JP2011033654A - Image heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image heater that keeps output image quality high by suppressing partial lubricant deterioration without incorporating a new mechanism and by keeping the resistance of friction between a slide member and a belt member low. <P>SOLUTION: A fixing film 405 forms a heating nip N for a recording material P between a pressure roller 402 and the fixing film 405. In order to decrease friction load on a heater 403 and the fixing film 405, a lubricant is applied to the internal face of the fixing film 405. When the pressure roller 402 is rotated and driven, the fixing film 405 rotates by following it. Every time a fixing process is performed on 1000 sheets of paper, a lubricant movement mode is executed to replace the lubricant in a slide portion between the heater 403 and the fixing film 405. In the lubricant movement mode, the heat nip is released by a pressure mechanism 420 after the pressure roller 402 is stopped, and thereafter, the pressure roller 402 is rotated to rotate the fixing film 405 by 20 degrees. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image heating apparatus that heats and pressurizes a recording material bearing a toner image using a belt member having an inner surface coated with a lubricant, and more specifically, moves a stagnant lubricant to move the stagnant lubricant. The present invention relates to control for restoring a lubrication state.

  2. Description of the Related Art Image forming apparatuses that transfer a toner image onto a recording material and then fix the full-color or black-and-white image on the recording material by sandwiching and conveying the recording material at a heating nip of an image heating apparatus and heating the recording material are widely used. In addition to a fixing device that fixes an unfixed toner image on a recording material, the image heating device also includes a finishing processing device that reheats a recording material carrying a semi-fixed or fixed image to adjust the finish of the image surface.

  Patent Document 1 discloses a fixing device that forms a heating nip of a recording material by pressing a driving roller against an outer surface of a belt member that supports an inner surface with a rubbing member incorporating a heating means (induction heating device). It is. In this method, since the heat capacity of the belt member is small, the temperature of the heating nip rises quickly, and it is not necessary to supply power during standby, so that overall power consumption is less than that of the roller heating method.

  Patent Document 2 discloses a pressurizing mechanism that can change the pressing force of the belt member sandwiched between the driving member and the rubbing member. Here, a beam-shaped pressing member is disposed by penetrating the belt member in the axial direction, and the pressing member presses the entire longitudinal direction of the rubbing member toward the driving roller. The pressurizing mechanism (cam) presses both end portions of the pressurizing member on the outside of the belt member with a variable pressing force.

  Patent Document 3 discloses an image heating apparatus using a belt member in which a lubricant is applied to an inner surface in order to reduce a friction load of rubbing with a rubbing member accompanying rotation of the belt member. Here, the control for reducing the starting load by starting the rotation of the belt member after increasing the temperature and decreasing the viscosity of the lubricant is shown.

JP-A-9-44014 JP 2001-142327 A JP 2000-338801 A

  As shown in Patent Document 3, the lubricant applied to the inner surface of the belt member gradually deteriorates by repeated heating and rubbing, and increases the frictional resistance between the rubbing member and the belt member. . When the frictional resistance between the rubbing member and the belt member increases beyond the limit, chatter vibration and slip of the belt member occur, and the deterioration of the fixed image becomes conspicuous.

  In particular, as shown in FIG. 2, when the resistance heating element (403) is disposed so as to directly heat the heating nip (N), the lubricant between the belt member (405) and the resistance heating element (403) has a high temperature. The resistance heating element (403) tends to deteriorate. Further, when the resistance heating element (404) is disposed one step backward from the rubbing surface of the rubbing member (404) in order to improve the separation property of the recording material on the downstream side, the lubrication stagnated in the receding recess. The agent tends to deteriorate. When the lubricant is deteriorated, the frictional force between the rubbing members (404, 403) and the belt member (405) is increased, so that additional heat is generated and the deterioration of the lubricant is accelerated. For this reason, an image quality problem occurs in image formation of about 200,000 sheets, and the entire fixing device (40) may be replaced with a new one.

  Therefore, it has been proposed to supply additional lubricant by bringing a pad soaked with new lubricant into contact with the inner surface of the belt member (405), but the excessively supplied lubricant moves in the longitudinal direction. If it oozes out into the heating nip, the recording material (P) will be soiled. Further, in the same circulation state of the lubricant as that during the rotation of the normal belt member (405), the effect of replacing the lubricant stagnated in the dent of the rubbing member (404, 403), which is essential, is poor, and as expected. There was no life extension effect.

  In addition, it has been proposed to provide a lubricant circulation path on the rubbing member to forcibly supply and discharge the lubricant. However, in the fixing device in which the diameter of the belt member is reduced to about 30 mm, There is no room for incorporation and it cannot be adopted from the viewpoint of manufacturing costs.

  The present invention provides an image heating apparatus that can suppress deterioration of a local lubricant without incorporating a new mechanism, and can keep the output image quality high by keeping the frictional resistance between the rubbing member and the belt member low. The purpose is that.

  The image heating apparatus of the present invention includes a belt member having an inner surface coated with a lubricant, a driving member that contacts the outer surface of the belt member to rotate the belt member, and an inner surface of the belt member. In addition, a rubbing member that sandwiches the belt member between the driving member and a heating means for the belt member is provided. And a pressure mechanism capable of changing a pressure applied to the belt member by the driving member and the rubbing member, and a state in which the pressure applied by the pressure mechanism is lower than that during image heating. And a control means capable of executing a lubricant movement mode in which the belt member is rotated by the driving member.

  In the image heating apparatus of the present invention, the lubricant movement mode is executed to generate a lubricant circulation state that is different from that during normal rotation of the belt member. As a result, at least a portion of the lubricant stagnated in an environment that is likely to deteriorate during rotation of the normal belt member (between the rubbing member and the belt member) is in another environment that is unlikely to deteriorate (upstream of the rubbing member). Replaced with stagnant lubricant. For this reason, it is possible to prevent the lubricant from continuously stagnating between the rubbing member and the belt member and progressing in deterioration.

  Therefore, local deterioration of the lubricant can be suppressed without incorporating a new mechanism, and the frictional resistance between the rubbing member and the belt member can be kept low, and the output image quality can be maintained high.

1 is an explanatory diagram of a configuration of an image forming apparatus. FIG. 3 is an explanatory diagram of a configuration of a fixing device. It is explanatory drawing of the pressurization mechanism of a fixing device. It is explanatory drawing of a heater. FIG. 6 is an explanatory diagram of a relationship between a time elapse at the time of starting the fixing device and a motor torque. It is explanatory drawing of the relationship between the temperature of a lubricant, and a viscosity. It is explanatory drawing of the movement of the lubricant in the lubricant movement mode of Example 1. 3 is a flowchart of a lubricant movement mode according to the first embodiment. FIG. 6 is an explanatory diagram of lubricant movement in a lubricant movement mode according to a third embodiment. 6 is a flowchart of a lubricant movement mode according to a third embodiment. 10 is a flowchart of a lubricant movement mode according to a fourth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention provides another embodiment in which a part or all of the configuration of the embodiment is replaced with the alternative configuration as long as the pressure of the heating nip is released and the belt member is rotated to move the lubricant. But it can be done.

  Therefore, the image heating apparatus is not limited to the image heating apparatus in which the pressure roller is pressed against the belt member, and the image heating apparatus can be implemented in which the pressure belt is pressed against the belt member.

  An image forming apparatus equipped with an image heating apparatus can be implemented without distinction between an intermediate transfer belt system, a recording material conveyance belt system, a system that transfers a toner image to a recording material, a tandem type, and a drum type. In the present embodiment, only main parts related to toner image formation / transfer will be described. However, in addition to necessary equipment, equipment, and a housing structure, various printers, various printing machines, copiers, fax machines, multifunction machines, etc. Can be implemented in

  In addition, about the general matter of the image heating apparatus shown by patent documents 1-3, illustration is abbreviate | omitted and the overlapping description is abbreviate | omitted.

<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 10 is a tandem type full-color printer in which image forming units 10Y, 10M, 10C, and 10K are arranged along an intermediate transfer belt 31.

  In the image forming unit 10 </ b> Y, a yellow toner image is formed on the photosensitive drum 11 </ b> Y and is primarily transferred to the intermediate transfer belt 31. In the image forming unit 10M, a magenta toner image is formed on the photosensitive drum 11M, and is primarily transferred onto the yellow toner image on the intermediate transfer belt 31. In the image forming units 10C and 10K, a cyan toner image and a black toner image are formed on the photosensitive drums 11C and 11K, respectively, and similarly, the toner images on the intermediate transfer belt 31 are sequentially superimposed and sequentially transferred.

  The four color toner images carried on the intermediate transfer belt 31 are collectively secondary transferred onto the recording material P by the secondary transfer portion T2. The recording material P drawn from the recording material cassette 20 by the pickup roller 21 and separated one by one by the separation roller waits at the registration roller 23, and performs secondary transfer in synchronization with the toner image on the intermediate transfer belt 31. Sent to the part T2.

  The recording material P onto which the toner image has been secondarily transferred at the secondary transfer portion T2 is heated and pressurized by the fixing device 40 and fixed on the surface, and then discharged onto the discharge tray 64 through the discharge roller 63. The

  The image forming units 10Y, 10M, 10C, and 10K are configured substantially the same except that the color of the toner used in the developing device attached thereto is different from yellow, magenta, cyan, and black. Hereinafter, the image forming unit 10Y will be described, and the other image forming units 10M, 10C, and 10K will be described by replacing “Y” at the end of the reference code with “M”, “C”, and “K”.

  In the image forming unit 10Y, a corona charger 12Y, an exposure device 13Y, a developing device 14Y, a transfer blade 17Y, and a cleaning device 15Y are arranged around the photosensitive drum 11Y. The photosensitive drum 11Y is composed of a metal cylinder on which a negatively charged photosensitive layer is formed, and rotates in a direction indicated by an arrow at a predetermined process speed. The corona charger 12Y charges the surface of the photosensitive drum 11Y to a uniform negative potential. The exposure device 13Y writes an electrostatic image of the image on the surface of the charged photosensitive drum 11Y. The developing device 14Y stirs and charges the two-component developer, and reversely develops the electrostatic image on the photosensitive drum 11Y with the negatively charged toner.

  The transfer blade 17Y presses the inner surface of the intermediate transfer belt 31 to form a primary transfer portion between the photosensitive drum 11Y and the intermediate transfer belt 31. By applying a positive DC voltage to the transfer blade 17Y, the toner image carried on the photosensitive drum 11Y is primarily transferred to the intermediate transfer belt 31.

  The secondary transfer roller 35 sandwiches the intermediate transfer belt 31 between the counter roller 34 and forms a secondary transfer portion T <b> 2 between the intermediate transfer belt 31 and the secondary transfer roller 35. The secondary transfer unit T2 overlaps and conveys the recording material P on the intermediate transfer belt 31 carrying the toner image, and applies a positive direct current voltage to the secondary transfer roller 35, so that the intermediate transfer belt 31 The toner image is secondarily transferred to the recording material P.

<Fixing device>
FIG. 2 is an explanatory diagram of the configuration of the fixing device. FIG. 3 is an explanatory diagram of a pressure mechanism of the fixing device. FIG. 4 is an explanatory diagram of the heater.

  As shown in FIG. 2, the fixing device 40 presses the drive member (402) from below to the belt member (405) supported on the inner surface by the rubbing members (404, 403), thereby A heating nip (N) is formed. In the process in which the recording material P passes through the heating nip (N), heat is supplied from the resistance heating element (403b) to the recording material P via the belt member (405), so that the unfixed toner image t is softened. Then, it is fixed on the surface of the recording material P. Such a pressure roller driving type and tensionless film heating type image heating apparatus are disclosed in Japanese Patent Application Laid-Open Nos. 4-44075 to 44083, Japanese Patent Application Laid-Open Nos. 4-204800 to 204984, and the like.

  The heater guide 404, the heater 403, the stay 406, and the fixing film 405 are determined in mutual positional relationship by end caps (428: FIG. 3) disposed at both ends in the longitudinal direction, thereby constituting the fixing film unit 401. .

  The heater guide 404, which is an example of a rubbing member, serves as both a support member for the heater 403 and a guide member for the inner surface of the fixing film 405, and is composed of a heat-resistant resin having high heat insulation, high heat resistance, and rigidity. Is done. The heater guide 404 is a horizontally long member having a vertical direction in the drawing as a longitudinal direction, and the heater 403 is fitted into a groove provided along the longitudinal direction of the lower surface of the heater guide 404 so as to be insulated and fixedly held.

  A stay 406, which is an example of a pressure member, is a metal U-shaped beam member that reinforces the heater guide 404, and is disposed so as to penetrate the fixing film 405 in the longitudinal direction.

  A fixing film 405, which is an example of a belt member, is formed of a cylindrical resin film material having excellent heat resistance as a flexible member and has an outer diameter of 30 mm. The fixing film 405 is a thin film cylinder having a polyimide base layer having a thickness of about 30 μm to 100 μm, and PFA, PTFE, etc. for imparting releasability to the softened toner via a primer layer (adhesive layer) on the base layer. The coat is given. The fixing film 405 may be a flexible metal cylindrical body or a cylindrical material having a composite layer structure of resin or rubber having a metal layer.

  The inner peripheral length of the fixing film 405 is larger than the outer peripheral length of the assembly including the heater guide 404, the heater 403, and the stay 406. Therefore, the fixing film 405 is loosely fitted around the heater guide 404, the heater 403, and the stay 406 so that the circumferential length has a margin.

  A pressure roller 402, which is an example of a drive member, sandwiches the fixing film 405 between the heater 403 of the fixing film unit 401 and the lower surface of the stay 406. The pressure roller 402 is formed to have a diameter of 30 mm by disposing an elastic layer 402b made of silicon rubber on the outer peripheral surface of the metal shaft 402a. A release layer 402c such as PFA having a thickness of about 10 to 100 μm is provided on the surface of the elastic layer 402b via a primer layer (adhesive layer).

  The pressure roller 402 is in contact with the fixing film 405 and is driven to rotate at a predetermined peripheral speed in the direction of arrow C, which is the conveyance direction of the recording material P. As the pressure roller 402 rotates, a rotational force in the direction of arrow D acts on the fixing film 405 by the frictional force between the pressure roller 402 and the fixing film 405 in the heating nip N. As a result, the fixing film 405 rotates in the direction of the arrow D around the heater guide 404 by causing the inner surface of the fixing film 405 to slide in close contact with the downward surface of the heater 403 in the heating nip N.

  The fixing film 405 is rotated by the rotation of the pressure roller 402 in contact with the fixing film 405, and adheres to and rubs against the heating surface of the heater guide 404 on which the heater 403 is disposed, so that the fixing film 405 has substantially the same peripheral speed as the recording material P is conveyed. Rotates at speed.

  The recording material P is introduced into the heating nip N in a state in which the fixing film 405 is rotated by being driven to rotate by the pressure roller 402, and the heater 403 is heated to a predetermined target temperature by energization. A recording material P carrying an unfixed toner image t is introduced between the fixing film 405 and the pressure roller 402, and the toner image carrying surface of the recording material P is in close contact with the outer surface of the fixing film 405. Pass through the heating nip N together. At this time, the heat of the heater 403 is applied to the recording material P through the fixing film 405, and the unfixed toner image t is heated and fixed on the surface of the recording material P. The recording material P that has passed through the heating nip N is separated from the surface of the fixing film 405 and is discharged and conveyed.

  As shown in FIG. 3, the pressure mechanisms 420 arranged at both ends of the stay 406 in the longitudinal direction urge the stay 406 toward the pressure roller 402 with a variable pressing force during image heating. As a result, the elastic layer 402 b of the pressure roller 402 is elastically deformed along the contour lines of the heater guide 404 and the heater 403 to form a heating nip N necessary for the fixing device 40. When pressed toward the pressure roller 402, the stay 406 prevents the heater guide 404 and the heater 403 from being bent and deformed.

  The length of the fixing film 405 in the longitudinal direction is 340 mm, the heater guide 404 has a length in the longitudinal direction of 360 mm, and the pressure roller 402 has a rubber (elastic layer) length of 330 mm. In the pressure roller 402, both ends of the metal shaft 402a are supported by a bearing 426 fixed to the frame of the fixing device 40 so as to be both supported and rotatable.

  The pressurizing mechanism 420 operates the drive motor 421 to rotate the cam shaft 423 and rotate the pair of pressurizing cams 422 to raise and lower one end of the pressurizing spring 427. As a result, the force with which the pressure spring 427 presses both ends of the stay 406 changes, and the pressure applied to the fixing film 405 can be changed.

  The pressure mechanism 420 is configured to prevent the pressure roller 402 from being deformed or wrinkling from the fixing film 405 due to a long-term biased pressure, after the fixing device 40 is stopped. Release the nip pressure. This is because if the pressure roller 402 is deformed by continuing the pressure state during the stop, the image formation cannot be started until the deformation of the pressure roller 402 returns to the original state at the subsequent startup.

  As shown in FIG. 4A, the heater 403, which is an example of a heating unit, has an elongated heat resistance, insulating property, and good thermal conductivity with the direction perpendicular to the conveying direction of the recording material P as the longitudinal direction. A resistance heating element 403b is arranged on the surface of the substrate 403a (fixing film sliding surface side).

  The substrate 403a is made of a ceramic material such as alumina or aluminum nitride, and the heater 403 has a low heat capacity as a whole. The resistance heating element 403b is formed by forming a paste prepared by kneading silver, palladium, glass powder (inorganic binder), and organic binder into a thin band shape on the substrate 403a by screen printing. As a material of the resistance heating element 403b, an electric resistance material such as RuO 2 or Ta 2 N may be used in addition to silver palladium (Ag / Pd).

  Power supply electrodes 403d and 403e using a silver-palladium screen printing pattern are disposed at the end in the longitudinal direction of the resistance heating element 403b. When the power supply connectors 42 and 43 are fitted to the power supply electrodes 403d and 403e of the heater 403, the electrical contacts of the power supply connectors 42 and 43 are in contact with the power supply electrodes 403d and 403e, respectively.

  As shown in FIG. 4C, the surface of the heater on which the resistance heating element 403b is formed is covered and protected by a heat resistant overcoat layer 403c. The overcoat layer 403c is mainly intended to improve the slidability with respect to the fixing film (405: FIG. 2) while ensuring electrical insulation between the resistance heating element 403b and the fixing film (405: FIG. 2). is there. The overcoat layer 403c is a heat resistant glass layer having a thickness of about 50 μm. The heater 403 is fixed to the lower surface of the heater guide (404: FIG. 2) with the surface side on which the overcoat layer 403c is formed exposed downward.

  As shown in FIG. 4B, the thermistor TH is a temperature sensing element provided for detecting the temperature of the heater 403. What is the back side of the heater, that is, the side on which the resistance heating element 403b of the substrate 403a is provided? It is arranged on the opposite side.

  As shown in FIG. 3, the thermistor TH is provided inside the passing width of the minimum size recording material, and communicates with the control unit 50 via the A / D converter 41.

  A commercial power supply (AC power supply) 44 is connected to the heater 403 (403d, 403e: FIG. 4) via a triac 45. When the triac 45 is controlled by the controller 50 and power is supplied via the triac 45, the resistance heating element 403b generates heat over the entire length in the longitudinal direction, and the temperature rapidly rises rapidly. As the temperature rises, the thermistor TH detects the temperature, and the controller 50 captures the output of the thermistor TH by A / D conversion. The control unit 50 controls the triac 45 based on the temperature detected by the thermistor TH, and controls the power supplied to the resistance heating element 403b by phase control or wave number control, so that the temperature detected by the thermistor TH is converged to a predetermined temperature. Let

  When the fixing device 40 is started up, the control unit 50 controls the triac 45 based on the temperature detected by the thermistor TH to cause the heater 403 to generate heat over the entire length in the longitudinal direction and maintain it at a predetermined temperature, thereby generating abnormal heat. Deter it.

<Lubricant>
FIG. 5 is an explanatory diagram of the relationship between the elapsed time and the motor torque when the fixing device is activated. 5, (a) is the relationship between the passage of time and the surface temperature of the fixing film, (b) is the relationship between the passage of time and the motor torque, (c) is the relationship between the passage of time and the motor speed, and (d) is the passage of time. And the motor output. FIG. 6 is an explanatory diagram of the relationship between the temperature and the viscosity of the lubricant.

  The fixing device 40 has a problem that the rotational torque of the pressure roller 402 is large because the driving load of the fixing film 405 sliding with the heater guide 404 and the heater 403 is large. The sliding friction between the heater guide 404 and the heater 403 and the fixing film 405 is a major factor of the driving load. In a configuration in which a predetermined pressure is applied by the pressure roller 402, the sliding friction of the fixing film 405 is a driving load of the pressure roller 402. Occupies the majority.

  In the fixing device 40, a heat-resistant lubricant (heat-resistant grease) is applied to the inner surface of the fixing film 405 in order to reduce the sliding friction between the fixing film 405 and the heater guide 404. In consideration of improvement of the wear resistance of the fixing film 405, stable rotation of the fixing film 405, uniform heat transfer to the fixing film 405, etc., heat resistant grease is applied to the friction surfaces of the heater 403 and the fixing film 405. ing. As the heat resistant grease, HP-300 manufactured by Dow Corning Asia Co., which is composed of perfluoropolyether as a base oil, polytetrafluoroethylene (PTFE) as a thickener, or the like was used.

  When the fixing device 40 is cold, the viscosity of the heat-resistant grease is high, and thus the friction resistance of the fixing film 405 is obtained. Further, the pressure roller 402 is also deformed at the nip portion with the fixing film 405 in the stopped state. These mainly increase the rotational torque when the fixing device 40 is started up.

  As shown in FIG. 3, the change in the starting load when the heat-resistant grease was used as a lubricant was examined by rotating the fixing device 40 with a drive motor 46 (DC motor) controlled at a constant rotational speed.

  As shown in FIG. 5A, the fixing device 40 starts temperature control when the power is turned on, and the detected temperature of the thermistor TH at the times t1, t2, and t3 is controlled to the standby temperature K3 via K1 and K2. . At this time, the torque of the DC motor 46 gradually decreases as T3 passes T1 and T2, and becomes stable. The reason why the torque is increased when the fixing device 40 is started is that the lubricant applied to the sliding portion has a low temperature and thus has a high viscosity, and the frictional resistance of the rubbing portion is increased to cause the torque for rotating the fixing film 405. This is because of the increase.

  Therefore, when the power is turned on again after the stop time exceeding the predetermined time and the motor is started again, if the drive motor 46 is rotated while the temperature of the fixing device 40 is increased, the torque at the initial stage of the start shows a large value. Since the motor output is proportional to the product of the motor torque and the motor rotation speed, the relationship is as shown in (d).

  As shown in FIG. 6, since the lubricant at a low temperature has a high viscosity, the friction resistance (viscosity resistance) of the fixing film 405 having the lubricant applied to the inner surface is very high at the start of the pressing roller 402. Become bigger.

  For this reason, the rotational torque of the drive motor 46 of the pressure roller 402 increases, and when the drive motor 46 is a pulse motor, a step-out occurs and the drive of the fixing film 405 may stop. Therefore, there has been a problem that the drive motor 46 requires an expensive and large motor with high output (high torque).

  As countermeasures for reducing the torque of the drive motor 46, Japanese Patent Application Laid-Open Nos. 3-209491 and 2000-338801 propose to start driving the fixing film 405 at a predetermined temperature or higher. First, only the heater 403 is activated to raise the temperature, the lubricant is softened by the temperature rise, and the rotation of the fixing film 405 is started after waiting for the frictional resistance between the heater 403 and the fixing film 405 to decrease. Yes.

  However, the method of reducing the frictional resistance between the heater 403 and the fixing film 405 by starting the driving of the fixing film 405 at a predetermined temperature or higher at which the lubricant melts is effective when the lubricant exists in the sliding portion. It is disadvantageous when the amount of lubricant in the sliding portion becomes small, and further disadvantageous after image formation has accumulated and the lubricant in the sliding portion has been exhausted.

  In order to prevent the lubricant in the sliding portion from being depleted, a configuration in which the lubricant is applied abundantly can be considered. In addition, since the fixing device 40 applies a lubricant to the inner surface of the fixing film 405 to improve the sliding property with respect to the heater guide 404 and the heater 403, the fixing device 405 is lubricated to improve the sliding property. A configuration in which the agent is applied abundantly is conceivable.

  However, if a lubricant is interposed between the heater guide 404 and the heater 403 and the fixing film 405 more than necessary, the lubricant is pressurized on the friction surface and leaks to the outside. The lubricant leaking in the longitudinal direction enters both ends of the fixing film 405 and enters the heating nip N. When the lubricant enters the heating nip N, when the recording material P is nipped and conveyed to the heating nip N, the pressure roller 402 is idled and slipping easily occurs. For this reason, it is not allowed to apply a large amount of lubricant to the fixing film 405, and it is not preferable to supply a new lubricant to the sliding portion from the outside.

  However, since the sliding portion between the heater guide 404 and the heater 403 and the fixing film 405 is pressurized, a force for pushing the applied lubricant from the sliding portion acts, and a small amount of lubricant is present in the sliding portion. It becomes. When the leading end of the recording material P passes through the heating nip N, the fixing film 405 is pushed up so that the leading end of the recording material P squeezes the tube, and the lubricant is pushed out from the sliding portion.

  The lubricant pushed out from the sliding portion accumulates on the edges of the upstream and downstream heater guides 404 sandwiching the sliding portion, while sufficient lubrication is applied to the sliding portion of the essential fixing film 405. There will be no agent. With the recent increase in process speed, in order to soften the toner in a short time, the pressure applied to the heating nip N increases, and this tendency is remarkable. Therefore, even if an attempt is made to increase the slidability by heating the lubricant at the start, the effect cannot be obtained, and the drive motor 46 at the start requires a high torque.

  Incidentally, as described above, the pressure mechanism 420 shown in FIG. 3 releases the pressure applied to the heating nip N after the fixing device 40 is stopped in order to prevent the fixing roller 402 from being deformed. At this time, it can be expected that the lubricant deposited on the edges of the upstream and downstream heater guides 404 naturally flows into the sliding portion.

  However, in either case, the phenomenon that the lubricant in the sliding portion is depleted or the phenomenon that the heat-degraded developer stagnates in the sliding portion and the frictional resistance increases cannot be sufficiently prevented.

  Therefore, in the following embodiment, the lubricant movement mode in which the lubricant accumulated on the upstream edge of the heater guide 404 is forcibly moved to the sliding portion can be executed. In the first and second embodiments, after the processing job is finished, the fixing film 405 is stopped and the pressure is released, and then the fixing film 405 is rotated again. In the third embodiment, after the processing job is completed, the temperature of the belt to be cooled is detected by a thermistor, and the fixing film 405 is rotated at a timing when the viscosity of the lubricant reaches a certain standard.

<Example 1>
FIG. 7 is an explanatory diagram of lubricant movement in the lubricant movement mode of the first embodiment. In FIG. 7, (a) is a first pressure position during image formation, and (b) is a second pressure position in the lubricant movement mode. FIG. 8 is a flowchart of the lubricant movement mode according to the first embodiment.

  As shown in FIG. 7A, the lubricant is deposited on the portion A on the upstream side of the heater guide 404 during image formation. The pressure mechanism 420 presses the fixing film 405 to the pressure roller 402. The heater guide 404 and the heater 403 are brought into pressure contact with the elastic layer 402b of the pressure roller 402 through the fixing film 405, thereby forming a heating nip N having a predetermined length in the rotation direction of the fixing film 405. This position is defined as a first pressure position. In Example 1, the pressure between the fixing film 405 and the pressure roller 402 at the first pressure position was about 0.2 MPa.

  The heater 403 is a plate-like resistance heating element fixed at the center of the heater guide 404, and is disposed so as to recede 0.2 mm to 0.3 mm from the convex portion with respect to the fixing film 405. A pool of lubricant is formed at the boundary with 404. The size of the pool is 2 mm on the upstream side and the downstream side with respect to the heater 403 having a length in the rotation direction of 8 mm.

  The fixing film 405 rotates following the pressure roller 402. The lubricant is applied to a region corresponding to the heating nip N on the inner surface of the fixing film 405 at the initial stage of operation. During heating by the heater 403, the lubricant is softened, so that the lubricant is held on the inner surface of the fixing film 405 in a film shape, and the frictional force between the sliding portion of the fixing film 405 and the heater 403 is reduced.

  However, with the increase in the cumulative number of sheets to be fixed (image heating process) or the cumulative processing time (cumulative parameter), a lumped and stagnant lubricant pool is formed in the upstream portion A of the heater guide 404. The On the other hand, in the portion B adjacent to the surface of the heater 403 that forms a depression on the downstream side of the heater guide 404, the lubricant that does not change stagnates and the deterioration due to heating proceeds.

  Therefore, as shown in FIG. 7B, the lubricant movement mode control is executed, and the lubricant that has stagnated in the portion A adjacent to the surface of the heater 403 and in the portion A upstream of the heater guide 404 is stagnated. Move the agent. In the lubricant transfer mode, after the rotation of the fixing film 405 is stopped, the pressure mechanism 420 is operated to move the fixing film 405 away from the heater 403, and the fixing film 405 and the pressure roller 402 are brought into contact with a low pressure. This position is defined as a second pressure position. In Example 1, the pressure between the fixing film 405 and the pressure roller 402 at the second pressure position was set to 0.1 MPa or less.

  Then, at the second pressure position, the pressure roller 402 is rotated again, so that the fixing film 405 is rotated about 20 degrees with slip, and is deposited on the portion A on the upstream side of the heating nip N. The lubricant is moved to the portion B adjacent to the surface of the heater 403.

  In the lubricant movement mode, the fixing film 405 is separated from the heater guide 404 to secure a space for the lubricant to enter, so that the lubricant can be easily moved to the sliding portion between the heater 403 and the fixing film 405. Then, by changing the trajectory of the fixing film 405 in the vicinity of the heating nip N, the inner surface of the fixing film 405 can be brought into contact with the heat resistant grease deposited on the portion A.

  As shown in FIG. 8 with reference to FIG. 2, when the print job (processing job) that has reached the prescribed cumulative image forming number (1000 sheets) has been completed since the previous execution of the lubricant movement mode control, the lubricant movement is completed. Control of the mode is started. The controller 50 stops energization of the heater 403, stops driving the drive motor 46, and stops the rotation of the pressure roller 402 (S11). Then, immediately after the drive is stopped, the control unit 50 operates the pressure mechanism 420 to move the fixing film unit 401 from the first pressure position to the second pressure position (S12). Here, “immediately after stopping driving” means immediately after stopping the energization of the driving motor 46, and in the first embodiment, it is within one second.

  The controller 50 drives the drive motor 46 (S13) to drive the pressure roller 402 for a predetermined time Tn in order to promote the movement of the lubricant to the portion B on the back side of the heating nip N (S14). YES) The fixing film 405 is driven and rotated with slip by the frictional force between the outer surface of the fixing film 405 and the pressure roller 402.

  Since the fixing film 405 is in contact with the lubricant deposited on the portion A, as the fixing film 405 rotates, the lubricant deposited on the portion A is removed as shown in FIG. Move to part B. The predetermined time Tn for driving the pressure roller 402 is preferably set to a value larger than the time for the fixing film 405 to move the distance from the portion A to the portion B in consideration of the slip. In Example 1, it was set to 0.5 second.

  After the pressing roller 402 is stopped (S15) and a predetermined time T1 has elapsed (YES in S16), the control unit 50 operates the pressing mechanism 420 to move the fixing film unit 401 from the second pressing position. Move to the first pressure position (S17). By returning to the first pressure position, it is possible to reduce time loss to the printing operation due to the pressure operation at the start of the next print job.

  When the fixing film unit 401 is moved from the second pressurizing position to the first pressurizing position, the state where the lubricant is allowed to cool and the viscosity is increased is lubricated by the applied pressure compared to the state where the lubricant is warmed. The amount that the agent is pushed out is small. Therefore, in order to ensure a sufficient amount of lubricant retained in the portion B, the predetermined time T1 is a time for the lubricant to cool and solidify. In Example 1, since the fixing device 40 and the heat resistant grease HP-300 manufactured by Dow Corning Asia Co. were used, the predetermined time T1 was set to 60 seconds.

  Thereafter, when the stopped state continues for 10 minutes or more, the pressure mechanism 420 moves the fixing film unit 401 from the first pressure position to the second pressure position in order to prevent the pressure roller 402 from being deformed. .

  According to the control of the lubricant movement mode of the first embodiment, since an appropriate amount of lubricant can be held on the sliding portion between the heater 403 and the fixing film 405, the long-life fixing device 40 can be provided. By using the configuration for collecting the lubricant, an appropriate amount of lubricant can be held on the sliding portion of the heater 403 and the fixing film 405 without adding a lubricant, and the driving load can be reduced.

  According to the control of the lubricant movement mode of the first embodiment, since the lubricant movement mode is executed every 1000 sheets of fixing processing, fixing is performed as compared with the case where the lubricant movement mode is executed every time a print job is completed. The life of the device 40 can be extended. When the deterioration of the lubricant of the part A is kept small when the deterioration of the lubricant is small in a new state, the lubricant having a small deterioration of the part A when the deterioration of the lubricant of the part B progresses at the end of the life. B can be supplied. As a result, the deterioration of the lubricant stagnating on the surface of the heater 403 is delayed, and the slip effect that appeared on the fixed image after 200,000 sheets when the lubricant transfer mode is not performed exceeds 300,000 sheets. I can't get it.

  Instead of using the predetermined time T1, it is possible to reduce the waiting time loss of the next print job by returning to the first pressure position immediately after the driving of the pressure roller 402 is stopped. Further, the second pressurizing position may be waited until the next print job is started. In any case, the object of the present invention can be achieved.

  In addition, depending on the type of lubricant, the lubricant whose viscosity is lowered immediately after the heating is stopped travels along the inner surface of the fixing film 405 by gravity only by moving to the second pressure position and opening the heating nip N. Move to portion B shown in FIG. In this case, if the fixing film unit 401 is held at the second pressure position for a predetermined time, the effect of the lubricant movement mode can be obtained without driving the pressure roller 402.

<Example 2>
In the second embodiment, the same lubricant movement mode as in the first embodiment is executed in the fixing device 40 shown in FIG. 2, but the execution frequency control of the lubricant movement mode is different from that in the first embodiment.

  That is, in Example 1, the lubricant transfer mode is executed for every 1000 accumulated image formation sheets from the new state of the fixing device 40 to the end of its life. On the other hand, in the second embodiment, when the fixing device 40 is in a new state, the lubricant movement mode is performed less frequently, and the total cumulative amount of the fixing process increases and the deterioration of the lubricant progresses. Execute travel mode frequently.

  As shown in FIG. 2, the lubricant gradually deteriorates as the number of recording materials processed by the fixing device 40 increases. In particular, the viscosity of the lubricant tends to increase as the base oil content of the lubricant (heat resistant grease) decreases due to evaporation. Table 1 shows the weight of the base oil contained in the unit weight lubricant in the parts A and B shown in FIG. 7B after accumulating 200,000 sheets of images without performing the lubricant transfer mode. Indicates the ratio.

  As shown in Table 1, the lubricant in the portion B that is in contact with the surface of the heater 403 is directly heated by the heater 403, so that the reduction in the base oil content is promoted. On the other hand, since the lubricant in the portion A upstream of the heater guide 404 is not directly heated, the base oil content is reduced little.

  When the lubricant movement mode of the first embodiment is executed at the end of the print job, the base oil weight ratio between the part A and the part B approaches. For this reason, the lubricant viscosity of the sliding portion of the heater 403 and the fixing film 405 is kept low compared with the case where the lubricant transfer mode of Example 1 is not performed, and as a result, the driving torque of the pressure roller 402 is also low. Kept.

  However, when the fixing device 40 is in a new state, there is almost no deterioration of the lubricant, so that the lubricant transfer mode is set in a state where the weight ratio of the base oil is high and the viscosity of the lubricant is low, that is, in a situation where it is not actually necessary. It will be executed. On the contrary, at the end of the life of the fixing device 40, the deterioration of the lubricant is remarkably progressing, and the lubricant transfer mode is used even in a state where the weight ratio of the base oil is low and the lubricant viscosity is high, that is, in a situation to be executed immediately. Is not easily executed.

  Therefore, in the second embodiment, the execution interval of the lubricant movement mode is changed according to the cumulative number of image formations as shown in Table 2, and the execution interval is lengthened when the fixing device 40 is in a new state, while it is executed at the end of the life. The interval is shortened.

  As shown in FIG. 2, a counter 51 for determining the execution of the lubricant movement mode and a counter 52 for the total number of processed sheets are provided, and the control unit 50 performs the counter every time the fixing operation of the recording material P is performed one sheet. The counter values 51 and 52 are incremented by +1. When the counter value of the counter 51 exceeds the control execution interval corresponding to the number of sheets of the counter 52 shown in Table 2, the lubricant movement mode is executed in the same manner as in the first embodiment after waiting for the end of the print job. After execution of the lubricant movement mode, the counter value of the counter 51 is reset to zero.

  In the control (frequency control) of the lubricant movement mode according to the second embodiment, the lubricant movement mode is performed at an execution interval that becomes shorter according to the deterioration of the lubricant, instead of the constant execution interval as in the first embodiment. Thereby, the friction load of the sliding part of the heater 403 and the fixing film 405 can be kept low over a long period of time. When the base oil content of the lubricant in the part B is relatively large in a new state, the decrease in the base oil content in the lubricant in the part A can be suppressed. As a result, when the base oil content in the part B decreases at the end of the life, the part A The lubricant in which a large amount of the base oil is maintained can be supplied to the portion B. Therefore, the life of the fixing device 40 can be further extended as compared with the control in the first embodiment.

  In the second embodiment, the number of fixed images is used as the cumulative parameter of the image heating process for determining the execution interval of the lubricant movement mode. However, the same effect can be obtained by determining the cumulative drive time of the drive motor 46. Obtainable.

<Example 3>
FIG. 9 is an explanatory diagram of lubricant movement in the lubricant movement mode of the third embodiment. FIG. 10 is a flowchart of the lubricant movement mode according to the third embodiment. In Embodiment 3, the same lubricant movement mode as in Embodiment 1 is executed in the fixing device 40 shown in FIG. 2, but the rotation timing of the fixing film 405 executed at the second pressure position is different from that in Embodiment 1. Different.

  That is, in Example 1, the lubricant is fluidly recovered to the sliding portion by utilizing the low viscosity of the high-temperature lubricant (heat resistant grease) immediately after printing. On the other hand, in Example 3, the lubricant (heat resistant grease) that is cooled from a high temperature and increases in viscosity is scraped off by the convex portion of the heater guide 404 to be collected in the sliding portion. In the second embodiment, the thermistor TH that detects the temperature of the fixing film 405 is used as a means for detecting the recovery timing of the lubricant.

  As shown in FIG. 9A, the heater guide 404 is provided with a groove 404a for holding the lubricant. The depth of the groove 404a is not so deep, but is about 0.5 mm to 1.5 mm, and is installed in the entire region in the longitudinal direction. Japanese Laid-Open Patent Publication No. 2000-306655 discloses a configuration in which a groove for holding the lubricant is provided in the sliding portion for the purpose of maintaining an appropriate amount of lubricant in the sliding portion and extending the life. .

  In the heater guide 404, convex portions 404b and 404c are arranged in the entire area in the longitudinal direction on the upstream side and the downstream side in the rotation direction of the fixing film 405. The height of the convex portions 404b and 404c is set to 404b <404c. In the first pressurizing position in which the sandwiching pressure is increased, both the convex portions 404b and 404c abut against the fixing film 405. However, at the second pressurizing position where the sandwiching pressure is reduced, the downstream convex portion 404 c contacts the fixing film 405, while the upstream convex portion 404 b is separated from the fixing film 405.

  At the first pressure position, the upstream convex portion 404 b and the downstream convex portion 404 c of the heater guide 404 in the rotation direction of the fixing film 405 are in pressure contact with the fixing film 405. Therefore, the lubricant moves from the fixing film 405 to the heater guide 404 as the fixing film 405 rotates. The lubricant is dammed by the convex portion 404 b on the upstream side of the heater guide 404 and accumulates in the portion A upstream of the heating nip N, while being pushed out to the downstream side of the heating nip N by the pressure of the heating nip N.

  When the image formation is completed and the heating of the heater 403 is stopped, the temperature of the sliding portion decreases, the temperature of the lubricant decreases, and the viscosity increases as shown in FIG. For this reason, even if the pressurizing mechanism 420 is subsequently operated to move the fixing film 405 away from the heater 403, the lubricant does not return to the sliding surface between the heater 403 and the fixing film 405. For this reason, as described above, the lubricant cannot be sufficiently held in the sliding portion between the heater 403 and the fixing film 405, and the sliding property at the sliding portion is lowered.

  As shown in FIG. 10 with reference to FIG. 2, the control unit 50 stops energization of the heater 403 after the print job (S21), stops driving the drive motor 46, and stops the rotation of the pressure roller 402. (S22). The thermistor TH detects the temperature of the inner surface of the fixing film 405 that dissipates heat. When the detected temperature of the thermistor TH becomes equal to or lower than Tm (YES in S23), the controller 50 operates the pressure mechanism 420 to move the fixing film unit 401 from the first pressure position to the second pressure position. (S24).

  Here, the temperature Tm is a temperature at which the lubricant is allowed to cool and satisfies a certain viscosity. In Example 3, the temperature Tm was set to 60 ° C. from the relationship between the temperature and the viscosity shown in FIG.

  The control unit 50 operates the drive motor 46 to drive the pressure roller 402 for a predetermined time Tn, and the fixing film is moved by the frictional force with the surface of the fixing film 405 of the fixing film unit 401 moved to the second pressure position. 405 is rotated (S25).

  As shown in FIG. 7B, the convex portion 404c on the downstream side of the heater guide 404 in the rotation direction of the fixing film 405 is higher in the radial direction than the convex portion 404b on the upstream side. For this reason, the lubricant that has a certain viscosity and swells on the inner surface of the fixing film 405 is scraped off by the convex portions 404 c and collected in the portion B.

  After driving the pressure roller 402 for a predetermined time Tn (YES in S26), the controller 50 stops driving the drive motor 46 (S27). Thereafter, the pressure mechanism 420 moves the fixing film unit 401 from the second pressure position to the first pressure position (S28). By returning the fixing film unit 401 to the first pressure position, it is possible to reduce the loss of print waiting time due to the pressure operation during the next print job.

  In step S26, the driving time of the pressure roller 402 for rotating the fixing film 405 is set to Tn, but may be controlled by the rotation speed Nn (rotation angle ωn) of the pressure roller 402.

  According to the lubricant movement mode of the third embodiment, it is possible to provide a long-life fixing device 40 by continuously holding an appropriate amount of lubricant on the sliding portion of the heater 403 and the fixing film 405.

  In Example 1, the rotation amount of the belt member (405) through the lubricant movement mode is shorter than the length of the rubbing member (404) in the rotation direction. However, in Example 3, since the convex portion 404c collects the lubricant through the lubricant movement mode, the rotation amount of the belt member (405) may be one rotation or more.

<Example 4>
FIG. 11 is a flowchart of the lubricant movement mode according to the fourth embodiment. In the fourth embodiment, the same lubricant movement mode as in the first embodiment is executed in the fixing device 40 shown in FIG. 2, but the execution timing of the lubricant movement mode is different from that in the first embodiment.

  That is, in the first embodiment, the lubricant movement mode is executed immediately after printing, but in the fourth embodiment, the lubricant movement mode is executed at the start-up after the fixing device is left to cool. In the fourth embodiment, the grease solidified by cooling after the end of the print job is scraped off by the convex portion 404c of the heater guide 404 and collected in the portion B before the start of the next print job. .

  As shown in FIG. 10 with reference to FIG. 2, when the fixing film unit 401 is left in pressure contact with the pressure roller 402 by the pressure mechanism 420 for a long time, the elastic layer 402b of the roller 402 to be pressurized is Deform. When the elastic layer 402b of the pressure roller 402 is deformed, there is a problem in that a lateral band-like image defect occurs in the fixed image at the time of image formation every rotation cycle of the fixing roller.

  As a countermeasure, as described above, after the print job is finished, the pressure mechanism 420 is operated to move the fixing film unit 401 from the first pressure position to the second pressure position (S31). ).

  When the power is turned on after the fixing device 40 is turned off and cooled, the driving motor 46 is operated to rotate the pressure roller 402 for a predetermined time Tn, and the fixing film 405 is caused by frictional force with the outer surface of the fixing film 405. 405 is rotated (S32).

  As shown in FIG. 7B, the convex portion 404c on the downstream side of the heater guide 404 in the rotation direction of the fixing film 405 is higher in the radial direction than the convex portion 404b on the upstream side. Therefore, as in the case of Example 3, the lubricant that has cooled and swelled on the inner surface of the fixing film 405 is scraped off by the convex portions 404c and collected in the portion B.

  When the predetermined time Tn has elapsed (S33), the control unit 50 stops the drive motor 46 and then operates the pressure mechanism 420 to move the fixing film unit 401 from the second pressure position to the first pressure position. (S34).

  The controller 50 supplies power to the heater 403 to generate heat over the entire length in the longitudinal direction of the heater 403 (S35), and operates the drive motor 46 with a slight delay to rotate the pressure roller 402 (S36). The fixing film 405 is rotated by following the pressure roller 402, and then the control unit 50 waits for the temperature detected by the thermistor TH to converge to a predetermined temperature and starts image formation. The heater 403 is controlled to a predetermined temperature to control the temperature of the fixing film 405, and the printer is ready for printing.

  In step S33, the driving time of the pressure roller 402 for rotating the fixing film 405 is set to Tn, but may be controlled by the rotation speed Nn (rotation angle ωn) of the pressure roller 402.

  According to the lubricant movement mode of the fourth embodiment, it is possible to provide the long-life fixing device 40 by keeping an appropriate amount of lubricant on the sliding portion of the heater 403 and the fixing film 405.

<Other examples>
Japanese Unexamined Patent Publication No. 2001-14327 discloses a fixing device in which the heating means (403) shown in FIG. 2 is replaced with an induction heating device. Even in such a fixing device, the lubricant transfer modes of the first to fourth embodiments can be implemented. In this case, the fixing film 405 needs to be an electromagnetic induction heat generating film, and an exciting coil and a magnetic core that generate heat by applying a magnetic flux to the electromagnetic induction heat generating film can be used as heating means.

  Japanese Patent Application Laid-Open No. 2002-108119 discloses a fixing device in which the heating means (403) shown in FIG. 2 is replaced with a halogen lamp heater. Even in such a fixing device, the lubricant transfer modes of the first to fourth embodiments can be implemented.

  In Examples 1 to 4, the lubricant transfer mode was automatically executed after the accumulated parameter of the image heating process reached a predetermined amount. However, as shown in FIG. 2, a list of maintenance modes may be displayed through the operation panel 53, and the user may select the maintenance mode and manually execute the lubricant movement mode.

46 drive motor 50 control unit 51, 52 counter 53 operation panel 401 fixing film unit 402 drive member (pressure roller)
402a Metal shaft 402b Elastic layer 403 Heating means (heater)
404 Rubbing member (heater guide)
405 Belt member (fixing film)
406 Pressure member (stay)
420 Pressurizing mechanism N Heating nip P Recording material TH Thermistor

Claims (10)

A belt member having an inner surface coated with a lubricant, a drive member that contacts the outer surface of the belt member to rotate the belt member, and a friction member that slides on the inner surface of the belt member In an image heating apparatus comprising a rubbing member that sandwiches the belt member and a heating means for the belt member,
A pressurizing mechanism capable of changing the pressing force of the belt member sandwiched by the driving member and the rubbing member;
Control means capable of executing a lubricant movement mode in which the belt member is rotated by the driving member in a state where the pressing force applied by the pressing mechanism is lower than that during image heating. An image heating apparatus.   2. The image heating apparatus according to claim 1, wherein the lubricant movement mode is automatically executed after a cumulative parameter of the image heating process reaches a predetermined amount.   The image heating apparatus according to claim 2, wherein the lubricant movement mode is executed after completion of a processing job in which a cumulative parameter of the image heating processing reaches a predetermined amount.   The image heating apparatus according to claim 3, wherein the lubricant movement mode is executed more frequently as the total cumulative amount of cumulative parameters of the image heating process increases.   The image heating apparatus according to claim 4, wherein the lubricant movement mode is executed in a state where the temperature of the belt member is increased after the heating unit is stopped after the processing job is completed.   6. The image heating apparatus according to claim 5, wherein the lubricant movement mode is executed after the temperature of the rubbing member is lowered to a predetermined temperature.   The said lubricant movement mode reduces the applied pressure of the said pinching after stopping rotation of the said drive member, and rotates the said drive member again after that. Image heating device.   The lubricant movement mode rotates the belt member with slip with respect to the drive member, and the rotation amount of the belt member through the lubricant movement mode is shorter than the length of the rubbing member in the rotation direction. The image heating apparatus according to claim 1, wherein:   The rubbing member has convex portions in the longitudinal direction on the upstream side and the downstream side in the rotation direction of the belt member, and both the convex portions abut against the belt member in a state where the pressing force is increased. The downstream convex portion contacts the belt member in a state where the clamping pressure is reduced, and the upstream convex portion is separated from the belt member. The image heating apparatus according to any one of the preceding claims. The heating means is a plate-like resistance heating element that is fixed to the center of the rubbing member in the rotation direction of the belt member and rubs against the inner surface of the belt member,
The heating means is disposed with respect to the belt member so as to recede from the convex portion of the rubbing member, whereby a lubricant pool is formed at the boundary between the rubbing member and the heating means. The image heating apparatus according to claim 9.

Images