Ink jet recording device

Abstract

To provide a configuration equipped with a pressure detection part for detecting the pressure inside a duct and capable of notifying that jamming has occurred in a belt hole at an appropriate timing.SOLUTION: A suction duct 3362 sucks air from a plurality of holes of a drying belt 9 and sucks a sheet on a conveyance surface 9a when inside air is sucked by a suction fan 3366. A pressure sensor 3368 detects the pressure inside the suction duct 3362. A control part controls the suction fan 3366 so that the number of rotations of the suction fan 3366 becomes a setting number of rotations. The control part notifies an abnormality when the number of times that an absolute value of the pressure detected by the pressure sensor 3368 for a second predetermined time exceeds a predetermined pressure value becomes a first number of times after an elapse of a first predetermined time from the start of the drive of the suction fan 3366.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus that forms an image on a sheet with ink and transports the sheet on which the image has been formed. [Background technology]

[0002] In a conventional inkjet recording device that ejects ink from an ink head to form an image on a sheet, a configuration has been proposed in which a suction fan is disposed inside a belt, and the suction fan attracts the sheet to the belt and transports it (Patent Document 1). Patent Document 1 describes a configuration in which the duty ratio of the power supplied to the suction fan motor is controlled according to the rotation speed of the motor to prevent a decrease in the suction fan's sheet attracting force due to filter clogging. Patent Document 1 also describes displaying the state of filter clogging according to the duty ratio of the power supplied to the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-30564 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, it is desirable to precisely control the suction force for adhering the sheet to the belt depending on the type of sheet, such as its size and basis weight. To achieve this, it is desirable to use a pressure sensor (pressure detection unit) to detect the pressure inside the duct through which the air inside is sucked by the suction fan. Meanwhile, the belt that adsorbs and transports the sheet has multiple holes formed therein for sucking air. The multiple holes in the belt may become clogged with paper dust or ink, and in this case, there is a risk that sufficient suction force for adhering the sheet to the belt may not be obtained. For this reason, it is desirable to determine and notify the user of such clogging of the multiple holes.

[0005] In a configuration that displays the clogged filter status according to the duty ratio of the power supplied to the motor, as described in Patent Document 1, if the suction space is large or the inertia of the fan or motor is high, the rotation speed of the suction fan motor is unlikely to change in response to the clogged filter status, i.e., the responsiveness is poor. Therefore, when attempting to determine the clogged belt hole status according to the duty ratio of the power supplied to the motor as in Patent Document 1, it may be difficult to determine the clogged belt hole status in a partial manner. Furthermore, the clogged belt hole status may not be notified in a timely manner, which may result in a decrease in the quality of the finished product.

[0006] The present invention aims to provide a configuration that includes a pressure detection unit that detects the pressure inside a duct and that can notify at an appropriate time that a blockage has occurred in a belt hole. [Means for solving the problem]

[0007] One aspect of the present invention is an inkjet recording device comprising an image forming unit that ejects ink to form an image on a sheet, and a sheet conveying device that conveys the sheet on which the image has been formed by the image forming unit, wherein the sheet conveying device comprises an endless belt having a plurality of holes formed therein, a plurality of tension members that tension the belt and form a conveying surface on the outer surface of the belt for conveying the sheet, a suction fan that sucks air, a duct that sucks air through the plurality of holes in the belt by the suction fan sucking in the air inside, thereby adsorbing the sheet to the conveying surface, a pressure detection unit that detects the pressure inside the duct, and a control unit that controls the suction fan so that the rotation speed of the suction fan becomes a set rotation speed, and wherein the control unit notifies of an abnormality when the number of times that the absolute value of the pressure detected by the pressure detection unit exceeds a predetermined pressure value during a second predetermined time period reaches a first predetermined number after a first predetermined time has elapsed since the suction fan started to be driven.

[0008] One aspect of the present invention is an inkjet recording apparatus comprising: an image forming unit that ejects ink to form an image on a sheet; and a sheet transporting device that transports the sheet on which the image has been formed by the image forming unit. The sheet transporting device comprises an endless belt having a plurality of holes formed therein; a plurality of tension members that tension the belt and form a transport surface on the outer surface of the belt for transporting the sheet; a suction fan that sucks air; a duct that sucks air through the plurality of holes in the belt by the suction fan, thereby adsorbing the sheet to the transport surface; a pressure detection unit that detects the pressure inside the duct; a rotation detection unit that detects the rotation speed of the suction fan; and a control unit that controls the rotation speed of the suction fan so that the pressure detected by the pressure detection unit becomes a set pressure. The control unit is characterized in that, after a first predetermined time has elapsed since the suction fan started to be driven, the number of times the rotation speed of the suction fan detected by the rotation detection unit falls below the predetermined rotation speed during a second predetermined time period reaches a first number. [Effects of the Invention]

[0009] According to the present invention, a configuration including a pressure detector that detects the pressure inside the duct makes it possible to notify at an appropriate time that a clog has occurred in a hole in the belt. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an inkjet recording apparatus according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the schematic configuration of a print module, a drying module, and a fixing module according to the first embodiment. [Figure 3] FIG. 2 is a cross-sectional view showing the schematic configuration of a drying belt unit according to the first embodiment. [Figure 4] FIG. 2 is a control block diagram relating to a drying belt unit according to the first embodiment. [Figure 5] 5 is a flowchart of control regarding the drying belt unit according to the first embodiment. [Figure 6](a) Graph showing the change in pressure when a blockage occurs, (b) Graph showing the change in pressure when a break occurs. [Figure 7] 10 is a flowchart of control regarding a drying belt unit according to a second embodiment. [Figure 8] (a) Graph showing the change in rotation speed when a blockage occurs, (b) Graph showing the change in rotation speed when a break occurs. DETAILED DESCRIPTION OF THE INVENTION

[0011] First Embodiment The first embodiment will be described with reference to Figures 1 to 6(b) First, the schematic configuration of an image forming system of this embodiment will be described with reference to Figure 1. [Inkjet recording device] The inkjet recording apparatus 100 as the image forming system of this embodiment uses an inkjet recording method in which ink is ejected to form an image on a sheet, and is a so-called sheet-fed inkjet recording apparatus that forms an ink image on a sheet using two liquids: a reaction liquid and ink. The sheet may be any recording material that can accept ink, such as paper such as plain paper or cardboard, plastic film such as an overhead projector sheet, specially shaped sheets such as envelopes or index paper, or cloth.

[0012] 1, the inkjet recording apparatus 100 of this embodiment includes a feeding module 1000, a printing module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inverting module 6000, and a stacking module 7000. The sheet S supplied from the feeding module 1000 undergoes various processes as it is transported along the transport path within each module, and is finally discharged to the stacking module 7000.

[0013] The feeding module 1000, printing module 2000, drying module 3000, fixing module 4000, cooling module 5000, reversing module 6000, and stacking module 7000 may each have separate housings, and these housings may be connected to form the inkjet recording apparatus 100. Alternatively, the feeding module 1000, printing module 2000, drying module 3000, fixing module 4000, cooling module 5000, reversing module 6000, and stacking module 7000 may be arranged in a single housing.

[0014] The feeding module 1000 has storage cabinets 1500a, 1500b, and 1500c for storing sheets S, and the storage cabinets 1500a to 1500c are provided so as to be able to be pulled out toward the front side of the apparatus to store the sheets S. The sheets S are fed one by one in each of the storage cabinets 1500a to 1500c by a separation belt and a transport roller, and are transported to the print module 2000. The number of storage cabinets 1500a to 1500c is not limited to three, and there may be one, two, four or more.

[0015] The print module 2000 includes a pre-imaging registration correction unit (not shown), a print belt unit 2010, and a recording unit 2020 as an image forming unit. The sheet S conveyed from the feeding module 1000 has its tilt and position corrected by the pre-imaging registration correction unit before being conveyed to the print belt unit 2010. The recording unit 2020 is positioned opposite the print belt unit 2010 with respect to the conveyance path. The recording unit 2020 is an inkjet recording unit that forms an image by ejecting ink onto the conveyed sheet S from above using a recording head. Multiple recording heads that eject ink are arranged along the conveyance direction. In this embodiment, the sheet S has a total of five line-type recording heads corresponding to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black), as well as reaction liquids. The sheet S is adsorbed and conveyed by the print belt unit 2010, ensuring clearance between the sheet S and the recording heads.

[0016] The number of ink colors and recording heads is not limited to the five mentioned above. The inkjet method can be a method using a heating element, a piezoelectric element, an electrostatic element, or a MEMS (Micro Electro Mechanical Systems) element. Each color of ink is supplied to the recording head from an ink tank (not shown) via an ink tube. The ink contains 0.1% to 20.0% by mass of a resin component, water, a water-soluble organic solvent, coloring material, wax, additives, etc., based on the total mass of the ink.

[0017] When the sheet S on which an image has been formed (printed) by the recording unit 2020 is transported by the print belt unit 2010, an inline scanner (not shown) arranged downstream of the recording unit 2020 in the transport direction of the sheet S detects misalignment and color density of the image formed on the sheet S. Based on this image misalignment and color density, corrections are made to the image to be formed on the sheet S, its density, etc.

[0018] The drying module 3000 includes a decoupling section 3200, a drying belt unit 3300, and a hot air blowing unit 3400. The drying module 3000 reduces the liquid content of the ink and reaction liquid applied to the sheet S to improve the fixation of the ink to the sheet S by the subsequent fixing module 4000. The sheet S on which an image has been formed is transported to the decoupling section 3200 arranged within the drying module 3000. In the decoupling section 3200, frictional force is generated between the sheet S and the belt by the wind pressure of air blown from above, causing the sheet S to be transported by the belt. In this way, the sheet S placed on the belt is transported by frictional force, thereby preventing the sheet S from shifting as it is transported between the print belt unit 2010 and the decoupling section 3200. The sheet S transported from the decoupling section 3200 is adsorbed and transported by the drying belt unit 3300, and the ink and reaction liquid applied to the sheet S are dried by blowing hot air onto it from the hot air blowing unit 3400 arranged above the belt.

[0019] In this way, the drying module 3000 heats the ink and reaction liquid applied to the sheet S, promoting evaporation of the water, thereby preventing so-called cockling, in which ink splatters on the sheet S and leaves a fringe-like line around the periphery. The drying module 3000 may be any device capable of heat drying, but a hot air dryer or heater is preferred. Heaters that heat air are preferably, for example, electric heating wires or infrared heaters, from the standpoints of safety and energy efficiency. Furthermore, the drying method may be a combination of a method of applying hot air, a method of irradiating the surface of the sheet S with electromagnetic waves (such as ultraviolet or infrared rays), or a conductive heat transfer method using contact with a heating element.

[0020] The fixing module 4000 as a fixing system has a fixing belt unit 4100 as a fixing device. The fixing belt unit 4100 fixes ink onto the sheet S by passing the sheet S conveyed from the drying module 3000 between a heated upper belt unit and a heated lower belt unit.

[0021] The cooling module 5000 has a plurality of cooling sections 5001, which cool the high-temperature sheet S transported from the fixing module 4000. The cooling sections 5001, for example, use a fan to draw outside air into a cooling box to increase the pressure inside the cooling box, and then cool the sheet S by blowing air out of the cooling box through a nozzle due to the pressure onto the sheet S. The cooling sections 5001 are arranged on both sides of the transport path of the sheet S, and cool both sides of the sheet S.

[0022] The cooling module 5000 is provided with a transport path switching unit 5002. The transport path switching unit 5002 switches the transport path of the sheet S depending on whether the sheet S is transported to the reversing module 6000 or to a double-sided transport path for double-sided printing, in which images are formed on both sides of the sheet S.

[0023] The reversing module 6000 has a reversing section 6400. The reversing section 6400 reverses the sheet S being conveyed, changing the orientation of the sheet S when it is discharged to the stacking module 7000. The stacking module 7000 has a top tray 7200 and a stacking section 7500, and stacks the sheet S conveyed from the reversing module 6000.

[0024] During double-sided printing, the sheet S is conveyed to a conveyance path below the cooling module 5000 by the conveyance path switching unit 5002. The sheet S then passes through a double-sided conveyance path including the fixing module 4000, the drying module 3000, the print module 2000, and the feeding module 1000, and is returned to the print module 2000. The double-sided conveyance section of the fixing module 4000 is provided with an inverting unit 4200 that inverts the sheet S. An image is formed with ink on the other side of the sheet S that has been returned to the print module 2000, and the sheet S is then discharged to the stacking module 7000 via the drying module 3000, the fixing module 4000, the cooling module 5000, and the inverting module 6000. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, an inkjet recording apparatus suitable for using the drying device of this embodiment will be described with reference to FIG. 1. The inkjet recording apparatus 100 is a so-called sheet-fed inkjet recording apparatus that forms an ink image on a sheet using ink. The sheet may be any recording material that can accept ink, such as paper such as plain paper or cardboard, plastic film such as an overhead projector sheet, specially shaped sheets such as envelopes or index paper, or cloth.

[0025] 1, the inkjet recording apparatus 100 includes a feeding module 1000, a printing module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inverting module 6000, and a stacking module 7000. The sheet S supplied from the feeding module 1000 undergoes various processes as it is transported along the transport path within each module, and is finally discharged to the stacking module 7000.

[0026] The feeding module 1000, printing module 2000, drying module 3000, fixing module 4000, cooling module 5000, reversing module 6000, and stacking module 7000 may each have separate housings, and these housings may be connected to form the inkjet recording apparatus 100. Alternatively, the feeding module 1000, printing module 2000, drying module 3000, fixing module 4000, cooling module 5000, reversing module 6000, and stacking module 7000 may be arranged in a single housing.

[0027] The feeding module 1000 has storage cabinets 1500a, 1500b, and 1500c for storing sheets S, and the storage cabinets 1500a to 1500c are provided so as to be able to be pulled out toward the front side of the apparatus to store the sheets S. The sheets S are fed one by one in each of the storage cabinets 1500a to 1500c by a separation belt and a transport roller, and are transported to the print module 2000. The number of storage cabinets 1500a to 1500c is not limited to three, and there may be one, two, four or more.

[0028] The print module 2000 has a pre-imaging registration correction unit (not shown), a print belt unit 2200, and a recording unit 2020. The sheet S transported from the feeding module 1000 has its inclination and position corrected by the pre-imaging registration correction unit, and is then transported to the print belt unit 2200.

[0029] A recording unit 2020 is disposed at a position facing the print belt unit 2200 across the transport path of the sheet S. The recording unit 2020 forms an image on the transported sheet S by ejecting ink onto the sheet S from above using multiple recording heads. The sheet S is transported by suction using the print belt unit 2200, ensuring clearance between the sheet S and the recording heads. In this embodiment, a total of five line-type recording heads corresponding to four colors, Y (yellow), M (magenta), C (cyan), and Bk (black), and reaction liquids, are aligned along the transport direction (arrow A).

[0030] The number of ink colors and recording heads is not limited to five. The inkjet method for ejecting ink can be a method using a heat generating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS element, or the like. Each color of ink is supplied to the recording head from an ink tank (not shown) via an ink tube.

[0031] An inline scanner (not shown) is disposed downstream in the transport direction of the recording unit 2020. The sheet S on which an image has been formed in the recording unit 2020 is transported by a print belt unit 2200 to an inline scanner (not shown), which reads the image formed on the sheet S. Based on the image formed on the sheet S, it is possible to correct misalignment and color density of the image to be formed on the sheet S.

[0032] The drying module 3000 includes a decoupling section 3200, a drying belt unit 3300, and a hot air blowing unit 3400. The drying module 3000 reduces the liquid content of the ink applied to the sheet S to improve the fixation of the ink to the sheet S by the subsequent fixing module 4000. The sheet S on which an image has been formed is transported to the decoupling section 3200 of the drying module 3000. In the decoupling section 3200, a wind pressure of air blown from above by an air blowing unit 3201 generates a frictional force between the sheet S and a decoupling belt 2 (see FIG. 2), causing the sheet S to be transported by the decoupling belt 2. In this way, the sheet S placed on the decoupling belt is transported by the frictional force, thereby preventing the sheet S from shifting as it is transported between the print belt unit 2010 and the decoupling section 3200.

[0033] The sheet S conveyed from the decoupling section 3200 is adsorbed and conveyed by the conveyor belt 7 (see FIG. 2) of the drying belt unit 3300, and hot air is blown onto it from a hot air blowing unit 3400 arranged above the conveyor belt 7. In this way, the image forming surface of the sheet S, on which an image is formed with ink, is dried, thereby heating the ink applied to the sheet S and promoting evaporation of moisture. The drying module 3000 that dries the sheet S will be described in detail later.

[0034] The fixing module 4000 has a fixing belt unit 4100. The fixing belt unit 4100 fixes ink onto the sheet S by passing the sheet S conveyed from the drying module 3000 between a heated upper belt unit and a heated lower belt unit.

[0035] The cooling module 5000 has a plurality of cooling sections 5100, which cool the high-temperature sheet S transported from the fixing module 4000. The cooling sections 5100 use, for example, a fan to draw outside air into a cooling box to increase the pressure inside the cooling box, and then cool the sheet S by blowing air out of the cooling box through a nozzle due to the pressure onto the sheet S. The cooling sections 5100 are arranged on both sides of the transport path of the sheet S, and cool both sides of the sheet S.

[0036] The cooling module 5000 is provided with a transport path switching unit 5002. The transport path switching unit 5002 switches the transport path of the sheet S depending on whether the sheet S is transported to the reversing module 6000 or to a double-sided transport path for double-sided printing, in which images are formed on both sides of the sheet S.

[0037] The reversing module 6000 has a reversing section 6400. The reversing section 6400 reverses the sheet S being conveyed, changing the orientation of the sheet S when it is discharged to the stacking module 7000. The stacking module 7000 has a top tray 7200 and a stacking section 7500, and stacks the sheet S conveyed from the reversing module 6000.

[0038] During double-sided printing, the sheet S is conveyed to a conveyance path below the cooling module 5000 by the conveyance path switching unit 5002. The sheet S then passes through a double-sided conveyance path including the fixing module 4000, the drying module 3000, the print module 2000, and the feeding module 1000, and is returned to the print module 2000. The double-sided conveyance section of the fixing module 4000 is provided with an inverting unit 4200 that inverts the sheet S. An image is formed with ink on the other side of the sheet S that has been returned to the print module 2000, and the sheet S is then discharged to the stacking module 7000 via the drying module 3000, the fixing module 4000, the cooling module 5000, and the inverting module 6000.

[0039] [Drying module] Next, the drying module 3000 will be described with reference to Fig. 2. As shown in Fig. 2, the drying module 3000 as a drying device receives the sheet S discharged from the print module 2000, dries the sheet S, and passes the sheet S to the fixing module 4000. In the drying module 3000, a decoupling unit 3200 is disposed upstream in the conveying direction A of the sheet S, and a drying belt unit 3300 and a hot air blowing unit 3400 are disposed downstream of the decoupling unit 3200.

[0040] The upper part of the drying module 3000 is a drying function section 3010, which receives the sheet S discharged from the print module 2000, dries it, and then forms a linear sheet transport path 1 for delivering the sheet S to the fixing module 4000. In this embodiment, the sheet transport path 1 has different functions at the upstream and downstream sections. The sheet transport path 1 is also a path (horizontal path) that transports the sheet in a substantially horizontal direction.

[0041] The upstream portion of the drying function section 3010 has a decoupling section 3200 composed of a decoupling belt 2 and a cold air blowing unit 3. The decoupling section 3200 transports the sheet S by using the cold air blowing unit 3 to blow cold air from above the decoupling belt 2 in the vertical direction, thereby pressing the sheet S against the decoupling belt 2. When the leading edge of the sheet S (the downstream end of the sheet S in the transport direction) reaches the decoupling belt 2 of the drying module 3000, the trailing edge of the sheet S is still on the print belt 4 of the print module 2000. An image is being formed on the sheet S on the print belt 4, and for this reason the sheet S is being transported by suction on the print belt 4.

[0042] In order to prevent disturbances to this image formation process, the force pressing the sheet S against the decoupling belt 2 is weaker than the suction force of the print belt, and the decoupling belt 2 is driven at a speed slightly faster than the print belt 4. In other words, while the trailing edge of the sheet S (the upstream edge of the sheet S in the conveying direction) is on the print belt 4, the sheet S is configured to slide against the decoupling belt 2. On the other hand, the moment the trailing edge of the sheet S leaves the area of ​​the print belt 4, the conveyance of the sheet S becomes dependent on the decoupling belt 2.

[0043] At this time, it is necessary to control the blowing force of the cold air blowing unit 3 so that the sheet S does not slip due to conveyance resistance. Therefore, the speed of the air blown from the cold air blowing unit 3 to the sheet conveyance path 1 is controlled to a predetermined pressure using a pressure sensor (not shown) provided inside the unit and an intake fan (not shown) provided in the intake section, and a blowing force is applied to the sheet S. The cold air blowing unit 3 has a cold air blowing hole surface with many cold air blowing holes for passing air so that a uniform pressing force can be applied to the sheet S.

[0044] The downstream portion of the drying function section 3010 has a drying section 8 composed of a hot air blowing unit 3400 as an air blowing section and a drying belt unit 3300. The hot air blowing unit 3400, which is disposed above the drying belt unit 3300, blows hot air heated by a heater (not shown) onto the drying belt unit 3300. To quickly dry the sheet S, the surface temperature of the drying belt 9 is controlled to a predetermined temperature via a temperature sensor provided inside the drying belt unit 3300 and heating rollers 3351a and 3351b (see FIG. 3) having halogen heaters 3353a and 3353b therein, thereby heating the sheet S. The drying belt unit 3300 suctions the sheet S to fix the sheet S on the drying belt 9 while blowing hot air from above in the vertical direction to dry the sheet S, and transports the sheet S while suppressing rippling, known as cockling.

[0045] [Drying belt unit] Next, the drying belt unit 3300 as a sheet conveying device will be described in detail with reference to Fig. 3. The drying belt unit 3300 conveys a sheet on which an image has been formed by the recording unit 2020. The drying belt unit 3300 includes a drying belt 9 as an endless belt, a driving roller 3331 as a plurality of tension members, heating rollers 3351a and 3351b, tension rollers 3311, a steering roller 3321, a suction fan 3366, a suction duct 3362, a pressure sensor 3368 as a pressure detection unit, an exhaust duct 3367, a control unit 101 (Fig. 4), and the like.

[0046] The drying belt 9 has a plurality of holes (not shown). The drying belt 9 is tensioned by a rotatably fixed driving roller 3331, heating rollers 3351a and 3351b, a tension roller 3311, and a steering roller 3321. The drying belt 9 is transported by the rotation of the driving roller 3331. The steering roller 3321 tilts relative to the driving roller 3331, so that the position (shift position) of the drying belt 9 in the width direction (the width direction of the sheet intersecting the sheet transport direction, the longitudinal direction of the driving roller 3331) is controlled.

[0047] Furthermore, the drive roller 3331 and the heating roller 3351b form a conveying surface 9a for conveying a sheet on the outer circumferential surface of the drying belt 9. Such a drying belt 9 constitutes a part of the above-mentioned sheet conveying path 1, and conveys the sheet S so that the upper surface of the sheet S faces vertically upward, in other words, in a substantially horizontal direction.

[0048] A suction unit 3360 is provided inside the drying belt 9. The suction unit 3360 includes a suction fan 3366 that sucks in air, a suction duct 3362 that sucks in air through multiple holes in the drying belt 9 as the air inside is sucked in by the suction fan 3366, and adsorbs the sheet to the conveying surface 9a, and an exhaust duct 3367. In the suction unit 3360, the suction duct 3362 and the drying belt 9 form a suction chamber 3361, and the suction fan 3366 connected below the suction chamber 3361 exhausts the air inside the suction chamber 3361 to the exhaust duct 3367, thereby generating a negative pressure in the suction chamber 3361.

[0049] Here, since suction fan 3366 requires high static pressure (negative pressure), a centrifugal fan such as a sirocco fan or turbo fan is desirable, but a low-cost axial flow fan may also be used. Also, multiple suction fans 3366 may be used.

[0050] A pressure sensor 3368 is disposed in the suction chamber 3361 as a pressure detector that detects the pressure inside the suction chamber 3361 (i.e., the pressure inside the suction duct 3362). The pressure sensor 3368 is not limited to any particular location as long as it can detect the pressure inside the suction chamber 3361. The pressure sensor 3368 detects the differential pressure (P0-P1) between atmospheric pressure P0 and pressure P1 at the measurement point. In this embodiment, due to the sensor configuration, the value detected by the pressure sensor 3368 is a negative pressure, which is a negative value. However, for ease of explanation, the pressure detected by the pressure sensor 3368 will be described below as an absolute value. The control unit 101 (FIG. 4), which will be described later, sets the rotation speed of the suction fan 3366 to a set rotation speed according to the type of sheet (size and basis weight).

[0051] The drying belt 9 has a plurality of holes (suction holes) of, for example, about 0.4 mm in diameter, which generates a force that attracts the sheet S to the drying belt 9 above the suction unit 3360. The sheet S is held by the drying belt 9 and transported by the suction force that attracts the sheet S and the air pressure from the warm air blowing unit 3400 described above. Here, in order to hold the drying belt 9 in a predetermined position above the suction chamber 3361, the drying belt 9 is supported from the inside by a support member (not shown).

[0052] In the process of conveying the sheet S, the ink is dried by hot air blown from the hot air blowing unit 3400 described above and by heat from the drying belt 9. The drying belt 9 is heated by a belt heating section 3350 consisting of heating rollers 3351a and 3351b and halogen heaters 3353a and 3353b. Halogen heaters 3353a and 3353b are provided inside the heating rollers 3351a and 3351b, respectively, and the heating rollers 3351a and 3351b are heated by the heating of the halogen heaters 3353a and 3353b.

[0053] Heating roller temperature sensors 3356a and 3356b are provided on the outside of heating rollers 3351a and 3351b to detect the temperatures of heating rollers 3351a and 3351b, respectively, and based on the detection results of these sensors, the power input to halogen heaters 3353a and 3353b is controlled so that the surface temperatures of heating rollers 3351a and 3351b reach target temperatures. Heating rollers 3351a and 3351b dry the ink on sheet S by transferring heat to the drying belt 9 that is stretched over them. The temperature of drying belt 9 is detected by non-contact belt temperature sensor 3343, and the target temperatures of heating rollers 3351a and 3351b are controlled so that they reach a set temperature (e.g., 80°C).

[0054] [Control Unit] Next, the control configuration of the drying belt unit 3300 of this embodiment will be described using the block diagram of FIG. 4. The suction fan 3366 is controlled by a control unit 101. The control unit 101 has a central processing unit (CPU) 101a, a read-only memory (ROM) 101b, a random access memory (RAM) 101c, and a timer 101d. The CPU 101a controls each unit by reading programs corresponding to control procedures stored in the ROM 101b. The RAM 101c stores work data and input data, and the CPU 101a performs control by referring to the data stored in the RAM 101c based on the programs. The control unit 101 may control the entire inkjet recording apparatus 100 or may control the drying module 3000. The operation unit 105 allows the user to set various settings for the inkjet recording apparatus 100, such as inputting information about the sheet type. The timer 101d is capable of counting time.

[0055] The control unit 101 is connected to a drive motor 102 connected to the drive roller 3331, and controls the drive motor 102 as a drive unit to drive the drive roller 3331. The control unit 101 is also connected to a steering motor 103 connected to the steering roller 3321, and controls the steering motor 103. The steering motor 103 tilts the steering roller 3321. The control unit 101 controls the deviation of the drying belt 9 by controlling the steering motor 103 in accordance with the detection result of a belt deviation detection sensor (not shown) that detects the position (deviation position) of the drying belt 9 in the width direction.

[0056] The control unit 101 is connected to the suction fan 3366 and sets the rotation speed of the suction fan 3366 to a set rotation speed that is set according to the type of sheet. The set rotation speed is set in advance so that the pressure inside the suction chamber 3361 during sheet conveyance becomes the set pressure according to the type of sheet. The control unit 101 is also connected to a rotation detection sensor 3369 that serves as a rotation detection unit. The rotation detection sensor 3369 is, for example, an encoder that detects the rotation of the drive shaft of the motor that drives the suction fan 3366, and is capable of detecting the rotation speed of the suction fan 3366.

[0057] Furthermore, the control unit 101 determines an abnormality in the drying belt 9 based on the pressure acquired from a pressure sensor 3368 serving as a pressure detection unit. An abnormality in the drying belt 9 refers to, for example, a state in which multiple holes in the drying belt 9 are clogged with paper powder or ink, making it impossible to sufficiently adsorb the sheet to the conveying surface 9a, or a state in which the drying belt 9 is torn. The control unit 101 notifies the display unit 105a of the operation unit 105 or an external device such as a personal computer (not shown) via the communication I / F 104 of such an abnormality in the drying belt 9.

[0058] The operation unit 105 is used to operate the inkjet recording apparatus 100 and is, for example, an operation panel having a touch panel that can input information such as the type of sheet S on which an image is to be formed and display various information. The operation unit 105 may be provided with physical buttons such as a start button in addition to the touch panel. In this embodiment, the display unit 105a of the operation unit 105 has a function of notifying the user of various information including error information such as an abnormality in the drying belt 9. For example, as will be described later, when the control unit 101 determines that an abnormality has occurred in the drying belt 9 based on the pressure acquired from the pressure sensor 3368, the control unit 101 displays on the display unit 105a that an abnormality has occurred in the drying belt unit 3300 (for example, that the drying belt 9 is clogged or that the drying belt 9 is torn).

[0059] Control unit 101 is connected to halogen heaters 3353a and 3353b, heating roller temperature sensors 3356a and 3356b, and belt temperature sensor 3343, and controls the target temperatures of heating rollers 3351a and 3351b so that belt temperature sensor 3343 reaches a set temperature (e.g., 80°C). Control unit 101 controls the power supplied to halogen heaters 3353a and 3353b so that the target temperatures are reached.

[0060] [Drying belt abnormality detection] Next, the control of the drying belt unit 3300 will be described using the flowchart in Fig. 5. In particular, this flowchart shows control related to abnormality determination of the drying belt 9. The control unit 101 executes this control when it detects that the print module 2000 has started a print job (S100). The control unit 101 receives media information (such as paper type) of the sheet S notified from the operation unit 105 or an external device via the communication I / F 104, and rotates the suction fan 3366 at a set rotation speed according to the information (S101).

[0061] Next, the control unit 101 waits until a first predetermined time has elapsed since the suction fan 3366 started to be driven (S102). This is because it takes time for the pressure in the suction chamber 3361 to reach the set pressure after the suction fan 3366 starts to rotate. The first predetermined time is a predetermined time (e.g., 30 seconds). After the first predetermined time has elapsed, the control unit 101 determines whether the absolute value of the pressure detected by the pressure sensor 3368 is equal to or less than a first pressure value (first threshold value) as a predetermined pressure value (S103). The first pressure value is a threshold value for determining whether some of the holes in the drying belt 9 are closed due to paper dust, ink, etc.

[0062] If the absolute value of the pressure detected by the pressure sensor 3368 exceeds the first pressure value in S103 (NO in S103), the control unit 101 starts the timer 101d (S104). Then, the control unit 101 determines whether the number of times that the absolute value of the pressure detected by the pressure sensor 3368 exceeds the first pressure value during a second predetermined time period has reached a first number of times (S105). The second predetermined time period is, for example, the time it takes for the drying belt 9 to make one rotation. The first number of times is, for example, four times. The second predetermined time period and the first number of times can be set as appropriate. For example, the second predetermined time period may be the time it takes for the drying belt 9 to make two rotations, and the first number of times may be, for example, one, two, or five times. In S105, if the number of times that the value of the pressure sensor 3368 exceeds the first pressure value becomes the first number of times (YES in S105), the control unit 101 determines that clogging has occurred in multiple holes of the drying belt 9 (S106).

[0063] That is, when the value detected by the pressure sensor 3368 exceeds the first pressure value, it means that the pressure inside the suction chamber 3361 has increased. The occurrence of this phenomenon multiple times (first number of times in this embodiment) within the second predetermined time period can be determined to be the result of clogging of some of the holes in the drying belt 9, causing periodic changes in pressure. Therefore, if the answer to S105 is YES, the control unit 101 determines that clogging has occurred in some of the holes in the drying belt 9 (S106) and notifies the user of an abnormality in the drying belt 9 (S107). For example, the control unit 101 displays, via the communication I / F 104, on the monitor of the external device or on the display unit 105a of the operation unit 105, that a clogging has occurred in the drying belt 9.

[0064] Next, the control unit 101 determines whether the print job has ended (S108). If the print job has ended (YES in S108), the control unit 101 stops the rotation of the suction fan 3366 and the drying belt 9 (S109). When the rotation of the suction fan 3366 and the drying belt 9 has stopped, this control ends (S110). Note that when notifying the abnormality in S107, the control unit 101 may proceed to S109 without determining whether the print job has ended. That is, the control unit 101 may control the drive motor 102 that drives the drying belt 9, and when notifying the abnormality in S107, stop driving the drying belt 9 and stop driving the suction fan 3366.

[0065] In S108, if the print job is not completed (NO in S108), the process returns to S103 and repeats this flow.

[0066] If the absolute value of the pressure detected by the pressure sensor 3368 is equal to or less than the first pressure value in S103 (YES in S103), the control unit 101 determines whether the absolute value of the pressure detected by the pressure sensor 3368 is equal to or greater than a second pressure value (second threshold) (S111). The second pressure value is a threshold for determining whether the drying belt 9 is in a state such as a broken belt.

[0067] If the absolute value of the pressure detected by the pressure sensor 3368 is lower than the second pressure value in S111 (NO in S111), the control unit 101 starts the timer 101d (S112). Then, the control unit 101 determines whether the number of times the absolute value of the pressure detected by the pressure sensor 3368 has become lower than the second pressure value during a second predetermined time has reached a second number (S113). The second number is, for example, four times. The second number can also be set appropriately and may be, for example, one, two, five, etc. The first number and the second number may also be the same number. If the number of times the value of the pressure sensor 3368 has fallen lower than the second pressure value has reached the second number (YES in S113), the control unit 101 determines that a tear has occurred in the drying belt 9 (S114).

[0068] That is, when the value detected by the pressure sensor 3368 becomes lower than the second pressure value, it means that the pressure in the suction chamber 3361 has decreased. Furthermore, when this phenomenon occurs multiple times (a second number of times in this embodiment) within the second predetermined time period, it can be determined that a tear has occurred in the drying belt 9, resulting in periodic changes in pressure. Therefore, when the answer to S113 is YES, the control unit 101 determines that a tear has occurred in the drying belt 9 (S114) and notifies the user of an abnormality in the drying belt 9 (S107). For example, the control unit 101 displays, via the communication I / F 104, on the monitor of the external device or on the display unit 105a of the operation unit 105, that a tear has occurred in the drying belt 9. Then, the process proceeds to S108. S108 and subsequent steps are as described above.

[0069] [Clogged and torn dryer belt] The relationship between pressure and time when clogging and tearing of the drying belt 9 occurs will be described using FIGS. 6(a) and 6(b). FIG. 6(a) is a graph showing the change in pressure over time when clogging occurs in some of the holes in the drying belt 9. The vertical axis represents pressure, and the horizontal axis represents time. When the suction fan 3366 starts rotating at a rotation speed set according to the media information of the sheet S, the pressure inside the suction chamber 3361 increases as the suction fan 3366 starts rotating, and rises to a set pressure (e.g., 1700 [Pa]). In this embodiment, the pressure is expressed as a constant pressure to simplify the explanation, but in reality, the pressure changes depending on whether or not the sheet S is present. For example, if the sheet S is present on the conveying surface 9a of the drying belt 9, the pressure is 1700 [Pa], and if not, the pressure is 1500 [Pa].

[0070] When a clogged portion of the drying belt 9 reaches above the suction chamber 3361, the pressure inside the suction chamber 3361 rises. When the clogged portion passes the suction chamber 3361, the pressure returns to the desired pressure. If the pressure detected by the pressure sensor 3368 at this time exceeds a first pressure value (2100 [Pa] in this embodiment), it can be assumed that this is due to the influence of clogged holes in the drying belt 9. Since the drying belt 9 is rotating, if the pressure sensor 3368 detects that the pressure exceeds the first pressure value a first number of times in synchronization with the rotation cycle of the belt, it can be determined that the drying belt 9 is clogged.

[0071] Next, Figure 6(b) is a graph showing the change in pressure over time when part of the drying belt 9 is torn. The vertical axis represents pressure, and the horizontal axis represents time. When the suction fan 3366 starts to rotate at the set rotation speed according to the media information of the sheet S, the pressure inside the suction chamber 3361 increases as the suction fan 3366 starts to rotate, and rises to the set pressure (for example, 1700 [Pa]). The actual pressure change has been described above, so a description thereof will be omitted.

[0072] When the torn portion of the drying belt 9 reaches above the suction chamber 3361, the pressure inside the suction chamber 3361 drops. When the torn portion passes the suction chamber 3361, the pressure returns to the desired pressure. If the pressure detected by the pressure sensor 3368 falls below a second pressure value (1000 [Pa] in this embodiment) at this time, it can be assumed that this is due to the influence of a tear in the drying belt 9. Since the drying belt 9 is rotating, if the pressure sensor 3368 detects a pressure less than the second pressure value a second number of times in synchronization with the rotation cycle of the belt, it can be determined that the drying belt 9 is torn.

[0073] As described above, in this embodiment, the pressure sensor 3368 that detects the pressure inside the suction duct 3362 is provided, and it is possible to notify at an appropriate time that a hole in the drying belt 9 is clogged or that a tear has occurred in the drying belt 9. When such a clogged hole or tear has occurred in the drying belt 9, the drying belt 9 may not be able to properly transport the sheet, and the sheet may not be sufficiently dried, which may result in a deterioration in the quality of the product. In contrast, in this embodiment, the pressure detected by the pressure sensor 3368 can be used to notify at an appropriate time that a hole in the drying belt 9 is clogged or that a tear has occurred, allowing a user or a service technician to replace the drying belt 9 at an appropriate time, thereby reducing the deterioration in the quality of the product.

[0074] Although it has been stated above that the arrangement of the pressure sensor 3368 is not particularly limited, more preferred arrangements will be described below.

[0075] Since the device of this embodiment has a horizontal path, the pressure sensor 3368 is disposed vertically between the exhaust duct 3367 and the conveying surface 9a. This is because the suction state can be grasped by measuring the pressure between the exhaust duct 3367 and the conveying surface 9a.

[0076] Furthermore, in this embodiment, the fixing belt unit 4100 of the fixing module 4000 is disposed downstream of the drying belt unit 3300 in the conveying direction. The fixing belt unit 4100 sandwiches and conveys a sheet between two belts, and therefore tends to have higher conveying stability than the drying belt unit 3300, which conveys a sheet using a single belt. Sheets that have entered the fixing belt unit 4100 are conveyed stably. On the other hand, ensuring conveying stability is more important for sheets that have not entered the fixing belt unit 4100, such as those located upstream of the conveying surface 9a, than for sheets located downstream. Therefore, by disposing the pressure sensor 3368 upstream of the conveying surface 9a of the drying belt unit 3300, specifically, upstream of the center of the conveying surface 9a in the sheet conveying direction, the sheet conveying stability can be monitored more accurately.

[0077] <Second embodiment> The second embodiment will be described with reference to Figures 7 to 8(b). In the first embodiment described above, the rotation speed of the suction fan 3366 was controlled to be constant, and an abnormality in the drying belt 9 was determined based on the detection result of the pressure sensor 3368. In contrast, in this embodiment, the rotation speed of the suction fan 3366 is controlled based on the detection result of the pressure sensor 3368, and an abnormality in the drying belt 9 is determined based on the rotation speed of the suction fan 3366. Since the other configurations and operations are the same as those of the first embodiment described above, the same reference numerals are used to designate the same configurations, and their description and illustration will be omitted or simplified. The following description will focus on the differences from the first embodiment.

[0078] In this embodiment, the control unit 101 (FIG. 4) controls the rotation speed of the suction fan 3366 based on the detection result of the pressure sensor 3368 so that the pressure inside the suction chamber 3361 becomes a set pressure (for example, 1700 [Pa]). That is, the control unit 101 is connected to the pressure sensor 3368 and the suction fan 3366, and controls the rotation speed of the suction fan 3366 so that the pressure inside the suction chamber 3361 becomes the set pressure during sheet conveyance. The set pressure is set based on the type of sheet (size and basis weight). The control unit 101 then determines whether there is an abnormality in the drying belt 9 based on the pressure acquired from the pressure sensor 3368 and the rotation speed set for the suction fan 3366.

[0079] Control relating to abnormality determination of the drying belt 9 in this embodiment will be described with reference to the flowchart in Fig. 7. When the control unit 101 detects that the print module 2000 has started a print job, it executes this control (S200). The control unit 101 controls the rotation speed of the suction fan 3366 in accordance with the value of the pressure sensor 3368 so that the suction pressure (set pressure) corresponds to the media information (paper type, etc.) of the sheet S notified from the operation unit 105 or an external device via the communication I / F 104 (S201). That is, in this embodiment, the control unit 101 controls the rotation speed of the suction fan 3366 so that the pressure detected by the pressure sensor 3368 becomes the set pressure.

[0080] Next, the control unit 101 waits until a first predetermined time has elapsed since the suction fan 3366 started to be driven (S202). This is because it takes time for the pressure in the suction chamber 3361 to reach the set pressure after the suction fan 3366 starts to rotate. The first predetermined time is a predetermined time (e.g., 30 seconds). After the first predetermined time has elapsed, the control unit 101 determines whether the rotation speed of the suction fan 3366 detected by the rotation detection sensor 3369 is equal to or greater than a first rotation speed (first threshold value) as a predetermined rotation speed (S203). The first rotation speed is a threshold value for determining whether some of the holes in the drying belt 9 are closed due to paper dust, ink, or the like.

[0081] If the rotation speed of the suction fan 3366 detected by the rotation detection sensor 3369 is lower than the first rotation speed in S203 (NO in S303), the control unit 101 starts the timer 101d (S204). Then, the control unit 101 determines whether the number of times that the rotation speed of the suction fan 3366 detected by the rotation detection sensor 3369 has become lower than the first rotation speed during a second predetermined time has reached the first number (S205). The second predetermined time is, for example, the time it takes for the drying belt 9 to make one rotation. The first number is, for example, four times. The second predetermined time and the first number can be set as appropriate. For example, the second predetermined time may be the time it takes for the drying belt 9 to make two rotations, and the first number may be, for example, one, two, or five times. In S205, if the number of times that the value of the rotation detection sensor 3369 is less than the first rotation number becomes the first number of times (YES in S205), the control unit 101 determines that clogging has occurred in multiple holes of the drying belt 9 (S206).

[0082] That is, when the value detected by the rotation detection sensor 3369 is less than the first rotation speed, it means that the pressure in the suction chamber 3361 has increased, causing the rotation speed of the suction fan 3366 to decrease. If this phenomenon occurs multiple times (the first number of times in this embodiment) within the second predetermined time period, it can be determined that this is the result of clogging of some of the holes in the drying belt 9, causing the pressure to periodically change and resulting in a change in the rotation speed of the suction fan 3366. Therefore, if the answer to S205 is YES, the control unit 101 determines that some of the holes in the drying belt 9 are clogged (S206) and notifies the user of an abnormality in the drying belt 9 (S207). For example, the control unit 101 displays, via the communication I / F 104, on the monitor of the external device or on the display unit 105a of the operation unit 105, that a clogging has occurred in the drying belt 9.

[0083] Next, the control unit 101 determines whether the print job has ended (S208). If the print job has ended (YES in S208), the control unit 101 stops the rotation of the suction fan 3366 and the drying belt 9 (S209). When the rotation of the suction fan 3366 and the drying belt 9 has stopped, this control ends (S210). Note that when notifying the abnormality in S207, the control unit 101 may proceed to S209 without determining whether the print job has ended. That is, the control unit 101 may control the drive motor 102 that drives the drying belt 9, and when notifying the abnormality in S107, stop driving the drying belt 9 and also stop driving the suction fan 3366.

[0084] In S208, if the print job is not completed (NO in S208), the process returns to S203 and repeats this flow.

[0085] If the rotation speed of the suction fan 3366 detected by the rotation detection sensor 3369 is equal to or greater than the first rotation speed in S203 (YES in S203), the control unit 101 determines whether the rotation speed of the suction fan 3366 detected by the rotation detection sensor 3369 is equal to or less than the second rotation speed (second threshold) (S211). The second rotation speed is a threshold for determining whether the drying belt 9 is in a state such as a broken belt.

[0086] If the rotation speed of the suction fan 3366 detected by the rotation detection sensor 3369 is higher than the second rotation speed in S211 (NO in S211), the control unit 101 starts the timer 101d (S212). Then, the control unit 101 determines whether the number of times that the rotation speed of the suction fan 3366 detected by the rotation detection sensor 3369 has become higher than the second rotation speed during a second predetermined time has reached a second number (S213). The second number is, for example, four times. The second number can also be set appropriately and may be, for example, one, two, five, etc. The first number and the second number may also be the same number. If the number of times that the value of the rotation detection sensor 3369 has become higher than the second rotation speed has reached the second number (YES in S213), the control unit 101 determines that a tear has occurred in the drying belt 9 (S214).

[0087] That is, when the value detected by the rotation detection sensor 3369 becomes higher than the second rotation speed, it means that the pressure in the suction chamber 3361 has decreased and the rotation speed of the suction fan 3366 has increased. Furthermore, when this phenomenon occurs multiple times (the second number of times in this embodiment) within the second predetermined time, it can be determined that a tear has occurred in the drying belt 9, resulting in a change in the rotation speed of the suction fan 3366 due to periodic changes in pressure. Therefore, if the answer to S213 is YES, the control unit 101 determines that a tear has occurred in the drying belt 9 (S214) and notifies the user of an abnormality in the drying belt 9 (S207). For example, the control unit 101 displays a message that a tear has occurred in the drying belt 9 on the monitor of the external device or on the display unit 105a of the operation unit 105 via the communication I / F 104. Then, the process proceeds to S208. Steps from S208 onward are as described above.

[0088] [Clogged and torn dryer belt] 8(a) and 8(b) will be used to explain the relationship between the rotation speed of the suction fan 3366 and time when clogging or tearing occurs in the drying belt 9. FIG. 8(a) is a graph showing the change in rotation speed over time when clogging occurs in some of the holes in the drying belt 9. The vertical axis represents the rotation speed of the suction fan 3366, and the horizontal axis represents time. When the suction fan 3366 starts rotating at a set rotation speed that results in a set pressure corresponding to the media information of the sheet S, the pressure inside the suction chamber 3361 increases as the suction fan 3366 starts rotating. For example, the set rotation speed of the suction fan 3366 when the set pressure reaches 1700 [Pa] is 10,000 [min-1]. In this embodiment, the rotation speed is expressed as a constant speed to simplify the explanation. However, in reality, the pressure changes depending on whether or not the sheet S is present, so the rotation speed of the suction fan 3366 also changes. For example, when the sheet S is present on the conveying surface 9a of the drying belt 9, the speed is 10,000 [min-1], and when the sheet S is not present, the speed is 13,000 [min-1].

[0089] When a clogged portion of the drying belt 9 reaches above the suction chamber 3361, the pressure inside the suction chamber 3361 rises, and the suction fan 3366 is controlled to reduce its rotation speed. When the clogged portion passes the suction chamber 3361, the pressure returns to the desired pressure, and the rotation speed of the suction fan 3366 also returns to normal. At this time, if the rotation speed detected by the rotation detection sensor 3369 falls below the first rotation speed (9000 min-1 in this embodiment), it can be assumed that this is due to clogging of the drying belt 9. Since the drying belt 9 is rotating, if the rotation detection sensor 3369 controls the rotation speed to be lower than the first rotation speed in synchronization with the belt rotation period, it can be determined that the drying belt 9 is clogged.

[0090] Next, Figure 8(b) is a graph showing the change in rotation speed over time when part of the drying belt 9 is torn. The vertical axis represents the rotation speed of the suction fan 3366, and the horizontal axis represents time. When the suction fan 3366 starts to rotate at a pressure corresponding to the media information of the sheet S, the pressure inside the suction chamber 3361 increases as the suction fan 3366 starts to rotate. For example, the rotation speed of the suction fan 3366 when the set pressure reaches 1700 [Pa] is 10000 [min-1]. The actual change in rotation speed has been described above, so it will not be repeated here.

[0091] When the torn portion of the drying belt 9 reaches the suction chamber 3361, the pressure inside the suction chamber 3361 drops, and the rotation speed of the controlled suction fan 3366 increases. When the torn portion passes the suction chamber 3361, the pressure returns to the desired pressure. At this time, if the rotation speed detected by the rotation detection sensor 3369 exceeds a second rotation speed (14,000 min-1 in this embodiment), it can be assumed that this is due to the influence of a tear in the drying belt 9. Since the drying belt 9 is rotating, if the rotation detection sensor 3369 detects that the rotation speed exceeds the second rotation speed a second number of times in synchronization with the belt rotation period, it can be determined that the drying belt 9 is torn.

[0092] In this embodiment, the pressure sensor 3368 is provided to detect the pressure inside the suction duct 3362, and notification can be made at an appropriate time when a clog has occurred in a hole in the drying belt 9 or when the drying belt 9 has been torn. In particular, in this embodiment, the rotation speed of the suction fan 3366 is controlled based on the detection result of the pressure sensor 3368 so that the pressure inside the suction chamber 3361 remains roughly constant. This makes it possible to suppress fluctuations in the suction pressure of the sheet being transported by the drying belt 9, thereby enabling more stable sheet transport.

[0093] Furthermore, in this embodiment, in a configuration in which the rotation speed of the suction fan 3366 is controlled based on the detection result of the pressure sensor 3368, it is possible to notify at an appropriate time that a hole in the drying belt 9 is clogged or torn from the rotation speed of the suction fan 3366, which changes in response to a change in the pressure inside the suction chamber 3361. Therefore, as in the first embodiment, a user or a service person can replace the drying belt 9 at an appropriate time, thereby reducing deterioration in the quality of the product.

[0094] <Other embodiments> In each of the above-described embodiments, the present invention has been described as being applied to the drying belt unit 3300, but the present invention can also be applied to configurations that include a sheet conveying device that adsorbs and conveys a sheet onto a belt, such as the print belt unit 2010 and the decoupling unit 3200. [Explanation of symbols]

[0095] 9. Drying belt (belt) 9a...Transport surface 100 Inkjet recording device 101 Control unit 102 Drive motor (drive unit) 105...Operation unit 105a...Display section 2020 Recording section (image forming section) 3300···Drying belt unit (sheet transport device) 3331 Drive roller (tension member) 3311 Tension roller (tension member) 3321 Steering roller (tensioning member) 3351a, 3351b: Heating roller (tensioning member) 3353a, 3353b Halogen heater (heater) 3362 Suction duct (duct) 3366···Suction fan 3368···Pressure sensor (pressure detection part) 3369···Rotation detection sensor (rotation detection part) 3400··· Warm air blowing unit (blower section)

Claims

1. an image forming unit that ejects ink to form an image on a sheet; a sheet conveying device that conveys a sheet on which an image has been formed by the image forming unit, the sheet conveying device, an endless belt having a plurality of holes formed therein; a plurality of tension members that tension the belt and form a conveying surface on the outer circumferential surface of the belt for conveying a sheet; A suction fan that draws in air; a duct that sucks air through the holes in the belt by the suction fan, thereby adsorbing the sheet to the conveying surface; a pressure detection unit that detects the pressure inside the duct; a control unit that controls the suction fan so that the rotation speed of the suction fan becomes a set rotation speed, The control unit notifies an abnormality when the number of times that the absolute value of the pressure detected by the pressure detection unit exceeds a predetermined pressure value during a second predetermined time period after a first predetermined time period has elapsed since the start of driving the suction fan reaches a first number. An inkjet recording apparatus characterized by:

2. When the predetermined pressure value is set to a first pressure value, the control unit notifies an abnormality when the number of times that the absolute value of the pressure detected by the pressure detection unit during the second predetermined time period becomes lower than a second pressure value that is lower than the first pressure value reaches a second number after the first predetermined time period has elapsed since the suction fan started to be driven.

2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

3. The second predetermined time is the time it takes for the belt to make one revolution.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

4. Further, a drive unit that drives the belt is provided. The control unit controls the drive unit and stops driving the belt when notifying the abnormality.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

5. The control unit stops driving the fan when notifying the abnormality.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

6. Further comprising a display unit, The control unit notifies the user of the abnormality by displaying a message on the display unit that an abnormality has occurred in the sheet conveying device.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

7. At least one of the plurality of tension members is a heating roller having a heater therein.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

8. The conveying device further includes a blower that blows air toward the conveying surface of the belt.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

9. The belt conveys the sheet so that the upper surface of the sheet faces vertically upward.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

10. The set rotation speed is set according to the type of sheet.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

11. further comprising an exhaust duct for exhausting the air sucked by the suction fan, In the vertical direction, the pressure detection unit is disposed between the exhaust duct and the conveying surface.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

12. a fixing device disposed downstream of the sheet conveying device in a sheet conveying direction, The fixing device sandwiches and conveys a sheet between two belts.

3. The inkjet recording apparatus according to claim 1, wherein the inkjet recording head is a recording head.

13. The pressure detection unit is disposed upstream of the center of the conveying surface in the conveying direction.

13. The inkjet recording apparatus according to claim 12.

14. an image forming unit that ejects ink to form an image on a sheet; a sheet conveying device that conveys a sheet on which an image has been formed by the image forming unit, the sheet conveying device, an endless belt having a plurality of holes formed therein; a plurality of tension members that tension the belt and form a conveying surface on the outer circumferential surface of the belt for conveying a sheet; A suction fan that draws in air; a duct that sucks air through the holes in the belt by the suction fan, thereby adsorbing the sheet to the conveying surface; a pressure detection unit that detects the pressure inside the duct; a rotation detection unit that detects the rotation speed of the suction fan; a control unit that controls the rotation speed of the suction fan so that the pressure detected by the pressure detection unit becomes a set pressure, The control unit notifies an abnormality when the number of times that the rotation speed of the suction fan detected by the rotation detection unit becomes lower than a predetermined rotation speed during a second predetermined time period after a first predetermined time period has elapsed since the start of driving the suction fan reaches a first number of times. An inkjet recording apparatus characterized by:

15. When the predetermined number of rotations is set to a first number of rotations, the control unit notifies of an abnormality when the number of times that the number of rotations of the suction fan detected by the rotation detection unit during the second predetermined time period becomes higher than a second number of rotations higher than the first number of rotations after the first predetermined time period has elapsed since the start of driving of the suction fan.

15. The inkjet recording apparatus according to claim 14.

16. The second predetermined time is the time it takes for the belt to make one revolution.

16. The inkjet recording apparatus according to claim 14 or 15.

17. Further, a drive unit that drives the belt is provided. The control unit controls the drive unit and stops driving the belt when notifying the abnormality.

16. The inkjet recording apparatus according to claim 14 or 15.

18. The control unit stops driving the fan when notifying the abnormality.

16. The inkjet recording apparatus according to claim 14 or 15.

19. Further comprising a display unit, The control unit notifies the user of the abnormality by displaying a message on the display unit that an abnormality has occurred in the sheet conveying device.

16. The inkjet recording apparatus according to claim 14 or 15.

20. At least one of the plurality of tension members is a heating roller having a heater therein.

16. The inkjet recording apparatus according to claim 14 or 15.

21. The conveying device further includes a blower that blows air toward the conveying surface of the belt.

16. The inkjet recording apparatus according to claim 14 or 15.

22. The belt conveys the sheet so that the upper surface of the sheet faces vertically upward.

16. The inkjet recording apparatus according to claim 14 or 15.

23. The set pressure is set according to the type of sheet.

16. The inkjet recording apparatus according to claim 14 or 15.

24. further comprising an exhaust duct for exhausting the air sucked by the suction fan, In the vertical direction, the pressure detection unit is disposed between the exhaust duct and the conveying surface.

16. The inkjet recording apparatus according to claim 14 or 15.

25. a fixing device disposed downstream of the sheet conveying device in a sheet conveying direction, The fixing device sandwiches and conveys a sheet between two belts.

16. The inkjet recording apparatus according to claim 14 or 15.

26. The pressure detection unit is disposed upstream of the center of the conveying surface in the conveying direction.

26. The inkjet recording apparatus according to claim 25.

Images