Printing device, printing system, and printing method

Abstract

To enable stable conveyance of a printing medium in a configuration in which the printing medium in which ink is ejected from a printing part horizontally sent out by a drive roller.SOLUTION: An angle θ491 around which a drive roller 491 winds a print medium M is smaller than an angle θ471 around which a drive roller 471 winds the print medium M, and the angle θ491 around which the print medium M is wound around the drive roller 491 is small. As a result, an inclination of the print medium M reaching the drive roller 491 is kept small. Further, a diameter R491 of the drive roller 491 is larger than a diameter R471 of the drive roller 471. By increasing the diameter R491 of the drive roller 491 in this way, although the winding angle θ491 of the print medium M by the drive roller 491 is small, an area where the drive roller 491 and the print medium M come into contact with each other can be secured, the rotation of the drive roller 491 can be reliably transmitted by the print medium M.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a technique for printing an image by ejecting ink from a printing unit while a print medium is transported by a drive roller. [Background technology]

[0002] In the printing device described in Patent Document 1, drive rollers are arranged on both sides of an inkjet head that ejects ink onto a printing medium from above, and the drive rollers transport the printing medium by rotating while wrapping the printing medium around them. In this way, the inkjet head ejects ink onto the printing medium transported between the two drive rollers, printing an image on the printing medium. This printing device also has built-in heaters, such as an under-heater and an after-heater, which dry the printing medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2017 / 138436 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a large amount of ink is ejected onto the print medium, it becomes difficult for the heater built into the printing device to sufficiently dry the print medium. Therefore, a system can be considered in which a drying device is provided separately from the printing device, and the printing medium discharged from the printing device is dried by the drying device. However, in such a system, of the two driving rollers arranged on both sides of the printing unit such as the inkjet head, the latter driving roller cannot secure an angle at which the print medium is wrapped around it.

[0005] That is, the print medium sent out from the downstream drive roller is transported from the printing device to the drying device. Therefore, it is preferable to be able to send out the print medium horizontally from the downstream drive roller. This is because when arranging a heater along the print medium in the drying device, the heater can be arranged horizontally without tilting, so the drying device can be configured compactly in the vertical direction. This situation can also occur in systems that perform processes other than drying (e.g., cutting). For this reason, the wrap angle of the print medium around the downstream drive roller cannot be increased, making it difficult for the drive roller to stably transport the print medium.

[0006] This invention has been developed in consideration of the above-mentioned problems, and aims to enable a printing medium to be stably transported by a drive roller in a configuration in which the printing medium onto which ink has been ejected from a printing unit is sent horizontally by the drive roller. [Means for solving the problem]

[0007] The printing device of the present invention includes a first drive roller and a second drive roller that rotate around the non-recording side of a long, strip-shaped printing medium having a recording side and a non-recording side opposite the recording side, and is equipped with a transport section that transports the printing medium from the second drive roller to the first drive roller, and a first printing section that ejects ink onto the recording side facing the recording side of the printing medium between the second drive roller and the first drive roller, wherein the first drive roller sends out the printing medium transported from the second drive roller horizontally with the recording side facing upward, the angle at which the first drive roller wraps the printing medium is smaller than the angle at which the second drive roller wraps the printing medium, the first drive roller is a suction roller that sucks in the printing medium, and the diameter of the first drive roller is larger than the diameter of the second drive roller.

[0008] The printing method of the present invention includes the steps of transporting a printing medium from a second drive roller to a first drive roller by a first drive roller and a second drive roller which rotate while wrapping the non-recording side of a long strip-shaped printing medium having a recording side and a non-recording side opposite the recording side, and ejecting ink onto the recording side from a first printing unit which faces the recording side of the printing medium between the second drive roller and the first drive roller, wherein the first drive roller sends out the printing medium transported from the second drive roller horizontally with the recording side facing upward, the angle at which the first drive roller wraps the printing medium is smaller than the angle at which the second drive roller wraps the printing medium, the first drive roller is a suction roller which sucks in the printing medium, and the diameter of the first drive roller is larger than the diameter of the second drive roller.

[0009] In the present invention (printing device and printing method) configured in this manner, an image is printed on the printing medium by ejecting ink from the printing unit onto the printing medium transported from the second drive roller to the first drive roller. The printing medium on which the image has been printed in this manner is sent out horizontally by the first drive roller. This allows a device (e.g., a drying device) that processes the printing medium conveyed from the printing device to be configured compactly in the vertical direction. In addition, the angle at which the first drive roller wraps the printing medium is smaller than the angle at which the second drive roller wraps the printing medium, and the wrapping angle of the printing medium around the first drive roller is kept small. In this way, the inclination of the printing medium reaching the first drive roller is kept small.

[0010] Moreover, in the present invention, the first drive roller is a suction roller. Therefore, the rotation of the first drive roller can be securely transmitted to the printing medium. Furthermore, the diameter of the first drive roller is larger than the diameter of the second drive roller. In this way, by increasing the diameter of the first drive roller, the contact area between the first drive roller and the printing medium can be secured, even though the winding angle of the printing medium around the first drive roller is small, and the rotation of the first drive roller can be more reliably transmitted to the printing medium. As a result, the printing medium can be stably fed by the first drive roller. Thus, in the present invention, in a configuration in which the printing medium on which ink has been ejected from the printing unit is fed horizontally by the drive roller, the printing medium can be stably transported by the drive roller.

[0011] The printing device may further include a second printing unit that ejects ink onto the recording surface of the printing medium transported to one side by the transport unit, and the transport unit further includes a third driving roller that is disposed on the other side opposite to the one side of the second driving roller and rotates while wrapping the printing medium, and transports the printing medium from the third driving roller to the second driving roller with the recording surface facing upward, and the second printing unit may be configured to face the recording surface of the printing medium between the third driving roller and the second driving roller. In this configuration, the printing medium on which an image has been printed by the second printing unit is transported by the second driving roller toward the first printing unit. At this time, since the wrapping angle of the printing medium around the second driving roller is large, the printing medium is stably transported by the second driving roller and heads toward the first printing unit. Therefore, the first printing unit can print an image by ejecting ink onto the printing medium transported stably in this manner. This makes it possible to stably print an image by the first printing unit on the printing medium on which an image has been printed by the second printing unit.

[0012] The printing device may also be configured so that the transport unit transports the printing medium transported from the second drive roller downward, then changes its direction of travel to the other side and transports it, thereby inverting the recording surface and non-recording surface of the printing medium upside down and transporting the printing medium from one side to the other side, and then transports the printing medium upward, then changes its direction of travel to one side, thereby again inverting the recording surface and non-recording surface of the printing medium upside down and transporting the printing medium from the other side to one side to the first drive roller, and the transport unit transports the printing medium from the second drive roller to the first drive roller only by rollers that contact the non-recording surface of the printing medium, and the first printing unit faces the recording surface that has been inverted upside down again by the transport unit and is facing upward.

[0013] In this configuration, the transport unit turns the print medium upside down twice from the second drive roller to the first drive roller, and the first print unit prints an image by ejecting ink onto the recording surface that faces upward after the two upside-down inversions. Therefore, a distance sufficient to perform two upside-down inversions is ensured between the printing by the second print unit and the printing by the first print unit, and the image can be printed by the first print unit in a state in which the image printed by the second print unit is somewhat dry. Therefore, it is possible to prevent the ink ejected from the second print unit from mixing with the ink ejected from the first print unit. Moreover, since there is no member that comes into contact with the recording surface of the print medium from the second drive roller to the first drive roller, the image printed by the second print unit is not disturbed. This allows the image printed by the first print unit to be printed while maintaining the image printed by the second print unit in good condition.

[0014] The printing device may be configured so that the first printing unit ejects white ink and the second printing unit ejects ink of a color other than white. In this configuration, the first printing unit can print a white background on the image printed by the second printing unit.

[0015] The printing device may be configured so that the second drive roller is a suction roller that sucks in the print medium. In this configuration, the second drive roller can more stably transport the print medium toward the first printing unit.

[0016] The printing device may further include a suction blower, a first connection portion connecting the suction blower and the first drive roller, and a second connection portion connecting the suction blower and the second drive roller, and the first drive roller and the second drive roller suck the non-recording side of the print medium with suction force generated by suction by the suction blower. In this configuration, the suction blower can be shared between the first drive roller and the second drive roller, simplifying the device configuration.

[0017] A printing system according to the present invention includes the above-mentioned printing device and a drying section that dries the print medium transported from the printing device, the drying section including an air blowing chamber having a plurality of nozzles arranged horizontally facing the print medium, and dries the print medium by injecting gas from the nozzles of the air blowing chamber onto the print medium. Therefore, in a configuration in which the print medium onto which ink has been ejected from the printing section is sent out horizontally by a drive roller, the print medium can be stably transported by the drive roller. Effect of the Invention

[0018] As described above, according to the present invention, in a configuration in which the print medium onto which ink has been ejected from the printing unit is fed horizontally by the drive roller, it is possible for the print medium to be stably transported by the drive roller. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a front view showing a schematic diagram of an example of a printing system according to the present invention. [Diagram 2] FIG. 2 is a front view showing a schematic diagram of a printing device included in the printing system shown in FIG. [Diagram 3] FIG. 4 is a diagram illustrating a suction mechanism provided for each driving roller, which is a suction roller. [Figure 4] FIG. 4 is a side view showing a schematic relationship between the printing medium and two drive rollers that support the printing medium on either side of a white printed portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] FIG. 1 is a front view showing a schematic example of a printing system according to the present invention. In FIG. 1 and the following figures, a horizontal direction X and a vertical direction Z are appropriately indicated. As shown in FIG. 1, the printing system 1 includes a printing device 3 and a drying device 6 arranged in the horizontal direction X. This printing system 1 transports a long strip-shaped printing medium M from a pay-out roll 11 to a take-up roll 12 in a roll-to-roll manner. The material of the printing medium M is a film such as OPP (oriented polypropylene) or PET (polyethylene terephthalate). However, the material of the printing medium M is not limited to a film, and may be paper or the like. Such a printing medium M is flexible. In the following description, the surface on which an image is printed of both sides of the printing medium M is appropriately referred to as the front surface M1, and the surface opposite to the front surface M1 is appropriately referred to as the back surface M2.

[0021] The printing device 3 prints an image on the surface M1 of the printing medium M by ejecting water-based ink by an inkjet method onto the surface M1 of the printing medium M being transported from the pay-out roll 11 to the take-up roll 12. The configuration of the printing device 3 will be described in detail later with reference to Figure 2 etc. The printing medium M on which the image has been printed in this manner is transported in the horizontal direction X from the printing device 3 towards the drying device 6.

[0022] The drying device 6 includes a drying furnace 60, and dries the printing medium M discharged from the printing device 3 as it is transported from the pay-out roll 11 to the take-up roll 12. The drying furnace 60 includes two upper blowing units 61u arranged in the horizontal direction X, two middle blowing units 61m arranged in the horizontal direction X below the upper blowing units 61u, and two lower blowing units 61l arranged in the horizontal direction X below the middle blowing units 61m.

[0023] The printing medium M discharged from the discharge port 312 of the printing device 3 passes through two upper-stage blowing units 61u in the horizontal direction X, and is then turned back toward the two middle-stage blowing units 61m by a pair of rollers 62. Next, the printing medium M passes through two middle-stage blowing units 61m in the horizontal direction X, and is then turned back toward the two lower-stage blowing units 61l by a pair of air turn bars 63. Furthermore, the printing medium M passes through two lower-stage blowing units 61l in the horizontal direction X, and is then discharged to the outside of the drying device 6.

[0024] The upper blowing unit 61u has two blowing chambers 64 arranged to sandwich the printing medium M passing in the horizontal direction X in the vertical direction Z. Each blowing chamber 64 has a plurality of nozzles 65 arranged in the horizontal direction X, and each nozzle 65 sprays hot air (gas at 60 degrees or higher) onto the printing medium M. In this way, the printing medium M is dried by the hot air sprayed from the nozzles 65 of these blowing chambers 64 while passing between the two blowing chambers 64 arranged above and below. Similarly to the upper blowing unit 61u, each of the middle blowing unit 61m and the lower blowing unit 61l has two blowing chambers 64 that sandwich the printing medium M in the vertical direction Z.

[0025] Incidentally, the specific configuration of the upper blower unit 61u is not limited to this example. For example, instead of the lower blower chamber 64 of the upper and lower blower chambers 64 of the upper blower unit 61u, multiple rollers arranged in the horizontal direction X may be provided. In this configuration, hot air can be sprayed onto the front surface M1 of the printing medium M from the upper blower chamber 64 while the back surface M2 of the printing medium M is supported from below by the multiple rollers.

[0026] Fig. 2 is a front view showing a schematic diagram of a printing device provided in the printing system of Fig. 1. In Fig. 2, one side X1 and the other side X2 of the horizontal direction X are appropriately shown. Here, the one side X1 is the side facing the drying device 6 from the printing device 3, and the other side X2 is the opposite side to the one side X1. The printing device 3 includes a housing 31, a color printing unit 32 arranged in the housing 31, a white printing unit 33 arranged above the color printing unit 32 in the housing 31, and a transport unit 4 that transports the printing medium M by a plurality of rollers arranged in the housing 31.

[0027] The color printing unit 32 has a plurality of (six) ejection heads 321 arranged in the traveling direction of the printing medium M (direction from the other side X2 to the one side X1) above the printing medium M transported by the transport unit 4. The plurality of ejection heads 321 have nozzles facing from above the surface M1 of the printing medium M passing below each of them, and eject color inks of different colors from the nozzles by an inkjet method. Here, color ink means ink other than white, and includes inks such as cyan, magenta, yellow, and black. In this way, the plurality of ejection heads 321 of the color printing unit 32 print a color image on the surface M1 of the printing medium M by ejecting color inks from above onto the surface M1 of the printing medium M passing below each of them.

[0028] The white printing unit 33 also has a single ejection head 331 arranged above the printing medium M transported by the transport unit 4. The ejection head 331 has nozzles facing from above the surface M1 of the printing medium M passing below it, and ejects white ink from the nozzles by an inkjet method. In this way, the ejection head 331 of the white printing unit 33 prints a white image on the surface M1 of the printing medium M by ejecting white ink from above onto the surface M1 of the printing medium M passing below it.

[0029] An inlet 311 opens in the side wall of the other side X2 of the housing 31, and the print medium M is carried into the housing 31 through the inlet 311. In contrast, the transport unit 4 has an inlet section 41. The inlet section 41 has a plurality of rollers 411 arranged below the color printing unit 32 from the other side X2 to the one side X1 in the horizontal direction X, and transports the print medium M carried in through the inlet 311 from the other side X2 to the one side X1 while supporting it with the plurality of rollers 411.

[0030] The transport section 4 also has an upward transport section 42 provided on one side X1 of the carry-in section 41. The upward transport section 42 has a plurality of rollers 421 arranged in the vertical direction Z outside (one side X1) of the color printing section 32. The upward transport section 42 bends the print medium M transported from the carry-in section 41 upward with the roller 421 located at the bottom end of the plurality of rollers 421, thereby changing the traveling direction of the print medium M from the one side X1 to the upward direction, and then transports the print medium M upward while being supported by the plurality of rollers 421.

[0031] Furthermore, the transport unit 4 has an upper transport unit 43 provided above the color printing unit 32. The upper transport unit 43 has a plurality of rollers 431 arranged above the color printing unit 32 from one side X1 to the other side X2 in the horizontal direction X. The upper transport unit 43 bends the printing medium M transported from the upward transport unit 42 to the other side X2 by a roller 431 located at the end of the one side X1 among the plurality of rollers 431, thereby changing the traveling direction of the printing medium M from the upper side to the other side X2, and then transports the printing medium M to the other side X2 while being supported by the plurality of rollers 431.

[0032] The conveying section 4 also has a downward conveying section 44 provided on the other side X2 of the upper conveying section 43. The downward conveying section 44 has a plurality of rollers 441 arranged in the vertical direction Z on the outside (the other side X2) of the color printing section 32. The downward conveying section 44 bends the print medium M conveyed from the upper conveying section 43 downward by the roller 441 located at the upper end of the plurality of rollers 441, thereby changing the traveling direction of the print medium M from the other side X2 to the lower side, and then conveys the print medium M downward while supporting it with the roller 441. Of the plurality of rollers 441 that the downward conveying section 44 has, the upper end roller 441 is located above each ejection head 321 of the color printing section 32, and the lower end roller 441 is located below each ejection head 321 of the color printing section 32. In other words, the downward conveying section 44 conveys the print medium M from above the color printing section 32 downward.

[0033] Furthermore, the transport section 4 has a color transport section 45 provided below the upper transport section 43 and on one side X1 of the downward transport section 44. The color transport section 45 has a plurality of rollers 451 arranged from the other side X2 to the one side X1 in the horizontal direction X and contacting the back surface M2 of the printing medium M, and the printing medium M transported from the downward transport section 44 is supported below the color printing section 32 by the plurality of rollers 451. In this way, the plurality of rollers 451 of the color transport section 45 transport the printing medium M from the other side X2 to the one side X1 while supporting the printing medium M from below by contacting the back surface M2 of the printing medium M transported from the downward transport section 44 from below. Then, the color printing section 32 ejects color inks from above onto the front surface M1 of the printing medium M transported along its front surface M1 by the color transport section 45.

[0034] At this time, the front surface M1 of the printing medium M transported by the color transport section 45 faces upward, and the back surface M2 of the printing medium M faces downward. In detail, the printing medium M is transported from the entrance 311 with its front surface M1 facing upward, and is transported by the transport section 41 from the other side X2 to the one side X1. The printing medium M that has passed through the transport section 41 is transported by the upper transport section 43 from the one side X1 to the other side X2 in a state in which it is turned upside down by the upward transport section 42 and the upper transport section 43. Therefore, the front surface M1 of the printing medium M transported by the upper transport section 43 faces downward. The printing medium M that has passed through the upper transport section 43 is transported by the color transport section 45 from the other side X2 to the one side X1 in a state in which it is turned upside down by the downward transport section 44 and the color transport section 45. Therefore, the front surface M1 of the printing medium M transported by the color transport section 45 faces upward.

[0035] The transport unit 4 also has rollers 461, 462, and 463 arranged upstream of the color transport unit 45 in the traveling direction of the printing medium M. The roller 461 is a drive roller that drives the printing medium M by rotating by the driving force of a motor while wrapping the front surface M1 of the printing medium M around it. The roller 462 is a nip roller that presses the printing medium M against the roller 461 by sandwiching the printing medium M between the roller 462 and the roller 461. The roller 463 is a driven roller that has a tension sensor that detects the tension applied to the printing medium M, and wraps the back surface M2 of the printing medium M transported from the drive roller 461 around it. The drive roller 461 and the driven roller 463 function to adjust the tension of the printing medium M, as described below.

[0036] Furthermore, the conveying section 4 has a reversing conveying section 47 that turns upside down the printing medium M conveyed from the color conveying section 45 to the one side X1 twice. The reversing conveying section 47 has a plurality of rollers 471, 472 that are arranged in the vertical direction Z on the one side X1 of the color conveying section 45 and contact the back surface M2 of the printing medium M. Of the rollers 471, 472, the upper end roller 471 is a driving roller that drives the printing medium M by rotating by the driving force of a motor while wrapping the back surface M2 of the printing medium M around it. The driving roller 471 bends the printing medium M conveyed from the color conveying section 45 downward, thereby changing the traveling direction of the printing medium M from the one side X1 to the downward side. Of the rollers 471, 472, the lower end roller 472 is a driven roller having a tension sensor that detects the tension applied to the printing medium M, and wraps the back surface M2 of the printing medium M around it. This driven roller 472 bends the printing medium M conveyed from the driving roller 471 to the other side X2, thereby changing the traveling direction of the printing medium M from the downward side to the other side X2. In this way, the printing medium M is turned upside down by the rollers 471, 472 contacting the back surface M2 of the printing medium M, so that the back surface M2 of the printing medium M faces upward and the front surface M1 of the printing medium M faces downward. The driving roller 471 and roller 472 function to adjust the tension of the printing medium M, as described below.

[0037] The reverse conveying section 47 also has a plurality of rollers 473 provided below the color conveying section 45 and on the other side X2 of the rollers 472. The plurality of rollers 473 are arranged from one side X1 to the other side X2 in the horizontal direction X, and contact the back surface M2 of the printing medium M. In this way, the printing medium M with the back surface M2 facing upward is conveyed from the one side X1 to the other side X2 by the plurality of rollers 473 contacting the back surface M2 of the printing medium M.

[0038] Furthermore, the reverse conveying section 47 has a plurality of rollers 473 and a plurality of rollers 474, 475, 476 provided on the other side X2 of the downward conveying section 44. These rollers 474 to 476 are arranged from the lower side to the upper side in the vertical direction Z, and contact the rear surface M2 of the printing medium M. Of the plurality of rollers 474 to 476, the lowermost roller 474 bends the printing medium M conveyed from the plurality of rollers 473 upward, thereby changing the traveling direction of the printing medium M from the other side X2 to the upper side, and the uppermost roller 476 bends the printing medium M conveyed from the roller 474 via the roller 475 to the one side X1, thereby changing the traveling direction of the printing medium M from the upper side to the one side X1. In this manner, the printing medium M is turned upside down by the rollers 474-476 in contact with the back surface M2 of the printing medium M, so that the front surface M1 of the printing medium M faces upward and the back surface M2 of the printing medium M faces downward.

[0039] The reverse conveying section 47 also has a roller 477 that is disposed above the upper conveying section 43 and on one side X1 of the roller 476 and that comes into contact with the back surface M2 of the printing medium M. The roller 477 conveys the printing medium M conveyed from the roller 476 from the other side X2 to the one side X1. In this way, the printing medium M with the front surface M1 facing upward is conveyed from the other side X2 to the one side X1 by the roller 477 that comes into contact with the back surface M2 of the printing medium M.

[0040] In this way, the reverse conveying section 47 conveys the printing medium M conveyed from the color conveying section 45 in a downward direction by the rollers 471 and 472, and further changes the traveling direction of the printing medium M to the other side X2 by the roller 472 and conveys the printing medium M, thereby inverting the front surface M1 and the back surface M2 of the printing medium M upside down. Next, the reverse conveying section 47 conveys the printing medium M from the one side X1 to the other side X2 by the multiple rollers 473, and then conveys the printing medium M in an upward direction by the rollers 474 to 476. Furthermore, the reverse conveying section 47 changes the traveling direction of the printing medium M to the one side X1 by the roller 476, thereby again inverting the front surface M1 and the back surface M2 of the printing medium M upside down, and conveys the printing medium M from the other side X2 to the one side X1 by the roller 477.

[0041] In this way, the reverse transport unit 47 turns the front surface M1 and back surface M2 of the printing medium M upside down twice using only the rollers 471-477 which contact the back surface M2 of the printing medium M and rotate while wrapping the back surface M2 around it. That is, the reverse transport unit 47 can turn the front surface M1 and back surface M2 of the printing medium M upside down twice without providing any support members such as rollers or air turn bars on the front surface M1 side of the printing medium M.

[0042] The conveying section 4 also has a white conveying section 48 provided above the upper conveying section 43 and on one side X1 of the rollers 477 of the reverse conveying section 47. The white conveying section 48 has rollers 481, and the printing medium M conveyed from the rollers 477 of the reverse conveying section 47 is supported below the white printed section 33 by the rollers 481. In this manner, the rollers 481 of the white conveying section 48 contact the back surface M2 of the printing medium M conveyed from the rollers 477 of the reverse conveying section 47 from below, thereby supporting the printing medium M from below, and conveying the printing medium M from the other side X2 to the one side X1. Then, the white printed section 33 ejects white ink from above onto the front surface M1 of the printing medium M conveyed along the front surface M1 by the white conveying section 48.

[0043] Furthermore, the transport section 4 has an unloading section 49 provided above the upper transport section 43 and on one side X1 of the white transport section 48. The unloading section 49 has a plurality of rollers 491, 492, 493 arranged from the other side X2 to the one side X1 of the horizontal direction X. The upper ends of these rollers 491 to 493 are aligned parallel to the horizontal direction X and contact the back surface M2 of the printing medium M. These rollers 491 to 493 transport the printing medium M horizontally from the other side X2 to the one side X1 of the horizontal direction X. In particular, the driving roller 491 is a driving roller that drives the printing medium M by rotating by the driving force of the motor while wrapping the back surface M2 of the printing medium M transported from the roller 481 around it. Meanwhile, an unloading opening 312 is opened in the side wall of the one side X1 of the housing 31. Therefore, the printing medium M is transported parallel to the horizontal direction X by the unloading section 49 and unloaded from the unloading opening 312.

[0044] In this way, the conveying section 4 does not have a support member on the front surface M1 side of the printing medium M, which supports the printing medium M that enters the color conveying section 45 and then is turned upside down twice to reach the discharge outlet 312, but only on the back surface M2 side of the printing medium M.

[0045] The printing device 3 also includes a pre-drying section 34 disposed in the housing 31. The pre-drying section 34 is disposed between the carry-in section 41 and the reverse conveying section 47 in the vertical direction Z. The pre-drying section 34 has a plurality of nozzles 341 arranged in the traveling direction of the printing medium M conveyed from one side X1 to the other side X2 by a plurality of rollers 473 of the reverse conveying section 47. Each nozzle 341 faces the surface M1 of the printing medium M conveyed by the plurality of rollers 473 from below, and sprays room temperature air from below onto the surface M1 of the printing medium M. That is, the surface M1 of the printing medium M onto which the color inks are ejected from the color printing section 32 is dried by the pre-drying section 34. The pre-drying section 34 is not necessarily limited to being disposed between the carry-in section 41 and the reverse conveying section 47, and the position at which the pre-drying section 34 is disposed is not limited as long as it can adopt a positional relationship in which air can be sprayed onto the surface M1 of the printing medium M conveyed by the reverse conveying section 47. That is, the pre-drying unit 34 can be arranged so that after color inks are ejected onto the surface of the printing medium M in the color printing unit 32, air can be sprayed onto the surface M1 of the printing medium M before the white printing unit 33 ejects white ink onto the surface M1 of the printing medium M. However, if the pre-drying unit 34 is arranged between the carry-in unit 41 and the reversing and conveying unit 47, the space below the reversing and conveying unit 47 can be utilized as an arrangement space for the pre-drying unit, which has the advantage of making the printing device smaller in the horizontal direction.

[0046] Furthermore, the printing device 3 includes an upper drying unit 35 disposed within the housing 31. The upper drying unit 35 is disposed above the discharge unit 49. This upper drying unit 35 has a plurality of nozzles 351 arranged in the traveling direction of the printing medium M transported from the other side X2 to the one side X1 by the discharge unit 49. Each nozzle 351 faces from above the surface M1 of the printing medium M transported by the discharge unit 49, and sprays room temperature air from above onto the surface M1 of the printing medium M. In other words, the surface M1 of the printing medium M onto which the white ink has been ejected from the white printing unit 33 is dried by the upper drying unit 35.

[0047] As described above, the transport unit 4 has three drive rollers 461, 471, and 491, and the printing medium M is transported in this order. In addition, each ejection head 321 of the color printing unit 32 faces the printing medium M between the drive roller 461 and the drive roller 471 from above, and each ejection head 321 ejects ink onto the front surface M1 of the printing medium M transported from the drive roller 461 on the other side X2 to the drive roller 471 on the one side X1. Furthermore, the front surface M1 and the back surface M2 of the printing medium M are turned upside down twice between the drive roller 471 and the drive roller 491, and the front surface M1 of the printing medium M before reaching the drive roller 491 faces upward. In this way, the ejection head 331 of the white printing unit 33 faces the front surface M1 of the printing medium M facing upward between the drive roller 471 and the drive roller 491 from above. Then, the ejection head 331 ejects ink onto the surface M1 of the print medium M that is transported from the drive roller 471 to the drive roller 491.

[0048] At this time, the drive rollers 461, 471, 491 each rotate at a speed according to the tension of the printing medium M detected by the tension sensors of the driven rollers 463, 472, respectively, thereby adjusting the tension of the printing medium M transported by the transport unit 4 to a predetermined target tension throughout. This makes it possible to apply an appropriate tension to the printing medium M while ejecting the color inks and white ink onto the printing medium M.

[0049] Further, the drive roller 471 and the drive roller 491 are suction rollers that suck the print medium M. As a result, the drive rollers 471, 491 can accurately transmit rotation to the print medium M by suction force, thereby driving the print medium M. In response to this, the transport unit 4 has a suction mechanism for sucking the inside of each of the drive rollers 471, 491 (FIG. 3).

[0050] 3 is a diagram showing a schematic diagram of a suction mechanism provided for each driving roller, which is a suction roller. The suction mechanism 5 has a suction blower 51, a common pipe 52 attached to the suction blower 51, a branch pipe 53 connecting the common pipe 52 and the driving roller 471, and a branch pipe 54 connecting the common pipe 52 and the driving roller 491.

[0051] When the suction blower 51 sucks the common pipe 52, the inside of the drive roller 471 (suction roller) is sucked through the branch pipe 53. As a result, negative pressure is applied to a plurality of suction holes opening in the circumferential surface of the drive roller 471, and the print medium M is sucked into the drive roller 471 by a suction force generated on the circumferential surface of the drive roller 471 by this negative pressure.

[0052] Similarly, when the suction blower 51 sucks the common pipe 52, the inside of the drive roller 491 (suction roller) is sucked through the branch pipe 54. As a result, negative pressure is applied to the multiple suction holes opening in the circumferential surface of the drive roller 491, and the print medium M is sucked into the drive roller 491 by the suction force generated on the circumferential surface of the drive roller 491 by this negative pressure.

[0053] Fig. 4 is a side view showing a schematic relationship between the printing medium M and two drive rollers that support the printing medium M on either side of the white printed portion. As shown in the "previous drive roller 471" column in Fig. 4, the drive roller 471 wraps the printing medium M at a wrap angle θ471 while contacting the back surface M2 of the printing medium M. Here, the wrap angle θ471 is the angle that the contact range between the circumferential surface of the drive roller 471 and the printing medium M forms around the rotation axis of the drive roller 471 when viewed from the direction in which the rotation axis of the drive roller 471 extends (a direction perpendicular to the vertical direction Z and the horizontal direction X). This drive roller 471 has a radius R471.

[0054] 4, the drive roller 491 wraps the printing medium M at a wrap angle θ491 while in contact with the rear surface M2 of the printing medium M. Here, the wrap angle θ491 is the angle that the contact area between the circumferential surface of the drive roller 491 and the printing medium M forms around the rotation axis of the drive roller 491 when viewed from the direction in which the rotation axis of the drive roller 491 extends (a direction perpendicular to the vertical direction Z and the horizontal direction X). This drive roller 491 has a radius R491.

[0055] 4, the wrap angle θ491 of the drive roller 491 with respect to the printing medium M is smaller than the wrap angle θ471 of the drive roller 471 with respect to the printing medium M. For example, the wrap angle θ471 is approximately 39 degrees, while the wrap angle θ491 is 12 degrees to 14 degrees, and the wrap angle θ491 can be set to ½ or less or ⅓ or less of the wrap angle θ471.

[0056] As described above, the ejection head 331 is the last of the multiple ejection heads 321, 331 provided in the printing device 3 to eject ink onto the printing medium M. The printing medium M onto which the ink has been ejected from the ejection head 331 is discharged from the discharge port 312 by the drive roller 491. In other words, the ejection head 331 is the ejection head of the multiple ejection heads 321, 331 that ejects ink onto the printing medium M just before the drive roller 491. In contrast, by reducing the wrap angle θ491, the inclination of the printing medium M before and after the drive roller 491 is suppressed. As a result, it is possible to suppress the inclination of the ejection head 331 just before the drive roller 491 while feeding the printing medium M horizontally from the drive roller 491.

[0057] In other words, the drive roller 491 sends out the printing medium M parallel to the horizontal direction X towards the discharge port 312. In this way, the printing medium M reaching the discharge port 312 from the drive roller 491 is kept parallel to the horizontal direction X. Meanwhile, because the wrap angle θ491 of the drive roller 491 with respect to the printing medium M is small, the inclination of the printing medium M with respect to the horizontal direction X immediately before reaching the drive roller 491 is small. Therefore, the inclination of the ejection head 331 facing this printing medium M can also be kept small. As a result, the inclination of the ink ejection direction from the ejection head 331 to the printing medium M with respect to the vertical direction Z can be kept small.

[0058] On the other hand, the diameter R491 of the drive roller 491 is larger than the diameter R471 of the drive roller 471. For example, the diameter R491 is 300 mm, while the diameter R471 is 150 mm, so that the diameter R491 can be more than twice the diameter R471. In this way, by using the drive roller 491 with a large diameter R491, it is possible to ensure a contact area between the drive roller 491 and the printing medium M, even though the winding angle θ491 of the drive roller 491 is small.

[0059] In the printing device 3 described above, an image is printed on the printing medium M by ejecting ink from the white printing section 33 (first printing section) onto the printing medium M transported from the drive roller 471 (second drive roller) to the drive roller 491 (first drive roller). The printing medium M on which the image has been printed is sent horizontally toward the discharge port 312 by the drive roller 491. Therefore, a device (e.g., the drying device 6) that processes the printing medium M discharged from the printing device 3 can be configured compactly in the vertical direction Z. In addition, the angle θ491 at which the driving roller 491 wraps the printing medium M is smaller than the angle θ471 at which the driving roller 471 wraps the printing medium M, and the wrap angle θ491 of the printing medium M around the drive roller 491 is small. This keeps the inclination of the printing medium M to the drive roller 491 small. As a result, the ink ejection surface of the white printed area 33 facing the printing medium M can be kept nearly horizontal, and problems such as ink flowing down the ink ejection surface of the white printed area 33 and solidifying within the ink ejection surface can be suppressed.

[0060] Moreover, the driving roller 491 is a suction roller. Therefore, the rotation of the driving roller 491 can be securely transmitted to the printing medium M. Furthermore, the diameter R491 of the driving roller 491 is larger than the diameter R471 of the driving roller 471. In this way, by increasing the diameter R491 of the driving roller 491, even though the winding angle θ491 of the printing medium M by the driving roller 491 is small, the contact area between the driving roller 491 and the printing medium M can be secured, and the rotation of the driving roller 491 can be more reliably transmitted to the printing medium M. As a result, the printing medium M can be stably fed by the driving roller 491. In this way, in the configuration in which the printing medium M on which ink has been ejected from the white printing portion 33 is fed horizontally by the driving roller 491, in this embodiment, the printing medium M can be stably transported by the driving roller 491.

[0061] The transport unit 4 also includes a color printing unit 32 (second printing unit) that faces the surface M1 (recording surface) of the printing medium M transported to the one side X1 by the transport unit 4 and ejects ink onto the surface M1. The transport unit 4 has a drive roller 461 (third drive roller) arranged on the other side X2 of the drive roller 471, and the drive roller 461 rotates with the printing medium M wrapped around it. The printing medium M is transported from the drive roller 461 to the drive roller 471 with the surface M1 facing upward, and the color printing unit 32 faces the surface M1 of the printing medium M between the drive roller 461 and the drive roller 471. In this configuration, the printing medium M on which an image has been printed by the color printing unit 32 is transported toward the white printing unit 33 by the drive roller 471. At this time, since the wrap angle θ471 of the printing medium M around the drive roller 471 is large, the printing medium M is stably transported by the drive roller 471 toward the white printing unit 33. Therefore, the white printing unit 33 can print an image by ejecting ink onto the print medium M that is transported stably in this manner. This allows the white printing unit 33 to stably print an image onto the print medium M on which an image has been printed by the color printing unit 32.

[0062] In addition, the carry-in unit 41 turns the print medium M upside down twice from the drive roller 471 to the drive roller 491, and the white printing unit 33 prints an image by ejecting ink onto the surface M1 that faces upward after the two upside-down inversions. Therefore, a distance sufficient for two upside-down inversions is secured between the printing by the color printing unit 32 and the printing by the white printing unit 33, and the image printing by the white printing unit 33 can be performed in a state in which the image printed by the color printing unit 32 is somewhat dried. Therefore, it is possible to prevent the ink ejected from the color printing unit 32 from mixing with the ink ejected from the white printing unit 33. Moreover, since there is no member that comes into contact with the surface M1 of the print medium M from the drive roller 471 to the drive roller 491, the image printed by the color printing unit 32 is not disturbed. As a result, the image printing by the white printing unit 33 can be performed while maintaining the image printed by the color printing unit 32 in good condition.

[0063] In addition, the white printing unit 33 ejects white ink, and the color printing unit 32 ejects ink of a color different from white. In this configuration, the white printing unit 33 can print a white background on the image printed by the color printing unit 32.

[0064] Furthermore, the drive roller 471 is a suction roller that sucks the print medium M. In this configuration, the drive roller 471 can transport the print medium M toward the white printed area 33 more stably.

[0065] The printing device 3 also includes a suction mechanism 5 that sucks the drive roller 471 and the drive roller 491. The suction mechanism 5 includes a suction blower 51, a common pipe 52 and a branch pipe 54 (first connection part) that connect the suction blower 51 and the drive roller 491, and a branch pipe 53 and a common pipe 52 (second connection part) that connect the suction blower 51 and the drive roller 471. The drive roller 491 and the drive roller 471 suck the back surface M2 of the printing medium M by a suction force generated by the suction blower 51. In this way, the suction blower 51 can be shared by the drive roller 491 and the drive roller 471, and the configuration of the printing device 3 is simplified.

[0066] In the embodiment described above, the printing system 1 corresponds to an example of the "printing system" of the present invention, the printing device 3 corresponds to an example of the "printing device" of the present invention, the color printing unit 32 corresponds to an example of the "second printing unit" of the present invention, the white printing unit 33 corresponds to an example of the "first printing unit" of the present invention, the transport unit 4 corresponds to an example of the "transport unit" of the present invention, the drive roller 461 corresponds to an example of the "third drive roller" of the present invention, the drive roller 471 corresponds to an example of the "second drive roller" of the present invention, the drive roller 491 corresponds to an example of the "first drive roller" of the present invention, and the suction blower 51 corresponds to an example of the "suction blower" of the present invention. the common pipe 52 and the branch pipe 54 correspond to an example of a "first connection part" of the present invention, the common pipe 52 and the branch pipe 53 correspond to an example of a "second connection part" of the present invention, the drying device 6 corresponds to an example of a "drying section" of the present invention, the air blowing chamber 64 corresponds to an example of an "air blowing chamber" of the present invention, the printing medium M corresponds to an example of a "printing medium" of the present invention, the front surface M1 corresponds to an example of a "recording surface" of the present invention, the back surface M2 corresponds to an example of a "non-recording surface" of the present invention, one side X1 corresponds to an example of a "one side" of the present invention, and the other side X2 corresponds to an example of a "other side" of the present invention.

[0067] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the ink ejected from the ejection head 331 immediately before the drive roller 491 that ejects the printing medium M from the printing device 3 is not limited to white ink.

[0068] Furthermore, the specific configuration for transporting the printing medium M from the driving roller 471 to the driving roller 491 is not limited to the above example. Therefore, it is not essential to perform the upside-down inversion of the printing medium M twice between the driving roller 471 and the driving roller 491.

[0069] Also, the drive roller 471 does not have to be a suction roller.

[0070] Furthermore, the type of ink ejected by the printing device 3 is not limited to water-based ink.

[0071] Furthermore, the process performed on the print medium M discharged from the printing device 3 is not limited to drying by the drying device 6. [Industrial Applicability]

[0072] The present invention can be applied to all printing devices that eject ink onto a print medium M using an inkjet method. [Explanation of symbols]

[0073] 1. Printing system 3...Printing device 32…Color printing section (second printing section) 33…White printing section (1st printing section) 4. Conveyor section 461...Drive roller (third drive roller) 471...Drive roller (second drive roller) 491...Drive roller (first drive roller) 51...Suction blower 52...Common piping (first connection, second connection) 53...Branch piping (second connection) 54...Branch pipe (first connection) 6...Drying device (drying section) 64…Blower chamber M…Print media M1: Surface (recording surface) M2: Back side (non-recording side) X1…One side X2: Other side

Claims

1. a conveying section including a first driving roller and a second driving roller that rotate around a non-recording surface of a long strip-shaped print medium having a recording surface and a non-recording surface opposite to the recording surface, and that conveys the print medium from the second driving roller to the first driving roller; a first printing unit that faces the recording surface of the print medium between the second driving roller and the first driving roller and ejects ink onto the recording surface; a second printing unit that faces the recording surface of the print medium transported to one side by the transport unit and ejects ink onto the recording surface; Equipped with the first drive roller horizontally sends out the print medium conveyed from the second drive roller with the recording surface facing upward; an angle at which the first drive roller wraps the print medium is smaller than an angle at which the second drive roller wraps the print medium; the first drive roller is a suction roller that attracts the print medium, The diameter of the first drive roller is larger than the diameter of the second drive roller, the transport section further includes a third drive roller that is disposed on the other side of the second drive roller opposite to the one side and rotates around the print medium, and transports the print medium from the third drive roller to the second drive roller with the recording surface facing upward; the second printing unit faces the recording surface of the print medium between the third drive roller and the second drive roller, the transport unit transports the print medium transported from the second drive roller in a downward direction, then changes its traveling direction to the other side and transports the print medium, thereby inverting the recording surface and the non-recording surface of the print medium upside down and transporting the print medium from the one side to the other side, then transports the print medium in an upward direction, then changes its traveling direction to the one side, thereby performing an operation of inverting the recording surface and the non-recording surface of the print medium upside down again and transporting the print medium from the other side to the one side to the first drive roller, the transport unit transports the print medium from the second drive roller to the first drive roller only by rollers that contact the non-recording surface of the print medium; The first printing unit faces the recording surface that faces upward as a result of the operation of being turned upside down again by the transport unit.

2. The printing device according to claim 1 , wherein the first printing unit ejects white ink, and the second printing unit ejects ink of a color different from white.

3. 3. The printing apparatus according to claim 1, wherein the second drive roller is a suction roller that sucks the printing medium.

4. A suction blower; a first connection portion that connects the suction blower and the first drive roller; a second connection portion that connects the suction blower and the second drive roller; Further equipped with The printing apparatus according to claim 3 , wherein the first drive roller and the second drive roller suck the non-recording surface of the print medium by a suction force generated by the suction blower.

5. A printing device according to any one of claims 1 to 4, a drying unit that dries the print medium transported from the printing device; Equipped with The drying section is a printing system that includes an air blowing chamber having a plurality of nozzles arranged horizontally and facing the printing medium, and dries the printing medium by spraying gas from the nozzles of the air blowing chamber onto the printing medium.

6. A step of transporting a long strip-shaped print medium having a recording surface and a non-recording surface opposite to the recording surface from the second drive roller to the first drive roller by a transport unit including a first drive roller and a second drive roller that rotate around the non-recording surface of the print medium; ejecting ink onto the recording surface from a first printing unit facing the recording surface of the print medium between the second drive roller and the first drive roller; a step of transporting the print medium from the third drive roller to the second drive roller with the print medium facing upward by the transport unit further including a third drive roller arranged on the other side opposite to the one side of the second drive roller and rotating around the print medium; a step in which a second printing unit facing the recording surface of the print medium between the third drive roller and the second drive roller faces the recording surface of the print medium transported to the one side by the transport unit and ejects ink onto the recording surface; Equipped with the first drive roller horizontally sends out the print medium conveyed from the second drive roller with the recording surface facing upward; an angle at which the first drive roller wraps the print medium is smaller than an angle at which the second drive roller wraps the print medium; the first drive roller is a suction roller that attracts the print medium, The diameter of the first drive roller is larger than the diameter of the second drive roller, the transport unit transports the print medium transported from the second drive roller in a downward direction, then changes its traveling direction to the other side and transports the print medium, thereby inverting the recording surface and the non-recording surface of the print medium upside down and transporting the print medium from the one side to the other side, then transports the print medium in an upward direction, then changes its traveling direction to the one side, thereby performing an operation of inverting the recording surface and the non-recording surface of the print medium upside down again and transporting the print medium from the other side to the one side to the first drive roller, the transport unit transports the print medium from the second drive roller to the first drive roller only by rollers that contact the non-recording surface of the print medium; The printing method, wherein the first printing unit faces the recording surface that faces upward as a result of the operation of being turned upside down again by the transport unit.

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