Printing system and method for manufacturing printed matter

Abstract

Provided is a printing system that adjusts the size of an image to be printed to target dimensions. The printing system comprises: a first image formation device that forms a first image on a base material on the basis of first image data; a first measurement device that measures the state of the base material by detecting a mark formed on the base material by the first image formation device; and a conveyance device that sequentially conveys the base material to the first image formation device and then to the first measurement device. The printing system: acquires the actual dimensions that are of the base material having the first image formed thereon and that are measured by applying, to the base material, a second tension different from a first tension being applied thereto in the conveyance device; and calculates, on the basis of the measurement result of the first measurement device and the actual dimensions, a first correction value for correcting the first image data.

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 relates to a technique for correcting the size of an image.

[0002] When printing on a stretchable substrate, a technique for correcting print data according to the stretching and shrinking is known. For example, Patent Document 1 describes a technique for calculating the stretching rate A of a sheet from the main scanning widths W1 and W2 of the first side before and after printing on the first side in an inkjet printing apparatus for single sheets, and correcting the printing position of the second side. Further, Patent Document 1 describes a technique for calculating a correction coefficient k by detecting the sub-scanning width L2 of the second side and correcting the stretching rate A.

[0003] Japanese Unexamined Patent Application Publication No. 2019-214190

[0004] As described in Patent Document 1, when the sheet is stretched by printing on the first side, the image area is also stretched at the same ratio.

[0005] For example, consider the case of applying the technique described in Patent Document 1 to package printing in which the target dimensions of a box that a user wants to make are determined and output according to those dimensions. In this case, the size of the image after printing on the first side will be different from the target dimensions (correct dimensions) in the image data. And for an image with a size different from this target dimension, in order to perform alignment of the second side, "a printed matter in which the printing positions of the first side and the second side are correct but do not match the target dimensions" will be output. Thus, there is a problem that does not occur in a printing apparatus that prints designs such as simple posters and calendars on both sides.

[0006] 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 match the size of a printed image to target dimensions.

[0007] 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 first image forming apparatus for forming a first image on a substrate based on first image data; a first measuring apparatus for measuring the state of the substrate; a transport apparatus for transporting the substrate in the order of the first image forming apparatus and the first measuring apparatus; and a processor, wherein the first measuring apparatus detects marks formed on the substrate by the first image forming apparatus to measure the state of the substrate; the processor obtains the actual dimensions of the substrate on which the first image is formed, measured by applying a second tension to the substrate that is different from a first tension applied to the substrate by the transport apparatus; and calculates a first correction value for correcting the first image data based on the measurement result of the first measuring apparatus and the actual dimensions.

[0008] A printing system according to a second aspect of the present disclosure comprises, in a printing system according to a first aspect, a second image forming apparatus that forms a second image on a substrate based on second image data, and a second measuring apparatus that measures the state of the substrate. Preferably, the transport apparatus transports the substrate in the order of the first image forming apparatus, the first measuring apparatus, the second image forming apparatus, and the second measuring apparatus, the second measuring apparatus detects marks and measures the state of the substrate, and the processor calculates a second correction value for correcting the second image data based on the measurement result of the second measuring apparatus and the actual size.

[0009] In the printing system according to the third aspect of this disclosure, it is preferable that the second tension is smaller than the first tension in the printing system according to the first or second aspect.

[0010] In the printing system according to the fourth aspect of this disclosure, it is preferable that the second tension is zero, as in the printing system according to the third aspect.

[0011] In the printing system according to the fifth aspect of this disclosure, in the printing system according to any of the first to fourth aspects, the second tension is preferably the tension applied to the substrate in the next process after printing.

[0012] In the printing system according to the sixth aspect of this disclosure, in the printing system according to any of the first to fifth aspects, the first measuring device preferably measures the spacing of the substrates in the transport direction and the width of the substrates in the mark transport device, and the actual dimensions are obtained from the spacing of the substrates in the transport direction and the width of the substrates in the mark transport device.

[0013] In the seventh aspect of this disclosure, the printing system is preferably, in the printing system according to any of the first to sixth aspects, the actual size is the size of the offline printed material after printing.

[0014] In the eighth aspect of this disclosure, the printing system is preferably, in the printing system of the seventh aspect, the substrate is a long web substrate, and the offline printed material after printing is preferably a sheet-like printed material obtained by cutting the web substrate.

[0015] A printing system according to the ninth aspect of this disclosure preferably includes an external measuring device for measuring the dimensions of a sheet-fed printed material, as in a printing system according to the eighth aspect.

[0016] The printing system according to the tenth aspect of this disclosure preferably includes a third measuring device for measuring actual dimensions in a printing system according to any of the second to sixth aspects, and the transport device transports the substrate in the order of the second measuring device, the third measuring device, and further preferably includes a tension changing mechanism for changing the tension applied to the substrate at the position of the third measuring device to a second tension.

[0017] In the printing system according to the 11th aspect of this disclosure, it is preferable that the third measuring device measures the actual dimensions with the transport device stopped.

[0018] A printing system according to a twelfth aspect of this disclosure preferably includes a transport condition measuring device for measuring the transport conditions of a substrate at the position of a third measuring device, in a printing system according to a tenth or eleventh aspect.

[0019] In the printing system according to the 13th aspect of this disclosure, in the printing system according to the 12th aspect, it is preferable that the transport condition measuring device measures at least one of the tension applied to the substrate and the temperature of the substrate.

[0020] In the printing system according to the 14th aspect of this disclosure, in the printing system according to any of the 13th aspects, it is preferable that the processor displays a first correction value on a display.

[0021] In the printing system according to the 15th aspect of this disclosure, in the printing system according to any of the 1st to 14th aspects, it is preferable that the processor corrects the first image data with a first correction value.

[0022] In the printing system according to the sixteenth aspect of this disclosure, in the printing system according to the fifteenth aspect, the first image forming apparatus preferably forms a corrected first image based on corrected first image data.

[0023] To achieve the above objective, a method for manufacturing printed matter according to a 17th aspect of the present disclosure is a method for manufacturing printed matter, wherein a substrate is transported in a transport device in the order of a first image forming device and a first measuring device, a first image is formed on the substrate in the first image forming device based on first image data, the marks formed on the substrate by the first image forming device are detected by the first measuring device to measure the state of the substrate, the actual dimensions of the substrate on which the first image is formed are obtained by applying a second tension to the substrate in the transport device that is different from the first tension applied to the substrate, a first correction value is calculated based on the measurement result of the first measuring device and the actual dimensions, the first image data is corrected with the first correction value, the substrate is transported in a transport device to the first image forming device, and a corrected first image is formed on the substrate in the first image forming device based on the corrected first image data.

[0024] In the 17th embodiment of the method for manufacturing printed materials, the configuration may include specific embodiments similar to those of the printing system described above.

[0025] According to the present invention, the size of the image to be printed can be adjusted to the target dimensions.

[0026] Figure 1 is a graph showing the transition in the length of the substrate after cutting. Figure 2 is a diagram showing an example of an inkjet printing system. Figure 3 is a block diagram showing the electrical configuration of the inkjet printing system. Figure 4 is a diagram illustrating the configuration of the first measuring device. Figure 5 is a diagram illustrating the configuration of the external measuring device. Figure 6 is a flowchart showing the manufacturing method of a printed material. Figure 7 is a diagram showing an example of an inkjet printing system. Figure 8 is a flowchart showing the manufacturing method of a printed material. Figure 9 is a diagram showing an example of an inkjet printing system. Figure 10 is a flowchart showing the manufacturing method of a printed material.

[0027] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0028] <Properties of Flexible Packaging Substrates> In the technology described in Patent Document 1, when a soft and stretchable substrate such as OPP (Oriented Poly Propylene) is used, the substrate expands and contracts slightly due to the slight tension applied to it during transport. For this reason, the "in-line measurement under transport tension" is measured to be several percent longer in the transport direction (length direction) and narrower in the width direction compared to the "dimensions after substrate cutting (=actual dimensions)".

[0029] In other words, when image data is corrected based on "inline measurements under transport tension," the relative sizes of the first and second images match, but the overall size is shorter in the transport direction and wider in the width direction compared to the target dimensions, resulting in a printed image.

[0030] Figure 1 is a graph showing the change in the length of the substrate after cutting (length in the transport direction before cutting). The horizontal axis of Figure 1 represents the elapsed time [minutes] from cutting the substrate, and the vertical axis represents the length of the substrate [millimeters]. The length was measured manually using a steel ruler. Figure 1 shows the cases where the substrate is MDO-PE (machine direction orientation - polyethylene) and OPP.

[0031] MDO-PE has a thickness of 25 micrometers. MDO-PE shows almost no change in length after cutting the substrate. OPP has a thickness of 20 micrometers. For example, if a 1000 mm long printed object is cut from OPP, it will shrink by 1.9 mm in length in about one hour. Thus, even within "actual dimensions," errors can occur depending on the measurement timing.

[0032] Due to the unique properties of these flexible packaging materials, it is essential to measure the actual dimensions at the desired conditions and timing in order to align printed materials to target dimensions. The desired conditions include, for example, the presence or absence of tension, and the timing includes, for example, the time elapsed after printing or cutting. These vary depending on the user and cannot be defined by the system.

[0033] <First Embodiment> [Overall Configuration of 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, an inkjet printing system that prints on a long web substrate using an inkjet method will be described. Figure 2 is a diagram showing an example of an inkjet printing system according to the first embodiment. The inkjet printing system 10 shown in Figure 2 transports a long, non-permeable substrate 1 and prints a color image and a white image on the printing surface of the substrate 1.

[0034] 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, and NY (Nylon). The inkjet printing system 10 produces reverse-printed material on the substrate 1, where the printed object is visible from the non-printed side, which is the side opposite the printed surface.

[0035] Furthermore, "non-permeable" means that it is impermeable to water-based inks. 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.

[0036] 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.

[0037] The conveying device 20 applies conveying tension to the substrate 1 and conveys it in a roll-to-roll manner along a conveying path from an unwinding roll (not shown) to a winding roll. The conveying device 20 includes a plurality of pass rollers 22 and a winding roll 24. The pass rollers 22 convey the substrate 1 in the conveying direction by rotating in contact with the substrate 1. The winding roll 24 is rotatably supported by a frame member (not shown). The winding roll 24 is rotationally driven by a motor (not shown) and winds up the substrate 1 on which the image has been formed.

[0038] In the example shown in Figure 2, 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).

[0039] 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.

[0040] 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.

[0041] The first ejection device 30A (an example of the "first image forming device") includes inkjet heads 32K, 32C, 32M, and 32Y. The inkjet heads 32K, 32C, 32M, and 32Y eject color inks (an example of the "first liquid"), i.e., black (K), cyan (C), magenta (M), and yellow (Y), respectively. Each color ink is an aqueous ink in which a colorant such as a dye or a pigment is dissolved or dispersed in water and a solvent soluble in water. Each of the inkjet heads 32K, 32C, 32M, and 32Y is supplied with a color ink of a corresponding color from an ink tank (not shown) via a piping path (not shown).

[0042] The inkjet heads 32K, 32C, 32M, and 32Y are arranged at regular intervals along the conveyance path of the substrate 1. The inkjet heads 32K, 32C, 32M, and 32Y 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 32K, 32C, 32M, and 32Y may each be configured by connecting a plurality of head modules in the width direction orthogonal to the conveyance direction of the substrate 1.

[0043] The inkjet heads 32K, 32C, 32M, and 32Y 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 color ink, are two-dimensionally arranged on each nozzle surface of the inkjet heads 32K, 32C, 32M, and 32Y.

[0044] Toward the printing surface of the substrate 1 conveyed by the conveyance device 20, droplets of color ink are ejected from at least one of the inkjet heads 32K, 32C, 32M, and 32Y based on color plate image data (an example of the "first image data"). By the ejected droplets adhering to the printing surface of the substrate 1, a color image (an example of the "first image") is formed on the printing surface of the substrate 1.

[0045] Note that although a configuration using four-color ink has been shown here, the ink colors and the number of colors are not limited to this embodiment. For example, an inkjet head that ejects light color inks such as light magenta and light cyan, special color inks such as green, orange, and violet, clear ink, metallic ink, etc. may be added. Also, the arrangement order of the inkjet heads for each color is not limited.

[0046] The substrate <1> on which a color image has been formed by the first ejection device <30A> is guided by the pass roller <22> and conveyed to the first drying device <30B>.

[0047] The first drying device <30B> is a device that dries the color ink on the printing surface of the substrate <1> conveyed by the conveying device <20>. The first drying device <30B> includes a plurality of hot air heaters (not shown).

[0048] The hot air heaters are each arranged with a blower outlet (not shown) facing the printing surface of the substrate <1>. Each hot air heater functions as a heating device that blows hot air from the blower outlet toward the printing surface of the substrate <1> to heat the substrate <1> and dry the color ink adhering to the printing surface.

[0049] The substrate <1> conveyed outside the first drying device <30B> has the color ink adhering to the printing surface dried. Drying means, for example, a state where the ink on the printing surface of the substrate <1> does not bleed through to the non-printing surface when the substrate <1> is wound up.

[0050] 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>.

[0051] 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>.

[0052] The second ejection device 40A (an example of the "second image forming apparatus") includes inkjet heads 42WA and 42WB. Both inkjet heads 42WA and 42WB eject white ink (an example of the "second liquid"), which is a white (W) water-based ink. White ink is supplied to the inkjet heads 42WA and 42WB from an ink tank (not shown) via a piping route (not shown).

[0053] The inkjet heads 42WA and 42WB are arranged at regular intervals along the transport path of the substrate 1. The inkjet heads 42WA and 42WB are line-type recording heads capable of forming an image on the substrate 1 transported by the transport device 20 in a single scan. The inkjet heads 42WA and 42WB may each be configured by connecting multiple head modules in the width direction of the substrate 1.

[0054] The inkjet heads 42WA and 42WB are each positioned with nozzle surfaces (not shown) facing the transport path of the substrate 1. Each nozzle surface of the inkjet heads 42WA and 42WB has multiple nozzles arranged in a two-dimensional pattern, which are the ejection ports for white ink.

[0055] Towards the printing surface of the substrate 1 being transported by the transport 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 "second image data"). The ejected droplets adhere to the printing surface of the substrate 1, thereby forming a white image (an example of "second image") on the printing surface of the substrate 1.

[0056] Here, the color image data and the white image data are derived from the same print image data. Therefore, the inkjet heads 42WA and 42WB eject white ink over the color image formed by the inkjet heads 32K, 32C, 32M, and 32Y. As a result, a white image is formed on the printed surface of the substrate 1, superimposed on the color image.

[0057] The substrate 1, on which a white image has been formed by the second discharge device 40A, is guided by the pass roller 22 and transported to the second drying device 40B.

[0058] The second drying apparatus 40B is a device for drying the white ink on the printed surface of the substrate 1, which is transported by the transport device 20. The configuration of the second drying apparatus 40B is the same as that of the first drying apparatus 30B, so a detailed explanation is omitted.

[0059] The substrate 1, on which the white ink has been dried by the second drying device 40B, is discharged from the second printing device 40.

[0060] Thus, the inkjet printing system 10 produces the final printed material by printing a color image on the substrate 1 in the first printing device 30 and a white image on the substrate 1 in the second printing device 40. The tension applied to the substrate 1 by the transport device 20 may differ between the first printing device 30 and the second printing device 40.

[0061] The substrate information acquisition unit 50 measures the state of the substrate 1. The substrate information acquisition unit 50 includes a first measuring device 52A, a second measuring device 52B, and an external measuring device 54.

[0062] The first measuring device 52A is positioned at a first location between the first discharge device 30A and the first drying device 30B in the transport path of the substrate 1. The second measuring device 52B is positioned at a second location between the second discharge device 40A and the second drying device 40B in the transport path of the substrate 1.

[0063] 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, and second drying device 40B.

[0064] The first measuring device 52A and the second measuring device 52B may each have similar configurations. Details of the configurations of the first measuring device 52A and the second measuring device 52B will be described later.

[0065] The external measuring device 54 measures the dimensions of the output offline printed material. The output offline printed material is, for example, a sheet-fed printed material obtained by cutting the substrate 1 after printing. Details of the configuration of the external measuring device 54 will be described later.

[0066] [Electrical Configuration of the Printing System] Figure 3 is a block diagram showing the electrical configuration of the inkjet printing system 10. As shown in Figure 3, 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. Each control unit and each device of the inkjet printing system 10 is connected to communicate control signals and data via a wired or wireless network.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] The transport control unit 102 controls the transport device 20 to transport the substrate 1 along the transport path. The transport control unit 102 also controls a motor (not shown) to wind the substrate 1, on which the image has been formed, onto the winding roll 24.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] [Configuration of the First Measuring Device] Figure 4 is a diagram illustrating the configuration of the first measuring device 52A. The first measuring device 52A includes a mark sensor 60 and edge sensors 62A and 62B. Also, as shown in Figure 4, the substrate 1 contains a plurality of cue marks MC.

[0078] The cue mark MC is formed on the substrate 1 by, for example, the inkjet head 32K of the first ejection device 30A. That is, the cue mark MC is a type of color image that is not included in the desired printed image IP (color image and white image).

[0079] The cue mark MC is a filled rectangular shape of a fixed size, with sides parallel to the transport direction of the substrate 1 (the Y direction in the example shown in Figure 4) and the width direction perpendicular to the transport direction (the X direction in the example shown in Figure 4). The cue mark MC is positioned at a certain distance in the -X direction from the edge ED on the GS (Gear Side) side (the +X direction side in the example shown in Figure 4) of the substrate 1.

[0080] The cue mark MC is positioned at the desired printing start position of the printable image IP. That is, the cue mark MC is positioned at intervals corresponding to the size of the printable image IP in the transport direction. The size of the printable image IP in the transport direction corresponds to the length of the printed material after printing. In the inkjet printing system 10, the size of the printable printable image IP in the transport direction is 100 to 1400 [millimeters]. That is, the cue mark MC is positioned at intervals of 100 to 1400 [millimeters] in the transport direction of the substrate 1, according to the size of the printable image IP in the transport direction. The size of the cue mark MC and its position within the substrate 1 are not limited to this example, and various configurations are possible.

[0081] The mark sensor 60 is positioned opposite the printed surface of the substrate 1 and on the +Z side of the passage position of the cue mark MC. The mark sensor 60 is an optical sensor for detecting the cue mark MC. The mark sensor 60 is composed of an integrated light-emitting unit (not shown) that emits light onto the substrate 1 and a light-receiving unit (not shown) that receives the reflected light of the emitted light. The mark sensor 60 detects the cue mark MC based on the light-receiving result from the light-receiving unit. The control unit 100 (see Figure 3) quantifies and obtains the spacing between the cue marks MC on the substrate 1 at the first position based on the detection result of the mark sensor 60.

[0082] Edge sensor 62A is positioned opposite edge ED on the GS side of the substrate 1. Edge sensor 62B is positioned opposite edge ED on the OS (Operator Side) side of the substrate 1 (the -X direction in the example shown in Figure 4). Edge sensors 62A and 62B are positioned at the same location in the transport direction of the substrate 1 (Y direction in Figure 4).

[0083] Edge sensors 62A and 62B are optical sensors for detecting the edges ED of the substrate 1. Each edge sensor 62A and 62B comprises a light-emitting unit (not shown) that projects a band 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 projected light. Edge sensors 62A and 62B 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 first position based on the detection results of the edge sensors 62A and 62B.

[0084] The configuration of the second measuring device 52B is the same as that of the first measuring device 52A. The central control unit 100 quantifies and acquires the spacing between the cue marks MC on the substrate 1 and the width of the substrate 1 at the second position.

[0085] [Configuration of the External Measuring Device] Figure 5 is a diagram illustrating the configuration of the external measuring device 54. The external measuring device 54 is a device for measuring the actual dimensions, which are the width and length of a printed material, by applying a tension (an example of a "second tension") to the substrate 1 that is different from the transport tension (an example of a "first tension") applied to the substrate 1 by the transport device 20. For example, the external measuring device 54 measures the actual dimensions of a printed material when no transport tension is applied.

[0086] A state in which no transport tension is applied means, for example, a state where the tension is zero. Zero tension includes the case where the tension is substantially zero. Substantially zero tension may be the tension at which no expansion or contraction occurs in the substrate 1, or the tension at which the expansion or contraction of the substrate 1 is so small that it cannot be perceived by a human.

[0087] The external measuring device 54 includes a mounting table 70 and a third measuring device 56.

[0088] The mounting platform 70 is a rectangular, flat plate-like member and has a mounting surface that is parallel to the X and Y directions. The printed material to be measured is placed on the mounting surface of the mounting platform 70. The mounting platform 70 may be equipped with a stopper member for defining and placing the leading edge position of the printed material.

[0089] In the example shown in Figure 5, a cut sample 2 is placed on the mounting table 70 as a printed material. The cut sample 2 is cut out from a roll-shaped substrate 1 that has been printed and wound onto a winding roll 24, including one page's worth of image (for example, the printed image IP shown in Figure 4). The cut sample 2 may have been cut out of the substrate 1 some time ago. If the width direction and transport direction of the substrate 1 before cutting out the cut sample 2 are considered to be the width direction and length direction of the cut sample 2, then in the example shown in Figure 5, the cut sample 2 is placed with its width direction parallel to the X direction and its length direction parallel to the Y direction.

[0090] The third measuring device 56 includes edge sensors 72A and 72B and a contrast sensor 74.

[0091] Edge sensor 72A is positioned opposite edge ED on one side of the width direction of the cut sample 2 (the -X direction side in Figure 5). Edge sensor 72B is positioned opposite edge ED on the other side of the width direction of the cut sample 2 (the +X direction side in Figure 5). Edge sensors 72A and 72B are positioned at the same location in the Y direction.

[0092] Edge sensors 72A and 72B are optical sensors for detecting the edge ED of the cut sample 2. Edge sensors 72A and 72B each consist of a light-emitting unit (not shown) that emits light onto the cut sample 2 and a light-receiving unit (not shown) that receives the reflected light from the emitted light. Edge sensors 72A and 72B each detect the edge ED of the cut sample 2 based on the light-receiving result from the light-receiving unit.

[0093] The external measuring device 54 detects the X-direction positions of the edges ED at both ends of the cut sample 2 using edge sensors 72A and 72B. The central control unit 100 quantifies and obtains the width of the cut sample 2 based on the detection results of the edge sensors 72A and 72B.

[0094] The mounting base 70 may be made of a light-transmitting material, and the edge sensors 72A and 72B may have the same configuration as the edge sensors 62A and 62B (see Figure 4). That is, the edge sensors 72A and 72B may each include a light-emitting unit (not shown) that emits a band of light perpendicular to the printed surface of the cut sample 2 onto the edge ED of the cut sample 2, and a light-receiving unit (not shown) that is positioned opposite the light-emitting unit via the cut sample 2 and the light-transmitting mounting base 70 to receive the emitted light.

[0095] The contrast sensor 74 is positioned opposite the printed surface of the cut sample 2 and on the -X side of the mounting base 70. The contrast sensor 74 is supported by a guide member (not shown) and is movable in the ±Y direction by a motor (not shown). This allows the contrast sensor 74 to be positioned opposite the cue mark MC.

[0096] The configuration of the contrast sensor 74 may be the same as that of the mark sensor 60, or the edge sensors 72A and 72B. The contrast sensor 74 detects the cue mark MC based on the light reception result from the light receiving unit.

[0097] The external measuring device 54 controls a motor (not shown) to move the contrast sensor 74 and detect the Y-direction positions of the two cue marks MC of the cut sample 2. The central control unit 100 quantifies and obtains the length of the cut sample 2, which is represented by the interval between the cue marks MC, based on the detection result of the contrast sensor 74.

[0098] The configuration of the external measuring device 54 is not limited to the example above; any configuration capable of measuring the actual size of the printed material is acceptable. For example, a configuration that uses a camera to image the entire printed material and then measures it is also possible.

[0099] [Method for Manufacturing Printed Materials] Figure 6 is a flowchart showing a method for manufacturing printed materials using an inkjet printing system 10.

[0100] In step S1, the inkjet printing system 10 prints a color image onto the substrate 1. Specifically, the transport control unit 102 uses the transport device 20 to apply transport tension to the substrate 1 and transports it. Subsequently, the ejection control unit 104 uses the first ejection device 30A to form a color image on the substrate 1 based on the image data of the color plate. The ejection control unit 104 also uses the first ejection device 30A to form cue marks MC on the substrate 1 along with the color image. Furthermore, the drying control unit 106 dries the color image and cue marks MC using the first drying device 30B.

[0101] 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 measures the time interval T1 [seconds] at which the cue mark MC is detected by the mark sensor 60 of the first measuring device 52A. The measurement control unit 108 also detects the positions in the X direction of the edges ED at both ends of the substrate 1, respectively, using the edge sensors 62A and 62B of the first measuring device 52A.

[0102] 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 62A and 62B. W1 corresponds to the width of the printed material.

[0103] Furthermore, the control unit 100 acquires the transport speed V1 [meters / minute] of the substrate 1 at the first position. The transport speed V1 may be measured by a speedometer (not shown), but here the set value set in the inkjet printing system 10 is used. In addition, the control unit 100 calculates the interval L1 [millimeters] of the cue marks MC at the first position from the time interval T1 and the transport speed V1 using the following formula 1. L1 corresponds to the length of the printed material.

[0104] L1=T1×V1 / 60×10 3 ...(Formula 1)

[0105] In step S3, the inkjet printing system 10 prints a white image onto the substrate 1. Specifically, the ejection control unit 104 causes the second ejection device 40A to form a white image on the substrate 1 based on the image data of the white plate. Furthermore, the drying control unit 106 dries the white image using the second drying device 40B.

[0106] 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 measures the time interval T2 [seconds] at which the cue mark MC is detected by the mark sensor 60 of the second measuring device 52B. The measurement control unit 108 also detects the positions in the X direction of the edges ED at both ends of the substrate 1, respectively, using the edge sensors 62A and 62B of the second measuring device 52B.

[0107] 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 62A and 62B. W2 corresponds to the width of the printed material.

[0108] Furthermore, the control unit 100 acquires the transport speed V2 [meters / minute] of the substrate 1 at the second position, and calculates the interval L2 [millimeters] of the cue marks MC at the second position from the time interval T2 and the transport speed V2 using the following equation 2. L2 corresponds to the length of the printed material.

[0109] L2=T2×V2 / 60×10 3 ...(Formula 2)

[0110] In step S5, the user stops the transport of the substrate 1, cuts out a cut sample 2 from the substrate 1 after printing is complete, and allows a desired amount of time to pass.

[0111] In step S6, the inkjet printing system 10 automatically measures the actual size of the printed material. Specifically, the measurement control unit 108 detects the X-direction positions of the edges ED at both ends of the cut sample 2 using the edge sensors 72A and 72B of the external measuring device 54. The measurement control unit 108 also detects the Y-direction positions of the two cue marks MC on the cut sample 2 using the contrast sensor 74 of the external measuring device 54.

[0112] The control unit 100 calculates the difference in the X-direction position of the edges ED at both ends of the cut sample 2, W3 [millimeters], from the detection results of the edge sensors 72A and 72B. W3 corresponds to the actual width of the printed material.

[0113] Furthermore, the control unit 100 calculates the interval L3 [millimeters] between the cue marks MC of the cut sample 2 from the detection results of the contrast sensor 74. L3 corresponds to the length of the printed material.

[0114] The measurement results from the external measuring device 54 may also be manually entered by the user into the central control unit 100 via the input device 110. Furthermore, the actual dimensions may be measured manually by the user (using a steel ruler).

[0115] In step S7, the inkjet printing system 10 calculates a first correction value for correcting the image data of the color plate based on the measurement result of the first measuring device 52A and the actual size, which is the measurement result of the external measuring device 54. That is, the control unit 100 calculates the scaling ratio SRW_4C in the width direction of the color image and the scaling ratio SRL_4C in the length direction of the color image based on the measurement results of steps S2 and S6 using the following equations 3 and 4.

[0116] SRW_4C=W1 / W3...(Formula 3) SRL_4C=L1 / L3...(Formula 4)

[0117] SRW_4C is the correction value in the width direction of the color image data (an example of the "first correction value"), and SRL_4C is the correction value in the transport direction of the color image data (an example of the "first correction value").

[0118] Furthermore, the control unit 100 calculates the widthwise expansion / contraction ratio SRW_W and the lengthwise expansion / contraction ratio SRL_W of the white image based on the measurement results from steps S4 and S6, respectively, using the following equations 5 and 6.

[0119] SRW_W=W2 / W3...(Formula 5) SRL_W=L2 / L3...(Formula 6)

[0120] SRW_W is the correction value in the width direction of the white plate image data (an example of a "second correction value"), and SRL_W is the correction value in the transport direction of the white plate image data (an example of a "second correction value").

[0121] The control unit 100 may display SRW_4C, SRL_4C, SRW_W, and SRL_W on a display (not shown) of the output device 112 (see Figure 3).

[0122] In step S8, the control unit 100 corrects the color image data using the correction value for the color image data calculated in step S6. Similarly, the control unit 100 corrects the white image data using the correction value for the white image data calculated in step S6.

[0123] In step S9, 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 S8. That is, the user reconnects the substrate 1 from which the cut sample 2 was cut. The transport control unit 102 restarts the transport of the substrate 1 in the transport device 20. The ejection control unit 104 causes the first ejection device 30A to form the corrected color image on the substrate 1 based on the corrected color image data. The drying control unit 106 dries the color image using the first drying device 30B. Similarly, the ejection control unit 104 causes the second ejection device 40A to form the corrected white image on the substrate 1 based on the corrected white image data. Furthermore, the drying control unit 106 dries the white image using the second drying device 40B.

[0124] As a result, users can adjust the finished dimensions of printed materials to match the conditions under which they measure actual dimensions. Therefore, it is possible to manufacture printed materials in which the target dimensions and actual dimensions match.

[0125] Once the correction value has been calculated, for subsequent printed materials of similar quality in terms of substrate and design, and with less stringent requirements for finished dimensions, the correction value can be used to perform corrective printing without performing actual size measurements.

[0126] <Second Embodiment> [Printing System] Figure 7 shows an example of an inkjet printing system according to the second embodiment. The inkjet printing system 11 shown in Figure 7 includes a third measuring device 56 in the transport path of the substrate 1 instead of an external measuring device 54. The third measuring device 56 may be included in the substrate information acquisition unit 50 (see Figure 3). The inkjet printing system 11 also includes an observation table 80 and a tension adjustment mechanism 82.

[0127] The observation stand 80 is a device for the user to observe the image printed on the substrate 1. By stopping the transport of the substrate 1, the user can observe the image at a position opposite the observation stand 80.

[0128] The configuration of the third measuring device 56 is the same as that of the third measuring device 56 provided in the external measuring device 54 (see Figure 5). The third measuring device 56 is positioned at a third location between the second drying device 40B and the winding roll 24 in the transport path of the substrate 1, and is positioned facing the observation table 80 via the substrate 1.

[0129] The edge sensor 72A of the third measuring device 56 is positioned opposite the edge ED on the GS side (see Figure 4) of the substrate 1 being transported by the transport device 20. The edge sensor 72B of the third measuring device 56 is positioned opposite the edge ED on the OS side (see Figure 4) of the substrate 1. The edge sensors 72A and 72B are positioned at the same location in the transport direction of the substrate 1 (Y direction in Figure 7).

[0130] The contrast sensor 74 is positioned opposite the printed surface of the substrate 1 and on the +Z side of the passage position of the cue mark MC.

[0131] Thus, the third measuring device 56 and the observation table 80 are arranged in the same way as the third measuring device 56 and the mounting table 70 in the external measuring device 54.

[0132] The tension adjustment mechanism 82 (an example of a "tension changing mechanism") adjusts the transport tension applied to the substrate 1 at the position of the observation table 80. The tension adjustment mechanism 82 adjusts the tension to be different from the transport tension applied to the substrate 1 during transport by the transport device 20 to the third measuring device 56. The tension adjustment mechanism 82 is controlled by the transport control unit 102 (see Figure 3). The tension adjustment mechanism 82 may also be controlled in response to user operation of the input device 110 (see Figure 3).

[0133] [Method for Manufacturing Printed Materials] Figure 8 is a flowchart showing the method for manufacturing printed materials according to the second embodiment. The processes in steps S1 to S4 are the same as in the first embodiment.

[0134] In step S11, the inkjet printing system 10 stops transporting the substrate 1 and adjusts the tension on the substrate 1. That is, the transport control unit 102 stops the transport device 20 when the image printed on the substrate 1 reaches the position of the observation table 80. The transport control unit 102 also uses the tension adjustment mechanism 82 to set the tension on the substrate 1 to zero (an example of "second tension"), that is, so that there is no tension on the substrate 1. The tension adjustment mechanism 82 may also be controlled by the user by operating the input device 110.

[0135] In step S12, the inkjet printing system 10 automatically measures the actual size of the printed material. Specifically, the measurement control unit 108 detects the X-direction positions of the edges ED at both ends of the substrate 1 using the edge sensors 72A and 72B of the third measuring device 56. The measurement control unit 108 also detects the Y-direction positions of the two cue marks MC on the substrate 1 using the contrast sensor 74 of the third measuring device 56.

[0136] The inkjet printing system 10 may, after the tension applied to the substrate 1 is reduced to zero in step S11 and a desired amount of time has elapsed, measure the actual dimensions in step S12.

[0137] The central control unit 100 calculates the difference in the X-direction positions W3 [millimeters] between the edges ED at both ends of the substrate 1 from the detection results of the edge sensors 72A and 72B. The central control unit 100 also calculates the interval L3 [millimeters] between the cue marks MC from the detection results of the contrast sensor 74.

[0138] The processing in steps S7 to S9 is the same as in the first embodiment.

[0139] Cutting the base material 1 requires the extra step of reattaching it. According to the second embodiment, the extra step of cutting and reattaching the base material 1 can be eliminated, allowing for efficient measurement of the actual dimensions of the printed material.

[0140] <Third Embodiment> [Printing System] Figure 9 is a diagram showing an example of an inkjet printing system according to the third embodiment. The inkjet printing system 12 shown in Figure 9 includes a tension meter 84 and a temperature sensor 86.

[0141] A tension meter 84 (an example of a "conveying condition measuring device") measures the conveying tension (an example of "conveying conditions") applied to the substrate 1 at the position of the observation table 80. A temperature sensor 86 (an example of a "conveying condition measuring device") measures the temperature (an example of "conveying conditions") of the substrate 1 at the position of the observation table 80. The temperature sensor 86 may also measure the ambient temperature near the observation table 80. The tension meter 84 and the temperature sensor 86 are controlled by a measurement control unit 108 (see Figure 3), and the measurement results are acquired.

[0142] [Method for Manufacturing Printed Materials] Figure 10 is a flowchart showing the method for manufacturing printed materials according to the third embodiment. The processes in steps S1 to S4 are the same as in the first embodiment.

[0143] In step S21, the inkjet printing system 10 adjusts the transport tension of the substrate 1 at the position of the third measuring device 56 using the tension adjustment mechanism 82. That is, the transport control unit 102 sets the transport tension applied to the substrate 1 at the position of the third measuring device 56 to a predetermined tension (an example of the "second tension") while continuing to transport the substrate 1. The predetermined tension is the tension applied to the substrate 1 in the next process after printing. The tension applied to the substrate 1 in the next process is, for example, the transport tension when the substrate 1 is transported by the post-processing machine. The next process is, for example, a lamination process or a bag-making process, and the post-processing machine is, for example, a laminating machine or a bag-making machine.

[0144] The transport control unit 102 can set the transport tension of the substrate 1 to a desired tension by controlling the tension adjustment mechanism 82 based on the measurement value of the tension meter 84. The transport control unit 102 may also adjust the transport tension of the substrate 1 by correcting the measurement value of the tension meter 84 with the measurement value of the temperature sensor 86.

[0145] In step S22, the inkjet printing system 10 automatically measures the actual size of the printed material while the substrate 1 is being transported. Specifically, the measurement control unit 108 measures the time interval T3 [seconds] at which the cue mark MC is detected by the contrast sensor 74 of the third measuring device 56. Here, the contrast sensor 74 may be in a fixed position. The measurement control unit 108 also detects the positions in the X direction of the edges ED at both ends of the substrate 1, respectively, by the edge sensors 72A and 72B of the third measuring device 56.

[0146] The central control unit 100 calculates the difference in position W3 [millimeters] in the X direction between the edges ED at both ends of the substrate 1 from the detection results of the edge sensors 72A and 72B.

[0147] Furthermore, the control unit 100 obtains the transport speed V3 [meters / minute] of the substrate 1 at the third position. In addition, the control unit 100 calculates the interval L3 [millimeters] of the cue marks MC at the third position from the time interval T3 and the transport speed V3 using the following equation 7.

[0148] L3=T3×V3 / 60×10 3 ...(Formula 7)

[0149] The processing in steps S7 to S9 is the same as in the first embodiment.

[0150] As a result, the dimensions of the printed material when it is set in the post-processing machine for the next step can be adjusted to match the target dimensions.

[0151] The printed materials produced by the first and second embodiments change dimensions when they are set in the post-processing machine for the next step and tension is applied. Therefore, the post-processing machine is set up by trial and error, and this setup time is the longest and becomes a bottleneck in the production line. According to the third embodiment, pre-setting of the post-processing machine becomes possible simply by exchanging dimensional data between the inkjet printing system 10 and the post-processing machine.

[0152] <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.

[0153] 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.

[0154] 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.

[0155] 1…Substrate 2…Cut sample 10, 11, 12…Inkjet printing system 20…Conveyor 22…Pass roller 24…Winding roll 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 54…External measuring device 56…Third measuring device 60…Mark sensor 62A…Edge sensor 62B…Edge sensor 70…Mounting platform 72A…Edge sensor 72B…Edge sensor 74…Contrast sensor 80…Observation platform 82…Tension adjustment mechanism 84...Tension meter 86...Temperature sensor 100...General control unit 102...Conveying control unit 104...Discharge control unit 106...Drying control unit 108...Measurement control unit 110...Input device 112...Output device ED...Edge IP...Printed image MC...Cue mark S1-S9, S11, S12, S21, S22...Steps of the method for manufacturing printed materials

Claims

1. A printing system for printing an image on a substrate, comprising: a first image forming apparatus for forming a first image on the substrate based on first image data; a first measuring apparatus for measuring the state of the substrate; a transport apparatus for transporting the substrate in the order of the first image forming apparatus and the first measuring apparatus; and a processor, wherein the first measuring apparatus measures the state of the substrate by detecting marks formed on the substrate by the first image forming apparatus; the processor obtains the actual size of the substrate on which the first image is formed, measured by applying a second tension to the substrate in the transport apparatus that is different from a first tension applied to the substrate; and calculates a first correction value for correcting the first image data based on the measurement result of the first measuring apparatus and the actual size.

2. A printing system according to claim 1, comprising: a second image forming apparatus for forming a second image on a substrate based on a second image data; and a second measuring apparatus for measuring the state of the substrate, wherein the transport apparatus transports the substrate in the order of the first image forming apparatus, the first measuring apparatus, the second image forming apparatus, and the second measuring apparatus; the second measuring apparatus detects the marks and measures the state of the substrate; and the processor calculates a second correction value for correcting the second image data based on the measurement result of the second measuring apparatus and the actual size.

3. The printing system according to claim 1, wherein the second tension is less than the first tension.

4. The printing system according to claim 3, wherein the second tension is zero.

5. The printing system according to claim 1, wherein the second tension is the tension applied to the substrate in the next step after printing.

6. The printing system according to claim 1, wherein the first measuring device measures the spacing of the marks in the transport direction of the substrate in the transport device and the width of the substrate, and the actual dimensions are obtained from the spacing of the marks in the transport direction of the substrate in the transport device and the width of the substrate.

7. The printing system according to claim 1, wherein the actual size is the dimensions of the offline printed material after printing.

8. The printing system according to claim 7, wherein the substrate is a long web substrate, and the offline printed material after printing is a sheet-fed printed material obtained by cutting the web substrate.

9. The printing system according to claim 8, further comprising an external measuring device for measuring the dimensions of the sheet-fed printed material.

10. The printing system according to claim 2, comprising a third measuring device for measuring the actual dimensions, wherein the transport device transports the substrate in the order of the second measuring device and the third measuring device, and further comprises a tension changing mechanism for changing the tension applied to the substrate at the position of the third measuring device to the second tension.

11. The printing system according to claim 10, wherein the third measuring device measures the actual dimensions while the transport device is stopped.

12. The printing system according to claim 10, further comprising a transport condition measuring device for measuring the transport conditions of the substrate at the position of the third measuring device.

13. The printing system according to claim 12, wherein the transport condition measuring device measures at least one of the tension applied to the substrate and the temperature of the substrate.

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

15. The printing system according to claim 1, wherein the processor corrects the first image data with the first correction value.

16. The printing system according to claim 15, wherein the first image forming apparatus forms a corrected first image based on the corrected first image data.

17. A method for manufacturing a printed material, comprising: transporting a substrate in a transport device in the order of a first image forming device and a first measuring device; forming a first image on the substrate in the first image forming device based on first image data; detecting a mark formed on the substrate by the first image forming device with the first measuring device to measure the state of the substrate; obtaining the actual size of the substrate on which the first image is formed, by applying a second tension to the substrate in the transport device that is different from a first tension applied to the substrate; calculating a first correction value based on the measurement result of the first measuring device and the actual size; correcting the first image data with the first correction value; transporting the substrate to the first image forming device in the transport device; and forming a corrected first image on the substrate in the first image forming device based on the corrected first image data.

Images