JP5966443B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device having a rotatable and flexible fixing sleeve, and an image forming apparatus using the fixing device.

  In recent years, there has been a growing demand for energy saving and high speed for image forming apparatuses such as printers, copiers, and facsimiles. In addition, there is a demand for a long life that can withstand continuous use for a long period of time and a quiet operation noise during printing. Among these demands, in order to realize a long lifetime, in the current image forming apparatus, importance is attached to the improvement of the durability of each component constituting the image forming apparatus. Prior to that, a technique for reducing the mechanical load on each component is also considered effective.

  However, if each operating part is reduced in weight for speeding up, the strength becomes weak, so it is difficult to achieve both speeding up and long life. Therefore, it is considered that there is a limit to speeding up the operation of the conventional image forming apparatus and extending the life.

  Here, a conventional fixing device will be described with reference to FIG. FIG. 8 is a front view of a main part of a conventional fixing device. The fixing device 30 'shown in FIG. 8 has a main part by a cylindrical fixing sleeve 33 having flexibility and a support member that wraps and supports the fixing sleeve 33 so as to be slidable, that is, in surface contact. Is configured. The support member is generally cylindrical and is configured to support it while being in surface contact with the inner peripheral surface of the fixing sleeve 33. However, in FIG. 8, most of the support member is hidden inside the fixing sleeve 33.

  On the outer peripheral surface of the flange 38, an end surface protection ring 39 ′ is provided as a detent at a position where the end portion 33 b in the thrust direction of the fixing sleeve 33 interferes with the end surface E. The end face protection ring 39 ′ is provided so as to be interposed between the end face protection ring 39 ′ and the base portion 42. A base 42 that holds the flange 38 itself is fixed to the fixing device 30 ′ and the housing of the image forming apparatus main body 1.

  A part of the support member also serves as a heat conduction pipe. A pair of flanges 38 are provided at both ends of the support member, and face each other so as to sandwich end portions (hereinafter also referred to as sleeve end portions) 33a and 33b of the fixing sleeve 33 from both sides. Therefore, the pair of flanges 38 acts to restrict the movement of the fixing sleeve 33 in the thrust direction f (hereinafter simply referred to as the thrust direction f).

  However, since the fixing sleeve 33 smoothly rotates at a high speed in the space for winding the sleeve set between the pair of flanges 38, there is a need for a certain margin for the fixing sleeve 33 to move in the thrust direction f to some extent. Therefore, a predetermined gap is provided between the respective end portions 33 a and 33 b of the fixing sleeve 33 and the opposing surface (hereinafter referred to as receiving surface) G of the flange 38.

  Along with the rotation of the fixing sleeve 33, a shifting force in the thrust direction f (hereinafter, also referred to as shifting force or simply shifting) may be generated in the fixing sleeve 33. However, it is difficult to control this shifting force. In particular, when a deviation in parallelism or a left-right difference in nip pressure increases between a roller and a fixing sleeve 33 constituting a pressure member, which will be described later, a strong shifting force is generated. Therefore, the fixing sleeve 33 moves in the thrust direction f by receiving a shifting force in a space between the pair of flanges 38, that is, a space for winding the sleeve slightly wider than the sleeve width.

  When the fixing sleeve 33 is pushed by the shifting force and moves in one direction, the fixing sleeve 33 moves too much. If it is too close, stress concentrates on the end face E (hereinafter also simply referred to as the sleeve end face) E of the fixing sleeve 33 and the fixing sleeve 33 is not only deformed, but also may cause a failure. In order to prevent such an obstacle, as shown in FIG. 8, an interference member (hereinafter referred to as an end face protection ring) 39 'that interferes as a detent is provided with each end face (hereinafter also referred to as a sleeve end face) of the fixing sleeve 33. It was sandwiched between E and the receiving surface G of the flange 38. Even if the end face protection ring 39 ′ is deviated from the fixing sleeve 33, the end face protecting ring 39 ′ interferes to prevent the movement of the fixing sleeve 33 as a detent and exhibits its effect.

  As a technique for preventing stress from concentrating on the end of the rotating member corresponding to the fixing sleeve in the thrust direction, in the heating device of the film heating method, the fixing device is configured with a metal film, and the film end is cracked. There is known one that does not generate (see, for example, Patent Document 1).

  However, as the speed of printers, copiers, facsimiles, etc. increases, the load due to the shifting force on the fixing sleeve tends to increase. Therefore, the fixing sleeve may get over the end face protection ring, deform the end face protection ring, and further cut it. Due to such a phenomenon, there is a problem that the fixing sleeve is damaged by directly contacting the receiving surface of the flange or the like.

  The technique disclosed in Patent Document 1 is a fixing device that uses a metal film as a rotating member corresponding to a fixing sleeve so that cracks are not generated at the end of the film. It does not restrict the sleeve from being biased toward its thrust direction. Therefore, it does not suggest a means for solving the problem that the sleeve end portion of the fixing sleeve contacts and damages the flange.

  The present invention has been made to solve the above-described problems of the prior art, and a fixing device and an image forming apparatus that can prevent the fixing sleeve from being deteriorated and damaged by approaching the fixing sleeve in the thrust direction. An object is to provide an apparatus.

In order to achieve the above object, a fixing device according to the present invention includes a flexible cylindrical fixing sleeve and a generally cylindrical tube that rotatably supports the fixing sleeve while being in surface contact with the inner peripheral surface of the fixing sleeve. A support member, a pressure member that forms a nip portion with the support member across the fixing sleeve, and a thrust end of the fixing sleeve facing the end surface in the thrust direction. A fixing device for fixing an image to a recording material carrying an image at the nip portion, and having an outer diameter and an inner diameter, and having a substantially coaxial and idled hole with the fixing sleeve a plurality of disc, the size of the outer diameter and the inner diameter of the perforated disk, in other than the nip portion and the vicinity thereof, said fixing sleeve between the outer and inner diameters deformed in the diameter direction with the rotation Is dimensioned to contain band, said perforated disc is arranged so as to be in surface contact with the end surface of the fixing sleeve, wherein the plurality of perforated discs are selectively used at least two or more different materials in each perforated disc It is characterized by being configured .

  According to the present invention, it is possible to provide a fixing device and an image forming apparatus capable of preventing the fixing sleeve from being deteriorated and damaged by approaching the fixing sleeve in the thrust direction.

1 is an overall schematic view of an image forming apparatus using a fixing device according to an embodiment of the present invention. 1 is a cross-sectional view of a main part of a fixing device according to an embodiment of the present invention. FIG. 2 is a front view of a main part of the fixing device according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of a main part of the fixing device according to the first embodiment of the present invention, and is a diagram illustrating a relationship between a state in which the fixing sleeve rotates and a diameter of the end face protection ring. It is a principal part front view of the fixing device which concerns on 2nd Embodiment of this invention. It is a figure explaining the thermal deformation of the end surface protection ring which concerns on embodiment of this invention. It is a front view of the flange which concerns on 3rd Embodiment of this invention. It is a principal part front view of the conventional fixing device.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is an overall schematic view of an image forming apparatus as a printer using a fixing device according to an embodiment of the present invention. This printer is provided with a paper feed unit 2 having a plurality of paper feed trays 12A and 12B (hereinafter also simply referred to as paper feed trays 12) in which a paper 11 as a recording material is stored at the bottom of the image forming apparatus main body 1. The image forming unit 3 is disposed above the image forming unit 3. The sheets 11 and 11A according to the present embodiment correspond to the recording material according to the present invention.

  The image forming unit 3 includes image forming units 8Y, 8M, 8C, and 8K (hereinafter simply referred to as image forming units) having photosensitive drums 10Y, 10M, 10C, and 10K (hereinafter also simply referred to as photosensitive drums 10) as image carriers. Unit 8), intermediate transfer unit 7 having intermediate transfer belt 7A as a flexible intermediate transfer member wound around a plurality of rollers 4, 5, 6 and optical writing on each photosensitive drum. A writing unit 15 to perform and a fixing device 30 for fixing the unfixed toner image T to the paper 11 are provided. A transport path 16 including paper feed rollers 18A and 18B for transporting the paper 11 is formed between the paper feed unit 2 and the fixing device 30.

  Each image forming unit 8 includes a photosensitive drum 10 and a charging device, a developing device, and a belt cleaning device (not shown in FIG. 1) disposed around the photosensitive drum 10, and is removable from the image forming apparatus main body 1. The developing devices included in the image forming units 8Y, 8M, 8C, and 8K store yellow, magenta, cyan, and black toners, respectively. Note that yellow is associated with Y, magenta M, cyan with C, and black with K, and these colors are abbreviated as Y, M, C, and K as appropriate.

  Each developing device is configured to supply replenishment toner from a toner bottle (not shown) when the toner decreases. The intermediate transfer belt 7A is disposed to face each of the photosensitive drums 10Y, 10M, 10C, and 10K, and rotates and moves counterclockwise in FIG. 1 by driving one of the rollers by a drive motor (not shown). To do.

  Transfer rollers 14Y, 14C, 14M, and 14K (hereinafter also simply referred to as transfer rollers 14) serving as primary transfer means are respectively arranged inside the intermediate transfer belt 7A facing each photoconductor drum 10 for primary transfer. The transfer bias is applied. A belt cleaning device 17 that cleans the belt surface is disposed at a portion facing the roller 4. The intermediate transfer belt 7A, the plurality of rollers 4 to 6 around which the intermediate transfer belt 7A is wound, the transfer roller 14, and the belt cleaning device 17 are configured as an integral unit and can be attached to and detached from the image forming apparatus main body 1. .

  A secondary transfer roller 20 as a secondary transfer unit to which a secondary transfer bias is applied is in contact with the intermediate transfer belt 7 </ b> A at a portion facing the roller 6. A portion of the secondary transfer roller 20 and the intermediate transfer belt 7 </ b> A are disposed so as to face the conveyance path 23.

  The writing unit 15 irradiates the surface of each photosensitive drum 10 with light-modulated laser light to form latent images of Y, M, C, and K colors on the surface of the photosensitive member. The writing unit 15 is arranged below the image forming units 8Y, 8M, 8C, and 8K, and is configured so that laser irradiation is performed from the lower side of the apparatus toward the upper side of the apparatus.

  Next, the operation of the printer will be briefly described with reference to FIG. When the image forming operation is started, the photosensitive drums 10 of the respective image forming units 8 are rotated in the clockwise direction by a driving unit (not shown), and the surface of each photosensitive drum 10 is made to have a predetermined polarity by each charging device. It is charged like this. The charged surface of each photosensitive drum 10 is irradiated with laser light from the writing unit 15 to form an electrostatic latent image on each surface.

  At this time, the image information to be exposed on each photosensitive drum is single-color image information obtained by separating a desired full-color image into color information for each color of Y, M, C, and K. The electrostatic latent image formed in this way is visualized as a toner image formed by the toner of each developing device when passing between each photosensitive drum 10 and the developing device.

  The intermediate transfer belt 7A is moved in the counterclockwise direction by a driving unit (not shown) so that a full-color toner image is carried on the surface of the intermediate transfer belt 7A. Specifically, the toner images are transferred onto the surface of the intermediate transfer belt 7A by the transfer rollers 14M, 14C, and 14K in the order of the colors Y, M, C, and K from the most upstream in the belt moving direction to the downstream.

  First, a yellow toner image (hereinafter referred to as a Y image) is formed by an image forming unit 8Y provided with a Y-developing device. The Y image is transferred onto the surface of the intermediate transfer belt 7A by the transfer roller 14Y. On the transferred Y image, the magenta M image formed by the image forming unit 8M is overlaid and transferred by the transfer roller 14M. On top of this, the cyan C image formed by the image forming unit 8C is overlaid and transferred by the transfer roller 14C. In addition, the black K image formed by the image forming unit 8K is superimposed and transferred by the transfer roller 14K. In this way, the intermediate transfer belt 7A carries a full-color toner image on its surface.

  Residual toner adheres to the surface of each photosensitive drum 10 after the toner image is transferred. This residual toner is removed by the belt cleaning device 17. After the surface of each photoconductive drum 10 is cleaned in this manner, the surface potential is initialized by a charge removal process by a charge removal device (not shown), and the apparatus waits for the next image formation.

  On the other hand, the paper 11 is fed from the paper feed unit 2 and sent to the conveyance path 16 by the rotational drive of the paper feed roller 18A or the paper feed roller 18B. In order to detect the size and thickness of the paper 11, it is preferable to provide a paper detection mechanism (not shown) in the transport path 16.

  The sheet 11 sent to the conveyance path 16 is controlled in feeding timing by a registration roller pair 19 provided on the conveyance path 16 on the sheet feeding side with respect to the secondary transfer roller 20, and the roller 6 and the secondary transfer roller are controlled. 20 is sent to the opposite part.

  A transfer voltage having a polarity opposite to the toner charging polarity of the toner image carried on the surface of the intermediate transfer belt 7A is applied to the secondary transfer roller 20. The toner image on the surface of the intermediate transfer belt 7 </ b> A is transferred onto the paper 11 at a time by the reverse polarity transfer voltage. The registration roller pair 19 is provided on the feeding path 16 on the paper feeding side, that is, on the upstream side of the secondary transfer roller 20.

  The paper 11 to which the toner image has been transferred is conveyed to the fixing device 30, and heat and pressure are applied when passing through the fixing device 30, and the toner image is melted and fixed on the paper 11. The sheet 11 </ b> A on which the toner image is fixed is conveyed toward the discharge unit 21 located at the end of the conveyance path 23.

  The paper 11 </ b> A conveyed to the discharge unit 21 is discharged to a paper discharge tray 22 provided at the top of the image forming apparatus main body 1. Note that the toner remaining on the intermediate transfer belt 7A after the toner image is transferred to the paper 11 is removed by the belt cleaning device 17.

  Next, the configuration and operation related to the fixing device will be described with reference to FIG. FIG. 2 is an enlarged cross-sectional view of the fixing device according to the present embodiment. The fixing device 30 shown in FIG. 2 includes a fixing sleeve 33, a pressure member 31, a nip forming member 32, a heat conduction pipe 34, an infrared heater 36, a thermostat function unit (not shown), a drive source, and the like. Yes.

  The fixing sleeve 33 is rotatable in a cylindrical shape having flexibility. The pressure member 31 is a roller that is provided on the radially outer side of the fixing sleeve 33 and presses the fixing sleeve 33 radially inward, and constitutes a nip portion 29. The nip forming member 32 is provided inside the fixing sleeve 33 in the radial direction, and presses the fixing sleeve 33 and the sheet 11 as a recording material with the pressing member 31 therebetween. The fixing sleeve 33 fixes the toner image on the transfer paper P by heating the transfer paper P carrying the image with the toner T. The transfer paper P shown in FIG. 2 and FIG. 4 is schematically explained by enlarging the paper 11 shown in FIG.

  The heat conduction pipe 34 is generally cylindrical, is provided on the inner peripheral side of the fixing sleeve 33, and supports the fixing sleeve 33 rotatably. The infrared heater 36 is provided inside the heat conduction pipe 34 and heats the heat conduction pipe 34. The heat conduction pipe 34 supports the fixing sleeve 33 so as to slide in surface contact with the outer periphery thereof. The infrared heater 36 heats the paper 11 from the heat conducting pipe 34 through the fixing sleeve 33. The sheet 11 carrying the toner image is heated to fix the toner image.

  The nip portion 29, the pressure member 31, and the fixing sleeve 33 according to the present embodiment are the nip portion, the pressure member, and the fixing sleeve according to the present invention. Further, the heat conduction pipe 34 and the nip forming member 32 according to the present embodiment correspond to the support member according to the present invention.

  The pressure member 31 is made of, for example, a metal core and silicone rubber. The nip forming member 32 is a member formed by, for example, winding fluoro rubber or the like with a PTFE (polytetrafluoroethylene) sheet or the like. The fixing sleeve 33 is a member composed of a base material such as SUS (stainless steel) or Ni (nickel), an elastic layer of silicone rubber, and a release layer of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer). It is.

  The heat conduction pipe 34 is made of a base material such as SUS or Ni, for example, and the outer peripheral surface in contact with the fixing sleeve 33 is coated with a property having both smoothness and wear resistance (hereinafter referred to as slidability), for example, It is desirable to apply a fluorine-based coating. The heat conducting pipe 34 is fixed on the inner side by a fixing plate 35a. Further, the heat conducting pipe 34 is fixed on the outside side by a fixing plate 35b. Then, the reinforcement stay 37 is configured to connect and reinforce each part on the inner side of the heat conduction pipe 34.

  The pressing member 31 applies a nip pressure to the nip forming member 32 by an urging means of an elastic member such as a spring or a leaf spring (not shown). The heating means need not be limited to the infrared heater 36 as long as it has an effect of instantaneously heating the nip upstream side of the heat conduction pipe 34, that is, the lower side of the heat conduction pipe 34 shown in FIG. . That is, induction heating, a resistance heating element, or the like may be used as a heating means instead of the infrared heater 36. Further, if there is a method of heating the fixing sleeve 33 without using the heat conduction pipe 34, that may be used.

  When the infrared heater 36 generates heat, the heat conduction pipe 34 is heated, and heat is transmitted to the fixing sleeve 33 in surface contact with the heat conduction pipe 34. In order to improve the thermal conductivity from the heat conduction pipe 34 to the fixing sleeve 33, it is necessary to have a good contact property in which the heat conduction pipe 34 and the fixing sleeve 33 are in uniform and intimate contact.

  In particular, the heat conduction pipe 34 and the fixing sleeve 33 are not in contact with each other to generate an air layer. The heat insulating portion by the air layer deteriorates the thermal conductivity, and the heat supply to the fixing sleeve 33 is insufficient. On the other hand, in order to maintain a prescribed temperature, it is necessary to heat more, which naturally results in contrary to energy saving. Further, since the heat conduction pipe 34 is heated to a specified temperature or higher, the durability of the coating film on the surface, that is, the lifetime is also adversely affected.

  On the other hand, since the setting is made to improve the contact between the heat conducting pipe 34 and the fixing sleeve 33, if the friction is excessively increased, the rotational load of the fixing sleeve 33 increases, which hinders the rotation of the fixing sleeve 33. That is, there arises a problem that the fixing sleeve 33 slips with respect to the outer peripheral surface of the pressure member 31 that is rotationally driven by a drive source (not shown).

  When the fixing sleeve 33 slips, heat is not diffused by rotation, and parts are deteriorated due to local overheating, leading to a decrease in durability. In addition, the transferability of the transfer material is reduced, and a deviation occurs in the amount of heat supplied, resulting in image quality anomalies such as poor fixing and gloss deviation. Therefore, the slidability of the outer peripheral surface of the heat conducting pipe 34, that is, the property having both the smoothness and the wear resistance is an important factor that determines the energy saving, durability and image quality.

  The heat conduction pipe 34 has a structure in which an outer peripheral length is determined by an opening area, and the opening is sandwiched between a fixing plate 35b and an internal fixing plate 35a. In addition, the infrared heater 36 and the like are accommodated in a heat conduction pipe 34 having a limited size without wasting space.

  Each of the fixing plates 35a and 35b has a U-shaped cross section, and the nip forming member 32 is held in the concave portion of the fixing plate 35b. The fixing sleeve 33 is sandwiched by receiving a nip pressure from the pressure member 31 and the nip forming member 32. When the pressure member 31 is driven to rotate by a drive source (not shown), the fixing sleeve 33 that has been subjected to the reaction of the frictional force is also rotated in a driven manner.

  The transfer paper P on which an image is formed with the toner T shown in FIG. 2 is fixed at the nip portion 29 by the pressure of the pressure member 31 and the heat of the fixing sleeve 33. The fixing sleeve 33 whose temperature has been lowered by the fixing operation is heated again by the infrared heater 36. Note that an infrared heater 36 is turned on / off by a thermostat function unit (not shown) so as to be stabilized at a target temperature.

(First embodiment)
Next, the fixing sleeve 33 and the end face protection ring 39 will be described in detail with reference to FIGS. FIG. 3 is a front view of an essential part of the fixing device according to the first embodiment of the present invention. FIG. 4 is a main part explanatory view of the fixing device according to the first embodiment of the present invention, and is a view for explaining the relationship between the state in which the fixing sleeve 33 rotates and the diameter of the end face protection ring 39. The end face protection ring 39 has a perforated disk shape with an outer diameter D1 and an inner diameter D2, and protects the sleeve end face E while making surface contact with the sleeve end face E. In addition to reference numerals D1 and D2, reference numeral D3, which will be described later, is also applied to inner diameters, outer diameters, hole diameters, and the like, which have substantially the same dimensions as those of D1, D2, and D3.

  In the nip portion 29, the fixing sleeve 33 sinks further to the inside closer to the rotation axis than the innermost radius due to the deformation accompanying the rotation. In this state, the end surface protection ring 39 protects the end surface E of the fixing sleeve 33 in a state where the fixing sleeve 33 is greatly deformed. The sleeve end surface E is clearly shown in FIGS. 3, 5, 7, and 8. FIG.

  The main part of the fixing device shown in FIG. 3 supports a flange 70, a flexible cylindrical fixing sleeve 33, and the fixing sleeve 33 that is slidable, that is, wound so as to slide in surface contact. The main part is comprised by the support member. The support member is generally cylindrical and is configured to support it while being in surface contact with the inner peripheral surface of the fixing sleeve 33. However, in FIG. 3, most of the support member is hidden inside the fixing sleeve 33.

  Hereinafter, the flange 70, the fixing sleeve 33, and the end face protection ring 39 according to the present embodiment will be described in detail. On the outer peripheral surface of the flange 70, the end face protection ring 39 is provided as a detent at a position where the end portion 33 b in the thrust direction of the fixing sleeve 33 interferes with the end face E. The end face protection ring 39 is provided so as to be interposed between the end face protection ring 39 and the base portion 42. A base 42 that holds the flange 70 itself is fixed to the fixing device 30 and the housing of the image forming apparatus main body 1.

  According to the present embodiment, “on the outer peripheral surface of the flange 70, the end face protection ring 39 is provided as a detent at a position where the end portion 33 b in the thrust direction of the fixing sleeve 33 interferes with the end face E. The term “has” corresponds to “a flange that is provided at an end portion in the thrust direction of the fixing sleeve so as to face the end surface thereof and restricts movement of the fixing sleeve in the thrust direction” according to the present invention.

  The nip release portion 51 shown in FIG. 4 is downstream of the nip portion 29 with respect to the P transport direction. In this nip release portion 51, the stress from the inner diameter side to the outer diameter side of the end face protection ring 39 and the stress in the direction that prevents rotation of the end face protection ring 39 act synergistically, and the sleeve end face E causes the end face protection ring 39 to move. There is a risk of getting over.

  At this time, the end portions 33 a and 33 b of the fixing sleeve 33 may act like a rotary blade in a pseudo manner on the end surface protection ring 39, which may cause damage to the end surface protection ring 39. On the contrary, the end face protection ring 39 acts like a rotary blade on the end portions 33a and 33b of the fixing sleeve 33 in a pseudo manner, and may cause damage to the sleeve 33 end portions 33a and 33b. Further, when the sleeve end portions 33a and 33b apply stress in a direction that prevents rotation to the end face protection ring 39, vibration with abnormal noise may occur.

  The end face protection ring 39 has a perforated disk shape having an outer diameter D1 and an inner diameter D2, and protects the sleeve end face E while being in surface contact with the sleeve end face E. The outer diameter D1 and the inner diameter D2 of the end face protection ring 39 are set to dimensions that include a region in which the fixing sleeve 33 is deformed in the diameter direction with rotation. The “outer diameter D1 and inner diameter D2” according to the present embodiment correspond to the “outer diameter and inner diameter including a region in which the fixing sleeve deforms in the diameter direction as the fixing sleeve rotates” according to the present invention.

  If the end surface E of the fixing sleeve 33 is held by the end surface protection ring 39, the sleeve end surface E can be prevented from being deteriorated and broken. That is, the end face protection ring 39 is dimensioned to the prescribed outer diameter D1 and inner diameter D2, and has a wider area within the range of the outer diameter D1 and inner diameter D2 and closer to the thrust direction f of the sleeve end face E. On the other hand, the stress can be uniformly received without concentration of stress on a part of the sleeve end surface E. 3, FIG. 5 and FIG. 7 show the configuration of one side of the flange 38 and the fixing sleeve 33, but the opposite side (not shown) is also configured symmetrically.

  Next, a shift occurring in the fixing sleeve 33 will be described with reference to the drawings. In the fixing device 30, when the paper 11 is passed according to the rotation of the fixing sleeve 33, the contact friction between the fixing sleeve 33 and the pressure member 31 is not necessarily equal to the paper 11. In addition, as shown in FIGS. 3 and 8, the fixing sleeve 33 is displaced in the f direction due to the accuracy problem of the rotating machine and the like. The direction of the shift is difficult to predict because it has many influential factors such as a dimensional accuracy error of the component and a temperature deviation in the thrust direction.

  As described above, in the fixing device 30 and the image forming apparatus according to the present embodiment, when the fixing sleeve 33 is shifted, the end surface E of the fixing sleeve 33 is directly or indirectly connected to the end surface protection ring 39a on the flange 70 side. Therefore, the movement of the fixing sleeve 33 in the thrust direction f is regulated while being stably held by the receiving surface G having a larger area. That is, stress concentration on the sleeve end portions 33a and 33b due to the fixing sleeve 33 approaching the flange 70 can be reduced. As a result, the fixing sleeve 33 can be prevented from being damaged. Therefore, it is possible to prevent the fixing sleeve 33 from being deteriorated and damaged due to the fixing sleeve 33 being approached in the thrust direction f.

(Second Embodiment)
A measure for eliminating the damage of the end face protection ring 39 described above along FIG. 4 is shown in the second embodiment. In the nip portion 29 clearly shown in FIG. 4, it is conceivable that the surface of the end face protection ring 39 is expanded further to the inner side near the rotation axis than the minimum moving radius due to the fixing sleeve 33 entering the inner side near the rotation axis. . However, as is obvious from FIG. 3, if the minimum inner diameter D2 of the end face protection ring 39 is made smaller than the outer diameter of the cylinder 79 forming the fixing sleeve holding surface, the end face protection ring 39 is fitted into the cylinder 79. I can't.

  FIG. 5 is a front view of an essential part of the fixing device according to the second embodiment of the present invention. As shown in FIG. 5, a two-body coupling type of a flange 70a and a flange 70b is configured. A constricted portion 71 is provided on the flange 70a, and the end face protection ring 39a is fitted freely idle. The flange 70b has a necessary thickness regardless of the narrow diameter D3 of the constricted portion 71. The fixing sleeve 33 is wound around the flange 70b having the necessary thickness and is rotatably supported.

  With the above-described configuration, the end face protection ring 39a has a wider range that can be protected toward the center of the rotation axis. The flange 70a is provided with a constricted portion 71 that is narrower than a diameter D3. Even if the hole diameter D3 is reduced, the constricted portion 71 is fitted while passing through the hole diameter D3. That is, the flange 70a is provided with a constricted portion 71 in which an end face protection ring 39a narrowed to an inner diameter D3 is narrowed to a diameter D3 or less so that it can be freely fitted.

  The “configuration in which the flange 70a is provided with a constricted portion 71 in which the end face protection ring 39a narrowed to the inner diameter D3 is narrowed to a diameter D3 or less so that the flange 70a can be freely idled” refers to the present invention. "The flange includes a constricted portion having an outer diameter smaller than the inner diameter including a region in which the fixing sleeve deforms in the diametrical direction, and the constricted portion passes through the hole of the perforated disk". Moreover, although the code | symbol D3 shown in FIG. 5 has shown both the internal diameter D3 of the end surface protection ring 39a and the diameter D3 of the constriction part 71, both contain a slight dimensional difference.

  The flange 70 a and the flange 70 b are joined by the constriction 71 on the rotation shaft of the fixing sleeve 33 after the end face protection ring 39 is fitted to the constriction 71. Further, it is desirable that the flange 70a and the flange 70b are firmly bonded. With such a configuration, the fixing sleeve 33 can cope with a high load due to high-speed rotation. Further, it is possible to prevent the fixing sleeve 33 from entering the inner side of the end face protection ring 39 in the rotation axis direction. Accordingly, it is possible to prevent the fixing sleeve 33 from being deteriorated and damaged due to the fixing sleeve 33 approaching the thrust direction f.

  According to the present embodiment, “the flange 70a and the flange 70b are coupled by the constricted portion 71 on the rotation shaft of the fixing sleeve 33 after the end face protection ring 39 is fitted to the constricted portion 71” according to the present invention. The “flange corresponds to a two-body coupling type configuration in which the constricted portion is coupled on the rotation shaft of the fixing sleeve”.

  Next, thermal deformation of the end face protection ring 39 will be described with reference to FIG. FIG. 6 is an explanatory diagram for an end face protection ring according to an embodiment of the present invention. In the nip portion 29 shown in FIG. 6, a part of the end face protection ring 39 protrudes from the receiving surface G of the flange 70. Therefore, the entire surface of the end face protection ring 39 is not received evenly on the receiving surface G of the flange.

  That is, as described above with reference to FIG. 4, the end surface E of the fixing sleeve 33 that bends inward from the inner diameter D <b> 2 of the end surface protection ring 39 could not be protected in the nip portion 29. Further, the end face protection ring 39 has a frictional resistance only at the portion of the nip portion 29 that contacts the receiving surface G of the flange 70 when rotating. For this reason, the end face protection ring 39 is deformed by receiving a stress that prevents the rotation of the end face protection ring 39 unevenly between the portions that do not contact the receiving surface G. In order to improve this, the end face protection ring 39 needs to be supported evenly over the entire receiving surface G of the flange.

  Further, when a soft material is used for the end face protection ring 39, thermal deformation is likely to occur. Further, if the end face protection ring 39 is made thicker, the end face protection ring 39 is not easily deformed, but the rotation of the end face protection ring 39 is hindered, and the wear generated between the fixing sleeve 33 becomes severe and the end face protection ring 39 is cut. It becomes easy to do. On the contrary, if the material of the end face protection ring 39 is hard, the frictional resistance is increased and the rotation is not smooth as compared with the soft one, and abnormal noise is easily generated from the end face protection ring 39 that rubs against the sleeve end E. .

(Third embodiment)
FIG. 7 is a front view of a flange according to the third embodiment of the present invention, and is configured as a two-body coupling type of the flange 70a and the flange 70b shown in FIG. Two end face protection rings 39a and 39b are fitted to the constricted portion 71 of one flange 70a so as to freely rotate. The fixing sleeve 33 is wound around the other flange 70b and is rotatably supported.

  The two end face protection rings 39a and 39b are easier to rotate than the flange 70 using the one end face protection ring 39 shown in FIG. This prevents local wear of the end face protection rings 39a and 39b due to rotation of the. Furthermore, there is an effect that the deformation of the end face protection rings 39a and 39b can be easily prevented.

  In addition, when two thin end face protection rings 39a and 39b are used in an overlapping manner, rotation is smoother than when one thick end face protection ring 39 is used. Therefore, the deformation resistance against the shifting force from the fixing sleeve end surface E is greater than that of the single end surface protection ring 39, and the deformation is less likely to occur. In addition, “using two end face protection rings 39a and 39b in an overlapping manner” according to the present embodiment means “having a plurality of perforated disks” according to the present invention.

  Furthermore, as a result of the combination experiment for each material, the end face protection rings 39a and 39b are easier to rotate because dissimilar materials reduce the coefficient of friction when these two perforated disks are rotated. I know. Assuming a pseudo rotary blade by the fixing sleeve 33, a hard material is used for the end face protection ring 39b that directly faces the end face E of the fixing sleeve 33, and the end face protection ring 39a that is far from the end face E has low rigidity. It is preferable to use a material having a low coefficient of friction.

  In addition, according to the present embodiment, “the end face protection rings 39a and 39b are made of different materials and reduce the coefficient of friction when the two perforated disks are rotated in an overlapping manner” This perforated disk means that at least two or more different materials are used for each perforated disk. Further, according to the present embodiment, “a hard material is used for the end surface protection ring 39b facing directly to the end surface E of the fixing sleeve 33, and a material having a low rigidity and a low friction coefficient is used for the end surface protection ring 39a far from the end surface E. "Means that a perforated disk made of a material having low rigidity and low friction coefficient is disposed on the side away from the end face of the fixing sleeve" according to the present invention.

  As described above, in the fixing device 30 and the image forming apparatus according to the present embodiment, when the fixing sleeve 33 is shifted, the end surface E of the fixing sleeve 33 is directly or indirectly connected to the end surface protection rings 39a and 39b. The fixing sleeve 33 is restricted from moving in the thrust direction f while being stably held by the receiving surface G having a larger area. That is, stress concentration on the sleeve end portions 33a and 33b due to the fixing sleeve 33 approaching the flanges 70 and 70a can be reduced. As a result, the fixing sleeve 33 can be prevented from being damaged. Accordingly, it is possible to prevent the fixing sleeve 33 from being deteriorated and damaged by the fixing sleeve 33 approaching the thrust direction f.

11, 11A paper (recording material)
30, 30 ′ fixing device 32 nip forming member (supporting member)
33 fixing sleeve 33a, 33b sleeve end 38, 70, 70a, 70b flange 39, 39a, 39b end face protection ring (perforated disk)
34 Heat conduction pipe (support member)
51 Nip release part 71 Constriction part D1 Outer diameter D2 Inner diameter, hole diameter, diameter D3 Inner diameter, hole diameter, diameter E Sleeve end face f Thrust direction G Receiving face

JP 2006-293225 A

Claims (6)

A flexible cylindrical fixing sleeve, a generally cylindrical support member that rotatably supports the fixing sleeve while being in surface contact with the inner peripheral surface of the fixing sleeve, and the support member sandwiching the fixing sleeve And a pressure member that forms a nip portion, and a flange that is provided at an end portion in the thrust direction of the fixing sleeve so as to face the end surface thereof and restricts movement of the fixing sleeve in the thrust direction, and the nip portion In a fixing device for fixing an image on a recording material carrying an image in
A plurality of perforated discs having an outer diameter and an inner diameter, which are substantially coaxial with the fixing sleeve and are freely rotatable, and the outer diameter and the inner diameter of the perforated disc are the same as the outer diameter except for the nip portion and the vicinity thereof. The fixing sleeve is dimensioned to include a region in which the fixing sleeve deforms in the diameter direction as it rotates, and the perforated disk is disposed so as to be in surface contact with the end surface of the fixing sleeve, and the plurality of The hole disk is configured by using at least two different kinds of different materials for each hole disk . The flange includes a constricted portion having an outer diameter smaller than an inner diameter including a region where the fixing sleeve deforms in a diametrical direction,
The fixing device according to claim 1, wherein the constricted portion is configured to penetrate a hole of the perforated disk.   2. The fixing device according to claim 1, wherein the flange has a two-body coupling structure in which the constricted portion is coupled on a rotation shaft of the fixing sleeve. 2. The fixing device according to claim 1 , wherein the plurality of perforated disks are provided with a perforated disk having a low rigidity and a low friction coefficient on a side away from an end face of the fixing sleeve. Among the plurality of perforated discs, a fixing device according to the whole surface of the board which is remote from the end face of the fixing sleeve, in any one of claims 1 to 4, characterized in that received in the receiving surface of the flange . An image forming apparatus comprising: a fixing device according to any one of claims 1-5.

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