JP2017167282A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that suppresses an increase in driving torque of a belt member compared with a case where a fixing device does not include a plate-like member that is arranged on the downstream side in the direction of rotation of the belt member with respect to a pressure member and scrapes off a lubricant applied to the belt member, and an image forming apparatus.SOLUTION: There is provided a fixing device 15 comprising: a rotatable pressure roll 52; a fixing belt 51 that rotates in contact with the pressure roll 52; a pressure pad 56 that is arranged on the inside of the fixing belt 51, and presses the fixing belt 51 toward the pressure roll 52 to form a nip area R1 through which a recording medium passes between the pressure roll 52 and the fixing belt 51; a lubricant that is applied to an inner peripheral surface of the fixing belt 51; and a plate-like member 60 that is in contact with the inner peripheral surface of the fixing belt 51 to scrape off the lubricant, where the plate-like member 60 is arranged on the downstream side in the direction of rotation of the fixing belt 51 with respect to the pressure pad 56.SELECTED DRAWING: Figure 2

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.

  For example, Patent Document 1 includes a belt member, a pressing member that presses the belt member, and a support member that supports the belt member, and a lubricant application that applies a lubricant to the inner surface of the belt member. A fixing device is disclosed in which a member is brought into contact with the inner surface of the belt member.

  For example, Patent Document 2 discloses a rotatable member that is rotatable, a belt member that is movable while being in contact with the rotatable member, and an inner side of the belt member. A pressing member that forms a nip portion through which a recording medium passes between the rotating member and the belt member by pressure contact, and a lubricant holding portion that is formed in a blade shape that holds the lubricant are disposed in the belt member. There is disclosed a fixing device that includes a lubricant application member that is arranged so that a blade tip portion of the lubricant holding portion abuts against a peripheral surface.

  For example, Patent Document 3 discloses that a belt member, a pressing member disposed so as to be in sliding contact with the inner peripheral surface of the belt member, and the belt member between the belt member by sandwiching the belt member between the pressing members. A backup member that forms a nip portion, and the pressing member is in sliding contact with the belt member, sandwiching the belt member with the backup member, and at least of the main body portion in the recording medium conveyance direction. A connecting portion extending from the upstream end toward the opposite side of the backup member, and a flange extending from the end of the connecting portion toward the upstream side in the transport direction, the connecting portion and the The flange portion is disclosed in a fixing device that forms a lubricant holding portion that holds the lubricant while facing the inner peripheral surface of the belt member.

  By the way, the use of the fixing device causes the lubricant interposed between the belt member and the pressing member to flow downstream in the rotation direction of the belt member, and the amount of lubricant interposed between the belt member and the pressing member is reduced. When it decreases, the driving torque of the rotating belt member may increase.

JP 2002-023534 A JP 2005-241765 A JP2012-233969A

  The object of the present invention is to increase the driving torque of the belt member as compared with the case where the plate member is disposed downstream of the pressing member in the rotation direction of the belt member and scrapes off the lubricant applied to the belt member. It is an object of the present invention to provide a fixing device and an image forming apparatus for suppressing the above-described problem.

  The invention according to claim 1 is a rotatable rotating member, a belt member that rotates while being in contact with the rotating member, and an inner side of the belt member that presses the belt member toward the rotating member. A pressing member that forms a nip portion through which a recording medium passes between the rotating member and the belt member, a lubricant applied to the inner peripheral surface of the belt member, and an inner peripheral surface of the belt member And a plate-like member that scrapes off the lubricant, and the plate-like member is a fixing device disposed downstream of the pressing member in the rotation direction of the belt member.

  The invention according to claim 2 is provided with a sliding member disposed between the pressing member and the belt member, and a direction in which the recording medium passes in the nip portion is substantially upward in the vertical direction, and the plate-like member The fixing device according to claim 1, wherein the fixing device is disposed in the vicinity of the pressing member, and the sliding member has a facing portion facing the plate-like member.

  According to a third aspect of the present invention, the facing portion of the sliding member is inclined toward the plate-like member, and a terminal portion of the facing portion is an end opposite to the belt member contact side of the plate-like member. The fixing device according to claim 2, wherein the fixing device protrudes from a perpendicular line extending from the vertical line to the opposing part.

  According to a fourth aspect of the present invention, there is provided an image carrier, a charging unit that charges the surface of the image carrier, a latent image forming unit that forms an electrostatic latent image on the charged surface of the image carrier, and 4. 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, the driving torque of the belt member as compared with the case where the belt member is disposed downstream of the pressing member in the rotational direction of the belt member and scrapes off the lubricant applied to the belt member. There is provided a fixing device in which the rise of the toner is suppressed.

  According to the invention which concerns on Claim 2, compared with the case where it does not have the plate-shaped member which is arrange | positioned in the rotation direction downstream of a belt member from a press member, and scrapes off the lubricant apply | coated to the belt member, A fixing device in which an increase in driving torque is further suppressed is provided.

  According to the third aspect of the present invention, the belt member is disposed on the downstream side of the pressing member in the rotation direction of the belt member and has no plate member that scrapes off the lubricant applied to the belt member. A fixing device in which an increase in driving torque is further suppressed is provided.

  According to the invention which concerns on Claim 4, it arrange | positions in the rotation direction downstream of a belt member from a press member, Compared with the case where it does not have a plate-shaped member which scrapes off the lubricant apply | coated to the belt member, An image forming apparatus including a fixing device that suppresses an increase in driving torque is provided.

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. 3 is an enlarged schematic cross-sectional view of the fixing device shown in FIG. 2. It is an expansion schematic cross section of a fixing device provided with a sliding member. It is an expansion schematic cross section of a fixing device provided with a sliding member. FIG. 3 is a schematic cross-sectional view in which a part of the fixing belt is enlarged.

  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. The image forming apparatus 1 illustrated in FIG. 1 includes a control unit 11, a storage unit 12, developing units 13Y, 13M, 13C, and 13K, a transfer unit 14, a fixing device 15, a conveyance unit 16, and an operation unit 17. It has. Note that the symbols Y, M, C, and K indicate configurations corresponding to yellow, magenta, cyan, and black toners, respectively. Each of the developing units 13Y, 13M, 13C, and 13K is different only in the toner used, and 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”.

  The control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and a computer program (hereinafter simply referred to as a program) in which the CPU is stored in the ROM or the storage unit 12. Are read and executed to control each unit of the image forming apparatus 1.

  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 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 conveyance part 16 has a container and a conveyance roll. The container accommodates a sheet P as a recording medium that has been cut into a predetermined size. Among the above-described sizes of the paper P, at least two different sizes are defined in the direction perpendicular to the transport direction, that is, in the width direction. Here, two types of paper P are used: a maximum width paper P1 and a narrow paper P2 that is narrower than the maximum width paper P1. The maximum width paper P1 is the paper having the maximum size in the width direction among the papers P handled by the image forming apparatus 1. These two types of paper P are distinguished by the control unit 11 depending on the container in which they are stored. The paper P accommodated in each container is taken out one by one by a transport roll according to 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, any recording medium may be used as long as it can record an image on the surface.

  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 drive 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, the image line of the electrostatic latent image. An image is formed (developed) on the photosensitive drum 31.

  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 image transfer, and removes 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 or the conveyance unit 16 conveys the paper P on which the image is transferred to the fixing device 15. The fixing device 15 fixes the image transferred onto the paper P by heating the paper P. The developing unit 13 and the transfer unit 14 are an example of an image forming unit that forms an image on a medium in the present invention.

  FIG. 2 is a schematic cross-sectional view illustrating an example of the configuration of the fixing device according to the present embodiment. Hereinafter, in order to explain the arrangement of the respective components of the fixing device 15, the space in which the respective components are arranged is represented as an xyz right-handed coordinate space. Also, among the coordinate symbols shown in the figure, a symbol in which a black circle is drawn in a circle with a white inside represents an arrow heading from the back side to the near 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. The y and z components are also defined as the y-axis direction, + y direction, -y direction, z-axis direction, + z direction, and -z direction. Further, when passing through the fixing device 15, the paper 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.

  2 includes a pressure roll 52 as an example of a rotating member, a fixing belt 51 as an example of a belt member that rotates while contacting the rotating member, an electromagnetic induction unit 53, a magnetic core 54, A pressing pad 56 as an example of a pressing member, a holder 57, a heat transfer portion 58, a shielding member 59, a lubricant applied to the inner surface of the fixing belt 51, and a plate-like member 60 that scrapes off the lubricant. I have.

  The pressure roll 52 shown in FIG. 2 includes a metal cylindrical core material 521 and an elastic layer 522 provided on the surface of the core material 521. 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 fixing belt 51 shown in FIG. 2 is connected to a rotation mechanism such as a drive motor (not shown), and rotates in the direction of an arrow D51 around an axis O1 parallel to the x-axis direction. The pressure roll 52 receives a driving force from the rotating fixing belt 51 and rotates the sheet P conveyed by the conveying unit 16 while rotating in the arrow D52 direction around the axis O2 parallel to the x-axis direction. Press against the fixing belt 51. When the paper P passes through the nip region R1 formed between the fixing belt 51 and the pressure roll 52, the pressure acting on the nip region R1, the heat supplied from the fixing belt 51, and the like are changed. In addition, the unfixed toner image is fixed on the paper P and discharged from the fixing device 15.

  The pressing pad 56, the holder 57, and the heat transfer unit 58 are disposed on the inner peripheral side of the fixing belt 51. The holder 57 includes a frame 571, a support member 572, a fixing member 573, and an elastic member 574. The frame 571 is a member extending in the x-axis direction, and supports the pressing pad 56 in the direction of arrow D56 (-y direction) shown in FIG. 2, that is, the direction in which the pressure roll 52 is disposed. The frame 571 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). However, in the configuration in which the shielding member 59 is provided as in this embodiment, an iron-based member having high rigidity may be used.

  The shielding member 59 shown in FIG. 2 is disposed between the electromagnetic induction portion 53 and the frame 571, and suppresses leakage of a magnetic path generated from the electromagnetic induction portion 53 to the frame 571 side. As shown in FIG. 2, one end portion 591 of the shielding member 59 is fixed by a fixing member 573 attached to the frame 571. In addition, among the end portions of the heat transfer portion 58, the end portion on the upstream side in the rotation direction of the fixing belt 51 is also fixed by the fixing member 573. The other end portion 592 of the shielding member 59 is coupled to the end portion on the downstream side in the rotation direction among the end portions of the heat transfer section 58. The elastic member 574 is disposed between the end 592 of the shielding member 59 and the support member 572 attached to the frame 571.

  The pressing pad 56 shown in FIG. 2 is supported by the frame 571 of the holder 57 at a position facing the pressing roll 52. The pressure pad 56 is disposed in a state of being pressed against the pressure roll 52 via the fixing belt 51, and presses the fixing belt 51 from the inner peripheral surface side toward the direction of the pressure roll 52 (−y direction). As a result, a nip region R1 through which the paper P passes is formed between the fixing belt 51 and the pressure roll 52. Examples of the material of the pressing pad 56 include resin materials such as PES resin (polyethersulfone) and PPS resin (polyphenylene sulfide), and metals such as iron and aluminum. As will be described later, a sliding member may be provided between the pressing pad 56 and the fixing belt 51.

  2 includes a temperature sensitive layer 581, a diffusion layer 582, and a heat storage layer 583. The heat transfer section 58 is urged in the radial direction around the axis O1 by a support mechanism including the holder 57 and the shielding member 59, whereby the contact state with the inner peripheral surface of the fixing belt 51 is maintained. Yes. In this embodiment, a fixing device in which the heat transfer portion 58 is in contact with the inner peripheral surface of the fixing belt 51 will be described as an example. However, the heat transfer portion 58 does not contact the inner peripheral surface of the fixing belt 51 and is determined in advance. The fixing device may be arranged with an interval of a specified size (for example, 0.5 mm or more and 1.5 mm or less).

  The temperature-sensitive layer 581 shown in FIG. 2 is a layer containing a metal material having a Curie point, and is, for example, a Ni—Fe-based or Ni—Cr—Fe-based magnetic shunt alloy. This Curie point is preferably in the range of not less than the set temperature of the fixing belt 51 and not more than the heat resistance temperature of the fixing belt 51. Specifically, for example, it is preferably 170 ° C. or more and 250 ° C. or less, more preferably 190. It is at least 230 ° C.

  The temperature sensitive layer 581 shown in FIG. 2 is formed in an arc shape along the inner peripheral surface of the fixing belt 51 and extends in the x-axis direction. The temperature-sensitive layer 581 is disposed in contact with the inner peripheral surface of the fixing belt 51 and is opposed to the electromagnetic induction portion 53 via the fixing belt 51. The temperature sensitive layer 581 generates heat by being electromagnetically induced by the action of an alternating magnetic field generated from the electromagnetic induction portion 53, and transfers heat to the fixing belt 51. The thickness of the temperature sensitive layer 581 is, for example, not less than 0.05 mm and not more than 1.0 mm, desirably not less than 0.3 mm and not more than 0.6 mm.

  The diffusion layer 582 shown in FIG. 2 is a layer containing a carbon material such as graphite or carbon fiber. The diffusion layer 582 is formed in an arc shape along the inner peripheral surface of the temperature-sensitive layer 581, and is disposed on the inner peripheral surface of the temperature-sensitive layer 581. The diffusion layer 582 mediates heat transfer between the temperature-sensitive layer 581 and the heat storage layer 583, for example, and preferably has higher thermal conductivity than the temperature-sensitive layer 581 and the heat storage layer 583.

  The heat storage layer 583 shown in FIG. 2 is a layer made of a nonmagnetic material such as aluminum (Al), for example. The heat storage layer 583 is formed in an arc shape along the inner peripheral surface of the diffusion layer 582 and is disposed on the inner peripheral surface of the diffusion layer 582. The heat storage layer 583 stores, for example, heat generated in the fixing belt 51 and the temperature sensitive layer 581, and preferably has a larger heat capacity than the fixing belt 51 and the diffusion layer 582.

  The elastic member 574 is not particularly limited, and examples thereof include a leaf spring and a coil spring. Further, the attachment position of the elastic member 574 is not particularly limited as long as the temperature sensitive layer 581 and the like can be pressed against the fixing belt 51.

  In this embodiment, one end portion 591 of the shielding member 59 is fixed. However, in this embodiment, the present invention is not limited to fixing by adhesion, welding, screwing, or the like. This includes the case of fixing with a degree of freedom.

  Examples of the lubricant applied to the inner peripheral surface of the fixing belt 51 include silicone oil, paraffin oil, fluorine oil, and other synthetic lubricating oil grease in which a solid substance and a liquid are mixed, wax, and the like. In the fixing process, for example, the frictional force between the rotating fixing belt 51 and the pressing pad 56 is alleviated by the lubricant applied to the inner peripheral surface of the fixing belt 51.

  FIG. 3 is an enlarged schematic cross-sectional view of the fixing device shown in FIG. As shown in FIGS. 2 and 3, the plate-like member 60 that scrapes off the lubricant is in contact with the inner peripheral surface of the fixing belt 51. Further, the plate-like member 60 is disposed on the downstream side in the rotation direction of the fixing belt 51 with respect to the pressing pad 56. The plate member 60 is preferably a flat plate (flat and uncurved plate) extending in the x-axis direction, but is not limited to this, for example, a curved plate or having a thickness of It may be a plate that is not constant. The plate-like member 60 is configured by, for example, a sheet or blade formed of a resin such as a fluororesin, silicone rubber, silicone rubber coated with a fluororesin, or the like. Examples of the blade include those obtained by bending the sheet into a U shape. The length of the plate member 60 in the x-axis direction is preferably, for example, the same as the length of the nip region R1 in the x-axis direction or shorter than the length of the nip region R1 in the x-axis direction by 1 mm or more. The plate-like member 60 is fixed to, for example, a support member (not shown) that supports both ends of the pressing belt 56, the frame 571, or the fixing belt 51 in the x-axis direction via a fixing member (not shown). .

  By the way, when the fixing device 15 is used for a long time, the lubricant applied to the inner peripheral surface of the fixing belt 51 is reduced, the frictional force between the fixing belt 51 and the pressing pad 56 is increased, and the fixing belt 51 is driven. Torque may increase. In this embodiment, when the lubricant interposed between the fixing belt 51 and the pressing pad 56 flows downstream in the rotation direction of the fixing belt 51, the lubricant is scraped off by the plate-like member 60. The scraped lubricant falls, for example, from the plate-like member 60 and flows between the fixing belt 51 and the pressing pad 56, and the decrease in the amount of lubricant between the fixing belt 51 and the pressing pad 56 is suppressed. It is thought that it is done. Further, when the fixing device 15 is stopped, the lubricant scraped off by the plate-like member 60 flows, for example, between the fixing belt 51 and the pressing pad 56 along the inner peripheral surface of the fixing belt 51. It is considered that a decrease in the amount of lubricant between the fixing belt 51 and the pressing pad 56 is suppressed, and an increase in driving torque of the fixing belt 51 is suppressed. As a result, it is considered that, for example, paper wrinkles and image misalignment are suppressed.

  The plate-like member 60 is preferably disposed on the downstream side of the pressing pad 56 in the rotation direction of the fixing belt 51 and in the vicinity of the pressing pad 56. Here, the vicinity means that the distance between the plate-like member 60 and the pressing pad 56 is within 11.65 mm of the belt circumference. Thus, by arranging the plate-like member 60 in the vicinity of the press pad 56, the plate-like member is compared with the case where the distance between the plate-like member 60 and the press pad 56 exceeds 11.65 mm in terms of circumference. It is considered that the lubricant scraped off at 60 can easily enter between the fixing belt 51 and the pressing pad 56.

  The effect of suppressing the driving torque increase of the fixing belt 51 by the plate-like member 60 is not limited to the fixing device in which the passage direction of the paper P in the nip region R1 is set substantially upward in the vertical direction. It is considered that the same effect can be obtained even in a fixing device set in a substantially horizontal direction. Note that “substantially vertical” means not only a vertical state but also a state inclined to 3 ° from the vertical, and “substantially horizontal” means not only a horizontal state but also a state inclined to 3 ° from the horizontal. Yes.

  In the following, a preferred embodiment of the fixing device in which the paper P passing direction in the nip region R1 is set substantially upward in the vertical direction will be described.

  FIG. 4 is an enlarged schematic cross-sectional view of a fixing device including a sliding member. The fixing device 15 illustrated in FIG. 4 includes a sliding member 61 provided between the fixing belt 51 and the pressing pad 56. The sliding member 61 reduces the frictional resistance between the fixing belt 51 and the pressing pad 56, and is preferably made of, for example, a material having a smaller friction coefficient than that of the pressing pad 56. More preferably, it is made of a wearable material. Examples of the sliding member 61 include resin sheets such as thermosetting polyimide, thermoplastic polyimide, polyamide, polyamideimide, silicone elastomer (silicone resin), fluororesin, and fluorine-containing elastomer. In addition to the above, as the sliding member 61, for example, a composite resin sheet in which a porous resin fiber cloth such as a fluororesin is used as a base layer and a surface of the base layer on the side of the pressing pad 56 is covered with a polyethylene terephthalate resin layer. Sintered molded polytetrafluoroethylene resin sheet, glass fiber sheet impregnated with Teflon (registered trademark), and the like.

  Both ends of the sliding member 61 shown in FIG. 4 (both ends in the rotation direction of the fixing belt 51) are fixed to the side surfaces of the pressing pad 56, and of the both ends, the downstream of the fixing belt 51 in the rotation direction. The end portion is a facing portion 62 that faces the plate-like member 60 disposed in the vicinity of the pressing pad 56.

  In this way, by providing the facing portion 62 that faces the plate-like member 60, the lubricant that has dropped from the plate-like member 60 is received by the facing portion 62 and travels along the facing portion 62 to the fixing belt 51 and the sliding member. Therefore, the decrease in the amount of lubricant between the fixing belt 51 and the sliding member 61 is further suppressed, and the driving torque of the fixing belt 51 is increased compared with the case where the facing portion 62 is not provided. It is thought that it can be suppressed more.

  FIG. 5 is an enlarged schematic cross-sectional view of a fixing device including a sliding member. In the fixing device 15 shown in FIG. 5, the opposing portion 62 of the sliding member 61 is disposed along the inclined surface of the overhang portion 56 a provided on the side surface of the pressing pad 56, and is a plate disposed in the vicinity of the pressing pad 56. It inclines to the shape member 60 side. The terminal portion 62a of the facing portion 62 protrudes from a perpendicular line (broken line P shown in FIG. 5) extending from the end portion 60a of the plate-like member 60 on the side opposite to the fixing belt contact side to the facing portion 62. The inclination angle of the facing portion 62 is not particularly limited as long as the terminal portion 62a of the facing portion 62 is set so as to protrude beyond the perpendicular line P shown in FIG. Further, the end portion 62 a of the facing portion 62 may be disposed on the end portion 60 a of the plate-like member 60. Note that the pressing pad 56 and the overhanging portion 56a may be integrally molded or may be separately molded.

  In this way, by inclining the facing portion 62 of the sliding member 61 toward the plate-like member 60, the lubricant travels through the facing portion 62 and the fixing belt 51 compared to the case where the facing portion 62 is not tilted. It is thought that it becomes easy to flow between and the sliding member 61. Further, by causing the end portion 62a of the facing portion 62 of the sliding member 61 to protrude from the end portion 60a of the plate-like member 60, the plate-like member is compared with the case where the end portion 62a of the facing portion 62 does not protrude. It is considered that the lubricant dropped from 60 can be easily received by the facing portion 62. From these facts, it is considered that a decrease in the amount of lubricant between the fixing belt 51 and the pressing pad 56 is further suppressed, and an increase in driving torque of the fixing belt 51 is further suppressed.

  The electromagnetic induction unit 53 shown in FIG. 2 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. The exciting coil is, for example, a coil formed by winding litz wires, which are bundles of mutually insulated copper wires, 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 electromagnetic induction unit 53 is an example of a magnetic field generating unit in the present embodiment.

  The magnetic core 54 shown in FIG. 2 is an arc-shaped ferromagnetic body made of, for example, sintered ferrite, ferrite resin, permalloy or the like. 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.

  The fixing belt 51 of the present embodiment is constituted by, for example, an endless belt member whose original shape is a cylindrical shape. When an alternating current is supplied to the exciting coil of the electromagnetic induction portion 53, a high-frequency alternating magnetic field is generated around the exciting coil 53, and this member acts on a member included in the rotating fixing belt 51 to generate heat, and the outer periphery of the fixing belt 51 The sheet P in contact with the surface is heated. As a result, the electromagnetic induction unit 53 heats the paper P via the fixing belt 51 with the amount of heat corresponding to the supplied power, and fixes the image transferred onto the paper P.

  FIG. 6 is an enlarged schematic cross-sectional view of a part of the fixing belt. The fixing belt 51 includes a base material layer 511, a heat generation layer 512, an elastic layer 513, and a surface release layer 514.

  The base material layer 511 is formed of a material and thickness having physical properties (relative magnetic permeability, specific resistance) that allow an 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 heat generation layer 512. The base material layer 511 is, for example, nonmagnetic 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), soft magnetic material (for example, Permalloy, Sendust (registered trademark), etc.) Or a nonmagnetic metal such as a hard magnetic material (Fe—Ni—Co or Fe—Cr—Co alloy) or a resin material such as a polyimide belt having a thickness of 50 μm to 200 μm.

The heat generating layer 512 is a layer that generates heat by electromagnetic induction of an alternating magnetic field generated by the electromagnetic induction unit 53. When an alternating magnetic field from the electromagnetic induction portion 53 penetrates in the thickness direction of the heat generating layer 512, electromagnetic induction occurs and an eddy current flows inside the heat generating layer 512. The heat generating layer 512 generates heat when the eddy current flows. The heating of the fixing belt 51 having the heat generating layer 512 by electromagnetic induction in an alternating magnetic field in this way, that is, heating, is referred to as “electromagnetic induction heating”. Examples of the material constituting the heat generating layer 512 include nonmagnetic metals such as gold (Au), silver (Ag), aluminum (Al), and copper (Cu), and metal alloys thereof. The thickness of the heat generating layer 512 is, for example, preferably in the range of 2 μm to 20 μm, and more preferably in the range of 5 μm to 10 μm. The specific resistance of the heat generating layer 512 is preferably, for example, 2.7 × 10 ⁻⁸ Ω · m or less.

  The material of the elastic layer 513 is preferably, for example, a fluororesin, a silicone resin, a silicone rubber, or a fluororubber from the viewpoints of heat resistance, thermal conductivity, insulation, and the like. The thickness of the elastic layer 513 is preferably in the range of 100 μm to 600 μm, for example. The material of the surface release layer 514 is, for example, a fluororesin such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) from the viewpoint of releasability and heat resistance. Etc. Further, the thickness of the surface release layer 514 is preferably in the range of 1 μm to 50 μm, for example.

  Below, the effect | action of the temperature sensitive layer 581 in the temperature below a Curie point and the temperature more than a Curie point is demonstrated. Since the temperature-sensitive layer 581 is a ferromagnetic material at a temperature below the Curie point, the AC magnetic field generated by the electromagnetic induction unit 53 passes through the fixing belt 51 and passes through the inside along the shape of the temperature-sensitive layer 581. Then, a magnetic path returning to the electromagnetic induction portion 53 is formed. Due to the magnetic path thus formed, the magnetic flux density penetrating the fixing belt 51 is increased, and the amount of heat generated by the heating belt 51 is also increased. On the other hand, since the temperature-sensitive layer 581 is a non-magnetic material at a temperature equal to or higher than the Curie point, the alternating magnetic field generated in the electromagnetic induction unit 53 and penetrating the fixing belt 51 penetrates the temperature-sensitive layer 581 and becomes a diffusion layer A magnetic path reaching 582, the heat storage layer 583, or the shielding member 59 is formed. In this case, the magnetic flux density transmitted through the fixing belt 51 is lower than that at a temperature lower than the Curie point, so the amount of heat generated by the fixing belt 51 is also reduced.

  Although the above is description of this embodiment, this embodiment is not restrict | limited to the example mentioned above, For example, it can deform | transform as follows.

  In the fixing device of this 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. However, the rotating member and the belt member are described. However, 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.

  In the fixing device of the present embodiment, the fixing belt is heated by electromagnetic induction. However, heating of the fixing belt is not limited to this, and the fixing belt may be heated using a heating source such as a halogen lamp. Good. Further, in the fixing device of the present embodiment, the heat transfer portion including the temperature sensitive layer, the heat storage layer, and the diffusion layer has been described as an example. However, in electromagnetic induction heating, at least the heat transfer portion including the temperature sensitive layer may be used. That's fine.

  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 1 μm electroless nickel layer, a 10 μm electrolytic copper layer, and a 9 μm electrolytic nickel layer are laminated on a polyimide substrate having an outer diameter of 30.5 mm and a thickness of 62 μm is provided. On the heat generating layer, a thickness of 200 μm is provided. An elastic layer composed of liquid cured silicone rubber (rubber hardness 33 degrees: JIS-A) is provided, and a mold release composed of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer tube having a thickness of 30 μm is provided on the elastic layer. The coated layer was used as a fixing belt. An adhesive layer made of a silane coupling agent was provided between the heat generating layer and the elastic 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.

<Lubricant>
Silicon oil was used as a lubricant applied to the inner peripheral surface of the fixing belt.

<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.

<Heat transfer part>
An arc-shaped (thickness 0.3 mm) iron-nickel alloy plate along the inner peripheral surface of the fixing belt was used as the temperature sensitive layer. An arc-shaped (thickness 0.1 mm) carbon fiber layer along the inner peripheral surface of the temperature-sensitive layer was used as the diffusion layer. Moreover, the aluminum plate of the circular arc shape (thickness 0.3mm) along the internal peripheral surface of a diffusion layer was used as a thermal storage layer.

<Pressing pad>
A material in which 40% glass fiber was blended with PPS was molded to a width of 7 mm corresponding to the NIP width was used as a pressure pad. A pressure pad was installed on the inner peripheral surface of the fixing belt, and a total load of 35 kgf was applied to the pressure roll through the fixing belt to form an NIP portion.

<Sliding sheet>
A 110 μm thick PTFE resin sheet was used as a sliding sheet. The sliding sheet was arranged as shown in FIG.

<Plate-shaped member>
A blade made of silicone rubber (thickness 3 mm, length in the x-axis direction (length in the longitudinal direction) 355 mm, width (length in the short direction) 3 mm) was used as the plate member. The plate-like member was arranged on the downstream side in the rotation direction of the fixing belt from the pressing pad with an interval of 8 mm, and the end of the plate-like member was brought into contact with the inner peripheral surface of the fixing belt.

(Comparative example)
The fixing device of the comparative example is the same as the embodiment except that the plate-like member is not installed.

<Evaluation of driving torque>
The fixing devices of the examples and comparative examples are operated, and at each rotation speed of the fixing belt (121 mm / s to 308 mm / s), before outputting plain paper, after outputting 200,000 plain papers, 40 plain papers are output. The driving torque of the fixing belt after outputting 10,000 sheets was measured. The driving torque is a value measured by a torque measuring device (TORQUE DETECTOR: manufactured by ONO SOKKI Co. LTD) installed on the shaft that rotates the fixing belt. The results of the examples are summarized in Table 1, and the results of the comparative examples are summarized in Table 2.

  In the fixing device of the example in which the plate-like member was installed, the difference in driving torque before and after the output of the plain paper was small compared to the fixing device of the comparative example in which the plate-like member was not installed. . That is, it can be said that the fixing device of the example in which the plate-like member is installed has suppressed the increase in the driving torque of the fixing belt as compared with the fixing device of the comparative example in which no plate-like member is installed.

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 11 Control part, 12 Storage part, 13, 13Y, 13M, 13C, 13K Developing part, 14 Transfer part, 15 Fixing apparatus, 16 Conveying part, 17 Operation part, 31 Photosensitive drum, 32 Charger, 33 Exposure device, 34 Developer, 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, 52 Pressure roll, 53 Electromagnetic induction part, 54 Magnetic core, 56 Press pad, 56a Overhang part, 57 Holder, 58 Heat transfer part, 59 Shielding member, 60 Plate member, 61 Sliding member, 62 Opposing part, 511 Base layer, 512 Heat generation Layer, 513 elastic layer, 514 surface release layer, 521 core material, 522 elastic layer, 571 frame, 572 support Wood, 573 fixing member, 574 an elastic member, 581 temperature sensitive layer, 582 the diffusion layer, 583 a heat storage layer.

Claims (4)

A rotatable rotating member;
A belt member that rotates while contacting the rotating member;
A pressing member that is disposed inside the belt member and presses the belt member toward the rotating member to form a nip portion through which a recording medium passes between the rotating member and the belt member;
A lubricant applied to the inner peripheral surface of the belt member;
A plate-like member that contacts the inner peripheral surface of the belt member and scrapes off the lubricant;
The fixing device according to claim 1, wherein the plate-like member is disposed downstream of the pressing member in the rotation direction of the belt member. A sliding member disposed between the pressing member and the belt member;
The passing direction of the recording medium in the nip portion is substantially upward in the vertical direction,
The plate-like member is disposed in the vicinity of the pressing member,
The fixing device according to claim 1, wherein the sliding member has a facing portion facing the plate-like member.   The opposed portion of the sliding member is inclined toward the plate-like member, and a terminal portion of the opposed portion is a perpendicular line extending from the end opposite to the belt member contact side of the plate-like member to the opposed portion. The fixing device according to claim 2, wherein the fixing device protrudes further.   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. The developing unit that develops and forms a toner image, the transfer unit that transfers the toner image to a recording medium, and the fixing device according to claim 1 that fixes the toner image on the recording medium. An image forming apparatus comprising: