Printing system and method for manufacturing printed matter

Abstract

Provided are a printing system for aligning the positions of two images, and a method for manufacturing printed matter. A printing system according to the present disclosure conveys a base material in a first direction sequentially to a first image formation device that forms a first image on the basis of first image data, a first measurement device that measures the width of the base material, a second image formation device that forms a second image on the basis of second image data, and a second measurement device that measures the width of the base material. A processor positionally aligns the first image data and the second image data on the basis of a reference position of the base material. On the basis of a measurement result from the first measurement device and a measurement result form the second measurement device, the processor calculates a first correction value for correcting the position of the second image data in a second direction intersecting the first direction.

Description

Printing System and Method for Manufacturing Printed Matter

[0001] The present invention relates to a printing system and a method for manufacturing printed matter, and particularly to a technique for correcting the position of an image.

[0002] There is known a printing apparatus that forms an image by applying ink to a substrate, dries the substrate, and then further applies ink to the substrate to form an image. In such a printing apparatus, the substrate may expand or contract due to intermediate drying, and the sizes of the images before and after drying may be different.

[0003] In contrast, Patent Document 1 discloses a web printing apparatus including a first printing unit that prints a first test pattern and a first image on a first surface of a web, and a second printing unit that prints a second test pattern and a second image on a second surface of the web. The apparatus obtains a first ratio indicating the ratio of a first size reflecting the size of the first test pattern in the width direction of the web to the width of the web from a first captured image of the first surface, and a second ratio indicating the ratio of a second size reflecting the size of the second test pattern in the width direction of the web to the width of the web from a second captured image of the second surface, and adjusts the widths in the width direction of the first image and the second image according to the first ratio and the second ratio.

[0004] Patent Document 1 further describes adjusting the position in the width direction of at least one of the first image and the second image according to the difference between the distance in the width direction between the edge of the web and the first test pattern and the distance in the width direction between the edge of the web and the second test pattern.

[0005] Japanese Patent Application Laid-Open No. 2022-38158

[0006] In the web printing apparatus described in Patent Document 1, although the widths of the first image and the second image can be made to match, there are cases where the positions of the first image and the second image cannot be correctly adjusted.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a printing system and a method for manufacturing printed matter that align the positions of two images.

[0008] To achieve the above objective, a printing system according to a first aspect of the present disclosure is a printing system for printing an image on a substrate, comprising: a transport device for transporting the substrate in a first direction; a first image forming device for forming a first image based on first image data; a first measuring device for measuring the width of the substrate in a second direction intersecting the first direction; a second image forming device for forming a second image based on second image data; a second measuring device for measuring the width of the substrate in a second direction; and a processor, wherein the transport device transports the substrate in the order of the first image forming device, the first measuring device, the second image forming device, and the second measuring device; the processor aligns the first image data and the second image data based on a reference position of the substrate, and calculates a first correction value for correcting the position of the second image data in a second direction based on the measurement result of the first measuring device and the measurement result of the second measuring device.

[0009] In the printing system according to the second aspect of the present disclosure, it is preferable that, in the printing system according to the first aspect, a second correction value is calculated to correct the scaling of the second image data in a second direction based on the measurement result of a first measuring device and the measurement result of a second measuring device.

[0010] A printing system according to a third aspect of the present disclosure is a printing system according to a second aspect, wherein the first image data includes a first alignment mark, and the second image data includes a user image area for freely arranging a user image and an accessory image area on which the second alignment mark is placed, and the processor aligns the first image data and the second image data using the positions of the first alignment mark and the second alignment mark formed on the substrate as reference positions, corrects the scaling in a second direction for the user image area of ​​the second image data using a second correction value, and calculates a first correction value based on the position of the second alignment mark formed on the substrate and the second correction value.

[0011] In the printing system according to the fourth aspect of the present disclosure, in the printing system according to the third aspect, it is preferable that the second alignment mark formed on the substrate is positioned at a position at a first distance in the second direction from the center position of the substrate in the second direction.

[0012] In a printing system according to a fifth aspect of this disclosure, in a printing system according to a third or fourth aspect, it is preferable that the user image area formed on the substrate is positioned such that the central position in the second direction is located at a second distance in the second direction from the central position of the substrate in the second direction.

[0013] In the printing system according to the sixth aspect of this disclosure, in the printing system according to the third or fourth aspect, it is preferable that the user image area formed on the substrate is positioned such that the central position in the second direction is located at the central position of the substrate in the second direction.

[0014] In the seventh aspect of this disclosure, the printing system, in any of the first to sixth aspects, preferably has a processor that aligns the first image data and the second image data with respect to the distance from the edge of the substrate in the second direction, using the edge of the substrate in the second direction as the reference position.

[0015] In the eighth aspect of the present disclosure, the printing system is preferably such that the processor displays a first correction value on a display, in a printing system according to any of the first to seventh aspects.

[0016] In the printing system according to the ninth aspect of this disclosure, in the printing system according to any of the first to eighth aspects, it is preferable that the processor corrects the position of the second image data in the second direction with a first correction value.

[0017] In the printing system according to the tenth aspect of this disclosure, in the printing system according to the ninth aspect, it is preferable that the second image forming apparatus forms a corrected second image based on the corrected second image data.

[0018] A printing system according to an eleventh aspect of the present disclosure, in a printing system according to any of the first to tenth aspects, comprises a first drying device for drying a first image formed on a substrate, and preferably the transport device transports the substrate in the order of a first image forming device, a first measuring device, a first drying device, a second image forming device, and a second measuring device.

[0019] To achieve the above objective, a method for manufacturing a printed article according to a twelfth aspect of the present disclosure is a method for manufacturing a printed article, comprising: transporting a substrate in a first direction in the order of a first image forming apparatus, a first measuring apparatus, a second image forming apparatus, and a second measuring apparatus; forming a first image on the substrate based on first image data in the first image forming apparatus; measuring the width of the substrate in a second direction intersecting the first direction in the first measuring apparatus; forming a second image on the substrate based on second image data in the second image forming apparatus; measuring the width of the substrate in a second direction in the second measuring apparatus; aligning the first image data and the second image data based on a reference position of the substrate; calculating a first correction value to correct the position of the second image data in a second direction based on the measurement result of the first measuring apparatus and the measurement result of the second measuring apparatus; correcting the position of the second image data in a second direction with the first correction value; and forming a corrected second image on the substrate based on the corrected second image data in the second image forming apparatus.

[0020] In the method for manufacturing printed materials according to the twelfth embodiment, the configuration may include specific embodiments similar to those of the printing system described above.

[0021] According to the present invention, the positions of two images can be aligned.

[0022] Figure 1 is a diagram illustrating an example of an inkjet printing system. Figure 2 is a block diagram showing the electrical configuration of the inkjet printing system. Figure 3 is a diagram illustrating the registration alignment between a color image and a white image. Figure 4 is a diagram illustrating the automatic registration adjustment function. Figure 5 is a diagram illustrating print data. Figure 6 is a diagram illustrating the generation of print data. Figure 7 is a diagram illustrating an example of the mechanism by which a misalignment in the X direction occurs between a color image and a white image. Figure 8 is a diagram illustrating another example of the mechanism by which a misalignment in the X direction occurs between a color image and a white image. Figure 9 is a diagram illustrating the configuration of a second measuring device. Figure 10 is a flowchart illustrating a method for manufacturing printed materials using an inkjet printing system.

[0023] [Overall Configuration of the Printing System] The printing system is a system that produces printed materials by printing an image onto a substrate. The substrate may be a single sheet or a continuous long sheet. The printing method may be inkjet printing, screen printing, letterpress printing, intaglio printing, offset printing, gravure printing, flexographic printing, etc. Here, we will describe an inkjet printing system that prints on a long substrate using the inkjet method. Figure 1 is a diagram showing an example of an inkjet printing system. The inkjet printing system 10 shown in Figure 1 transports a long, non-permeable substrate 1 and outputs a printed image including a color image and a white image to the printing surface of the substrate 1.

[0024] The substrate 1 is a non-permeable medium, such as a transparent film substrate used in flexible packaging. Examples of film substrates include PET (Polyethylene Terephthalate), OPP (Oriented Poly Propylene), and NY (Nylon). The inkjet printing system 10 produces reverse-printed materials on the substrate 1, where the printed object is visible from the non-printed side, which is the side opposite the printed surface.

[0025] Furthermore, "non-permeable" means that it is non-permeable to water-based inks, which will be described later. Flexible packaging refers to packaging made of a material that deforms according to the shape of the article being packaged. Transparent means that the transmittance of visible light is 30 percent or more and 100 percent or less, preferably 70 percent or more and 100 percent or less.

[0026] The inkjet printing system 10 includes a transport device 20, a first printing device 30, a second printing device 40, and a substrate information acquisition unit 50.

[0027] The conveying device 20 conveys the base material 1 in a roll-to-roll manner along a conveying path from an unwinding roll (not shown) to a winding roll (not shown). The conveying device 20 includes a plurality of pass rollers 22. The pass rollers 22 convey the base material 1 in the conveying direction (an example of the "first direction") by rotating in contact with the base material 1. The base material 1 may be conveyed under tension. The conveying speed of the base material 1 in the conveying direction (conveying speed) is, for example, 50 meters / minute.

[0028] In the example shown in Figure 1, the conveying device 20 conveys the base material 1 in a conveying direction along the Y direction, but the conveying direction of the base material 1 may be appropriately changed to a direction other than the Y direction using a folding roller (not shown).

[0029] The first printing device 30 and the second printing device 40 are arranged in the transport path of the substrate 1 from the upstream side, in the order of the first printing device 30 and the second printing device 40.

[0030] The first printing apparatus 30 includes a first ejection device 30A and a first drying device 30B. The substrate 1 transported to the first printing apparatus 30 is guided by the pass roller 22 and transported to the first ejection device 30A.

[0031] The first ejection device 30A (an example of the "first image forming apparatus") includes inkjet heads 32K, 32C, 32M, and 32Y. The inkjet heads 32K, 32C, 32M, and 32Y eject black (K), cyan (C), magenta (M), and yellow (Y) color inks (an example of the "first liquid"), respectively. Each color ink is an aqueous ink obtained by dissolving or dispersing a coloring material such as a dye or pigment in water and a water-soluble solvent. Each of the inkjet heads 32K, 32C, 32M, and 32Y is supplied with the corresponding color ink from an ink tank (not shown) via a piping route (not shown).

[0032] The inkjet heads 32K, 32C, 32M, and 32Y are arranged at regular intervals along the transport path of the substrate 1. Each of the inkjet heads 32K, 32C, 32M, and 32Y is a line-type recording head capable of forming an image on the substrate 1 transported by the transport device 20 in a single scan. Each of the inkjet heads 32K, 32C, 32M, and 32Y may be configured by connecting multiple head modules in the width direction (X direction) of the substrate 1 perpendicular to (an example of "intersecting") the transport direction (Y direction) of the substrate 1.

[0033] Each of the inkjet heads 32K, 32C, 32M, and 32Y has a nozzle surface (not shown) facing the transport path of the substrate 1. Each nozzle surface of the inkjet heads 32K, 32C, 32M, and 32Y has multiple nozzles arranged in a two-dimensional pattern, which are the ejection ports for color ink.

[0034] Towards the printing surface of the substrate 1 being transported by the transport device 20, at least one of the inkjet heads 32K, 32C, 32M, and 32Y ejects droplets of color ink based on the image data of the color plate (an example of "first image data"). The ejected droplets adhere to the printing surface of the substrate 1, thereby forming a color image (an example of "first image") on the printing surface of the substrate 1.

[0035] Although this example shows a configuration using four color inks, the ink colors and number of colors are not limited to this embodiment. For example, additional inkjet heads may be added to eject light-colored inks such as light magenta and light cyan, special color inks such as green, orange, and violet, clear ink, metallic ink, etc. Furthermore, the arrangement order of the inkjet heads for each color is not limited.

[0036] The substrate 1, on which a color image has been formed by the first discharge device 30A, is guided by the pass roller 22 and transported to the first drying device 30B.

[0037] The first drying device 30B is a device for drying the color ink on the printed surface of the substrate 1, which is transported by the transport device 20. The first drying device 30B is equipped with a plurality of hot air heaters (not shown).

[0038] Each hot air heater is positioned with an air outlet (not shown) facing the printed surface of the substrate 1. Each hot air heater functions as a heating device that heats the substrate 1 by blowing hot air from its air outlet toward the printed surface of the substrate 1, thereby drying the color ink adhering to the printed surface.

[0039] The substrate 1, which has been transported to the outside of the first drying apparatus 30B, has had the color ink attached to its printed surface dried. Drying means, for example, that when the substrate 1 is rolled up, the ink on the printed surface of the substrate 1 does not bleed through to the non-printed surface.

[0040] The substrate 1 on which the color ink has been dried by the first drying device 30B is discharged from the first printing device 30 and conveyed to the second printing device 40 via the pass roller 22.

[0041] The second printing device 40 includes a second ejection device 40A and a second drying device 40B. The substrate 1 conveyed to the second printing device 40 is guided by the pass roller 22 and conveyed to the second ejection device 40A.

[0042] The second ejection device 40A (an example of the “second image forming device”) includes inkjet heads 42WA and 42WB. The inkjet heads 42WA and 42WB each eject white ink (an example of the “second liquid”), which is white (W) aqueous ink. The inkjet heads 42WA and 42WB are each supplied with white ink from an ink tank (not shown) via a piping path (not shown).

[0043] The inkjet heads 42WA and 42WB are arranged at regular intervals along the conveyance path of the substrate 1. The inkjet heads 42WA and 42WB are line-type recording heads capable of forming an image by scanning the substrate 1 conveyed by the conveyance device 20 once each. The inkjet heads 42WA and 42WB may each be configured by connecting a plurality of head modules in the width direction of the substrate 1.

[0044] The inkjet heads 42WA and 42WB are each arranged such that a nozzle surface (not shown) faces the conveyance path of the substrate 1. A plurality of nozzles, which are ejection ports for white ink, are two-dimensionally arranged on each nozzle surface of the inkjet heads 42WA and 42WB.

[0045] Toward the printing surface of the substrate 1 conveyed by the conveyance device 20, droplets of white ink are ejected from at least one of the inkjet heads 42WA and 42WB based on white plate image data (an example of the “second image data”). By the ejected droplets adhering to the printing surface of the substrate 1, a white image (an example of the “second image”) is formed on the printing surface of the substrate 1.

[0046] Here, the color plate image data and the white plate image data are separated from the same printed image data. Therefore, the inkjet heads 4​​2WA and 4​​2WB eject white ink on top of the color image formed by the inkjet heads 32K, 32C, 32M, and 32Y. As a result, a white image is formed on the printing surface of the base material 1 overlying the color image.

[0047] The base material 1 on which the white image is formed by the second ejection device 40A is guided by the pass roller 22 and conveyed to the second drying device 40B.

[0048] The second drying device 40B is a device for drying the white ink on the printing surface of the base material 1 conveyed by the conveying device 20. Since the configuration of the second drying device 40B is the same as that of the first drying device 30B, a detailed description thereof will be omitted. [[ID=\\(7\\)]]

[0049] The base material 1 on which the white ink has been dried by the second drying device 𝑠0B is discharged from the second printing device 40.

[0050] In this way, the inkjet printing system 10 manufactures the final printed matter by printing a color image on the base material 1 in the first printing device 30 and printing a white image on the base material 1 in the second printing device 40.

[0051] The base material information acquisition unit 50 measures the state of the base material 1. The base material information acquisition unit 50 includes a first measuring device 52A, a second measuring device 52B, and a third measuring device 52C.

[0052] The first measuring device 52A is disposed at a first position between the first ejection device 30A and the first drying device 30B in the conveyance path of the base material 1. The second measuring device 52B is disposed at a second position between the second ejection device 40A and the second drying device 40B in the conveyance path of the base material 1. The third measuring device 52C is disposed at a third position on the downstream side of the second drying device 40B in the conveyance path of the base material 1.

[0053] In other words, the conveying device 20 conveys the substrate 1 in the following order: first discharge device 30A, first measuring device 52A, first drying device 30B, second discharge device 40A, second measuring device 52B, second drying device 40B, and third measuring device 52C.

[0054] The first measuring device 52A, the second measuring device 52B, and the third measuring device 52C may each have similar configurations. Details of the configuration of the second measuring device 52B will be described later.

[0055] [Electrical Configuration of Inkjet Printing System] Figure 2 is a block diagram showing the electrical configuration of the inkjet printing system 10. As shown in Figure 2, the inkjet printing system 10 comprises a general control unit 100, a transport control unit 102, an ejection control unit 104, a drying control unit 106, a measurement control unit 108, an input device 110, and an output device 112.

[0056] The central control unit 100 centrally controls each part of the inkjet printing system 10. In this embodiment, each process is executed on any computer. Alternatively, any computer may execute these processes using a processor as hardware, a program as software, or a combination thereof. In that case, the processor is configured to work in cooperation with the program to execute the various processes in this embodiment, and can function as each part (Unit) or each means (Means) in this embodiment. Furthermore, the execution order of the processes by the processor is not limited to the order described and may be changed as appropriate. Any computer may be a general-purpose computer, a computer for a specific application, a workstation, or any other system capable of executing each process.

[0057] A processor may consist of one or more hardware components, and the type of hardware is not limited. For example, a processor may consist of programmable logic devices such as a CPU (Central Processing Unit), MPU (Micro Processing Unit), FPGA (Field Programmable Gate Array), dedicated circuits for performing specific processing such as an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit), or an NPU (Neural Processing Unit). Furthermore, the type of hardware may be a combination of different types of hardware. When multiple hardware components are configured to execute one or more processes of a processor, these components may reside in physically separate devices or in the same device. Furthermore, in any embodiment, the order of the processes performed by the processor is not limited to the order described above and may be changed as appropriate. The hardware components are composed of electrical circuits (circuits) and the like, which are combinations of circuit elements such as semiconductor elements.

[0058] Furthermore, the program may be firmware or software such as microcode. Alternatively, the program may be, for example, a group of program modules, each function of which may be implemented by a processor configured to perform its respective function. The program may be program code or multiple code segments stored on one or more non-temporary computer-readable media (e.g., storage media or other storage). The program may be divided and stored on multiple non-temporary computer-readable media located in physically separate devices. Program code or code segments may represent any combination of procedures, functions, subprograms, routines, subroutines, modules, software packages, classes, or instructions, data structures, or program statements. Program code or code segments may be connected to other code segments or hardware circuits by sending and receiving information, data, arguments, parameters, or memory contents.

[0059] The transport control unit 102 controls the transport device 20 to transport the substrate 1 along the transport path.

[0060] The ejection control unit 104 controls the first ejection device 30A to eject color ink from the inkjet heads 32K, 32C, 32M, and 32Y, respectively, to print a color image on the substrate 1. The ejection control unit 104 also controls the second ejection device 40A to eject white ink from the inkjet heads 42WA and 42WB, respectively, to print a white image on the substrate 1.

[0061] The drying control unit 106 controls the first drying device 30B and the second drying device 40B to heat and dry the color ink and the white ink.

[0062] The measurement control unit 108 controls the substrate information acquisition unit 50 to measure the state of the substrate 1 and acquires the measurement results.

[0063] The input device 110 includes, for example, a mouse (not shown) and a keyboard (not shown). The input device 110 receives input from the mouse and keyboard to the inkjet printing system 10.

[0064] The output device 112 includes, for example, a display (not shown). The output device 112 presents information about the inkjet printing system 10 to the user.

[0065] The input device 110 and output device 112 may include a communication interface (not shown) for sending and receiving information between the inkjet printing system 10 and other devices.

[0066] [Registration] The inkjet printing system 10 prints a color image and a white image on one side of a transparent film substrate used for flexible packaging, making misalignment of the two images easily noticeable. For this reason, the required precision for image positioning is very high, for example, within 0.2 [millimeters].

[0067] In the inkjet printing system 10, the substrate 1 expands and contracts after the color image dries. For example, the substrate 1 stretches in the transport direction and contracts in the width direction. Furthermore, the substrate 1 expands and contracts again after the white image dries. For this reason, the expansion and contraction rates for the color image and the white image are calculated, and the original image size is corrected using these expansion and contraction rates.

[0068] In particular, the inkjet printing system 10 has a long transport path for the substrate 1 in the first drying device 30B in order to dry the ink ejected by the first ejector 30A, and the distance between the first ejector 30A and the second ejector 40A is 10 meters or more. As a result, misalignment between the color image and the white image is likely to occur, and three operations, "tilt alignment," "size alignment," and "position alignment," are performed for "registration adjustment."

[0069] Figure 3 is a diagram illustrating the registration alignment between a color image IC and a white image IW. F3A in Figure 3 shows a state where the tilt, size, and position of the color image IC and the white image IW are different. The image data for the color plate and the image data for the white plate are plate-separated from the same print image data, and it is preferable that the color image IC and the white image IW are printed with the same tilt, the same size, and the same position. The tilt of the color image IC and the white image IW is, for example, the rotation angle of the white image with respect to the normal of the printed surface of the substrate 1, when the color image is used as the reference.

[0070] Figure 3, F3B, shows the state after tilt adjustment has been performed from the state in F3A. Here, the white image IW is rotated around the printed surface of the substrate 1 by a predetermined rotation angle, with the normal to the printed surface as the axis, to match the tilt of the color image IC and the white image IW. As shown in F3B, the tilt between the color image IC and the white image IW has been eliminated.

[0071] Figure 3, F3C, shows the state after size adjustment has been performed from the state of F3B. Here, the vertical size of the color image IC has been made relatively smaller, and the horizontal size has been made relatively larger, so the size difference between the color image IC and the white image IW has been eliminated.

[0072] Figure 3, F3D, shows the state after alignment has been performed from the state of F3C. Here, the position of the white image IW has been moved to the upper side vertically and to the left side horizontally, eliminating the positional difference between the color image IC and the white image IW. In this way, registration alignment between the color image IC and the white image IW is performed.

[0073] [Alignment Function] In both digital and analog printing presses, it is common practice to align the positions of colors by setting a reference point such as the edge of the substrate or an "alignment cross mark." A cross mark is a mark formed by two intersecting lines, and is also called a trim mark.

[0074] Figure 4 is a diagram illustrating the automatic registration adjustment function, which is an automated alignment function in the inkjet printing system 10.

[0075] F4A in Figure 4 shows a color image formed on the substrate 1 by the first ejection device 30A and a color cross mark TC (an example of a "first alignment mark"). The color cross mark TC is formed, for example, by the inkjet head 32K at the leading edge (upstream side) in the Y direction of the color image and at one corner in the X direction.

[0076] F4B in Figure 4 shows the white image and white cross mark TW (an example of a "second alignment mark") formed on the substrate 1 by the second ejection device 40A. The white cross mark TW is formed, for example, by the inkjet head 42WA at the leading edge in the Y direction of the white image and at one corner in the X direction.

[0077] Figure 4, F4C, shows the actual printed output. In the printed output, the color image and the white image are printed on top of each other, and the color cross mark TC and the white cross mark TW are printed on top of each other.

[0078] As mentioned above, the color image data and the white image data are derived from the same print image data. Therefore, ideally, the color image and the white image, as well as the color cross mark TC and the white cross mark TW, are printed in the same position on the substrate 1.

[0079] F4D is an enlarged view of the color cross mark TC and white cross mark TW from F4C. As shown in F4D, the color cross mark TC and white cross mark TW may be printed with a misalignment. In this case, the color image and the white image are printed with a similar misalignment.

[0080] The automatic registration adjustment function captures the color cross mark TC and white cross mark TW of the F4C with the automatic registration camera 54 (see Figure 9) provided in the second measuring device 52B. This function quantifies the amount of deviation of the white cross mark TW relative to the position of the color cross mark TC, and corrects the image formation position in the X and Y directions of the second ejection device 40A based on this deviation.

[0081] [Additional function for accessory images] In the inkjet printing system 10, when generating the color image data and white image data, which are the print data, the "image data area" where the user can freely place images and the "standard accessory image area" such as a cross mark are processed separately.

[0082] Figure 5 is a diagram illustrating print data. Here, a color image data is shown as an example of print data. The print data includes a pattern image area (an example of a "user image area") where the user can freely place patterns (an example of a "user image"), and an accessory image area where standardized accessory images such as a color cross mark TC are placed. As shown in Figure 5, the data in the pattern image area is in vector format, and the data in the accessory image area is in raster format. The inkjet printing system 10 generates raster format print data from the data in the pattern image area and the data in the accessory image area.

[0083] Figure 6 is a diagram illustrating the generation of print data. The central control unit 100 acquires vector-format image data such as PDF (Portable Document Format).

[0084] The control unit 100 converts the image data into raster image data using RIP (Raster Image Processor) processing. For example, the control unit 100 converts the image data into 1-bit TIFF (Tagged Image File Format) image data. The RIP processing may include scaling correction (size adjustment).

[0085] Furthermore, the control unit 100 acquires accessory image data in raster format as 1-bit TIFF (Tagged Image File Format).

[0086] The control unit 100 adds 1-bit TIFF accessory image data to the image data of the pattern that has been converted to 1-bit TIFF by RIP processing, and generates 1-bit TIFF print data.

[0087] In this way, the inkjet printing system 10 limits the RIP processing area by separately adding accessory image data, which is generated in raster format, to the image data. This reduces the processing load and shortens the processing time.

[0088] [Challenges when combining scaling adjustments] With paper substrates and PET (Polyethylene Terephthalate) substrates, where deformation hardly occurs, there is no need to perform size adjustments, so the automatic registration adjustment function and the separate attachment function for accessory images could be used without problems.

[0089] However, when using both functions on a soft substrate like OPP, which has a relatively large scaling amount, a problem arose where the color image and the white image were shifted in the X direction because scaling correction was not applied to the accessory image.

[0090] Figure 7 illustrates an example of the mechanism by which a shift in the X-direction occurs between a color image and a white image.

[0091] Prior to alignment, the inkjet printing system 10 calculates a shrinkage rate for size adjustment (scaling correction). As shown at F7A in Figure 7, the ejection control unit 104 (see Figure 2) forms a color image IC and a color cross mark TC on the substrate 1 using the first ejection device 30A. The pattern image region including the color image IC is positioned such that its center in the X direction coincides with the center of the substrate 1 in the X direction. The pattern image region including the color image IC may also be positioned at a location where its center in the X direction is a second distance away from the center of the substrate 1 in the X direction. The color cross mark TC is positioned at a location where it is a third distance away from the center of the pattern image region in the X direction.

[0092] Next, as shown in F7B of Figure 7, the control unit 100 (see Figure 2) obtains the width (an example of the "width in the second direction"), which is the length of the substrate 1 in the X direction, from the measurement results of the first measuring device 52A. Here, the width of the substrate 1 is assumed to be 1000 millimeters.

[0093] Next, as shown in F7C of Figure 7, the drying control unit 106 (see Figure 2) dries the color ink on the substrate 1 using the first drying device 30B.

[0094] Furthermore, as shown in F7D of Figure 7, the discharge control unit 104 forms the white image IW and the white cross mark TW on the substrate 1 using the second discharge device 40A. Note that this step is not necessary for calculating the shrinkage rate.

[0095] Furthermore, as shown in F7E of Figure 7, the control unit 100 obtains the width of the substrate 1 from the measurement results of the second measuring device 52B. Here, the width of the substrate 1 is assumed to be (1000 × α) [millimeters]. That is, the width of the substrate 1 is deformed by α times due to drying by the first drying device 30B. Here, α is assumed to be less than 1. This α corresponds to the shrinkage rate for expansion and contraction correction.

[0096] The integrated control unit 100 uses the acquired α to perform scaling correction in the X direction on the pattern image area of ​​the white plate image data. That is, the integrated control unit 100 corrects the size of the pattern image area of ​​the white plate image data in the X direction by α times.

[0097] Next, the inkjet printing system 10 performs alignment. As shown at F7A in Figure 7, the ejection control unit 104 uses the first ejection device 30A to form a color image IC and a color cross mark TC on the substrate 1. The color cross mark TC is positioned 490 [millimeters] away in the X direction from the center of the pattern image area including the color image IC in the X direction. The drying control unit 106 then uses the first drying device 30B to dry the color ink on the substrate 1, as shown at F7C in Figure 7. As a result of this drying, the width of the substrate 1 becomes (1000 × α) [millimeters], and the distance between the center of the pattern image area including the color image IC in the X direction and the color cross mark TC becomes (490 × α) [millimeters].

[0098] Next, as shown in F7D of Figure 7, the discharge control unit 104 forms a white image IW and a white cross mark TW on the substrate 1 using the second discharge device 40A. The pattern image region including the white image IW is positioned such that its center in the X direction coincides with the center of the substrate 1 in the X direction. Alternatively, the pattern image region including the white image IW may be positioned such that its center in the X direction is a second distance away from the center of the substrate 1 in the X direction.

[0099] Here, scaling correction is applied to the pattern image area of ​​the white plate image data, so the size of the white image IW is corrected by α times. On the other hand, scaling correction is not applied to the accessory image area, so the white cross mark TW is positioned 490 [millimeters] (an example of "first distance") in the X direction from the center of the pattern image area including the white image IW in the X direction.

[0100] Subsequently, the measurement control unit 108 (see Figure 2) uses the automatic registration camera 54 (see Figure 9) of the second measuring device 52B to photograph the color cross mark TC and the white cross mark TW. The overall control unit 100 quantifies and acquires the amount of misalignment between the color cross mark TC and the white cross mark TW based on the images captured by the automatic registration camera 54. The overall control unit 100 also adjusts the image formation position in the X direction of the second ejection device 40A using the automatic registration adjustment function based on the acquired amount of misalignment.

[0101] As a result, a printed document is output in which the color cross mark TC and the white cross mark TW coincide. However, the distance between the center of the pattern image area containing the color image IC in the X direction and the color cross mark TC is (490 × α) [millimeters], and the distance between the center of the pattern image area containing the white image IW in the X direction and the white cross mark TW is 490 [millimeters]. Therefore, in this printed document, the color image IC and the white image IW are offset by (490 × (1 - α)) [millimeters] in the X direction.

[0102] Such misalignment in the X-direction between the color image IC and the white image IW is not limited to cases where the accessory image is used as the reference position for alignment. Figure 8 illustrates another example of the mechanism by which misalignment in the X-direction between the color image and the white image occurs. Here, we will explain the case where the edge of the substrate 1 is used as the reference position for alignment.

[0103] Similar to the case in Figure 7, the width of the substrate 1 is deformed by α times due to drying by the first drying apparatus 30B. The control unit 100 uses α to perform scaling correction in the X direction for the pattern image area of ​​the white plate image data.

[0104] As shown in F8A of Figure 8, the ejection control unit 104 forms a color image IC on the substrate 1 using the first ejection device 30A. Here, the center in the X direction of the pattern image area including the color image IC is located 500 [millimeters] away in the -X direction from one edge ED of the substrate 1.

[0105] Next, as shown in F8C of Figure 8, the drying control unit 106 dries the color ink on the substrate 1 using the first drying device 30B. As a result of this drying, the width of the substrate 1 becomes (1000 × α) [millimeters], and the distance between the edge ED of the substrate 1 and the center in the X direction of the pattern image area including the color image IC becomes (500 × α) [millimeters].

[0106] Next, as shown in F8D of Figure 8, the ejection control unit 104 forms a white image IW on the substrate 1 using the second ejection device 40A. Here, the size of the white image IW is corrected by α times because scaling correction is applied to the pattern image area of ​​the white plate image data. On the other hand, scaling correction is not applied to the accessory image area, so the white image IW is formed at a position 500 [millimeters] away from the edge ED of the substrate 1 in the X direction.

[0107] As a result, the distance between the edge ED of substrate 1 and the center of the pattern image area including the color image IC in the X direction becomes (500 × α) [millimeters], and the distance between the edge ED of substrate 1 and the center of the pattern image area including the white image IW in the X direction becomes 500 [millimeters]. Therefore, a printed material is output in which the pattern image area including the color image IC and the pattern image area including the white image IW are shifted by (500 × (1 - α)) [millimeters] in the X direction.

[0108] [Configuration of the measuring device] Figure 9 is a diagram illustrating the configuration of the second measuring device 52B. The second measuring device 52B includes an automatic recognition camera 54 and edge sensors 56A and 56B.

[0109] The automatic registration camera 54 is positioned opposite the printed surface of the substrate 1 and is located on the +Z side of the passing position of the color cross mark TC and the white cross mark TW. The automatic registration camera 54 is a digital camera that captures images of the color cross mark TC and the white cross mark TW using an image sensor such as a CMOS (Complementary Metal Oxide Semiconductor) or a CCD (Charge-Coupled Device). The central control unit 100 quantifies and acquires the amount of misalignment between the color cross mark TC and the white cross mark TW based on the images captured by the automatic registration camera 54.

[0110] Edge sensor 56A is positioned opposite edge ED on the GS (Gear Side) side of the substrate 1 (the X-direction side in the example shown in Figure 9). Edge sensor 56B is positioned opposite edge ED on the OS (Operator Side) side of the substrate 1 (the -X-direction side in the example shown in Figure 9). Edge sensors 56A and 56B are positioned at the same location in the transport direction of the substrate 1 (Y-direction in Figure 9).

[0111] Edge sensors 56A and 56B are optical sensors for detecting the edges ED of the substrate 1. Each edge sensor 56A and 56B comprises a light-emitting unit (not shown) that emits a strip of light perpendicular to the printed surface of the substrate 1 onto the edges ED of the substrate 1, and a light-receiving unit (not shown) positioned opposite the light-emitting unit via the substrate 1 and receiving the emitted light. Edge sensors 56A and 56B each detect the position of the edges ED of the substrate 1 in the X direction based on the light-receiving result by the light-receiving unit. The control unit 100 quantifies and obtains the width of the substrate 1 at the second position based on the detection results of the edge sensors 56A and 56B.

[0112] The configuration of the first measuring device 52A may be the same as that of the second measuring device 52B. The first measuring device 52A does not need to be equipped with an automatic registration camera 54. The control unit 100 quantifies and acquires the width of the substrate 1 at the first position based on the detection results of the edge sensors 56A and 56B of the first measuring device 52A. The configuration of the third measuring device 52C may be the same as that of the first measuring device 52A.

[0113] [Manufacturing Method for Printed Materials] Figure 10 is a flowchart showing the manufacturing method for printed materials using an inkjet printing system 10. In the manufacturing method for printed materials, scaling correction and alignment are performed. Here, we will explain the case in which alignment is performed using an automatic registration adjustment function with a color cross mark TC and a white cross mark TW that are placed 490 [millimeters] away from the center of the image area in the X direction, as shown in Figure 7.

[0114] In step S1, the inkjet printing system 10 prints a color image onto the substrate 1. Specifically, the transport control unit 102 transports the substrate 1 using the transport device 20. Subsequently, the ejection control unit 104 forms a color image on the substrate 1 using the first ejection device 30A based on the image data of the color plate. The ejection control unit 104 also forms a color cross mark TC on the substrate 1 along with the color image using the first ejection device 30A. Furthermore, the drying control unit 106 dries the color image and the color cross mark TC using the first drying device 30B.

[0115] In step S2, the inkjet printing system 10 measures the state of the substrate 1 at the first position. Specifically, the measurement control unit 108 detects the positions in the X direction of the edges ED at both ends of the substrate 1 using the edge sensors 56A and 56B of the first measuring device 52A.

[0116] The central control unit 100 calculates the difference in the X-direction positions W1 [millimeters] between the edges ED at both ends of the substrate 1 from the detection results of the edge sensors 56A and 56B. W1 is the width of the substrate 1 at the first position.

[0117] In step S3, the inkjet printing system 10 prints a white image onto the substrate 1. Specifically, the ejection control unit 104 forms a white image on the substrate 1 using the second ejection device 40A based on the image data of the white plate. The ejection control unit 104 also forms a white cross mark TW on the substrate 1 along with the white image using the second ejection device 40A. Furthermore, the drying control unit 106 dries the white image and the white cross mark TW using the second drying device 40B.

[0118] In step S4, the inkjet printing system 10 measures the state of the substrate 1 at the second position. Specifically, the measurement control unit 108 detects the positions in the X direction of the edges ED at both ends of the substrate 1 using the edge sensors 56A and 56B of the second measuring device 52B.

[0119] The central control unit 100 calculates the difference in the X-direction positions W2 [millimeters] between the edges ED at both ends of the substrate 1 from the detection results of the edge sensors 56A and 56B. W2 is the width of the substrate 1 at the second position.

[0120] In step S5, the inkjet printing system 10 calculates a correction value. Here, the control unit 100 calculates the shrinkage rate α for scaling correction as a second correction value using the following equation 1: α = W2 / W1 …(Equation 1)

[0121] The control unit 100 may display the shrinkage rate α on a display (not shown) of the output device 112 (see Figure 2). Alternatively, the user may manually calculate the shrinkage rate α.

[0122] Furthermore, as mentioned above, the amount of X-direction displacement between the color image IC and the white image IW when the positions of the color cross mark TC and the white cross mark TW are aligned is (490 × (1 - α)) [millimeters]. The control unit 100 uses the shrinkage rate α obtained by Equation 1 to calculate a first correction value for correcting the position of the pattern image area of ​​the white plate image data, which is a first correction value for shifting the image formation position in the X direction of the second ejection device 40A by (490 × (1 - α)) [millimeters].

[0123] In step S6, the inkjet printing system 10 corrects the white plate image data with the first correction value calculated in step S5. Here, the control unit 100 corrects the size of the pattern image area of ​​the white plate image data in the X direction by the shrinkage rate α, and corrects the position of the pattern image area of ​​the white plate image data in the X direction by the first correction value. The correction of the white plate image data may also be performed manually by the user.

[0124] In step S7, the inkjet printing system 10 prints a color image and a white image onto the substrate 1 based on the image data corrected in step S6. That is, the transport device 20 transports the substrate 1. The ejection control unit 104 forms a color image on the substrate 1 using the first ejection device 30A based on the image data of the color plate. The drying control unit 106 dries the color image using the first drying device 30B. The ejection control unit 104 forms a corrected white image on the substrate 1 using the second ejection device 40A based on the corrected image data of the white plate.

[0125] The measurement control unit 108 uses the automatic registration camera 54 of the second measuring device 52B to photograph the color cross mark TC and the white cross mark TW. The overall control unit 100 quantifies and acquires the amount of misalignment between the color cross mark TC and the white cross mark TW based on the images captured by the automatic registration camera 54. The overall control unit 100 also adjusts the image formation position in the X direction of the second ejection device 40A using the automatic registration adjustment function based on this amount of misalignment.

[0126] As a result, it is possible to manufacture printed materials in which the positions of color images and white images are aligned.

[0127] In this way, the correction amount (offset amount) for the print position misalignment in the X direction is calculated from the deformation ratio of the substrate 1 in the X direction. This allows the user to obtain the offset amount without actually measuring the output printout, and the position of the color image and the white image can be matched by the obtained offset amount during printing. Therefore, it is possible to reduce measurement work, improve measurement accuracy, shorten job changeover time, and automate the offset work.

[0128] As shown in Figure 8, when aligning the color image and the white image with respect to the edge ED of the substrate 1, the control unit 100 can correct the image data of the white plate with a first correction value for correcting the position of the image data of the white plate, which is a first correction value for shifting the image formation position of the second ejection device 40A in the X direction by (500 × (1 - α)) [millimeters].

[0129] In this case, the control unit 100 corrected the position in the X direction of the pattern image area of ​​the white plate image data with the first correction value, but the position in the X direction of the accessory image area of ​​the white plate image data may also be corrected with the first correction value.

[0130] [Other] Up to this point, we have described an inkjet printing system 10 for manufacturing reverse-printed materials, but this disclosure can also be applied to an inkjet printing system for manufacturing front-printed materials. In this case, the first ejector 30A may eject droplets of white ink to form a white image, and the second ejector 40A may eject droplets of color ink to form a color image. Alternatively, the first ejector 30A may eject droplets of CMYK (cyan, magenta, yellow, black) ink to form a CMYK image, and the second ejector 40A may eject droplets of OGV (orange, green, violet) ink to form an OGV image. The second ejector 40A may also eject droplets of ink such as clear ink or metallic ink.

[0131] In the case of surface printing, the substrate 1 is not limited to a transparent substrate, but can also be an opaque substrate such as paper.

[0132] The technical scope of the present invention is not limited to the scope described in the embodiments above. The configurations and other elements in each embodiment can be appropriately combined with those in each embodiment without departing from the spirit of the present invention.

[0133] 1...Substrate 10...Inkjet printing system 20...Transport device 22...Pass roller 30...First printing device 30A...First ejection device 30B...First drying device 32C...Inkjet head 32K...Inkjet head 32M...Inkjet head 32Y...Inkjet head 40...Second printing device 40A...Second ejection device 40B...Second drying device 42WA...Inkjet head 42WB...Inkjet head 50...Substrate information acquisition unit 52A...First measuring device 52B...Second measuring device 52C...Third measuring device 54...Automatic registration camera 56A...Edge sensor 56B...Edge sensor 100...General control unit 102...Transportation control unit 104...Ejection control unit 106...Drying control unit 108...Measurement control unit 110...Input device 112...Output device ED...Edge IC...Color image IW...White image S1-S7...Steps in the manufacturing method of printed materials TC...Color cross mark TW...White cross mark

Claims

1. A printing system for printing an image on a substrate, comprising: a transport device for transporting the substrate in a first direction; a first image forming device for forming a first image based on first image data; a first measuring device for measuring the width of the substrate in a second direction intersecting the first direction; a second image forming device for forming a second image based on second image data; a second measuring device for measuring the width of the substrate in the second direction; and a processor, wherein the transport device transports the substrate in the order of the first image forming device, the first measuring device, the second image forming device, and the second measuring device; the processor aligns the first image data and the second image data based on a reference position of the substrate; and calculates a first correction value for correcting the position of the second image data in the second direction based on the measurement result of the first measuring device and the measurement result of the second measuring device.

2. The printing system according to claim 1, wherein a second correction value is calculated to correct the scaling of the second image data in the second direction based on the measurement result of the first measuring device and the measurement result of the second measuring device.

3. The printing system according to claim 2, wherein the first image data includes a first alignment mark, the second image data includes a user image area for freely arranging a user image and an accessory image area on which a second alignment mark is placed, the processor aligns the first image data and the second image data using the positions of the first alignment mark and the second alignment mark formed on the substrate as reference positions, corrects the scaling in the second direction of the user image area of ​​the second image data using the second correction value, and calculates the first correction value based on the position of the second alignment mark formed on the substrate and the second correction value.

4. The printing system according to claim 3, wherein the second alignment mark formed on the substrate is positioned at a first distance in the second direction from the center position of the substrate in the second direction.

5. The printing system according to claim 3, wherein the user image region formed on the substrate is positioned such that the central position in the second direction is located at a second distance in the second direction from the central position of the substrate in the second direction.

6. The printing system according to claim 3, wherein the user image region formed on the substrate has its central position in the second direction positioned at the central position of the substrate in the second direction.

7. The printing system according to claim 1, wherein the processor aligns the first image data with respect to the distance from the edge of the substrate in the second direction, using the edge of the substrate in the second direction as a reference position.

8. The printing system according to claim 1, wherein the processor causes the first correction value to be displayed on a display.

9. The printing system according to claim 1, wherein the processor corrects the position of the second image data in the second direction with the first correction value.

10. The printing system according to claim 9, wherein the second image forming apparatus forms a corrected second image based on the corrected second image data.

11. The printing system according to any one of claims 1 to 10, comprising a first drying device for drying the first image formed on the substrate, wherein the transport device transports the substrate in the order of the first image forming device, the first measuring device, the first drying device, the second image forming device, and the second measuring device.

12. A method for manufacturing a printed material, comprising: transporting a substrate in a first direction in the order of a first image forming apparatus, a first measuring apparatus, a second image forming apparatus, and a second measuring apparatus; forming a first image on the substrate based on first image data in the first image forming apparatus; measuring the width of the substrate in a second direction intersecting the first direction in the first measuring apparatus; forming a second image on the substrate based on second image data in the second image forming apparatus; measuring the width of the substrate in the second direction in the second measuring apparatus; aligning the first image data and the second image data based on a reference position of the substrate; calculating a first correction value to correct the position of the second image data in the second direction based on the measurement result of the first measuring apparatus and the measurement result of the second measuring apparatus; correcting the position of the second image data in the second direction with the first correction value; and forming a corrected second image on the substrate based on the corrected second image data in the second image forming apparatus.

Images