Ink jet printer

Abstract

To provide a technique which can shorten time required for rising of a hot air dryer when drying a printing medium using the hot air dryer and an infrared dryer.SOLUTION: A drying mechanism 30 has a first heater unit 31, a second heater unit 32, a duct 33, a temperature sensor 35, and a flow rate adjustment section. The first heater unit 31 has a radiation heat source 311 for radiating radiation heat to a printing medium and a first body 312 having a first opening 313 for passing radiation heat and surrounding the radiation heat source 311. The second heater unit 32 has a hot air source 321 for generating hot air and a second body 322 having a second opening 328 for passing hot air and surrounding the hot air source 321. The duct 33 makes atmosphere in the first body 312 and atmosphere in the second body 322 communicate with each other. The temperature sensor 35 detects a temperature of hot air from the hot air source 321. The flow rate adjustment section adjusts flow rate of an air flow passing through the duct 33 on the basis of a detection result by the temperature sensor 35.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an inkjet printing apparatus that performs printing by ejecting ink onto a print medium such as paper.

[0002] Conventionally, there is known a printing device that performs printing by ejecting ink onto the surface of a long strip-shaped continuous substrate while transporting the continuous substrate with a plurality of transport rollers or the like. Such a printing device is provided with a drying mechanism that dries the ink ejected onto the continuous substrate while transporting the continuous substrate. An inkjet printing device provided with such an ink drying mechanism is described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-016949 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the offset printing press (1) of Patent Document 1, a discharge device (5) is provided downstream of printing mechanisms (8a-8f) that print on the sheets. In the discharge device (5), dryer units (11a-11d) are arranged in sequence in the conveying direction of the sheets (paragraph 0017). The dryer units (11a-11d) are composed of a hot air dryer, an infrared dryer, a UV dryer, or a combination dryer. In the case of a combination dryer, the sheets are dried by both hot air and light energy (paragraph 0020).

[0005] However, when using a hot air dryer and an infrared dryer, the time required for the hot air dryer to start up after starting by turning on the power, etc. is significantly longer than that required for the infrared dryer. Specifically, the hot air dryer may take a long time, about several tens of minutes, after starting up until it can generate hot air at a predetermined temperature. This may result in a decrease in work efficiency.

[0006] The present invention has been developed in consideration of the above circumstances, and aims to provide technology that can shorten the time it takes for a hot air dryer to start up after being turned on when drying printing media using a hot air dryer and an infrared dryer. [Means for solving the problem]

[0007] In order to solve the above problems, a first invention of the present application is an inkjet printing device that prints by ejecting ink onto a print medium, the inkjet printing device having a transport mechanism, an ejection head, and a drying mechanism. The transport mechanism transports the print medium along a predetermined transport path. The ejection head ejects droplets of the ink onto the surface of the print medium transported by the transport mechanism. The drying mechanism heats the print medium onto which the ink droplets have been ejected, downstream of the transport path from the ejection head. The drying mechanism has a first heater unit, a second heater unit, a duct, a temperature sensor, and a flow rate adjustment unit. The first heater unit has a radiant heat source that radiates radiant heat to the print medium, and a first housing that has a first opening that allows the radiant heat to pass and surrounds the radiant heat source. The second heater unit is provided separately from the first heater unit and includes a hot air source that generates hot air, and a second housing that has a second opening through which the hot air passes and surrounds the hot air source. The duct connects a first communication hole that communicates an internal space of the first housing with an external space at a position separated from the first opening, and a second communication hole that communicates an internal space of the second housing with an external space at a position separated from the second opening, thereby communicating an atmosphere in the first housing with an atmosphere in the second housing. The temperature sensor detects the temperature of the hot air generated from the hot air source. The flow rate adjustment unit adjusts the flow rate of the air flow passing through the internal passage of the duct based on the detection result by the temperature sensor.

[0008] The second invention of the present application is an inkjet printing device of the first invention, wherein the flow rate adjustment unit is a blower fan provided in the duct and whose rotation speed is adjustable, and when the blower fan rotates, an airflow is generated from within the first housing to within the second housing.

[0009] A third invention of the present application is the inkjet printing apparatus of the first invention, wherein the flow rate adjusting portion is provided in the duct and is an opening / closing valve whose opening degree is adjustable.

[0010] A fourth invention of the present application is an inkjet printing device of any one of the first to third inventions, wherein the first heater unit further has a shutter plate that can open and close the first opening from outside the first housing, and a blackbody surface is formed on an opposing surface of the shutter plate that faces the radiant heat source when the first opening is closed.

[0011] A fifth invention of the present application is an inkjet printing device according to any one of the first to fourth inventions, wherein the first housing further has a hot air introduction hole spaced apart from the first communication hole and the first opening, connecting the internal space of the first housing with the external space, and the drying mechanism further has a second duct having an upstream end facing the second opening or communicating with the atmosphere inside the second housing and a downstream end communicating with the hot air introduction hole, and allowing the hot air to pass through its internal passage. Effect of the Invention

[0012] According to the first to fifth aspects of the present application, when the atmosphere in the second housing is low temperature, the atmosphere warmed by the radiant heat source in the first housing can be supplied to the second housing through the duct. This can support the warm air generated in the second housing to increase in temperature, thereby shortening the time required for the warm air to reach a predetermined temperature. Moreover, after the warm air reaches the predetermined temperature, the supply of the atmosphere in the first housing is stopped, thereby preventing the warm air from increasing in temperature too much.

[0013] In particular, according to the fourth aspect of the present invention, the black body absorbs radiant heat and generates heat, thereby making it possible to heat the atmosphere inside the first housing more efficiently.

[0014] In particular, according to the fifth aspect of the present invention, the hot air generated from the hot air source until the hot air reaches a predetermined temperature can be supplied into the first housing through the second duct, thereby making it possible to more efficiently heat the atmosphere in the first housing. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram conceptually illustrating a configuration of an inkjet printing apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a vertical cross-sectional view showing a schematic configuration of a drying mechanism of the first embodiment. [Diagram 3] 2 is a block diagram showing connections between a control unit and each unit of an inkjet printing apparatus according to a first embodiment. FIG. [Figure 4] 5 is a flowchart showing a procedure for starting up a drying mechanism in the first embodiment. [Diagram 5] FIG. 11 is a vertical cross-sectional view showing a schematic configuration of a drying mechanism according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the components described in the embodiment are merely examples, and are not intended to limit the scope of the present invention. In addition, in the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary for ease of understanding.

[0017] <1. First embodiment> <1-1. Configuration of Inkjet Printing Device> FIG. 1 is a conceptual diagram showing the configuration of an inkjet printing apparatus 1 according to a first embodiment of the present invention. This inkjet printing apparatus 1 is an inkjet printer that records characters and images on the surface of a long strip-shaped continuous substrate 9 by ejecting droplets of water-based ink from a plurality of ejection heads 21 toward the continuous substrate 9 while transporting the continuous substrate 9. However, the long strip-shaped continuous substrate 9 is merely one example of a printing medium. The printing medium may be paper, or may be a substrate made of plastic film, cardboard, metal foil, or glass. In other words, the inkjet printing apparatus 1 may be any device that ejects ink onto a printing medium to perform printing.

[0018] As shown in FIG. 1, the inkjet printing apparatus 1 includes a transport mechanism 10, a printing mechanism 20, a drying mechanism 30, and a control unit 90.

[0019] The transport mechanism 10 transports the continuous base material 9 in a transport direction along a predetermined transport path TR, the transport mechanism 10 being aligned with the longitudinal direction of the continuous base material 9. The transport mechanism 10 transports the continuous base material 9 by a roll-to-roll method. The transport mechanism 10 has a feed roller 11, a plurality of transport rollers 12, a winding roller 13, and a rotation drive unit 15. The feed roller 11, the plurality of transport rollers 12, and the winding roller 13 are rotatable about a horizontal axis extending in a direction perpendicular to the transport direction. The rotation drive unit 15 rotates the winding roller 13 by driving a motor or the like (not shown). The rotation drive unit 15 may rotate rollers other than the winding roller 13 (such as the transport roller 12).

[0020] The feed roller 11 pays out the continuous base material 9 wound in a roll. Each transport roller 12 is arranged along the transport path TR of the continuous base material 9. The multiple transport rollers 12 support the continuous base material 9 fed from the feed roller 11 on the predetermined transport path TR. The winding roller 13 winds up the continuous base material 9 that has passed through the transport path TR into a roll. In FIG. 1, the transport direction of the continuous base material 9 along the transport path TR is appropriately indicated by an arrow.

[0021] The printing mechanism 20 has a plurality of (four in this embodiment) ejection heads 21. All of the four ejection heads 21 have a printable width larger than the size of the continuous base material 9 in the lateral direction (a direction perpendicular and substantially horizontal to the transport direction, and a direction perpendicular to the paper surface of FIG. 1) and have the same structure. The four ejection heads 21 are arranged in order along the transport path TR at intervals from each other in the transport direction. Each of the four ejection heads 21 ejects ink droplets from a plurality of nozzles (not shown) toward the surface (upper surface) of the continuous base material 9 transported by the transport mechanism 10. The four ejection heads 21 eject ink droplets of each color, K (Black), C (Cyan), M (Magenta), and Y (Yellow), in order toward the downstream side of the transport path, and record monochromatic images on the surface (upper surface) of the continuous base material 9. The ink droplets of K, C, M, and Y become color components of a color image. Then, a multi-color image is formed on the upper surface of the continuous base material 9 by superimposing the four single-color images.

[0022] The drying mechanism 30 is disposed downstream of the printing mechanism 20 in the transport direction. The drying mechanism 30 heats the continuous base material 9 onto which ink droplets are ejected by the four ejection heads 21, downstream of the transport path of the four ejection heads 21, while being transported by the transport mechanism 10. The drying mechanism 30 dries the ink ejected onto the upper surface of the continuous base material 9 by heating the continuous base material 9. The drying mechanism 30 in this embodiment is disposed above the transport path TR of the continuous base material 9. However, the position at which the drying mechanism 30 is disposed is not limited to this.

[0023] Fig. 2 is a vertical cross-sectional view showing a schematic configuration of the drying mechanism 30. As shown in Fig. 2, the drying mechanism 30 has a first heater unit 31, a second heater unit 32, a duct 33, a temperature sensor 35, a first blower fan 331, a second blower fan 332, and a third blower fan 336.

[0024] The first heater unit 31 has a plurality of (two in this embodiment) radiant heat sources 311 and a first housing 312. The radiant heat sources 311 are heating elements constituted by so-called carbon heaters. The radiant heat sources 311 are connected to a power source via an on / off circuit (not shown). The radiant heat sources 311 generate heat when electricity flows through the carbon fibers inside the radiant heat sources 311 when energized, and radiate radiant heat such as infrared rays. The radiant heat sources 311 radiate radiant heat to the continuous base material 9, which is a printing medium. This heats the continuous base material 9 being transported near the first heater unit 31. As a result, it is possible to evaporate mainly the moisture in the ink discharged onto the upper surface of the continuous base material 9. In addition, the radiant heat sources 311 themselves generate heat, and thus the atmosphere inside the first housing 312 can be warmed.

[0025] The first housing 312 is a housing that forms the outer wall of the first heater unit 31. The first housing 312 of this embodiment has a rectangular parallelepiped shape composed of a side wall 317, a bottom 318, and a top plate 319. However, the shape of the first housing 312 is not limited to this. Two radiant heat sources 311 are accommodated in the internal space of the first housing 312. That is, the first housing 312 surrounds each of the radiant heat sources 311. In addition, the inner surface of the first housing 312 (particularly, the lower surface of the top plate 319, etc.) is mirror-finished. This allows the radiant heat from the two radiant heat sources 311 to be reflected, and more radiant heat can be radiated to the continuous base material 9 outside the first housing 312 through each first opening 313 described later. The first housing 312 may be further covered from the outside with a heat insulating material not shown. This makes it possible to further increase the temperature of the atmosphere within first housing 312 when each radiant heat source 311 is energized.

[0026] A plurality of (two in this embodiment) first openings 313 are provided in the bottom 318 of the first housing 312. Each of the two first openings 313 penetrates the bottom 318 and communicates the internal space of the first housing 312 with the external space. The two first openings 313 can expose the internal space of the first housing 312 to the external space below the first housing 312. This allows each first opening 313 to pass radiant heat from the radiant heat source 311 and radiate the radiant heat to the continuous base material 9 transported below the first housing 312.

[0027] A shutter plate 36 and a shutter movement mechanism (not shown) are disposed near each first opening 313 of the first housing 312. Each shutter plate 36 extends in a plate shape along the lower surface of the bottom 318 of the first housing 312. Furthermore, when the first housing 312 is viewed from below, each shutter plate 36 is larger than the first opening 313. This allows each shutter plate 36 to close the first opening 313 from below without any gaps when it is in a closing position Pc described below.

[0028] The shutter movement mechanism reciprocates the shutter plate 36 along the bottom 318 of the first housing 312 between a closing position Pc where the shutter plate 36 completely closes the first opening 313 from below, and an opening position Po horizontally spaced from the closing position Pc where the shutter plate 36 opens the first opening 313. Note that in FIG. 2, the shutter plate 36 positioned at the opening position Po is illustrated by a dashed line. This allows the shutter plate 36 to open and close the first opening 313 from the outside of the first housing 312. However, the structure for opening and closing the shutter plate 36 is not limited to this.

[0029] In addition, the upper surface of the shutter plate 36 of this embodiment is coated with a black body to be painted black. The black body is, for example, "soot" or "platinum black". As a result, a black body surface 361 is formed on the upper surface of the shutter plate 36. That is, the black body surface 361 is formed on the facing surface of the shutter plate 36 that faces the radiant heat source 311 when the first opening 313 is closed. When the first opening 313 is closed by the shutter plate 36, the black body forming the black body surface 361 absorbs the radiant heat radiated from the radiant heat source 311 and generates heat. As a result, the atmosphere inside the first housing 312 can be heated more efficiently. However, instead of forming the black body surface 361 on the upper surface of the shutter plate 36, an infrared absorbing film or the like may be formed.

[0030] Further, a first communication hole 314 is formed in the side wall 317 of the first housing 312. The first communication hole 314 penetrates the side wall 317 of the first housing 312, and communicates the internal space of the first housing 312 with the external space. However, the position at which the first communication hole 314 is formed is not limited thereto. The first communication hole 314 may be provided in a position separated from the first opening 313.

[0031] Furthermore, a plurality of (three in this embodiment) outside air introduction holes 315 are formed in the top plate portion 319 of the first housing 312. The three outside air introduction holes 315 each penetrate the top plate portion 319 of the first housing 312 and communicate the internal space of the first housing 312 with the external space. This allows outside air to be appropriately taken in from the external space to the internal space of the first housing 312. However, the position at which each outside air introduction hole 315 is formed is not limited thereto. Each outside air introduction hole 315 may be provided at a position separated from the first opening 313 and the first communication hole 314.

[0032] The second heater unit 32 is provided separately from the first heater unit 31, and has a plurality of (three in this embodiment) hot air sources 321 and a second housing 322. The hot air source 321 is a so-called sheath heater, and has a nichrome wire, which is a heating element covered with a metal pipe. The nichrome wire is a spiral resistor, and is connected to a power source via an on / off circuit (not shown). When electricity is applied, the nichrome wire generates heat by flowing electricity through it, and heats the air that comes into contact with the nichrome wire. This allows the hot air source 321 to generate hot air (including hot air) of about several tens of degrees Celsius to several hundred and several tens of degrees Celsius. The hot air source 321 generates hot air and supplies it toward the continuous base material 9 that is being transported near the second heater unit 32. As a result, it is possible to dry mainly the solvent component in the ink discharged onto the upper surface of the continuous base material 9.

[0033] Here, the time required for the warm air source 321 to start up after being turned on is significantly longer than that required for the radiant heat source 311. Specifically, if no measures are taken, the warm air source 321 may require a long time, on the order of several tens of minutes, after being turned on until it can generate warm air (including hot air) at a predetermined temperature.

[0034] The second housing 322 is a housing that forms the outer wall of the second heater unit 32. The second housing 322 of this embodiment has a hollow shape composed of a side wall 323, a bottom portion 324, and a top plate portion 325. The side wall 323 has a substantially cylindrical three-dimensional shape. The bottom portion 324 is a funnel-shaped portion that gradually converges from the lower end of the side wall 323 downward. The top plate portion 325 covers the upper portion of the side wall 323. The shape of the second housing 322 is not limited to this. For example, the side wall 323 of the second housing 322 may be a rectangular tube.

[0035] Three hot air sources 321 are housed in the internal space of the second housing 322. That is, the second housing 322 surrounds each hot air source 321. The second housing 322 may be further covered from the outside with a heat insulating material (not shown). This makes it possible to further increase the temperature of the atmosphere inside the second housing 322 when the hot air source 321 is energized.

[0036] A second opening 328 is provided at the center of the bottom 324 of the second housing 322. The second opening 328 communicates the internal space of the second housing 322 with the external space. In the second opening 328, the internal space of the second housing 322 can be exposed to the external space below the second housing 322. This allows the second opening 328 to pass hot air generated from the hot air source 321. In addition, the second opening 328 is provided with a plurality of nozzle valves (not shown). The hot air generated from the hot air source 321 is supplied from the plurality of nozzle valves to the continuous base material 9 transported below the second housing 322.

[0037] Further, a second communication hole 326 is formed in the side wall 323 of the second housing 322. The second communication hole 326 penetrates the side wall 323 of the second housing 322 and communicates the internal space of the second housing 322 with the external space. However, the position at which the second communication hole 326 is formed is not limited thereto. The second communication hole 326 may be provided at a position separated from the second opening 328.

[0038] A temperature sensor 35 is mounted near the second opening 328 of the second housing 322. The temperature sensor 35 detects the temperature of the warm air passing through the second opening 328. The temperature sensor 35 is also electrically connected to the control unit 90. The temperature sensor 35 outputs data related to the detection result of the warm air temperature to the control unit 90. However, the position where the temperature sensor 35 is mounted is not limited thereto. The temperature sensor 35 may be any sensor that detects the temperature of the warm air (including hot air) generated from the warm air source 321 and outputs the detection result to the control unit 90.

[0039] The duct 33 is a pipe for passing a high-temperature airflow through its internal passage. The duct 33 is formed from a material having thermal insulation properties, or is covered from the outside with a thermal insulation material (not shown). This makes it possible to suppress a decrease in the temperature of the airflow passing through the internal passage of the duct 33. The upstream end of the duct 33 is connected to the first communication hole 314 of the first housing 312, and the downstream end is connected to the second communication hole 326 of the second housing 322. That is, the duct 33 connects the first communication hole 314 and the second communication hole 326, and communicates the atmosphere in the first housing 312 with the atmosphere in the second housing 322.

[0040] A first blower fan 331 is inserted in an internal passage near the upstream end of the duct 33. A second blower fan 332 is inserted in an internal passage near the downstream end of the duct 33. That is, the first blower fan 331 and the second blower fan 332 are each provided in the duct 33. The first blower fan 331 and the second blower fan 332 each use an axial flow type fan motor that rotates an impeller using the driving force of a motor (not shown) to generate an airflow from the upstream end side of the duct 33 to the downstream end side of the duct 33. The rotation of the first blower fan 331 and the second blower fan 332 generates an airflow from inside the first housing 312 to inside the second housing 322.

[0041] The first blower fan 331 and the second blower fan 332 can adjust their rotation speeds. In addition, the first blower fan 331 and the second blower fan 332 are each electrically connected to the control unit 90. The control unit 90 adjusts the rotation speeds of the first blower fan 331 and the second blower fan 332 based on data input from the temperature sensor 35. This makes it possible to adjust the flow rate of the air flow passing through the internal passage of the duct 33. That is, the first blower fan 331 and the second blower fan 332 can adjust the flow rate of the air flow passing through the internal passage of the duct 33 based on the detection result by the temperature sensor 35. The first blower fan 331 and the second blower fan 332 are each an example of a "flow rate adjustment unit" of the present invention.

[0042] A branch pipe 38 is connected to a branch position Pb between the upstream end and downstream end of the duct 33. The upstream end of the branch pipe 38 is open to an external space of the branch pipe 38 (preferably an external space of the inkjet printing apparatus 1). Furthermore, an internal passage of the branch pipe 38 is connected in communication with an internal passage of the duct 33 at the branch position Pb where the downstream end of the branch pipe 38 is located.

[0043] Further, a third blower fan 336 is inserted in the internal passage near the upstream end of the branch pipe 38. The third blower fan 336 uses an axial flow type fan motor that rotates an impeller using the driving force of a motor (not shown) to generate an airflow from the upstream end side (external space) of the branch pipe 38 to the downstream end side (branch position Pb) of the branch pipe 38. By rotating the third blower fan 336, an airflow is generated that flows from the external space through the internal passage of the branch pipe 38 to the internal passage of the duct 33.

[0044] The third blower fan 336 is capable of adjusting its rotation speed. The third blower fan 336 is electrically connected to the control unit 90. The control unit 90 adjusts the rotation speed of the third blower fan 336 based on data input from the temperature sensor 35. This makes it possible to adjust the flow rate of the airflow passing through the internal passage of the branch pipe 38. That is, the third blower fan 336 can adjust the flow rate of the airflow passing through the internal passage of the branch pipe 38 based on the detection result by the temperature sensor 35.

[0045] Next, the control unit 90 will be described. The control unit 90 is an information processing device for controlling each part of the inkjet printing apparatus 1. Fig. 3 is a block diagram showing the connection between the control unit 90 and each part of the inkjet printing apparatus 1. As conceptually shown in Fig. 3, the control unit 90 has a processor 91 such as a CPU, a memory 92 such as a RAM, and a storage unit 93 such as a hard disk drive. The storage unit 93 stores a computer program 90P for executing a printing process while transporting the continuous base material 9, and for drying the continuous base material 9 onto which the ink has been ejected.

[0046] 3, the control unit 90 is communicatively connected to the transport mechanism 10, the four ejection heads 21 of the printing mechanism 20, the two radiant heat sources 311 of the first heater unit 31 of the drying mechanism 30, the three hot air sources 321 of the second heater unit 32, the first blower fan 331, the second blower fan 332, the third blower fan 336, and the temperature sensor 35. The processor 91 of the control unit 90 controls the operation of each of these units according to a computer program 90P. As a result, the transport and printing process of the continuous base material 9 proceeds, and the drying process of the continuous base material 9 onto which the ink has been ejected proceeds.

[0047] <1-2. Procedure for starting the drying mechanism and performing the drying process> Next, a procedure for starting up the drying mechanism 30 from a low temperature state and performing a drying process on the continuous base material 9 onto which the ink has been ejected will be described.

[0048] When starting up the drying mechanism 30, first, as a preliminary step, the control unit 90 drives the shutter movement mechanism of the first heater unit 31 to move each shutter plate 36 to the closing position Pc and close each first opening 313. Then, the power supply of the radiant heat source 311 of the first heater unit 31 is turned on to energize it, and the power supply of the hot air source 321 of the second heater unit 32 is turned on to energize the nichrome wire therein. In addition, the first blower fan 331, the second blower fan 332, and the third blower fan 336 are driven (step S1). At this time, the rotation speed of the first blower fan 331 is set to be significantly higher than the rotation speed of the third blower fan 336. At this time, it is not necessary to drive the third blower fan 336. In addition, the power supply of the temperature sensor 35 is turned on.

[0049] As a result, first, the radiant heat source 311 generates heat, and the black body forming the black body surface 361 of the shutter plate 36 absorbs the radiant heat radiated from the radiant heat source 311 and generates heat. Then, the atmosphere in the first housing 312 and the outside air flowing into the first housing 312 from each outside air introduction hole 315 become hot due to thermal conduction from the radiant heat source 311 and the black body surface 361. Then, the hot atmosphere in the first housing 312 flows into the internal passage of the duct 33 through the first communication hole 314, and flows into the second housing 322 through the second communication hole 326. Furthermore, the atmosphere in the second housing 322 and the atmosphere flowing into the second housing 322 through the second communication hole 326 come into contact with the nichrome wire of the hot air source 321 and are slightly warmed. The slightly warmed atmosphere inside the second housing 322 is then discharged downward from a plurality of nozzle valves provided in the second opening 328.

[0050] Also, the temperature sensor 35 starts detecting the temperature of the hot air sent out from the second opening 328 of the second heater unit 32. In this embodiment, as described above, the atmosphere heated by the radiant heat source 311 in the first housing 312 is supplied into the second housing 322 via the duct 33, thereby supporting the increase in temperature of the hot air generated in the second housing 322. This makes it possible to shorten the time required for the temperature of the hot air sent out from the multiple nozzle valves of the second opening 328 of the second housing 322 to reach a predetermined temperature or higher.

[0051] Next, the control unit 90 gradually reduces the rotation speed of the first blower fan 331 to a predetermined rotation speed or less (brings the rotation speed closer to zero) while checking that the temperature of the hot air blown out from the multiple nozzle valves of the second opening 328 is gradually increasing based on the data input from the temperature sensor 35. This substantially stops the airflow from inside the first housing 312 to inside the second housing 322. Meanwhile, the rotation speed of the third blower fan 336 is gradually increased (step S2).

[0052] Next, when the rotation speed of the first blower fan 331 becomes equal to or lower than a predetermined rotation speed, the control unit 90 judges whether or not the temperature of the hot air sent out from the multiple nozzle valves of the second opening 328, which is related to the detection result by the temperature sensor 35, is equal to or higher than a value (predetermined lower limit) required to dry the ink (step S3). If the detection result by the temperature sensor 35 is less than the predetermined lower limit (step S3: No), the control unit 90 judges that the temperature of the hot air sent out from the hot air source 321 is not yet sufficiently high, and again slightly increases the rotation speed of the first blower fan 331 (step S4), and again executes steps S2 to S3.

[0053] On the other hand, if the detection result by the temperature sensor 35 is equal to or higher than the value (predetermined lower limit) required to dry the ink (step S3: YES), the control unit 90 determines that the temperature of the hot air sent out from the hot air source 321 has risen sufficiently, and determines that the start-up of the drying mechanism 30 has been completed. Then, the transport of the continuous base material 9 and the printing process are started. The control unit 90 drives the shutter movement mechanism of the first heater unit 31 to move each shutter plate 36 to the open position Po and open each first opening 313. As a result, the radiant heat radiated from the radiant heat source 311 passes through the first opening 313 and heads downward.

[0054] The control unit 90 then operates the transport mechanism 10 to transport the continuous base material 9 in the longitudinal direction along a predetermined transport path TR, while controlling the four ejection heads 21 to eject ink droplets onto the surface (upper surface) of the continuous base material 9. This records an image on the surface of the continuous base material 9. Thereafter, when the continuous base material 9 arrives below the drying mechanism 30 located downstream of the printing mechanism 20, the radiant heat emitted from the radiant heat source 311 mainly evaporates the water in the ink ejected onto the surface of the continuous base material 9. In addition, the hot air supplied from the hot air source 321 mainly dries the solvent component in the ink, and the ink is fixed onto the surface of the continuous base material 9. As a result, the drying process of the image recorded on the surface of the continuous base material 9 is completed.

[0055] As described above, in this embodiment, when the atmosphere in the second housing 322 is low temperature, the atmosphere warmed by the radiant heat source 311 in the first housing 312 can be supplied into the second housing 322 via the duct 33. This can support the increase in temperature of the hot air generated in the second housing 322, thereby shortening the time required for the hot air to reach a predetermined temperature. In addition, after the hot air reaches the predetermined temperature, the supply of the atmosphere in the first housing 312 is stopped, thereby preventing the hot air sent out from the second housing 322 from rising too high in temperature.

[0056] <2. Second embodiment> Next, the configuration of an inkjet printing apparatus according to a second embodiment of the present invention will be described. In the following, differences from the first embodiment will be mainly described, and duplicated descriptions of parts equivalent to those of the first embodiment will be omitted. Figure 5 is a vertical cross-sectional view showing a schematic configuration of a drying mechanism 30B according to this embodiment.

[0057] 5, the drying mechanism 30B includes a first heater unit 31B, a second heater unit 32B, a duct 33B, a temperature sensor 35B, a second duct 37B, a first blower fan 331B, a second blower fan 332B, a third blower fan 336B, a fourth blower fan 371B, a fifth blower fan 372B, and a sixth blower fan 373B. The duct 33B, the temperature sensor 35B, the first blower fan 331B, the second blower fan 332B, and the third blower fan 336B of this embodiment have the same configurations as the duct 33, the temperature sensor 35, the first blower fan 331, the second blower fan 332, and the third blower fan 336 of the first embodiment.

[0058] A plurality of (two in this embodiment) outside air introduction holes 315B and a hot air introduction hole 316B are formed in a top plate portion 319B of a first housing 312B of the first heater unit 31B of this embodiment. The two outside air introduction holes 315B each penetrate the top plate portion 319B of the first housing 312B and communicate the internal space and the external space of the first housing 312B. This allows outside air to be appropriately taken in from the external space to the internal space of the first housing 312B.

[0059] The hot air introduction hole 316B penetrates the top plate portion 319B of the first housing 312B and communicates the internal space of the first housing 312B with the external space. However, the position where the hot air introduction hole 316B is formed is not limited thereto. The hot air introduction hole 316B may be provided at a position in the first housing 312B that is separated from the first communication hole 314B to which the duct 33B is connected and the first opening 313B through which the radiant heat from the radiant heat source 311B passes.

[0060] Further, a hot air outlet hole 327B is formed in the bottom 324B of the second housing 322B of the second heater unit 32B of this embodiment. The hot air outlet hole 327B penetrates the bottom 324B of the second housing 322B and connects the internal space of the second housing 322B to the external space.

[0061] The second duct 37B is a pipe for passing hot air through its internal passage. The second duct 37B is formed from a material having heat insulation properties, or is covered from the outside with a heat insulating material (not shown). This can suppress a decrease in the temperature of the air flow passing through the internal passage of the second duct 37B. The upstream end of the second duct 37B is connected to the hot air outlet hole 327B of the second housing 322B, and the downstream end is connected to the hot air introduction hole 316B of the first housing 312B. That is, the second duct 37B connects the hot air outlet hole 327B and the hot air introduction hole 316B, and communicates the atmosphere in the second housing 322B with the atmosphere in the first housing 312B.

[0062] However, the second housing 322B does not necessarily have to be provided with the hot air outlet hole 327B. In this case, the upstream end of the second duct 37B may be disposed so as to face the second opening 328B of the second housing 322B, or may be inserted into the second housing 322B through the second opening 328B. That is, the upstream end of the second duct 37B may face the second opening 328B or communicate with the atmosphere inside the second housing 322B, and the downstream end may communicate with the hot air introduction hole 316B.

[0063] A fourth blower fan 371B is inserted in an internal passage near the upstream end of the second duct 37B. A fifth blower fan 372B is inserted in an internal passage near the downstream end of the second duct 37B. The fourth blower fan 371B and the fifth blower fan 372B each use an axial fan motor that rotates an impeller using the driving force of a motor (not shown) to generate an airflow from the upstream end of the second duct 37B to the downstream end of the second duct 37B. By rotating the fourth blower fan 371B and the fifth blower fan 372B, an airflow is generated from inside the second housing 322B to inside the first housing 312B.

[0064] The fourth blower fan 371B and the fifth blower fan 372B can adjust their rotation speeds. In addition, the fourth blower fan 371B and the fifth blower fan 372B are each electrically connected to the control unit. The control unit adjusts the rotation speeds of the fourth blower fan 371B and the fifth blower fan 372B based on data input from the temperature sensor 35B. This allows the flow rate of the air flow passing through the internal passage of the second duct 37B to be adjusted. That is, the fourth blower fan 371B and the fifth blower fan 372B can adjust the flow rate of the air flow passing through the internal passage of the second duct 37B based on the detection result by the temperature sensor 35B.

[0065] A branch pipe 39B is connected to a branch position Pd between the upstream end and downstream end of the second duct 37B. The upstream end of the branch pipe 39B is open to the outside space. The internal passage of the branch pipe 39B is connected to the internal passage of the second duct 37B at the branch position Pd where the downstream end of the branch pipe 39B is located.

[0066] A sixth blower fan 373B is inserted in the internal passage near the upstream end of the branch pipe 39B. The sixth blower fan 373B uses an axial fan motor that rotates an impeller using the driving force of a motor (not shown) to generate an airflow from the upstream end side (external space) of the branch pipe 39B to the downstream end side (branch position Pd) of the branch pipe 39B. The rotation of the sixth blower fan 373B generates an airflow that flows from the external space through the internal passage of the branch pipe 39B to the internal passage of the second duct 37B.

[0067] The sixth blower fan 373B is capable of adjusting its rotation speed. The sixth blower fan 373B is electrically connected to the control unit. The control unit adjusts the rotation speed of the sixth blower fan 373B based on data input from the temperature sensor 35B. This makes it possible to adjust the flow rate of the airflow passing through the internal passage of the branch pipe 39B. That is, the sixth blower fan 373B can adjust the flow rate of the airflow passing through the internal passage of the branch pipe 39B based on the detection result by the temperature sensor 35B.

[0068] In this embodiment, when the drying mechanism 30B is started up to perform a drying process on the continuous base material onto which ink has been ejected, the same procedure as steps S1 to S4 described in the first embodiment is executed, and in step S1, the fourth blower fan 371B, the fifth blower fan 372B, and the sixth blower fan 373B are further driven. At this time, the rotation speed of the fourth blower fan 371B is set to be significantly higher than the rotation speed of the sixth blower fan 373B. At this time, it is not necessary to drive the sixth blower fan 373B.

[0069] As a result, in step S1, the atmosphere warmed by the radiant heat source 311B in the first housing 312B until the warm air generated from the warm air source 321B reaches a predetermined temperature is supplied to the second housing 322B via the duct 33B, and the warm air slightly warmed by the warm air source 321B in the second housing 322B can be supplied to the first housing 312B via the second duct 37B. That is, the warm air generated until the warm air generated from the warm air source 321B reaches a predetermined temperature is not sent downward (discarded) from the second opening 328B, but can be supplied to the first housing 312B via the second duct 37B. As a result, the atmosphere in the first housing 312B can be heated more efficiently.

[0070] In step S2, it is preferable to gradually decrease the rotation speed of the fourth blower fan 371B to a predetermined rotation speed or less (to approach substantially zero). On the other hand, it is preferable to gradually increase the rotation speed of the sixth blower fan 373B.

[0071] <3. Modifications> Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0072] In the drying mechanism of the above embodiment, the first blower fan and the second blower fan are provided to adjust the flow rate of the air flow passing through the internal passage of the duct. However, instead of the first blower fan, an opening / closing valve capable of adjusting its opening degree may be provided. That is, the "flow rate adjustment unit" of the present invention may be an opening / closing valve provided in the duct and capable of adjusting its opening degree. This makes it possible to adjust the flow rate of the air flow passing through the internal passage of the duct, as in the first embodiment. Also, instead of the third blower fan, an opening / closing valve capable of adjusting its opening degree may be provided. This makes it possible to adjust the flow rate of the air flow passing through the internal passage of the branch pipe, as in the first embodiment.

[0073] In this modification, when the drying mechanism is started to perform a drying process on the continuous base material onto which the ink has been ejected, the same procedures as steps S1 to S4 described in the first embodiment are executed, and in step S1, the on-off valves provided in place of the first and third blower fans are opened. The opening degree of the on-off valve provided in place of the first blower fan is then set to be much larger than the opening degree of the on-off valve provided in place of the third blower fan. This allows the high-temperature atmosphere in the first housing to flow further into the second housing 322 through the internal passage of the duct, as in the first embodiment.

[0074] In step S2, it is preferable to gradually decrease the opening of the on-off valve provided in place of the first blower fan to a predetermined opening or less (to an almost closed state), and on the other hand, it is preferable to gradually increase the opening of the on-off valve provided in place of the third blower fan.

[0075] Similarly, in the second embodiment, instead of the fourth blower fan 371B and the sixth blower fan 373B, an opening / closing valve capable of adjusting the opening degree may be provided, which similarly adjusts the flow rate of the air flow passing through the internal passage of the second duct 37B and the branch pipe 39B.

[0076] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate to the extent that no contradiction arises. [Explanation of symbols]

[0077] 1 Inkjet printing device 9 Continuous substrate 10. Conveyor mechanism 20 Printing mechanism 21 Discharge head 30,30B Drying mechanism 31, 31B First heater unit 32,32B Second heater unit 33,33B Duct 35,35B Temperature Sensor 36 Shutter plate 37B 2nd Duct 38 Branch piping 39B Branch piping 90 Control section 311,311B Radiant heat source 312,312B 1st cabinet 313,313B 1st opening 314,314B 1st communication hole 315,315B Outside air intake 316B Hot air inlet 321,321B Hot air source 322,322B 2nd housing 326 2nd communication hole 327B Hot air outlet hole 328,328B 2nd opening 331,331B First blower fan 332,332B Second blower fan 336,336B 3rd blower fan 361 Blackbody 371B No. 4 blower fan 372B No. 5 blower fan 373B No. 6 Blower Fan Pb Branch position (on the duct) Pc (shutter plate) blocking position Pd Branch position (on the second duct) Po (shutter plate) open position

Claims

1. An inkjet printing device that prints by ejecting ink onto a print medium, a transport mechanism that transports the print medium along a predetermined transport path; an ejection head that ejects droplets of the ink onto a surface of the print medium that is being transported by the transport mechanism; a drying mechanism that heats the print medium onto which the ink droplets are ejected, the drying mechanism being located downstream of the ejection head along the transport path; having The drying mechanism includes: a first heater unit including a radiant heat source that radiates radiant heat to the print medium and a first housing that has a first opening through which the radiant heat passes and surrounds the radiant heat source; a second heater unit provided separately from the first heater unit and including a hot air source that generates hot air and a second housing that has a second opening through which the hot air passes and surrounds the hot air source; a duct that connects a first communication hole that communicates an internal space of the first housing with an external space at a position separated from the first opening and a second communication hole that communicates an internal space of the second housing with an external space at a position separated from the second opening, and that connects an atmosphere in the first housing with an atmosphere in the second housing; A temperature sensor that detects the temperature of the hot air generated from the hot air source; a flow rate adjusting unit that adjusts the flow rate of the air flow passing through the internal passage of the duct based on a detection result by the temperature sensor; 1. An inkjet printing apparatus comprising:

2. 2. The inkjet printing apparatus of claim 1, the flow rate adjusting unit is a blower fan provided in the duct and capable of adjusting the rotation speed thereof, An inkjet printing apparatus, wherein an air flow directed from inside the first housing to inside the second housing is generated by the rotation of the blower fan.

3. 2. The inkjet printing apparatus of claim 1, In the inkjet printing apparatus, the flow rate adjusting unit is an opening / closing valve provided in the duct and capable of adjusting an opening degree.

4. 4. The inkjet printing apparatus according to claim 1, The first heater unit includes: a shutter plate capable of opening and closing the first opening from the outside of the first housing; and an ink jet printing apparatus, wherein a blackbody surface is formed on a surface of the shutter plate that faces the radiant heat source when the first opening is closed;

5. 4. The inkjet printing apparatus according to claim 1, The first housing includes: The first communication hole and the first opening are provided apart from each other, and a hot air introduction hole is provided to communicate an internal space of the first housing with an external space. and The drying mechanism includes: a second duct having an upstream end facing the second opening or communicating with the atmosphere in the second housing, and a downstream end communicating with the hot air introduction hole and allowing the hot air to pass through an internal passage thereof; The inkjet printing apparatus further comprising:

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