Inkjet printing device

Abstract

To provide an inkjet printing device, which is configured to flow mist floating between an inkjet head and a medium toward a downstream side in a conveying direction with a simple structure and to perform printing with high accuracy.SOLUTION: A first rotating body (R1) is arranged at least at a downstream side of an inkjet head (40) in a conveying direction (T) of a medium (P) by conveying parts (50 and 31) and can contact the medium (P). A second rotating body (R2), arranged between the first rotating body (R1) and the inkjet head (40) in the conveying direction (T), rotates in non-contact with the medium (P), in a position where a gap (DF) between the medium (P) and the body is equal to a head gap (DH) between the inkjet head (40) and the medium (P) or less and is wider than a gap (DR) between the first rotating body (R1) and the medium (P), so as to generate air flow (F) flowing, in the conveying direction (T), between the inkjet head (40) and the medium (P).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an inkjet printing device equipped with an inkjet head. [Background technology]

[0002] In an inkjet printing device, when an inkjet head ejects ink, a small volume mist (including satellites) is generated in addition to the main droplets used to form an image. This mist floats inside the inkjet printing device and soils the internal components of the device and the head surface. In response to this, airflow generating devices have been proposed that generate airflow by sucking air above the medium or ejecting air downward toward the medium (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5644205 [Patent Document 2] Patent No. 5811667 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the head gap between the inkjet head and the medium is particularly wide, the mist tends to remain between the inkjet head and the medium, and the mist tends to adhere to the inkjet head. When the mist adheres to the inkjet head in this way, it can cause ink ejection problems in the inkjet head or the mist can fall from the inkjet head and adhere to paper, making it difficult to print with high precision.

[0005] Furthermore, if the airflow generating device strengthens the upward air suction or downward air ejection in order to prevent the mist from accumulating between the inkjet head and the medium, the ink landing accuracy will deteriorate and the medium will float, making it impossible to print with high precision. Furthermore, if an ejection mechanism that ejects air is arranged separately from a suction mechanism that sucks in air as the airflow generating device, the structure of the inkjet printing device will become complicated.

[0006] An object of the present invention is to provide an inkjet printing device that can cause the mist floating between the inkjet head and the medium to flow downstream in the transport direction with a simple configuration and can perform printing with high accuracy. [Means for solving the problem]

[0007] In one aspect, an inkjet printing device includes a transport unit that transports a medium, an inkjet head that ejects ink onto the medium transported by the transport unit, a first rotating body that is arranged at least upstream of the inkjet head in the transport direction of the medium by the transport unit and is capable of contacting the medium, and a second rotating body that is arranged between the first rotating body and the inkjet head in the transport direction and rotates without contacting the medium at a position where a gap with the medium is equal to or smaller than a head gap between the inkjet head and the medium and is wider than the gap between the first rotating body and the medium, thereby generating an airflow that flows in the transport direction between the inkjet head and the medium. Effect of the Invention

[0008] According to this aspect, the mist floating between the inkjet head and the medium can be caused to flow downstream in the transport direction with a simple configuration, and printing can be performed with high accuracy. [Brief description of the drawings]

[0009] [Figure 1] 1 is a front view showing an internal structure of an inkjet printing apparatus according to an embodiment; [Diagram 2] FIG. 2 is a diagram illustrating a control configuration of an inkjet printing apparatus according to an embodiment. [Diagram 3] FIG. 4 is a front view showing a paper pressure roller and an airflow generating roller according to an embodiment. [Figure 4] 4 is a plan view showing a paper pressure roller and an airflow generating roller according to an embodiment; FIG. [Diagram 5] FIG. 2 is a front view showing the speed and direction of airflow in one embodiment by the length and direction of arrows. [Figure 6] FIG. 2 is a front view showing the speed and direction of airflow in one embodiment by the length and direction of arrows. [Figure 7] FIG. 4 is a front view showing airflow in a transport direction by shading in one embodiment. [Figure 8] FIG. 4 is a front view showing airflow in a transport direction by shading in one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An inkjet printing apparatus according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] 1 and 2 are a front view showing the internal structure of an inkjet printing apparatus 1 according to an embodiment and a diagram showing a control configuration.

[0012] 3 and 4 are a front view and a plan view showing the paper pressure roller R1 and the airflow generating roller R2 in one embodiment.

[0013] Note that the up-down, front-back, and left-right directions shown in Figures 1, 3, and 4, as well as Figures 5 to 8 described below, are examples for the convenience of explanation, and for example, the up-down direction is the vertical direction, and the front-back and left-right directions are the horizontal directions.

[0014] 1, the inkjet printing device 1 includes a device housing 2, an external paper feed unit 10, an internal paper feed unit 20, an inkjet head 40, a print transport unit 50, a paper discharge unit 60, a mist collection unit 70, two paper holding down rollers R1, and two airflow generating rollers R2. Also, as shown in FIG. 2, the inkjet printing device 1 further includes a control unit 81, a memory unit 82, an interface unit 83, a first rotating body drive unit 91, a second rotating body drive unit 92, and a transport drive unit 93.

[0015] In addition, the paper P in this embodiment is an example of a medium, and the medium may be a sheet-like medium made of a material other than paper, or a medium having a folded portion such as an envelope. Therefore, in this specification, paper feed is an example of supply, and paper discharge is an example of ejection. Therefore, paper feed can be replaced with supply, paper discharge with ejection, and paper with medium. Also, in FIG. 1, the transport path of paper P continuing from the external paper feed unit 10 or the internal paper feed unit 20 to the paper discharge unit 60 is shown by a solid line, and the switchback path 34 for double-sided printing is shown by a dashed line.

[0016] The external paper feed unit 10 has a paper feed tray 11, a paper feed roller 12, and a separation plate 13. The external paper feed unit 10 is an example of a supply unit, and is arranged, for example, so as to be exposed to the outside of the device housing 2, and feeds paper P into the device housing 2.

[0017] Unprinted sheets P are stacked in the paper feed tray 11. For example, two paper feed rollers 12 are arranged side by side in the transport direction T of the sheets P, and feed and transport the uppermost sheet P among the multiple sheets P stacked in the paper feed tray 11. The separation plate 13 sandwiches the sheets P between itself and the paper feed rollers 12 and separates them one by one.

[0018] The internal paper feed section 20 has a first paper feed section 21, a second paper feed section 22, and a third paper feed section .

[0019] The first paper feed section 21, the second paper feed section 22, and the third paper feed section 23 are arranged in this order from top to bottom inside the device housing 2. The first paper feed section 21, the second paper feed section 22, and the third paper feed section 23 each have a paper feed tray 21a, 22a, 23a on which unprinted paper P is stacked, and a paper feed roller 21b, 22b, 23b that picks up and transports the uppermost paper P among the multiple sheets of paper P stacked on the paper feed tray 21a, 22a, 23a.

[0020] The inkjet printing device 1 further includes a plurality of conveying rollers 31, a path switching unit 32, switchback rollers 33, and a switchback path 34. The conveying rollers 31, the path switching unit 32, the switchback rollers 33, and the switchback path 34 circulate the paper P for double-sided printing and convey it to the inkjet head 40 so that it can be refed.

[0021] The transport rollers 31 are arranged in pairs on a transport path of the paper P inside the device housing 2 so as to sandwich the paper P therebetween, and transport the paper P.

[0022] The path switching unit 32 switches the transport path of the paper P on which printing has been performed by the inkjet head 40 between a path toward the paper discharge unit 60 and a switchback path 34. The path switching unit 32 is, for example, a flipper. The switchback rollers 33 switchback-transport the paper P on the switchback path 34, thereby inverting the paper P upside down.

[0023] The inkjet head 40 is, for example, a line-type inkjet head having one or more head modules each having a plurality of nozzles that eject ink, and ejects ink onto the paper P that is transported by the transport rollers 31, a print transport unit 50 (described later), or the like. In this way, the inkjet head 40 prints on the paper P.

[0024] The print transport unit 50 is disposed to face the inkjet head 40 and transports the paper P. The print transport unit 50 has a plurality of pulleys 51, a belt 52 stretched around the pulleys 51, and a suction fan 53 that sucks air through a plurality of holes provided in the belt 52 to cause the paper P to adhere to the belt 52. The print transport unit 50 may have a transport member other than the belt 52, such as a roller, or may not adsorb the paper P. The print transport unit 50 functions as an example of a transport unit that transports the paper P together with the transport roller 31 and the like. This transport unit may have a transport member such as a roller or a belt.

[0025] The paper discharge unit 60 has a paper discharge tray 61 and paper discharge rollers 62. The paper discharge unit 60 is an example of a discharge unit, and is disposed, for example, so as to be exposed to the outside of the device housing 2, and discharges the paper P to the outside of the device housing 2.

[0026] Printed paper P is stacked on the paper discharge tray 61. The paper discharge rollers 62 are arranged, for example, in a pair above and below, and transport the paper P toward the paper discharge tray 61.

[0027] The mist collection unit 70 is disposed in a flow path of the airflow F generated by the rotation of the airflow generating roller R2, which will be described later, and collects the mist of ink discharged from the inkjet head 40. The mist collection unit 70 may collect the mist by sucking in air with a suction mechanism such as a fan, or may collect the mist by utilizing the airflow above the paper P. Since it is particularly undesirable for the mist to float between the inkjet head 40 and the paper P, the mist collection unit 70 may be omitted as long as the mist can be discharged from between the inkjet head 40 and the paper P by the airflow F generated by the airflow generating roller R2.

[0028] The paper pressure rollers R1 are arranged, for example, in pairs, one above the other, on the upstream side and the other below the inkjet head 40 in the transport direction T of the paper P. The paper pressure roller R1, only the upper side of which is shown in FIG. 3, is a medium pressure roller as an example of a first rotating body, and rotates when driven by a first rotating body drive unit 91 described later, or when the lower paper pressure roller R1 shown in FIG. 1 comes into contact with the belt 52, and the upper paper pressure roller R1 also rotates in conjunction with this rotation. The paper pressure roller R1 is arranged so as to be able to come into contact with the paper P, for example, at a height (for example, a height that only comes into contact with a floating paper P) above the height at which the paper P is nipped together with the print transport unit 50 (a height at which the paper P is always in contact), and prevents the paper P from colliding with the inkjet head 40. The paper pressure roller R1 is also arranged facing the print transport unit 50 (above the print transport unit 50). In addition, the pair of upper and lower paper holding rollers R1 are arranged to be able to rise and fall, and by partially moving the belt 52 of the printing transport section 50 up and down as the lower paper holding roller R1 rises and falls, it is possible to adjust the head gap DH between the inkjet head 40 and the paper P shown in Figure 3.

[0029] The paper pressure roller R1 may be disposed only on the upstream side of the inkjet head 40 in the transport direction T. Furthermore, the paper pressure roller R1 may not be a pair, upper and lower, but may be a single roller disposed only on the upper side (the inkjet head 40 side). Furthermore, the upper paper pressure roller R1 may be disposed at a height where it is in constant contact with the paper P.

[0030] The airflow generating roller R2 is disposed between the paper hold down roller R1 and the inkjet head 40 in the transport direction T. In the example of Fig. 3 and Fig. 4, the airflow generating roller R2 is disposed between the paper hold down roller R1 on the upstream side in the transport direction T and the inkjet head 40, and between the inkjet head 40 and the paper hold down roller R1 on the downstream side in the transport direction T. The airflow generating roller R2 is also disposed facing the print transport section 50 (above the print transport section 50).

[0031] The gap DF (second gap) between the airflow generating roller R2 and the paper P at the first position (1) shown by the solid line in FIG. 3 is equal to or smaller than the head gap DH between the inkjet head 40 and the paper P (DF≦DH) and is wider than the gap DR (first gap) between the paper holding roller R1 and the paper P (DF>DR). Desirably, the gap DF between the airflow generating roller R2 and the paper P is wider than half the head gap DH (DF>(DH / 2)). The airflow generating roller R2 generates an airflow F that flows between the inkjet head 40 and the paper P in the transport direction T by rotating without contacting the paper P at the first position (1). The rotation speed of the airflow generating roller R2 is preferably equal to or greater than the transport speed of the paper P (for example, the transport speed of the print transport unit 50). The airflow generating roller R2 is an example of a second rotating body, and is preferably rotated by driving a second rotating body driving unit 92 described later or by interlocking with the paper holding roller R1. The rotation direction of the airflow generating roller R2 is counterclockwise in FIG. 3, the same as that of the paper holding roller R1, so that the lower end (paper P side) of the airflow generating roller R2 coincides with the transport direction T.

[0032] The airflow generating roller R2 is disposed so as to be movable (liftable) between the first position (1) described above and a second position (2) shown by a two-dot chain line in FIG. 3 where it can come into contact with the paper P. The second position (2) is, for example, a medium holding position, at the same height as the paper holding down roller R1. The airflow generating roller R2 moves up and down, for example, by being driven by a lifting drive unit of the second rotating body drive unit 92, which will be described later. In this case, it is preferable that the airflow generating roller R2 is fixed so as to be liftable to the inkjet head 40, which cannot be lifted or lowered.

[0033] The distance Dr between the airflow generating roller R2 and the inkjet head 40 in the transport direction T is preferably shorter than the radius r of the airflow generating roller R2. If the distance Dr is longer than the radius r, the airflow F may rise from below the inkjet head 40 due to an ascending air current generated between the inkjet head 40 and the downstream airflow generating roller R2, causing mist to be dispersed. If the distance Dr is longer than the radius r, the airflow F generated by the upstream airflow generating roller R2 may escape upward from between the inkjet head 40 and the upstream airflow generating roller R2. The airflow generating roller R2 may be disposed, for example, closer to the inkjet head 40 in the transport direction T than the paper holding roller R1.

[0034] 4, the paper pressure roller R1 and the airflow generating roller R2 extend a length equal to or greater than the length of the inkjet head 40 in the width direction (front-rear direction) of the paper P perpendicular to the transport direction T, and are preferably located on the upstream or downstream side of the transport direction T over the entire inkjet head 40. If the airflow generating roller R2 is shorter than the inkjet head 40 in the width direction of the paper P, disturbances such as air entrainment are likely to occur.

[0035] In addition, when the paper pressure roller R1 is disposed only on the upstream side in the transport direction T of the inkjet head 40, the airflow generating roller R2 may also be disposed only on the upstream side in the transport direction T of the inkjet head 40. Furthermore, it is preferable that the airflow generating roller R2 is disposed on both the upstream side and the downstream side in the transport direction T of the inkjet head 40, but it may be disposed on only one side. Furthermore, the airflow generating roller R2 may be disposed so as to be unable to move (rise and fall). Furthermore, it is preferable that the first rotating body, an example of which is the paper pressure roller R1, and the second rotating body, an example of which is the airflow generating roller R2, are cylindrical rollers, but for example, an airflow generating roller R2 having blades to easily generate the airflow F may be used.

[0036] 2 has a processor (e.g., CPU: Central Processing Unit) that functions as an arithmetic processing device that controls the overall operation of the inkjet printing apparatus 1. This processor controls each part of the inkjet printing apparatus 1 by reading and executing a predetermined program, for example, from the storage unit 82 or from a storage medium (non-transitory computer-readable recording medium) that is detachable from the inkjet printing apparatus 1. In this way, the control unit 81 or the inkjet printing apparatus 1 (the control unit 81 and the storage unit 82) functions as a computer that executes a program.

[0037] The control unit 81 moves the airflow generating roller R2 to the first position (1) or the second position (2) based on at least one of the above-mentioned head gap DH, the type of paper P, and the printing information of the printing performed by ejecting ink from the inkjet head 40.

[0038] As an example of control based on the head gap DH, the control unit 81 moves the airflow generating roller R2 to the first position (1) when the head gap DH is four or more times larger than the gap DR between the paper holding roller R1 and the paper P (DH≧4DR), and moves the airflow generating roller R2 to the second position (2) when the head gap DH is not four or more times larger than the gap DR (DH<4DR).

[0039] As an example of control based on the type of paper P, when the paper P is relatively thick or has high rigidity (is difficult to deform), the control unit 81 may move the airflow generating roller R2 to the second position (2) and use it to hold down the paper P in the same manner as the paper holding down roller R1. In this case, for example, the gaps DF and DR are the same, but by making the gap DF narrower than the gap DR, even paper P that floats more strongly can be transported without contacting the inkjet head 40. In addition, the control unit 81 may control the position of the airflow generating roller R2 based on other factors such as whether the paper P is matte paper or not, whether the surface is smooth or not, as the type of paper P. Note that the airflow generating roller R2 may have a function of holding down the paper P (suppressing contact with the inkjet head 40) even at the first position (1).

[0040] As an example of control based on the printing information, the control unit 81 may move the airflow generating roller R2 to the first position (1) when a specified time has elapsed since the inkjet head 40 started to eject ink, when the print rate of the image printed on the paper P is equal to or greater than a specified rate, when the transport speed (printing speed) of the paper P is equal to or less than a specified speed, etc., and may move the airflow generating roller R2 to the second position (2) when a specified time has elapsed since the inkjet head 40 started to eject ink, when the print rate of the image printed on the paper P is less than a specified rate, when the transport speed (printing speed) of the paper P is equal to or greater than a specified speed, etc. Note that when ink ejection is started or when the print rate is low, the airflow from the inkjet head 40 to the paper P due to the ejection of ink from the inkjet head 40 is not well developed, and if the airflow F in the transport direction T becomes large, the ink landing accuracy is likely to deteriorate.

[0041] The airflow generating roller R2 is not limited to the first position (P1) and the second position (P2) described above, and may be arranged to be movable to three or more positions including other positions. The airflow generating roller R2 may be arranged to be movable not only in the vertical direction but also in other directions (for example, the transport direction T). The movement of the airflow generating roller R2 may be controlled by the control unit 81 based on, for example, a user's setting. In this case, for example, a user who sees a print image (print result) of the paper P after printing can arbitrarily adjust the position of the airflow generating roller R2.

[0042] The control unit 81 may also switch the airflow generating roller R2 between an ON state in which the roller rotates and an OFF state in which the roller does not rotate, based on at least one of the head gap DH, the type of paper P, and the print information. The control unit 81 may also switch the airflow generating roller R2 between an ON state in which the roller rotates and an OFF state in which the roller does not rotate, based on a user setting.

[0043] For example, the control unit 81 switches the air flow generating roller R2 to the ON state under conditions such as when a specified time has elapsed since the inkjet head 40 began to eject ink, when the print rate of the image printed on the paper P is equal to or greater than a specified rate, and when the transport speed (printing speed) of the paper P is less than a specified speed, i.e., under conditions similar to those for moving the air flow generating roller R2 to the first position (1) as described above, and switches the air flow generating roller R2 to the OFF state under conditions similar to those for moving the air flow generating roller R2 to the second position (2) as described above.

[0044] The control unit 81 may also adjust the rotation speed of the airflow generating roller R2 based on at least one of the head gap DH, the type of paper P, and the print information. The control unit 81 may also adjust the rotation speed of the airflow generating roller R2 based on a user setting.

[0045] For example, the control unit 81 can adjust the rotation speed of the airflow generating roller R2 by controlling the drive of the second rotor drive unit 92 described below, but if the second rotor drive unit 92 is omitted and the airflow generating roller R2 rotates integrally with the paper hold-down roller R1, the control unit 81 can adjust the rotation speed of the airflow generating roller R2 by controlling a rotation ratio adjustment mechanism that adjusts the rotation ratio between the paper hold-down roller R1 and the airflow generating roller R2. One example of this rotation ratio adjustment mechanism is a known mechanism that has a clutch, a transmission belt, multiple gears with different diameters, etc.

[0046] For example, the control unit 81 may relatively increase the rotational speed of the air flow generating roller R2 under conditions such as when the head gap DH is four or more times larger than the gap DR between the paper holding roller R1 and the paper P (DH≧4DR), i.e., under conditions similar to those for moving the air flow generating roller R2 to the first position (1) as described above, and may relatively slow the rotational speed of the air flow generating roller R2 under conditions similar to those for moving the air flow generating roller R2 to the second position (2) as described above.

[0047] The storage unit 82 has memories such as a ROM (Read Only Memory), which is a read-only semiconductor memory in which a specific control program is pre-recorded, and a RAM (Random Access Memory), which is a semiconductor memory that can be written to and read at any time and is used as a working memory area as needed when the processor executes various control programs.

[0048] The interface unit 83 transmits and receives various information to and from external devices. For example, the interface unit 83 receives a print job including print data from a print control device or a user terminal.

[0049] The first rotating body driving unit 91 has a rotation driving unit that rotates the paper pressure roller R1. The first rotating body driving unit 91 may have a lifting driving unit that lifts and lowers the paper pressure roller R1. These rotation driving units and lifting driving units are, for example, actuators such as motors.

[0050] The second rotor drive unit 92 has a rotation drive unit that rotates the airflow generating roller R2, and an elevation drive unit (movement drive unit) that moves the airflow generating roller R2 to the first position (1) and the second position (2). The rotation drive unit and the elevation drive unit are, for example, actuators such as motors.

[0051] The transport drive unit 93 is an actuator such as a motor that drives the transport rollers 31, the path switching unit 32, the switchback rollers 33, the switchback path 34, and the like shown in FIG.

[0052] Here, as shown in FIGS. 5 and 7, when the airflow generating roller R2 rotates at the above-mentioned first position (1), an airflow F that flows in the transport direction T between the inkjet head 40 and the paper P is generated.

[0053] In particular, when the head gap DH shown in FIG. 3 is wide, the airflow speed between the inkjet head 40 and the paper P is reduced, and the mist is likely to stagnate. However, as shown in FIG. 5 and FIG. 7, the airflow generating roller R2 rotates at the first position (1), and the airflow F flowing in the transport direction T at the intermediate position between the inkjet head 40 and the paper P becomes faster. Originally, the airflow F becomes faster near the paper P due to the transport of the paper P, but if the airflow F is made too fast near the inkjet head 40, the landing accuracy of the ink (droplet formation) may deteriorate. Therefore, it is effective to generate the airflow F quickly at the intermediate position between the inkjet head 40 and the paper P to flow the mist. Note that the head gap DH may be adjusted to be wider when, for example, the paper P is easily bent and deformed, is thick paper, or has an uneven surface (e.g., embossed paper or letter paper).

[0054] 6 and 8, when the airflow generating roller R2 rotates at the above-mentioned second position (2), the airflow F flowing in the transport direction T at the intermediate position between the inkjet head 40 and the paper P is small, and as shown by the thick arrow in Fig. 6, an airflow F is also generated in the opposite direction to the transport direction T. When an airflow F is generated in this manner in the opposite direction to the transport direction T, the mist tends to remain between the inkjet head 40 and the paper P, and the mist tends to adhere to the inkjet head 40.

[0055] In the present embodiment described above, the inkjet printing device 1 includes a transport section (e.g., the print transport section 50, transport roller 31, etc.), the inkjet head 40, a paper pressure roller R1 which is an example of a first rotating body, and an airflow generating roller R2 which is an example of a second rotating body. The transport section transports paper P which is an example of a medium. The inkjet head 40 ejects ink onto the paper P transported by the transport section. The paper pressure roller R1 is disposed upstream and downstream (at least the upstream side) of the inkjet head 40 in the transport direction T of the paper P by the transport section, and is capable of contacting the paper P. The airflow generating roller R2 is positioned between the paper hold-down roller R1 and the inkjet head 40 in the transport direction T, and rotates without contacting the paper P at a position (first position (1)) where the gap DF with the paper P is equal to or smaller than the head gap DH between the inkjet head 40 and the paper P (DF≦DH) and is wider than the gap DR between the paper hold-down roller R1 and the paper P (DF>DR), thereby generating an airflow F that flows in the transport direction T between the inkjet head 40 and the paper P.

[0056] As a result, with a simple configuration using the rotating airflow generating roller R2, the mist floating between the inkjet head 40 and the paper P can be made to flow downstream in the transport direction T. In addition, it is possible to prevent the mist that has accumulated between the inkjet head 40 and the paper P from adhering to the inkjet head 40, causing ink discharge failure at the inkjet head 40, or from dropping from the inkjet head 40 and adhering to the paper P. In addition, since it is possible to avoid sucking air with a strong suction force by the mist collecting section 70 or the like to suck the mist, it is possible to prevent the ink landing accuracy of the inkjet head 40 from deteriorating and the paper P from floating. Therefore, printing can be performed with high accuracy. Note that it is preferable that the airflow generating roller R2 is disposed at least upstream of the inkjet head 40 in the transport direction T, but by disposing the airflow generating roller R2 downstream of the inkjet head 40, the airflow F can be generated in the same manner and the backflow of the airflow F can be suppressed.

[0057] In addition, in this embodiment, the air flow generating roller R2 is arranged to be movable between a first position (1) where it generates an air flow F by rotating without contacting the paper P, and a second position (2) where it can contact the paper P.

[0058] As a result, when there is not a high need to generate air flow F at the first position (1), the air flow generating roller R2 can be moved to the second position (2), which suppresses the floating of the paper P in the same manner as the paper holding roller R1, and the air flow generating roller R2 can be used for other purposes, such as suppressing the floating of the paper P.

[0059] Furthermore, in this embodiment, the control unit 81 switches the airflow generating roller R2 between an ON state in which it rotates and an OFF state in which it does not rotate based on at least one of the head gap DH between the inkjet head 40 and the paper P, the type of paper P, and printing information for printing performed by ejecting ink from the inkjet head 40.

[0060] As a result, when there is relatively little need to generate air current F, such as when not much mist is generated from the inkjet head 40, by turning off the rotation, it is possible to avoid the air current F affecting the ink landing accuracy of the inkjet head 40 and to eliminate unnecessary power.

[0061] Furthermore, in this embodiment, the control unit 81 adjusts the rotation speed of the airflow generating roller R2 based on at least one of the head gap DH between the inkjet head 40 and the paper P, the type of paper P, and the printing information of the printing performed by ejecting ink from the inkjet head 40.

[0062] As a result, when there is a relatively high need to generate the airflow F, such as when a large amount of mist is generated from the inkjet head 40, the rotation speed of the airflow generating roller R2 can be increased to reliably flow the mist downstream in the transport direction T. Furthermore, when there is a relatively low need to generate the airflow F, the rotation speed of the airflow generating roller R2 can be decreased to avoid the airflow F affecting the ink landing accuracy of the inkjet head 40 and to eliminate unnecessary power.

[0063] The present invention is not limited to the above-described embodiment as it is, and the components can be modified and embodied without departing from the gist of the invention in the implementation stage. In addition, various inventions can be formed by appropriate combinations of the multiple components disclosed in the above-described embodiment. For example, all the components shown in the embodiment may be appropriately combined. Of course, various modifications and applications are possible without departing from the spirit of the invention. Some of the inventions described in the specification of this application are described below.

[0064] [Appendix 1] A transport unit that transports the medium; an inkjet head that ejects ink onto the medium transported by the transport unit; a first rotating body that is disposed at least upstream of the inkjet head in a direction in which the medium is transported by the transport unit and is capable of contacting the medium; a second rotating body that is disposed between the first rotating body and the inkjet head in the transport direction, and rotates without contacting the medium at a position where a gap between the medium is equal to or smaller than a head gap between the inkjet head and the medium and is wider than the gap between the first rotating body and the medium, thereby generating an airflow that flows in the transport direction between the inkjet head and the medium; An inkjet printing apparatus comprising:

[0065] [Appendix 2] The second rotating body is disposed so as to be movable between a first position where the second rotating body generates the airflow by rotating without contacting the medium, and a second position where the second rotating body can come into contact with the medium. 2. The inkjet printing apparatus according to claim 1.

[0066] [Appendix 3] A control unit that controls the second rotating body is further provided. The control unit switches the second rotating body between an ON state in which the second rotating body rotates and an OFF state in which the second rotating body does not rotate, based on at least one of the head gap, the type of the medium, and printing information of printing performed by ejecting ink from the inkjet head. 3. The inkjet printing apparatus according to claim 1 or 2.

[0067] [Appendix 4] A control unit that controls the second rotating body is further provided. The control unit adjusts the rotation speed of the second rotating body based on at least one of the head gap, the type of the medium, and print information of printing performed by ejecting ink from the inkjet head. 4. The inkjet printing apparatus according to claim 1, [Explanation of symbols]

[0068] 1 Inkjet printing device 2. Equipment casing 10 External paper feed section 11 Paper feed tray 12 Paper feed roller 13 Cutting Board 20 Internal paper feed section 21 1st paper feed section 22 2nd paper feed section 23 3rd paper feed section 21a, 22a, 23a Paper feed tray 21b, 22b, 23b Paper feed roller 31 Conveyor roller 32 Route switching section 33 Switchback roller 34 Switchback Route 40 Inkjet head 50 Printing transport section 51 Pulley 52 Belt 53 Suction fan 60 Paper output section 61 Output tray 62 Paper ejection roller 70 Mist collection section 81 Control Unit 82 Memory section 83 Interface section 91 First rotating body drive unit 92 Second Rotating Body Drive Unit 93 Conveyor drive unit DF Gap between the airflow roller and the paper (second gap) DH Head Gap DR Gap between the paper pressure roller and the paper (first gap) Dr Distance between the airflow generating roller and the inkjet head F Airflow P Paper R1 Paper pressure roller R2 Air flow generating roller r Radius of the airflow generating roller T Transport direction

Claims

1. A transport unit that transports the medium; an inkjet head that ejects ink onto the medium transported by the transport unit; a first rotating body that is disposed at least upstream of the inkjet head in a direction in which the medium is transported by the transport unit and is capable of contacting the medium; a second rotating body that is disposed between the first rotating body and the inkjet head in the transport direction, and rotates without contacting the medium at a position where a gap between the medium is equal to or smaller than a head gap between the inkjet head and the medium and is wider than the gap between the first rotating body and the medium, thereby generating an air flow that flows in the transport direction between the inkjet head and the medium; An inkjet printing apparatus comprising:

2. The second rotating body is disposed so as to be movable between a first position where the second rotating body generates the airflow by rotating without contacting the medium, and a second position where the second rotating body can come into contact with the medium.

2. The inkjet printing apparatus according to claim 1.

3. A control unit that controls the second rotating body is further provided. The control unit switches the second rotating body between an ON state in which the second rotating body rotates and an OFF state in which the second rotating body does not rotate, based on at least one of the head gap, the type of the medium, and print information of printing performed by ejecting ink from the inkjet head.

3. The inkjet printing apparatus according to claim 1, wherein the inkjet printing apparatus is a liquid ejection apparatus.

4. A control unit that controls the second rotating body is further provided. The control unit adjusts the rotation speed of the second rotating body based on at least one of the head gap, the type of the medium, and print information of printing performed by ejecting ink from the inkjet head.

3. The inkjet printing apparatus according to claim 1, wherein the inkjet printing apparatus is a liquid ejection apparatus.

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