JP2021008035A - Ink jet printer and ink jet printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for reducing deterioration of print quality even when an inert gas is supplied in an inkjet printing technique. A processing chamber 40 is arranged on the downstream side of a discharge head 21 for ejecting ink to a recording medium 9, and has a carry-in inlet 41 and a carry-out outlet 42 for passing the recording medium 9. The irradiation unit 70 irradiates the recording medium 9 inside the processing chamber 40 with ultraviolet rays. The inert gas supply unit 50 supplies the inert gas to the inside of the processing chamber 40. The discharge head 21 and the processing chamber 40 are housed in the apparatus housing 90. The air discharge unit 60 sucks the atmosphere from the carry-in side suction port 611 and the carry-out side suction port 631 and discharges the atmosphere to the outside of the device housing 90. The carry-in side suction port 611 is provided on the upstream side of the carry-in inlet 41, and the carry-out side suction port 631 is provided on the downstream side of the carry-out outlet 42. [Selection diagram] Fig. 1

Description

The present invention relates to a technique of printing on a recording surface of a recording medium by an inkjet method.

Conventionally, there is known an inkjet printing device that records an image on the surface of a recording medium by ejecting ink from a plurality of heads while conveying a strip-shaped recording medium. In this type of inkjet printing apparatus, ink that is cured by being irradiated with active energy rays such as ultraviolet rays and electron beams may be used. In this case, after the ink is ejected onto the recording surface of the recording medium, the ink adhering to the recording medium is irradiated with active energy. As a result, the ink is cured and the image is printed on the recording medium. When the ink is cured by irradiating it with active energy rays, it is known that the curing of the ink is hindered by the influence of oxygen in the vicinity of the ink. In order to cure the ink efficiently, it is desirable to replace the air layer on the surface of the recording medium with an inert gas or the like to reduce the oxygen concentration in the vicinity of the ink.

A technique for reducing the oxygen concentration on the surface of such a recording medium is described in, for example, Patent Document 1. The active energy irradiation device described in the document separates the boundary layer peeling portion having a gas suction port for peeling the gas boundary layer near the surface of the medium to which the active energy ray-curable material is applied, and the gas boundary layer. An inert gas supply unit that supplies an inert gas to the surface of the medium later, a laminar flow securing unit that secures a laminar flow of the inert gas on the surface of the medium, and a material application of the medium via the laminar flow of the inert gas. It is provided with an energy ray irradiation unit that irradiates an active energy ray toward a surface. It is described that the oxygen concentration can be locally reduced on the medium and the active energy ray-curable material can be efficiently cured by supplying the inert gas after the gas boundary separation layer on the medium is peeled off. ing.

Japanese Unexamined Patent Publication No. 2012-166539

However, in the case of the prior art, the inert gas supplied for curing the ink may move from the irradiation area where the active energy rays are irradiated to the ejection area where the ink is ejected. As the concentration of the inert gas in the ejection area increases, the characteristics of the ink (eg, wettability) may change due to the relative decrease in oxygen concentration. For example, in the case of ultraviolet curable ink, when the oxygen concentration decreases, the wettability decreases, so that the ink adhering to the recording medium is difficult to spread sufficiently on the recording medium, and pinholes occur. May decrease.

An object of the present invention is to provide a technique for reducing deterioration of print quality even when an inert gas is supplied in an inkjet printing technique.

In order to solve the above problems, the first aspect is an inkjet printing device that ejects electromagnetic curable ink onto a recording medium to record an image, and comprises a transfer mechanism that conveys the recording medium along a predetermined transfer path. , A discharge head for ejecting ink to the recording medium, a processing chamber arranged on the downstream side of the ejection head and having a carry-in inlet and a carry-out outlet for passing the recording medium, and inside the processing chamber. An irradiation unit that irradiates the recording medium with electromagnetic waves, an inert gas supply unit that supplies an inert gas inside the processing chamber, an apparatus housing that houses the discharge head and the processing chamber, and the processing chamber. Suction is performed from the carry-in side suction port provided on the upstream side of the carry-in port, the carry-out side suction port provided on the downstream side of the carry-out port of the processing chamber, and the carry-in side suction port and the carry-out side suction port. It is provided with an air discharge unit including an exhaust pipe that guides the atmosphere to the outside of the device housing.

The second aspect is the inkjet printing apparatus of the first aspect, further comprising a carry-in side partition wall which is connected to the carry-in entrance of the processing chamber and has a portion facing the transport path, and the carry-in side suction. The opening opens on the recording medium side of the carry-in side partition wall.

The third aspect is the inkjet printing apparatus of the second aspect, in which the pressure loss in the processing chamber is larger than the pressure loss in the first suction space surrounded by the carry-in side partition wall.

A fourth aspect is an inkjet printing apparatus according to any one of the first to third aspects, which is a carry-out side partition wall which is connected to the carry-out port of the processing chamber and has a portion facing the transport path. Further, the carry-out side suction port opens on the carry-out path side of the carry-out side partition wall.

A fifth aspect is the inkjet printing apparatus of the fourth aspect, in which the pressure loss in the processing chamber is larger than the pressure loss in the space surrounded by the carry-out side partition wall.

A sixth aspect is the inkjet printing apparatus according to any one of the first to fifth aspects, further comprising a roller having a cylindrical outer peripheral surface around which the recording medium is wound, and the inert gas supply unit. , Discharge the inert gas toward the roller.

A seventh aspect is the inkjet printing apparatus of the sixth aspect, in which at least one of the carry-in side suction port and the carry-out side suction port faces the outer peripheral surface of the roller.

An eighth aspect is the inkjet printing apparatus of the sixth or seventh aspect, wherein the roller has a cooling mechanism for cooling the outer peripheral surface.

A ninth aspect is the inkjet printing apparatus according to any one of the first to eighth aspects, wherein the amount of the atmosphere discharged per unit time by the air discharging unit is the inert gas supply unit. It is larger than the amount of gas supplied per unit time.

A tenth aspect is an inkjet printing apparatus according to any one of the first to ninth aspects, further comprising an oxygen densitometer for measuring the oxygen concentration in the processing chamber.

The eleventh aspect is the inkjet printing apparatus of the tenth aspect, further including a control unit that controls the discharge amount of the atmosphere by the air discharge unit according to the output from the oxygen meter.

A twelfth aspect is an inkjet printing method of ejecting an electromagnetic wave curable ink onto a recording medium to record an image, wherein (a) a transfer step of transporting the recording medium along a predetermined transport path, and (b). The recording medium is carried into the inside of the processing chamber through the ink ejection step of ejecting ink from the ejection head to the recording medium and (c) the carry-in port of the processing chamber arranged on the downstream side of the ejection head. The steps, (d) an irradiation step of irradiating the recording medium with an electromagnetic wave inside the processing chamber, and (e) an inert gas supply step of supplying an inert gas inside the processing chamber, and (f). ) A carry-out step of carrying out the recording medium to the outside of the processing room through the carry-out port of the processing room, (g) a carry-in side suction port provided on the upstream side of the carry-in port of the processing room, and the above. Includes an air discharge step of sucking atmosphere from each of the carry-out side suction ports provided on the downstream side of the carry-out outlet of the treatment chamber and discharging the atmosphere to the outside of the discharge head and the apparatus housing in which the treatment chamber is housed. ..

According to the inkjet printing device of the first aspect, the inert gas flowing out from the carry-in inlet and the carry-out port of the processing chamber can be discharged to the outside of the device housing through the carry-in side suction port and the carry-out side suction port. .. Therefore, it is possible to prevent the characteristics of the ink adhering to the recording medium from changing due to the movement of the inert gas flowing out of the processing chamber to the vicinity of the ejection head on the upstream side. As a result, deterioration of print quality can be reduced.

According to the inkjet printing apparatus of the second aspect, the atmosphere of the carry-in side partition wall connected to the carry-in entrance of the processing chamber can be sucked from the carry-in side suction port. Therefore, the inert gas flowing out from the carry-in port can be effectively discharged to the outside of the device housing.

According to the inkjet printing apparatus of the third aspect, by making the pressure loss in the processing chamber larger than the pressure loss in the first suction space, the inert gas in the processing chamber is less likely to flow out. Therefore, the concentration of the inert gas in the treatment chamber can be easily increased. In addition, the atmosphere can easily flow into the space of the carry-in side partition wall, and the atmosphere can be sucked well at the carry-in side suction port. Therefore, the inert gas flowing out of the treatment chamber can be satisfactorily sucked.

According to the inkjet printing apparatus of the fourth aspect, the atmosphere inside the carry-out side partition wall connected to the carry-out outlet of the processing chamber can be sucked from the carry-out side suction port. Therefore, the inert gas flowing out from the carry-out port can be effectively discharged to the outside of the apparatus housing.

According to the inkjet printing apparatus of the fifth aspect, by increasing the pressure loss in the processing chamber, the inert gas in the processing chamber is less likely to flow out. Therefore, the concentration of the inert gas in the treatment chamber can be easily increased. In addition, the atmosphere can easily flow into the space of the carry-out side partition wall, and the atmosphere can be sucked well at the carry-out side suction port. Therefore, the inert gas leaking from the treatment chamber can be satisfactorily sucked.

According to the inkjet printing apparatus of the sixth aspect, tension can be applied to the recording medium by a roller. Further, since the inert gas is discharged on the recording medium wound around the roller, the atmosphere on the recording medium can be efficiently replaced with the inert gas.

According to the inkjet printing apparatus of the seventh aspect, the inert gas flowing out onto the roller from the carry-out port or carry-in port of the processing chamber can be satisfactorily sucked.

According to the inkjet printing apparatus of the eighth aspect, the recording medium on the roller can be effectively cooled.

According to the inkjet printing apparatus of the ninth aspect, the air discharge unit can discharge more atmosphere than the amount of the inert gas supplied to the processing chamber. As a result, the movement of the inert gas flowing out of the processing chamber to the vicinity of the discharge head can be effectively suppressed.

According to the inkjet printing apparatus of the tenth aspect, the oxygen concentration in the processing chamber can be detected by providing the oxygen concentration meter.

According to the inkjet printing apparatus of the eleventh aspect, the amount of air discharged by the air discharging unit is controlled according to the oxygen concentration in the processing chamber. Therefore, the oxygen concentration in the processing chamber can be maintained at an appropriate value suitable for curing the ink.

According to the inkjet printing method of the twelfth aspect, the inert gas flowing out from the carry-in inlet and the carry-out port of the processing chamber can be discharged to the outside of the apparatus housing through the carry-in side suction port and the carry-out side suction port. .. Therefore, it is possible to prevent the characteristics of the ink adhering to the recording medium from changing due to the movement of the inert gas flowing out of the processing chamber to the vicinity of the ejection head on the upstream side. As a result, deterioration of print quality can be suppressed.

It is a figure which shows the schematic structure of the inkjet printing apparatus of an embodiment. It is a vertical sectional view of a discharge head and a support base. It is a schematic side view which shows the structure of the vicinity of an irradiation part in an inkjet printing apparatus. It is a schematic front view which shows the structure of the vicinity of an irradiation part in an inkjet printing apparatus. It is a figure which shows the electrical connection structure of the control part and each part in an inkjet printing apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the components described in this embodiment are merely examples, and the scope of the present invention is not limited to them. In the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary for easy understanding.

<1. Embodiment>
FIG. 1 is a diagram showing a schematic configuration of the inkjet printing apparatus 1 of the embodiment. The inkjet printing device 1 records an image on the recording surface of the recording medium 9 by ejecting ink droplets from a plurality of ejection heads 21 while conveying a strip-shaped recording medium 9 (for example, printing paper). It is a device. As the ink used in the inkjet printing apparatus 1, an ultraviolet curable ink that is cured by being irradiated with ultraviolet rays, which are electromagnetic waves, can be adopted. The ink may contain a curing starting material or the like for accelerating curing as a component.

The inkjet printing device 1 includes a transport mechanism 10, an image recording unit 20, a support unit 30, a processing chamber 40, an inert gas supply unit 50, an air discharge unit 60, an irradiation unit 70, and a control unit 80. Each unit (including the image recording unit 20 and the processing room 40) other than the control unit 80 is housed in the box-shaped device housing 90.

The transport mechanism 10 is a mechanism for transporting the recording medium 9 in the moving direction along the longitudinal direction thereof. The transport mechanism 10 has an unwinding portion 11, a plurality of transport rollers 12, a chill roller 13, and a take-up portion 14. The plurality of transfer rollers 12 include a switching roller 121 and a nip roller 122, which will be described later. The recording medium 9 is unwound from the unwinding unit 11 and is conveyed along a transfer path composed of a plurality of transfer rollers 12. Each transport roller 12 guides the recording medium 9 to the downstream side in the moving direction by rotating about the horizontal axis. Further, the recording medium 9 after being conveyed is collected by the winding unit 14. In this way, the recording medium 9 is conveyed along the predetermined transfer path TR1 by being supported by the transfer roller 12, the chill roller 13, and the like arranged at the predetermined positions.

In the following description, the moving direction of the recording medium 9 along the transport path TR1 may be simply referred to as a “moving direction”. Further, the downstream side in the moving direction may be simply referred to as the "downstream side", and the upstream side in the moving direction may be simply referred to as the "upstream side". Further, a direction orthogonal to the moving direction and parallel to the surface of the recording medium 9 may be referred to as a "width direction".

As shown in FIG. 1, when the recording medium 9 is unwound from the unwinding unit 11, it first passes through the cleaner 15. The cleaner 15 includes a plurality of suction rolls 151 arranged in close proximity to each other in the vertical direction. The plurality of suction rolls 151 rotate while being in contact with the recording surface 9a and the back surface 9b of the recording medium 9. Foreign matter adhering to the recording surface 9a and the back surface 9b of the recording medium 9 is adsorbed by the suction roll 151 and removed. As a result, the number of foreign substances adhering to the recording medium 9 before printing can be reduced. Therefore, it is possible to reduce printing defects such as ink being repelled or seeping out due to foreign matter. The cleaner 15 may use a method other than the suction roll 151 such as a suction mechanism.

When the recording medium 9 passes through the cleaner 15, the recording medium 9 moves substantially horizontally along the arrangement direction of the plurality of ejection heads 21 below the image recording unit 20. At this time, the recording surface 9a of the recording medium 9 is directed upward (toward the discharge head 21). Further, the transport mechanism 10 has a switching roller 121, a chill roller 13, and a nip roller 122 on the downstream side in the moving direction from the image recording unit 20.

The nip roller 122 actively rotates at a constant speed while contacting the recording surface 9a and the back surface 9b of the recording medium 9 and gripping the recording medium 9. The transport mechanism 10 adjusts the rotation speed of the unwinding portion 11 with respect to the rotation speed of the nip roller 122. As a result, tension is applied to the recording medium 9. As a result, slack and wrinkles of the recording medium 9 during transportation are suppressed.

The image recording unit 20 is a mechanism for ejecting ultraviolet curable ink to the recording medium 9 conveyed by the conveying mechanism 10. The image recording unit 20 of the present embodiment has four discharge heads 21. The four ejection heads 21 are arranged along the moving direction of the recording medium 9. At the time of printing, inks of each color of C (Cyan), M (Magenta), Y (Yellow), and K (Black), which are color components of a color image, are directed from the four ejection heads 21 toward the recording surface 9a of the recording medium 9. Droplets are ejected respectively. As a result, a color image is formed on the recording surface 9a of the recording medium 9. The step of ejecting ink from the ejection head 21 to the recording medium 9 is an example of the ink ejection process.

The support unit 30 has a plurality of support bases 31 arranged along the moving direction of the recording medium 9. Each of the four discharge heads 21 is attached to one of the plurality of support bases 31. As a result, the four discharge heads 21 are supported, and the mutual positional relationship of each of these parts is fixed. Each support base 31 has a through hole 311 in the center of which the lower end portion of the discharge head 21 fits. Therefore, the lower surface of the discharge head 21 attached to the support base 31 faces the recording surface 9a of the recording medium 9 without being blocked by the support base 31.

FIG. 2 is a vertical cross-sectional view of the discharge head 21 and the support base 31. A plurality of nozzles 211 for ejecting ink droplets are provided on the lower surface of each ejection head 21. The plurality of nozzles 211 are regularly arranged in the width direction of the recording medium 9 orthogonal to the moving direction of the recording medium 9 over substantially the entire width of the recording medium 9. The discharge head 21 is fixed to the support base 31 with its lower end fitted in the through hole 311 of the support base 31. The lower surface of the discharge head 21 is a nozzle surface 212 on which a plurality of nozzles 211 are formed.

As shown in FIG. 1, a switching roller 121 as a switching unit is arranged on the downstream side of the image recording unit 20. The switching roller 121 rotates about a horizontal axis extending in the width direction while contacting the back surface 9b of the recording medium 9. As a result, the recording medium 9 is bent in the direction opposite to the recording surface 9a. As a result, the moving direction of the recording medium 9 is switched from the first direction (substantially horizontal direction in the present embodiment) to the second direction (vertically downward in the present embodiment).

The switching roller 121 comes into contact with the back surface 9b of the recording medium 9. Therefore, the surface of the switching roller 121 does not come into contact with the uncured ink. Therefore, the contact with the switching roller 121 suppresses the deterioration of the image quality on the recording medium 9. Further, a member for switching the moving direction of the recording medium 9 is not arranged on the recording surface 9a side of the recording medium 9.

FIG. 3 is a schematic side view showing the configuration of the vicinity of the irradiation unit 70 in the inkjet printing apparatus 1. FIG. 4 is a schematic front view showing the configuration of the vicinity of the irradiation unit 70 in the inkjet printing apparatus 1.

As shown in FIG. 4, the chill roller 13 rotates about a horizontal axis 131 extending in the width direction while contacting the back surface 9b of the recording medium 9. One end of the horizontal shaft 131 is connected to the motor 13M, and the chill roller 13 rotates by rotating the horizontal shaft 131 by driving the motor 13M. One side wall 133 is arranged to face each other on both sides of the chill roller 13 in the width direction. The horizontal axis 131 is rotatably supported by two side walls 133. The chill roller 13 is arranged substantially vertically above the processing chamber 40 and the irradiation unit 70. The diameter of the outer peripheral surface 13S of the chill roller 13 is larger than the diameter of the outer peripheral surface of the front and rear transfer rollers 12.

Cooling water 130 is stored inside the chill roller 13. The cooling water 130 is appropriately circulated by a circulator (not shown). As a result, the surface of the chill roller 13 is cooled and the temperature is maintained. As described above, the structure for storing the cooling water 130 and the mechanism for circulating the cooling water 130 are examples of the cooling mechanism for cooling the outer peripheral surface 13S of the chill roller 13.

The processing chamber 40 is arranged on the downstream side of the discharge head 21. In other words, the processing chamber 40 is arranged on the downstream side of the position where the ink from the ejection head 21 adheres to the recording medium 9. The processing chamber 40 has a carry-in port 41 and a carry-out port 42 for passing the recording medium 9. The carry-in inlet 41 is an opening for carrying the recording medium 9 into the processing space 40R inside the processing chamber 40, and the carry-out outlet 42 is an opening for carrying out the recording medium 9 from the processing space 40R.

The processing chamber 40 has a first wall portion 43, a second wall portion 44, and a third wall portion 45. The first wall portion 43 constitutes the side surface on the upstream side of the processing space 40R, and the second wall portion 44 constitutes the side surface on the downstream side of the processing space 40R. Further, the third wall portion 45 is a plate-shaped member that connects the first wall portion 43 and the second wall portion 44, and constitutes the bottom surface of the processing space 40R. Both sides of the first wall portion 43, the second wall portion 44, and the third wall portion 45 in the width direction are connected to the side wall 133. That is, the inward facing surfaces of the two side walls 133 form the side surfaces on both sides of the processing space 40R in the width direction.

The first wall portion 43 has a first facing surface 43S that faces the outer peripheral surface 13S of the chill roller 13 and is curved along the outer peripheral surface 13S. The first facing surface 43S and the outer peripheral surface 13S form a first flow path 46a. The upstream end of the first flow path 46a is the carry-in inlet 41.

The second wall portion 44 has a second facing surface 44S that faces the outer peripheral surface 13S of the chill roller 13 and is curved along the outer peripheral surface 13S. The second facing surface 44S and the outer peripheral surface 13S form a second flow path 46b. The downstream end of the second flow path 46b is the carry-out port 42.

The chill roller 13 is arranged on the top surface side of the processing chamber 40 opposite to the third wall portion 45. That is, the outer peripheral surface 13S of the chill roller 13 (specifically, the portion of the outer peripheral surface 13S sandwiched between the first wall portion 43 and the second wall portion 44) constitutes the top surface of the processing chamber 40. Therefore, the processing chamber 40 is a substantially closed space except for the carry-in entrance 41 and the carry-out outlet 42.

It is not essential that the side surfaces of the processing chamber 40 on both sides in the width direction are composed of the two side walls 133. For example, the side walls extending from the third wall portion 45 to the chill roller 13 side and extending in the moving direction may be provided on both outer sides of the transport path TR1 in the width direction.

An oxygen concentration meter 47 is provided in the processing space 40R. The oxygen concentration meter 47 measures the oxygen concentration inside the processing space 40R and outputs it to the control unit 80. It is not essential that the oxygen concentration meter 47 measures the oxygen concentration in the processing space 40R. For example, a mechanism for sending the atmosphere in the processing space 40R to the outside through a predetermined hole may be provided, and an oxygen concentration meter may be provided on the path of the atmosphere sent out to the outside. In this case, the oxygen concentration in the processing chamber 40 can be measured by measuring the oxygen concentration in the atmosphere.

The step in which the transport mechanism 10 carries the recording medium 9 into the inside of the processing chamber 40 through the carry-in inlet 41 is an example of the carry-in process. Further, the step in which the transport mechanism 10 carries out the recording medium 9 to the outside of the processing chamber 40 through the carry-out port 42 is an example of the carry-out step.

The inert gas supply unit 50 supplies the inert gas to the inside of the processing chamber 40. More specifically, nitrogen gas, which is an inert gas, is supplied toward the recording surface 9a of the recording medium 9 inside the processing chamber 40. As shown in FIG. 3, the inert gas supply unit 50 has a supply port 51 that supplies nitrogen gas toward the recording surface 9a of the recording medium 9. A nitrogen gas supply source 54 is connected to the supply port 51 via a pipe 52 and an on-off valve 53. When the on-off valve 53 is opened, nitrogen gas is sent from the supply source 54 toward the supply port 51. Further, by adjusting the opening degree of the on-off valve 53, the pressure of the nitrogen gas supplied from the supply port 51 can be adjusted. A pressure adjusting mechanism for adjusting the pressure of the nitrogen gas supplied from the supply port 51 may be provided separately from the on-off valve 53. Further, the supply port 51 may be separately provided with a discharge mechanism such as a so-called air knife so that a higher pressure nitrogen gas can be supplied. The step in which the inert gas supply unit 50 supplies the inert gas to the inside of the processing chamber 40 is an example of the inert gas supply step.

In this example, the tip end side portion of the pipe 52 is provided inside the first wall portion 43, and the supply port 51 opens at the first facing surface 43S. Therefore, the inert gas supplied from the inert gas supply unit 50 passes through the first flow path 46a and moves into the processing chamber 40. Further, the supply port 51 injects the inert gas toward the outer peripheral surface 13S of the chill roller 13. In this case, since the inert gas can be sprayed on the recording surface 9a of the recording medium 9, the atmosphere on the recording surface 9a can be efficiently replaced with the inert gas.

The air discharge unit 60 includes a carry-in side suction unit 61, a carry-out side suction unit 63, and a fan 65 (see FIG. 5). The carry-in side suction unit 61 has a carry-in side suction port 611, a carry-in side partition wall 612, and an exhaust pipe 613. Further, the carry-out side suction unit 63 has a carry-out side suction port 631, a carry-out side partition wall 632, and an exhaust pipe 633.

The carry-in side suction port 611 is provided on the upstream side of the carry-in port 41 of the processing chamber 40. The carry-out side suction port 631 is provided on the downstream side of the carry-out port 42 of the processing chamber 40. The carry-in side suction port 611 is connected to the exhaust pipe 613, and the carry-out side suction port 631 is connected to the exhaust pipe 633. The exhaust pipes 613 and 633 communicate with the outside of the apparatus housing 90 via the fan 65. The fan 65 generates an air flow from the inside of the exhaust pipes 613 and 633 to the outside of the apparatus housing 90. The air discharge unit 60 sucks the atmosphere around the recording medium 9 on the transport path TR1 from the carry-in side suction port 611 and the carry-out side suction port 631 by the action of the fan 65. More specifically, the carry-in side suction unit 61 sucks the atmosphere between the outer peripheral surface 13S of the chill roller 13 and the carry-in side partition wall 612, and the carry-out side suction part 63 sucks the atmosphere between the outer peripheral surface 13S and the carry-out side partition wall 632. Inhale the atmosphere of. The atmosphere sucked from the carry-in side suction port 611 and the carry-out side suction port 631 is guided to the outside of the device housing 90 by the exhaust pipes 613 and 633, and then discharged. The step in which the air discharge unit 60 sucks the atmosphere around the recording medium 9 from the carry-in side suction port 611 and the carry-out side suction port 631 and discharges the atmosphere to the outside of the apparatus housing 90 is an example of the air discharge process. .. It is not essential that the fan 65 is provided in the main body of the inkjet printing device 1. For example, the fan 65 may be omitted, and the exhaust side ends of the exhaust pipes 613 and 633 may be configured to be connectable to a suction source outside the apparatus.

As shown in FIG. 3, the exhaust pipe 613 is connected to the back surface of the carry-in side partition wall 612 (the surface opposite to the transport path TR), and the exhaust pipe 633 is connected to the back surface of the carry-out side partition wall 632. In this example, as shown in FIG. 4, the exhaust pipe 613 is connected to the carry-in side partition wall 612 at one place. For example, when the connection portion of the exhaust pipe 613 is branched into a plurality of parts, the carry-in side partition wall is connected. It may be connected to 612 at a plurality of locations different in the width direction. The same applies to the exhaust pipe 633.

The carry-in side partition wall 612 is a member having a portion facing the recording surface 9a of the recording medium 9 on the transport path TR1, and in this example, has a portion facing the outer peripheral surface 13S of the chill roller 13. As shown in FIG. 3, the carry-in side partition wall 612 has a U-shape that opens toward the outer peripheral surface 13S of the chill roller 13 in a cross-sectional view, and forms a first suction space 61R inside. The carry-in side suction port 611 opens on the carry-in side partition wall 612 on the transport path TR1 side. In this example, the carry-in side suction port 611 is provided on the surface of the carry-in side partition wall 612 facing the chill roller 13. The downstream end of the carry-in side partition wall 612 is connected to the carry-in inlet 41 of the processing chamber 40, that is, the upstream end of the first wall 43. The upstream end of the carry-in side partition wall 612 is separated from the chill roller 13 by a predetermined distance, and constitutes an inlet 614 for allowing the recording medium 9 to enter the carry-in side suction portion 61. As shown in FIG. 4, the width direction dimension of the carry-in side partition wall 612 is substantially the same as the width direction dimension of the chill roller 13, for example.

The height dimension from the outer peripheral surface 13S of the chill roller 13 to the carry-in side suction port 611 is larger than the height dimension of the carry-in inlet 41 (height dimension from the outer peripheral surface 13S to the first facing surface 43S). The height dimension from the outer peripheral surface 13S to the carry-out side suction port 631 is larger than the height dimension of the carry-out outlet 42 (height dimension from the outer peripheral surface 13S to the second facing surface 44S).

The carry-out side partition wall 632 is a member having a portion facing the recording surface 9a of the recording medium 9 on the transport path TR1, and in this example, has a portion facing the outer peripheral surface 13S of the chill roller 13. As shown in FIG. 3, the carry-out side partition wall 632 has a U-shape that opens toward the outer peripheral surface 13S of the chill roller 13 in a cross-sectional view, and forms a second suction space 63R inside. The carry-out side suction port 631 opens on the transport path TR1 side of the carry-out side partition wall 632. In this example, the carry-out side suction port 631 is provided on the surface of the carry-out side partition wall 632 facing the chill roller 13. The upstream end of the carry-out side partition wall 632 is connected to the carry-out port 42 of the processing chamber 40, that is, the downstream end of the second wall 44. The downstream end of the carry-out side partition wall 632 is arranged apart from the chill roller 13, and constitutes an outlet 634 for discharging the recording medium 9 from the carry-out side suction portion 63. Although not shown, the width direction dimension of the carry-out side partition wall 632 is substantially the same as the width direction dimension of the chill roller 13 like, for example, the carry-in side partition wall 612.

The width direction dimension of the carry-in side suction port 611 can be substantially the same as, for example, the width direction dimension of the carry-in inlet 41 (in this example, the width dimension between the two side walls 133) (see FIG. 4). In this case, the atmosphere containing the inert gas flowing out from the inside of the processing chamber 40 can be sucked over the entire width direction of the carry-in inlet 41. Similarly, the width direction dimension of the carry-out side suction port 631 can be substantially the same as, for example, the width direction dimension of the carry-out outlet 42 (in this example, the width dimension between the two side wall 133s) (see FIG. 4). In this case, the atmosphere (including the inert gas) flowing out from the inside of the processing chamber 40 through the carry-out port 42 can be sucked over the entire width direction of the carry-out port 42.

It is not essential that the suction port 611 on the carry-in side is a single opening extending in the width direction, and may be, for example, a plurality of openings dispersedly arranged at a plurality of locations in the width direction. Similarly, the carry-out side suction port 631 may not be a single opening extending in the width direction, but may be a plurality of openings dispersedly arranged at a plurality of locations in the width direction.

The shape and size of the carry-in side partition wall 612 are not particularly limited as long as they have a portion facing the transport path TR1. However, the pressure loss in the processing chamber 40 is preferably larger than the pressure loss in the carry-in side suction portion 61 (in the first suction space 61R surrounded by the carry-in side partition wall 612). Therefore, for example, the height dimension of the carry-in inlet 41 (distance between the outer peripheral surface 13S and the first facing surface 43S) may be smaller than the height dimension of the inlet 614. Further, the pressure loss of the processing chamber 40 may be increased by increasing the size of the first flow path 46a or the second flow path 46b in the moving direction. By making the pressure loss of the processing chamber 40 larger than the pressure loss of the suction unit 61 on the carry-in side in this way, the inert gas in the processing chamber 40 is less likely to flow out. Therefore, the concentration of the inert gas in the processing chamber 40 can be easily increased. Further, since the atmosphere easily flows into the space of the carry-in side partition wall 612, the atmosphere can be satisfactorily sucked at the carry-in side suction port 611. Therefore, the inert gas flowing out from the processing chamber 40 through the carry-in inlet 41 can be satisfactorily sucked by the carry-in side suction unit 61.

The shape and size of the carry-out side partition wall 632 are not particularly limited as long as they have a portion facing the transport path TR1. However, like the carry-in side partition wall 612, the pressure loss in the processing chamber 40 is preferably larger than the pressure loss in the carry-out side suction portion 63 (in the second suction space 63R surrounded by the carry-out side partition wall 632). Therefore, for example, the height dimension of the carry-out port 42 (distance between the outer peripheral surface 13S and the second facing surface 44S) may be smaller than the height dimension of the inlet 614. By making the pressure loss in the processing chamber 40 larger than the pressure loss in the suction side suction unit 63, the atmosphere can easily flow into the second suction space 63R. Therefore, the atmosphere can be satisfactorily sucked at the carry-out side suction port 631. Therefore, the inert gas flowing out from the processing chamber 40 through the carry-out port 42 can be satisfactorily sucked by the carry-out side suction unit 63.

The irradiation unit 70 is arranged on the downstream side of the inert gas supply unit 50 and substantially vertically below the chill roller 13. Further, the irradiation unit 70 is arranged directly below the processing chamber 40. The irradiation unit 70 performs an irradiation process of irradiating the recording medium 9 supported by the chill roller 13 with irradiation light. The irradiation unit 70 of the present embodiment includes a metal halide lamp 71 and a reflector 72. The metal halide lamp 71 is a tubular light source extending in the width direction.

The irradiation light emitted from the metal halide lamp 71 includes ultraviolet rays in a wavelength band effective for curing the ink ejected from the ejection head 21. Further, the irradiation light emitted from the metal halide lamp 71 has a sufficient amount of light to completely cure the ink. When the ink on the recording medium 9 is irradiated, the ink is cured and the ink is fixed on the recording medium 9. As a result, the image is recorded on the recording surface 9a of the recording medium 9. The step in which the irradiation unit 70 irradiates the recording surface 9a of the recording medium 9 with ultraviolet rays inside the processing chamber 40 is an example of the irradiation step.

A third wall portion 45 of the processing chamber 40 is arranged between the irradiation portion 70 and the chill roller 13. The third wall portion 45 is made of a material that allows the transmission of ultraviolet rays. The material of the first wall portion 43 and the second wall portion 44 is not particularly limited, but the first facing surface 43S and the second facing surface 44S are preferably made of rubber. In this case, when a foreign substance adheres to the recording surface 9a of the recording medium 9, the first facing surface 43S or the second facing surface 44S is damaged by hitting the foreign substance, or the recording medium 9 is damaged. Can be suppressed.

When the recording medium 9 passes through the inert gas supply unit 50, it is conveyed while being cooled by the chill roller 13. The irradiation process by the irradiation unit 70 is performed on the recording medium 9 conveyed by the chill roller 13. In this case, the temperature rise of the recording medium 9 due to the irradiation treatment is suppressed. The recording medium 9 is bent in the direction opposite to the recording surface 9a by the chill roller 13 to switch the traveling direction. The switching angle of the traveling direction by the chill roller 13 is preferably 180 degrees or more. In this case, the recording medium 9 is sufficiently cooled because the contact time with the chill roller 13 is long. Therefore, the temperature rise of the recording medium 9 due to the irradiation treatment is further suppressed. Tension is applied to the recording medium 9 by the chill roller 13. Therefore, it is possible to prevent the recording medium 9 from being loosened or wrinkled due to thermal expansion. The recording medium 9 that has passed through the irradiation unit 70 is collected by the winding unit 14 via a plurality of transport rollers 12 including the chill roller 13 and the nip roller 122.

FIG. 5 is a diagram showing an electrical connection configuration between the control unit 80 and each unit in the inkjet printing device 1. The control unit 80 is composed of a computer having an arithmetic processing unit 81 such as a CPU, a memory 82 such as a RAM, and a storage unit 83 such as a hard disk drive. The control unit 80 is electrically connected to the unwinding unit 11, the winding unit 14, the four discharge heads 21, the oxygen concentration meter 47, the on-off valve 53, the fan 65, the irradiation unit 70, and the nip roller 122, respectively. The control unit 80 temporarily reads the computer program P stored in the storage unit 83 into the memory 82, and the arithmetic processing unit 81 performs arithmetic processing based on the computer program P to perform the operation of each of the above units. Control. By this control, the printing process in the inkjet printing apparatus 1 proceeds.

The control unit 80 is electrically connected to the server 2 installed outside the inkjet printing device 1. The image data D to be printed is stored in the server 2. At the time of printing processing, the recording medium 9 is conveyed by the transfer mechanism 10, and the control unit 80 reads the designated image data D from the server 2, and based on the image data D, inks of each color from each ejection head 21. Is discharged. As a result, the image corresponding to the image data D is recorded on the recording surface 9a of the recording medium 9. The image data D may be provided to the control unit 80 without going through the server 2.

According to the inkjet printing device 1, the inert gas flowing out from the carry-in inlet 41 and the carry-out port 42 of the processing chamber 40 is discharged to the outside of the device housing 90 through the carry-in side suction port 611 and the carry-out side suction port 631. be able to. Therefore, when the inert gas flowing out of the processing chamber 40 moves to the vicinity of the ejection head 21 on the upstream side, it is possible to prevent the characteristics such as the wettability of the ink adhering to the recording medium 9 from changing. As a result, deterioration of print quality can be reduced.

As shown in FIG. 3, when the carry-in side partition wall 612 is connected to the carry-in inlet 41, the inert gas flowing out from the carry-in inlet 41 is good through the carry-in side suction port 611 provided in the carry-in side partition wall 612. Can be sucked into. Similarly, when the carry-out side partition wall 632 is connected to the carry-out port 42, the inert gas flowing out from the carry-out port 42 is satisfactorily sucked through the carry-out side suction port 631 provided in the carry-out side partition wall 632. can do. By these actions, the inert gas flowing out of the processing chamber 40 can be effectively discharged to the outside of the apparatus housing 90.

When the carry-in side suction port 611 and the carry-out side suction port 631 face the outer peripheral surface 13S of the chill roller 13, the inert gas that flows out from the processing chamber 40 through the carry-in inlet 41 and the carry-out port 42 onto the recording surface 9a of the recording medium 9. Can be sucked well.

The control unit 80 controls the on-off valve 53 to control the amount of the inert gas supplied into the processing chamber 40 per unit time. By controlling the fan 65, the control unit 80 controls the amount of air discharged from the air discharge unit 60 per unit time. For example, the control unit 80 controls the on-off valve 53 and the fan 65 to supply the amount of air discharged per unit time by the air discharge unit 60 and the amount of the inert gas discharged by the inert gas supply unit 50 per unit time. It may be larger than the amount. In this case, the air discharge unit 60 can discharge more atmosphere than the amount of the inert gas supplied to the processing chamber 40. As a result, it is possible to effectively prevent the inert gas flowing out from the processing chamber 40 through the carry-in inlet 41 or the carry-out outlet 42 from moving to the vicinity of the discharge head 21 of the image recording unit 20.

The control unit 80 may control the discharge amount of the atmosphere by the air discharge unit 60 per unit time according to the output from the oxygen concentration meter 47. For example, if the amount of air discharged by the air discharging unit 60 is too large, the inert gas flows out from the processing chamber 40 more than necessary, so that the oxygen concentration in the processing chamber 40 rises relatively and the ink curing speed. May affect. Therefore, for example, the control unit 80 may control the fan 65 so as to reduce the discharge amount when the output of the oxygen concentration meter 47 exceeds a predetermined reference value. On the contrary, the fan 65 may be controlled so as to increase the discharge amount when the output of the oxygen concentration meter 47 falls below a predetermined reference value. As a result, the amount of air discharged by the air discharging unit can be controlled according to the oxygen concentration in the processing chamber, so that the oxygen concentration in the processing chamber 40 can be maintained at a value suitable for ink curing. Further, the control unit 80 may control the on-off valve 53 together with the fan 65 according to the output of the oxygen concentration meter 47.

<2. Modification example>
Although the embodiments have been described above, the present invention is not limited to the above, and various modifications can be made.

For example, the above-mentioned inkjet printing apparatus 1 records an image on printing paper as a recording medium. However, the inkjet printing apparatus of the present invention may record an image on a strip-shaped recording medium (for example, a resin film or the like) other than general paper.

In the above embodiment, an inexpensive nitrogen gas is used as the inert gas supplied from the supply unit. However, the inert gas may be another gas such as helium or argon, or a mixed gas thereof. Further, in the above embodiment, the electromagnetic wave emitted from the irradiation unit is ultraviolet light. However, the irradiation unit may irradiate an electromagnetic wave other than ultraviolet light.

In the above embodiment, the transport mechanism 10 is a roll-to-roll system, but the transport mechanism of the present invention is not limited to this system. For example, the transport mechanism may be a suction transport method in which a belt is wound around a pair of rollers and a suction means is provided on the belt to suck and transport the recording medium. When the transport mechanism is an adsorption transport method, it may be a single-wafer recording medium instead of a strip-shaped recording medium.

Although the present invention has been described in detail, the above description is exemplary in all aspects and the invention is not limited thereto. It is understood that a myriad of variations not illustrated can be envisioned without departing from the scope of the invention. The configurations described in the above embodiments and the modifications can be appropriately combined or omitted as long as they do not conflict with each other.

1 Inkjet printing device 10 Conveyance mechanism 13 Chill roller 130 Cooling water 13S Outer peripheral surface 20 Image recording unit 21 Discharge head 40 Processing room 40R Processing space 41 Carry-in port 42 Carry-out port 47 Oxygen concentration meter 50 Inactive gas supply part 60 Air discharge part 61 Carry-in Side suction part 611 Carry-in side suction port 612 Carry-in side partition 613, 631 Exhaust pipe 61R 1st suction space 63 Carry-out side suction part 631 Carry-out side suction port 632 Carry-out side partition 63R 2nd suction space 65 Fan 70 Irradiation part 80 Control part 9 Recording medium 9a Recording surface 90 Equipment housing TR1 Transport path

Claims (12)

An inkjet printing device that records images by ejecting electromagnetic wave curable ink onto a recording medium.
A transport mechanism that transports the recording medium along a predetermined transport path, and
An ejection head that ejects ink to the recording medium,
A processing chamber arranged on the downstream side of the discharge head and having a carry-in inlet and a carry-out outlet for passing the recording medium.
An irradiation unit that irradiates the recording medium inside the processing chamber with electromagnetic waves,
An inert gas supply unit that supplies the inert gas to the inside of the processing chamber,
A device housing that houses the discharge head and the processing chamber, and
The carry-in side suction port provided on the upstream side of the carry-in entrance of the processing chamber, the carry-out side suction port provided on the downstream side of the carry-out outlet of the processing room, and the carry-in side suction port and the carry-out side suction. An air discharge unit including an exhaust pipe that guides the atmosphere sucked from the mouth to the outside of the device housing,
A device for inkjet printing. The inkjet printing apparatus according to claim 1.
A carry-in side bulkhead, which is connected to the carry-in inlet of the processing chamber and has a portion facing the transport path.
With more
An inkjet printing device in which the carry-in side suction port opens on the recording medium side of the carry-in side partition wall. The inkjet printing apparatus according to claim 2.
An inkjet printing apparatus in which the pressure loss in the processing chamber is larger than the pressure loss in the first suction space surrounded by the carry-in side partition wall. The inkjet printing apparatus according to any one of claims 1 to 3.
A carry-out side bulkhead, which is connected to the carry-out port of the processing chamber and has a portion facing the transport path.
With more
An inkjet printing device in which the carry-out side suction port opens on the carry-out path side of the carry-out side partition wall. The inkjet printing apparatus according to claim 4.
An inkjet printing apparatus in which the pressure loss in the processing chamber is larger than the pressure loss in the space surrounded by the carry-out side partition wall. The inkjet printing apparatus according to any one of claims 1 to 5.
A roller having a cylindrical outer peripheral surface around which the recording medium is wound,
With more
The inert gas supply unit is an inkjet printing device that discharges the inert gas toward the roller. The inkjet printing apparatus according to claim 6.
An inkjet printing device in which at least one of the carry-in side suction port and the carry-out side suction port faces the outer peripheral surface of the roller. The inkjet printing apparatus according to claim 6 or 7.
An inkjet printing device in which the rollers have a cooling mechanism for cooling the outer peripheral surface. The inkjet printing apparatus according to any one of claims 1 to 8.
An inkjet printing apparatus in which the amount of the atmosphere discharged per unit time by the air discharging unit is larger than the amount of the inert gas supplied per unit time by the inert gas supply unit. The inkjet printing apparatus according to any one of claims 1 to 9.
An oxygen densitometer that measures the oxygen concentration in the processing chamber,
An inkjet printing device further equipped with. The inkjet printing apparatus according to claim 10.
A control unit that controls the amount of air discharged by the air discharge unit according to the output from the oxygen meter.
An inkjet printing device further equipped with. It is an inkjet printing method that records an image by ejecting electromagnetic wave curable ink onto a recording medium.
(A) A transport process in which the recording medium is transported along a predetermined transport path, and
(B) An ink ejection process for ejecting ink from the ejection head to the recording medium,
(C) A carry-in step of carrying the recording medium into the inside of the processing chamber through a carry-in inlet of the processing chamber arranged on the downstream side of the discharge head.
(D) An irradiation step of irradiating the recording medium with electromagnetic waves inside the processing chamber,
(E) An inert gas supply step of supplying the inert gas to the inside of the processing chamber,
(F) A unloading step of unloading the recording medium to the outside of the processing chamber through the unloading port of the processing chamber.
(G) Atmosphere is sucked from each of the carry-in side suction port provided on the upstream side of the carry-in port of the processing chamber and the carry-out side suction port provided on the downstream side of the carry-out port of the processing room. An air discharge process for discharging the discharge head and the outside of the apparatus housing in which the processing chamber is housed,
Including inkjet printing methods.

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