Patent Publication Number: US-8991817-B1

Title: Paper conveyance apparatus

Description:
FIELD 
     Embodiments described herein relate to a paper conveyance apparatus which corrugates a paper corresponding to the thickness of the paper and conveys the paper. 
     BACKGROUND 
     Conventionally, the position or intensity of the corrugations added in a direction orthogonal to the conveyance direction of a paper conveyance surface, i.e., a paper width direction, is changed to prevent the front end of a paper from hanging down. 
     However, a mechanical control needs to be carried out based on a sensor for detecting the width of a paper, a sensor for detecting the thickness of a paper and the detection results of the sensors. Consequently, more components are needed to carry out corrugating processing, which leads to an increase in cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an image forming apparatus provided with a paper conveyance apparatus according to a first embodiment; 
         FIG. 2  is a perspective view illustrating a portion of the paper conveyance apparatus shown in  FIG. 1 ; 
         FIG. 3  is a perspective view illustrating the portion of the paper conveyance apparatus observed from the direction indicated by an arrow A shown in  FIG. 1 ; 
         FIG. 4  is a perspective view illustrating the portion of the paper conveyance apparatus shown in  FIG. 1 ; 
         FIGS. 5 and 6  are each side views of the portion of the paper conveyance apparatus shown in  FIG. 1 ; 
         FIG. 7A  is a diagram illustrating an effect of  FIG. 5 ; 
         FIG. 7B  is a diagram illustrating an effect of  FIG. 6 ; 
         FIG. 8  is a diagram illustrating an effect of the first embodiment; 
         FIG. 9  is a perspective view of a portion of a paper conveyance apparatus, according to a second embodiment; 
         FIG. 10  is a side view of a portion of a paper conveyance apparatus, according to a third embodiment; 
         FIG. 11  is a side view of the portion of the paper conveyance apparatus according to the third embodiment; 
         FIG. 12  is a perspective view of a portion of a paper conveyance apparatus according to a fourth embodiment; 
         FIG. 13  is a side view of the portion of the paper conveyance apparatus according to the fourth embodiment; 
         FIG. 14  is a front view of a portion of a paper conveyance apparatus according to a fifth embodiment; and 
         FIG. 15  is a diagram illustrating an effect of the fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A paper conveyance apparatus according to an embodiment includes a roller pair including a drive roller and a driven roller configured to discharge a paper from a main body of an image forming apparatus. The paper conveyance apparatus further includes a corrugation component configured to abut against the paper discharged by the roller pair to corrugate the paper as the paper is discharged, and an elastic component configured to push the corrugation component against the discharged paper. 
     Embodiments of the present invention are described in detail below with reference to accompanying drawings. 
     A First Embodiment 
       FIG. 1  is a schematic diagram of an image forming apparatus provided with a paper conveyance apparatus  100  according to a first embodiment. The paper conveyance apparatus  100  carries out a paper post-processing, which includes stapling, sorting, hole punching, and saddle-stitching. A paper processing apparatus carrying out a stapling processing is described herein. 
     A fixed tray  75  is arranged on the upper portion of a paper conveyance apparatus  100 . The fixed tray  75  is inclined so that the front end of a loaded paper P is higher than the rear end of the paper. A pair of paper discharging rollers  76  and  77  serving as a discharging mechanism for clamping and conveying a paper P is arranged adjoining a paper discharge port  71  of the fixed tray  75 . A fixed tray path  74  is arranged between an inlet roller  22  for receiving a paper P from an apparatus at the front end of an image forming apparatus  5  and the paper discharge port  71  to guide the paper P to the paper discharging rollers  76  and  77 . 
     A plurality of tray ribs  80  are arranged below the paper discharge port  71  as a rear end supporter for supporting the rear end of a paper P. The fixed tray  75  and the tray ribs  80  are integrally molded. A sensor  81  is arranged above the paper discharge port  71  to detect the loading limit of the papers P on the fixed tray  75 . 
     As stated above, the fixed tray  75  is arranged in an inclined state so that the front end of a paper P is higher than the rear end of the paper P. Thus, due to the inclination of the fixed tray  75 , a paper P conveyed to the fixed tray  75  returns towards the direction indicated by an arrow x, that is, the rear end direction of the sheet. Then the rear end of the paper P is abutted against the tray ribs  80 , thereby longitudinally aligning the papers P. Similarly, the papers P discharged from the image forming apparatus  5  are successively discharged to the fixed tray  75  until a given number of papers are loaded, and then the papers are longitudinally aligned. 
     A standby tray  10  is arranged below the fixed tray  75 . A paper path  36  is arranged between the inlet roller  22  and the standby tray  10  to guide a paper P to a pair of paper feed rollers (paper feed section)  24 . Further, an outlet sensor  60  is arranged between the paper feed rollers  24  and the standby tray  10 . In the present embodiment, the outlet sensor  60  is arranged adjoining the paper feed rollers  24 . The outlet sensor  60  detects a paper P conveyed through the paper path  36 . The paper feed rollers  24  convey a paper P while clamping the paper P. A processing tray  12  is arranged below the standby tray  10  for loading the papers P falling from the standby tray  10 , that is, from the position between moving tray components  10   a  and  10   b  (See  FIG. 2 , discussed further below). A roller pair, consisting of a drive roller  19   a  and a driven roller  19   b  in contact with each other under a specified pressure, is located at the downstream side of the paper feed rollers  24 , and conveys the paper P conveyed by the paper feed rollers  24 . The drive roller  19   a  and the driven roller  19   b  are made from, for example, rubber. 
     The processing tray  12  aligns and supports loaded papers P during a paper stapling process carried out by a stapler  14 . In this embodiment, the stapler  14  serves as a processing mechanism carrying out a paper post-processing. The processing tray  12  is inclined downwards facing the stapler  14 , and is provided with a pair of alignment rollers  38   a  and  38   b  which align the papers P falling from the standby tray  10  in a longitudinal direction, that is, a conveyance direction. The alignment rollers  38   a  and  38   b , which are arranged close to the stapler  14 , additionally function as bundle conveyance rollers which clamp a stapled paper bundle and take out the stapled paper bundle from the stapler  14 . 
     Further, when a paper P falls into the processing tray  12  from the standby tray  10 , a paddle  44  loaded on the processing tray  12  is arranged at the position where the rear end of the paper P falls. The paddle  44  can be rotated to align the top papers P in a longitudinal direction. The paddle  44  has elasticity and is made from, for example, rubber. 
     A stopper  45  which is abutted against the rear end of a paper P to regulate the position of the rear end is arranged at the end part of the processing tray  12  at the side of the stapler  14 . A conveyance belt  50  is arranged substantially in the center of the processing tray  12 . The conveyance belt  50  conveys a paper bundle which is stapled and taken out from the stapler  14  by the alignment rollers  38   a  and  38   b  to a first paper discharging tray (discharging section)  16 . A conveyance claw  50   a  is arranged on the conveyance belt  50  to hook the rear end of the paper bundle. 
     The standby tray  10  is capable of making a paper P fall into the processing tray  12 . On the other hand, the standby tray  10  is also capable of conveying a paper P needing no stapling to the direction of the first paper discharging tray  16 . The conveyance of a paper P to the first paper discharging tray  16  is realized through the roller pair consisting of, for example, the drive roller  19   a  and the driven roller  19   b , by contacting with the paper P on the standby tray  10 . 
     The drive roller  19   a  is driven to rotate by a rotation solenoid  63  through an arm  64  and is also rotationally driven by a conveyance motor (not shown) which is connected with a first roller shaft  19   d  which can rotationally support the drive roller  19   a . When abutted against the drive roller  19   a , the driven roller  19   b  is rotated through the rotation of the drive roller  19   a . A nip is formed between the driven roller  19   b  and the drive roller  19   a  when the driven roller  19   b  is abutted against the drive roller  19   a.    
     A corrugation component  25 , which will be described later, is arranged above position where a paper P is discharged through the roller pair consisting of, for example, the drive roller  19   a  and the driven roller  19   b.    
       FIG. 2  is a perspective view of the standby tray  10 . The standby tray  10  is inclined so that the front end of a paper P is higher than the rear end of the paper. The standby tray  10  consists of a pair of tray components  10   a  and  10   b , which slide in the width direction of a paper P, and is configured to receive a paper P and support two sides of the paper P. The standby tray  10  is moved by a standby tray motor (not shown) to slide. The tray component  10   a  slides in the direction indicated by an arrow y and a direction reverse to the direction indicated by an arrow y. The tray component  10   b  slides in the direction indicated by an arrow z and a direction reverse to the direction indicated by an arrow z. The driven roller  19   b  arranged on the standby tray  10  is moved to slide through the slide movement of the standby tray  10 . 
     A series of flows of the papers P in the paper conveyance apparatus  100  are described below. There are three conveyance paths for papers P: a first conveyance path through which a paper P is discharged to the fixed tray  75  without being stapled; a second conveyance path through which a paper P is discharged to the paper discharging tray  16  without being stapled; and a third conveyance path through which a paper P is stapled and discharged from the processing tray  12  to the paper discharging tray  16 . 
     The first conveyance path is described first. In a case where a paper is discharged to the fixed tray  75  without being stapled, a paper P discharged from the paper feed roller  6  of the image forming apparatus  5  is received by the inlet roller  22  and conveyed to the paper discharging rollers  76  and  77  through the tray path  74  and then discharged to the fixed tray  75 . The papers P discharged from the image forming apparatus  5  are successively discharged to the fixed tray  75  until a given number of papers are loaded, and then the papers are longitudinally aligned. 
     The second conveyance path is now described. In a case where a paper P is discharged to the first paper discharging tray  16  without being stapled, for example, the paper discharging tray  16  slides to the position indicated by the dotted line shown in  FIG. 1  in advance. When no stapling processing is needed, the paper P conveyed to the inlet roller  22  is conveyed from the inlet roller  22  to the paper feed roller  24  through the paper path  36  and is fed to the standby tray  10  by the paper feed roller  24 . Sequentially, the paper P is conveyed on the standby tray  10  by the drive roller  19   a  and the driven roller  19   b  and discharged to the paper discharging tray  16 . 
     The third conveyance path is now described. When a paper P is subjected to a stapling processing, the tray components  10   a  and  10   b  of the standby tray  10  slide so that the paper P can be supported. The paper P discharged from the image forming apparatus  5  and fed by the paper feed roller  24  is, for example, loaded on the standby tray  10  to wait for the completion of the stapling processing of the preceding paper P on the processing tray  12 . A plurality of papers P are loaded on the standby tray  10  during the period of the processing carried out in the processing tray  12 . 
     If the preceding paper P on the processing tray  12  is discharged to the paper discharging tray  16  and a preceding stapling processing carried out in the processing tray  12  is completed, the tray component  10   a  shown in  FIG. 2  slides in the direction indicated by the arrow y, and the tray component  10   b  slides in the direction indicated by the arrow z. Then, the paper P loaded on the standby tray  10  falls into the processing tray  12 . After the stapling processing, the conveyance belt  50  is driven to hook the rear end of a stapled paper bundle T with the conveyance claw  50   a  to convey the paper bundle T to the paper discharging tray  16 . 
     When conveying a paper P of a long size is to be conveyed to the standby tray  10 , the paper P can be conveyed to the standby tray  10  through the conveyance based on the paper feed roller  24  even if the drive roller  19   a  is separated from the driven roller  19   b . The driven roller  19   b , if separated from the drive roller  19   a , has no conveyance force to convey a paper P. However, a paper P of a long size such as FOLIO, due to its sufficient length, can be conveyed to the standby tray  10  by the paper feed roller  24  at the upstream side of the driven roller  19   b.    
     In this case, as the paper P of a long size such as FOLIO is long in longitudinal direction, the paper P can be prevented from hanging down even if the drive roller  19   a  is separated from the driven roller  19   b  or the paper is corrugated by the corrugation component  25 , and the paper contacts the paper discharging tray  16 . Even in the conveyance of a paper P in the aforementioned third conveyance path, the front end of the paper P contacts the paper discharging tray  16  when the paper P is waiting on the standby tray  10 . 
       FIG. 3  is a perspective view illustrating a portion of the paper conveyance apparatus  100  observed from the direction indicated by an arrow A shown in  FIG. 1 .  FIG. 3  illustrates the final stage of the aforementioned second conveyance path through which the paper P is discharged to the first paper discharging tray  16  without being stapled. In order to illustrate the relation among the first roller shaft, the second roller shaft and the corrugation component  25 , the tray components  10   a  and  10   b  are not shown in  FIG. 3 . 
     A plurality of (four, in the example shown in  FIG. 3 ) roller pairs are arranged at given intervals in a direction orthogonal to the conveyance direction of papers. The interval and the number of the roller pairs can be properly changed according to the maximum or minimum width of the papers processed by the image forming apparatus. The roller pair consists of the drive roller  19   a  and the driven roller  19   b  which are contacted with each other under a specified pressure. 
     The drive roller  19   a  rotates around the first roller shaft  19   d , arranged orthogonal to the conveyance direction of papers, as a center. The driven roller  19   b  rotates around the second roller shaft  19   e , arranged parallel to the first roller shaft  19   d , as a center. Further, the drive roller  19   a  and the driven roller  19   b  are arranged in such a manner that the drive roller  19   a  is above the driven roller  19   b  and opposite to the driven roller  19   b  in the vertical direction. 
     The first roller shaft  19   d  may be, for example, a metal shaft. Further, the first roller shaft  19   d  rotates bi-directionally using a motor (not shown) as a drive source. A plurality of drive rollers  19   a  are arranged on the first roller shaft  19   d . Thus, the plurality of drive rollers  19   a  integrated with the first roller shaft  19   d  are rotated as the first roller shaft  19   d  is rotated. 
     Each of the driven rollers  19   b  is supported to rotate separately around the second roller shaft  19   e  as a center. The drive roller  19   a  is pressed to each of the driven rollers  19   b  by a roller pressing component, which may be, for example, a spring component (not shown). 
     Moreover, in addition to the plurality of roller pairs, the paper discharging section is further provided with the corrugation component  25 . The corrugation component  25  is an arm-shaped component which corrugates the paper discharged by the roller pair. A member  251  at one end of the corrugation component  25  can rotationally support a shaft  26 . The corrugation component  25  is orthogonal to the shaft  26  and is supported in such a state that the corrugation component  25  extends downstream in the paper conveyance direction. 
     As shown in  FIG. 4 , a corrugation section  252  for pressing a paper P is formed on the lower side of the other end of the corrugation component  25 . An engaging section  255  is formed by integrating an engaging concave section  253  with an engaging piece  254  at a position opposite to the engaging concave section  253 . The engaging section  255  is arranged on the corrugation component  25  between the corrugation section  252  and the member  251 . The engaging section  255  is engaged around the first roller shaft  19   d . The engaging concave section  253  is engaged with the first roller shaft  19   d  with a play of distance L therebetween (refer to  FIG. 5 ). Therefore, the engaging concave section  253  can move a little in a direction orthogonal to the first roller shaft  19   d.    
     Herein, in the paper conveyance apparatus according to the present embodiment, a center reference method in which a paper is conveyed by taking the center of the width of the paper as a reference is adopted as a paper conveyance method. In the use of the center reference method, even if the width of papers conveyed in the paper conveyance path is changed, the centers of the width of the papers pass a common center reference position. Thus, in the direction of a rotation shaft of the roller pair orthogonal to the paper conveyance direction, the two inner drive rollers  19   a  are arranged at positions the same distance away from the center reference position. The two outer drive rollers  19   a  are also arranged at positions the same distance away from the center reference position. 
     A spring  27  is arranged between the member  251  and the engaging section  255  of the corrugation component  25  as an elastic component. One end of the spring  27  is engaged with a locking section  256  which is integrally formed on the corrugation component  25 . The other end of the spring  27  is engaged with, for example, a frame  28  in the main body of the paper conveyance apparatus  100  (refer to  FIG. 5 ). The elastic component may also be a cushion material or the like. 
     Thus, the corrugation component  25  is pressed by taking the member  251  as the center in the direction indicated by the arrow B shown in  FIG. 5  through the elastic force of the spring  27 . The range of the pressing distance of the corrugation component is equivalent to the distance L of the play between the first roller shaft  19   d  and the engaging section  255  as shown in  FIG. 5 . 
     Operations of the corrugation component  25  are described herein with reference to  FIG. 5  and  FIG. 6 . 
     The thickness of the paper P used in  FIG. 5  is t1 and that of the paper P used in  FIG. 6  is t2. In this example, the thicknesses t1 and t2 meet the following condition: t1&lt;t2. Further, the papers used in  FIG. 5  and  FIG. 6  are made from the same material. 
     First, the paper P having a thickness t1 used in  FIG. 5  is discharged through the roller pair. One part of the paper P is abutted against the corrugation section  252  under the elastic force of the spring  27  during the discharging process. The part of the paper P abutted against the corrugation section  252  is pressed to be corrugated.  FIG. 7A  illustrates a state in which the paper P having a thickness t1 is corrugated. At this time, the angle of the corrugation shown in  FIG. 7A  is set to be θ1. 
     Similarly, the paper P having a thickness t2 used in  FIG. 6  is discharged through the roller pair. One part of the paper Pis abutted against the corrugation section  252  under the elastic force of the spring  27  during the discharging process. The part of the paper P abutted against the corrugation section  252  is pressed to be corrugated.  FIG. 7B  illustrates a state in which the paper P having a thickness t2 is corrugated. The angle of the corrugation shown in  FIG. 7B  is set to be θ2 at this time. 
     As noted above, the papers P having a thickness t1 and a thickness t2 are made from the same material. Accordingly, the paper P having the thickness t2 has stronger resistance to the elastic force of the spring  27 . As the thickness t2 is greater than the thickness t1, the angles of the corrugations meet the following relationship: θ1&gt;θ2. As a result, the paper P having a thickness t1 is greatly corrugated. 
     In this way, a thin paper P can be corrugated greatly. Thus, an adjustment can be made to corrugate a paper properly corresponding to the thickness of the paper P. 
     The thickness of a paper is taken into consideration in the description above. Moreover, papers made from different materials can be corrugated corresponding to materials thereof under the effect of the elastic component. 
       FIG. 8  illustrates a comparison on paper conveying loads for the conventional corrugation component and the corrugation component described in the present embodiment. According to the results of five times of measurement, the average conveying load of the conventional corrugation component is 168 gf and that of the corrugation component described in the present embodiment is 115 gf. 
     From the results illustrated in  FIG. 8 , it can be concluded that the corrugation component  25  described in the present embodiment is capable of reducing conveying load. Thus, a smooth paper conveyance can be achieved even in the use of a corrugation component. 
     Papers can be conveyed smoothly in the present embodiment. Further, an elastic component for applying elasticity in the direction of a paper is arranged on the corrugation component which corrugates the paper. Thus, a paper can be properly corrugated without using a sensor for detecting the thickness of a paper. 
     A Second Embodiment 
       FIG. 9  is a perspective view of the corrugation component  25  illustrating a second embodiment of the paper conveyance apparatus. The corrugation component  25  described in the first embodiment slides with respect to a paper P while applying a pressing force to the paper P, thereby corrugating the paper P using the corrugation section  252 . However, the paper may not be corrugated smoothly if the paper P is thick or the smoothness of the surface of the paper P is poor. 
     Thus, in the second embodiment, a corrugation roller  257  is arranged at a position equivalent to the position of the corrugation section  252  described in the first embodiment. 
     A support hole  2571  is formed on the corrugation roller  257 . Two support shafts  258   a  and  258   b , which may be integrally formed on the corrugation component  25 , are inserted into the support hole  2571  to rotationally support the support hole  2571 . Locking claws  258   c  and  258   d , each facing opposite directions, are formed on the front ends of the support shafts  258   a  and  258   b . The locking claws  258   c  and  258   d  have elasticity. The corrugation roller  257  is pushed against the locking claws  258   c  and  258   d  to close the two locking claws to each other. Consequently the corrugation roller  257  is positioned around the support shafts  258   a  and  258   b , and then the locking claws  258   c  and  258   d  returns to the original position. Thereby, the corrugation roller  257  is rotationally supported. 
     The corrugation roller  257  corrugates the paper P while rotating on the paper P. The friction between the paper P and the corrugation component  25  due to the elasticity of the spring  27  can be reduced. 
     In the presently described second embodiment, a paper can be conveyed smoothly even if the friction between the paper P and the corrugation component is increased as the paper P is thick or the smoothness of the surface of the paper is poor. 
     A Third Embodiment 
       FIG. 10  is a side view of a portion of a third embodiment of the corrugation component  25 . 
     In the present embodiment, instead of the spring  27  described in the first embodiment, a weight  81  is arranged on the corrugation component  25 . The weight  81  is arranged on a corrugation component  25  far away from the shaft  26  which is rotationally supported. Moreover, a cushion material  82  is arranged between the engaging concave section  253  and the first roller shaft  19   d  between which a play is set. The cushion material  82  is arranged to prevent a mechanical noise caused by the contact of the engaging concave section  253  with the first roller shaft  19   d  during the conveyance process of a paper P. The corrugation component  25  is pressed towards the direction of the paper P by the weight  81 . 
     The effect of the third embodiment is described herein with reference to  FIG. 10  and  FIG. 11 . The present embodiment is also described by taking the papers P used in  FIG. 10  and  FIG. 11  which are made from the same material but have different thicknesses as an example. The thickness of the paper P used in  FIG. 10  is set to be t1 and that of the paper P used in  FIG. 11  is set to be t2. The thicknesses t1 and t2 meet the following relationship: t1&lt;t2. 
     Thus, the thickness t1 of the paper P used in  FIG. 10  is smaller than the thickness t2 of the paper P used in  FIG. 11 , and the corrugations generated by the weight  81  is as that shown in  FIG. 7A . Similarly, the thickness t2 of the paper P used in  FIG. 11  is greater than the thickness t1 of the paper P used in  FIG. 10 , and the corrugations generated by the weight  81  is as that shown in  FIG. 7B . 
     Thus, with the use of the weight  81 , a thin paper P can be corrugated greatly while a thick paper P can be corrugated slightly. Further, the corrugation section  252  abutted against a paper P may also be the corrugation roller  257  described in the second embodiment. 
     In this embodiment, a paper can be properly corrugated corresponding to the paper by pressing a corrugation component for corrugating a paper towards the direction of the paper. 
     A Fourth Embodiment 
       FIG. 12  is a perspective view of the corrugating component  25  according to a fourth embodiment. In the fourth embodiment, the spring  27  or the weight  81  described in the embodiments above is replaced by an elastic piece  259 . 
     The elastic piece  259  is integrally formed on the corrugation component  25  in the opened part of the engaging concave section  253  opposite to the engaging piece  254 . The elastic piece  259  has elasticity in a direction orthogonal to the first roller shaft  19   d . The first roller shaft  19   d  is arranged between the engaging piece  254  and the elastic piece  259 . The corrugation component  25  rotates around the shaft  26  as the center according to the thickness of a paper P. 
     The engaging piece  254  is engaged with the first roller shaft  19   d  with a play of distance G therebetween (refer to  FIG. 13 ). Therefore, the engaging concave section  253  can move a little in a direction orthogonal to the first roller shaft  19   d . The range of the pressing distance of the corrugation component is equivalent to the distance G of the play between the first roller shaft  19   d  and the engaging piece  254  as shown in  FIG. 13 . That is, the corrugation component  25  rotates when the thickness of a paper P is increased so as to adjust the extent of the corrugation. In the case of a thin paper P, the corrugation component  25  resists to the elasticity of the elastic piece  259  to corrugates the thin paper P to a lesser extent. In the case of a thick paper P, the corrugation component  25  restricts the extent of corrugation based on the elastic piece  259  and corrugates the thick paper P. 
     The papers, which are made from the same material with respective thicknesses t1 and t2 having the relationship t1&lt;t2, are also taken as an example in the present embodiment. When the paper P having the thickness t1 passes through the corrugation section  252 , the corrugation component  25  does not rotate, and a corrugation generated on the paper P is in a state equivalent to the state shown in  FIG. 7A . When the paper P having the thickness t2 passes through the corrugation section  252 , the corrugation component  25  rotates. In this way, the generated corrugation is in a state equivalent to the state shown in  FIG. 7B . 
     Thus, with elastic piece  259 , a thin paper P can be corrugated greatly and a thick paper P can be corrugated slightly, thereby a paper can be properly corrugated. 
     A Fifth Embodiment 
       FIG. 14  is a side view of the corrugating component  25  according to a fifth embodiment. 
     In the embodiments described, a paper P is corrugated by the corrugation component  25 . Moreover, the widths of the tray components  10   a  and  10   b  of the standby tray  10  are adjusted according to the size of a paper P while positions of the drive roller  19   a  and the driven roller  19   b  are adjusted. 
     The distance between each roller pair (drive roller  19   a  and corresponding driven roller  19   b ) should be as wide as possible according to the size of the paper P without narrowing the conveyance nip between the drive roller  19   a  and the driven roller  19   b . The adjustment of the distance between the roller pairs is indicated by arrows in  FIG. 14 . 
     Residual paper conveyance forces obtained when the width of a standby tray is changed in the conventional corrugation component and in the corrugation component described in the present embodiment are compared in  FIG. 15 . The residual conveyance force represents the residual conveyance force obtained when temperature drops and the friction coefficient between the drive roller  19   a  and the driven roller  19   b  made from rubber is reduced. 
       FIG. 15  shows measurement results on residual conveyance forces obtained when the clamping width of a paper P based on the tray components  10   a  and  10   b  is changed and when a condition for the corrugation component is changed. Clamping widths of 165 mm and 177.4 mm are taken as examples of changed clamping widths of a paper P. The change in a condition for the corrugation component refers to: (1) the use of the conventional corrugation component, (2) the use of the corrugation component described in the present embodiment and (3) no use of a corrugation component. 
     As shown in  FIG. 15 , residual conveyance force was measured five times for each combination of the clamping widths and corrugation component. In the case where the width of the tray components  10   a  and  10   b  of the standby tray  10  is 165 mm, the average residual conveyance force is 32 gf in the use of the conventional corrugation component, 108 gf in the use of the corrugation component described herein and 500 gf when no corrugation component is used. Similarly, in the case where the width of the tray components  10   a  and  10   b  is 177.4 mm, the average residual conveyance force is 159 gf in the use of the conventional corrugation component, 220 gf in the use of the corrugation component described herein and 500 gf when no corrugation component is used. 
     When the corrugation component  25  described in the present embodiment is used, conveying load is reduced, as shown in  FIG. 8 , while residual conveyance force is increased, as shown in  FIG. 15 . Thus, even in the use of a corrugation component, a paper can be conveyed smoothly while the residual conveyance force required for conveyance can be guaranteed. 
     Papers can be conveyed smoothly even in the use of a corrugation component in the present embodiment. Moreover, by adjusting the gap between the drive roller and the driven roller matching with the size of a paper, residual conveyance force is obtained without narrowing the conveyance nip. 
     In the aforementioned embodiments, an example is described in which only one corrugation component is arranged in the center of the standby tray  10 , however, the present invention is not limited to this, a plurality of corrugation components may be arranged. Further, the conveyance of a paper is based on a center reference; however, a paper may also be conveyed even if the paper deviates in a direction orthogonal to the paper conveyance direction. In this case, it is preferred that a plurality of corrugation components are arranged corresponding to the size of the paper. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.