Sheet conveyance device, and image forming device including sheet conveyance device

Abstract

To provide a sheet conveying device capable of preventing an operator from forgetting to attach a separation claw when belt replacement requires attaching and detaching work of the separation claw.SOLUTION: An upper separation claw 4041a and an upper belt temperature sensor 4043a are provided to an upper discharge unit 4040a attachable to and detachable from an upper belt unit 410. When replacing an upper belt 411, the upper separation claw 4041a and the upper belt temperature sensor 4043a are integrally removed by removing the upper discharge unit 4040a from the upper belt unit 410. After replacing the upper belt 411, the upper separation claw 4041a is attached together with the upper belt temperature sensor 4043a by attaching the upper discharge unit 4040a to the upper belt unit 410. In this manner, the upper separation claw 4041a is attached to the upper belt 411 by attaching the upper discharge unit 4040a.SELECTED DRAWING: Figure 20

Description

[Technical field]

[0001] The present invention relates to a sheet conveying device that conveys a sheet by a belt rotatably stretched around a plurality of rollers. [Background technology]

[0002] Patent Document 1 discloses an inkjet type image forming apparatus that heats a sheet while conveying the sheet with a belt. The belt is stretched over multiple rollers, such as a conveying roller that rotates the belt, a steering control roller that suppresses meandering of the belt, a tension roller that applies a certain tension to the belt, and a driven roller that follows the rotation of the belt.

[0003] Patent document 2 discloses an image forming apparatus equipped with a temperature sensor that detects the temperature of the heated fixing belt, and a separation member such as a separation claw that separates a sheet that has reached the vicinity of the exit of the nip portion from the belt in order to improve the separation of the sheet from the fixing belt. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-15290 A [Patent Document 2] JP 2020-34679 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the belt deteriorates, it is replaced before the end of its lifespan. Conventionally, an operator must remove the separation claw before replacing the belt, and then reinstall the separation claw in its original position after replacing the belt. However, operators sometimes forget to install the separation claw. If the separation claw is not installed, unseparated sheets are carried around by the belt, and the temperature sensor cannot detect the belt temperature correctly due to the sheets. This not only causes poor images, but also may cause breakdowns or abnormalities due to heat.

[0006] The present invention has been made in consideration of the above problems, and aims to provide a sheet conveying device that can prevent an operator from forgetting to attach a separation claw when the installation and removal of the separation claw is required when replacing a belt, and an image forming apparatus equipped with a sheet conveying device. [Means for solving the problem]

[0007] A sheet conveying device according to one embodiment of the present invention is a sheet conveying device that conveys a sheet, and is characterized in that it comprises a belt unit having a rotating endless belt, a plurality of tension rollers that tension the belt, and a heating section for heating the belt, a separation member that abuts or is close to the outer peripheral surface of the belt downstream of the sheet conveying surface that conveys the sheet of the belt in relation to the rotation direction of the belt, and separates the sheet conveyed downstream of the sheet conveying surface from the belt, a temperature detection section that detects the temperature of the belt from the outside of the belt downstream in the rotation direction of the separation member, and a holding section that is removably provided on the belt unit and holds the separation member and the temperature detection section as a single unit removably attached to the belt unit. Effect of the Invention

[0008] According to the present invention, in a configuration in which the work of attaching and detaching the separating member is required when replacing the belt, it is possible to prevent an operator from forgetting to attach the separating member. [Brief description of the drawings]

[0009] [Figure 1]FIG. 1 is a schematic diagram illustrating an inkjet recording apparatus. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a perspective view showing the steering unit as viewed from the front side. [Figure 4] FIG. 4 is a perspective view showing the steering unit as viewed from the rear side. [Diagram 5] FIG. [Figure 6] FIG. 4 is an enlarged perspective view showing a rotation detection sensor of the steering roller. [Figure 7] FIG. [Figure 8] FIG. 4 is a schematic diagram showing a fixing belt unit. [Figure 9] FIG. 4 is an enlarged perspective view showing a rotation detection sensor of the tension roller. [Figure 10] FIG. 4 is a cross-sectional view showing the vicinity of an outlet of a nip portion of the fixing belt unit. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. [Figure 15] 4 is a perspective view showing a first state in which an upper door unit of the fixing module is located at a closed position. FIG. [Figure 16] 13 is a perspective view showing a second state in which the upper door unit of the fixing module is located in the open position and the upper belt unit is located in the upper storage position. FIG. [Figure 17] 13 is a perspective view showing a third state in which the upper door unit of the fixing module is positioned in the open position and the upper belt unit is positioned in the maintenance position. FIG. [Figure 18] FIG. 13 is a side view showing the fixing module in a third state. [Figure 19] FIG. 13 is a perspective view showing a state in which the lower belt unit is located at a pulled-out position when the fixing module is in a third state. [Figure 20]Schematic diagrams showing the sheet discharge unit, in which (a) the upper discharge unit and the lower discharge unit are attached to the upper belt unit, (b) the upper belt unit is positioned in the maintenance position, (c) the upper discharge unit is removed from the upper belt unit, and (d) the lower discharge unit is removed from the lower belt unit. [Figure 21] 6 is a perspective view showing attachment and detachment of the upper discharge unit to the upper belt unit. FIG. [Figure 22] 6 is a perspective view showing attachment and detachment of the lower discharge unit to the lower belt unit. FIG. [Figure 23] FIG. 4 is a control block diagram showing a control system of the fixing module. [Figure 24] 11 is a flowchart showing a detection control process of the separation claws. [Diagram 25] FIG. 13 is a diagram showing an example of an error screen. [Figure 26] FIG. 4 is a perspective view showing a direction in which the sheet discharge unit is attached to and detached from the drying belt unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, an image forming apparatus equipped with a sheet conveying device of this embodiment will be described with reference to FIG. 1. Here, as an example of the image forming apparatus, a so-called sheet-fed inkjet recording apparatus 100 that forms an image on a sheet using ink and a reaction liquid will be described. The sheet may be any recording material that can receive 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, and cloth.

[0011] In this specification, the side on which an operator stands when operating the inkjet recording apparatus 100 is referred to as the "front (or front)" and the opposite side is referred to as the "rear (or rear)". Additionally, the left side as viewed from the front is referred to as the "left" and the right side as viewed from the front is referred to as the "right".

[0012] <Inkjet recording device> 1, the inkjet recording apparatus 100 includes a feeding module 1000, a print 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 is subjected to various processes while being transported along a transport path in each module, and is finally discharged to the stacking module 7000.

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

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

[0015] The print module 2000 has a pre-imaging transport unit (not shown), a print belt unit 2200, and a recording unit 2300. The sheet S transported from the feeding module 1000 is transported to the print belt unit 2200 after the inclination and position of the sheet S are corrected by the pre-imaging transport unit.

[0016] A recording unit 2300 is disposed at a position facing the print belt unit 2200 with respect to the transport path of the sheet S. The recording unit 2300, which serves as an image forming unit, forms an image by ejecting ink from above onto the sheet S transported by the print belt using multiple recording heads. The sheet S is transported by suction using the print belt unit 2200, ensuring clearance with the recording heads. In this embodiment, a total of five line-type recording heads corresponding to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black) and the reaction liquid are aligned along the transport direction of the sheet S.

[0017] 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 heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS (Micro Electro Mechanical Systems) element, or the like. Each color of ink is supplied to the recording head from an ink tank (not shown) via an ink tube. The ink contains a resin component of "0.1% by mass to 20.0% by mass" based on the total mass of the ink, water, a water-soluble organic solvent, a coloring material, wax, additives, and the like.

[0018] An in-line scanner (not shown) is disposed downstream in the transport direction of the recording unit 2300. The sheet S on which an image has been formed by the recording unit 2300 is transported by the print belt unit 2200 to an in-line scanner (not shown), which reads the image formed on the sheet S. Here, the misalignment and color density of the image formed on the sheet S are detected, and the image to be formed on the sheet S, its density, and the like are corrected based on the misalignment and color density of the image.

[0019] The drying module 3000 includes a cold air blowing unit 3100, a decoupling belt unit 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 in order to improve the fixation of the ink to the sheet S by the subsequent fixing module 4000.

[0020] The sheet S on which an image has been formed is transported to a decoupling belt unit 3200 disposed within the housing of the drying module 3000. In the decoupling belt unit 3200, frictional force is generated between the sheet S and the belt by wind pressure 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 when it is transported between the print belt unit 2010 and the decoupling belt unit 3200.

[0021] The sheet S conveyed from the decoupling belt unit 3200 is conveyed by a drying belt unit 3300 as a sheet conveying device, and ink applied to the sheet S is dried by blowing hot air from a hot air blowing unit 3400 arranged above the belt. The ink applied to the sheet S is heated by the drying module 3000 to promote evaporation of moisture, thereby suppressing the occurrence of so-called cockling, in which ink is scattered on the sheet S and a line like a border is formed around the periphery. The drying module 3000 may be any device that can heat and dry the sheet, but a hot air dryer or a heater is preferable. As the heater, for example, heating by an electric heating wire or an infrared heater is preferable from the viewpoint of safety and energy efficiency.

[0022] The fixing module 4000 has a fixing belt unit 4100. The fixing belt unit 4100 fixes the ink onto the sheet S by passing the sheet S conveyed from the drying module 3000 between a heated upper belt unit 410 and a lower belt unit 420.

[0023] The cooling module 5000 has a cooling section 5100, and cools the high-temperature sheet S transported from the fixing module 4000. The cooling section 5100 cools the sheet S, for example, by taking in outside air with a fan into a cooling box to increase the pressure inside the cooling box, and blowing air from nozzles formed in a transport guide onto the sheet S. The cooling sections 5100 are disposed on both sides of the transport path of the sheet S, and can cool the sheet S from both sides.

[0024] The cooling module 5000 is also 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.

[0025] The inversion module 6000 has an inversion section 6400. The inversion section 6400 inverts the sheet S being conveyed, and changes 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 inversion module 6000.

[0026] 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. Thereafter, the sheet S passes through a double-sided conveyance path of 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 inversion unit 4200 that inverts the sheet S. The sheet S returned to the print module 2000 has an image formed with ink on the other side on which the image is not formed, and is discharged to the stacking module 7000 via the drying module 3000, the fixing module 4000, the cooling module 5000, and the inversion module 6000.

[0027] <Drying module> Next, the configuration of the drying module 3000 will be described with reference to Fig. 2. As shown in Fig. 2, in the decoupling belt unit 3200, the decoupling belt 3201 is stretched by a driving roller 3331, a tension roller 3211, and tension rollers 3270a and 3270b. Both ends of the driving roller 3331, the tension roller 3211, and the tension rollers 3270a and 3270b are rotatably supported by the front and rear plates of the decoupling belt unit 3200. Of these rollers, the tension roller 3211 is supported by a slide rail 3213 so as to be displaceable and rotatable in a predetermined direction, and applies tension to the decoupling belt 3201 by pressing the decoupling belt 3201 from the inside to the outside by the biasing force of a tension spring 3214.

[0028] The sheet S delivered from the print belt unit 2010 is sent to the decoupling belt unit 3200. When the sheet S is transported, the sheet S is pressed against the decoupling belt 3201 by air blown from the cold air blowing unit 3100 arranged above the decoupling belt unit 3200 and transported. The decoupling belt 3201 has numerous holes and is supported by a punching metal 3202 arranged inside the decoupling belt 3201. The punching metal 3202 has holes smaller than the holes in the decoupling belt 3201, allowing the air blown from the cold air blowing unit 3100 to locations other than the sheet S to escape. In addition, the decoupling belt 3201 is neutralized by a neutralization unit 3250 to prevent the decoupling belt 3201 from becoming charged due to friction between the sheet S and the decoupling belt 3201 and generating an excessive binding force on the sheet S.

[0029] The sheet S conveyed to the decoupling belt 3201 passes through an internal discharge guide 3240 and is sent to a drying belt unit 3300. An endless drying belt 3301 of the drying belt unit 3300 is stretched around a driving roller 3331, a heating roller 3351a, a heating roller 3351b, a tension roller 3311, and a steering roller 3321, which are rotatably fixed. The drying belt 3301 is driven by the rotation of the driving roller 3331. The driving roller 3331 is rotated by a belt driving motor (not shown).

[0030] In this embodiment, with respect to the rotation direction (arrow X direction) of the drying belt 3301, the drive roller 3331 stretches and drives the drying belt 3301 downstream of a sheet transport surface 3301P that transports the sheet S of the drying belt 3301. The heating roller 3351b stretches and heats the drying belt 3301 upstream (upstream in the rotation direction) of the sheet transport surface 3301P. The heating roller 3351a stretches and heats the drying belt 3301 upstream of the heating roller 3351b.

[0031] The hot air blowing unit 3400 disposed above the drying belt unit 3300 blows hot air heated by a heater onto the drying belt unit 3300. A suction unit 3360 is provided on the inside of a sheet conveying surface 3301P of the drying belt 3301. In the suction unit 3360, a suction chamber 3361 is formed by a suction duct 3362 and the drying belt 3301, and a fan 3366 exhausts air to an exhaust duct 3367 to generate negative pressure in the suction chamber 3361. Since the drying belt 3301 has numerous small holes of about "φ0.4 mm" in size, the drying belt 3301 generates a force to attract the sheet S. The sheet S is transported on the sheet conveying surface 3301P of the drying belt 3301 by this suction force and the wind pressure from the hot air blowing unit 3400. Incidentally, inside the drying belt 3301, a number of rollers 3364 for supporting the drying belt 3301 are rotatably disposed at positions that do not impede the suction by the fan 3366.

[0032] During the process of conveying the sheet S by the drying belt 3301, the sheet S is heated by hot air blown from the hot air blowing unit 3400 and by the drying belt 3301, thereby drying the ink applied to the sheet S. The drying belt 3301 is heated by a heating roller 3351a and a heating roller 3351b. Inside the heating rollers 3351a and 3351b, heaters 3353 are provided for increasing the temperatures of the heating rollers 3351a and 3351b, respectively. Outside the heating rollers 3351a and 3351b, heater temperature sensors 3356 are provided for detecting the surface temperatures of the heating rollers. The heater 3353 is temperature-controlled based on the detection result by the heater temperature sensor 3356 so that the temperatures of the heating rollers 3351a and 3351b become the set temperatures. A non-contact belt temperature sensor 3343 such as an infrared sensor is provided to detect the temperature of the drying belt 3301, and the detection result of the belt temperature sensor 3343 is reflected in the temperature setting of the heater 3353. The belt temperature sensor 3343 may be a contact sensor capable of detecting the temperature by contacting the drying belt 3301.

[0033] Also provided is a separation claw 3341 that forcibly separates the sheet S from the drying belt 3301. The separation claw 3341 abuts against or is close to the outer circumferential surface of the drying belt 3301 at the downstream end in the rotation direction of the drying belt 3301, and separates the sheet S transported to the downstream end of the drying belt 3301 from the drying belt 3301.

[0034] In order to improve the heating efficiency of the drying belt 3301, it is effective to increase the contact area of ​​each of the heating rollers 3351a and 3351b with the drying belt 3301. In this embodiment, the heating roller 3351a is "φ110 mm" and the heating roller 3351b is "φ60 mm" which are larger diameter rollers than the other rollers to increase the contact area. As the drying belt 3301 is conveyed, the heat of the drying belt 3301 is dissipated by the atmosphere or other rollers that stretch it. Therefore, by arranging the heating rollers 3351b and 3351a upstream of the sheet conveying surface 3301P, the sheet S is efficiently heated.

[0035] In this embodiment, the tension roller 3311 contributes to improving the heating efficiency of the drying belt 3301. The tension roller 3311 presses the tension portion 3301Q of the drying belt 3301, which is tensioned by the heating rollers 3351a and 3351b, from the outside to the inside, thereby applying a certain tension to the drying belt 3301. The tension roller 3311 moves from the outside to the inside when the drying belt 3301 expands due to heat. At that time, as will be described in detail later, the winding angle between the heating rollers 3351a and 3351b and the drying belt 3301 is secured so as to suppress a change in the contact area between the heating rollers 3351a and 3351b and the drying belt 3301 compared to before the belt expansion.

[0036] The tension roller 3311 presses the tensioning portion 3301Q from the outside to the inside, so that the belt winding angle around the heating roller 3351a and the heating roller 3351b can be set to be close to "180°". This is to improve the temperature rise efficiency of the drying belt 3301 and to reduce the influence of the change in the belt tension posture when the drying belt 3301 stretches due to the temperature rise. When the drying belt 3301 stretches by "20 mm", the intrusion position of the tension roller 3311 only moves by "10 mm", and the winding angle of the drying belt 3301 around the other rollers does not change significantly. This makes it possible to improve both the temperature rise efficiency of the drying belt 3301 and the heat transfer efficiency from the drying belt 3301 to the sheet S, and further to stabilize the belt tension state. The drying belt 3301 may be made of resin, rubber, or metal. However, the drying belt 3301 made of resin or rubber has a larger linear expansion coefficient than that made of metal, so that the above-mentioned effect is easily obtained.

[0037] The sheet S heated by the heating of the drying belt 3301 and the hot air from the hot air blowing unit 3400 is transported to the sheet discharge unit 3340 and then discharged to the fixing module 4000 by the discharge roller 3345. In the drying module 3000, the hot air blowing unit 3401, the heating roller 3351a, and the heating roller 3351b raise the temperature of the drying belt unit 3300 to about "80°C". However, the decoupling belt unit 3200 is configured to blow non-heating air from the upper cold air blowing unit 3100, and the air blowing unit 3102 provided at the upper part of the connection with the drying belt unit 3300 exhausts and sucks in non-heating air to circulate the air and block the hot air from the hot air blowing unit 3400, so there is no large temperature rise and the impact is limited.

[0038] <Steering unit> Incidentally, when the sheet S is transported by the drying belt 3301, it is necessary to control the position of the drying belt 3301 in order to prevent a large deviation from occurring in the transport position of the sheet S in the width direction intersecting the rotation direction of the drying belt 3301. In this embodiment, a steering roller 3321 is disposed between the drive roller 3331 and the heating roller 3351a in relation to the rotation direction of the drying belt 3301, so that the position of the drying belt 3301 can be controlled (see FIG. 2). A steering unit 800 having the steering roller 3321 will be described using FIG. 3 and FIG. 4 with reference to FIG. 2. FIG. 3 shows the steering unit 800 as viewed from the front side, and FIG. 4 shows the steering unit 800 as viewed from the rear side.

[0039] As shown in FIG. 3, one end of the steering roller 3321 is rotatably supported by a steering arm 3323a, and the steering arm 3323a is provided on the front side plate 3303 so as to be rotatable around a rotation shaft 3326a. The steering motor 3324 supports an eccentric steering cam (not shown). A part of the steering arm 3323a is biased by a steering arm spring 3327 in a direction to abut against the steering cam. As the steering cam is rotated by the steering motor 3324, the steering arm 3323a rotates by the amount of eccentricity of the steering cam 3322. A flag 3328 is rotatably provided on the steering motor 3324 on the opposite side of the steering cam, and a flag sensor 3329 detects the flag 3328. The amount of rotation of the steering motor 3324 is controlled according to the detection result of the flag sensor 3329, and the amount of rotation of the steering roller 3321 is determined.

[0040] 4, the other end of the steering roller 3321 is rotatably supported by a steering arm 3323b, and the steering arm 3323b is provided on the rear side plate 3304 so as to be rotatable about a rotation shaft 3326b. The steering arm 3323b rotates so as to absorb the twist generated when the above-mentioned steering arm 3323a rotates, and does not greatly change the position of the steering roller 3321.

[0041] With this configuration, the steering arm 3323a rotates and swings the steering roller 3321, thereby generating a thrust force in the width direction (rotation axis direction) on the drying belt 3301, thereby controlling the position of the drying belt 3301. Note that a configuration may be adopted in which the steering arm 3323b is fixed to the rear side plate 3304 without providing the rotation shaft 3326b, and the play of the support part 3330 that supports the steering roller 3321 absorbs the twist generated in the steering roller 3321 when the steering arm 3323a rotates.

[0042] <Tension unit> As described above, the tension roller 3311 presses the drying belt 3301 from the outside to the inside to apply a constant tension to the drying belt 3301. The tension unit 3310 having the tension roller 3311 will be described using Fig. 5 with reference to Fig. 2. Fig. 5 shows the tension unit 3310. The tension unit 3310 is a unit that is detachable from the drying belt unit 3300.

[0043] 5, the tension roller 3311 is rotatably supported by a tension arm 3312, and the tension arm 3312 is supported so as to be movable in a predetermined direction along a slide rail (not shown) relative to a tension frame 3317. The tension arm 3312 is biased by a plurality of tension springs 3314, so that the tension roller 3311 is biased in a biasing direction T1 from the outside to the inside via the tension arm 3312. In this embodiment, when the tension unit 3310 is incorporated into the drying belt unit 3300 and biases the drying belt 3301, a tension of, for example, "40 kgf" is applied to the drying belt 3301.

[0044] A large biasing force is required to tension the drying belt 3301 without slack, and the operator must operate the tension unit 3310 with a large force to apply and release the biasing force. In order to reduce the burden on the operator, the present embodiment has a two-stage lever pressure release structure. The tension lever 3316a is supported by a lever shaft 3316c extending in the direction of the rotation axis (width direction) of the tension roller 3311, and an eccentric cam (not shown) is provided on the lever shaft 3316c. In the position of the tension lever 3316a shown in FIG. 5, the biasing force of the tension spring 3314 biases the tension arm 3312 in the biasing direction T1 via a link member (not shown).

[0045] <Steering roller rotation detection> Next, the rotation detection of the steering roller 3321 will be described with reference to FIG. 6. As described above, the drying belt 3301 is heated by the heating rollers 3351a and 3351b during the sheet conveyance process. On the other hand, heating the drying belt 3301 in a state where the drying belt 3301 is not rotating may lead to damage to the drying belt 3301. The temperature of the drying belt 3301 is detected by the belt temperature sensor 3343, but the correct temperature cannot be detected until the heated part of the drying belt 3301 reaches the position where the belt temperature sensor 3343 is disposed as the drying belt 3301 rotates. In addition, the correct temperature cannot be detected when the drying belt 3301 is heated in a state where it is not rotating. Therefore, a rotation detection sensor 3392 is provided to detect the rotation of the drying belt 3301.

[0046] In this embodiment, a rotation detection sensor 3392 is provided on the steering roller 3321 to detect the rotation of the drying belt 3301. A magnet ring 3391 is attached coaxially to the steering roller 3321. The magnet ring 3391 is magnetized with N and S poles in the circumferential direction. The rotation detection sensor 3392 is disposed so as to face the outer circumferential surface of the magnet ring 3391. The rotation detection sensor 3392 is supported by a rotation detection sensor support plate 3394 and a sensor pressing plate 3393. When the steering roller 3321 rotates and the magnetic field generated by the magnet ring 3391 changes, the rotation detection sensor 3392 reads the change in the magnetic field, thereby detecting the rotation of the steering roller 3321.

[0047] The winding angle of the drying belt 3301 with respect to the steering roller 3321 does not change significantly due to the action of the tension roller 3311 even if the drying belt 3301 is stretched by heat, so the belt tension state on the steering roller 3321 is stable. Therefore, the drying belt 3301 rotates following the rotation of the steering roller 3321, so the rotation detection sensor 3392 can detect the rotation of the drying belt 3301 without erroneous detection. If the rotation detection sensor 3392 is provided near the heating rollers 3351a and 3351b, it is not preferable because it is close to the heat source, and there is a risk of the device becoming larger, so it is difficult to adopt it. As in this embodiment, by arranging the rotation detection sensor 3392 on the steering roller 3321 located away from the heating rollers 3351a and 3351b, the rotation of the drying belt 3301 can be correctly detected without being affected by heat and without making the device larger. The rotation detection sensor 3392 is not limited to the above-mentioned one, and other types may be used.

[0048] <Fixing module> Next, the fixing module 4000 will be described in detail with reference to FIG. 7. In this embodiment, the fixing module 4000 is an example of a sheet conveying device that conveys a sheet. FIG. 7 is a schematic diagram showing the fixing module 4000. A fixing belt unit 4100 is provided on the upper part of the fixing module 4000. The fixing belt unit 4100 has a substantially linear sheet conveying path 400a for receiving the sheet S discharged from the drying module 3000, performing fixing, and then delivering the sheet S to the cooling module 5000. Then, sheet discharge units (4040a, 4040b), which will be described later, are provided downstream of the sheet conveying path 400a in the conveying direction of the sheet S.

[0049] The fixing belt unit 4100 has an upper belt unit 410 and a lower belt unit 420. The upper belt unit 410 is disposed vertically above the lower belt unit 420. The upper belt unit 410 has an upper belt 411 and a plurality of tension rollers around which the upper belt 411 is stretched. The upper belt unit 410 has the upper belt 411 that conveys the sheet S in a detachable manner. The lower belt unit 420 has a lower belt 421, a plurality of tension rollers around which the lower belt 421 is stretched, and a pad 423 having an arc-shaped curved surface. The pad 423 is disposed so as to form a nip portion with the upper belt 411 via the lower belt 421.

[0050] The sheet S is conveyed while being sandwiched in a nip between the upper belt unit 410 and the lower belt unit 420. The lower belt 421 is disposed opposite the upper belt unit 410 when the upper door unit 43 described later is located in the closed position and the upper belt unit 410 is located in the upper storage position. At this time, the lower belt 421 conveys the sheet S by sandwiching it together with the upper belt 411. The pressure of the nip is determined by the tension and thickness of the upper belt 411 and the curvature of the pad 423. If the pressure of the nip is too high, the ink of the sheet S may adhere to the upper belt 411 and peel off from the sheet S. Therefore, the pressure is preferably "1 Pa to 2000 Pa", and more preferably "1 Pa to 200 Pa".

[0051] When the curvature of the pad 423 becomes large, the difference in the conveying path between the front and back of the sheet S becomes large, and there is a possibility that friction will occur between the sheet S and the belt. When the curvature of the pad 423 becomes large, there is a possibility that a phenomenon will occur in which the sheet S itself memorizes the curved shape and curls, so it is desirable that the curvature radius of the pad 423 is "50 mm or more". In addition, from the viewpoint of manufacturing precision, it is desirable that the curvature radius of the pad 423 is "100000 mm or less". Due to these constraints, in this embodiment, the tension of the upper belt 411 is 200 N, the thickness is "0.3 mm", the curvature of the pad 423 is "30000 mm", and the nip pressure is about 16 Pa.

[0052] By adopting such a configuration, uniform pressure can be applied even in a wide nip. As a result, even when the temperature of the upper belt unit 410 is set to the melting point of wax or the boiling point of water, the contact time between the sheet S and the upper belt unit 410 can be increased to sufficiently transfer heat to the sheet S. However, if the nip continues to be formed after the heat is sufficiently transferred, a phenomenon occurs in which the ink adheres to the upper belt 411 and peels off the sheet S, or the upper belt 411 and the sheet S rub against each other, causing a disturbance in the image, so a contact time that is too long is not preferable. Therefore, it is desirable that the time it takes for the leading edge of the sheet S to enter the entrance of the nip and come out of the exit of the nip is "0.5 s to 4 s". In this embodiment, a pad 423 with a length of "900 mm" in the sheet transport direction is used, the sheet S is transported at "700 mm / s", and the time it takes for the leading edge of the sheet S to enter the entrance of the nip and completely exit the exit of the nip is "about 1.3 s". Since moisture is necessary for ink to penetrate into the sheet S, it is preferable that the upper belt 411 and the lower belt 421 are impermeable to prevent moisture evaporated from the surface of the sheet S from escaping through the upper belt 411 or the lower belt 421 that they come into contact with when the sheet becomes hot.

[0053] <Fusing belt unit> Next, the fixing belt unit 4100 will be described with reference to Fig. 8. As shown in Fig. 8, the fixing belt unit 4100 as a sheet conveying device includes an upper belt unit 410 and a lower belt unit 420, and a nip portion N is formed by pressing an upper belt 411 of the upper belt unit 410 and a lower belt 421 of the lower belt unit 420 together. A sheet S1 is sandwiched and conveyed at the nip portion N, and an image formed with ink is fixed to the sheet S by applying pressure and heat thereto.

[0054] The upper belt unit 410 includes an endless upper belt 411, a plurality of tension rollers that tension the upper belt 411, and a first heating unit 4060a. The plurality of tension rollers are an entrance roller 4110, an exit roller 4120, a driving roller 4031a, a tension roller 4011a, a guide roller 4051a, and a steering roller 4021a. These rollers are arranged in order from the upstream of the nip portion N in the rotation direction of the upper belt 411, and the upper belt 411 forms a rotation trajectory. The nip portion N is present between the entrance roller 4110 and the exit roller 4120. That is, the entrance roller 4110 and the exit roller 4120 are arranged to sandwich the nip portion N in the rotation direction of the upper belt 411. Each roller is supported by an upper frame 414, which is a housing of the upper belt unit 410. The steering rollers 4021a and 4021b are swung by two steering motors 4029a and 4029b (see FIG. 23 described later) that are provided independently of each other.

[0055] The first heating unit 4060a as a heating section is disposed inside the upper belt 411 and includes a first heater section 4061a and a reflecting plate 4052a. The first heating unit 4060a is detachable from the first belt unit body 410a having the upper belt 411. The first belt unit body 410a includes the upper belt 411, a plurality of rollers that stretch the upper belt 411, and an upper frame 414. The first heater section 4061a is disposed in a non-contact manner with the upper belt 411 and along the width direction of the upper belt 411 that intersects with the rotation direction of the upper belt 411, and heats the upper belt 411 by radiating heat. The reflecting plate 4052a is disposed along the width direction and reflects the radiant heat of the first heater section 4061a toward a predetermined area of ​​the upper belt 411.

[0056] In this embodiment, the first heating unit 4060a of the upper belt unit 410 is disposed inside the upper belt 411 and above the nip portion N, and heats the upper belt 411 from the inside. The first heating unit 4060a has a plurality of first heater parts 4061a. In this embodiment, three first heater parts 4061a are arranged side by side in the rotation direction of the upper belt 411. In addition, a reflecting plate 4052a is arranged so as to cover the periphery of the first heater part 4061a except for the side facing the upper belt 411. The reflecting plates 4052a are arranged in the same number as the first heater parts 4061a in correspondence with the first heater parts 4061a. In addition, the reflecting plate 4052a is formed so that the nip portion N side of the first heater part 4061a is open and so as to cover both ends in the width direction of the first heater part 4061a. This allows the radiant heat of the first heater portion 4061a to be radiated toward the nip portion N efficiently by the reflecting plate 4052a.

[0057] That is, in the upper belt unit 410, the predetermined area is an area (first area) in the range of the nip portion N on the inner circumferential surface of the upper belt 411, and the nip portion N is directly heated by the multiple first heater portions 4061a and the multiple reflectors 4052a. This allows heat to be efficiently transferred to the sheet S passing through the nip portion N. In this embodiment, the area in the range of the nip portion N heated by the multiple first heater portions 4061a is the inner circumferential surface (lower surface portion) of the upper belt 411, and is the lower surface portion 411a located upstream of the center position of the nip portion N with respect to the conveying direction of the sheet S passing through the nip portion N. That is, in this embodiment, the predetermined area in the upper belt unit 410 is the lower surface portion 411a.

[0058] The lower surface portion 411a is located opposite to the lower belt 421 stretched between a nip upstream roller 426 and a nip downstream roller 427, among the tension rollers of the lower belt 421 described later, and is also located opposite to an area where the lower belt 421 is supported by a pad 423 disposed between these rollers. This allows the distance between the lower surface portion 411a of the upper belt 411 and the first heating unit 4060a to be kept approximately constant regardless of the rotation of the upper belt 411.

[0059] The lower belt unit 420 includes an endless lower belt 421, a plurality of tension rollers that tension the lower belt 421, and a second heating unit 4060b. The plurality of tension rollers are a nip upstream guide roller 425, a nip upstream roller 426, a nip downstream roller 427, a drive roller 4031b, a tension roller 4011b, a guide roller 4051b, a guide roller 428, and a steering roller 4021b. These rollers are arranged in order from the upstream of the nip portion N in the rotation direction of the lower belt 421.

[0060] Further, a nip portion N exists between the nip upstream roller 426 and the nip downstream roller 427, and a pad 423 is disposed therebetween. That is, the nip upstream roller 426 and the nip downstream roller 427 are disposed so as to sandwich the nip portion N with respect to the rotation direction of the lower belt 421. The pad 423 abuts against the inner peripheral surface of the lower belt 421 in the region of the nip portion N to support the lower belt 421. In other words, the nip upstream roller 426 and the nip downstream roller 427 are disposed on both sides of the pad 423 with respect to the rotation direction of the lower belt 421. The distance between the nip upstream roller 426 and the nip downstream roller 427 is shorter than the distance between the entrance roller 4110 and the exit roller 4120. The lower belt 421 has a rotational trajectory formed by each of these rollers and the pad 423. Each of the rollers and the pad 423 is supported by a lower frame 424, which is a housing of the lower belt unit 420.

[0061] The second heating unit 4060b is disposed inside the lower belt 421 and includes a second heater portion 4061b and a reflector 4052b. The second heating unit 4060b is detachable from the second belt unit body 420a having the lower belt 421. The second belt unit body 420a includes the lower belt 421, a plurality of rollers that stretch the lower belt 421, a pad 423, and a lower frame 424. The second heater portion 4061b is disposed in a non-contact manner with the lower belt 421 and along the width direction of the lower belt 421 that intersects with the rotation direction of the lower belt 421, and heats the lower belt 421 by radiating heat. The reflector 4052b is disposed along the width direction and reflects the radiant heat of the second heater portion 4061b toward a predetermined area of ​​the lower belt 421.

[0062] In this embodiment, the second heating unit 4060b of the lower belt unit 420 is disposed inside the lower belt 421 and below the nip portion N, and heats the lower belt 421 from the inside. The second heating unit 4060b has a plurality of second heater parts 4061b. In this embodiment, two second heater parts 4061b are arranged side by side in the rotation direction of the lower belt 421. In addition, a reflector 4052b is arranged so as to cover the periphery of the second heater part 4061b except for the side facing the lower belt 421. The reflector 4052b is arranged in the same number as the second heater part 4061b in correspondence with the second heater part 4061b. In addition, the reflector 4052b is formed so as to open the lower side of the second heater part 4061b and to cover both ends in the width direction of the second heater part 4061b. This allows the radiant heat of the second heater portion 4061b to be efficiently irradiated toward the lower portion of the lower belt 421 by the reflector 4052b.

[0063] That is, in the lower belt unit 420, the predetermined area is an area (second area) of the inner circumferential surface of the lower belt 421 that is outside the nip portion N, and in this embodiment, it is the lower part of the lower belt 421. Specifically, the area outside the nip portion N that is heated by the second heaters 4061b is the inner circumferential surface (lower surface portion) of the lower belt 421 between the guide roller 4051b and the guide roller 428 with respect to the rotation direction of the lower belt 421. That is, the predetermined area in the lower belt unit 420 is the lower surface portion 421a of the lower belt 421, and the lower surface portion 421a is a surface on which the lower belt 421 is stretched in a substantially horizontal direction between the guide roller 4051b and the guide roller 428. As described above, the lower belt unit 420 is provided with the pad 423 at a position corresponding to the nip portion N, and cannot directly heat the nip portion N like the upper belt unit 410. For this reason, by arranging a plurality of second heater portions 4061b and a plurality of reflecting plates 4052b facing the lower surface portion 421a of the lower belt 421, the lower belt 421 is directly heated efficiently.

[0064] The lower surface portion 421a, which is an area of ​​the lower belt 421 heated by the multiple second heater portions 4061b and the multiple reflectors 4052b, is located on the upstream side of the nip upstream guide roller 425 at the entrance of the nip portion N and the steering roller 4021b in the rotation direction of the lower belt 421. The lower surface portion 421a is located downstream of the center position between the guide roller 428 and the tension roller 4011b that tension the lower portion of the lower belt 421 in the rotation direction of the lower belt 421. Therefore, the multiple second heater portions 4061b and the multiple reflectors 4052b can heat the lower belt 421 at a position relatively close to the nip portion N, and the heat can be efficiently transferred to the sheet S passing through the nip portion N.

[0065] As described above, in the upper belt unit 410, the pad 423 keeps the distance between the upper belt 411 and the first heating unit 4060a approximately constant regardless of the rotation of the upper belt 411. This stabilizes the thermal effect from the first heater section 4061a to the upper belt 411. In the lower belt unit 420, the tension roller 4011b and the guide roller 428 stretch the lower belt 421 upstream and downstream of the second heating unit 4060b, so that the distance between the lower belt 421 and the second heating unit 4060b is kept approximately constant regardless of the rotation of the lower belt 421. This stabilizes the thermal effect from the second heater section 4061b to the lower belt 421.

[0066] The first heater portion 4061a and the second heater portion 4061b may be heaters that radiate heat to heat the belt, for example, halogen heaters. In this embodiment, these heaters are halogen heaters.

[0067] As described above, the reflectors 4052a and 4052b are arranged around the first heater section 4061a and the second heater section 4061b to efficiently collect light onto the upper belt 411 and the lower belt 421, respectively. The reflectors 4052a and 4052b are made of, for example, mirror-finished aluminum members to efficiently reflect light. The heater outputs of the first heater sections 4061a and the second heater sections 4061b are controlled based on the temperature detected by a temperature detection section (not shown). This allows the upper belt 411 and the lower belt 421 to be kept at an appropriate temperature.

[0068] In this embodiment, as a preferred example, the belt is directly heated from the inside by a halogen heater, but the heater may be a sheet heating element or an IH heater. Also, the belt may be indirectly heated by contacting a heating roller made of aluminum or the like containing a halogen heater with the belt, or an external heating means may be used to heat the belt from the outside.

[0069] [About the tension rollers of each belt unit] We will now explain the tension rollers 4011a, 4011b and drive rollers 4031a, 4031b of the above-mentioned upper belt unit 410 and lower belt unit 420. Note that the functions of these rollers are the same in the upper belt unit 410 and the lower belt unit 420, so the following explanation will be given taking the rollers of the lower belt unit 420 as an example.

[0070] <Tension roller> First, the tension roller 4011b will be described with reference to FIG. 8. Of the multiple tension rollers provided in the lower belt unit 420, one roller is the tension roller 4011b that applies tension to the lower belt 421. The tension roller 4011b is disposed on the surface (downward) opposite to the surface (upward) that forms the nip portion N, and tensions the lower belt 421. In this embodiment, the tension roller 4011b is disposed downstream of the nip downstream roller 427, which is one of the nip upstream roller 426 and the nip downstream roller 427 that form the nip portion N, in the rotation direction of the lower belt 421. Specifically, the tension roller 4011b is disposed further downstream of the drive roller 4031b that is downstream of the nip downstream roller 427 with respect to the rotation direction of the lower belt 421.

[0071] The tension roller 4011b is supported so as to be movable in a predetermined direction (in the present embodiment, the direction of the arrow shown in FIG. 3) and is pressed by a pressing member (for example, a spring) not shown. For example, when the circumferential length of the lower belt 421 varies from the target length due to manufacturing variations or changes caused by the use conditions, the tension roller 4011b is pressed by the pressing member, so that the tension state of the lower belt 421 can be stabilized. Specifically, in the present embodiment, the tension roller 4011b of the lower belt unit 420 is configured to be supported so as to be movable in the horizontal direction (leftward and rightward). In addition, the tension roller 4011b is arranged so that, from the upstream side of the rotation direction of the lower belt 421, the tension roller 4011b, the guide roller 4051, the heating unit by the second heating unit 4060b, and the guide roller 428 are arranged. The arrangement of this embodiment makes it possible to suppress fluctuations in the distance between the second heating unit 4060b and the lower belt 421 even if the position of the tension roller 4011b moves in the horizontal direction due to variations in the circumferential length of the lower belt 421. Meanwhile, the tension roller 4011a of the upper belt 411 is also configured to be supported so as to be movable in the horizontal direction.

[0072] <Drive roller> Next, the driving roller 4031b will be described with reference to Fig. 8. Of the multiple tension rollers provided in the lower belt unit 420, one roller is a driving roller 4031b for applying a driving force to the lower belt 421.

[0073] The driving roller 4031b is a roller made of metal such as aluminum or iron. Both front and rear ends of the driving roller 4031b are rotatably supported by the lower frame 424, and the driving roller 4031b is rotated by inputting the driving force of a belt driving motor (not shown) using a drive transmission mechanism (not shown) such as a gear or a timing belt, and rotates the lower belt 421 in a predetermined direction by frictional force. The upper belt 411 and the lower belt 421 are rotated by being driven by two belt driving motors (not shown) in which the driving roller 4031a and the driving roller 4031b are provided independently.

[0074] <Tension roller rotation detection> Next, the rotation detection of the tension rollers 4011a and 4011b will be described using Fig. 9 with reference to Fig. 8. Since the rotation detection configurations of the tension rollers 4011a and 4011b are similar, the rotation detection configuration of the tension roller 4011a of the upper belt unit 410 will be described here. Note that the drying belt unit 3300 is also provided with a rotation detection sensor similar to that described below in order to detect the rotation of the tension roller 3311.

[0075] As described above, the upper belt 411 is heated by a plurality of first heater units 4061a during the sheet conveyance process. On the other hand, heating the upper belt 411 in a state where the upper belt 411 is not rotating may lead to damage to the upper belt 411. As shown in FIG. 8, a non-contact type upper belt temperature sensor 4043a such as an infrared sensor is provided to detect the temperature of the upper belt 411, and the detection result of the upper belt temperature sensor 4043a is reflected in the temperature setting of the first heating unit 4060a. Although the temperature of the upper belt 411 is detected by the upper belt temperature sensor 4043a in this manner, the upper belt temperature sensor 4043a cannot detect the correct temperature until the heated portion of the upper belt 411 reaches the position where the upper belt temperature sensor 4043a is disposed as the upper belt 411 rotates. In addition, the upper belt temperature sensor 4043a cannot detect the correct temperature even when the upper belt 411 is heated in a state where it is not rotating. Therefore, in order to detect whether the upper belt 411 is rotating normally so that the upper belt temperature sensor 4043a can detect the correct temperature, a rotation detection sensor 4013a is provided as a rotation detection section.

[0076] As shown in FIG. 9, in this embodiment, a rotation detection sensor 4013a is provided on the tension roller 4011a to detect the rotation of the upper belt 411. A magnet ring 4012a is attached coaxially with the tension roller 4011a. The magnet ring 4012a is magnetized with N and S poles in the circumferential direction. The rotation detection sensor 4013a is disposed so as to face the outer circumferential surface of the magnet ring 4012a. The rotation detection sensor 4013a is supported by a rotation detection sensor support plate 4015a and a sensor pressing plate 4014a. When the tension roller 4011a rotates and the magnetic field generated by the magnet ring 4012a changes, the rotation detection sensor 4013a reads the change in the magnetic field, thereby detecting the rotation of the tension roller 4011a.

[0077] The tension roller 4011a applies tension to the upper belt 411. Therefore, the tension roller 4011a rotates following the rotation of the upper belt 411, so the rotation detection sensor 4013a can detect the rotation of the upper belt 411 without erroneous detection. If the rotation detection sensor 4013a is provided near the first heating unit 4060a (see FIG. 8), it is not preferable because it is close to the heat source. As in this embodiment, by arranging the rotation detection sensor 4013a on the tension roller 4011a located away from the first heating unit 4060a, the rotation of the upper belt 411 can be correctly detected without being affected by heat. Note that the rotation detection sensor 4013a is not limited to the above-mentioned one, and may be of another type.

[0078] In addition, in the fixing belt unit 4100, rotation detection sensors 4013a and 4013b are provided on the steering rollers 4021a and 4021b to detect the rotation of the upper belt 411 and the lower belt 421, respectively. These rotation detection sensors 4013a and 4013b may have the same configuration as the rotation detection sensor 3392 for detecting the rotation of the drying belt 3301 in the drying belt unit 3300 described above.

[0079] <Sheet ejection unit> Next, the sheet discharge units (4040a, 4040b) disposed in the fixing belt unit 4100 will be described with reference to FIG. 8 and FIG. 10 to FIG. 16. FIG. 10 is a cross-sectional view showing the vicinity of the exit of the nip portion of the fixing belt unit 4100. The sheet S that has passed through the nip portion N formed by the upper belt 411 and the lower belt 421 is curvature-separated from the upper belt 411 and the lower belt 421 by the driving rollers 4031a, 4031b, and is conveyed to the cooling module 5000 (see FIG. 1). As shown in FIG. 10, the sheet discharge units (4040a, 4040b) include an upper discharge unit 4040a detachably provided on the upper belt unit 410, and a lower discharge unit 4040b detachably provided on the lower belt unit 420.

[0080] When there is little margin at the leading edge of the sheet S in the conveying direction, or when thin paper or thin coated paper is conveyed with the fiber direction (so-called paper grain) facing the front-rear direction, the leading edge of the sheet S in the conveying direction becomes weak. In that case, the sheet S that has passed through the nip portion N is difficult to be curvature-separated from the upper belt 411 and the lower belt 421 by the driving rollers 4031a and 4031b, so there is a risk that the sheet S will wind around the upper belt 411 or the lower belt 421. To prevent this, the upper discharge unit 4040a as a holding portion holds an upper separation claw 4041a as a separating member and an upper belt temperature sensor 4043a as a temperature detecting portion.

[0081] As shown in Fig. 11 and Fig. 12, the upper discharge unit 4040a has a claw holder 4042a for holding an upper separation claw 4041a and a sensor holder 4042b for holding an upper belt temperature sensor 4043a. A plurality of claw attachment parts 40421 are formed in the claw holder 4042a in the width direction, and the upper separation claw 4041a is replaceably attached to the claw attachment part 40421 by a screw 4049. On the other hand, a plurality of sensor attachment parts 40422 are formed in the sensor holder 4042b in the width direction, and the upper belt temperature sensor 4043a is replaceably attached to the sensor attachment part 40422 by a screw 4049. The plurality of sensor attachment parts 40422 are formed at three locations in the width direction, namely, the center and both ends, and the upper belt temperature sensor 4043a is detachably attached to the sensor attachment part 40422 by a screw 4049. In this embodiment, the upper belt temperature sensor 4043a can be attached to the sensor holding portion 4042b so as to be able to detect the temperature of the center portion of the upper belt 411 and the temperature of at least one of the end portions. The upper discharge unit 4040a has an upper unit attachment portion 4042c in which a through hole is formed so that the shaft portion of a screw 4046a passes through. The upper discharge unit 4040a is screwed to the upper belt unit 410 by the screw 4046a (see FIG. 21 described later).

[0082] As shown in FIG. 13 and FIG. 14, the lower discharge unit 4040b has a claw holder 4042d for holding the lower separation claw 4041b and a sensor holder 4042e for holding the lower belt temperature sensor 4043b. The claw holder 4042d has a plurality of claw attachment parts 40423 formed in the width direction, and the lower separation claw 4041b is replaceably attached to the claw attachment part 40423 by a screw 4049. On the other hand, a plurality of sensor holders 4042e are provided in the width direction, and the lower belt temperature sensor 4043b is replaceably attached by a screw 4049. The plurality of sensor holders 4042e are formed at three locations in the width direction, the center and both ends, and the lower belt temperature sensor 4043b is detachably attached to the sensor holder 4042e by a screw 4049. The lower discharge unit 4040b also has an upper unit attachment part 4042f in which a through hole is formed through which the shaft part of the screw 4046b passes. The lower discharge unit 4040b is screwed to the lower belt unit 420 by screws 4046b (see FIG. 22 described later).

[0083] The upper separation claw 4041a and the lower separation claw 4041b forcibly separate the sheet S from the upper belt 411 and the lower belt 421. Specifically, the upper separation claw 4041a comes into contact with or is close to the outer peripheral surface of the upper belt 411 downstream of a sheet conveying surface 411P that conveys the sheet S formed by the nip portion N in the upper belt 411 in relation to the rotation direction of the upper belt 411, and separates the sheet S conveyed downstream of the nip portion N from the upper belt 411. The lower separation claw 4041b comes into contact with or is close to the outer peripheral surface of the lower belt 421 downstream of a sheet conveying surface 421P that conveys the sheet S formed by the nip portion N in the lower belt 421 in relation to the rotation direction of the lower belt 421, and separates the sheet S conveyed downstream of the nip portion N from the lower belt 421. The upper belt temperature sensor 4043a detects the temperature of the upper belt 411 from the outside of the upper belt 411 in a non-contact manner downstream of the upper separation claw 4041a in the rotation direction of the upper belt 411. The lower belt temperature sensor 4043b detects the temperature of the lower belt 421 from the outside of the lower belt 421 in a non-contact manner downstream of the lower separation claw 4041b in the rotation direction of the lower belt 421.

[0084] In the upper discharge unit 4040a, the claw holder 4042a and the sensor holder 4042b are formed in a mutually intersecting direction so that the upper separation claw 4041a and the upper belt temperature sensor 4043a are disposed as described above with respect to the upper belt 411 when the upper discharge unit 4040a is attached to the upper belt unit 410. Similarly, in the lower discharge unit 4040b, the claw holder 4042d and the sensor holder 4042e are formed in a mutually intersecting direction so that the lower separation claw 4041b and the lower belt temperature sensor 4043b are disposed as described above with respect to the lower belt 421 when the lower discharge unit 4040b is attached to the lower belt unit 420. Note that the upper belt temperature sensor 4043a and the lower belt temperature sensor 4043b are not limited to non-contact type, and may be contact type sensors capable of detecting temperature by contacting the upper belt 411 or the lower belt 421.

[0085] 10, the lower discharge unit 4040b may be provided with an inner discharge roller pair 4045 having a pair of rollers that rotate in contact with each other. The inner discharge roller pair 4045 sandwiches the sheet S that has passed through the nip portion N and transports it to the cooling module 5000. The inner discharge roller pair 4045 may be disposed in the upper discharge unit 4040a. Alternatively, the inner discharge roller pair 4045 may be divided and disposed such that one of the pair of rollers of the inner discharge roller pair 4045 is disposed in the upper discharge unit 4040a and the other of the pair of rollers is disposed in the lower discharge unit 4040b.

[0086] <Jam Clearance> Incidentally, if a sheet becomes jammed (jammed) or slips in conveyance on the sheet conveying path 400a (see FIG. 7) and the conveying timing deviates from the specified timing, the device detects the jam. In this case, the sheet S remaining in the sheet conveying path 400a is automatically discharged to the purge tray, but if the remaining sheet cannot be discharged to the purge tray, the user must remove the remaining sheet. The sheet S is conveyed while being sandwiched in the nip portion between the upper belt unit 410 and the lower belt unit 420, but if the sheet S remains in the nip portion when a jam occurs, the user must open the nip portion and remove the remaining sheet.

[0087] For this reason, either one of the upper belt unit 410 and the lower belt unit 420 is movable relative to the other belt unit between a nip position where the upper belt 411 and the lower belt 421 form a nip portion N, and a spaced position where the upper belt 411 and the lower belt 421 are spaced apart from the nip position. In this embodiment, the upper belt unit 410 is movable relative to the lower belt unit 420 between the nip position and the spaced position. This will be described below.

[0088] As shown in FIGS. 15 and 16, the fixing module 4000 has an upper door unit 43 that can be opened upward. The upper belt unit 410 of the fixing belt unit 4100 is disposed inside the upper door unit 43, and the upper door unit 43 is configured to be able to be opened upward together with the upper belt unit 410. The upper door unit 43 is rotatably connected to the device body 400 by a support shaft 44 (see FIG. 18 described later) provided on the rear side of the device body 400 as a housing. The support shaft 44 as a rotation shaft is provided on the rear side of the device body 400 with respect to the sheet width direction (front-rear direction) that intersects with the sheet conveying direction, and is provided along the sheet conveying direction. The upper door unit 43 is provided rotatably with respect to the device body 400 around the support shaft 44.

[0089] The upper door unit 43 has a handle 431 on the front side of the device body 400, and is rotated and opened by pulling up the handle 431 upward. The upper door unit 43 is an example of a storage section, and is provided separately from the upper belt unit 410, can store the upper belt unit 410, and can be displaced to a closed position (see FIG. 15) and an open position (see FIG. 16) by rotating with respect to the device body 400. In the closed position, the upper belt 411 and the lower belt 421 form a nip portion N at a nip position, and in the open position, the upper belt 411 and the lower belt 421 are spaced apart from each other from the nip position at a spaced position. In this embodiment, the upper door unit 43 is composed of a top plate and side plates, and functions as an upper cover of the device body 400.

[0090] Furthermore, in this embodiment, an operation unit, a display unit 900, and the like are integrally provided in the upper door unit 43. The display unit 900 as a notification unit is, for example, a liquid crystal display capable of displaying various information, and may be a touch panel that allows a user to input various information by touching it. Note that such a display unit 900 may be provided in the print module 2000, the drying module 3000, and the like other than the fixing module 4000.

[0091] When a jam occurs, the user can lift up the handle 431 of the upper door unit 43 to open the upper door unit 43 upward to the separated position, and remove the sheet S remaining inside the apparatus main body 400 from the front of the apparatus. In this embodiment, a gas spring (not shown) is provided to improve operability when the user opens and closes the upper door unit 43. The gas spring biases the upper door unit 43 toward the open position.

[0092] In this embodiment, the upper door unit 43 is provided so as to be rotatable between a horizontal closed position and an open position inclined by "30 degrees" from the horizontal. When the opening angle of the upper door unit 43 is a first angle or less with respect to the horizontal direction, the gas spring has a biasing force that rotates the upper door unit 43 and the upper belt unit 410 to the closed position by their own weight. The upper door unit 43 is fixed in the closed position by hitting an abutment portion (not shown) provided on the device main body 400 by the biasing force of its own weight. The first angle here is, for example, "5 degrees". In addition, when the opening angle of the upper door unit 43 is a second angle or more with respect to the horizontal direction, the gas spring has a biasing force that rotates the upper door unit 43 to the open position. The second angle here is, for example, "20 degrees". As a result, by providing the gas spring, the upper door unit 43 can be automatically closed when the opening angle is "5 degrees or less" and automatically opened when the opening angle is "20 degrees or more", improving operability.

[0093] In this embodiment, in order to improve operability, the reaction force of the gas spring and the resultant force of the weight of the upper door unit 43 and the upper belt unit 410 are set so that the force acts in a direction toward the closed position in the closed position. That is, the arrangement and load setting of the gas spring are set in the direction in which the upper door unit 43 closes. However, the gas spring may be set so that the force acts in a direction toward the open position (opening tendency) even in the closed position, and the closed position may be fixed by a latch mechanism or the like.

[0094] <Upper belt unit part replacement work> The upper belt unit 410 of the fixing belt unit 4100 is provided with components such as an upper belt 411, a plurality of tension rollers, a roller drive unit (not shown), a first heater unit 4061a, and a sensor (not shown). These components have a risk of failure during their product lifespan, and are required to be replaceable in the market in order to accommodate periodic replacement and replacement due to accidental failure. In the commercial printing market, product operation rate is of utmost importance to users, so replacement work is desired to be performed quickly and reliably.

[0095] Therefore, in this embodiment, a configuration is adopted that allows parts replacement of the upper belt unit 410 with the upper door unit 43 open upward, and will be described with reference to Figs. 17 and 18. When performing work such as part replacement, cleaning, or oiling, as shown in Fig. 17, a handle 431 arranged on the front side of the upper door unit 43 is pulled upward, and the upper door unit 43 is rotated upward to open the sheet transport path 400a (see Fig. 7). The upper door unit 43 is held in an open position by a holding member (not shown).

[0096] 18, the fixing module 4000 has a first displacement portion 441 as a displacement portion. The first displacement portion 441 is provided to displace the upper belt unit 410 relative to the upper door unit 43 between an upper storage position (see FIG. 18) stored in the upper door unit 43 and a maintenance position (see FIG. 19) protruding from the upper door unit 43. The first displacement portion 441 has a rotation shaft 46, a stopper 51, and a gas spring 47.

[0097] The rotating shaft 46 is provided on the rear side of the upper door unit 43 when the upper door unit 43 is located at the closed position in the sheet width direction (front-rear direction), and is arranged along the sheet conveying direction. The upper belt unit 410 is provided rotatably around the rotating shaft 46. The upper belt unit 410 arranged inside the upper door unit 43 is supported rotatably relative to the upper door unit 43 by the rotating shaft 46 provided on the rear side of the upper door unit 43. The upper belt unit 410 is fixed to the upper door unit 43 by a lock mechanism (not shown) arranged on the front side of the upper door unit 43.

[0098] The upper belt unit 410 hits a stopper 51 provided on the upper door unit 43 and stops rotating at the maintenance position. That is, the stopper 51 holds the upper belt unit 410 at the maintenance position when the upper door unit 43 is located at the open position. In a third state in which the upper door unit 43 is located at the open position and the upper belt unit 410 is located at the maintenance position, the upper belt 411 can be drawn out to the front side of the device main body 400 in the sheet width direction. In this state, an operator can replace the upper belt 411 or perform maintenance on the upper belt unit 410.

[0099] <Lower belt unit part replacement work> Next, part replacement and maintenance of the lower belt unit 420 will be described with reference to Fig. 19. The upper door unit 43 is placed in the open position, and the double door 950 on the front side of the fixing module 4000 is opened. The fixing member (not shown) that fixes the lower belt unit 420 is removed, and the lower belt unit 420 is pulled out to the front side. This pulls out the lower belt unit 420 supported by slide rails 432 and 433 whose longitudinal direction is the front-rear direction.

[0100] In this embodiment, the slide rails 432 and 433 displace the lower belt unit 420 relative to the device body 400 between a lower storage position stored in the device body 400 and a drawn-out position protruding from the device body 400. Here, the drawn-out position is a position protruding forward from the device body 400 in the sheet width direction and allowing the lower belt 421 to be attached to and detached from the lower belt unit 420. The lower belt unit 420 is allowed to move from the lower storage position to the drawn-out position when the upper door unit 43 is located in the open position. With the lower belt unit 420 drawn out to the drawn-out position, an operator can replace the lower belt 421 or perform maintenance on the lower belt unit 420.

[0101] <Attaching and detaching the upper discharge unit> As described above, when the upper belt unit 410 is in the maintenance position, the upper belt 411 can be replaced. However, when removing the upper belt 411 from the upper belt unit 410, it is necessary to remove the upper separation claw 4041a first. Therefore, in this embodiment, the upper separation claw 4041a and the upper belt temperature sensor 4043a are held in the upper discharge unit 4040a so that the upper separation claw 4041a can be attached and detached integrally to the upper belt unit 410 together with the upper belt temperature sensor 4043a. The attachment and detachment of the upper discharge unit 4040a to and from the upper belt unit 410 will be described using FIGS. 20(a) to 20(c) and 21 with reference to FIGS. 15 and 17.

[0102] When the upper door unit 43 is in the closed position shown in FIG. 15, the upper separation claw 4041a abuts against the outer circumferential surface of the upper belt 411 as shown in FIG. 20(a). In addition, the upper belt temperature sensor 4043a is disposed at a position facing the upper belt 411 downstream of the upper separation claw 4041a in the rotation direction of the upper belt 411. When the upper door unit 43 is displaced from the closed position to the open position shown in FIG. 16, the upper belt unit 410 is moved to a separated position where the upper belt 411 and the lower belt 421 are separated from each other with respect to the lower belt unit 420 as shown in FIG. 20(b). At this time, the upper discharge unit 4040a attached to the upper belt unit 410 is moved integrally with the upper belt unit 410 in a direction away from the lower discharge unit 4040b attached to the lower belt unit 420. Thereafter, with the upper belt unit 410 in the maintenance position (see FIG. 17), as shown in FIG. 20(c), the upper discharge unit 4040a is removed from the upper belt unit 410. To replace the upper belt 411, it is necessary to release the upper separation claw 4041a that is in contact with the upper belt 411, and in this embodiment, the upper discharge unit 4040a that is disposed integrally with the upper belt temperature sensor 4043a is removed from the upper belt unit 410, thereby removing the upper separation claw 4041a. At this time, the upper belt temperature sensor 4043a is also removed.

[0103] As shown in Fig. 21, the upper belt unit 410 has a first support plate 4101 that supports one end of the rollers (4031a, 4011a, 4051a, 4021a, etc.) that stretch the upper belt 411 in the width direction intersecting the rotation direction of the upper belt 411, and a second support plate 4102 that supports the other end of the rollers. The upper discharge unit 4040a is attached to the surface of the first support plate 4101 in the width direction of the upper belt 411. The first support plate 4101 is formed with a boss 4103 as a fitting protrusion that protrudes from the surface toward the upper belt 411 in the width direction. On the other hand, the upper discharge unit 4040a is formed with a fitting hole 4141 that fits with the boss 4103. The upper discharge unit 4040a has one end in the width direction in a state where the boss 4103 is fitted into the fitting hole 4141, and the other end in the width direction is fixed to the second support plate 4102 by a screw 4046a.

[0104] Although not shown in the figure, the worker can remove the bundled wires of the electric components arranged on the front side from the connector, and also remove the screw 4046a screwed to the second support plate 4102, and pull out the upper discharge unit 4040a from the front side of the apparatus main body 400 to the front side. Then, after replacing the upper belt 411, the worker attaches the upper discharge unit 4040a to the upper belt unit 410. At that time, the fitting hole 4141 is fitted into the boss 4103, and the upper discharge unit 4040a is screwed in place with the fitting hole 4141 fitted into the boss 4103, whereby the upper separation claw 4041a comes into contact with the upper belt 411, and the upper belt temperature sensor 4043a is disposed in the above-mentioned opposing position. The position of the upper discharge unit 4040a is determined when the fitting hole 4141 fits with the boss 4103 of the first support plate 4101, but the fitting length is only a few mm, and the contact force of the upper separation claw 4041a against the upper belt 411 is very low (0.3 N or less). Therefore, there is no risk of the surface of the upper belt 411 being scratched when the upper discharge unit 4040a is attached or detached.

[0105] <Attaching and detaching the lower discharge unit> As with the above-described upper belt unit 410, when removing the lower belt 421 from the lower belt unit 420, the lower separation claw 4041b must be removed first. In this embodiment, the lower separation claw 4041b and the lower belt temperature sensor 4043b are held in the lower discharge unit 4040b so that the lower separation claw 4041b and the lower belt temperature sensor 4043b can be attached and detached together with the lower belt unit 420. Attachment and detachment of the lower discharge unit 4040b to the lower belt unit 420 will be described with reference to FIG. 20(d) and FIG. 22.

[0106] As described above, when the upper door unit 43 is displaced from the closed position to the open position shown in FIG. 16, the upper belt unit 410 is moved to a separated position where the upper belt 411 and the lower belt 421 are separated from each other with respect to the lower belt unit 420 (see FIG. 20(b)). After that, in a state where the lower belt unit 420 is pulled out to the pulled-out position (see FIG. 19), the lower discharge unit 4040b is removed from the lower belt unit 420 as shown in FIG. 20(d). In order to replace the lower belt 421, it is necessary to release the lower separation claw 4041b that is in contact with the lower belt 421. In this embodiment, the lower discharge unit 4040b that is disposed integrally with the lower belt temperature sensor 4043b is removed from the lower belt unit 420, thereby removing the lower separation claw 4041b. At this time, the lower belt temperature sensor 4043b is also removed together.

[0107] As shown in FIG. 22, the lower discharge unit 4040b has a first support plate 4201 that supports one end of the rollers (4031b, 4011b, 4021b, etc.) that stretch the lower belt 421 in the width direction intersecting with the rotation direction of the lower belt 412, and a second support plate 4202 that supports the other end of the rollers. The lower discharge unit 4040b is attached to the surface of the first support plate 4201 in the width direction of the lower belt 421. The upper discharge unit 4040a is formed with a boss 4241 that protrudes in the width direction. On the other hand, the first support plate 4201 is formed with a fitting hole 4203 that fits with the boss 4241. The lower discharge unit 4040b is screwed to the second support plate 4202 with a screw 4046b in a state in which the boss 4241 fits with the fitting hole 4203. Although not shown in the figure, the worker can disconnect the bundled wires of the electrical components located at the front side from the connector and also remove the screws 4046b screwed into the second support plate 4202, and then pull out the lower discharge unit 4040b from the front of the device main body 400 to the front side.

[0108] Although not shown in the figure, the worker can pull out the lower discharge unit 4040b from the front of the apparatus main body 400 to the front side by removing the bundled wires of the electric components arranged on the front side and removing the screw 4046b screwed to the second support plate 4202. Then, after replacing the lower belt 421, the worker attaches the lower discharge unit 4040b to the lower belt unit 420. At that time, the fitting hole 4203 is fitted into the boss 4241, and the screw 4046b is used to screw the lower discharge unit 4040b. In this way, by screwing the lower discharge unit 4040b with the fitting hole 4203 fitted into the boss 4241, the lower separation claw 4041b is brought into contact with the lower belt 421, and the lower belt temperature sensor 4043b is placed in the above-mentioned opposing position. The position of the lower discharge unit 4040b is determined when the boss 4241 of the lower discharge unit 4040b is engaged with the fitting hole 4203, but the engagement length is only a few mm, and the contact force of the lower separation claw 4041b against the lower belt 421 is very low (0.3 N or less). Therefore, there is no risk of the surface of the lower belt 421 being scratched when the lower discharge unit 4040b is attached or detached.

[0109] <Control block> FIG. 23 shows a control block diagram of the control system of the fixing module 4000. As shown in FIG. 23, the fixing module 4000 includes a control unit 401 that controls the operation of the entire fixing module. The control unit 401 is connected to a display unit 900, temperature sensors (4043a, 4043b), rotation detection sensors (4013a, 4013b), belt drive motors (4032a, 4032b), steering motors (4029a, 4029b), and heater units (4061a, 4061b) via cables and connectors. The control unit 401 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The ROM and RAM store various programs such as a "separation claw detection control process" (see FIG. 24) described later and various data. The RAM also temporarily stores the results of calculations and the like associated with the execution of various programs.

[0110] For example, when removing the upper belt 411 from the upper belt unit 410, it is necessary to loosen the tension applied to the upper belt 411 in order to make the upper belt 411 easier to remove. Therefore, the tension roller 4011a (detachable roller) is detachably provided on the upper belt unit 410. When the tension roller 4011a is removed, the tension applied to the upper belt 411 is loosened, making it easier to remove the upper belt 411. After replacing the upper belt 411, the removed tension roller 4011a is reinstalled. If the tension roller 4011a is not installed correctly, the upper belt 411 is not given the necessary tension, and the upper belt temperature sensor 4043a cannot correctly detect the temperature of the upper belt 411. If the tension roller 4011a is installed correctly, the tension roller 4011a rotates with the necessary tension applied to the upper belt 411. Therefore, by providing the rotation detection sensor 4013a on the removable tension roller 4011a, it is possible to prevent erroneous detection of temperature due to insufficient belt tension. In addition, it is also possible to detect whether the tension roller 4011a is attached or not according to the detection result of the rotation detection sensor 4013a. In addition to temperature detection by the upper belt temperature sensor 4043a, by starting heating by the first heater unit 4061a after detecting belt drive by detecting the rotation of the tension roller 4011a, it is possible to improve the reliability of the device after belt replacement.

[0111] As described above, in this embodiment, in order to remove the upper separation claw 4041a before removing the upper belt 411 from the upper belt unit 410, the upper discharge unit 4040a is removed from the upper belt unit 410. At that time, the upper belt temperature sensor 4043a is removed together with the upper separation claw 4041a. Therefore, in this embodiment, whether or not the upper separation claw 4041a has been left attached to the upper belt 411 after replacement of the upper belt 411 can be detected by the upper belt temperature sensor 4043a held in the upper discharge unit 4040a integrally with the upper separation claw 4041a.

[0112] <Separation claw detection control process> The following description will be given with reference to Fig. 23, and with reference to Fig. 24 and Fig. 25. Fig. 24 is a flowchart showing the separation claw detection control process. Fig. 25 is an example of an error screen displayed on the display unit. The separation claw detection control process shown here is started by the control unit 401 when the power is turned on after replacement of the upper belt 411. Note that, although the description will be given here using the replacement of the upper belt 411 as an example, it is also applicable when replacing the lower belt 421 or the drying belt 3301 of the drying belt unit 3300 by using the temperature sensor and rotation detection sensor provided therefor.

[0113] As shown in FIG. 24, the control unit 401 judges whether or not a signal has been received from the upper belt temperature sensor 4043a connected so as to be able to receive a signal (S1). In this embodiment, if the upper discharge unit 4040a removed from the upper belt unit 410 has not been reattached, the control unit 401 does not receive a signal from the upper belt temperature sensor 4043a. If a signal has not been received from the upper belt temperature sensor 4043a (No in S1), the control unit 401 issues an error notification (S5). In this case, since the upper discharge unit 4040a has not been reattached, the control unit 401 displays an error screen as shown in FIG. 25 on the display unit 900 to notify the operator that "the separation claw is not attached". The display of this error screen allows the operator to understand that the upper discharge unit 4040a needs to be reattached, and therefore it is possible to prevent the operator from forgetting to attach the upper separation claw 4041a.

[0114] When a signal is received from the upper belt temperature sensor 4043a (Yes in S1), the control unit 401 starts driving the upper belt drive motor 4032a (S2). That is, since the upper separation claw 4041a is reattached, the control unit 401 rotates the upper belt 411. When the control unit 401 rotates the upper belt 411, the control unit 401 judges whether or not the rotation of the upper belt 411 can be detected based on the signal of the rotation detection sensor 4013a (S3). Whether or not the rotation of the upper belt 411 can be detected is judged based on whether or not the rotation amount detected by the rotation detection sensor 4013a is within a predetermined range. When the rotation of the upper belt 411 cannot be detected (No in S3), the control unit 401 issues an error notification (S5). In this case, the control unit 401 causes the display unit 900 to display a message to inform the operator that "the upper belt is not rotating properly." When the rotation of the upper belt 411 has been detected (Yes in S3), the control unit 401 turns on the first heater unit 4061a (S4) to heat the upper belt 411.

[0115] As described above, in this embodiment, the upper separation claw 4041a and the upper belt temperature sensor 4043a are provided in the upper discharge unit 4040a that is detachable from the upper belt unit 410. When replacing the upper belt 411, the upper separation claw 4041a and the upper belt temperature sensor 4043a are removed integrally by removing the upper discharge unit 4040a from the upper belt unit 410. After replacing the upper belt 411, the upper separation claw 4041a is attached together with the upper belt temperature sensor 4043a by attaching the upper discharge unit 4040a to the upper belt unit 410. In this way, the worker can attach the upper separation claw 4041a to the upper belt 411 by attaching the upper discharge unit 4040a, so that the worker will not forget to attach the upper separation claw 4041a after replacing the belt.

[0116] In addition, since the upper separation claw 4041a is attached together with the upper belt temperature sensor 4043a, whether the upper separation claw 4041a has been left attached after the belt has been replaced can be detected based on the presence or absence of a signal from the upper belt temperature sensor 4043a. If the upper discharge unit 4040a is not attached, there is no signal from the upper belt temperature sensor 4043a, and the "error screen" is displayed on the display unit 900 as described above. This allows the worker to know that the upper separation claw 4041a has not been attached even if the upper discharge unit 4040a is not attached. This prevents the worker from forgetting to attach the upper separation claw 4041a after the belt has been replaced.

[0117] The above-described embodiment can also be applied to the drying belt unit 3300 (see FIG. 2) of the drying module 3000. The embodiment can also be applied to a configuration in which the sheet S is conveyed on a belt, instead of a configuration in which the sheet S is nipped and conveyed at a nip portion, as in the drying belt unit 3300. For example, when applied to the drying belt unit 3300, the sheet discharge unit 3340 has a configuration similar to that of the lower discharge unit 4040b (see FIGS. 13 and 14) described above, that is, a configuration in which the separation claw 3341 and the belt temperature sensor 3342 are integrally held in the sheet discharge unit 3340. This makes it possible to attach and detach the separation claw 3341 when replacing the drying belt 3301 by simply attaching and detaching the sheet discharge unit 3340. This makes it possible to prevent the separation claw 3341 from being left unattached when replacing the drying belt 3301.

[0118] In addition, for example, when applied to the drying belt unit 3300, the attachment / detachment direction of the sheet ejection unit 3340 does not have to be the same as the attachment / detachment direction of the lower ejection unit 4040b described above.

[0119] 26, the sheet discharge unit 3340 has a first support plate 3380 that supports one end of the rollers (3331, 3321, 3351a, 3351b, etc.) that stretch the drying belt 3301, and a second support plate 3381 that supports the other end of the rollers, in a width direction that intersects with the rotation direction of the drying belt 3301. The sheet discharge unit 3340 is attached to the drying belt unit 3300 in a first direction (direction of arrow Z in the figure) that intersects with both the rotation direction and width direction of the drying belt 3301.

[0120] In the inkjet recording apparatus 100 of this embodiment, the print module 2000 is connected upstream of the drying module 3000 in the transport direction, and the fixing module 4000 is connected downstream of the drying module 3000 in the transport direction (see FIG. 1), and it is troublesome to disconnect each module for belt replacement. Therefore, the sheet discharge unit 3340 is mounted in a first direction (arrow Z direction in the figure) that intersects with the drying belt unit 3300 in both the rotation direction and width direction of the drying belt 3301. The hot air blowing unit 3400 is disposed inside the above-mentioned upper door unit 43, and when the upper door unit 43 is in the open position, the sheet discharge unit 3340 can be attached and detached without the hot air blowing unit 3400 getting in the way.

[0121] The sheet discharge unit 3340 is attached in a direction intersecting the rotation direction and the width direction of the drying belt 3301, and has an engagement portion 3347 that engages with the first support plate 3380 and the second support plate 3381, respectively. When the sheet discharge unit 3340 is attached from a direction intersecting both the rotation direction and the width direction, the engagement portion 3347 engages with the engaged portions of the first support plate 3380 and the second support plate 3381, so that the sheet discharge unit 3340 is temporarily supported by the first support plate 3380 and the second support plate 3381. In addition, the sheet discharge unit 3340 is provided with hand screw members 3346 as mounting members at both ends in the width direction. With the sheet discharge unit 3340 temporarily supported, an operator can fix the sheet discharge unit 3340 to the drying belt unit 3300 by operating the hand screw members 3346.

[0122] <Other embodiments> In the above embodiment, the inkjet recording apparatus 100 has been described as an example of an image forming apparatus, but the present invention is not limited to this. The present invention can also be applied to, for example, an electrophotographic image forming apparatus using toner, and can obtain the same effects as the present embodiment. [Explanation of symbols]

[0123] 100...image forming apparatus (inkjet recording apparatus), 401...control unit, 410...belt unit (upper belt unit), 411...belt (upper belt), 411P...sheet conveying surface, 900...notification unit (display unit), 2300...image forming unit (recording unit), 3346...attachment member (hand-operated screw member), 4011a...detachment roller (tension roller), 4013a...rotation detection unit (rotation detection sensor), 404 0a...holding section (upper discharge unit), 4041a...separating member (upper separation claw), 4043a...temperature detection section (upper belt temperature sensor), 4045...roller pair (inner discharge roller pair), 4060a...heating section (first heating unit), 4100...sheet conveying device (fixing belt unit), 4101...first support plate, 4102...second support plate, 4103...engagement protrusion (boss), 4141...engagement hole, S...sheet

Claims

1. A sheet conveying device that conveys a sheet, A belt unit including a rotating endless belt, a plurality of tension rollers around which the belt is tensioned, and a heating unit for heating the belt; a separating member that comes into contact with or is close to an outer peripheral surface of the belt downstream of a sheet conveying surface of the belt that conveys a sheet with respect to a rotation direction of the belt, and separates the sheet conveyed downstream of the sheet conveying surface from the belt; a temperature detector that detects a temperature of the belt from an outer side of the belt downstream of the separating member in the rotation direction; a holding portion that is detachably provided on the belt unit and that detachably holds the separating member and the temperature detection portion integrally with the belt unit, A sheet conveying device comprising:

2. the belt unit has a first support plate supporting one end of the tension roller in a width direction intersecting the rotation direction, and a second support plate supporting the other end of the tension roller, One of the first support plate and the holding portion has a fitting protrusion protruding in the width direction, the other of the first support plate and the holding portion has a fitting hole into which the fitting protrusion fits, The holding portion has one end side in the width direction attached to the first support plate in a state in which the fitting protrusion and the fitting hole are fitted to each other, and the other end side in the width direction is detachably attached to the second support plate.

2. The sheet transport device according to claim 1.

3. The retaining portion is attached to the second support plate by a screw.

3. The sheet transport device according to claim 2.

4. the belt unit has a first support plate supporting one end of the tension roller in a width direction intersecting the rotation direction, and a second support plate supporting the other end of the tension roller, the holding portion is attached in a first direction intersecting both the rotational direction and the width direction, and has an engaging portion that engages with the first support plate and the second support plate, The holding portion is detachably attached to the first support plate and the second support plate in a state in which the holding portion is engaged with the first support plate and the second support plate by the engaging portion.

2. The sheet transport device according to claim 1.

5. The holding portion has mounting members at both ends in the width direction for mounting to the first support plate and the second support plate.

3. The sheet transport device according to claim 2.

6. the separating member is detachable from the holding portion in a state where the holding portion is detached from the belt unit.

2. The sheet transport device according to claim 1.

7. the temperature detection unit is detachable from the holding unit in a state where the holding unit is detached from the belt unit.

2. The sheet transport device according to claim 1.

8. the holding section holds a roller pair that sandwiches and conveys a sheet that has passed through the sheet conveying surface downstream of the separating member on the sheet conveying surface, the roller pair being integral with the separating member and the temperature detection section and detachably attached to the belt unit.

2. The sheet transport device according to claim 1.

9. The heating unit heats at least one of the tension rollers.

2. The sheet transport device according to claim 1.

10. any one of the tension rollers is a detachable roller that is detachably provided on the belt unit, The belt unit includes a rotation detection unit that detects rotation of the attachment / detachment roller.

2. The sheet transport device according to claim 1.

11. an image forming unit that forms an image on a sheet; The sheet conveying device according to claim 1 , which conveys a sheet on which an image is formed by the image forming unit; A notification department; a control unit connected to the temperature detection unit so as to be able to receive a signal from the temperature detection unit; When the control unit does not receive a signal from the temperature detection unit, the control unit causes the notification unit to notify that the holding unit is not installed in the sheet conveying device.

1. An image forming apparatus comprising:

Images