Printing device

Abstract

To provide a printing device that can improve efficiency in drying a printing medium, while avoiding increase in energy that is required in drying.SOLUTION: A printing device 1 makes a guide roller R and a path change roller 33 convey a continuous paper WP to a print surface contact roller 29 spirally. In a first section, the continuous paper WP is heated to be dried by heating units H1-H4 arranged to be opposed to one another. A path in a second section closer to a downstream side than the first section is bent and changed by the path change roller 33, which elongates the path for the continuous paper WP in the second section. In the first section, the continuous paper WP is heated by the heating units H1-H4, so that the continuous paper WP is heated to a highest temperature in the second section. Therefore, the continuous paper WP can be dried more efficiently in the second section, by elongating the path in the second section. This can improve efficiency in drying the continuous paper WP, without increasing energy that is required in drying.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus that prints on a long print medium. [Background technology]

[0002] The printing device includes a drying mechanism for drying ink adhered to a print medium (e.g., continuous paper). The drying mechanism uses, for example, a heating drum, a blower, and an infrared heater to heat the print medium to which the ink for printing is adhered, thereby drying the ink.

[0003] The following configuration has been proposed as a conventional drying mechanism for drying ink (see, for example, Patent Document 1). Specifically, a print medium with ink on its front side is guided into the drying mechanism via an entrance. The back side (non-printing side) of the print medium is then brought into contact with multiple direction-changing rollers, and the print medium is conveyed in a spiral shape by being changed in direction by each direction-changing roller. A heating unit is disposed between each direction-changing roller so as to face the printing surface of the print medium. Each heating unit uses a blower or infrared heating unit to heat the printing surface of the print medium and dry the ink. Specifically, the print medium is heated sequentially by the multiple heating units while being changed in direction by the multiple direction-changing rollers in a spiral shape.

[0004] The print medium, transported in a spiral shape while being heated by the heating unit, is guided to the print surface contact roller. The print surface contact roller is the roller that first comes into contact with the print surface of the print medium after ink has adhered to the print medium. Therefore, the process of drying the print surface to which ink has adhered is completed by the time the print medium is transported to the print surface contact roller. Then, when the print surface contact roller comes into contact with the print surface of the print medium, the print medium is folded back and guided toward the exit of the drying mechanism. In this way, by configuring the print medium transport path to be heated while being arranged in a spiral shape, the drying mechanism can be made smaller. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-037537 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional examples with such a configuration have the following problems. In recent years, improvements in productivity and print quality in printing devices have required further improvements in the drying efficiency of print media. Common methods for improving drying efficiency include increasing the heating temperature of the heating unit or increasing the number of heating units. However, these methods increase the energy required for drying, and there are concerns that the increased number of heating units will result in an increase in the size of the drying mechanism. In other words, with conventional devices, it is difficult to sufficiently improve drying efficiency while avoiding an increase in the energy required for drying.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a printing device that can improve the drying efficiency of the print medium while avoiding an increase in the energy required for drying. [Means for solving the problem]

[0008] The inventors of the present invention have investigated the above problem and have come to the following conclusion. Specifically, in a printing device with a conventional configuration, the temperature of the print medium gradually increases as it is transported in a spiral pattern and heated sequentially by multiple heating units. Specifically, the temperature of the print medium guided into the drying mechanism is highest in the area between the direction-diverting roller (hereinafter referred to as the "final direction-diverting roller") located immediately downstream of the heating unit that heats the print medium last, and the print surface contact roller. In other words, the ink on the print medium dries most efficiently in the area between the final direction-diverting roller and the print surface contact roller. However, in conventional drying mechanisms, the path of the print medium between the final direction-diverting roller and the print surface contact roller is short, which is thought to prevent sufficient improvement in the drying efficiency of the print medium.

[0009] In order to achieve the above object, the present invention has the following configuration. That is, a printing device according to the present invention comprises a printing section that applies ink to the printing surface of a long print medium being transported, and a drying mechanism that heats the print medium transported from the printing section to dry the ink, the drying mechanism comprising a plurality of direction-changing rollers that come into contact with the back surface of the print medium transported from the printing section, on which no ink has been deposited, to change the transport direction of the print medium multiple times and transport the print medium in a spiral shape, a plurality of drying units that are arranged to face the printing surface of the print medium transported in a spiral shape and heat the print medium to dry the ink, and a drying mechanism that heats the print medium to dry the ink within the spiral transport section of the print medium. The printing surface contact roller is located downstream of a first section, which is a transport section in which the multiple drying units are arranged, and first comes into contact with the printing surface of the printing medium and folds the printing medium back; and a path changing roller is located in a second section, which is a section in which the printing medium is transported from the direction changing roller, which is located downstream of the first section and closest to the first section, to the printing surface contact roller, and contacts the back side of the printing medium in the second section to bend and change the transport path of the printing medium.

[0010] [Operations and Effects] In the printing device according to the present invention, a long print medium is conveyed in a spiral shape while being changed in direction by multiple direction-changing rollers contacting the backside of the print medium. In the first section of the spiral conveyance section, multiple drying units are arranged facing the printing surface of the print medium, and the drying units heat the print medium to dry the ink. A print surface contact roller is arranged downstream of the first section, and when the print surface contact roller first contacts the printing surface of the print medium conveyed in a spiral shape in the first section, the conveyance direction of the print medium is reversed.

[0011] In addition, a path-changing roller is disposed in the second section, downstream of the first section and where the print medium is transported from the direction-changing roller located closest to the first section to the print surface contact roller. The path-changing roller contacts the back side of the print medium in the second section, bending and changing the print medium transport path. In other words, compared to the straight path from the direction-changing roller located closest to the first section to the print surface contact roller, the path-changing roller changes the print medium transport path, thereby lengthening the print medium transport path in the second section. The second section is the section where the print medium is heated by all of the multiple drying units and reaches its highest temperature. Therefore, by lengthening the print medium in the second section, the print medium is dried more efficiently in the second section. As a result, the drying efficiency of the print medium can be improved without making design changes that increase the energy required for drying, such as installing a new drying unit or increasing the heating temperature of the drying unit.

[0012] In the above-described invention, it is preferable that the path changing roller changes the transport path of the print medium in the second section so that the print medium faces one of the drying units.

[0013] [Operations and Effects] In the printing device according to the present invention, the path change roller changes the transport path of the print medium in the second section so that the print medium faces one of the drying units. By having the print medium in the second section face one of the drying units, the drying unit that heats the print medium in the first section also heats the print medium in the second section. As a result, the drying efficiency of the print medium in the second section can be further improved without the need to install a new drying unit.

[0014] In the above-described invention, it is preferable that the path changing roller changes the transport path of the print medium in the second section so that the printed surface of the print medium faces one of the drying units.

[0015] [Actions and Effects] In the printing device according to the present invention, the path change roller changes the transport path of the print medium in the second section so that the printed surface of the print medium faces one of the drying units. By having the print medium in the second section face one of the drying units, the drying unit that heats the print medium in the first section also heats the printed surface of the print medium in the second section. By having the drying unit heat the printed surface of the print medium, the drying efficiency of the ink adhering to the printed surface is further improved. As a result, the drying efficiency of the print medium in the second section can be further improved without the need to install a new drying unit.

[0016] In the above-described invention, it is preferable that the transport path of the print medium in the second section is arranged so as to be surrounded by the transport path of the print medium in the first section.

[0017] [Actions and Effects] In the printing device according to the present invention, the print media transport path in the second section is arranged so that it is surrounded by the print media transport path in the first section. This arrangement allows the heat transferred from the drying unit to the print media in the first section to be efficiently transferred to the second section, which is surrounded by the first section. This further improves the drying efficiency of the print media without increasing the energy required for drying. Furthermore, the compact print media transport path allows for the miniaturization of the printing device.

[0018] In the above-described invention, it is preferable that the printer further comprises a ventilation section that is arranged along the width direction of the print medium transported through the second section and that ventilates the gas.

[0019] [Actions and Effects] The printing device according to the present invention is equipped with a ventilation unit that ventilates gas. The ventilation unit is arranged along the width direction of the print medium transported through the second section. Even if steam evaporated from the print medium in the second section remains in the second section, the ventilation unit ventilates the print medium and efficiently removes the steam remaining around the print medium in the second section. As a result, the drying efficiency of the print medium in the second section can be further improved.

[0020] In the above-described invention, the ventilation section is preferably configured to supply gas heated by the drying unit to the second section.

[0021] [Operations and Effects] In the printing device according to the present invention, the gas heated by the drying unit is supplied to the second zone by the ventilation section. In this case, the gas supplied from the drying unit has low humidity and high temperature, so the humidity in the second zone can be efficiently reduced. This further improves the drying efficiency of the print medium in the second zone.

[0022] In the above-described invention, the ventilation section is preferably configured to exhaust gas from the second section.

[0023] [Operation and Effect] In the printing device according to the present invention, the ventilation section is configured to exhaust gas from the second section. In this case, steam remaining in the second section is efficiently exhausted by the ventilation section. This further improves the drying efficiency of the print medium in the second section.

[0024] In the above-described invention, it is preferable to further include a gas circulation section that circulates the gas discharged by the ventilation section inside the drying mechanism.

[0025] [Operation and Effect] In the printing device according to the present invention, the gas discharged by the ventilation section is circulated inside the drying mechanism by the gas circulation section. This configuration reduces the amount of exhaust gas in the drying mechanism.

[0026] In the above-described invention, it is preferable that the ventilation section is disposed at a position sandwiched between the printing surface of the printing medium in the second section and the printing surface of the printing medium downstream of the second section.

[0027] [Operations and Effects] In the printing device according to the present invention, a ventilation section is disposed between the printing surface of the printing medium in the second section and the printing surface of the printing medium downstream of the second section. This configuration allows steam that accumulates near the printing medium due to the drying of the printing surface of each printing medium to be ventilated and removed from both sides of the ventilation section. In other words, the efficiency of steam removal can be further improved, allowing the printing medium to dry more efficiently. [Effects of the Invention]

[0028] According to the printing device of the present invention, a long print medium is transported in a spiral shape while being changed in direction by multiple direction-changing rollers contacting the backside of the print medium. In a first section of the spiral transport section, multiple drying units are arranged facing the printing surface of the print medium, and the drying units heat the print medium to dry the ink. A print surface contact roller is arranged downstream of the first section, and when the print surface contact roller first contacts the printing surface of the print medium transported in a spiral shape in the first section, the transport direction of the print medium is reversed.

[0029] In addition, a path-changing roller is disposed in the second section, downstream of the first section and where the print medium is transported from the direction-changing roller located closest to the first section to the print surface contact roller. The path-changing roller contacts the back side of the print medium in the second section, bending and changing the print medium transport path. In other words, compared to the straight path from the direction-changing roller located closest to the first section to the print surface contact roller, the path-changing roller changes the print medium transport path, thereby lengthening the print medium transport path in the second section. The second section is the section where the print medium is heated by all of the multiple drying units and reaches its highest temperature. Therefore, by lengthening the print medium in the second section, the print medium is dried more efficiently in the second section. As a result, the drying efficiency of the print medium can be improved without making design changes that increase the energy required for drying, such as installing a new drying unit or increasing the heating temperature of the drying unit. This improves the drying efficiency of the print medium while avoiding an increase in the energy required for drying. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a printing device according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of a drying mechanism according to the first embodiment. [Figure 3] 3 is a diagram showing an outline of a path of the continuous paper in the drying mechanism according to the first embodiment. FIG. [Figure 4]1A and 1B are diagrams illustrating the configuration of a heating unit according to Example 1. FIG. 1A is a vertical cross-sectional view of the heating unit along the width direction of the continuous paper, and FIG. 1B is a vertical cross-sectional view of the heating unit along the transport direction of the continuous paper. [Figure 5] FIG. 4 is a cross-sectional view taken along the line AA in FIG. [Figure 6] FIG. 3 is a diagram showing an example of an air discharge path according to the first embodiment. [Figure 7] 4A and 4B are diagrams illustrating the effect of the drying mechanism according to the first embodiment. [Figure 8] FIG. 10 is a diagram showing an outline of a path of the continuous paper in the drying mechanism according to the second embodiment. [Figure 9] FIG. 10 is a diagram showing an example of an air supply path according to a third embodiment. [Figure 10] FIG. 10 is a cross-sectional view taken along the arrow BB in FIG. 9. [Figure 11] FIG. 10 is a diagram showing the configuration of a drying mechanism according to a modified example. [Figure 12] FIG. 10 is a cross-sectional view showing the configuration of a drying mechanism according to a modified example. [Figure 13] FIG. 10 is a diagram showing the configuration of a drying mechanism according to a modified example. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0031] A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a schematic diagram showing the overall configuration of a printing device 1 according to the first embodiment. Fig. 2 is a diagram showing a drying mechanism 21 according to the first embodiment. Fig. 3 is a diagram showing a main part of the drying mechanism 21 according to the first embodiment.

[0032] <Explanation of overall configuration> 1, the printing device 1 of this embodiment is an inkjet printing device, and includes a paper feed unit 3, a printing device main body 5, and a paper discharge unit 7.

[0033] The paper feed unit 3 holds a roll of continuous paper (ream paper) WP so that it can rotate around a horizontal axis. The paper feed unit 3 supplies the continuous paper WP from the roll to the printing device main body 5. The printing device main body 5 prints on the long continuous paper WP. The paper discharge unit 7 then takes up the continuous paper WP printed by the printing device main body 5 around a horizontal axis. The paper discharge unit 7 is equipped with an electric motor for winding up the continuous paper WP. If the supply side of the continuous paper WP is considered upstream and the discharge side of the continuous paper WP is considered downstream, the paper feed unit 3 is located upstream of the printing device main body 5. The continuous paper WP corresponds to the printing medium of the present invention.

[0034] The printing device main body 5 is equipped with a drive roller 9, a drive roller 11, multiple transport rollers 13, and a nip roller 15. The drive roller 9 is located on the entrance side of the printing device main body 5. The drive roller 11 is located on the exit side of the printing device main body 5. The drive roller 9 and the drive roller 11 are each rotatably supported and driven by an electric motor. The drive roller 9 takes in the continuous paper WP from the paper feed unit 3. The drive roller 11 sends the continuous paper WP to the paper discharge unit 7. The drive roller 9 and the drive roller 11 each provide power to the continuous paper WP for transport. The multiple transport rollers 13 are rotatably supported and are rollers that guide the continuous paper WP. They are driven rollers that rotate passively by coming into contact with the moving continuous paper WP. Unlike the drive roller 11, the multiple transport rollers 13 do not have an electric motor and do not provide power to transport the continuous paper WP.

[0035] The printing device main body 5 also includes a printing unit 19, a drying mechanism 21, a cooling unit 23, and an inspection unit 25, in this order from the upstream side.

[0036] The printing unit 19 deposits ink (ink droplets) onto the printing surface FF of the transported web paper WP. The printing unit 19 includes, for example, four inkjet heads 19A to 19D. The four inkjet heads 19A to 19D eject ink droplets using, for example, a piezoelectric element method or a thermal (bubble) method. The most upstream inkjet head 19A ejects black (K) ink droplets. The next inkjet head 19B ejects cyan (C) ink droplets. The next inkjet head 19C ejects magenta (M) ink droplets. The next inkjet head 19D ejects yellow (Y) ink droplets.

[0037] In this example, the printing unit 19 includes four inkjet heads 19A to 19D, but is not limited to this. For example, the printing unit 19 may include one, two, or six inkjet heads.

[0038] The drying mechanism 21 heats the web paper WP that has been carried out (transported) from the printing unit 19 to dry the ink. The detailed configuration of the drying mechanism 21 will be described later. The cooling unit 23 cools the web paper WP that has been heated by the drying mechanism 21. The cooling unit 23 includes, for example, a water-cooled roller that has a built-in flow path for passing cooling water. The inspection unit 25 includes, for example, a CCD sensor or a CIS sensor (contact image sensor). The inspection unit 25 inspects the image printed on the web paper WP.

[0039] The printing device 1 includes a control unit 27 and a storage unit (e.g., memory) not shown. The control unit 27 includes a central processing unit (CPU). The control unit 27 controls each component of the printing device 1 (e.g., the printing unit 19 and the drying mechanism 21). The storage unit stores programs necessary for the operation of the printing device 1.

[0040] <Drying mechanism configuration> Next, the drying mechanism 21, which is a characteristic feature of the present invention, will be described with reference to Figures 2 and 3. Figure 3 is a schematic diagram showing the transport path of the web paper WP in the drying mechanism 21 in detail.

[0041] (A) Multiple roller configuration The drying mechanism 21 includes a guide roller R, a print surface contact roller 29, a transport roller 31, and a path change roller 33. The transport roller and print surface contact roller are referred to as "rollers" where appropriate. In the web paper WP, the print surface FF is the surface to which ink is applied by the printing unit 19. The back surface BF is the surface opposite the print surface FF, and is the surface to which no ink from the printing unit 19 is applied.

[0042] The guide roller R, printing surface contact roller 29, transport roller 31, and path changing roller 33 are driven rollers similar to the transport roller 13 described above. Specifically, each of the guide roller R, printing surface contact roller 29, transport roller 31, and path changing roller 33 is rotatably supported and guides the web paper WP. The guide roller R, printing surface contact roller 29, transport roller 31, and path changing roller 33 do not have electric motors and do not provide power for transporting the web paper WP, but rather rotate passively by contacting the moving web paper WP.

[0043] In the first embodiment, seven guide rollers R are provided. As shown in Figures 2 and 3, the guide rollers R are distinguished by being assigned the symbols R1 to R7 in order from the upstream side in the transport direction of the web paper WP. That is, of the multiple guide rollers R, guide roller R1 is located on the most upstream side, and guide roller R7 is located on the most downstream side.

[0044] Each of the guide rollers R comes into contact with the back surface BF of the web paper WP discharged from the printing unit 19 to change the transport direction of the web paper WP. The printing surface contact roller 29 is located downstream of the seven guide rollers R1 to R7. Of the multiple rollers provided in the drying mechanism 21 (printing device 1), the printing surface contact roller 29 is the first roller to come into contact with the printing surface FF of the web paper WP. The printing surface contact roller 29 also has the function of changing the transport direction of the web paper WP. The web paper WP discharged from the printing unit 19 and brought in through the entrance of the drying mechanism 21 is transported in a spiral manner by the guide rollers R1 to R7.

[0045] Here, the path along which the web paper WP is transported by guide rollers R1 to R7 will be described. First, the web paper WP discharged from the printing unit 19 is transported by transport roller 13A, guide roller R1, guide roller R2, and guide roller R3, in that order. Transport roller 13A and guide rollers R1 to R3 are located downstream of the printing unit 19, and are located in front of the printing unit 19 in a plan view.

[0046] The transport roller 13A is positioned downstream of the printing unit 19 (i.e., the most downstream inkjet head 19D) and upstream of the guide roller R3. The transport roller 13A is positioned near the inkjet head 19D. The transport roller 13A contacts the back surface BF of the web paper WP. The transport roller 13A, guide roller R1, and guide roller R2 each guide the web paper WP diagonally downward so that the printing surface FF of the web paper WP faces upward. The tilt angle (absolute value) of the web paper WP increases as it moves toward the guide roller R3. After being redirected by rollers 13A, R1, and R2, the web paper WP is redirected vertically downward by the guide roller R3.

[0047] After the web paper WP is transported to guide roller R3, it is transported by guide rollers R4, R5, R6, and R7 in that order. Guide roller R4 redirects the web paper WP, which has been redirected by guide roller R3, diagonally downward so that the printing surface FF of the web paper WP faces downward.

[0048] Guide roller R5 is positioned lower than guide roller R4. Guide roller R5 redirects the web paper WP diagonally upward so that the printing surface FF of the web paper WP faces downward.

[0049] Guide roller R6 is positioned higher than guide roller R5. Guide roller R6 is positioned at approximately the same height as guide roller R4. Guide roller R6 redirects the web paper WP, whose direction has been changed by guide roller R5, vertically upward.

[0050] Guide roller R7 is positioned higher than guide roller R6. Guide roller R7 is positioned at approximately the same height as guide roller R3. Guide roller R7 is also positioned between guide roller R6 and the web paper WP transported between transport roller 13A and guide roller R3. Guide roller R7 redirects the web paper WP, whose direction has been changed by guide roller R6, diagonally downward so that the printing surface FF faces upward.

[0051] As shown in Fig. 2, the four guide rollers R3, R4, R6, and R7 are arranged to form a substantially rectangular shape when viewed in the width direction perpendicular to the conveying direction TD of the web paper WP, which corresponds to the y direction in Fig. 1 and other figures.

[0052] 2, the printing surface contact roller 29 is disposed at a position surrounded by the four guide rollers R3, R4, R6, and R7. In other words, the printing surface contact roller 29 is disposed at a position surrounded by the web paper WP transported between guide roller R3 and guide roller R7.

[0053] The printing surface contact roller 29 is the roller that first comes into contact with the printing surface FF of the web paper WP after the ink has been applied. The printing surface contact roller 29 guides the web paper WP toward the exit of the drying mechanism 21 by folding back the web paper WP after the ink has dried. The guidance to the exit of the drying mechanism 21 is specifically performed by the printing surface contact roller 29 and the transport roller 31.

[0054] The transport rollers 31 are disposed downstream of the printing surface contact roller 29. In the first embodiment, nine transport rollers 31 are disposed in the drying mechanism 21. The nine transport rollers 31 guide the web paper WP folded back by the printing surface contact roller 29 to the outlet of the drying mechanism 21 while passing through a gap CL1 between the web paper WP transported between the transport roller 13A and the guide roller R3 and the web paper WP transported between the guide roller R7 and the printing surface contact roller 29.

[0055] Of the sections through which the web paper WP is transported, the transport section in which heating units H1 to H4, described below, are arranged will be referred to as the "first section." As shown in FIG. 3 and other figures, the portion of the web paper WP corresponding to the first section will be referred to as the web paper WPa. Guide rollers R1 to R6 transport the web paper WPa in the first section. Guide roller R7 is the guide roller R that is located downstream of the first section and closest to the first section.

[0056] Of the sections through which the web paper WP is transported, the section from guide roller R7 to printing surface contact roller 29 will be referred to as the "second section" hereinafter. Specifically, as shown in Figure 3, the section from contact point P2 between the web paper WP and guide roller R7 to contact point P3 between the web paper WP and printing surface contact roller 29 corresponds to the second section. As shown in Figure 3, the part of the web paper WP that corresponds to the second section will be referred to as web paper WPb.

[0057] Furthermore, of the sections through which the web paper WP is transported, the section transported by transport roller 31 will be referred to as the "third section" hereinafter. Specifically, as shown in Figure 3 etc., the section downstream of contact point P3 between the web paper WP and printing surface contact roller 29 corresponds to the third section. As shown in Figure 3 etc., the part of the web paper WP that corresponds to the third section will be referred to as web paper WPc.

[0058] Each of the path change rollers 33 is disposed downstream of each of the guide rollers R in the transport direction TD of the web paper WP, and upstream of the printing surface contact roller 29. That is, the path change rollers 33 are disposed downstream of the guide roller R7. Note that in the first embodiment, four path change rollers 33 are provided. As shown in FIG. 3, the path change rollers 33 are distinguished by being assigned the symbols 33A to 33D in order from the upstream side in the transport direction of the web paper WP. That is, of the multiple path change rollers 33, path change roller 33A is disposed furthest upstream, and path change roller 33D is disposed furthest downstream. Note that each of the guide rollers R and each of the path change rollers 33 correspond to the direction change rollers in the present invention.

[0059] Each of the path change rollers 33 comes into contact with the back surface BF of the web paper WPb in the second section, thereby changing the transport path of the web paper WPb in the second section. That is, by winding the web paper WPb around each of the path change rollers 33 in the second section, the transport path of the web paper WP is bent and changed from the straight path Wv shown by the dotted line in FIG. 3 to a path that bypasses the straight path Wv. The path that bypasses the straight path Wv, shown by the symbol WPb and the solid line in FIG. 3 and other figures, is longer than the straight path Wv. That is, each of the path change rollers 33 lengthens the path of the web paper WPb in the second section. Details of the transport path of the web paper WPb in the second section will be described later.

[0060] (B) Heating unit configuration The drying mechanism 21 also includes four heating units H1 to H4. The four heating units H1 to H4 heat the web paper WP that is guided into the drying mechanism 21. Heating unit H1, heating unit H2, heating unit H3, and heating unit H4 are arranged in this order along the transport path of the web paper WP. That is, of the four heating units H1 to H4, heating unit H1 is arranged on the most upstream side. The four heating units H1 to H4 heat the web paper WP in a non-contact manner.

[0061] The heating unit H1 is disposed between the guide rollers R1 and R2, facing the printing surface FF of the web paper WP. In other words, the heating unit H1 is disposed on the printing surface FF side of the web paper WP transported between the guide rollers R1 and R2.

[0062] Heating unit H2 is positioned between guide roller R2 and guide roller R3, facing the printing surface FF of the web paper WP. Heating unit H3 is positioned between guide roller R3 and guide roller R4, facing the printing surface FF of the web paper WP. Heating unit H4 is positioned between guide roller R6 and guide roller R7, facing the printing surface FF of the web paper WP. In other words, the four heating units H1 to H4 in this embodiment are not positioned to face the back surface BF of the web paper WP.

[0063] Furthermore, between guide roller R4 and guide roller R6, the web paper WP is transported without being heated by the heating unit. The reason for this is explained below. Between guide roller R4 and guide roller R6, the printing surface FF faces downward. Therefore, when the front surface of the heating unit (the surface on the heating side) faces the printing surface FF, the front surface of the heating unit faces upward. As a result, when the web paper WP slackens, the web paper WP comes into contact with the front surface of the heating unit and becomes overheated. Therefore, to prevent the web paper WP from being overheated, the web paper WP is transported between guide roller R4 and guide roller R6 without being heated by the heating unit.

[0064] In this way, each of the heating units H1 to H4 is arranged in the first section so as to face the printing surface FF of the web paper WP. By directly heating the web paper WP in the first section that it faces, the ink on the printing surface FF is dried. Each of the heating units H1 to H4 corresponds to the drying unit in the present invention.

[0065] As an example, each of the heating units H1 to H4 heats the printing surface FF of the web paper WP with infrared rays (electromagnetic waves). When heating the web paper WP with infrared rays, each of the heating units H1 to H4 is preferably arranged to heat the printing surface FF of the web paper WP transported between two adjacent guide rollers R. As an example, the heating unit H1 heats the web paper WP transported between adjacent guide rollers R1 and R2 with infrared rays. Here, the guide rollers R1 and R2 are configured so as not to enter the infrared radiation area (heating area) of the heating unit H1. By arranging the guide roller R so that it does not enter the heating area, it is possible to prevent the guide roller R from being heated excessively. The same applies to the other heating units H2 to H4.

[0066] Figure 4(a) is a vertical cross-sectional view of the heating unit H1 taken along the width direction WD of the web paper WP. Figure 4(b) is a vertical cross-sectional view of the heating unit H1 taken along the transport direction TD of the web paper WP. The width direction WD is perpendicular to the transport direction TD. The four heating units H1 to H4 have the same configuration. Therefore, the detailed configuration of the first heating unit H1 will be described as a representative of these.

[0067] The heating unit H1 includes multiple carbon heaters 35 that irradiate the web paper WP with infrared rays. The multiple carbon heaters 35 are arranged flat in the width direction WD. Each carbon heater 35 is formed in a rod shape and is arranged longitudinally in the transport direction TD. Therefore, the multiple carbon heaters 35 are arranged in a two-dimensional plane so as to be parallel to the web paper WP. Note that the first heating unit H1 may include a single carbon heater 35 instead of multiple heaters. In this case, the single carbon heater 35 is arranged in a two-dimensional plane by bending it.

[0068] The printing surface FF (ink and continuous paper WP) can be directly heated by irradiating it with infrared rays from the carbon heater 35. By using the carbon heater 35, it is possible to irradiate infrared rays with a wavelength that is optimal for heating (drying) the ink. In other words, the carbon heater 35 can irradiate infrared rays with a wavelength that is highly absorbed by water.

[0069] The multiple carbon heaters 35 are housed in a housing 37. The housing 37 is formed in a rectangular parallelepiped shape. A front surface 37A of the housing 37 is open. Note that a lattice fence (not shown) may be provided on the front surface 37A to prevent contact between the web paper WP and the carbon heaters 35.

[0070] The heating unit H1 includes a blower fan 39 and a guide plate 41. The blower fan 39 is provided on the side of the housing 37 and is driven by an electric motor. The blower fan 39 sends gas into the housing 37. This allows the gas heated by the carbon heater 35 and surrounding the carbon heater 35 to be sent to the printing surface FF. The guide plate 41 is provided inside the housing 37 and is configured to allow air to flow evenly from the front surface 37A of the housing 37. In other words, the first heating unit H1 is configured to heat the printing surface FF with radiant heat from the carbon heater 35 and to blow warm air onto the printing surface FF.

[0071] The heating unit H1 has two exhaust sections 43. The two exhaust sections 43 are provided on the upstream and downstream sides of the housing 37, which houses the carbon heater 35 and other components, so as to sandwich the housing 37 in the transport direction TD of the web paper WP. The openings of the two exhaust sections 43 face the printing surface FF. This allows hot air blown from the front surface 37A by the blower fan 39 to be exhausted on the upstream and downstream sides of the housing 37. The number of exhaust sections 43 in the heating unit H1 may be changed as appropriate.

[0072] As shown in FIGS. 2, 4(a), and 4(b), the printing apparatus 1 is also equipped with four reflectors RF1 to RF4. Reflector RF1 is located on the opposite side of heating unit H1, sandwiching the web paper WP transported between guide rollers R1 and R2. Similarly, reflector RF2 is located on the opposite side of heating unit H2, sandwiching the web paper WP transported between guide rollers R2 and R3. Reflector RF3 is located on the opposite side of heating unit H3, sandwiching the web paper WP transported between guide rollers R3 and R4. Reflector RF4 is located on the opposite side of heating unit H4, sandwiching the web paper WP transported between guide rollers R6 and R7.

[0073] Each of the four reflectors RF1 to RF4 is made of a shiny metal. Each of the four reflectors RF1 to RF4 reflects infrared rays that are irradiated from the carbon heater 35 and transmitted through the web paper WP. The reflected infrared rays can be re-irradiated onto the web paper WP. This allows the infrared rays irradiated from the carbon heater 35 to be used effectively.

[0074] 2, the front faces 37A of the heating units H1 to H4 are arranged to surround the paper web WPa in the first section and the paper web WPb in the second section. This arrangement makes it easier for the heating units H1 to H4 to increase the temperature of the space through which the paper web WPa and the paper web WPb are transported, which makes it easier for the ink printed on the paper web WPa and the paper web WPb to dry.

[0075] The drying mechanism 21 is equipped with an exhaust air collection unit (not shown). The exhaust air collection unit is disposed above the rollers 13A, R1 to R8, 31, and 33 and the four heating units H1 to H4. The exhaust air collection unit is connected to the exhaust units 43 of each of the four heating units H1 to H4. The exhaust air collection unit collects the gas sucked in by each of the exhaust units 43 and sends the collected gas to an exhaust duct in the building where the printing device 1 is installed.

[0076] (C) Continuous paper transport path in the second section Here, we will explain the path along which the web paper WP is transported in section 2. First, the web paper WP wound around guide roller R7 is transported in the order of path change roller 33A, path change roller 33B, path change roller 33C, path change roller 33D, and print surface contact roller 29.

[0077] The path-changing roller 33A is disposed between the guide roller R3 and the guide roller R7. The path-changing roller 33A is disposed at approximately the same height as the guide rollers R3 and R7. That is, the web paper WP wound around the guide roller R7 is transported approximately horizontally toward the front of the drying mechanism 21 and wound around the path-changing roller 33A.

[0078] Path change roller 33B is disposed in front of and at a lower position than path change roller 33A. The continuous paper WP wound around path change roller 33A is transported diagonally downward so that the printing surface FF faces upward, and is then wound around path change roller 33B.

[0079] At this time, the positional relationship between the path change rollers 33A and 33B is adjusted in advance so that the web paper WPb in the second section transported between them has its printing surface FF facing the heating unit H2. That is, the web paper WPb in the second section transported between them is positioned so that it faces the heating unit H2 with the web paper WPa in the first section sandwiched between them. In other words, the web paper WPb in the second section transported between them is transported parallel to the web paper WPa transported between the guide rollers R2 and R3.

[0080] By positioning the printing surface FF facing the heating unit H2, the web paper WPb in the second section transported between the path change rollers 33A and 33B is more likely to be indirectly heated by the heating unit H2. It is also preferable to reduce the distance between the path of the web paper WPb between the path change rollers 33A and 33B and the path of the web paper WPa between the guide rollers R2 and R3. By positioning the path of the web paper WPb closer to the path of the web paper WPa, when the heating unit H2 indirectly heats the web paper WPb in the second section, the web paper WPb can be heated more efficiently.

[0081] Path change roller 33C is positioned lower than path change roller 33B. The web paper WP wound around path change roller 33B is transported vertically downward and wound around path change roller 33C. At this time, the positional relationship between path change roller 33B and path change roller 33C is adjusted in advance so that the web paper WPb in the second section transported between path change roller 33B and path change roller 33C is oriented with its printing surface FF facing heating unit H3.

[0082] That is, the web paper WPb in the second section transported between the path change rollers 33B and 33C is positioned to face the heating unit H3 with the web paper WPa in the first section sandwiched between them. In other words, the web paper WPb in the second section transported between the path change rollers 33B and 33C is transported parallel to the web paper WPa transported between the guide rollers R3 and R4.

[0083] By positioning the printing surface FF facing the heating unit H3, the web paper WPb in the second section transported between the path change rollers 33B and 33C is more likely to be indirectly heated by the heating unit H3. It is also preferable to reduce the distance between the path of the web paper WPb between the path change rollers 33B and 33C and the path of the web paper WPa between the guide rollers R3 and R4. By positioning the path of the web paper WPb closer to the path of the web paper WPa, the web paper WPb can be heated more efficiently when the heating unit H3 indirectly heats the web paper WPb in the second section.

[0084] Path change roller 33D is positioned lower than path change roller 33C. The web paper WP wound around path change roller 33C is transported diagonally downward so that the printing surface FF faces downward, and is then wound around path change roller 33D. The positional relationship between path change roller 33D and printing surface contact roller 29 is adjusted in advance so that the web paper WP wound around path change roller 33D is transported vertically upward and wound around printing surface contact roller 29.

[0085] In this way, the web paper WPb in the second section is conveyed in a spiral shape by each of the path changing rollers 33 so as to detour around the linear path Wv, and is guided from the guide roller R7 to the printing surface contact roller 29.

[0086] (D) Ventilation duct configuration The drying mechanism 21 according to the first embodiment also includes four ventilation ducts 51. Each ventilation duct 51 is arranged along the transport path of the web paper WPb in the second section. The ventilation ducts 51 ventilate the internal space of the drying mechanism 21, thereby reducing humidity, particularly around the web paper WPb.

[0087] In the drying mechanism 21 according to the first embodiment, the path-changing rollers 33A-33D are provided, thereby significantly improving the drying efficiency of the ink on the paper web WPb in the second section. Here, efficient drying of the ink on the paper web WPa in the first section and the paper web WPb in the second section makes it easier for steam generated from the paper web WP due to drying to accumulate inside the drying mechanism 21. In particular, if the path-changing roller 33 moves the transport path of the paper web WPb in the second section closer to the transport path of the paper web WPa in the first section, the paper web WPb in the second section will be in close proximity to the paper web WPa in the first section or the paper web WPc in the third section. As a result, steam is particularly likely to accumulate around the paper web WPb in the second section. If steam accumulates, there is a concern that the drying efficiency of the ink on the paper web WP will decrease.

[0088] Therefore, in the drying mechanism 21 according to the first embodiment, a ventilation duct 51 is disposed along the transport path of the web paper WPb in the second section, thereby preventing steam from accumulating around the web paper WPb in the second section. As shown in Fig. 3, the ventilation duct 51 is preferably disposed in a position sandwiched between the web paper WPb in the second section and the web paper WPc in the third section. The space sandwiched between two adjacent transport paths is a place where steam is particularly likely to stagnate, so by disposing the ventilation duct 51 in such a location, steam can be more reliably prevented from accumulating inside the drying mechanism 21.

[0089] The configuration of the ventilation duct 51 will be explained using the drawings. FIG. 5 is a cross-sectional view taken along the line AA in FIG. 3. FIG. 5 corresponds to a cross-sectional view of the heating mechanism 21. The ventilation duct 51 is arranged in the drying mechanism 21 so as to extend in the width direction WD of the web paper WP. A plurality of air vents 53 are formed on the side of the ventilation duct 51 across the width direction WD. The air vents 53 draw in air around the web paper WP and guide it into the ventilation duct 51.

[0090] One end of each ventilation duct 51 protrudes outward from the drying mechanism 21 toward the right side (the far side in FIG. 1 ) of the drying mechanism 21. Each air vent 53 is formed to face from the other end outside the ventilation duct 51 toward the one end inside the ventilation duct 51. Therefore, the fluid (air, for example) guided into the ventilation duct 51 via the air vent 53 can easily flow from the other end to the one end of the ventilation duct 51.

[0091] One end of each ventilation duct 51 is connected to an air duct 55. The air duct 55 is connected to a connecting pipe 59 via a circulation fan 57. The connecting pipe 59 is connected to a circulation pipe 61. The circulation fan 57 is configured to send air from inside the air duct 55 to inside the connecting pipe 59. The connecting pipe 59 is connected to the inside of the drying mechanism 21 from the right side of the drying mechanism 21. The circulation pipe 61 extends, for example, in the vertical direction (z direction) and is connected to the heating units H1 to H4, etc.

[0092] 5, the flow of humid air generated around the web paper WP due to the heating and drying of the web paper WP is indicated by the symbol Vp and dotted lines. That is, air Vp is sent into the interior of ventilation duct 51 via vent hole 53, and is then sent to one end of ventilation duct 51 and guided to ventilation pipe 55. Air Vp guided into ventilation pipe 55 is circulated by circulation fan 57 into connecting pipe 59, i.e., into drying mechanism 21.

[0093] The air Vp sent to the connecting pipe 59 is sent via the circulation pipe 61 to the heating units H1 to H4, where it is heated and dried. The heated and dried air Vp is discharged to the outside of the heating units H1 to H4 via the exhaust section 43 and other devices provided in the heating units H1 to H4. An example of the path of the air Vp discharged to the outside of the heating units H1 to H4 is shown by the arrows labeled Ex in FIG. 6. In this way, the highly humid air Vp generated around the web paper WP is efficiently discharged by the ventilation duct 51. This prevents steam from accumulating around the web paper WP.

[0094] As shown in FIG. 5 , the sides of the ventilation duct 51 are positioned to face the printed surface FF of the paper web WP. That is, the ventilation duct 51 is positioned to be sandwiched between the printed surfaces FF of the paper web WP. In this embodiment, the ventilation duct 51 is positioned to be sandwiched between the printed surfaces FF of the paper web WP in the second section and the printed surfaces FF of the paper web WP in the third section. In this case, the air vents 53 formed on the sides of the ventilation duct 51 face the printed surface FF of the paper web WP. When the paper web WP dries, the moisture in the ink easily evaporates from the printed surface FF. Therefore, high-humidity air Vp is likely to be generated on the printed surface FF of the paper web WP. By positioning the sides of the ventilation duct 51 to face the printed surface FF of the paper web WP, the air Vp generated around the printed surface FF can be quickly guided into the ventilation duct 51. As a result, the discharge efficiency of the high-humidity air Vp can be improved.

[0095] <Explanation of operation> Next, the operation of the printing device 1 will be described with reference to Figures 1 and 2. The paper feed unit 3 supplies the continuous paper WP to the printing device main body 5. Ink (ink droplets) is ejected onto the continuous paper WP by the printing unit 19, and the continuous paper WP is transported to the drying mechanism 21. Here, the surface of the continuous paper WP onto which the ink is adhered is the printing surface FF. The surface opposite the printing surface FF is the back surface BF.

[0096] See Figure 2. In the first section, the web paper WP is transported in a spiral shape from transport roller 13A to guide roller R7, passing through guide rollers R1 to R6. In the section of the first section from transport roller 13A to guide roller R2, the web paper WP is transported diagonally downward with the printing surface FF facing upward (i.e., a diagonal direction that combines a forward and downward direction). In the section from guide roller R1 to guide roller R2, heating unit H1 heats the web paper WP in a non-contact manner. In other words, radiant heat from heating unit H1 directly heats the web paper WP, causing the temperature of the web paper WP to rise.

[0097] After being heated by heating unit H1, the web paper WP is further transported diagonally downward with the print surface FF facing upward from guide roller R2 to guide roller R3. In the section from guide roller R2 to guide roller R3, heating unit H2 heats the web paper WP in a non-contact manner. The temperature of the web paper WP further rises due to radiant heat from heating unit H2.

[0098] After being heated by heating units H1 and H2, the web paper WP is transported vertically downward in the section from guide roller R3 to guide roller R4. Then, in the section from guide roller R3 to guide roller R4, heating unit H3 heats the web paper WP in a non-contact manner. Heating by heating unit H3 further increases the temperature of the web paper WP.

[0099] After being heated by heating units H1 to H3, the web paper WP is transported with its printed surface FF facing downward in the section from guide roller R4 to guide roller R6. In this section, the web paper WP is transported without being directly heated by heating units H1 to H4.

[0100] After being transported to guide roller R6, the web paper WP is transported vertically upward in the section from guide roller R6 to guide roller R7. In this section, heating unit H4 heats the web paper WP in a non-contact manner. The temperature of the web paper WP is further increased by the heating of heating unit H4. In other words, the temperature of the web paper WP is highest when it is transported to guide roller R7, which corresponds to the stage in the first section immediately after being heated by heating unit H4.

[0101] As the temperature of the web paper WP rises, the ink on the printing surface FF of the web paper WP dries more efficiently. That is, of the web paper WPa in the first section, the ink dries most efficiently on the web paper WPa guided by guide roller R7.

[0102] The transport of the web paper WP in the first section is completed by being transported to guide roller R7. After being transported to guide roller R7, the web paper WP is transported to printing surface contact roller 29 via path changing rollers 33A to 33D.

[0103] The transport path of the paper web WP in the second section from the guide roller R7 to the printing surface contact roller 29 is a detour from the straight path Wv from the guide roller R7 to the printing surface contact roller 29. That is, by transporting the paper web WP via the path change rollers 33A to 33D in the second section, the transport path of the paper web WP in the second section is longer than the straight path Wv. In other words, by transporting the paper web WP via the path change rollers 33A to 33D, the paper web WP, which is at its hottest, can be transported for a longer period of time. As a result, the paper web WP can be maintained at a higher temperature for a longer period of time, and the ink on the printing surface FF dries more efficiently by the time the paper web WP reaches the printing surface contact roller 29.

[0104] Additionally, in the section of the second section from path change roller 33A to path change roller 33B, the print surface FF of the web paper WP faces the heating unit H2. Specifically, the web paper WPb in the second section faces the heating unit H2 across the web paper WPa in the first section. This allows the hot air and radiant heat from the heating unit H2 to be more efficiently transmitted to the web paper WPb in that section. In other words, in the section from path change roller 33A to path change roller 33B, the web paper WPb is more efficiently indirectly heated by the heating unit H2, further improving the ink drying efficiency.

[0105] In the second section, from path change roller 33B to path change roller 33C, the print surface FF of the web paper WP faces the heating unit H3. This allows the warm air and radiant heat from the heating unit H3 to be more efficiently transmitted to the web paper WPb in this section. In other words, in the section from path change roller 33B to path change roller 33C, the web paper WPb is more efficiently indirectly heated by the heating unit H3, further improving the drying efficiency of the ink.

[0106] After the web paper WP is transported via path-changing rollers 33A-33D, the printing surface contact roller 29 first comes into contact with the printing surface FF of the web paper WP after ink has been applied by the printing unit 19. Due to direct and indirect heating by heating units H1-H4, the ink on the printing surface FF is dried to the extent that it does not transfer. Therefore, even when the printing surface contact roller 29 comes into contact with the printing surface FF of the web paper WP, ink transfer is prevented. Transport of the web paper WP in the second section is completed by being transported by the printing surface contact roller 29.

[0107] The printing surface contact roller 29 turns back the web paper WP while contacting the printing surface FF. The nine transport rollers 31 guide the web paper WP turned back by the printing surface contact roller 29 (the web paper WPc of the third section) through the gap CL1 between the web paper WPa of the first section transported from transport roller 13A to guide roller R3 and the web paper WPb of the second section transported from guide roller R7 to path change roller 33B, to the outlet of the drying mechanism 21 and the cooling section 23. In other words, the nine transport rollers 31 guide the web paper WP guided inside the spiral to the outside of the spiral, while guiding the web paper WP to the outlet of the drying mechanism 21.

[0108] The cooling unit 23 cools the web paper WP that has been heated by the drying mechanism 21. The web paper WP that has been cooled by the cooling unit 23 is then transported to the inspection unit 25. The inspection unit 25 inspects the printed portion (characters and graphics). The web paper WP that has been inspected by the inspection unit 25 is taken up by the paper discharge unit 7.

[0109] Furthermore, as the paper web WP is dried efficiently, air Vp containing a large amount of water vapor is generated around the paper web WP. In the drying mechanism 21, the path of the paper web WPb in the second section is changed from the straight path Wv to a detour, and the path of the paper web WPb is close to the path of the paper web WP in the other sections. Therefore, the highly humid air Vp is likely to stagnate around the paper web WPb, particularly in the second section.

[0110] The air Vp stagnating around the web paper WPb is sent into the ventilation duct 51 via the ventilation hole 53. The air Vp is then sent from the ventilation duct 51 through the ventilation pipe 55 to the circulation fan 57, and is then sent by the circulation fan 57 into the connecting pipe 59 and the circulation pipe 61. In other words, the air Vp discharged to the outside of the drying mechanism 21 by the ventilation duct 51 is circulated back into the drying mechanism 21 by the circulation fan 57. The air Vp, which contains a large amount of water vapor, travels through the circulation pipe 61 to the heating units H1 to H4, where it is heated and dried. The heated and dried air Vp is diffused into or outside the printing device 1 along paths such as the path Ex shown in FIG. 6.

[0111] <Effects of the configuration of Example 1> In the printing device 1 according to the first embodiment, after printing ink is applied to the printing surface FF of the long web paper WP in the printing unit 19, the web paper WP is transported into the drying mechanism 21 via an entrance (not shown). After being transported into the drying mechanism 21, the web paper WP is transported in a spiral shape to the printing surface contact roller 29 by the guide roller R and the path changing roller 33. The printing surface contact roller 29 then comes into contact with the printing surface FF of the web paper WP, thereby changing the transport direction of the web paper WP so that it folds back, and guides the web paper WP to the exit of the drying mechanism 21.

[0112] The path along which the web paper WP is transported spirally to the printing surface contact roller 29 includes a first section on the upstream side and a second section on the downstream side. The first section is a transport section in which heating units H1 to H4 are arranged. In the first section, the web paper WP is transported spirally while being changed in direction by multiple guide rollers R contacting the back surface BF. Also in the first section, multiple drying units H1 to H4 are arranged so as to face the printing surface FF of the web paper WP.

[0113] The heat generated by the drying units H1 to H4 is transferred directly to the web paper WP transported through the first section, heating the web paper WP and evaporating the water content of the ink. As the drying units H1, H2, H3, and H4 heat the web paper WP in order, the temperature of the web paper WP rises. In other words, the temperature of the web paper WP is highest at the downstream end of the first section.

[0114] The second section is a section in which the web WP is transported from the guide roller R7 to the printing surface contact roller 29. Of the guide rollers R, the guide roller R7 is the guide roller R that is located downstream of and closest to the first section. In the second section, the web WP is transported to the printing surface contact roller 29 by the path changing roller 33 contacting the back side of the web WP. At this time, the path of the web WP is curved and changed from the straight path Wv by the path changing roller 33. In other words, by providing the path changing roller 33, the path of the web WP in the second section can be made longer.

[0115] The temperature of the web paper WP is at its highest when it is transported into the second section. The higher the temperature of the web paper WP, the higher the drying efficiency of the web paper WP. Therefore, by transporting the web paper WP through the longer second section while the temperature is at its highest, the moisture content of the web paper WP can be further reduced by the time the printing surface contact roller 29 contacts the printing surface FF. This allows the drying efficiency of the web paper WP in the drying mechanism 21 to be improved without requiring design changes such as adding a new heating unit to the second section or increasing the heating temperature of heating units H1 to H4. In other words, the drying efficiency of the web paper WP can be improved without requiring design changes that increase the energy required for drying.

[0116] The path change roller 33 changes the transport path of the web paper WP in the second section so that the web paper WP in the second section faces one of the heating units H1 to H4. In the first embodiment, the path change roller 33A changes the transport path of the web paper WPb so that the print surface FF of the web paper WPb in the section from the path change roller 33A to the path change roller 33B faces the heating unit H2. By changing the path in this way, as shown in FIG. 7, the heat KA generated from the heating unit H2 passes through the web paper WPa in the first section and indirectly heats the web paper WPb in the section from the path change roller 33A to the path change roller 33B. Furthermore, because the web paper WPb from the path change roller 33A to the path change roller 33B is parallel to the front surface 37A of the heating unit H2, the heat KA generated by the heating unit H2 is transmitted perpendicular to the web paper WPb. This improves the efficiency of indirect heating by the heating unit H2.

[0117] Furthermore, the path change roller 33B changes the transport path of the web paper WPb so that the print surface FF of the web paper WPb in the section from the path change roller 33B to the path change roller 33C faces the heating unit H3. By changing the path in this way, as shown in FIG. 7, heat KB generated by the heating unit H3 passes through the web paper WPa in the first section and indirectly heats the web paper WPb in the section from the path change roller 33B to the path change roller 33C. Furthermore, because the web paper WPb from the path change roller 33B to the path change roller 33C is parallel to the front surface 37A of the heating unit H3, the heat KB generated by the heating unit H3 is transmitted perpendicular to the web paper WPb. This improves the efficiency of this indirect heating by the heating unit H3.

[0118] The transport path for the paper web WPb in the second section is arranged so as to be surrounded by the transport path for the paper web WPa in the first section. The transport path for the paper web WPa in the first section is located in a position surrounded by heating units H1 to H4. Therefore, the heat from heating units H1 to H4 used to heat the paper web WPa in the first section is concentrated on the transport path for the paper web WPb in the second section. Therefore, the radiant heat and convective heat generated from heating units H1 to H4 are efficiently transferred to the paper web WPb in the second section. As a result, the paper web WPb in the second section can be maintained at a higher temperature, further improving the drying efficiency of the paper web WPb in the second section.

[0119] By improving the drying efficiency of the paper web WPb in the second section, highly humid air Vp is generated around the paper web WPb in the second section. This air Vp is efficiently removed from around the paper web WPb by the ventilation duct 51 arranged along the transport path of the paper web WPb in the second section. This prevents a decrease in the drying efficiency of the paper web WPb due to the highly humid air Vp continuing to remain around the paper web WPb.

[0120] The drying mechanism 21 also includes a circulation fan 57. The circulation fan 57 circulates the air Vp discharged through the ventilation duct 51 into the interior of the drying mechanism 21. By configuring the air Vp to circulate into the interior of the drying mechanism 21, the amount of air exhausted from the drying mechanism 21 can be reduced. As a result, it is possible to avoid increasing the size of the air conditioning equipment for the printing device 1 and to effectively utilize the thermal energy in the drying mechanism 21. [Example]

[0121] Next, a second embodiment of the present invention will be described with reference to the drawings. Note that the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. Fig. 8 is a diagram showing a drying mechanism 21A according to the second embodiment.

[0122] The drying mechanism 21A according to the second embodiment differs from the drying mechanism 21 according to the first embodiment in the number of path-changing rollers 33 and the position of the printing surface contact roller 29. As shown in FIG. 8 , the path-changing roller 33D is omitted from the drying mechanism 21A according to the second embodiment. In the drying mechanism 21A, the printing surface contact roller 29 is disposed at substantially the same height as the path-changing roller 33C. That is, the paper web WP guided by the path-changing roller 33C is transported horizontally to the rear of the drying mechanism 21 with the printing surface FF facing downward. The paper web WP transported horizontally is guided by the printing surface contact roller 29. The printing surface FF of the paper web WP then contacts the printing surface contact roller 29, causing the paper web WP to be folded back. The folded back paper web WP is transported by the transport roller 31 toward the exit of the drying mechanism 21.

[0123] This embodiment has the same effects as the first embodiment. Specifically, the three path-changing rollers 33A-33C change the transport path of the web paper WPb in the second section to a path that bypasses the linear path Wv from the guide roller R7 to the print surface contact roller 29. This lengthens the transport path of the web paper WPb in the second section, improving the drying efficiency of the web paper WPb in the second section. Furthermore, the web paper WPb, whose path has been changed by the path-changing rollers 33A-33C, faces the heating units H2 and H3, as in the first embodiment. Therefore, the heat indirectly transferred from the heating units H2 and H3 heats the web paper WPb more efficiently. This further improves the drying efficiency of the web paper WPb in the second section.

[0124] In the drying mechanism 21A according to the second embodiment, the length of the second section can be shortened while maintaining the path of the web paper WPb facing the heating units H2 and H3 by changing the position of the printing surface contact roller 29. In this case, the transport distance of the web paper WP in the drying mechanism 21 is shortened overall, so the amount of web paper WP that becomes waste in the printing device 1 can be reduced. In other words, the amount of web paper WP that is wasted in the printing device 1 can be reduced. [Example]

[0125] Next, a third embodiment of the present invention will be described with reference to the drawings. Fig. 9 is a diagram showing a drying mechanism 21B according to the third embodiment.

[0126] In the drying mechanism 21B according to Example 3, the position of the print surface contact roller 29 and the number of path-changing rollers 33 are the same as those in the drying mechanism 21 according to Example 1. However, in Example 1, the ventilation duct 51 is configured to remove the humid air Vp from around the web paper WP by drawing in air from around the web paper WP and sending it to the heating units H1 to H4, etc. On the other hand, the ventilation duct 51B according to Example 3 is configured to remove the humid air Vp from around the web paper WP by heating and drying the air Dr drawn in by the heating units H1 to H4, etc., and sending the air Dr around the web paper WP.

[0127] Here, the configuration of ventilation duct 51B will be described with reference to Figure 10 and other figures. Figure 10 is a cross-sectional view taken along the line BB in Figure 9, and corresponds to a horizontal cross-sectional view of heating mechanism 21B. In Example 3, air Dr sent into heating units H1 to H4 is heated and dried inside housing 37, and the heated and dried air Dr is guided to circulation pipe 61. The heated and dried air Dr is sent from circulation pipe 61 to circulation fan 57 via connecting pipe 59.

[0128] The circulation fan 57 circulates the air Dr through the ventilation pipe 55 and the ventilation duct 51B. The air Dr circulated to the ventilation duct 51B is discharged to the outside through the ventilation holes 53. The air Dr discharged to the outside of the ventilation duct 51B is blown onto the printing surface FF of the web paper WP arranged around the ventilation duct 51B. The flow of the air Dr in the drying mechanism 21B is indicated by the dotted line labeled Dr in FIG. 10. The flow of the air Dr sent into the heating units H1 to H4 is indicated by the arrow Gt in FIG. 9.

[0129] As the air Dr is blown onto the printed surface FF of the web paper WP through the ventilation holes 53, the humid air Vp that has been generated around the printed surface FF of the web paper WP is expelled from the periphery of the printed surface FF and diffused inside or outside the drying mechanism 21B. The flow of the diffused air Vp is indicated by the solid arrows in Figure 10.

[0130] In this way, the drying mechanism 21B according to Example 3 is configured to supply heated and dried air Dr from the drying duct 51B to the printing surface FF of the paper web WP. By supplying heated and dried air Dr from the drying duct 51B to the printing surface FF of the paper web WP, the highly humid air Vp generated around the paper web WP, particularly in the second section, is discharged from the space around the paper web WP and diffused inside or outside the drying mechanism 21B. As a result, similar to the drying mechanism 21 according to Example 1, the drying mechanism 21B according to Example 3 can avoid a decrease in the drying efficiency of the paper web WP due to the highly humid air Vp remaining around the paper web WP.

[0131] (1) In each of the above-described embodiments, the web paper WP in the second section, whose path has been changed by the path changing roller 33, is positioned so that the printed side FF faces the heating unit H2 or H3. However, the positioning of the web paper WP in the second section is not limited to this, and the path of the web paper WP in the second section may be set so that the back side BF faces the heating unit H2 or H3.

[0132] (2) In each of the above-described embodiments, the web paper WP in the second section, whose path has been changed by the path changing roller 33, is not limited to a configuration in which any portion thereof faces the heating unit H2 or H3. The path of the web paper WP in the second section may be set so that any portion thereof faces the heating unit H1 or H4.

[0133] (3) In the above-described embodiments, the printing device 1 is not limited to a configuration including four heating units H1 to H4. The number of heating units included in the printing device 1 may be changed as appropriate, as long as the effects of the present invention can be obtained. As an example, as shown in FIG. 11, the printing device 1 may include a drying mechanism 21C that does not include the heating unit H1. In this case, the drying mechanism 21C according to the modified example heats and dries the web paper WP using three heating units H2 to H4.

[0134] (4) In the first embodiment described above, the ventilation duct 51 is not limited to a configuration in which air is circulated to the drying mechanism 21 using the circulation fan 57 or the like. Fig. 12 shows the configuration of a drying mechanism 21D according to a modified example. Unlike the first embodiment, the drying mechanism 21D according to the modified example does not include the ventilation pipe 55, the circulation fan 57, the connecting pipe 59, and the circulation pipe 61.

[0135] In the drying mechanism 21D according to the modified example, one end of the ventilation duct 51 that protrudes outside the drying mechanism 21D is open. That is, the air Vp guided into the ventilation duct 51 via the air vents 53 flows from the other end to one end of the ventilation duct 51 and is discharged from the one end of the ventilation duct 51 to the outside of the drying mechanism 21D. In this way, by discharging the highly humid air Vp generated around the web paper WP directly from the ventilation duct 51 to the outside of the drying mechanism 21D, the air Vp can be efficiently discharged from around the web paper WP in the second section and other areas. This prevents steam from accumulating around the web paper WP.

[0136] (5) In the above-described embodiment, the printing medium is not limited to the web paper WP. Other examples of printing media include thin, long-length materials such as films.

[0137] (6) In the first embodiment described above, the ventilation duct 51 supplied humid air to the heating units H1 to H4 via the circulation pipe 61. However, instead of connecting the ventilation pipe 55 to the circulation pipe 61, the ventilation pipe 55 may be connected to an opening 71 formed in a side panel of the drying mechanism 21, and the humid air collected by the ventilation duct 51 may be returned to the interior space of the drying mechanism 21 via the opening 71. FIG. 13 shows a preferred position for the opening 71. As shown in FIG. 13, the opening 71 is positioned so that air can be sent toward an interior space 72 surrounded by the printing surface contact roller 29 and the path changing rollers 33A, 33B, and 33C. Because the interior space 72 has a larger capacity than the space in which the ventilation duct 51 is installed, returning humid air to this space 72 does not adversely affect the drying of the web paper WP.

[0138] (7) In the above-described embodiment, an inkjet printing system is exemplified as a printing device according to the present invention, but the configuration according to the present invention can also be applied to printing devices other than inkjet type, such as offset printing machines.

[0139] (8) In each of the above-described embodiments, the shape, number, and arrangement of the conveying roller 13A, guide roller R, conveying roller 31, and path changing roller 33 may be changed as appropriate as long as the effects of the present invention can be obtained. [Explanation of symbols]

[0140] 1...Printing device 3...Paper feed section 5...Printing device body 7...Paper ejection section 9...Drive roller 11...Drive roller 13...Transport roller 19...Printing Department 21...Drying mechanism 23...Cooling section 25...Inspection Department 27...Control unit 29...Printing surface contact roller 31...Transport roller 33...Route change roller 35...Carbon heater 39...Ventilation fan 43...Exhaust section 51...Ventilation duct 53...Ventilation hole 57...Circulation fan R...Guide roller Wv...straight line path WP...Continuous paper H1~H4 ... Heating units RF1~RF4…Reflector

Claims

1. a printing unit that deposits ink onto a printing surface of the conveyed long print medium; a drying mechanism that heats the print medium discharged from the printing unit to dry the ink; Equipped with The drying mechanism includes: a plurality of direction-changing rollers that come into contact with the back surface of the print medium, on which no ink is attached, of the print medium conveyed from the printing unit, thereby changing the conveying direction of the print medium a plurality of times and conveying the print medium in a spiral shape; a plurality of drying units arranged to face the printing surface of the print medium transported in a spiral shape, and heating the print medium to dry the ink; a print surface contact roller that is disposed downstream of a first section, which is a spiral transport section for the print medium and is a transport section in which the plurality of drying units are disposed, and that first comes into contact with a print surface of the print medium and folds the print medium; a path changing roller that is disposed in a second section, which is a section in which the print medium is transported from the direction changing roller that is disposed downstream of the first section and closest to the first section to the print surface contact roller, and that contacts the back side of the print medium in the second section to bend and change the transport path of the print medium; A printing device comprising:

2. 2. The printing device according to claim 1, The path changing roller is The transport path of the print medium in the second section is changed so that the print medium faces one of the drying units. A printing device characterized by:

3. 2. The printing device according to claim 1, The path changing roller is The transport path of the print medium in the second section is changed so that the printed surface of the print medium faces one of the drying units. A printing device characterized by:

4. 2. The printing device according to claim 1, The transport path of the print medium in the second section is arranged to be surrounded by the transport path of the print medium in the first section. A printing device characterized by:

5. 5. The printing device according to claim 1, a ventilation section that is disposed along the width direction of the print medium transported through the second section and that ventilates the gas; A printing device characterized by:

6. 6. The printing device according to claim 5, The ventilation section is configured to supply gas heated by the drying unit to the second section. A printing device characterized by:

7. 6. The printing device according to claim 5, The ventilation section is configured to exhaust gas from the second section. A printing device characterized by:

8. 8. The printing device according to claim 7, a gas circulation unit that circulates the gas discharged by the ventilation unit inside the drying mechanism; A printing device characterized by:

9. 6. The printing device according to claim 5, The ventilation section is disposed at a position sandwiched between the printing surface of the print medium in the second section and the printing surface of the print medium downstream of the second section. A printing device characterized by:

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