Patent Publication Number: US-9403381-B2

Title: Curl eliminating device for recording medium and image forming apparatus including the same

Description:
INCORPORATION BY REFERENCE 
     This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2014-166719 filed Aug. 19, 2014, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure relates to a curl eliminating device for eliminating a curl of a recording medium such as a paper sheet and to an image forming apparatus including the curl eliminating device. 
     Conventionally, in an electrophotographic type or an inkjet recording type image forming apparatus such as a copier or a printer, a double-sided printing method is widely used, in which the paper sheet after forming an image on one side of the paper sheet is not discharged but is conveyed again to an image forming unit so that an image is formed on the other side too. The double-sided printing type image forming apparatus is equipped with a double-sided circulation transport path for reversing the paper sheet after an image is formed on one side thereof, so as to reconvey the reversed paper sheet to the image forming unit. 
     As to the image forming apparatus of the double-sided printing type described above, it is common to switch back the paper sheet in the double-sided circulation transport path, to stop the paper sheet temporarily on a reverse tray, and then to reconvey the paper sheet from the rear end so that the front and back sides of the paper sheet are reversed. For this reason, when the paper sheet passes through the double-sided circulation transport path having a U-shaped curve, a curl (curling) may occur to the paper sheet. Main causes of the curl include contraction of a resin component in toner due to thermal fixing in an electrophotographic image forming apparatus, swelling of the paper sheet due to impregnation of ink in an inkjet image forming apparatus, and a moisture control function of the paper sheet depending on temperature and humidity conditions. 
     For instance, when continuously printing on both sides of the paper sheets, in order to improve print efficiency, during printing on a second side, the next paper sheet having the first side printed is set on standby in the double-sided circulation transport path. In this case, curl may occur to the paper sheet stopped at a bent part of the double-sided circulation transport path. In particular, as need for bookbinding by on-demand printing has been increased, frequency of using thick paper sheets having basis weight of 300 g/m 2  as cover papers of booklets has been increased. Such thick paper sheets tend to occur curls, which is hardly straightened. 
     Accordingly, there are proposed various curl eliminating devices for eliminating curl of a paper sheet. For instance, there is known a curl correction device for correcting curl of a paper sheet by making the paper sheet pass through a nip portion between a pressure roller and a belt. It is also known to adjust pressing amount of the pressure roller to the belt by using a cam. 
     In addition, there is known a curl eliminating device in which first and third rollers as compressive soft rollers are pressed to contact with both sides of a second roller as a non-compressive hard roller, and a nip portion for the sheet to pass through is determined in accordance with direction of the curl of the sheet. 
     Further, there is known a decurl device including a decurl part capable of moving in the direction perpendicular to the conveying direction of continuous paper, in which the decurl part is moved opposite to the curl direction of the continuous paper so that a curled part is straightened by a decurl bar for removing the curl. 
     SUMMARY 
     A curl eliminating device according to one aspect of the present disclosure includes a decurl roller pair, a cleaning member, and a pressure contact mechanism. The decurl roller pair includes a first roller contacting with a non-image formed side of a recording medium and a second roller configured to be pressed to contact with an outer circumference surface of the first roller and configured to contact with an image formed side of the recording medium, so as to correct a curl of the recording medium. The first roller is an elastic roller including an elastic layer formed on the outer circumference surface, and the second roller is a roller having a diameter smaller than that of the first roller and hardness higher than that of the first roller. The cleaning member cleans the second roller. The pressure contact mechanism presses the cleaning member to contact with an outer circumference surface of the second roller from the side opposite to the first roller. 
     Further features and advantages of the present disclosure will become apparent from the description of embodiments given below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an internal structure of an inkjet type multifunction peripheral as an example of an image forming apparatus equipped with a curl eliminating device of the present disclosure. 
         FIG. 2  is a diagram showing the curl eliminating device according to a first embodiment of the present disclosure. 
         FIG. 3  is a cross-sectional view of a decurl roller pair and a cleaning roller taken along the axial direction thereof, which constitute the curl eliminating device of the first embodiment. 
         FIG. 4  is a diagram showing of an eccentric cam used for a pressure adjustment mechanism of the curl eliminating device. 
         FIG. 5  is a diagram of the curl eliminating device viewed from diagonally above on an upstream side in a conveying direction according to a second embodiment of the present disclosure. 
         FIG. 6  is a diagram of the curl eliminating device viewed from above according to the second embodiment. 
         FIG. 7  is a cross-sectional view of the curl eliminating device taken along a plane perpendicular to the axial direction according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Now, embodiments of the present disclosure are described with reference to the drawings.  FIG. 1  is a side cross-sectional view indicating an internal structure of an inkjet type multifunction peripheral  100  equipped with a curl eliminating device  25  of the present disclosure. 
     As shown in  FIG. 1 , the multifunction peripheral  100  includes sheet feed cassettes  2   a  to  2   c  as paper sheet storing units disposed in a lower part inside a multifunction peripheral main body  1 . Inside the sheet feed cassettes  2   a  to  2   c , there are stacked and stored paper sheets P as cut paper sheets before printing as an example of recording medium. A sheet feeding device including a pickup roller  3  and a sheet feed roller pair  4  is disposed on the downstream side in the paper sheet conveying direction of each of the sheet feed cassettes  2   a  to  2   c , for example on the upper left side of the sheet feed cassette  2   a  in  FIG. 1 . This sheet feeding device separates the paper sheets P one by one and sends out the paper sheet P toward the upper left of the sheet feed cassettes  2   a  to  2   c  in  FIG. 1 . The sheet feed cassettes  2   a  to  2   c  can be drawn out horizontally from the front side of the multifunction peripheral main body  1  so as to supply the paper sheets P. 
     A manual sheet supply tray  2   d  is disposed on the outer right side of the multifunction peripheral main body  1 . Paper sheets P′ of a size different from that of the paper sheets P in the sheet feed cassettes  2   a  to  2   c , or paper sheets P′ such as envelops that are difficult to pass through a bent conveying path, or paper sheets P′ to be set manually one by one, or the like are set on the manual sheet supply tray  2   d . A sheet feeding device including a pickup roller  3  and a sheet feed roller pair  4  is disposed on the downstream side in the paper sheet conveying direction of the manual sheet supply tray  2   d , namely on the left side of the manual sheet supply tray  2   d  in  FIG. 1 . This sheet feeding device separates the paper sheets P′ on the manual sheet supply tray  2   d  one by one and sends out the paper sheet P′ toward the left in  FIG. 1 . 
     In addition, a first paper sheet transport path  4   a  is disposed inside the multifunction peripheral  100 . The paper sheet P sent out from one of the sheet feed cassettes  2   a  to  2   c  is conveyed in the first paper sheet transport path  4   a  upward vertically along the left side surface of the multifunction peripheral main body  1 . On the other hand, the paper sheet P′ sent out from the manual sheet supply tray  2   d  is conveyed in the first paper sheet transport path  4   a  in a substantially horizontal left direction, and then is conveyed upward vertically along the left side surface of the multifunction peripheral main body  1 . 
     A registration roller pair  13  is disposed at a downstream end of the first paper sheet transport path  4   a  in the paper sheet conveying direction. Further, a first belt conveying unit  5  and a printing unit  9  are disposed near the downstream side of the registration roller pair  13 . The paper sheet P sent from one of the sheet feed cassettes  2   a  to  2   c  (or the paper sheet P′ sent from the manual sheet supply tray  2   d ) passes in the first paper sheet transport path  4   a  and reaches the registration roller pair  13 . The registration roller pair  13  corrects skew of the paper sheet P or P′ and sends out the paper sheet P or P′ to the first belt conveying unit  5  in synchronization with timing of ink discharge operation performed by the printing unit  9 . Note that conveying roller pairs  14   a  for conveying the paper sheet P or P′ are disposed at appropriate positions in the first paper sheet transport path  4   a.    
     The first belt conveying unit  5  includes an endless first conveying belt  8  wound around a plurality of rollers including a drive roller. The first conveying belt  8  is driven by the drive roller to turn in a clockwise direction in  FIG. 1 . Inside the first conveying belt  8 , at a position corresponding to the backside of the conveying surface (upper surface) of the first conveying belt  8 , there is disposed a paper sheet suction unit (not shown). The paper sheet suction unit has many holes for sucking air on the upper surface and includes a fan inside, so as to suck air downward from the upper surface. In addition, the first conveying belt  8  also has many air holes (not shown) for sucking air. With the structure described above, the first belt conveying unit  5  sucks and holds the paper sheet P or P′ on the conveying surface of the first conveying belt  8  so as to convey the paper sheet P or P′. 
     The paper sheet P sent by the registration roller pair  13  is sucked and held on the conveying surface (upper surface in  FIG. 1 ) of the first conveying belt  8  and is conveyed from left to right in  FIG. 1 . The first belt conveying unit  5  can move in the up and down direction in the multifunction peripheral main body  1 . 
     The printing unit  9  includes line heads for printing an image on the paper sheet P sucked and held on the conveying surface of the first conveying belt  8  so as to be conveyed. In accordance with image data received from an external computer or the like, each of the line heads sequentially discharges corresponding ink toward the paper sheet P or P′ sucked by the first conveying belt  8 , and hence a full color image is printed on the paper sheet P or P′ as an overlaid image of yellow, magenta, cyan, and black inks. 
     A second belt conveying unit  12  is disposed on the downstream side (right side in  FIG. 1 ) of the first belt conveying unit  5  in the paper sheet conveying direction. The paper sheet P or P′ on which an ink image is printed by the printing unit  9  is sent to the second belt conveying unit  12 , and the ink on the surface of the paper sheet P or P′ is dried while the paper sheet P or P′ passes through the second belt conveying unit  12 . 
     The second belt conveying unit  12  includes an endless second conveying belt  40  wound around a plurality of rollers including a drive roller. The second conveying belt  40  is driven by the drive roller to turn in the clockwise direction in  FIG. 1 . The paper sheet P or P′ is sucked and held on the conveying surface (upper surface) of the second conveying belt  40  by the same mechanism as the first conveying belt  8 . After the printing unit  9  prints an image on the paper sheet P, the paper sheet P is conveyed by the first belt conveying unit  5  to the right direction and received by the second conveying belt  40 , and then is conveyed to a diagonally upper right direction in  FIG. 1 . 
     A decurl part  15  is disposed on the downstream side of the second belt conveying unit  12  in the paper sheet conveying direction near the right side surface of the multifunction peripheral main body  1 . The decurl part  15  includes a particle roller  15   a  that has an outer circumference surface on which many particles are attached and contacts with a printed surface of the paper sheet P or P′, and an endless belt  15   b  that is stretched around two support rollers and has a surface coated with Teflon (trademark). When the endless belt  15   b  is driven to turn by the common drive source shared by the second belt conveying unit  12 , the particle roller  15   a  pressed to contact with the endless belt  15   b  rotates following the endless belt  15   b . The paper sheet P or P′ after the ink is dried by the second belt conveying unit  12  is sent to the decurl part  15  in which curl (curling) is corrected. 
     A second paper sheet transport path  4   b  is disposed on the downstream side (upper side in  FIG. 1 ) of the decurl part  15  in the paper sheet conveying direction. When double-sided printing is not performed, the paper sheet P or P′ after passing through the decurl part  15  is discharged from the second paper sheet transport path  4   b  via a discharge roller pair  16   a  onto a paper sheet discharge tray  17  disposed on the upper left of the multifunction peripheral  100 , or is conveyed from the second paper sheet transport path  4   b  via a discharge roller pair  16   b  into a paper sheet post processing device (not shown) connected to the left outside surface of the multifunction peripheral  100 . 
     In addition, a maintenance unit  19  is disposed below the second belt conveying unit  12 . When performing purge action to discharge ink in the nozzles having high viscosity from the ink discharge nozzles, the first belt conveying unit  5  is moved downward, and then the maintenance unit  19  is moved to between the printing unit  9  and the first belt conveying unit  5 . The maintenance unit  19  after moving to below the printing unit  9  wipes off the ink discharged from the ink discharge nozzles of the print head and collects the wiped-off ink. 
     An image reader unit  21  is disposed in the uppermost part in the multifunction peripheral main body  1 . The image reader unit  21  includes a scanning optical system including a scanner lamp for illuminating a document in copy operation and a mirror for changing an optical path of reflection light from the document, a condenser lens for condensing the reflection light from the document so as to form an image, and a CCD sensor for converting the formed image light into an electric signal, and the like (all of which are not shown). The image reader unit  21  reads the document image so as to convert it into image data. A document feeder device  23  for automatically feeding document sheets to the image reader unit  21  is disposed on the upper surface of the multifunction peripheral main body  1 . 
     A double-sided circulation transport path  18  for performing double-sided printing on the paper sheet P or P′ is disposed above the printing unit  9  in the upper part of the multifunction peripheral main body  1 . When performing the double-sided printing, after printing on a first side of the paper sheet P is finished, the paper sheet P passes through the second belt conveying unit  12  and the decurl part  15 , and then passes in the second paper sheet transport path  4   b  so as to be sent to the double-sided circulation transport path  18 . After the paper sheet P or P′ is sent to the double-sided circulation transport path  18 , the conveying direction of the paper sheet P or P′ is switched in a reverse tray  20  for printing on a second side so that the paper sheet P or P′ passes above the printing unit  9  and is sent to the left side. Then, the paper sheet P or P′ is sent via the first paper sheet transport path  4   a  and the registration roller pair  13  to the first belt conveying unit  5  again in the state where the second side faces upward. Further, similarly to the first paper sheet transport path  4   a , there are disposed conveying roller pairs  14   b  and  14   c  for conveying the paper sheet P or P′ at appropriate positions in the second paper sheet transport path  4   b  and the double-sided circulation transport path  18 . The conveying roller pair  14   c  disposed in the double-sided circulation transport path  18  is driven to rotate by a first motor  30 . As the first motor  30 , a stepping motor is used, which facilitates adjustment of the rotation speed of the conveying roller pair  14   c.    
     In addition, the double-sided circulation transport path  18  can also have a function of making the next paper sheet P or P′ wait on standby when continuously printing on both sides of the paper sheet P or P′. By making the paper sheet P or P′ wait on standby in the double-sided circulation transport path  18  and controlling the rotation drive of the first motor  30 , the paper sheet P or P′ is accelerated, decelerated, or stopped, so that an interval between paper sheets when performing the double-sided printing can be decreased. Thus, image forming efficiency can be improved. 
     Because the printed side (printed surface) of the paper sheet P or P′ is swelled with the ink after printing on one side thereof by the printing unit  9 , the paper sheet P or P′ is curled with convex side of the printed side. In particular, when using water based ink having small permeability in the paper sheet P or P′, the ink is apt to stay on the printed side so that occurrence of curl becomes outstanding. When the curled paper sheet P or P′ is conveyed via the reverse tray  20  and the registration roller pair  13  to the printing unit  9  again, the paper sheet P or P′ may be insufficiently sucked and held by the first belt conveying unit  5 , or the distance to the print head of the printing unit  9  may vary so that poor quality of printing may occur. 
     Accordingly, there is disposed the curl eliminating device  25  in the double-sided circulation transport path  18  so as to correct the curl of the paper sheet P or P′. The curl eliminating device  25  is disposed near the upstream side of the reverse tray  20  in the paper sheet conveying direction so as to avoid a stop position of the paper sheet P or P′ when continuously printing on both sides of the paper sheet P or P′. 
     Further, in the multifunction peripheral  100 , there is disposed a control unit (CPU)  50  for controlling operations of the rollers, the printing unit  9 , the first belt conveying unit  5 , the second belt conveying unit  12 , the maintenance unit  19 , and the like described above. 
       FIG. 2  is a diagram showing a structure of the curl eliminating device  25  according to a first embodiment of the present disclosure, and  FIG. 3  is a cross-sectional view of a decurl roller pair  32  and a cleaning roller  39  as a cleaning member of the curl eliminating device  25  taken along the axial direction thereof. The decurl roller pair  32  includes a first roller  33  having an elastic layer and a second roller  35  (not shown in  FIG. 2 ) having higher hardness than that of the first roller  33 . 
     In order to enhance a curl correction effect by the decurl roller pair  32 , it is necessary that the diameter of the second roller  35  as a hard roller is as small as possible (e.g., 8 mm or smaller). A metal roller having a diameter of 7 mm, for example, is used as the second roller  35 . On the other hand, as the first roller  33 , an elastic roller is used, for example, which includes an elastic layer made of foamed silicone rubber formed on the outer circumference surface of a rotation shaft  33   a  and has a diameter of 24.2 mm. 
     A rotation shaft  35   a  of the second roller  35  is supported by frames  40   a  and  40   b  in the front and rear direction of the multifunction peripheral  100  via bearings in a rotatable manner. In addition, the rotation shaft  33   a  of the first roller  33  is supported by the frames  40   a  and  40   b  via bearings in a rotatable manner and is supported in a slidable manner along slots  40   aa  and  40   ba  formed in the frames  40   a  and  40   b . The first roller  33  and the second roller  35  are pressed to contact with each other at a predetermined pressure by a pressure adjustment mechanism  37  as described later. 
     The cleaning roller  39  is pressed to contact with the second roller  35  contacting with the printed surface of the paper sheet, from the side opposite to the nip portion with the first roller  33 . The cleaning roller  39  is a felt roller including felt (nonwoven fabric) wound around an outer circumference surface of a roller body or an elastic roller having a surface made of a porous elastic material. The cleaning roller  39  rotates following the second roller  35  so as to wipe off ink attached to the second roller  35 . A rotation shaft  39   a  of the cleaning roller  39  is supported by the frames  40   a  and  40   b  via bearing in a rotatable manner and is supported in a slidable manner along the slots  40   aa  and  40   ba  formed in the frames  40   a  and  40   b.    
     In addition, a compression springs  47  (pressure contact mechanism) for pressing bearing portions  39   b  provided to both end portions of the rotation shaft  39   a  in a downward direction (toward the second roller  35 ). The cleaning roller  39  is pressed by the compression springs  47  to contact with the second roller  35  at a predetermined pressure. As a drive source for driving the second roller  35  of the decurl roller pair  32  to rotate, a second motor  31  (see  FIG. 1 ) is used, which is different from the first motor  30  as a drive source of the conveying roller pair  14   c . As the second motor  31 , a DC brushless motor is used, which is suitable for use at a high rotational frequency and a high torque. 
     The second motor  31  for driving the decurl roller pair  32  also drives a discharging unit  27  including the discharge roller pair  16   b . In other words, the single second motor  31  works as both the drive sources for the decurl roller pair  32  and the discharging unit  27 . In this way, it is not necessary to dispose a dedicated motor for driving the discharging unit  27  so that the number of motors and a space for disposing the motors can be reduced. Thus, it is possible to contribute to downsizing and cost reduction of the multifunction peripheral  100 . 
     Further, a drive force is input from the second motor  31  to a drive input gear  48  fixed to an end of the rotation shaft  35   a  of the second roller  35 . In this way, the second roller  35  rotates, and the first roller  33  and the cleaning roller  39  rotate following the second roller  35 . The decurl roller pair  32  is disposed to cover a substantially entire region in the paper sheet width direction (perpendicular to the paper plane of  FIGS. 2 and 3 ). When the paper sheet P or P′ passes through the nip portion of the decurl roller pair  32 , curl (curing) of the paper sheet is corrected. In addition, a jamming disposal handle  49  is disposed on the other end (opposite to the drive input gear  48 ) of the rotation shaft  35   a  of the second roller  35 . When jamming of the paper sheet P or P′ occurs on the decurl roller pair  32 , the second roller  35  is manually rotated by grasping the jamming disposal handle  49  so as to deal with the jamming. 
     The pressure adjustment mechanism  37  includes eccentric cams  43  fixed to both ends of a cam shaft  41  and a pressure adjustment motor  45  for rotating the cam shaft  41 .  FIG. 4  is a diagram showing the eccentric cam  43  that is used for the pressure adjustment mechanism  37  of the curl eliminating device  25 . The eccentric cam  43  has a D-shaped shaft hole  43   a  in which the cam shaft  41  is inserted and fixed and an outer circumference surface  43   b  having a varying distance from the center of the shaft hole  43   a . The outer circumference surface  43   b  of the eccentric cam  43  contacts with the bearing portion of the rotation shaft  33   a  of the first roller  33 . When the eccentric cams  43  are rotated by the pressure adjustment motor  45 , a position of the rotation shaft  33   a  of the first roller  33  with respect to the rotation shaft  35   a  of the second roller  35  (an intershaft distance) is adjusted. 
     A contact pressure between the first roller  33  and the second roller  35  necessary for correcting curl is different depending on a thickness of the paper sheet. Accordingly, it is preferred that the control unit  50  (see  FIG. 1 ) sets the contact pressure between the first roller  33  and the second roller  35  to an appropriate value on the basis of thickness information of the paper sheet input from a host device such as a personal computer or from an operation panel (not shown). Specifically, the control unit  50  transmits a control signal based on the thickness information of the paper sheet to the pressure adjustment motor  45 . The control unit  50  controls the eccentric cams  43  to rotate by a predetermined amount for adjusting the intershaft distance between the rotation shaft  33   a  and the rotation shaft  35   a , so that the contact pressure between the first roller  33  and the second roller  35  becomes a set value corresponding to the thickness of the paper sheet P or P′. 
     As described above, it is necessary to use a hard roller having a small diameter as the second roller  35  constituting the decurl roller pair  32 . For this reason, the second roller  35  may be warped by a strong press contact force acting between the first roller  33  and the second roller  35 . When a warp occurs to the second roller  35 , the decurl roller pair  32  becomes misaligned, and hence a wrinkle occurs on the paper sheet P or P′ passing through the nip portion of the decurl roller pair  32 , or a curl correction amount in the axial direction by the decurl roller pair  32  becomes uneven. As a result, image quality may be deteriorated. 
     Accordingly, in this embodiment, the cleaning roller  39  for cleaning the second roller  35  is disposed on the side opposite to the first roller  33  with respect to the second roller  35 . With this structure, opposed portions on the outer circumference surface of the second roller  35  are sandwiched between the first roller  33  and the cleaning roller  39 . As a result, the press contact force acting from the first roller  33  to the second roller  35  by the pressure adjustment mechanism  37  and the press contact force acting from the cleaning roller  39  to the second roller  35  by the compression spring  47  are canceled by each other, so that the warp of the second roller  35  can be suppressed. 
     Accordingly, ink attached to the outer circumference surface of the second roller  35  is removed by the cleaning roller  39  so that dirt (offset) on the image surface is suppressed, and occurrence of wrinkle on the paper sheet P or P′, or the unevenness of the curl correction amount due to the warp of the second roller  35  can be also suppressed. 
       FIG. 5  is a diagram of the curl eliminating device  25  according to a second embodiment of the present disclosure viewed from diagonally above the conveying direction upstream side,  FIG. 6  is a diagram of the curl eliminating device  25  of the second embodiment viewed from above, and  FIG. 7  is a cross-sectional view of the curl eliminating device  25  of the second embodiment taken along a plane perpendicular to the axial direction (taken along the line AA′ in  FIG. 6 ). In this embodiment, as the cleaning member for cleaning the second roller  35 , a web device  60  including a fiber web  51 , a sending-out roller  52 , a pressure roller  53 , and a winding roller  55  is provided instead of the cleaning roller  39 . The pressure adjustment mechanism  37  including the eccentric cams  43  fixed to both ends of the cam shaft  41  and the pressure adjustment motor  45  (see  FIG. 3 ) for driving the cam shaft  41  to rotate is the same as in the first embodiment. 
     The fiber web  51  is wound around the sending-out roller  52  like a roll, and the fiber web  51  sent out from the sending-out roller  52  is pressed by the pressure roller  53  to contact with the second roller  35 , and then is wound around the winding roller  55 . The pressure roller  53  is a metal roller having a high stiffness and a diameter of 10 mm or larger. The compression springs  47  (pressure contact mechanism) for pressing a bearing portion  53   a  in a downward direction (toward the second roller  35 ) is disposed on each end portion of the rotation shaft of the pressure roller  53 . The pressure roller  53  is pressed by the compression springs  47  to contact with the second roller  35  at a predetermined press contact force. 
     A drive input gear  57  is attached to the rotation shaft of the winding roller  55 . When a rotation drive force is transmitted to the drive input gear  57  from a drive source (not shown), the sending-out roller  52  and the winding roller  55  rotate at a line speed of approximately 1% of that of the second roller  35 . In addition, the pressure roller  53  rotates following the fiber web  51  that is moved by the rotations of the sending-out roller  52  and the winding roller  55 . 
     In this way, the fiber web  51  rubs the outer circumference surface of the second roller  35  so as to remove the ink attached to the outer circumference surface of the second roller  35 . In addition, when the fiber web  51  is gradually sent out from the sending-out roller  52 , a new part to which no ink is attached contacts with the second roller  35 , while the part to which ink is attached is wound around the winding roller  55 . Accordingly, there is no possibility that ink attached to the fiber web  51  is transferred to the second roller  35 . 
     Further, in this embodiment, the pressure roller  53  for pressing the fiber web  51  to the second roller  35  is disposed on the side opposite to the first roller  33  with respect to the second roller  35 . 
     With this structure, opposed portions on the outer circumference surface of the second roller  35  are sandwiched between the first roller  33  and the pressure roller  53 . As a result, the press contact force acting from the first roller  33  to the second roller  35  by the pressure adjustment mechanism  37  and the press contact force acting from the pressure roller  53  to the second roller  35  by the compression springs  47  are canceled by each other, so that the warp of the second roller  35  can be suppressed similarly to the first embodiment. 
     Accordingly, ink attached to the outer circumference surface of the second roller  35  is removed by the fiber web  51  so that dirt (offset) on the image surface is suppressed, and occurrence of wrinkle on the paper sheet P or P′, or unevenness of the curl correction amount due to a warp of the second roller  35  can be also suppressed. 
     Other than that, the present disclosure is not limited to the embodiments described above and can be variously modified within the scope of the spirit of the present disclosure. For instance, the second motor  31  as a drive source for the discharging unit  27  also works as a drive source for the decurl roller pair  32  in the embodiments described above, but it is possible to configure that the second motor  31  is a dedicated drive source for the decurl roller pair  32 . 
     In addition, the inkjet printing type multifunction peripheral  100  equipped with the curl eliminating device  25  is exemplified in the embodiments described above, but the curl eliminating device of the present disclosure can be applied not only to the inkjet printing type but also to other types of image forming apparatus such as an electrophotographic copier, printer, multifunction peripheral, or facsimile. 
     The present disclosure can be applied to a curl eliminating device that uses the decurl roller pair for correcting curl of a recording medium. By using the present disclosure, it is possible to provide a curl eliminating device having a simple structure that can suppress occurrence of offset due to dirt on the decurl roller pair and can improve a curl removing effect, and an image forming apparatus including the curl eliminating device.