, the inkjet printing unit 20 prints the pattern and registration mark RMi onto the web W, similar to Embodiment 1 (step S32). Also, as a gravure registration mark printing step, the gravure printing unit 30 prints the pattern and registration mark RMg onto the web W (step S33).

[0082] As a step in calculating the pitch deviation, the control unit 50 detects the registration mark RMi with the detection unit 41 and calculates the inkjet printing pitch Pi, similar to the first embodiment (step S34). The control unit 50 also calculates the gravure printing pitch Pg based on the plate cylinder diameter of the gravure printing unit 31, which has been pre-input and stored in the storage unit 52 (step S35). Furthermore, the control unit 50 calculates the pitch deviation, which is the difference between the inkjet printing pitch Pi and the gravure printing pitch Pg (step S36).

[0083] Furthermore, as a misregistration calculation step, the control unit 50 detects the registration mark RMi printed in the inkjet registration mark printing step and the registration mark RMg printed in the gravure registration mark printing step using the detection unit 42, and calculates the misregistration amount between the inkjet printing and the gravure printing (step S37).

[0084] As an initial registration step, the control unit 50 controls the inkjet printing pitch Pi by adjusting the feed direction length of the image to be printed by the inkjet printing unit 20 based on the calculated pitch misalignment amount, similar to Embodiment 1 or Embodiment 2 (step S38). The control unit 50 also controls the printing position, i.e., the printing timing, of the image to be printed by the inkjet printing unit 20 based on the calculated misalignment amount to perform registration at the start of printing (step S39).

[0085] As explained above, in this modified configuration, in a combined printing press 1 that combines an inkjet printing unit 20 and a gravure printing unit 30, the printing pitch at the start of printing is controlled by adjusting the feed length of the image printed by the inkjet printing unit 20, based on the printing pitch of the gravure printing. Furthermore, registration control at the start of printing is controlled by adjusting the printing position of the image on the inkjet printing unit 20, based on the registration mark RMg of the gravure printing. Therefore, initial registration, which would otherwise require complex adjustments, can be performed by adjusting the inkjet printing unit 20, making it easy to perform initial registration with high accuracy.

[0086] (Embodiment 3) In the above-described embodiments 1 and 2, the print pitch was controlled by adjusting the length of the pattern in the feed direction in the inkjet printing unit 23, but the print pitch can also be controlled by other methods. In this embodiment, a method of controlling the print pitch by adjusting the tension related to inkjet printing will be described.

[0087] In this embodiment, the control unit 51'' of the multifunction printer 2 differs from the multifunction printer 1 of Embodiment 1 in that it includes a tension control unit 516. The other configurations are the same as in Embodiment 1, so the same reference numerals are used and detailed descriptions are omitted.

[0088] Figure 9 is a functional block diagram of the control unit 50'' of the multifunction printer 2. The control unit 51'' of the control unit 50'' includes a tension control unit 516. The tension control unit 516 adjusts the tension of the web W printed by the inkjet printing unit 20 by controlling the rotational speed of the infeed roll 12 and the suction roll 24, thereby adjusting the inkjet printing pitch Pi.

[0089] The following describes a composite printing method, including a method for controlling the printing pitch in the composite printing machine 2 according to this embodiment, with reference to the flowchart in Figure 10. Similar to Embodiment 1, the web W unwound from the unwinding device 11 is transported to the inkjet printing unit 23 by the infeed roll 12. Then, as a pitch adjustment mark printing step, the inkjet printing unit 23 prints a CMYK four-color pattern and a registration mark RM on the web W (step S41). The web W is then transported to the inkjet printing drying unit 25 by the suction roll 24, and after being dried in the inkjet printing drying unit 25, it is sent to the gravure printing unit 30.

[0090] Next, as a pitch deviation calculation step, the sensor information acquisition unit 511 of the control unit 51'' controls the detection unit 41 located between the inkjet printing unit 20 and the gravure printing unit 30 to detect the pitch adjustment registration mark RMi printed on the web W (step S42). The calculation unit 512 calculates the inkjet printing pitch Pi, which is the printing pitch of the inkjet printing unit 23, based on the timing of detection of the pitch adjustment registration mark RMi and the feed speed of the web W (step S43). The feed speed of the web W may be a speed preset as the feed speed of the composite printer 2, or a measured value may be used. The measured value is, for example, a value measured based on the measurement value of an encoder installed on the infeed roll 12 that transports the web W to the inkjet printing unit 23.

[0091] Furthermore, the calculation unit 512 calculates the gravure printing pitch Pg based on the plate cylinder diameter of the gravure printing unit 31, which has been pre-input and stored in the storage unit 52 (step S44). The gravure printing pitch Pg is calculated based on the circumference length calculated from the diameter of the plate cylinder 311, the material of the web W, the tension applied to the web W, etc. The gravure printing pitch Pg only needs to be calculated once when the operation of the composite printing press 2 starts, so thereafter, the value of the gravure printing pitch Pg that has been calculated and stored in the storage unit 52 can be used. Alternatively, the gravure printing pitch Pg may be read from a table that has been pre-stored in the storage unit 52 as a value corresponding to the set plate cylinder diameter, the material of the web W, the tension applied to the web W, etc.

[0092] Furthermore, the calculation unit 512 calculates the difference between the inkjet printing pitch Pi calculated in step S43 and the gravure printing pitch Pg calculated in step S44 as the pitch deviation amount (step S45).

[0093] Next, in the pitch control step, the tension control unit 516 of the control unit 51'' controls the inkjet printing pitch Pi based on the calculated pitch deviation (step S46). Specifically, the tension control unit 516 reads the tension corresponding to the calculated pitch deviation from the correspondence table stored in the storage unit 52 and controls the rotation speed of at least one of the infeed roll 12 and suction roll 24, which are tension adjustment units. This controls the tension applied to the web W of the gravure printing unit 31 and adjusts the length of the printed image in the feeding direction, thereby controlling the printing pitch.

[0094] As described above, the print pitch control in this embodiment is performed by adjusting the inkjet print pitch Pi based on the gravure print pitch Pg. Therefore, since the print pitch of the inkjet print unit 23 can be adjusted based on the print pitch of the gravure print unit 31, which can print at a more stable pitch, it is possible to control the print pitch efficiently and accurately.

[0095] The inkjet-printed web W is transported from the inkjet printing unit 20 to the gravure printing unit 30 by the intermediate feed roll 13. Then, as in Embodiment 1, registration control is performed between the inkjet printing and gravure printing based on the inkjet-printed registration mark RMi and the gravure-printed registration mark RMg (step S47).

[0096] The web W, which has been inkjet and gravure printed, is sent to the winding device 15 by the outfeed roll 14 and wound up by the winding device 15. The aforementioned print pitch control and registration control are performed for each print pitch of the image and continue until printing is complete.

[0097] As described above, the combined printing press 2 according to this embodiment adjusts the inkjet printing pitch Pi by controlling the tension of the web W for gravure printing based on the pitch deviation amount calculated by the control unit 51''. This reduces the computational load related to adjusting the printed pattern and enables responsive printing pitch control with simple control. Furthermore, since tension control is performed by adjusting the rotational speed of the infeed roll 12 and the suction roll 24, compared to the case where tension control is performed using an intermediate feed roll 13, dancer roll, etc., which are placed between the inkjet printing unit 20 and the gravure printing unit 30 and transport the web W to the gravure printing unit 30, the tension control does not affect the gravure printing section 31, so stable tension control with good convergence can be achieved.

[0098] Furthermore, by performing registration control and print pitch control independently, accurate registration and print pitch control can be achieved for both inkjet and gravure printing. [Explanation of Symbols]

[0099] 1,1',2 Combined printing press, 11 Unwinding device, 12 Infeed roll, 121 Measurement unit, 13 Intermediate feed roll, 14 Outfeed roll, 15 Winding device, 20 Inkjet printing unit, 21 Precoat unit, 22 Precoat drying unit, 23 Inkjet printing unit, 231 Print head, 24 Suction roll, 25 Inkjet printing drying unit, 30 Gravure printing unit, 31 Gravure printing unit, 311 Plate cylinder, 312 Furnishing roll, 313 Impression cylinder, 314 Ink pan, 315 Doctor blade, 32 Gravure printing drying unit, 41,42 Detection unit, 50,50',50'' Control unit, 51,51',51'' Control unit, 511 Sensor information acquisition unit, 512 Calculation unit, 513 Pitch control unit, 514 Registration control unit, 515 Pattern data adjustment unit, 516 Tension control unit, 52 memory unit, 53 display unit, 54 input unit, RM registration mark, W web

Claims

1. An inkjet printing unit that prints images and pitch adjustment marks printed for each image onto the web using inkjet printing, A gravure printing unit that prints an image onto the aforementioned web by gravure printing, A detection unit for detecting the pitch adjustment marks, A tension adjustment unit for adjusting the tension of the web printed by the inkjet printing unit, It comprises a control unit that controls the printing pitch, The tension adjustment unit is, The system includes an infeed roll positioned upstream of the inkjet printing unit and transporting the web to the inkjet printing unit, and a suction roll positioned downstream of the inkjet printing unit and transporting the web printed by the inkjet printing unit to a downstream process. The control unit, Based on the pitch adjustment marks detected by the detection unit, the inkjet printing pitch, which is the printing pitch of the inkjet printing unit, is calculated. Without changing the rotation speed of the plate cylinder of the gravure printing unit, Based on the pitch deviation, which is the difference between the gravure printing pitch (the printing pitch of the gravure printing unit) and the inkjet printing pitch, the rotational speed of the infeed roll and the suction roll of the tension adjustment unit is controlled to adjust the tension of the web being transported by the inkjet printing unit, thereby controlling the inkjet printing pitch. A multifunction printing press characterized by the following features.

2. A pitch adjustment mark printing step involves printing the image and pitch adjustment marks, which are printed for each image, onto the web using inkjet printing. A pitch deviation calculation step that detects the pitch adjustment marks and calculates the inkjet printing pitch, and calculates the pitch deviation amount which is the difference between the gravure printing pitch, which is the printing pitch of the gravure printing unit that prints the image on the web by gravure printing, and the inkjet printing pitch. A pitch control step includes controlling the inkjet printing pitch by adjusting the tension of the web related to the inkjet printing, without changing the rotation speed of the plate cylinder of the gravure printing unit, by controlling the rotation speed of an infeed roll positioned upstream of the inkjet printing unit and transporting the web to the inkjet printing unit, and a suction roll positioned downstream of the inkjet printing unit and transporting the web printed by the inkjet printing unit to a downstream process, based on the amount of pitch deviation, without changing the rotation speed of the plate cylinder of the gravure printing unit. A composite printing method characterized by the following features.

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