JP5544852B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

2. Description of the Related Art As a fixing device used in an image forming apparatus such as a copying machine or a printer, a fixing device including a heating member configured by a belt member (fixing belt) stretched by a plurality of rolls is known.
For example, Patent Document 1 includes a fixing belt stretched between a fixing roller and a heating roller, and a pressure roller that contacts the outer peripheral surface of the fixing belt and forms a nip with the fixing belt. Fixing provided with a fixing member having a shape with a large curvature at the exit separation surface inside the fixing belt at a position corresponding to the exit separation portion of the nip formed by the fixing roller and the pressure roller via the belt An apparatus is described.

Japanese Patent Laid-Open No. 2003-5565

  An object of the present invention is to suppress wear of a belt member or a fixing member that may come into contact with the plate member when the belt member is supported from the inside using the plate member.

According to a first aspect of the present invention, there is provided a belt member that can be circulated, a first fixing member that is disposed inside the belt member, and the first fixing member via the belt member. A second fixing member that is pressed and formed between the belt member and a passage portion through which the recording material passes; and a downstream side of the belt member in the moving direction of the belt member and the belt member. An opposing surface disposed on the inner side and surrounded by a plurality of sides including the side located on the side on which the first fixing member is disposed, and opposed to the inner circumferential surface of the belt member, A pressing member that presses the belt member toward the second fixing member by using an opposing surface; and provided between the opposing surface and the inner peripheral surface of the belt member. 1 on the side where the fixing member is located A first surface on the inner peripheral surface side of the belt member, and a second surface opposite to the first surface. And a plate-like member having an end surface connecting the first surface and the second surface at the tip end in the protruding direction, and the plate-like member and the inner peripheral surface of the belt member. A sheet-like member, and a first corner formed by the first surface and the end surface of the plate-like member, and a second corner formed by the second surface and the end surface. Fixing is characterized in that at least one of the corner portions is chamfered, and the sheet-like member is provided so as to protrude toward the first fixing member from the tip portion of the plate-like member. Device.
According to a second aspect of the present invention, there is provided a belt member provided so as to be capable of circulating movement, a first fixing member disposed inside the belt member, and the first fixing member via the belt member. A second fixing member that is pressed and formed between the belt member and a passage portion through which the recording material passes; and a downstream side of the belt member in the moving direction of the belt member and the belt member. An opposing surface disposed on the inner side and surrounded by a plurality of sides including the side located on the side on which the first fixing member is disposed, and opposed to the inner circumferential surface of the belt member, A pressing member that presses the belt member toward the second fixing member by using an opposing surface; and provided between the opposing surface and the inner peripheral surface of the belt member. 1 on the side where the fixing member is located A first surface on the inner peripheral surface side of the belt member, and a second surface opposite to the first surface. And a plate-like member having an end surface connecting the first surface and the second surface at the distal end in the protruding direction, and formed by the first surface and the end surface of the plate-like member Chamfering is performed on at least one of the first corner portion and the second corner portion formed by the second surface and the end surface, and the plate-like member has a width of the belt member. The tip portion of the plate-like member is provided along the width direction of the belt member, and the center portion in the longitudinal direction of the plate-like member is directed toward the end portion in the longitudinal direction. It is formed so as to be separated from the first fixing member. A fixing device according to claim.

According to a third aspect of the present invention, an image forming unit that forms an image on a recording material, and a fixing unit that fixes the image on a recording material on which an image is formed by the image forming unit, the fixing unit includes: A belt member provided so as to be able to circulate; a first fixing member disposed inside the belt member; and being pressed against the first fixing member via the belt member, the image forming means A second fixing member that forms a passage portion through which the recording material on which an image is formed passes between the belt member and the belt member, and further on the downstream side in the moving direction of the belt member than the first fixing member. An opposing surface disposed inside the member and surrounded by a plurality of sides including the side located on the side where the first fixing member is arranged, and opposed to the inner peripheral surface of the belt member. , Using the facing surface A pressing member that presses the belt member toward the second fixing member, and the first fixing member of the pressing member is disposed between the opposing surface and the inner peripheral surface of the belt member. A first surface on the inner peripheral surface side of the belt member on the side opposite to the first surface. A plate-shaped member having a second surface and having an end surface connecting the first surface and the second surface at a distal end in the protruding direction; the plate-shaped member; and the inner peripheral surface of the belt member; A sheet-like member disposed between, a first corner formed by the first surface and the end surface of the plate-like member, and the second surface and the end surface At least one of the second corners to be formed is chamfered, and the sheet Member is an image forming apparatus, characterized in that it protrudes into the first fixing member side than the distal end portion of the plate-like member.
According to a fourth aspect of the present invention, there is provided image forming means for forming an image on a recording material, and fixing means for fixing the image on a recording material on which an image has been formed by the image forming means. A belt member provided so as to be able to circulate; a first fixing member disposed inside the belt member; and being pressed against the first fixing member via the belt member, the image forming means A second fixing member that forms a passage portion through which the recording material on which an image is formed passes between the belt member and the belt member, and further on the downstream side in the moving direction of the belt member than the first fixing member. An opposing surface disposed inside the member and surrounded by a plurality of sides including the side located on the side where the first fixing member is arranged, and opposed to the inner peripheral surface of the belt member. , Using the facing surface A pressing member that presses the belt member toward the second fixing member, and the first fixing member of the pressing member is disposed between the opposing surface and the inner peripheral surface of the belt member. A first surface on the inner peripheral surface side of the belt member on the side opposite to the first surface. A plate-like member having a second surface and having an end surface connecting the first surface and the second surface at a distal end portion in the protruding direction, and the first surface of the plate-like member, Chamfering is applied to at least one of the first corner formed by the end face and the second corner formed by the second face and the end face, and the plate-like member is Provided along the width direction of the belt member, the tip of the plate-like member, It is provided along the width direction of the belt member, and is formed so as to be separated from the first fixing member as it goes from the center portion in the longitudinal direction of the plate member to the end portion in the longitudinal direction. The image forming apparatus.

According to the first aspect of the present invention, it is possible to suppress wear of the belt member and wear of the first fixing member that may come into contact with the plate-like member as compared with the case where the present invention is not adopted.
According to the second aspect of the present invention, it is possible to suppress the wear of the belt member and the wear of the first fixing member that may come into contact with the plate-like member as compared with the case where the present invention is not adopted. Compared with the case where no is used, it is possible to suppress image disturbance caused by vaporization of water contained in the recording material.
According to the third aspect of the present invention, it is possible to suppress the wear of the belt member and the wear of the first fixing member that may come into contact with the plate-like member as compared with the case where the present invention is not adopted.
According to the invention of claim 4 , it is possible to suppress the wear of the belt member and the wear of the first fixing member which may come into contact with the plate-like member as compared with the case where the present invention is not adopted. Compared with the case where no is used, it is possible to suppress image disturbance caused by vaporization of water contained in the recording material.

1 is a diagram illustrating a configuration example of an image forming apparatus according to an exemplary embodiment. FIG. 3 is a cross-sectional configuration diagram for describing a configuration of a fixing unit of the present embodiment. It is a figure for demonstrating a nip part. It is a figure for demonstrating a peeling pad, a pressurization roll, and a fixing roll. It is a perspective view at the time of seeing a peeling pad from the downward direction. It is a figure for demonstrating the pressure distribution in a nip part. It is the figure which expanded and showed the 1st opposing part of the plate-shaped member.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
<Description of Image Forming Apparatus>
FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus 1 according to the present embodiment. An image forming apparatus 1 shown in FIG. 1 is a so-called “tandem type” color printer, and controls the operation of an image forming unit 10 as an example of an image forming unit that forms an image based on image data, and the entire image forming apparatus 1. And, for example, a main control unit 50 that performs communication with a personal computer (PC), image processing performed on image data, and the like, and a user interface (UI) that receives operation input from the user and displays various information to the user ) Part 90.

<Description of Image Forming Unit>
The image forming unit 10 is a functional unit that forms an image by, for example, electrophotography, and includes six image forming units 11C, 11M, 11HC, 11HM, 11Y, and 11K (hereinafter referred to as “image forming units”) arranged in parallel. 11 "). Each image forming unit 11 functions as a functional member, for example, a photosensitive drum 12 on which an electrostatic latent image is formed and then each color toner image is formed, and the surface of the photosensitive drum 12 is charged with a predetermined potential A charger 13 that exposes the photosensitive drum 12 charged by the charger 13 based on image data, and development that develops the electrostatic latent image formed on the photosensitive drum 12 with toner of each color. And a cleaner 16 for cleaning the surface of the photosensitive drum 12 after transfer.
Each developing unit 15 of each image forming unit 11 is connected to toner containers 17C, 17M, 17HC, 17HM, 17Y, and 17K (hereinafter referred to as “toner containers 17”) for storing toners of respective colors by toner transport paths (not shown). ing. Each color toner is supplied from the toner container 17 to the developing device 15 by a supply screw (not shown) provided in the toner conveyance path.

  Each of the image forming units 11 is configured in substantially the same manner except for the toner accommodated in the developing unit 15, and each of them is C (cyan) color, M (magenta) color, HC (high chroma cyan) color, and HM (high chroma magenta). ), Y (yellow) and K (black) toner images are formed. The HC color here is a cyan color having a cyan hue, a hue that is brighter and higher in saturation than the C color, and the HM color has a magenta hue, and M color. It is a magenta color with a brighter color tone and a relatively high saturation.

  The image forming unit 10 intermediates the intermediate transfer belt 20 to which the respective color toner images formed on the photosensitive drums 12 of the respective image forming units 11 are transferred and the respective color toner images formed by the respective image forming units 11. A primary transfer roll 21 for transferring (primary transfer) to the transfer belt 20. Furthermore, a secondary transfer roll 22 that batch-transfers (secondary transfer) each color toner image transferred onto the intermediate transfer belt 20 onto a sheet that is a recording material (recording paper), and each color toner that has been secondarily transferred. And a fixing unit 60 for fixing the image on the paper. In addition, the image forming unit 10 cools each color toner image fixed on the sheet by the fixing unit 60 and promotes fixing of the color toner image on the sheet, and the sheet is bent (curled). And a curl correction unit 85 for correcting the above. The area where the secondary transfer roll 22 is arranged and the respective color toner images on the intermediate transfer belt 20 are secondarily transferred to the paper is hereinafter referred to as “secondary transfer area Tr”.

<Description of paper transport system>
Further, the image forming unit 10 feeds out a plurality of (two in the present embodiment) sheet storage containers 40A and 40B that store sheets and the sheets stored in the sheet storage containers 40A and 40B as a sheet transport system. Feeding rolls 41A and 41B, a first transport path R1 for transporting paper from the paper container 40A, and a second transport path R2 for transporting paper from the paper container 40B. Further, the image forming unit 10 includes a third transport path R3 that transports the paper from the paper storage container 40A and the paper storage container 40B toward the secondary transfer region Tr. In addition, the image forming unit 10 conveys the sheet on which the toner image of each color is transferred in the secondary transfer region Tr so as to pass through the fixing unit 60, the cooling unit 80, and the curl correcting unit 85. And a fifth transport path R5 for transporting the sheet from the curl correction unit 85 toward the sheet stacking section 44 provided in the discharge section of the image forming apparatus 1.
From the first conveyance path R1 to the fifth conveyance path R5, conveyance rolls and conveyance belts are arranged along the respective conveyance paths to sequentially convey the fed sheets.

<Description of double-sided conveyance system>
In addition, the image forming unit 10 serves as a double-sided conveyance system in which an intermediate paper storage container 42 that temporarily holds the paper on which the toner images of each color are fixed on the first surface by the fixing unit 60 and the paper from the curl correction unit 85 as intermediate paper. A sixth transport path R6 for transporting toward the storage container 42 and a seventh transport path R7 for transporting the paper stored in the intermediate paper storage container 42 toward the third transport path R3 are provided. Further, the image forming unit 10 is disposed on the downstream side of the curl correction unit 85 in the sheet conveyance direction, and conveys the sheet toward the sheet stacking unit 44 and a sixth conveyance path R5 that conveys the sheet to the intermediate sheet storage container 42. A distribution mechanism unit 43 that selectively distributes the sheet to the path R6 and a feeding roll 45 that feeds the sheet stored in the intermediate sheet storage container 42 toward the seventh transport path R7 are provided.

<Description of image forming operation>
Next, a basic image forming operation in the image forming apparatus 1 according to the present embodiment will be described.
Each of the image forming units 11 of the image forming unit 10 forms toner images of C color, M color, HC color, HM color, Y color, and K color by an electrophotographic process using the above functional members. Each color toner image formed by each image forming unit 11 is primary-transferred sequentially on the intermediate transfer belt 20 by the primary transfer roll 21 to form a composite toner image in which the respective color toners are superimposed. The synthetic toner image on the intermediate transfer belt 20 is conveyed to the secondary transfer region Tr in which the secondary transfer roll 22 is disposed as the intermediate transfer belt 20 moves (in the direction of the arrow).

  On the other hand, in the paper transport system, the feeding rolls 41A and 41B rotate in synchronization with the start timing of image formation in each image forming unit 11, and the UI unit 90, for example, out of the paper storage container 40A and the paper storage container 40B. The designated sheet is fed by the feeding rolls 41A and 41B. The sheet fed by the feeding rolls 41A and 41B is transported along the first transport path R1 or the second transport path R2 and the third transport path R3, and reaches the secondary transfer region Tr. In the secondary transfer region Tr, the composite toner image held on the intermediate transfer belt 20 is secondarily transferred collectively onto the paper by the transfer electric field formed by the secondary transfer roll 22.

  Thereafter, the sheet on which the composite toner image is transferred is separated from the intermediate transfer belt 20 and conveyed to the fixing unit 60 along the fourth conveyance path R4. The synthesized toner image on the paper transported to the fixing unit 60 is fixed on the paper after being subjected to a fixing process by the fixing unit 60. Then, the sheet on which the fixed image is formed is cooled by the cooling unit 80, and the curl correction unit 85 corrects the bending of the sheet. Thereafter, the paper passing through the curl correction unit 85 is guided by the distribution mechanism unit 43 to the fifth transport path R5 during single-sided printing and transported toward the paper stacking unit 44. The toner (primary transfer residual toner) adhering to the photosensitive drum 12 after the primary transfer and the toner (secondary transfer residual toner) adhering to the intermediate transfer belt 20 after the secondary transfer are respectively cleaner 16, And removed by the belt cleaner 26.

  On the other hand, during double-sided printing, the paper on which the fixed image is formed on the first surface of the paper by the above-described process passes through the curl correction unit 85 and is then guided to the sixth transport path R6 by the distribution mechanism unit 43. The sixth transport path R6 is transported toward the intermediate paper storage container. Again, the feeding roll 45 rotates in accordance with the start timing of image formation on the second surface by each image forming unit 11, and the sheet is fed out from the intermediate sheet storage container 42. The sheet fed by the feed roll 45 is transported along the seventh transport path R7 and the third transport path R3 and reaches the secondary transfer region Tr. In the secondary transfer region Tr, as in the case of the first surface, the toner images of the respective colors on the second surface held on the intermediate transfer belt 20 are collectively applied to the sheet by the transfer electric field formed by the secondary transfer roll 22. Second transfer is performed.

  Then, the paper on which the toner images are transferred on both sides is fixed by the fixing unit 60 as in the case of the first side, cooled by the cooling unit 80, and further corrected by the curl correction unit 85. Is done. Thereafter, the paper that has passed through the curl correction unit 85 is guided to the fifth transport path R5 by the distribution mechanism unit 43 and transported toward the paper stacking unit 44. In this way, the image forming process in the image forming apparatus 1 is repeatedly executed for the number of printed sheets.

<Description of fixing unit configuration>
Next, the fixing unit 60 used in the image forming apparatus 1 of the present embodiment will be described.
FIG. 2 is a cross-sectional configuration diagram for explaining the configuration of the fixing unit 60 of the present embodiment. A fixing unit 60 as an example of a fixing device and a fixing unit includes a fixing belt module 61 that heats a sheet and a pressure configured to be able to contact and separate from the fixing belt module 61 as shown in FIG. The main part is composed of the roll 62 (an example of the second fixing member).

  The fixing belt module 61 rotates while fixing the fixing belt 610 as an example of a belt member provided so as to be circulated and the fixing belt 610 is stretched, and the fixing belt module 61 and the pressure roll 62 are in pressure contact ( And a fixing roll 611 that heats the fixing belt 610 from the inside at a nip portion N, which is a region where they are pressed against each other. The fixing belt module 61 includes an internal heating roll 612 that heats the fixing belt 610 while stretching the fixing belt 610 from the inside, an external heating roll 613 that heats the fixing belt 610 while stretching the fixing belt 610 from the outside, It has. The fixing belt module 61 includes a tension roll 614 that stretches the fixing belt 610 between the fixing roll 611 and the internal heating roll 612 (upstream of the nip portion N), and a downstream region in the nip portion N. A peeling pad 64 (an example of a pressing member) disposed in the vicinity of the fixing roll 611 and a tension roll 615 that stretches the fixing belt 610 on the downstream side of the nip portion N are provided.

  The fixing belt 610 includes, for example, a base layer formed of a polyimide resin, an elastic layer made of silicone rubber laminated on the surface side (outer peripheral surface side) of the base layer, and a PFA coated on the elastic layer. And a release layer made of (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin). Here, the elastic layer is provided in order to improve the image quality especially for color images. That is, the toner image held on the sheet to be fixed is formed by laminating toners of various colors that are powders. Therefore, in order to supply heat uniformly to the entire toner image at the nip portion N, it is preferable that the surface of the fixing belt 610 be deformed following the unevenness of the toner image on the paper.

  The fixing roll 611 as an example of the first fixing member is a cylindrical roll formed of, for example, aluminum or SUS, and rotates in the arrow direction in the drawing in response to a rotational driving force from a driving motor (not shown). Then, the fixing roll 611 is heated to a predetermined temperature (for example, 150 ° C.) by, for example, three halogen heaters 71 as heating sources disposed inside the fixing roll 611.

  The internal heating roll 612 is a cylindrical roll formed of, for example, aluminum or SUS. The internal heating roll 612 is heated to a predetermined temperature (for example, 190 ° C.) by, for example, four halogen heaters 72 serving as heating sources disposed inside. The internal heating roll 612 is provided with spring members (not shown) that press the fixing belt 610 from the inside to the outside at both ends, and the tension of the entire fixing belt 610 is set to 15 kgf, for example.

  Further, the internal heating roll 612 is provided with a mechanism for controlling the meandering (belt walk) of the fixing belt 610. That is, a belt edge position detection mechanism (not shown) that detects the end position (edge position) of the fixing belt 610 is disposed in the vicinity of the internal heating roll 612. The internal heating roll 612 is provided with a displacement mechanism (not shown) that displaces one end of the internal heating roll 612 in a direction perpendicular to the axial direction of the internal heating roll 612. The displacement mechanism displaces the fixing belt 610 in the axial direction of the internal heating roll 612 by displacing one end of the internal heating roll 612 according to the detection result of the belt edge position detection mechanism. Thereby, the belt walk of the fixing belt 610 is controlled.

The external heating roll 613 is a cylindrical roll formed of, for example, aluminum or SUS. Then, the external heating roll 613 is heated to a predetermined temperature (for example, 190 ° C.) by, for example, three halogen heaters 73 serving as heating sources arranged inside.
As described above, the fixing unit 60 of the present embodiment employs a configuration in which the fixing belt 610 is heated by the fixing roll 611, the internal heating roll 612, and the external heating roll 613.

  The peeling pad 64 is a block member made of a metal such as SUS or a rigid body such as resin and having a substantially arc-shaped cross section. Then, the axial direction of the fixing roll 611 at a position near the downstream side of an area (an example of a passing portion) where the pressure roll 62 is pressed against the fixing roll 611 via the fixing belt 610 (hereinafter referred to as “roll nip portion N1”). It is fixedly arranged over the entire area. Here, as shown in FIG. 2B, the peeling pad 64 is disposed to face the inner surface 64 a facing the fixing roll 611 and the inner peripheral surface of the fixing belt 610, with the fixing belt 610 facing the pressure roll 62. A pressing surface 64b to be pressed (an example of a facing surface), an outer surface 64c that has an angle with respect to the pressing surface 64b and that rapidly changes the advancing direction of the fixing belt 610 (bends the fixing belt 610), and an upper surface 64d. Have. In addition, the peeling pad 64 has a predetermined load (for example, a nip width of 5 mm along the traveling direction of the fixing belt 610) (for example, a predetermined width region) on the pressure roll 62 via the fixing belt 610. And an average of 10 kgf), which are installed so as to press uniformly, and form a “peeling pad nip portion N2” connected to the roll nip portion N1.

  Next, the pressure roll 62 is formed by laminating an elastic layer made of silicone rubber and a release layer made of a PFA tube in this order from the substrate side, for example, using a cylindrical roll made of aluminum or SUS as a base. ing. The pressure roll 62 is disposed so as to be in contact with and separated from the fixing belt module 61. When the pressure roll 62 is set so as to contact (pressure contact) while pressing the fixing belt module 61, the fixing roll of the fixing belt module 61 is used. As 611 rotates in the direction of the arrow, it follows the fixing roll 611 and rotates in the direction of the arrow.

<Description of the fixing operation in the fixing unit>
Next, the fixing operation in the fixing unit 60 of the present embodiment will be described.
The sheet on which the composite toner image (unfixed toner image) is electrostatically transferred in the secondary transfer region Tr (see FIG. 1) of the image forming apparatus 1 is fixed along the fourth conveyance path R4 (see FIG. 1). It is conveyed toward the nip portion N (see FIG. 2). The unfixed toner image on the paper surface passing through the nip portion N is fixed to the paper mainly by pressure and heat acting on the roll nip portion N1.

  That is, in the fixing unit 60 of the present embodiment, the heat acting on the roll nip portion N1 is mainly supplied by the fixing belt 610. The fixing belt 610 is supplied with heat supplied from the halogen heater 71 arranged inside the fixing roll 611 via the fixing roll 611 and from the halogen heater 72 arranged inside the internal heating roll 612 via the internal heating roll 612. And the heat supplied from the halogen heater 73 disposed inside the external heating roll 613 through the external heating roll 613. As a result, not only the fixing roll 611 but also the internal heating roll 612 and the external heating roll 613 are replenished with heat energy, so that a sufficient amount of heat is secured at the roll nip portion N1 even if the process speed is high. .

  In the fixing unit 60 of the present embodiment, the fixing belt 610 that functions as a direct heating member can be configured to have an extremely small heat capacity. In addition, the fixing belt 610 is configured to come into contact with the fixing roll 611 that is a heat supply member, and the internal heating roll 612 and the external heating roll 613 with a wide lap area (large wrap angle). Therefore, since a sufficient amount of heat is supplied from the fixing roll 611, the internal heating roll 612, and the external heating roll 613 during a short period in which the fixing belt 610 rotates once, the fixing belt 610 is returned to the necessary fixing temperature in a short time. It becomes possible to make it. Thereby, a predetermined fixing temperature is maintained in the roll nip portion N1.

  As a result, in the fixing unit 60 of the present embodiment, the fixing temperature is maintained even if the paper is continuously fed at a high speed. In addition, the phenomenon that the fixing temperature drops at the start of the fixing operation at high speed (so-called “temperature droop phenomenon”) is suppressed. In particular, when fixing to thick paper having a large heat capacity, the maintenance of the fixing temperature and the occurrence of temperature droop are suppressed, and furthermore, the fixing temperature is switched halfway according to the type of paper (both the fixing temperature is increased and decreased). Even if necessary, the fixing belt 610 has a small heat capacity, so that the temperature can be easily switched by adjusting the output of the halogen heater 71, and further, the halogen heater 72 and the halogen heater 73.

  In the fixing unit 60 of the present embodiment, the fixing roll 611 is a hard roll formed of aluminum, SUS, or the like, and the pressure roll 62 is a soft roll that covers an elastic layer. Therefore, in the roll nip portion N1, the fixing roll 611 hardly bends, and the surface of the pressure roll 62 is bent, so that a nip region having a width in the traveling direction of the fixing belt 610 is formed. As described above, in the roll nip portion N1, the fixing roll 611 on the side where the fixing belt 610 is wrapped is hardly deformed. Therefore, the fixing belt 610 passes through the roll nip portion N1 while keeping the moving speed constant. As a result, the fixing belt 610 is prevented from being wrinkled or distorted at the roll nip portion N1, so that a high-quality fixed image is stably provided.

  After passing through the roll nip portion N1, the sheet is conveyed to the peeling pad nip portion N2. The peeling pad nip portion N <b> 2 is configured so that the peeling pad 64 is pressed against the pressure roll 62 and the fixing belt 610 is pressed against the pressure roll 62. Accordingly, the roll nip portion N1 has a curved shape that is convex downward due to the curvature of the fixing roll 611, whereas the peeling pad nip portion N2 has a curved shape that is convex upward due to the curvature of the pressure roll 62. Yes.

  Therefore, the traveling direction of the sheet heated and pressed under the curvature of the fixing roll 611 in the roll nip portion N1 is changed to the curvature directed in the opposite direction by the pressure roll 62 in the peeling pad nip portion N2. At that time, a minute micro slip occurs between the toner image on the paper and the surface of the fixing belt 610. As a result, the adhesion between the toner image and the fixing belt 610 is weakened, and a state is formed in which the paper is easily peeled off from the fixing belt 610. As described above, the peeling pad nip portion N2 is also positioned in a preparation process for surely peeling in the final peeling process.

  Since the fixing belt 610 is conveyed so as to be wound around the peeling pad 64 at the exit of the peeling pad nip portion N2, the conveyance direction of the fixing belt 610 changes abruptly there. That is, since the fixing belt 610 moves along the outer surface 64c of the peeling pad 64, the bending of the fixing belt 610 becomes large. Therefore, the paper whose adhesion with the fixing belt 610 is weakened in advance in the peeling pad nip portion N2 is separated from the fixing belt 610 by the stiffness of the paper that the paper itself has.

  The paper separated from the fixing belt 610 is guided in the traveling direction by the peeling guide plate 83 disposed on the downstream side of the peeling pad nip portion N2. Thereafter, the paper guided by the peeling guide plate 83 is conveyed toward the cooling unit 80 by the paper discharge guide 78 and the paper discharge belt 79, whereby the fixing process in the fixing unit 60 is completed.

FIG. 3 is a view for explaining the nip portion N. FIG.
In the present embodiment, the boundary region N2S is formed on the roll nip portion N1 side of the pad disposition region (the press contact portion between the separation pad 64 and the pressure roll 62) N2T in which the separation pad 64 is disposed in the separation pad nip portion N2. Is done. In the boundary region N2S, the peeling pad 64 does not press the fixing belt 610, and the fixing belt 610 is pressed against the pressure roll 62 by the tension of the fixing belt 610. As a result, the nip pressure in the boundary region N2S is relatively lower than the nip pressure in the roll nip portion N1 and the nip pressure in the pad disposition region N2T. In this case, a pressure drop portion having a low nip pressure is formed in the boundary region N2S.

  By the way, in the fixing process by the fixing unit 60 of the present embodiment, the paper on which the toner image is formed is heated and pressurized in the roll nip portion N1. In that case, the water | moisture content of the paper which received the heat in the roll nip part N1 may vaporize, and water vapor | steam may be generated. Here, since a high nip pressure is applied at the roll nip portion N <b> 1, bubbles (air gap) due to water vapor are not generated between the fixing belt 610 and the pressure roll 62.

  However, when the boundary region N2S (pressure drop portion) is formed as described above, water vapor is easily generated in the boundary region N2S. When the paper enters the pad arrangement region N2T having a high nip pressure in a state where water vapor is generated, the water vapor (bubbles) generated in the boundary region N2S moves around on the surface of the paper by the high nip pressure. Here, the toner image on the paper is in a state immediately after passing through the roll nip portion N1 and the melted toner is not yet completely solidified. For this reason, a phenomenon occurs in which the toner image is disturbed by the movement of bubbles. As a result, a minute hole is formed in the fixed image, or unevenness occurs, resulting in an image defect.

  In view of this, in the present embodiment, as shown in FIG. 3, a plate-like member 66 is provided to suppress a decrease in pressure in the boundary region N2S. The plate member 66 is formed by bending a SUS sheet metal, and is formed in an L shape in a side view. The plate member 66 is fixed to the peeling pad 64. Further, the plate-like member 66 has a first facing portion 661 disposed to face the pressing surface 64b of the peeling pad 64, and a second facing portion 662 disposed to face the outer surface 64c. Although illustration is omitted, on the outer surface of the plate-like member 66 (surface facing the fixing belt 610), a sliding sheet (sliding layer) having fine irregularities formed on the surface is provided. As the sliding sheet, for example, a fluororesin-impregnated glass fiber sheet can be used. By providing such a sliding sheet, the sliding resistance between the plate-like member 66 and the fixing belt 610 is reduced.

  Here, the first facing portion 661 of the plate-like member 66 extends toward the upstream side in the paper transport direction from the boundary (joint portion) 64e between the inner surface 64a of the peeling pad 64 and the pressing surface 64b of the peeling pad 64. Yes. In addition, the first facing portion 661 of the plate-like member 66 is provided so as to protrude toward the upstream side in the moving direction of the fixing belt 610 from the boundary 64e between the inner side surface 64a and the pressing surface 64b. More specifically, the first facing portion 661 is provided so that a part thereof is located in the boundary region N2S.

  When the plate-like member 66 is provided as in the present embodiment, the fixing belt 610 located in the boundary region N2S is pressed by the plate-like member 66. In other words, the fixing belt 610 positioned in the boundary region N2S is supported by the plate-like member 66 from the inside. As a result, a decrease in pressure in the boundary region N2S is suppressed, and the above-described image defect is less likely to occur. The plate-like member 66 can be provided so that the tip of the first facing portion 661 contacts the outer peripheral surface of the fixing roll 611. In this case, the tip of the first facing portion 661 is supported by the fixing roll 611, and the first facing portion 661 is difficult to deform. Thereby, the pressure drop in the boundary region N2S is further suppressed. The plate-like member 66 is fixed to the peeling pad 64 with the second facing portion 662 sandwiched between the outer surface 64 c of the peeling pad 64 and the plate-like fixing member 67 arranged to face the outer surface 64 c. The fixing member 67 is fixed to the outer surface 64c of the peeling pad 64 by a screw member (not shown).

  FIG. 4 is a diagram for explaining the peeling pad 64, the pressure roll 62, and the fixing roll 611. Specifically, FIG. 2A shows the fixing roll 611 and the pressure roll 62 when the fixing unit 60 is viewed from the direction of the arrow G in FIG. FIG. 5B also shows the peeling pad 64 and the pressure roll 62 when the fixing unit 60 is viewed from the arrow G direction.

  As shown in FIG. 2A, the pressure roll 62 in the present embodiment is formed in a so-called flare shape, and the diameter (outer diameter) of the central portion (central portion in the axial direction) is larger than the diameter of the end portion. Is also getting smaller. In other words, the pressure roll 62 is formed with the outer peripheral surface having a curvature so that the diameter gradually increases toward the end. Further, the fixing roll 611 is formed in a crown shape, and the diameter (outer diameter) of the central portion (the central portion in the axial direction) is larger than the diameter of the end portion. In other words, the fixing roll 611 is formed with the outer peripheral surface having a curvature so that the diameter gradually decreases toward the end of the fixing roll 611. When the pressure roll 62 and the fixing roll 611 are configured in this way, a force that pulls the paper in the width direction acts at the nip portion N, and the paper is less likely to be wrinkled.

  The pressure roll 62 will be further described. The pressure roll 62 is in a state where the central portion in the axial direction is recessed, and when the pressure roll 62 is not pressed by the fixing roll 611, the amount of the depression is 250 μm. . In other words, the height difference between the outer peripheral surface at the end of the pressure roll 62 and the outer peripheral surface at the center of the pressure roll 62 (the amount of positional deviation in the radial direction of the pressure roll 62) is 250 μm.

  Further, the fixing roll 611 will be further described. The fixing roll 611 is in a state in which the central portion in the axial direction protrudes, and the protruding amount is 50 μm when the pressure roll 62 is not pressed. In other words, the height difference between the outer peripheral surface at the end of the fixing roll 611 and the outer peripheral surface at the center of the fixing roll 611 (the amount of positional deviation in the radial direction of the fixing roll 611) is 50 μm. Further, the relationship with the pressure roll 62 will be described. The protrusion amount (50 μm) of the fixing roll 611 is smaller than the recess amount (250 μm) of the pressure roll 62.

  In this embodiment, as shown in FIG. 5B, the pressing surface 64b of the peeling pad 64 is formed so as to follow the surface of the pressure roll 62. In other words, the pressing surface 64b of the peeling pad 64 has a central portion (a central portion in the longitudinal direction of the peeling pad 64) positioned closer to the pressure roll 62 than an end portion (an end portion in the longitudinal direction of the peeling pad 64). It is formed in a crown shape. More specifically, the pressing surface 64b of the peeling pad 64 is formed in an arc so as to approach the pressure roll 62 from the end of the peeling pad 64 toward the center of the peeling pad 64.

  More specifically, the pressing surface 64b of the peeling pad 64 is in a state where the central portion in the longitudinal direction of the peeling pad 64 protrudes, and the protruding amount becomes 1000 μm when the pressure roll 62 is not pressed. ing. In other words, the difference in height between the location of the pressing surface 64b located at the end of the peeling pad 64 and the location of the pressing surface 64b located at the center of the peeling pad 64 is 1000 μm.

  Explaining the relationship with the pressure roll 62, the protrusion amount (1000 μm) of the peeling pad 64 is larger than the dent amount (250 μm) of the pressure roll 62. Explaining the relationship with the fixing roll 611, the protruding amount (1000 μm) of the peeling pad 64 is larger than the protruding amount (50 μm) of the fixing roll 611. 4B, illustration of the plate-like member 66 (see FIG. 3) is omitted, but the plate-like member 66 is curved so that the first facing portion 661 follows the pressing surface 64b of the peeling pad 64. It is provided in the state. In addition, the first facing portion 661 of the plate-like member 66 is also formed in a crown shape.

  Here, the pressing surface 64b of the peeling pad 64 (the first facing portion 661 of the plate-like member 66) can be formed flat, but in this case, the pressure in the pad placement region N2T is the central portion of the peeling pad 64. It decreases as it goes toward (the center in the longitudinal direction). In the present embodiment, water vapor that has been suppressed at the roll nip portion N1 and the peeling pad nip portion N2 may be generated at the outlet of the peeling pad nip portion N2, resulting in an image defect. Here, when the pressing surface 64b of the peeling pad 64 is formed in a flat shape as described above and the pressure roll 62 is formed in a flare shape as described above, the pressure in the pad placement region N2T is changed to the peeling pad 64. It decreases as it goes to the central part of. In this case, since the water vapor is easily generated due to the pressure drop, the scale of the image defect tends to increase.

  Therefore, in the peeling pad 64 in the present embodiment, the pressing surface 64b is formed in a crown shape as described above, and the pressure generated between the peeling pad 64 and the pressure roll 62 (pressure in the pad arrangement region N2T) is peeled off. It is made uniform in the longitudinal direction of the pad 64. In this case, the water vapor generated in the boundary region N2S does not concentrate at a specific location but is dispersed in the longitudinal direction of the peeling pad 64. As a result, even if an image defect occurs due to water vapor, the scale is reduced. That is, image defects are less noticeable.

  In the present embodiment, as described above, the protrusion amount (1000 μm) on the pressing surface 64 b of the peeling pad 64 is larger than the recess amount (250 μm) of the pressure roll 62. This is because the bending of the peeling pad 64 is taken into consideration. The peeling pad 64 receives a load from the pressure roll 62 and bends away from the pressure roll 62. As a result, a pressure drop tends to occur at the central portion in the axial direction. When the protrusion amount on the pressing surface 64b is larger than the recess amount of the pressure roll 62 as in the present embodiment, the pressure drop that tends to occur in the central portion in the axial direction is suppressed. In this embodiment, the peeling pad 64 is more easily bent than the fixing roll 611. Therefore, in this embodiment, the protruding amount of the peeling pad 64 is as large as 1000 μm, but the protruding amount of the fixing roll 611 is as small as 50 μm.

  FIG. 5 is a perspective view when the peeling pad 64 is viewed from below. 5A is a perspective view of the peeling pad 64 before the plate-like member 66 is attached, and FIG. 5B is a perspective view of the peeling pad 64 after the plate-like member 66 is attached.

  In the peeling pad 64 in the present embodiment, the pressing surface 64b is formed so as to follow the surface of the pressure roll 62 as described above. Referring again to FIG. 5A, the pressing surface 64 b draws an arc so as to approach the pressure roll 62 from the end (both ends) of the peeling pad 64 toward the center of the peeling pad 64. (Having a curvature). More specifically, the pressing surface 64b is formed in a state where the central portion protrudes downward rather than the end portion.

  Further, the pressing surface 64b of the peeling pad 64 in the present embodiment has a first side 641 on one end side in the longitudinal direction of the peeling pad 64 as shown in FIG. A second side 642 is provided on the other end side, and a third side 643 (side on which the first fixing member is arranged) is located upstream in the paper conveyance direction (side on which the fixing roll 611 is arranged). And a fourth side 644 on the downstream side in the paper conveyance direction. In other words, the pressing surface 64 b of the peeling pad 64 is formed by being surrounded by a plurality of sides of the first side 641 to the fourth side 644.

  In the present embodiment, the third side 643 is formed by drawing an arc. In addition, the third side 643 is formed with a curvature so as to protrude toward the upstream side in the sheet conveyance direction (the side on which the fixing roll 611 is disposed). More specifically, the third side 643 is provided in a state where the central portion in the longitudinal direction is closer to the fixing roll 611 than the end portion. In addition, the separation distance between the fixing roll 611 and the third side 643 is small at the center of the peeling pad 64 and large at the end of the peeling pad 64.

  More specifically, when the separation distance between the third side 643 and the fourth side 644 is T2 at the center of the peeling pad 64, the third side 643 and the fourth side at the end of the peeling pad 64 are described. The separation distance from 644 is T1 (<T2). In the present embodiment, since the third side 643 is formed in a circular arc shape, the width of the pressing surface 64b (the width in the moving direction of the fixing belt 610) differs between the central portion and the end portion of the peeling pad 64. ing. In addition, in the present embodiment, the width of the pressing surface 64b decreases as it goes from the center portion of the peeling pad 64 toward the end portion.

  The plate-like member 66 will be described with reference to FIG. 5B. The first facing portion 661 of the plate-like member 66 is provided in a curved state so as to follow the pressing surface 64b of the peeling pad 64. . In addition, the first facing portion 661 is formed in a circular arc shape (having a curvature) so as to approach the pressure roll 62 from the end portion (both end portions) in the longitudinal direction toward the center portion in the longitudinal direction. ing. More specifically, the first facing portion 661 is provided in a state where the central portion protrudes downward rather than the end portion in the longitudinal direction.

  Moreover, the 1st opposing part 661 has the 1st edge | side 661A in the one end side in a longitudinal direction, and has the 2nd edge | side 661B in the other end side in a longitudinal direction. The first facing portion 661 has a third side 661C on the upstream side in the sheet conveyance direction (the side on which the fixing roll 611 is disposed). The third side 661C is located closer to the fixing roll 611 than the third side 643 provided on the peeling pad 64. The first facing portion 661 has a fourth side 661D on the downstream side in the paper transport direction. In addition, the first facing portion 661 is formed by being surrounded by a plurality of sides of the first side 661A to the fourth side 661D.

  In the present embodiment, the third side 661C is formed in an arc shape. In addition, the third side 661C is formed with a curvature so as to protrude toward the upstream side in the sheet conveyance direction (the side on which the fixing roll 611 is disposed). More specifically, the third side 661C is provided in a state in which the central portion in the longitudinal direction is closer to the fixing roll 611 than the end portion. In other words, the separation distance between the fixing roll 611 and the third side 661C is small at the central portion in the longitudinal direction of the first opposing portion 661 and large at the end portion in the longitudinal direction of the first opposing portion 661. ing.

  More specifically, the separation distance between the third side 661C and the fourth side 661D is T4 in the center portion in the longitudinal direction of the first facing portion 661, and the end portion in the longitudinal direction of the first facing portion 661. T3 (<T4). In the present embodiment, since the third side 661C is formed in an arc shape, the width of the first facing portion 661 (the width in the moving direction of the fixing belt 610) is the center in the longitudinal direction of the first facing portion 661. The part and the end are different. More specifically, in the present embodiment, the width of the first facing portion 661 decreases from the center portion of the first facing portion 661 toward the end portion.

FIG. 6 is a view for explaining the pressure distribution in the nip portion N. FIG. Specifically, a state when the pressure distribution in the nip portion N shown in FIG. 3 is viewed from above is shown.
In the present embodiment, a rectangular roll nip portion N1 is formed by the fixing roll 611 and the pressure roll 62 on the upstream side in the sheet conveyance direction. Further, a pad disposition region N2T is formed by the peeling pad 64 and the pressure roll 62 on the downstream side in the sheet transport direction from the roll nip portion N1. In addition, a pressing nip portion N3 formed when the plate-like member 66 presses the fixing belt 610 is formed between the roll nip portion N1 and the pad arrangement region N2T.

  Here, the pressing surface 64b of the peeling pad 64 has the four sides of the first side 641 to the fourth side 644 as described above. For this reason, the pad arrangement region N2T also has a first side N21 to a fourth side N24 corresponding to the four sides of the pressing surface 64b. In the present embodiment, as described above, the third side 643 of the pressing surface 64 b is formed in an arc shape so that the central portion thereof approaches the fixing roll 611. For this reason, the third side N23 in the pad arrangement region N2T is also formed in an arc shape so that the center portion thereof approaches the fixing roll 611.

  In the present embodiment, the pressing nip portion N3 is formed by the first facing portion 661 (see FIG. 5B) of the plate-like member 66. The pressing nip portion N3 is provided in a state of being continuous with the pad arrangement region N2T, and is provided upstream of the pad arrangement region N2T in the movement direction of the fixing belt 610. Further, the pressing nip portion N3 has a side N31 corresponding to the third side 661C formed with a curvature on the upstream side in the moving direction of the fixing belt 610. The side N31 is formed in a state having a curvature so that the central portion in the longitudinal direction approaches the roll nip portion N1. More specifically, the side N31 is formed so as to move away from the roll nip portion N1 as it goes from the center portion to the end portion. The separation distance between the roll nip portion N1 and the pressing nip portion N3 is the largest at the end portion of the roll nip portion N1 (end portion in the direction orthogonal to the paper transport direction), and the center portion of the roll nip portion N1 (the transport direction of the paper) It becomes the smallest in the central part in the orthogonal direction.

  In the present embodiment, there is a possibility that the water vapor that has been suppressed at the roll nip portion N1 may be generated in the boundary region N2S, and if this water vapor enters the pad arrangement region N2T, an image defect may occur. For this reason, in this embodiment, as described above, the side N31 of the pressing nip portion N3 is formed by drawing an arc so as to move away from the roll nip portion N1 as it goes from the center portion to the end portion. This is because image defects due to water vapor are more likely to occur at the center than at the ends. As described above, when the arc is formed so as to move away from the roll nip portion N1 as it goes from the center portion to the end portion, generation of water vapor in the boundary region N2S is suppressed, and image defects are less likely to occur.

  In the above embodiment, the plate-like member 66 is provided to suppress the pressure drop in the boundary region N2S. However, the plate-like member 66 can be omitted. For example, the pressure drop in the boundary region N2S can be suppressed by extending the tip of the peeling pad 64. Further, it is possible to suppress the pressure drop in the boundary region N2S by bringing the entire peeling pad 64 closer to the fixing roll 611. In addition, when extending the tip part of the peeling pad 64, the strength of the peeling pad 64 may be reduced. When the peeling pad 64 is brought close to the fixing roll 611, the peeling pad 64 and the fixing roll 611 are in contact with each other over a wide range. there's a possibility that. On the other hand, such a problem is unlikely to occur in the aspect in which the plate-like member 66 is separately attached to the peeling pad 64 as described above. For this reason, it can be said that the aspect which attaches the plate-shaped member 66 separately with respect to the peeling pad 64 is a more preferable aspect compared with the case where the pressure reduction by the peeling pad 64 itself is suppressed.

  Although not described above, in the present embodiment, as shown in FIG. 3, the first position is deviated from a line (imaginary line) connecting the axis of the fixing roll 611 and the axis of the pressure roll 62. The fixing unit 60 is configured so that the front end portion of the facing portion 661 is positioned. In addition, in the present embodiment, the tip portion of the first facing portion 661 is not placed on a line connecting the axis of the fixing roll 611 and the axis of the pressure roll 62, but at a position off the line. A tip portion of the first facing portion 661 is provided. More specifically, the front end portion of the first facing portion 661 is located downstream of the line connecting the axis of the fixing roll 611 and the axis of the pressure roll 62 in the moving direction of the fixing belt 610.

  The pressing force with which the pressure roll 62 presses the fixing roll 611 is the largest on the line connecting the axis of the fixing roll 611 and the axis of the pressure roll 62. Here, when the tip of the first facing portion 661 is placed (positioned) on the line connecting the axis of the fixing roll 611 and the axis of the pressure roll 62, the influence of the pressing force is affected. The tip end portion of the first facing portion 661 is more easily deformed due to the large reception. In this case, the front end portion is in strong contact with the outer peripheral surface of the fixing roll 611, and wear of the fixing roll 611 or the like is more likely to proceed. Further, the load on the fixing roll 611 becomes larger. Therefore, in the present embodiment, as described above, the tip of the first facing portion 661 is disposed at a position deviated from the line connecting the axis of the fixing roll 611 and the axis of the pressure roll 62. In this case, the deformation of the tip portion of the first facing portion 661 is suppressed, and the above-described problem is less likely to occur.

Here, the plate member 66 will be described in more detail.
FIG. 7 is an enlarged view of the first facing portion 661 of the plate-like member 66. More specifically, it is a cross-sectional view of the end portion located on the upstream side in the moving direction of the fixing belt 610 among the end portions provided in the first facing portion 661. In other words, it is a cross-sectional view of the tip portion of the first facing portion 661 in the protruding direction.

  As shown in the figure, the first facing portion 661 has a first surface 663 on the inner peripheral surface side of the fixing belt 610 (see FIG. 3), and a second surface on the opposite side to the first surface 663. It has a surface 664. In addition, the first facing portion 661 has a second surface 664 on the side facing the pressing surface 64b (see FIG. 3) of the peeling pad 64. Furthermore, the first facing portion 661 includes an end surface 665 that connects the first surface 663 and the second surface 664. Further, in this drawing, a sliding sheet (sliding layer) S (an example of a sheet-like member) not shown above is illustrated. Here, in the sliding sheet S, fine irregularities (not shown) are formed on the side in contact with the inner peripheral surface of the fixing belt 610.

  In the present embodiment, the corners of the plate-like member 66 are chamfered. More specifically, the first corner portion 666 formed by the first surface 663 and the end surface 665 is chamfered. And the location where this chamfering was given becomes a curved surface, and has the state of curvature. Further, the second corner 667 formed by the second surface 664 and the end surface 665 is also chamfered. And the location where this chamfering was performed also becomes a curved surface, and has the state of curvature.

  Here, when the first corner portion 666 is not chamfered, more abrasion powder is generated due to friction between the first corner portion 666 and the fixing belt 610 than when the first corner portion 666 is chamfered. . Further, when chamfering is not performed on the second corner portion 667, more abrasion powder is generated due to friction between the second corner portion 667 and the fixing roll 611 than when chamfering is performed. When the wear powder enters between the sliding sheet S and the fixing belt 610, the wear powder enters the unevenness formed on the sliding sheet S. When wear powder enters the unevenness, the surface of the sliding sheet S becomes smooth, and the sliding resistance between the sliding sheet S and the fixing belt 610 increases. For this reason, in this embodiment, chamfering is performed on the plate-like member 66 to suppress the generation of the wear powder, and the increase in the sliding resistance between the sliding sheet S and the fixing belt 610 is suppressed.

  As shown in FIG. 7, the sliding sheet S protrudes toward the fixing roll 611 (see FIG. 3) from the front end portion (end surface 665) of the first facing portion 661. In other words, in the moving direction of the fixing belt 610, the end portion of the sliding sheet S is positioned on the upstream side of the front end portion of the first facing portion 661. In this case, the chamfered portion of the plate-like member 66 is more reliably covered by the sliding sheet S, and the wear powder is less likely to be generated.

  Here, in this embodiment, as a result of the chamfering, a curved surface R1 having one end connected to the first surface 663 and the other end connected to the end surface 665 is formed at the location where the first corner portion 666 was present. The Here, in the present embodiment, the distance between the intersection position K1 between the extension line of the first surface 663 and the extension line of the end surface 665 and the one end is defined as a distance A, and the distance between the intersection position K1 and the other end is defined as a distance. In the case of B, the distance A is larger than the distance B. Thus, when the relationship of distance A> distance B is given, the fixing belt 610 moves more smoothly than when the relationship of distance B> distance A is given.

  Further, in the present embodiment, as a result of chamfering, a curved surface R2 having one end connected to the second surface 664 and the other end connected to the end surface 665 is formed at the location where the second corner portion 667 was present. The In this embodiment, the distance between the intersection position K2 between the extension line of the second surface 664 and the extension line of the end surface 665 and the one end is defined as a distance C, and the distance between the intersection position K2 and the other end is defined as a distance. In the case of D, the distance C is larger than the distance D. Thus, when the relationship of distance C> distance D is given, the fixing roll 611 rotates more smoothly than when the relationship of distance D> distance C is given.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming part, 60 ... Fixing unit, 62 ... Pressure roll, 64 ... Peeling pad, 64b ... Pressing surface, 66 ... Plate-shaped member, 610 ... Fixing belt, 611 ... Fixing roll, 643 3rd side, 663 ... 1st surface, 664 ... 2nd surface, 665 ... End surface, 666 ... 1st corner, 667 ... 2nd corner, N1 ... Roll nip, S ... Sliding sheet

Claims (4)

A belt member capable of circulating movement;
A first fixing member disposed inside the belt member;
A second fixing member, which is pressed against the first fixing member via the belt member and forms a passing portion through which the recording material passes, between the belt member,
The belt is disposed downstream of the first fixing member in the moving direction of the belt member and inside the belt member, and is surrounded by a plurality of sides including a side located on the side where the first fixing member is arranged. A pressing member that has a facing surface formed facing the inner peripheral surface of the belt member and presses the belt member toward the second fixing member using the facing surface;
Provided between the opposing surface and the inner peripheral surface of the belt member, and closer to the first fixing member side than the side of the pressing member located on the side where the first fixing member is disposed. Protruding, having a first surface on the inner peripheral surface side of the belt member and a second surface on the opposite side of the first surface, the first surface and the second surface And a plate-like member having an end face connecting to the tip in the protruding direction;
A sheet-like member disposed between the plate-like member and the inner peripheral surface of the belt member;
With
At least one of a first corner formed by the first surface and the end surface of the plate-like member and a second corner formed by the second surface and the end surface. Beveled,
The fixing device according to claim 1, wherein the sheet-like member is provided so as to protrude toward the first fixing member from the front end portion of the plate-like member. A belt member capable of circulating movement;
A first fixing member disposed inside the belt member;
A second fixing member, which is pressed against the first fixing member via the belt member and forms a passing portion through which the recording material passes, between the belt member,
The belt is disposed downstream of the first fixing member in the moving direction of the belt member and inside the belt member, and is surrounded by a plurality of sides including a side located on the side where the first fixing member is arranged. A pressing member that has a facing surface formed facing the inner peripheral surface of the belt member and presses the belt member toward the second fixing member using the facing surface;
Provided between the opposing surface and the inner peripheral surface of the belt member, and closer to the first fixing member side than the side of the pressing member located on the side where the first fixing member is disposed. Protruding, having a first surface on the inner peripheral surface side of the belt member and a second surface on the opposite side of the first surface, the first surface and the second surface And a plate-like member having an end face connecting to the tip in the protruding direction;
With
At least one of a first corner formed by the first surface and the end surface of the plate-like member and a second corner formed by the second surface and the end surface. Beveled,
The plate-like member is provided along the width direction of the belt member,
The front end portion of the plate-like member is provided along the width direction of the belt member, and is separated from the first fixing member from the center portion in the longitudinal direction of the plate-like member toward the end portion in the longitudinal direction. The fixing device is formed as described above. Image forming means for forming an image on a recording material;
Fixing means for fixing the image to a recording material on which an image is formed by the image forming means,
The fixing means is
A belt member capable of circulating movement;
A first fixing member disposed inside the belt member;
A second fixing member that is pressed against the first fixing member via the belt member and forms a passing portion between the belt member and a recording material on which an image is formed by the image forming unit; ,
The belt is disposed downstream of the first fixing member in the moving direction of the belt member and inside the belt member, and is surrounded by a plurality of sides including a side located on the side where the first fixing member is arranged. A pressing member that has a facing surface formed facing the inner peripheral surface of the belt member and presses the belt member toward the second fixing member using the facing surface;
Provided between the opposing surface and the inner peripheral surface of the belt member, and closer to the first fixing member side than the side of the pressing member located on the side where the first fixing member is disposed. Protruding, having a first surface on the inner peripheral surface side of the belt member and a second surface on the opposite side of the first surface, the first surface and the second surface And a plate-like member having an end face connecting to the tip in the protruding direction;
A sheet-like member disposed between the plate-like member and the inner peripheral surface of the belt member;
With
At least one of a first corner formed by the first surface and the end surface of the plate-like member and a second corner formed by the second surface and the end surface. Beveled,
The image forming apparatus, wherein the sheet-like member is provided so as to protrude toward the first fixing member from the front end portion of the plate-like member. Image forming means for forming an image on a recording material;
Fixing means for fixing the image to a recording material on which an image is formed by the image forming means,
The fixing means is
A belt member capable of circulating movement;
A first fixing member disposed inside the belt member;
A second fixing member that is pressed against the first fixing member via the belt member and forms a passing portion between the belt member and a recording material on which an image is formed by the image forming unit; ,
The belt is disposed downstream of the first fixing member in the moving direction of the belt member and inside the belt member, and is surrounded by a plurality of sides including a side located on the side where the first fixing member is arranged. A pressing member that has a facing surface formed facing the inner peripheral surface of the belt member and presses the belt member toward the second fixing member using the facing surface;
Provided between the opposing surface and the inner peripheral surface of the belt member, and closer to the first fixing member side than the side of the pressing member located on the side where the first fixing member is disposed. Protruding, having a first surface on the inner peripheral surface side of the belt member and a second surface on the opposite side of the first surface, the first surface and the second surface And a plate-like member having an end face connecting to the tip in the protruding direction;
With
At least one of a first corner formed by the first surface and the end surface of the plate-like member and a second corner formed by the second surface and the end surface. Beveled,
The plate-like member is provided along the width direction of the belt member,
The front end portion of the plate-like member is provided along the width direction of the belt member, and is separated from the first fixing member from the center portion in the longitudinal direction of the plate-like member toward the end portion in the longitudinal direction. An image forming apparatus formed as described above.

Images