JP2014122101A - Curl correction device and image formation apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transport a sheet with front and rear portions of a curl corrected portion stabilized in a curl correction device rotatable so as to correct a curl of the sheet and an image formation apparatus including the curl correction device.SOLUTION: A curl correction device 7 includes: a correction unit 70; and a lower housing 73. The correction unit 70 includes inside: an elastic roller 701 and a hard roller 702. A curl of a sheet is corrected in nip parts between the elastic roller 701 and the hard roller 702. The lower housing 73 includes lower entry ribs 731B. The lower entry ribs 731B are arranged to enter the correction unit 70 inward of an outer peripheral portion of the correction unit 70, and guide the sheet. The correction unit 70 also includes first notches 705A1. The first notches 705A1 are formed by partially notching the outer peripheral portion of the correction unit 70 to be opposed to the lower entry ribs 731B.

Description

  The present invention relates to a curl correction apparatus for correcting sheet curl and an image forming apparatus including the curl correction apparatus.

  Conventionally, a technique described in Patent Document 1 is known as a curl correction device that corrects curl of a sheet. This curl correcting device is disposed downstream of the fixing unit in the sheet conveying direction in the image forming apparatus. In the image forming apparatus, since the toner image transferred onto the sheet is subjected to fixing processing, the sheet is passed through the fixing unit. In the fixing unit, the heated and pressurized sheet is likely to curl. When the sheet is curled, the capacity of the sheet discharged to the discharge unit of the image forming apparatus is deteriorated.

  Patent Document 1 discloses a curl correction apparatus for dealing with both the upper curl in which the leading end of the sheet warps upward and the lower curl in which the leading end of the sheet warps downward. A technique that can be reversed up and down is disclosed.

JP 2011-219270 A

  In the curl correction apparatus described in Patent Document 1, the curl of the sheet is corrected at the nip portion between the hard roller and the elastic roller. The hard roller and the elastic roller are supported by a rotatable rotating unit. In this case, when the curled sheet is carried into the curl correcting device, the curled sheet may enter the outer peripheral portion of the rotating unit without being carried into the nip portion, and the sheet may be jammed.

  The present invention has been made in order to solve the above-described problems. In a curl correction device that can be rotated to correct a curl of a sheet and an image forming apparatus including the curl correction device, the sheet is curled. It is intended to be stably conveyed before and after the section.

  A curl straightening device according to an aspect of the present invention includes a first rotation shaft, is rotated around the first rotation shaft, and is elastically deformable, and a second rotation parallel to the first rotation shaft. A second shaft that includes a shaft, is rotated about the second rotation shaft, is elastically deformed by being pressed by the first roller, and forms a curved nip portion with the first roller; A roller, a sheet conveyance path in which a sheet is conveyed in a predetermined sheet conveyance direction while passing through the nip portion, and the first and second rollers by pivotally supporting the first and second rotation shafts. A support unit that is rotatably supported and includes a third rotating shaft disposed in parallel to the first rotating shaft and an outer peripheral portion, and is supported by the apparatus main body so as to be rotatable around the third rotating shaft; The sheet transport direction of the support unit A guide part that is arranged on the flow side or downstream side and guides the sheet toward the support unit or guides the sheet carried out from the support unit; and the support unit rather than the outer peripheral part of the support unit A rib member that projects from the guide portion along the sheet conveying direction so as to enter the inside of the sheet, and the outer peripheral portion of the support unit is partially opposed to the rib member. It is formed by notching, and has a notch part through which the rib member passes with the rotation of the support unit.

  According to this configuration, the curl of the sheet is corrected at the nip portion formed between the first roller and the second roller in the support unit as the curl correction portion. The guide unit is disposed on the upstream side or the downstream side in the sheet conveyance direction of the support unit, and guides the sheet toward the support unit. Or a guide part guides the sheet carried out from the support unit. The rib member protrudes from the guide portion along the sheet conveyance direction so as to enter the inside of the support unit from the outer peripheral portion of the support unit. The notch is formed by partially notching the outer periphery of the support unit so as to face the rib member. And a rib member passes a notch part with rotation of a support unit. Therefore, the sheet is stably conveyed between the guide unit and the support unit including the curl correction unit. In addition, the sheet is prevented from being conveyed along the outer periphery of the support unit.

  In the above configuration, the support unit includes a pair of guide plates that extend from the outer peripheral portion toward the nip portion so as to sandwich the sheet conveyance path and guide the sheet, and the notch portion includes the notch portion. It is desirable that the guide plate be formed.

  In the above configuration, it is preferable that a plurality of the rib members and the notch portions are arranged along a sheet width direction intersecting the sheet conveying direction.

  In the above configuration, it is desirable that the plurality of rib members be able to appear and retract with respect to the sheet conveyance path.

  In the above-described configuration, the guide portion includes a plurality of openings that are opened along the sheet width direction, and the plurality of rib members can be projected and retracted from the plurality of openings, respectively, with respect to the sheet conveyance path. It is desirable that

  Said structure WHEREIN: The protrusion amount with respect to the said sheet conveyance path of the said rib member arrange | positioned in the center part of the said sheet width direction among these rib members is the said rib member arrange | positioned at the edge part of the said sheet width direction. It is desirable that the protrusion amount is larger than the protrusion amount of the sheet conveyance path.

  Said structure WHEREIN: The protrusion amount with respect to the said sheet conveyance path of the said rib member arrange | positioned in the center part of the said sheet width direction among these rib members is the said rib member arrange | positioned at the edge part of the said sheet width direction. It is desirable that the protrusion amount is smaller than the protrusion amount with respect to the sheet conveyance path.

  In the above-described configuration, the plurality of rib members each including a shaft portion that extends in the sheet width direction, and a stretching portion that is rotatable around the shaft portion and can protrude and retract with respect to the sheet conveyance path, A shaft extending in the sheet width direction and rotatable; a plurality of cam members fixed to the shaft facing the plurality of rib members; and abutting against the extending portions of the plurality of rib members; Drive means for rotationally driving, and when the cam member is rotated around the shaft, the plurality of rib members are rotated around the shaft portion and are projected and retracted with respect to the sheet conveying path. desirable.

  In the above configuration, it is preferable that the rib member is disposed at a position different from a position where both end edges in the sheet width direction of the sheet conveyed through the sheet conveyance path pass.

  According to this structure, it is suppressed that a rib member contacts the both ends of a sheet | seat, and it is prevented that conveyance of a sheet | seat is prevented.

  An image forming apparatus according to another aspect of the present invention includes the curl correction apparatus according to any one of the above, and an image forming unit that is disposed in the sheet conveyance path and forms an image on the sheet. And

  According to this configuration, in the image forming apparatus, the sheet is stably conveyed between the guide unit and the support unit including the curl correction unit. In addition, the sheet is prevented from being conveyed along the outer periphery of the support unit.

  In the above configuration, the image forming unit includes a transfer unit that transfers a toner image to a sheet, and a fixing unit that performs a fixing process on the sheet of the toner image. Also, it is desirable to dispose on the downstream side in the sheet conveying direction.

  According to this configuration, even when the sheet subjected to the fixing process is curled, the sheet is stably conveyed between the guide unit and the support unit. In addition, the sheet is prevented from being conveyed along the outer periphery of the support unit. As a result, the curl of the sheet is preferably corrected by the curl correction device.

  In the above configuration, a sheet discharge unit that discharges the sheet subjected to the fixing process by the fixing unit and a predetermined interval from the sheet discharge unit are disposed, and the sheet is subjected to predetermined post-processing. It is preferable that the apparatus includes a post-processing device and a relay transport unit that transports the sheet from the paper discharge unit to the post-processing device, and the curl correction device is disposed in the relay transport unit.

  According to this configuration, the curl correction device can be arranged using the relay conveyance unit. Further, the curl of the sheet is stably corrected before the sheet reaches the post-processing apparatus.

  According to the present invention, in a curl correction apparatus that is rotatable to correct a sheet curl, and an image forming apparatus including the curl correction apparatus, the sheet is stably conveyed before and after the curl correction unit.

1 is a cross-sectional view illustrating an internal structure of an image forming apparatus according to an embodiment of the present invention. It is a typical sectional view of an image forming device for showing arrangement of a curl straightening device concerning an embodiment of the present invention. It is sectional drawing of the image forming apparatus for showing arrangement | positioning of the curl correction apparatus which concerns on embodiment of this invention. It is a perspective view of the correction unit which concerns on one Embodiment of this invention. It is a perspective view of the correction unit which concerns on one Embodiment of this invention. It is a perspective view of the curl correction apparatus which concerns on one Embodiment of this invention. It is a perspective view of the state where the correction unit concerning one embodiment of the present invention was attached to the 1st frame. It is a perspective view of the 2nd frame concerning one embodiment of the present invention. It is an expansion perspective view of the curl correction apparatus concerning one embodiment of the present invention. It is an expansion perspective view of the curl correction apparatus concerning one embodiment of the present invention. It is the perspective view which showed the correction unit and the lower housing. It is sectional drawing of a curl correction apparatus. It is the top view which showed the correction unit and the lower housing. It is an electrical block diagram in connection with the rotation drive of the correction unit. It is the side view (A) and (B) which showed the inside of the lower housing of the curl correction apparatus which concerns on other embodiment of this invention. It is a perspective view of a cam and a movable rib.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an internal structure of an image forming apparatus 1 according to an embodiment of the present invention. Here, as the image forming apparatus 1, a multi-function machine having a printer function and a copying function is illustrated, but the image forming apparatus may be a printer, a copier, or a facsimile machine.

  <Description of Image Forming Apparatus>

  The image forming apparatus 1 includes an apparatus main body 10 having a substantially rectangular parallelepiped housing structure, and an automatic document feeder 20 disposed on the apparatus main body 10. In the apparatus main body 10, a reading unit 25 that optically reads a document image to be copied, an image forming unit 30 that forms a toner image on a sheet, a fixing unit 60 that fixes the toner image on a sheet, and image formation A sheet feeding unit 40 that stores a regular sheet conveyed to the unit 30, and a regular sheet is conveyed from the sheet feeding unit 40 or the manual sheet feeding unit 46 to the sheet discharge port 10E via the image forming unit 30 and the fixing unit 60. A conveyance path 50 and a conveyance unit 55 (relay conveyance unit) having a sheet conveyance path constituting a part of the conveyance path 50 inside are accommodated.

  An automatic document feeder (ADF) 20 is rotatably attached to the upper surface of the apparatus body 10. The ADF 20 automatically feeds a document sheet to be copied toward a predetermined document reading position in the apparatus main body 10.

  The reading unit 25 passes through a contact glass for reading a document sheet automatically fed from the ADF 20 on the upper surface of the apparatus body 10 or a contact glass (not shown) for reading a manually placed document sheet. Is read optically. In the reading unit 25, a scanning mechanism including a light source, a movable carriage, a reflection mirror, and the like, and an image sensor are accommodated (not shown).

  The image forming unit 30 performs a process of generating a full-color toner image and transferring it onto a sheet. Yellow (Y), magenta (M), cyan (C), and black (Bk) arranged in tandem. An image forming unit 32 including four units 32Y, 32M, 32C, and 32Bk for forming the respective toner images, an intermediate transfer unit 33 disposed adjacent to the image forming unit 32, and an intermediate transfer unit 33. And a toner replenishing section 34 disposed in the.

  Each of the image forming units 32Y, 32M, 32C, and 32Bk includes a photosensitive drum 321 and a charger 322, an exposure device 323, a developing device 324, a primary transfer roller 325, and a cleaning device disposed around the photosensitive drum 321. 326.

  The photosensitive drum 321 rotates about its axis, and an electrostatic latent image and a toner image are formed on its peripheral surface. As the photosensitive drum 321, a photosensitive drum using an amorphous silicon (a-Si) material can be used. The charger 322 uniformly charges the surface of the photosensitive drum 321. The exposure device 323 includes a laser light source and optical system devices such as a mirror and a lens, and forms an electrostatic latent image by irradiating the peripheral surface of the photosensitive drum 321 with light based on image data of a document image. .

  The developing device 324 supplies toner to the peripheral surface of the photosensitive drum 321 in order to develop the electrostatic latent image formed on the photosensitive drum 321.

  The primary transfer roller 325 forms a primary transfer nip portion with the photosensitive drum 321 across the intermediate transfer belt 331 provided in the intermediate transfer unit 33, and the toner image on the photosensitive drum 321 is transferred onto the intermediate transfer belt 331. Primary transfer. The cleaning device 326 includes a cleaning roller and the like, and cleans the peripheral surface of the photosensitive drum 321 after the toner image is transferred.

  The intermediate transfer unit 33 includes an intermediate transfer belt 331, a driving roller 332, and a driven roller 333. The intermediate transfer belt 331 is an endless belt that is stretched around a driving roller 332 and a driven roller 333, and toner images from a plurality of photosensitive drums 321 are superimposed on the same portion on the outer peripheral surface of the intermediate transfer belt 331. Are transferred (primary transfer).

  A secondary transfer roller 35 (transfer means) is disposed facing the peripheral surface of the drive roller 332. At the secondary transfer nip portion between the driving roller 332 and the secondary transfer roller 35, the full-color toner image overcoated on the intermediate transfer belt 331 is transferred onto the sheet.

  The toner supply unit 34 includes a yellow toner container 34Y, a magenta toner container 34M, a cyan toner container 34C, and a black toner container 34Bk. These toner containers 34Y, 34C, 34M, and 34Bk respectively store toner of each color, and are supplied to the developing devices 324 of the image forming units 32Y, 32M, 32C, and 32Bk corresponding to each color of YMCBk through a supply path (not shown). Supply toner of each color.

  The sheet feeding unit 40 includes a two-stage first sheet feeding cassette 40A and a second sheet feeding cassette 40B that store a standard sheet P among sheets subjected to image forming processing. These paper feed cassettes can be pulled out from the front of the apparatus body 10 toward the front.

  The first sheet cassette 40A includes a sheet storage unit 41 that stores a sheet bundle formed by stacking fixed sheets P. By driving the pickup roller 43 and the sheet feeding roller 44, the uppermost sheet P of the sheet bundle in the sheet feeding cassette 40 </ b> A is fed out one by one and carried to the upstream end of the conveyance path 50. The second paper feed cassette 40B has the same configuration as the first paper feed cassette 40A.

  A manual feed tray 46 is disposed on the right side surface 10 </ b> R of the apparatus main body 10. A paper feed roller 461 is disposed in the vicinity of the manual feed tray 46. The manual feed tray 46 is attached to the apparatus main body 10 at its lower end so as to be freely opened and closed.

  The conveyance path 50 includes a main conveyance path 50A that conveys the sheet P from the paper feeding unit 40 to the exit of the fixing unit 60 through the image forming unit 30, and a sheet that is printed on one side when performing duplex printing on the sheet. A reverse conveyance path 50B for returning the sheet to the image forming unit 30, a switchback conveyance path 50C for directing the sheet from the downstream end of the main conveyance path 50A to the upstream end of the reverse conveyance path 50B, and the downstream of the main conveyance path 50A. A horizontal conveyance path 50D (sheet conveyance path) that conveys the sheet in the horizontal direction from the end to the sheet discharge port 10E provided on the left side surface 10L of the apparatus main body 10. Most of the horizontal conveyance path 50 </ b> D is configured by a sheet conveyance path provided inside the conveyance unit 55.

  A registration roller pair 51 is disposed on the upstream side of the secondary transfer nip portion of the main conveyance path 50A. The sheet is temporarily stopped by the resist roller pair 51 in a stopped state, and skew correction is performed. Thereafter, the registration roller pair 51 is rotationally driven by a drive unit (not shown) at a predetermined timing for image transfer, whereby the sheet is sent out to the secondary transfer nip portion. In addition, a plurality of sheet conveyance rollers 52 for conveying the sheet are arranged in the main conveyance path 50A.

  A paper discharge roller 53 is disposed at the most downstream end of the transport path 50. The paper discharge roller 53 feeds the sheet through a sheet discharge port 10E to a post-processing device described later disposed on the left side surface 10L of the apparatus main body 10. In the image forming apparatus to which the post-processing apparatus is not attached, a sheet discharge tray 10TR (FIG. 2) described later is provided below the sheet discharge port 10E.

  The transport unit 55 is a unit that transports the sheet unloaded from the fixing unit 60 to the sheet discharge port 10E. In the image forming apparatus 1 of the present embodiment, the fixing unit 60 is disposed on the right side 10R side of the apparatus main body 10, and the sheet discharge port 10E is disposed on the left side 10L side of the apparatus main body 10 facing the right side 10R. Yes. Accordingly, the transport unit 55 transports the sheet in the horizontal direction from the right side surface 10R of the apparatus main body 10 toward the left side surface 10L. The transport unit 55 can be attached to the apparatus main body 10 and constitutes a part of the apparatus main body.

  The image forming apparatus 1 further includes a post-processing device (not shown). As described above, the post-processing apparatus is disposed on the left side surface 10L of the apparatus main body 10. The post-processing device receives the sheet from the sheet discharge port 10E, performs a predetermined post-processing on the sheet, and then stacks the sheet. The post-processing for the sheet includes stapling processing, booklet binding processing, and the like.

  The fixing unit 60 is an induction heating type fixing device that performs a fixing process for fixing a toner image on a sheet, and includes a heating roller 61, a fixing roller 62, a pressure roller 63, a fixing belt 64, and an induction heating unit 65. A pressure roller 63 is pressed against the fixing roller 62 to form a fixing nip portion. As the sheet passes through the fixing nip portion, the toner image transferred to the sheet is fixed to the sheet.

  Further, the image forming apparatus 1 includes a curl correction device 7. 2 and 3 are schematic cross-sectional views showing the arrangement of the curl correction device 7 in the image forming apparatus 1. 3 is a cross-sectional view showing the positional relationship among the intermediate transfer unit 33, the fixing unit 60, the curl correction device 7, and the transport unit 55 in the image forming apparatus 1. The curl correction device 7 has a function of correcting (curling) the sheet curl. The curl correction device 7 is disposed inside the transport unit 55 on the upstream side in the sheet transport direction. The sheet subjected to the fixing process in the fixing unit 60 is conveyed to the conveyance unit 55 by a conveyance roller pair 50 </ b> R (paper discharge unit) disposed on the downstream side of the fixing unit 60. The curl correction device 7 corrects the curl of the sheet delivered from the conveyance roller pair 50 </ b> R, and then conveys the sheet to the downstream roller pair 55 </ b> R disposed in the conveyance unit 55. The downstream roller pair 55 </ b> R is disposed in the horizontal conveyance path 50 </ b> D downstream of the curl correction device 7 in the sheet conveyance direction. The downstream roller pair 55R includes a first downstream roller 55R1 and a second downstream roller 55R2. The sheet conveyed from the curl correction device 7 is conveyed toward the sheet discharge port 10E while being sandwiched between the first downstream roller 55R1 and the second downstream roller 55R2. Thereafter, the sheet P is discharged to the sheet discharge tray 10TR or the above-described post-processing device.

  When the fixing process is performed on the sheet in the fixing unit 60, the sheet is heated by the fixing roller 62. Further, the sheet is pressed toward the fixing roller 62 by the pressure roller 63. At this time, the toner image is fixed on the surface of the sheet on the fixing roller 62 side. When the toner image is shrunk by heat, the sheet faces the fixing roller 62 (first surface) on the inner peripheral side, and the side facing the pressure roller 63 (second surface) on the outer peripheral side. It is easy to curl (curvature). When the sheet is curled, the capacity of the sheet discharged onto the sheet discharge tray 10TR or the post-processing apparatus is deteriorated. The curl correction device 7 corrects the curl, so that the storage capacity of the sheet is stably maintained.

  Next, the curl correction apparatus 7 according to the first embodiment of the present invention will be described in detail with reference to FIGS. The curl correction device 7 includes a correction unit 70 (support unit), a first frame 71, and a second frame 72. 4 and 5 are perspective views of the correction unit 70 according to this embodiment. FIG. 6 is a perspective view of the curl correction apparatus 7 according to the present embodiment. FIG. 7 is a perspective view of the state in which the correction unit 70 is mounted on the first frame 71. FIG. 8 is a perspective view of the second frame 72. FIGS. 9 and 10 are enlarged perspective views of the curl correction device 7. FIG. 11 is a perspective view showing a state in which the correction unit 70 is mounted on the lower housing 73. FIG. 12 is a cross-sectional view of the curl correction device 7. Further, FIG. 13 is a plan view of a state in which the correction unit 70 is mounted on the lower housing 73.

  The correction unit 70 is a main body portion of the curl correction device 7. The correction unit 70 is attached to a first frame 71 and a second frame 72 described later on the rear side of the transport unit 55. The correction unit 70 is also attached to a frame (not shown) on the front side of the transport unit 55. The correction unit 70 has a substantially cylindrical shape that extends in the front-rear direction. The correction unit 70 includes an outer peripheral portion 70A (see FIG. 12). Further, the correction unit 70 includes a unit shaft 700 (third rotation shaft). The unit shaft 700 becomes a rotation shaft in the rotation of the correction unit 70. The unit shaft 700 is a shaft portion that extends in the front-rear direction at the center of the correction unit 70. The unit shaft 700 is disposed in parallel with the elastic roller shaft 701A between an elastic roller shaft 701A and a hard roller shaft 702A described later. Further, the correction unit 70 includes an elastic roller 701 (first roller), a hard roller 702 (second roller), a rear flange portion 703, a front flange portion 704, a first guide portion 705, and a second guide portion. 706.

  The elastic roller 701 is rotated around an elastic roller shaft 701A (first rotation shaft), and can be elastically deformed. The elastic roller shaft 701 </ b> A serves as a rotation shaft in the rotation of the elastic roller 701. The elastic roller 701 is rotatably supported by a rear flange portion 703 and a front flange portion 704 described later. The elastic roller 701 is a roller member arranged around the elastic roller shaft 701A. A plurality of elastic rollers 701 are arranged at intervals in the axial direction (front-rear direction) of the elastic roller shaft 701A. In the present embodiment, the elastic roller 701 is made of a rubber member.

  The hard roller 702 is rotated around a hard roller shaft 702A (second rotation shaft) parallel to the elastic roller shaft 701A. The hard roller shaft 702A serves as a rotation shaft in the rotation of the hard roller 702. The hard roller 702 is rotatably supported by a rear flange portion 703 and a front flange portion 704 described later. The hard roller 702 is a metal roller. In the present embodiment, the hard roller 702 is made of a stainless material. The hard roller 702 is elastically deformed by being pressed by the elastic roller 701. As a result, a nip portion N through which the sheet passes is formed between the elastic roller 701 and the hard roller 702 (see FIG. 12). The nip portion N functions as a curl correction portion that corrects the curl of the sheet P. When the elastic roller 701 is elastically deformed, the nip portion N has a curved shape along the peripheral surface of the hard roller 702. The horizontal conveyance path 50D described above includes a nip portion N. The sheet is conveyed in a predetermined sheet conveyance direction (from right to left) in the horizontal conveyance path 50D while passing through the nip portion N.

  The rear flange portion 703 is a side wall portion that is disposed orthogonal to the unit shaft 700 at the rear end portion of the correction unit 70. The rear flange portion 703 is composed of two wall portions arranged at intervals in the front-rear direction. Specifically, the rear flange portion 703 includes a first rear flange 703A and a second rear flange 703B. The first rear flange 703 </ b> A is a wall portion disposed on the outer side in the axial direction of the rear flange portion 703. The second rear flange 703 </ b> B is a wall portion disposed on the inner side in the axial direction of the rear flange portion 703. As shown in FIG. 4, the first rear flange 703 </ b> A has a shape in which a part in the circumferential direction is partially cut into a fan shape. The first rear flange 703A and the second rear flange 703B are connected by a plurality of connecting rods (not shown) arranged at intervals in the circumferential direction. Further, an outer peripheral gear portion 703G (FIG. 5) composed of a plurality of gear teeth is disposed on the outer peripheral portion of the first rear flange 703A. The outer peripheral gear portion 703G is engaged with a first drive shaft 721A described later, whereby a rotational driving force for rotating the correction unit 70 is transmitted to the outer peripheral gear portion 703G.

  The front flange portion 704 is a side wall portion that is disposed orthogonal to the unit shaft 700 at the front end portion of the correction unit 70. The front flange portion 704 is composed of two wall portions arranged at intervals in the front-rear direction. Specifically, the front flange portion 704 includes a first front flange 704A and a second front flange 704B. The first front flange 704 </ b> A is a wall portion that is disposed outside the front flange portion 704 in the axial direction. The second front flange 704 </ b> B is a wall portion disposed on the inner side in the axial direction of the front flange portion 704. The first front flange 704A and the second front flange 704B are connected by a plurality of connecting rods (not shown) arranged at intervals in the circumferential direction.

  The first guide portion 705 is a pair of plate-like members extending between the second rear flange 703B and the second front flange 704B. Specifically, the first guide portion 705 includes an eleventh guide 705A and a twelfth guide 705B (both are guide plates). The first guide unit 705 has a function of guiding the sheet conveyed through the horizontal conveyance path 50D to the nip N. The first guide unit 705 has a function of guiding the sheet carried out from the nip N to the horizontal conveyance path 50D again. At this time, the sheet is conveyed between the eleventh guide 705A and the twelfth guide 705B. In other words, the pair of the eleventh guide 705A and the twelfth guide 705B are extended from the outer peripheral portion 70A of the correction unit 70 toward the nip portion N so as to sandwich the horizontal conveyance path 50D and guide the sheet.

  The second guide portion 706 is a pair of plate-like members extending between the second rear flange 703B and the second front flange 704B. Specifically, the second guide portion 706 includes a 21st guide 706A and a 22nd guide 706B (both are guide plates). The second guide unit 706 has a function of guiding the sheet conveyed through the horizontal conveyance path 50D to the nip N. Further, the second guide unit 706 has a function of guiding the sheet carried out from the nip N to the horizontal conveyance path 50D again. At this time, the sheet is conveyed between the 21st guide 706A and the 22nd guide 706B. In other words, the pair of 21st guide 706A and 22nd guide 706B are extended from the outer peripheral portion 70A of the correction unit 70 toward the nip portion N so as to sandwich the horizontal conveyance path 50D and guide the sheet.

  In other words, the correction unit 70 supports the elastic roller 701 and the hard roller 702 rotatably by supporting the elastic roller shaft 701A and the hard roller shaft 702A. The correction unit 70 includes a unit shaft 700 disposed in parallel with the elastic roller shaft 701A between the elastic roller shaft 701A and the hard roller shaft 702A. The correction unit 70 is rotatable around the unit axis 700.

  Further, the correction unit 70 includes an input gear 707, a relay gear 708, and a transmission gear 709 (FIG. 5).

  The input gear 707 is a gear disposed on the unit shaft 700 on the outer side in the axial direction of the first rear flange 703A. The input gear 707 is rotatable with respect to the unit shaft 700. The unit shaft 700 is connected to a second drive shaft 722A described later.

  The relay gear 708 is a gear portion that is disposed in the aforementioned notch portion of the first rear flange 703A. The relay gear 708 is rotatably supported by the second rear flange 703B. The relay gear 708 includes a first relay gear portion 708A and a second relay gear portion 708B. The first relay gear portion 708A and the second relay gear portion 708B are gear portions disposed adjacent to each other in the axial direction. The first relay gear portion 708A is engaged with the input gear 707. The second relay gear portion 708B is engaged with a transmission gear 709 described later. The relay gear 708 receives the rotational driving force from the input gear 707 and transmits the rotational driving force to the transmission gear 709.

  The transmission gear 709 is a gear fixed to the hard roller shaft 702A between the first rear flange 703A and the second rear flange 703B. The transmission gear 709 is rotated integrally with the hard roller shaft 702A. When the rotational driving force is transmitted from the relay gear 708 to the transmission gear 709, the hard roller 702 is rotated by the rotational driving force. As the hard roller 702 rotates, the elastic roller 701 is driven by the hard roller 702 and rotated.

  Referring to FIGS. 9 and 10, the first frame 71 supports the correction unit 70 rotatably on the rear side of the correction unit 70. The correction unit 70 is attached to the first frame 71 in the direction of the arrow D61 in FIG. The first frame 71 is a plate-like member facing in the front-rear direction, and an upper portion of the first frame 71 is bent forward. The first frame 71 includes a rotary shaft 711, a rotary gear 712, a unit bearing portion 71R, and an opening portion 71G. The rotary shaft 711 is a central portion in the vertical direction of the first frame 71 and is a shaft portion that protrudes forward in the left end portion of the first frame 71. A rotary gear 712 is attached to the rotary shaft 711.

  The rotary gear 712 is a gear that is rotatably supported by the rotary shaft 711. The rotary gear 712 includes a first gear portion 712A and a second gear portion 712B. The first gear portion 712A and the second gear portion 712B are gear portions adjacent in the front-rear direction. The first gear portion 712A is engaged with a first drive shaft 721A described later. Further, the second gear portion 712B is engaged with the outer peripheral gear portion 703G of the correction unit 70. The rotary gear 712 has a function of transmitting a rotational driving force generated by a rotary motor 721 described later to the correction unit 70.

  The unit bearing portion 71R is a bearing portion disposed at the lower end portion and the right end portion of the first frame 71. The unit shaft 700 of the correction unit 70 is inserted into the unit bearing portion 71R. As a result, the correction unit 70 is rotatably supported by the first frame 71.

  The opening 71G is a long hole opened in the vertical direction above the unit bearing portion 71R. A second drive shaft 722A described later is inserted through the opening 71G.

  The second frame 72 supports the first frame 71. The first frame 71 is fixed to the second frame 72 by screws (not shown). The second frame 72 is a plate-like member that has a larger area than the first frame 71 and faces in the front-rear direction. The second frame 72 includes a rotary motor 721, a drive motor 722, a swing piece 75, and a detection sensor 76.

  The rotary motor 721 is disposed at the left end of the second frame 72 and on the rear surface of the second frame 72. The rotary motor 721 is a motor that generates a rotational driving force that rotates the correction unit 70 around the unit axis 700. The rotary motor 721 includes a first drive shaft 721A. The first drive shaft 721 </ b> A penetrates the second frame 72 and protrudes to the front side of the second frame 72. As described above, the first driving shaft 721 </ b> A is engaged with the first gear portion 712 </ b> A of the rotary gear 712, whereby the rotational driving force of the rotary motor 721 is transmitted to the rotary gear 712.

  The drive motor 722 is disposed on the rear surface of the second frame 72 slightly to the right of the center of the second frame 72. The drive motor 722 is a motor that generates a rotational driving force that rotates the hard roller 702 in the correction unit 70 around the hard roller shaft 702A. The drive motor 722 includes a second drive shaft 722A. The second drive shaft 722 </ b> A penetrates the second frame 72 and protrudes to the front side of the second frame 72. The second drive shaft 722 </ b> A penetrates the opening 71 </ b> G of the first frame 71 described above and protrudes to the front side of the first frame 71. The second drive shaft 722 </ b> A is engaged with the input gear 707 of the correction unit 70, thereby transmitting the rotational driving force of the drive motor 722 to the input gear 707. The rotational driving force is transmitted from the input gear 707 to the transmission gear 709 via the relay gear 708. As a result, the hard roller 702 is rotated by the rotational driving force of the drive motor 722. Since the input gear 707 is arranged coaxially with the unit shaft 700 of the correction unit 70, even when the correction unit 70 rotates, the rotational driving force is stably supplied from the second drive shaft 722A to the input gear 707. Is entered.

  The swing piece 75 (FIG. 8) is swingably disposed on the second frame 72 on the right side of the second drive shaft 722A. The swing piece 75 is a member having an L-shape when viewed from the front. The swing piece 75 includes a fulcrum part 751 and a detection piece 752. The fulcrum portion 751 is disposed at the upper end portion of the swing piece 75 and is fixed to a shaft portion protruding from the second frame 72. The fulcrum portion 751 serves as a rotation shaft in the swing of the swing piece 75. The detection piece 752 is disposed at the lower end portion of the swing piece 75 and extends toward the right. The detection piece 752 is moved to the right every rotation of the correction unit 70 and is detected by a detection sensor 76 described later.

  The detection sensor 76 is disposed on the right side of the swing piece 75. The detection sensor 76 is a sensor for detecting the detection piece 752. The detection sensor 76 includes a light emitting unit 761 and a light receiving unit 762. Detection light is emitted from the light emitting unit 761 toward the light receiving unit 762. When the detection light is blocked by the detection piece 752, the detection piece 752 is detected by the detection sensor 76. When the correction unit 70 is rotated once, the detection piece 752 is detected by the detection sensor 76 corresponding to a predetermined position on the circumference of the correction unit 70. Based on the detection timing, a counting unit 820 described later counts a step signal of the rotary motor 721. Then, based on the count, a drive control unit 810 described later adjusts the rotation angle of the rotary motor 721. As a result, the rotation angle of the correction unit 70 is controlled.

  With reference to FIGS. 11 to 13, the curl correction device 7 further includes a lower housing 73 and an upper housing 74. The lower housing 73 and the upper housing 74 are housing members that house the correction unit 70. As shown in FIG. 3, the lower housing 73 and the upper housing 74 each define a right portion (upstream portion in the sheet conveying direction) of the conveying unit 55.

  The lower housing 73 is disposed below the correction unit 70. The lower housing 73 includes a lower carry-in portion 731 (guide portion), a lower support portion 732, and a lower carry-out portion 733.

  The lower carry-in portion 731 is disposed below the horizontal conveyance path 50 </ b> D and upstream of the correction unit 70 in the sheet conveyance direction, and guides the sheet P toward the correction unit 70. The lower carry-in portion 731 includes a lower carry-in rib 731A and a lower entry rib 731B (rib member). The lower carry-in ribs 731 </ b> A are a plurality of rib members that are arranged at intervals in the sheet width direction intersecting the sheet conveyance direction on the upper surface portion of the lower carry-in portion 731. The lower carry-in rib 731A extends along the sheet width direction. The lower entry rib 731B is a rib member connected to a part of the plurality of lower carry-in ribs 731A. The lower entry rib 731B protrudes from the lower carry-in portion 731 along the sheet conveyance direction so as to enter the inside (the nip portion side) of the correction unit 70 from the outer peripheral portion 70A of the correction unit 70. The lower entry rib 731B guides the sheet toward the inside of the correction unit 70 and between the eleventh guide 705A and the twelfth guide 705B. Referring to FIG. 13, in the sheet width direction (front-rear direction), the positions where the lower carry-in rib 731A and the lower entry rib 731B are arranged are both ends of the sheet P conveyed in the horizontal conveyance path 50D in the sheet width direction. It is arranged at a position different from the position where the edge passes.

  The lower support portion 732 is disposed on the downstream side of the lower carry-in portion 731 in the sheet conveyance direction and below the correction unit 70. The lower support part 732 defines the lower part of the space in which the correction unit 70 rotates.

  The lower carry-out unit 733 is disposed downstream of the lower support unit 732 and the correction unit 70 in the sheet conveyance direction. The lower carry-out unit 733 guides the sheet P carried out from the nip N of the correction unit 70 toward the horizontal conveyance path 50D.

  The upper housing 74 is disposed above the correction unit 70. The upper housing 74 includes an upper carry-in portion 741 (guide portion), an upper support portion 742, and an upper carry-out portion 743 (guide portion).

  The upper carry-in unit 741 is disposed above the horizontal conveyance path 50 </ b> D and upstream of the correction unit 70 in the sheet conveyance direction, and guides the sheet P toward the correction unit 70. The upper carry-in portion 741 includes an upper carry-in rib 741A and an upper entry rib 741B (rib member). The upper carry-in ribs 741 </ b> A are a plurality of rib members that are arranged at intervals in the sheet width direction intersecting the sheet conveyance direction on the lower surface portion of the upper carry-in portion 741. The upper carry-in rib 741A extends along the sheet width direction. The upper entry rib 741B is a rib member that is connected to a part of the plurality of upper carry-in ribs 741A. The upper entry rib 741B protrudes from the upper carry-in portion 741 along the sheet conveyance direction so as to enter the inside (the nip portion side) of the correction unit 70 from the outer peripheral portion 70A of the correction unit 70. The upper entry rib 741B guides the sheet toward the inside of the correction unit 70 and between the eleventh guide 705A and the twelfth guide 705B. Similarly to the lower carry-in rib 731A and the lower entry rib 731B, the position at which the upper carry-in rib 741A and the upper entry rib 741B are arranged in the sheet width direction (front-rear direction) is the sheet P conveyed in the horizontal conveyance path 50D. The sheet is disposed at a position different from the position through which both end edges in the sheet width direction pass. Further, in the sheet width direction, the upper carry-in rib 741A and the upper entry rib 741B are disposed at positions facing the lower carry-in rib 731A and the lower entry rib 731B.

  The upper support portion 742 is disposed on the downstream side of the upper carry-in portion 741 in the sheet conveyance direction and above the correction unit 70. The upper support part 742 defines the upper part of the space in which the correction unit 70 rotates.

  The upper carry-out unit 743 is disposed downstream of the upper support unit 742 and the correction unit 70 in the sheet conveyance direction. The upper carry-out unit 743 guides the sheet P carried out from the nip portion N of the correction unit 70 toward the horizontal conveyance path 50D. The upper carry-out portion 743 includes a plurality of upper carry-out ribs 743A (rib members) arranged at intervals in the sheet width direction. The upper carry-out rib 743A protrudes from the upper carry-out portion 743 along the sheet conveyance direction so as to enter the inside (the nip portion side) of the correction unit 70 from the outer peripheral portion 70A of the correction unit 70. The upper carry-out rib 743A guides the sheet carried from the 21st guide 706A and the 22nd guide 706B to the horizontal conveyance path 50D inside the correction unit 70.

  Furthermore, with reference to FIGS. 11 and 13, the correction unit 70 includes a first notch 705A1 and a second notch 705B1 (both notched portions).

  The first notch 705A1 is a notch formed by partially notching the outer edge of the eleventh guide 705A in the outer peripheral part 70A of the correction unit 70. The first cutout portions 705A1 face the plurality of lower entry ribs 731B and are arranged in a plurality along the sheet width direction. As the correction unit 70 rotates around the unit axis 700, the first notch 705A1 passes inside the lower entry rib 731B (position where the lower entry rib 731B faces). Further, the notch 705A1 passes inside the upper entry rib 741B and the upper carry-out rib 743A as the correction unit 70 rotates. In other words, with the rotation of the correction unit 70, the upper entry rib 741B and the upper carry-out rib 743A pass through the first notch 705A1. Therefore, interference between the correction unit 70 and the upper carry-in rib 741A, the upper entry rib 741B, and the upper carry-out rib 743A that protrude so as to enter the inner side of the outer peripheral portion 70A of the correction unit 70 is suppressed. .

  Similarly, the second notch 705B1 is a notch formed by partially notching the outer edge of the twelfth guide 705B in the outer peripheral portion 70A of the correction unit 70. A plurality of second cutout portions 705B1 are arranged to face the plurality of upper entry ribs 741B. As the correction unit 70 rotates about the unit axis 700, the second notch 705B1 passes inside the lower entry rib 731B, the upper entry rib 741B, and the upper carry-out rib 743A. In other words, as the correction unit 70 rotates about the unit axis 700, the lower entry rib 731B, the upper entry rib 741B, and the upper carry-out rib 743A pass through the second notch 705B1. The 21st guide 706A and the 22nd guide 706B are also formed with similar notches.

  Next, the curl correction operation of the curl correction apparatus 7 according to this embodiment will be described. FIG. 14 is an electrical block diagram of the control unit 800. The control unit 800 controls the curl correction device 7 in an integrated manner. In addition to the detection sensor 76, the rotary motor 721, and the drive motor 722, the control unit 800 controls the curl amount detection sensor 77 (detection unit). Electrically connected.

  Referring to FIG. 2, the curl amount detection sensor 77 is disposed downstream of the fixing unit 60 in the sheet conveyance direction. The curl amount detection sensor 77 detects a characteristic value corresponding to the curl amount of the sheet. In the present embodiment, the curl amount detection sensor 77 is a distance measuring sensor disposed in the apparatus main body 10. The curl amount detection sensor 77 is disposed orthogonal to the sheet surface of the conveyed sheet. The curl amount detection sensor 77 is composed of a combination of a light emitting element and a light receiving element (not shown) based on a triangulation method. A semiconductor laser is used for the light emitting element. The light of the semiconductor laser is condensed through a light projection lens (not shown) and irradiated onto the sheet P. A part of the light beam diffusely reflected from the sheet P forms a spot on the light receiving element through a light receiving lens (not shown). As a result, the distance from the curl amount detection sensor 77 to the object is detected. The curl amount detection sensor 77 measures the distance (position) of the sheet surface at the front end, the center, and the rear end in the sheet conveyance direction. By previously fixing the position where the curl amount detection sensor 77 is mounted, the curl amount of the sheet is detected from the plurality of distances.

  The control unit 800 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) that is used as a work area of the CPU, and the CPU executes the control program. As a result, the drive control unit 810, the count unit 820, and the storage unit 830 are functionally operated.

  The drive control unit 810 controls the rotation of the correction unit 70 and the rotation of the hard roller 702 by controlling the rotary motor 721 and the drive motor 722.

  The counting unit 820 counts a pulse step signal for rotation of the rotary motor 721 based on the timing at which the detection sensor 76 detects the detection piece 752. Based on the count result of the count unit 820, the drive control unit 810 controls the rotation of the rotary motor 721. As a result, the rotation angle (rotation position) of the correction unit 70 is controlled.

  The storage unit 830 stores in advance a table for calculating the curl amount of the sheet P according to the characteristic value (distance) detected by the curl amount detection sensor 77. Based on the detection result of the curl amount detection sensor 77, the drive control unit 810 refers to the table stored in the storage unit 830 and derives the curl amount and curl direction of the sheet. Based on the curl amount and the curl direction, the rotation of the correction unit 70 and the rotation angle of the correction unit 70 are determined.

  Next, curl correction of the sheet P will be described with reference to FIGS. After the toner image is formed on the sheet P in the image forming unit 32, the fixing unit 60 performs fixing processing of the toner image on the sheet P. At this time, as described above, the sheet P is easily curled so that the first surface P (1) is the inner peripheral side and the second surface P (2) is the outer peripheral surface. In other words, as shown in FIG. 12, a so-called lower curl state in which the leading edge of the sheet P warps downward tends to occur. When the sheet P discharged from the fixing unit 60 passes through a position where the curl amount detection sensor 77 faces, the curl amount detection sensor 77 causes the leading end portion, the central portion, and the rear end portion of the sheet P to be conveyed, The distance from the curl amount detection sensor 77 is measured. Then, the drive control unit 810 detects the curl amount of the sheet P based on the measurement result of the curl amount detection sensor 77 and a table stored in the storage unit 830 in advance. Further, the lower or upper curl of the sheet P is determined by the drive control unit 810 based on the relationship between the plurality of distances detected by the curl amount detection sensor 77. When the sheet P is a lower curl, the drive control unit 810 arranges the correction unit 70 so that the elastic roller 701 is disposed below and the hard roller 702 is disposed above.

  That is, as shown in FIG. 12, when the sheet P is conveyed in a state of lower curl, the drive control unit 810 controls the rotation angle of the correction unit 70 in advance, and the elastic roller 701 moves the first position of the sheet P. The correction unit 70 is arranged such that the first roller P2 is in contact with the first surface P (1) and the hard roller 702 is in contact with the second surface P (2) of the sheet P. In addition, arrangement | positioning of this correction unit 70 is defined as a 1st attitude | position.

  The sheet P is conveyed into the correction unit 70 from between the lower carry-in portion 731 of the lower housing 73 and the upper carry-in portion 741 of the upper housing 74 (in the direction of arrow DP in FIG. 12). At this time, as described above, the lower entry rib 731 </ b> B and the upper entry rib 741 </ b> B are arranged so as to enter the inside of the outer peripheral portion 70 </ b> A of the correction unit 70. For this reason, the lower approach rib 731 </ b> B and the upper approach rib 741 </ b> B reliably carry the sheet P into the correction unit 70. In other words, the sheet P is prevented from entering the gap between the outer peripheral portion 70 </ b> A of the correction unit 70 and the lower support portion 732 or the upper support portion 742. In particular, as shown in FIG. 12, when the sheet P is in the lower curl state, the leading end portion of the sheet P easily enters the gap between the outer peripheral portion 70A of the correction unit 70 and the lower support portion 732 (FIG. 12). Arrow D121). In the present embodiment, the lower entry rib 731B suitably suppresses the sheet P from entering the gap. The sheet P carried into the correction unit 70 enters the nip portion N from between the eleventh guide 705A and the twelfth guide 705B. The nip portion N has a curved shape along the peripheral surface of the hard roller 702 disposed above when the elastic roller 701 disposed below is compressed and deformed. For this reason, the lower curl of the sheet P is preferably corrected along the curved surface of the nip portion N.

  The sheet P that has passed through the nip portion N is conveyed toward the outside of the correction unit 70 while passing between the 21st guide 706A and the 22nd guide 706B. At this time, as described above, the upper carry-out rib 743A protrudes from the upper carry-out portion 743 so as to enter inside the outer peripheral portion 70A of the correction unit 70. For this reason, the sheet P carried out from the correction unit 70 is prevented from entering the gap between the correction unit 70 and the upper support portion 742. In particular, in FIG. 12, along the peripheral surface of the hard roller 702, the leading end portion of the sheet P that is detached from the nip portion N is easily conveyed in a state of facing upward. Even in such a case, as described above, the upper carry-out rib 743A prevents the front end portion of the sheet P from being caught on the upper support portion 742 side.

  In the above-described embodiment, the sheet P is described as being conveyed to the curl correction device 7 in a state of lower curl. On the other hand, when the sheet P is curled so that the first surface P (1) is on the outer peripheral side and the second surface P (2) is on the inner peripheral side, in other words, the leading end of the sheet P is When the sheet P is conveyed to the curl correction device 7 in the state of warping upward (upper curl), the drive control unit 810 rotates the correction unit 70 by 180 degrees from the state of FIG. 12 in advance. The posture of the correction unit 70 at this time is defined as the second posture. In this case, the hard roller 702 contacts the first surface P (1) of the sheet P, and the elastic roller 701 contacts the second surface P (2) of the sheet P. The elastic roller 701 disposed above is compressed and deformed, and the nip portion N is curved along the peripheral surface of the hard roller 702, whereby the upper curl of the sheet P that has entered the nip portion N is suitably corrected. The Even in this case, the sheet P can be stably conveyed toward the inside of the correction unit 70, and the sheet P unloaded from the nip portion N can be stably conveyed to the horizontal conveyance path 50D. Become.

  Next, with reference to FIG. 15 and FIG. 16, the curl correction apparatus 9 which concerns on the 2nd Embodiment of this invention is demonstrated. FIG. 15 is a side view (A) and (B) showing the inside of the lower housing of the curl correcting device 9. FIG. 16 is a perspective view of the cam 92 and the movable rib 93. The curl correction device 9 is different from the curl correction device 7 according to the previous embodiment in that a movable rib 93 (rib member) is provided instead of the lower entry rib 731B. For this reason, below, it demonstrates centering around the characteristic of the movable rib 93, and abbreviate | omits description of another point. In the description of the curl correction device 9, a part of the configuration of the curl correction device 7 is used.

  Referring to FIG. 15, a plurality of movable ribs 93 are arranged in the sheet width direction, similarly to the lower entry rib 731 </ b> B of the previous embodiment. That is, the movable rib 93 is disposed so as to enter the inner side of the outer peripheral portion 70 </ b> A of the correction unit 70. Then, the first cutout portion 705A1 and the second cutout portion 705B1 formed in the correction unit 70 pass through positions where the movable ribs 93 face each other as the correction unit 70 rotates. In other words, as the correction unit 70 rotates, the movable rib 93 passes through the first notch 705A1 and the second notch 705B1 formed in the correction unit 70.

  In the present embodiment, the movable rib 93 can be moved in and out of the horizontal conveyance path 50D (sheet conveyance path). In the guide portion corresponding to the lower carry-in portion 731 in FIG. A plurality of openings 731Z are opened along the sheet width direction in the guide portion. The plurality of movable ribs 93 can be projected and retracted from the plurality of openings 731Z with respect to the horizontal conveyance path 50D.

  Referring to FIG. 16, each movable rib 93 includes a shaft portion 931 that extends in the sheet width direction, and a stretching portion 932 that can rotate around the shaft portion 931. And the front-end | tip part 93A of each movable rib 93 can be made to appear with respect to the horizontal conveyance path 50D via the opening part 731Z. In the present embodiment, the movable rib 93 is rotated around the shaft portion 931 by its own weight.

  The curl correction device 9 includes a rib drive motor 90 (drive means), a cam shaft 91 (shaft), and a cam 92 (cam member). The rib driving motor 90 generates a driving force that causes the movable rib 93 to move in and out of the horizontal conveyance path 50D. The rib drive motor 90 includes a third drive shaft 901. The third drive shaft 901 transmits the rotational drive force of the rib drive motor 90 to the clutch 902 described later. The camshaft 91 extends in the seat width direction (front-rear direction) and is rotatable. Specifically, the camshaft 91 is rotatably supported by a housing corresponding to the lower housing 73 of the curl correction device 7. A clutch 902 is disposed between the camshaft 91 and the third drive shaft 901. The clutch 902 has a function of transmitting the rotational driving force of the third driving shaft 901 to the camshaft 91 and cutting off the transmission of the rotational driving force.

  The cam 92 is fixed to the camshaft 91 so as to face the plurality of movable ribs 93, and comes into contact with the extending portions 932 of the plurality of movable ribs 93 from below. When the cam 92 is rotated around the camshaft 91 (arrow D161 in FIG. 16), the plurality of movable ribs 93 are moved up and down, and appear in and out of the horizontal conveyance path 50D (arrow D162 in FIG. 16). Referring to FIG. 16, cam 92 is arranged at a position different from large-diameter portion 92 </ b> A in the circumferential direction of camshaft 91 and large-diameter portion 92 </ b> A projecting radially from camshaft 91 with a first diameter. And a small-diameter portion 92B that protrudes in the radial direction from the camshaft 91 with a second diameter smaller than the first diameter. And as FIG. 15 shows, the some cam 92 arrange | positioned at the camshaft 91 is set so that arrangement | positioning of the large diameter part 92A and the small diameter part 92B in the circumferential direction may differ.

  When the rib drive motor 90 is rotationally controlled by a control unit (not shown) and the camshaft 91 is disposed at the position shown in FIG. 15A, the large-diameter portion of the cam 92 disposed at the center in the sheet width direction. 92A comes into contact with the movable rib 93, and the small diameter portion 92B of the cam 92 disposed at the end in the sheet width direction comes into contact with the movable rib 93. As a result, of the plurality of movable ribs 93, the amount of protrusion of the movable rib 93 arranged at the center in the sheet width direction with respect to the horizontal conveyance path 50D is the horizontal conveyance path of the movable rib 93 arranged at the end in the sheet width direction. It becomes larger than the protrusion amount for 50D. Therefore, even when the sheet P is conveyed to the curl correction device 9 with the central portion of the sheet P warped upward from both ends in the sheet width direction, the sheet P is stabilized at the nip portion N. Can be carried in.

  On the other hand, when the rib drive motor 90 is rotationally controlled by a control unit (not shown) and the camshaft 91 is disposed at the position shown in FIG. 15B, the small diameter of the cam 92 disposed at the center in the sheet width direction. The portion 92 </ b> B contacts the movable rib 93, and the large-diameter portion 92 </ b> A of the cam 92 disposed at the end in the sheet width direction contacts the movable rib 93. As a result, of the plurality of movable ribs 93, the amount of protrusion of the movable rib 93 arranged at the center in the sheet width direction with respect to the horizontal conveyance path 50D is the horizontal conveyance path of the movable rib 93 arranged at the end in the sheet width direction. It becomes smaller than the protrusion amount for 50D. Therefore, even when the sheet P is conveyed to the curl correction device 9 with both end portions of the sheet P warped upward from the central portion in the sheet width direction, the sheet P is stabilized at the nip portion N. Can be carried in.

  According to the above embodiment, the curl of the sheet P is corrected at the nip portion N formed between the elastic roller 701 and the hard roller 702 in the correction unit 70 as the curl correction portion. The lower carry-in unit 731 and the upper carry-in unit 741 are arranged on the upstream side of the correction unit 70 in the sheet conveyance direction, and guide the sheet P toward the correction unit 70. The upper carry-out unit 743 is disposed on the downstream side of the correction unit 70 in the sheet conveyance direction, and guides the sheet P carried out from the correction unit 70. The lower entry rib 731B, the upper entry rib 741B, and the upper carry-out rib 743A (rib member) enter the inside of the correction unit 70 from the outer peripheral part 70A of the correction unit 70 so as to enter the correction unit 70 along the sheet conveyance direction. The upper carry-in part 741 and the upper carry-out part 743 project. Further, the first cutout portion 705A1 and the second cutout portion 705B1 (cutout portion) are formed by partially cutting the outer peripheral portion 70A of the correction unit 70 so as to face the rib member. The rib member passes through the notch as the correction unit 70 rotates. For this reason, the sheet P is stably conveyed between the lower carry-in part 731, the upper carry-in part 741, the upper carry-out part 743 and the correction unit 70 including the curl correction part. Further, the sheet P is prevented from being conveyed along the outer peripheral portion 70 </ b> A of the correction unit 70.

  Further, according to the above embodiment, the first notch 705A1 and the second notch 705B1 are formed in the eleventh guide 705A and the twelfth guide 705B, so that the lower carry-in part 731 and the upper carry-in part 741 The sheet P is stably delivered between the eleventh guide 705A and the twelfth guide 705B of the correction unit 70.

  Further, according to the first embodiment, the sheet P is stably conveyed by the plurality of lower entry ribs 731B, upper entry ribs 741B, and upper carry-out ribs 743A arranged along the sheet width direction.

  Further, according to the second embodiment described above, the plurality of movable ribs 93 can be moved in and out of the horizontal conveyance path 50D. For this reason, the movable rib 93 protrudes with respect to the horizontal conveyance path 50D, whereby the sheet is conveyed stably. Further, when the sheet P that is easily damaged is conveyed, the movable rib 93 can be immersed from the horizontal conveyance path 50D. Further, the plurality of movable ribs 93 can be caused to appear and disappear in the horizontal conveyance path 50D via the plurality of openings 731Z.

  Further, according to the second embodiment, in one aspect, the protrusion amount of the movable rib 93 disposed at the center portion in the sheet width direction among the plurality of movable ribs 93 with respect to the horizontal conveyance path 50D is the sheet width. The amount of protrusion of the movable rib 93 arranged at the end in the direction with respect to the horizontal conveyance path 50D is set larger. For this reason, even when the central portion of the sheet in the sheet width direction is warped with respect to the end portion, the sheet can be stably conveyed between the lower carry-in portion 731 and the correction unit 70.

  Further, according to the second embodiment, in another aspect, the amount of protrusion of the movable rib 93 arranged at the center in the sheet width direction among the plurality of movable ribs 93 with respect to the horizontal conveyance path 50D is the sheet width. It is set smaller than the protruding amount of the movable rib 93 arranged at the end in the direction with respect to the horizontal conveyance path 50D. For this reason, even when the end portion of the sheet in the sheet width direction is warped with respect to the center portion, the sheet can be stably conveyed between the lower carry-in portion 731 and the correction unit 70.

  Moreover, according to said 2nd Embodiment, the some movable rib 93 can be made to appear in the horizontal conveyance path 50D with rotation around the cam shaft 91 of the cam 92. As shown in FIG. In particular, the plurality of movable ribs 93 are rotated around the shaft portion 931 by their own weight. The cam 92 pushes up the movable rib 93 from below, so that the movable rib 93 appears and disappears in the horizontal conveyance path 50D.

  Further, according to the above-described embodiment, the lower entry rib 731B, the upper entry rib 741B, the upper carry-out rib 743A, and the movable rib 93 pass through both end edges in the sheet width direction of the sheet P conveyed on the horizontal conveyance path 50D. It is arranged at a position different from the position. For this reason, it is suppressed that the said rib member contacts the both ends edge of the sheet | seat P, and it is prevented that conveyance of the sheet | seat P is prevented.

  Further, according to the above-described embodiment, even when the sheet P subjected to the fixing process is curled, the curl of the sheet P is preferably corrected by the curl correction devices 7 and 9. Further, the curl correction devices 7 and 9 can be arranged using the transport unit 55. Further, before the sheet P reaches the post-processing apparatus, the curl of the sheet P is stably corrected.

  As described above, the curl correction apparatuses 7 and 9 and the image forming apparatus 1 including the curl correction apparatuses according to the embodiment of the present invention have been described. However, the present invention is not limited to this, and for example, the following modified embodiment is provided. Can be adopted.

  (1) In the first embodiment, the lower entry rib 731B, the upper entry rib 741B, and the upper carry-out rib 743A are described as the rib members. However, the present invention is limited to this. is not. Any one or two of the above may be arranged, and a rib member protruding toward the outer peripheral portion 70A of the correction unit 70 may be arranged in the lower carry-out portion 733 as well as the above rib member. .

  (2) Although the above embodiment has been described using the curl amount detection sensor 77 which is a distance measuring sensor as the sensor for detecting the characteristic value according to the curl amount of the sheet P, the present invention is limited to this. It is not a thing. As the characteristic value corresponding to the curl amount, other sensors or the like may be used. For example, a mode in which a light reflection type sensor is used and the curl amount of the sheet P is detected from the reflection angle of the light irradiated toward the leading end of the sheet P may be used.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 32 Image forming part 35 Secondary transfer roller (transfer means)
50D horizontal conveyance path (sheet conveyance path)
50R Conveying roller pair (discharge section)
55 Transport unit (relay transport unit)
55R downstream roller pair 55R1 first downstream roller 55R2 second downstream roller 60 fixing unit 7 curl correction device 70 correction unit (support unit)
700 Unit shaft (third rotation shaft)
701 Elastic roller (first roller)
701A Elastic roller shaft (first rotating shaft)
702 Hard roller (second roller)
702A Hard roller shaft (second rotation shaft)
703 Rear flange portion 703A First rear flange 703B Second rear flange 703G Outer peripheral gear portion 704 Front flange portion 704A First front flange 704B Second front flange 705 First guide portion 705A Eleventh guide (guide plate)
705A1 First notch (notch)
705B 12th guide (guide plate)
705B1 Second notch (notch)
706 2nd guide part 706A 21st guide 706B 22nd guide 707 Input gear 708 Relay gear 708A 1st relay gear part 708B 2nd relay gear part 709 Transmission gear 709A Transmission gear shaft 70A Outer peripheral part 71 1st frame 711 Rotary shaft 712 Rotary Gear 712A First gear portion 712B Second gear portion 72 Second frame 721 Rotary motor 721A First drive shaft 722 Drive motor 722A Second drive shaft 73 Lower housing 731 Lower carry-in portion (guide portion)
731A Lower carry-in rib 731B Lower entry rib (rib member)
731Z Opening 732 Lower support portion 733 Lower carry-out portion 74 Upper housing 741 Upper carry-in portion (guide portion)
741A Upper carry-in rib 741B Upper entry rib (rib member)
742 Upper support part 743 Upper carry-out part (guide part)
743A Upper carry-out rib (rib member)
75 swing piece 751 fulcrum part 752 detection piece 76 detection sensor 761 light emission part 762 light reception part 77 curl amount detection sensor 810 drive control part 820 count part 830 storage part 90 rib drive motor (drive means)
901 Third drive shaft 902 Clutch 91 Cam shaft (shaft)
92 Cam (Cam member)
92A Large diameter part 92B Small diameter part 93 Movable rib (rib member)
931 Shaft 932 Stretched portion 93A Tip

Claims (12)

A first roller provided with a first rotation shaft, rotated about the first rotation shaft, and elastically deformable;
A second rotation axis parallel to the first rotation axis; rotated around the second rotation axis; elastically deforms the first roller by being pressed by the first roller; A second roller forming a nip portion curved between,
A sheet conveyance path in which a sheet is conveyed in a predetermined sheet conveyance direction while passing through the nip portion;
A third rotating shaft that rotatably supports the first and second rollers by pivotally supporting the first and second rotating shafts, and is arranged in parallel with the first rotating shaft; A support unit supported on the apparatus main body so as to be rotatable about the third rotation axis,
A guide portion that is arranged on the upstream side or the downstream side in the sheet conveying direction of the support unit, guides the sheet toward the support unit, or guides the sheet carried out of the support unit;
A rib member that projects from the guide portion along the sheet conveying direction so as to enter the inside of the support unit from the outer peripheral portion of the support unit, and guides the sheet;
The outer peripheral portion of the support unit is partially cut away to face the rib member, and the notch portion through which the rib member passes with the rotation of the support unit;
A curl straightening device comprising: The support unit includes a pair of guide plates extending from the outer peripheral portion toward the nip portion so as to sandwich the sheet conveyance path and guiding the sheet,
The curl correction apparatus according to claim 1, wherein the notch is formed in the guide plate.   The curl correction apparatus according to claim 1, wherein a plurality of the rib members and the notch portions are arranged along a sheet width direction intersecting with the sheet conveyance direction.   The curl correction apparatus according to claim 3, wherein the plurality of rib members can be moved in and out of the sheet conveyance path. A plurality of openings that are opened along the sheet width direction in the guide portion;
The curl correction apparatus according to claim 4, wherein each of the plurality of rib members can be projected and retracted from the plurality of openings with respect to the sheet conveyance path.   Of the plurality of rib members, the protruding amount of the rib member arranged at the center portion in the sheet width direction with respect to the sheet conveyance path is the sheet conveyance path of the rib member arranged at the end portion in the sheet width direction. The curl correction device according to claim 4 or 5, wherein the amount of protrusion is larger than a protruding amount with respect to.   Of the plurality of rib members, the protruding amount of the rib member arranged at the center portion in the sheet width direction with respect to the sheet conveyance path is the sheet conveyance path of the rib member arranged at the end portion in the sheet width direction. The curl correction apparatus according to claim 4, wherein the curl correction apparatus is smaller than a protruding amount with respect to. The plurality of rib members comprising: a shaft portion that extends in the sheet width direction; and a stretching portion that is rotatable about the shaft portion and that can extend and retract with respect to the sheet conveyance path;
A shaft extending in the sheet width direction and rotatable,
A plurality of cam members fixed to the shaft facing the plurality of rib members and abutting against the extending portions of the plurality of rib members;
Drive means for rotationally driving the shaft,
The rotation of the cam member around the shaft causes the plurality of rib members to rotate around the shaft portion and to protrude and retract with respect to the sheet conveyance path. Curling straightener.   The said rib member is arrange | positioned in the said sheet conveyance path in the position different from the position where the both ends edge of the sheet width direction of the said sheet conveyed in the said sheet conveyance path passes. The curl correction apparatus as described. A curl correction device according to any one of claims 1 to 9,
An image forming apparatus, comprising: an image forming unit disposed in the sheet conveyance path and forming an image on the sheet. The image forming unit includes a transfer unit that transfers a toner image to a sheet, and a fixing unit that performs a fixing process on the sheet of the toner image.
The image forming apparatus according to claim 10, wherein the curl correcting device is disposed downstream of the fixing unit in the sheet conveying direction. A paper discharge unit that discharges the sheet subjected to the fixing process by the fixing unit;
A post-processing device that is disposed at a predetermined interval from the paper discharge unit and performs a predetermined post-processing on the sheet;
A relay conveyance unit that conveys the sheet from the paper discharge unit to the post-processing device,
The image forming apparatus according to claim 11, wherein the curl correction apparatus is disposed in the relay conveyance unit.

Images