Image forming device

Abstract

This image forming device comprises: a conveyance mechanism that has a conveyance path along which a recording medium is conveyed; an image forming unit that forms an image on the recording medium; a drying unit that can perform pre-drying for drying the recording medium before image formation; and a processor that controls the conveyance mechanism, the image forming unit, and the drying unit, wherein the processor can switch between a first mode in which pre-drying is performed and a second mode in which pre-drying is not performed.

Description

Image forming device

[0001] The present disclosure relates to an image forming apparatus.

[0002] Some image forming apparatuses, such as electrophotographic printers using toner and inkjet printers using ink, are equipped with a drying unit for drying an image formed on the recording surface of a recording medium (see, for example, Japanese Patent No. 3597487). If an image formed on the recording surface comes into contact with a conveyance mechanism or the like while it is not yet sufficiently dried, fine white spots may appear in the image due to bleeding of the ink in an insufficiently dried state. The drying unit is used to prevent quality defects such as fine white spots by post-drying the formed image after the image is formed and before the recording surface comes into contact with the conveyance mechanism or the like.

[0003] In addition to post-drying, one measure to further reduce the occurrence of such quality defects is to perform pre-drying, which involves drying the recording medium before image recording. Pre-drying reduces the moisture content of the recording medium, preventing insufficient drying during post-drying due to the energy lost from the drying unit to the evaporation of moisture in the recording medium. This can further enhance the effectiveness of post-drying and may further reduce the occurrence of quality defects such as fine white spots.

[0004] The image forming apparatus described in Japanese Patent No. 3597487 uses both an electrophotographic image forming unit and an inkjet image forming unit, and has a fixing unit as a drying unit that fixes an image formed by the electrophotographic method onto a recording medium by heat. Furthermore, Japanese Patent No. 3597487 discloses that the radiant heat of the fixing unit may be used for post-drying of an image formed by the inkjet method and pre-drying before image formation.

[0005] As mentioned above, pre-drying is a known method for preventing quality defects, but the inventors' extensive research has revealed that, depending on the type of recording medium, it may be better not to perform pre-drying. For example, depending on the recording medium, pre-drying may cause excessive drying, resulting in deformation of the recording medium and resulting in quality defects.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to provide an image forming apparatus that can suppress poor quality of image formation.

[0007] The image forming apparatus of the present disclosure comprises a transport mechanism having a transport path for transporting a recording medium, an image forming unit for forming an image on the recording medium, a drying unit capable of performing pre-drying to dry the recording medium before image formation, and a processor for controlling the transport mechanism, the image forming unit, and the drying unit, and the processor is capable of switching between a first mode in which pre-drying is performed and a second mode in which pre-drying is not performed.

[0008] In addition to pre-drying, the drying unit may be capable of performing post-drying, which dries an image formed on the recording medium after the image is formed in the image forming unit.

[0009] The processor may be configured to be able to switch the path along which the recording medium is transported by controlling the transport mechanism, and to switch between the first mode and the second mode by switching the path.

[0010] It is preferable that the image forming device is configured to sequentially form images on the multiple recording media by continuously supplying the multiple recording media to a conveying path, and that the drying unit is configured to perform both pre-drying and post-drying on each of the multiple recording media.

[0011] The image forming device may be configured such that, among a plurality of recording media that continuously pass through a section of the conveying path in which the drying unit is located, the drying unit performs pre-drying on the Nth recording medium and performs post-drying on the N+1th recording medium.

[0012] The image forming apparatus may have two printing modes: a single-sided printing mode in which an image is formed on only one side of the recording medium, and a double-sided printing mode in which images are formed on both the first and second sides of the recording medium. In this case, it is preferable that the image forming apparatus uses at least a part of the transport path in both the single-sided printing mode and the double-sided printing mode.

[0013] When the image forming device is in double-sided printing mode and sequentially forms images on multiple recording media by continuously supplying the multiple recording media to a conveying path, and the drying unit performs both pre-drying and post-drying on each of the multiple recording media, the drying unit may be configured to perform pre-drying on the Nth recording medium among the multiple recording media that continuously pass through the section of the conveying path in which the drying unit is located, perform post-drying on the image formed on the first side of the N+1th recording medium after image formation on the first side, and perform post-drying on the image formed on the second side of the N+2th recording medium after image formation on the second side.

[0014] In the image forming device, the transport mechanism has a transport path in which an image forming unit and a drying unit are arranged, a circular path along which the recording medium circulates, a supply path that supplies the recording medium to the circular path, a discharge path that discharges the recording medium from the circular path, and a switchback section that temporarily pulls the recording medium out of the circular path to reverse the direction of travel of the recording medium, and the transport mechanism further has a first path switching mechanism that switches the path of the recording medium at the connection between the circular path and the discharge path between a path toward the discharge path and a path along the circular path, and a second path switching mechanism that switches the path of the recording medium at the connection between the circular path and the switchback section between a path toward the switchback section and a path along the circular path, and the processor may be configured to switch the path of the recording medium by controlling the first path switching mechanism and the second path switching mechanism.

[0015] In the image forming apparatus, the processor may be configured to receive information about the recording medium and switch between the first mode and the second mode based on the information.

[0016] In the image forming apparatus, the information about the recording medium may include the moisture content of the recording medium, and the processor may be configured to select the first mode if the recording medium has a moisture content exceeding a predetermined specified moisture content, and to select the second mode if the recording medium has a moisture content equal to or less than the specified moisture content. In this case, the specified moisture content is preferably 4.8%.

[0017] In the image forming device, the information regarding the recording medium may include the thickness of the recording medium, and the processor may be configured to select the first mode if the recording medium is a recording medium with a thickness exceeding a predetermined specified thickness, and to select the second mode if the recording medium is a recording medium with a thickness less than the specified thickness.

[0018] In the image forming apparatus, the drying unit may perform pre-drying as well as post-drying, which dries an image formed on the recording medium after the image has been formed in the image forming unit, and the processor may be configured to control the drying unit based on information about the recording medium to control the drying output when post-drying is performed.

[0019] In the image forming apparatus, the processor determines whether the amount of organic solvent on the recording medium is 160 μg / cm ２ The drying output may be controlled under the following conditions:

[0020] In an image forming apparatus, pre-drying may be a drying step that is carried out before processing of a recording medium, including application of a pretreatment liquid.

[0021] The image forming apparatus may further include a treatment liquid application unit that applies a pretreatment liquid to the image forming surface of the recording medium before the image is formed on the recording medium, and a pretreatment liquid drying unit that dries the image forming surface on which the pretreatment liquid has been applied, before the image is formed by the image forming unit.

[0022] In the image forming apparatus, the image forming unit is preferably a unit that forms images by an inkjet method.

[0023] In the image forming apparatus, the recording medium is preferably paper.

[0024] According to the image forming apparatus of the present disclosure, it is possible to suppress poor quality of image formation.

[0025] 1 is a diagram illustrating an overall configuration of an inkjet printing apparatus according to an embodiment; FIG. 2 is an explanatory diagram of a first path switching mechanism; FIG. 3 is an explanatory diagram of a second path switching mechanism; FIG. 4 is an explanatory diagram of a switchback unit; FIG. 5 is a functional block diagram illustrating a schematic configuration of a control system of the inkjet printing apparatus; FIG. 6 is a schematic diagram of a transport path; FIG. 7 is a diagram illustrating a first transport path; FIG. 8 is a diagram illustrating a second transport path; FIG. 9 is a diagram illustrating a third transport path; FIG. 10 is a diagram illustrating a fourth transport path; FIG. 11 is an explanatory diagram of a table associating paper types with modes; FIG. 12 is a flowchart of printing processing; FIG. 13 is an explanatory diagram of an example of a case where a plurality of papers are continuously supplied; FIG. 14 is an explanatory diagram of an example of a case where a plurality of papers are continuously supplied; FIG. 15 is a diagram illustrating a modified example of a drying unit; FIG. 16 is a diagram illustrating a modified example of a drying unit; FIG. 17 is a diagram illustrating a modified example of a drying unit; FIG. 18 is a diagram illustrating a modified example of a drying unit; FIG. 19 is a diagram illustrating a modified example of a drying unit; FIG. 19 is a diagram illustrating a modified example of a drying unit; FIG. 19 is a diagram illustrating a modified example of a drying unit; FIG. 19 is a diagram illustrating a modified example of a drying unit; FIG. 20 is a diagram illustrating a modified example of a drying unit; FIG. 21 is a diagram illustrating a modified example of a drying unit; FIG. 22 is a diagram illustrating a modified example of a drying unit; FIG. 23 is a diagram illustrating a modified example of a drying unit; FIG. 24 is a diagram illustrating a modified example of a drying unit; FIG. 25 is a diagram illustrating a modified example of a drying unit; FIG. 26 is a diagram illustrating a modified example of a drying unit; FIG. 27 is a diagram illustrating a modified example of a drying unit; FIG. 10A and 10B are diagrams illustrating a modified example of a pretreatment liquid drying unit, a modified example of a pretreatment liquid drying unit, and a diagram illustrating an overall configuration of a modified inkjet printing apparatus.

[0026] Hereinafter, an embodiment of an image forming apparatus according to the present disclosure will be described with reference to the drawings. In each drawing, the same elements are denoted by the same reference numerals.

[0027] "Configuration of Inkjet Printing Apparatus 1" Figure 1 is a diagram showing the overall configuration of an inkjet printing apparatus 1 according to an embodiment of the image forming apparatus of the present disclosure. The inkjet printing apparatus 1 is an inkjet color digital printing apparatus that forms a desired image on a sheet of paper P. The inkjet printing apparatus 1 has two printing modes: a single-sided printing mode in which an image is formed on only one side of the paper P, and a double-sided printing mode in which an image is formed on both the front and back sides of the paper P, that is, a first side and a second side.

[0028] 1, the inkjet printing apparatus 1 includes a transport mechanism 10, a paper feeding device 20, a pretreatment liquid application unit 30, a pretreatment liquid drying unit 35, an image forming unit 40, a drying unit 50, and a stacking device 60. Although not shown in FIG. 1, the inkjet printing apparatus 1 also includes a processor 100 (see FIG. 5) as a control device.

[0029] The transport mechanism 10 has a transport path 12 along which the paper P is transported. In FIG. 1 , the transport path 12 along which the paper P is transported is indicated by a two-dot chain line. The transport path 12 includes a circular path 13 along which the paper P travels, a supply path 14 that supplies the paper P to the circular path 13, and a discharge path 15 that discharges the paper P from the circular path 13. The transport path 12 is equipped with a switchback unit 16 that reverses the traveling direction of the paper P, and a first path switching mechanism 17 and a second path switching mechanism 18 that switch the path of the paper P. The supply path 14 is connected to the circular path 13 at a first connection unit 21. The discharge path 15 is connected to the circular path 13 at a second connection unit 22. The switchback unit 16 is connected to the circular path 13 at a third connection unit 23 (see FIG. 6 ).

[0030] In the transport path 12, the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, and the drying unit 50 are arranged between a first connection portion 21 and a second connection portion 22 on the circular path 13. The paper P is supplied from the supply path 14 to the circular path 13 at the first connection portion 21, and passes through the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, and the drying unit 50 in this order while being transported along the circular path 13 to the second connection portion 22.

[0031] The transport mechanism 10 includes a plurality of transport guides 70 to 78 along the transport path 12, as well as a chain gripper and transport rollers (not shown). The transport mechanism 10 also includes a paper feed drum 24, a pretreatment liquid application drum 32, a pretreatment liquid drying drum 36, an imaging drum 42, a rotating drum 26, and a belt conveyor 54 equipped with a heating belt 51 (described later). The transport mechanism 10 also includes a motor (not shown) as a power source and a drive unit such as a motor drive circuit (not shown). The paper P is transported along the transport path 12 by these elements that make up the transport mechanism 10.

[0032] One end of the supply path 14 is disposed on the paper feed device 20 side, and the other end is connected to the circular path 13 at a first connection portion 21. The paper P is supplied from the paper feed device 20 to one end of the supply path 14, transported along the supply path 14, and supplied from the other end of the supply path 14 to the circular path 13.

[0033] One end of the discharge path 15 is connected to the circular path 13 at the second connection portion 22, and the other end is connected to the stacking device 60. The paper P is discharged from the circular path 13 to one end of the discharge path 15, transported along the discharge path 15, and discharged from the other end of the discharge path 15 to the stacking device 60.

[0034] The first path switching mechanism 17 is provided at a second connection portion 22 that connects the discharge path 15 to the circular path 13. The first path switching mechanism 17 switches the path of the paper P at the second connection portion 22 between a path toward the discharge path 15 and a path along the circular path 13.

[0035] The first path switching mechanism 17 will be described with reference to FIG. 2, which shows an enlarged view of a portion II enclosed by a dashed line and including the first path switching mechanism 17. The first path switching mechanism 17 includes, for example, a first branch guide 17a and a guide switching unit (not shown). The first branch guide 17a is rotatably fixed to a fulcrum 17b provided at one end of a conveying guide 74 (described later). The guide switching unit rotates the first branch guide 17a to switch between a discharge state shown in II-1 in FIG. 2 and a rotation state shown in II-2 in FIG. 2. The guide switching unit may be, for example, an actuator such as a solenoid.

[0036] The discharge state II-1 in Figure 2 is a state in which the first branch guide 17a is rotated in a direction that contacts the conveyance guide 75 on the circular path 13 side, closing the circular path 13 and opening the discharge path 15. When the paper P is conveyed to the second connection section 22 in this state, the paper P proceeds toward the discharge path 15. The circulating state shown in II-2 in Figure 2 is a state in which the first branch guide 17a is positioned to connect the conveyance guide 73 and the conveyance guide 74, closing the discharge path 15 and opening the circular path 13. In this state, the paper P conveyed to the second connection section 22 is conveyed directly along the circular path 13.

[0037] The second path switching mechanism 18 is provided at a third connection section that connects the switchback section 16 to the circular path 13. The second path switching mechanism 18 switches the path of the paper P between a path toward the switchback section 16 and a path along the circular path 13.

[0038] The second path switching mechanism 18 will be described with reference to FIG. 3 , which shows an enlarged view of a portion III of the second path switching mechanism 18 surrounded by a dashed line. The second path switching mechanism 18 includes, for example, a second branch guide 18a and a guide switching unit (not shown). The second branch guide 18a is rotatably fixed to a fulcrum 18b provided at one end of a switchback guide 16c in the switchback unit 16 (described later). The guide switching unit rotates the second branch guide 18a to switch between an orbiting state shown in III-1 in FIG. 3 and a retracted state shown in III-2 in FIG. 3. The guide switching unit may include, for example, an actuator such as a solenoid.

[0039] The circulating state shown in III-1 in Figure 3 is a state in which the second branch guide 18a is rotated to a position that blocks the path to the inlet of the switchback section 16, thereby closing the switchback section 16 and opening the circulating path 13. In this state, paper P transported to the third connection section 23 is transported directly along the circulating path 13. The switchback retracting state shown in III-2 in Figure 3 is a state in which the second branch guide 18a is rotated to a position that blocks the circulating path 13, thereby opening the path to the switchback inlet and closing the circulating path 13. When paper P is transported to the third connection section 23 in this state, the paper P is transported into the switchback section 16.

[0040] The switchback section 16 temporarily pulls out the paper P from the circular path 13 and reverses the traveling direction of the paper P. That is, the leading edge of the paper P in the traveling direction when it was being transported on the circular path 13 before being drawn into the switchback section 16 becomes the trailing edge of the paper P in the traveling direction after it is returned from the switchback section 16 to the circular path 13. Furthermore, the front and back of the surface that contacts the transport surface are reversed between when the paper P is transported on the circular path 13 as is without being drawn into the switchback section 16 at the third connection section 23 and when it is returned to the circular path 13 after being drawn into the switchback section 16.

[0041] The following description will be given with reference to FIG. 4, which shows an enlarged view of a portion IV enclosed by a dashed line and including the switchback unit 16. The switchback unit 16 includes switchback guides 16a to 16c that guide the paper P, and transport rollers 16d and 16e that can reverse their rotation direction. The transport rollers 16d and 16e can switch between rotating in a direction that draws the paper P into the switchback guides 16a and 16b and rotating in a direction that ejects the paper P toward the circular path 13. The reversal of the rotation direction of the transport rollers 16d and 16e can be achieved by reversing the rotation direction of the drive motor. To draw the paper P into the switchback unit 16, as shown in FIG. 4, the upper transport roller 16d of the transport rollers 16d and 16e is rotated counterclockwise, and the lower transport roller 16e is rotated clockwise. On the other hand, when the paper P that has been drawn into the switchback section 16 is returned to the circular path 13, the conveying rollers 16d and 16e are rotated in the opposite direction to the rotation when the paper P is drawn in, as shown by IV-2 in Fig. 4. That is, the upper conveying roller 16d is rotated clockwise, and the lower conveying roller 16e is rotated counterclockwise.

[0042] The paper feeder 20 includes a paper feed tray on which a stack of multiple sheets of paper can be placed. The type of paper P is not particularly limited, but printing paper primarily made of cellulose, such as high-quality paper, coated paper, and art paper, can be used. The maximum paper size that can be used in the inkjet printing device 1 is, for example, 750 mm x 585 mm.

[0043] The paper feeder 20 takes out the sheets P from the stack set therein one by one in order from the top, and supplies them to the supply path 14 of the transport path 12 .

[0044] The pretreatment liquid application unit 30 applies a pretreatment liquid to the paper P. The pretreatment liquid may be called a "precoat," "preconditioner," "undercoat liquid," or "treatment agent." The pretreatment liquid is a liquid that has the function of aggregating, insolubilizing, or thickening colorant components in ink. The pretreatment liquid application unit 30 includes a pretreatment liquid application drum 32 and a pretreatment liquid application device 33. The pretreatment liquid application drum 32 receives the paper P from the paper feed drum 24 and transports the received paper P to the pretreatment liquid drying unit 35. The pretreatment liquid application drum 32 includes a gripper (not shown) on its circumferential surface. The gripper grips the leading edge of the paper P and rotates, thereby wrapping the paper P around the drum circumferential surface and transporting it.

[0045] The pretreatment liquid application device 33 includes an application roller 34, and applies pretreatment liquid to the paper P transported by the pretreatment liquid application drum 32. The application roller 34 is supported by a contact / separation mechanism (not shown) that is movable between an application position where the application roller 34 comes into contact with the paper P to apply pretreatment liquid to the paper P and a retracted position where the application roller 34 is separated from the paper P and does not apply pretreatment liquid.

[0046] The area where the pretreatment liquid is applied to the paper P may be a full application where the pretreatment liquid is applied to the entire paper P, or a partial application where the pretreatment liquid is applied to a portion of the area where ink is applied in the image forming unit 40. From the viewpoints of uniformly adjusting the amount of pretreatment liquid applied, uniformly recording thin lines and fine image portions, and suppressing density unevenness such as image irregularities, a full application where the pretreatment liquid is applied to the entire image forming surface of the paper P by application using an application roller or the like is preferred.

[0047] The method for applying the pretreatment liquid is not limited to the roller application method, and other methods may be applied to the pretreatment liquid application device 33. Examples of other methods for the pretreatment liquid application device 33 include application using a blade, ejection using an inkjet method, and spraying using a spray method.

[0048] The pretreatment liquid drying unit 35 dries the paper P on which the pretreatment liquid has been applied. The pretreatment liquid drying unit 35 includes a pretreatment liquid drying drum 36. The pretreatment liquid drying drum 36 receives the paper P from the pretreatment liquid application drum 32 and transports the received paper P to the image forming unit 40. The pretreatment liquid drying drum 36 includes a gripper (not shown) on its circumferential surface. The pretreatment liquid drying drum 36 transports the paper P by rotating while gripping the leading edge of the paper P with the gripper. The circumferential surface of the pretreatment liquid drying drum 36 is made of a material with high thermal conductivity, such as metal. The circumferential surface is heated by a heat source, such as a heater, provided inside the circumferential surface, thereby drying the pretreatment liquid while the paper P is transported by the pretreatment liquid drying drum 36.

[0049] The image forming unit 40 includes a printing drum 42 and a head unit 44. The printing drum 42 receives the paper P from the pretreatment liquid drying drum 36 and transports the received paper P to the drying unit 50 via the rotating drum 26. The printing drum 42 has grippers (not shown) on its circumferential surface, and by rotating while gripping the leading edge of the paper P with the grippers, the paper P is wound around the drum circumferential surface and transported. The printing drum 42 also has a suction mechanism (not shown), which adsorbs the paper P wound around the drum circumferential surface to the drum circumferential surface and transports it. Negative pressure is used for adsorption. The printing drum 42 has numerous suction holes on its circumferential surface, and by applying suction from the inside of the printing drum 42 through these suction holes, the paper P is adsorbed to the circumferential surface of the printing drum 42.

[0050] The head unit 44 includes inkjet heads 46C, 46M, 46Y, and 46K. The inkjet head 46C is a recording head that ejects droplets of cyan ink. The inkjet head 46M is a recording head that ejects droplets of magenta ink. The inkjet head 46Y is a recording head that ejects droplets of yellow ink. The inkjet head 46K is a recording head that ejects droplets of black ink. Each of the inkjet heads 46C, 46M, 46Y, and 46K is supplied with ink from an ink tank (not shown), which is an ink supply source of the corresponding color, via a piping path (not shown). For example, a water-based ink is used as the ink for drawing. Water-based ink refers to ink in which a coloring material such as a pigment or dye is dissolved or dispersed in water and / or a water-soluble solvent.

[0051] Ink droplets are ejected from at least one of the inkjet heads 46C, 46M, 46Y, and 46K toward the paper P being transported by the drawing drum 42, and the ejected droplets adhere to the paper P, thereby forming an image on the paper P.

[0052] In this example, a configuration using four ink colors, CMYK, is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, special color ink, etc. may be added as needed. For example, a configuration is also possible in which inkjet heads that eject light-colored inks such as light cyan and light magenta are added, and / or inkjet heads that eject special color inks such as green, orange, or white are added. Furthermore, the arrangement order of the inkjet heads of each color is not particularly limited.

[0053] The drying unit 50 is capable of performing pre-drying, which dries the paper P before an image is formed on it. In addition to pre-drying, the drying unit 50 is also capable of performing post-drying, which dries the image formed on the paper P after the image has been formed by the image forming unit 40, that is, evaporates the ink solvent. In this embodiment, pre-drying refers to a drying process that is performed before processing the paper P, including applying a pretreatment liquid.

[0054] The drying unit 50 applies heat to the paper P to dry it. The drying unit 50 includes, as an example, a belt conveyor 54 equipped with a heating belt 51. The belt conveyor 54 includes a drive roller 52 and a driven roller 53 in addition to the heating belt 51. The belt conveyor 54, which conveys the paper P, constitutes part of the conveying mechanism 10. The heating belt 51 is a belt having a conveying surface made of a highly thermally conductive material such as metal, and is heated from the back side of the conveying surface by a heat source such as a heater (not shown). The paper P is heated by the heating belt 51 while being conveyed along the heating belt 51. The temperature of the conveying surface of the heating belt 51 is set to a desired temperature, for example, in the range of 80°C to 150°C, and the temperature can be changed as needed.

[0055] The heating belt 51 has a plurality of suction holes for suctioning and conveying the paper P. A suction box (not shown) is disposed in the space between the drive roller 52 and the driven roller 53 on the rear side of the conveying surface of the heating belt 51. The suction box is connected to an exhaust pump (not shown). A vacuum blower such as a ring blower can be used as the exhaust pump. The suction box generates suction pressure in the suction holes of the heating belt 51. This allows the paper P to be adsorbed to the conveying surface.

[0056] The paper P is transferred from the image forming drum 42 to the rotating drum 26 and then to a chain gripper (not shown), and with the leading edge of the paper P gripped by the gripper, the paper P is placed on the heating belt 51 and is adsorbed to the heating belt 51. The heating belt 51 and the gripper are fed at approximately the same speed. As a result, the paper P is heated and dried by the heating belt 51 while being transported by the chain gripper and heating belt 51.

[0057] The inkjet printing device 1 has a first mode in which pre-drying is performed on the paper P, and a second mode in which pre-drying is not performed, and the processor 100 controls switching between the first mode and the second mode. Specifically, the processor 100 switches between the first mode and the second mode by controlling the transport mechanism 10 to switch the transport path of the paper P in the transport path 12. Details of the transport path and the processing by the processor 100 will be described later.

[0058] The stacking device 60 stacks the image-formed sheets P. The stacking device 60 receives the sheets P discharged from the discharge path 15 of the transport path 12, and stacks the sheets P in a bundle on a stacking tray (not shown).

[0059] In the inkjet printing apparatus 1, by continuously supplying a plurality of sheets of paper P to the transport path 12, it is possible to sequentially form images on the plurality of sheets of paper P. In this embodiment, the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, and the drying unit 50 can process each of the plurality of sheets of paper P that are continuously supplied. The drying unit 50 is configured to be able to perform both pre-drying and post-drying on each of the plurality of sheets of paper P that are continuously supplied. When the first mode is selected, the drying unit 50 performs pre-drying and post-drying on each of the plurality of sheets of paper P that are continuously supplied, and when the second mode is selected, it performs only post-drying on each of the plurality of sheets of paper P that are continuously supplied.

[0060] 5 is a functional block diagram showing a schematic configuration of a control system of the inkjet printing apparatus 1. In addition to a processor 100, the inkjet printing apparatus 1 includes a storage device 102, a communication unit 104, an input device 106, and a display device 108.

[0061] The processor 100 includes a CPU (Central Processing Unit). The processor 100 functions as a processing unit and / or a control unit that performs various processes by executing instructions of a program stored in the storage device 102. The processor 100 comprehensively controls the conveyance mechanism 10, the paper feed device 20, the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, the drying unit 50, and the stacking device 60.

[0062] The storage device 102 is a computer-readable medium that is a non-transitory tangible entity. The storage device 102 includes a memory that is a main storage device and a storage that is an auxiliary storage device. The storage device 102 may be, for example, a semiconductor memory, a hard disk drive (HDD) device, a solid state drive (SSD) device, or a combination of these. A part or all of the storage area of ​​the storage device 102 may be included in the processor 100.

[0063] The storage device 102 stores various parameters used in the inkjet printing apparatus 1 and programs used in each section of the inkjet printing apparatus 1. The storage device 102 also functions as a temporary storage section for various data including image data.

[0064] Various parameters stored in the storage device 102 are read out via the processor 100 and set in each part of the device. Various programs stored in the storage device 102 are read out via the processor 100 and executed in each part of the device.

[0065] The communication unit 104 has a required communication interface. The inkjet printing apparatus 1 is connected to the host computer 110 via the communication unit 104, and can send and receive data to and from the host computer 110. Here, "connection" includes a wired connection, a wireless connection, or a combination of these. The communication unit 104 may be equipped with a buffer memory for speeding up communication processing. The communication unit 104 serves as an image input interface unit for acquiring image data representing an image to be printed. The image data acquired from the host computer 110 via the communication unit 104 is stored in the storage device 102.

[0066] The input device 106 is configured by, for example, operation buttons, a keyboard, a mouse, a touch panel, a multi-touch screen, other pointing devices, a voice input device, or an appropriate combination of these. The input device 106 accepts various inputs from an operator.

[0067] The display device 108 is configured by, for example, a liquid crystal display, an organic electro-luminescence (OEL) display, a projector, or an appropriate combination of these.

[0068] Information input via the input device 106 is sent to the processor 100. The processor 100 causes each unit to execute various processes in accordance with the information input from the input device 106.

[0069] The display device 108 can display various information such as various setting information of the device or abnormality information in response to commands from the processor 100. A user (operator) can set various parameters and input and edit various information using the input device 106 while viewing the content displayed on the display device 108.

[0070] "Conveyance Path" Figure 6 is a schematic diagram of the conveyance path 12 for paper P. As shown in Figure 6, the conveyance path 12 from paper feed to paper discharge has a circular path 13, a supply path 14, and a discharge path 15. In Figure 6, to simplify the explanation of the conveyance path, the paths are labeled A to F. The supply path 14 is made up of path A, the discharge path 15 is made up of path C, and the switchback section 16 is made up of path E. The circular path 13 is made up of path B from the first connection section 21 to the second connection section 22, path D from the second connection section 22 to the third connection section 23, and path F from the third connection section 23 to the first connection section 21.

[0071] 6 , the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, and the drying unit 50 are arranged on path B, which is part of the circular path 13. As described above, the inkjet printing device 1 is configured to be switchable between a first mode in which pre-drying is performed on the paper P and a second mode in which pre-drying is not performed. The inkjet printing device 1 is also configured to be selectively switchable between a single-sided printing mode and a double-sided printing mode. Depending on the combination of these modes, the transport path is switched, and the paper P is transported along the transport path appropriate for each mode.

[0072] The inkjet printing device 1 includes, as an example, the following four modes, which are determined by whether printing is single-sided or double-sided and whether pre-drying is performed: (1) Single-sided printing without pre-drying (second mode), (2) Single-sided printing with pre-drying (first mode), (3) Double-sided printing without pre-drying (second mode), (4) Double-sided printing with pre-drying (first mode).

[0073] 7A to 7D show the first transport path R1 to the fourth transport path R4 in each of modes (1) to (4). In FIGS. 7A to 7D, the first transport path R1 to the fourth transport path R4 are indicated by two-dot chain lines relative to the transport path 12. In FIGS. 7A to 7D, to clarify the orientation and front / back of the paper P, the orientation and front / back of the paper P when supplied from the supply path 14 are set to the initial state, and a triangle (△) is added to the leading edge Pc of the first side Pa of the paper P in the traveling direction in the initial state (see FIG. 7A). The side to which the triangle is added is the first side Pa, its back side is the second side Pb, and the end to which the triangle is added is the leading edge Pc in the traveling direction when supplied. The same applies to FIGS. 10 and 11. 7A to 7D, for the sake of simplicity, the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, and the drying unit 50 are omitted. However, as described above, these units are arranged on the path B, and processing by each unit is appropriately performed while the paper P passes through the path B.

[0074] (1) In the single-sided printing mode without pre-drying, the paper P is transported along the first transport path R1 that passes through paths A-B-C. That is, in this mode, the paper P does not make a full circuit around the circular path 13, and the circular path 13 passes only through path B, which is a part of the circular path 13. Because pre-drying is not performed, the paper P is fed from path A to path B, and in path B, the pretreatment liquid application unit 30 applies pretreatment liquid to one side (here, the first side Pa), the pretreatment liquid drying unit 35 dries the pretreatment liquid, the image forming unit 40 forms an image on one side, and the drying unit 50 post-drys the paper P. Then, the paper P with the image printed on one side is discharged from path C without making a circuit around the circular path 13.

[0075] (2) In the single-sided printing mode with pre-drying, the paper P is transported along the second transport path R2, which passes through the path A-B-D-F-B-C. That is, in this mode, the paper P passes through path B of the circular path 13 twice, completing one and a half revolutions around the circular path 13. Because pre-drying is performed, when the paper P is fed from path A to path B and passes through path B for the first time, the application of pretreatment liquid to the paper P and image formation are not performed, and only pre-drying by the drying unit 50 is performed. The paper P is transported back to path B via paths D and F, and when it passes through path B for the second time, the application of pretreatment liquid to one side (here, the first side Pa), drying of the pretreatment liquid, image formation on one side, and post-drying are performed in this order. The paper P with the image printed on one side is then discharged from path C.

[0076] (3) In the no-pre-drying, double-sided printing mode, the paper P is transported along the third transport path R3, which passes through the path A-B-D-E-E-F-B-C. In this mode, the paper P passes through path B of the circular path 13 twice, completing one and a half revolutions around the circular path 13. In this case, by passing through the switchback unit 16 along the way, the front and rear edges and front and back sides of the paper when passing through path B are reversed between the first and second passes. Because pre-drying is not performed, when the paper P fed from path A to path B passes through path B for the first time, the application of pretreatment liquid to the first side Pa (one side of the paper P), drying of the pretreatment liquid, image formation on the first side Pa, and post-drying are performed in this order. The paper P is pulled into the switchback unit 16 from path B through path D and travels back and forth along path E, thereby reversing the front and rear edges of the paper P and the front and back sides of the paper P when passing through path B. When the paper P passes through path B for the second time, the second side Pb, which is the reverse side of the first side Pa of the paper P, becomes the image forming side, and the application of the pretreatment liquid to the second side Pb, drying of the pretreatment liquid, image formation on the second side Pb, and post-drying are performed in this order. Then, the paper P with images printed on both sides is discharged from path C.

[0077] (4) In the double-sided printing mode with pre-drying, the paper P is transported along the fourth transport path R4, which passes through the path A-B-D-F-B-D-E-E-F-B-C. In this mode, the paper P passes through path B of the circular path 13 three times, completing two and a half revolutions around the circular path 13. In this case, by passing through the switchback section 16 midway through the second revolution, the front and rear edges and front and back sides of the paper P are reversed between the first, second, and third revolutions when passing through path B. Because pre-drying is performed by the drying unit 50, when the paper P fed from path A passes through path B for the first time, application of pre-treatment liquid to the paper P and image formation are not performed; only pre-drying by the drying unit 50 is performed. The paper P is transported back to path B via paths D and F, and when it passes through path B for the second time, application of pre-treatment liquid to the first side Pa, which is one side of the paper P, drying of the pre-treatment liquid, image formation on the first side Pa, and post-drying are performed in this order. The paper P passes through path D again, and is then drawn into switchback section 16 and travels back and forth along path E, reversing the leading and trailing ends of the paper P in the traveling direction, and is also turned over when it passes through path B for the third time. When the paper P passes through path B for the third time, the second side Pb, which is the back side of the first side Pa of the paper P, becomes the image forming surface, and the application of pretreatment liquid to the second side Pb, drying of the pretreatment liquid, image formation on the second side Pb, and post-drying are carried out in this order. Then, the paper P with images printed on both the first side Pa and the second side Pb is discharged from path C.

[0078] In this way, modes (1) to (4) are switched by switching between the first transport path R1 to the fourth transport path R4. As shown in Figures 7A to 7D, at least a portion of the transport path 12 is shared between the single-sided printing modes (1) and (2) and the double-sided printing modes (3) and (4). The first transport path R1 to the fourth transport path R4 in modes (1) to (4) are merely examples, and the transport paths in each mode are not limited to those described above. For example, to increase the strength of the printed sheet after printing, mode (1) may be realized by a transport path that passes through path A-B-D-F-B-C, which makes one and a half revolutions around the circular path 13. After printing on one side via path B for the first time, post-drying alone may be performed again via path B for the second time.

[0079] "Processing by Processor 100" Processor 100 accepts a designation of single-sided printing or double-sided printing from input device 106. In addition, processor 100, for example, accepts information about paper P from input device 106 and, based on this information, switches between a first mode in which pre-drying is performed and a second mode in which pre-drying is not performed. Here, switching between the first mode and the second mode means setting to the first mode or the second mode based on information about paper P. For example, processor 100 sets the transport path for paper P to a transport path corresponding to the first mode or a transport path corresponding to the second mode.

[0080] The information about the paper P is, for example, the type of paper P. Examples of paper types include fine paper, coated paper, and art paper. A table T such as that shown in FIG. 8 , which associates the type of paper used in the inkjet printing device 1 with whether pre-drying is required, is stored in advance in the storage device 102. In table T shown in FIG. 8 , the first mode is associated with the paper type "A," the second mode is associated with the paper type "B," and the second mode is associated with the paper type "C." The processor 100 receives the type of paper P, reads table T from the storage device 102, and sets either the first mode or the second mode. If the input type of paper P is "A," the first mode is selected; if the type of paper P is "B," the second mode is selected.

[0081] When creating table T in advance, for example, paper whose average moisture content is equal to or greater than a specified moisture content is set as a first mode, and paper whose average moisture content is less than the specified moisture content is set as a second mode. The specified moisture content is, for example, 5%, 4.8%, 4.5%, etc., with 4.8% being particularly preferable. In this specification, "moisture content" refers to the percentage of moisture contained in paper P (moisture content). Furthermore, paper type and thickness may be combined, and for example, coated paper whose thickness is equal to or greater than a specified thickness may be set as a first mode, and paper whose thickness is less than the specified thickness may be set as a second mode. The specified thickness varies depending on the paper type; for example, for gloss coated paper, it is 0.188 mm.

[0082] The information about the paper P to be received may also include the moisture content of the paper P. The processor 100 receives the moisture content of the paper P as information about the paper P. For example, if the received moisture content is equal to or greater than a specified moisture content, the processor 100 sets the paper P to the first mode (i.e., with pre-drying). If the received moisture content is less than the specified moisture content, the processor 100 sets the paper P to the second mode (i.e., without pre-drying). The specified moisture content can be freely set. Here, the specified moisture content may be, for example, 5%, 4.8%, or 4.5%, with 4.8% being particularly preferred. The specified moisture content is pre-stored in the storage device 102. When the processor 100 receives a moisture content as information about the paper, the processor 100 reads the specified moisture content from the storage device 102, compares the received moisture content with the specified moisture content, and sets the paper P to the first or second mode. The operator may input the general moisture content of the paper P through the input device 106, or may input the moisture content measured with a moisture meter before loading the paper P into the paper feeder 20.

[0083] Furthermore, the information about the paper P to be received may include the thickness of the paper P. When the type of paper P to be used is set as a default, the processor 100 receives the thickness of the paper P as information about the paper P, and, for example, sets the first mode if the thickness is equal to or greater than a specified thickness, and the second mode if the thickness is less than the specified thickness. The specified thickness is stored in advance in the storage device 102, and when the processor 100 receives a thickness as information about the paper, it reads the specified thickness from the storage device 102, compares the received thickness with the specified thickness, and sets the first mode or the second mode. Note that the information about the paper P may be a combination of the type of paper and the thickness.

[0084] The processor 100 sets the above-mentioned modes (1) to (4) based on the information from the input device 106. That is, the processor 100 controls the conveying mechanism 10 to switch the conveying path to one of the first conveying path R1 to the fourth conveying path R4. Switching the conveying path to the first conveying path R1 to the fourth conveying path R2 is achieved by switching the first branch guide 17a of the first path switching mechanism 17, switching the second branch guide 18a of the second path switching mechanism 18, and / or switching the rotation direction of the conveying rollers 16d, e of the switchback unit 16, etc.

[0085] The transport mechanism 10 includes elements of a mechanism related to the transport of the paper P from the paper feed device 20 to the stacking device 60 described in FIG. 1 . Specifically, the transport mechanism 10 includes the paper feed drum 24, the pretreatment liquid application drum 32, the pretreatment liquid drying drum 36, the image forming drum 42, the rotating drum 26, the belt conveyor 54, a chain gripper (not shown), and transport rollers (not shown), all of which are shown in FIG. 1 . The transport mechanism 10 also includes drive units such as a motor (not shown) and a motor drive circuit (not shown) serving as a power source. The processor 100 controls the elements of the transport mechanism 10 so as to transport the paper P from the paper feed device 20 to the stacking device 60 according to the set transport path. The processor 100 controls the paper feed device 20 to start feeding the paper P, stop feeding the paper P, and the like.

[0086] The processor 100 performs various types of image processing, such as conversion processing, correction processing, and halftone processing, on image data to be printed.

[0087] The processor 100 operates the pretreatment liquid application unit 30 and the pretreatment liquid drying unit 35. The processor 100 controls the application operation of the pretreatment liquid application device 33, such as the amount and timing of application of the pretreatment liquid. The processor 100 controls the pretreatment liquid drying unit 35 to control the drying output, drying time, etc. The drying output is the output of the heat source, and, for example, if the heat source is a heater, it is the heater output, and if the heat source is a hot air blower, it is the temperature and flow rate of the hot air blown out from the hot air blower.

[0088] The processor 100 operates the image forming unit 40. Based on the dot data of each ink color generated through image processing, the processor 100 controls the ejection operations of the inkjet heads 46C, 46M, 46Y, and 46K so as to record an image on the paper P transported by the image forming drum 42.

[0089] The processor 100 also operates the drying unit 50. The processor 100 controls the drying unit 50 to control the drying output and / or drying time. It is preferable that the processor 100 controls the drying unit 50 based on information about the paper P to control the drying output when post-drying is performed. In this case, the processor 100 determines whether the amount of organic solvent on the paper P is 160 μg / cm ２ For example, it is preferable to control the drying output of the post-drying under the following conditions: ２ The following drying conditions are examined to create a table that associates the type of paper P with the drying conditions, and the table is stored in the storage device 102. The processor 100 then receives the type of paper P as information about the paper P, reads the table from the storage device 102, and controls the drying output to correspond to the type of paper P.

[0090] The processor 100 may also control the drying output and / or drying time when pre-drying is performed based on the type of paper, moisture content, thickness, or the like, as input information about the paper P. For example, a table correlating information about the paper P with the drying output of pre-drying may be stored in advance in the storage device 102, and the processor 100 may receive information about the paper P, read the table from the storage device 102, and control the drying unit 50 to obtain the corresponding drying output. The processor 100 may also receive information about the paper P and, according to that information, control the drying unit 50 to set a higher drying output the greater the moisture content and a lower drying output the less moisture content, or to set a higher drying output the thicker the paper is and a lower drying output the thinner the paper is.

[0091] The hardware structure of the processor 100 may be any of the various processors listed below. The various processors include a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as dedicated electrical circuits such as a PLD (Programmable Logic Device) that can change its circuit configuration after manufacture, such as an FPGA (Field-Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit), which is a processor with a circuit configuration designed specifically for executing specific processing.

[0092] The above-described processing may be performed by one of these various processors, or by a combination of two or more processors of the same or different types (e.g., a plurality of FPGAs, or a combination of a CPU and an FPGA). Furthermore, a plurality of processing units may be configured by a single processor. An example of configuring a plurality of processing units by a single processor is a system-on-chip (SOC), in which a processor is used to realize the functions of an entire system including a plurality of processing units on a single IC (Integrated Circuit) chip.

[0093] Furthermore, more specifically, the hardware structure of these processors can be an electric circuit that combines circuit elements such as semiconductor elements.

[0094] "Printing Process Flow in Inkjet Printing Apparatus 1" An example of the flow of printing processes in the inkjet printing apparatus 1 will be described with reference to FIG.

[0095] First, in step S11, the processor 100 receives information about the paper P and information about whether single-sided printing or double-sided printing is to be performed. For example, the processor 100 receives input of information about the paper P and information specifying whether single-sided printing or double-sided printing is to be performed from the input device 106.

[0096] In step S12, the processor 100 determines whether the printing is one-sided or two-sided. If the determination result in step S12 is "one-sided printing," the process proceeds to step S13.

[0097] In step S13, the processor 100 determines whether the first mode, i.e., whether pre-drying is performed, is selected based on the information about the paper P. Here, not being in the first mode means being in the second mode, i.e., without pre-drying.

[0098] If the determination result in step S13 is not the "first mode," the process proceeds to step S14. In step S14, the processor 100 controls the transport mechanism 10 to set the transport path R1 to execute the (1) single-sided printing mode without pre-drying. Next, in step S15, the processor 100 controls the transport mechanism 10, the paper feed device 20, the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, the drying unit 50, and the stacking device 60 to execute the single-sided printing process without pre-drying.

[0099] On the other hand, if the determination result in step S13 is the "first mode," the process proceeds to step S16. In step S16, the processor 100 controls the transport mechanism 10 to set the second transport path R2 for executing the (2) pre-drying, single-sided printing mode. Next, in step S17, the processor 100 controls the transport mechanism 10, the paper feed device 20, the pre-treatment liquid application unit 30, the pre-treatment liquid drying unit 35, the image forming unit 40, the drying unit 50, and the stacking device 60 to execute pre-drying, single-sided printing processing.

[0100] If the determination result in step S12 is not "single-sided printing," i.e., if it is "double-sided printing," the process proceeds to step S23, where the processor 100 determines, based on information about the paper P, whether the first mode, i.e., with pre-drying, or the second mode, i.e., only with pre-drying, is selected.

[0101] If the determination result in step S23 is not "first mode," the process proceeds to step S24. In step S24, the processor 100 controls the transport mechanism 10 to set the transport path R3 to execute the (3) double-sided printing mode without pre-drying. Next, in step S25, the processor 100 controls the transport mechanism 10, the paper feed device 20, the pretreatment liquid application unit 30, the pretreatment liquid drying unit 35, the image forming unit 40, the drying unit 50, and the stacking device 60 to execute double-sided printing without pre-drying.

[0102] If the determination result in step S23 is "first mode," the process proceeds to step S26. In step S26, the processor 100 controls the transport mechanism 10 to set the fourth transport path R4 for executing the (4) pre-drying double-sided printing mode. Next, in step S27, the processor 100 controls the transport mechanism 10, the paper feed device 20, the pre-treatment liquid application unit 30, the pre-treatment liquid drying unit 35, the image forming unit 40, the drying unit 50, and the stacking device 60 to execute pre-drying double-sided printing processing.

[0103] In this way, the printing process is executed in either mode, and then the printing process ends.

[0104] As described above, the inkjet printing apparatus 1 according to this embodiment includes a conveying mechanism 10, an image forming unit 40, a drying unit 50, and a processor 100 that controls these units. The processor 100 can switch between a first mode in which pre-drying is performed on a recording medium (paper P in this example) and a second mode in which pre-drying is not performed. This configuration allows the presence or absence of pre-drying to be set depending on the recording medium, thereby reducing poor quality image formation. By using the second mode in which pre-drying is not performed on recording media that do not require pre-drying, throughput can be improved and deformation of the recording medium due to over-drying can be reduced. By performing pre-drying on recording media that require pre-drying, the drying time after image formation can be reduced.

[0105] In the inkjet printing device 1 of the above embodiment, pre-drying and post-drying are performed using the same drying unit 50, so it is possible to reduce unit costs, power consumption, and the device size compared to when separate drying units are provided for pre-drying and post-drying.

[0106] In the inkjet printing device 1 of the above embodiment, the processor 100 can switch the path (transport path) along which the recording medium is transported by controlling the transport mechanism 10, and switching the transport path switches between the first mode and the second mode. In this way, switching the transport path switches between the first mode and the second mode, which can simplify the device configuration in some cases compared to when switching between the presence and absence of pre-drying by a method other than switching the transport path.

[0107] In the inkjet printing apparatus 1 of the above embodiment, the processor 100 is configured to receive information about the recording medium and switch between the first mode and the second mode based on that information. The operator simply inputs information about the recording medium, and the inkjet printing apparatus 1 sets the mode appropriate for the recording medium and executes the printing process, reducing the burden on the operator.

[0108] In the inkjet printing device 1 of the above embodiment, throughput is improved because multiple sheets of paper P can be continuously supplied to the transport path 12, thereby allowing image formation to be performed sequentially on the multiple sheets of paper P. The drying unit 50 performs both pre-drying and post-drying for each of the multiple sheets of paper P, thereby simplifying the device configuration.

[0109] 10 and 11 show a specific example of a case where a plurality of sheets P are continuously supplied to the transport path 12. FIG.

[0110] 10, it is preferable that the paper sheets P indicated by the solid lines to be pre-dried in the drying unit 50 and the paper sheets P indicated by the broken lines to be post-dried are alternately supplied to the path B in the conveying path 12, which is a section where the units 30, 35, 40, and 50 are arranged. This is because the paper sheets P (in FIG. 10) are supplied from the path A to the path B of the circular path 13 at the first connecting portion 21. Ｎ＋２ ) and the paper P (in FIG. 10 ) is supplied from the path F to the path B in the circular path 13. Ｎ＋３ This can be achieved by controlling the transport timing of the paper P so that the transport of the first and second sheets alternate. Here, the paper P supplied from path A to path B is a paper on which pre-drying is performed, and the paper P2 transported from path F to path B is a paper on which pre-drying has been completed and on which image formation and post-drying are performed. Such continuous transport of paper is assumed, for example, in the case of (2) single-sided printing mode with pre-drying.

[0111] According to the configuration shown in FIG. 10, the drying unit 50 is configured to dry a plurality of sheets P that pass continuously through the section of the transport path 12 where the drying unit 50 is arranged, i.e., the path B. １ , P ２ ....P Ｎ , P Ｎ＋１ For example, the Nth sheet of paper P Ｎ Pre-drying is performed on the N+1 sheet of paper P Ｎ＋１ According to this configuration, the throughput can be improved compared to the case where the next sheet P is supplied after both pre-drying and post-drying for one sheet P are completed.

[0112] 11, in the case of the double-sided printing mode with pre-drying of (4), it is preferable that the paper P indicated by the solid line, which is pre-dried in the drying unit 50, the paper P indicated by the broken line, which is post-drying of the first side Pa, and the paper P indicated by the dashed line, which is post-drying of the second side Pb, are supplied in this order to the path B, which is the section in the conveying path 12 where the units 30, 35, 40, and 50 are arranged. This is, for example, when the paper P (paper P in FIG. 11) is supplied from the path A, which is the supply path, to the path B in the first connection part 21. Ｎ＋３ ) and the paper P (paper P in FIG. 10) is transferred from the path F to the path B without being switched back during the circular path. Ｎ＋４ ) and paper P (paper P in the figure) that is switched back during the circular path and transferred from path F to path B Ｎ＋５ This can be achieved by controlling the transport timing of the paper P so that the transfer of the first side (Pa) and the second side (Pb) are carried out in this order. Here, the paper P supplied from path A to path B is a paper on which pre-drying is performed. The paper P transferred from path F to path B without switching back is a paper on which pre-drying has been completed and on which image formation on the first side (Pa) and post-drying are performed. The paper P switched back and transferred from path F to path B is a paper on which image formation on the first side (Pa) has been completed and on which image formation on the second side (Pb) and post-drying are performed.

[0113] According to the configuration shown in FIG. 11, the drying unit 50 is configured to dry a plurality of sheets P that pass continuously through the section of the transport path 12 where the drying unit 50 is arranged, i.e., the path B. １ , P ２ ....P Ｎ , P Ｎ＋１ ..., the Nth sheet of paper P Ｎ Pre-drying is performed for the N+1th sheet of paper P Ｎ＋１ Then, post-drying is performed on the image formed on the first side Pa, and the N+2th sheet P Ｎ＋２ For the image formed on the second side Pb, post-drying is performed. With this configuration, it is possible to improve throughput in the double-sided printing mode.

[0114] "Modifications of Drying Unit 50" In the above embodiment, the drying unit 50 includes a heating belt 51, and the heating belt 51 heats and dries the paper P. However, the configuration of the drying unit 50 is not limited to this. The drying unit 50 may include any device that is effective in reducing the moisture content of the paper P, such as a heat roller, a hot air blower, an infrared (IR) heater, a microwave generator, a superheated steam generator, a UV lamp, or an IR lamp. The drying unit 50 may include a combination of devices, not limited to one type, that reduce the moisture content of the paper P. FIGS. 12A to 12L show modified drying units 50A to 50L.

[0115] 12A, the drying unit 50A may include, in addition to the heating belt 51, infrared (IR) heaters 56 inside the drive roller 52 and the driven roller 53 and at positions facing the conveying surface of the heating belt 51. In this case, the drying unit 50A can heat and dry the paper P conveyed on the heating belt 51 from both sides.

[0116] 12B, the drying unit 50B may be configured without the heating belt 51, but with a normal conveyor belt 57 and only an IR heater 56 disposed in a position facing the conveying surface of the conveyor belt 57. In this case, the drying unit 50B dries the paper P conveyed on the conveyor belt 57 by heating it with the IR heater 56. Here, the normal conveyor belt 57 means a belt whose conveying surface is not made of a material with high thermal conductivity, such as metal.

[0117] 12C , the drying unit 50C may be configured without the heating belt 51, but with a normal conveyor belt 57, and with only an IR heater 56 disposed opposite the rotating drum 26 that receives the paper P from the imaging drum 42. In this case, the drying unit 50C uses the IR heater 56 to heat and dry the paper P being attracted to and conveyed by the rotating drum 26.

[0118] 12D , in addition to the heating belt 51, the drying unit 50D may include an IR heater 56 inside the rotating drum 26 that receives the paper P from the imaging drum 42. In this case, the drying unit 50D heats and dries the paper P being transported to the rotating drum 26 with the IR heater 56, and also heats and dries the paper P being transported on the heating belt 51.

[0119] 12E, the drying unit 50E may include, in addition to the heating belt 51, IR heaters 56 inside the drive roller 52 and the driven roller 53, and a hot air blower 58 disposed opposite the conveying surface of the heating belt 51. In this case, the drying unit 50E can heat and dry the paper P conveyed on the heating belt 51 from both sides.

[0120] 12F, the drying unit 50F may be configured without the heating belt 51, and may include only a warm air blower 58 disposed opposite a normal conveyor belt 57. In this case, the drying unit 50F heats and dries the paper P by blowing warm air from the warm air blower 58 onto the paper P conveyed on the conveyor belt 57.

[0121] 12G, the drying unit 50G may be configured without the heating belt 51, but with a normal conveyor belt 57, and with only a warm air blower 58 disposed opposite the rotating drum 26 that receives the paper P from the imaging drum 42. In this case, the drying unit 50G heats and dries the paper P being adsorbed and conveyed to the rotating drum 26 by blowing warm air from the warm air blower 58 onto the paper P, thereby drying it.

[0122] 12H , in addition to the heating belt 51, the drying unit 50H may include IR heaters 56 inside the drive roller 52 and the driven roller 53, and may also include a hot air blower 58 located inside the rotating drum 26 that receives the paper P from the imaging drum 42. In this case, the drying unit 50H heats and dries the paper P being adsorbed and transported to the rotating drum 26 by using the hot air blower 58 to blow hot air from the rotating drum 26 side, and also heats and dries the paper P being transported on the heating belt 51.

[0123] 12I, the drying unit 50I may be configured to include, in addition to the heating belt 51, IR heaters 56 inside the drive roller 52 and the driven roller 53, and also include the IR heater 56 and a hot air blower 58 arranged opposite the conveying surface of the heating belt 51. In this case, the drying unit 50I can heat and dry the paper P conveyed on the heating belt 51 from both sides.

[0124] 12J, the drying unit 50J may not include the heating belt 51, but may include an IR heater 56 and a hot air blower 58 arranged opposite a normal conveyor belt 57. In this case, the drying unit 50J heats the paper P conveyed on the conveyor belt 57 with the IR heater 56, and also heats and dries the paper P by blowing hot air from the hot air blower 58 onto the paper P.

[0125] 12K, the drying unit 50K may be configured without the heating belt 51, but with a normal conveyor belt 57, and with an IR heater 56 and a hot air blower 58 arranged opposite the rotating drum 26 that receives the paper P from the imaging drum 42. In this case, the drying unit 50K heats the paper P being conveyed to the rotating drum 26 with the IR heater 56, and also heats and dries the paper P by blowing hot air from the hot air blower 58 onto the paper P.

[0126] 12L , in addition to the heating belt 51, the drying unit 50L may include IR heaters 56 inside the drive roller 52 and the driven roller 53, and may also include the IR heater 56 and a hot air blower 58 arranged inside the rotating drum 26 that receives the paper P from the imaging drum 42. In this case, the drying unit 50L can heat and dry the paper P that is being attracted to and transported on the rotating drum 26 using the IR heater, and can also heat the paper P by blowing hot air from the hot air blower 58 onto the paper P, and can heat and dry the paper P that is being transported on the heating belt 51.

[0127] "Modifications of the Pretreatment Liquid Drying Unit 35" In the above-described embodiment, the pretreatment liquid drying unit 35 includes the pretreatment liquid drying drum 36, and the paper P is heated and dried by the pretreatment liquid drying drum 36. However, the configuration of the pretreatment liquid drying unit 35 is not limited to this. The pretreatment liquid drying unit 35 may have any configuration as long as it has the effect of drying the pretreatment liquid. FIGS. 13A to 13F show modified pretreatment liquid drying units 35A to 35F.

[0128] 13A includes an IR heater 38 inside the pretreatment liquid drying drum 36. The pretreatment liquid applied to the paper P transported on the pretreatment liquid drying drum 36 is dried by the paper P being heated by the heated circumferential surface of the pretreatment liquid drying drum 36 and by the IR heater 38.

[0129] 13B includes a hot air blower 39 inside the pretreatment liquid drying drum 36. The pretreatment liquid applied to the sheet P transported through the pretreatment liquid drying drum 36 is dried by the sheet P being heated by the heated circumferential surface of the pretreatment liquid drying drum 36 and by hot air blown onto the sheet P from the hot air blower 39.

[0130] 13C includes an IR heater 38 and a hot air blower 39 inside the pretreatment liquid drying drum 36. The pretreatment liquid applied to the paper P transported through the pretreatment liquid drying drum 36 is dried by heating the paper P on the heated circumferential surface of the pretreatment liquid drying drum 36, heating by the IR heater 38, and heating by blowing hot air from the hot air blower 39 onto the paper P.

[0131] 13D includes an IR heater 38 disposed opposite the pretreatment liquid drying drum 36. The pretreatment liquid applied to the paper P transported along the pretreatment liquid drying drum 36 is dried by the paper P being heated by the heated circumferential surface of the pretreatment liquid drying drum 36 and by the IR heater 38.

[0132] 13E includes a hot air blower 39 disposed opposite the pretreatment liquid drying drum 36. The pretreatment liquid applied to the sheet P transported along the pretreatment liquid drying drum 36 is dried by the sheet P being heated by the heated circumferential surface of the pretreatment liquid drying drum 36 and by hot air blown onto the sheet P from the hot air blower 39.

[0133] 13F includes an IR heater 38 and a hot air blower 39 that are disposed opposite the pretreatment liquid drying drum 36. The pretreatment liquid applied to the sheet P transported along the pretreatment liquid drying drum 36 is dried by heating the sheet P on the heated circumferential surface of the pretreatment liquid drying drum 36, heating by the IR heater 38, and heating by blowing hot air from the hot air blower 39 onto the sheet P.

[0134] In the pretreatment liquid drying units 35A to 35F, the transport surface of the pretreatment liquid drying drum 36 is made of a material with high thermal conductivity. However, in the case where the IR heater 38 and / or the hot air blower 39 are provided, the transport surface of the pretreatment liquid drying drum 36 may not be made of a material with high thermal conductivity.

[0135] Other Modifications In the above embodiment, the pre-drying is performed by the drying unit 50. However, if the pre-treatment liquid drying unit 35 is provided as in the above embodiment, the pre-drying may be performed by the pre-treatment liquid drying unit 35. Alternatively, the pre-drying may be performed by both the pre-treatment liquid drying unit 35 and the drying unit 50. An appropriate transport path may be set depending on whether the pre-drying is performed by the pre-treatment liquid drying unit 35 or the drying unit 50. In the above embodiment, the pre-treatment liquid application step is performed before the image formation step. However, the inkjet printing apparatus 1 may be configured to have a mode in which pre-treatment is performed and a mode in which pre-treatment is not performed, and to be switchable between a mode with pre-treatment and a mode without pre-treatment.

[0136] Furthermore, the image forming apparatus of the present disclosure may be configured without the pretreatment liquid application unit 30 and the pretreatment liquid drying unit 35, as in a modified inkjet printing apparatus 2 shown in Fig. 14. In Fig. 14, the same components as those in the inkjet printing apparatus 1 shown in Fig. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. The inkjet printing apparatus 2 does not include the pretreatment liquid application unit 30 and the pretreatment liquid drying unit 35, but the other configuration is the same as that of the inkjet printing apparatus 1 described above. The printing process is also the same as in the above embodiment, except that it does not include the pretreatment liquid application process and the pretreatment liquid drying process.

[0137] Although the inkjet printing device 1 including the image forming unit 40 that forms images using an inkjet method has been described above, the image forming device of the present disclosure is not limited to inkjet printing devices. The image forming device of the present disclosure can also be applied to printing devices that include an image forming unit that forms images using an electrophotographic method or transfer printing, for example.

[0138] In the above embodiment, an example has been described in which sheet paper P is used as the recording medium, but the medium used for recording images is not limited to sheet paper, and may be a continuous medium such as continuous paper. Furthermore, the sheet paper is not limited to cut paper that has been cut to a predetermined size in advance, but may be obtained by cutting a continuous medium to a predetermined size as needed.

[0139] The term "recording medium" is a general term for various terms such as paper, recording paper, printing paper, printing medium, print medium, print-receiving medium, image-forming medium, image-receiving medium, image-receiving medium, and ejection-receiving medium. The material and shape of the medium are not particularly limited, and various sheet bodies can be used, regardless of material or shape, such as sticker paper, resin sheet, film, cloth, nonwoven fabric, etc. Furthermore, the recording medium is not limited to a sheet body, and may be an inflexible medium such as a building material.

[0140] The configurations described in the above embodiments and the features described in the modified examples can be used in appropriate combinations, and some features can also be replaced.

[0141] The embodiments of the present disclosure described above may have their constituent elements modified, added, or deleted as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited to the embodiments described above, and many modifications may be made by those having ordinary skill in the relevant art within the technical concept of the present disclosure.

[0142] The following supplementary notes are further disclosed regarding the above embodiments. <Supplementary Note 1> An image forming apparatus including: a transport mechanism having a transport path for transporting a recording medium; an image forming unit that forms an image on the recording medium; a drying unit capable of performing pre-drying to dry the recording medium before image formation; and a processor that controls the transport mechanism, the image forming unit, and the drying unit, wherein the processor is capable of switching between a first mode in which pre-drying is performed and a second mode in which pre-drying is not performed. <Supplementary Note 2> The image forming apparatus according to Supplementary Note 1, wherein the drying unit is capable of performing post-drying to dry an image formed on the recording medium after the image has been formed in the image forming unit, in addition to pre-drying. <Supplementary Note 3> The image forming apparatus according to Supplementary Note 2, wherein the processor is capable of switching the path for transporting the recording medium by controlling the transport mechanism, and wherein switching the path switches between the first mode and the second mode. <Supplementary Note 4> The image forming apparatus according to Supplementary Note 2 or Supplementary Note 3, wherein image formation is performed sequentially on a plurality of recording media by continuously supplying the plurality of recording media to a conveying path, and wherein the drying unit performs both pre-drying and post-drying on each of the plurality of recording media. <Supplementary Note 5> The image forming apparatus according to Supplementary Note 4, wherein, of a plurality of recording media that continuously pass through a section of the conveying path in which the drying unit is arranged, the drying unit performs pre-drying on the Nth recording medium and post-drying on the N+1th recording medium. <Supplementary Note 6> The image forming apparatus according to any one of Supplements 2 to 5, wherein the image forming apparatus has two printing modes: a single-sided printing mode in which an image is formed on only one side of the recording medium, and a double-sided printing mode in which images are formed on both the first and second sides of the recording medium. <Supplementary Note 7> The image forming apparatus according to Supplementary Note 6, wherein at least a part of the conveying path is shared between the single-sided printing mode and the double-sided printing mode.<Supplementary Note 8> The image forming device according to Supplementary Note 7, in which the image forming mode is double-sided printing, and the multiple recording media are continuously supplied to the conveying path to sequentially form images on the multiple recording media, and the drying unit performs both pre-drying and post-drying on each of the multiple recording media, of the multiple recording media that continuously pass through the section of the conveying path where the drying unit is located, the drying unit performs pre-drying on the Nth recording medium, performs post-drying on the image formed on the first side of the N+1th recording medium after image formation on the first side, and performs post-drying on the image formed on the second side of the N+2th recording medium after image formation on the second side. <Supplementary Note 9> The image forming apparatus according to any one of Supplementary Notes 2 to 8, wherein the transport mechanism has a circulatory path on which the image forming unit and the drying unit are arranged and on which the recording medium circulates, a supply path that supplies the recording medium to the circulatory path, a discharge path that discharges the recording medium from the circulatory path, and a switchback section that temporarily pulls the recording medium out of the circulatory path to reverse the direction of travel of the recording medium, and the transport mechanism further includes a first path switching mechanism that switches the path of the recording medium at a connection between the circulatory path and the discharge path between a path toward the discharge path and a path along the circulatory path, and a second path switching mechanism that switches the path of the recording medium at a connection between the circulatory path and the switchback section between a path toward the switchback section and a path along the circulatory path, and the processor switches the path of the recording medium by controlling the first path switching mechanism and the second path switching mechanism. <Supplementary Note 10> The image forming apparatus according to any one of Supplementary Notes 1 to 9, wherein the processor receives information about the recording medium, and switches between the first mode and the second mode based on the information. <Supplementary Note 11> The image forming apparatus according to Supplementary Note 10, wherein the information about the recording medium includes the moisture content of the recording medium, and the processor selects the first mode when the recording medium has a moisture content exceeding a predetermined specified moisture content, and selects the second mode when the recording medium has a moisture content equal to or less than the specified moisture content. <Supplementary Note 12> The image forming apparatus according to Supplementary Note 11, wherein the specified moisture content is 4.8%.<Supplementary Note 13> The image forming apparatus according to Supplementary Note 10, wherein the information about the recording medium includes a thickness of the recording medium, and the processor selects a first mode when the recording medium is thicker than a predetermined specified thickness, and selects a second mode when the recording medium is thicker than the specified thickness. <Supplementary Note 14> The image forming apparatus according to any one of Supplementary Notes 10 to 13, wherein the drying unit is capable of performing post-drying in addition to pre-drying, which dries an image formed on the recording medium after the image is formed in the image forming unit, and the processor controls the drying unit based on the information about the recording medium to control the drying output when post-drying is performed. <Supplementary Note 15> The processor controls the amount of organic solvent on the recording medium to be 160 μg / cm. ２ The image forming apparatus according to Appendix 14, which controls the drying output under the following conditions. <Appendix 16> The image forming apparatus according to any one of Appendixes 1 to 15, wherein pre-drying is a drying process carried out before processing of the recording medium, including application of a pretreatment liquid. <Appendix 17> The image forming apparatus according to Appendix 16, further comprising: a treatment liquid application unit that applies pretreatment liquid to an image forming surface of the recording medium before an image is formed on the recording medium, before image formation by the image forming unit; and a pretreatment liquid drying unit that dries the image forming surface to which the pretreatment liquid has been applied. <Appendix 18> The image forming apparatus according to any one of Appendixes 1 to 17, wherein the image forming unit is a unit that forms an image by an inkjet method. <Appendix 19> The image forming apparatus according to any one of Appendixes 1 to 18, wherein the recording medium is paper.

[0143] The disclosure of Japanese Patent Application No. 2023-197533, filed on November 21, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. An image forming device comprising: a transport mechanism having a transport path for transporting a recording medium; an image forming unit for forming an image on the recording medium; a drying unit capable of performing pre-drying to dry the recording medium before image formation; and a processor for controlling the transport mechanism, the image forming unit and the drying unit, wherein the processor is capable of switching between a first mode in which the pre-drying is performed and a second mode in which the pre-drying is not performed.

2. The image forming apparatus according to claim 1, wherein the drying unit is capable of performing, in addition to the pre-drying, post-drying for drying the image formed on the recording medium after the image has been formed in the image forming unit.

3. The image forming apparatus according to claim 2, wherein the processor is capable of switching a path for transporting the recording medium by controlling the transport mechanism, and switching between the first mode and the second mode is achieved by switching the path.

4. The image forming apparatus according to claim 2, wherein image formation is performed sequentially on the plurality of recording media by continuously supplying the plurality of recording media to the transport path, and the drying unit performs both the pre-drying and the post-drying on each of the plurality of recording media.

5. The image forming apparatus of claim 4, wherein, among a plurality of recording media that continuously pass through a section of the transport path in which the drying unit is arranged, the drying unit performs the pre-drying on the Nth recording medium and performs the post-drying on the N+1th recording medium.

6. The image forming apparatus according to claim 2, further comprising two printing modes: a single-sided printing mode in which an image is formed on only one side of the recording medium, and a double-sided printing mode in which images are formed on both a first side and a second side of the recording medium.

7. The image forming apparatus according to claim 6, wherein at least a part of the transport path is shared between the single-sided printing mode and the double-sided printing mode.

8. The image forming device according to claim 7, wherein, in the double-sided printing mode, the multiple recording media are continuously supplied to the transport path to sequentially form images on the multiple recording media, and the drying unit performs both the pre-drying and the post-drying on each of the multiple recording media, among the multiple recording media that continuously pass through a section of the transport path in which the drying unit is located, the drying unit performs the pre-drying on the Nth recording medium, performs the post-drying on the image formed on the first side of the N+1th recording medium, and performs the post-drying on the image formed on the second side of the N+2th recording medium, after image formation on the second side.

9. The image forming apparatus of claim 3, wherein the transport mechanism includes a circulatory path along which the image forming unit and the drying unit are disposed and along which the recording medium circulates, a supply path that supplies the recording medium to the circulatory path, a discharge path that discharges the recording medium from the circulatory path, and a switchback section that temporarily pulls out the recording medium from the circulatory path to reverse the direction of travel of the recording medium, and the transport mechanism further includes a first path switching mechanism that switches the path of the recording medium between a path toward the discharge path and a path along the circulatory path at a connection between the circulatory path and the discharge path, and a second path switching mechanism that switches the path of the recording medium between a path toward the switchback section and a path along the circulatory path at a connection between the circulatory path and the switchback section, and the processor switches the path of the recording medium by controlling the first path switching mechanism and the second path switching mechanism.

10. The image forming apparatus according to any one of claims 1 to 9, wherein the processor receives information relating to the recording medium, and switches between the first mode and the second mode based on the information.

11. An image forming apparatus as described in claim 10, wherein the information regarding the recording medium includes the moisture content of the recording medium, and the processor selects the first mode when the recording medium is a recording medium with a moisture content exceeding a predetermined specified moisture content, and selects the second mode when the recording medium is a recording medium with a moisture content equal to or less than the specified moisture content.

12. The image forming apparatus according to claim 11, wherein the specified moisture content is 4.8%.

13. An image forming apparatus as described in claim 10, wherein the information regarding the recording medium includes a thickness of the recording medium, and the processor selects the first mode when the recording medium is a recording medium with a thickness exceeding a preset specified thickness, and selects the second mode when the recording medium is a recording medium with a thickness less than the specified thickness.

14. The image forming apparatus of claim 10, wherein the drying unit is capable of performing, in addition to the pre-drying, post-drying to dry an image formed on the recording medium after the image has been formed in the image forming unit, and the processor controls the drying unit based on the information regarding the recording medium to control the drying output when performing the post-drying.

15. The processor detects that the amount of organic solvent on the recording medium is 160 μg / cm ２ The image forming apparatus according to claim 14 , wherein the drying output is controlled under the following condition:

16. The image forming apparatus according to any one of claims 1 to 9, wherein the pre-drying is a drying step carried out before processing of the recording medium, including application of a pre-treatment liquid.

17. The image forming apparatus according to claim 16, further comprising: a pretreatment liquid application unit that applies the pretreatment liquid to an image forming surface of the recording medium before the image is formed thereon, prior to the image formation by the image forming unit; and a pretreatment liquid drying unit that dries the image forming surface to which the pretreatment liquid has been applied.

18. The image forming apparatus according to any one of claims 1 to 9, wherein the image forming unit is a unit that forms an image by an inkjet method.

19. The image forming apparatus according to any one of claims 1 to 9, wherein the recording medium is paper.

Images