JP2013214039A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device, even when a sliding sheet is heated and extended in the fixing device, suppressing formation of wrinkle in the sliding sheet compared with a case having no this configuration, and an image forming apparatus.SOLUTION: The front/rear ends of a sliding sheet 68 along a rotating and traveling direction (an arrow direction in Figure 2) of a fixing belt 61 as a film tube body are clamped and fixed by a pair of sheet plates 90a and 90b and a pair of sheet plates 90c and 90d respectively. Side faces facing a holder 65 as a retaining member include frames 92 respectively, and each frame 92, the sheet plate 90a, and the sheet plate 90c are connected by a spring member 80. A tensile force of the spring member 80 is set to a range less than or equal to an elastic limit point under a fixing temperature (for example 200°C) according to the material of the sliding sheet 68 used and such a range that no wrinkle is formed by extension of the sliding sheet 68 under the fixing temperature.

Description

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

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or printer, a process for fixing an unfixed toner image held on a recording member such as paper on a recording member to form a permanent image is called a fixing step. I'm calling. Conventionally, methods such as pressure fixing, oven fixing, and solvent fixing are used as the fixing step, but heat is effectively transmitted, the toner image is fixed more firmly, and is relatively safe. From the viewpoint, the thermal pressure fixing method is most commonly used. In this thermal pressure fixing method, a recording member on which an unfixed toner image is held is passed through a nip constituted by two heated rolls or belts, and when the nip passes, the recording member is heated by the rolls or belts to be in a molten state. In this method, the toner image is fixed on the recording member by pressing the unfixed toner image that has been pressed against the recording member with a nip pressure.

  In recent years, the electromagnetic induction heating and fixing system, which has been introduced, requires a coil and a high-frequency power source in addition to the conventional heating and fixing member and pressure member corresponding to two heated rolls or belts. The coil is installed inside the heat fixing member or at a position close to the external heat fixing member, and is electrically connected to a high frequency power source. As a heat fixing member, induction heating can be performed in either a roll shape or a belt shape as long as a metal heating layer is provided. In any case, an induction electromotive force is generated in the metal heating layer of the heat-fixing member by flowing a high-frequency current through a coil arranged at a position close to the heat-fixing member, and an eddy current flows to heat the heat-fixing member. Has been.

  Further, in the belt-type heat fixing member, a pressing member is disposed inside the resin film tubular body in order to form a nip between the pressure member composed of a rotatable rotating member and the resin film tubular body (for example, a belt). Has been. Further, a sliding sheet is disposed in order to reduce the frictional resistance between the inside of the resin film tubular body and the pressing member (for example, Patent Document 1).

  Further, in order to prevent the displacement of the sliding sheet relative to the pressing member at the time of re-pressing after the pressure member made of the rotating member and the resin film tubular body are separated, the sliding sheet travels. The front and rear ends of the sliding sheet are screwed to the pressing member along the direction and positioned, or the rear end of the sliding sheet is screwed to the pressing member and the front end of the sliding sheet is used as a pressing member by using a spring member The structure which positions is proposed (for example, patent document 2).

JP 2007-79034 A JP 2009-204924 A

  The present invention provides a fixing device and an image forming apparatus in which the occurrence of wrinkles in the sliding sheet is suppressed even when the sliding sheet is heated and stretched in the fixing device, as compared with the case without this configuration. With the goal.

  As a result of intensive studies to solve the above problems, the present invention has been reached as follows.

  (1) The unfixed toner by sandwiching a rotatable rotating member and a recording medium which is disposed in pressure contact with the rotating member and holds an unfixed toner image in a nip formed between the rotating member. A rotatable film tubular body for fixing an image on the recording medium, a sliding sheet interposed between the film tubular body and the pressing member, and a holding member for holding the sliding sheet and the pressing member; And a spring member that holds the front and rear ends of the sliding sheet along the direction of rotation of the film tubular body to the holding member.

  (2) The fixing device according to (1), further including a second spring member that pulls the left and right end portions of the sliding sheet to the holding member along a rotation axis direction of the film tubular body. is there.

  (3) A latent image forming unit for forming a latent image on the latent image holding member, a developing unit for developing the latent image using a developer for developing an electrostatic image, and an intermediate transfer member for developing the developed toner image. An image forming apparatus comprising: a transfer unit that transfers the toner image on the transfer medium; and a fixing unit that fixes the toner image on the transfer medium. An image forming apparatus comprising the fixing device according to (2).

  According to invention of Claim 1, compared with the case where it does not have a spring member which pulls the front-and-rear end part of the said sliding sheet along the rotation direction of a film tubular body on the said holding member, a sliding sheet is Even if heated and stretched in the fixing device, generation of wrinkles in the sliding sheet is suppressed.

  According to the second aspect of the present invention, the spring member that pulls the front and rear end portions of the sliding sheet along the rotational traveling direction of the film tubular body to the holding member, and the rotational axis direction of the film tubular body. Even if the sliding sheet is heated and stretched in the fixing device as compared with the case where it does not have the second spring member that pulls the left and right end portions of the sliding sheet to the holding member, The generation of wrinkles is further suppressed.

  According to the third aspect of the present invention, even when the sliding sheet is heated and stretched in the fixing device, the generation of wrinkles in the sliding sheet is suppressed as compared with the case where the fixing device having this configuration is not provided. An image forming apparatus having a fixing device is obtained.

FIG. 2 is a schematic configuration diagram illustrating an example of a configuration of a fixing device in the present embodiment. It is a schematic sectional drawing explaining an example of the structure by which the both ends which the sliding sheet | seat in this Embodiment opposes are hold | maintained by a holding member via a spring member. It is a schematic perspective view explaining an example of the structure by which the front-and-rear end part of the sliding sheet along the rotation direction of the film tubular body in this Embodiment is pulled by the holding member via a spring member. It is a schematic perspective view explaining an example of the structure by which the edge part of the sliding sheet | seat in this Embodiment is pulled by the holding member via a spring member from 4 directions. 1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to the present invention.

  The fixing device and the image forming apparatus in the embodiment of the present invention will be described below.

[Fixing device]
First, the fixing device in the present embodiment will be described below with reference to FIG. Note that a fixing device that employs an electromagnetic induction heating method will be described as an example of the fixing device in the present embodiment.

  As shown in FIG. 1, a fixing device 60 according to the present embodiment is disposed in pressure contact with a pressure roll 62 that is a rotatable rotating member and a pressure roll 62 that is a rotating member. The unfixed toner image is fixed on the recording medium P by sandwiching the recording medium P holding the unfixed toner image in a pressure part N (hereinafter also referred to as “nip part N”) formed on It has a fixing belt 61 that is a film tubular body, and a sliding sheet 68 that is interposed between the fixing belt 61 that is a film tubular body and a pressing pad 64 that is a pressing member. The sliding sheet 68 will be described later.

  Further, the configuration of the fixing device 60 will be described with reference to FIG. The fixing device 60 is disposed so as to face the fixing belt 61 that is a film tubular body, a magnetic field generation unit 85 as an example of a heating member that generates heat from the magnetic field generated by an alternating current, and the fixing belt 61. A pressure pad 62 that is a pressing member that is pressed from a pressure roll 62 that is a rotating member via a pressure roll 62 that is an example of a member and a fixing belt 61 is provided.

  The fixing belt 61, which is a film tubular body, is rotatably supported by a pressing pad 64, a belt guide member 63, and edge guide members (not shown) disposed at both ends of the fixing belt 61. Then, it is brought into pressure contact with the pressure roll 62 at the pressure part (nip part) N and is rotated in the direction of arrow E following the pressure roll 62.

  The film tubular body described above may be made of resin or metal. In addition, when a film tubular body is used as a fixing belt, a single-layer resin film or a single-layer metal film is used, but the resin layer and the metal layer may each be a multilayer, You may combine a resin layer and a metal layer, such as providing a resin-made elastic layer and a release layer on a film as a base material. In particular, when the lowermost layer of the film tubular body that is in contact with the sliding sheet in the present embodiment is a metal layer, the lowermost layer of the film tubular body is a metal layer because wear is less likely to occur than when it is a resin layer. Preferably there is.

  The belt guide member 63 is attached to a holder 65 disposed inside the fixing belt 61. The belt guide member 63 is formed by a plurality of ribs (not shown) directed in the rotation direction of the fixing belt 61 to reduce the contact area with the inner peripheral surface of the fixing belt 61. Further, the belt guide member 63 is formed of a heat resistant resin such as PFA (perfluoroalkyl vinyl ether copolymer) or PPS (polyphenylene sulfide) having a low friction coefficient and low thermal conductivity. Thus, the sliding resistance between the belt guide member 63 and the inner peripheral surface of the fixing belt 61 is reduced, and the heat divergence is reduced.

  The pressure pad 64 is pressed from the pressure roll 62 via the fixing belt 61 to form the pressure portion N. The pressing pad 64 that is a pressing member is supported by a holder 65 that is a holding member so as to press the pressure roll 62 with a load of, for example, 35 kgf by a spring or an elastic body. The pressing pad 64 is made of an elastic body such as silicone rubber or fluorine rubber. The pressing pad 64 has a concave portion and a convex portion on the pressure roll 62 side. As a result, when the fixing belt 61 moves away from the surface of the pressing pad 64 on the pressure roll 62 side, a sudden change in curvature occurs, and the recording medium P after fixing is easily peeled off from the fixing belt 61.

  The peeling assisting member 70 disposed in the vicinity of the downstream side of the pressure unit N is held by the baffle holder 72 so that the peeling baffle 71 faces in the direction (counter direction) opposite to the rotation direction of the fixing belt 61. Further, a sliding sheet 68 is disposed between the pressing pad 64 and the fixing belt 61 to reduce sliding resistance between the inner peripheral surface of the fixing belt 61 and the pressing pad 64. In the present embodiment, the sliding sheet 68 is configured separately from the pressing pad 64, and at least both ends are fixed to the holder 65.

  A lubricant application member 67 is disposed in the holder 65 serving as a holding member over the longitudinal direction of the fixing device 60. The lubricant applying member 67 contacts the inner peripheral surface of the fixing belt 61 and supplies the lubricant to the sliding portion between the fixing belt 61 and the sliding sheet 68. Examples of the lubricant include liquid oils such as silicone oil and fluorine oil; grease in which a solid substance and a liquid are mixed, and a combination thereof.

  The pressure roll 62 includes, for example, a solid iron core (columnar core) 621 having a diameter of 16 mm, a rubber layer 622 such as a silicone sponge having a thickness of 12 mm, which covers the outer peripheral surface of the core 621, and the like, for example And a surface layer 623 with a heat-resistant resin coating such as PFA having a thickness of 30 μm or a heat-resistant rubber coating. In addition, as a manufacturing method of the pressure roll 62, for example, a fluororesin tube in which an adhesion primer is applied to the inner peripheral surface of a PFA tube (becomes the surface layer 623) and a solid shaft (becomes the core 621) are used. After setting in a molding die and injecting a liquid foamed silicone rubber between the fluororesin tube and the solid shaft, the silicone rubber is vulcanized and foamed by heat treatment (150 ° C., 2 hours) to form a rubber layer 622. The method of forming is mentioned.

  The pressure roll 62 is disposed so as to face the fixing belt 61, rotates in the direction of arrow D at a process speed of, for example, 140 mm / sec, and drives the fixing belt 61. Further, the pressure belt 62 is held by the pressure roll 62 and the pressure pad 64 to form the pressure portion N, and the recording medium P holding the unfixed toner image is passed through the pressure portion N. Then, heat and pressure are applied to fix the unfixed toner image on the recording medium P.

  The magnetic field generation unit 85 has a cross-section with a curved shape that follows the shape of the fixing belt 61, and is installed with an outer peripheral surface of the fixing belt 61 with a gap of about 0.5 mm to 2 mm, for example. The magnetic field generation unit 85 includes an excitation coil 851 that generates a magnetic field, a coil support member 852 that holds the excitation coil 851, and an excitation circuit 853 that supplies current to the excitation coil 851.

The exciting coil 851 is formed, for example, by winding a litz wire, which is a bundle of about 16 to 20 copper wires having a diameter of 0.5 mm that are insulated from each other, in a closed ring shape such as an oval shape, an elliptical shape, or a rectangular shape. Use things. By applying an alternating current having a predetermined frequency to the exciting coil 851 by the exciting circuit 853, an alternating magnetic field H is generated around the exciting coil 851. When the alternating magnetic field H crosses the metal layer of the fixing belt 61, an eddy current I is generated so as to generate a magnetic field that hinders the change of the alternating magnetic field H by electromagnetic induction. The frequency of the alternating current applied to the exciting coil 851 is set, for example, from 10 kHz to 50 kHz. When the eddy current I flows through the metal layer of the fixing belt 61, Joule heat is generated by electric power W (W = I ² R) proportional to the resistance value R of the metal layer, and the fixing belt 61 is heated.

  The coil support member 852 is made of a nonmagnetic material having heat resistance. Examples of such a non-magnetic material include heat resistant resins such as heat resistant glass, polycarbonate, polyethersulfone, and PPS, or heat resistant resins obtained by mixing glass fibers with these.

  In the present embodiment, the electromagnetic induction heating type fixing device 60 including the magnetic field generation unit 85 has been described as an example of a heating member that heats the fixing belt 61. However, as the heating member, a radiation lamp heating element, a resistance heating element, and the like. The body can also be adopted.

  Examples of the radiant lamp heating element include a halogen lamp. Examples of the resistance heating element include iron-chromium-aluminum, nickel-chromium, platinum, molybdenum, tantalum, tungsten, silicon carbide, molybdenum-silicide, and carbon.

  In the fixing device 60, the fixing belt 61 is driven and rotated by the rotation of the pressure roll 62 in the direction of arrow D, and is exposed to the magnetic field generated by the excitation coil 851. At this time, an eddy current is generated in the metal layer in the fixing belt 61, and the outer peripheral surface of the fixing belt 61 is heated to a temperature at which fixing can be performed. The fixing belt 61 heated in this way moves to the pressure part N with the pressure roll 62. The recording medium P having the unfixed toner image provided on the surface thereof is carried into the fixing device 60 via the fixing inlet guide 56 by the conveying means. When the recording medium P passes through the pressure part N of the fixing belt 61 and the pressure roll 62, the unfixed toner image is heated by the fixing belt 61 and fixed on the surface of the recording medium P. Thereafter, the recording medium P on which the image is formed is conveyed by the conveying unit and is discharged from the fixing device 60. Also, the fixing belt 61 whose surface temperature on the outer peripheral surface has been lowered after the fixing process in the pressurizing unit N rotates in the direction of the excitation coil 851 and is heated again in preparation for the next fixing process.

[Sliding sheet]
In the sliding sheet 68 in the present embodiment, unevenness is provided on the contact surface with the inner peripheral surface of the fixing belt 61 to reduce the sliding resistance. Examples of the material of the sliding sheet 68 include glass fiber, stainless steel (mainly abbreviated as “SUS” in JIS) mesh, carbon cloth, fluororesin-impregnated glass fiber sheet, and crosslinked PTFE sheet. In the case of using fibers and carbon cloth, it is possible to use a woven fabric from the viewpoint that the surface irregularities are equally spaced, and the thickness of the fibers of the warp and weft yarns can be arbitrarily set to control the surface irregularities. It is preferable to configure.

  Specific examples of the lubricant that can be applied as the lubricant supplied from the lubricant application member 67 to the uneven surface of the sliding sheet 68 include the above-mentioned grease, dimethyl silicone oil, dimethyl silicone oil with an organic metal salt, and hindered amine added dimethyl. Examples include silicone oil, organometallic salt and hindered amine-added dimethyl silicone oil, methylphenyl silicone oil, organometallic salt-added amino-modified silicone oil, hindered amine-added amino-modified silicone oil, and the like.

[Holding configuration of tensioned sliding sheet to holding member]
In FIG. 2, the front and rear end portions of the sliding sheet 68 along the rotational travel direction (the arrow direction in FIG. 2) of the film tubular body in the present embodiment are pulled by the holding member 65 via the spring member 80. An example of the configuration is shown.

  As shown in FIG. 2, the front and rear end portions of the sliding sheet 68 along the rotational travel direction (arrow direction in FIG. 2) of the fixing belt 61 which is a film tubular body are respectively a pair of sheet metals 90a and 90b and a pair of sheet metals. It is clamped between 90c and 90d. On the other hand, a frame 92 is provided on each side surface of the holder 65 that is a holding member, and each frame 92 and the sheet metal 90 a and the sheet metal 90 c are connected by a spring member 80. In FIG. 2, each frame 92 and the sheet metal 90 a and the sheet metal 90 c are connected by the spring member 80. However, the present invention is not limited to this, and the spring member 80 includes both the frame 92 and the pair of sheet metals 90 a and 90 b or It suffices to be connected to either one and / or both of the frame 92 and the pair of sheet metals 90c and 90d.

  The tension of the spring member 80 is below the elastic limit point at the fixing temperature (for example, 200 ° C.) according to the material of the sliding sheet 68 to be used, and the range in which wrinkles due to the elongation of the sliding sheet 68 at the fixing temperature does not occur. Set by. Here, the “elastic limit point” refers to a limit point when plastic deformation that does not return from the property of elasticity when stress exceeds a certain limit, and is also referred to as a yield point. The spring member 80 is fixed to both or one of the pair of sheet metals and is fixed to the frame 92. Alternatively, the spring member 80 is fixed to the frame 92 and fixed to both or one of the pair of sheet metals. It may be locked.

  2 and 3, the tensile stress of the spring member 80 at the front and rear ends of the sliding sheet 68 is more preferably the same. Since the sliding sheet 68 generally extends at the fixing temperature, the positional deviation of the sliding sheet 68 is suppressed by pulling the front and rear end portions of the sliding sheet 68 with the same stress, and as a result, the fixing temperature. It is thought that the generation of wrinkles on the sliding sheet is suppressed.

  Further, as shown in FIG. 3, the spring member 80 may be composed of a plurality of spring groups. The front and rear end portions of the sliding sheet 68 are pulled and held by a plurality of spring groups, so that the sliding sheet 68 can be rotated in the rotational running direction of the fixing belt 61 as compared with the case where the sliding belt 68 is pulled by one spring in one direction. It is considered that the tensile stress applied to the front and rear end portions becomes substantially uniform, and as a result, the occurrence of wrinkling of the sliding sheet 68 during fixing is further reduced.

  In another embodiment of the present invention, as shown in FIG. 4, the front and rear end portions of the sliding sheet 68 along the rotational travel direction (the arrow direction in FIG. 4) of the fixing belt 61 that is a film tubular body are respectively The pair of sheet metals 90a and 90b and the pair of sheet metals 90c and 90d are clamped, and the left and right end portions of the sliding sheet 68 along the rotation axis direction of the fixing belt 61 are respectively paired with the sheet metals 90e and 90f and the sheet metal. It is clamped between a pair of sheet metals (not shown in FIG. 4) provided on the surface opposite to the surface on which 90e and 90f are formed. On the other hand, a frame 92 is provided on each of the four side surfaces of the holder 65, which is a holding member, and each frame 92 provided on the opposite surface is connected to the sheet metal 90a and the sheet metal 90c by a spring member 80. Each frame 92 provided on the opposing surface, the sheet metal 90e, and the sheet metal (not shown in FIG. 4) on the opposite side of the sheet metal 90e are connected by spring members 82, respectively. In FIG. 4, each frame 92 and the sheet metal 90 a, the sheet metals 90 c and 90 e, and the sheet metal on the opposite side of the sheet metal 90 e are connected by the spring members 80 and 82. Each frame 92 has a pair of sheet metals 90a and 90b, a pair of sheet metals 90c and 90d, a pair of sheet metals 90e and 90f, and a pair of sheet metals provided on the surface opposite to the surface on which the sheet metals 90e and 90f are formed (see FIG. 4) (not shown in FIG. 4) and any one of them may be connected by the spring member 80 and the spring member 82, respectively.

  Similarly to the above, the tension of the spring members 80 and 82 is equal to or less than the elastic limit point at the fixing temperature (for example, 200 ° C.) according to the material of the sliding sheet 68 to be used, and depends on the elongation of the sliding sheet 68 at the fixing temperature. It is set within the range where wrinkles do not occur. Here, the “elastic limit point” refers to a limit point when plastic deformation that does not return from the property of elasticity when stress exceeds a certain limit, and is also referred to as a yield point. The spring members 80 and 82 may be fixed to the respective frames 92 and may be locked to the respective pair of sheet metals, or may be fixed to both or either of the respective pair of sheet metals and hooked to the respective frames 92. It may be stopped.

  In FIG. 4, the tensile stresses of the spring members 80 and 82 at the front and rear end portions and the left and right end portions of the sliding sheet 68 are more preferably the same. Since the sliding sheet 68 extends as a whole at the fixing temperature, the front and rear end portions and the left and right end portions of the sliding sheet 68 are pulled with the same stress, so that the positional deviation of the sliding sheet 68 is suppressed. As a result, it is considered that the occurrence of wrinkling of the sliding sheet at the fixing temperature is further suppressed.

  Furthermore, as shown in FIG. 4, the spring members 80 and 82 may be composed of a plurality of spring groups. By fixing the front and rear end portions and the left and right end portions of the sliding sheet 68 with a plurality of spring groups, the fixing belt 61 can be rotated in the direction of rotation as compared with a case where the sliding sheet 68 is pulled with one spring in one direction. The tensile stress applied to not only the front and rear end portions of the sliding sheet 68 along but also the left and right end portions of the sliding sheet 68 with respect to the rotational traveling direction becomes substantially equal. As a result, the wrinkles of the sliding sheet 68 at the fixing temperature are generated. Is considered to be further reduced.

  In the embodiment shown in FIGS. 2 to 4 described above, the end portions of the sliding sheet 68 are pulled using the spring members 80 and 82, but the present invention is not limited to this. Instead, a heat shrink member (not shown) may be used. The heat-shrinkable member slides within a range that is below the elastic limit point at the fixing temperature (for example, 200 ° C.) according to the material of the sliding sheet 68 that is used and that does not cause wrinkles due to the elongation of the sliding sheet 68 at the fixing temperature. A heat shrinkage rate is set in advance so as to pull the moving sheet 68. Here, as described above, the “elastic limit point” refers to a limit point when plastic deformation that does not return to its original state when the stress exceeds a certain limit, and is also referred to as a yield point.

  Examples of the heat-shrinkable member include a heat-shrinkable tube, and the heat-shrinkable tube is a shape-memory plastic tube that shrinks to a pre-stored shape when heated. Examples thereof include a vinyl chloride heat-shrinkable tube, a polyolefin heat-shrinkable tube, and a heat-shrinkable tube made of polyvinylidene fluoride resin. Further, as the heat-shrinkable member, a heat-shrinkable tube PST manufactured by Heraman Tighton may be used.

  In the embodiment shown in FIGS. 2 and 3, the front and rear end portions of the sliding sheet 68 along the rotational traveling direction of the fixing belt 61 are a pair of sheet metals 90a and 90b and a pair of sheet metals 90c and 90d. The pair of sheet metals 90a and 90b and the pair of sheet metals 90c and 90d are connected to the frame 92 provided on the side surface of the holder 65 by the spring member 80, respectively. A pair of sheet metals 90a and 90b and a pair of sheet metals 90c and 90d that clamp the front and rear end portions of the sheet 68 are directly provided separately from the holder 65 without a spring member (not shown). And the tension member is controlled by a control unit (not shown), and is below the elastic limit point at the fixing temperature (for example, 200 ° C.) according to the material of the sliding sheet 68 to be used. And, to the extent that wrinkles by elongation of the sliding sheet 68 in fixing temperature does not occur, it may be raised to pull the sliding sheet 68. In this case, it is also possible to adjust the degree of pulling according to the location by using a plurality of connected locations. For example, when the upstream side of the sliding sheet 68 is extended due to deterioration over time, it is possible to make the tensile strength on the upstream side stronger than other parts.

  Similarly, in the embodiment shown in FIG. 4, the pair of sheet metals 90 a and 90 b and the pair of sheet metals 90 c and 90 d holding the front and rear end portions of the sliding sheet 68 along the rotational traveling direction of the fixing belt 61. , And a surface opposite to the surface on which the pair of sheet metals 90e and 90f and the sheet metals 90e and 90f are formed to clamp the left and right ends of the sliding sheet 68 along the rotational traveling direction of the fixing belt 61. A pair of sheet metal (not shown in FIG. 4) is directly connected to a tension member (not shown) provided separately from the holder 65 without a spring member, and the tension member is not shown. Wrinkles due to the elongation of the sliding sheet 68 at the fixing temperature and below the elastic limit point at the fixing temperature (for example, 200 ° C.) according to the material of the sliding sheet 68 to be used. It may be raised to pull the sliding sheet 68 with no range.

[Image forming apparatus]
FIG. 5 shows a schematic configuration of an image forming apparatus to which the sliding sheet and the fixing device of the present embodiment are applied. Here, an intermediate transfer type image forming apparatus generally called a tandem type will be described as an example.

  An image forming apparatus 100 shown in FIG. 5 includes a plurality of image forming units 1Y, 1M, 1C, and 1K that form toner images of respective color components by an electrophotographic method as an example of an image forming unit including a latent image forming unit and a developing unit. Is provided. Next, the image forming apparatus 100 sequentially transfers (primary transfer) each color component toner image formed by each of the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt (image holding member) 15 as an example of a transfer unit. And a secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner image transferred onto the intermediate transfer belt 15 onto a sheet that is a recording medium P (recording material). Furthermore, the image forming apparatus 100 includes the above-described fixing device 60 that fixes the secondary transferred image on the recording medium P as an example of a fixing unit. Further, the image forming apparatus 100 includes a control unit 40 that controls the operation of each device (each unit).

  As shown in FIG. 5, each of the image forming units 1Y, 1M, 1C, and 1K includes a photosensitive drum 11 that rotates in the direction of arrow A, a charger 12 that charges the photosensitive drum 11, and a photosensitive drum 11. It has a laser exposure device 13 for writing an electrostatic latent image, and a developing device 14 that accommodates each color component toner and visualizes the electrostatic latent image on the photosensitive drum 11 with the toner. Further, a primary transfer roll 16 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, a drum cleaner 17 that removes residual toner on the photosensitive drum 11, and Have 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. ing.

  The intermediate transfer belt 15 is circulated and driven in the direction of arrow B shown in FIG. As various rolls, a drive roll 31 that drives the intermediate transfer belt 15, a support roll 32 that supports the intermediate transfer belt 15, a tension roll 33 that applies a constant tension to the intermediate transfer belt 15 to prevent meandering, and a secondary transfer. A backup roll 25 provided in the section 20 and a cleaning backup roll 34 provided in a cleaning section for scraping the residual toner on the intermediate transfer belt 15 are provided.

  The primary transfer unit 10 includes a primary transfer roll 16 that faces the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The secondary transfer unit 20 is disposed on the back side of the intermediate transfer belt 15 as a secondary transfer roll (transfer member) 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 and a counter electrode of the secondary transfer roll 22. And a power supply roll 26 that applies a secondary transfer bias to the backup roll 25.

  An intermediate transfer belt cleaner 35 for removing residual toner and paper dust on the intermediate transfer belt 15 is provided on the downstream side of the secondary transfer unit 20. A reference sensor (home position sensor) 42 that generates a reference signal for taking an image forming timing in each of the image forming units 1Y, 1M, 1C, and 1K is disposed upstream of the yellow image forming unit 1Y. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K.

  The recording medium transport system includes a recording medium container 50, a pickup roll 51 that takes out and transports the recording medium P in the recording medium container 50, a transport roll 52 that transports the recording medium P, and a recording medium P. A conveyance chute 53 to be sent to the next transfer unit 20, a conveyance belt 55 for conveying the recording medium P secondarily transferred by the secondary transfer roll 22 to the fixing device 60, and a fixing inlet for guiding the recording medium P to the fixing device 60. And a guide 56.

  A basic image forming process of the image forming apparatus 100 will be described. In the image forming apparatus 100 as shown in FIG. 5, after image processing is performed on image data output from an image reading apparatus (not shown) or the like, the image data is converted into four colors Y, M, C, and K. It is converted into material gradation data and output to the laser exposure unit 13. For example, each of the photosensitive drums that rotates the exposure beam Bm emitted from the semiconductor laser in the direction of arrow A of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. 11 is irradiated. After the surface of each photoconductive drum 11 is charged by the charger 12, the surface is scanned and exposed by the laser exposure device 13 to form an electrostatic latent image. The formed electrostatic latent image is developed as a toner image of each color of Y, M, C, and K by each of the image forming units 1Y, 1M, 1C, and 1K.

  Next, the toner image formed on the photosensitive drum 11 is sequentially superimposed on the surface of the intermediate transfer belt 15 in the primary transfer unit 10 to perform primary transfer. The intermediate transfer belt 15 moves in the direction of arrow B and conveys the toner image to the secondary transfer unit 20. The recording medium conveyance system supplies the recording medium P from the recording medium container 50 in accordance with the timing at which the toner image is conveyed to the secondary transfer unit 20. In the secondary transfer unit 20, the unfixed toner image held on the intermediate transfer belt 15 is electrostatically transferred onto the recording medium P sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. Thereafter, the recording medium P on which the toner image has been electrostatically transferred is conveyed to the fixing device 60 by the conveying belt 55, and the fixing device 60 processes the unfixed toner image on the recording medium P with heat and pressure and puts it on the recording medium P. To settle. The recording medium P on which the fixed image has been formed is conveyed to a paper discharge placement unit provided in the discharge unit of the image forming apparatus.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to a following example.

[Example 1]:
As a holder 65 (FIGS. 2 and 3) as a holding member, a rectangular parallelepiped molded body made of a metal material (specifically SUS304) is used, and as a sliding sheet 68 (FIGS. 2 and 3), a crosslinked PTFE sheet is used. (Hitachi Cable: Exelon XF-1B, thickness: 0.3 mm) A single-layer sliding sheet was used. The spring member 80 (FIGS. 2 and 3) is a spring having a force not less than a tensile force capable of suppressing wrinkles due to heating of the sliding sheet at a fixing temperature (for example, 200 ° C.) and not more than an elastic limit point of the sliding sheet. 2 and 3, as shown in FIGS. 2 and 3, the front and rear end portions of the sliding sheet 68 along the rotational traveling direction (the arrow direction in FIGS. 2 and 3) of the fixing belt 61 (FIG. 1), that is, sliding Both end portions of the sheet 68 in the process direction were pulled to the holder 65.

<Evaluation of wrinkle generation on sliding sheet>
The holder 65 on which the sliding sheet 68 is pulled is attached to a belt fixing device of a high-speed copying machine (manufactured by Fuji Xerox Co., Ltd .: Color 1000 Press), the temperature is raised to the fixing temperature (200 ° C.), and the process speed is increased to 180 ppm. It was visually evaluated after fixing 500,000 sheets. The results are shown in Table 1.

The criteria for visual judgment of wrinkle occurrence are as follows.
A: Wrinkles were not observed.
○: There are wrinkles that do not affect the image quality.
Δ: Wrinkles occur and image quality is disturbed.
X: Many wrinkles are generated, and the image quality is greatly disturbed.

[Example 2]:
In place of the configuration shown in FIG. 3, the configuration shown in FIG. 4 is adopted, and the spring member 82 (FIG. 4) has a tensile force that can suppress wrinkles due to heating of the sliding sheet at a fixing temperature (for example, 200 ° C.) or more. A spring having a force below the elastic limit of the sliding sheet was used. Then, as shown in FIG. 4, the front and rear ends of the sliding sheet 68 along the rotational traveling direction (arrow direction in FIG. 4) of the fixing belt 61 (FIG. 1) and the sliding sheet along the rotational traveling direction. The left and right end portions of 68 were produced in the same manner as in Example 1 except that the holder 65 was pulled. The holder on which the sliding sheet was pulled in all directions was attached to a belt fixing device of a high speed copying machine (Fuji Xerox Co., Ltd .: Color 1000 Press), and wrinkle generation evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]:
Instead of the spring member 80 shown in FIG. 2, a pair of sheet metals 90 a and 90 b that clamp the front and rear ends of the sliding sheet along the rotational travel direction (arrow direction in FIG. 2) of the fixing belt 61 (FIG. 1), and A pair of sheet metal 90c, 90d was screwed to each frame 92, and the sliding sheet was fixed to the holder. The holder on which the sliding sheet was fixed with screws was attached to a belt fixing device of a high-speed copying machine (Fuji Xerox Co., Ltd .: Color 1000 Press), and wrinkle generation evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]:
Only the rear end portion of the sliding sheet along the rotational traveling direction (the arrow direction in FIG. 2) of the fixing belt 61 (FIG. 1) is fixed to the holder by using a plate and a screw as a frame as in Comparative Example 1, On the other hand, the front end portion of the sliding sheet along the rotational running direction of the fixing belt (the arrow direction in FIG. 2) was pulled to the holder via the spring member 80 in the same manner as in Example 1. The holder to which the sliding sheet was attached was attached to a belt fixing device of a high-speed copying machine (manufactured by Fuji Xerox Co., Ltd .: Color 1000 Press), and wrinkle generation was evaluated in the same manner as in Example 1. The results are shown in Table 1. In addition, since only the one side edge part which a sliding sheet opposes is hold | maintained with the spring member, the sliding sheet extended at the fixing temperature is pulled by the spring member, and the tendency for the position of a sliding sheet to shift as a result is seen. . In addition, the sliding sheet, which has a shape that conforms to the shape of the holder at high temperature, shrinks and shifts when it is returned to room temperature, and the shape attached to the corners of the holder particularly at high temperature shifts. Again, since it was stretched and pressed at a high temperature during fixing, the angle shape of the holder attached to the sliding sheet tended to remain somewhat when fixing a plurality of sheets.

[Comparative Example 3]:
In the configuration shown in FIG. 4, only the left and right ends of the sliding belt 68 along the rotational travel direction (arrow direction in FIG. 4) of the fixing belt 61 (FIG. 1), that is, both ends of the sliding sheet 68 in the rotational axis direction. Only the part was produced in the same manner as in Example 1 except that the holder 65 was pulled and held through the spring member 82. A holder in which only the left and right end portions of the sliding sheet were pulled was attached to a belt fixing device of a high speed copying machine (manufactured by Fuji Xerox Co., Ltd .: Color 1000 Press), and wrinkle generation evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

  In the example, it can be seen that the occurrence of wrinkles in the sliding sheet is suppressed even when the sliding sheet is heated and stretched in the fixing device, as compared with the comparative example.

[Example 3]
As a holder 65 (FIGS. 2 and 3) as a holding member, a rectangular parallelepiped molded body made of a metal material (specifically SUS304) is used, and as a sliding sheet 68 (FIGS. 2 and 3), a crosslinked PTFE sheet is used. (Hitachi Cable: Exelon XF-1B, thickness: 0.3 mm) A single-layer sliding sheet was used. In place of the spring member 80 shown in FIGS. 2 and 3, a heat-shrinkable tube PST made by Heraman Tighton is used as a heat-shrinkable member, and wrinkles due to heating of the sliding sheet at a fixing temperature (for example, 200 ° C.) are eliminated. As shown in FIGS. 2 and 3, the fixing belt 61 (FIG. 1) rotates and travels in the rotational direction (FIGS. 2 and 3). The front and rear end portions of the sliding sheet 68 along the arrow direction of FIG.

  The holder 65 on which the sliding sheet 68 is pulled is attached to a belt fixing device of a high-speed copying machine (manufactured by Fuji Xerox Co., Ltd .: Color 1000 Press), the temperature is raised to the fixing temperature (200 ° C.), and the process speed is increased to 180 ppm. When the wrinkle of the sliding sheet was visually evaluated after fixing 500,000 sheets, almost no wrinkle was generated on the sliding sheet, and sliding was also caused by the shearing force on the sliding sheet generated by running of the fixing belt. No creep occurred on the sheet. Here, “creep” refers to a deformation that occurs after a certain period of time in a material that is subjected to a certain temperature and a certain stress.

[Example 4]
As a holder 65 (FIGS. 2 and 3) as a holding member, a rectangular parallelepiped molded body made of a metal material (specifically SUS304) is used, and as a sliding sheet 68 (FIGS. 2 and 3), a crosslinked PTFE sheet is used. (Hitachi Cable: Exelon XF-1B, thickness: 0.3 mm) A single-layer sliding sheet was used. In place of the spring member 80 and the frame 92 shown in FIGS. 2 and 3, a tension member provided separately from the holder 65 (FIGS. 2 and 3) as a holding member is used in the rotation running direction (process direction) of the fixing belt. It connected with each of two sets of sheet metal which has pinched the front-and-rear edge part of the sliding sheet | seat along. The tension force of the tension member is set at a fixing temperature (for example, 200 ° C.) that is set to a force that is equal to or greater than a tensile force that can suppress wrinkles due to heating of the sliding sheet and is less than an elastic limit point of the sliding sheet. The tension member was pulled up under the control of the section. Thereafter, the holder 65 on which the sliding sheet 68 is mounted and the stretching member are attached to a belt fixing device of a high speed copying machine (Fuji Xerox Co., Ltd .: Color 1000 Press), and the temperature is raised to the fixing temperature (200 ° C.). After the process speed was increased to 180 ppm and 500,000 sheets were fixed, the sliding sheet was visually evaluated for wrinkling. As a result, the sliding sheet was hardly wrinkled.

  As an application example of the present invention, there is application to an image forming apparatus such as a copying machine or a printer using an electrophotographic system.

  1Y, 1M, 1C, 1K Image forming unit, 10 Primary transfer unit, 11 Photosensitive drum, 12 Charger, 13 Laser exposure unit, 14 Developer, 15 Intermediate transfer belt, 16 Primary transfer roll, 17 Drum cleaner, 20 2 Next transfer section, 22 Secondary transfer roll, 25 Backup roll, 26 Feed roll, 31 Drive roll, 32 Support roll, 33 Tension roll, 34 Cleaning backup roll, 35 Intermediate transfer belt cleaner, 40 Control section, 43 Image density sensor, DESCRIPTION OF SYMBOLS 50 Recording medium accommodating part, 51 Pickup roll, 52 Conveyance roll, 53 Conveyance chute, 55 Conveyance belt, 56 Fixing inlet guide, 60 Fixing device, 61 Fixing belt, 62 Pressure roll, 63 Belt guide member, 64 Press pad, 65 Holder, 67 Lubricant Cloth member, 68 Sliding sheet, 70 Peeling auxiliary member, 71 Peeling baffle, 72 Baffle holder, 80, 82 Spring member, 85 Magnetic field generation unit, 90a, 90b, 90c, 90d, 90e, 90f Sheet metal, 92 frame, 100 image Forming device, 621 core, 622 rubber layer, 623 surface layer, 851 excitation coil, 852 coil support member, 853 excitation circuit.

Claims (3)

A rotatable rotating member;
A rotation that is arranged in pressure contact with the rotating member and fixes the unfixed toner image on the recording medium by sandwiching a recording medium holding an unfixed toner image in a nip formed between the rotating member and the rotating member. A possible film tubular body,
A sliding sheet interposed between the film tubular body and the pressing member;
A holding member for holding the sliding sheet and the pressing member;
A spring member for pulling and holding the front and rear ends of the sliding sheet along the direction of rotation of the film tubular body to the holding member;
A fixing device.   The fixing device according to claim 1, further comprising a second spring member that pulls the left and right end portions of the sliding sheet to the holding member along a rotation axis direction of the film tubular body. A latent image forming unit that forms a latent image on the latent image holding member; a developing unit that develops the latent image using a developer for developing an electrostatic image; and a developed toner image via an intermediate transfer member or An image forming apparatus comprising: transfer means for transferring onto a transfer body without intervention; and fixing means for fixing a toner image on the transfer body;
An image forming apparatus, wherein the fixing unit includes the fixing device according to claim 1.

Images