JP2010078863A - Endless belt, fixing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the buckling of the end of an endless belt even when the thickness of the end of the endless belt is not larger than that of the center part. <P>SOLUTION: A fixing device includes: a rotor which rotates and drives; the endless belt 62 of which surface is pressed against the rotor to form a pinching region for pinching a sheet between a space to the rotor, is rotated following the rotor, and conveys the sheet introduced into the pinching region with the rotor; and a heating means to heat an unfixed toner image on the sheet in the pinching region. The endless belt 62 has a layer 621 of which end is deformed in an uneven form along the circumferential direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an endless belt, a fixing device, and an image forming apparatus.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, a photosensitive member (photosensitive drum) formed in a drum shape is uniformly charged, and the photosensitive drum is controlled based on image information. An electrostatic latent image is formed on the photosensitive drum by exposure with the exposed light. The electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is primarily transferred from the photosensitive drum to the intermediate transfer belt, and then secondarily transferred from the intermediate transfer belt to the recording paper. The toner image is fixed on the recording paper by a fixing device.

  The fixing device includes, for example, a rotatable heat fixing roll having a heating source, an endless belt that is in pressure contact with the heat fixing roll and is driven by the heat fixing roll, and the endless belt disposed inside the endless belt. A pressing member that presses the belt against the fixing roll and forms a pressure contact area (nip region) between the endless belt and the heat fixing roll, and is disposed in a state of being fitted inside both ends of the endless belt. A belt guide member that rotatably guides the inner surface of the endless belt, and passing the sheet through the pressure contact region to fix the unfixed toner image on the sheet by heating and pressing. Are known.

  As this type of fixing device, a fixing device disclosed in Patent Document 1 is known. In the fixing device disclosed in Patent Document 1, edges that restrict movement of the endless belt 62 in a direction orthogonal to the rotation direction of the endless belt 62 are provided at both ends of the endless belt 62 that can rotate while contacting the fixing roll 61. A guide member 80 is provided, and the edge guide member 80 is configured such that a contact portion with the edge surface of the endless belt 62 can be elastically deformed into a bimetal shape.

  Thereby, it is possible to suppress the occurrence of damage such as cracks and breaks at the end of the belt member, and to enable a stable fixing operation over a long period of time.

  Patent Document 2 discloses a configuration in which a heat-resistant coating layer or a heat-resistant reinforcing tape is attached to the outer surface and / or inner surface of the peripheral edge of both ends of a heat-resistant seamless belt made of an organic polymer material. Thereby, generation | occurrence | production of the crack in use can be prevented and durability can be improved.

  Patent Document 3 discloses a fixing belt having at least a release layer and a metal layer, wherein the thickness of both end portions of the metal layer is larger than the thickness of the central portion. Has been.

  Further, in the fixing device disclosed in Patent Document 4, the endless belt has at least one rubber layer on the outer periphery of the metal or resin film, and the rubber layer covers the end of the endless belt. Prevents stress concentration due to edge shift.

Further, in Patent Document 5, in an endless belt member having at least an endless belt-like base layer, this base layer has a concave groove along the belt circumference at the position of the belt longitudinal end. An endless belt member is disclosed.
Japanese Patent Laying-Open No. 2006-065250 (FIG. 3) JP-A-5-345369 JP 2005-31474 A JP 2005-55469 A JP 2006-138944 A

  This invention makes it a subject to be able to suppress buckling of the edge part of an endless belt, even when not making thickness of the edge part of an endless belt thicker than a center part.

  The endless belt according to claim 1 of the present invention has a layer in which the end is deformed in an uneven shape along the circumferential direction.

  According to a second aspect of the present invention, there is provided a fixing device including: a rotating body that is rotationally driven; and a sandwiching region that sandwiches a sheet between the rotating body and a surface that is relatively pressed against the rotating body. The endless belt according to claim 1, wherein the sheet is rotated by being driven by a body, and the sheet introduced into the nipping area is conveyed by the rotating body, and an unfixed toner image on the sheet in the nipping area. Heating means for heating.

  According to a third aspect of the present invention, there is provided an image forming apparatus capable of holding an image formed on a surface thereof, a charging means for charging the surface of the image holding body, and the image holding charged by the charging means. A latent image forming means for forming a latent image on the surface of the body, a developing means for developing the latent image formed on the surface of the image holding body with the toner by the latent image forming means to form a toner image, and the developing A transfer unit that transfers the toner image formed by the unit to a recording medium; and a fixing device according to claim 2 that fixes the unfixed toner image transferred by the transfer unit to the recording medium as the sheet. I have.

  According to the configuration of the first aspect of the present invention, buckling of the end portion of the endless belt can be suppressed even when the end portion of the endless belt is not thicker than the center portion.

  According to the configuration of the second aspect of the present invention, even when the end portion of the endless belt is not thicker than the center portion, image formation can be performed over a long period of time.

  According to the configuration of the third aspect of the present invention, even when the thickness of the end portion of the endless belt is not made thicker than that of the central portion, it is possible to form an image over a long period of time.

Below, an example of an embodiment concerning the present invention is described based on a drawing.
In this embodiment, first, an endless belt will be described, then a fixing device including the endless belt will be described, and then an image forming apparatus including the fixing device will be described. Note that the endless belt according to the present embodiment can be applied to devices other than the fixing device, and may be used as an intermediate transfer belt or a conveyance belt, for example.

<Configuration of endless belt>
FIG. 1 is a schematic view showing one end portion in the axial direction (width direction) of the endless belt 62 according to the present embodiment. FIG. 2 is a schematic view showing one axial end portion of the endless belt 62 according to the modification. FIG. 3 is a schematic view in which an adhesive is filled in the recess of the endless belt 62 shown in FIG.

  As shown in FIGS. 1A and 1B, the endless belt 62 according to the present embodiment includes a layer 621 whose end is deformed in a concavo-convex shape along the circumferential direction. The endless belt 62 has a single layer structure, and is composed of a single layer 621. The layer 621 has a plurality of convex portions 62A formed along the circumferential direction.

  The endless belt 62 may have a multilayer structure, or may have a configuration in which a plurality of layers including the layer 621 are stacked. Further, the material, shape, size, etc. of the endless belt 62 are not particularly limited.

  Further, the configuration in which the reinforcing member for reinforcing the end portion of the endless belt 62 is provided on the endless belt 62, the configuration in which the film thickness of the end portion is made thicker than the film thickness of the central portion, etc. are not excluded. You may employ | adopt in addition to the structure which concerns on this embodiment.

(Configuration of the convex portion 62A according to the present embodiment)
Next, the configuration of the convex portion 62A according to the present embodiment will be described.

  The convex portion 62A according to the present embodiment is for suppressing deformation in the radial direction (the thickness direction of the endless belt 62) at the end of the endless belt 62. FIG. 1 (A) and FIG. 1 (B). As shown, a plurality of layers are formed along the circumferential direction of the layer 621. Specifically, the deformation in the radial direction refers to a deformation in which the end portion of the endless belt 62 spreads to the outer periphery or is narrowed to the inner periphery.

  As shown in FIG. 1A, the convex portion 62A protrudes to the outer peripheral side from the outer peripheral surface 622 of the layer 621. Further, as shown in FIG. 1B, the convex portion 62A is formed in a rib shape extending from both ends of the layer 621 along the axial direction. In FIG. 1B, only the convex portion 62A formed on one end side of the layer 621 is illustrated.

  On the inner peripheral surface 623 side that is the opposite surface to the outer peripheral surface 622, as shown in FIG. 1A, a concave portion that is recessed toward the outer peripheral side from the inner peripheral surface 623 of the layer 621 on the inner peripheral side of the convex portion 62A. 62B is formed.

  In addition, the structure which is formed in the inner peripheral surface 623 side of the layer 621 may be sufficient as the convex part 62A, as shown in FIG. In this configuration, as shown in FIG. 2A, the convex portion 62A protrudes to the inner peripheral side from the inner peripheral surface 623 of the layer 621. Further, the protrusions 62A are formed in a rib shape extending along the axial direction from both ends of the layer 621 (see FIG. 2B).

  As shown in FIG. 2A, on the outer peripheral surface 622 side opposite to the inner peripheral surface 623, a concave portion 62B is formed on the outer peripheral side of the convex portion 62A and recessed toward the inner peripheral side from the outer peripheral surface 622 of the layer 621. Is formed.

  Further, the convex portion 62A does not necessarily protrude from the outer edge or the inner edge of the endless belt 62. For example, an elastic body layer such as silicone rubber softer than the base layer provided with the convex portion 62A, or a fluororesin layer may be provided. It is also possible to laminate on the outermost peripheral surface or the innermost peripheral surface so as to fill in the recesses between the convex portions 62A so that the outer edge or inner edge of the endless belt 62 is free from irregularities.

  In addition, the “end portion of the layer 621” where the convex portion 62A is formed specifically refers to a range from the edges at both ends of the layer 621 to 20 mm in the axial direction.

  The convex portion 62 </ b> A only needs to be provided within the range of the end portion, and does not need to be formed from both ends of the layer 621. Note that, from the viewpoint of the strength of the end face of the endless belt 62, it is desirable that the convex portions 62 </ b> A be formed at the edge portions at both ends of the layer 621. By forming the protrusion 62A on the end surface of the layer 621, the area of the end surface of the layer 621 is increased.

  Further, the convex portion 62 </ b> A does not need to be provided over the entire circumference of the end portion of the layer 621, and may be configured to be provided intermittently along the circumferential direction of the end portion of the layer 621. Note that, from the viewpoint of the strength of the end portion of the endless belt 62, the convex portion 62 </ b> A is preferably provided continuously over the entire circumference of the end portion of the layer 621. Note that, in the configuration in which the convex portions 62A are provided intermittently, it is preferable that the convex portions 62A are formed in at least three places on the entire circumference of the layer 621.

  Further, in the present embodiment, the protrusions 62A are formed at both ends in the axial direction of the endless belt 62, but may be formed at one end in the axial direction.

  The size of the convex portion 62A is not particularly limited, and may be determined as appropriate depending on whether the convex portion 62A is provided on the inner peripheral surface 623 side or the outer peripheral surface 622 side of the belt body. Considering the case, the length of the endless belt 62 in the axial direction (L in FIGS. 1 and 2) is preferably 1 to 20 mm, more preferably 5 to 10 mm, and the height of the convex portion 62A (FIG. 1). And T) in FIG. 2 is preferably 0.1 to 2 mm, and more preferably 0.2 to 1 mm.

  Further, in order to suppress deformation of the convex portion 62A due to the convex portion 62A being stretched or the like, as shown in FIG. 3, the convex portion 62A is projected in a state where the convex portion 62A protrudes by filling the concave portion 62B with a bonding agent 624 or the like. The structure which hardens 62A may be sufficient. In addition, the structure which fills the recessed part between the convex part 62A of the outer peripheral side of the layer 621 and the convex part 62A with a bonding agent may be sufficient.

  As a deformation of the convex portion 62A, when incorporated in a fixing device described later, the convex portion 62A is deformed by stretching the convex portion 62A as the endless belt 62 slides with the belt running guide 63 and the like. It is possible to do.

  In the configuration shown in FIG. 2, the concave portion 62 </ b> B or the concave portion between the convex portion 62 </ b> A on the inner peripheral side of the endless belt 62 and the convex portion 62 </ b> A may be filled with a bonding agent.

  Further, in addition to the structure filled with the bonding agent, it is possible to further reinforce with an annular reinforcing member or tape.

  Various adhesives, various unvulcanized rubbers, various thermosetting resins, and various thermoplastic resins can be used as the bonding agent filling the recess 62B. Moreover, what exhibits adhesiveness by heating or pressurization needs to be heated and pressurized as necessary after filling the recess 62B. In addition, in a thermoplastic resin or the like, heat fusion (ultrasonic fusion) can be performed by applying ultrasonic vibration under pressure.

  Examples of the adhesive include a condensation curable or addition curable silicone adhesive mainly composed of organopolysiloxane, and a modified silicone adhesive mainly composed of polypropylene oxide (modified silicone) terminated with a methyldimethoxysilyl group. Agents, polyimide adhesives based on polyimide (PI) low molecular weight polymers belonging to aromatic heterocyclic polymers, and polybenzimidazoles (PBI) based on polybenzimidazole belonging to aromatic heterocyclic polymers Imidasol adhesive, epoxy resin based epoxy resin, urethane resin adhesive, reactive hot melt adhesive, polyurethane resin hot melt adhesive, polyamide resin hot melt adhesive, polyolefin resin hot melt adhesive Agents, chloroprene rubber adhesives, etc. From the viewpoint of heat resistance and flexibility, silicone and modified silicone or polyimide are preferred.

  In addition, various fillers can be added to the filler formed as the joint for the purpose of ensuring durability and conductivity. As the filler, a lubricious filler having a layered structure (eg, molybdenum disulfide, hexagonal boron nitride, mica, graphite, molybdenum disulfide, talc), conductive filler (eg, carbon black, graphite), heat resistance Filler comprising a heat-resistant resin (for example, a filler in which the heat-resistant resin is selected from imide resin, amide resin, and wholly aromatic polyester resin: polyimide, liquid crystal polymer, aramid), and others (glass powder) , Aluminum silicate, carbon fiber, bronze, potassium titanate, titanium oxide, metal powder, barium sulfate, metal oxide, carbide, nitride, silicate compound) and the like can be used.

  Moreover, as the thermoplastic resin as the bonding agent, various commercially available thermoplastic resins can be used. However, in consideration of heat resistance, various fluororesins, thermoplastic polyimide (PI), polyamideimide (PAI), poly Ether imide (PEI) is suitable.

<Material of endless belt 62>
As described above, the endless belt 62 may have a single-layer structure including only a base layer, or a multilayer structure having an arbitrary layer (for example, a coating layer containing a thermoplastic resin) on the base layer. Also good.

  The material used for the base layer of the endless belt 62 is not particularly limited, but can be appropriately selected from various known plastic materials and metal materials.

  Among plastic materials, what is generally called engineering plastic is suitable. For example, fluororesin, polyimide (PI), fluorinated polyimide, polyamideimide (PAI), polybenzimidazole (PBI), polyetheretherketone ( PEEK), polysulfone (PSU), polyethersulfone (PES), polyphenylene sulfide (PPS), polyetherimide (PEI), wholly aromatic polyester (liquid crystal polymer) and the like are preferable. Of these, thermosetting polyimide, thermoplastic polyimide, polyamideimide, polyetherimide, fluororesin and the like, which are excellent in mechanical strength, heat resistance, wear resistance, chemical resistance, and the like, are preferable.

  Moreover, there is no restriction | limiting in particular as a metal material, Various metals can be used suitably, For example, SUS, nickel, copper, aluminum etc. can be used conveniently. In addition, it is also possible to laminate | stack the said various resin and various metals.

  The thickness of the base layer is preferably in the range of 20 to 200 μm, and more preferably in the range of 40 to 100 μm.

  Further, the endless belt 62 according to the present embodiment can be formed by laminating a rubber material on the entire surface or a part of the base layer. The rubber material can be used as appropriate from various rubber materials, and examples thereof include urethane rubber, ethylene / propylene rubber (EPM), silicone rubber, fluoro rubber (FKM), and the like. Silicone rubber having excellent processability is preferred.

  The thickness of the rubber material is preferably in the range of 30 to 500 μm, and more preferably in the range of 100 to 300 μm.

  Furthermore, when the endless belt 62 according to the present embodiment is used as a fixing belt, it is preferable that a non-adhesive fluororesin is laminated on the outermost surface layer as a surface release layer. Examples of the fluororesin include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoroethylene-perfluoroethyl vinyl ether copolymer ( EFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyethylene-tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polychloroethylene trifluoride (PCTFE), Fluorine resins such as vinyl fluoride (PVF) are mentioned, and polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkyl vinyl are particularly preferred from the viewpoints of heat resistance and mechanical properties. Ether copolymer (PFA) of tetrafluoroethylene - perfluoro methyl vinyl ether copolymer (MFA), tetrafluoroethylene - perfluoro ethyl vinyl ether (EFA) copolymer or their modified products are preferably used.

  The thickness of the surface release layer is preferably in the range of 5 to 100 μm, and more preferably in the range of 10 to 50 μm.

  Various fillers can be appropriately added to each layer constituting the endless belt 62 according to the present embodiment in accordance with purposes such as conductivity, thermal conductivity, insulation, peelability, slidability, and reinforcement. It is.

  As the filler, a lubricating filler having a layered structure (eg, molybdenum disulfide, hexagonal boron nitride, mica, graphite, molybdenum disulfide disulfide, talc), conductive filler (eg, carbon black, graphite) A filler comprising a heat-resistant resin (for example, a filler in which the heat-resistant resin is selected from an imide resin, an amide resin, and a wholly aromatic polyester resin: for example, (fluorinated) polyimide, liquid crystal polymer, aramid ) And others (glass powder, aluminum silicate, carbon fiber, bronze, potassium titanate, titanium oxide, metal powder, barium sulfate, metal oxide, carbide, nitride, silicate compound) and the like can be used.

  The endless belt 62 according to the present embodiment is provided with a lubricant holding portion at one end portion or both end portions thereof, and a plurality of various heat resistant resins such as fluororesin, various metals, or various rubber materials. It is also possible to laminate over the entire area.

<Fixing device>
Next, a fixing device using the endless belt 62 according to the present embodiment will be described.
Various configurations are conceivable as the fixing device. Hereinafter, a fixing device including a fixing roll having a heating source and an endless belt pressed by a pressure pad will be described as a first embodiment, and a second embodiment will be described. A fixing device including a fixing belt and a pressure roll as an example of an endless belt pressed by a heat source will be described.

[First Embodiment of Fixing Device]
First, the fixing device 60 according to the first embodiment will be described. FIG. 4 is a schematic diagram illustrating a configuration of the fixing device 60 according to the first embodiment.

  As shown in FIG. 4, the fixing device 60 includes a fixing roll 61 as an example of a rotating body that is driven to rotate, an endless belt 62, and a pressure as an example of a pressure member that pressurizes the fixing roll 61 via the endless belt 62. And a pad 64. The pressure pad 64 only needs to be relatively pressed between the endless belt 62 and the fixing roll 61. Accordingly, the endless belt 62 side may be pressed against the fixing roll 61, and the fixing roll 61 side may be pressed against the fixing roll 61.

  The fixing roll 61 is configured by laminating a heat-resistant elastic body layer 612 and a release layer 613 around a metal core (cylindrical cored bar) 611. Inside the fixing roll 61, a halogen lamp 66 is disposed as an example of a heating unit that heats an unfixed toner image in the sandwiching area. The heating means is not limited to the halogen lamp, and other heat generating members that generate heat may be used.

  On the other hand, a temperature sensitive element 69 is disposed in contact with the surface of the fixing roll 61. The lighting of the halogen lamp 66 is controlled based on the temperature measurement value by the temperature sensing element 69, and the surface temperature of the fixing roll 61 is maintained at a predetermined set temperature (for example, 150 ° C.).

  The endless belt 62 is rotatably supported by a pressure pad 64 and a belt traveling guide 63 disposed inside, and a meandering prevention member 80 (see FIG. 5) disposed at both ends described later. In the sandwiching area N, it is disposed in pressure contact with the fixing roll 61.

  The pressure pad 64 is disposed inside the endless belt 62 in a state of being pressed against the fixing roll 61 via the endless belt 62, and forms a sandwiching region N with the fixing roll 61. In the pressure pad 64, a pre-nip member 64a for securing a wide clamping area N is arranged on the inlet side of the clamping area N, and a peeling clamping member 64b for distorting the fixing roll 61 is sandwiched. It is arranged on the exit side of the insertion area N.

  Further, in order to reduce the sliding resistance between the inner circumferential surface of the endless belt 62 and the pressure pad 64, a low friction sheet 68 is provided on the surface of the pre-nip member 64a and the peeling pin member 64b that contacts the endless belt 62. ing. The pressure pad 64 and the low friction sheet 68 are held by a metal holder 65.

  Further, a belt traveling guide 63 is attached to the holder 65 so that the endless belt 62 can smoothly rotate. That is, the belt traveling guide 63 is made of a material having a small static friction coefficient in order to rub against the inner peripheral surface of the endless belt 62. Further, the belt traveling guide 63 is formed of a material having low thermal conductivity so that it is difficult to remove heat from the endless belt 62.

  The fixing roll 61 is rotated in the direction of arrow C by a drive motor (not shown), and the endless belt 62 is rotated in the direction opposite to the rotation direction of the fixing roll 61 following this rotation. That is, the fixing roll 61 rotates in the clockwise direction in FIG. 4, whereas the endless belt 62 rotates in the counterclockwise direction.

  The sheet K having the unfixed toner image is guided by the fixing entrance guide 56 and conveyed to the sandwiching area N. When the paper K passes through the sandwiching area N, the toner image on the paper K is fixed by the pressure acting on the sandwiching area N and the heat supplied from the fixing roll 61.

  The sheet to be conveyed is not limited to paper, and may be a film-like member formed in a film shape such as a plastic film. Further, the sheet is not limited to a recording medium on which an image is recorded, and sheets for various uses are used. Further, the number of sheets may be one, or a plurality of sheets may be conveyed as in the case of producing a laminate sheet.

  In the fixing device 60 according to the first embodiment, the concave pre-pinching member 64a that substantially follows the outer peripheral surface of the fixing roll 61 ensures a wide pinching region N as compared with the configuration without the pre-pinching member 64a. The

  Further, in the fixing device 60 according to the first embodiment, the separation of the fixing roll 61 is disposed in the exit region of the sandwiching region N by projecting the outer peripheral surface of the fixing roll 61 and disposing the peeling sandwiching member 64b. It is comprised so that it may become large automatically.

  If the peeling and clamping member 64b is arranged in this way, the paper K after fixing passes through the locally formed distortion when passing through the peeling and clamping area, so that the paper K is fixed. Easy to peel off from the roll 61.

  Further, a peeling member 70 is disposed on the downstream side of the sandwiching area N of the fixing roll 61 as an auxiliary means for peeling. The peeling member 70 is held by a holder 72 in a state in which the peeling baffle 71 is close to the fixing roll 61 in a direction (counter direction) opposite to the rotation direction of the fixing roll 61.

  Hereinafter, members other than the endless belt 62 used in the fixing device 60 according to the first embodiment will be described in detail.

  The fixing roll 61 as a fixing member is not particularly limited in shape, structure, size, etc., and can be appropriately selected from those known per se according to the purpose. The fixing roll 61 includes a cylindrical core 611, an elastic layer 612 formed on the surface thereof, and a release layer 613 formed on the surface of the elastic layer.

  Such a fixing roll 61 can be manufactured by a known manufacturing method. Generally, a mold for forming an elastic layer 612 is disposed around a cylindrical core 611, and liquid rubber is molded into the mold. After being poured into the gap between the cylindrical core 611 and vulcanized and hardened, a resin sleeve such as PFA on the surface can be used.

  The material of the cylindrical core 611 is not particularly limited as long as it is a material having excellent mechanical strength and good heat conductivity. For example, aluminum (for example, A-5052 material), SUS, iron, copper, etc. Examples include metals, alloys, ceramics, and FRMs. The fixing device 60 according to the first embodiment is configured by a cylindrical body having an outer diameter of 25 mm, a thickness of 0.5 mm, and a length of 360 mm.

  The material of the elastic layer 612 can be appropriately selected from known materials, but any material can be used as long as it is an elastic body with high heat resistance. In particular, it is preferable to use an elastic body such as rubber or elastomer having a rubber hardness of about 15 to 45 ° (JIS-A), and examples thereof include silicone rubber and fluororubber.

  In the first embodiment, among these materials, silicone rubber is preferable in that the surface tension is small and the elasticity is excellent. Examples of the silicone rubber include RTV silicone rubber and HTV silicone rubber. Specifically, polydimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), methyl phenyl silicone rubber (PMQ), fluoro Examples include silicone rubber (FVMQ).

  The thickness of the elastic layer 612 is preferably 3 mm or less, and more preferably in the range of 0.5 to 1.5 mm. In the fixing device 60 of the first embodiment, the core is coated with an HTV silicone rubber having a rubber hardness of 35 ° (JIS-A) with a thickness of 600 μm.

  The material of the release layer 613 is not particularly limited as long as it exhibits an appropriate release property with respect to the toner image, and examples thereof include fluorine rubber, silicone rubber, fluorine resin, and silicone resin. Among these materials, a fluororesin is preferable.

  Examples of the fluororesin include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), and tetrafluoroethylene-perfluoroethyl vinyl ether copolymer (EFA). ), Polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyethylene-tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluorinated ethylene (PCTFE), fluorine Fluorine resin such as vinyl fluoride (PVF).

  Polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-perfluoromethyl vinyl ether copolymer (MFA), tetrafluoro, especially in terms of heat resistance and mechanical properties An ethylene-perfluoroethyl vinyl ether copolymer (EFA) is preferably used.

  The thickness of the release layer 613 is preferably 5 to 50 μm, more preferably 10 to 30 μm. If the thickness of the release layer 613 is less than 5 μm, the release layer is likely to wrinkle or wear due to the distortion of the fixing roll 61 in the vicinity of the end of the paper, whereas if it exceeds 50 μm, the release layer becomes hard. This is because there is an increased possibility of defects such as uneven gloss in the image, both of which are undesirable.

  The thickness of the release layer 613 is usually 10 to 100 μm, preferably 20 to 30 μm. There is no restriction | limiting in particular as a method of forming the said mold release layer 613 on the surface of the said core, For example, the method of coat | covering the tube formed by extrusion molding is mentioned. In the fixing device 60 of the first embodiment, 30 μm thick PFA is coated.

  As the heating source for heating the fixing roll 61, for example, the halogen lamp 66 is used as described above, and there is no particular limitation as long as it has a shape and structure that can be accommodated in the core. Can be selected as appropriate. The surface temperature of the fixing roll 61 heated by the halogen lamp 66 is measured by a temperature sensitive element provided in the fixing roll 61, and the temperature is controlled to be constant by the control means. There is no restriction | limiting in particular as a temperature sensing element, For example, a thermistor, a temperature sensor, etc. are mentioned.

  As described above, the pressure pad 64 arranged inside the endless belt 62 includes the pre-nip member 64a and the peeling pin member 64b, and the fixing roll 61 is loaded with a load of, for example, 32 kgf by a spring or an elastic body. It is supported by the holder 65 so as to press. The surface on the fixing roll 61 side is formed with a concave curved surface that substantially follows the outer peripheral surface of the fixing roll 61. Further, from the viewpoint of preventing deterioration due to heat at the time of fixing, each material is preferably composed of a material having heat resistance.

  The pressure pad 64 disposed inside the endless belt 62 presses the fixing roll 61 via the endless belt 62, and the sheet K holds an unfixed toner image between the endless belt 62 and the fixing roll 61. There is no particular limitation on the shape and material as long as it has a function capable of forming the sandwiching region N through which the toner can pass. Further, in addition to the pressure pad 64, the fixing roller 61 is rotated while being pressed. It is also possible to arrange pressure rollers or the like side by side.

  For the pre-nip member 64a, a heat-resistant elastomer such as silicone rubber or fluororubber, or an elastic body such as a leaf spring can be used, and among these materials, silicone rubber is preferable because of its excellent elasticity. Examples of the silicone rubber include RTV silicone rubber and HTV silicone rubber. Specifically, polydimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), methyl phenyl silicone rubber (PMQ), fluoro Examples include silicone rubber (FVMQ). From the viewpoint of hardness, silicone rubber having a JIS-A hardness of 10 to 40 ° is preferably used. There is no restriction | limiting in particular about the shape of a elastic body, a structure, a magnitude | size, etc., According to the objective, it can select suitably. In the fixing device 60 of the first embodiment, silicone rubber having a width of 10 mm, a thickness of 5 mm, and a length of 320 mm is used.

  The peeling sandwiching member 64b is made of a heat-resistant resin such as PPS (polyphenylene sulfide), polyimide, polyester, polyamide, or a metal such as iron, aluminum, or SUS. As the shape of the peeling sandwiching member, the outer surface shape in the sandwiching region N is formed as a convex curved surface having a constant radius of curvature. In the fixing device 60 of the present embodiment, the endless belt 62 is wrapped around the fixing roll 61 by a pressure pad at an angle of about 40 ° to form a sandwiched region N having a width of about 8 mm.

  The low friction sheet 68 is provided to reduce the sliding resistance (friction resistance) between the inner peripheral surface of the endless belt 62 and the pressure pad 64, and a material having a small friction coefficient and excellent wear resistance and heat resistance is suitable. ing.

  As a material of the low friction sheet 68, various materials such as metal, ceramics, and resin can be adopted. Specifically, the heat-resistant resin is fluororesin, polyethersulfone (PES), poly In addition to butylene terephthalate (PBT), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), natural materials such as 6-nylon or 6,6-nylon, and carbon and glass fibers added to these Materials can be used.

  Among these, a fluororesin sheet having a contact surface with the endless belt 62 that has a small sliding resistance with the inner surface of the endless belt 62 and a fine uneven shape on the surface on which the lubricant is held is preferable.

  Specifically, a sintered PTFE resin sheet, a glass fiber sheet impregnated with Teflon (registered trademark), a laminated sheet in which a glass fiber made of a fluororesin skive film sheet is heat-fused sand, or a fluororesin sheet. What provided streak unevenness etc. can be used.

  The low friction sheet 68 may be configured separately from the pre-nip member 64a and the peeling pin member 64b, or may be configured integrally with the pre-pinching member 64a and the peel pin member 64b. Good.

  Further, the holder 65 is provided with a lubricant application member 67 along the longitudinal direction of the fixing device 60. The lubricant application member 67 is disposed so as to contact the inner peripheral surface of the endless belt 62 and supplies an appropriate amount of lubricant. As a result, the lubricant is supplied to the sliding portion between the endless belt 62 and the low friction sheet 68, and the sliding resistance between the endless belt 62 and the pressure pad via the low friction sheet 68 is further reduced. Smooth rotation is aimed at. Further, it has an effect of suppressing wear on the inner peripheral surface of the endless belt 62 and the surface of the low friction sheet 68.

  Silicone oil is preferred as the lubricant, and dimethyl silicone oil, dimethyl silicone oil with addition of organometallic salt, dimethyl silicone oil with addition of hindered amine, dimethyl silicone oil with addition of organometallic salt and hindered amine, methylphenyl silicone oil, amino-modified silicone oil are preferred as the silicone oil. Organic metal salt-added amino-modified silicone oil, hindered amine-added amino-modified silicone oil, carboxy-modified silicone oil, silanol-modified silicone oil, sulfonic acid-modified silicone oil, etc. can also be used. preferable.

  In addition, when superior performance due to heat resistance is required, it is also preferable to use methylphenyl silicone oil or fluorine oil (perfluoropolyether oil, modified perfluoropolyether oil) or the like. In addition, in order to improve heat resistance, it is also possible to add a trace amount antioxidant in silicone oil. In addition, synthetic lubricating oil grease in which a solid substance and a liquid are mixed, for example, silicone grease, fluorine grease, or the like, or a combination thereof can also be used. In the fixing device 60 of the first embodiment, an amino-modified silicone oil (KF96: manufactured by Shin-Etsu Chemical Co., Ltd.) having a viscosity of 300 cs is used.

  Further, as described above, the belt traveling guide 63 is made of a material having a low coefficient of friction and a low thermal conductivity so that heat is not easily taken from the endless belt 62 because it slides on the inner peripheral surface of the endless belt 62. A heat resistant resin such as PFA or PPS is used.

  Further, the fixing device 60 according to the present embodiment includes a meandering prevention member 80 that contacts the end surface of the endless belt 62 and prevents the meandering. 5A and 5B are schematic views illustrating the configuration of the meandering prevention member 80 provided in the fixing device 60 according to the present embodiment.

  The meandering prevention member 80 includes a support portion 801, a flange portion 802, and an insertion portion 803. As shown in FIG. 5A, the meandering prevention member 80 has its insertion portion 803 inserted from both end portions of the endless belt 62, and the flange portion 802 abuts against its end surface when the endless belt 62 meanders. They are arranged with a certain distance apart.

  At this time, the endless belt 62 is configured to rotate along the outer peripheral surface of the belt traveling guide 63. As shown in FIG. 4, the endless belt 62 is configured to be pressed against the fixing roll 61 by the pressure pad 64, and thus is rotated by the frictional force from the fixing roll 61 due to the pressing force.

  As a result, when the frictional force from the fixing roll 61 becomes non-uniform in the width direction due to variations in component dimensions and the influence of the paper K passing through the sandwiching area N, the endless belt 62 is moved in the axial direction. A moving force works and a so-called belt walk is generated that is offset to either end.

  Therefore, in the fixing device 60 according to the present embodiment, the meandering prevention member 80 as shown in FIG. 5 is provided, and the endless belt 62 is meandered by the flange portion 802 provided so that the end of the endless belt 62 abuts. Suppress.

  The meandering prevention member 80 is formed of a heat-resistant resin such as PPS, PET, PBT, or LCP, and further added with a filler for lowering durability and a friction coefficient.

[Second Embodiment of Fixing Device]
Next, the fixing device 90 according to the second embodiment will be described. FIG. 6 is a schematic diagram illustrating a configuration of the fixing device 90 according to the second embodiment.
Note that the same components as those of the fixing device according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted here.

  As shown in FIG. 6, the fixing device 90 according to the second embodiment includes a fixing belt 92 as an endless belt and a pressure roll 91 as an example of a rotating body that rotates. The fixing belt 92 is configured in the same manner as the endless belt 62 described above.

  The fixing belt 92 is disposed on the toner image holding surface side of the sheet K, and a ceramic heater 82 which is a resistance heating element as an example of a heating unit is disposed inside the fixing belt 92. Is configured to supply heat to the sandwiching region N.

  The ceramic heater 82 has a substantially flat surface on the pressure roll 91 side. And it is arrange | positioned in the state pressurized to the pressurization roll 91 via the fixing belt 92, and the clamping area | region N is formed. Therefore, the ceramic heater 82 also functions as a pressure member. The paper K that has passed through the sandwiching area N is peeled off from the fixing belt 92 by the change in the curvature of the fixing belt 92 in the exit area (peeling sandwiching portion) of the sandwiching area N.

  Further, a low friction sheet 68 is disposed between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82 in order to reduce sliding resistance between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82. The low friction sheet 68 may be configured separately from the ceramic heater 82 or may be configured integrally with the ceramic heater 82.

  On the other hand, the pressure roll 91 is disposed so as to face the fixing belt 92, and is configured to rotate in the direction of arrow D by a driving motor (not shown), and the fixing belt 92 is rotated following the rotation. The pressure roll 91 includes a core (cylindrical cored bar) 911, a heat-resistant elastic body layer 912 coated on the outer peripheral surface of the core 911, and a release layer 913 made of a heat-resistant resin coating or a heat-resistant rubber coating. As necessary, each layer is made semiconductive by adding carbon black or the like as a countermeasure against toner offset.

  Further, in the fixing device 90 of the second embodiment, the fixing belt 92 is an endless belt whose original shape is formed in a cylindrical shape, and is coated on the base layer and the surface or both surfaces of the base layer on the pressure roll 91 side. And a release layer.

  In addition, as an auxiliary means for peeling, a peeling member 70 can be disposed on the downstream side of the sandwiching area N of the fixing belt 92. The peeling member 70 is held by the holder 72 in a state where the peeling baffle 71 is close to the fixing belt 92 in a direction (counter direction) opposite to the rotation direction of the fixing belt 92.

  In addition, edge guides (not shown) are provided at both ends of the holder 95. The edge guides are arranged such that the inner surfaces of both edge guides arranged so as to face each other at both end portions of the holder 95 have an interval substantially matching the width of the fixing belt 92. When the fixing belt 92 rotates, movement of the fixing belt 92 in the width direction (belt walk) is restricted by the end portions of the fixing belt 92 coming into contact with the inner surfaces of both edge guides. Thus, the fixing belt 92 is set so that the deviation is regulated by the edge guide.

  Then, the sheet K having the unfixed toner image is guided to the sandwiching area N of the fixing device 90 by the fixing entrance guide. When the paper K passes through the sandwiching area N, the toner image on the paper K is fixed by the pressure acting on the sandwiching area N and the heat supplied from the ceramic heater on the fixing belt 92 side.

  In addition to the ceramic heater 82, the heating source may be a halogen lamp provided inside the endless belt 62, or may utilize electromagnetic induction heat generated by an electromagnetic induction coil provided inside or outside the endless belt 62. It doesn't matter.

  Further, in addition to a flat pressure member, a pressure roller that rotates while pressing against the fixing roll 61 can be arranged in parallel within the endless belt 62.

<Image forming apparatus>
Next, an image forming apparatus according to the present embodiment including the fixing device according to the first embodiment will be described. FIG. 7 is a schematic configuration diagram showing the configuration of the image forming apparatus according to the present embodiment.

  An image forming apparatus 100 shown in FIG. 7 is an intermediate transfer type image forming apparatus generally called a tandem type, and includes a plurality of image forming units 1Y, 1M, 1C on which toner images of respective color components are formed by electrophotography. 1K and the respective color component toner images formed by the image forming units 1Y, 1M, 1C, and 1K are sequentially transferred (primary transfer) to the intermediate transfer belt 15, and transferred onto the intermediate transfer belt 15. A secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner image onto a sheet K as a recording medium, and a fixing device 60 that fixes the secondary transferred image on the sheet K. Further, the image forming apparatus 100 includes a control unit 40 that controls the operation of each device (each unit).

  The fixing device 60 is the fixing device of the first embodiment described above, and the fixing device includes the endless belt 62 of the embodiment described above. The image forming apparatus 100 may be configured to include the fixing device 90 according to the second embodiment described above.

  Each of the image forming units 1Y, 1M, 1C, and 1K of the image forming apparatus 100 includes a photosensitive drum 11 that rotates in the arrow A direction as an example of an image holding body that can hold an image formed on the surface.

  A charger 12 for charging the photosensitive drum 11 is provided around the photosensitive drum 11 as an example of a charging unit for charging the surface of the image holding member. The charging unit 12 is charged on the surface of the image holding member charged by the charging unit. As an example of a latent image forming means for forming a latent image, a laser exposure device 13 (an exposure beam is indicated by a symbol Bm in the drawing) for writing an electrostatic latent image on the photosensitive drum 11 is provided.

  Further, around the photosensitive drum 11, each color component toner is an example of a developing unit that forms a toner image by developing the latent image formed on the surface of the image holding member with the toner by the latent image forming unit. A developing device 14 is provided that visualizes the electrostatic latent image on the photosensitive drum 11 with toner, and each toner image formed on the photosensitive drum 11 is intermediately transferred by the primary transfer unit 10. A primary transfer roll 16 for transferring to the belt 15 is provided.

  Further, a drum cleaner 17 for removing residual toner on the photosensitive drum 11 is provided around the photosensitive drum 11, and a charger 12, a laser exposure device 13, a developing device 14, a primary transfer roll 16, and a drum cleaner are provided. Seventeen electrophotographic devices are sequentially arranged along the rotation direction of the photosensitive drum 11. These image forming units 1Y, 1M, 1C, and 1K are arranged substantially linearly in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15. Has been.

The intermediate transfer belt 15 as an intermediate transfer member is formed of a film-like endless belt containing a resin such as polyimide or polyamide as a base layer and containing an appropriate amount of an antistatic agent such as carbon black. And the volume resistivity is formed so that it may become 10 < ⁶ > -10 < ¹⁴ > (omega | ohm) cm, The thickness is comprised by about 0.1 mm, for example.

  The intermediate transfer belt 15 is circulated and driven (rotated) at a predetermined speed in the direction B shown in FIG. 7 by various rolls. As these various rolls, a drive roll 31 that is driven by a motor (not shown) having excellent constant speed and rotates the intermediate transfer belt 15, and an intermediate transfer that extends substantially linearly along the arrangement direction of the photosensitive drums 11. A support roll 32 that supports the belt 15, a tension roll 33 that functions as a correction roll that applies a constant tension to the intermediate transfer belt 15 and prevents meandering of the intermediate transfer belt 15, and a backup roll provided in the secondary transfer unit 20. 25. A cleaning backup roll 34 is provided in a cleaning unit that scrapes off residual toner on the intermediate transfer belt 15.

The primary transfer unit 10 includes a primary transfer roll 16 that is disposed to face the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The primary transfer roll 16 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. Sponge layer is formed of blend rubber of NBR, SBR and EPDM mixed with a conducting agent such as carbon black, the volume resistivity is spongy cylindrical roll of 107.5-10 ^8.5 [Omega] cm.

  The primary transfer roll 16 is placed in pressure contact with the photosensitive drum 11 with the intermediate transfer belt 15 in between, and the primary transfer roll 16 has a voltage (with negative polarity; the same applies hereinafter) having a polarity opposite to that of the toner. (Primary transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 so as to form superimposed toner images on the intermediate transfer belt 15.

  The secondary transfer unit 20 is a secondary roller disposed on the toner image holding surface side of the intermediate transfer belt 15 as an example of a transfer unit that transfers the toner image formed by the backup roll 25 and the developing unit to a recording medium. And a transfer roll 22.

The backup roll 25 is composed of a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and EPDM rubber inside. And it is formed so that the surface resistivity may be 10 ⁷ to 10 ¹⁰ Ω / □, and the hardness is set to, for example, 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd., the same shall apply hereinafter). The backup roll 25 is disposed on the back side of the intermediate transfer belt 15 to constitute a counter electrode of the secondary transfer roll 22, and a metal power supply roll 26 to which a secondary transfer bias is stably applied is disposed in contact with the backup roll 25. ing.

On the other hand, the secondary transfer roll 22 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ^7.5 to 10 ^8.5 Ωcm.

  The secondary transfer roll 22 is disposed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween. Further, the secondary transfer roll 22 is grounded, and a secondary transfer bias is formed between the secondary transfer roll 22 and the backup roll 25. The toner image is secondarily transferred onto the paper K conveyed to the transfer unit 20.

  Further, on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, an intermediate transfer belt that removes residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15. A cleaner 35 is provided so as to be able to contact and separate.

  On the other hand, on the upstream side of the yellow image forming unit 1Y, a reference sensor (home position sensor) 42 that generates a reference signal serving as a reference for taking image forming timings in the image forming units 1Y, 1M, 1C, and 1K. It is arranged. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K. The reference sensor 42 recognizes a predetermined mark provided on the back side of the intermediate transfer belt 15 and generates a reference signal. Each image forming unit is instructed by an instruction from the control unit 40 based on the recognition of the reference signal. 1Y, 1M, 1C, and 1K are configured to start image formation.

  Further, in the image forming apparatus according to the present embodiment, as a transport unit that transports the paper K, a paper tray 50 that stores the paper K, and a pick-up roll that picks up and transports the paper K accumulated in the paper tray 50 at a predetermined timing. 51, a transfer roll 52 that transports the paper K fed by the pickup roll 51, a transport guide 53 that feeds the paper K transported by the transport roll 52 to the secondary transfer unit 20, and a secondary transfer roll 22. A conveyance belt 55 that conveys the sheet K conveyed to the fixing device 60 and a fixing entrance guide 56 that guides the sheet K to the fixing device 60 are provided.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. In the image forming apparatus as shown in FIG. 7, image data output from an image reading device (IIT) not shown or a personal computer (PC) not shown is subjected to predetermined image processing by an image processing device (IPS) not shown. After being applied, the image forming operation is executed by the image forming units 1Y, 1M, 1C, and 1K.

  The image processing apparatus performs predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and other various image editing on the input reflectance data. Is given. The image data that has been subjected to image processing is converted into color material gradation data of four colors Y, M, C, and K, and is output to the laser exposure unit 13.

  The laser exposure device 13 irradiates the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K with, for example, an exposure beam Bm emitted from a semiconductor laser in accordance with the input color material gradation data. Yes. In each of the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, after the surface is charged by the charger 12, the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent images are developed as toner images of respective colors Y, M, C, and K by the respective image forming units 1Y, 1M, 1C, and 1K.

  The toner images formed on the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 in the primary transfer unit 10 where the photosensitive drums 11 and the intermediate transfer belt 15 contact each other. Transcribed. More specifically, in the primary transfer portion 10, a voltage (primary transfer bias) having a polarity opposite to the toner charging polarity (minus polarity) is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16, and the toner image. Are sequentially superimposed on the surface of the intermediate transfer belt 15 to perform primary transfer.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is conveyed to the secondary transfer unit 20. When the toner image is conveyed to the secondary transfer unit 20, the pickup unit 51 rotates in accordance with the timing at which the toner image is conveyed to the secondary transfer unit 20 in the conveyance unit. Is supplied. The paper K supplied by the pick-up roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 through the transport guide 53. Before reaching the secondary transfer unit 20, the sheet K is temporarily stopped, and the registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner image is held. And the position of the toner image are aligned.

  In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 15. At this time, the sheet K conveyed at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (negative polarity) is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the backup roll 25. Is done. The unfixed toner image held on the intermediate transfer belt 15 is collectively electrostatically transferred onto the paper K in the secondary transfer unit 20 pressed by the secondary transfer roll 22 and the backup roll 25. The

  Thereafter, the sheet K on which the toner image has been electrostatically transferred is conveyed as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and is conveyed downstream of the secondary transfer roll 22 in the sheet conveyance direction. It is conveyed to the belt 55. The transport belt 55 transports the paper K to the fixing device 60 in accordance with the optimal transport speed in the fixing device 60. The unfixed toner image on the paper K conveyed to the fixing device 60 is fixed on the paper K by receiving a fixing process with heat and pressure by the fixing device 60. Then, the sheet K on which the fixed image is formed is conveyed to a paper discharge mounting portion (not shown) provided in the discharge portion of the image forming apparatus.

  On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 rotates, and is cleaned by the cleaning backup roll 34 and the intermediate transfer belt cleaner 35. It is removed from the intermediate transfer belt 15.

  Although the embodiments of the present invention have been described above, the present invention is not construed as being limited to the above-described embodiments, and various modifications, changes, and improvements can be made, and a range that satisfies the requirements of the present invention. Needless to say, this is feasible.

  Hereinafter, the evaluation results when the endless belt according to the example and the endless belt according to the comparative example are manufactured and attached to the fixing device and the image forming apparatus will be specifically described. However, the present invention is not limited to the following examples.

Example 1
First, an N-methylpyrrolidone solution of a polyimide precursor having a viscosity of 120 Pa · s (trade name) is applied to the surface of an aluminum cylindrical mold having an outer diameter of 30 mm, which is blasted on the surface and then applied and baked with a silicone release agent. : U varnish, manufactured by Ube Industries Co., Ltd.) by a flow coating (spiral winding application) method, spin-dried at 110 ° C. for 40 minutes, and further, a fluororesin (PFA) dispersion (trade name: 710CL, After coating by spray coating (Mitsui / DuPont Fluoro Chemical Co., Ltd.), the coating film was baked at 380 ° C. for 30 minutes.

  Next, the formed film is removed from the core surface, and both ends are cut, and a coating layer having a film thickness of 25 μm containing PFA as a thermoplastic resin is formed on the outer periphery of a polyimide resin (heat resistant resin) having a film thickness of 70 μm. An endless belt having a formed inner diameter of 30 mm and a total length of 352 mm and before forming the convex portion was obtained.

  Next, the endless belt is inserted inside a metal mold having an inner diameter of 30.2 mm having eight rib-shaped concave portions at both ends on the inner peripheral surface, and eight rib-shaped protrusions are also formed on the outer peripheral surface. The end of the endless belt was plastically deformed by press-fitting a metal mandrel provided with a shaped portion from both sides in a state heated to 250 ° C. Further, after cooling, the endless belt was pulled out from the mold.

  Thereby, an endless belt 62 having a convex portion 62A as shown in FIG. 1 was obtained. In addition, the length (L) of the axial direction of the formed convex part 62A is 5 mm, and height (T) is 500 micrometers.

(Example 2)
First, in the same manner as in Example 1, a convex portion having an inner diameter of 30 mm and a total length of 352 mm in which a coating layer having a thickness of 25 μm containing PFA as a thermoplastic resin is formed on the outer periphery of a polyimide resin (heat resistant resin) having a thickness of 70 μm. An endless belt before formation was produced.

  Next, the endless belt is inserted into a metal mold having an outer diameter of 30 mm having 30 corrugated concave and convex portions at both ends on the outer peripheral surface, and 30 corrugated concave and convex portions are also formed on the inner peripheral surface. The end of the endless belt was plastically deformed by press-fitting from both sides in a state where the metal outer mold provided with was heated to 250 ° C. Further, after cooling, the endless belt was pulled out from the mold.

  Thereby, the endless belt which has 30 convex parts 62A in both ends toward the inner peripheral surface side as shown in FIG. 2 was obtained. In addition, the length (L) of the axial direction of the formed convex part 62A is 5 mm, and height (T) is 300 micrometers.

(Example 3)
The concave portion 62B on the back side of the convex portion 62A of the endless belt 62 produced in Example 1 is filled with an adhesive (see FIG. 3).

(Comparative Example 1)
First, in Example 1, a film thickness of 25 μm containing PFA as a thermoplastic resin on the outer periphery of a polyimide resin (heat resistant resin) having a film thickness of 70 μm, where both ends are cut before the end part is reinforced. A belt having an inner diameter of 30 mm and a total length of 352 mm on which the coating layer was formed was used as an endless belt of Comparative Example 1.

<Evaluation>
In this evaluation, the endless belts produced in Examples 1 to 3 and the endless belt of Comparative Example 1 are attached as the endless belt 62 to the fixing device 60 according to the first embodiment shown in FIG. Attaching to the forming apparatus 100 was performed.

  An image is formed by the image forming apparatus 100, and the fixing device 60 is formed for every 50,000 sheets, 100,000 sheets, 150,000 sheets, 200,000 sheets, 250,000 sheets, and 300,000 sheets. Was taken out of the image forming apparatus 100, and the end portion (end face) of the endless belt was checked for damage.

  The fixing roll 61 in the fixing device 60 is a pipe made of a carbon steel pipe having a thickness of 0.5 mm and an outer diameter of 25 mm, and a silicone rubber (LSR manufactured by Shin-Etsu Chemical Co., Ltd.) having a thickness of 0.6 mm and an outermost surface layer. Injection molding was carried out so that a 30 μm thick PFA tube (950 HP-Plus manufactured by Mitsui DuPont Fluorochemical Co., Ltd. was extruded and the inner surface was treated with excimer laser) was integrally coated.

  In the evaluation, the pressure (nip pressure) in the contact area between the fixing roll 61 and the endless belt 62 was set to 1.3 times as usual as an acceleration condition for confirming the durability of the end of the endless belt.

  As a result of the evaluation, in the endless belts 62 of Examples 1 to 3, it was possible to form an image without any problem up to 300,000 sheets.

  On the other hand, in the endless belt 62 of the comparative example 1, a small crack is seen at the end (end surface) of the belt when 150,000 sheets are finished, and the end of the belt is broken at the end of 290,000 sheets. As a result, image formation has become impossible.

FIG. 1 is a schematic view showing one end portion in the axial direction (width direction) of the endless belt according to the present embodiment. FIG. 2 is a schematic diagram illustrating one axial end portion of an endless belt according to a modification. FIG. 3 is a schematic view in which an adhesive is filled in the recess of the endless belt shown in FIG. 1. FIG. 4 is a schematic diagram illustrating the configuration of the fixing device according to the first embodiment. FIG. 5 is a schematic diagram illustrating a configuration of a meandering prevention member provided in the fixing device according to the first embodiment. FIG. 6 is a schematic diagram illustrating the configuration of the fixing device according to the second embodiment. FIG. 7 is a schematic configuration diagram showing the configuration of the image forming apparatus according to the present embodiment.

Explanation of symbols

11 Photosensitive drum (image carrier)
12 Charger (charging means)
13 Laser exposure device (latent image forming means)
14 Developer (Developing means)
22 Secondary transfer roll (transfer means)
60 Fixing Device 61 Fixing Roll (Rotating Body)
62 Endless belt 66 Halogen lamp (heating means)
82 Ceramic heater (heating means)
90 Fixing Device 91 Pressure Roll (Rotating Body)
92 Fixing belt (endless belt)
100 Image forming apparatus K Paper (sheet)
N sandwiching area

Claims (3)

  An endless belt having a layer whose ends are deformed in an uneven shape along the circumferential direction. A rotating body that rotates,
A surface is relatively pressed against the rotating body to form a sandwiching area in which a sheet is sandwiched between the rotating body, the sheet that is rotated by being driven by the rotating body, and is introduced into the sandwiching area. The endless belt according to claim 1, wherein the endless belt is conveyed by the rotating body;
Heating means for heating an unfixed toner image on the sheet in the sandwich region;
A fixing device provided with An image carrier capable of holding an image formed on the surface;
Charging means for charging the surface of the image carrier;
Latent image forming means for forming a latent image on the surface of the image carrier charged by the charging means;
Developing means for developing a latent image formed on the surface of the image carrier by the latent image forming means with toner to form a toner image;
Transfer means for transferring the toner image formed by the developing means to a recording medium;
The fixing device according to claim 2, wherein an unfixed toner image transferred by the transfer unit is fixed to the recording medium as the sheet;
An image forming apparatus.

Images