JP2015081946A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

[PROBLEMS] To prevent wear generated on the surface of a fixing belt in the axial direction, and to make the fixing belt thick by a belt stopper, and to be damaged early by repeated bending due to curvature change during rotation of the fixing belt. Provided is a fixing device capable of avoiding this. A rotatable endless fixing belt, a pressure rotating body provided to face the fixing belt and pressurizing the fixing belt, and an inner peripheral side of the fixing belt. The fixing belt 11 is provided separately from the nip forming member 31 that forms the fixing nip portion 41 that contacts the pressure rotator 21 via the belt 11 and sandwiches the recording medium P carrying the toner image. The fixing device 6 includes end flanges 61 and 61 as belt stopper members that contact the side end portions of the fixing belt 11 and regulate the position of the fixing belt 11 in the rotation axis direction X. It has a moving mechanism 100 that moves the end flanges 61 and 61 in the rotation axis direction X without interlocking with the position near the belt. [Selection] Figure 3

Description

  The present invention relates to a fixing device and an image forming apparatus, and more particularly to a fixing device provided in an image forming apparatus such as a printer, a copier, a facsimile machine, a plotter, or a multifunction machine having a plurality of functions thereof.

In recent years, there has been a strong market demand for energy saving and high speed for image forming apparatuses such as printers, copiers, facsimiles, plotters, and the like, or multifunction peripherals having a plurality of functions. In an image forming apparatus, an image forming process such as electrophotographic recording, electrostatic recording, magnetic recording, or the like is used. Printing paper, photosensitive paper, electrostatic recording, in which an unfixed toner image is a sheet-like recording medium by an image transfer method or a direct method Formed on paper and the like. As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely used.
Among them, various belt-type fixings that shorten the start-up time of the fixing device and reduce power consumption by adopting a thin fixing belt with a low heat capacity as the fixing member of the fixing device. An apparatus has been proposed (see, for example, Patent Document 1). Here, the start-up time of the fixing device means a time required from a normal temperature state such as when the power is turned on to a predetermined temperature (reload temperature) at which image formation / printing can be performed.

  In the belt type fixing device, in recent years, the start-up time has been further shortened and the first print time (the time from the receipt of a print request to the completion of printing through printing preparation and the completion of the first sheet discharge) has been reduced. Shortening is desired (hereinafter referred to as “conventional problem 1”). Further, as the speed of the image forming apparatus increases, the number of sheets to be passed per unit time increases and the required heat amount increases, so that there is a problem that the heat amount is insufficient at the beginning of continuous printing (so-called temperature drop). (Hereinafter referred to as “conventional issue 2”).

  In order to solve the above conventional problems 1 and 2, there has been proposed a fixing device that achieves the following effects by using an endless belt as a fixing belt. That is, the entire fixing belt can be heated, the first print time can be shortened, and the shortage of heat at the time of high-speed rotation can be solved, so that excellent fixing properties can be obtained even when mounted on a high-production image forming apparatus. Such a fixing device has been proposed (for example, Patent Document 2).

  In such a belt-type fixing device, an end burr caused by cutting of a recording medium passing through the fixing nip, a separation claw that slides on the fixing belt, a contact-type temperature sensor, etc. It is known that wear occurs on the surface at various positions. When the belt surface layer is worn away due to wear, a fixing failure of the toner image occurs. Therefore, various means for preventing a reduction in the service life of the fixing device due to local wear have been proposed (for example, Patent Document 3). . “Sliding” means sliding in contact.

In Patent Document 3, belt stopper members are provided on both sides of the fixing belt in the rotation direction, and a heating roller (belt conveying roller) is reciprocated in the axial direction, whereby the fixing belt is heated via the belt stopper member. It is reciprocated in the axial direction following and interlocking with the movement of
When the fixing belt is configured as in Patent Document 3, the fixing belt may be damaged early. For example, when the fixing belt is thin and has a small diameter configuration in order to reduce the heat capacity, the curvature of the fixing belt greatly changes with rotation, for example, the small diameter fixing belt passes through a flat fixing nip portion. In such a configuration, the fixing belt becomes thick due to a belt stopper provided inside the fixing belt, and the fixing belt is damaged early due to repeated bending caused by a change in curvature. Proposals for solving such problems have already been made (see, for example, Patent Document 4).

  However, in Patent Document 4, the fixing belt moves only in the rotation axis direction (belt width direction) of the fixing belt by its own “belt shift” within a range limited by the fixed belt stopper member. Therefore, there is a problem that it is not possible to sufficiently prevent the occurrence of wear on the surface of the fixing belt at a local position in the axial direction.

  The present invention has been made to solve the above-described problems, and the objects thereof are as follows. While preventing wear on the surface of the fixing belt in the axial direction, the fixing belt is thickened by the belt retaining member, and is damaged early due to repeated bending due to the curvature change during rotation of the fixing belt. An object of the present invention is to provide a fixing device capable of avoiding this.

In order to achieve the above object, the present invention adopts the following characteristic means / invention specific items (hereinafter referred to as “configuration”).
The present invention provides a rotatable endless fixing belt, a pressure rotating body that is provided to face the fixing belt and pressurizes the fixing belt, and is provided on an inner peripheral side of the fixing belt. A nip forming member that forms a nip portion that contacts the pressure rotator through which a recording medium carrying a toner image is sandwiched is provided separately from the fixing belt, and is provided at a side end of the fixing belt. A belt stopper member that contacts and regulates a position in a belt width direction orthogonal to the rotation direction of the fixing belt, wherein the belt stopper is not interlocked with the position of the fixing belt. It has a moving mechanism which moves a member in the belt width direction.

  According to the present invention, it is possible to prevent wear generated on the surface of the fixing belt at a local position in the belt width direction, and the fixing belt is thickened by the belt stopper member, and is repeatedly bent due to a curvature change during rotation of the fixing belt. It is possible to avoid being damaged early.

1 is a schematic overall configuration diagram of an image forming apparatus showing an embodiment of the present invention. 1 is a cross-sectional view of a main part of a fixing device showing Embodiment 1. FIG. FIG. 2 is a diagram of the fixing device according to the first exemplary embodiment as viewed from the exit side in the recording medium conveyance direction, and is a plan view of a main part illustrating a state at the start of movement of the fixing belt by a moving mechanism. FIG. 2 is a diagram of the fixing device according to the first exemplary embodiment as viewed from the exit side in the recording medium conveyance direction, and is a plan view of a main part showing a state when the movement of the fixing belt by the moving mechanism is completed. FIG. 3 is a cross-sectional view around the end flange of the first embodiment. FIG. 10 is a plan view for explaining the principle of Modification 1 and explaining the relationship between the inclination of the pressure rotator and the belt side of the fixing belt. FIG. 9 is a cross-sectional front view in which a part of the parallelism adjusting mechanism of the fixing device showing Modification Example 1 is broken. It is a partial cross section front view explaining the contact detection switch which comprises the belt speed detection means which shows the modification 4. (A) is a partial cross-sectional front view for explaining a contact detection switch in an off state, and (b) a contact detection switch in an on state. FIG. 10 is a control block diagram for performing movement speed control of a fixing belt according to Modification 4; FIG. 10 is a plan view of a main part illustrating a state when the fixing device according to the second exemplary embodiment is viewed from the exit side in the recording medium conveyance direction and when the movement of the fixing belt is started by the moving mechanism. FIG. 9 is a plan view of a main part showing a state when a fixing belt movement is completed by a moving mechanism, when the fixing device of Embodiment 2 is viewed from the exit side in the recording medium conveyance direction. FIG. 10 is a plan view of a main part when the fixing device of Embodiment 3 is viewed from an exit side in a recording medium conveyance direction. (A) is sectional drawing around a belt stopper member, (b) is an expanded sectional view of the principal part which shows the arrangement | positioning state of the stopper rotation guide fixed to the edge part flange and the belt stopper member. FIG. 6 is a plan view of a main part when the fixing device of Embodiment 4 is viewed from the exit side in the recording medium conveyance direction. It is a top view of the principal part which shows the state which removed the 1st belt stopper member from FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. In the embodiments and modifications, components (members and components) having the same function and shape are denoted by the same reference numerals as long as there is no risk of confusion, and description thereof is omitted.

  First, an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic overall configuration diagram of an image forming apparatus showing an embodiment of the present invention. The image forming apparatus 1 shown in FIG. 1 is a tandem indirect transfer type color printer. The image forming apparatus 1 is not limited to a printer, and may be configured as a copier, a facsimile machine, a plotter, or the like, or a complex machine (including a printing machine) having a plurality of functions.

  As shown in FIG. 1, an image forming unit 3, an optical writing device 4, a paper feeding unit 5, a fixing device 6, and the like are disposed (arranged) in the apparatus main body 2 of the image forming apparatus 1, or Meaning that the position is determined). The image forming unit 3 is a portion that is disposed at a substantially central portion in the apparatus main body 2, forms a toner image, and transfers the formed toner image to a recording medium. The optical writing device 4 is a portion that is disposed below the image forming unit 3 and emits a light beam toward an image carrier, which will be described later, constituting the image forming unit 3. The paper feed unit 5 is a part that is disposed below the optical writing device 4 and that accommodates and feeds a sheet-like recording medium P that is a transfer target or a recording medium. The fixing device 6 is a portion that is disposed above the image forming unit 3 and that fixes the recording medium P onto which the unfixed toner image is transferred.

  The image forming unit 3 includes four image forming units 23Y, 23M, 23C, and 23K corresponding to yellow (Y), magenta (M), cyan (C), and black (K) toners from the left side in FIG. They are arranged in this order toward the right side. In addition to the above configuration, the image forming unit 3 includes a primary transfer roller 12 disposed corresponding to each of the image forming units 23Y, 23M, 23C, and 23K, an intermediate transfer belt 13 as an intermediate transfer member, and a secondary transfer roller 12. A transfer roller 14 and the like are disposed.

  Since any of the four image forming units 23Y, 23M, 23C, and 23K has the same configuration, the subscripts Y, M, C, and K representing the distinction of colors are omitted as appropriate for the sake of simplicity. . In FIG. 1, only the four image forming units 23Y, 23M, 23C, and 23K and the four photoconductors 7Y, 7M, 7C, and 7K are provided with subscripts Y, M, C, and K that indicate color distinction. ing. The image forming unit 23 has a function and configuration as an example of a process cartridge. The image forming unit 23 has a device described later and is integrated so as to be detachable from the device main body 2.

  The image forming unit 23 includes a drum-shaped photoconductor 7 as an image carrier, a charging device 8 as a charging unit, a developing device 9 as a developing unit, and a cleaning device 10 as a cleaning unit. ) In one piece. By unitizing the photoconductor 7, the charging device 8, the developing device 9, and the cleaning device 10 as a process cartridge, replacement and maintenance work can be facilitated and the positional accuracy between the members can be maintained with high accuracy. The quality of the formed image can be improved.

  The image forming process will be described while supplementing the detailed configuration. The photoreceptor 7 is rotationally driven in a clockwise direction in FIG. 1 by a driving means (not shown) such as a driving motor. A photosensitive layer on which an electrostatic latent image is formed is provided on the outer peripheral surface of the photoreceptor 7. The charging device 8 includes a charging roller disposed in the vicinity of the outer peripheral surface of the photoconductor 7. When a voltage is applied to the charging device 8 from a power supply unit (not shown) (which means that a voltage is applied), the outer peripheral surface of the photoreceptor 7 is uniformly charged.

  The optical writing device 4 emits a light beam corresponding to the image data, and exposes the outer peripheral surface of the uniformly charged photoreceptor 7. By this exposure, an electrostatic latent image corresponding to the image data is formed on the outer peripheral surface of the photoreceptor 7. The developing device 9 supplies toner as a developer to the photoreceptor 7. The supplied toner adheres to the electrostatic latent image formed on the outer peripheral surface of the photoconductor 7, and the electrostatic latent image on the outer peripheral surface of the photoconductor 7 is visualized as a toner image. As the developer, a two-component developer containing toner and carrier is used, but a one-component developer containing no carrier may be used.

  The intermediate transfer belt 13 is an endless / loop belt, and is wound around a driving roller 16A, which is also a secondary transfer backup roller, a tension roller 16B, and a cleaning backup roller 16C. The intermediate transfer belt 13 is endlessly moved (rotated / runned) in the direction of the arrow in the figure when a driving roller 16A coupled to a driving motor (not shown) is driven to rotate. The tension roller 16B and the cleaning backup roller 16C are driven to rotate by the frictional force with the intermediate transfer belt 13 as the intermediate transfer belt 13 rotates in the arrow direction in the figure. Above the intermediate transfer belt 13, there is disposed a bottle storage portion that detachably stores four toner bottles 24Y, 24M, 24C, and 24K storing new toner.

  The primary transfer roller 12 is disposed on the inner peripheral surface side (inside the loop) of the intermediate transfer belt 13, and a transfer voltage (primary transfer bias) is applied to these primary transfer rollers 12. The toner image on each photoconductor 7 is transferred onto the intermediate transfer belt 13. The toner images formed on the respective photoreceptors 7 are sequentially transferred and superimposed on the intermediate transfer belt 13, and a color toner image is formed on the intermediate transfer belt 13.

The color toner image formed on the intermediate transfer belt 13 is transferred to the secondary transfer roller 14 at the timing when the recording medium P is sent to the position of the secondary transfer nip where the intermediate transfer belt 13 and the secondary transfer roller 14 are in contact with each other. When the transfer voltage is applied, the image is transferred to the recording medium P.
Here, the recording medium P transported to the position of the secondary transfer nip portion is transported from the paper feed cassette 5 </ b> A disposed in the paper feed portion 5 via the paper feed roller 17 and the registration roller pair 18. It is a thing. Specifically, a large number of recording media P such as transfer paper are stored in the paper feeding cassette 5A of the paper feeding unit 5 in an overlapping manner. When the paper feeding roller 17 is driven to rotate counterclockwise in FIG. 1 by a driving means (not shown), the uppermost recording medium P is separated into one sheet by the cooperative action with a separating member (not shown). The sheet is fed toward the pair of registration rollers 18.

The recording medium P transported to the registration roller pair 18 is temporarily stopped in a state where it abuts (means contacting the abutted state) at the position of the roller nip portion of the registration roller pair 18 whose rotation drive has been temporarily stopped. To do. Then, the registration roller pair 18 is rotationally driven in time with the color toner image on the intermediate transfer belt 13, whereby the recording medium P is conveyed toward the secondary transfer nip portion. Thus, a desired color toner image is transferred onto the recording medium P.
Thereafter, the recording medium P on which the color toner image is transferred at the position of the secondary transfer nip portion is sent to the position of the fixing device 6. In the fixing device 6, the toner image on the recording medium P is fixed by heat and pressure generated by the fixing belt 11 and the pressure rotating body 21. The recording medium P for which the fixing process has been completed is conveyed and discharged by a discharge roller pair 19 and the like, and is sequentially discharged and stacked on a discharge tray 20 formed on the upper surface of the apparatus main body 2.

  The cleaning device 10 cleans the outer peripheral surface of the photoconductor 7 after the toner image is transferred to the intermediate transfer belt 13. By this cleaning, toner, paper dust, and the like remaining on the outer peripheral surface of the photoreceptor 7 after the toner image is transferred to the intermediate transfer belt 13 are collected as waste toner. Further, the untransferred toner that has not been transferred to the recording medium P remaining on the intermediate transfer belt 13 is cleaned by the belt cleaning device 15.

  The image forming apparatus 1 shown in FIG. 1 is not limited to the fixing device 6, and fixing devices 6 </ b> A, 6 </ b> B, and 6 </ b> C according to modified examples and embodiments described later are applied. Therefore, according to the image forming apparatus 1, by including the fixing devices 6, 6A, 6B, and 6C having the effects described later, it is possible to provide a highly reliable device with few failures of the fixing device.

(Embodiment 1)
First, the basic configuration of the fixing device according to the first exemplary embodiment of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of a main part of the fixing device according to the first embodiment.
As shown in FIG. 2, in the fixing device 6, a rotatable endless fixing belt 11 and a pressure rotator 21 that pressurizes the fixing belt 11 are disposed to face each other. On the inner peripheral side of the fixing belt 11, a fixing nip portion 41 is formed as a nip portion that is in contact with the pressure rotator 21 via the fixing belt 11 and sandwiches the recording medium P carrying the toner image T as a toner image. A nip forming member 31 is disposed. When the pressure rotator 21 presses the nip forming member 31 via the fixing belt 11, a flat fixing nip portion 41 is formed between the fixing belt 11 and the pressure rotator 21. In order to prevent the nip forming member 31 from being deformed by a reaction force when the fixing belt 11 is pressed, the auxiliary pressing member 51 supports the nip forming member 31 from the back side of the fixing nip portion 41.

  The pressure rotator 21 is rotated in the R2 direction by being driven by a driving means (not shown), whereby a driving force due to friction is transmitted to the fixing belt 11 in the fixing nip portion 41. As a result, the fixing belt 11 is moved in the R1 direction. Followed rotation. The recording medium P carrying the toner image T is sandwiched between the fixing belt 11 and the pressure rotator 21 in the fixing nip portion 41, and is conveyed in the Y direction, which is the recording medium conveyance direction, with each rotation. Simultaneously with the conveyance, the toner image T is fixed on the recording medium P by applying heat and pressure from the fixing belt 11 and the pressure rotator 21 to the toner image T on the recording medium P in the fixing nip 41.

In the present embodiment, the heating source 25 as a heating means for supplying heat to the toner image T at the fixing nip portion 41 is a linear heating element (for example, a halogen heater) provided long along the width direction of the fixing belt 11. The fixing belt 11 is heated by heat generation.
The heating source 25 is shown only in FIG. 1 and is omitted in other drawings. The heating source is not limited to the linear heating element, and may be a radiant heater, an IH (induction heating) coil, or the like. These heating sources heat the fixing belt 11 facing the toner image T, that is, the fixing nip portion 41, so that heat can be efficiently supplied to the toner image T.

The fixing belt 11 is preferably configured to have a substantially cylindrical shape with a diameter of about 15 to 120 mm in consideration of a heat capacity, a space for housing a member in the belt, and the like. It is desirable to have flexibility. Further, even if the fixing belt 11 moves in the belt width direction perpendicular to the rotation direction, the shape and mechanical characteristics are at least in the vicinity of the width of the recording medium P so that the toner image T on the recording medium P can be satisfactorily fixed. It is desirable that the thermal characteristics are substantially uniform.
In general, the fixing belt 11 includes a base material layer, an elastic layer, and a surface layer that are laminated in order from the inner peripheral side. However, when an IH coil is used as a heating means for the fixing belt, a heating layer is formed between the base material layer and the elastic layer, and when the performance requirements regarding image quality are not high, the base material layer except for the elastic layer, In some cases, the surface layer has a two-layer structure. In this embodiment, the inner diameter of the fixing belt 11 is 25 mm, and the fixing belt 11 is configured by the following base material layer, elastic layer, and surface layer.

The base material layer of the fixing belt 11 is preferably a resin material such as polyimide or a metal material such as nickel or stainless steel having a thickness of 20 to 100 μm from the viewpoint of compatibility between flexibility and rigidity. Further, for the purpose of improving the slidability with the nip forming member 31 and the absorption rate of the radiant heat from the heating source, a coating material may be coated on the inner peripheral surface of the base material layer. For example, a fluorine resin coating is desirable for improving the slidability, and a black paint coating is desirable for improving the radiant heat absorption rate.
When an IH coil is used as the heating means, the heating layer of the fixing belt 11 has a thickness of about 10 μm and is preferably a metal material, particularly copper. Heat is generated by mutual induction heating from the IH coil.

  The elastic layer of the fixing belt 11 preferably has a thickness of 50 to 300 μm and uses an elastic material such as silicone rubber. Even when the surfaces of the recording medium P and the fixing belt 11 are uneven due to the deformation of the elastic layer, it is possible to improve the non-uniformity of the pressing force and the thermal conductivity in the fixing nip portion 41, and the toner fixing quality is improved. improves.

  The surface layer of the fixing belt 11 has a thickness of 3 to 50 μm, and a material having high releasability with respect to the toner image T on the recording medium P is used. As the surface layer, for example, PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin), PTFE (tetrafluoroethylene resin), polyimide, polyetherimide, PES (polyether sulfide), or the like is preferably used. In particular, fluorine resin materials such as PFA and PTFE are desirable because they have a low coefficient of friction and good toner releasability. The surface layer is worn by members such as a temperature sensor and a separation claw (not shown) that are in contact with the fixing belt 11 in addition to the recording medium P and the pressure rotating body 21. If the surface layer is worn away and the elastic layer is exposed, fixing failure occurs in the toner image T. Therefore, the thickness needs to be determined carefully. In the present embodiment, the surface layer is made of 20 μm PFA.

  Note that the fixing belt 11 may be formed, for example, with a coating film of Teflon (registered trademark) on the back surface side of the base material layer in order to reduce frictional resistance with an end flange described later. The material for forming the coating film is not limited to Teflon (registered trademark), and surface coating such as plating, DLC (diamond-like carbon), and glass coating can be used.

  The pressure rotator 21 includes a pipe-shaped cored bar 21a formed of a metal material and an elastic layer 21b formed of a heat-resistant elastic material such as silicone rubber or foamed silicone rubber. Although not shown, a surface layer having a thickness of 10 to 70 μm formed of a fluorine-based resin such as PFA or PTFE is provided on the outer peripheral portion of the elastic layer, so that the releasability of the toner image T on the recording medium P can be improved. Can be increased. In the present embodiment, the pressure rotating body 21 has a diameter of 25 mm, the elastic layer 21b has a thickness of 4 mm, and the surface layer has a thickness of 50 μm. Note that a heating element such as a halogen heater may be incorporated in the cored bar portion 21a as needed.

The nip forming member 31 is a member that is fixedly provided as will be described later and is slid by the fixing belt 11. The material of the nip forming member 31 is preferably a highly heat-resistant resin material such as LCP (liquid crystal polymer), polyimide, or PAI (polyamideimide), but may be a metal material such as aluminum or stainless steel. Although not shown, the nip forming member 31 of the fixing belt 11 is wound around the nip forming member 31 in the form of a sheet with a low friction coefficient or coated on the sliding surface with the fixing belt 11. The sliding friction resistance with respect to can be reduced.
The pressure auxiliary member 51 is desirably made of a metal material having high rigidity such as stainless steel or iron, and has sufficient rigidity for the nip forming member 31 that relatively presses the fixing belt 11 to maintain an optimum shape. It is desirable to have.

A moving mechanism 100 of the fixing device 6 according to the first embodiment will be described with reference to FIGS. FIG. 3 is a view of the fixing device according to the first exemplary embodiment as viewed from the exit side in the recording medium conveyance direction, and is a plan view of a main part showing a state at the start of movement of the fixing belt by the moving mechanism. FIG. 4 is a view of the fixing device according to the first exemplary embodiment as viewed from the exit side in the recording medium conveyance direction, and is a plan view of a main part illustrating a state when the movement of the fixing belt by the moving mechanism is completed. FIG. 5 is a cross-sectional view around the end flange of the first embodiment.
3 and 4, the belt width direction orthogonal to the rotation direction of the fixing belt 11 is also referred to as “rotation axis direction X” assuming that there is a virtual rotation axis. 3 and 4, the rotation axis direction X is shown to be horizontal. In the rotation axis direction X, the direction toward the right in the figure is the rotation axis direction Xa, and the direction toward the left in the figure is the rotation axis direction Xb.

  As shown in FIGS. 3 and 4, the moving mechanism 100 includes end flanges 61 and 62, a positioning member 91, a rack gear 101, a pinion gear 102, a drive motor 103, and the like. The moving mechanism 100 has a function of moving the end flanges 61 and 62 as belt stopper members in the rotational axis direction X without being linked to the position of the fixing belt 11, in other words, regardless of the position of the fixing belt 11. Have.

As shown in FIGS. 3 and 4, the nip forming member 31 and the auxiliary pressure member 51 are provided extending in the rotation axis direction X. Both ends of the nip forming member 31 and the auxiliary pressure member 51 are fixedly supported by a pair of left and right frames 73 and 74 in the drawing. The pressure rotator 21 is rotatably supported at both ends of the cored bar 21a by a pair of left and right frames 71 and 72 in the drawing via bearings (not shown). The frames 71 and 72 are swingably provided on the case side of the fixing device 6 shown in FIG. 1 via a fulcrum shaft (not shown) (see FIG. 7). The frames 73 and 74 are fixed to the casing case of the fixing device 6 shown in FIG.
When the frames 71 and 72 are displaced in the vertical direction in the figure with respect to the frames 73 and 74, that is, by a known contact / separation mechanism including a spring and a cam (not shown), the pressure rotator 21 is moved relative to the fixing belt 11. Work. The pressure rotator 21 is normally pressed against the nip forming member 31 via the fixing belt 11 by the contact / separation mechanism (not shown). The pressure rotator 21 is pressed against the nip forming member 31 via the fixing belt 11 (meaning that it is pressed and pressed), whereby the fixing nip portion 41 is formed.

  A drive gear 81 is fixed to one end portion (right side in the drawing) of the cored bar portion 21 a of the pressure rotating body 21. In the vicinity of the driving gear 81, driving means (not shown) such as a motor fixed to the apparatus main body 2 of FIG. By driving the driving gear 81 by the driving means, the pressure rotator 21 rotates, and the driving torque of the pressure rotator 21 is transmitted to the fixing belt 11 via the fixing nip portion 41, thereby fixing. The belt 11 is driven to rotate.

  An end flange 61 is disposed between the frame 73 and the left side end of the fixing belt 11, and an end flange 62 is disposed between the frame 74 and the right side end of the fixing belt 11. ing. In FIG. 5, the configuration of the end flange 62 and the side end portion of the fixing belt 11 in the rotation axis direction is illustrated by using the end flange 62 as an example, but the same applies to the end flange 61. That is, the end flange 62 and the end flange 61 are substantially C-shaped and have a specific left-right symmetric shape with a part cut away. Of the end flanges 61, 62, the belt inscribed portions 611, 621 having a convex shape protrude on the inner peripheral surface of each side end portion side of the fixing belt 11 to be inscribed, thereby rotatably supporting the fixing belt 11. It functions as a belt support or belt support member. The belt inscribed portions 611 and 621 maintain the general shape of the fixing belt 11 that slides around (meaning the general outer shape of the fixing belt 11). Belt inscribed portions 611 and 621 are portions indicated by broken lines in FIGS. 3 and 4.

Further, the belt facing surfaces 612 and 622 of the end flanges 61 and 62 function as a belt stopper member that contacts the side end portion of the fixing belt 11 and regulates the position of the fixing belt 11 in the rotation axis direction X. Here, the side end portion of the fixing belt 11 means a side end surface of the fixing belt 11 and a region including a side end corner and an edge.
The end flanges 61 and 62 are integrally formed of a high heat-resistant resin such as PPS (polyphenylene sulfide resin), LCP, PEEK (polyether ether ketone resin), or PEK (polyether ketone resin).

  The belt facing surfaces 612 and 622 are in contact with the side end portion of the fixing belt 11 with respect to the “belt shift” in which the fixing belt 11 moves in the rotation axis direction X as the fixing belt 11 rotates. It has a role to regulate the position. At this time, since the belt facing surfaces 612 and 622 are substantially perpendicular to the rotation axis direction X of the fixing belt 11, the side end portion of the fixing belt 11 is deformed by the reaction force received from the belt facing surfaces 612 and 622. Can be suppressed.

The end flanges 61 and 62 are attached and fixed to the end portions of the positioning member 91 extending (meaning extending) in the rotation axis direction X via coupling means such as screws. A rack gear 101 is attached and fixed to the positioning member 91. As shown in FIG. 5, the positioning member 91 has a rectangular cross section and is formed of a metal such as iron, which is a highly rigid material that can maintain the parallelism of the end flanges 61 and 62. The positioning member 91 is moved and guided in parallel with the rotation axis direction X of the fixing belt 11 by a guide member (not shown) provided on the apparatus main body 2 side of FIG.
The positioning member 91 may be any material that can satisfy the above functions, and may be integrally formed of, for example, a resin in which a metal is inserted.

On the other hand, the housing case of the fixing device 6 shown in FIG. 1 is fixedly provided with a drive motor 103 as a drive means having an output shaft to which a pinion gear 102 that always meshes with the rack gear 101 is attached and fixed. As the drive motor 103, a stepping motor is used as an example of a drive motor that is driven by a pulse input that can perform positioning control with high accuracy.
The moving mechanism 100 employs the rack gear 101 as the moving means of the positioning member 91. However, the moving mechanism 100 is not limited to this, and any other means may be used as long as the same movement is obtained. For example, a mechanism using a ball screw or the like may be used. Further, the drive motor 103 is not limited to a stepping motor, and may be a DC motor or the like.

By the rotational drive of the drive motor 103, the rack gear 101 meshed with the pinion gear 102 is converted into a reciprocating linear motion, and the positioning member 91 moves in the rotational axis direction X of the fixing belt 11. In the present embodiment, the initial position (home position) of the positioning member 91 in the fixing device 6 is the position shown in FIG. 3 at the start of movement, and gradually moves from there to the position shown in FIG. . As the positioning member 91 moves, the belt facing surfaces 611 and 612 of the end flanges 61 and 62 that regulate the position of the fixing belt 11 also move in the rotational axis direction X. As a result, the fixing belt 11 moves in the rotational axis direction Xa by being pushed toward the belt itself or by the belt facing surface 612 of the end flange 61, and accumulation of wear at a local position in the axial direction of the fixing belt. Can be prevented.
The moving range of the positioning member 91 by the moving mechanism 100 is expressed from the position shown in FIG. 3 to the position shown in FIG. That is, even if the fixing belt 11 takes an arbitrary position between the belt facing surfaces 612 and 622 of the end flanges 61 and 62, the side end portion of the fixing belt 11 is the fixing nip portion 41 of the pressure rotator 21. It is set so that it may not enter inside the both ends of the range which forms. Thereby, the wear of the nip forming member 31 and the increase in the rotational torque of the pressing rotator 21 due to the surface of the nip forming member 31 sliding in contact with the pressing rotator 21 are prevented. However, if the above does not become a problem, the side end portion of the fixing belt 11 can enter the inside of the fixing nip portion 41 as long as the recording medium P does not pass. The moving state of the fixing belt 11 in FIG. 4 shows a state in which the fixing belt 11 is moved by its own belt, rather than being pushed by the belt facing surface 612 of the end flange 61.

  More specifically, for example, a specific range with respect to the rotation axis direction X of the fixing belt 11 by a member such as a cutting burr generated at the end edge of the recording medium P, a temperature sensor or a separation claw not shown in contact with the fixing belt 11. Causes local wear. By moving the fixing belt 11 in the rotation axis direction X as in the present embodiment, the above-mentioned local wear accumulates at a specific position of the fixing belt 11 and the surface layer of the fixing belt 11 is worn away. Can be prevented.

  The moving speed of the fixing belt 11 in the rotation axis direction X needs to be within an appropriate range. Specifically, if the moving speed is too fast, the moving distance of the fixing belt 11 and the positioning member 91 during the use period of the fixing device 6 becomes long, and the fixing device 6 becomes large. On the other hand, if the moving speed is too slow, the amount of wear received until the surface of the fixing belt 11 passes through the range where local wear occurs increases, and the surface layer is worn away. In this embodiment, since the moving speed of the positioning member 91 and the moving speed of the fixing belt 11 are substantially the same, the moving speed of the positioning member 91 is slower than the above-described range, that is, the speed of the fixing belt 11 close to its own belt. The range was set.

  If the parallelism or the like of the end flanges 61 and 62 with respect to the pressure rotator 21 is lost when the positioning member 91 moves, an extra load is applied to the side end of the fixing belt 11 and the same end is deformed. As a result, the fixing belt 11 may be damaged. Therefore, it is desirable that the moving direction of the positioning member 91 is parallel to the rotation axis direction X by the guide member (not shown) or the means (not shown) as described above.

As described above, according to the first embodiment, the following effects can be obtained. First, the fixing belt 11 is rotated by the moving mechanism 100 without providing a belt stopper member on the inner peripheral surface, the outer peripheral surface, or the like of the fixing belt 11 and without interlocking with the position of the fixing belt 11 near the belt. It can move in the axial direction X. Accordingly, it is possible to avoid the fixing belt 11 from being damaged early due to repeated bending due to a change in curvature during rotation without increasing the thickness.
Second, when the fixing belt 11 is moved in the rotation axis direction X by the moving mechanism 100, the above-mentioned local wear accumulates at a specific position of the fixing belt 11, and the surface layer of the fixing belt 11 is worn away. Can be prevented.
Third, since the end flanges 61 and 62 as belt stopper members also have the function of a belt support member that rotatably supports the fixing belt 11, a simple fixing device is configured with a reduced number of parts. Can be provided.

As described above, the end flange 62 moves so as to face one side end of the fixing belt 11, and the fixing belt 11 rotating in the R1 direction moves so as to approach the end flange 62. Alternatively, it is in contact with the belt facing surface 622 of the end flange 62 (claim 9).
According to the configuration of the first embodiment, it is not necessary to provide a movable belt stopper member (end flange 62) on both sides of the fixing belt 11, and the fixing device 6 can be simplified.

(Modification 1)
With reference to FIG.6 and FIG.7, the modification 1 of Embodiment 1 is demonstrated. FIG. 6 is a plan view illustrating the relationship between the inclination of the pressure rotator and the belt of the fixing belt for explaining the principle of the first modification, and FIG. 7 is a parallelism adjustment mechanism of the fixing device showing the first modification. It is the cross-sectional front view which fractured | ruptured some.
As described in the first embodiment, in order to transport the recording medium P, the fixing belt 11 rotates in the R1 direction shown in FIG. 2 in a normal state. When rotating in one direction as described above, the fixing is caused by the inclination between the fixing belt 11 and the pressure rotator 21, uneven rotation speed in the direction of the rotation axis of the pressure rotator 21, or the like. A “belt shift” occurs in which the belt 11 moves in one direction of the rotation axis direction X. In many cases, the occurrence of the “belt shift” causes the side end portion of the fixing belt 11 to move closer to the belt facing surface 612 of the end flange 61 or the belt facing surface 622 of the end flange 62. Abut.

  In this modification, as shown in FIG. 6, the rotation axis (not shown) of the pressure rotator 21 indicated by a broken line is inclined with respect to the virtual rotation axis of the fixing belt 11. As a result, as shown in FIG. 2, the fixing belt 11 rotating in the R <b> 1 direction is rotationally driven by the pressure rotator 21 so as to always approach or abut against the belt facing surface 622 of the end flange 62. did. The belt facing surface 622 of the end flange 62 moves in a direction in which the contact position with respect to the side end of the fixing belt 11 moves away from the fixing belt 11 as the positioning member 91 moves. Compared with the configuration in which the side end portion of the fixing belt 11 moves so as to approach the belt facing surface 612 of the end flange 61 and comes into contact, the fixing belt 11 side is moved by the movement of the end flange 62 by this configuration. The load generated at the end is reduced, and breakage can be prevented.

  Note that FIG. 6 exaggerates the inclination of the elastic layer 21b of the pressure rotating body 21 and the fixing belt 11 shown by broken lines in order to make the phenomenon easy to understand. The direction closer to the belt is controlled with an inclination that does not cause any problems. Further, if the inclination between the pressure rotator 21 and the fixing belt 11 is too large, the contact force with respect to the end flange 62 of the rotating fixing belt 11 increases, and a load is applied to the side end of the fixing belt 11. It is also necessary to consider that it breaks.

  Therefore, in the present modification, as shown in FIG. 7, a parallelism adjustment mechanism 170 that finely adjusts the parallelism of the rotation shaft (core metal portion 21 a) of the pressure rotating body 21 with respect to the virtual rotation shaft of the fixing belt 11. (Claim 7). The parallelism adjustment mechanism 170 finely adjusts the inclination of the rotation axis (core metal portion 21a) of the pressure rotating body 21 and the virtual rotation axis of the fixing belt 11 within an appropriate range, and the direction of the belt is adjusted. Can be controlled.

  The parallelism adjusting mechanism 170 includes a frame 171, a position adjusting cam 172, a cam drive motor 173, a spring 174, and the like. One of the frames 71 and 72 that rotatably supports each end of the cored bar 21a of the pressure rotator 21 is disposed in the housing case of the fixing device 6 shown in FIG. The frame 171 is swingably supported via a fulcrum shaft 71a. The frame 171 is supported at one end on the left end side in the drawing in a swingable manner by the housing case (not shown) of the fixing device 6 via a fulcrum shaft 171a. A contact / separation mechanism having a lever, an eccentric cam, a spring, and the like (not shown) is provided on the free end side (the side opposite to the fulcrum shaft 71a) of the frames 71 and 72, so that the pressure rotator 21 is attached to the fixing belt 11. It is designed to make contact and separation.

A position adjusting cam 172 having a cam shaft 172a that is rotatably supported by the housing case (not shown) is provided in contact with the other end of the frame 171 on the right end side in the drawing. The position adjusting cam 172 shown in FIG. 7 represents a state in which the small diameter portion is in contact with the action point 171b of the frame 171 and occupies the initial position. A cam drive motor 173 is connected to the cam shaft 172a, and the position adjustment cam 172 is rotated by the drive of the cam drive motor 173. As the cam drive motor 173, a stepping motor is used as an example of a drive motor driven by pulse input that can control the rotation amount with high accuracy. Further, the other end of the tension spring 174 is attached between the fulcrum shaft 71a attachment portion and the other end portion of the frame 171. By the tension spring 174, the other end portion of the frame 171 is constantly applied with a pressing force / biasing force in a direction to contact the position adjusting cam 172.
The parallelism adjustment mechanism 170 is not limited to this, and may be a mechanism having a position adjustment screw that displaces the position of the action point 171b in the vertical direction and a drive motor that rotates the position adjustment screw via a worm gear, for example.

  Here, the operation of the parallelism adjusting mechanism 170 will be described. The cam drive motor 173 is driven by a predetermined number of steps (or the number of pulses applied) against the urging force of the tension spring 174, whereby the position adjusting cam 172 occupying the initial position shown in FIG. It is rotated by an angle. As a result, the frame 171 is lifted and displaced by the predetermined angle of the position adjusting cam 172 around the fulcrum shaft 171a, so that the frame 71 is slightly lifted by an amount corresponding to the arrangement position of the fulcrum shaft 71a. It will be displaced. As a result, the position of the rotary shaft of the pressurizing rotator 21 that is rotatably supported by the frame 71 is slightly displaced upward in the drawing relative to that of the frame 72, so that the rotary shaft of the pressurizing rotator 21 and the fixing are fixed. The inclination of the belt 11 with respect to the virtual rotation axis is finely adjusted, and the state shown in FIG. 6 is obtained.

  According to the modification example 1, as described above, the parallelism adjusting mechanism 170 that adjusts the parallelism of the rotation shaft of the pressure rotator 21 with respect to the rotation shaft of the fixing belt 11 is provided. That is, by adjusting the parallelism by the parallelism adjusting mechanism 170, the fixing belt is adjusted in the proper direction by adjusting the direction of the fixing belt and the contact force to the belt stopper members (end flanges 61 and 62). It is possible to prevent the fixing belt from being damaged by suppressing the load on the side end portion.

(Modification 2)
Modification 2 of Modification 1 will be described. In the first embodiment and the first modification, the positioning member 91 that fixes the end flanges 61 and 62 is configured to move only from the initial position in FIG. 3 in the direction of the end flange 62 (rotation axis direction Xa). Adjustment was made so that the direction of movement of the fixing belt 11 due to the belt was unidirectional. Not limited to this, in the second modification, the positioning member 91 is configured to be movable in both directions of the end flanges 61 and 62 from the initial position. That is, the moving direction of the fixing belt 11 may be detected by a sensor (not shown) or the like, and the positioning member 91 may be moved so that the end flange on which the fixing belt 11 is approaching is separated from the fixing belt 11. ). By doing so, the above effect can be obtained without adjusting the moving direction of the fixing belt 11 due to the inclination of the pressure rotator 21 and the fixing belt 11 or the like.

  A specific example of detecting the moving direction of the fixing belt 11 will be described. A plurality of light-reflective photosensors (not shown), for example, are fixed to the housing case so as to face the left and right side ends of the fixing belt 11 shown in FIG. These photosensors detect whether the side end of the fixing belt 11 is approaching the left or right, so that the end flange 61 or the end flange 62 closer to the fixing belt 11 is separated from the fixing belt 11. The positioning member 91 is moved. That is, the drive motor 103 may be controlled by a control means (not shown) so as to move the positioning member 91 so that the end flange 61 or the end flange 62 on the side closer to the fixing belt 11 is separated from the fixing belt 11. . Note that the end flanges 61 and 62 may be colored black so that the photo sensor can easily detect the approach of the side end of the fixing belt 11.

  As described above, in Modification 2, the position of the belt stopper member (end flange 61, 62) that contacts the side end of the fixing belt 11 moves in a direction away from the fixing belt 11 ( Claim 3). Therefore, according to the second modification, it is possible to prevent a load from being applied to the side end portion of the fixing belt due to the movement of the belt stopper members (end flanges 61 and 62), and to prevent the fixing belt from being damaged.

(Modification 3)
A third modification of the first embodiment will be described (claim 4). In the third modification, the moving speed or the moving timing of the positioning member 91 is changed as compared with the first embodiment, such as changing the moving speed of the positioning member 91 or setting the positioning member 91 to move at a predetermined timing. Only the point of controlling is different.
The moving speed of the positioning member 91 shown in FIGS. 3 and 4 does not need to be constant and does not need to be constantly moved. The life of the fixing belt 11 is further extended by controlling the moving speed or moving timing of the positioning member 91, such as changing the moving speed of the positioning member 91 or setting the positioning member 91 to move at a predetermined timing. It is also possible to do.

  For example, by changing the movement speed of the positioning member 91 so as to be proportional to the rotation speed of the fixing belt 11 in the R1 direction, the movement distance in the rotation direction of the fixing belt 11 and the movement distance in the rotation axis direction X are changed. 11 is constant regardless of the rotation speed. As a result, the amount of wear that the surface layer of the fixing belt 11 receives is constant regardless of the rotation speed of the fixing belt 11. Further, by moving the positioning member 91 only when the rotation speed of the fixing belt 11 in the R1 direction is equal to or higher than a certain value, the contact force of the side end portion of the fixing belt 11 with respect to the end flange 62 is suppressed, and the fixing belt 11 is moved. The life can be extended.

  In the third modification, the moving speed of the belt stopper member is optimized according to the load applied to the side surface of the fixing belt due to contact with the belt stopper member (end flanges 61 and 62), the wear state of the fixing belt surface layer, and the like. Turn into. Thereby, the life of the fixing device can be extended against damage to the fixing belt and abrasion of the surface of the fixing belt.

(Modification 4)
With reference to FIGS. 8-10, the modification 4 of the modification 3 is demonstrated (Claim 5, 6, 8). FIG. 8 is a partial cross-sectional front view for explaining the contact detection switch constituting the belt speed detection means. 9A shows a state where the contact detection switch is off (hereinafter abbreviated as “OFF”), and FIG. 9B shows a state where the contact detection switch is on (hereinafter abbreviated as “ON”). It is a partial cross section front view explaining each. FIG. 10 is a control block diagram for controlling the moving speed of the fixing belt. FIG. 10 also shows a cam drive motor 173 that is a control component according to claim 8 in order to simplify the drawing.
The modification 4 is mainly different from the modification 3 in that it includes a belt speed detection unit that detects the moving speed of the fixing belt 11 in the rotation axis direction X. As shown in FIGS. 8 and 9, the belt speed detection means includes a contact detection switch 123 provided on the end flange 62, a control means 110 and a drive motor 103 shown in FIG. 10.

As shown in FIGS. 8 and 9, a metal thin piece 121 is attached and fixed to the belt inscribed portion 621 of the end flange 62 so as to be in contact with the side end portion of the fixing belt 11. On the other hand, a metal thin piece 122 is attached and fixed to the belt facing surface 622 of the end flange 62 so as to be in contact with the thin piece 121. The thin piece 121 and the thin piece 122 are made of, for example, an iron thin plate having elasticity, and constitute a contact detection switch 123.
As shown in FIG. 9A, when the side end portion of the fixing belt 11 is not in contact with the thin piece 121, the thin pieces 121 and 122 are separated from each other and are in a non-contact state. The contact detection switch 123 is in an OFF state due to conduction.
On the other hand, as shown in FIG. 9B, when the fixing belt 11 moves in the rotation axis direction Xa and the side end of the fixing belt 11 contacts the thin piece 121, the thin piece 121 receives a force from the fixing belt 11. It is elastically deformed and comes into contact with the thin piece 122 so that the contact circuit AB is electrically connected. Thereby, the contact detection switch 123 is turned on.

In FIG. 10, the control means 110 includes a microcomputer (not shown) that includes a CPU, an I / O (input / output) port, a ROM, a RAM, a timer, and the like, which are connected by a signal bus. ing. The CPU of the control means 110 receives an ON / OFF signal from the contact detection switch 123 via the input port, and controls the drive motor 103 via the output port. The ROM stores a program for controlling the drive motor 103, a program for calculating the moving speed of the fixing belt 11 in the rotation axis direction X, or the moving distance of the positioning member 91 (from the initial position of FIG. 3 to FIG. 4). The distance to the movement stop position until) is stored in advance.
The control unit 110 varies the moving speed of the positioning member 91 via the drive motor 103, and the belt detection surface 123 of the end flange 62 and the side end of the fixing belt 11 are detected by the contact detection switch 123 for each moving speed. A contact state with the part is detected. Thereby, the moving speed of the fixing belt 11 can be detected. As described above, the belt speed detection means includes the contact detection switch 123 provided on the end flange 62, the control means 110, and the drive motor 103.

  By detecting the moving speed of the fixing belt 11 in the rotation axis direction X, the moving speed of the positioning member 91 can be controlled according to the moving speed. For example, by moving the positioning member 91 in accordance with the moving speed of the fixing belt 11, the contact force of the side end portion of the fixing belt 11 with respect to the belt facing surface 622 of the end flange 62 is made minute, and the side end of the fixing belt 11 is The life of parts can be extended.

In the modified example 4, as described above, the belt speed detecting means for detecting the moving speed of the fixing belt 11 in the rotation axis direction X is provided (Claim 5). Therefore, according to the fourth modification, by detecting the moving speed of the fixing belt, the load applied to the side end portion of the fixing belt due to the contact with the belt stopper members (end flanges 61 and 62), or a constant width. It is possible to calculate the amount of wear that the fixing belt surface layer receives. Thereby, the moving speed of the belt stopper member for extending the life of the fixing device can be reliably optimized.
In the modified example 4, as described above, the belt speed detecting means detects the moving speed of the fixing belt in the rotation axis direction by detecting the contact state of the fixing belt with the belt stopper member (end flange 62). (Claim 6). Therefore, according to the fourth modification, the moving speed of the fixing belt can be calculated by using the contact state of the fixing belt with respect to the belt stopping member and the moving speed of the belt stopping member. Thereby, the moving speed of the fixing belt can be detected with a simple detection device configuration.

  Further, the fixing is performed by adjusting the inclination by the parallelism adjusting mechanism 170 of the first modification shown in FIG. 7 so that the moving speed of the fixing belt 11 in the rotation axis direction X detected by the belt speed detecting means is within an appropriate range. The moving speed of the belt 11 in the rotation axis direction X may be adjusted (claim 8). That is, in FIG. 10, the control means 110 detects the moving speed of the fixing belt 11 as described above, and adjusts the inclination of the pressure rotator 21 through the control of the cam drive motor 173 of the parallelism adjustment mechanism 170. The moving speed of the fixing belt 11 in the rotation axis direction X can be adjusted. As a result, the life against the abrasion of the surface layer of the fixing belt 11 and the breakage of the side end can be stably extended.

  In particular, in a fixing device in which the moving speed of the fixing belt 11 in the rotation axis direction X varies during use due to, for example, thermal expansion of the pressure rotator 21 or deterioration due to long-term use, the modification 1 In addition to the effects, the following effects are achieved. That is, by automatically adjusting the moving speed of the fixing belt 11 in the rotational axis direction X and the moving speed of the positioning member 91, the moving speed of the fixing belt is stably maintained within an appropriate range. The life of the fixing belt thus obtained can be stably realized.

(Embodiment 2)
The second embodiment will be described with reference to FIGS. 11 and 12. FIG. 11 is a view of the fixing device according to the second exemplary embodiment as viewed from the exit side in the recording medium conveyance direction, and is a plan view of a main part showing a state at the start of movement of the fixing belt by the moving mechanism. FIG. 12 is a plan view of the main part showing a state when the fixing belt movement by the moving mechanism is completed.
The second embodiment is different from the first embodiment only in that a fixing device 6A having a moving mechanism 100A is used instead of the fixing device 6 having the moving mechanism 100. The configuration of the fixing device 6A other than this difference is the same as that of the fixing device 6. Compared with the moving mechanism 100 of the first embodiment, the moving mechanism 100A of the second embodiment is configured such that the positioning member 91 is removed, and only the end flange 62 side is moved. The main difference is that the frame is fixed to the frame 73. The second embodiment has the same configuration as that of the first embodiment except that the description is not specified.

In the present embodiment, the end flange 61 is fixed to the frame 73, and the belt inscribed portion 611 of the end flange 61 is formed long. Further, the rack gear 101 is directly attached to the upper portion of the end flange 62, and the end flange 62 is moved in the rotation axis direction Xa of the fixing belt 11. Also in this embodiment, the fixing belt 11 is adjusted in the direction closer to the belt so as to move in the direction of the end flange 62 by the driven rotation in the R1 direction shown in FIG. The fixing belt 11 can be moved in the rotation axis direction Xa. In the configuration of the first embodiment, in order to control the positional relationship between the end flanges 61 and 62 with high accuracy, it is necessary to increase the rigidity and dimensional accuracy of the positioning member 91, which complicates the fixing device 6. With the configuration described in the second embodiment, the positions of the end flanges 61 and 62 can be controlled with high accuracy even if the positioning member 91 is omitted, and the fixing device 6A can be simplified.
In the second embodiment, it is needless to say that at least one configuration of the first to fourth modifications can be applied.

As described above, the end flange 62 moves so as to face one side end of the fixing belt 11, and the fixing belt 11 rotating in the R1 direction moves so as to approach the end flange 62. Alternatively, it is in contact with the belt facing surface 622 of the end flange 62 (claim 9).
According to the above configuration, it is not necessary to provide a movable belt stopper member (end flange 62) on both sides of the fixing belt 11, and the fixing device 6A can be simplified.

(Embodiment 3)
The third embodiment will be described with reference to FIGS. 13 and 14. FIG. 13 is a plan view of a main part of the fixing device according to the third embodiment as viewed from the exit side in the recording medium conveyance direction. 14A is a cross-sectional view around the belt stopper member, and FIG. 14B is an enlarged cross-sectional view of the main part showing the arrangement state of the stopper rotation guide fixed to the end flange and the belt stopper member. FIG.
The third embodiment is different from the second embodiment only in that a fixing device 6B shown in FIG. 13 is used instead of the fixing device 6A. As shown in FIGS. 13 and 14, the fixing device 6 </ b> B according to the third embodiment is different from the end flange 62 as a member that contacts the side end of the fixing belt 11, as shown in FIGS. 13 and 14. The difference is that a body belt stop member 111 is provided. Except for this difference, the configuration that is not particularly described in the third embodiment is the same as that of the second embodiment.

As shown in FIG. 14 (a), the belt stopper member 111 is a ring-shaped sheet member, and is in contact with the side end portion of the fixing belt 11 so as to be driven to rotate. The belt stopper 111 is made of a high heat resistant resin similar to the above-described material forming the end flanges 61 and 62. The belt stopper member 111 has a slit-like notch in the end flange 62 at a portion of the end flange 62 where the belt stopper member 111 enters inside the belt inscribed surface of the belt inscribed portion 621. Thus, interference with the end flange 62 is prevented.
As shown in FIGS. 14 (a) and 14 (b), an L-shaped stop rotation guide 131 is attached and fixed to the outer periphery of the belt facing surface 622 of the end flange 62. The stop rotation guide 131 is made of a high heat resistant resin similar to the above-described material forming the end flanges 61 and 62. The belt stopper member 111 is sandwiched between the end flange 62 and the stopper rotation guide 131 and covers the outer periphery and inner periphery of the belt stopper member 111 so that the belt stopper member 111 can rotate and rotate in the rotation axis direction. The position of X is regulated.

  When the belt stopper member 111 comes into contact with the side end portion of the fixing belt 11, it is driven to rotate by the frictional force from the fixing belt 11. Compared to the case where the belt facing surface 622 of the fixed end flange 62 and the side end of the fixing belt 11 abut and slide as in the second embodiment, the belt stopper member 111 and the fixing belt 11 The sliding distance between the two can be reduced, and wear generated on both sides can be suppressed. In particular, the position where the side end portion of the fixing belt 11 abuts against the belt stopper member 111 which is a counterpart member hardly changes with the rotation of the fixing belt 11. For this reason, in the second embodiment, the position of the belt facing surface 622 where the side end of the fixing belt 11 abuts in the end flange 62 is significantly worn, resulting in unevenness on the surface, and as a result, the abutting fixing belt There is a possibility that the load on the side end portion of 11 will increase and break. By rotating the belt stopper member 111 in the same direction as the side end portion of the fixing belt 11, the above problems can be suppressed.

As described above, in the third embodiment, the belt stopper member 111 is driven to rotate relative to the rotation of the fixing belt 11 in the R1 direction by contacting the side end portion of the fixing belt 11 (claims). 10). Therefore, according to the fourth embodiment, by rotating the belt stopper member, it is possible to prevent a specific range of the belt stopper member from being worn by sliding with the side end portion of the fixing belt 11. Since the belt stopper member is driven to rotate, a mechanism for rotational driving is not required, and the fixing device 6B can be configured simply.
In the third embodiment, it is needless to say that at least one configuration of the first to fourth modifications can be applied.

(Embodiment 4)
The fourth embodiment will be described with reference to FIGS. 15 and 16. FIG. 15 is a plan view of the main part of the fixing device according to the fourth embodiment as viewed from the exit side in the recording medium conveyance direction, and FIG. 16 is a plan view of the main part showing a state where the first belt stopper member is removed from FIG. .
The fourth embodiment is different from the second embodiment only in that a fixing device 6C shown in FIGS. 15 and 16 is used instead of the fixing device 6A. Compared with the fixing device 6A of the second embodiment, the fixing device 6C of the fourth embodiment replaces the end flange 62 with a belt rough shape maintaining member 62a and a first belt offset as shown in FIGS. The main difference is that the stop member 62b and the second belt stopper member 62c are used. Except for this difference, the configuration in which the description is not specified in the fourth embodiment is the same as that in the second embodiment.

  The belt general shape maintaining member 62a is formed with a belt inscribed portion 62aa (a portion indicated by a broken line in FIGS. 15 and 16) that maintains the general shape of the fixing belt 11 that slides around the belt. The belt inscribed portion 62aa functions as a belt support portion that rotatably supports the fixing belt 11 by projecting to the inner peripheral surface on the right side end portion side in the drawing of the fixing belt 11 and in contact with the inner peripheral surface. To do. A first belt locking member 62b and a second belt locking member 62c are provided on the belt inscribed portion 62aa of the belt general shape maintaining member 62a.

The first belt stopper member 62b is detachably attached to the belt general shape maintaining member 62a. The first belt stopping member 62b is formed with a belt facing surface 62ba that functions as a belt stopping portion that contacts the side end portion of the fixing belt 11 and regulates the position of the fixing belt 11 in the rotation axis direction X. .
The second belt stopping member 62c is formed with a belt facing surface 62ca that functions as a belt stopping portion that contacts the side end portion of the fixing belt 11 and restricts the position of the fixing belt 11 in the rotation axis direction X. . The first belt stopper member 62b and the second belt stopper member 62c are formed of a high heat resistant resin similar to the above-described material forming the end flanges 61 and 62.

As shown in FIG. 15, after the use of the fixing device 6C is started, the side end portion of the fixing belt 11 is in contact with the belt facing surface 62ba of the first belt stopping member 62b. When the first belt locking member 62b is removed from the fixing device 6C at a predetermined timing with respect to the fixing device 6C having such a configuration, the fixing belt 11 approaches the second belt locking member 62c due to “belt shift”. The final result is as shown in FIG. That is, the side end portion of the fixing belt 11 moves to a position where it abuts on the belt facing surface 62ca of the second belt stopper member 62c. As described above, since there are two positions in the rotation axis direction Xa between the first belt locking member 62b and the second belt locking member 62c, the position of the belt locking member that contacts the fixing belt 11 is switched. Thus, the fixing belt 11 can be moved in the rotation axis direction Xa.
In the fourth embodiment, it is needless to say that at least one of the configurations of the first to fourth modifications can be applied.

  In this embodiment, the position where the belt stopper member comes into contact with the fixing belt 11 is set to two positions. Changing the contact position between the belt stopper member and the side end of the fixing belt 11 such as removing the first belt stopper member 62b from the fixing device 6C is the image forming apparatus 1 of FIG. It may be carried out by a user or a service person. Alternatively, it is assumed that the fixing device 6C automatically performs using an appropriate link mechanism or the like.

  Although the present invention has been described with respect to specific embodiments and modifications, the technical contents disclosed by the present invention are not limited to those exemplified in the above-described embodiments, modifications, or examples. That is, it may be configured by appropriately combining them, and it will be apparent to those skilled in the art that various embodiments, modifications, and examples can be configured within the scope of the present invention according to the necessity and application. It is.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 3 Image forming part (an example of image forming means)
4 Optical writing device 5 Paper feeding unit 6, 6A, 6B, 6C Fixing device 7 Photoconductor (an example of an image carrier)
8 Charging device 9 Developing device 10 Cleaning device 11 Fixing belt 21 Pressure rotating body 23 Image forming unit 25 Heating source (an example of heating means)
31 Nip forming member 41 Fixing nip (an example of a nip)
51 Pressurizing auxiliary members 61 and 62 End flanges (an example of a belt stopper member and a belt support member)
62a Belt shape maintaining member (an example of a belt support member)
62b First belt stopper member (an example of a belt stopper member)
62c Second belt stopper member (an example of a belt stopper member)
71-74 Frame 91 Positioning member 100, 100A Moving mechanism 103 Drive motor (component of belt speed detecting means)
110 Control means (component of belt speed detection means)
123 Contact detection switch (component of belt speed detection means)
170 Parallelism adjusting mechanism P Recording medium X Rotational axis direction (belt width direction)

JP 2004-286922 A Japanese Patent No. 4320234 JP 2012-047848 A JP 2013-186192 A

Claims (11)

A rotatable endless fixing belt, a pressure rotating body that is provided to face the fixing belt and pressurizes the fixing belt, and is provided on an inner peripheral side of the fixing belt. A nip forming member that forms a nip portion that contacts a pressure rotator and sandwiches a recording medium carrying a toner image is provided separately from the fixing belt, and contacts a side end portion of the fixing belt. A belt stopper member that regulates a position in the belt width direction orthogonal to the rotation direction of the fixing belt, and a fixing device comprising:
A fixing device comprising: a moving mechanism that moves the belt stopper member in the belt width direction without being linked to the position of the fixing belt.   The fixing device according to claim 1, wherein the belt stopper member includes a belt support portion that rotatably supports the fixing belt.   The fixing device according to claim 1, wherein a position of the belt stopper member that contacts the side end portion of the fixing belt moves in a direction away from the fixing belt.   The timing of moving the fixing belt in the belt width direction, the moving speed of the fixing belt, or the combination of the timing and the moving speed, the position of the belt stopping member that contacts the side end of the fixing belt. The fixing device according to claim 1, wherein the fixing device is controlled by the control unit.   5. The fixing device according to claim 4, further comprising belt speed detecting means for detecting a moving speed of the fixing belt in the belt width direction.   The fixing device according to claim 5, wherein the belt speed detection unit detects a moving speed of the fixing belt in the belt width direction by detecting a contact state of the fixing belt with the belt stopper member. .   7. The fixing device according to claim 1, further comprising a parallelism adjusting mechanism that adjusts a parallelism of the rotating shaft of the pressure rotating body with respect to the rotating shaft of the fixing belt.   Adjusting the parallelism of the rotational axis of the pressure rotator with respect to the belt width direction of the fixing belt according to the moving speed of the fixing belt in the belt width direction detected by the fixing belt speed detecting means; The fixing device according to claim 7, characterized in that: The belt stopper member is moved so as to face one of the side end portions of the fixing belt,
9. The fixing belt according to claim 1, wherein the fixing belt rotating in the rotation direction moves so as to approach the belt stopper member or is in contact with the belt stopper member. The fixing device according to one.   5. The belt holding member according to claim 1, wherein the belt stopper member rotates following the rotation of the fixing belt by contacting the side end portion of the fixing belt. 6. Fixing device.   An image forming apparatus comprising: an image forming unit that forms a toner image on a recording medium; and the fixing device according to claim 1.

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