INKJET PRINTING SYSTEM

Abstract

 An inkjet printing system that can reduce displacement in images to be printed on both sides of a medium (80) is to be provided. The inkjet printing system is provided with a front surface head that performs printing on a front surface of a medium (80), a rear surface head that performs printing on a rear surface (80b) of the medium to which printing has been performed by the front surface head, a front surface print controlling section that causes the front surface head to print an image (60) including a front position mark (62a, 62b) for print control adjustment, a rear surface print controlling section that causes the rear surface head to print an image (70) including a rear position mark (72a, 72b) for print control adjustment, and a displacement calibrating section that calibrates a displacement between the images (60, 70) to be printed on both sides of the medium (80). The displacement calibrating section calibrates the displacement between the images (60, 70) to be printed on both sides of the medium (80) by adjusting print control by the rear surface print controlling section in accordance with an amount of displacement between the front position mark (62a, 62b) and the rear position mark (72a, 72b).

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of Japanese Patent Application No. 2015-063447, filed on March 25, 2015. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

[0002] The disclosure relates to an inkjet printing system that performs printing on both sides of a medium.

DESCRIPTION OF THE BACKGROUND ART

[0003] Conventionally, as an inkjet printing system that performs printing on both sides of a medium, a configuration that includes a first inkjet head that performs printing on one surface of the medium and a second inkjet head that performs printing on the other surface of the medium to which the printing has been performed by the first inkjet head is known (for example, see Patent Document 1).
[Patent Document 1] JP 2010-053497 A

SUMMARY

[0004] However, in the conventional inkjet printing system, there is a problem that a displacement is generated in the printed images on both sides of the medium.

[0005] Thus, the present disclosure aims to provide an inkjet printing system that can reduce the displacement in the images to be printed on both sides of the medium.

[0006] An inkjet printing system of the present disclosure includes: a first inkjet head that performs printing on one surface of a medium; a second inkjet head that performs printing on the other surface of the medium to which printing has been performed by the first inkjet head; a first print controlling section that causes the first inkjet head to print an image including a fist image for print control adjustment; a second print controlling section that causes the second inkjet head to print an image including a second image for print control adjustment; and a displacement calibrating section that calibrates a displacement between the images to be printed on both sides of the medium. In this system, the displacement calibrating section calibrates the displacement between the images to be printed on both sides of the medium by adjusting at least one of print control by the first print controlling section and print control by the second print controlling section in accordance with an amount of displacement between the first image and the second image.

[0007] According to this configuration, the inkjet printing system of the present disclosure calibrates the displacement in the images to be printed on both sides of the medium by adjusting the print control according to the amount of displacement between the first image printed on the one surface of the medium and the second image printed on the other surface of the medium, thus the displacement in the images to be printed on both sides of the medium can be reduced.

[0008] Further, the inkjet printing system of the present disclosure may further include: a both-side image detecting section that detects the first image and the second image on the medium; and a displacement amount calculating section that calculates the amount of displacement between the first image and the second image based on a detection result by the both-side image detecting section.

[0009] According to this configuration, since the inkjet printing system of the present disclosure automatically calculates the amount of displacement of the first image and the second image, convenience can be improved as compared to a configuration in which a user determines the amount of displacement of the first image and the second image from the medium.

[0010] Further, in the inkjet printing system of the present disclosure, the both-side image detecting section may detect the first image and the second image from one surface side of the medium.

[0011] According to this configuration, the inkjet printing system of the present disclosure simultaneously detects the first image printed on the one surface of the medium and the second image printed on the other surface of the medium from one surface side of the medium, the amount of displacement of the first image and the second image can be detected highly accurately as compared to a configuration in which the first image printed on the one surface of the medium and the second image printed on the other surface of the medium are respectively detected from a one surface side of the medium and the other surface side of the medium. Thus, the inkjet printing system of the present disclosure can calibrate the displacement in the images to be printed on both sides of the medium highly accurately, as a result of which the displacement in the images to be printed on both sides of the medium can further be reduced.

[0012] Further, in the inkjet printing system of the present disclosure, the displacement calibrating section may calibrate the displacement between the images to be printed on both sides of the medium according to the amount of displacement between the first image and the second image calculated by the displacement amount calculating section.

[0013] According to this configuration, since the inkjet printing system of the present disclosure automatically calibrates the displacement in the images to be printed on both sides of the medium according to the amount of displacement of the first image and the second image that has been calculated automatically, convenience can be improved as compared to a configuration in which a suitable instruction for calibrating the displacement in the images to be printed on both sides of the medium is manually inputted by the user based on the amount of displacement of the first image and the second image.

[0014] Further, in the inkjet printing system of the present disclosure, the first print controlling section and the second print controlling section may cause the first image and the second image to be printed in a state in which the both-side image detecting section can detect the first image and the second image from one surface side of the medium.

[0015] According to this configuration, the inkjet printing system of the present disclosure can simultaneously detect the first image printed on the one surface of the medium and the second image printed on the other surface of the medium from one surface side of the medium, the amount of displacement of the first image and the second image can be detected highly accurately as compared to a configuration in which the first image printed on the one surface of the medium and the second image printed on the other surface of the medium are respectively detected from a one surface side of the medium and the other surface side of the medium. Thus, the inkjet printing system of the present disclosure can calibrate the displacement in the images to be printed on both sides of the medium highly accurately, as a result of which the displacement in the images to be printed on both sides of the medium can further be reduced.

[0016] Further, in the inkjet printing system of the present disclosure, the displacement amount calculating section may calculate the amount of displacement between the first image and the second image based on an average of detection results from plural times of detection of the first image and the second image by the both-side image detecting section.

[0017] According to this configuration, the inkjet printing system of the present disclosure can improve the accuracy of the calibration of the displacement in the images to be printed on both sides of the medium in a case where the amount of displacement of the first image and the second image varies each time the first image and the second image are detected by the both-side image detecting section. Accordingly, the inkjet printing system of the present disclosure can further reduce the displacement in the images to be printed on both sides of the medium.

[0018] Further, the inkjet printing system of the present disclosure may include a one-side image detecting section that detects the first image on the medium that is before printing is performed by the second inkjet head, and the displacement calibrating section calibrates the displacement between the images to be printed on both sides of the medium by adjusting the print control by the second print controlling section according to a detection result obtained by the one-side image detecting section.

[0019] According to this configuration, the inkjet printing system of the present disclosure further calibrates the displacement in the images to be printed on both sides of the medium according to the amount of displacement of the first image and the second image after having performed printing on the other surface of the medium by having performed calibration so that the second image to be printed on the other surface of the medium would not be displaced relative to the first image printed on one surface of the medium. Therefore, the displacement in the images to be printed on both sides of the medium can further be reduced.

[0020] The inkjet printing system of the present disclosure can reduce the displacement in the images to be printed on both sides of the medium.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 

FIG. 1 is a plan view of an inkjet printing system according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of the inkjet printing system illustrated in FIG. 1, as viewed from a front side;

FIG. 3 is a schematic structural diagram of the inkjet printing system illustrated in FIG. 1, as viewed from a right lateral side;

FIG. 4 is a block diagram of the inkjet printing system illustrated in FIG. 1;

FIG. 5 is a diagram of an example of an image that a front surface print controlling section illustrated in FIG. 4 causes a front surface printer to print;

FIG. 6 is a diagram of the image illustrated in FIG. 5, as viewed from a rear surface side of a medium;

FIG. 7 is a flow chart of an operation of the inkjet printing system illustrated in FIG. 1 according to a detection result of a front-side image position detecting device;

FIG. 8 is a diagram of an example of an image that the rear surface print controlling section illustrated in FIG. 4 causes a rear surface printer to print;

FIG. 9 is a diagram of the image illustrated in FIG. 5 and the image illustrated in FIG. 8, as viewed from the rear surface side of the medium;

FIG. 10 is a flow chart of an operation of the inkjet printing system illustrated in FIG. 1 according to a detection result of a front and rear image position detecting device; and

FIG. 11A is a diagram of an example different from the example illustrated in FIG. 9 and shows a case where a front position mark and a rear position mark are not displaced, and FIG. 11B shows a case where the front position mark and the rear position mark illustrated in FIG. 11A are displaced.

DETAILED DESCRIPTION OF EMBODIMENTS

[0022] One embodiment of the present disclosure will be described hereinbelow with reference to the drawings.

[0023] Firstly, a configuration of an inkjet printing system according to the present embodiment will be described.

[0024] FIG. 1 is a plan view of an inkjet printing system 10 according to an embodiment of the present disclosure. FIG. 2 is a schematic structural diagram of the inkjet printing system 10 as viewed from a front side. FIG. 3 is a schematic structural diagram of the inkjet printing system 10 as viewed from a right lateral side. In FIGs. 2 and 3, parts of front surface printers 20 and 30 are cross sectioned to illustrate internal configurations thereof.

[0025] As illustrated in FIGs. 1 to 3, the inkjet printing system 10 is a system for performing printing on one surface of a medium 80 such as a cloth and then performing printing on the other surface of the medium 80. Hereinbelow, the one surface of the medium 80 will be termed a front surface 80a, and the other surface of the medium 80 will be termed a rear surface 80b. The medium 80 may be anything other than cloth, so long as it has a sheet-like shape.

[0026] The inkjet printing system 10 includes a front surface printer 20 that is an inkjet printer for performing printing on the front surface 80a of the medium 80, and a rear surface printer 30 that is an inkjet printer for performing printing on the rear surface 80b of the medium 80 to which the printing has been performed on the front surface 80a by the front surface printer 20. The surface printers 20 and 30 are installed on a floor 90. The medium 80 is supplied to the front surface printer 20 from a roller not shown, onto which the medium 80 is wound. Further, the medium 80 printed by the rear surface printer 30 is wound up by another roller that is not shown.

[0027] The inkjet printing system 10 is provided with an inverting roller 41 that inverts front and rear sides of the medium 80 with the front surface 80a having been printed by the front surface printer 20, a direction changing roller 42 that changes a transferring direction of the medium 80 whose front and rear sides have been inverted by the inverting roller 41, a direction changing roller 43 that changes the transferring direction of the medium 80 whose transferring direction has been changed by the direction changing roller 42, and a tension applying member 44 that applies a certain tension on the medium 80 whose transferring direction has been changed by the direction changing roller 43. The inverting roller 41, the direction changing roller 42, the direction changing roller 43, and the tension applying member 44 are arranged to be aligned in a direction illustrated by an arrow 10b, which intersects vertically to a vertical direction illustrated by an arrow 10a. Further, the inverting roller 41, the direction changing roller 42, the direction changing roller 43, and the tension applying member 44 extend along a direction illustrated by an arrow 10c, which intersects vertically to both the direction illustrated by the arrow 10a and the direction illustrated by the arrow 10b. The inverting roller 41, the direction changing roller 42, and the direction changing roller 43 are supported by a supporting mechanism that is not shown, in a state of having positions of their central axis extending in the direction illustrated by the arrow 10c and a state of being rotatable about the central axis. The tension applying member 44 is a member that applies a certain tension to the medium 80 by gravity directed downward in the vertical direction illustrated by the arrow 10a. As the inkjet printing system 10 can allow a length of the medium 80 between the front surface printer 20 and the rear surface printer 30 to be changed by being provided with the tension applying member 44 for applying the certain tension on the medium 80, it can allow a transferring speed of the medium 80 in the front surface printer 20 and a transferring speed of the medium 80 in the rear surface printer 30 to be different from each other, as a result of which the printing by the front surface printer 20 and the printing by the rear surface printer 30 can be controlled independently to some degree.

[0028] The inkjet printing system 10 includes a front-side image position detecting device 51 as a one-side image detecting section that detects a front position mark on a medium 80, to which the front position mark as a first image for print control adjustment has been printed on a front surface 80a thereof by the front surface printer 20 but the printing by the rear surface printer 30 has not been performed yet, and a front and rear image position detecting device 52 as a both-side image detecting section that detects the front position mark and a rear position mark on the medium 80, to which the rear position mark as a second image for print control adjustment has been printed on a rear surface 80b thereof by the rear surface printer 30. The front-side image position detecting device 51 is disposed on a transfer passage of the medium 80 between the front surface printer 20 and the rear surface printer 30. The front and rear image position detecting device 52 is disposed on a downstream side of the rear surface printer 30 in a transferring direction of the medium 80.

[0029] The front surface printer 20 includes a front surface head 21 as a first inkjet head supported movably in a direction illustrated by an arrow 10b by a supporting mechanism that is not shown, a transfer roller 22 that transfers the medium 80 relative to the front surface head 21 in a direction illustrated by an arrow 10c, a pressing roller 23 that is disposed at a position facing the transfer roller 22 via the medium 80 and presses the medium 80 onto the transfer roller 22, a pre-process heater 24 that heats the medium 80 before ink is adhered thereon by the front surface head 21 for uniformizing a printing condition by the front surface head 21, a printing heater 25 for heating the medium 80 at the time when the ink is adhered thereon by the front surface head 21 for stabilization of striking accuracy of ink droplets, which is discharged by the front surface head 21 and is to be adhered onto the medium 80, and for prevention of ink smearing after it has struck, and a post-process heater 26 for heating the medium 80 to which the ink has been adhered by the front surface head 21 in order to promote drying of the ink adhered to the medium 80 by the front surface head 21.

[0030] Similarly, the rear surface printer 30 includes a rear surface head 31 as a second inkjet head supported movably in the direction illustrated by the arrow 10c by a supporting mechanism that is not shown, a transfer roller 32 that transfers the medium 80 relative to the rear surface head 31 in the direction illustrated by the arrow 10b, a pressing roller 33 that is disposed at a position facing the transfer roller 32 via the medium 80 and presses the medium 80 onto the transfer roller 32, a pre-process heater 34 that heats the medium 80 before ink is adhered thereon by the rear surface head 31 for uniformizing a printing condition by the rear surface head 31, a printing heater 35 for heating the medium 80 at the time when the ink is adhered thereon by the rear surface head 31 for stabilization of striking accuracy of ink droplets, which is discharged by the rear surface head 31 and is to be adhered onto the medium 80, and for prevention of ink smearing after it has struck, and a post-process heater 36 for heating the medium 80 to which the ink has been adhered by the rear surface head 31 in order to promote drying of the ink adhered to the medium 80 by the rear surface head 31.

[0031] FIG. 4 is a block diagram of the inkjet print system 10.

[0032] As illustrated in FIG. 4, the inkjet printing system 10 is provided with an operation section 11 being an input device such as a mouse or a keyboard with which various operations are to be inputted, a display section 12 being a display device such as an LCD (Liquid Crystal Display) or the like for displaying various types of information, a communication section 13 being a communication device for communicating with an external device, a storage section 14 being a storage device such as EEPROM (Electrically Erasable Programmable Read Only Memory), HDD(Hard Disk Drive), or the like that stores various types of data, and a control section 15 that controls an entirety of the inkjet printing system 10.

[0033] The control section 15 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores program and various types of data in advance, and a RAM (Random Access Memory) to be used as work area for the CPU. The CPU is configured to execute the program stored in the ROM or the storage section 14.

[0034] The control section 15 functions, by executing the program stored in the ROM or the storage section 14, as a front surface print controlling section 15a that is a first print controlling section for causing the front surface head 21 of the front surface printer 20 (see FIGs. 2 and 3) to print an image, a rear surface print controlling section 15b that is a second print controlling section for causing the rear surface head 31 of the rear surface printer 30 (see FIGs. 2 and 3) to print an image, a displacement amount calculating section 15c that calculates an amount of displacement between a front position mark and a rear position mark based on a detection result of the front and rear image position detecting device 52 (see FIG. 1), and a displacement calibrating section 15d that calibrates a displacement of the images to be printed on both sides of the medium 80 (see FIG. 1).

[0035] Next, an operation of the inkjet print system 10 will be described.

[0036] When print data is sent from a computer such as a PC (Personal Computer) or the like that is not illustrated, the front surface print controlling section 15a prints an image based on the sent print data (hereinbelow referred to as a "target image") on the medium 80 by the front surface printer 20. Specifically, the front surface print controlling section 15a causes ink to be discharged onto the medium 80 by the front surface head 21 while moving the front surface head 21 in a main scanning direction shown by an arrow 10b and a sub scanning direction shown by an arrow 10c relative to the medium 80. Here, the front surface print controlling section 15a moves the front surface head 21 in the main scanning direction if a relative position of the front surface head 21 relative to the medium 80 along the main scanning direction is to be changed. Further, the front surface print controlling section 15a moves the medium 80 by the transfer roller 22 in the sub scanning direction if the relative position of the front surface head 21 relative to the medium 80 along the sub scanning direction is to be changed.

[0037] In a case of printing the target image on the medium 80 by the front surface printer 20, the front surface print controlling section 15a prints the front position mark together with the target image on the medium 80 by the front surface printer 20. That is, an image that the front surface print controlling section 15a causes the front surface printer 20 to print includes the target image and the front position mark.

[0038] FIG. 5 is a diagram illustrating an example of an image 60 that the front surface print controlling section 15a causes the front surface printer 20 to print.

[0039] As illustrated in FIG. 5, the image 60 includes a target image 61 and a front position mark 62.

[0040] The front position mark 62 includes a front reference position mark 62a for determining a reference position of the target image 61. For example, the front reference position mark 62a is preferably arranged on a downstream side in a transferring direction of the medium 80 relative to the target image 61 shown by the arrow 10c. Further, the front reference position mark 62a is preferably arranged at one end, the other end, or center of the medium 80 in the direction illustrated by the arrow 10b.

[0041] The front position mark 62 includes at least one front relative position mark 62b for determining the relative position with respect to the front reference position mark 62a. For example, the front relative position mark 62b is preferably arranged on at least one of the following sides: one end side of the medium 80 relative to the target image 61 in the direction illustrated by the arrow 10b, the other end side of the medium 80 relative to the target image 61 in the direction illustrated by the arrow 10b, one end side of the medium 80 relative to the target image 61 in the direction illustrated by the arrow 10c, and the other end side of the medium 80 relative to the target image 61 in the direction illustrated by the arrow 10c. Further, for example, the front relative position mark 62b is preferably arranged at least one of the followings: one end, the other end, and center of the medium 80 in the direction illustrated by the arrow 10b.

[0042] The rear surface print controlling section 15b transfers the medium 80 in the sub scanning direction illustrated by the arrow 10b by the transfer roller 32 of the rear surface printer 30 accompanying the printing on a front surface 80a by the front surface print controlling section 15a.

[0043] FIG. 6 is a diagram of the image 60 as viewed from a rear surface 80b side of the medium 80.

[0044] In a case where the front reference position mark 62a and the front relative position mark 62b printed on the front surface 80a of the medium 80 by the front surface printer 20 are printed on a thin medium 80, or in a case where they are printed by a large amount of ink that would soak into the inside of the medium 80 despite the medium 80 being a thick cloth, they penetrate to the rear surface 80b of the medium 80 as illustrated in FIG. 6. Thus, when the medium 80 is transferred in the sub scanning direction illustrated by the arrow 10b by the transfer roller 32 of the rear surface printer 30, the front reference position mark 62a and the front relative position mark 62b are detected by the front-side image position detecting device 51 from a rear surface 80b side of the medium 80.

[0045] FIG. 7 is a flow chart of an operation of the inkjet printing system 10 according to the detection result of the front-side image position detecting device 51.

[0046] The control section 15 performs the operation illustrated in FIG. 7 each time the front position mark 62 is detected by the front-side image position detecting device 51.

[0047] As illustrated in FIG. 7, the displacement amount calculating section 15c calculates the amount of displacement between the target image 61 that is actually printed on the front surface 80a of the medium 80 by the front surface printer 20 and the target image 61 in data of the image 60 generated by the front surface print controlling section 15a(S101).

[0048] Specifically, the displacement amount calculating section 15c can calculate the amount of displacement between reference positions in the direction illustrated by the arrow 10b and the direction illustrated by the arrow 10c between the target image 61 that is actually printed on the front surface 80a of the medium 80 by the front surface printer 20 and the target image 61 in the data of the image 60 generated by the front surface print controlling section 15a, based on the position of the front reference position mark 62a in the detection result of the front-side image position detecting device 51 and the position of the front reference position mark 62a in the data of the image 60 generated by the front surface print controlling section 15a.

[0049] Further, the displacement amount calculating section 15c can calculate the amount of displacement in size in a direction of the front relative position mark 62b relative to the front reference position mark 62a and the amount of displacement in angle in the direction of the front relative position mark 62b relative to the front reference position mark 62a between the target image 61 that is actually printed on the front surface 80a of the medium 80 by the front surface printer 20 and the target image 61 in the data of the image 60 generated by the front surface print controlling section 15a, based on the relative position of the front relative position mark 62b relative to the front reference position mark 62a in the detection result of the front-side image position detecting device 51 and the relative position of the front relative position mark 62b relative to the front reference position mark 62a in the data of the image 60 generated by the front surface print controlling section 15a.

[0050] After the process of S101, the displacement calibrating section 15d determines whether or not the displacement amount calculated in S101 exceeds a specific allowable amount (S102).

[0051] In determining that the allowable amount is exceeded in S102, the displacement calibrating section 15d instructs the front surface print controlling section 15a to change at least one of the reference position, size, and angle of the image to be printed on the front surface 80a of the medium 80 by the front surface printer 20 so that the displacement amount would be within the allowable amount (S103). Accordingly, as to the target image 61 to be newly printed on the front surface 80a by the front surface print controlling section 15a, the displacement from the target image 61 in the data of the image 60 generated by the front surface print controlling section 15a is thereby calibrated.

[0052] In determining that the allowable amount is not exceeded in S102 or when the process of S103 is completed, the displacement calibrating section 15d instructs the rear surface print controlling section 15b to change at least one of reference position, size, and angle of the image to be printed on the rear surface 80b of the medium 80 by the rear surface printer 30 so that the target image 61 that is actually printed on the front surface 80a of the medium 80 by the front surface printer 20 and the image to be printed on the rear surface 80b of the medium 80 by the rear surface printer 30 overlap via the medium 80 without displacement (S104). That is, the displacement calibrating section 15d calibrates the displacement in the images to be printed on both sides of the medium 80 by adjusting the print control by the rear surface print controlling section 15b according to the detection result of the front-side image position detecting device 51.

[0053] When the process of S104 is completed, the displacement calibrating section 15d ends the operation illustrated in FIG. 7.

[0054] When the front reference position mark 62a is detected by the front-side image position detecting device 51, the rear surface print controlling section 15b starts the printing by the rear surface printer 30 at the time point when a specific amount has been transferred by the transfer roller 32 since when the front reference position mark 62a is detected by the front-side image position detecting device 51. Specifically, the rear surface print controlling section 15b prints the mirrored target image, which mirrors the target image printed by the front surface printer 20, on the medium 80 by the rear surface printer 30. Specifically, the rear surface print controlling section 15b causes ink to be discharged by the rear surface head 31 onto the medium 80 while moving the rear surface head 31 in the main scanning direction shown by the arrow 10c and the sub scanning direction shown by the arrow 10b relative to the medium 80. Here, the rear surface print controlling section 15b moves the rear surface head 31 in the main scanning direction if the relative position of the rear surface head 31 relative to the medium 80 along the main scanning direction is to be changed. Further, the rear surface print controlling section 15b moves the medium 80 by the transfer roller 32 in the sub scanning direction if the relative position of the rear surface head 31 relative to the medium 80 along the sub scanning direction is to be changed.

[0055] In a case of printing the mirrored target image on the medium 80 by the rear surface printer 30, the rear surface print controlling section 15b prints the rear position mark together with the mirrored target image on the medium 80 by the rear surface printer 30. That is, an image that the rear surface print controlling section 15b causes the rear surface printer 30 to print includes the mirrored target image and the rear position mark.

[0056] FIG. 8 is a diagram illustrating an example of an image 70 that the rear surface print controlling section 15b causes the rear surface printer 30 to print. In FIG. 8, to enhance easy understanding of the image 70, the image 60 (see FIG. 6) printed on the front surface 80a of the medium 80 and permeating to the rear surface 80b of the medium 80 is not depicted.

[0057] As illustrated in FIG. 8, the image 70 includes a mirrored target image 71 and a rear position mark 72.

[0058] The rear position mark 72 includes a rear reference position mark 72a for determining a reference position of the mirrored target image 71. Further, the rear position mark 72 includes at least one rear relative position mark 72b for determining the relative position with respect to the rear reference position mark 72a.

[0059] As illustrated in FIGs. 5 and 8, the image 70 to be printed on the rear surface 80b by the rear surface printer 30 is an image that mirrored the image 60 to be printed on the front surface 80a by the front surface printer 20.

[0060] FIG. 9 is a diagram observing the image 60 and the image 70 from the rear surface 80b side of the medium 80.

[0061] In the case where the front reference position mark 62a and the front relative position mark 62b printed on the front surface 80a of the medium 80 by the front surface printer 20 are printed on a thin medium 80, or in the case where they are printed by a large amount of ink that would soak into the inside of the medium 80 despite the medium 80 being a thick cloth, they penetrate to the rear surface 80b of the medium 80 as illustrated in FIG. 9. Thus, when the medium 80 is transferred in the sub scanning direction illustrated by the arrow 10b by the transfer roller 32 of the rear surface printer 30, the front reference position mark 62a and the front relative position mark 62b are detected by the front and rear image position detecting device 52 from the rear surface 80b side of the medium 80. Further, both the rear reference position mark 72a and the rear relative position mark 72b printed on the rear surface 80b of the medium 80 by the rear surface printer 30 are detected by the front and rear image position detecting device 52 from the rear surface 80b side of the medium 80.

[0062] FIG. 10 is a flow chart of an operation of the inkjet printing system 10 according to the detection result of the front and rear image position detecting device 52.

[0063] The control section 15 performs the operation illustrated in FIG. 10 each time the front position mark 62 and the rear position mark 72 are detected by the front and rear image position detecting device 52.

[0064] As illustrated in FIG. 10, the displacement amount calculating section 15c calculates the amount of displacement between the mirrored target image 71 that is actually printed on the rear surface 80b of the medium 80 by the rear surface printer 30 and the mirrored target image 71 in data of the image 70 generated by the rear surface print controlling section 15b (S111).

[0065] Specifically, the displacement amount calculating section 15c can calculate the amount of displacement between reference positions in the direction illustrated by the arrow 10b and the direction illustrated by the arrow 10c between the mirrored target image 71 that is actually printed on the rear surface 80b of the medium 80 by the rear surface printer 30 and the mirrored target image 71 in the data of the image 70 generated by the rear surface print controlling section 15b, based on the position of the rear reference position mark 72a in the detection result of the front and rear image position detecting device 52 and the position of the rear reference position mark 72a in the data of the image 70 generated by the rear surface print controlling section 15b.

[0066] Further, the displacement amount calculating section 15c can calculate the amount of displacement in size in a direction of the rear relative position mark 72b relative to the rear reference position mark 72a and the amount of displacement in angle in the direction of the rear relative position mark 72b relative to the rear reference position mark 72a between the mirrored target image 71 that is actually printed on the rear surface 80b of the medium 80 by the rear surface printer 30 and the mirrored target image 71 in the data of the image 70 generated by the rear surface print controlling section 15b, based on the relative position of the rear relative position mark 72b relative to the rear reference position mark 72a in the detection result of the front and rear image position detecting device 52 and the relative position of the rear relative position mark 72b relative to the rear reference position mark 72a in the data of the image 70 generated by the rear surface print controlling section 15b.

[0067] After the process of S111, the displacement calibrating section 15d determines whether or not the displacement amount calculated in S111 exceeds a specific allowable amount (S112).

[0068] In determining that the allowable amount is exceeded in S112, the displacement calibrating section 15d instructs the rear surface print controlling section 15b to change at least one of the reference position, size, and angle of the image to be printed on the rear surface 80b of the medium 80 by the rear surface printer 30 so that the displacement amount would be within the allowable amount (S113). Accordingly, as to the mirrored target image 71 to be newly printed on the rear surface 80b by the rear surface print controlling section 15b, the displacement from the mirrored target image 71 in the data of the image 70 generated by the rear surface print controlling section 15b is thereby calibrated.

[0069] When the process of S 113 is completed, the displacement calibrating section 15d ends the operation illustrated in FIG. 10.

[0070] In determining in S112 that the allowable amount is not exceeded, the displaced amount calculating section 15c calculates the displaced amount between the target image 61 that is actually printed on the front surface 80a of the medium 80 by the front surface printer 20 and the mirrored target image 71 that is actually printed on the rear surface 80b of the medium 80 by the rear surface printer 30 (S114).

[0071] Specifically, the displacement amount calculating section 15c can calculate the amount of displacement between reference positions in the direction illustrated by the arrow 10b and the direction illustrated by the arrow 10c between the target image 61 that is actually printed on the front surface 80a of the medium 80 by the front surface printer 20 and the mirrored target image 71 that is actually printed on the rear surface 80b of the medium 80 by the rear surface printer 30, based on the position of the front reference position mark 62a in the detection result of the front and rear image position detecting device 52 and the position of the rear reference position mark 72a in the detection result of the front and rear image position detecting device 52.

[0072] Further, the displacement amount calculating section 15c can calculate the amount of displacement in size in a direction of the relative position mark relative to the reference position mark and the amount of displacement in angle in the direction of the relative position mark relative to the reference position mark between the target image 61 that is actually printed on the front surface 80a of the medium 80 by the front surface printer 20 and the mirrored target image 71 that is actually printed on the rear surface 80b of the medium 80 by the rear surface printer 30, based on the relative position of the front relative position mark 62b relative to the front reference position mark 62a in the detection result of the front and rear image position detecting device 52 and the relative position of the rear relative position mark 72b relative to the rear reference position mark 72a in the detection result of the front and rear image position detecting device 52.

[0073] After the process of S114, the displacement calibrating section 15d determines whether or not the displacement amount calculated in S114 exceeds a specific allowable amount (S 115).

[0074] In determining that the allowable amount is exceeded in S115, the displacement calibrating section 15d instructs the rear surface print controlling section 15b to change at least one of the reference position, size, and angle of the image to be printed on the rear surface 80b of the medium 80 by the rear surface printer 30 so that the displaced amount would be within the allowable amount (S116). That is, the displacement calibrating section 15d calibrates the displacement in the images to be printed on both sides of the medium 80 by adjusting the print control by the rear surface print controlling section 15b according to the amount of displacement between the front position mark 62 and the rear position mark 72. Accordingly, as to the mirrored target image 71 to be newly printed on the rear surface 80b by the rear surface print controlling section 15b, the displacement from the target image 61 printed on the front surface 80a of the medium 80 is thereby calibrated.

[0075] In determining that the allowable amount is not exceeded in S115 or when the process of S116 is completed, the displacement calibrating section 15d ends the operation illustrated in FIG. 10.

[0076] As described above, the inkjet printing system 10 can reduce the displacement in the images to be printed on both sides of the medium 80, since the displacement in the images to be printed on both sides of the medium 80 is calibrated by adjusting the print control according to the amount of displacement between the front position mark 62 printed on the front surface 80a of the medium 80 and the rear position mark 72 printed on the rear surface 80b of the medium 80 (S116).

[0077] Thus, the inkjet printing system 10 can print highly precise images on both sides of the medium 80. Due to this, the inkjet printing system 10 can print on luxury products being a thin fabric with aesthetic surfaces on both sides, such as a scarf or a handkerchief. Further, printing on luxury fabric and luxury woven fabric configured of thick fabric such as a curtain, which may be observed from both sides becomes enabled. Especially with the thin fabric, in cases where printing is performed only on the front surface, a portion on the rear surface among fibers where printing is not performed may appear on the front surface by being washed and the fibers therein being inversed, which causes the image printed on the front surface to become thinner as a result of the washing. However, the inkjet printing system 10 can print on both surfaces of the thin fabric, so the image printed on both sides is less likely to fade even if the fibers are inverted by washing, as a result of which a printed object that is resistant to washing can be produced.

[0078] The inkjet printing system 10 further calibrates the displacement in the images to be printed on both sides of the medium 80 according to the amount of displacement of the front position mark 62 and the rear position mark 72 (S116) after having performed printing on the rear surface 80b of the medium 80 by having calibrated so that the rear position mark 72 printed on the rear surface 80b of the medium 80 is not displaced relative to the front position mark 62 printed on the front surface 80a of the medium 80 (S104). Therefore, the displacement in the images to be printed on both sides of the medium 80 can further be reduced.

[0079] Since the inkjet printing system 10 automatically calculates the amount of displacement of the front position mark 62 and the rear position mark 72, convenience can be improved as compared to a configuration in which a user determines the amount of displacement of the front position mark 62 and the rear position mark 72 from the medium 80.

[0080] The inkjet printing system 10 may not automatically calculate the amount of displacement of the front position mark 62 and the rear position mark 72, but it may be configured such that the user is to make the determination from the medium 80. For example, the inkjet printing system 10 can make it easy for the user to determine the displacement amount from the medium 80 if a scale is printed as the front position mark 62 and the rear position mark 72.

[0081] FIG. 11A is a diagram of an example of the front position mark 62 and the rear position mark 72 in a case where no displacement is present. FIG. 11B is a diagram of the front position mark 62 and the rear position mark 72 illustrated in FIG. 11A in a case where displacement is present.

[0082] The scale of the rear position mark 72 illustrated in FIG. 11A is depicted with 5% shorter intervals than the scale of the front position mark 62. In FIG. 11A, the front position mark 62 includes a triangle 62c indicating a position of a scale line to be the reference. Similarly, the rear position mark 72 includes a triangle 72c indicating a position of a scale line to be the reference. Accordingly, in a case where the scale of the front position mark 62 and the scale of the rear position mark 72 are displaced as illustrated in FIG. 11B, since the scale lines at a position shown by an arrow 100, that is, the scale lines that are apart from the reference scale lines by four scale lines, have a matched position, it can be understood that the printing of the rear surface 80b (see FIG. 1) is displaced relative to the printing of the front surface 80a (see FIG. 1) in a direction indicated by an arrow 101 by 20% of one scale line (= 5% × 4). The displacement amount shown in FIG. 11B may be determined visually by the user from the medium 80, or the inkjet printing system 10 may calculate the amount automatically. Further, the scales may be depicted to extend along a direction shown by the arrow 10b (see FIG. 1), or may be depicted to extend along a direction shown by the arrow 10c (see FIG. 1). Further, in the above, 5% is merely an example, so it may be other rates.

[0083] The inkjet printing system 10 automatically calibrates the displacement in the images to be printed on both sides of the medium 80 according to the amount of displacement of the front position mark 62 and the rear position mark 72 that has been calculated automatically. Therefore, convenience can be improved as compared to a configuration in which a suitable instruction for calibrating the displacement in the images to be printed on both sides of the medium 80 is manually inputted by the user based on the amount of displacement of the front position mark 62 and the rear position mark 72.

[0084] The inkjet printing system 10 may not automatically calibrate the displacement in the images to be printed on both sides of the medium 80, but may be configured such that the displacement in the images to be printed on both sides of the medium 80 is calibrated according to an instruction inputted by the user via the operation section 11 or the communication section 13. For example, the user can input the instruction for calibrating the displacement in the images to be printed on both sides of the medium 80 via the operation section 11 or the communication section 13 based on the amount of displacement between the front position mark 62 and the rear position mark 72 automatically calculated by the inkjet printing system 10 and displayed in the display section 12, or on the amount of displacement between the front position mark 62 and the rear position mark 72 that the user determined from the medium 80.

[0085] As the inkjet printing system 10 can simultaneously detect the front position mark 62 printed on the front surface 80a of the medium 80 and the rear position mark 72 printed on the rear surface 80b of the medium 80 from one surface side of the medium 80, the amount of displacement between the front position mark 62 and the rear position mark 72 can be detected highly accurately as compared to a configuration in which the front position mark 62 printed on the front surface 80a of the medium 80 and the rear position mark 72 printed on the rear surface 80b of the medium 80 are respectively detected from the front surface 80a side of the medium 80 and the rear surface 80b side of the medium 80. Thus, the inkjet printing system 10 can calibrate the displacement in the images to be printed on both sides of the medium 80 highly accurately, as a result of which the displacement in the images to be printed on both sides of the medium 80 can further be reduced.

[0086] In the case where the medium 80 is a thick cloth, the inkjet print system 10 can allow the front position mark 62 to be penetrated to the rear surface 80b of the medium 80 by printing the front position mark 62 on the front surface 80a of the medium 80 using ink in an amount large enough to soak into the inside of the medium 80. Further, if the medium 80 is formed of transparent or light color, or the thickness of the medium 80 is thin so that the medium 80 itself has some degree of transparency, the inkjet printing system 10 can allow the front position mark 62 to be penetrated to the rear surface 80b of the medium 80 by printing the front position mark 62 on the front surface 80a of the medium 80 by a dark color, even without having to print the front position mark 62 on the front surface 80a of the medium 80 by using ink in an amount large enough to soak into the inside of the medium 80. Furthermore, in the case where the medium 80 itself has a high transparency, the inkjet printing system 10 can allow the front position mark 62 to be penetrated to the rear surface 80b of the medium 80 by regularly printing the front position mark 62 on the front surface 80a of the medium 80.

[0087] The displacement amount calculating section 15c of the inkjet printing system 10 may calculate the amount of displacement between the front position mark 62 and the rear position mark 72 based on an average of plural detection results of the front position mark 62 and the rear position mark 72 by the front and rear image position detecting device 52. According to this configuration, the inkjet printing system 10 can improve the accuracy of the calibration of the displacement in the images to be printed on both sides of the medium 80 in a case where the amount of displacement of the front position mark 62 and the rear position mark 72 varies each time the detection of the front position mark 62 and the rear position mark 72 is performed by the front and rear image position detecting device 52. Accordingly, the inkjet printing system 10 can further reduce the displacement in the images to be printed on both sides of the medium 80.

[0088] The displacement calibrating section 15d of the inkjet printing system 10 adjusts the print control by the rear surface print controlling section 15b so that the displacement in the images to be printed on both sides of the medium 80 is calibrated in the present embodiment. However, to calibrate the displacement in the images to be printed on both sides of the medium 80, the displacement calibrating section 15d simply needs to control at least one of the print control by the front surface print controlling section 15a and the print control by the rear surface print controlling section 15b.

[0089] In the inkjet printing system 10, the target image and the front position mark are configured of separate images. However, in the inkjet printing system 10, the target image itself may be used as the front position mark, and the mirrored target image itself may be used as the rear position mark.

[0090] The inkjet printing system 10 in the present embodiment is configured to detect the front position mark 62 printed on the front surface 80a of the medium 80 by the front-side image position detecting device 51 from the rear surface 80b side of the medium 80. However, the front-side image position detecting device 51 may be configured to detect the front position mark 62 printed on the front surface 80a of the medium 80 from the front surface 80a side of the medium 80.

[0091] The inkjet printing system 10 in the present embodiment is configured to detect the front position mark 62 printed on the front surface 80a of the medium 80 and the rear position mark 72 printed on the rear surface 80b of the medium 80 by the front and rear image position detecting device 52 from the rear surface 80b side of the medium 80. However, the front and rear image position detecting device 52 may be configured to detect the front position mark 62 printed on the front surface 80a of the medium 80 and the rear position mark 72 printed on the rear surface 80b of the medium 80 from the front surface 80a side of the medium 80. Further, the front and rear image position detecting device 52 may be configured to detect the front position mark 62 printed on the front surface 80a of the medium 80 from the front surface 80a side of the medium 80 and the rear position mark 72 printed on the rear surface 80b of the medium 80 from the rear surface 80b side of the medium 80.

[0092] The inkjet printing system 10 in the present embodiment is provided with two inkjet printers, namely the front surface printer 20 and the rear surface printer 30. However, the inkjet printing system 10 may be configured by one inkjet printer including two inkjet heads: an inkjet head that performs printing on the front surface 80a of the medium 80 and an inkjet head that performs printing on the rear surface 80b of the medium 80, to the front surface 80a of which the printing has been performed by the former inkjet head.

REFERENCE SIGNS LIST

[0093] 

10: Inkjet Printing System

15a: Front Surface Print Controlling Section (First Print Controlling Section)

15b: Rear Surface Print Controlling Section (Second Print Controlling Section)

15c: Displacement Amount Calculating Section

15d: Displacement Calibrating Section

21: Front Surface Head (First Inkjet Head)

31: Rear Surface Head (Second Inkjet Head)

51: Front-Side Image Position Detecting Device (One-Side Image Detecting Section)

52: Front And Rear Image Position Detecting Device (Both-Side Image Detecting Section)

60: Image (Image Including First Image)

62: Front Position Mark (First Image)

70: Image (Image Including Second Image)

72: Rear Position Mark (Second Image)

80: Medium

80a: Front Surface (One Surface)

80b: Rear Surface (The Other Surface)

Claims

1. An inkjet printing system comprising:

a first inkjet head that performs printing on one surface of a medium;

a second inkjet head that performs printing on the other surface of the medium to which printing has been performed by the first inkjet head;

a first print controlling section that causes the first inkjet head to print an image including a fist image for print control adjustment;

a second print controlling section that causes the second inkjet head to print an image including a second image for print control adjustment; and

a displacement calibrating section that calibrates a displacement between the images to be printed on both sides of the medium,

wherein the displacement calibrating section calibrates the displacement between the images to be printed on both sides of the medium by adjusting at least one of print control by the first print controlling section and print control by the second print controlling section in accordance with an amount of displacement between the first image and the second image.

2. The inkjet printing system according to claim 1, further comprising:

a both-side image detecting section that detects the first image and the second image on the medium; and

a displacement amount calculating section that calculates the amount of displacement between the first image and the second image based on a detection result by the both-side image detecting section.

3. The inkjet printing system according to claim 2, wherein the both-side image detecting section detects the first image and the second image from one surface side of the medium.

4. The inkjet printing system according to claim 2 or 3, wherein the displacement calibrating section calibrates the displacement between the images to be printed on both sides of the medium according to the amount of displacement between the first image and the second image calculated by the displacement amount calculating section.

5. The inkjet printing system according to any one of claims 2 to 4, wherein the first print controlling section and the second print controlling section causes the first image and the second image to be printed in a state in which the both-side image detecting section can detect the first image and the second image from one surface side of the medium.

6. The inkjet printing system according to any one of claims 2 to 5, wherein the displacement amount calculating section calculates the amount of displacement between the first image and the second image based on an average of detection results from plural times of detection of the first image and the second image by the both-side image detecting section.

7. The inkjet printing system according to any one of claims 1 to 6, further comprising a one-side image detecting section that detects the first image on the medium that is before printing performed by the second inkjet head, wherein
the displacement calibrating section calibrates the displacement between the images to be printed on both sides of the medium by adjusting the print control by the second print controlling section according to a detection result of the one-side image detecting section.

Drawing