Dryer, printing system, and drying method

Abstract

To stably transport a printing medium in a section from a front stage rotor between upper and middle stage transport parts to a rear stage rotor after a lower stage transport part, upon drying the printing medium while transporting the printing medium so as to pass through the upper, middle and lower stage transport parts in order.SOLUTION: A printing medium M to be transported between a roller 522 (front stage rotator) and a roller 561 (rear stage rotator) is supported by a roller 74 (intermediate rotor) of a lower stage transport unit 51l rotating while contacting a back surface M2 (non-printing surface) of a printing medium M. Therefore, the printing medium M can be stably transported in a section from the roller 522 between an upper stage transport part 51u and a middle stage transport part 51m to the roller 561 after the lower stage transport part 51l.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technique for drying a print medium having ink attached thereto by using hot air. [Background technology]

[0002] Patent Document 1 discloses a drying device that dries ink-covered print media by spraying gas from nozzles onto the print media. This drying device, in particular, has three vertically arranged transport sections. Each transport section transports the print media horizontally, with the print media passing through the upper transport section, middle transport section, and lower transport section in that order. Specifically, the upper transport section transports the print medium to one side, the middle transport section located below the upper transport section transports the print medium to the other side, and the lower transport section located below the middle transport section transports the print medium to one side. Each transport section has multiple nozzles arranged along the print medium, above and below the print medium, and sprays gas from these nozzles. This allows the print medium to be dried while being transported without contacting the print medium.

[0003] Furthermore, two rollers are arranged vertically between the upper conveying section and the middle conveying section, and the print medium conveyed from the upper conveying section to one side is folded downward by the upper roller, then folded back to the other side by the lower roller, before proceeding to the middle conveying section. Two air turn bars are arranged vertically between the middle conveying section and the lower conveying section, and the print medium conveyed from the middle conveying section to the other side is folded downward by the upper air turn bar, then folded back to one side by the lower air turn bar, before proceeding to the lower conveying section. Furthermore, rollers are arranged downstream of the lower conveying section (in other words, downstream in the conveying direction of the print medium), and the print medium conveyed from the lower conveying section to one side is supported by the rollers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-148383 Summary of the Invention [Problem to be solved by the invention]

[0005] In this drying device, the print medium is transported by floating transport between the front rotating body (roller) located between the upper and middle transport sections and the rear rotating body (roller) located after the lower transport section, so there are no parts that come into contact with the print medium. As a result, the print medium is not transported straight in this section, and there are cases where the print medium is biased in the width direction or falls off the nozzles.

[0006] This invention has been made in consideration of the above-mentioned problems, and aims to stably transport the printing medium in the section from the front rotating body between the upper and middle conveying sections to the rear rotating body after the lower conveying section when drying the printing medium while transporting the printing medium so that it passes through the upper, middle, and lower conveying sections in sequence. [Means for solving the problem]

[0007] The drying device according to the present invention includes an upper transport section having a plurality of upper print surface nozzles arranged above a long strip-shaped print medium having a print surface with ink attached and a non-print surface opposite the print surface, and transporting the print medium to one side in a horizontal direction with the print surface facing up while spraying gas onto the print surface from the upper print surface nozzles; a front turn section having a front rotor that rotates while contacting the non-print surface of the print medium, and folding the print medium transported from the upper transport section to the other side opposite the one side by the front rotor; and a middle turn section having a plurality of middle print surface nozzles arranged below the print medium, and transporting the print medium folded to the other side by the front rotor with the print surface facing down while spraying gas onto the print surface from the middle print surface nozzles. The printing system includes a conveying unit, a rear-stage folding unit that has a non-contact support member that supports the printing medium by spraying gas onto the printing surface of the printing medium, and that folds the printing medium conveyed from the middle-stage conveying unit downward using the non-contact support member and then folds it back to one side, a lower-stage conveying unit that has a plurality of lower-stage printing surface nozzles arranged above the printing medium, and that transports the printing medium folded back to one side by the rear-stage folding unit to one side with the printing surface facing upward while spraying gas onto the printing surface from the lower-stage printing surface nozzles, and a rear-stage rotating body that rotates while coming into contact with the printing medium conveyed from the lower-stage conveying unit, and at least one of the middle-stage conveying unit and the lower-stage conveying unit has an intermediate rotating body that rotates while coming into contact with the non-printing surface of the printing medium conveyed between the front-stage rotating body and the rear-stage rotating body.

[0008] The drying method of the present invention includes the steps of: transporting a long, strip-shaped print medium with its print surface facing upward while spraying gas onto the print surface from a plurality of upper print surface nozzles arranged above the print medium; folding back the print medium transported to one side in a horizontal direction with the print surface facing upward by a front-stage rotating body that rotates while contacting the non-print surface of the print medium; transporting the folded back print medium to the other side with the print surface facing downward while spraying gas onto the print surface from a plurality of middle print surface nozzles arranged below the print medium; The printing medium transported to one side is folded downward by a non-contact support member that supports the printing medium by spraying gas onto the printing surface of the printing medium, and then folded back to one side; the printing medium folded back to one side is transported to the one side with the printing surface facing upward, while spraying gas onto the printing surface from a plurality of lower printing surface nozzles arranged above the printing medium; and the printing medium transported to one side is transported by a rear-stage rotating body that rotates while contacting the printing medium, and the printing medium transported between the front-stage rotating body and the rear-stage rotating body is supported by an intermediate rotating body that rotates while contacting the non-printing surface of the printing medium.

[0009] In the present invention (drying device and drying method) configured in this way, the print medium transported between the front and rear rotors is supported by the intermediate rotor, which rotates while contacting the non-printing side of the print medium. This allows the print medium to be transported stably from the front rotor between the upper and middle transport sections to the rear rotor behind the lower transport section.

[0010] The drying device may also be configured so that the intermediate rotator contacts the non-printing surface while facing the gap between two adjacent lower-stage printing surface nozzles in the lower-stage conveying section from below, with the printing medium in between. In this configuration, the printing medium being conveyed by the lower-stage conveying section can be supported by the intermediate rotator, and the printing medium can be stably conveyed toward the rear-stage rotator behind the lower-stage conveying section.

[0011] The drying device may also be configured so that an intermediate rotator is provided at each of the multiple intervals formed in the arrangement of the multiple lower-printing-surface nozzles. In this configuration, the multiple lower-printing-surface nozzles and the multiple intermediate rotators are arranged so that the lower-printing-surface nozzles and the intermediate rotators are arranged alternately (i.e., in a staggered pattern). Therefore, the printing medium transported by the lower-stage transport unit can be firmly supported by the multiple intermediate rotators, allowing for extremely stable transport of the printing medium toward the subsequent rotator behind the lower-stage transport unit.

[0012] The drying device may also be configured to include a position sensor that detects the widthwise position of the print medium and a rotor drive unit that drives the rear rotor, and to adjust the widthwise position of the print medium by displacing the rear rotor with the rotor drive unit in accordance with the position of the print medium detected by the position sensor. In this configuration, the widthwise position of the print medium is adjusted by displacing the rear rotor in accordance with the detection result of the widthwise position of the print medium, thereby stabilizing the transport of the print medium. However, if the transport of the print medium reaching the rear rotor is too unstable, the displacement of the rear rotor cannot sufficiently stabilize the transport of the print medium. In contrast, because the print medium is supported by the intermediate rotor, the print medium is transported stably relative to the rear rotor. As a result, the displacement of the rear rotor can sufficiently stabilize the transport of the print medium.

[0013] The drying device may also be configured such that the middle transport unit has multiple middle non-printing surface nozzles arranged above the print medium, the middle non-printing surface nozzles and the middle non-printing surface nozzles are arranged in a staggered pattern, the middle non-printing surface nozzles spray gas onto the non-printing surface, and no intermediate rotor is provided for the print medium transported by the middle transport unit. With this configuration, the print medium before reaching the lower transport unit can be thoroughly dried by gas sprayed from both the middle non-printing surface nozzles and the middle non-printing surface nozzles of the middle transport unit. This allows for both reliable drying of the print medium and stable transport.

[0014] The drying device may also be configured to further include a drying oven housing the upper conveying unit, the middle conveying unit, and the lower conveying unit, and an exhaust unit for discharging gas from the drying oven, the exhaust unit discharging an amount of gas from the drying oven corresponding to the amount of gas sprayed from the upper printed surface nozzle, the middle printed surface nozzle, the middle non-printed surface nozzle, and the lower printed surface nozzle. In this configuration, an airflow passing through the drying oven can be generated by spraying gas from the nozzles and discharging gas by the exhaust unit. However, if the number of nozzles is small, such an airflow may not be sufficient. In contrast, by providing multiple middle non-printed surface nozzles in the middle conveying unit, a sufficient airflow passing through the drying oven can be ensured, allowing the print medium to be thoroughly dried. This allows for both reliable drying and stable transport of the print medium.

[0015] The printing system according to the present invention includes a printing device that prints an image by ejecting ink onto the printing surface of a print medium, and the drying device described above that dries the ink ejected by the printing device and adheres to the printing surface. Therefore, when drying the print medium while transporting it so that it passes through the upper, middle, and lower transport units in order, it is possible to transport the print medium stably from the front-stage rotating body between the upper and middle transport units to the rear-stage rotating body behind the lower transport unit. [Effects of the Invention]

[0016] As described above, according to the present invention, when drying a printing medium while transporting the printing medium so that it passes through the upper, middle and lower conveying sections in sequence, it is possible to stably transport the printing medium in the section from the front rotating body between the upper and middle conveying sections to the rear rotating body after the lower conveying section. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a front view schematically illustrating an example of a printing system according to the present invention. [Figure 2] FIG. 2 is a front view schematically showing a drying device provided in the printing system of FIG. 1. [Figure 3]3 is a partially enlarged schematic view showing the blower dryers of the upper and lower conveying sections. FIG. [Figure 4] FIG. 4 is a partially enlarged schematic view of the air blow dryer in the middle conveying section. [Figure 5] FIG. 4 is a side view schematically showing the configuration of a position adjustment unit. [Figure 6] FIG. 3 is a plan view schematically showing the configuration of a position adjustment unit. [Figure 7] FIG. 2 is a block diagram showing an electrical configuration of the drying device. [Figure 8] FIG. 2 is a block diagram showing a configuration for controlling an injection amount and an exhaust amount. DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 is a front view schematically illustrating an example of a printing system according to the present invention. In FIG. 1 and the following figures, a horizontal direction X, a horizontal direction Y perpendicular to the horizontal direction X, and a vertical direction Z are indicated as appropriate. As shown in FIG. 1, the printing system 1 includes a coating device 2, a printing device 3, and a drying device 5 arranged in this order in the horizontal direction X (arrangement direction). In this printing system 1, a long strip of printing medium M is transported roll-to-roll from a supply roll 11 to a take-up roll 12. The printing device 3 inkjet prints an image on the printing medium M, which has been coated with a coating liquid by the coating device 2. The drying device 5 dries the printing medium M with the printed image. The printing medium M is made of a film such as OPP (oriented polypropylene) or PET (polyethylene terephthalate). However, the material of the printing medium M is not limited to film and may be paper or the like. The printing medium M is flexible. In the following description, the surface of the print medium M on which an image is printed will be referred to as the front surface M1, and the surface opposite the front surface M1 will be referred to as the back surface M2.

[0019] The coating device 2 has a pan 21 that stores a liquid primer (coating liquid), a gravure roller 22 that is partially immersed in the primer stored in the pan 21, and a conveying unit 23 that conveys the print medium M. The coating device 2 has a coating area where the gravure roller 22 contacts the print medium M conveyed by the conveying unit 23 from below, and the conveying unit 23 conveys the print medium M along the coating area while facing the surface M1 of the print medium M downward. Meanwhile, the gravure roller 22 supplies the primer to the coating area by rotating while holding the primer on its circumferential surface. In this way, the primer supplied by the gravure roller 22 is applied to the surface M1 of the print medium M in the coating area. Furthermore, in the coating area, the traveling direction of the print medium M and the rotation direction of the circumferential surface of the gravure roller 22 are opposite. In other words, the primer is applied to the print medium M using a so-called reverse kiss method. Then, the transport unit 23 transports the printing medium M from the coating device 2 to the printing device 3 while facing the surface M1 of the printing medium M coated with the primer upward.

[0020] The printing device 3 comprises a housing 31, a color printing unit 32 arranged within the housing 31, a white printing unit 33 arranged above the color printing unit 32 within the housing 31, and a transport unit 34 that transports the printing medium M using multiple rollers arranged within the housing 31.

[0021] The color printing unit 32 has multiple (six) ejection heads 321 arranged in the direction of travel of the printing medium M above the printing medium M transported by the transport unit 34. Each of the multiple ejection heads 321 has a nozzle facing from above toward the surface M1 of the printing medium M passing below it, and ejects different color inks from the nozzles using an inkjet method. Here, color ink refers to ink other than white, and includes inks such as cyan, magenta, yellow, and black. In this way, the multiple 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 it.

[0022] The white printing unit 33 also has a single ejection head 331 arranged above the printing medium M transported by the transport unit 34. The ejection head 331 has nozzles facing from above toward the surface M1 of the printing medium M passing below it, and ejects white ink from the nozzles using 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.

[0023] The printing medium M is carried from the coating device 2 into the housing 31 of the printing device 3 with the surface M1 facing upward. Meanwhile, the transport unit 34 turns the printing medium M carried into the housing 31 upside down twice before transporting the printing medium M to the color printing unit 32. This allows the ejection heads 321 of the color printing unit 32 to eject color inks onto the surface M1 of the printing medium M facing upward. Furthermore, the transport unit 34 turns the printing medium M with the color inks attached upside down twice before transporting the printing medium M to the white printing unit 33. This allows the ejection head 331 of the white printing unit 33 to eject white ink onto the surface M1 of the printing medium M facing upward. In this way, the printing medium M with the color inks and white ink attached to its surface M1 is transported from the printing device 3 to the drying device 5 by the transport unit 34.

[0024] 2 is a front view schematically showing the drying device provided in the printing system of FIG. 1. In this figure, one side X1 and the other side X2 of the horizontal direction X are shown, with the one side X1 and the other side X2 facing opposite each other. The drying device 5 dries the printing medium M while transporting the printing medium M in the horizontal direction X, folding it back as appropriate. The drying device 5 includes a housing 6 (drying oven) disposed on one side X1 of the housing 31 of the printing device 3. The housing 6 has a rectangular parallelepiped shape extending in the horizontal direction X, and both side walls 6a, 6b of the housing 6 in the horizontal direction X are parallel to the vertical direction Z and perpendicular to the horizontal direction X, facing each other with a gap in between in the horizontal direction X.

[0025] Of the side walls 6a, 6b, an inlet 61 penetrates in the horizontal direction X through the side wall 6a on the other side X2 in the horizontal direction X (the side facing the printing device 3), and an outlet 66 penetrates in the horizontal direction X through the housing 6b on one side X1 in the horizontal direction X (the opposite side of the printing device 3). The printing medium M discharged from the printing device 3 is carried into the housing 6 through the inlet 61 and then discharged out of the housing 6 through the outlet 66.

[0026] That is, the drying device 5 includes a transport unit 51 in the housing 6 that transports the printing medium M, and the transport unit 51 transports the printing medium M from the inlet 61 to the outlet 66. The transport unit 51 has an upper transport unit 51u that transports the printing medium M from the other side X2 to the one side X1, a middle transport unit 51m that transports the printing medium M from the one side X1 to the other side X2, and a lower transport unit 51l that transports the printing medium M from the other side X2 to the one side X1. The middle transport unit 51m is located below the upper transport unit 51u, and the lower transport unit 51l is located below the middle transport unit 51m. Therefore, the printing medium M transported by the upper transport unit 51u, the printing medium M transported by the middle transport unit 51m, and the printing medium M transported by the lower transport unit 51l are aligned in the vertical direction Z, or in other words, overlap each other when viewed from the vertical direction Z. Specifically, the upper transport unit 51u transports the printing medium M at the same height as the entrance 61, and the printing medium M is transported in the horizontal direction X by the upper transport unit 51u with the front surface M1 facing upward and the back surface M2 facing downward. The middle transport unit 51m transports the printing medium M below the upper transport unit 51u, and the printing medium M is transported in the horizontal direction X by the middle transport unit 51m with the front surface M1 facing downward and the back surface M2 facing upward. The lower transport unit 51l transports the printing medium M below the middle transport unit 51m, and the printing medium M is transported in the horizontal direction X by the lower transport unit 51l with the front surface M1 facing upward and the back surface M2 facing downward.

[0027] The transport unit 51 also has a front-stage folding unit 52 that folds back the printing medium M from the upper transport unit 51u to the middle transport unit 51m. This front-stage folding unit 52 has two rollers 521, 522 arranged in the vertical direction Z on one side X1 of the housing 6. Each of the rollers 521, 522 is arranged parallel to the horizontal direction Y and is supported by the housing 6 around a rotation axis parallel to the horizontal direction Y. Of the rollers 521, 522, the upper roller 521 wraps around the back surface M2 of the printing medium M transported to one side X1 by the upper transport unit 51u and folds back the printing medium M downward, and the lower roller 522 wraps around the back surface M2 of the printing medium M folded back downward by the roller 521 and folds back the printing medium M to the other side.

[0028] In this way, the front surface M1 and the back surface M2 of the printing medium M are inverted upside down by folding the printing medium M from one side X1 to the other side X2 by the front-stage folding unit 52. The printing medium M folded to the other side X2 by the front-stage folding unit 52 is transported to the other side X2 by the middle-stage transport unit 51m.

[0029] The transport unit 51 also has a rear-stage folding unit 54 that folds the printing medium M from the middle transport unit 51m to the lower transport unit 51l. This rear-stage folding unit 54 has two air turn bars 541, 542 arranged in the vertical direction Z on the other side X2 of the housing 6. The air turn bars 541, 542 are each arranged parallel to the horizontal direction Y and supported by the housing 6. Of the air turn bars 541, 542, the upper air turn bar 541 sprays air onto the surface M1 of the printing medium M transported from the middle transport unit 51m toward the other side X2. This causes the air turn bar 541 to bend the printing medium M downward while leaving a gap between it and the surface M1 of the printing medium M. Of the air turn bars 541, 542, the lower air turn bar 542 sprays air onto the surface M1 of the printing medium M transported downward from the air turn bar 541. As a result, the air turn bar 542 bends the printing medium M to one side X1 while leaving a gap between the air turn bar 542 and the surface M1 of the printing medium M.

[0030] In this way, the rear-stage folding unit 54 folds the printing medium M from the other side X2 to the one side X1, thereby inverting the front side M1 and the back side M2 of the printing medium M upside down. The printing medium M folded back to the one side X1 by the rear-stage folding unit 54 is transported to the one side X1 by the lower-stage transport unit 51l.

[0031] The transport unit 51 also has a roller 561 that supports the printing medium M that has been transported from the lower transport unit 51l to one side X1. The roller 561 is arranged parallel to the horizontal direction Y on one side X1 of the housing 6, and is supported by the housing 6 so as to be rotatable around an axis of rotation that is parallel to the horizontal direction Y. The roller 561 supports the printing medium M by rotating while coming into contact with the back surface M2 of the printing medium M that has been transported from the lower transport unit 51l to one side X1. The roller 561 constitutes part of a position adjustment mechanism 56 that adjusts the position of the printing medium M in the horizontal direction Y, as will be described later.

[0032] The drying device 5 includes six air dryers 7a to 7f in the housing 6. Of these, two air dryers 7a and 7b are provided in the upper transport section 51u and arranged between the inlet 61 and the rollers 521. The air dryers 7a and 7b dry the printing medium M transported from the inlet 61 toward the rollers 521. The two air dryers 7c and 7d are provided in the middle transport section 51m and arranged between the rollers 522 and the air turn bar 541. The air dryers 7c and 7d dry the printing medium M transported from the rollers 522 toward the air turn bar 541. The two air dryers 7e and 7f are provided in the lower transport section 51l and arranged between the air turn bar 542 and the rollers 561. The air blowers 7e and 7f dry the print medium M that is transported from the air turn bar 542 toward the roller 561.

[0033] Fig. 3 is a partially enlarged schematic view of the blow dryers in the upper and lower conveying sections, and Fig. 4 is a partially enlarged schematic view of the blow dryer in the middle conveying section. Next, blow dryers 7a to 7f will be described with reference to Figs. 3 and 4.

[0034] The blower dryer 7a has an air blowing unit 71u arranged above the printing medium M being transported from the carry-in entrance 61 toward the rollers 521. The air blowing unit 71u has an air blowing chamber 72u extending in the horizontal direction X above the printing medium M. Both end surfaces of the air blowing chamber 72u in the horizontal direction X are planes perpendicular to the horizontal direction X and parallel to the vertical direction Z. Hot air (air at a temperature of 60 degrees or higher) generated by heating air with a heater provided outside the printing system 1 is supplied to the air blowing chamber 72u. The lower surface of the air blowing chamber 72u is a nozzle arrangement plane 73u that faces from above the surface M1 (upper surface) of the printing medium M facing upward. This nozzle arrangement plane 73u is a plane parallel to the horizontal direction X and perpendicular to the vertical direction Z. Furthermore, the air blowing unit 71u has a plurality of nozzles 76u arranged at a predetermined pitch in the horizontal direction X on the nozzle arrangement plane 73u. In this way, the multiple nozzles 76u are lined up between the nozzle arrangement plane 73u and the surface M1 of the printing medium M, and face the surface M1 of the printing medium M. Each nozzle 76u is in communication with the air blowing chamber 72u, and hot air supplied to the air blowing chamber 72u is sprayed from the nozzles 76u onto the surface M1 of the printing medium M, drying the printing medium M. In this way, of the multiple air blowing dryers 7a to 7f, the air blowing dryer 7a dries the printing medium M carried into the housing 6 first.

[0035] Furthermore, the blower dryer 7a has multiple rollers 74 (the same number as the nozzles 76u) arranged below the printing medium M transported from the carry-in entrance 61 toward the rollers 521. The multiple rollers 74 are arranged at a predetermined pitch in the direction of travel of the printing medium M (horizontal direction X), and the circumferential surface of each roller 74 contacts the back surface M2 (lower surface) of the printing medium M from below. Each roller 74 supports the printing medium M from below while rotating in response to the printing medium M about an axis of rotation parallel to the horizontal direction Y. The rollers 74 also have fine spiral grooves that allow air to easily escape between the printing medium M and the circumferential surface of the rollers 74.

[0036] Incidentally, the nozzles 76u face from above the area between two adjacent rollers 74 in the horizontal direction X, and the rollers 74 face from below the area between two upper adjacent nozzles 76u in the horizontal direction X. That is, in the horizontal direction X, the nozzles 76u and the rollers 74 are alternately arranged at a pitch that is half the predetermined pitch, and are alternately arranged one by one in the horizontal direction X in a plan view from the vertical direction Z. In other words, the nozzles 76u and the rollers 74 are arranged in a staggered pattern.

[0037] 3, in the portion of the printing medium M facing the nozzle 76u, the printing medium M is pushed downward by the hot air from the nozzle 76u, causing the printing medium M to be biased downward from the upper end of the roller 74, and the portion of the printing medium M facing the roller 74 is supported by the roller 74. Therefore, the printing medium M is transported in the horizontal direction X from the other side X2 to the one side X1 while undulating between the upper end of the roller 74 and below the upper end.

[0038] The blower dryer 7b is disposed downstream of the blower dryer 7a in the traveling direction of the printing medium M transported from the carry-in entrance 61 toward the rollers 521. Similar to the blower dryer 7a, the blower dryer 7b has an air blowing unit 71u disposed above the printing medium M transported from the carry-in entrance 61 toward the rollers 521, and multiple rollers 74 disposed below the printing medium M. In the blower dryer 7b, the multiple rollers 74 support the back surface M2 of the printing medium M from below, while multiple nozzles 76u of the air blowing unit 71u (the same number as the rollers 74) spray hot air from above onto the front surface M1 of the printing medium M, thereby drying the printing medium M.

[0039] The blower dryer 7c has air blowing units 71u and 71l arranged above and below the printing medium M being transported from the roller 522 toward the air turn bar 541. The upper air blowing unit 71u has an air blowing chamber 72u extending in the horizontal direction X above the printing medium M. Both end surfaces of the air blowing chamber 72u in the horizontal direction X are planes perpendicular to the horizontal direction X and parallel to the vertical direction Z. The above-mentioned hot air is supplied to the air blowing chamber 72u. The lower surface of the air blowing chamber 72u is a nozzle arrangement plane 73u that faces from above the back surface M2 (upper surface) of the printing medium M facing upward. This nozzle arrangement plane 73u is a plane parallel to the horizontal direction X and perpendicular to the vertical direction Z. Furthermore, the air blowing unit 71u has a plurality of nozzles 76u arranged at a predetermined pitch in the horizontal direction X on the nozzle arrangement plane 73u. In this way, the multiple nozzles 76u are lined up between the nozzle arrangement plane 73u and the back surface M2 of the printing medium M, and face the back surface M2 of the printing medium M. Each nozzle 76u is in communication with the air blowing chamber 72u, and hot air supplied to the air blowing chamber 72u is sprayed from the nozzles 76u onto the back surface M2 of the printing medium M.

[0040] The lower blower unit 71l has an air-blowing chamber 72l extending in the horizontal direction X below the printing medium M. Both end surfaces of the air-blowing chamber 72l in the horizontal direction X are planes perpendicular to the horizontal direction X and perpendicular to the vertical direction Z. The above-mentioned hot air is supplied to the air-blowing chamber 72l. The upper surface of the air-blowing chamber 72l is a nozzle arrangement plane 73l that faces from below the surface M1 (lower surface) of the printing medium M, which faces downward. This nozzle arrangement plane 73l is a plane that is parallel to the horizontal direction X and perpendicular to the vertical direction Z. Furthermore, the air-blowing unit 71l has a plurality of nozzles 76l arranged at a predetermined pitch in the horizontal direction X on this nozzle arrangement plane 73l. In this way, the plurality of nozzles 76l are lined up between the nozzle arrangement plane 73l and the surface M1 of the printing medium M, and face the surface M1 of the printing medium M. Each nozzle 76l is in communication with the air blowing chamber 72l, and the hot air supplied to the air blowing chamber 72l is sprayed onto the surface M1 of the printing medium M from the nozzles 76l.

[0041] In this way, the air blowing units 71u and 71l sandwich the printing medium M. In other words, the printing medium M transported by the middle transport section 51m passes between the air blowing units 71u and 71l. In this way, the air blowing dryer 7c dries the printing medium M by spraying hot air from the air blowing units 71u and 71l on both the upper and lower sides toward the printing medium M transported by the middle transport section 51m.

[0042] The upper nozzle 76u faces from above the area between two adjacent lower nozzles 76l in the horizontal direction X, and the lower nozzle 76l faces from below the area between two adjacent upper nozzles 76u in the horizontal direction X. That is, in the horizontal direction X, the upper nozzles 76u and the lower nozzles 76l are alternately arranged at a pitch that is half the predetermined pitch, and are alternately arranged one by one in the horizontal direction X in a plan view from the vertical direction Z. In other words, the nozzles 76u, 76l are arranged in a staggered pattern. This staggered arrangement of the nozzles 76u, 76l is achieved by shifting the positions of the blower chambers 72u, 72l relative to each other in the horizontal direction X.

[0043] 4, in the portion of the printing medium M facing the upper nozzle 76u, the hot air from the nozzle 76u pushes the printing medium M downward, causing it to deviate downward from the transport center line L, and in the portion of the printing medium M facing the lower nozzle 76l, the hot air from the nozzle 76l pushes the printing medium M upward, causing it to deviate upward from the transport center line L. Here, the transport center line L is a horizontal imaginary straight line that is equidistant from the nozzle 76u and the nozzle 76l in the vertical direction Z. Therefore, the printing medium M is transported in the horizontal direction X from one side X1 to the other side X2 while undulating between above and below the transport center line L.

[0044] The blower dryer 7d is disposed downstream of the blower dryer 7c in the traveling direction of the printing medium M transported from the roller 522 toward the air turn bar 541. Similar to the blower dryer 7c, the blower dryer 7d has blower units 71u and 71l that sandwich the printing medium M in the vertical direction Z. In the blower dryer 7d, the blower unit 71u sprays hot air from above onto the back surface M2 of the printing medium M, and the blower unit 71l sprays hot air from below onto the front surface M1 of the printing medium M, thereby drying the printing medium M.

[0045] Similar to the air blower 7a, the air blower 7e has an air blowing unit 71u arranged above the print medium M and multiple rollers 74 that contact the print medium M from below. However, the air blower 7e is arranged relative to the print medium M being transported from the air turn bar 542 to the roller 561. Therefore, multiple nozzles 76u provided in the air blowing unit 71u of the air blower 7e face the print medium M from above as it moves from the air turn bar 542 to the roller 561. Furthermore, the multiple rollers 74 of the air blower 7e contact the print medium M from below as it moves from the air turn bar 542 to the roller 561. In this way, the air blower 7e has multiple nozzles 76u arranged at equal intervals in the horizontal direction X above the print medium M, and multiple rollers 74 (the same number as the nozzles 76u) arranged at equal intervals in the horizontal direction X below the print medium M. 2 and 3, the nozzles 76u and rollers 74 are arranged in a staggered pattern in the horizontal direction X. In this way, in the blower dryer 7e, the multiple rollers 74 support the back surface M2 of the printing medium M from below, while the multiple nozzles 76u spray hot air onto the front surface M1 of the printing medium M from above, drying the printing medium M.

[0046] The blower dryer 7f is disposed downstream of the blower dryer 7e in the traveling direction of the printing medium M transported from the air turn bar 542 toward the roller 561. Similar to the blower dryer 7e, the blower dryer 7f has a plurality of nozzles 76u that face the printing medium M from above and a plurality of rollers 74 that contact the printing medium M from below, the nozzles 76u and rollers 74 being arranged in a staggered pattern in the horizontal direction X. In this way, in the blower dryer 7f, the plurality of rollers 74 support the back surface M2 of the printing medium M from below, while the plurality of nozzles 76u spray hot air from above onto the front surface M1 of the printing medium M, thereby drying the printing medium M.

[0047] Incidentally, the nozzles 76u, 76l described above extend parallel to the horizontal direction Y. In the horizontal direction Y, the width of each nozzle 76u, 76l is wider than the width of the print medium M, and the print medium M is transported so that both ends of the print medium M are located between both ends of the nozzles 76u, 76l. Similarly, each roller 74 extends parallel to the horizontal direction Y. In the horizontal direction Y, the width of each roller 74 is wider than the width of the print medium M, and the print medium M is transported so that both ends of the print medium M are located between both ends of the roller 74.

[0048] The drying device 5 also includes exhaust units 8a and 8b in the housing 6 that exhaust air from the housing 6 to the outside. The exhaust unit 8a is located at the end of the other side X2 of the housing 6, between the blower dryers 7a, 7d, and 7e and the side wall 6a. The exhaust unit 8b is located at the end of the one side X1 of the housing 6, between the blower dryers 7b, 7c, and 7f and the side wall 6b. The exhaust units 8a and 8b have a common configuration. The exhaust units 8a and 8b each have four exhaust chambers 81 to 84 arranged in the vertical direction Z. Exhaust chamber 81 is located above the printing medium M transported by upper transport unit 51u, exhaust chamber 82 is located between the printing medium M transported by upper transport unit 51u and the printing medium M transported by middle transport unit 51m, exhaust chamber 83 is located between the printing medium M transported by middle transport unit 51m and the printing medium M transported by lower transport unit 51l, and exhaust chamber 84 is located below the printing medium M transported by lower transport unit 51l. Each of exhaust chambers 81 to 84 exhausts air sucked from inside housing 6 to the outside of housing 6.

[0049] The exhaust of these exhaust chambers 81-84 generates an air current in the housing 6 that flows from one side to the other side in the horizontal direction Y (from the front to the back in FIG. 2). The total amount of air exhausted by the exhaust chambers 81-84 per unit time (exhaust amount) is set according to the total amount of air sprayed by the blower dryers 7a-7e per unit time (injection amount). In other words, the exhaust chambers 81-84 increase or decrease their respective exhaust amounts according to an increase or decrease in the injection amount of the blower dryers 7a-7e.

[0050] FIG. 5 is a side view schematically illustrating the configuration of the position adjustment unit, and FIG. 6 is a plan view schematically illustrating the configuration of the position adjustment unit. The position adjustment unit 56 has a roller 561 as described above. The position adjustment unit 56 also has a rotation support mechanism 563 that rotatably supports the roller 561. The rotation support mechanism 563 has a cylindrical rotation shaft 563a parallel to the vertical direction Z and a stay 563b fixed to the housing 6, and the rotation support mechanism 563 is rotatably supported by the stay 563b. Meanwhile, the roller 561 is rotatably supported by a support member 561a parallel to the horizontal direction Y, and both ends of the support member 561a protrude from the roller 561 in the horizontal direction Y. The ends of the support member 561a are attached to the tip of the rotation shaft 563a. Therefore, the roller 561 can rotate in a rotation direction Rd around a straight line parallel to the vertical direction Z along with the rotation shaft 563a.

[0051] Furthermore, the position adjustment unit 56 has a drive mechanism 564 that drives the roller 561 in the rotation direction Rd. This drive mechanism 564 has an actuator 564a that moves a rod parallel to the horizontal direction X, and the rod of the actuator 564a is connected to an end of the support member 561a (the end opposite to the end face to which the rotation shaft 563a is attached). Therefore, by driving the support member 561a with the actuator 564a, the roller 561 can be rotated in the rotation direction Rd. Here, because the rotation angle of the roller 561 is minute, the roller 561 can be rotated by driving it in the horizontal direction X with the actuator 564a.

[0052] An edge sensor Sd is provided downstream of the roller 561 in the transport direction of the printing medium M. The edge sensor Sd is an optical sensor that detects the position of the edge in the horizontal direction Y of the printing medium M transported from the roller 561. As will be described later, the angle of rotation of the roller 561 by the actuator 564a is feedback-controlled based on the position of the edge of the printing medium M detected by the edge sensor Sd.

[0053] 5, the position adjustment unit 56 has a roller 568 between the take-up roll 12 and the roller 561, and the roller 568 supports the printing medium M between the roller 561 and the take-up roll 12. In other words, the printing medium M is taken up from the roller 561 via the roller 568 onto the take-up roll 12. The edge sensor Sd detects the position of the edge of the printing medium M being transported between the roller 561 and the roller 568.

[0054] 7 is a block diagram showing the electrical configuration of the drying device 5. As shown in the figure, the drying device 5 includes a control unit 100, which is a processor such as a CPU (Central Processing Unit), and a memory unit 110, which is a storage device such as an HDD (Hard Disk Drive). The memory unit 110 stores a target position Ptd of the printing medium M in the horizontal direction Y (in other words, the width direction of the printing medium M). Here, the target position Ptd is the target position of the edge of the printing medium M detected by the edge sensor Sd. The control unit 100 then performs feedback control on the roller 561 based on this target position Ptd.

[0055] For example, the target position Ptd is set so that a center line parallel to the horizontal direction X that passes through the center of the roller 561 in the horizontal direction Y coincides with the center of the printing medium M in the horizontal direction Y. However, the specific setting value of the target position Ptd is not limited to this example.

[0056] The control unit 100 inputs an operation amount corresponding to the difference between the position of the edge of the printing medium M detected by the edge sensor Sd and the target position Ptd to the actuator 564a. The actuator 564a rotates the roller 561 in the rotation direction Rd by a rotation angle θd (amount of displacement) corresponding to the operation amount. This executes feedback control to reduce the difference between the position of the edge of the printing medium M detected by the edge sensor Sd and the target position Ptd. As a result, the position of the edge of the printing medium M detected by the edge sensor Sd can be kept within a predetermined range (in other words, the range of steady-state deviation) from the target position Ptd.

[0057] There are various ways to define the rotation angle θd. For example, the rotation angle θd may be set to zero degrees when the roller 561 is parallel to the horizontal direction Y, and the clockwise direction in plan view may be set to the positive side of the rotation angle θd, and the counterclockwise direction may be set to the negative side of the rotation angle θd.

[0058] As described above, in the above embodiment, the printing medium M transported between roller 522 (front rotator) and roller 561 (rear rotator) is supported by roller 74 (intermediate rotator) of lower transport unit 51l, which rotates while contacting the back surface M2 (non-printing surface) of printing medium M. Therefore, it is possible to stably transport printing medium M in the section from roller 522 between upper transport unit 51u and middle transport unit 51m to roller 561 behind lower transport unit 51l.

[0059] Furthermore, roller 74 is provided in the gap between two adjacent nozzles 76u (lower printing surface nozzles) in lower conveying section 51l so as to face the printing medium M from below and contact the back surface M2. In this configuration, roller 74 supports printing medium M being conveyed by lower conveying section 51l, and printing medium M can be stably conveyed toward roller 561 behind lower conveying section 51l.

[0060] In particular, in the lower transport section 51l, a roller 74 is provided at each of the multiple intervals formed in the arrangement of the multiple nozzles 76u. In this configuration, the multiple nozzles 76u and the multiple rollers 74 are arranged so that the nozzles 76u and the rollers 74 are arranged alternately (i.e., in a staggered pattern). Therefore, the printing medium M transported by the lower transport section 51l can be firmly supported by the multiple rollers 74, and the printing medium M can be transported extremely stably toward the roller 561 behind the lower transport section 51l.

[0061] Also provided are an edge sensor Sd (position sensor) that detects the position of the printing medium M in the horizontal direction Y (width direction), and an actuator 564a (rotating body drive unit) that drives the roller 561. The actuator 564a rotates the roller 561 in accordance with the position of the printing medium M detected by the edge sensor Sd, thereby adjusting the position of the printing medium M in the horizontal direction Y. That is, by rotating the roller 561 in accordance with the result of detecting the position of the printing medium M in the horizontal direction Y, the position of the printing medium M in the horizontal direction Y is adjusted, thereby stabilizing the transport of the printing medium M. However, if the transport of the printing medium M reaching the roller 561 is too unstable, the rotation of the roller 561 cannot sufficiently stabilize the transport of the printing medium M. In contrast, because the printing medium M is supported by the roller 74, the printing medium M is transported stably relative to the roller 561. As a result, the rotation of the roller 561 can sufficiently stabilize the transport of the printing medium M.

[0062] Furthermore, the middle transport unit 51m has a plurality of nozzles 76u (middle non-printing surface nozzles) arranged above the print medium M, with the nozzles 76l and 76u arranged in a staggered pattern. That is, the print medium M transported by the middle transport unit 51m is provided with the nozzles 76u, but no rollers 74. With this configuration, the print medium M before reaching the lower transport unit 51l can be thoroughly dried by hot air sprayed from both the nozzles 76l and 76u of the middle transport unit 51m. This allows for both reliable drying of the print medium M and stable transport.

[0063] The drying oven 6 includes a housing 6 (drying furnace) that houses the upper transport unit 51u, the middle transport unit 51m, and the lower transport unit 51l, and exhaust units 8a and 8b that exhaust air from the housing 6. The exhaust units 8a and 8b exhaust air from the housing 6 in an amount (exhaust volume) corresponding to the amount (ejection volume) of air sprayed from the nozzles 76u and 76l. With this configuration, an airflow passing through the housing 6 can be generated by the air sprayed from the nozzles 76u and 76l and the air exhausted by the exhaust units 8a and 8b. However, if the number of nozzles 76u and 76l is small, this airflow may not be sufficient. By providing multiple nozzles 76u in the middle transport unit 51m, a sufficient amount of air can be secured to pass through the housing 6, allowing the printing medium M to be thoroughly dried. This allows for both reliable drying and stable transportation of the printing medium M.

[0064] 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 drying device 5 corresponds to an example of the "drying device" of the present invention, the upper conveying unit 51u corresponds to an example of the "upper conveying unit" of the present invention, the middle conveying unit 51m corresponds to an example of the "middle conveying unit" of the present invention, the lower conveying unit 51l corresponds to an example of the "lower conveying unit" of the present invention, the front turning unit 52 corresponds to an example of the "front turning unit" of the present invention, the roller 522 corresponds to an example of the "front rotating body" of the present invention, the rear turning unit 54 corresponds to an example of the "rear turning unit" of the present invention, the air turn bars 541 and 542 correspond to an example of the "non-contact support member" of the present invention, the roller 561 corresponds to an example of the "rear rotating body" of the present invention, the actuator 564a corresponds to an example of the "rotating body driving unit" of the present invention, the housing 6 corresponds to an example of the "drying oven" of the present invention, and the lower The roller 74 of the conveying section 51l corresponds to an example of an "intermediate rotating body" of the present invention, the nozzle 76u of the upper conveying section 51u corresponds to an example of an "upper printing surface nozzle" of the present invention, the nozzle 76l of the middle conveying section 51m corresponds to an example of a "middle printing surface nozzle" of the present invention, the nozzle 76u of the middle conveying section 51m corresponds to an example of a "middle non-printing surface nozzle" of the present invention, the nozzle 76u of the lower conveying section 51l corresponds to an example of a "lower printing surface nozzle" of the present invention, the exhaust sections 8a and 8b correspond to an example of an "exhaust section" of the present invention, the edge sensor Sd corresponds to an example of a "position sensor" 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 "printing surface" of the present invention, the back surface M2 corresponds to an example of a "non-printing surface" of the present invention, the horizontal direction X corresponds to an example of a "horizontal direction" 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.

[0065] The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, the front folding unit 52 does not necessarily have to be configured with two rollers 521, 522, but may be configured so that a single large roller folds the print medium M from one side X1 to the other side X2. Similarly, the rear folding unit 54 does not necessarily have to be configured with two air turn bars 541, 542.

[0066] Furthermore, the configuration of the rotation support mechanism 563 that displaces the roller 561 is not limited to the above example. That is, the rotation support mechanism 563 may be configured so that the roller 561 is displaced by a motor instead of an actuator.

[0067] The position of the center of rotation of the roller 561 is not limited to the above example and can be changed as appropriate. The displacement direction of the roller 561 is not limited to the rotation direction Rd but may be the horizontal direction Y.

[0068] The position of the edge sensor Sd can also be changed as appropriate.

[0069] Furthermore, the arrangement and number of rollers 74 may be changed as appropriate between roller 522 and roller 561. For example, some of the rollers 74 in the lower transport unit 51l may be replaced with nozzles 76l. Alternatively, some or all of the nozzles 76u in the middle transport unit 51m may be replaced with rollers 74. The rollers 74 in the middle transport unit 51m come into contact with the back surface M2 of the printing medium M from above. Furthermore, when rollers 74 are provided in the middle transport unit 51m, all of the rollers 74 in the lower transport unit 51l may be replaced with nozzles 76l.

[0070] Although not described in detail above, the injection amount from the blower dryers 7a-7e and the exhaust amount from the exhaust units 8a, 8b can be controlled, for example, using the configuration shown in FIG. 8. FIG. 8 is a block diagram showing a configuration for controlling the injection amount and the exhaust amount. An air pump Ps is provided for the blower chambers 72u, 72l of the blower dryers 7a-7e. Hot air generated by heating outside air with the main heater Hm is supplied to the blower chambers 72u, 72l by the air pump Ps and then sprayed from the nozzles 76u, 76l. An exhaust pump Pe is provided for the exhaust units 8a, 8b. In response to the operation of the exhaust pump Pe, the exhaust units 8a, 8b exhaust air from the housing 6. The control unit 100 controls the blower pump Ps and the exhaust pump Pe to adjust the injection amount and the exhaust amount as described above. As a result, the exhaust amount increases as the injection amount increases, and decreases as the injection amount decreases. [Industrial Applicability]

[0071] The present invention is applicable to all techniques for drying a print medium having ink attached thereto by jetting gas. [Explanation of symbols]

[0072] 1. Printing system 3...Printing device 5...Drying device 51u...Upper conveyor 51m...Middle conveyor section 51l...Lower conveying section 52...Front folded section 522... Roller (pre-rotating body) 54...Rear folding section 541...Air turn bar (non-contact support member) 542...Air turn bar (non-contact support member) 561... Roller (rear rotating body) 564a...Actuator (rotating body drive unit) 6...Housing (drying oven) 74...Roller (intermediate rotating body) 76u...Nozzle 76l...Nozzle 8a...Exhaust section 8b...Exhaust section Sd...Edge sensor (position sensor) M…Print media M1…Surface (printed surface) M2…Back side (non-printing side) X…Horizontal direction X1...One side X2: other side

Claims

1. an upper conveying unit that has a plurality of upper printing surface nozzles arranged above a long strip-shaped printing medium having a printing surface with ink attached and a non-printing surface opposite to the printing surface, and that ejects gas from the upper printing surface nozzles onto the printing surface while conveying the printing medium to one side in a horizontal direction with the printing surface facing upward; a front-stage folding unit having a front-stage rotating body that rotates while contacting the non-printing surface of the print medium, and folding the print medium transported from the upper-stage transport unit back to the other side opposite the one side by the front-stage rotating body; a middle stage conveying unit that has a plurality of middle stage printing surface nozzles arranged below the print medium, and that conveys the print medium that has been folded back to the other side by the front stage folding unit to the other side with the print surface facing downward, while injecting gas onto the print surface from the middle stage printing surface nozzles; a rear-stage folding unit having a non-contact support member that supports the print medium by injecting gas onto the printing surface of the print medium, and folding the print medium conveyed from the middle-stage conveying unit downward by the non-contact support member and then folding it back to the one side; a lower transport unit having a plurality of lower print surface nozzles arranged above the print medium, the lower transport unit transporting the print medium folded back to the one side by the rear folding unit to the one side with the print surface facing upward, while injecting gas onto the print surface from the lower print surface nozzles; a drying furnace accommodating the upper conveying section, the middle conveying section, and the lower conveying section; a rear-stage rotating body that rotates while contacting the print medium transported from the lower-stage transport unit; a position sensor that detects the position in the width direction of the print medium that has been transported from the lower transport unit; a rotor drive unit that drives the rear rotor; and the lower conveying unit has an intermediate rotating body that rotates while contacting the non-printing surface of the print medium, A drying device characterized in that the position of the printing medium in the width direction is adjusted by displacing the rear-stage rotating body using the rotating body drive unit in accordance with the position of the printing medium detected by the position sensor.

2. The drying device according to claim 1 , wherein the intermediate rotator contacts the non-printing surface while facing the gap between two adjacent lower-stage printing surface nozzles in the lower-stage transport section from below with the printing medium interposed therebetween.

3. The drying device according to claim 2 , wherein the intermediate rotating body is provided at each of a plurality of intervals formed in the arrangement of the plurality of lower printing surface nozzles.

4. the middle stage conveying unit has a plurality of middle stage non-printing surface nozzles arranged above the print medium, the middle stage printing surface nozzles and the middle stage non-printing surface nozzles are arranged in a staggered pattern, and the middle stage non-printing surface nozzles inject gas onto the non-printing surface; 4. The drying device according to claim 2, wherein the intermediate rotator is not provided for the print medium transported by the intermediate transport section.

5. an exhaust unit that exhausts gas from the drying furnace; Furthermore, The drying device according to claim 4, wherein the exhaust section exhausts an amount of gas from the drying furnace corresponding to the amount of gas sprayed from the upper printing surface nozzle, the middle printing surface nozzle, the middle non-printing surface nozzle, and the lower printing surface nozzle.

6. the rear-stage rotor, the position sensor, and the rotor drive unit are disposed outside the drying furnace; The position sensor detects the position of the print medium in the width direction outside the drying oven.

6. The drying device according to claim 1.

7. a printing device having a first ejection head that ejects a first ink onto a long strip-shaped printing medium having a printing surface and a non-printing surface opposite to the printing surface, and that ejects the first ink from the first ejection head onto the printing surface while transporting the printing medium; a drying device according to claim 1 , the drying device being provided downstream in a transport direction of the printing device and configured to dry the print medium having the first ink adhered thereto while transporting the print medium; A printing system comprising:

8. 8. The printing system according to claim 7, wherein the printing device further has a housing in which a first ejection head is disposed, and after transporting the printing medium into the housing, the printing medium is subjected to a first upside-down inversion twice, and then transported to the one side with the printing surface facing upward, while ejecting the first ink from the first ejection head onto the printing surface.

9. 9. The printing system according to claim 8, wherein the printing device further includes a second ejection head that ejects a second ink onto the printing medium, and the printing medium with the first ink attached thereto is subjected to a second upside-down inversion twice, and then transported to the one side with the printing surface facing upward while ejecting the second ink from the second ejection head onto the printing surface, and the printing medium before and after the second upside-down inversion overlap in a planar view.

Images