JP2011123273A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which can more smoothly peel a recording material sticking to a pressure member, and in which it is hard to damage the recording material. <P>SOLUTION: A fixing unit 60 includes: a fixing belt 610 configured to fix a toner image on paper P; a pressure roll 62 configured to come into press-contact with the outer peripheral surface of the fixing belt 610 to form a nip part N through which the paper P holding an unfixed toner image passes between the fixing belt 610 and the pressure roll 62; a fixing roll 611 disposed facing the pressure roll 62 across the fixing belt 610 to stretch the fixing belt 610; a peeling pad 64 disposed in a position, which is the downstream-side area of the nip part N and adjacent to the fixing roll 611, and configured to peel the paper P from the fixing belt 610; and a peeling member disposed in contact with the pressure roll 62 and having a pawl part to peel the paper P sticking to the pressure roll 62; wherein the pawl part of the peeling member has a bent part on a surface of a side to guide the peeled paper P. <P>COPYRIGHT: (C)2011,JPO&INPIT

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

Here, in general, the sheet that has passed through the nip portion is separated from the fixing belt and discharged from the fixing device. However, although the paper is separated from the fixing belt, the paper is sometimes attached to the pressure roll and discharged. In this case, since the paper jam occurs due to the paper being wound around the pressure roll, it is necessary to peel the paper attached to the pressure roll without damaging it as much as possible.
An object of the present invention is to provide a fixing device or the like that can more smoothly peel a sheet attached to a pressure roll and hardly damage the sheet.

  According to the first aspect of the present invention, there is provided a fixing member that fixes a toner image on a recording material, and a recording material that holds an unfixed toner image between the fixing member and the outer peripheral surface of the fixing member. A fixing member for forming a fixing pressure member, a tension member sandwiching the fixing member and facing the pressure member, and tensioning the fixing member; and downstream of the fixing pressure member A first separation member that is a side region and is disposed adjacent to the tension member and that separates the recording material from the fixing member; and a pressure member that is disposed in contact with the pressure member. A second peeling member having a claw portion for peeling off the recording material attached to the recording material, wherein the claw portion of the second peeling member is bent to a surface on the side that guides the separated recording material. A fixing device having a section.

According to a second aspect of the present invention, the claw portion has a first surface that guides the recording material by contacting the recording material with the bent portion as a boundary, and the additional surface with respect to the first surface. The fixing device according to claim 1, further comprising a second surface bent toward the pressure member side.
According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the claw portion has a concave portion in a portion other than an outer peripheral portion of a surface on the side for guiding the recording material. .
According to a fourth aspect of the present invention, when the claw portion is viewed from the direction in which the recording material passes, the both end portions of the surface where the claw portion contacts the pressure member are at the center portion. 4. The fixing device according to claim 1, wherein the fixing device is curved so as to be away from the pressure member.
The invention according to claim 5 further includes a paper discharge guide member that holds the peeling member and is coupled to a rotation shaft of the pressure member, and the paper discharge guide member is a first surface of the peeling member. The fixing device according to claim 1, further comprising a bent portion for guiding the recording material.

  According to a sixth aspect of the present invention, there is provided a toner image forming unit for forming a toner image, a transfer unit for transferring the toner image formed by the toner image forming unit onto a recording material, and a toner image on the recording material. A fixing member for fixing, and a pressure member that forms a fixing pressure part for allowing a recording material holding an unfixed toner image to pass between the fixing member and the fixing member by being pressed against the outer peripheral surface of the fixing member; A tension member that is disposed opposite to the pressure member with the fixing member interposed therebetween and stretches the fixing member, and is disposed in a region adjacent to the tension member in the downstream region of the fixing pressure portion. A first peeling member for peeling the recording material from the fixing member; and a nail for contacting the pressure member and peeling the recording material attached to the pressure member. A second peeling member having a portion, and The claw portion of the second stripping member, an image forming apparatus characterized by having a bent portion on a surface of a side for guiding the peeled said recording material.

According to the first aspect of the present invention, compared to the case where the present invention is not adopted, it is possible to provide a fixing device that can more smoothly peel the paper adhered to the pressure roll and hardly damage the paper.
According to the second aspect of the present invention, the contact area between the paper peeled from the pressure roll and the claw portion can be made smaller than in the case where the present invention is not adopted.
According to the third aspect of the present invention, the paper separated from the pressure roll can be guided more smoothly than in the case where the present invention is not adopted.
According to the fourth aspect of the present invention, compared to the case where the present invention is not adopted, the paper attached to the pressure roll can be more reliably peeled off.
According to the fifth aspect of the present invention, compared to the case where the present invention is not adopted, it is possible to more smoothly guide the sheet peeled from the pressure roll to the discharge guide member.
According to the sixth aspect of the present invention, it is possible to provide an image forming apparatus capable of suppressing paper damage and obtaining a better image quality as compared with the case where the present invention is not adopted.

1 is a diagram illustrating a configuration example of an image forming apparatus to which a fixing device according to an exemplary embodiment is applied. FIG. 3 is a cross-sectional configuration diagram for describing a configuration of a fixing unit of the present embodiment. It is a figure explaining the paper discharge guide provided with the peeling member in this Embodiment. FIG. 6 is a diagram illustrating a form in which a paper discharge guide according to the present embodiment is actually attached. (A)-(c) is the figure explaining the peeling member attached to a paper discharge guide. It is the figure which demonstrated in more detail about the operation | movement at the time of peeling a paper from a pressure roll with a peeling 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 to which a fixing unit (fixing device) 60 according to the present embodiment is applied. An image forming apparatus 1 shown in FIG. 1 is a so-called “tandem type” color printer, and controls an image forming unit 10 that forms an image based on image data, operation control of the entire image forming apparatus 1, for example, a personal computer (PC). A main control unit 50 that performs communication with the user, image processing performed on image data, and the like, and a user interface (UI) unit 90 that receives operation input from the user and displays various information to the user. ing.

<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 as an example of toner image forming units arranged in parallel. 11K (hereinafter “image forming unit 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 device 15, and each of them is C (cyan) color, M (magenta) color, HC (high chroma cyan) color, and HM (high chroma magenta). Color, 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 as an example of a fixing unit (fixing device) for fixing the image on the sheet.
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.
In the image forming apparatus 1 of the present embodiment, the intermediate transfer belt 20, the primary transfer roll 21, and the secondary transfer roll 22 constitute a transfer unit. Further, an area where the secondary transfer roll 22 is disposed and each color toner image on the intermediate transfer belt 20 is secondarily transferred to a sheet is hereinafter referred to as a “secondary transfer area Tr”.

<Description of paper transport system>
In addition, 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 a sheet 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. The fixing unit 60 includes a fixing belt module 61 as an example of a heating unit that heats the paper P, and a pressure roll 62 as an example of a pressure member configured to be able to contact with and separate from the fixing belt module 61. The main part is composed.
The fixing belt module 61 is arranged to face the pressure roll 62 with the fixing belt 610 sandwiched between the fixing belt 610 as an example of a fixing member that fixes the toner image on the paper P, and rotates while stretching the fixing belt 610. The fixing belt 610 is attached to a nip portion (fixing pressure portion) N, which is one of the tension members that operate and is a region where the fixing belt module 61 and the pressure roll 62 are in pressure contact (contact with each other while being pressed against each other). A fixing roll 611 for heating from the inside, an internal heating roll 612 as an example of an internal heating means for heating the fixing belt 610 while stretching the fixing belt 610 from the inside, and a fixing belt 610 while stretching the fixing belt 610 from the outside. And an external heating roll 613 as an example of an external heating means for heating. 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 of the nip portion N. A peeling pad 64 as an example of a first peeling member disposed at a position adjacent to the fixing roll 610, and a tension roll 615 that stretches the fixing belt 610 on the downstream side of the nip portion N. .

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 paper P 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 P.
The fixing roll 611 is a cylindrical roll formed of, for example, aluminum or SUS, and receives a rotational driving force from a driving motor (not shown) and rotates in the arrow direction in the figure. 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. The fixing roll 611 is fixedly disposed over the entire axial direction of the fixing roll 611 at a position near the downstream side of the area 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”). Has been. 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) in a predetermined width region (for example, 5 mm along the traveling direction of the fixing belt 610) via the fixing belt 610. For example, it is installed so as to press uniformly at an average of 10 kgf), and a “peeling pad nip portion N2” connected to the roll nip portion N1 is formed.

  The pressure roll 62 is a member that forms a nip portion N through which the paper P holding an unfixed toner image passes between the pressure belt 62 and the fixing belt 610 by being pressed against the outer peripheral surface of the fixing belt 610. The pressure roll 62 is configured, for example, by using, as a base, a cylindrical roll made of aluminum or SUS, and an elastic layer made of silicone rubber and a release layer made of a PFA tube in order from the base side. 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 P 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 transport path R4 (see FIG. 1). 60 is conveyed toward the nip N (see FIG. 2). The unfixed toner image on the surface of the paper P passing through the nip portion N is fixed on the paper P 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 substantially constant even when 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 the temperature droop phenomenon are suppressed, and the fixing temperature is switched in the middle according to the paper type (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 maintaining the moving speed substantially 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.

Subsequently, after passing through the roll nip portion N1, the paper P 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 paper P 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 P 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 P 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 of the peeling pad 64, the bending of the fixing belt 610 becomes large. Therefore, the paper P 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 P itself has.

The paper P separated from the fixing belt 610 is guided in its traveling direction by a peeling guide plate 69 as an example of a peeling guide member arranged on the downstream side of the peeling pad nip portion N2. The paper P guided by the peeling guide plate 69 is then conveyed toward the cooling unit 80 by a paper discharge guide 78 as an example of a paper discharge guide member and a paper discharge belt 79. That is, the peeling guide plate 69 is a member for completely separating the paper P peeled from the fixing belt 610 from the fixing belt 610 and defining the traveling direction of the paper P. The paper discharge guide 78 and the paper discharge belt 79 are members for smoothly guiding the paper P, whose traveling direction is defined by the peeling guide plate 69, to the cooling unit 80.
The fixing process in the fixing unit 60 is completed by the operation described above.

<Explanation of paper discharge guide and second peeling member>
Here, the paper P that has passed through the nip portion N is normally separated from the fixing belt 610 as described above and conveyed toward the cooling unit 80. However, the paper P may be discharged while adhering to the pressure roll 62 side. This is likely to occur when performing duplex printing. That is, at the time of duplex printing, as described above, the paper P on which the fixed image is formed on the first surface is along the sixth transport path R6, the seventh transport path R7, and the third transport path R3 (see FIG. 1). Each color toner image on the second surface is secondarily transferred onto the paper P at once. Then, after the secondary transfer, the sheet P enters the fixing unit 60 again through the fourth transport path R4 (see FIG. 1) in order to fix the toner image on the second surface. At this time, the fixed image on the first surface is formed on the pressure roll 62 side. A part of the toner forming the fixed image on the first surface may be remelted by the heat supplied at the nip portion N. As a result of applying pressure together with heat in the nip portion N, the sheet P and the pressure roll 62 are likely to adhere to each other through the melted toner.
If a normal fixing operation is performed with the paper P and the pressure roll 62 attached, paper jam occurs due to the paper P being wound around the pressure roll 62. Therefore, in the present embodiment, the paper discharge guide 78 is provided with a second peeling member for peeling the paper P from the pressure roll 62.

FIG. 3 is a diagram illustrating the paper discharge guide 78 provided with the second peeling member in the present embodiment. FIG. 4 is a diagram for explaining a form in which the paper discharge guide 78 in the present embodiment is actually attached. Hereinafter, the paper discharge guide 78 of the present embodiment will be described with reference to FIGS. 3 and 4.
The paper discharge guide 78 shown in FIGS. 3 and 4 is provided with a guide plate 781 for guiding the paper P after passing through the nip portion N, and an attachment for fixing the paper discharge guide 78 itself provided below the guide plate 781. The main part is composed of the part 782.
The guide plate 781 is a member for guiding the paper P discharged on the upper surface thereof and transporting it to the paper discharge belt 79. In the present embodiment, the guide plate 781 has five cutout portions 783 that are open on the pressure roll 62 side. A peeling member 790, which is a second peeling member, which will be described later in detail, is attached and held at a position corresponding to the notch 783.
The attachment portion 782 takes an arc shape at the tip portion 782a. Then, as shown in FIG. 4, the entire discharge guide 78 is fixed by being coupled to the rotary shaft 621 portion of the pressure roll 62 at the tip end portion 782a. Further, by adopting this form, the paper discharge guide 78 can be rotated around the tip end portion 782a. In a normal state, the paper discharge guide 78 is fixed at a predetermined position to be described later. However, when a paper jam or the like occurs in the vicinity of the paper discharge guide 78, the paper discharge guide 78 can be retracted by rotating the paper discharge guide 78 around the leading end 782a from the fixed position. . Then, after the paper discharge guide 78 is retracted, the jammed paper P can be removed.

FIGS. 5A to 5C are diagrams illustrating the peeling member 790 attached to the paper discharge guide 78.
Here, Fig.5 (a) is a figure at the time of seeing the peeling member 790 from the IIIa direction in FIG. FIG. 5B is a view when the peeling member 790 is viewed from the IVb direction in FIG. Further, FIG. 5C is a sectional view of the peeling member 790 taken along IVc-IVc in FIG.
As shown in FIG. 5A, the peeling member 790 includes a claw portion 791 for peeling the paper P attached to the pressure roll 62 and a support portion 792 for attaching the claw portion 791 to the paper discharge guide 78. The main part is composed.
In this embodiment, the claw portion 791 is urged to the pressure roll 62 by an elastic member such as a spring member (not shown). As a result, the claw portion 791 comes into contact with and closely contacts the pressure roll 62 with a predetermined pressure. When the paper P attached to the pressure roll 62 is conveyed in this state, the tip of the claw portion 791 enters between the pressure roll 62 and the paper P. Thereby, the paper P can be peeled from the pressure roll 62. The peeled paper P is guided by the upper surface of the claw portion 791 and sent to the guide plate 781.

  Further, an upper surface 793 that is a surface that contacts the paper P of the claw portion 791 is formed with a step. That is, as shown in FIGS. 5A and 5C, the upper surface 793 of the claw portion 791 includes a high step portion 793a having a surface for separating the paper P from the pressure roll 62 and a high step portion 793a. It comprises a low step portion 793b as a recess formed at a low position. The high step portion 793 a is formed on the outer peripheral portion of the claw portion 791. The low step portion 793b is formed in a portion other than the outer peripheral portion of the claw portion 791. That is, the high step portion 793a guides the paper P by contacting the paper P, while the low step portion 793b does not normally contact the paper P. With such a configuration, a part of the upper surface 793 of the claw portion 791 comes into contact with the paper P. As a result, the paper P peeled from the pressure roll 62 can be guided more smoothly. Since the paper P can be guided more smoothly, damage such as scratches that occur when the paper P is peeled off by the claw portion 791 is less likely to occur.

  Further, the upper surface 793 of the claw portion 791 is formed with a bent portion 794 in a direction orthogonal to the transport direction of the paper P. That is, as shown in FIG. 5B, for example, the high step portion 793a of the claw portion 791 is a surface that is a first surface that guides the paper P by contacting the paper P with the bent portion 794 as a boundary. 794a and a surface 794b which is a second surface bent downward with respect to the surface 794a. In other words, the surface 794b can be said to be bent toward the pressure roll 62 side. Thus, by providing the two surfaces on the upper surface 793 with the bent portion 794 as a boundary, the surface in contact with the paper P is further reduced. That is, by adopting such a configuration, the portion where the upper surface of the claw portion 791 is in contact with the normal paper P is limited to the portion of the high step portion 793a and the portion of the surface 794a. In this way, by further limiting the portion in contact with the normal paper P, the paper P peeled off from the pressure roll 62 can be guided more smoothly. Since the paper P can be guided more smoothly, damage such as scratches that occur when the paper P is peeled off by the claw portion 791 is further less likely to occur. In the present embodiment, the angle θ formed by the surface 794a and the surface 794b is, for example, 190 °.

  Further, in this embodiment, the lower surface 795 that is a surface that contacts the pressure roll 62 of the claw portion 791 has both end portions when viewed from the direction in which the paper P passes, as shown in FIG. It curves so that it may distance from the pressure roll 62 with respect to the center part. That is, it has a downwardly convex shape when viewed in the direction of FIG. By doing in this way, the contact area of the nail | claw part 791 and the pressurization roll 62 reduces. As a result, the claw portion 791 can easily enter between the paper P and the pressure roll 62, and the operation of separating the paper P from the pressure roll 62 can be performed more reliably.

FIG. 6 is a diagram illustrating the operation when the paper P is peeled from the pressure roll 62 by the peeling member 790 in more detail.
As shown in FIG. 6, the peeling member 790 is attached to the attachment portion 785 of the guide plate 781. And the peeling member 790 will be in the state which can rotate in this part. Further, this portion is biased toward the pressure roll 62 by an elastic member (not shown) such as a spring member. As a result, the peeling member 790 comes into contact with the pressure roll 62. In this embodiment, the tip of the claw portion 791 of the peeling member 790 comes into contact with the pressure roll 62. In addition, the guide plate 781 has a bent portion 784 in this embodiment. That is, the guide plate 781 is configured to have a surface 784a that is a first surface and a surface 784b that is a second surface, with the bent portion 784 as a boundary. The surface 784a and the surface 784b have different angles, and the surface 784a is bent toward the pressure roll 62 with respect to the surface 784b to be bent. In this state, the surface 784a and the peeling member 790 interfere with each other. Therefore, a notch 783 (see FIG. 3) is provided in the guide plate 781 to avoid interference between the surface 784a and the peeling member 790. That is, the peeling member 790 enters a notch 783 provided in the guide plate 781 when the claw 791 is in contact with the pressure roll 62.

In the present embodiment, when the paper P attached to the pressure roll 62 is conveyed, first, the leading end of the claw portion 791 of the peeling member 790 enters between the pressure roll 62 and the leading end of the paper P, The paper P is peeled from the pressure roll 62. Next, the peeled paper P is guided by the surface 794 a which is the first surface of the peeling member 790 and is conveyed in the direction of the guide plate 781.
In this embodiment, the bent portion 784 of the guide plate 781 is arranged so as to be positioned on the extension of the surface 794a of the peeling member 790 at this time. In FIG. 6, the plane formed by the surface 794a is indicated by a dotted line. The paper P peeled from the pressure roll 62 and guided to the surface 794a of the peeling member 790 comes into contact with the bent portion 784 of the guide plate 781, and is further conveyed by being guided by the surface 784b of the guide plate 781. .
Further, since the surface 784a of the guide plate 781 is bent toward the pressure roll 62, the sheet P can be conveyed even when the leading end portion of the sheet P is conveyed toward the pressure roll 62. it can. That is, even when the paper P is directed to the pressure roll 62 side, since the surface 784a of the guide plate 781 is close to the pressure roll 62 side, the leading edge of the paper P can be lifted by the surface 784a. In this case, the sheet P is guided and conveyed by the surface 784a, the bent portion 784, and the surface 784b of the sheet-fitting guide plate 781. That is, by configuring the guide plate 781 as described above, the paper P can be guided more smoothly.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 60 ... Fixing unit, 61 ... Fixing belt module, 62 ... Pressure roll, 64 ... Peeling pad, 78 ... Discharge guide, 611 ... Fixing roll, 612 ... Internal heating roll, 613 ... External heating roll 781 ... Guide plate, 784,794 ... Bent part, 784a, 784b, 794a, 794b ... Surface, 790 ... Peeling member, 791 ... Claw part, 793a ... High step part, 793b ... Low step part, N ... Nip part, P ... paper

Claims (6)

A fixing member for fixing a toner image on a recording material;
A pressure member that forms a fixing pressure part for allowing a recording material holding an unfixed toner image to pass between the fixing member and the outer peripheral surface of the fixing member by pressure contact;
A tension member that is disposed opposite the pressure member across the fixing member, and stretches the fixing member;
A first release member that is disposed in a downstream region of the fixing pressure unit and is adjacent to the stretching member and separates the recording material from the fixing member;
A second peeling member disposed in contact with the pressure member and having a claw portion for peeling the recording material attached to the pressure member;
The fixing device according to claim 1, wherein the claw portion of the second peeling member has a bent portion on a surface that guides the peeled recording material.   The claw portion has a first surface that guides the recording material by contacting the recording material with the bent portion as a boundary, and a second surface that bends toward the pressure member side with respect to the first surface. The fixing device according to claim 1, further comprising a surface.   The fixing device according to claim 1, wherein the claw portion has a concave portion in a portion other than an outer peripheral portion of a surface on a side for guiding the recording material.   When the claw portion is viewed from the direction in which the recording material passes, both end portions of the surface where the claw portion contacts the pressure member are moved away from the pressure member with respect to the central portion. The fixing device according to claim 1, wherein the fixing device is curved. A paper discharge guide member that holds the peeling member and is coupled to a rotation shaft of the pressure member;
5. The sheet discharge guide member according to claim 1, wherein the sheet discharge guide member is positioned on an extension of the first surface of the peeling member and has a bent portion for guiding the recording material. The fixing device described. Toner image forming means for forming a toner image;
Transfer means for transferring the toner image formed by the toner image forming means onto a recording material;
A fixing member for fixing the toner image on the recording material, and a fixing pressure unit for allowing the recording material holding the unfixed toner image to pass between the fixing member and the outer peripheral surface of the fixing member. A pressure member to be formed, a tension member that is disposed opposite to the pressure member with the fixing member interposed therebetween, and stretches the fixing member; A first peeling member disposed at a position adjacent to the first peeling member and peeling the recording material from the fixing member;
A second peeling member disposed in contact with the pressure member and having a claw portion for peeling the recording material attached to the pressure member;
The image forming apparatus according to claim 1, wherein the claw portion of the second peeling member has a bent portion on a surface that guides the peeled recording material.

Images