JP2014052462A - Image heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image heating device in which even when a generation position of temperature rise at paper non-passing parts is changed due to recording material size change or the like, the temperature rise at paper non-passing parts can be alleviated swiftly without causing unnecessary power consumption or local temperature fall.SOLUTION: A end fan ducts 604, 605 guide ventilation of end fans 601, 602 to a heat equalizing roller 13 while shielding a pressurizing roller 2 from ventilation from the end fans 601, 602. A control part 150 controls a contact/separating mechanism 105 so that when after a continuous heating treatment to the recording material is started in a state that the heat equalizing roller 13 is separated from the pressurizing roller 2, a temperature at an end portion of the pressurizing roller 2 exceeds a prescribed temperature, the heat equalizing roller 13 is brought into press-contact with the pressurizing roller 2. When, after the heat equalizing roller 13 is brought into press-contact with the pressurizing roller 2, a temperature at an end portion of the pressurizing roller 2 exceeds a prescribed temperature, the end fans 602, 602 are actuated.

Description

  The present invention relates to an image heating apparatus that can cool both ends of a press-contact rotator by using a blower to suppress temperature rise of the non-sheet passing portion, and more specifically, efficiently suppress temperature rise of the non-sheet passing portion with low power consumption. The present invention relates to an arrangement structure of a blower that can be used.

  The toner image formed on the image carrier is transferred to a recording material directly or via an intermediate transfer member, and the recording material onto which the toner image has been transferred is heated and pressed at a nip portion of a fixing device which is an example of an image heating device. An image forming apparatus for fixing the toner image to a recording material is widely used. In the image heating apparatus, a heating rotator (belt member or roller member) and a pressure rotator (belt member or roller member) are pressed to form a nip portion of a recording material. When a recording material is continuously heat-treated with an image heating device, the temperature rises at both ends in the longitudinal direction of the nip portion that is heated but not subjected to heat removal from the recording material. (Patent Document 1).

  Patent Document 1 discloses an image heating apparatus that heats a heating rotator using an induction heating apparatus. Then, by controlling the movable magnetic core and the movable magnetic flux shielding plate that shields the magnetic flux, the heating member outside the length region in the direction perpendicular to the conveyance direction of the recording material where the temperature rise of the non-sheet passing portion occurs Incident magnetic flux is reduced.

  Patent Document 2 shows an image heating apparatus in which four fans are arranged along a pressure contact rotating body. Then, when the temperature rise of the non-sheet passing portion that exceeds the predetermined temperature occurs, the two outer fans among the four fans are operated to directly air-cool both ends of the pressure contact rotating body, and the nip portion is not allowed to pass. The heat of the paper section is removed. Prior to the heat treatment of the recording material, the inner two of the four fans are operated to directly air-cool the central portion of the pressure contact rotator, and the radius distribution in the rotation axis direction of the pressure contact rotator. (Temperature expansion) is adjusted.

  In Patent Document 4, a heat equalizing roller is pressed against a pressure rotating body to enhance heat transfer in the rotation axis direction, thereby leveling the temperature distribution in the rotation axis direction of the pressure rotating body and increasing the temperature of the non-sheet passing portion. A suppressed image heating device is shown.

JP2012-128312A JP 2010-181468 A JP 2002-365963 A JP 2011-175047 A

  As shown in Patent Document 1, even when the heated region in the rotation axis direction of the heating rotator can be precisely controlled, uniform heating is performed up to both ends of the width of the recording material (direction perpendicular to the conveying direction). Therefore, it is necessary to apply heat to the outside of the width of the recording material. This is because there is a possibility that the required temperature may not be reached at both ends of the width of the recording material in the heat treatment of the first and second sheets in which no temperature increase in the non-sheet passing portion has occurred.

  However, if the heating is applied to the outside of the width of the recording material, the non-sheet passing portion temperature rises outside the width of the recording material after the start of the heat treatment. As the recording material conveyance speed is increased in order to increase productivity, a steep non-sheet passing portion temperature rise occurs. As the thickness of the heating rotator is reduced in order to accelerate the rise in temperature, heat transfer in the direction of the rotation axis is impaired and a steep non-sheet passing portion temperature rise occurs.

  Therefore, as disclosed in Patent Document 2, it has been proposed that a fan is disposed at the end of the press-contact rotating body to air-cool the non-sheet-passing portion. However, in this case, there is a possibility that a part of the air blown to the end portion of the pressure contact rotator wraps around the center portion of the pressure contact rotator and air cooling reaches the center portion of the pressure contact rotator. In this case, the heating rotator is further heated so as to compensate for the temperature drop in the nip portion at the center, which may cause unnecessary power consumption and increase the temperature rise of the non-sheet passing portion.

  Therefore, as shown in Patent Document 3, it has been proposed to shield the end portion and the center portion of the press-contact rotating body with a fixed partition plate so that the air blown to the end portion does not enter the center portion. However, the fixed partition plate cannot cope with the temperature rise of the non-sheet passing portion in which the position generated according to the size of the recording material moves. When a recording material having a width wider than that of the partition plate is heat-treated, the pressure contact rotating body causes a large temperature drop on the outside of the partition plate.

  The present invention provides an image heating apparatus capable of quickly mitigating non-sheet-passing portion temperature rise without causing unnecessary power consumption or local temperature drop even if the occurrence position of non-sheet-passing portion temperature rise changes. The purpose is to provide.

The image heating apparatus of the present invention includes a heating rotator that heats a recording material, a pressure rotator that presses against the heating rotator to form a nip portion of the recording material, and a pressure rotator that presses against the pressure rotator. A heat transfer rotating body that transfers heat so as to equalize a temperature distribution in the rotation axis direction of the body, and an end blowing unit that blows air to the end of the heat transfer rotating body in the rotation axis direction.
Is.

  The image heating apparatus according to the present invention is necessary for keeping the temperature of the central portion constant because the excessive heat amount of the non-sheet-passing portion temperature increase contributes to the heating of the central portion of the pressure rotating body through the heat transfer rotating body. The heating power of the heating rotator is reduced. At the same time, the heat removal by the end blowing means is also expanded and averaged in the direction of the rotation axis of the pressure rotator through the heat transfer rotator, so that a smooth temperature distribution can be formed on the pressure rotator.

  Therefore, even if the position where the non-sheet passing portion temperature rise occurs changes, the non-sheet passing portion temperature rise can be quickly mitigated without causing unnecessary power consumption or local temperature drop.

1 is an explanatory diagram of a configuration of an image forming apparatus. FIG. 3 is an explanatory diagram of a cross-sectional configuration perpendicular to the rotation axis of the fixing device. 3 is an explanatory diagram of a cross-sectional structure of a fixing belt. FIG. FIG. 4 is an explanatory diagram of a vertical cross-sectional configuration parallel to the rotation axis direction of the fixing device. It is explanatory drawing of arrangement | positioning of an outer side magnetic body core. It is explanatory drawing of operation | movement of a center fan and a center fan duct. It is a perspective view of a center fan and a center fan duct. It is explanatory drawing of the cooling effect of the pressure roller by a center fan. It is a block diagram of control of a fixing device. It is a time chart of control of a central fan. It is a flowchart of control of a center fan. It is explanatory drawing of operation | movement of an edge part fan and an edge part fan duct. It is a perspective view of an end fan and an end fan duct. It is a time chart of control of an end fan. It is a flowchart of control of an edge part fan.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention replaces a part or all of the configuration of the embodiment with the alternative configuration as long as the blow of the end fan cools the end portion and the central portion of the pressure contact roller through the heat equalizing roller at the same time. Other embodiments can also be implemented.

  Accordingly, the heating rotator and the pressure rotator are not limited to belt members, and at least one of them may be a roller member. The image heating apparatus may be an optional unit combined with a single image heating processing apparatus or an image forming system, in addition to those incorporated in the image forming apparatus. As long as the image carried on the recording material is heated, the image heating device may be an image surface gloss processing device or a recording material decurling device in addition to the fixing device.

  The image forming apparatus can be implemented regardless of the full color / monochrome, one drum type / tandem type, recording material conveyance method / intermediate transfer method, type of image carrier, charging method, exposure method, transfer method, and fixing method. In the present embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention includes a printer, various printing machines, a copier, a fax machine, a composite machine, in addition to necessary equipment, equipment, and a housing structure. It can be implemented in various applications such as a machine.

(1) Example of Image Forming Apparatus FIG. 1 is an explanatory diagram of the configuration of the image forming apparatus. As shown in FIG. 1, the image forming apparatus E is a tandem intermediate transfer type full-color printer in which yellow, magenta, cyan, and black image forming portions PY, PM, PC, and PK are arranged along an intermediate transfer belt 26. is there.

  In the image forming unit PY, a yellow toner image is formed on the photosensitive drum 21 (Y) and transferred to the intermediate transfer belt 26. In the image forming unit PM, a magenta toner image is formed on the photosensitive drum 21 (M) and transferred to the intermediate transfer belt 26. In the image forming units PC and PK, a cyan toner image and a black toner image are formed on the photosensitive drums 21 (C and K), respectively, and transferred to the intermediate transfer belt 26.

  The intermediate transfer belt 26 is composed of an endless resin belt, is stretched around a driving roller 27, a secondary transfer counter roller 28, and a tension roller 29, and is driven by the driving roller 27. The recording material P is taken out from the recording material cassette 31 one by one by the paper feed roller 32 and waits at the registration roller 33. The recording material P is fed to the secondary transfer portion T2 by the registration roller 33, and the toner image is transferred from the intermediate transfer belt 26 in the process of being conveyed through the secondary transfer portion T2. The recording material P to which the four color toner images have been transferred is conveyed to the fixing device 200, and is heated and pressurized by the fixing device 200 to fix the toner image on the surface. The recording material on which the image is fixed is discharged to the external tray 37 through the discharge conveyance path 36.

  The image forming units PY, PM, PC, and PK are different except that the toner colors used in the developing devices 23 (Y), 23 (M), 23 (C), and 23 (K) are different from yellow, magenta, cyan, and black. The configuration is substantially the same. In the following, the image forming unit PY will be described, and redundant description regarding the image forming units PM, PC, and PK will be omitted.

  In the image forming unit PY, a charging roller 22, an exposure device 25, a developing device 23, a transfer roller 30, and a drum cleaning device 24 are arranged around the photosensitive drum 21. The charging roller 22 charges the surface of the photosensitive drum 21 to a uniform potential. The exposure device 25 scans the laser beam and writes an electrostatic image of the image on the photosensitive drum 21. The developing device 23 supplies toner to the electrostatic image and develops the toner image on the photosensitive drum 21. The transfer roller 30 is applied with a DC voltage to transfer the toner image on the photosensitive drum 21 to the intermediate transfer belt 26.

<Example 1>
(2) Image Heating Device Example FIG. 2 is an explanatory diagram of a cross-sectional configuration perpendicular to the rotation axis of the fixing device. FIG. 3 is an explanatory diagram of a cross-sectional structure of the fixing belt. FIG. 4 is an explanatory diagram of a vertical cross-sectional configuration parallel to the rotation axis direction of the fixing device. FIG. 5 is an explanatory view of the arrangement of the outer magnetic core. In the following description, regarding the fixing device and the members constituting the fixing device, the longitudinal direction is a direction orthogonal to the recording material conveyance direction on the surface of the recording material, and the length is a dimension in the longitudinal direction. The short direction is a direction parallel to the recording material conveyance direction on the surface of the recording material, and the width is a dimension in the short direction.

  As shown in FIG. 2, during the heat treatment of the recording material, the control unit 150 operates the motor 104 to rotationally drive the pressure roller 2. The fixing belt 1 is driven to rotate by the pressure roller 2 and is driven to rotate at a circumferential speed substantially the same as the conveyance speed of the recording material P carrying the unfixed toner image T. Here, the surface rotation speed of the fixing belt 1 is set to 300 mm / sec, and an A4 size laterally fed full-color image can be fixed on 80 plain papers per minute. In the case of A4 size vertical feeding, fixing processing can be performed on 58 sheets of plain paper.

  During the heat treatment of the recording material, the recording material P having the unfixed toner image T is introduced into the nip portion N in a state where the temperature of the fixing belt 1 is adjusted to a predetermined fixing temperature. The toner image carrying surface of the recording material P is brought into close contact with the outer peripheral surface of the fixing belt 1 and is nipped and conveyed together with the fixing belt 1 through the nip portion N. As a result, heat is applied to the fixing belt 1, and the unfixed toner image T is fixed to the surface of the recording material P by receiving pressure from the nip portion N. The recording material P that has passed through the nip N is separated from the fixing belt 1 by the curvature, and is conveyed to the outside from the fixing device 200.

  The fixing belt 1 is a cylindrical endless belt having a longitudinal length of 390 mm, an inner diameter of 30 mm, and a thickness of 360 μm. The fixing belt 1 has a metal layer for enabling induction heating.

  As shown in FIG. 3, the base layer 1 a is a nickel metal layer manufactured by an electroforming method and has a thickness of 40 μm. In addition to nickel, an iron alloy, copper, silver, or the like can be appropriately selected for the metal layer. The metal layer may be formed by laminating a metal on the resin base layer. The thickness of the metal layer needs to be adjusted according to the frequency of the high-frequency current flowing through the exciting coil 6 and the permeability / conductivity of the metal layer. The thickness of the metal layer is preferably set between about 5 and 200 μm.

  The elastic layer 1b is a heat-resistant silicon rubber layer provided on the outer periphery of the base layer 1a. The silicon rubber layer has a hardness of JIS-A 20 degrees and a thermal conductivity of 0.8 W / mK. The thickness of the silicon rubber layer is preferably set within a range of 100 to 1000 μm. Here, in consideration of reducing the heat capacity of the fixing belt 1 to shorten the warm-up time and obtaining a suitable fixed image when fixing a color image, the thickness of the silicon rubber layer is set to 300 μm.

  The surface release layer 1c is a fluororesin layer (for example, PFA or PTFE) provided on the outer periphery of the elastic layer 1b, and has a thickness of 30 μm here. The resin layer 1d is a slippery layer such as a fluororesin or polyimide provided on the inner surface side of the base layer 1a. Here, the resin layer 1d is polyimide having a thickness of 20 μm. The resin layer 1d preferably has a thickness of 10 to 50 μm in order to reduce sliding friction between the inner surface of the fixing belt and the temperature sensor TH1.

  The pressure roller 2 is disposed in contact with the outer periphery of the fixing belt 1. The pressure roller 2 has a cylindrical shape with an outer diameter of 30 mm and a length in the longitudinal direction of 350 mm, and forms a nip portion N with the fixing belt 1. The hardness at the center in the longitudinal direction of the pressure roller 2 is ASK-C70 ° C. The pressure roller 2 is provided with an elastic layer 2b of a silicon rubber layer on the peripheral surface of an iron alloy cored bar 2a, and the outer peripheral surface of the elastic layer 2b is covered with a release layer 2c of a fluororesin layer (for example, PFA or PTFE). ing. The cored bar 2a has a diameter of 20 mm in the center in the longitudinal direction so that the pressure distribution in the longitudinal direction of the nip portion N between the fixing belt 1 and the pressure roller 2 is uniform even when the pressing member 3 is bent during pressing. The diameter of both ends is 19 mm. The elastic layer 2b has a thickness of 5 mm, and the release layer 2c has a thickness of 30 μm. In order to make the conveyance speed at both ends of the recording material P faster than that at the central portion and to prevent the occurrence of paper wrinkles, the width of the nip portion N in the rotational direction is the width at both ends in the longitudinal direction when the nip pressure is 600N. About 9 mm and about 8.5 mm in the center.

  As shown in FIG. 4, the support side plate 12 supports the fixing flange 10 in a non-rotating manner and supports the pressure roller 2 in a rotatable manner. The fixing flange 10 is fixed to the support side plate 12 and regulates the position of the fixing belt 1 in the longitudinal direction. The fixing flange 10 is a right and left restricting member that restricts the longitudinal movement and the circumferential shape of the fixing belt 1. Since the base layer of the fixing belt 1 is made of metal, a fixing flange 10 that simply receives the end of the fixing belt 1 as a means for restricting the shift in the width direction even when the fixing belt 1 is in a rotating state. Is sufficient.

  Both ends of the stay 4 are disposed through the fixing flange 10. The stay 4 applies pressure evenly to the pressure applying member 3 along the longitudinal direction of the nip portion. The stay 4 is made of iron because it needs rigidity. As shown in FIG. 2, since the stay 4 is close to the exciting coil 6, in order to shield the magnetic field generated by the exciting coil 6 and avoid induction heating, a magnetic shielding core is formed on the upper surface of the stay 4 over the longitudinal direction. 5 is arranged. The magnetic shielding core 5 is a magnetic shielding member that is provided on the coil side of the stay 4 and prevents temperature rise due to induction heating.

  The pressure applying member 3 is held by a metal stay 4 and presses the nip portion N by applying a pressing force to the pressure roller 2 via the fixing belt 1. The pressure applying member 3 forms a fixing nip portion N by applying a pressing force between the fixing belt 1 and the pressure roller. The pressure applying member 3 is a heat resistant resin.

  The stay pressurizing springs 9 b are contracted between the both ends of the stay 4 and the stay spring receiving member 9 a on the apparatus chassis side, thereby applying a pressing force to the stay 4. As a result, the lower surface of the fixing flange 10 and the upper surface of the pressure roller 2 are pressed against each other with the fixing belt 1 interposed therebetween, so that a nip portion N having a predetermined width is formed. The stay pressurizing spring 9 b applies a pressing force to both ends of the stay 4 to form a nip portion N having a predetermined width between the fixing belt 1 supported by the pressure applying member 3 and the pressure roller 2.

  By rotating a cam (not shown), the urging force of the stay pressurizing spring 9b against the stay 4 can be released, and the pressurization of the nip portion N can be released. When the fixing device 200 is stopped, the pressure of the nip portion N is released to prevent the elastic layer of the pressure roller 2 and the fixing belt 1 from being permanently deformed.

  As shown in FIG. 2, the induction heating device 100 is a heating source for induction heating the fixing belt 1. The induction heating device 100 is disposed on the upper surface side of the outer peripheral surface of the fixing belt 1 so as to face the fixing belt 1 with a predetermined gap (gap). The fixing belt 1 and the exciting coil 6 of the induction heating device 100 are kept electrically insulated by a 0.5 mm mold. The distance between the mold surface and the fixing belt surface is 1.0 mm, and the distance between the fixing belt 1 and the exciting coil 6 is constant at 1.5 mm.

  As shown in FIG. 5, the exciting coil 6 uses, for example, a litz wire as an electric wire, and is wound so that the electric wire is horizontally long and has a bottom shape and faces a part of the peripheral surface and side surface of the fixing belt 1. The outer magnetic core 7 a covers the excitation coil 6 so that the magnetic field generated by the excitation coil 6 does not substantially leak to other than the metal layer (conductive layer) of the fixing belt 1. The outer magnetic core 7a is arranged side by side in a direction perpendicular to the recording material conveyance direction, and is configured to surround the winding center portion and the periphery of the exciting coil 6. The outer magnetic core 7a is arranged for increasing the efficiency of the magnetic circuit of the exciting coil 6 and for magnetic shielding, and efficiently guides the alternating magnetic flux generated from the exciting coil 6 to the fixing belt 1. The outer magnetic core 7a may be made of a material having high permeability and low residual magnetic flux density such as ferrite. The mold member 7c supports the exciting coil 6 and the outer magnetic core 7a with an electrically insulating resin.

  As shown in FIG. 2, the temperature sensor TH <b> 1 that is an example of the center temperature detection unit detects the temperature of the center of the fixing belt 1 in the rotation axis direction. An induction heating apparatus 100 that is an example of a heating unit heats the fixing belt 1. A temperature control circuit 102, which is an example of temperature control means, controls the induction heating device 100 based on the output of the temperature sensor TH1 so that the temperature of the central portion in the rotation axis direction of the fixing belt 1 maintains a predetermined temperature.

  The temperature sensor TH1 is a temperature detection element such as a thermistor, for example, and abuts against the inner surface of the central portion in the longitudinal direction of the fixing belt 1 to detect the temperature of the portion of the fixing belt 1 that becomes a sheet passing area. Since the temperature sensor TH1 is attached to the pressure applying member 3 via an elastic support member, even if a positional variation such as the contact surface of the fixing belt 1 undulates, a good contact state follows the positional variation. To maintain.

The temperature information detected by the temperature sensor TH1 is fed back to the temperature control circuit 102. The temperature control circuit 102 controls the power supply device 101 (excitation circuit) so that the temperature detected by the temperature sensor TH1 is maintained at a predetermined target temperature (fixing temperature). As shown in Table 1, the target temperature for temperature adjustment of the fixing belt 1 is changed according to the temperature of the environment in which the image forming apparatus E is placed and the type of recording material. In Table 1, the low temperature environment is 15 ° C. or lower, and the high temperature environment is 30 ° C. or higher. Thin paper is cut paper having a weight per unit area of 52 [g / m ² ] or more and less than 64 [g / m ² ]. The plain paper 1 has a weight per unit area of 64 [g / m ² ] or more and less than 82 [g / m ² ], and the recycled paper 1 has a weight per unit area of 64 [g / m ² ] or more and 82 [g / m ² ]. g / m ² ] of recycled paper (recycled paper).

  The power supply device 101 applies a high frequency current of 20 kHz to 50 kHz to the exciting coil 6 while the fixing belt 1 is rotating during the heat treatment of the recording material. The alternating magnetic field generated by the exciting coil 6 to which the high-frequency current is applied generates an induction current in the metal layer (conductive layer) of the fixing belt 1 to induce heat generation in the fixing belt 1.

  The temperature control circuit 102 controls the electric power input to the exciting coil 6 by changing the frequency of the high-frequency current based on the detected value of the temperature sensor TH1 so that the detected temperature of the temperature sensor TH1 is constant at 180 ° C., for example. To do. When the temperature detected by the temperature sensor TH1 reaches, for example, 220 ° C., the temperature control circuit 102 cuts off the energization to the exciting coil 6.

  In the fixing device 200, since the induction heating device 100 is disposed outside the fixing belt 1, not inside the fixing belt 1 that becomes high temperature, the temperature of the exciting coil 6 does not easily become high. Therefore, the electrical resistance of the exciting coil 6 does not increase, and loss due to Joule heat generation can be reduced even when a high-frequency current is passed. Since the exciting coil 6 is arranged outside the fixing belt 1, it contributes to the reduction of the diameter and the heat capacity of the fixing belt 1, and the energy saving is improved. Since the warming-up time of the fixing device 200 has a very low heat capacity, when the power of 1500 W is input to the exciting coil 6, the surface temperature of the fixing belt 1 reaches the target temperature of 180 ° C. in about 15 seconds. For this reason, the heating operation during standby is not required, and the power consumption can be kept very low.

(3) Core Moving Mechanism As shown in FIG. 4, the induction heating device 100 that is an example of induction heating means causes the magnetic flux to act on the fixing belt 1 to induction heat the fixing belt 1. The outer magnetic core 7a and the magnetic flux shielding member 103, which are examples of the incident magnetic flux adjusting mechanism, are arranged in the direction of the axis of rotation of the magnetic flux incident on the fixing belt 1 in accordance with the length in the direction perpendicular to the conveying direction of the recording material to be heated. Can be adjusted.

  The outer magnetic core 7a is disposed so as to be movable up and down by a core moving mechanism 106 using a cam row whose phases are gradually changed. The outer magnetic core 7a rises at a non-sheet passing portion formed outside the range through which the recording material passes, widens the gap between the exciting coil 6 and the outer magnetic core 7a, and passes through the fixing belt 1. The heat generation amount of the fixing belt 1 is reduced by reducing the magnetic flux density.

  The outer magnetic core 7a is formed in the region of both end portions of the fixing belt 1 so as to cope with the temperature rise of the non-sheet passing portion in recording materials of various paper sizes such as postcards, A5, B4, A4, and A3. Are divided into a plurality of portions in a direction orthogonal to the recording material conveyance direction. The width of the outer magnetic core 7a viewed in a direction perpendicular to the recording material conveyance direction is 10 mm here. The controller 150 discriminates the type of the recording material and moves the outer magnetic core 7 a located in the non-sheet passing area in a direction away from the excitation coil 6 to reduce the magnetic flux density incident on the fixing belt 1. As the outer magnetic core 7a moves corresponding to the size of the recording material, the temperature rise at the non-sheet passing portion is suppressed.

(4) Magnetic flux shielding member As shown in FIG. 4, the outer magnetic core 7a employs a mechanism that moves up and down by a set of two, so the non-passage is within a range of maximum 10 mm × 2 = 20 mm. There is a possibility that the magnetic flux enters the fixing belt 1 of the paper portion and the non-sheet passing portion temperature rises. Therefore, the magnetic flux shielding member 103 is provided so that the range in which the magnetic flux enters the fixing belt 1 can be finely adjusted.

  The pair of magnetic flux shielding members 103 are maintained in the longitudinal direction of the fixing belt 1 while maintaining a symmetrical positional relationship parallel to the fixing belt 1 by a driving mechanism 107 using a resin screw mechanism (not shown) arranged in parallel to the fixing belt 1. Moving. The magnetic flux shielding member 103 has a greater effect of weakening the magnetic flux incident on the fixing belt 1 than the movement of the outer magnetic core 7a, and moves in conjunction with the moving mechanism of the outer magnetic core 7a. The longitudinal heat generation distribution can be controlled more finely than the division width of the core 7a.

  The magnetic flux shielding member 103 is disposed between the exciting coil 6 and the fixing belt 1 at both ends in the longitudinal direction of the fixing belt 1. The width of the magnetic flux shielding member 103 in the direction intersecting the recording material conveyance direction has a sufficient width to exhibit the magnetic flux shielding effect, does not reduce the maximum heat generation width corresponding to the maximum size recording material, In consideration of not increasing the width in the longitudinal direction, the width is set to 20 mm. Here, a copper plate was used, and the thickness of the copper plate was set to 0.5 mm in consideration of the skin depth at 20 kHz to 50 kHz. The magnetic flux shielding member 103 may be a nonmagnetic metal such as aluminum, copper, silver, gold, or brass, or an alloy thereof, or may be a material such as ferrite or permalloy that is a high magnetic permeability member. The arrangement of the magnetic flux shielding member 103 may be between the exciting coil 6 and the outer magnetic core 7a, between the fixing belt 1 and the magnetic shielding core 5, or the like.

(5) Heat Transfer Rotator As shown in FIG. 2, a pressure roller 2 as an example of a pressure rotator is pressed against a fixing belt 2 as an example of a heating rotator to form a nip portion N of a recording material. . The heat equalizing roller 13, which is an example of a heat transfer rotating body, is in pressure contact with the pressure roller 2 and transfers heat so as to equalize the temperature distribution in the rotation axis direction of the pressure roller 2.

  The fixing device 200 includes a soaking roller 13 that can be attached to and detached from the pressure roller 2 by a contact / separation mechanism 105. The soaking roller 13 absorbs the heat of the non-sheet passing portion of the fixing belt when it is in pressure contact with the pressure roller 2, and transfers the absorbed heat in the longitudinal direction of the pressure roller 2 to disperse it. The temperature distribution in the longitudinal direction of the pressure roller 2 is leveled. By leveling the temperature distribution in the longitudinal direction of the pressure roller 2, the temperature rise of the non-sheet passing portion of the fixing belt 1 can be suppressed, the reproducibility of the conveyance performance of the pressure roller 2 can be improved, the trailing edge wrinkles can be generated, Such a problem in conveying the recording material can be reduced.

The soaking roller 13 is made of aluminum, copper, etc., having a thermal conductivity of 100 W / m · K or more at 100 to 250 ° C. and a heat capacity of 3.0 [kJ / m ³ · K] or less at 100 to 250 ° C. It is preferable to use a material.

  The soaking roller 13 is a solid roller having an axial diameter of 8 [mm], a diameter of φ20 [mm], a length in the longitudinal direction of 300 [mm], and an interior filled with one kind of material. The soaking roller 13 is provided with a surface layer such as a fluorine coating of 20 [μm] in order to prevent dust and the like from adhering.

  As shown in FIG. 4, the soaking roller 13 is arranged in parallel with the fixing belt 1 and the pressure roller 2, and both end portions of the soaking roller 13 are rotatably supported by bearing members fixed to the support side plate 12. ing.

  As shown in FIG. 2, the soaking roller 13 can be brought into and out of contact with the pressure roller 2 by a pressure mechanism 105 including a spring or the like. The heat equalizing roller 13 forms a nip region during pressure bonding to transfer heat and is driven by the frictional force of the pressure roller 2 to rotate.

(6) Central Fan, Central Fan Duct FIG. 6 is an explanatory diagram of the operation of the central fan and the central fan duct. FIG. 7 is a perspective view of the central fan and the central fan duct. FIG. 8 is an explanatory diagram of the cooling effect of the pressure roller by the central fan.

  As shown in FIG. 4, the central fan 600 and the central fan duct 603, which are examples of the central blowing unit, blow air to the central portion of the pressure roller 2 in the rotation axis direction. The central fan 600 is arranged side by side at the same height as the end fans 601 and 602. The central fan duct 603, which is an example of the central duct, guides the air blown by the central fan 600 to the pressure roller 2 while shielding the heat equalizing roller 13 from the air blown by the central fan 600.

  A central fan 600 and a central fan duct 603 are disposed on the upstream side of the fixing device 200. The central fan 600 and the central fan duct 603 are disposed at the center in the longitudinal direction of the pressure roller 2. The central fan 600 is positioned in front of the fixing device 200 and fixed to the frame of the image forming apparatus. The central fan duct 603 is fixed to the fixing device 200 that can be detached from the frame of the image forming apparatus. However, the central fan 600 and the central fan duct 603 may be disposed in either the fixing device 200 or the fixing device 200. The air from the central fan 600 is blown in a range of ± 50 mm from the center in the longitudinal direction of the pressure roller 2. The central fan 600 operates by receiving a DC 24V power supply. The central fan 600 is turned on based on temperature difference information between the central temperature sensor TH1 and the end temperature sensor TH2.

  As shown in FIG. 7 with reference to FIG. 6, an opening of 13.7 mm × 32 mm is formed on the front end side of the central fan duct 603. A guide shape 603 a is provided so that the air blown from the opening directly hits the peripheral surface of the pressure roller 2. The guide shape 603 a efficiently applies the air blown by the central fan 600 to the pressure roller 2 without applying to the pressure roller 2.

  As shown in FIG. 8, the temperature distribution in the longitudinal direction of the fixing belt 1 changes according to ON / OFF of the central fan 600. The temperature distribution was measured using an infrared thermography FSV-7000S manufactured by Apiste Co., Ltd.

  When the central fan 600 is not driven, the surface temperature of the fixing belt 1 at the end position of the recording material is lowered as indicated by the broken line. The temperature distribution of the pressure roller 2 heated by the fixing belt 1 is also higher at the central portion than at the end portion, and the central portion of the pressure roller 2 is further thermally expanded. The larger is the so-called crown shape.

  When the pressure roller 2 expands and the outer diameter changes, the recording material conveyance speed changes. When the crown-shaped pressure roller 2 transports the recording material, the feeding speed at the center is faster than the end, and the end of the recording material is pulled to the center of the recording material, causing wrinkles at the trailing edge of the recording material. It becomes easy to do. The trailing edge wrinkle of the recording material is more conspicuous as the recording paper has a lower rigidity.

  Therefore, before the start of image formation, the central fan 600 is operated to cool the central portion in the longitudinal direction. As a result of heating the fixing belt 1 so as to withstand cooling of the air blowing and maintaining the temperature of the central portion, the temperature of the end portion that does not receive air blowing rises and the crown shape is eliminated. As a result, the occurrence of rear end wrinkles is prevented.

(7) Control of Central Fan FIG. 9 is a block diagram of control of the fixing device. FIG. 10 is a time chart for controlling the central fan. FIG. 11 is a flowchart of the control of the central fan.

  As shown in FIG. 9, information (size and type) of the recording material output by the user is sent to the recording material information processing unit 1002 from the operation unit 301 or an external computer. Information of the recording material information processing unit 1002 is transferred to the CPU 1000 of the control unit 150. The CPU 1000 refers to the memory 1001, obtains the number of movements of the outer magnetic core 7 a and the amount of movement of the magnetic flux shielding member 103 based on the information of the recording material information processing unit 1002, and transfers them to the core movement / magnetic shielding control unit 1004. . The core movement / magnetic shielding controller 1004 moves the designated number of outer magnetic cores 7a and moves the magnetic flux shielding member 103 by the designated amount of movement.

  The control unit 150 refers to the memory 1001 with the information of the recording material processing unit 1002 and determines whether or not the type of the recording material that drives the central fan 600. The control unit 150 refers to the memory 1001 with the information of the printed sheet counter 1003, determines the off condition of the central fan 600, and issues a command to the fan control unit 1006. The fan control unit 1006 controls ON / OFF of the central fan 600.

  As shown in FIG. 10, the central fan 600 is driven when the power is turned on at the beginning of the day or at the start of an image forming job. When the fixing device 200 is started up, the central portion of the pressure roller 2 is rapidly cooled, and the above-described target temperature distribution is realized in the pressure roller 2 as soon as possible.

  As shown in FIG. 10 with reference to FIG. 2, the controller 150 first operates the pressure roller detaching motor to press the pressure roller 2 against the fixing belt 1 to form the nip portion N.

  Next, the controller 150 rotates the fixing belt 1 by driving the pressure roller 2 with a drive motor. At that time, the magnetic flux shielding member 103 and the outer magnetic core 7a realize the maximum heat generation width.

  Next, the control unit 150 supplies power to the exciting coil 6 to start temperature adjustment of the fixing belt 1. The central fan 600 is operated at the timing when the fixing belt 1 reaches the target temperature.

  Next, in order to control the heat generation width according to the size of the recording material, the control unit 150 operates the core moving motor and the magnetic shielding motor to set the heat generation width of the fixing belt 1 according to the recording material size. To do.

  Next, the control unit 150 starts image forming and outputs an image on the recording material. When the number of heat-treated recording materials reaches a predetermined number, the central fan 600 is stopped.

  When the image formation is completed, the controller 150 stops temperature adjustment of the fixing belt 1, stops driving the pressure roller 2, and separates the pressure roller 2 from the fixing belt 1. Thereafter, the core moving motor and the magnetic shielding motor are operated to move the outer magnetic core 7a and the magnetic flux shielding member 103 to the home position (maximum heat generation width).

  As shown in FIG. 11 with reference to FIG. 9, when the main body power of the image forming apparatus is turned on or an image forming job is received (S1), the control unit 150 sets the temperature adjustment table according to the environmental temperature and the type of recording material. The target temperature for temperature adjustment is calculated with reference to (S2). The controller 150 moves the magnetic flux shielding member 103 and the outer magnetic core 7a to maximize the heat generation width of the fixing belt 1 (S3).

  The controller 150 stops if the temperature of the fixing belt 1 obtained from the output of the thermistor TH1 exceeds 140 ° C. (N in S4) and the central fan 600 is driven (S13), and the target temperature offset T1. Is eliminated (S14).

  If the temperature of the fixing belt 1 obtained from the output of the thermistor TH1 is 140 ° C. or less (Y in S4) and the width of the recording material is 100 mm or more (Y in S5), the controller 150 determines the end of the fixing belt 1 And a temperature difference ΔTH between the central portions is obtained. The controller 150 stops if the temperature difference ΔTH is Toff1 = 10 ° C. or more (Y of S6) and the central fan 600 is operating (S7), and returns the target temperature offset (S8). This is because the temperature rise of the non-sheet passing portion is sufficient to prevent the trailing edge wrinkles.

  If the temperature difference ΔTH is less than Ton1 = 5 ° C. (Y in S9), the control unit 150 operates the central fan 600 (S10), and subtracts the target temperature offset T1 = 10 ° C. from the target temperature for temperature adjustment ( S11). The reason for lowering the target temperature offset T1 is that the temperature at the end of the fixing belt 1 becomes too high unless the target temperature for temperature adjustment of the fixing belt 1 is lowered. If the temperature difference ΔTH is greater than or equal to Ton1 and less than Toff1 (N in S9), the control unit 150 maintains the current state.

  The controller 150 moves the magnetic flux shielding member 103 and the outer magnetic core 7a within one second after the recording material enters the nip portion N (Y in S12 or S15), and records the heat generation width of the fixing belt 1. According to the material size (S16), the recording material is continuously heated.

  The control unit 150 operates the central fan 600 as necessary even during continuous heat treatment of the recording material. When the width of the recording material is less than 100 mm (N in S17), the control unit 150 stops the central fan 600 (S25) and eliminates the target temperature offset T1 (S26).

  When the width of the recording material is 100 mm or more (Y in S17), the control unit 150 stops the central fan 600 when the cumulative number N2 of the heat-treated recording materials reaches a predetermined number N2 = 5 (N in S18). Then, the target temperature offset T1 is canceled (S26). N2 = 5 is a value converted to A4 on one side.

  The controller 150 increases the temperature difference ΔTH between the end portion and the central portion of the fixing belt 1 until the cumulative number N2 of the recording materials heated in the image forming job reaches a predetermined number N2 = 5 (Y in S18). Accordingly, ON / OFF of the central fan 600 is determined.

  If the temperature difference ΔT exceeds Toff2 = 10 ° C. (Y in S19), the controller 150 stops if the central fan 600 is operating (S20), and cancels the target temperature offset T1 (S21). .

  When the temperature difference ΔT is Toff2 = 10 ° C. or less (N in S19) and the temperature difference ΔT is Ton2 = 5 ° C. or less (Y in S22), the control unit 150 operates the central fan 600 (S23), The target temperature offset T2 = 10 ° C. is subtracted from the target temperature for temperature adjustment (S24).

  If the image forming job is completed (Y in S27), the control unit 150 stops the image forming apparatus. If the image forming job is not completed (N in S27), the control unit 150 continues the image forming (S17).

(8) End Fan, End Fan Duct FIG. 12 is an explanatory view of the operation of the end fan and the end fan duct. FIG. 13 is a perspective view of the end fan and the end fan duct.

  As shown in FIG. 4, the end fans 601 and 602 and the end fan ducts 604 and 605 that are examples of the end blowing unit blow air to the end of the heat equalizing roller 13 in the rotation axis direction. The end fans 601 and 602 are disposed at a position lower than the recording material conveyance surface. End fan ducts 604 and 605, which are examples of end ducts, guide the air from the end fans 601 and 602 to the heat equalizing roller 13 while shielding the pressure roller 2 from the air from the end fans 601 and 602.

  When the heating area becomes wider than the recording material in the width direction perpendicular to the conveyance direction of the recording material, the temperature of the non-sheet passing portion of the fixing belt 1 that does not contact the recording material is increased. In addition, since the amount of heat taken by the recording material is smaller at the end portion in the width direction of the recording material than in the central portion in the width direction of the recording material, the end portion in the width direction of the recording material increases as the number of sheets passed increases. A slight temperature increase occurs compared to the central portion. The phenomenon of the temperature rise at the non-sheet passing portion and the temperature rise at the end of the recording material is noticeable in the fixing belt 1 using the low heat capacity belt. Due to these temperature rises, uneven gloss occurs at the end and center of the recording material, and the durability life of the fixing belt 1 is affected. Therefore, in the fixing device E, the end fans 601 and 602 and the end portions are affected. The fan ducts 604 and 605 are controlled to suppress these temperature increases.

  End fans 601 and 602 and end fan ducts 604 and 605 are disposed upstream of the fixing device 200. The end fan 601 and 602 and the end fan ducts 604 and 605 are disposed at both ends in the longitudinal direction of the pressure roller 2. The end fans 601 and 602 are positioned in front of the fixing device 200 and fixed to the frame of the image forming apparatus E. The end fan ducts 604 and 605 are fixed to the fixing device 200 detachable from the frame of the image forming apparatus E. However, the end fans 601 and 602 and the end fan ducts 604 and 605 may be disposed in either the fixing device 200 or the image forming apparatus E.

  As shown in FIG. 12, the air blown from the end fans 601 and 602 through the end fan ducts 604 and 605 is blown to the soaking roller 13 and guided along the lower surface of the soaking roller 13. The fixing belt 1 is not sprayed directly. The soaking effect of the soaking roller 13 is enhanced by blowing cool air to the soaking roller 13 to lower the temperature of the soaking roller 13.

  When directly sprayed onto the pressure roller 2, the air reaches the center of the fixing belt 1 in the longitudinal direction, and the temperature detected by the temperature sensor TH1 decreases. Then, the induction heating device 100 increases the output so as to increase the temperature of the fixing belt 1, and the temperature increase of the non-sheet passing portion further proceeds.

  The end fans 601 and 602 are turned on based on the temperature information of the end temperature sensors TH2 and TH3 during the job and the converted number of sheets during the job. It is also possible to increase the air volume of the end fans 601 and 602 with the temperature detected by the temperatures of the end temperature sensors TH2 and TH3.

  As shown in FIG. 13, the end fan ducts 604 and 605 have a slit-shaped hole of 1.9 mm × 73 mm on the blowing side. As shown in FIG. 4, the center line of the slit-shaped hole is disposed at a position 105 mm from the longitudinal center. That is, each of the end fan ducts 604 and 605 is disposed at a position facing the range corresponding to the maximum size recording material outside the range corresponding to the minimum size recording material of the heat equalizing roller 13 in the width direction.

(9) End Fan Control FIG. 14 is a time chart of the end fan control. FIG. 15 is a flowchart of the end fan control.

  As shown in FIG. 12, the contact / separation mechanism 105 contacts and separates the soaking roller 13 with respect to the pressure roller 2. A temperature sensor TH2, which is an example of an end temperature detecting means, detects the temperature of the end of the fixing belt 1 in the rotation axis direction. The control unit 150, which is an example of a control unit, controls the contact / separation mechanism 105 and the end fans 601 and 602 based on the output of the temperature sensor TH2. The controller 150 starts the continuous heating process of the recording material in a state in which the soaking roller 13 is separated from the pressurizing roller 2, and then the soaking roller is applied to the pressurizing roller 2 when the end of the pressurizing roller 2 exceeds a predetermined temperature. 13 is pressed. The control unit 150 operates the end fans 601 and 602 when the end of the pressure roller 2 exceeds a predetermined temperature after the temperature equalizing roller 13 is pressed against the pressure roller 2.

  As shown in FIG. 15 with reference to FIG. 9, when the image forming job is received, the control unit 150 starts to rotate and heat the fixing belt 1 (S31).

  When the size of the recording material is determined (Y in S32), the controller 150 moves the outer magnetic core 7a in accordance with the size of the recording material (S33). Then, it waits for the fixing belt 1 to reach the target temperature, and when it reaches the target temperature, the recording material heating process is started (S33).

  The controller 150 causes the contact / separation mechanism 105 when the temperature of the non-sheet-passing portion is increased with the continuous heat treatment of the recording material and the temperature detected by the temperature sensor TH2 is 220 ° C. or higher (Y in S34). The soaking roller 13 is operated and brought into pressure contact with the pressure roller 2 (S35). If the temperature detected by the temperature sensor TH2 is lower than 220 ° C., the soaking roller 13 keeps the separated state with respect to the pressure roller 2. When the temperature equalizing roller 13 is brought into pressure contact with the fixing belt 1 during the temperature rise or in the initial stage of the recording material heating process, the temperature rise slows down or an unnecessary temperature drop occurs. It is pressed during processing.

  Even if the temperature equalizing roller 13 is pressed against the pressure roller 2 and the temperature of the non-sheet passing portion is increased and the temperature detected by the temperature sensor TH2 becomes 230 ° C. or higher (Y in S36), the controller 150 ends the end portion. The fans 601 and 602 are turned on (S37). If the detected temperature of the temperature sensor TH2 is lower than 230 ° C., the end fans 601 and 602 are not operated, and the suppression of the temperature rise of the non-sheet passing portion relying solely on the soaking roller 13 is continued. The above procedure is continued until the image forming job is completed (N in S38).

  In the image forming apparatus E according to the first exemplary embodiment, the heating roller 13 and the end fans 601 and 602 are effective in a configuration in which the heating region of the fixing belt 1 can be accurately set using the magnetic flux shielding member 103 and the outer magnetic core 7a. Reduce the temperature rise at the non-sheet passing part. Thereby, the durable life of the fixing belt 1 is improved.

(10) Effects of Embodiment 1 In the fixing device 200, the fixing device 200 has a thin and small diameter fixing belt 1 in order to increase the temperature at high speed. By using a belt member for the heating rotator, power saving and shortening of the start-up time are realized. The temperature rise of the non-sheet passing portion of the fixing belt 1 can be accurately suppressed while improving the transportability of the recording material.

  Since the fixing device 200 efficiently heats the region of the fixing belt 1 having a small mass according to the width of the recording material by the induction heating device 100, the fixing device 200 is excellent in power saving and shortening of the startup time. Since the fixing device 200 generates a temperature difference between a region of the fixing belt 1 that is cooled by contact with the recording material and a region that is not cooled by the recording material outside the recording material, the heat treatment of the continuous recording material is performed. When this is performed, the temperature rise in the non-sheet passing portion occurs.

  In the fixing device 200, the heat capacity of the heating rotator is reduced, and the fixing device 200 is heated by a heat source having good heating efficiency. Further, from the viewpoint of cost and energy efficiency, a thin heating rotator is brought into contact with the recording material to heat and melt the toner image on the recording material.

  Since the fixing device 200 uses the thin fixing belt 1 in order to reduce the heat capacity of the heating rotator, the cross-sectional area of the cross section perpendicular to the axis is extremely small, and the heat mobility in the axial direction is not good. This tendency becomes more conspicuous as the fixing belt 1 is thinner, and is further lowered with a material such as a resin having low thermal conductivity.

  In the fixing device 200, a small-sized recording material having a small width is continuously fed in the same manner as in the case where the recording material having the full length in the longitudinal direction of the heating rotator, that is, the recording material having the maximum sheet passing width, is heated. Even in this case, the temperature difference between the non-sheet passing area and the sheet passing area does not increase. Even if the heat capacity of the conveyed recording material is large or the productivity (number of printed sheets per unit time) is high, the temperature difference between the paper passing area and the non-paper passing area does not increase.

  The fixing device 200 can accurately suppress the temperature increase of the non-sheet passing portion of the fixing belt 1 while improving the paper transportability. Since the temperature unevenness in the longitudinal direction of the pressure roller 2 can be eliminated, even if a small size recording material is passed through immediately after passing a small size recording material, paper wrinkles, skew, etc. , Fixing unevenness hardly occurs. Therefore, it is easy to apply the thin-walled and low heat capacity fixing belt 1 to a high-throughput copying machine or the like.

  Note that the threshold value of the temperature detected by the temperature sensor TH2 that presses the soaking roller 13 against the pressure roller 2 is the setting of the size and type of the recording material, the productivity of the image forming apparatus E, or after the start of the heating process of the recording material. It may be changed according to the cumulative number of processed sheets. Further, as shown in FIG. 4, in the present embodiment, the temperature sensors TH2 and TH3 detect the temperature of the fixing belt 1, but it is not intended to be limited to this configuration. The temperature sensors TH2 and TH3 may be configured to detect the temperature of the pressure roller 2.

  The threshold value of the temperature detected by the temperature sensor TH2 for operating the end fans 601 and 602 is the cumulative processing after the recording material size and type, the productivity setting of the image forming apparatus E, or the recording material heating process is started. It may be changed according to the number of sheets.

  In addition, if the temperature equalizing roller 13 is started in accordance with the operation of the end fans 601 and 602, the temperature drop in the sheet passing area can be prevented. Therefore, the ON timing of the end fans 601 and 602 and the temperature equalizing roller 13 Each threshold may be set so that the arrival timings coincide with each other.

  Further, the central fan 600 and the end fans 601 and 602 can use centrifugal fans such as sirocco fans. The sirocco fan can adjust the air volume by changing the input voltage. It is possible to adjust the air volume of the end fans 601 and 602 according to the temperature detected by the temperature sensors TH1, TH2, and TH3.

  A halogen lamp or a heating resistor may be used as a heating source. As a configuration for changing the heating range, a configuration may be adopted in which the heating source is divided and the energization is selectively performed so as to heat the region according to the sheet passing width.

  Similarly, in a heating apparatus using an induction coil as a heating source, a configuration in which the heating source is divided and selectively energized may be employed.

DESCRIPTION OF SYMBOLS 1 Fixing belt, 2 Pressure roller, 3 Pressure application member, 4 Stay 5 Magnetic shielding core, 6 Excitation coil, 7a Outer magnetic body core 10 Fixing flange, 12 Support side plate 13 Heat equalizing roller, 100 Induction heating device, 101 Power supply device 102 Temperature control circuit, 103 Magnetic flux shielding member, 104 Motor 105 Contact / separation mechanism, 150 Control unit, 200 Fixing device 600 Central fan, 601, 602 End fan 603 Central fan duct, 603a Guide shape 604, 605 End fan duct TH1 , TH2 temperature sensor

Claims (6)

A heating rotator for heating the recording material;
A pressure rotating body that presses against the heating rotating body to form a nip portion of the recording material;
A heat transfer rotating body that transfers heat so as to equalize the temperature distribution in the rotation axis direction of the pressure rotating body by being pressed against the pressure rotating body;
An image heating apparatus comprising: an end blowing unit that blows air to an end of the heat transfer rotating body in the rotation axis direction.   The end air blower includes an end fan disposed at a position lower than the conveying surface of the recording material, and the heat transfer of the air from the end fan while shielding the pressure contact rotating body from the air blow of the end fan. The image heating apparatus according to claim 1, further comprising an end duct that guides the rotating body. A central air blowing means for blowing air to a central portion of the pressure contact rotating body in the rotation axis direction;
The central blower means a central fan arranged side by side at the same height as the end fan, and the central fan blows the central fan to the pressure rotating body while shielding the heat transfer rotary body from the blow of the central fan. The image heating apparatus according to claim 2, further comprising a central duct for guiding. A contact / separation mechanism for contacting / separating the heat transfer rotor with respect to the pressure contact rotor;
End temperature detection means for detecting the temperature of the end portion in the rotation axis direction of the press-contact rotating body or the heating rotating body;
After starting the continuous heating process of the recording material with the heat transfer rotator spaced from the pressure contact rotator, when the end of the pressure contact rotator exceeds a predetermined temperature, the heat transfer rotator is pressed against the pressure contact rotator. Based on the output of the end temperature detecting means so that the end blowing means is operated when the end of the pressure contact rotating body exceeds a predetermined temperature after the heat transfer rotating body is pressed against the pressure rotating body. 4. The image heating apparatus according to claim 1, further comprising a control unit configured to control the contact / separation mechanism and the end air blowing unit. A central temperature detecting means for detecting the temperature of the central portion of the heating rotating body in the rotation axis direction;
Heating means for heating the heating rotator;
Temperature control means for controlling the heating means based on the output of the central temperature detecting means so that the temperature of the central part in the rotation axis direction of the heating rotator maintains a predetermined temperature. The image heating apparatus according to claim 1. Induction heating means for inductively heating the heating rotator by causing magnetic flux to act on the heating rotator;
An incident magnetic flux adjusting mechanism capable of adjusting a distribution in a rotation axis direction of a magnetic flux incident on the heating rotating body according to a length in a direction perpendicular to a conveying direction of a recording material to be heat-treated. The image heating apparatus according to claim 1.

Images