Fixing unit

Abstract

The invention relates to a fixing unit. The heater is provided on the inner side of the belt so as not to contact the belt, and heats the belt by emitting electromagnetic waves. The reflecting member reflects the electromagnetic waves emitted by the heater toward a region of the band. The heater is disposed inside the reflective member. The temperature detection unit is disposed outside the reflective member and detects a temperature of the region. The fan generates airflow. The flow path forming portion is provided on an inner side of the belt and forms a flow path through which an air flow generated from the fan flows. The temperature detection unit is provided inside the flow path forming portion.

Description

Technical Field

[0001] The present invention relates to a fixing unit that heats a sheet on which an image is formed by inkjet to fix the image to the sheet. Background Art

[0002] Japanese Patent Application Laid-Open No. 2018-136392 describes a configuration in which the temperature of a heater is measured using a sensor provided on a heater to be heated, and when an abnormal temperature rise is detected, power supply control for the heater is changed. Summary of the Invention

[0003] According to a first aspect of the present invention, a fixing unit includes: an endless belt configured to heat a sheet having an ink image formed thereon to fix the image to the sheet; a heater disposed inside the belt without contacting the belt and configured to heat the belt by emitting electromagnetic waves; a reflecting member configured to reflect electromagnetic waves emitted by the heater toward an area of ​​the belt, the heater disposed inside the reflecting member; a temperature detecting unit disposed outside the reflecting member and configured to detect a temperature of the area; a fan configured to generate an airflow; and a flow path forming portion disposed inside the belt and forming a flow path through which the airflow generated by the fan flows. The temperature detecting unit is disposed inside the flow path forming portion.

[0004] According to a second aspect of the present invention, a fixing unit includes: an endless belt configured to heat a sheet having an ink image formed thereon to fix the image to the sheet; a first heater and a second heater, the first heater and the second heater being disposed inside the belt without contacting the belt and configured to heat the belt by emitting electromagnetic waves; a first reflecting member configured to reflect electromagnetic waves emitted by the first heater toward a first region of the belt, the first heater being disposed inside the first reflecting member; a second reflecting member configured to reflect electromagnetic waves emitted by the second heater toward a second region of the belt, the second heater being disposed inside the second reflecting member; a temperature detecting unit disposed outside the first and second reflecting members and configured to detect a temperature of one of the first and second regions; and a fan configured to generate an airflow. The airflow generated by the fan flows along a portion of the first and second reflecting members in a width direction of the belt intersecting with a rotational direction of the belt. The temperature detecting unit is disposed on a flow path through which the airflow generated by the fan flows.

[0005] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a sectional view showing a schematic configuration of an inkjet recording apparatus according to a first embodiment.

[0007] Figure 2 is a cross-sectional view showing a schematic configuration of a fixing module according to the first embodiment.

[0008] Figure 3A is an enlarged sectional view showing a schematic configuration of a part of the fixing belt unit according to the first embodiment.

[0009] Figure 3B is a cross-sectional view illustrating a heater and a reflector of the fixing belt unit according to the first embodiment.

[0010] Figure 4 is a perspective view showing the configuration around the fan according to the first embodiment.

[0011] Figure 5 is a cross-sectional view of the fixing belt unit according to the first embodiment, taken along the width direction in the fan and the flow path.

[0012] Figure 6A is a perspective view illustrating a first state in which the upper door unit is located at a closed position of the fixing module according to the first embodiment.

[0013] Figure 6B is a perspective view illustrating a second state in which the upper door unit is located at the open position of the fixing module and the upper belt unit is located at the upper storage position of the fixing module according to the first embodiment.

[0014] Figure 6C is a perspective view illustrating a third state in which the upper door unit is located at the open position of the fixing module and the upper belt unit is located at the maintenance position of the fixing module according to the first embodiment.

[0015] Figure 7 is a block diagram regarding fixing control of the upper belt unit according to the first embodiment.

[0016] Figure 8 is a flowchart regarding fixing control of the upper belt unit according to the first embodiment.

[0017] Figure 9A are a plan view and a side view of the temperature sensor according to the first embodiment.

[0018] Figure 9B is a schematic diagram showing a viewing angle of the temperature sensor according to the first embodiment.

[0019] Figure 9C is a graph showing the relationship between viewing angle and measurement accuracy.

[0020] Figure 10A : is a schematic diagram showing the relationship between the heater and the belt in the width direction according to the first embodiment, and a diagram showing the radiation intensity distribution in the width direction of the heater.

[0021] Figure 10B is a graph showing the relationship between the heating time and the temperature of the belt.

[0022] Figure 11 is a diagram showing an ambient temperature distribution in a flow path provided with a temperature sensor according to the first embodiment.

[0023] Figure 12 is an enlarged sectional view showing a schematic configuration of a part of a fixing belt unit according to a second embodiment.

[0024] Figure 13 is a block diagram regarding fixing control of the upper belt unit according to the second embodiment.

[0025] Figure 14 is a cross-sectional view of a fixing belt unit according to a second embodiment, taken along the width direction in a fan and a flow path.

[0026] Figure 151 is a schematic cross-sectional view mainly showing a heating configuration according to the third embodiment, with a portion of the upper belt unit omitted.

[0027] Figure 16 is a schematic diagram showing a temperature sensor, a reflector, and a belt according to a fourth embodiment, as viewed from above the reflector.

[0028] Figure 17A is a schematic diagram of a temperature sensor, a reflector, and a belt according to a fourth embodiment, viewed from the side.

[0029] Figure 17B is a graph showing the relationship between the heating time and the temperature of the belt.

[0030] Figure 18 1 is a schematic cross-sectional view mainly showing a heating configuration according to a fifth embodiment, with a portion of an upper belt unit omitted. DETAILED DESCRIPTION

[0031] First embodiment

[0032] Will refer to Figures 1 to 11 The first embodiment will be described. Figure 1 A schematic configuration of the inkjet recording apparatus of this embodiment is described.

[0033] Inkjet recording equipment

[0034] The inkjet recording apparatus 1 used as an imaging system in this embodiment uses an inkjet recording system that ejects ink to form an image on a sheet. This is a so-called sheet-type inkjet recording apparatus that forms an ink image on a sheet using two liquids: a reaction liquid and ink. The sheet may be, for example, a recording material capable of receiving ink, such as paper (such as plain paper or thick paper), plastic film (such as a sheet used for an overhead projector), a sheet having a special shape (such as an envelope or index paper), or cloth.

[0035] like Figure 1 As shown in FIG. 1 , the inkjet recording apparatus 1 of the present embodiment includes a feeding module 1000, a printing module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, a reversing module 6000, and a stacking module 7000. While the sheet S supplied from the feeding module 1000 is conveyed along a conveying path in each module, various processes are performed, and the sheet S is finally discharged to the stacking module 7000.

[0036] Note that 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 have separate housings, and these housings may be connected to constitute the inkjet recording apparatus 1. 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 provided in one housing.

[0037] The feeding module 1000 includes storage compartments 1100a, 1100b, and 1100c for storing sheets S, and the storage compartments 1100a to 1100c are provided to be drawn toward the front side of the apparatus to store the sheets S. The sheets S are fed one by one in each of the storage compartments 1100a to 1100c by a separator belt and a conveying roller, and are conveyed to the printing module 2000. The number of the storage compartments 1100a to 1100c is not limited to three, and may be one, two, four, or more.

[0038] The printing module 2000, serving as an imaging unit, includes a pre-imaging alignment correction unit (not shown), a printing belt unit 2010, and a recording unit 2020. The sheet S conveyed from the feed module 1000 is corrected for its inclination and position by the pre-imaging alignment correction unit and then conveyed to the printing belt unit 2010. The recording unit 2020 is positioned across the conveying path from the printing belt unit 2010. The recording unit 2020 is an inkjet recording unit that forms an image by ejecting ink onto the sheet S from above via a recording head relative to the conveyed sheet S. The multiple recording heads that eject ink are arranged along the conveying direction. In this embodiment, a total of five line recording heads are provided for the reaction liquids, in addition to the four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). The sheet S is sucked and conveyed by the printing belt unit 2010 to ensure a gap between the recording heads and the sheet S.

[0039] Note that the number of ink colors and the number of recording heads are not limited to the five described above. The inkjet method can employ methods using heating elements, piezoelectric elements, electrostatic elements, or microelectromechanical systems (MEMS) elements. Each color of ink is supplied from an ink cartridge (not shown) to each recording head via an ink tube. The ink contains 0.1% to 20.0% by mass of a resin component, water, a water-soluble organic solvent, a colorant, wax, and additives, based on the total mass of the ink.

[0040] When the print belt unit 2010 conveys a sheet S (on which an image is formed by the recording unit 2020), deviations and color density of the image formed on the sheet S are detected by an inline scanner (not shown) arranged downstream of the recording unit 2020 in the conveying direction of the sheet S. Based on the deviations and color density of the image detected by the inline scanner, deviations, image density, etc. of the image to be formed on the sheet S are corrected.

[0041] The drying module 3000, serving as a drying device, includes a separation unit 3200, a drying belt unit 3300, and a warm air blowing unit 3400. The drying module 3000 reduces the liquid content of the ink and reaction liquid applied to the sheet S to enhance the fixing properties of the ink to the sheet S in the subsequent fixing module 4000. The sheet S, with an image formed thereon, is conveyed to the separation unit 3200, located within the drying module 3000. In the separation unit 3200, the pressure of air blown from above creates friction between the sheet S and the belt, which then conveys the sheet S. This frictional force conveys the sheet S placed on the belt, preventing it from deviating as it is conveyed across the printing belt unit 2010 and the separation unit 3200. The sheet S conveyed from the separation unit 3200 is suctioned and conveyed by the drying belt unit 3300, while hot air is blown from the warm air blowing unit 3400, located above the belt, to dry the ink and reaction liquid applied to the sheet S.

[0042] In this way, by heating the ink and reaction liquid applied to the sheet S and accelerating the evaporation of water by the drying module 3000, the occurrence of the so-called wrinkling phenomenon in which the ink spreads on the sheet S and forms boundary-like lines around the sheet S can be suppressed. As the drying module 3000, any device can be used as long as it can dry the ink in a heating manner. For example, a hot air dryer or a heater is preferred. As an example of a heater, from the perspective of heating safety and heating energy efficiency, an electric heating wire heater or an infrared heater is preferably used. The drying method can be a combination of a method of applying hot air and a method of irradiating the surface of the sheet S with electromagnetic waves (ultraviolet rays, infrared rays, etc.) or a conductive heat transfer method using contact with a heating element.

[0043] The fixing module 4000 serving as a fixing system includes a fixing belt unit 4100 as a fixing unit. The fixing belt unit 4100 passes the sheet S conveyed from the drying module 3000 through heated upper and lower belt units to fix ink to the sheet S. The fixing belt unit 4100 will be described in detail below.

[0044] The cooling module 5000 includes a plurality of cooling units 5001, and cools the high-temperature sheet S conveyed from the fixing module 4000 by the cooling units 5001. For example, each of the cooling units 5001 draws outside air into a cooling box by a fan to increase the pressure inside the cooling box, and blows the air blown out of the cooling box toward the sheet S through a nozzle using pressure to cool the sheet S. The cooling unit 5001 is provided on each of both sides of the conveyance path of the sheet S and cools both surfaces of the sheet S.

[0045] The cooling module 5000 is provided with a conveying path switching unit 5002. The conveying path switching unit 5002 switches the conveying path of the sheet S according to whether the sheet S is conveyed to the reversing module 6000 or conveyed to a duplex conveying path for duplex printing.

[0046] The reversing module 6000 includes a reversing portion 6400. The reversing portion 6400 reverses the front and back of the conveyed sheet S and changes the front and back of the sheet S when the sheet S is discharged to the stacking module 7000. The stacking module 7000 includes a top tray 7200 and a stacking portion 7500, and stacks the sheets S conveyed from the reversing module 6000.

[0047] During duplex printing, the conveyance path switching unit 5002 conveys the sheet S to the conveyance path below the cooling module 5000. Thereafter, the sheet S is returned to the printing module 2000 via the duplex conveyance path of the fixing module 4000, the drying module 3000, the printing module 2000, and the feeding module 1000. A reversing section 4200 for reversing the front and back sides of the sheet S is provided in the duplex conveying section of the fixing module 4000. The sheet S returned to the printing module 2000 has an image formed on the other surface, where no image has been formed, using ink, and is then discharged to the stacking module 7000 via the drying module 3000, the fixing module 4000, the cooling module 5000, and the reversing module 6000.

[0048] Fusing module

[0049] Next, we will refer to Figure 2 The fixing module 4000 is described in detail. Figure 2 4 is a schematic diagram showing the fixing module 4000. A fixing belt unit 4100 as a fixing unit is provided at an upper portion of the fixing module 4000. The fixing belt unit 4100 has a substantially linear sheet conveying path 4100a for receiving the sheet S discharged from the drying module 3000, fixing the sheet S, and then conveying the sheet S to the cooling module 5000 (see FIG. 4). Figure 1). In each of the drawings, the front side of the inkjet recording apparatus 1 is referred to as a front direction F, the back side thereof is referred to as a rear direction B, the right side thereof when viewed from the front side is referred to as a rightward direction R, the left side thereof when viewed from the front side is referred to as a left direction L, the upper side thereof is referred to as an upper direction U, and the lower side thereof is referred to as a lower direction D. An operation unit (not shown) operated by an operator is provided on the front side of the inkjet recording apparatus.

[0050] The fixing belt unit 4100 includes an upper belt unit 10 and a lower belt unit 20. The upper belt unit 10 is arranged above the lower belt unit 20 in the vertical direction. The upper belt unit 10 includes: an upper belt 30, which is an example of a belt or a first belt; and a tension roller 410 (tensile member or first tensile member) that applies tension to the upper belt 30. That is, the upper belt unit 10 is an example of a belt unit (first belt unit) and detachably includes the upper belt 30 that conveys the sheet S. The lower belt unit 20 is an example of a second belt unit and includes: a lower belt 40, which is an example of a clamping portion forming member or a second belt; a tension roller 420 (second tensile member) that applies tension to the lower belt 40; and a pad 428 having an arcuate curved surface. The pad 428 is provided to form a clamping portion with the upper belt 30 via the lower belt 40.

[0051] The sheet S is conveyed while being clamped by the clamping portion between the upper belt unit 10 and the lower belt unit 20. That is, as will be described below, the lower belt 40 is arranged to face the upper belt unit 10 when the upper door unit 43 is in the closed position and the upper belt unit 10 is in the upper storage position. At this time, the lower belt 40 clamps and conveys the sheet S together with the upper belt 30. The pressure of the clamping portion is determined by the tension and thickness of the upper belt 30 and the curvature of the pad 428. When the pressure of the clamping portion is too high, there is a possibility that the ink on the sheet S adheres to the upper belt unit 10 and the ink peels off the sheet S. Therefore, the pressure is preferably 1Pa to 2000Pa, more preferably 1Pa to 200Pa.

[0052] When the curvature of the pad 428 is large, the difference in the conveying path between the front and back sides of the sheet S is large, and there is a possibility that the sheet S and the belt rub against each other. When the curvature of the pad 428 is large, there is a possibility that the sheet S itself remembers the curved shape and curls up. Therefore, the radius of curvature of the pad 428 is ideally 50 mm or more. In addition, from the perspective of manufacturing accuracy, the curvature of the pad 428 ideally has a radius of curvature of 100,000 mm or less. Due to these limitations, in this embodiment, the tension of the upper belt 30 is set to 200 N, the thickness of the upper belt 30 is set to 0.3 mm, the curvature of the pad 428 is set to 30,000 mm, and the pressure of the clamping portion is set to approximately 16 Pa.

[0053] With this structure, even a wide clamping section can be uniformly compressed. As a result, even when the temperature of the upper belt unit 10 is at a temperature corresponding to the melting point of wax or the boiling point of water, sufficient heat can be transferred to the sheet S by extending the contact time between the sheet S and the upper belt unit 10. However, if the clamping section is formed continuously after sufficient heat transfer, ink may adhere to the upper belt 30 and peel off the sheet S, or the upper belt 30 and sheet S may rub against each other, disrupting the image. Therefore, extremely long contact times are not preferred. Therefore, the time it takes for the leading edge of the sheet S to emerge from the clamping section's exit after entering the clamping section's entrance is ideally between 0.5 and 4 seconds. In this embodiment, using a pad 428 having a length of 900 mm in the sheet conveying direction and conveying the sheet S at a speed of 700 mm / s, the time it takes for the leading edge of the sheet S to emerge from the clamping section's exit after entering the clamping section's entrance is approximately 1.3 seconds. Note that, because moisture is essential when the ink permeates into the sheet S, the upper belt 30 and the lower belt 40 are preferably water-impermeable so that moisture evaporated from the surface of the sheet S when the sheet becomes overheated cannot escape through the upper belt 30 or the lower belt 40, which are surfaces in contact with the sheet S. In this embodiment, for the upper belt 30 and the lower belt 40, a belt material having a thickness of approximately 0.4 mm is used, which is obtained by applying a polytetrafluoroethylene (PTFE) coating to the surface of a glass fiber-based material, in consideration of heat resistance, sliding properties, sealing properties, and durability.

[0054] Fusing belt unit

[0055] As described above, the fixing belt unit 4100 as the fixing unit includes the upper belt unit 10 and the lower belt unit 20, and the upper belt 30 of the upper belt unit 10 and the lower belt 40 of the lower belt unit 20 are in pressure contact with each other to form the nip portion N. The sheet S1 is conveyed while being nipped by the nip portion N, and at this time, an image formed by ink is fixed to the sheet S1 by application of pressure and heat.

[0056] The upper belt unit 10 includes an endless upper belt 30, which serves as a belt or a first belt; a plurality of stretching rollers, which serve as a plurality of first stretching members, for stretching the upper belt 30; and a first heating unit 300. The plurality of stretching rollers are an inlet roller 411, an outlet roller 412, a drive roller 610, a tension roller 410, a guide roller 413, a guide roller 414, and a turn roller 415. These rollers are arranged in this order from the upstream side of the nip portion N in the rotation direction of the upper belt 30, thereby forming a rotation trajectory of the upper belt 30.

[0057] In addition, a nip portion N exists between the inlet roller 411 and the outlet roller 412. That is, the inlet roller 411 and the outlet roller 412 are arranged so as to sandwich the nip portion N therebetween in the rotational direction of the upper belt 30. Furthermore, the upper belt 30 is stretched by the inlet roller 411 and the outlet roller 412 to form a first stretched surface 30a. Each roller is supported by an upper frame 416 serving as a first frame, which is the housing of the upper belt unit 10.

[0058] The lower belt unit 20 includes an endless lower belt 40, which serves as a belt or a second belt; a plurality of stretching rollers, which serve as a plurality of second stretching members, for stretching the lower belt 40; and a second heating unit 400. The plurality of stretching rollers are a nip upstream guide roller 421, a nip upstream roller 422, a nip downstream roller 423, a drive roller 620, a tension roller 420, a guide roller 424, a guide roller 425, and a turn roller 426. These rollers are arranged in this order from the upstream side of the nip portion N in the rotational direction of the lower belt 40.

[0059] Additionally, a nip portion N exists between the upstream nip roller 422 and the downstream nip roller 423, and a pad 428 is provided within the nip portion N. Specifically, the upstream nip roller 422 and the downstream nip roller 423 are arranged so as to sandwich the nip portion N therebetween in the rotational direction of the lower belt 40. The pad 428, serving as a support member, abuts against the inner circumferential surface of the lower belt 40 in the nip portion N region to support the lower belt 40. In other words, the upstream nip roller 422 and the downstream nip roller 423 are provided on either side of the pad 428 in the rotational direction of the lower belt 40. Furthermore, the upstream nip roller 422 and the downstream nip roller 423 stretch the lower belt 40 to form a second stretched surface 40a. The nip portion N is formed between the first stretched surface 30a and the second stretched surface 40a of the upper belt 30. The rollers and the pad 428 define the rotational trajectory of the lower belt 40. The rollers and the pads 428 are supported by a lower frame 427 as a second frame, which is a housing of the lower belt unit 20 .

[0060] When the drive rollers 610 and 620 of the respective belt units are rotated by corresponding motors (not shown), the friction between the surface of roller 610 and the inner surface of belt 30, and between the surface of roller 620 and the inner surface of belt 40, drives the upper belt 30 and lower belt 40 to rotate. Rotation detection sensors 413a and 424a are provided on the rotational axes of guide rollers (driven rollers) 413 and 424, which are driven to rotate by the rotation of the upper belt 30 and lower belt 40. Rotation detection sensors 413a and 424a are elements composed of magnets whose magnetic force changes along the rotational direction of guide rollers 413 and 424. They detect the rotation of the upper belt 30 and lower belt 40 by detecting the changes in the north and south poles caused by rotation using Hall sensors (not shown). In this embodiment, the rotation detection sensors are elements composed of magnets, but a transmissive sensor may be used instead, which uses a physical marker having an edge in the rotational direction of the driven roller to detect changes in light blocking and light transmission.

[0061] Next, the first heating unit 300 and the second heating unit 400 of the respective belt units will be described. The first heating unit 300 is provided inside the upper belt 30 and includes heating portions 117, 127, and 137. The heating portions include heaters 110a, 110b, 120a, 120b, 130a, and 130b and reflectors (reflection plates) 115, 125, and 135 (see FIG. 1 ) as reflective members, respectively. Figure 3A ). The first heating unit 300 may be attached to and detached from the first tape unit main body 10a including the upper tape 30.

[0062] The heaters 110a, 110b, 120a, 120b, 130a, and 130b included in the heating parts 117, 127, and 137 are arranged along the width direction of the upper belt 30 intersecting the rotation direction of the upper belt 30 without contacting the upper belt 30, thereby heating the upper belt 30 by radiant heat. The reflectors 115, 125, and 135 are provided along the width direction and reflect electromagnetic waves (radiant heat) emitted from the heaters 110a, 110b, 120a, 120b, 130a, and 130b toward specific areas of the upper belt 30.

[0063] In this embodiment, the first heating unit 300 of the upper belt unit 10 is disposed inside the upper belt 30 and above the clamping portion N to heat the upper belt 30 from the inside. The first heating unit 300 includes a plurality of heating portions 117, 127, and 137. In this embodiment, the three heating portions 117, 127, and 137 are arranged side by side along the rotation direction of the upper belt 30.

[0064] The reflectors 115, 125, and 135 are provided to cover the periphery of the heaters 110a, 110b, 120a, 120b, 130a, and 130b, except for one side facing the upper belt 30. That is, the reflectors 115, 125, and 135 are formed so that the heaters 110a, 110b, 120a, 120b, 130a, and 130b are open toward the clamping portion N and both ends of the heaters 110a, 110b, 120a, 120b, 130a, and 130b in the width direction are covered. As a result, the reflectors 115, 125, and 135 effectively radiate the radiant heat of the heaters 110a, 110b, 120a, 120b, 130a, and 130b toward the clamping portion N.

[0065] That is, in the upper belt unit 10, the specific area is the area of ​​the inner peripheral surface of the upper belt 30 located within the range of the nip portion N, and the nip portion N is directly heated by the plurality of heating portions 117, 127, and 137. As a result, heat can be efficiently transferred to the sheet S passing through the nip portion N. In the present embodiment, the area within the range of the nip portion N heated by the plurality of heating portions 117, 127, and 137 is the area of ​​the inner peripheral surface (lower surface portion) of the upper belt 30, and is located upstream of the center position of the nip portion N in the conveyance direction of the sheet S passing through the nip portion N. In addition, the heating portions 117, 127, and 137 implement temperature adjustment control so that the temperature of the upper belt 30 is maintained at a predetermined temperature by controlling the input power based on the value detected by the temperature sensor 310, which detects the surface temperature of the upper belt 30.

[0066] The second heating unit 400 is provided inside the lower belt 40 and includes heating portions 147 and 157. The heating portions include heaters 140a, 140b, 150a, and 150b and reflectors (reflection plates) 145 and 155 (see FIG. 1 ) as reflecting members, respectively. Figure 3A ). The second heating unit 400 may be attached to and detached from the second belt unit main body 20a including the lower belt 40.

[0067] The heaters 140a, 140b, 150a, and 150b included in the heating parts 147 and 157 are arranged along the width direction of the lower belt 40 intersecting the rotation direction of the lower belt 40 without contacting the lower belt 40, thereby heating the lower belt 40 by radiant heat. The reflectors 145 and 155 are provided along the width direction and reflect electromagnetic waves (radiant heat) emitted from the heaters 140a, 140b, 150a, and 150b toward specific areas of the lower belt 40.

[0068] In this embodiment, the second heating unit 400 of the lower belt unit 20 is provided inside the lower belt 40 and below the clamping portion N to heat the lower belt 40 from the inside. The second heating unit 400 includes a plurality of heating portions 147 and 157. In this embodiment, the two heating portions 147 and 157 are arranged side by side along the rotation direction of the lower belt 40.

[0069] The reflectors 145 and 155 are provided to cover the periphery of the heaters 140a, 140b, 150a, and 150b, except for the side facing the lower belt 40. That is, the reflectors 145 and 155 are formed so that the heaters 140a, 140b, 150a, and 150b are open downward and both ends of the heaters 140a, 140b, 150a, and 150b in the width direction are covered. Therefore, the reflectors 145 and 155 effectively radiate the radiant heat of the heaters 140a, 140b, 150a, and 150b toward the lower portion of the lower belt 40.

[0070] That is, in the lower belt unit 20, the specific area is the area of ​​the inner circumferential surface of the lower belt 40 located outside the clamping portion N, and in this embodiment, is the lower portion of the lower belt 40. Specifically, the area heated by the multiple heating portions 147 and 157 is the area of ​​the inner circumferential surface (lower surface portion) of the lower belt 40 located between the guide roller 424 and the guide roller 425 along the rotation direction of the lower belt 40. In other words, the specific area of ​​the lower belt unit 20 is the area of ​​the surface of the lower belt 40 stretched in a substantially horizontal direction by the guide rollers 424 and 425. As described above, the lower belt unit 20 is provided with the pad 428 at a position corresponding to the clamping portion N, and unlike the upper belt unit 10, the clamping portion N cannot be directly heated. Therefore, by arranging the multiple heating portions 147 and 157 so as to face the above-mentioned area of ​​the lower belt 40, the lower belt 40 can be effectively heated in a direct manner.

[0071] The region of the lower belt 40 heated by the plurality of heating portions 147 and 157 is located on the downstream side in the rotational direction of the lower belt 40 relative to the central position between the guide roller 425 and the tension roller 420, which stretch the lower portion of the lower belt 40 in the rotational direction of the lower belt 40. Therefore, the lower belt 40 can be heated by the plurality of heating portions 147 and 157 at a position relatively close to the nip portion N, and heat can be efficiently transferred to the sheet S passing through the nip portion N. Furthermore, the heating portions 147 and 157 implement temperature adjustment control such that the temperature of the lower belt 40 is maintained at a predetermined temperature by controlling input power based on a value detected by the temperature sensor 320, which detects the surface temperature of the lower belt 40.

[0072] When the rotation detection sensors 413a and 424a detect that the belts have stopped rotating, heating of the heating portions 117, 127, 137, 147, and 157 is stopped. As a result, occurrence of local heating caused by heating while the upper and lower belts 30 and 40 are stopped can be suppressed.

[0073] Heating part

[0074] Next, we will refer to Figure 3A and Figure 3B The heating portions 117 , 127 , 137 , 147 and 157 are described in detail. Figure 3A is an enlarged sectional view showing the periphery of the heating portions 117, 127, 137, 147, and 157 of the fixing belt unit 4100, Figure 3B 110a and 110b and the reflector 115. Since the heating portions 117, 127, 137, 147, and 157 provided in the upper belt unit 10 and the lower belt unit 20 basically have a common configuration, the common configuration will be described with the heating portion 117 as a representative.

[0075] The heating portion 117 includes two heaters 110a and 110b, which have different maximum powers. The ends of the heaters 110a and 110b in the width direction are supported by a support portion (not shown). The heaters 110a and 110b in this embodiment are halogen heaters, and a power higher than the power of the heater 110b can be supplied to the heater 110a. That is, the heater 110a corresponds to a first heater, and the heater 110b corresponds to a second heater whose power is lower than the power of the heater 110a.

[0076] The heaters 110a and 110b are covered by a reflector 115 and heat the upper belt 30 directly below the heaters 110a and 110b. The reflector 115 is formed using, for example, a mirror-finished aluminum member and reflects light generated by the heaters 110a and 110b to focus the light on a specific area of ​​the upper belt 30.

[0077] like Figure 3B As shown, the shape of the reflector 115 has a portion of a parabola. The reflector 115 is a parabola with a reflector vertex 115a as a vertex. The parabolic shape formed in the direction from the reflector vertex 115a toward the upper belt 30 extends to the reflector parabola endpoint 115c, and then extends toward the upper belt 30 in a substantially vertical direction to form a reflector straight portion 115b. Note that due to component manufacturing limitations, etc., the shape of the reflector 115 can be approximated by a polygon composed of multiple line segments. The reflector straight portion 115b is preferably arranged as short as possible (can be 0), but is provided to ensure space for arranging the temperature sensor 210 described below.

[0078] The heaters 110a and 110b are arranged closer to the upper belt 30 than the reflector focus 115d, relative to the focus (reflector focus) 115d of the parabola guided by the reflector vertex 115a and the reflector parabola end point 115c, and are arranged at different heights in the vertical direction. In addition, the heater 110a, to which high power can be supplied, is arranged to be offset downward from the heater 110b.

[0079] That is, the cross-sectional shape of the reflector 115 includes a reflector vertex 115a, a reflector parabola endpoint 115c, and a reflector straight portion 115b extending from the reflector parabola endpoint 115c toward the upper belt 30. With respect to a focus 115d of an approximate parabola passing through the reflector vertex 115a and the reflector parabola endpoint 115c, the two heaters 110a and 110b are disposed at positions closer to the upper belt 30 than the focus 115d, and the two heaters 110a and 110b are at different distances from the upper belt 30.

[0080] The positions of heaters 110a and 110b can be defined as follows. Because heaters 110a and 110b meet the following requirements, heater 110b will be used as a representative example for description. First, a line drawn from heater 110b toward reflector 115 along a direction perpendicular to a vertical line extending from heater 110b to upper tape 30, which intersects the rotational direction of upper tape 30, is defined as incident light segment λ1. The point where incident light segment λ1 intersects the inner surface of reflector 115 is defined as a first intersection point P1. A line drawn from first intersection point P1, such that the angle of incidence and angle of reflection relative to incident light segment λ1 are the same, is defined as reflected light segment λ2. The point where reflected light segment λ2 intersects upper tape 30 is defined as a second intersection point P2. The point where a vertical line V extending from first intersection point P1 to upper tape 30 intersects upper tape 30 is defined as a third intersection point P3. In this case, the heater 110 b is disposed so that the second intersection point P2 is closer to the heater 110 b than the third intersection point P3 in the rotation direction of the upper belt 30 .

[0081] By arranging heaters 110a and 110b closer to upper belt 30 than reflector focal point 115d, the ratio of light generated by heaters 110a and 110b reflected by reflector 115 can be reduced, thereby improving the efficiency of heating upper belt 30. On the other hand, if heaters 110a and 110b are too close to upper belt 30, while heating efficiency can be enhanced, the intensity distribution of light irradiated onto upper belt 30 becomes more biased. In addition, by arranging two heaters 110a and 110b with a height difference in the vertical direction, the bias of the concentrated light distribution can be changed when heaters 110a and 110b are turned on individually, thereby preventing the concentrated light distribution from being localized in one place when both heaters 110a and 110b are turned on simultaneously.

[0082] In addition, in this embodiment, a temperature sensor 210 is provided. This temperature sensor is a safety sensor that detects the temperature of the area of ​​the upper belt 30 heated by the heaters 110a and 110b and senses whether the temperature is higher than or equal to a threshold value of 200°C. The temperature sensor 210 is provided near the outside of the reflector 115 because it is necessary to directly detect the temperature of the area (belt area) of the upper belt 30 heated by the heaters 110a and 110b. In other words, the temperature sensor 210, as a temperature detection unit, is provided at a location where the temperature of the upper belt 30 in a specific area can be detected from outside the reflector 115 to detect the temperature of the upper belt 30.

[0083] The threshold temperature of 200°C is set to prevent deformation of the upper belt 30 and is determined based on the material of the upper belt 30, so the temperature is not limited to this threshold. Normally, when the upper belt 30 rotates and the temperature of the heaters 110a and 110b is controlled, the temperature of the temperature sensor 210 remains below approximately 130°C and does not detect temperatures exceeding 200°C. On the other hand, if the rotation detection sensor 413a malfunctions and the upper belt 30 is driven to stop rotating, the temperature near the detection position of the temperature sensor 210 increases because local heating continues. Therefore, by arranging the temperature sensor 210, even in the event of such a malfunction, the temperature sensor 210 can directly detect the highest temperature portion of the upper belt 30. This allows the device to be stopped before the upper belt 30 is damaged by deformation, etc., thereby achieving a safer fusing unit.

[0084] The reflector 115 is subjected to the above-mentioned mirror polishing, etc. to improve the reflection efficiency, but some of the light irradiated by the heaters 110a and 110b is absorbed by the reflector 115 itself, and the temperature of the reflector 115 rises. Therefore, the temperature of the reflector 115 is likely to eventually rise to about 300°C. On the other hand, the reflector 115 heated to a high temperature also heats the ambient atmosphere, and the temperature of the temperature sensor 210 provided near the reflector 115 may also rise to about 200°C. The thermal resistance temperature of the temperature sensor 210 is about 110°C. If the temperature sensor 210 provided near the reflector 115 becomes overheated, the temperature detection accuracy of the temperature sensor 210 may deteriorate. For this reason, in this embodiment, in order to suppress the temperature increase of the temperature sensor 210, the following measures are taken.

[0085] Position of the temperature sensor relative to the heater

[0086] First, in this embodiment, Figure 3A As shown, temperature sensors 210, 220, 230, 240, and 250, serving as temperature detection units, are disposed adjacent to reflectors 115, 125, 135, 145, and 155, respectively. Specifically, temperature sensor 210 is disposed adjacent to reflector 115, temperature sensor 220 is disposed adjacent to reflector 125, temperature sensor 230 is disposed adjacent to reflector 135, temperature sensor 240 is disposed adjacent to reflector 145, and temperature sensor 250 is disposed adjacent to reflector 155. A detection window is formed in each of reflectors 115, 125, 135, 145, and 155, allowing each of temperature sensors 210, 220, 230, 240, and 250 to detect the temperature of upper belt 30 or lower belt 40 without contacting the upper belt 30 or lower belt 40. The detection window is, for example, an opening or a cutout, and is formed so that a detection surface of each temperature sensor faces the belt in an oblique direction relative to the surface of the belt.

[0087] Furthermore, temperature sensor 210 is positioned closer to heater 110b than to heater 110a, and heater 110b has a lower power than heater 110a. That is, in this embodiment, temperature sensor 210 is positioned on one of the side surfaces of reflector 115 that is closer to heater 110b. Because the input power to heater 110b is lower than the input power to heater 110a, the temperature rise of the side surface of reflector 115 that is closer to heater 110b is suppressed. Therefore, by positioning temperature sensor 210 near this side surface, the temperature rise of temperature sensor 210 can be suppressed.

[0088] In the present embodiment, a plurality of heating portions 117, 127, and 137 are provided in the upper belt unit 10. Therefore, a temperature sensor 210 as a temperature detection unit provided in the heating portion 117 and a temperature sensor 220 provided in the heating portion 127 are both provided between the reflector 115 and the reflector 125. In addition, the temperature sensors 210 and 220 are provided near the side surfaces of the reflectors 115 and 125, respectively, which are close to the low-power heaters 110b and 120b.

[0089] This will be described in detail below. First, the reflector 115, serving as the first reflective member of the heating section 117, reflects radiant heat from the heaters 110a and 110b, serving as the first and second heaters, toward a first region of the upper belt 30. A temperature sensor 210, serving as a first temperature detection unit, is positioned at a location where it can detect the temperature of the upper belt 30 in the first region. Meanwhile, the third and fourth heaters 120a and 120b, serving as the third and fourth heaters of the heating section 127, are positioned away from contact with the upper belt 30 to heat the upper belt 30 through radiant heat. The power of heater 120b is lower than that of heater 120a. Heaters 120a and 120b are positioned inside the reflector 125, serving as the second reflective member, and reflect the radiant heat from them toward a second region of the upper belt 30. A temperature sensor 220, serving as a second temperature detection unit, is positioned at a location where it can detect the temperature of the upper belt 30 in the second region from outside the reflector 125.

[0090] In this configuration, temperature sensor 210 of heating section 117 is positioned between reflectors 115 and 125 in the rotational direction of upper belt 30, closer to heater 110b than to heater 110a, and closer to heater 120b than to heater 120a. Temperature sensor 220 of heating section 127 is positioned between reflectors 115 and 125 in the rotational direction of upper belt 30, closer to heater 110b than to heater 110a, and closer to heater 120b than to heater 120a. In other words, temperature sensors 210 and 220 are positioned between reflectors 115 and 125, and in the area between reflectors 115 and 125, heaters 110b and 120b are positioned closer to temperature sensors 210 and 220, respectively, than to heaters 110a and 120a, respectively. As a result, temperature increases in temperature sensors 210 and 220 can be suppressed.

[0091] On the other hand, the temperature sensor 230, which is a temperature detection unit provided in the heating portion 137, is provided between the reflector 125 and the reflector 135. The temperature sensor 230 is provided near the side surface of the reflector 135 close to the heater 130b, which has a lower power than the heater 130a. That is, the temperature sensor 230 is also provided at a position closer to the heater 130b, which is the second heater, than to the heater 130a, which is the first heater, and the power of the heater 130b is lower than the power of the heater 130a. However, of the heaters 120a and 120b adjacent to the temperature sensor 230 in the heating portion 127, the heater 120a on the high-power side is closer to the temperature sensor 230.

[0092] As described above, in the present embodiment, in the case where three or more heating sections are provided, although not all temperature sensors can be provided close to the heaters on the low power side, at least the heaters closest to the temperature sensor 230 in the heating sections 127 and 137 are provided other than the heaters 120 a and 130 a on the high power side. That is, by using only one of the heaters close to the temperature sensor 230 in the heating sections 127 and 137 as the heater on the low power side, it is possible to suppress an increase in the temperature of the temperature sensor 230.

[0093] Furthermore, in the heating sections 147 and 157 disposed in the lower belt unit 20, temperature sensors 240 and 250 as temperature detection units are disposed in a similar relationship to the heating sections 117 and 127. That is, both the temperature sensor 240 disposed in the heating section 147 and the temperature sensor 250 disposed in the heating section 157 are disposed between the reflectors 145 and 155. Furthermore, the temperature sensors 240 and 250 are disposed near the side surfaces of the reflectors 145 and 155, which are close to the heaters 140 b and 150 b, and the power of the heaters 140 b and 150 b is smaller than that of the heaters 140 a and 150 a. As a result, an increase in the temperature of the temperature sensors 240 and 250 can be suppressed.

[0094] Blow air into the space where the temperature sensor is installed

[0095] In this embodiment, in addition to the above measures, the temperature increase of the temperature sensors 210, 220, 230, 240 and 250 is suppressed by blowing air into the space where the temperature sensors 210, 220 and 230 are provided using fans 1500, 1501 and 1502. Figure 3A 、 4 and 5. Figure 4As shown, fans 1500, 1501, and 1502 for generating airflow are connected to the front plates 38 and 48. In this embodiment, the fans 1500, 1501, and 1502 are arranged on the outer sides of the upper belt 30 and the lower belt 40 in the width direction. In addition, the fans 1500, 1501, and 1502 are only arranged on one side of the two sides of the upper belt 30 and the lower belt 40 in the width direction. The front plate 38 is the front side plate of the upper belt unit 10. The front plate 38 has a grip portion 38a so that the user can grasp the grip portion 38a to perform processing operations when the sheet S is jammed or perform equipment maintenance operations, as described below. The front plate 48 is the front side plate of the lower belt unit 20.

[0096] like Figure 3A As shown, the upper belt unit 10 and the lower belt unit 20 have flow path forming parts 161a, 161b and 161c that form flow paths 160a, 160b and 160c, and the airflow generated by the fans 1500, 1501 and 1502 flows through the flow paths. Temperature sensors 210, 220, 230, 240 and 250 are arranged in the flow paths 160a, 160b and 160c. That is, temperature sensors 210 and 220 are arranged in the flow path 160a, the temperature sensor 230 is arranged in the flow path 160b, and the temperature sensors 240 and 250 are arranged in the flow path 160c. Each of the flow path forming parts 161a, 161b and 161c can be formed by one component or can be formed by multiple components. In addition, the part of the reflector adjacent to the heating part can also serve as a flow path forming part. In this embodiment, each flow path forming part is configured as follows.

[0097] The flow path forming portion 161a forming the flow path 160a includes the front plate 38 as a first cover portion, the lower plate 162 as a second cover portion, the upper plate 163 as a third cover portion, and the rear plate 37 ( Figure 5 ). The front plate 38 covers the upstream side of the temperature sensors 210 and 220 in the direction in which the air flow flows through the flow path 160a. The lower plate 162 covers the side of the surface of the upper belt 30 irradiated by the radiant heat of the heaters 110a, 110b, 120a, and 120b relative to the temperature sensors 210 and 220 (at Figure 3A and Figure 5 The upper plate 163 covers the side opposite to the surface of the upper belt 30 relative to the temperature sensors 210 and 220 (at the bottom side). Figure 3A and Figure 5 The rear plate 37 is a rear side plate of the upper belt unit 10, and covers the downstream sides of the temperature sensors 210 and 220 in the direction in which the air flow flows through the flow path 160a.

[0098] As part of the reflectors 115 and 125, the side surfaces of the reflectors 115 and 125 on the side closest to the temperature sensors 210 and 220 constitute the flow path forming portion 161a. The reflectors 115 and 125 and the upper plate 163 are connected by connecting plates 116 and 126, respectively, and the connecting plates 116 and 126 also constitute the flow path forming portion 161a. The lower plate 162, the upper plate 163, and the connecting plates 116 and 126 are arranged along the width direction of the upper belt 30 and connected to the front plate 38 and the rear plate 37. Therefore, the flow path forming portion 161a is formed by the front plate 38, the rear plate 37, the lower plate 162, the upper plate 163, the reflectors 115 and 125, and the connecting plates 116 and 126, and the space surrounded by them is the flow path 160a. Note that the lower plate 162, the upper plate 163, and the connecting plates 116 and 126 do not need to be connected to the rear plate 37.

[0099] Similarly, the flow path forming portion 161b forming the flow path 160b includes the front plate 38 as a first cover portion, the lower plate 164 as a second cover portion, the upper plate 163 as a third cover portion, and the rear plate 37 ( Figure 5 ). The front plate 38 covers the upstream side of the temperature sensor 230 in the direction of the air flow through the flow path 160b. The lower plate 164 covers the side of the surface of the upper belt 30 irradiated by the radiant heat of the heaters 130a and 130b relative to the temperature sensor 230 (at Figure 3A and Figure 5 The upper plate 163 is in communication with the flow path forming portion 161a and covers the side opposite to the surface of the upper belt 30 relative to the temperature sensor 230 (at the bottom of the upper belt 30). Figure 3A and Figure 5 The rear plate 37 covers the downstream side of the temperature sensor 230 in the direction in which the air flow flows through the flow path 160b.

[0100] As part of the reflectors 125 and 135, the side surfaces of the reflectors 125 and 135 near the temperature sensor 230 constitute the flow path forming portion 161b. The reflector 135 and the upper plate 163 are connected by the connecting plate 136, and the connecting plate 136 also constitutes the flow path forming portion 161b. Note that the above-mentioned connecting plate 126 also constitutes the flow path forming portion 161b. The lower plate 164, the upper plate 163, and the connecting plate 136 are arranged along the width direction of the upper belt 30 and are connected to the front plate 38 and the rear plate 37. Therefore, the flow path forming portion 161b is formed by the front plate 38, the rear plate 37, the lower plate 164, the upper plate 163, the reflectors 125 and 135, and the connecting plates 126 and 136, and the space surrounded by them is the flow path 160b. Note that the connecting plate 136 does not have to be connected to the rear plate 37. In addition, the connection plate 126 may be omitted, and the flow path 160 a and the flow path 160 b may communicate with each other between the reflector 125 and the upper plate 163 .

[0101] Similarly, the flow path forming portion 161c forming the flow path 160c includes a front plate 48 as a first cover portion, a lower plate 165 as a second cover portion, an upper plate 166 as a third cover portion, and a rear plate (not shown) as a fourth cover portion. The front plate 48 is a front side plate of the lower belt unit 20 and covers the upstream side of the temperature sensors 240 and 250 in the direction in which the air flow flows through the flow path 160c. The lower plate 165 covers the side (at the bottom) of the surface of the lower belt 40 that is irradiated by the radiant heat of the heaters 140a, 140b, 150a, and 150b, which is close to the temperature sensors 240 and 250. Figure 3A and Figure 5 The upper plate 166 covers the side opposite to the surface of the lower belt 40 relative to the temperature sensors 240 and 250 (at the bottom of the upper plate 166). Figure 3A and Figure 5 The rear plate is a rear side plate of the lower belt unit 20, and covers the downstream side of the temperature sensors 240 and 250 in the direction in which the air flow flows through the flow path 160c.

[0102] As part of the reflectors 145 and 155, the side surfaces of the reflectors 145 and 155 on the side close to the temperature sensors 240 and 250 constitute the flow path forming portion 161c. The connecting plates 146 and 156 connect the reflectors 145 and 155 and the upper plate 166, respectively, and the connecting plates 146 and 156 also constitute the flow path forming portion 161c. The lower plate 165, the upper plate 166, and the connecting plates 146 and 156 are arranged along the width direction of the lower belt 40 and are connected to the front plate 48 and the rear plate. Therefore, the front plate 48, the rear plate, the lower plate 165, the upper plate 166, the reflectors 145 and 155, and the connecting plates 146 and 156 form the flow path forming portion 161c, and the space surrounded by them is the flow path 160c. Note that the lower plate 165, the upper plate 166, and the connecting plates 146 and 156 do not have to be connected to the rear plate.

[0103] Fans 1500, 1501, and 1502 are connected to the front panels 38 and 48. Fan 1500 is connected to the flow path forming portion 161a to blow air to the flow path 160a. Fan 1501 is connected to the flow path forming portion 161b to blow air to the flow path 160b. Fan 1502 is connected to the flow path forming portion 161c to blow air to the flow path 160c.

[0104] The first flow path inlet unit 167a, which serves as a second duct portion, is connected to the upstream side (front side) of the flow path forming portion 161a in the direction of airflow, that is, the front plate 38. The first flow path inlet unit 167a is connected to the second flow path inlet unit 168a, which serves as a first duct portion provided in the upper frame 416. The fan 1500 is connected to the second flow path inlet unit 168a. The second flow path inlet unit 168a is connected to the fan 1500 to allow the airflow generated by the fan 1500 to flow into it. The first flow path inlet unit 167a is connected to the front plate 38 and the second flow path inlet unit 168a to deliver the airflow generated by the fan 1550 to the inside of the flow path forming portion 161a.

[0105] Therefore, if Figure 5 As shown, the airflow generated by fan 1500 is sent to the inside of flow path forming portion 161a via second flow path inlet unit 168a and first flow path inlet unit 167a, and flows through flow path 160a, as indicated by arrow 1500a. On the other hand, flow path outlet 169b is provided on the downstream side (rear side) of flow path forming portion 161a in the direction of airflow, that is, on rear plate 37, so that the air that has passed through flow path 160a can be discharged to the outside of upper belt unit 10. In addition, at least a portion of each of temperature sensors 210 and 220 is provided on the inside of flow path forming portion 161a.

[0106] Similarly, the first flow path inlet unit 167b as the second duct part is connected to the upstream side (front side) of the flow path forming part 161b in the air flow direction, i.e., the front plate 38. The first flow path inlet unit 167b is connected to the second flow path inlet unit 168b as the first duct part provided in the upper frame 416. The fan 1501 is connected to the second flow path inlet unit 168b. The structure in which the airflow flows from the fan 1501 to the inside of the flow path forming part 161b is the same as the structure in which the airflow flows from the fan 1500 to the inside of the flow path forming part 161a. In the upper belt unit 10, the flow path inlet structure connected to each of the fans 1500 and 1501 includes two components. This is because the first flow path inlet units 167a and 167b and the second flow path inlet units 168a and 168b are separated from each other when maintaining the equipment, etc., as described in detail below.

[0107] On the other hand, in the lower belt unit 20, the fan 1502 is connected directly or via a duct to the upstream side (front side) of the flow path forming portion 161b in the air flow direction, that is, the front plate 48. The flow path inlet structure connected to the fan 1502 in the lower belt unit 20 may also include two members, similar to the flow path inlet structure connected to each of the fans 1500 and 1501 in the upper belt unit 10.

[0108] The temperature sensor 210 for detecting the temperature of the upper belt 30 heated by the heaters 110a and 110b is located between the reflector 115 and the reflector 125 and is provided at a position close to the fan 1500 described below relative to the widthwise center 2200 of the upper belt 30. In other words, the temperature sensor 210 is provided upstream of the widthwise center 2200 of the upper belt 30 in the direction in which the fan 1500 causes the airflow to flow. Figure 5 The area (detection area) α of the upper belt 30 detected by the temperature sensor 210 is shown. In this embodiment, the detection area α is also located upstream of the widthwise center 2200 of the upper belt 30 in the direction of airflow caused by the fan 1500 described below. Note that this also applies to the other temperature sensors 220, 230, 240, and 250.

[0109] As described above, temperature sensors 210, 220, 230, 240, and 250 are disposed in flow paths 160a, 160b, and 160c. Fans 1500, 1501, and 1502 draw air and send it into flow path forming portions 161a, 161b, and 161c, respectively, to form air flows in flow paths 160a, 160b, and 160c, respectively. The formed air flows then cool temperature sensors 210, 220, 230, 240, and 250. Consequently, increases in the temperatures of temperature sensors 210, 220, 230, 240, and 250 can be suppressed.

[0110] Furthermore, when a plurality of heating elements are arranged side by side in the rotational direction of the upper belt 30 or the lower belt 40 as in this embodiment, heat is supplied to the temperature sensor from the adjacent reflector, and the temperature of the temperature sensor rises. Therefore, as described above, by arranging two temperature sensors 210 and 220 or two temperature sensors 240 and 250 in one flow path 160a or one flow path 160c, the temperature sensors can be effectively cooled using a small number of fans.

[0111] Note that although the temperature sensors are configured as described above to minimize the number of fans used and reduce the cross-sectional size of the device, the arrangement of the temperature sensors and the number of fans and flow paths are not limited to the above. For example, a flow path may be formed for each temperature sensor. For example, the heating portion 147 or the heating portion 157 of the temperature sensors 240 and 250, or both, may be provided on the opposite side to that described above (relative to the side of the heating portion 147). Figure 3A The position shown is located outside the reflector on the opposite left or right side), and a fan and flow path can be added. In addition, the heating portion 117 or the heating portion 137 of the temperature sensors 210 and 230 or both can be set on the opposite side and a fan and flow path can be added.

[0112] As described above, by appropriately positioning the temperature sensor relative to the heater and blowing air into the space where the temperature sensor is located, for example, the amount of heat received by reflector 115 from heaters 110a and 110b is reduced, and the air flow cools temperature sensor 210, thereby enabling the temperature of temperature sensor 210 to be suppressed to approximately 95°C. As a result, temperature sensor 210 can detect temperature with high accuracy. This also applies to other temperature sensors 220, 230, 240, and 250.

[0113] In the above description, fans 1500, 1501, and 1502 are fans located upstream of flow paths 160a, 160b, and 160c in the direction of airflow, supplying air to flow paths 160a, 160b, and 160c. However, at least one of fans 1500, 1501, and 1502 may be a fan located downstream of the corresponding flow path 160a, 160b, or 160c in the direction of airflow, exhausting air from the flow path. Furthermore, at least one of the flow paths may be provided with both a fan for supplying air and a fan for exhausting air.

[0114] About jam handling and maintenance

[0115] Next, we will refer to Figures 6A to 6C Jam handling and maintenance in the fixing module 4000 according to this embodiment are described. Figure 1 ) and the conveying timing deviates from the predetermined conveying timing, the device detects a jam. In this case, the sheet S remaining on the sheet conveying path 4100a is automatically discharged to the clear tray, but when the remaining sheet cannot be discharged to the clear tray, the user needs to remove the remaining sheet. The sheet S is conveyed while being clamped by the clamping portion N between the upper belt unit 10 and the lower belt unit 20. However, if the sheet S remains in the clamping portion N when the jam occurs, the user opens the clamping portion N and removes the remaining sheet.

[0116] Therefore, one of the upper belt unit 10 and the lower belt unit 20 can move relative to the other belt unit between a clamping position, in which the upper belt 30 and the lower belt 40 form a clamping portion N, and a separation position, in which the upper belt 30 and the lower belt 40 are further apart than in the clamping position. In this embodiment, the upper belt unit 10 can move relative to the lower belt unit 20 between the clamping position and the separation position. This will be described in detail below.

[0117] like Figures 6A to 6CAs shown, the fixing module 4000 includes an upper door unit 43, which serves as a shell or a first shell that can be opened along the upward direction U. The upper belt unit 10 of the fixing belt unit 4100 can be accommodated in the upper door unit 43, and the upper door unit 43 can be opened integrally with the upper belt unit 10 along the upward direction U. The upper door unit 43 is pivotally connected to the device main body 44 as the second shell by a support shaft 45, and the support shaft is arranged on the side of the device main body 44 facing the backward direction B. The support shaft 45 as the second pivot support part is arranged on the rear side of the device main body 44 in the width direction (front and back direction), and is arranged along the sheet conveying direction (left and right direction). The upper door unit 43 is arranged to be pivotable around the support shaft 45 relative to the device main body 44.

[0118] The upper door unit 43 has a handle 431 on one side facing the front direction F of the apparatus body 44, and is pivoted open by pulling up the handle 431 in the upward direction U. The upper door unit 43 can be opened in the closed position ( Figure 6A ) and open position ( Figure 6B ). The closed position is a clamping position in which the clamping portion N is formed by the upper belt 30 and the lower belt 40, and the open position is a separation position in which the upper belt 30 and the lower belt 40 are further spaced apart from each other than in the clamping position. In this embodiment, the upper door unit 43 is composed of a top plate or a side plate and functions as an upper cover for the device body 44.

[0119] When a jam occurs, the user pulls up the handle 431 of the upper door unit 43 to open the upper door unit 43 upward to the separated position, and can remove the sheet S remaining in the device body 44 from the front surface of the device. In this embodiment, in order to improve the user's operability in opening and closing the upper door unit 43, a gas spring (not shown) is provided so that the gas spring biases the upper door unit 43 toward the open position to maintain the upper door unit 43 in the open position. When the device is in use, the upper door unit 43 is maintained in the closed position by its own weight, and the clamping portion N is formed as described above.

[0120] The upper belt unit 10 is supported by the support shaft 46 in a manner pivotable between a first position and a second position relative to the upper door unit 43. Figure 6C As shown in FIG. 1 , a support shaft 46 as a pivot support portion or a first pivot support portion is provided on the rear side of the upper door unit 43 in the width direction (front-rear direction) and is provided along the sheet conveying direction (left-right direction). In addition, the first position (upper storage position) is a position where the upper belt unit 10 is accommodated in the upper door unit 43 ( Figure 6B The second position (maintenance position) is a position where at least a portion of the upper belt unit 10 is more exposed to the outside of the upper door unit 43 than at the first position ( Figure 6C ). At the above-mentioned separation position, the upper belt unit 10 can be moved from the first position to the second position.

[0121] When the device is in use, the upper belt unit 10 is fixed to the front of the upper door unit 43 by a retaining member such as a screw (not shown) to be maintained in the upper storage position. When maintenance of the upper belt unit 10 is performed, while the upper door unit 43 is in the open position, the upper belt unit 10 is moved downward from the upper door unit 43 around the support shaft 46, for example, by grasping the grip portion 38a provided on the front plate 38 to the maintenance position. The maintenance position is a state that allows the upper belt 30 to be attached to / detached from the upper belt unit 10, for example.

[0122] As described above, in the upper belt unit 10, the flow path inlet structure connected to each of the fans 1500 and 1501 includes two components. That is, the flow path inlet structure includes the first flow path inlet unit 167a or 167b and the second flow path inlet unit 168a or 168b. Here, if all the flow path inlet structures connected to the fans 1500 and 1501 are fixed to the upper frame 416 of the upper belt unit 10, it is necessary to move the upper belt unit 10 including the fans 1500 and 1501 downward ( Figure 6C ), which may result in an increase in equipment size or a decrease in the maintainability of the equipment.

[0123] To this end, in this embodiment, Figure 5 As shown, the fans 1500 and 1501 and the second flow path inlet units 168a and 168b are fixed to the upper frame 416, and the second flow path inlet units 168a and 168b and the first flow path inlet units 167a and 167b are configured to be separable by the connecting portion 169 during maintenance. That is, the connecting portion 169 can connect the second flow path inlet units 168a and 168b and the first flow path inlet units 167a and 167b at the upper storage position, and separate the second flow path inlet units 168a and 168b and the first flow path inlet units 167a and 167b when the upper belt unit 10 is moved from the upper storage position to the maintenance position. As a result, during maintenance, the upper belt unit 10 can be moved downward from the upper storage position while the fans 1500 and 1501 are lifted in the upper door unit 43.

[0124] In this embodiment, as the first stretched surface 30a ( Figure 2As the direction (upper and lower directions) orthogonal to the sheet conveying direction shown in FIG. 1 gradually approaches the first stretched surface 30a, the connecting surface 169a between the second flow path inlet units 168a and 168b and the first flow path inlet units 167a and 167b is inclined in a direction toward the upstream side of the direction in which the air flows through the flow paths 160a and 160b. That is, in Figure 5 In the embodiment of the present invention, the connecting surface 169a of the connecting portion 169 is inclined forward as it extends downward. By forming the connecting surface 169a as an inclined surface in this manner, even if the positions of the second flow path inlet units 168a and 168b and the first flow path inlet units 167a and 167b are slightly offset during connection, this offset in the inclined direction can be absorbed, and the connection can be stably implemented. Note that a sealing member or the like can be provided on the connecting surface 169a to enhance sealability.

[0125] In this embodiment, since the lower belt unit 20 does not need to be disassembled for maintenance as described above, the fan 1502 is directly attached to the front plate 48 of the lower belt unit 20 .

[0126] Fans 1500 and 1501 are positioned obliquely above the intake ports of second flow path inlet units 168a and 168b, creating a downward, slanted air flow. Some of the air blown by fans 1500 and 1501 leaks out of flow path forming portions 161a and 161b (e.g., the front ends of reflectors 115 and 125) and strikes the lower portion and side surfaces of front plate 38, as well as grip portion 38a. This reduces the temperature of grip portion 38a, which is used to handle a sheet S jam or perform equipment maintenance.

[0127] Structure for controlling the heater of the upper belt unit

[0128] Next, we will refer to Figure 7 A configuration for controlling the heaters 110 a , 110 b , 120 a , 120 b , 130 a , and 130 b included in the upper tape unit 10 is described. Figure 71 is a hardware block diagram of the upper belt unit 10 according to the present embodiment. The configuration for controlling the upper belt unit 10 includes a central processing unit (CPU) 1100 as a control unit, a relay 1200, a power supply 1300 as a power supply unit, a motor 1400 as a drive unit, field effect transistors (FETs) 111, 121, and 131 as voltage adjustment units, excessive temperature rise detection hardware (HW) 211, 221, and 231 as a threshold determination unit, heaters 110a, 110b, 120a, 120b, 130a, and 130b, protective temperature sensors 210, 220, and 230, a temperature sensor 310 for temperature adjustment, and a rotation detection sensor 413a.

[0129] The CPU 1100 controls the driving of the motor 1400. The motor 1400 drives the upper belt 30 to rotate and, in this embodiment, drives the driving roller 610 via a transmission path (not shown). The motor 1400 starts or stops driving according to the instruction of the CPU 1100.

[0130] The CPU 1100 drives the FETs 111, 121, and 131 by controlling the FETs 111, 121, and 131 to turn on and / or off the power supplied to the heaters 110a, 110b, 120a, 120b, 130a, and 130b. Power is supplied to each of the heaters 110a, 110b, 120a, 120b, 130a, and 130b from the power supply 1300. The FETs 111, 121, and 131 are provided between the power supply 1300 and the heaters 110a, 110b, 120a, 120b, 130a, and 130b, and adjust the voltage applied to the corresponding heaters by the power supply 1300 based on the control of the CPU 1100.

[0131] The CPU 1100 adjusts the power supplied to the heaters 110a, 110b, 120a, 120b, 130a, and 130b to perform temperature regulation by feeding back temperature information from the temperature sensor 310. That is, the CPU 1100 implements temperature regulation control of the upper belt 30 by driving the FETs 111, 121, and 131 based on the temperature (detection result) detected by the temperature sensor 310.

[0132] Excessive temperature rise detection HWs 211, 221, and 231 can switch FETs 111, 121, and 131 between an on-state, in which power source 1300 energizes heaters 110a, 110b, 120a, 120b, 130a, and 130b, and an off-state, in which power source 1300 and heaters 110a, 110b, 120a, 120b, 130a, and 130b are off. When the temperature detected by temperature sensors 210, 220, and 230 becomes equal to or higher than a threshold value, excessive temperature rise detection HWs 211, 221, and 231 switch from the on-state to the off-state. That is, when the temperature of temperature sensors 210, 220, and 230 is detected to be equal to or higher than the threshold value, excessive temperature rise detection HWs 211, 221, and 231 stop driving FETs 111, 121, and 131. The excessive temperature rise threshold is a temperature set according to the material of the belt to prevent deformation, and is set to 200° C. in this embodiment, but is not limited thereto.

[0133] When any one of the excessive temperature rise detection HWs 211, 221, and 231 detects a temperature of 200°C or higher, control of the corresponding one of the FETs 111, 121, and 131 is stopped. For example, when the excessive temperature rise detection HW 211 detects the temperature of the temperature sensor 210, control of the FET 111 is stopped, but the hardware circuit does not stop control of the other FETs 121 and 131. The CPU 1100 detects a shutdown signal from the excessive temperature rise detection HW 211 through software and stops the FETs 121 and 131. Although the CPU stops the FETs in the above description, the FETs may also be stopped by the hardware circuit.

[0134] The rotation detection sensor 413a detects when the upper belt 30 stops rotating, causing the heating of the heaters 110a, 110b, 120a, 120b, 130a, and 130b to stop by disconnecting the relay 1200. An operation unit 1401, serving as a notification unit, is connected to the CPU 1100. The operation unit 1401 is used to operate the inkjet recording apparatus 1 and is, for example, an operation panel having a touch panel capable of inputting and displaying information. In addition to the touch panel in the operation unit 1401, physical buttons such as a start button may also be provided. In this embodiment, the display unit included in the operation unit 1401 has a function of notifying the user of various types of information, such as error messages. Examples of error messages include a stop caused by excessive temperature rise of the upper belt 30. Furthermore, the CPU 1100 can notify an external terminal connected to the inkjet recording apparatus 1, such as a personal computer, of various types of information, such as error messages from the fixing belt unit 4100. In this case, the CPU 1100 functions as a notification unit.

[0135] Upper belt unit fixing control

[0136] Next, we will refer to Figure 8 The following describes the fusing control of the upper belt unit 10. When the fusing control is started, the CPU 1100 controls the motor 1400 of the upper belt 30 to rotate the upper belt 30. Furthermore, the CPU 1100 turns on the relay 1200 (S101). The CPU 1100 causes the rotation detection sensor 413a to determine whether the upper belt 30 is rotating (S102). The CPU 1100 proceeds to S103 when it determines that the upper belt 30 is rotating (Yes in S102), and proceeds to S105 when it determines that the upper belt 30 is not rotating (No in S102).

[0137] If yes in S102, the CPU 1100 controls the temperature of the heaters 110a, 110b, 120a, 120b, 130a, and 130b according to the temperature value read from the temperature sensor 310 (S103). In this embodiment, the CPU 1100 controls the temperature of the heaters 110a, 110b, 120a, 120b, 130a, and 130b by controlling the temperature of the FETs 111, 121, and 131 using the duty width of the PWM control signal.

[0138] Next, the CPU 1100 determines whether the temperature value read from each of the temperature sensors 210, 220, and 230 is equal to or higher than the threshold temperature (S104). When the value of at least one of the temperature sensors 210, 220, and 230 is equal to or higher than the threshold temperature (Yes in S104), the CPU 1100 proceeds to S105. On the other hand, when the temperature value read from the temperature sensor 210, 220, or 230 is lower than the threshold temperature (No in S104), the CPU 1100 proceeds to S102. In S105, the CPU 1100 turns off the FETs 111, 121, and 131 to stop the heaters 110a, 110b, 120a, 120b, 130a, and 130b.

[0139] If the rotation detection sensor 413a malfunctions and the upper belt 30 is driven to stop rotating, even if the upper belt 30 is stopped, it may be determined in S102 that the upper belt 30 is rotating. In this case, the CPU 1100 proceeds to S103. In S103, the CPU 1100 controls the temperatures of the heaters 110a, 110b, 120a, 120b, 130a, and 130b based on the temperature value read from the temperature sensor 310. Since the upper belt 30 is not rotating, only the temperature of the portion of the upper belt 30 facing the heating sections 117, 127, and 137 rises, while the temperature value read by the temperature sensor 310 remains substantially unchanged.

[0140] As a result, in S104, the temperature value read from the temperature sensor 210, 220, or 230 becomes equal to or higher than the threshold temperature, and the CPU 1100 proceeds to S105. In S105, the CPU 1100 turns off the FETs 111, 121, and 131 to stop the heaters 110a, 110b, 120a, 120b, 130a, and 130b. Therefore, the driving of the heaters can be stopped before the temperature of the upper belt 30 reaches an excessively high temperature exceeding the threshold.

[0141] Temperature sensor structure

[0142] Next, we will refer to Figures 9A to 9C The configurations of the temperature sensors 210, 220, and 230 will be described. Since the temperature sensors 210, 220, and 230 have the same configuration, the temperature sensor 210 will be described as a representative. Figure 9A 2 are external shape diagrams of the temperature sensor 210 , wherein the upper diagram is a plan view and the lower diagram is a side view. Figure 9B and Figure 9C 2 is a diagram for explaining the viewing angle of the temperature sensor 210 .

[0143] Sensor module 3801 is a package with a built-in sensor module, mounted on substrate 3800, and has a detection window 3802 at its upper portion. Temperature sensor 210 absorbs infrared rays emitted from the measurement target through detection window 3802 and converts the absorbed infrared energy into an electrical signal, thereby achieving non-contact temperature detection. Furthermore, temperature sensor 210 can output the results detected by sensor module 3801 through connector 3806. In this embodiment, among the components mounted on substrate 3800, sensor module 3801, which actually detects the temperature, is located at the very end of the substrate.

[0144] Figure 9B 3804 is a diagram schematically illustrating the viewing angle of temperature sensor 210. Detection window 3802 not only allows infrared rays to enter sensor module 3801 but also acts as a lens. That is, temperature sensor 210 has a fixed viewing angle 3804 and detects the temperature of measurement target 3803 within viewing angle 3804 in a non-contact manner.

[0145] Figure 9CThis figure is used to explain the definition of angle of view 3804. The temperature measurement accuracy when measurement target 3803 is located on center line 3805 of angle of view 3804 is set to 100%. Next, measurement target 3803 is moved from center line 3805 without changing the distance from temperature sensor 210. The angle θ formed by measurement target 3803 and center line 3805 when the temperature measurement accuracy drops to 50% due to the movement is defined as angle of view 3804. Note that the value of 50% in this embodiment is merely an example and is not limited to 50%.

[0146] Heater structure

[0147] Next, we will refer to Figure 10A and Figure 10B The configuration of heaters 110a, 110b, 120a, 120b, 130a, and 130b will be described. In this embodiment, the two heaters in each heating section differ only in power, but are identical in terms of light distribution. Therefore, heater 110a will be described below as a representative example. Figure 10A The figure is a schematic diagram of the heater 110a and upper belt 30, viewed from upstream toward downstream along the sheet conveying direction. The figure shows the radiation intensity of the heater 110a at locations along the belt width. The belt width direction is perpendicular to the sheet conveying direction and is represented as the x-axis in the figure. The sheet conveying direction is represented as the y-axis, and the height direction is represented as the z-axis. In this embodiment, the heater 110a distributes light so that the radiation intensity in the belt width end regions 2501 and 2503 is higher than that in the belt width center region 2502, thereby suppressing uneven heating across the belt width.

[0148] Figure 10BThis graph shows the relationship between the heating time and the temperature of the upper belt 30 when the upper belt 30 is continuously heated by the heater. The horizontal axis represents time, and the vertical axis represents the temperature of the upper belt 30. Graph 2504 shows the temperature increase in the end regions 2501 and 2503 in the belt width direction, while graph 2505 shows the temperature increase in the center region 2502 in the belt width direction. Because light is distributed so that the radiation intensity in the end regions 2501 and 2503 is higher than that in the center region 2502, the temperature increases at a greater angle in graph 2504. The dashed line 2506 shown in the figure indicates the limit temperature set to prevent belt deformation, which is determined based on the belt material. Therefore, the threshold for detecting excessive temperature rise is set so that the belt does not exceed the limit temperature indicated by dashed line 2506. Note that heaters 110a, 110b, 120a, 120b, 130a, and 130b have the same configuration, but may have different configurations. For example, one of the two heaters in each heating section can distribute light as described above, while the other heater can distribute light with a flat radiant intensity across the width of the strip. Alternatively, both heaters can distribute light with a flat radiant intensity. Alternatively, the radiant intensity of the two heaters can be flat, while the lengths can be different.

[0149] Temperature distribution

[0150] Next, the ambient temperature distribution in the flow path where the temperature sensors 210 , 220 , and 230 are located will be described. As described above, the temperature sensors 210 and 220 are disposed between the reflectors 115 and 125 , and the temperature sensor 230 is disposed between the reflectors 125 and 135 . Figure 11 The ambient temperature distribution between the reflector 115 and the reflector 125 is shown. Figure 5 As described above, since air flows in the direction indicated by arrow 1500a between reflectors 115 and 125 from fan 1500, external air is blown to a location near fan 1500. As a result, the ambient temperature near fan 1500 decreases. Each time the air moves in the direction indicated by arrow 1500a, the heat transferred from heaters 110a and 110b and heaters 120a and 120b via reflectors 115 and 125 warms the air, causing the ambient temperature to increase at locations farther from fan 1500.

[0151] Therefore, in this embodiment, as described above, temperature sensor 210 is positioned upstream of the widthwise center 2200 of upper belt 30, in the direction of airflow caused by fan 1500. As a result, low-temperature air can strike temperature sensor 210, effectively cooling it. This also applies to other temperature sensors. As described above, in this embodiment, in a system that directly heats the belt using a reflector and heater, and in a configuration that detects the belt temperature using a non-contact temperature sensor, the placement of the temperature sensor in the airflow path prevents the temperature sensor from overheating. As a result, when the temperature sensor is used as a sensor to detect excessive temperature rise due to a decrease in its detection accuracy, it is possible to suppress degradation of product quality and equipment safety.

[0152] Second embodiment

[0153] Will refer to Figures 12 to 14 The second embodiment will now be described. In the first embodiment described above, a single temperature sensor was provided for each heater to detect the temperature directly below each heater. In this embodiment, however, temperature detection is performed by multiple temperature sensors for each heater. Since other configurations and operations are similar to those of the first embodiment, the same reference numerals will be used to represent the same configurations, and their description and explanation will be omitted or simplified. The following will primarily describe the differences from the first embodiment.

[0154] Figure 12 1 is an enlarged cross-sectional view showing a portion of the upper belt unit 10A and a portion of the lower belt unit 20A of the fixing belt unit 4100A in the inkjet recording apparatus according to the present embodiment. Figure 2) is that each heater has three temperature sensors (temperature sensors 210a, 210b, and 210c, 220a, 220b, and 220c, 230a, 230b, and 230c, 240a, 240b, and 240c, or 250a, 250b, and 250c) that detect the belt temperature directly below each heater (the area exposed to radiant heat from the heater). That is, in this embodiment, a plurality of temperature sensors (temperature sensors 210a, 210b, and 210c) are provided along the width direction to detect the temperature of the upper belt 30 directly below the heaters 110a and 110b. Similarly, a plurality of temperature sensors (temperature sensors 220a, 220b, and 220c, 230a, 230b, and 230c, 240a, 240b, and 240c, or 250a, 250b, and 250c) are arranged along the width direction to detect the temperature of the upper belt 30 or the lower belt 40 immediately below each of the other heaters. The other configuration is the same as that of the first embodiment.

[0155] Structure for controlling the heater of the upper belt unit

[0156] Figure 13 1 is a hardware block diagram of the upper belt unit 10A according to the present embodiment. Three temperature sensors are provided for each heater to detect the belt temperature directly below each heater. In addition, with respect to the block diagram of the first embodiment ( Figure 7 ), the excessive temperature rise detection HWs 211, 221, and 231 change, so that the power supply to the heater can be controlled based on the inputs from the three temperature sensors.

[0157] Placement of temperature sensors and fans

[0158] Figure 14 1 is a diagram showing the arrangement of the temperature sensors 210a, 210b, and 210c and the arrangement of the fan 1500 according to the present embodiment. Since the same applies to the other temperature sensors 220a, 220b, and 220c, 230a, 230b, and 230c, 240a, 240b, and 240c, and 250a, 250b, and 250c, the arrangement of the temperature sensors 210a, 210b, and 210c and the arrangement of the fan 1500 will be described below as representatives.

[0159] This embodiment differs from the first embodiment in that the number of temperature sensors detecting the belt temperature directly below each heater has increased. As in the first embodiment, temperature sensors 210a, 210b, and 210c are positioned close to fan 1500 in the front-to-back direction (widthwise) to suppress temperature increases in temperature sensors 210a, 210b, and 210c. Specifically, in this embodiment, all temperature sensors 210a, 210b, and 210c are positioned closer to fan 1500 than to the widthwise center 2200 of upper belt 30.

[0160] However, considering the length of the substrate on which the temperature sensors 210a, 210b, and 210c are arranged, when the plurality of temperature sensors 210a, 210b, and 210c are arranged side by side in the width direction, it may be difficult to arrange all of the temperature sensors 210a, 210b, and 210c closer to the fan 1500 than to the widthwise center 2200 of the upper belt 30. In this case, the plurality of temperature sensors 210a, 210b, and 210c may be disposed more upstream of the widthwise center of the upper belt 30 than downstream of the widthwise center of the upper belt 30 in the direction in which the airflow flows through the flow path 160a.

[0161] When the corresponding areas of the upper belt 30 that can be detected by the temperature sensors 210a, 210b, and 210c are the detection areas αa, αb, and αc, the plurality of temperature sensors 210a, 210b, and 210c can be arranged along the direction in which the airflow flows through the flow path 160a, so that the area upstream of the center in the width direction of the upper belt 30 in the total area of ​​the detection areas αa, αb, and αc of the plurality of temperature sensors 210a, 210b, and 210c is larger than the area downstream of the center in the width direction of the upper belt 30 in the total area. The detection area is a reference area. Figures 9A to 9C The area of ​​the upper band 30 within the range of viewing angle 3804 is described.

[0162] Furthermore, if there is a temperature distribution along the width of the upper belt 30, once the temperature at the hottest point in the temperature distribution is detected, a threshold value that does not exceed the upper belt 30's limit temperature can be directly set. If the hottest point in the temperature distribution is difficult to detect, the heater can be stopped before the belt's limit temperature is reached by setting the detection threshold value to a value different from the temperature at the temperature sensor location so as not to exceed the belt's limit temperature. Difficulty in detecting the hottest point in the temperature distribution occurs, for example, when multiple temperature sensors are arranged along the width, as in this embodiment. However, due to the narrow spacing between the temperature sensors, it is physically difficult to detect the hottest point in the temperature distribution.

[0163] In this embodiment, by arranging multiple temperature sensors, the heater can be safely stopped even if a defect such as a malfunction occurs in one temperature sensor. In this configuration according to this embodiment, fan 1500 is a fan arranged upstream of flow path 160a in the direction indicated by arrow 1500a to supply air into flow path 160a. However, the fan can be a fan that discharges air downstream in the direction indicated by arrow 1500a, or can include both a fan for supplying air and a fan for discharging air. In the case where the fan for discharging air is arranged downstream in the direction indicated by arrow 1500a, the same effect can be achieved by arranging the temperature sensor away from the fan.

[0164] Third embodiment

[0165] Will refer to Figure 15 The third embodiment will now be described. In the first embodiment described above, a configuration has been described in which the heating unit, including heating portions 117, 127, and 137, is disposed inside the upper belt 30. In this embodiment, on the other hand, the heating unit is disposed outside the upper belt 30. Since other configurations and operations are similar to those of the first embodiment described above, the same reference numerals will be used to denote the same configurations, and their description and explanation will be omitted or simplified. Below, the differences from the first embodiment will be primarily described.

[0166] Figure 15 10B is an enlarged sectional view showing a portion of the upper belt unit 10B according to the present embodiment. Since the configuration and operation of the lower belt unit according to the present embodiment are similar to those of the upper belt unit 10B, the description of the lower belt unit will be omitted.

[0167] In this embodiment, the heating unit including the heating portions 117, 127, and 137 is disposed outside the upper belt 30. By arranging the heating unit including the heating portions 117, 127, and 137 outside the upper belt 30, space inside the upper belt unit 10 can be secured, and the degree of freedom in arranging various components can be increased. On the other hand, disadvantages are that the size of the apparatus increases and the clamping portion N cannot be directly heated.

[0168] The components (heaters, reflectors, flow paths, and temperature sensors) that constitute the heating portions 117, 127, and 137 are the same as those of the first embodiment. Even if the heating portions 117, 127, and 137 are disposed outside the upper belt 30, the same effects as those of the first embodiment can be achieved with respect to the temperature rise of the temperature sensors 210, 220, and 230. In the configuration according to this embodiment, as in the second embodiment, a plurality of temperature sensors can be disposed along the width direction.

[0169] Fourth embodiment

[0170] Will refer to Figures 16 to 17B Describe the fourth embodiment. In the above-mentioned first embodiment, such a configuration has been described in which the temperature sensors 210, 220 and 230 are arranged in the flow paths 160a and 160b through which the air flow flows. On the other hand, in the present embodiment, the temperature sensors 210, 220 and 230 are arranged on the outside of the widthwise end portions of the heater. Since other configurations and operations are similar to those in the above-mentioned first embodiment, the same configurations are represented by the same reference numerals, and their descriptions and explanations will be omitted or simplified, and the differences from the first embodiment will be mainly described below. In the following description, the case where the present embodiment is applied to the upper belt unit 10 will be described, but the present embodiment can be similarly applied to the lower belt unit 20.

[0171] In the first embodiment described above, fans 1500 and 1501 are used to create air flow between reflectors 115 and 125, and between reflectors 125 and 135, where temperature sensors 210, 220, and 230 are arranged. Temperature sensors 210, 220, and 230 are arranged near fans 1500 and 1501, allowing the temperature sensors to stably detect the temperature of the upper belt 30. In this embodiment, the temperature sensors can stably detect the temperature of the upper belt 30 without creating the air flow. In this embodiment, since no air flow is created, flow path forming portions 161a and 161b as described in the first embodiment are not provided.

[0172] Figure 16 The arrangement of the upper belt 30, heaters 110, 120, and 130, and temperature sensors 210, 220, and 230 when observing the upper belt unit 10C according to this embodiment from above is shown. The heaters 110, 120, and 130 correspond to the heaters 110a and 110b, 120a and 120b, and 130a and 130b in the first embodiment, but for ease of explanation, the multiple heaters are shown as a single heater. In this embodiment, since the temperature sensors 210, 220, and 230 are not arranged between the reflectors 115 and 125, and between the reflectors 125 and 135, the arrangement relationship between the heaters 110a and 110b, 120a and 120b, and 130a and 130b can be different from that in the first embodiment, and, for example, a high-power heater and a low-power heater can be freely arranged compared to the first embodiment. In this embodiment, one heater can be provided in each heating section.

[0173] The temperature sensors 210, 220, and 230 are respectively provided to detect the temperature directly below the heaters 110, 120, and 130. That is, the temperature sensors 210, 220, and 230 are provided at positions outside the widthwise ends of the heaters 110, 120, and 130 to detect the temperature of the upper belt 30. At these positions, the temperature of the upper belt 30 in a specific area can be detected from outside a reflector (not shown).

[0174] Figure 17A 2 is a diagram showing the positional relationship between the upper belt 30 and the temperature sensor 210 when viewed from the upstream side to the downstream side along the sheet conveying direction. The temperature sensor 210, which is provided outside the end portion of the upper belt 30, is provided so as to obliquely detect the end portion region 2501 of the upper belt 30. The temperature sensor 210 is provided so that the heater 110 does not enter the detection region 2101 to directly observe the heated area directly below the heater 110. The detection region 2101 is a reference region. Figures 9A to 9C The area of ​​the upper band 30 within the range of viewing angle 3804 is described.

[0175] When temperature sensor 210 is arranged in this manner, the depression angle of temperature sensor 210 relative to upper belt 30 increases. As the depression angle of temperature sensor 210 increases, detection region 2101 encompasses a wider belt area. Therefore, it is necessary to use a sensor with a narrow detection region 2101 as temperature sensor 210, or to provide a margin for detecting excessive temperature rises, given the wide range of belt temperatures to be detected.

[0176] Figure 17B 2201 is a graph showing the relationship between the heating time and the belt temperature at each position in the width direction of the upper belt 30 when the heater 110 continuously heats the upper belt 30. The horizontal axis represents time and the vertical axis represents belt temperature. The graph 2201 shows the end position 2102 ( Figure 16 ) increases. The graph 2202 shows the central position 2103 ( Figure 16 ) temperature rise. The difference in the temperature rise slope between the graph 2201 and the graph 2202 is the difference in the heater light distribution ( Figure 16 (right figure in the figure).

[0177] In this embodiment, temperature sensor 210 detects the temperature at end position 2102, which is the region with the highest rate of temperature increase. Therefore, limit temperature 2006 of upper belt 30 and excessive temperature rise detection threshold temperature 2204 are the same temperature. Note that the relationship between limit temperature and excessive temperature rise detection threshold temperature in this embodiment is merely an example and is not limiting. For example, excessive temperature rise detection threshold temperature 2204 may have a safety margin and be set to a value lower than limit temperature 2206. The above-described configuration of temperature sensor 210 is similarly applicable to the other temperature sensors 220 and 230.

[0178] Fifth embodiment

[0179] Will refer to Figure 18 Describe the fifth embodiment. In the above-mentioned first embodiment, such a structure has been described in which the temperature sensors 210, 220 and 230 are arranged in the flow paths 160a and 160b, and the air flow flows through the flow paths in the upper belt 30. On the other hand, in this embodiment, the temperature sensors 210, 220 and 230 are arranged on the side of the upper belt 30 opposite to the side where the heater and the reflector are provided. Since other structures and operations are similar to those in the above-mentioned first embodiment, the same figure marks are used to represent the same structures, and their descriptions and explanations are omitted or simplified, and hereinafter, the differences from the first embodiment will be mainly described. In the following description, the case where the present embodiment is applied to the upper belt unit 10 will be described, but the present embodiment is similarly applicable to the lower belt unit 20.

[0180] In this embodiment, similar to the fourth embodiment described above, the temperature sensor can stably detect the temperature of the upper belt 30 without forming an air flow. In this embodiment, since no air flow is formed, the flow path forming portions 161a and 161b described in the first embodiment are not provided.

[0181] Figure 18 is an enlarged sectional view showing a portion of the upper belt unit 10D according to the present embodiment. Since the construction and action in the lower belt unit according to the present embodiment are similar to those in the upper belt unit 10D, the description of the lower belt unit will be omitted. In the present embodiment, similar to the fourth embodiment, since the temperature sensors 210, 220 and 230 are not provided between the reflector 115 and the reflector 125 and between the reflector 125 and the reflector 135, the arrangement relationship between the heaters 110a and 110b, 120a and 120b, and 130a and 130b is different from that in the first embodiment, and, for example, a high-power heater and a low-power heater can be freely provided compared to the first embodiment. For example, it is possible as Figure 18 Heater arrangement shown.

[0182] In this embodiment, the heating unit including the heating portions 117, 127, and 137 heats the inner surface of the upper belt 30 on the side (upper side) opposite to the clamping portion N. Temperature sensors 210, 220, and 230 are provided on the outer surface of the upper belt 130 at positions facing the heaters 110a and 110b, 120a and 120b, and 130a and 130b of the heating portions 117, 127, and 137, respectively, via the upper belt 30. That is, the temperature sensors 210, 220, and 230 are provided on the side of the upper belt 30 opposite to the side on which the heaters 110a, 110b, 120a, 120b, 130a, and 130b and the reflectors 115, 125, and 135 are provided, and detect the temperature in a specific area on the back side of the upper belt 30.

[0183] In this embodiment, the heating unit including heating sections 117, 127, and 137 is configured to heat the inner surface of the upper belt 30 rather than the nip section N, and temperature sensors 210, 220, and 230 are configured to detect the temperature of the outer surface of the upper belt 30. As a result, since the temperature sensors 210, 220, and 230 are not positioned near the reflectors 115, 125, and 135, increases in the temperatures of the temperature sensors 210, 220, and 230 can be suppressed. On the other hand, disadvantages include an increase in the size of the device and the inability to directly heat the nip section N. In the configuration according to this embodiment, as in the first embodiment, multiple temperature sensors are provided along the width direction.

[0184] Other embodiments

[0185] In each of the above embodiments, the present invention has been described as being applied to a fixing unit (fixing belt unit) of an inkjet recording apparatus, but the application of the present invention is not limited thereto. For example, the present invention can also be applied to a fixing unit of an electrophotographic image forming apparatus using toner or the like, and the same effects as those of each of the embodiments can be obtained.

[0186] In each of the above embodiments, the temperature sensors 210, 220, 230, 240, and 250 are used as sensors that detect excessive temperature rise of the belt and stop supplying power to the heater. These temperature sensors 210, 220, 230, 240, and 250 can be used to control the temperature of the heater.

[0187] One or more embodiments of the present invention may also be implemented as follows: a computer of a system or device, the computer reading and executing computer-executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more fully referred to as a "non-transitory computer-readable storage medium") to implement one or more of the functions of the one or more embodiments described above and / or including one or more circuits (e.g., application-specific integrated circuits (ASICs)) for implementing one or more of the functions of the one or more embodiments described above; a method implemented by a computer of a system or device, for example, by reading and executing computer-executable instructions from a storage medium to implement one or more of the functions of the one or more embodiments described above and / or controlling one or more circuits to implement one or more of the functions of the one or more embodiments described above. The computer may include one or more processors (e.g., central processing units (CPUs), microprocessing units (MPUs)) and may include a network composed of separate computers or separate processors to read and execute computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or storage medium. The storage medium may include, for example, a hard disk, random access memory (RAM), read-only memory (ROM), memory of a distributed computing system, an optical disk (such as a compact disk (CD)), a digital versatile disk (DVD), or a Blu-ray disk (BD). TM ), one or more of flash memory devices, memory cards, etc.

[0188] Other embodiments

[0189] The embodiments of the present invention can also be implemented by the following method, that is, software (including computer program products of computer programs / instructions) that perform the functions of the above-mentioned embodiments is provided to a system or device through a network or various storage media, and a computer (central processing unit (CPU), microprocessing unit (MPU)) of the system or device reads and executes the computer program / instructions.

[0190] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments and that the scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A fixing unit, comprising: an endless belt configured to heat a sheet having an ink image formed thereon to fuse the image to the sheet; a heater provided inside the belt without contacting the belt and configured to heat the belt by emitting electromagnetic waves; a reflective member configured to reflect electromagnetic waves emitted by the heater toward a region of the belt, the heater being disposed inside the reflective member; a temperature detection unit provided outside the reflective member and configured to detect a temperature of the area; a fan configured to generate an airflow; and a flow path forming portion provided inside the belt and forming a flow path through which the airflow generated from the fan flows, Wherein, the temperature detection unit is provided inside the flow path forming portion.

2. The fixing unit according to claim 1, wherein The temperature detection unit is provided adjacent to the reflecting member in the rotation direction of the belt.

3. The fixing unit according to claim 1 or 2, wherein The heater is a first heater, The fixing unit further includes a second heater that is provided inside the reflecting member together with the first heater in a manner not to contact the belt and is configured to heat the belt by emitting electromagnetic waves, the power of the second heater being smaller than the power of the first heater. The reflecting member is configured to reflect electromagnetic waves emitted from the first heater and the second heater toward the region of the belt, and The temperature detection unit is provided at a position closer to the second heater than to the first heater.

4. The fixing unit according to claim 3, wherein the reflecting member is a first reflecting member configured to reflect electromagnetic waves emitted from the first heater and the second heater toward a first region of the belt, The temperature detection unit is provided at a position capable of detecting the temperature of the belt in the first area, The fixing unit further includes: a third heater disposed in a non-contact manner with the belt and configured to heat the belt by emitting electromagnetic waves; a fourth heater disposed in a manner not to contact the belt and configured to heat the belt by emitting electromagnetic waves, wherein power of the fourth heater is smaller than power of the third heater; as well as a second reflecting member configured to reflect electromagnetic waves emitted from the third heater and the fourth heater, the third heater and the fourth heater being provided inside the second reflecting member, toward the second region of the belt; and The temperature detection unit is provided between the first and second reflecting members in the rotational direction of the belt, the position being closer to the second heater than the first heater and closer to the fourth heater than the third heater.

5. The fixing unit according to claim 4, wherein The temperature detection unit is a first temperature detection unit, The fixing unit further includes a second temperature detecting unit that is provided at a position where the temperature of the belt in the second area can be detected from outside the second reflecting member and is configured to detect the temperature of the second area, and The second temperature detecting unit is provided at the position between the first reflecting member and the second reflecting member in the rotation direction of the belt, the position being closer to the second heater than the first heater and closer to the fourth heater than the third heater.

6. The fixing unit according to claim 1 or 2, wherein The heater and the reflecting member are arranged along a width direction of the belt, the width direction intersecting with a rotation direction of the belt, and The temperature detection unit is one of a plurality of temperature detection units provided along the width direction.

7. The fixing unit according to claim 1 or 2, wherein The fan is provided outside the belt in a width direction of the belt intersecting with a rotation direction of the belt.

8. The fixing unit according to claim 6, wherein The flow path is formed along the width direction, and In the case where the area of ​​the belt whose temperature can be detected by the multiple temperature detection units is defined as the detection area, the multiple temperature detection units are arranged in the direction of the airflow flowing through the flow path, so that in the total area of ​​the detection areas of the multiple temperature detection units, the area upstream of the center of the belt in the width direction is larger than the area downstream of the center of the belt in the width direction.

9. The fixing unit according to claim 7, wherein The fan is provided on only one of both sides of the belt in the width direction.

10. The fixing unit according to claim 1 or 2, wherein In a case where a line drawn from the heater toward the reflective member in a direction orthogonal to a vertical line drawn from the heater to the belt and orthogonal to a width direction of the belt intersecting with a rotational direction of the belt is defined as an incident light segment, a point where the incident light segment intersects the inner surface of the reflective member is defined as a first intersection point, a line drawn from the first intersection point so that an incident angle and a reflection angle with respect to the incident light segment are the same is defined as a reflected light segment, a point where the reflected light segment intersects the belt is defined as a second intersection point, and a point where a vertical line drawn from the first intersection point to the belt intersects the belt is defined as a third intersection point, The heater is disposed so that the second intersection point is closer to the heater than the third intersection point in the rotational direction of the belt.

11. The fixing unit according to claim 1 or 2, wherein A portion of the reflecting member constitutes the flow path forming portion.

12. The fixing unit according to claim 1 or 2, further comprising: a power supply unit configured to supply power to the heater; and A threshold value determination unit is configured to stop the power supply of the power supply unit when the temperature detected by the temperature detection unit is higher than or equal to a threshold value.

13. A fixing unit, comprising: an endless belt configured to heat a sheet having an ink image formed thereon to fuse the image to the sheet; a first heater and a second heater, the first heater and the second heater being provided inside the belt in a manner not to be in contact with the belt and configured to heat the belt by emitting electromagnetic waves; a first reflecting member configured to reflect electromagnetic waves emitted by the first heater toward a first region of the belt, the first heater being disposed inside the first reflecting member; a second reflecting member configured to reflect electromagnetic waves emitted by the second heater toward a second region of the belt, the second heater being disposed inside the second reflecting member; a temperature detection unit provided outside the first reflecting member and the second reflecting member and configured to detect a temperature of one of the first area and the second area; and a fan configured to generate an air flow, wherein the airflow generated from the fan flows along a portion of the first reflecting member and a portion of the second reflecting member in a width direction of the belt intersecting with a rotational direction of the belt, and The temperature detection unit is provided on a flow path through which the air flow generated by the fan flows.

14. The fixing unit according to claim 13, wherein The temperature detection unit is provided adjacent to the reflecting member in the rotation direction of the belt.

15. The fixing unit according to claim 13 or 14, wherein The heater is a first heater, The fixing unit further includes a second heater that is provided inside the reflecting member together with the first heater in a manner not to contact the belt and is configured to heat the belt by emitting electromagnetic waves, the power of the second heater being smaller than the power of the first heater. The reflecting member is configured to reflect electromagnetic waves emitted from the first heater and the second heater toward the region of the belt, and The temperature detection unit is provided at a position closer to the second heater than to the first heater.

16. The fixing unit according to claim 13 or 14, wherein The fan is provided outside the belt in a width direction of the belt.

17. The fixing unit according to claim 13 or 14, wherein The flow path is formed along the width direction, The temperature detection unit is one of a plurality of temperature detection units arranged along the width direction, and In the case where the area of ​​the belt whose temperature can be detected by the multiple temperature detection units is defined as the detection area, the multiple temperature detection units are arranged in the direction of the airflow flowing through the flow path, so that in the total area of ​​the detection areas of the multiple temperature detection units, the area upstream of the center in the width direction of the belt is larger than the area downstream of the center in the width direction of the belt.

18. The fixing unit according to claim 13 or 14, further comprising: a power supply unit configured to supply power to the heater; and A threshold value determination unit is configured to stop the power supply of the power supply unit when the temperature detected by the temperature detection unit is higher than or equal to a threshold value.

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