JP2017026761A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device and an image forming apparatus that detects damage to ends in a rotation axis direction of a belt member.SOLUTION: A fixing device comprises: a rotatable pressure roll; a fixing belt 62 that is rotatable in contact with the pressure roll; a nip forming member that is arranged opposite the pressure roll across the fixing belt 62, presses the fixing belt 62 against the pressure roll to form a nip part at which a recording medium passes through, between the pressure roll and fixing belt 62; and a contact part 78 that has a notch 78b formed in at least part of an outer peripheral surface 78a that is in contact with an inner peripheral surface at ends in a rotation axis direction of the fixing belt 62. The fixing device includes: a regulation member that regulates displacement in the rotation axis direction of the fixing belt 62; and a detection device 82 that detects the presence or deformation of the fixing belt 64 in the notch 78b.SELECTED DRAWING: Figure 4

Description

  The present invention relates to 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 charged, and the photosensitive drum is controlled by light controlled based on image information. An electrostatic latent image is formed on the photosensitive drum by exposure, and the electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is transferred from the photosensitive drum to a recording medium such as paper. Thereafter, the toner image is fixed on the recording medium by a fixing device.

  As the fixing device, for example, a rotating member, a belt member that is in contact with the rotating member and rotationally moves in accordance with the rotating member, and presses the inner surface of the belt member toward the rotating member. A fixing device that fixes a toner image on the recording medium by passing the recording medium through the nip portion. (For example, see Patent Documents 1 and 2).

  Also, for example, Patent Document 3 discloses a fixing device having a belt member that is wound around a plurality of rollers and driven to travel, and is provided with a belt breakage detecting unit that detects breakage of the belt member. ing.

Japanese Patent Application Laid-Open No. 11-133776 JP 2005-148618 A JP 2002-287542 A

  An object of the present invention is to provide a fixing device and an image forming apparatus that detect breakage of an end portion of a belt member in a rotation axis direction.

  The invention according to claim 1 is disposed so as to face a rotatable rotating member, a rotatable belt member in contact with the rotating member, and the rotating member via the belt member. A nip forming member that forms a nip through which a recording medium passes between the rotating member and the belt member by pressing toward the rotating member; and an inner peripheral surface of an end portion in the rotation axis direction of the belt member; A regulating member that contacts and has a contact part formed with a notch in at least a part of the contact part, and restricts movement of the belt member in the rotation axis direction; and the belt member at the notch And a detecting unit that detects the presence or absence or deformation of the fixing device.

  The invention according to claim 2 is the fixing device according to claim 1, wherein the detection means is an optical detection device that optically detects the presence or absence or deformation of the belt member at the notch.

  According to a third aspect of the present invention, the detecting means includes a swinging member capable of swinging around a swinging center, and a detection unit that detects swinging of the swinging member. 3. The fixing device according to claim 1, wherein one end is in contact with an outer peripheral surface of the belt member and is opposed to the notch through the belt member.

  The invention according to claim 4 is the fixing device according to any one of claims 1 to 3, further comprising a heating source that contacts the inner surface or the outer surface of the belt member and heats the belt member.

  The invention according to claim 5 is the fixing device according to any one of claims 1 to 3, wherein the belt member includes an electromagnetic induction heat generating layer.

  According to a sixth aspect of the present invention, there is provided an image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming an electrostatic latent image on the charged surface of the image carrier, 6. A developing unit that develops an electrostatic latent image with a developer to form a toner image, a transfer unit that transfers the toner image to a recording medium, and the toner image that is fixed to the recording medium. An image forming apparatus comprising: the fixing device according to item 1.

  According to the first aspect of the present invention, there is provided a fixing device that detects breakage of the end of the belt member in the rotation axis direction.

  According to the second aspect of the present invention, there is provided a fixing device that detects the breakage of the end of the belt member in the rotation axis direction.

  According to the invention which concerns on Claim 3, the fixing device which detects the damage of the edge part of the rotating shaft direction of a belt member is provided.

  According to the invention which concerns on Claim 4, the fixing device which detects the damage of the edge part of the rotating shaft direction of a belt member is provided.

  According to the invention which concerns on Claim 5, the fixing device which detects the damage of the edge part of the rotating shaft direction of a belt member is provided.

  According to the sixth aspect of the present invention, there is provided an image forming apparatus including a fixing device that detects breakage of an end portion of the belt member in the rotation axis direction.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus including a fixing device according to an exemplary embodiment. FIG. 2 is a schematic cross-sectional view illustrating an example of a configuration of a fixing device according to the present embodiment. FIG. 5 is a schematic side view illustrating an example of a configuration of a regulating member viewed from a direction in which a recording medium is conveyed. (A) And (B) is a schematic diagram for demonstrating the detection apparatus provided in the fixing device of this embodiment. It is a figure for demonstrating the other shape of the notch part formed in the contact part, and is a schematic cross section in the AA of FIG. 4 (A). (A) is a schematic side view of the fixing belt in a state in which the fixing belt end portion (opposite side to the detection device) is damaged, and (B) is a view of the detection device and the contact portion along the AA line of (A). It is a schematic diagram. (A) is a schematic side view of the fixing belt in a state in which the fixing belt end portion (detection device side) is damaged, and (B) is a schematic diagram of the detection device and the fixing belt along the AA line of (A). It is. (A) And (B) is a schematic diagram for demonstrating the modification of the detection apparatus provided in the fixing device of this embodiment. (A) is a schematic side view of the fixing belt in a state in which the fixing belt end portion (opposite side to the detection device) is damaged, and (B) is a view of the detection device and the contact portion along the AA line of (A). It is a schematic diagram. (A) is a schematic side view of the fixing belt in a state where the fixing belt end portion (detection device side) is damaged, and (B) is a schematic diagram of the fixing belt and the detection device along the line AA of (A). It is.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus including a fixing device according to the present embodiment. An image forming apparatus 100 shown in FIG. 1 is an intermediate transfer type image forming apparatus generally called a tandem type. An image forming apparatus 100 shown in FIG. 1 has a plurality of image forming units 1Y on which toner images of respective color components (yellow (Y), magenta (M), cyan (C), black (B)) are formed by electrophotography. , 1M, 1C, 1K, a primary transfer unit 10 that sequentially transfers (primary transfer) the color component toner images formed by the image forming units 1Y, 1M, 1C, 1K to the intermediate transfer belt 15, and the intermediate transfer belt 15. A secondary transfer unit 20 that collectively transfers (secondary transfer) the superimposed toner image transferred thereon onto a recording medium (recording paper) P; and a fixing device 60 that fixes the secondary transferred image on the recording medium P. It is equipped with. Moreover, it has the control part 40 which controls operation | movement of each apparatus (each part).

  In this embodiment, each of the image forming units 1Y, 1M, 1C, and 1K includes a charger 12 that charges the photosensitive drum 11 around the photosensitive drum 11 that rotates in the direction of arrow A, and a photosensitive drum. A laser exposure unit 13 for writing an electrostatic latent image on the image 11 (in FIG. 1, the exposure beam is indicated by a symbol Bm), and each color component toner is accommodated so that the electrostatic latent image on the photosensitive drum 11 can be transferred with the toner. A developing device 14 for visualizing, a primary transfer roll 16 for transferring each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, and residual toner on the photosensitive drum 11. An electrophotographic device such as a drum cleaner 17 is removed in order. 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 which is an intermediate transfer member is constituted by a film endless belt (endless belt) in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide. The volume resistivity of the intermediate transfer belt 15 is formed to be, for example, 10 ⁶ Ωcm or more and 10 ¹⁴ Ωcm or less, and the thickness thereof is, for example, about 0.1 mm. The intermediate transfer belt 15 is circulated (rotated) by various rolls at a predetermined speed in the direction B shown in FIG. In the present embodiment, as 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 extends along the arrangement direction of the photosensitive drums 11. Provided in the secondary transfer unit 20 are a support roll 32 that supports the intermediate transfer belt 15, a tension roll 33 that functions as a correction roll that applies tension to the intermediate transfer belt 15 and prevents meandering of the intermediate transfer belt 15. And a cleaning backup roll 34 provided in a cleaning unit that scrapes off residual toner on the intermediate transfer belt 15.

In the present embodiment, 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, for example, a shaft (not shown) and a sponge layer (not shown) as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical bar made of a metal such as iron or SUS. The sponge layer is made of, for example, a blend rubber of acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and ethylene-propylene-diene rubber (EPDM) containing a conductive agent such as carbon black, and has a volume resistivity. Is a sponge-like cylindrical roll of 10 ⁷ Ωcm or more and 10 ⁹ Ωcm or less, for example. The primary transfer roll 16 is disposed in pressure contact with the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. Further, the primary transfer roll 16 is opposite to the toner charging polarity (negative polarity; the same applies hereinafter). A polarity voltage (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.

In the present embodiment, the secondary transfer unit 20 includes a secondary transfer roll 22 disposed on the toner image holding surface side of the intermediate transfer belt 15 and a backup roll 25. The backup roll 25 is composed of a tube of EPDM rubber and NBR blend rubber in which, for example, carbon is dispersed, and the inside is made of, for example, EPDM rubber. The surface resistivity is formed to be, for example, 10 ⁷ Ω / □ or more and 10 ¹⁰ Ω / □ or less, and the hardness is set to, for example, 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd.). Has been. The backup roll 25 is disposed on the back surface side of the intermediate transfer belt 15 to constitute a counter electrode of the secondary transfer roll 22, and a metal-made power supply roll 26 for applying a secondary transfer bias is disposed in contact therewith.

In the present embodiment, the secondary transfer roll 22 includes, for example, a shaft (not shown) and a sponge layer (not shown) as an elastic layer fixed around the shaft. The shaft is, for example, a cylindrical rod made of metal such as iron or SUS. The sponge layer is made of, for example, a blended rubber of NBR, SBR, and EPDM containing a conductive agent such as carbon black, and has a volume resistivity of 10 ⁷ Ωcm or more and 10 ⁹ Ωcm or less, such as a cylindrical shape such as a sponge. It is a roll. 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. Then, the toner image is secondarily transferred onto the recording medium P conveyed to the secondary transfer unit 20.

  Further, in the present embodiment, residual toner, paper dust, and the like on the intermediate transfer belt 15 after the secondary transfer are removed on the downstream side of the secondary transfer unit 20 of the intermediate transfer belt 15, and the surface of the intermediate transfer belt 15 is removed. An intermediate transfer belt cleaner 35 for cleaning the toner is detachably provided. Further, in the present embodiment, 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 on the upstream side of the yellow image forming unit 1Y. 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 mark provided on the back side of the intermediate transfer belt 15 and generates a reference signal. In response to an instruction from the control unit 40 based on the recognition of the reference signal, each image forming unit 1Y, 1M, 1C, and 1K are configured to start image formation.

  Furthermore, in the image forming apparatus 100 of the present embodiment, as a paper transport system, for example, a paper tray 50 that accommodates the recording medium P, and a pickup roll 51 that takes out and transports the recording medium P accumulated in the paper tray 50, The transport roll 52 that transports the recording medium P fed by the pickup roll 51, the transport chute 53 that feeds the recording medium P transported by the transport roll 52 to the secondary transfer unit 20, and the secondary transfer roll 22 A transport belt 55 that transports the recording medium P transported after the next transfer to the fixing device 60 and a fixing inlet guide 56 that guides the recording medium P to the fixing device 60 are provided.

  Next, a basic image forming process of the image forming apparatus 100 according to the present embodiment will be described.

  In the image forming apparatus 100 as shown in FIG. 1, image data output from an image reading apparatus (IIT) (not shown), a personal computer (PC) (not shown) or the like is received by an image processing apparatus (IPS) ( After the image processing is performed by the image forming unit 1Y, 1M, 1C, and 1K, an image forming operation is performed. Specifically, in the IPS, input reflectance data is subjected to predetermined image editing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and the like. Image processing is performed. 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 unit 13 irradiates, for example, an exposure beam Bm emitted from a semiconductor laser to the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K according to the input color material gradation data. . In each of the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then 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 are in contact with each other. Transcribed. More specifically, in the primary transfer unit 10, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (negative polarity) of the toner is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16. Primary transfer is performed by sequentially superposing the toner images on the surface of the intermediate transfer belt 15.

  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 transported to the secondary transfer unit 20, in the paper transport system, the pick-up roll 51 rotates in accordance with the timing at which the toner image is transported to the secondary transfer unit 20, and the predetermined size from the paper tray 50 is reached. The recording medium P, which is a sheet of paper, is supplied. The recording medium P supplied by the pickup roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 via the transport chute 53. Before reaching the secondary transfer unit 20, the recording medium P is temporarily stopped, and a registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner image is held. The position of the medium P 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 recording medium P 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 recording medium P by the secondary transfer unit 20 pressed by the secondary transfer roll 22 and the backup roll 25. The

  Thereafter, the recording medium P on which the toner image has been electrostatically transferred is transported as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and is provided downstream of the secondary transfer roll 22 in the paper transport direction. It is conveyed to the conveyor belt 55. On the conveyance belt 55, the recording medium P is conveyed to the fixing device 60 in accordance with the optimum conveyance speed in the fixing device 60. The unfixed toner image on the recording medium P conveyed to the fixing device 60 is fixed on the recording medium P by being subjected to a fixing process with heat and pressure by the fixing device 60, as will be described later. Then, the recording medium P on which the fixed image is formed is conveyed to a paper discharge placement unit provided in a discharge unit of the image forming apparatus.

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

  FIG. 2 is a schematic cross-sectional view illustrating an example of the configuration of the fixing device according to the present embodiment. A fixing device 60 shown in FIG. 2 rotates via a pressure roller 92 as an example of a rotatable rotating member, a fixing belt 62 as an example of a belt member that can rotate while contacting the rotating member, and the belt member. A pressure pad 64 as an example of a nip forming member that is disposed to face the member, presses the belt member toward the rotating member, and forms a nip portion through which the recording medium passes between the rotating member and the belt member; And a magnetic field generation unit 90 as an example of a heating source for heating the belt member.

  The fixing belt 62 shown in FIG. 2 is rotatable by a pressure pad 64 disposed inside the fixing belt 62, a belt travel guide 63, and a regulating member 74 disposed at both ends of the fixing belt 62, which will be described later. It is supported by. The fixing belt 62 contacts the pressure roll 92 at the nip portion N and rotates in the arrow C direction according to the pressure roll 92 rotating in the arrow D direction.

  The fixing belt 62 shown in FIG. 2 includes, for example, a base material layer, a heat generating layer provided on the base material layer, an elastic layer provided on the heat generating layer, and a release layer provided on the elastic layer. ing. The base material layer is made of, for example, a resin material such as polyester or polyimide, or a metal such as stainless steel. The thickness of the base material layer is preferably in the range of 10 μm to 100 μm, for example. The heat generating layer is a layer that generates heat by electromagnetic induction, and examples of the material constituting the heat generating layer include metals such as nickel, copper, zinc, and tin, and metal alloys thereof. The thickness of the heat generating layer is preferably in the range of 2 μm to 20 μm, for example. The material of the elastic layer is preferably, for example, a fluororesin, a silicone resin, a silicone rubber, or a fluororubber from the viewpoint of heat resistance, thermal conductivity, insulation, and the like. The thickness of the elastic layer is preferably in the range of 10 μm to 500 μm, for example. Examples of the material of the release layer include fluororesins such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) and polytetrafluoroethylene (PTFE) from the viewpoint of releasability and heat resistance. . The thickness of the release layer is preferably in the range of 20 μm to 100 μm, for example.

  The pressure pad 64 shown in FIG. 2 is attached to a holder 65 made of metal or the like inside the fixing belt 62. The pressure pad 64 is disposed so as to be pressed against the pressure roll 92 via the fixing belt 62, and a nip portion N through which the recording medium P passes is formed between the fixing belt 62 and the pressure roll 92. doing. Examples of the material of the pressure pad 64 include resin materials such as PES resin (polyethersulfone) and PPS resin (polyphenylene sulfide), and metals such as iron and aluminum. The fixing device 60 of the present embodiment preferably includes a sheet-like sliding member (not shown) provided between the pressure pad 64 and the fixing belt 62.

  2 includes a solid core (cylindrical metal core) 921, an elastic body layer 922 disposed around the core 921, and a release layer 923 disposed around the elastic body layer 922. It is a cylindrical roll provided. For example, both ends of the core 921 are rotatably supported by a bearing member (not shown), and predetermined with respect to the fixing belt 62 by a biasing member such as a coil spring disposed at both ends of the core 921. It is pressed by the pressed pressure.

  Examples of the material of the core 921 shown in FIG. 2 include metals or alloys such as iron, aluminum, SUS, and copper, ceramics, fiber reinforced metal (FRM), and the like.

  The material of the elastic layer 922 shown in FIG. 2 is, for example, rubber, elastomer, foamed resin or the like having a hardness (JIS-A: hardness measured by a JIS-KA type testing machine) of 15 ° to 60 °. More specifically, silicone rubber, fluororubber, liquid silicone rubber filled with hollow glass beads, silicone sponge and the like can be mentioned. The thickness of the elastic body layer 922 is preferably in the range of 2 mm to 20 mm, for example.

  Examples of the material of the release layer 923 shown in FIG. 2 include fluororesins such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) and polytetrafluoroethylene (PTFE), and silicone rubber. For the purpose of imparting antistatic properties, the release layer 923 may contain, for example, conductive powder such as carbon black, graphite, metal powder, etc., and for the purpose of improving wear resistance. For example, powders of inorganic compounds such as titanium oxide, iron oxide, and aluminum oxide may be blended. The thickness of the release layer 923 is preferably in the range of 10 μm to 200 μm, for example.

  The magnetic field generation unit 90 shown in FIG. 2 has a curved cross section that follows the shape of the fixing belt 62, and is installed at an interval of, for example, about 0.5 mm or more and 2 mm or less from the outer peripheral surface of the fixing belt 62. Yes. A magnetic field generation unit 90 shown in FIG. 2 includes an excitation coil 901 that generates a magnetic field, a coil support member 902 that holds the excitation coil 901, and an excitation circuit 903 that supplies current to the excitation coil 901.

  As the exciting coil 901, for example, a litz wire obtained by bundling a plurality of copper wires having a diameter of 0.5 mm that are insulated from each other (for example, about 16 or more and 20 or less) is circular, elliptical, rectangular, or the like. Those formed by wrapping around are used. An AC magnetic field is generated around the excitation coil 901 by applying an AC current having a predetermined frequency (for example, a range of 10 kHz to 50 kHz) to the excitation coil 901 by the excitation circuit 903. When the AC magnetic field crosses the heat generating layer of the fixing belt 62, an eddy current is generated so that a magnetic field that prevents the change of the AC magnetic field is generated by electromagnetic induction. Then, when the eddy current flows through the heat generating layer of the fixing belt 62, for example, Joule heat is generated by electric power proportional to the resistance value of the heat generating layer, and the fixing belt 62 is heated.

  The coil support member 902 is made of, for example, a nonmagnetic material having heat resistance. Examples of the nonmagnetic material include heat-resistant glass, polycarbonate, polyether sulfone, polyphenylene sulfide (PPS), and other heat-resistant resins, or resins obtained by mixing glass fibers with the heat-resistant resin.

  In the present embodiment, an electromagnetic induction heating type fixing device 60 including a magnetic field generation unit 90 will be described as an example of a heating source for heating the fixing belt 62. However, the present invention is not limited to this. A heating element, a resistance heating element, or the like may be used. Examples of the radiant 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 present embodiment, the fixing belt 62 may be heated by bringing a heating source such as a radiation heating element or a resistance heating element into contact with the inner surface or the outer surface of the fixing belt 62.

  The belt traveling guide 63 shown in FIG. 2 is attached to the holder 65 inside the fixing belt 62, and is configured so that the fixing belt 62 rotates around the outer peripheral surface of the belt traveling guide 63.

  In the fixing device 60 shown in FIG. 2, a separation assisting member 70 for separating the recording medium P separated from the fixing belt 62 from the fixing belt 62 and guiding it to a paper discharge path toward the discharge portion of the image forming apparatus 100 is provided. Has been placed. The peeling auxiliary member 70 is held by a baffle holder 72 in a state where the peeling baffle 71 is in contact with the fixing belt 62 in a direction (counter direction) opposite to the rotation direction of the fixing belt 62.

  FIG. 3 is a schematic side view illustrating an example of the configuration of the regulating member viewed from the direction in which the recording medium is conveyed. As shown in FIG. 3, the regulating member 74 used in the present embodiment has a flange portion 76 and a contact portion 78. The contact portions 78 are installed and fixed at both end portions of the holder 65, and support both end portions in the rotation axis direction of the fixing belt 62 (hereinafter simply referred to as both end portions or end portions) from the inner peripheral surface side. The contact portion 78 shown in FIG. 3 has, for example, a cylindrical shape, and the outer peripheral surface 78 a becomes a contact portion that comes into contact with the inner peripheral surface of the end portion in the rotation axis direction of the fixing belt 62. In the contact portion 78 shown in FIG. 3, a notch 78 b is formed in at least a part of the outer peripheral surface 78 a serving as a contact portion with the inner peripheral surface of the end portion of the fixing belt 62. The flange portions 76 are arranged in a state of being spaced apart from each other at a certain distance so as to abut against the end surface of the fixing belt 62 when meandering. In addition, a holding portion 80 is provided on the opposite side of the contact portion 78 with respect to the flange portion 76, the holding portion 80 is held by a fixing portion in the fixing device 60, and the regulating member 74 is fixed. The regulating member 74 is formed of, for example, a heat-resistant resin such as PPS, PET, PBT, or LCP, or a material to which a filler for further reducing durability or a friction coefficient is added.

  4A and 4B are schematic views for explaining a detection device provided in the fixing device of the present embodiment, and FIG. 4A is a detection as seen from the direction in which the recording medium is conveyed. 4B is a schematic side view of the apparatus and the fixing belt, and FIG. 4B is a schematic view of the detection apparatus and the fixing belt viewed from the rotation axis direction (longitudinal direction) of the fixing belt. The fixing belt shown in FIG. 4B is a schematic cross-sectional view taken along the line AA in FIG.

  As shown in FIG. 4A, the fixing device 60 of this embodiment includes a detection device 82 provided at the end of the fixing belt 62 in the rotation axis direction. Further, as shown in FIG. 4B, the detection device 82 is disposed so as to face the notch 78b formed in the contact portion 78 with the fixing belt 62 interposed therebetween. Note that the detection device 82 and the notch portion 78b may be provided on at least one end side of both ends of the fixing belt 62 in the rotation axis direction.

  The detection device 82 used in the present embodiment is, for example, an optical detection device (hereinafter referred to as an optical detection device 82) that optically detects the presence or absence or displacement of the fixing belt 62 at the notch 78b. The optical detection device 82 includes, for example, a light emitting unit that emits light toward the fixing belt 62 and a light receiving unit that receives light reflected by the fixing belt 62 and the like. Based on the strength or the like, the presence / absence or deformation of the fixing belt 62 at the notch 78b is detected.

  The cutout portion 78b shown in FIG. 4B is a through-hole penetrating the wall forming the hollow cylindrical contact portion 78, but the shape of the cutout portion 78b is not limited to this. . FIG. 5 is a view for explaining another shape of the notch formed in the contact portion, and is a schematic cross-sectional view taken along the line AA of FIG. As shown in FIG. 5, the notch 78 b may be, for example, a groove (concave) that does not penetrate the wall of the contact portion 78. That is, the cutout portion 78b of the present embodiment may have a step shape that is recessed in the contact portion 78 with respect to a contact portion (outer peripheral surface 78a) that contacts the end portion of the fixing belt 62. In addition, in this embodiment, although the hollow contact part 78 is illustrated, it is not restricted to this, The solid contact part 78 may be sufficient. The size of the cutout portion 78b formed in the contact portion 78 is not particularly limited as long as it is a size that can be detected by the detection device 82. However, if the cutout portion 78b is too large, the strength of the contact portion 78 is reduced. May decrease.

  The operation of the fixing device 60 of this embodiment will be described.

  In the fixing device 60 of the present embodiment, the pressure roll 92 is connected to a drive motor (not shown) and rotates in the direction of arrow D shown in FIG. 2, and the fixing belt 62 also rotates in the direction of arrow C following this rotation. . When the fixing belt 62 is exposed to the magnetic field generated by the exciting coil 901, as described above, an eddy current is generated in the heat generating layer in the fixing belt 62, and the fixing belt 62 reaches a temperature at which the outer peripheral surface can be fixed. Heated. The fixing belt 62 heated in this way is moved to the nip portion formed with the pressure roll 92. In addition, the recording medium P on which the toner image is electrostatically transferred in the secondary transfer unit 20 of the image forming apparatus 100 illustrated in FIG. 1 is formed between the pressure roll 92 and the fixing belt 62 by the conveying unit. It is conveyed to the nip portion N. Then, when the recording medium P passes through the nip portion N, pressure acting on the nip portion N, heat supplied from the fixing belt 62, and the like are applied to the recording medium P, and an unfixed toner image is formed on the recording medium P. It is fixed. The recording medium P after fixing passes through the nip portion N, is peeled off from the fixing belt 62, and is discharged from the fixing device 60. The fixing belt 62 that has completed the fixing process in the nip portion N rotates in the direction of the exciting coil 901 and is heated again in preparation for the next fixing process.

  By the way, when the frictional force from the pressure roll 92 becomes non-uniform in the width direction due to variations in component dimensions or the influence of the recording medium P passing through the nip portion N, the fixing belt 62 is used. There is a case in which a so-called belt walk is generated in which a force that moves in the direction of the rotation axis (width direction) (hereinafter referred to as a shift movement force) acts on one end. In general, even if the fixing belt 62 is shifted toward the end in the rotation axis direction, the end of the fixing belt 62 contacts the flange portion 76 of the restricting member 74, so that the restriction member 74 is not installed. Thus, the movement (meandering) of the fixing belt 62 in the direction of the rotation axis is suppressed. However, when the shifting force applied to the fixing belt 62 increases, for example, the end of the fixing belt 62 may buckle, and the end of the fixing belt 62 may be damaged when the fixing belt 62 rotates in this state. . When the end portion of the fixing belt 62 is damaged, a local temperature rise or the like may occur. Therefore, it is desirable to quickly detect the end portion of the fixing belt 62. In particular, in a fixing device provided with a heat generating layer that generates heat by electromagnetic induction on the fixing belt 62, or a fixing device provided with a heating source that contacts the inner surface or outer surface of the fixing belt 62 and heats the fixing belt 62, the heat generating layer, Since it may lead to abnormal heat generation of the heating source, it is desirable to quickly detect breakage of the end portion of the fixing belt 62.

  6A is a schematic side view of the fixing belt in a state where the end portion of the fixing belt (the side opposite to the detection device) is damaged, and FIG. 6B is a cross-sectional view taken along line AA in FIG. It is a schematic diagram of a detection apparatus and a contact part. For example, when the end of the fixing belt 62 opposite to the detection device 82 is damaged, as shown in FIG. 6A, a part or all of the notch 78b covered with the fixing belt 62 is exposed. At this time, as shown in FIG. 6B, since the light emitted from the light emitting part of the optical detection device 82 mainly passes through the notch part 78b, the notch part 78b is formed in the fixing belt 62 that is not damaged. Compared with the case where the light is covered, the intensity of the reflected light received by the light receiving unit is reduced. Further, even in the case of the recess-shaped notch portion 78b as shown in FIG. 5, the light emitted from the light emitting portion is scattered by the recess-shaped notch portion 78b. Compared with the case where the light is covered, the intensity of the reflected light received by the light receiving unit is reduced. By detecting such a variation in reflected light intensity with the optical detection device 82, the presence or absence of the fixing belt 62 at the notch 78b is detected. That is, when the reflected light intensity fluctuates, a part or all of the cutout portion 78b is exposed, and breakage of the end portion of the fixing belt 62 is detected.

  FIG. 7A is a schematic side view of the fixing belt in a state where the end portion of the fixing belt (detecting device side) is damaged, and FIG. 7B is a detecting device taken along the line AA in FIG. 2 is a schematic diagram of a fixing belt. For example, when the end portion of the fixing belt 62 on the detection device 82 side is damaged, the end portion of the fixing belt 62 is moved to the outer peripheral surface side of the fixing belt 62 as shown in FIG. Projecting (projecting part 62a). As described above, when the end portion of the fixing belt 62 is deformed, the light emitted from the light emitting portion of the detection device 82 is reflected by the protruding portion 62a, so that it is compared with the case where it is reflected by the undeformed fixing belt 62. The distance from when the light emitted from the light emitting unit of the detection device 82 is reflected by the object and received by the light receiving unit varies (for example, becomes shorter), and the intensity of the reflected light received by the light receiving unit, etc. Also fluctuate. By detecting such a fluctuation in reflected light intensity or the like by the detection device 82, deformation of the fixing belt 62 is detected. That is, the deformation of the fixing belt 62 at the notch is detected, so that the breakage of the end of the fixing belt 62 is detected. Although not shown in the figure, for example, a control unit that is electrically connected to the detection device 82 is provided, and when the detection device 82 detects the presence or absence or deformation of the fixing belt 62 at the notch. The control unit controls the operation of the fixing device 60 to be stopped, the heating of the fixing belt 62 to be stopped, or a warning prompting the replacement of the fixing belt 62 to be displayed on the display unit of the image forming apparatus 100. It is desirable that

  In the present exemplary embodiment, the example in which the presence / absence and deformation of the fixing belt 62 is detected using the intensity of reflected light has been described. However, the present invention is not limited to this. For example, with the breakage of the end portion of the fixing belt 62, the distance until the light emitted from the light emitting unit of the optical detection device 82 is reflected by the object and received by the light receiving unit also varies. Therefore, for example, the light irradiated by the light emitting unit is reflected by the object and the light received by the light receiving unit is evaluated and calculated, converted into a distance, and the presence or absence of the fixing belt 62 or deformation based on the variation in the distance May be detected. As an evaluation / calculation method for converting the light received by the light receiving unit into a distance, a conventionally known method or the like is used, and examples thereof include a triangular distance measurement method, a phase difference distance measurement method, and a pulse propagation method.

  Further, in the present embodiment, when the measurement value (for example, reflected light intensity, distance, etc.) obtained by the detection device 82 is outside the preset threshold range, the fixing belt 62 is not present on the notch 78b, or As the fixing belt 62 is deformed on the notch 78b, the fixing belt 62 may be damaged.

  In the present embodiment, the present invention is not limited to the optical detection device 82. For example, the presence or deformation of the fixing belt 62 at the notch 78b may be detected using the detection device 82 described below. .

  FIGS. 8A and 8B are schematic views for explaining a modification of the detection device provided in the fixing device of the present embodiment, and FIG. 8A is from the direction in which the recording medium is conveyed. FIG. 8B is a schematic side view of the detection device and the fixing belt viewed from the rotation axis direction (longitudinal direction) of the fixing belt. The fixing belt shown in FIG. 8B is a schematic cross-sectional view taken along the line AA in FIG.

  As shown in FIGS. 8A and 8B, the detection device 82 of the present embodiment has a swinging member 84 (hereinafter referred to as a swinging member) that can swing (rotate) around a swinging shaft (rotating shaft) 84a. And a detection unit 86 that detects the swing of the swing arm 84. Also, as shown in FIG. 8B, a triangular arm end 84 b is provided at one end of the swing arm 84, and the tip of the arm end 84 b is the end of the fixing belt 62 in the rotational axis direction. It is in contact with the outer peripheral surface of the part. Further, as shown in FIG. 8B, the arm end portion 84b faces a notch portion 78b provided in the contact portion 78 with the fixing belt 62 interposed therebetween. The detection unit 86 is, for example, an optical detection unit including a light emitting unit and a light receiving unit, and is provided at a position facing the other end of the swing arm 84 (an end opposite to the arm end 84b). It has been. Note that the detection device 82 and the notch portion 78b may be provided on at least one end side of both ends of the fixing belt 62 in the rotation axis direction.

  9A is a schematic side view of the fixing belt in a state where the end portion of the fixing belt (the side opposite to the detection device) is damaged, and FIG. 9B is a cross-sectional view taken along the line AA in FIG. It is a schematic diagram of a detection apparatus and a contact part. In the state where the end portion of the fixing belt 62 is not damaged, as shown in FIG. 8B, the arm end portion 84b of the swing arm 84 is in contact with the outer peripheral surface of the end portion of the fixing belt 62. The light emitted from the light emitting part of the detecting part 86 arranged on the other end side of the swing arm 84 is reflected by the swing arm 84 and received by the light receiving part. However, when the end portion of the fixing belt 62 opposite to the detection device 82 is damaged, as shown in FIG. 9A, a part or all of the notch 78b covered with the fixing belt 62 is exposed. Then, as shown in FIG. 9B, for example, when the swing arm 84 rotates in the arrow X direction around the swing shaft 84a, and the arm end portion 84b is dropped into the notch portion 78b, the swing arm The other end of 84 deviates from a position facing the detection unit 86. At this time, since the light emitted from the light emitting portion of the detecting portion 86 passes through the swing arm 84, the light receiving portion is compared with the case where the notched portion 78b is covered with the fixing belt 62 that is not damaged. The intensity of the reflected light received is reduced. The same applies to the case of the recessed notch 78b as shown in FIG. By detecting such a variation in reflected light intensity by the detection unit 86, the presence or absence of the fixing belt 62 at the notch 78b is detected. That is, when the reflected light intensity fluctuates, part or all of the notch 78b is exposed, and breakage of the end of the fixing belt 62 is detected.

  FIG. 10A is a schematic side view of the fixing belt in a state where the fixing belt end portion (detection device side) is damaged, and FIG. 10B is a fixing belt taken along line AA in FIG. It is a schematic diagram of a detection device. For example, when the end portion of the fixing belt 62 on the detection device 82 side is damaged, due to the stiffness of the fixing belt 62, a part of the end portion of the fixing belt 62 is, for example, as shown in FIG. Projecting to the outer peripheral surface side (protruding portion 62a). Thus, when the end of the fixing belt 62 on the detection device 82 side is deformed, for example, the swing arm 84 rotates about the swing shaft 84a in the direction of the arrow Y in the figure, and the other end of the swing arm 84 is It deviates from the position facing the detector 86. At this time, since the light emitted from the light emitting portion of the detecting portion 86 passes through the swing arm 84, the intensity of the reflected light received by the light receiving portion is lower than that of the fixing belt 62 that is not deformed. . By detecting such a variation in the reflected high intensity by the detection unit 86, deformation of the fixing belt 62 at the notch 78b is detected, and damage to the end of the fixing belt 62 is detected. Although not shown in the figure, a control unit that is electrically connected to the detection unit 86 is provided, and when the detection unit 86 detects the presence or absence or deformation of the fixing belt 62 in the notch 78b, The control unit controls the operation of the fixing device 60 to be stopped, the heating of the fixing belt 62 to be stopped, or a warning prompting the replacement of the fixing belt 62 to be displayed on the display unit of the image forming apparatus 100. It is desirable to be done.

  Further, in the present embodiment, when the measurement value (for example, reflected light intensity) obtained by the detection unit 86 is outside the preset threshold range, the fixing belt 62 is not present on the notch or the notch is notched. As the fixing belt 62 is deformed on the part, the breakage of the end of the fixing belt 62 may be detected.

  The detection unit 86 has been described by taking the optical detection unit 86 as an example. However, the detection unit 86 is not limited to this as long as it detects the swing of the swing arm 84. For example, the other end of the swing arm 84 is detected. An electromagnetic switch or the like that detects the contact of the magnetic body attached to the magnetic body may be used.

  In the fixing device 60 of the present embodiment, the pressure roller is illustrated as the rotating member, and the fixing belt disposed on the side in contact with the toner image on the recording medium is illustrated as the belt member. The members are not limited to these, and the rotating member may be a fixing roll, and the belt member may be used as a pressure belt disposed on the side not in contact with the toner image on the recording medium.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely, the present invention is not limited to the following examples.

(Example)
In the example, the test was performed using the fixing device shown in FIG. The specific configuration of the fixing device is as follows.

<Fixing belt>
A heat-generating layer in which a 10-μm nickel layer, a 10-μm copper layer, and a 1-μm nickel layer are laminated on a polyimide substrate having an outer diameter of 30.5 mm and a thickness of 60 μm is provided. A liquid-cured silicone rubber having a thickness of 200 μm is formed on the heat-generating layer. An elastic layer composed of (rubber hardness 33 degrees: JIS-A) was provided, and a release layer composed of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer tube having a thickness of 30 μm was coated on the elastic layer. This was used as a fixing belt. An adhesive layer made of a silane coupling agent was provided between the heat generation layer and the elastic layer, and between the elastic layer and the release layer. The surface temperature of the fixing belt was controlled by a temperature sensor and a temperature controller which are temperature sensitive elements arranged in contact with the inner surface of the fixing belt.

<Regulating member>
A regulating member shown in FIG. 3 was produced by molding a PPS resin containing glass fibers. The notch formed in the contact part of the regulating member was a through-hole-shaped notch as shown in FIG. The size of the notch is 5 mm wide × 10 mm long in the circumferential direction.

<Detection device>
A detection device shown in FIG. 8 is installed at one end of the fixing belt in the rotation axis direction. An optical sensor was used as the detection unit of the detection device. When the detection unit of the detection device detects breakage of the end portion of the fixing belt, the operation of the image forming apparatus is controlled to stop.

<Pressure roll>
A solid iron roll of φ18 is used as a core, and an elastic layer composed of a 5 mm silicone rubber sponge layer is provided thereon via an adhesive layer, and 50 μm carbon black is blended thereon via the adhesive layer. What provided the release layer comprised with an electroconductive PFA tube was used as a pressure roll.

<Nip forming member and sliding member>
A material in which 40% glass fiber was blended with PPS and molded with a width of 7 mm corresponding to the NIP width was used as a nip forming member. On this nip-forming member, a glass cloth woven sheet is sandwiched between fluororesin films, and then a heated and integrated sliding sheet is provided. NIP part was formed.

  This fixing device is mounted on an image forming apparatus (DoccentreVC3375), and the belt moving force is intentionally increased to create a broken state of the fixing belt. As a result, the operation of the image forming apparatus stops after 1 sec of breakage, resulting in an abnormality. The device was not deformed, failed or smoked due to heat generation. In addition, after 200,000 sheets have been passed through the image forming apparatus, the failure state of the fixing belt was intentionally created as described above. Stopped, and there was no device deformation, failure, or smoke due to abnormal heat generation.

(Comparative example)
Instead of providing the detection device and the notch portion of the embodiment, the above embodiment is the same as the above embodiment except that a reflecting plate is installed on the outer peripheral surface of one end portion of the fixing belt and an optical sensor is installed at a position 2 cm away from the reflecting plate. And a fixing device and an image forming apparatus similar to the above. When the intensity of the reflected light from the reflecting plate fluctuates with the optical sensor, the operation of the image forming apparatus is controlled to stop, assuming that the breakage of the fixing belt end is detected.

  As in the embodiment, as a result of intentionally increasing the belt moving force and creating a belt breakage state, at the initial stage of sheet passing, the operation of the image forming apparatus is stopped after 1 sec of breakage, and the apparatus is deformed due to abnormal heat generation. There was no breakdown or smoke. However, after passing 100,000 sheets, the operation of the image forming apparatus stopped because it was determined that the fixing belt end was detected even though the fixing belt end was not damaged. This is considered to be because dirt such as paper dust and toner adhering to the reflecting plate and dust from the outside adhere to the reflecting plate surface and the amount of reflected light is reduced.

  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, 42 Reference sensor, 43 Image density sensor, 50 paper tray, 51 pickup roll, 52 transport roll, 53 transport chute, 55 transport belt, 56 fixing inlet guide, 60 fixing device, 62 fixing belt, 62a protrusion, 63 belt running guide, 64 pressure pad, 65 holder, 7 0 peeling assisting member, 71 peeling baffle, 72 baffle holder, 74 regulating member, 76 flange portion, 78 contact portion, 78a outer peripheral surface, 78b notched portion, 80 holding portion, 82 detection device (optical detection device), 84 shaking Moving member (swinging arm), 84a swinging shaft, 84b arm end, 86 detection unit, 90 magnetic field generation unit, 92 pressure roll, 100 image forming apparatus, 901 excitation coil, 902 coil support member, 903 excitation circuit, 921 Core, 922 Elastic layer, 923 Release layer.

Claims (6)

A rotatable rotating member;
A belt member rotatable while contacting the rotating member;
A nip portion that is disposed so as to face the rotating member via the belt member, presses the belt member toward the rotating member, and a recording medium passes between the rotating member and the belt member. A nip forming member to be formed;
The belt member has a contact portion that is in contact with the inner peripheral surface of the end portion in the rotation axis direction of the belt member and has a notch formed in at least a part of the contact portion, and restricts movement of the belt member in the rotation axis direction. A regulating member,
And a detecting unit that detects presence or absence or deformation of the belt member at the notch.   The fixing device according to claim 1, wherein the detection unit is an optical detection device that optically detects presence or absence or deformation of the belt member at the notch.   The detecting means includes a swinging member that can swing around a swinging center, and a detection unit that detects swinging of the swinging member, and one end of the swinging member has an outer periphery of the belt member 3. The fixing device according to claim 1, wherein the fixing device is in a position in contact with a surface and opposed to the notch through the belt member.   The fixing device according to claim 1, further comprising a heating source that contacts an inner surface or an outer surface of the belt member and heats the belt member.   The fixing device according to claim 1, wherein the belt member includes an electromagnetic induction heat generating layer. An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming an electrostatic latent image on the charged surface of the image carrier, and the electrostatic latent image by a developer. A developing unit that develops a toner image, a transfer unit that transfers the toner image to a recording medium, and a fixing device according to claim 1 that fixes the toner image to the recording medium. An image forming apparatus comprising: