JP2016166944A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device in which a lubricant is applied to an inner surface of a belt, and suppress the lubricant from leaking to the outside of the belt.SOLUTION: A fixing part comprises: a cylindrical fixing belt 51 that has a lubricant applied to its inner surface and fixes an image to a recording medium by heat; a heating part that is arranged inside the fixing belt 51 and heats the fixing belt 51; belt holding members 611 that cover the ends E1 of the fixing belt 51 from the inside and outside and slide with the fixing belt 51 when the fixing belt 51 is driven to rotate; and support members 612 that fix the belt holding members 611 and support the ends of the fixing belt 51 from the inside via the belt holding members 611.SELECTED DRAWING: Figure 6A

Description

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

  In order to reduce friction between a belt formed in an endless cylindrical shape and a member provided inside the belt, a technique for supplying oil to the inner surface of the belt is known. In Patent Document 1, in a fixing device in which oil is supplied to the inner surface of the fixing belt in order to reduce friction between the fixing belt and a pressure contact member provided inside the fixing belt, the oil is supplied from the end of the fixing belt. In order to prevent leakage to the outside, it is described that a groove is provided in the cylindrical portion of the belt guide member.

JP 2002-357968 A

  The present invention provides a technique for suppressing leakage of lubricant to the outside of a belt in a fixing device in which the lubricant is applied to the inner surface of the belt.

  According to a first aspect of the present invention, there is provided a fixing device including a cylindrical belt having an inner surface coated with a lubricant and fixing an image on a recording medium by heat, a heating unit disposed inside the belt and heating the belt, Covering the end of the belt from the inside and the outside, and when the belt is driven to rotate, a cover member that slides with the belt, and fixing the cover member, and the end of the belt from the inside through the cover member And a supporting member to support.

  According to a second aspect of the present invention, there is provided the fixing device according to the first aspect, wherein the covering member covers an end of the belt along the entire circumference of the belt.

  According to a third aspect of the present invention, there is provided the fixing device according to the first or second aspect, wherein the length of the region in which the covering member covers the belt in the longitudinal direction of the belt is determined when the belt is rotated. It exceeds the maximum value of the length moving in the longitudinal direction.

  According to a fourth aspect of the present invention, there is provided the fixing device according to any one of the first to third aspects, wherein the covering member is made of perfluoroalkoxyalkane.

  A fixing device according to a fifth aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the rotating body rotates while pressing the recording medium between the belt, the belt, and the rotating body. And a contact / separation mechanism for contacting or separating each other.

  An image forming apparatus according to claim 6 is an image forming unit that forms an unfixed image on a recording medium, a cylindrical belt that is coated with a lubricant on its inner surface and fixes the image onto the recording medium by heat, A heating unit that is disposed inside the belt, heats the belt, covers an end of the belt from the inside and the outside, and covers the belt when the belt is driven to rotate, and the covering member And a supporting member that supports the end portion of the belt from the inside through the covering member.

According to the invention which concerns on Claim 1 and Claim 6, compared with the case where the cover member does not cover the edge part of a belt from the inner side and the outer side, it is suppressed that a lubricant leaks to the outer side of a belt.
According to the invention which concerns on Claim 2, compared with the case where the cover member does not cover the edge part of a belt along the whole periphery, it is suppressed that a lubricant leaks to the outer side of a belt.
According to the invention of claim 3, when the length of the belt covering the belt in the longitudinal direction of the belt is equal to or less than the maximum length of the belt moving in the longitudinal direction when driven in rotation. Compared to the above, the lubricant is prevented from leaking to the outside of the belt.
According to the invention which concerns on Claim 4, compared with the case where the fluororesin does not cover the edge part of a belt from an inner side and an outer side, it is suppressed that a lubricant leaks to the outer side of a belt.
According to the invention which concerns on Claim 5, when a belt and a rotary body contact, it is suppressed that a lubricant leaks to the outer side of a belt.

The figure which shows the whole structure of an image forming apparatus Diagram showing the outline of the fixing unit A view of the fixing part from the direction of arrow III in FIG. An enlarged view of a part of the fixing belt The figure which shows the support mechanism of the fixing belt which concerns on a comparative example The figure which shows the support mechanism of the fixing belt which concerns on a comparative example The figure which shows the support mechanism of the fixing belt which concerns on one Embodiment. The figure which shows the support mechanism of the fixing belt which concerns on one Embodiment. The figure which shows the support mechanism of the fixing belt which concerns on a modification.

  FIG. 1 is a diagram showing an overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 is an apparatus that forms an image by electrophotography. The image forming apparatus 1 according to the present embodiment is a so-called tandem type, and forms an image on a sheet P that is an example of a recording medium based on image data representing an image. In the figure, the control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU stores a computer program (hereinafter simply referred to as “ROM”) stored in the ROM or the storage unit 12. Each unit of the image forming apparatus 1 is controlled by reading out and executing the program. The storage unit 12 is a large-capacity storage unit such as a hard disk drive, and stores a program read by the CPU of the control unit 11. The operation unit 17 includes operation buttons and the like for inputting various instructions. The operation unit 17 receives an operation by the user and supplies a signal corresponding to the operation content to the control unit 11.

  The developing units 13Y, 13M, 13C, and 13K form toner images on the paper P. The symbols Y, M, C, and K indicate configurations corresponding to yellow, magenta, cyan, and black toners, respectively. Although the developing units 13Y, 13M, 13C, and 13K use different toners, there is no significant difference in the configuration. Hereinafter, when it is not necessary to particularly distinguish each of the developing units 13Y, 13M, 13C, and 13K, the alphabet at the end of the code indicating the color of the toner is omitted and referred to as “developing unit 13”.

  Each developing unit 13 includes a photosensitive drum 31, a charger 32, an exposure device 33, a developing device 34, a primary transfer roll 35, and a drum cleaner 36. The photosensitive drum 31 is an image carrier having a charge generation layer and a charge transport layer, and is rotated in the direction of an arrow D13 in the drawing by a driving unit (not shown). The charger 32 charges the surface of the photosensitive drum 31. The exposure device 33 includes a laser emission source, a polygon mirror, and the like (both not shown), and a photoconductor after the laser light corresponding to the image data is charged by the charger 32 under the control of the control unit 11. Irradiation toward the drum 31. Thereby, a latent image is held on each photosensitive drum 31. The image data may be acquired from an external device by the control unit 11 via a communication unit (not shown). The external device is, for example, a reading device that reads an original image or a storage device that stores data indicating an image.

  The developing device 34 contains a two-component developer containing toner of any one of Y, M, C, and K and a magnetic carrier such as ferrite powder. The tip of the magnetic brush formed on the developing unit 34 comes into contact with the surface of the photosensitive drum 31, so that the toner is exposed on the surface of the photosensitive drum 31 by the exposure device 33, that is, an electrostatic latent image image. An image is formed (developed) on the photosensitive drum 31 by adhering to the line portion.

  The primary transfer roll 35 generates a predetermined potential difference at a position where the intermediate transfer belt 41 of the transfer unit 14 faces the photosensitive drum 31, and the image is transferred to the intermediate transfer belt 41 by this potential difference. The drum cleaner 36 removes untransferred toner remaining on the surface of the photosensitive drum 31 after the image is transferred, and neutralizes the surface of the photosensitive drum 31. That is, the drum cleaner 36 removes unnecessary toner and charges from the photosensitive drum 31 in preparation for the next image formation.

  The transfer unit 14 includes an intermediate transfer belt 41, a secondary transfer roll 42, a belt conveyance roll 43, and a backup roll 44, and determines an image formed by the developing unit 13 according to a user operation. This is a transfer section that transfers the paper P to the paper P of the selected paper type. The intermediate transfer belt 41 is an endless belt member, and the belt conveyance roll 43 and the backup roll 44 stretch the intermediate transfer belt 41. At least one of the belt conveyance roll 43 and the backup roll 44 is provided with a drive unit (not shown), and moves the intermediate transfer belt 41 in the direction of arrow D14 in the drawing. Note that the belt conveyance roll 43 or the backup roll 44 that does not have a driving unit rotates following the movement of the intermediate transfer belt 41. As the intermediate transfer belt 41 moves and rotates in the direction of the arrow D14 in the drawing, the image on the intermediate transfer belt 41 is moved to a region sandwiched between the secondary transfer roll 42 and the backup roll 44.

  The secondary transfer roll 42 transfers the image on the intermediate transfer belt 41 onto the paper P conveyed from the conveyance unit 16 by a potential difference with the intermediate transfer belt 41. The belt cleaner 49 removes untransferred toner remaining on the surface of the intermediate transfer belt 41. Then, the transfer unit 14 and the conveyance unit 16 convey the paper P on which the image has been transferred (that is, an unfixed image fixed on the recording medium by heating) to the fixing unit 15. The developing unit 13 and the transfer unit 14 are examples of image forming units.

  The fixing unit 15 (an example of a fixing device) fixes the image transferred onto the paper P by heating. The structure of the fixing unit 15 will be described later. The conveyance part 16 has a container and a conveyance roll. The container accommodates a sheet P cut into a predetermined size. In the example of FIG. 1, two types of paper P are used: paper P1 and paper P2 that is narrower than paper P1. The paper P accommodated in each container is taken out one by one by a transport roll in accordance with an instruction from the control unit 11 and transported to the transfer unit 14 via a paper transport path. The recording medium is not limited to paper, and may be, for example, a resin sheet. In short, the medium may be any medium that can form an image on the surface.

  FIG. 2 is a diagram showing an outline of the fixing unit 15. Hereinafter, in order to explain the arrangement of each component of the fixing unit 15, the space in which each component is arranged is represented as an xyz right-handed coordinate space. In addition, among the coordinate symbols shown in the figure, the symbol with a black circle inside a white circle represents an arrow heading from the back to the front of the page, and the inside is drawn with a white circle. The symbol represents an arrow heading from the front side to the back side. A direction along the x-axis in space is referred to as an x-axis direction. Of the x-axis directions, the direction in which the x component increases is referred to as + x direction, and the direction in which the x component decreases is referred to as -x direction. For the y and z components, the y-axis direction, + y direction, -y direction, z-axis direction, + z direction, and -z direction are defined. Further, when the sheet P passes through the fixing unit 15, the sheet P is conveyed in the z-axis direction with the surface on which the image is formed facing the + y direction. That is, the z-axis direction is the conveyance direction of the paper P, and the x-axis direction is the width direction of the paper P.

  The fixing unit 15 includes a fixing belt 51, a pressure roll 52, an electromagnetic induction unit 53, a magnetic core 54, a pressing pad 56, a holder 57, a heat storage plate 58, and a contact / separation mechanism 59. As shown in FIG. 2, the fixing belt 51 rotates in the arrow D51 direction around an axis O1 parallel to the x-axis direction. As shown in FIG. 2, the pressure roll 52 includes a metal cylindrical core member 521 and an elastic layer 522 provided on the surface of the core member 521. The core material 521 rotates in the direction of the arrow D52 around the axis O2, which is an axis parallel to the axis O1, and accordingly, the elastic layer 522 rotates in the direction of the arrow D52. The material of the elastic layer 522 is, for example, a silicone rubber layer or a fluorine rubber layer. The elastic layer 522 may include a surface release layer (fluororesin layer) on the surface thereof. The pressure roll 52 assists the heating of the sheet P by the fixing belt 51 by pressing the sheet P conveyed by the conveying unit 16 against the fixing belt 51 while being rotated by a driving unit (not shown). The pressure roll 52 is pressed (latched) against the fixing belt 51 by the contact / separation mechanism 59. In the state where the pressure roll 52 is not pressed against the fixing belt 51 by the contact / separation mechanism 59, the pressure roll 52 and the fixing belt 51 are not in contact with each other, and there is a gap between the two. The pressure roll 52 is an example of a rotating body. The fixing belt 51 is rotated by a driving unit (not shown) in a state where the pressure roll 52 is not pressed, and is applied by a frictional force from the pressure roll 52 in a state where the pressure roll 52 is pressed. The paper P is rotated by being driven by the pressure roll 52, and the paper P conveyed from the transfer unit 14 is conveyed to the discharge port 18. In the present embodiment, the drive unit that rotationally drives the fixing belt 51 is provided at one end in the x-axis direction (longitudinal direction of the fixing belt 51). That is, in the present embodiment, the fixing belt 51 is driven on one side.

  The pressing pad 56, the holder 57, and the heat storage plate 58 are disposed on the inner peripheral side of the fixing belt 51. The holder 57 is a rod-like member extending in the x-axis direction, and both ends in the x-axis direction are supported by the casing of the image forming apparatus 1. The holder 57 is made of, for example, a heat-resistant resin such as glass mixed PPS (polyphenylene sulfide) or a nonmagnetic metal such as gold (Au), silver (Ag), aluminum (Al), or copper (Cu). Is formed. As a result, the holder 57 is relatively less affected by the induced magnetic field and less susceptible to the induced magnetic field than when other materials are used. The holder 57 supports the pressing pad 56 so as to press it in the direction of the arrow D56 (-y direction) shown in FIG.

  The pressing pad 56 is made of a heat resistant resin such as LCP (Liquid Crystal Polymer), and is supported by the holder 57 at a position facing the pressure roll 52. The pressing pad 56 is disposed in a state of being pressed from the pressure roll 52 via the fixing belt 51 and presses the fixing belt 51 from the inside toward the direction of the pressure roll 52 (−y direction). As a result, a nip region R <b> 1 is formed between the fixing belt 51 and the pressure roll 52. The paper P is conveyed so as to pass through the nip region R1. In the nip region R <b> 1, the pressing pad 56 is deformed so as to be recessed toward the axis O <b> 1 by the pressing of the pressing roll 52, and the fixing belt 51 has a shape along the shape of the deformed pressing pad 56. The pressing pad 56 may be made of an elastic body such as silicone rubber or fluorine rubber. The pressing pad 56 is supported by the holder 57 so as not to rotate, and the fixing belt 51 rotates while sliding on the pressing pad 56.

  The heat storage plate 58 is a member that generates heat due to electromagnetic induction generated by the action of the alternating magnetic field generated by the electromagnetic induction unit 53 and conducts heat to the fixing belt 51. The heat storage plate 58 includes a magnetic path forming member 581, a resin layer 582, and a heat capacity adjusting member 583 that are stacked in this order from the inner peripheral surface side of the fixing belt 51 toward the axis O <b> 1. The heat storage plate 58 is supported by a support mechanism (not shown) so as to be pressed against the fixing belt 51 from the inside of the fixing belt 51 and so as not to rotate. The contact state is maintained.

  The magnetic path forming member 581 generates heat by the electromagnetic induction generated by the action of the alternating magnetic field generated by the electromagnetic induction unit 53 and heats the fixing belt 51. The magnetic path forming member 581 is an example of a heating unit according to the present invention. The magnetic path forming member 581 is a layer including a ferromagnetic material, and is, for example, a Ni-Fe-based or Ni-Cr-Fe-based magnetic shunt alloy. The Curie point of this ferromagnetic material may be in the range of not less than the set temperature of the fixing belt 51 and not more than the heat resistant temperature of the fixing belt 51. Specifically, for example, it is preferably 170 ° C. to 250 ° C. Desirably, it is 190 degreeC-230 degreeC. The magnetic path forming member 581 is formed in a shape along the inner peripheral surface of the fixing belt 51, is in contact with the inner peripheral surface of the fixing belt 51, and is disposed to face the electromagnetic induction portion 53 through the fixing belt 51. . The magnetic path forming member 581 is disposed in contact with the inner peripheral surface of the fixing belt 51 while maintaining the fixing belt 51 in a cylindrical shape without contacting the holder 57. The magnetic path forming member 581 generates heat by being electromagnetically induced by the action of an alternating magnetic field generated from the electromagnetic induction portion 53, and slides on the inner peripheral surface of the rotating fixing belt 51 to transmit heat to the fixing belt 51. The heat storage plate 58 is supported so as not to rotate by a support mechanism (not shown), and the fixing belt 51 rotates while sliding on the magnetic path forming member 581, and heat from the magnetic path forming member 581 is transmitted.

  The thickness of the magnetic path forming member 581 is, for example, 0.05 to 1.0 mm, desirably 0.3 to 0.6 mm. The shape of the magnetic path forming member 581 is a shape obtained by cutting a portion corresponding to a predetermined central angle range (for example, 30 ° to 180 °) from an alloy formed in a cylindrical shape having the above thickness. Although it is mentioned, it is not restricted to this.

  The resin layer 582 is provided along the magnetic path forming member 581 on the opposite side of the surface facing the fixing belt 51. The resin layer 582 is made of a heat-resistant resin such as a polyimide resin or a polyamideimide resin. Instead of the resin layer 582, for example, a layer using a material other than the resin such as a glass fiber sheet may be provided.

  In the heat capacity adjusting member 583, the resin layer 582 is provided on the opposite side of the surface facing the magnetic path forming member 581 along the resin layer 582. The heat capacity adjusting member 583 stores heat generated by the fixing belt 51 and the magnetic path forming member 581. The heat capacity adjusting member 583 is made of a nonmagnetic material such as aluminum (Al).

  The electromagnetic induction unit 53 includes an excitation coil to which an alternating current having a frequency determined from an excitation circuit (not shown) is supplied according to an instruction from the control unit 11. This frequency is, for example, a frequency of an alternating current generated by a general general-purpose power supply, for example, a frequency of 20 kHz to 100 kHz. The amount of the alternating current is controlled by the control unit 11. An exciting coil is a coil formed by winding litz wires, which are bundled copper wires insulated from each other, wound in a closed loop shape such as an elliptical shape or a rectangular shape. By supplying the alternating current from the exciting circuit to the exciting coil, an alternating magnetic field around the litz wire is generated around the electromagnetic induction portion 53. The greater the amount of current is, the greater the intensity of the generated alternating magnetic field.

  The magnetic core 54 is a columnar ferromagnet made of, for example, fired ferrite, ferrite resin, permalloy, or the like and having a circular cross section. These materials are oxides or alloy materials having a relatively high magnetic permeability. The magnetic core 54 induces a magnetic field line (magnetic flux) of an alternating magnetic field generated around the excitation coil of the electromagnetic induction unit 53, passes through the fixing belt 51 from the magnetic core 54, and returns to the magnetic core 54 (magnetic path). ). When the magnetic core 54 forms a magnetic path, the magnetic field lines of the AC magnetic field are concentrated on a portion of the fixing belt 51 facing the magnetic core 54. A shield (not shown) is provided outside the magnetic core 54 as viewed from the axis O1. This shield shields an alternating magnetic field and suppresses leakage to the outside.

  FIG. 3 is a view of the fixing unit 15 as viewed from the direction of arrow III in FIG. As shown in FIG. 3, the fixing unit 15 includes a plurality of magnetic cores 54 arranged at intervals in the x-axis direction. The magnetic cores 54 are not in contact with each other. This arrangement of the magnetic core 54 is for dispersing the magnetic flux passing through the magnetic core 54 in the x-axis direction. For example, when the magnetic core 54 is composed of a single plate member continuous in the x-axis direction, the magnetic flux passing through the magnetic core 54 is concentrated in the center, and the magnetic flux density penetrating the fixing belt 51 is the central portion in the x-axis direction. Will be biased to. In order to prevent this, a plurality of magnetic cores 54 are prepared and arranged at intervals in the x-axis direction so as not to contact each other. Note that the magnetic flux “penetrates” a layered member such as a belt means that the magnetic flux passes through in the thickness direction of these layered members.

  The fixing belt 51 is composed of a plurality of endless belt-shaped members as will be described later. When an alternating current is supplied to the exciting coil of the electromagnetic induction unit 53, a high-frequency alternating magnetic field is generated around the exciting coil 53, and a dielectric heat generating member included in the rotating fixing belt 51 generates heat by the high-frequency alternating magnetic field. The paper P in contact with the outer peripheral surface is heated. As a result, the electromagnetic induction unit 53 heats the medium via the fixing belt 51 with the amount of heat corresponding to the supplied electric power, and fixes the image transferred to the medium on the medium.

  FIG. 4 is an enlarged view showing a part of the fixing belt 51. The fixing belt 51 includes a base material layer 511, a conductive heat generation layer 512, an elastic layer 513, and a surface release layer 514. The base material layer 511 is formed of a heat-resistant sheet-like member, supports the conductive heat generating layer 512, and plays a role of ensuring the mechanical strength required for the entire fixing belt 51. The base material layer 511 is formed of a material and thickness having physical properties (relative magnetic permeability, specific resistance) that allow the alternating magnetic field to pass therethrough. The base material layer 511 does not generate heat due to the action of an alternating magnetic field or is less likely to generate heat than the conductive heat generation layer 512. The base material layer 511 is, for example, non-magnetic stainless steel having a thickness of 30 μm or more and 200 μm or less (desirably 50 μm or more and 150 μm or less, more desirably 100 μm or more and 150 μm or less), or nonmagnetic such as soft magnetic material (for example, permalloy, sendust, etc.). It is formed using a magnetic metal such as a metal or a hard magnetic material (Fe—Ni—Co, Fe—Cr—Co alloy, etc.), or a resin material such as a polyimide belt having a thickness of 50 μm to 200 μm.

  The conductive heat generating layer 512 is made of, for example, a nonmagnetic metal such as gold (Au), silver (Ag), aluminum (Al), or copper (Cu), or an alloy based on these, and has a thickness of 2 μm or more. It is formed to be 20 μm or less (preferably 5 μm or more and 10 μm or less). These materials are paramagnetic materials having a relative permeability of about 1 and a specific resistance of 2.7 × 10 −8 Ω · m or less. When the AC magnetic field generated by the electromagnetic induction portion 53 penetrates in the thickness direction of the conductive heat generating layer 512, electromagnetic induction occurs and eddy current flows inside the conductive heat generating layer 512. The conductive heat generating layer 512 generates heat by this eddy current. As described above, the conductive heat generating layer 512 generates heat by the alternating magnetic field generated by the electromagnetic induction unit 53.

  The elastic layer 513 is formed using a material such as silicone rubber, fluorine rubber, or fluorosilicone rubber that is deformed when pressure is applied and returns to its original shape when released from the pressure. For example, the elastic layer 513 is formed using a silicone rubber having a hardness of 10 ° to 30 ° (JIS-A) as a material so as to have a thickness of 100 μm to 600 μm. Since the image transferred onto the paper P by the secondary transfer roll 42 is formed by laminating each color toner as powder, there are fine protrusions and depressions. The elastic layer 513 is adapted to deform in accordance with the bulge or depression of this image. If the elastic layer 513 is not deformed in this way, the amount of heat supplied between the portion that contacts the fixing belt 51 and the portion that does not contact the fixing belt 51 in the image varies, and unevenness occurs in the degree to which the image is fixed. . This unevenness is reduced by the elastic layer 513 being deformed as described above.

  Since the surface release layer 514 is in direct contact with the image (toner) formed on the paper, it is desirable that the release property with respect to the toner is higher. The surface release layer 514 is, for example, PFA (Perfluoro alkoxy alkane), PTFE (polytetrafluoroethylene), a silicone copolymer, or the like as those having a relatively high release property with respect to the toner. The composite layer or the like is used as a material. Further, the smaller the thickness of the surface release layer 514, the shorter the period required until the layer becomes thin due to wear and cannot function as the release layer, that is, the life of the fixing belt 51 is shortened. On the other hand, as the thickness increases, the heat capacity of the fixing belt 51 increases, and the time required for heating the fixing belt 51 to a predetermined temperature increases. The surface release layer 514 is formed to have a thickness of 1 μm or more and 50 μm or less, assuming that these lifetimes and times are within a predetermined range.

  FIG. 5 is a view showing a support mechanism 60 of the fixing belt 51 according to the comparative example. The fixing belt 51 is supported by the support mechanism 60 at the end E1 on the side not driven by the drive unit. FIG. 5A is a view of the end E1 of the fixing belt 51 viewed from the radial direction of the fixing belt 51 (direction perpendicular to the axis O1). 5B is a view of the end E1 of the fixing belt 51 as viewed from the direction of the arrow IV in FIG. 5A. In FIG. 5, illustration of various members disposed on the inner peripheral side of the fixing belt 51 is omitted. The support mechanism 60 is a mechanism that supports the end E1 of the fixing belt 51 so that the fixing belt 51 rotates. In this example, the support mechanism 60 includes a belt holding member 601 and a support member 602. The belt holding member 601 is provided along the circumferential direction of the fixing belt 51 so as to contact the inner peripheral surface of the fixing belt 51. The belt holding member 601 is fixed to the support member 602, and when the fixing belt 51 rotates, the belt holding member 601 slides with the inner peripheral surface of the fixing belt 51. As shown in FIG. 5B, the belt holding member 601 has a joint J <b> 1 at a part of the fixing belt 51 in the circumferential direction. The support member 602 is a member that supports the end E1 of the fixing belt 51 from the inside via the belt holding member 601. The belt holding member 601 and the support member 602 are bonded by an adhesive (not shown), and the belt holding member 601 is fixed to the support member 602 so as not to rotate.

  Oil (an example of a lubricant) is applied to the inner peripheral surface of the fixing belt 51 in advance in order to reduce friction between the fixing belt 51 and the pressing pad 56 and to smoothly rotate the fixing belt 51. The oil applied to the inner peripheral surface of the fixing belt 51 gradually moves to the end of the fixing belt 51 as the fixing belt 51 is driven to rotate. In the support mechanism 60 shown in FIG. 5, the belt holding member 601 is in contact with the fixing belt 51 only on the inner peripheral surface. Therefore, due to the deformation of the fixing belt 51 accompanying the rotation of the fixing belt 51, a gap g1 (see FIG. 5B) is generated between the fixing belt 51 and the belt holding member 601, and oil flows from the gap g1 to the outside of the fixing belt 51. May leak. Further, in the support mechanism 60 shown in FIG. 5, since the belt holding member 601 has a joint J1 (a portion in which the material constituting the belt holding member 601 (PFA in this example) is joined), the belt holding member 601 passes through the joint J1. Oil may leak out of the fixing belt 51. As a result, the leaked oil adheres to the outer peripheral surface of the fixing belt 51, and the paper P may become dirty when the paper P is heated. Further, the inside of the image forming apparatus 1 may be contaminated by the leaked oil. In particular, in the fixing unit 15 including the contact / separation mechanism 59 described above, the fixing belt 51 is deformed when the pressure roll 52 and the fixing belt 51 come into contact with or separate from each other, and the gap g1 is further increased. The possibility of leaking outside is even higher.

  FIG. 6 is a view showing a support mechanism 61 for the fixing belt 51 according to an embodiment of the present invention. 6A and 6B are views of the end E1 of the fixing belt 51 viewed from the same direction as that of FIGS. 5A and 5B, respectively. The support mechanism 61 is a mechanism that supports the end E1 of the fixing belt 51 so that the fixing belt 51 rotates. In this example, the support mechanism 61 includes a belt holding member 611 and a support member 612. The support mechanism 61 includes a belt holding member 611 that covers the end E1 of the fixing belt 51 from the inside and the outside along the entire circumference, and the belt holding member 611 is a joint (a material constituting the belt holding member 611). The support mechanism 60 shown in FIG. 5 is different from the support mechanism 60 shown in FIG. The belt holding member 611 is previously formed into a continuous circular shape so as to eliminate the joint. The belt holding member 611 is an example of a covering member according to the present invention. The belt holding member 611 is fixed to the support member 612, and the belt holding member 611 slides on the outer peripheral surface and the inner peripheral surface of the fixing belt 51 when the fixing belt 51 rotates. The belt holding member 611 is a non-woven fabric made of a material such as fluorine resin such as PFA, and absorbs oil applied to the inner peripheral surface of the fixing belt 51. The support member 612 is a member that supports the end E1 of the fixing belt 51 from the inside via the belt holding member 611, like the support member 602 shown in FIG. The belt holding member 611 and the support member 612 are bonded with an adhesive (not shown), and the belt holding member 611 is fixed to the support member 612 so as not to rotate.

  As shown in FIG. 6, when the belt holding member 611 covers the end E1 of the fixing belt 51 from both the inside and the outside, the fixing belt 51 is less likely to be deformed than the configuration of FIG. A gap is less likely to occur between the holding member 611 and the holding member 611. Therefore, the oil applied to the inner peripheral surface of the fixing belt 51 is prevented from leaking to the outside as compared with the configuration of FIG. 5, and the paper P may be stained and the inside of the image forming apparatus 1 may be stained. Is reduced. Note that the position of the fixing belt 51 may shift in the x-axis direction when it is rotationally driven. In order to prevent the fixing belt 51 from separating from the belt holding member 611 due to the deviation in the x-axis direction, the belt holding member 611 has a length d1 (see FIG. 6A) in the x-axis direction of the region covering the fixing belt 51. It is desirable to exceed the maximum value d2 (see FIG. 6A) of the length that the fixing belt 51 moves in the x-axis direction.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. An example is shown below. In addition, you may combine each following aspect.

(1) The shape of the belt holding member is not limited to that described in the embodiment. The shape of the belt holding member may be any shape as long as the end E1 of the fixing belt 51 is covered from the inside and the outside. For example, in order to adjust the friction between the belt holding member and the fixing belt 51, unevenness may be provided in the region of the belt holding member that contacts the fixing belt 51. Further, the belt holding member does not necessarily have the same shape on the side contacting the inner peripheral surface of the fixing belt 51 and the side contacting the outer peripheral surface. When the length in the x-axis direction of the region covering the fixing belt 51 is different between the side contacting the inner peripheral surface of the fixing belt 51 and the side contacting the outer peripheral surface, the x of the region covering the fixing belt 51 It is desirable that the minimum value in the axial direction exceeds the maximum value d2 in which the fixing belt 51 moves in the x-axis direction.

  FIG. 7 is a view showing a support mechanism 62 of the fixing belt 51 according to a modification. FIG. 7 is a view of the end E1 of the fixing belt 51 viewed from the same direction as FIG. 5A. The support mechanism 62 includes a belt holding member 621 and a support member 612. In this example, the belt holding member 621 is provided with a convex portion H1 on the side in contact with the outer peripheral surface of the fixing belt 51, and the area in contact with the fixing belt 51 is smaller than that in the configuration of FIG. . The belt holding member 621 is fixed to the support member 612, and when the fixing belt 51 rotates, the belt holding member 621 slides with the outer peripheral surface and the inner peripheral surface of the fixing belt 51. At this time, the convex portion H <b> 1 of the belt holding member 621 slides with the outer peripheral surface of the fixing belt 51. When the outer peripheral surface of the fixing belt 51 comes into contact with the convex portion H <b> 1, a space S <b> 1 is formed between the belt holding member 621 and the outer peripheral surface of the fixing belt 51. This space S1 has a role of holding oil applied to the inner peripheral surface of the fixing belt 51. Even if the oil leaks to the outside of the fixing belt 51, the space S1 is compared with the configuration of FIG. Further, the possibility that the paper P is soiled and the possibility that the inside of the image forming apparatus 1 is soiled are reduced.

  The belt holding member may not be a non-woven fabric and may not absorb oil applied to the inner peripheral surface of the fixing belt 51. Also in this case, if the belt holding member covers the end E1 of the fixing belt 51 from the inside and the outside, the oil applied to the inner peripheral surface of the fixing belt 51 leaks to the outside as compared with the configuration of FIG. It is suppressed from taking out.

(2) The belt holding member may have a seam. Further, the belt holding member does not necessarily have to be an integrally molded member. The belt holding member may be formed by bonding a plurality of members. For example, a member that contacts the inner peripheral surface of the fixing belt 51 and a member that contacts the outer peripheral surface may be separately formed, and the belt holding member may be formed by bonding these members. Further, the belt holding member does not necessarily have to cover the entire circumference of the end portion of the fixing belt 51.

(3) The configurations of the image forming apparatus 1 and the fixing unit 15 are not limited to the configurations described in the embodiments. For example, the fixing unit 15 may not include the contact / separation mechanism 59. In another example, the heat storage plate 58 may not be in contact with the fixing belt 51. In still another example, a member for supplying oil to the inner peripheral surface of the fixing belt 51 may be disposed on the inner peripheral side of the fixing belt 51.

  The heat storage plate 58 may be disposed on the outer peripheral side of the fixing belt 51. In this case, the heat storage plate 58 includes a magnetic path forming member 581, a resin layer 582, and a heat capacity adjusting member 583 that are stacked in this order from the outer peripheral surface side of the fixing belt 51 in the radial direction (the direction away from the axis O 1). It only has to be. Further, the heat storage plate 58 may have a shape that is not curved. Further, the heat storage plate 58 may be configured without the heat capacity adjusting member 583.

  The image forming apparatus including the fixing unit 15 is not limited to the tandem type of the above-described embodiment, and may be another configuration such as a rotary type. The image forming apparatus provided with the fixing unit 15 is not limited to an image forming apparatus that forms an image by superimposing a plurality of color toner images, but is an image forming apparatus that forms a single color toner image. May be.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 11 ... Control part, 12 ... Memory | storage part, 13 ... Developing part, 14 ... Transfer part, 15 ... Fixing part, 16 ... Conveyance part, 17 ... Operation part, 18 ... Discharge port, 31 ... Photoconductor Drum, 32 ... charger, 33 ... exposure device, 34 ... developing device, 35 ... primary transfer roll, 36 ... drum cleaner, 41 ... intermediate transfer belt, 42 ... secondary transfer roll, 43 ... belt transport roll, 44 ... backup Roll, 49 ... Belt cleaner, 51 ... Fixing belt, 511 ... Base material layer, 512 ... Conductive heating layer, 513 ... Elastic layer, 514 ... Surface release layer, 53 ... Electromagnetic induction part, 54 ... Magnetic core, 58 ... Heat storage plate , 581 ... Magnetic path forming member, 582 ... Resin layer, 583 ... Heat capacity adjusting member, 59 ... Contact / separation mechanism, 60, 61, 62 ... Support mechanism, 601, 611, 621 ... Belt holding member, 602, 612 ... Support member

Claims (6)

A cylindrical belt having an inner surface coated with a lubricant and fixing an image on a recording medium by heat;
A heating unit that is disposed inside the belt and heats the belt;
A cover member that covers an end portion of the belt from the inside and the outside, and that slides with the belt when the belt is driven to rotate;
And a support member that fixes the cover member and supports an end portion of the belt from the inside through the cover member. The fixing device according to claim 1, wherein the covering member covers an end portion of the belt along the entire circumference of the belt. The length of the belt in the longitudinal direction of the region where the covering member covers the belt exceeds the maximum length of the belt moving in the longitudinal direction when driven in rotation. The fixing device according to 1 or 2. The fixing device according to claim 1, wherein the covering member is made of perfluoroalkoxyalkane. A rotating body that rotates while pressing the recording medium with the belt;
The fixing device according to claim 1, further comprising: a contact / separation mechanism that contacts or separates the belt and the rotating body. Image forming means for forming an unfixed image on a recording medium;
A cylindrical belt having an inner surface coated with a lubricant and fixing the image on the recording medium by heat;
A heating unit that is disposed inside the belt and heats the belt;
A cover member that covers an end portion of the belt from the inside and the outside, and that slides with the belt when the belt is driven to rotate;
An image forming apparatus comprising: a support member that fixes the cover member and supports an end portion of the belt from the inside through the cover member.

Images