JP2009204731A - Fixing device and image forming apparatus - Google Patents

Abstract

In a fixing device in which a heat insulating member such as a heat insulating bush is attached to an end of a fixing member such as a fixing roller, it is possible to prevent parts from falling off and to prevent wear between parts.
A fixing member 71 having a heat source and rotatable about a predetermined axis, a substantially annular heat insulating member 76a externally fitted to an end portion of the fixing member, and a locking portion 771a which is substantially ring-shaped and protrudes inward. , 772a and a retaining ring member 77a used for retaining the heat insulating member, and the retaining ring member 77a is fitted on the outer peripheral surface of the fixing member 71 protruding outward in the axial direction from the heat insulating member 76, and The locking portion reaches the inner peripheral surface of the fixing member 71 and is securely locked and fixed.
[Selection] Figure 5

Description

  The present invention relates to a fixing device used in an image forming apparatus using an electrophotographic system such as a printer, a copying machine, a facsimile machine, and a multifunction machine, and an image forming apparatus including such a fixing device.

  A fixing device used in an image forming apparatus using an electrophotographic method usually has a fixing roller provided with a heating means that generates heat by energizing the inside, and a peripheral surface of the fixing roller facing the peripheral surface of the fixing roller. Each of the sheets on which the toner image has been transferred is heated by the fixing roller by passing through a nip formed between the rotating fixing roller and the pressing roller. The upper toner image is subjected to a fixing process.

  The end of the fixing roller is supported by a support member such as a ball bearing. Between the core metal of the fixing roller having a heating means and the ball bearing, the end of the fixing roller is protected from heat and from the end of the roller. In order to prevent heat dissipation, a heat insulating bush member made of a heat resistant resin is disposed (see, for example, Patent Document 1).

JP 2005-325957 A

  When the heat-insulating bush member is externally fitted to the end portion of the fixing roller, the C-shaped ring for retaining is fitted into a groove portion formed in the fixing roller as a retaining ring. In the technique of the above-mentioned Patent Document 1, a C-shaped retaining ring is locked to the heat insulating bush member, and even when the fixing roller and the heat insulating bush member do not rotate integrally due to expansion of the heat insulating bush member or the like. Since the retaining ring is locked to the heat insulating bush member, the heat insulating bush member and the retaining ring rotate together, and the retaining ring functions as a retaining member for the heat resistant bush.

  However, when the retaining ring rotates together with the heat-resistant bush in this way, the retaining ring relatively rubs against the fixing roller, and noise is generated between the retaining groove and the annular groove into which the retaining ring is fitted. Or the retaining ring may fall off. At the same time, the core roller of the fixing roller itself is formed into a thin cylindrical shape in order to reduce the burden on driving the fixing roller and reduce the weight and improve the heat conduction efficiency. In such a case, the recess of the annular groove into which the retaining ring is fitted cannot be made too deep, and a new problem arises that it is not easy to satisfactorily fit the retaining ring into the annular groove.

  Therefore, in view of the above technical problems, the present invention may be used even when a heat insulating member such as a heat insulating bush slips with respect to the fixing member or when a groove for fitting a retaining ring to the fixing member becomes shallow. An object of the present invention is to provide a fixing device that suppresses the falling of components and prevents the occurrence of wear between components and an image forming apparatus using such a fixing device.

  In order to solve the above technical problem, the fixing device of the present invention is a fixing device that heats the developer on a recording medium carrying the developer and fixes the developer on the recording medium. A fixing member that includes a heat source and is rotatable about a predetermined axis, a substantially annular heat insulating member that is externally fitted to an end portion of the fixing member, and a locking portion that is substantially ring-shaped and protrudes inward. A retaining ring member used for retaining the heat insulating member, and the retaining ring member is fitted on an outer peripheral surface of the fixing member protruding outward in the axial direction from the heat insulating member. The fixing member is locked to the inner peripheral surface.

  In the fixing device of the present invention, the heat insulating member may be provided to be interposed between the fixing member and a bearing member that rotatably supports both end portions of the shaft of the fixing member. A concave portion having a shape along the outer shape of the retaining ring member may be provided on a side surface of the heat insulating member adjacent to the retaining ring member. Further, a rotation driving member for transmitting rotation driving to the fixing member is provided, and the retaining ring member disposed on the rotation driving member side is biased toward the rotation driving member side in the axial direction of the fixing member. It may be provided as follows. Further, the retaining ring member can be formed by bending a metal bar-like member, and a pair of locking portions can be provided, and a notch can be provided on one of them. Further, the fixing member protruding outward in the axial direction from the heat insulating member is formed so that a locking hole for locking the locking portion penetrates from the outer peripheral surface of the fixing member to the inner peripheral surface. It can be a structure.

  The image forming apparatus of the present invention capable of solving the above technical problem includes an image carrier for forming a required electrostatic latent image on a recording medium, and the recording medium on which the electrostatic latent image is formed. A fixing member having a heat source for fixing the developer thereon and rotatable about a predetermined axis, a substantially annular heat insulating member fitted on the end of the fixing member, and a latch that is substantially ring-shaped and protrudes inward A retaining ring member that is used to prevent the heat insulating member from falling off, and the retaining ring member is fitted on the outer peripheral surface of the fixing member that protrudes outward in the axial direction from the heat insulating member. The locking portion reaches the inner peripheral surface of the fixing member and is locked.

  According to the fixing device of the present invention, even when the heat-resistant member slips with respect to the fixing member, the pair of locking portions of the retaining ring member reaches the inner peripheral surface of the fixing member and is locked. Therefore, there is an advantage that the retaining ring member does not come off the fixing member. Further, in the case where the concave portion having a shape along the outer shape of the retaining ring member is provided on the side surface of the heat insulating member, the retaining ring member is fixed to the heat insulating member, and the slip of the heat resistant member with respect to the fixing member itself Can be prevented in advance.

  Hereinafter, an image forming apparatus and a fixing device according to preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of an image forming apparatus 1 according to the first embodiment of the present invention. The image forming apparatus 1 is an apparatus that forms a latent image on a recording medium P such as paper by an electrophotographic method, develops the toner with a developer, and fixes the latent image. In the image forming apparatus 1, image forming units 16Bk, 16Y, 16M, and 16C that form toner images of black, yellow, magenta, and cyan are arranged on the recording medium P along the conveyance direction of the recording medium P. Composed. Each of the image forming units 16Bk, 16Y, 16M, and 16C includes a photosensitive drum 52Bk, 52Y, 52M, and 52C that is a cylindrical image carrier, and a charging device, a developing device, and a photosensitive member cleaning device (not shown). ing. These image forming units 16Bk, 16Y, 16M, and 16C are integrally configured, and can be detached from the image forming apparatus 1. For this purpose, the upper cover 23 of the image forming apparatus 1 is provided so as to be openable and closable.

  The exposure devices 21Bk, 21Y, 21M, and 21C are arranged to face the upper portions of the respective photosensitive drums 52Bk, 52Y, 52M, and 52C, and are supported by the upper cover 23. Each exposure device 21Bk, 21Y, 21M, 21C selectively exposes the surface of each photoconductor drum 52Bk, 52Y, 52M, 52C to form an electrostatic latent image. The transfer rollers 51Bk, 51Y, 51M, and 51C are opposed to the respective photosensitive drums 52Bk, 52Y, 52M, and 52C from the lower side of the apparatus, and are arranged via the conveyance belt 17 for conveying the common recording medium P in each color. The

  The paper feed cassette 11 is disposed below the image forming apparatus 1 and accommodates the recording medium P. A paper feed mechanism is disposed adjacent to the front end of the paper feed cassette 11. The paper feed mechanism includes paper feed rollers 12a and 12b and a separation roller 13, and separates and feeds the recording media P one by one. Conveying rollers 14 and 15 are provided in the upper part of the paper feeding mechanism.

  The fixing device 7 is disposed on the downstream side of the conveying belt 17 where the cylindrical photosensitive drums 52Bk, 52Y, 52M, and 52C and the transfer rollers 51Bk, 51Y, 51M, and 51C are opposed to each other. Is removable. The detailed structure of the fixing device 7 will be described later. The recording medium P discharged from the fixing device 7 is transported by the discharge roller 19 and then discharged onto the upper cover 23 by the discharge transport roller 20.

In addition to plain paper, OHP sheets, cards, postcards, thick paper weighing more than 200 g / m ² , envelopes, special paper such as coated paper with a large heat capacity, and other films may be used as the recording medium. it can. The image forming apparatus 1 is a printer, a copier, a facsimile machine, a multifunction machine, or the like, and may be any type that can use the fixing device to which the present invention is applied.

  Next, the fixing device 7 will be described. FIG. 2 is a cross-sectional view of the main part when viewed from the recording medium entering direction of the fixing device in the first embodiment. FIG. 3 is a perspective view showing an end portion of the fixing roller in the first embodiment. FIG. 4 is a side view showing an end portion of the fixing roller in the first embodiment. FIG. 5 is an exploded perspective view showing an end portion of the fixing roller in the first embodiment.

  As shown in FIG. 2, the fixing device 7 is a device that heats and fixes a toner image formed by a developer on a recording medium together with pressure, and fixes an unfixed toner image on the recording medium P. The nip portion is formed by press-contacting the fixing roller 71 as a fixing member and the pressure roller 72 by a pressure unit (not shown). The fixing roller 71 is, for example, a cylindrical hollow roller having an outer diameter of 25 mm. A heat-resistant elastic layer having a thickness of 1.0 mm made of silicone rubber is formed on the outer peripheral surface of a steel core bar 711, and is further separated on the outer peripheral surface. A fluororesin layer having a thickness of 0.03 mm is formed as a mold layer. In the present embodiment, steel is used for the core metal 711, but other metals such as aluminum may be used. The pressure roller 72 is, for example, a cylindrical solid roller having an outer diameter of 24 mm, a heat-resistant elastic layer made of foamed silicone rubber is formed on the outer peripheral surface of a steel core, and a release layer is further formed on the outer peripheral surface. As a fluororesin layer having a thickness of 0.03 mm. Both ends of the pressure roller 72 are rotatably supported by pressure roller bearings 79a and 79b.

  Near the surface of the fixing roller 71, a thermistor is disposed as a temperature detecting element (not shown). A halogen heater 74 functioning as a heat source is instructed inside the fixing roller 71 by heater support members 80a and 80b. It is arranged in a state. The heat source is not limited to the halogen heater 74, and induction heating means, other heat sources, and the like can be used. Further, side plates 78 a and 78 b fixed to the apparatus housing as a frame member are disposed on the left and right sides of the fixing roller 71. At both ends of the fixing roller 71, heat insulating bushes 76a and 76b made of a heat-resistant resin and functioning as heat insulating members for the fixing roller 71 are fitted on the outer peripheral surface of the core metal.

  The heat insulating bushes 76a and 76b have a short cylindrical or ring shape in the axial direction made of a heat resistant resin, and slit portions 761a and 761b are provided to prevent the heat insulating bushes 76a and 76b from cracking due to thermal expansion. On the end side, flanges 762a and 762b projecting radially outward from the peripheral surface are provided. Examples of the heat resistant resin constituting the heat insulating bushes 76a and 76b include a fluororesin such as silicon resin and PTFE (polytetrafluoroethylene), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), and the like. Inside the heat insulating bushes 76a and 76b, the outer periphery of the end portion of the fixing roller 71 is disposed in contact with the outer periphery of the fixing roller 71, and outside the heat insulating bushes 76a and 76b, the ball bearings 75a and 75b are further connected to the apparatus housing. It is supported by the fixed side plates 78a and 78b. The inner diameters of the heat insulating bushes 76a and 76b are slightly smaller than the outer diameter of the fixing roller 71. When the heat insulating bushes 76a and 76b are fitted on the fixing roller 71, the inner diameters are slightly elastically deformed to widen the diameter. It is fitted on the fixing roller 71.

  Ball bearings 75a and 75b, which are fixing roller bearings, are members in which a plurality of steel balls are interposed between an inner ring and an outer ring so that the inner ring and the outer ring can rotate smoothly. 78a, 78b and the heat insulating bushes 76a, 76b, the inner rings of the ball bearings 75a, 75b are fitted on the heat insulating bushes 76a, 76b, and the flanges 751a, 751b of the outer rings of the ball bearings 75a, 75b are provided. The outer rings of the ball bearings 75a and 75b are fixed in contact with the side plates 78a and 78b.

  The retaining rings 77a and 77b are members that prevent the heat insulating bushes 76a and 76b from coming off from the end of the fixing roller 71. In the present embodiment, the linear members having a desired spring property made of metal such as stainless steel. Is formed by bending. As shown in FIG. 4, the retaining ring 77 a is formed by extending one linear metal member so as to be routed in a circle along the outer periphery of the fixing roller 71, but the ends are close to each other. The straight portion 773a extends straight outward from the circumference in the tangential direction, and is bent almost perpendicularly at the corner portion 774a from a portion that swells slightly outward so that the locking portion 771a is a core metal of the fixing roller 71. 711 has a shape reaching the inner peripheral side. In addition, a locking portion 772a that protrudes radially inward in a mountain shape is provided on the opposite side of the circumference facing the locking portion 771a. The retaining rings 77a and 77b having such a shape are fitted into both ends of the cored bar 711 of the fixing roller 71, respectively. The retaining ring 77a sandwiches the flange portion of the heat insulating bush 76a and the ball bearing 75a between the side plate 78a, and the retaining ring 77b sandwiches the flange portion of the heat insulating bush 76b and the ball bearing 75b and the drive gear 73 between the side plates 78b. It is arranged. As described above, the fixing roller 71 is configured to prevent dropping due to movement in the axial direction, which is the axial direction.

  The locking portion 771a and the locking portion 772a of the retaining ring 77a are cored by a coupling hole 712 formed of a pair of elongated through holes provided in the cored bar 711 of the fixing roller 71 as shown in FIGS. It is fixed by being fitted so as to enter the inside of the gold. Here, the coupling hole 712 is a hole provided in the core metal 711 of the fixing roller 71 so as to penetrate the inner side and the outer side, and is formed at a position facing the locking portion 772a and the locking portion 771a on the circumference. Yes. With the locking portions 771a and 772a of the retaining rings 77a and 77b fitted in the coupling holes 712, the retaining rings 77a and 77b are surely fixed to the outer peripheral portion of the fixing roller 71, so It is possible to prevent parts from falling off due to the axial movement of the bushes 76a and 76b and the ball bearings 75a and 75b.

  Next, the operation of the image forming apparatus 1 of this embodiment will be described. First, the recording medium P stored in the paper feed cassette 11 is separated and fed out one by one by the paper feed rollers 12a and 12b and the separation roller 13. It is. The recording medium P is transported by the transport roller portions 14 and 15 and further sent to the transport belt 17. On the other hand, the surfaces of the photosensitive drums 52Bk, 52Y, 52M, and 52C charged by a charging device (not shown) are respectively exposed by the exposure devices 21Bk, 21Y, 21M, and 21C, and electrostatic latent images corresponding to images to be formed. Is formed. The electrostatic latent image is developed by a developing device (not shown), and toner images as developer images are formed on the photosensitive drums 52Bk, 52Y, 52M, and 52C.

  Subsequently, the recording medium P is moved between the photosensitive drums 52Bk, 52Y, 52M, and 52C as image carriers and the transfer rollers 51Bk, 51Y, 51M, and 51C as image transfer means as the conveyance belt 17 travels. When passing, black, yellow, magenta, and cyan toner images are sequentially transferred to form a color toner image. The toner remaining on the photoreceptor drums 52Bk, 52Y, 52M, and 52C after the transfer is removed by a photoreceptor cleaning device (not shown). The recording medium P to which the toner image has been transferred is then conveyed to the fixing device 7 having the structure as described above. In the fixing device 7, the toner image is fixed by heating and pressing the fixing roller 71, and a predetermined color image is formed. The recording medium P on which the toner image has been fixed is then transported by the discharge roller 19 and then discharged onto the upper cover 23 by the discharge transport roller 20 and stacked at the discharge portion.

  Next, the operation of the fixing device 7 according to the embodiment of the present invention will be described. First, in the fixing device 7, the rotation of the fixing roller 71 is started with the start of printing in the image forming apparatus 1. The fixing roller gear 73 is driven by a fixing device driving gear disposed in the main body of the image forming apparatus 1 and is rotated in a direction in which the recording medium P is conveyed. The pressure roller 72 is driven to rotate as the fixing roller 71 rotates. The halogen heater 74 is supplied with a current from a power supply circuit (not shown) to generate heat, and heats the fixing roller 71 from the inside. Then, the surface temperature of the heated fixing roller 71 is detected by a thermistor (not shown) and input to a temperature control circuit of a control unit (not shown). Here, the temperature control circuit controls the supply of current from the power feeding circuit to the halogen heater 74 based on the detected surface temperature of the fixing roller 71, and maintains the surface temperature of the fixing roller 71 at the fixing temperature. In a state where the surface temperature of the fixing roller 71 is maintained at the fixing temperature, the toner image is heated and is pressed with a predetermined pressure by the pressure roller 72, whereby the toner image is fixed on the recording medium P.

  Next, the operation of each member at the end of the fixing roller 71 according to the present embodiment will be described by taking the retaining ring 77a as a representative, and each component is thermally expanded by being heated by a heat source in the fixing roller 71. Due to differences in thermal expansion coefficients and dimensional variations of materials, a gap may be formed between the heat insulating bush 76a and the cored bar 711 of the fixing roller 71, particularly at a cold start. In such a situation, although the retaining ring 77a and the fixing roller 71 rotate integrally, a slip occurs between the metal core 711 of the fixing roller 71 and the heat insulating bush 76a, so that the heat insulating bush 76a is formed. It does not rotate. The retaining ring 77a rotates while the heat insulating bush 76a is not rotating, and the fixing roller 71 receives the thrust force from the drive and moves toward the drive gear 73, so that the side surface of the retaining ring 77a is the surface of the heat insulating bush 76a. Rotates in contact with Even in such a state, in the form of the retaining ring 77a of the present embodiment, the fixing roller 71 is firmly fixed so that the engaging portions 771a and 772a of the retaining ring 77a reach the inner side of the core metal of the fixing roller 71, respectively. And the retaining ring 77a does not come off. Further, even when the fixing roller 71 receives the thrust force due to driving and moves to the opposite side of the driving gear 73, even when the retaining ring 77a is inclined due to play due to axial thermal expansion of the fixing roller 71, etc. The retaining portions 771a and 772a of the retaining ring 77a do not disengage outside in the roller axis direction, and the retaining ring 77a may be dropped when the retaining portions 771a and 772a interfere with the heater support member 80a. Prevented in advance. Further, the retaining ring 77a is a linear metal material having spring properties as described above, and elastically deforms. Therefore, even when a slight thrust force is received from the fixing roller 71 and the heat insulating bush 76a, the retaining ring 77a is elastically deformed. The thrust force can be absorbed, and the occurrence of situations such as plastic deformation and dropout of parts can be prevented.

  As described above, according to the fixing device 7 of the present embodiment, the locking portion 771a of the retaining ring 77a is bent and disposed so as to be positioned inside the cored bar through the coupling hole 712 of the fixing roller 71 cored bar. Even if slip occurs between the heat insulating bush 77a and the fixing roller 71 core metal, thermal expansion of the fixing roller 71, play in the thrust direction, excessive pressing, and the like have occurred. Even so, it is possible to prevent the retaining ring 77a from coming off. Further, in the present embodiment, the processing for the fixing roller can be performed by forming the pair of coupling holes 712, and the processing is facilitated, as compared with the conventional configuration in which the groove for the retaining ring is formed.

[Second Embodiment]
Next, an image forming apparatus and a fixing device according to a second embodiment of the present invention will be described. The image forming apparatus according to the present embodiment has a similar structure (see FIG. 1) except that the fixing device to be mounted is different from the image forming apparatus according to the first embodiment. In order to avoid the description, the description of the entire apparatus other than the fixing apparatus will be omitted, and different fixing apparatuses will be described. The fixing device according to the present embodiment will be described with reference to FIGS. FIG. 6 is a perspective view showing an end portion of the fixing roller in the second embodiment. FIG. 7 is a side view showing an end portion of the fixing roller in the second embodiment. FIG. 8 is an exploded perspective view showing an end portion of the fixing roller in the second embodiment. FIG. 9 is a view showing a heat insulating bush in the second embodiment. In the following description, the retaining ring 77a will be described, but the same applies to the retaining ring 77b attached to the opposite end of the fixing roller 71. The configuration on the retaining ring 77a side will be described, and the retaining ring 77b will be duplicated. The explanations made are omitted.

  In the first embodiment described above, if the retaining ring 77a rotates while the side surface of the retaining ring 77a is in contact with the surface of the heat insulating bush 81a and the heat insulating bush 81a does not rotate, the side surface of the retaining ring 77a is thermally insulated. Since there is a possibility that the surface of the bush 81a is rubbed and worn, in this embodiment, a recess 812a is formed along the outer shape of the retaining ring 77a on the side surface of the heat insulating bush 81a. That is, as shown in FIG. 7, the heat insulating bush 81a has a concave portion 812a formed on the side surface to accommodate the retaining ring 77a with a slight gap, and the concave portion 812a is close to the end of the retaining ring 77a. On the side, it has a straight portion 813a along the straight portion 773a of the retaining ring 77a, a corner portion 814a along a corner portion 774a that is bent at a substantially right angle, and the space between both corner portions 814 is extended substantially linearly. It has an edge portion 815a, and has a shape having a substantially semicircular edge portion 816a on the locking portion 772a side.

  The depth of the concave shape 812a formed on the side surface of the heat insulating bush 81a is the amount of play generated by the axial thermal expansion of the fixing roller 71, that is, the opposite side of the drive gear 73 due to the thrust force of the fixing roller 71 being driven. And a length deeper than the total length of the amount of inclination of the retaining ring 77a. In the slit 811a of the heat insulating bush 81a, the distance between the end surface and the retaining ring 77a is a mountain shape to form the locking part 772a, and the slit 811a and the retaining ring 77a are separated by the locking part 772a. It is configured as follows.

  The operations of the image forming apparatus and the fixing device of the present embodiment are the same as those of the first embodiment. Further, in the fixing device of the present embodiment, even if a slip occurs between the fixing roller 71 core and the heat insulating bush 81a, the straight portion 773a of the retaining ring 77a contacts the straight portion 813a of the concave portion 812a of the heat insulating bush 81a. By contact, the retaining ring 77a and the heat insulating bush 81a can rotate together. Even when the fixing roller 71 receives the thrust force from the drive and moves to the drive gear 73 side, even if the side surface of the retaining ring 77a is in contact with the surface of the heat insulating bush 81a, If it is the form of the heat insulation bush 81a, it is possible to prevent the surface abrasion of the heat insulation bush 81a by the side surface of the retaining ring 77a contacting and rotating.

  On the other hand, when the fixing roller 71 receives the thrust force from the drive and moves to the opposite side of the drive gear 73, play occurs due to the axial thermal expansion of the fixing roller 71, thereby causing the retaining ring 77a to tilt. Even if it exists, since the recessed part 812a depth of the heat insulation bush 81a is sufficiently deep, the retaining ring 77a does not protrude outside the recessed part 812a, and can rotate integrally.

  Similarly, the corner portion 774a of the retaining ring 77a interferes with the heater support member 80a, so that the retaining ring 77a is prevented from coming off. Furthermore, since the locking portion 772a is separated from the slit 811a of the heat insulating bush 81a, the vicinity of the locking portion 772a is prevented from being caught, and the retaining ring 77a is prevented from falling off.

  As described above, in the developing device according to the present embodiment, when the retaining ring 77a is mounted on the heat insulating bush 81a, the retaining ring 77a is engaged with the recess 812a of the heat insulating bush 81a and fixed. The rotation of the retaining ring 77a can be received by the shape of the recess 812a provided in the heat insulating bush 81a between the shaft core of the roller 71 and the ball bearing 75a. For this reason, the heat insulating bush 81a can be rotated without causing a rotation slip with respect to the shaft of the fixing roller 71 as the fixing roller 71 rotates, and there is no inconvenience that the retaining ring 77a rotates with respect to the heat insulating bush 81a. become. Therefore, it is possible to extend the life of the parts without wearing the heat insulating bush 81a. Furthermore, since the movement toward the drive gear depends on the component size variation, the nip load variation, etc., such abrasion of the surface of the heat insulation bush does not necessarily occur, but by preventing this wear, It is possible to extend the service life.

  In each embodiment, the printer is mainly described. However, the present invention can be applied to a facsimile machine, a copier, a multifunction machine, and the like. Further, although a color printer is exemplified as the printer, a monochrome printer may be used.

  In the above-described embodiment, the retaining rings 77a and 77b have been described as being formed by bending a linear metal member. However, other materials having a predetermined rigidity and capable of elastic deformation other than metal are used. It is also possible to make a thin plate of metal or other material into a predetermined shape by pressing or punching. In the above-described embodiment, an example in which a pair of retaining portions of the retaining ring is provided has been described. However, the number of retaining portions is not limited to one, and it is also possible to provide a single or three or more retaining portions.

  Furthermore, the present invention is not limited to each embodiment, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention. Moreover, the description of the member described in the whole specification is only an example, and is not limited to these descriptions.

1 is a schematic side view showing an image forming apparatus including a fixing device according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view of a main part when the fixing device according to the first embodiment of the present invention is viewed from the recording medium entering direction. FIG. 3 is a perspective view showing the vicinity of an end portion of a fixing roller in the first embodiment of the present invention. FIG. 3 is a side view showing the vicinity of the end portion of the fixing roller in the first embodiment of the present invention. FIG. 2 is an exploded perspective view showing the vicinity of an end portion of a fixing roller in the first embodiment of the present invention. FIG. 10 is a perspective view showing the vicinity of an end portion of a fixing roller in a second embodiment of the present invention. FIG. 6 is a side view showing the vicinity of an end portion of a fixing roller in a second embodiment of the present invention. FIG. 6 is an exploded perspective view showing the vicinity of an end portion of a fixing roller in a second embodiment of the present invention. It is the side view (A) seen from the axial direction which shows the heat insulation bush in the 2nd Embodiment of this invention, and the side view (B) seen from the direction perpendicular | vertical to an axial direction.

Explanation of symbols

1 Image forming device 7 Fixing device 52Bk, 52Y, 52M, 52C Photosensitive drum 71 Fixing roller 72 Pressure roller 73 Driving gear 74 Heater 75a, 75b Ball bearing 76a, 76b Heat insulation bush 77a, 77b Stop ring 78a, 78b Side plate 79a, 79b Pressure roller bearings 80a, 80b Heater support plate 712 Joint hole 751a Flange portion 761a Slit portion 762a Saddle portion 771a, 772a Locking portion 773a Straight portion 774a Corner portion 81a Thermal insulation bush 811a Slit 812a Recess portion 813a Straight portion 814a Corner portion 815a Edge Part 816a edge P recording medium

Claims (8)

A fixing device for fixing the developer onto the recording medium by heating the developer with respect to the recording medium carrying the developer,
A fixing member having a heat source and rotatable about a predetermined axis;
A substantially annular heat insulating member fitted on the end of the fixing member;
A retaining ring member that is substantially ring-shaped and has a locking portion that protrudes inward, and is used for retaining the heat insulating member;
The retaining ring member is fitted on the outer peripheral surface of the fixing member protruding outward in the axial direction from the heat insulating member, and the locking portion reaches the inner peripheral surface of the fixing member and is locked. Fixing device. The fixing device according to claim 1, wherein the heat insulating member is provided between the fixing member and a bearing member that rotatably supports both end portions of the shaft of the fixing member. The fixing device according to claim 1, wherein a concave portion having a shape along an outer shape of the retaining ring member is provided on a side surface of the heat insulating member adjacent to the retaining ring member. A rotation drive member for transmitting rotation drive to the fixing member is provided, and the retaining ring member disposed on the rotation drive member side is biased toward the rotation drive member side in the axial direction of the fixing member. The fixing device according to claim 1, wherein the fixing device is provided. 2. The retaining ring member according to claim 1, wherein the retaining ring member is formed by bending a metal rod-shaped member, and a pair of the engaging portions are provided and a notch is provided in one of the engaging portions. Fixing device. The fixing member projecting outward in the axial direction from the heat insulating member is formed with a locking hole for locking the locking portion so as to penetrate from the outer peripheral surface of the fixing member to the inner peripheral surface. The fixing device according to claim 1. An image carrier that forms a required electrostatic latent image on a recording medium;
A fixing member provided with a heat source for fixing a developer on the recording medium on which the electrostatic latent image is formed, and rotatable about a predetermined axis;
A substantially annular heat insulating member fitted on the end of the fixing member;
A retaining ring member that has a substantially annular shape and has a locking portion that protrudes inward, and is used to prevent the heat insulating member from coming off;
The retaining ring member is fitted on the outer peripheral surface of the fixing member that protrudes outward in the axial direction from the heat insulating member, and the locking portion is locked to the inner peripheral surface of the fixing member. Image forming apparatus. The heat insulating member is provided between the fixing member and a bearing member that rotatably supports both end portions of the shaft of the fixing member, and the fixing member is attached to the housing via the bearing member. The image forming apparatus according to claim 7, wherein the image forming apparatus is rotatably supported.