JP2012131065A - Recording medium conveying apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate drying of a recording medium after liquid drop ejection while suppressing the temperature rise of a drawing drum.SOLUTION: This recording medium conveying apparatus includes a second transfer drum 128 to which a recording medium drawn with the ejection of liquid drops is transferred from the drawing drum 170; a drying unit 210 provided at the second transfer drum 128 and blowing hot air to the recording medium conveyed by the drawing drum 170 to dry it; and a hot air control means for controlling the drying unit 210 so that hot air from the drying unit 210 does not reach the top of the drawing drum 170 when there is no recording medium on the drawing drum 170.

Description

  The present invention relates to a recording medium conveyance device and an image forming apparatus.

  As an image forming apparatus provided with a recording medium conveying apparatus, for example, an image forming apparatus of a liquid discharge recording method using a recording head for discharging ink droplets is known. This liquid discharge recording type image forming apparatus discharges ink droplets from a recording head to a transported recording medium to form an image.

  In such a liquid discharge recording type image forming apparatus, in the process of drying the paper after image formation, it is necessary to stably dry the paper in a short time without deforming the paper.

  It is generally known that the dryness of the paper greatly depends on the basis weight of the paper (eg, 100 to 300 gsm), the amount of ink ejected onto the paper, etc., and is the most severe as expected (hard to dry). The device side has been devised to ensure dryness in cases of drying conditions (assuming the use of cardboard, etc.).

  On the other hand, when thin paper is used as the paper, the dry conditions established based on thick paper that is difficult to dry will cause the paper deformation (cuckling) to increase due to the excessive drying capacity. It is necessary to set conditions for the drying equipment.

  That is, when drying thick paper, a large-capacity heater is required to heat up to the paper temperature required to obtain the required film strength. On the other hand, when thin paper is dried, there is a possibility that deformation of the paper cannot be suppressed because the paper is heated too much in a drying device that supports thick paper.

  Here, it is known that the above-described cuckling phenomenon can be suppressed to some extent if the penetration into the sheet immediately after ejection (image formation) can be suppressed. That is, immediately after ejection, the ink on the surface can be dried in a state where the penetration has not progressed, and therefore, it is easy to suppress cuckling. In addition, since the amount of heat applied can be suppressed, damage to the paper can be reduced.

  Therefore, as disclosed in Patent Document 1 and the like, the applicant of the present invention is an intermediate conveyance between a drawing unit that forms an image and a drying unit that mainly dries after image formation in an image forming apparatus of a liquid discharge recording method. A configuration is proposed in which a drying unit for drying the conveyed paper is provided in the section.

  Further, in Patent Document 2, in an image forming apparatus of a liquid discharge recording method, a heating part of a heating element is moved in synchronization with a moving speed of a sheet conveyed by a conveying belt to heat an ink application part on the sheet. The structure to perform is disclosed.

JP 2010-149417 A JP-A-9-314818

  However, in the configuration of Patent Document 1, since the paper transported by the intermediate transport unit is dried, the paper cannot be dried while being transported from the drawing unit to the intermediate transport unit. There is a possibility that cockle cannot be reliably suppressed. Similarly, in the configuration of Patent Document 2, since the paper conveyed by the conveyance belt is dried, the paper cannot be dried while being conveyed from the drawing unit to the intermediate conveyance unit.

  Therefore, it is necessary to accelerate the drying of the paper after the droplet discharge. However, if the drying is further accelerated, the paper in the drawing cylinder is dried, so that the drawing cylinder is heated at the same time, and various obstacles may occur.

  The present invention has been made in view of the above-described facts, and an object thereof is to provide a recording medium conveying apparatus and an image forming apparatus that accelerate drying of a recording medium after droplet discharge while suppressing an increase in temperature of a drawing cylinder. To do.

  A recording medium conveying apparatus according to a first aspect of the present invention includes a drawing cylinder that rotates and conveys a recording medium on which droplets are ejected and drawn, and a transfer cylinder that delivers the recording medium drawn from the drawing cylinder. And hot air drying means that is provided in the transfer cylinder and blows and blows hot air onto the recording medium conveyed by the drawing cylinder, and when there is no recording medium on the drawing cylinder, hot air from the hot air drying means Hot air control means for controlling the hot air drying means so as not to go onto the drawing cylinder.

  According to this configuration, since the hot air drying means blows the hot air onto the recording medium conveyed by the drawing cylinder and dries it, the drying of the recording medium after droplet discharge can be accelerated. At this time, the drawing cylinder is temporarily warmed, but when there is no recording medium on the drawing cylinder, for example, after the recording medium drawn from the drawing cylinder is transferred to the transfer cylinder, the hot air control means Since the hot air of the hot air drying means is controlled so as not to go onto the drawing cylinder, the temperature rise of the drawing cylinder can be suppressed.

  In the recording medium conveying apparatus according to the second aspect of the present invention, in the first aspect, the transfer drum has an outer peripheral surface opened, and the hot air drying means is disposed inside the transfer drum, and Hot air is blown onto the drawing surface of the recording medium, and the hot air control means rotates the hot air drying means around the rotation axis of the transfer cylinder to change the direction of blowing hot air.

  According to this configuration, when there is no recording medium on the drawing cylinder, the hot air control means rotates the hot air drying means around the rotation axis of the transfer cylinder so that the hot air of the hot air drying means does not go onto the drawing cylinder. The temperature rise of the drawing cylinder can be suppressed without stopping the hot air of the hot air drying means.

  In the recording medium conveying apparatus according to the third aspect of the present invention, in the second aspect, the hot air drying means is a drying unit in which a fan and a heater provided in the blowing direction of the fan are integrated, and the drying The unit is fixed to a shaft that is rotatably mounted around the rotation axis, and the hot air blowing direction is changed by rotating the shaft.

  According to this configuration, since the entire drying unit can be rotated, it is not necessary to individually control the fan, heater, and the like of the drying unit.

  In the recording medium transport apparatus according to a fourth aspect of the present invention, in the third aspect, the shaft is connected to a rotating device outside the transfer cylinder, and the hot air control means is located on the drawing cylinder. When there is no air, the rotating device is controlled to rotate the shaft so that the hot air of the drying unit does not go onto the drawing cylinder.

  According to this configuration, since the drying unit can be rotated by rotating the shaft by controlling the rotating device outside the transfer cylinder, the drying unit can be operated separately from the operation of the transfer cylinder. it can.

  In the recording medium conveying apparatus according to the fifth aspect of the present invention, in the first aspect, the transfer drum has an outer peripheral surface opened, and the hot air drying means is disposed inside the transfer drum, and Hot air is blown onto the drawing surface of the recording medium, and the hot air control means is a shutter that blocks between a heater and a fan constituting the hot air drying means.

  According to this configuration, when there is no recording medium on the drawing cylinder, the heater and the fan can be blocked by the shutter so that the hot air of the hot air drying means does not go onto the drawing cylinder, so the fan is not stopped. However, the temperature rise of the drawing cylinder can be suppressed.

  In the recording medium carrying device according to the sixth aspect of the present invention, in any one of the third to fifth aspects, the hot air control means transfers the recording medium drawn from the drawing cylinder to the transfer cylinder. Thereafter, the hot air drying means is controlled to stop the heater, and the rotation of the fan is stopped at a time interval from the stop of the heater.

  According to this structure, it can suppress that a fan melt | dissolves with the residual heat of a heater.

  A recording medium transport apparatus according to a seventh aspect of the present invention is the recording medium transport apparatus according to any one of the third to sixth aspects, wherein the temperature measuring means is provided on the transfer cylinder and measures the temperature of the recording medium; Temperature control means for performing duty control for controlling the length of on / off time of the heater according to the measurement temperature of the measurement means, and the temperature control means includes a preset target management upper limit temperature and target management lower limit When the measured temperature exceeds the upper limit with respect to the temperature threshold, the time for turning off the heater is increased, and when the measured temperature falls below the lower limit, the time for turning on the heater is increased, Feedback control is performed in which weighting is performed according to the difference between the measured temperature and the target temperature, which is an intermediate value between the target management upper limit temperature and the target management lower limit temperature.

  According to this configuration, excessive drying of the recording medium can be prevented by performing DUTY control of the heater temperature between the target management upper limit temperature and the target management lower limit temperature.

  In a recording medium transport apparatus according to an eighth aspect of the present invention, in the seventh aspect, the temperature control means is configured such that when the recording temperature does not exist on the drawing cylinder and the measured temperature exceeds the target value, The heater is turned off, and when it falls below the lower limit, the heater is turned on.

  According to this configuration, the recording medium can be quickly heated by the next printing while reducing power consumption.

  In the recording medium carrying device according to the ninth aspect of the present invention, in the seventh aspect or the eighth aspect, the temperature control means changes the target value according to the type of the recording medium.

  According to this configuration, optimum drying control can be performed according to the type of recording medium.

  In an image forming apparatus according to a tenth aspect of the present invention, the recording medium conveyance device according to any one of the first aspect to the ninth aspect and a drawing cylinder of the recording medium conveyance device are provided, and the recording medium A droplet discharge head for discharging droplets.

  According to this configuration, it is possible to expedite drying of the recording medium after the droplets are ejected by the droplet ejection head, while suppressing the temperature rise of the drawing cylinder of the recording medium conveying apparatus.

  According to the present invention, it is possible to provide a recording medium conveying apparatus and an image forming apparatus that speed up drying of a recording medium after droplet discharge while suppressing an increase in temperature of the drawing cylinder.

FIG. 1 is a schematic configuration diagram illustrating an overall configuration of an ink jet recording apparatus as an example of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an enlarged view of the recording medium transport apparatus 200 that is a main part of the ink jet recording apparatus according to the first embodiment. FIG. 3A is a perspective view of the second transfer drum. FIG. 3B is a perspective view of the second transfer drum with the drying unit removed. FIG. 4 is a perspective view of the drying unit. FIG. 5 is a partially exploded perspective view of one drying apparatus. FIG. 6 is a cross-sectional view of the second transfer drum including the drying unit. FIG. 7 is a principal block diagram showing the system configuration of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 8 is a diagram for explaining the operation of the ink jet recording apparatus and the recording medium transport apparatus according to the first embodiment of the present invention. FIG. 9 is a diagram illustrating a drying device in the drying unit of the inkjet recording device and the recording medium transport device according to the second embodiment of the present invention. FIG. 10 is a view showing a modification of the ink jet recording apparatus and the recording medium conveying apparatus according to the first embodiment of the present invention, and is a cross-sectional view of a second transfer cylinder including a drying unit. FIG. 11 is an explanatory diagram of DUTY control for the heater of the temperature control means.

(First embodiment)
The image forming apparatus according to the first embodiment of the present invention will be specifically described below with reference to the accompanying drawings. In the drawings, members (components) having the same or corresponding functions are denoted by the same reference numerals and description thereof is omitted as appropriate.

<Overall configuration>
FIG. 1 is a schematic configuration diagram illustrating an overall configuration of an ink jet recording apparatus as an example of an image forming apparatus according to a first embodiment of the present invention.

  The ink jet recording apparatus 100 ejects ink of a plurality of colors from the ink jet heads 172M, 172K, 172C, and 172Y onto the recording surface of the recording medium P held on the pressure drum (drawing drum 170) of the drawing unit 116 to obtain a desired color. An impression cylinder direct drawing type ink jet recording apparatus that forms an image, and a treatment liquid (including an aggregating agent that agglomerates the components in the ink composition) is applied onto the recording medium P before ink ejection, and the treatment liquid Is an on-demand type image forming apparatus to which a two-liquid reaction (aggregation) method in which an ink liquid is reacted to form an image on a recording medium P is applied.

  That is, as shown in FIG. 1, the inkjet recording apparatus 100 mainly includes a paper feeding unit 112, a treatment liquid application unit 114, a drawing unit 116, a drying unit 118, a fixing unit 120, and a paper discharge unit 122. ing.

  The paper feeding unit 112 is a mechanism that supplies the recording medium P to the processing liquid application unit 114, and the recording media P that are sheets are stacked on the paper feeding unit 112. The paper feed unit 112 is provided with a paper feed tray 150, and the recording medium P is fed from the paper feed tray 150 to the processing liquid application unit 114 one by one. In order to prevent the recording medium P from being lifted, the paper feed tray 150 may be provided with a suction hole on the outer surface and connected to a suction unit that performs suction from the suction hole.

  In the inkjet recording apparatus 100 of the first embodiment, as the recording medium P, a plurality of types of recording media P having different paper types and sizes (paper sizes) can be used. A mode is also possible in which a plurality of paper trays (not shown) are provided in the paper feed unit 112 to distinguish and collect various recording media and the paper to be fed to the paper feed tray 150 is automatically switched from among the plurality of paper trays. In addition, a mode is also possible in which the operator selects or replaces the paper tray as necessary. In this example, a sheet (cut paper) is used as the recording medium P. However, a configuration in which a continuous paper (roll paper) is cut to a required size and fed is also possible.

  The processing liquid application unit 114 is a mechanism that applies the processing liquid to the recording surface of the recording medium P. The treatment liquid includes an aggregating agent that agglomerates the components in the ink composition applied by the drawing unit 116, and causes an aggregation reaction with the ink when the treatment liquid comes into contact with the ink. Separation is promoted, and it is possible to form a high-quality image without causing blurring after ink landing, landing interference (unification), or color mixing. In addition, as a process liquid, it can also comprise using another component other than a coagulant | flocculant as needed. By using the treatment liquid together with the ink composition, it is possible to increase the speed of ink jet recording, and an image with excellent density and resolution can be obtained even with high speed recording (for example, reproducibility of fine lines and fine portions).

  Such a processing liquid application unit 114 includes a paper feed cylinder 152, a processing liquid drum 154, and a processing liquid coating device 156. The treatment liquid drum 154 is a drum that holds the recording medium P and rotates and conveys it. The processing liquid drum 154 includes a claw-shaped holding means (gripper) 155 on the outer peripheral surface thereof, and the recording medium P is sandwiched between the claw of the holding means 155 and the peripheral surface of the processing liquid drum 154. The tip can be held. The treatment liquid drum 154 may be provided with a suction hole on the outer peripheral surface thereof and connected to a suction unit that performs suction from the suction hole. As a result, the recording medium P can be held in close contact with the peripheral surface of the treatment liquid drum 154.

  A processing liquid coating device 156 is provided outside the processing liquid drum 154 so as to face the peripheral surface thereof. In the recording medium P, the processing liquid is applied to the recording surface by the processing liquid application device 156.

  The recording medium P to which the processing liquid is applied by the processing liquid applying unit 114 is transferred from the processing liquid drum 154 to the drawing drum 170 of the drawing unit 116 via the intermediate transport unit 126 (first transfer cylinder).

  The drawing unit 116 includes a drawing drum 170 and inkjet heads 172M, 172K, 172C, and 172Y. Although not shown in FIG. 1, a sheet pressing roller for removing the wrinkles of the recording medium P is disposed on the front side of the ink jet heads 172M, 172K, 172C, and 172Y with respect to the drawing drum 170. Also good.

  Similar to the treatment liquid drum 154, the drawing drum 170 includes a claw-shaped holding means (gripper) 171 on its outer peripheral surface, and holds and fixes the leading end of the recording medium. The drawing drum 170 has a plurality of suction holes on the outer peripheral surface, and the recording medium P is attracted to the outer peripheral surface of the drawing drum 170 by negative pressure. As a result, contact with the head due to paper floating is avoided, and paper jam is prevented. In addition, image unevenness due to fluctuations in the clearance with the head is prevented.

  The recording medium P fixed to the drawing drum 170 in this way is conveyed with the recording surface facing outward, and ink is ejected onto the recording surface from the ink jet heads 172M, 172K, 172C, 172Y.

  The inkjet heads 172M, 172K, 172C, and 172Y are full-line inkjet recording heads (inkjet heads) each having a length corresponding to the maximum width of the image forming area on the recording medium P. Is formed with a nozzle row in which a plurality of nozzles for ink ejection are arranged over the entire width of the image forming area. Each inkjet head 172M, 172K, 172C, 172Y is installed so as to extend in a direction orthogonal to the conveyance direction of the recording medium P (the rotation direction of the drawing drum 170).

  The droplets of the corresponding color ink are ejected from the respective ink jet heads 172M, 172K, 172C, 172Y toward the recording surface of the recording medium P held tightly on the drawing drum 170, whereby the processing liquid application unit 114 The ink comes into contact with the treatment liquid previously applied to the recording surface, and the color material (pigment) dispersed in the ink is aggregated to form a color material aggregate. As a result, the color material flow on the recording medium P is prevented, and an image is formed on the recording surface of the recording medium P.

  The drawing unit 116 configured as described above can perform drawing on the recording medium P in a single pass. Thereby, high-speed recording and high-speed output are possible, and productivity can be improved.

  The recording medium P on which an image is formed by the drawing unit 116 is transferred from the drawing drum 170 to the drying drum 176 of the drying unit 118 via the intermediate conveyance unit 128 (second transfer cylinder).

  The drying unit 118 is a mechanism for drying moisture contained in the solvent separated by the color material aggregating action, and includes a drying drum 176 and a solvent drying device 178, as shown in FIG.

Similar to the treatment liquid drum 154, the drying drum 176 includes a claw-shaped holding unit (gripper) 177 on the outer peripheral surface thereof, holds the tip of the recording medium P by the holding unit 177, and suction holes on the outer peripheral surface of the drum. (Not shown), and the recording medium P can be adsorbed to the drying drum 176 by negative pressure.
The solvent drying device 178 is arranged at a position facing the outer peripheral surface of the drying drum 176, and has a configuration in which a plurality of combinations of the IR heater 180 and the hot air nozzle 182 are arranged. Various drying conditions can be realized by appropriately adjusting the temperature and the amount of hot air blown from the hot air nozzle 182 toward the recording medium P. The recording medium P is conveyed while being attracted and restrained to the outer peripheral surface of the drying drum 176 so that the recording surface faces outward, and the recording surface is dried by the IR heater 180 and the hot air nozzle 182.

  Further, the drying drum 176 has suction holes on the outer peripheral surface thereof, and has suction means for performing suction from the suction holes. As a result, the recording medium P can be held in close contact with the peripheral surface of the drying drum 176. Moreover, since the recording medium P can be restrained by the drying drum 176 by performing negative pressure suction, the recording medium P can be prevented from being clogged.

  The recording medium P that has been dried by the drying unit 118 is transferred from the drying drum 176 to the fixing drum 184 of the fixing unit 120 via the intermediate conveyance unit 130 (third transfer cylinder).

  The fixing unit 120 includes a fixing drum 184, a pressing roller 188 (smoothing means), and an inline sensor 190. Like the processing liquid drum 154, the fixing drum 184 includes a claw-shaped holding unit (gripper) 185 on the outer peripheral surface, and the leading end of the recording medium P can be held by the holding unit 185.

  As the fixing drum 184 rotates, the recording medium P is conveyed with the recording surface facing outward, and the recording surface is smoothed by the pressing roller 188 to fix the ink.

  The pressure roller 188 smoothes the recording medium P by pressurizing the recording medium P from which the ink has been dried. The inline sensor 190 measures a check pattern, moisture content, surface temperature, glossiness, etc. on the recording medium P, and for example, a CCD line sensor can be suitably used.

  Subsequent to the fixing unit 120, a paper discharge unit 122 is provided. A paper discharge unit 192 is installed in the paper discharge unit 122. A fourth transfer drum 194 and a transport chain 196 are provided between the fixing drum 184 and the paper discharge unit 192 of the fixing unit 120. The conveyance chain 196 is wound around the tension roller 198. The recording medium P that has passed through the fixing drum 184 is sent to the transport chain 196 via the fourth transfer drum 194 and is transferred from the transport chain 196 to the paper discharge unit 192.

  Although not shown in FIG. 1, the ink jet recording apparatus 100 of the present example has an ink storage / loading unit that supplies ink to each of the ink jet heads 172M, 172K, 172C, and 172Y, and a treatment liquid application, in addition to the above configuration. A head maintenance unit for supplying a processing liquid to the unit 114 and cleaning the ink jet heads 172M, 172K, 172C, 172Y (wiping, purging, nozzle suction, etc. of the nozzle surface) A position detection sensor for detecting the position of the recording medium P, a temperature sensor for detecting the temperature of each part of the apparatus, and the like are provided.

  Of the configuration of the ink jet recording apparatus 100 described above, the processing liquid drum 154, the drawing drum 170, the drying drum 176, the fixing drum 184, and the intermediate conveyance units 126, 128, 130 between them, etc. This constitutes the recording medium transport apparatus 200 according to the first embodiment of the present invention.

<Details of intermediate transport section (transfer drum)>
FIG. 2 shows an enlarged view of the recording medium transport apparatus 200 that is the main part of the ink jet recording apparatus 100 of the first embodiment, and more particularly the transfer cylinder of the recording medium transport apparatus 200 according to the first embodiment. To do.

  As shown in FIG. 2, in the recording medium conveyance device 200, the processing liquid drum 154, the intermediate conveyance unit 126 (first transfer cylinder), the drawing drum 170, the intermediate conveyance unit 128 (second transfer cylinder), the drying drum 176, the intermediate A transport unit 130 (third transfer cylinder) and a fixing drum 184 are arranged side by side, and the recording medium P is transported by each drum, and processing liquid application, drawing, drying, and fixing (curing) are sequentially performed while being transported. To be done.

  Each transfer drum 126, 128, and 130 includes rib-attached guide members 127, 129, and 131, respectively, and holding claws 133, 135, and 137 at the end portions of the arms that extend in directions opposite to each other by 180 degrees across the rotation shaft. The recording medium P is rotated around the rotation axis by gripping the leading end of the recording medium P, and the recording medium P is moved along the guide members (127, 129, 131) while the rear end of the recording medium P is free. It is configured to carry the sheet so that the back side is convex.

  Each transfer drum 126, 128, and 130 may be configured to use a chain gripper to grip the recording medium P and convey it with the back side convex.

  Next, of the transfer cylinders 126, 128, and 130, the second transfer cylinder 128 will be described in detail, but the other transfer cylinders 126 and 130 have the same configuration.

  FIG. 3A is a perspective view of the second transfer drum 128.

  The second transfer drum 128 includes a transfer drum frame 204 in which a rotation shaft, which will be described later, is rotatably connected to the main body frame 202 of the ink jet recording apparatus 100, and a rotation gear 206 fixed to the tip of the rotation shaft. Yes. The transfer drum frame 204 is rotatable by the rotation of the rotation gear 206 with the main body frame 202 sandwiched between the frame and the rotation gear 206. The transfer drum frame 204 is open on the outer peripheral surface, has a drying unit 210 as hot air drying means inside (near the rotating shaft), and is on the recording surface (front surface) side of the recording medium P facing inward during conveyance. Blow hot air on to dry.

  FIG. 3B is a perspective view of the second transfer drum 128 with the drying unit 210 removed.

  The drying unit 210 has a shaft which will be described later, and the shaft is inserted into a shaft hole 212 provided in the transfer drum frame 204 and attached to the transfer drum frame 204.

  FIG. 4 is a perspective view of the drying unit 210.

The drying unit 210 is configured by incorporating two drying devices 222 and 224 in a unit frame 220.

One drying device 222 is provided on the drawing drum 170 side and blows hot air HW from the nozzle port 226 to the recording medium P conveyed by the drawing drum 170 to dry it. The other drying device 224 is provided on the drying drum 176 side, and blows hot air HW from the nozzle port 228 to the recording medium P conveyed by the second transfer drum 128 to dry it.

  FIG. 5 is a partially exploded perspective view of one drying device 222. The other drying device 224 has the same configuration as below.

  The drying device 222 includes a temperature sensor 230, a resistance wire heater 232, a shielding plate 234, and an axial fan 236 in order from the nozzle port 226 side.

The temperature sensor 230 measures the temperature of the hot air HW blown out from the nozzle port 226. The resistance wire heater 232 generates heat and generates hot air HW when heat is generated and the wind of the axial fan 236 hits it. The shielding plate 234 is partially open, and the resistance wire is used so that the heat of the resistance wire heater 232 does not reach the axial flow fan 236 while allowing the wind of the axial flow fan 236 to strike the resistance wire heater 232 from the opening. A portion between the heater 232 and the axial fan 236 is shielded. The axial fan 236 has a resin propeller, and generates wind by the propeller.

  FIG. 6 is a sectional view of the second transfer drum 128 including the drying unit 210.

  The drying unit 210 has a shaft 240 that is attached to the unit frame 220 so as to be rotatable about a rotation shaft 250 of the transfer drum frame 204. The shaft 240 is inserted into the shaft hole 212 as described above, and the drying unit 210 is attached to the transfer drum frame 204. The distal end of the shaft 240 protrudes from the shaft hole 212 toward the outside of the rotation gear 206 that rotates the transfer drum frame 204, and is sandwiched between the flange members 242. One end of the flange member 242 is connected to a solenoid 244 serving as a rotation device, and can move up and down.

  The shaft 240 is rotated by the vertical movement of one end of the flange member 242 and the drying unit 210 is rotated. However, a clutch 246 is connected to the flange member 242 so that this rotation does not go too far.

  The rotating shaft 250 of the transfer drum frame 204 is inserted into a bearing 252 provided on the main body frame 202 and is connected to the rotary gear 206 outside the main body frame 202. Further, the shaft hole 212 described above is provided in the rotating shaft 250. Here, the transfer drum frame 204 is rotated by the rotating gear 206 via the rotating shaft 250, and the drying unit 210 is rotated by the flange member 242 and the solenoid 244 via the shaft 240. The drying unit 210 can be operated separately from the operation 204.

<Description of control system>
FIG. 7 is a principal block diagram showing the system configuration of the inkjet recording apparatus 100 according to the first embodiment of the present invention.

  The inkjet recording apparatus 100 includes a communication interface 300, a system controller 302, a program storage unit 303, a memory 304, a sensor 305, a motor driver 306, a print control unit 308, an image buffer memory 310, a head driver 312 and the like.

  The communication interface 300 is an interface unit that receives image data sent from the host computer 314. As the communication interface 300, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 314 is taken into the inkjet recording apparatus 100 via the communication interface 300 and temporarily stored in the memory 304.

  The memory 304 is a storage unit that temporarily stores an image input via the communication interface 300, and data is read and written through the system controller 302. The memory 304 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 302 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 100 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 302 controls each unit such as the communication interface 300, the program storage unit 303, the memory 304, the motor driver 306, the hot air control unit 320, the processing liquid application control unit 322, the drying control unit 324, and the fixing control unit 326. In addition to performing communication control with the host computer 314, read / write control of the memory 304, etc., control signals for controlling the above-described units are generated.

  The memory 304 stores programs executed by the CPU of the system controller 302 and various data necessary for control. Note that the memory 304 may be a non-rewritable storage unit or a rewritable storage unit such as an EEPROM. The memory 304 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  Various control programs are stored in the program storage unit 303, and the control programs are read out and executed in accordance with instructions from the system controller 302. The program storage unit 303 may use a semiconductor memory such as a ROM or an EEPROM, or may use a magnetic disk or the like. An external interface may be provided and a memory card or PC card may be used. Of course, you may provide several recording media among these recording media. The program storage unit 303 may also be used as a recording unit (not shown) for operating parameters.

  The motor driver 306 is a driver that drives the motor 307 in accordance with an instruction from the system controller 302. In FIG. 7, the motors arranged in the respective units in the apparatus are represented by reference numeral 307. For example, the motor 307 illustrated in FIG. 7 includes the processing liquid drum 154 illustrated in FIG. 1, the intermediate conveyance unit 126 (first transfer cylinder), the drawing drum 170, the intermediate conveyance unit 128 (second transfer cylinder), the drying drum 176, A motor that drives the rotation of the intermediate conveyance unit 130 (third transfer cylinder), the fixing drum 184, and the like is included.

  The print control unit 308 has a signal processing function for performing various processing and correction processing for generating a print control signal from the image data in the memory 304 in accordance with the control of the system controller 302. The generated print data This is a control unit that supplies (dot data) to the head driver 312. Necessary signal processing is performed in the print control unit 308, and the ejection droplet amount (droplet ejection amount) and ejection timing of the inkjet head 172 are controlled via the head driver 312 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print controller 308 includes an image buffer memory 310, and image data, parameters, and other data are temporarily stored in the image buffer memory 310 when image data is processed in the print controller 308. Also possible is an aspect in which the print controller 308 and the system controller 302 are integrated and configured with one processor.

  The head driver 312 generates a driving signal to be applied to the piezoelectric element of the inkjet head 172 based on the image data given from the print control unit 308, and drives the piezoelectric element by applying the driving signal to the piezoelectric element. It is configured including a circuit. Note that the head driver 312 shown in FIG. 7 may include a feedback control system for keeping the driving conditions of the inkjet head 172 constant.

  The sensor 305 is various sensors provided in each part in the apparatus, and includes a position detection sensor, a pressure sensor, and the like in addition to the inline sensor 190 shown in FIG. 1 and the temperature sensor 230 shown in FIG. The output signal of the sensor 305 is sent to the system controller 302, and the system controller 302 sends a control signal to each part of the apparatus based on the output signal, thereby controlling each part of the apparatus.

  Further, the ink jet recording apparatus 100 includes a hot air control unit 320, a processing liquid application control unit 322, a drying control unit 324, and a fixing control unit 326, and in accordance with instructions from the system controller 302, the drying unit 210 is provided. The operation of each part of the treatment liquid coating device 156, the solvent drying device 178, and the pressure roller 188 is controlled.

<Action>
Next, the operation of the inkjet recording apparatus 100 and the recording medium transport apparatus 200 according to the first embodiment of the present invention will be described.
FIG. 8 is a diagram for explaining the operation of the inkjet recording apparatus 100 and the recording medium transport apparatus 200 according to the first embodiment of the present invention.

  As shown in FIGS. 8A and 8B, the hot air control unit 320 of the inkjet recording apparatus 100 (the recording medium transport apparatus 200), when the print job is started, each drying apparatus 222 of the drying unit 210 (the drying unit 222). , 224) to turn on the heaters 232 and the fans 236 to blow out the hot air HW from the nozzle ports 226 and 228, respectively. Then, the hot air control unit 320 controls the solenoid 244 to rotate the shaft 240. As a result, the drying unit 210 is rotated around the rotation shaft 250 of the second transfer drum 128 to change the blowing direction of the hot air HW, and the hot air is blown onto the recording medium P conveyed by the drawing drum 170 to be dried. The degree of rotation may be rotated so that the nozzle port 226 of the drying device 222 faces the drawing drum 170. For example, when the nozzle port 226 faces downward, the rotation is 90 degrees. From the viewpoint of expediting drying of the recording medium P after droplet ejection (image formation), it is preferable that the ink jet head 172 side is more than 90 degrees as shown in FIG. 8B.

  Next, as shown in FIGS. 8B and 8C, when the recording medium P does not exist on the drawing drum 170, the hot air control unit 320 uses the second recording medium P drawn from the drawing drum 170, for example. After being transferred to the transfer drum 128 or after the conveyance of one recording medium P is finished, the shaft 240 is rotated by controlling the solenoid 244. As a result, the drying unit 210 is rotated around the rotation shaft 250 of the second transfer drum 128 to change the blowing direction of the hot air HW so that the hot air HW of the drying unit 210 does not go onto the drawing drum 170. The degree of rotation may be rotated so that the nozzle port 226 of the drying device 222 does not face the drawing drum 170. For example, when the nozzle port 226 faces downward, the rotation is 45 degrees. From the viewpoint of preventing the hot air HW from being applied to the drawing drum 170, the angle is preferably less than 45 degrees. If the arrangement of the drying device 224 is not taken into consideration, the rotation angle is preferably 0 degrees or a negative rotation angle.

  As described above, according to the ink jet recording apparatus 100 and the recording medium transport apparatus 200 according to the first embodiment of the present invention, the drying unit 210 as hot air drying means sprays the hot air HW onto the recording medium P transported by the drawing drum 170. Therefore, drying of the recording medium P after discharging the droplets can be accelerated compared to the conventional method. At this time, the drawing drum 170 is temporarily warmed. However, when there is no recording medium P on the drawing drum 170, for example, after the recording medium P drawn from the drawing drum 170 is transferred to the transfer cylinder. Since the hot air control unit 320 controls the hot air HW of the drying unit 210 so as not to go onto the drawing drum 170, the temperature rise of the drawing drum 170 can be suppressed. At this time, since the drying unit 210 is controlled to rotate around the rotation shaft 250, the temperature rise of the drawing drum 170 can be suppressed without stopping the hot air HW of the drying unit 210.

  If the heater 232 and the fan 236 are stopped immediately after the recording medium P is transported onto the drawing drum 170, the temperature of the drawing drum 170 can be suppressed, but the fan 236 may be melted by the residual heat of the heater 232. There is. Therefore, for safety, after the recording medium P drawn from the drawing drum 170 is transferred to the second transfer drum 128, the drying unit 210 is controlled to stop the heater 232, and from the stop of the heater 232 The rotation of the fan 236 is stopped after a time interval (for example, about 10 minutes).

(Second Embodiment)
Next, an ink jet recording apparatus and a recording medium transport apparatus according to a second embodiment of the present invention will be described. FIG. 9 is a diagram illustrating a drying device in the drying unit of the inkjet recording device and the recording medium transport device according to the second embodiment of the present invention.

  The ink jet recording apparatus and the recording medium transport apparatus according to the second embodiment of the present invention have the same configuration as that of the first embodiment, but unlike the first embodiment, the drying unit does not rotate.

  Instead, the drying device 400 on the drawing drum 170 side of the drying unit is provided with a long plate-like shutter 402 that blocks between the fan 236 and the heater 232. The shutter 402 is connected to a solenoid (not shown) or the like and is slidable from the outside of the drying device 400 between the fan 236 and the heater 232.

  The drying unit according to the second embodiment is always in the state shown in FIG. 8B and is dried by blowing hot air onto the recording medium P conveyed by the drawing drum 170. Then, the hot air control unit 320, when the recording medium P is not on the drawing drum 170, for example, after the recording medium P drawn from the drawing drum 170 is transferred to the second transfer cylinder 128, or one recording medium After the transport of P is completed, the solenoid 402 is controlled to slide the shutter 402 between the fan 236 and the heater 232. As a result, the wind of the fan 236 is blocked from the heater 232 and the nozzle port 226 side so that the hot air HW of the drying unit does not flow onto the drawing drum 170.

  As described above, according to the ink jet recording apparatus and the recording medium transport apparatus according to the second embodiment of the present invention, when there is no recording medium P on the drawing drum 170, the hot air HW of the drying device 400 of the drying unit moves onto the drawing drum 170. Since the shutter 402 can block between the heater 232 and the fan 236 so as not to go, the temperature rise of the drawing drum 170 can be suppressed without stopping the fan 236.

(Modification)
Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art, and for example, the plurality of embodiments described above can be implemented in combination as appropriate. Moreover, you may combine the following modifications suitably.

  For example, in the first embodiment, the case where the solenoid 244 is used as the rotating device of the drying unit 210 has been described, but a motor 500 may be used as shown in FIG.

  Further, the system controller 302 shown in FIG. 7 is provided with temperature control means for performing duty control for controlling the length of the on / off time of the heater 232 in accordance with the temperature measured by the temperature sensor 230 (surface temperature of the recording medium P). You may do it. This temperature control means finely controls the capability by finely turning on / off the heater 232 in consideration of conditional factors such as the paper type of the recording medium P and the temperature and humidity in the apparatus.

  FIG. 11 is an explanatory diagram of DUTY control for the heater 232 of the temperature control means. That is, as shown in FIGS. 11A and 11B, when the measured temperature of the temperature sensor 230 exceeds the upper limit with respect to the preset target management upper limit temperature and target management lower limit temperature for the recording medium P, as shown in FIGS. The time for turning off the heater 232 is increased, and when the temperature falls below the lower limit, the drive time is controlled so as to increase the time for turning on the heater 232, thereby controlling the temperature difference Δt, and the target management upper limit temperature and target management. The surface temperature of the recording medium P is kept between the lower limit temperatures.

  At this time, feedback control may be performed in which weighting is performed according to the difference between the measured surface temperature of the recording medium P and the sheet target temperature that is an intermediate value between the target management upper limit temperature and the target management lower limit temperature. .

  For example, there may be a case where the temperature of the target recording medium P (or the drawing drum 170) does not reach or overheats due to a change in temperature and humidity in the apparatus even when the same amount of heat is applied. Therefore, PI control that controls the amount of heat applied by integrating the deviation (residual deviation) between the target temperature and the measured temperature in the time axis direction, or PID control that takes into account the rate of change obtained by differentiating the change in measured temperature with time, etc. It may be used. Specifically, it is effective for situations such as overshooting when the target temperature is exceeded or not being maintained even when the target temperature is reached.

  As described above, in the present invention, the heater 232 is DUTY controlled (duty correction ratio is determined) while measuring the surface temperature of the recording medium P. Further, the DUTY target value (target temperature) is determined (changed) in accordance with the basis weight of the recording medium P, the paper type, the environment such as temperature and humidity, the droplet ejection amount, and the like.

  Thus, while using the drying unit 210 having a drying capacity sufficient to dry the thick recording medium P, there is no excessive drying even when the thin recording medium P is dried. The drying capacity of the drying unit 210 can be adjusted to an optimum state in accordance with (basis weight of the recording medium P, paper type, environment such as temperature and humidity, droplet ejection amount, etc.).

  The temperature control means turns off the heater 232 when the temperature measured by the temperature sensor 230 exceeds the target value when there is no recording medium P on the drawing drum 170, and when the temperature falls below the lower limit. The heater 232 may be turned on. As a result, the recording medium P can be quickly heated by the next printing while reducing power consumption.

  In the above embodiment, an ink jet type image recording apparatus using water-based ink using water as a solvent has been described as an example. However, the liquid to be ejected is not limited to ink for image recording / character printing, etc. Any liquid that uses a solvent or a dispersion medium soaking into the medium can be applied to various discharge liquids.

  In the above embodiment, the configuration of CMYK standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not particularly limited, and light ink, dark ink, and special color ink are added as necessary. May be. For example, it is possible to add an ink jet head that discharges light ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

  Further, the treatment liquid application step may be provided either before or after the ink application step using the ink composition. However, in the present embodiment, an aspect in which the ink application process is provided after the treatment liquid is applied in the treatment liquid application process is preferable.

  Further, although the case where the drying unit 210 is built in the second transfer drum 128 has been described, the drying unit 210 may be provided above or below the second transfer drum 128.

100 Inkjet recording device 128 Intermediate transport section, second transfer cylinder (transfer cylinder)
170 Drawing drum (drawing cylinder)
172 Inkjet head (droplet ejection head)
200 Recording medium transport device 210 Drying unit (hot air drying means)
222 Drying equipment (hot air drying means)
230 Temperature sensor (temperature measurement means)
232 Resistance wire heater 236 Axial fan 240 Shaft 242 Scissors member (rotating device)
244 Solenoid (rotating device)
246 Clutch (rotating device)
250 Rotating shaft 305 Sensor (temperature measuring means)
320 Hot air control unit (hot air control means)
400 Drying device (hot air drying means)
402 Shutter 500 Motor (rotating device)
HW Hot air P Recording medium

Claims (10)

A drawing cylinder for rotating and conveying a recording medium on which droplets are discharged and drawn;
A transfer cylinder to which the recording medium drawn from the drawing cylinder is transferred;
Hot air drying means provided on the transfer cylinder and sprayed with hot air on the recording medium conveyed by the drawing cylinder; and
Hot air control means for controlling the hot air drying means so that hot air of the hot air drying means does not go onto the drawing cylinder when the recording medium is not on the drawing cylinder;
A recording medium conveying apparatus comprising: The transfer drum has an open outer peripheral surface,
The hot air drying means is disposed inside the transfer drum, and blows hot air from the opening to the drawing surface of the recording medium,
The hot air control means rotates the hot air drying means around the rotation axis of the transfer drum to change the direction of hot air blowing.
The recording medium carrying device according to claim 1. The hot air drying means is a drying unit in which a fan and a heater provided in the blowing direction of the fan are integrated.
The drying unit is fixed to a shaft rotatably attached around the rotation axis, and changes the direction of blowing hot air by rotating the shaft.
The recording medium carrying device according to claim 2. The shaft is connected to a rotation device outside the transfer drum,
The hot air control means controls the rotating device to rotate the shaft when there is no recording medium on the drawing cylinder, so that the hot air of the drying unit does not go onto the drawing cylinder.
The recording medium carrying device according to claim 3. The transfer drum has an open outer peripheral surface,
The hot air drying means is disposed inside the transfer drum, and blows hot air from the opening to the drawing surface of the recording medium,
The hot air control means is a shutter that blocks between a heater and a fan constituting the hot air drying means.
The recording medium carrying device according to claim 1. The hot air control means controls the hot air drying means to stop the heater after the recording medium drawn from the drawing cylinder is transferred to the transfer cylinder, and keeps a time interval from the stop of the heater. And stop the rotation of the fan,
The recording medium carrying device according to any one of claims 3 to 5. A temperature measuring means provided on the transfer cylinder for measuring the temperature of the recording medium;
Temperature control means for performing duty control for controlling the length of on / off time of the heater according to the measurement temperature of the temperature measurement means;
With
The temperature control means includes
When the measured temperature exceeds the upper limit with respect to the preset thresholds for the target management upper limit temperature and the target management lower limit temperature, the time for turning off the heater is increased, and when the measured temperature falls below the lower limit. Increases the time to turn on the heater, and performs feedback control in which the measured temperature is weighted according to the difference between the target temperature that is an intermediate value between the target management upper limit temperature and the target management lower limit temperature,
The recording medium carrying device according to any one of claims 3 to 6. The temperature control means turns off the heater if the measured temperature exceeds the target value when the recording medium is not on the drawing cylinder, and turns on the heater if the temperature falls below the lower limit. ,
The recording medium carrying device according to claim 7. The temperature control means changes the target value depending on the type of the recording medium.
The recording medium carrying device according to claim 7 or 8. The recording medium carrying device according to any one of claims 1 to 9,
A droplet discharge head that is provided on a drawing cylinder of the recording medium conveying device and that discharges droplets to the recording medium;
An image forming apparatus comprising:

Images