JP6620936B2 - Fixing device, image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus in a copying machine, a printer, a facsimile, or a complex machine including the fixing device.

  In an image forming apparatus in a copying machine, a printer, a facsimile, or a complex machine thereof, as a fixing device for fixing an unfixed toner image on a recording medium, a heat roller method, a film heating method, an electromagnetic induction heating method, etc. Contact heating type fixing devices are widely used.

  As an example of such a fixing device, a belt-type fixing device (for example, Patent Document 1) and a surf fixing (film fixing) fixing device (for example, Patent Document 2) using a ceramic heater are known.

  Further, in the fixing device of Patent Document 3, in order to heat a large-sized recording medium such as an A3 Nobi size, an end heater for heating the end of the large-sized recording medium is provided in addition to the halogen heater. The end heater is accommodated in the heater holding portion.

  By the way, in the fixing device using the end heater as described above, when a rotation abnormality of the fixing belt occurs, as a result of heating only a specific portion of the fixing belt by the end heater, However, there is a problem that the temperature gradient increases and the heated portion undergoes thermal deformation.

  In order to solve the above problems, the present invention is provided in a rotatable fixing member, a heating source for heating the fixing member, a nip forming member for pressing the fixing member from the inside thereof, and the nip forming member, An end heating source that heats the fixing member; a rotation detection mechanism that detects a rotation speed of the fixing member; and a temperature detection mechanism that detects a temperature at a position corresponding to the end heating source of the fixing member. The end heating source heats a position corresponding to the end of the maximum passage region of the recording medium in the width direction of the fixing member, and the rotation speed of the fixing member detected by the rotation detection mechanism The heating by the edge heating source is controlled.

  In the fixing device of the present invention, a rotation detecting mechanism for detecting the rotation speed of the fixing member is provided, and heating of the end heating source is controlled by the rotation speed of the fixing member. As a result, even when a rotation abnormality occurs in the fixing member, it is possible to control the end heating source in accordance with the rotation speed of the fixing member, such as detecting a decrease in the rotation speed of the fixing member and reducing the heating amount by the heating source. It becomes possible.

1 is a schematic configuration diagram of an image forming apparatus. 1 is a schematic configuration diagram of a fixing device. FIG. 4 is a perspective view illustrating a configuration of an end portion in the width direction of the fixing belt. It is a figure which shows the width direction position of the heat source of a fixing device. FIG. 4 is a diagram illustrating a positional relationship in the width direction of each member provided in the fixing device. It is a figure which shows the detection mechanism provided in the fixing device of this embodiment. FIG. 3 is a schematic diagram illustrating an arrangement of a temperature detection mechanism provided in the fixing device. FIG. 4 is a schematic diagram illustrating an arrangement of a rotation detection mechanism provided in the fixing device. It is a figure which shows the threshold value of the emitted-heat amount of the edge part heater for every rotation speed of a fixing belt.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

  In the center of the color image forming apparatus 1 shown in FIG. 1, an image forming unit 2 in which four process units 9Y, 9M, 9C, 9Bk are detachably provided is arranged. Each process unit 9Y, 9M, 9C, 9Bk contains developers of different colors of yellow (Y), magenta (M), cyan (C), and black (Bk) corresponding to the color separation components of the color image. The configuration is the same except that.

  Specifically, each process unit 9 includes a photosensitive drum 10 that is a drum-like rotating body capable of carrying toner as a developer on the surface, and a charging roller 11 that uniformly charges the surface of the photosensitive drum 10. And a developing device 12 having a developing roller 13 for supplying toner to the surface of the photosensitive drum 10.

  At the top of the image forming apparatus 1, toner bottles 26Y, C, M, and Bk filled with yellow, cyan, magenta, and black toners are detachably provided. Each color toner is supplied to each color developing device 12 through a supply path provided between the toner bottles 26Y, 26C, 26M, and Bk and each developing device 12.

  Below the process unit 9, the exposure unit 3 is arranged. The exposure unit 3 is configured to emit laser light based on the image data.

  A transfer unit 4 is disposed above the image forming unit 2. The transfer unit 4 is opposed to the endless intermediate transfer belt 16 stretched around the driving roller 14 and the driven roller 15 so as to be able to run around, and the photosensitive drum 10 of each process unit 9 sandwiching the intermediate transfer belt 16 therebetween. The primary transfer roller 17 is disposed at the position. Each primary transfer roller 17 presses the inner peripheral surface of the intermediate transfer belt 16 at each position, and a primary transfer nip is formed at a place where the pressed portion of the intermediate transfer belt 16 and each photosensitive drum 10 come into contact. Has been.

  A secondary transfer roller 18 is disposed at a position opposite to the drive roller 14 of the intermediate transfer belt 16 and the drive roller 14 across the intermediate transfer belt 16. The secondary transfer roller 18 presses the outer peripheral surface of the intermediate transfer belt 16, and a secondary transfer nip is formed at a location where the secondary transfer roller 18 and the intermediate transfer belt 16 are in contact with each other.

  The paper feed unit 5 is located below the image forming apparatus 1 and includes a paper feed cassette 19 that stores paper P as a recording medium, a paper feed roller 20 that carries the paper P out of the paper feed cassette 19, and the like. ing.

  The conveyance path 6 is a conveyance path that conveys the paper P carried out from the paper feeding unit 5, and the conveyance roller pair is located in the middle of the conveyance path 6 until it reaches the paper discharge unit 8 described later in addition to the pair of registration rollers 21. Are appropriately arranged.

  The fixing device 7 includes a fixing belt 30 as a fixing member that is heated by a heat source, a pressure roller 31 that can press the fixing belt 30, and the like.

  The paper discharge unit 8 is provided on the most downstream side of the conveyance path 6 of the image forming apparatus 1. The paper discharge unit 8 is provided with a pair of paper discharge rollers 24 for discharging the paper P to the outside and a paper discharge tray 25 for stocking the discharged paper P.

  The basic operation of the image forming apparatus 1 will be described below with reference to FIG.

  In the image forming apparatus 1, when an image forming operation is started, an electrostatic latent image is formed on the surface of the photosensitive drum 10 of each process unit 9Y, 9C, 9M, 9Bk. The image information exposed to each photosensitive drum 10 by the exposure unit 3 is single-color image information obtained by separating a desired full-color image into color information of yellow, cyan, magenta, and black. An electrostatic latent image is formed on each photosensitive drum 10, and toner stored in each developing device 12 is supplied to the photosensitive drum 10 by a drum-shaped developing roller 13. It is visualized as a toner image (developer image) that is a visible image.

  In the transfer unit 4, the intermediate transfer belt 16 is driven to run in the direction of arrow A in the figure by the rotational drive of the drive roller 14. Further, each primary transfer roller 17 is applied with a constant voltage or a constant current-controlled voltage having a polarity opposite to the charging polarity of the toner. As a result, a transfer electric field is formed in the primary transfer nip, and the toner images formed on the respective photosensitive drums 10 are sequentially superimposed and transferred onto the intermediate transfer belt 16 in the primary transfer nip.

  On the other hand, when the image forming operation is started, the sheet P stored in the sheet feeding cassette 19 is moved to the transport path 6 by rotating the sheet feeding roller 20 of the sheet feeding unit 5 below the image forming apparatus 1. Sent out. The sheet P sent to the conveyance path 6 is timed by the registration roller 21 and is sent to the secondary transfer nip between the secondary transfer roller 18 and the drive roller 14. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 16 is applied, and a transfer electric field is formed in the secondary transfer nip. The toner images on the intermediate transfer belt 16 are collectively transferred onto the paper P by the transfer electric field formed in the secondary transfer nip.

  The sheet P on which the toner image is transferred is conveyed to the fixing device 7, and the sheet P is heated and pressed by the fixing belt 30 and the pressure roller 31, and the toner image is fixed on the sheet P. Then, the paper P on which the toner image is fixed is separated from the fixing belt 30, transported by a pair of transport rollers, and discharged to the paper discharge tray 25 by the paper discharge roller 24 in the paper discharge unit 8.

  The above description is an image forming operation when a full color image is formed on the paper P. A single color image can be formed using any one of the four process units 9Y, 9C, 9M, and 9Bk. It is also possible to form two or three color images using two or three process units 9.

  Next, the configuration of the fixing device 7 of this embodiment will be specifically described. The fixing device 7 is provided with a rotatable fixing belt 30, a pressure roller 31 as a pressure member disposed opposite to the fixing belt 30, and halogen heaters 32 a and 32 b as heating sources.

  Inside the fixing belt 30, a nip forming member 33 that forms a nip N with the pressure roller 31 via the fixing belt 30, and a heat equalizing member 34 provided between the fixing belt 30 and the nip forming member 33. And a stay 35 for supporting the nip forming member 33 from the opposite side of the nip N, a reflecting member 36 for reflecting radiant heat from the halogen heater 32, and the like.

  The fixing belt 30 is constituted by an endless belt or a film using a metal material such as nickel or SUS or a resin material such as polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. An elastic layer formed of a silicone rubber layer or the like may be provided between the base material of the belt and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, minute irregularities on the belt surface are transferred to the image, and the image has a crusty skin shape. There may be a problem that the gloss unevenness (skin skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the skin image is improved.

  The pressure roller 31 is provided with an elastic rubber layer 312 on the outer side of the core 311 and a release layer (PFA or PTFE layer) on the outer peripheral surface side in order to obtain releasability. The pressure roller 31 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. The pressure roller 31 is pressed against the fixing belt 30 by a spring or the like, and has a predetermined nip width when the elastic rubber layer 312 is crushed and deformed. The pressure roller 31 may be a hollow roller, and the pressure roller 31 may be provided with a heating source such as a halogen heater. The elastic rubber layer 312 may be solid rubber, but if there is no heater inside the pressure roller 31, sponge rubber may be used. Sponge rubber is more desirable because it increases heat insulation and makes it difficult for the fixing belt to lose heat.

  The rotation of the pressure roller 31 is transmitted to the fixing belt 30 at the fixing nip N by the rotation of the pressure roller 31, and the fixing belt 30 is rotated by the pressure roller 31.

  The stay 35 supports the nip forming member 33 that receives pressure from the pressure roller 31 in the fixing nip N from the opposite side of the fixing nip N. Thereby, the nip forming member 33 is prevented from being bent and a uniform nip width in the axial direction is obtained.

  As shown in FIG. 3, the fixing belt 30 and the stay 35 are held by flanges 41 as holding members at both ends in the width direction. The fixing belt 30 is rotatably held by the flange 41, and runs around while being guided by the flange 41 by the driven rotation.

  A slip ring 42 that protects the end portion of the fixing belt 30 is provided between the end surface of the fixing belt 30 and the facing surface of the flange 41 that faces the fixing belt 30. As a result, when the fixing belt 30 is displaced in the axial direction, it is possible to prevent the end portion of the fixing belt 30 from coming into direct contact with the flange 41 and to prevent the end portion from being worn or damaged.

  A reflective member 36 is provided between the stay 35 and the halogen heater 32. The reflection member 36 reflects the radiant heat flowing from the halogen heater 32 toward the stay 35 toward the fixing belt 30. Thereby, useless energy consumption can be suppressed and the fixing belt 30 can be efficiently heated. Instead of providing the reflecting member 36, the surface of the stay 35 may be subjected to heat insulation treatment or mirror treatment so that the stay 35 reflects radiant heat from the halogen heater 32.

  FIG. 4 is a schematic diagram for explaining the arrangement in the width direction of the heat generating part and the end heater provided in the halogen heater for heating the fixing belt 30. Hereinafter, the center in the width direction of the fixing belt 30 is defined as the inner side in the width direction, and the end in the width direction of the fixing belt 30 is defined as the outer side in the width direction.

  The fixing device has a heat generating part h1 at the center in the width direction, a halogen heater 32a for heating the center in the width direction of the fixing belt 30, and a halogen heater 32b having a heat generating part h2 at both ends in the width direction. Provided.

  When a small size paper P such as a postcard size or A4 vertical size is passed through the fixing device, only the halogen heater 32a generates heat, and when a large size paper P such as an A3 size is passed. Both the halogen heaters 32a and 32b generate heat. The heating area of the halogen heater 32 is provided with a width corresponding to the width L1 of the A3 size paper.

  In addition, the fixing device of the present embodiment is provided with an end heater 37 as an end heating source in order to cope with A3 Nobi size paper (paper width L2) which is the maximum size paper to be passed. The sheet width L2 is the maximum sheet passing area (maximum passing area of the recording medium) of the fixing device.

  The end heater 37 is provided outside the A3 size paper width L1 (outside in the width direction of the heat generation part h2 of the halogen heater 32b) and at a position corresponding to the end of the A3 nobi size paper. The end heater 37 is provided so that the heat generating portion h2 partially overlaps the region in the width direction. In the case where an A3 size paper is passed through the fixing device, the end heater 37 generates heat in addition to the halogen heaters 32a and 32b. As described above, the end heater 37 generates heat only in the case of the maximum size A3 Nobi size paper, and the halogen heaters 32a and 32b mainly heat the other side of the paper and the center side of the A3 Novi size paper. It is a heating source.

  Instead of the end heater 37 of the present embodiment, the heat generating portion h2 of the halogen heater 32b can be provided with a width corresponding to the A3 Nobi size paper width L2. However, in this case, for example, when an A3 size sheet is passed, not only the non-sheet passing region at the end in the width direction of the fixing belt 30 is heated and the problem of an increase in the end temperature occurs, but also excess energy Consumption will occur.

  In the present embodiment, it is possible to set a heat generation range in accordance with the width of each A3 size paper and A3 size paper, and there is a problem that the end temperature of the fixing belt 30 rises even when the A3 size paper is passed. Will not occur. In this embodiment, an A3 size paper is set as an example of the paper having the largest paper width that is passed through the fixing device, and an A3 size paper is set as an example of the maximum paper size supported by the heat generation unit h2. The size of is not limited to this. For example, assuming that the end heater 37 corresponds to a size larger than A3 size paper, the area of the heat generating portion h2 may be set in accordance with the paper width smaller than that.

  A soaking member 34 is provided facing the fixing belt 30. The heat equalizing member 34 is provided over the width direction of the fixing belt 30, and moves the heat in the width direction to make the temperature of the fixing belt 30 uniform in the width direction. The soaking member 34 is made of copper, aluminum, silver or the like having a high thermal conductivity in order to facilitate heat transfer in the width direction. Moreover, it is desirable to use copper in consideration of cost, processing surface, and the like.

  FIG. 5 is a schematic diagram showing the positional relationship of each member. The upper side of the figure is the fixing nip N side, and the lower side of the figure is the inner side of the fixing belt 30.

  Concave portions 331 are provided at both ends in the width direction of the nip forming member 33, and the end heaters 37 are accommodated in the respective concave portions 331. The end heater 37 heats the end in the width direction of the fixing belt 30 at the position of the fixing nip N via the heat equalizing member 34.

  Next, each detection mechanism provided in the fixing device will be described.

  As shown in FIG. 6, the fixing device 7 includes a temperature detection mechanism 38 for detecting the surface temperature of the fixing belt 30 and a rotation detection for detecting the rotation amount (or rotation speed) of the fixing belt 30 of the fixing belt 30. A mechanism 39 is provided. The temperature detection mechanism 38 is provided at a position facing the halogen heater 32b. By providing the temperature detection mechanism 38 in the vicinity of the fixing nip N on the upstream side in the rotation direction of the fixing nip N, it is possible to detect the temperature of the fixing belt 30 under conditions closer to the temperature of the fixing belt 30 in the fixing nip N. it can.

  As shown in FIG. 7, a temperature detection mechanism 38 is provided at the end of the fixing belt 30 in the width direction at a position corresponding to the end heater 37 in the width direction. The temperature detection mechanism 38 detects the temperature of the fixing belt 30 heated by the end heater 37. The end heater 37 adjusts the heating amount of the end heater 37 based on the detection result of the temperature detection mechanism 38, and prevents an excessive temperature increase at the end of the fixing belt 30.

  When the fixing belt 30 is clogged with the flanges 41 provided at both ends of the fixing belt 30 and the rotation is stopped (or decelerated) due to some trouble, the end heater 37 is fixed to the fixing belt 30. Only a part in the circumferential direction is heated, and the temperature of that part rises rapidly. Particularly, in the case of the fixing belt 30 that does not have an elastic layer as in the present embodiment, the heat capacity of the fixing belt 30 is small, and heating only a part of the fixing belt 30 causes overheating of the portion. It's easy to do. The excessive temperature rise causes a problem such that only a part of the fixing belt 30 is thermally deformed.

  At this time, merely detecting the surface temperature of the fixing belt 30 and adjusting the heating amount by the end heater 37 cannot quickly cope with the excessive temperature rise of the fixing belt 30. That is, when the fixing belt 30 stops rotating (or decelerates) due to abnormal rotation or the like, the end heater 37 continues to heat the fixing belt 30 via the heat equalizing member 34. Then, the heating of the end heater 37 causes the surface of the fixing belt 30 to overheat, and the temperature detecting mechanism 38 detects this overheated temperature, thereby stopping the heating of the end heater 37 for the first time (or the heating amount). Signal). As described above, even when the rotation speed of the fixing belt 30 is decreased, the heating by the end heater 37 is continued, and a time difference is generated until the heating amount of the end heater 37 is decreased. Further, it is not possible to sufficiently prevent an excessive temperature rise of the fixing belt 30.

  Therefore, in the present embodiment, by providing the above-described rotation detection mechanism, a decrease in the rotation speed of the fixing belt 30 is detected, and control for reducing the heating amount of the end heater 37 or stopping the heating is performed based on the detection result. ing.

  The rotation detection mechanism 39 is a reflective photosensor having a light emitting part and a light receiving part. As shown in FIG. 8, a reflective portion 40 is provided at a position facing the rotation detection mechanism 39 in a partial region in the circumferential direction of the fixing belt 30.

  In order to detect the rotation of the fixing belt 30, first, light is emitted from the light emitting unit of the rotation detection mechanism 39. The irradiated light is reflected by the reflecting portion 40 of the fixing belt 30, and this reflected light is received by the light receiving portion of the rotation detection mechanism 39. As a result, it is possible to detect that the reflection unit 40 has passed through the facing position of the rotation detection mechanism 39 due to the rotation of the fixing belt 30. The rotation detection mechanism 39 can detect the rotation speed (rotation speed) of the fixing belt 30 by measuring the detection frequency (passage frequency) by the light receiving unit.

  As described above, the rotation detection mechanism 39 can detect the rotation of the fixing belt 30 without contact with the fixing belt 30, and the rotation detection mechanism 39 fixes the surface by scratches on the surface of the fixing belt 30 or friction with the rotation detection mechanism 39. Wear on the surface of the belt 30 can be prevented.

  The configuration of the rotation detection mechanism is not limited to the reflection type photosensor described above, and any method capable of detecting the rotation speed (rotation speed) of the fixing belt 30 can be selected, and a predetermined marking position provided on the fixing belt 30 can be selected. It can be set as the structure which reads (the part corresponded to the reflection part of this embodiment). Moreover, it can also be set as a contact-type rotation detection mechanism.

  The rotation detection mechanism 39 and the reflection part 40 are provided on the outer side in the width direction from the maximum sheet passing region L <b> 2 of the paper P on the end side in the width direction of the fixing belt 30. By preventing the sheet from passing through the position of the reflection unit 40, the reflection unit 40 can be prevented from affecting the toner image on the sheet P.

  FIG. 9 is a graph showing the heating amount of the end heater 37 for each rotation speed of the fixing belt 30 detected by the rotation detection mechanism 39. The abscissa represents the rotational speed from 0 to 100%, and the ordinate represents the amount of heat generated by the end heater 37 from 0 to 100%.

  In the present embodiment, the permissible amount of heat generated by the end heater 37 is different for each rotation speed (the amount of heat generated at the position of the straight line in the figure), and the amount of heat generated by the end heater 37 is greater than the permissible amount (see FIG. In this case, the end heater 37 is stopped, for example, so that the amount of generated heat is reduced or the heat generation is stopped.

  As for the heat generation amount of the end heater 37 shown on the vertical axis in FIG. 9, the maximum heat generation amount is 100%. In addition, the maximum rotation speed of the fixing belt 30 can be set as the rotation speed 100% (hereinafter referred to as the reference speed V1) shown on the horizontal axis, but not limited to this, an arbitrary rotation speed can be set. it can. That is, the rotational speed at which it is determined that an abnormality has occurred in the rotation of the fixing belt 30 is set as the reference speed V1, and when the rotational speed of the fixing belt 30 becomes lower than this speed, the heating amount by the end heater 37 is limited. be able to.

  In this embodiment, it is set so that the allowable amount of heat generated by the end heater 37 decreases as the rotational speed decreases (see the straight line in the figure). At the rotational speed V0 or lower, the end heater 37 generates heat. Stop.

  On the other hand, it is possible to add only control for stopping the heat generation of the end heater 37 at a speed equal to or lower than a specific rotation speed (for example, the rotation speed V0 in the present embodiment). Even when an abnormality occurs and the rotation speed gradually decreases, the heat generation of the end heater 37 cannot be restricted at a stage where the rotation speed is higher than the speed V0, and the fixing belt 30 is excessively heated. It cannot respond quickly. Further, when the fixing belt 30 continues to rotate at a rotational speed greater than the rotational speed V0 and at a speed much smaller than the target rotational speed, the heating by the end heater 37 is continued.

  In the present embodiment, the amount of heating by the end heater 37 is limited little by little as the rotation speed of the fixing belt 30 decreases, and the speed gradually decreases due to abnormal rotation of the fixing belt 30. Even in such a case, heat generation by the end heater 37 can be limited early. Even when the rotation of the fixing belt 30 does not stop and rotates at a predetermined speed or more, the amount of heat generated by the end heater 37 can be limited to prevent overheating of the fixing belt 30.

  In the present embodiment, the allowable amount of heat generated by the end heater 37 is linearly decreased with respect to the decrease in the rotation speed of the fixing belt 30. However, the present invention is not limited to this. For example, the allowable amount of heat generated by the end heater 37 may be decreased exponentially, or the amount of heat generated by the end heater 37 may be increased step by step for each predetermined rotation speed of the fixing belt 30. May be reduced.

  Further, in this embodiment, when the fixing belt 30 is deformed or extremely shifted in the width direction, or when the end portion is damaged, the reflecting portion 40 does not face the rotation detection mechanism 39, and the fixing is performed. The rotation of the belt 30 cannot be detected. As a result, it is determined that an abnormality has occurred in the rotation of the fixing belt 30, and heating of the end heater 37 can be stopped.

  A plurality of reflecting portions 40 of the fixing belt 30 may be arranged in the circumferential direction or the axial direction of the fixing belt 30. Thereby, the rotation detection mechanism 39 can detect the rotation speed of the fixing belt 30 with higher accuracy.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile, or a complex machine thereof.

  Examples of the recording medium include paper P (plain paper), thick paper, postcard, envelope, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet, and the like.

  In the above-described embodiment, the fixing device provided with the two heaters of the halogen heaters 32a and 32b has been described. However, the fixing device is not limited to this and may be one, or three or more.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 7 Fixing apparatus 30 Fixing belt (fixing member)
31 Pressure roller 32a Halogen heater (heating source)
32b Halogen heater (heating source)
33 Nip forming member 37 End heater (end heating source)
38 Temperature detection mechanism 39 Rotation detection mechanism 40 Reflector

JP 2004-286922 A Japanese Patent No. 2861280 JP 2014-178370 A

Claims (6)

A rotatable fixing member;
A heating source for heating the fixing member;
A nip forming member that presses the fixing member from the inside;
An end heating source provided on the nip forming member for heating the fixing member;
A rotation detection mechanism for detecting the rotation speed of the fixing member;
A temperature detection mechanism for detecting a temperature at a position corresponding to the end heating source of the fixing member;
The end heating source heats a position corresponding to an end of the maximum passage area of the recording medium in the width direction of the fixing member,
The fixing device, wherein heating by the end heating source is controlled based on the number of rotations of the fixing member detected by the rotation detection mechanism.   The fixing device according to claim 1, wherein a heating amount by the end portion heating source is reduced as the rotational speed is reduced.   The fixing device according to claim 1, wherein heating of the end heating source is stopped in a state where rotation of the fixing member is not detected. A reflection part that reflects light is provided on a part of the fixing member in the circumferential direction,
4. The fixing device according to claim 1, wherein the rotation detection mechanism is a reflection type photosensor, and detects the number of rotations of the fixing member by receiving light from the reflection portion. 5. When the width direction center side of the fixing member is the width direction inner side and the width direction end portion side of the fixing member is the width direction outer side,
The fixing device according to claim 4, wherein the reflection portion is provided on the outer side in the width direction than the maximum passage region of the recording medium.   An image forming apparatus comprising the fixing device according to claim 1.

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