Sheet conveyance apparatus

Abstract

A sheet conveyance apparatus includes a conveyance roller, an abutment member including an abutment surface, an obliquely conveying roller configured to convey the sheet such that the side edge portion is moved toward the abutment surface, a sheet side-edge detection portion, and a controller. The controller is configured to control the conveyance force of the obliquely conveying roller at a first conveyance force until a predetermined time has elapsed, in an abutment operation in which the sheet is abutted against the abutment surface by the obliquely conveying roller, and control the conveyance force of the obliquely conveying roller at a second conveyance force larger than the first conveyance force if the predetermined time has elapsed and the position of the side edge portion of the sheet detected by the sheet side-edge detection portion is out of a predetermined range.

What is claimed is: 
     
         1 . A sheet conveyance apparatus comprising:
 a conveyance roller configured to convey a sheet;   an abutment member including an abutment surface and configured to correct skew of the sheet, the abutment surface being disposed downstream of the conveyance roller and extending along a sheet conveyance direction, the abutment surface being a surface against which a side edge portion of the sheet in a width direction orthogonal to the sheet conveyance direction abuts;   an obliquely conveying roller disposed downstream of the conveyance roller in the sheet conveyance direction and configured to convey the sheet such that the side edge portion is moved toward the abutment surface;   a sheet side-edge detection portion configured to detect a position of the side edge portion of the sheet in the width direction and change an output value in accordance with the position of the side edge portion of the sheet conveyed by the obliquely conveying roller; and   a controller configured to control conveyance force applied by the obliquely conveying roller in the width direction of the sheet, in accordance with a detection result from the sheet side-edge detection portion,   wherein the controller is configured to 
 control the conveyance force of the obliquely conveying roller at a first conveyance force until a predetermined time has elapsed, in an abutment operation in which the sheet is abutted against the abutment surface by the obliquely conveying roller, and 
 control the conveyance force of the obliquely conveying roller at a second conveyance force larger than the first conveyance force if the predetermined time has elapsed and the position of the side edge portion of the sheet detected by the sheet side-edge detection portion is out of a predetermined range. 
   
     
     
         2 . The sheet conveyance apparatus according to  claim 1 , wherein the controller is configured to
 control rotational speed of the obliquely conveying roller at a first rotational speed if the conveyance force of the obliquely conveying roller is controlled at the first conveyance force, and   control the rotational speed of the obliquely conveying roller at a second rotational speed faster than the first rotational speed if the conveyance force of the obliquely conveying roller is controlled at the second conveyance force.   
     
     
         3 . The sheet conveyance apparatus according to  claim 1 , wherein the obliquely conveying roller includes 
 a driving roller configured to rotate, and   a driven roller, the driving roller being configured to drive the driven roller, the driving roller and the driven roller being configured to form a nip and convey a sheet while nipping the sheet in the nip, 
wherein the controller is configured to 
 control nip pressure of the nip at a first pressure if the conveyance force of the obliquely conveying roller is controlled at the first conveyance force, and 
 control the nip pressure of the nip at a second pressure higher than the first pressure if the conveyance force of the obliquely conveying roller is controlled at the second conveyance force. 
 
     
     
         4 . The sheet conveyance apparatus according to  claim 1 , wherein if the predetermined time has elapsed and the position of the side edge portion of the sheet detected by the sheet side-edge detection portion is within the predetermined range, the controller controls the conveyance force of the obliquely conveying roller at the first conveyance force until the abutment operation is completed. 
     
     
         5 . The sheet conveyance apparatus according to  claim 1 , wherein the predetermined time is a first time,
 wherein the conveyance roller is a first conveyance roller,   wherein the sheet conveyance apparatus further includes 
 a sheet downstream-edge detection portion disposed downstream of the obliquely conveying roller in the sheet conveyance direction and configured to detect an edge portion of the sheet on a downstream side in the sheet conveyance direction, and 
 a second conveyance roller disposed downstream of the sheet downstream-edge detection portion in the sheet conveyance direction and configured to convey the sheet, and 
   wherein the controller is configured to cause the second conveyance roller to convey the sheet if a second time has elapsed since the sheet downstream-edge detection portion detected the edge portion of the sheet on the downstream side.   
     
     
         6 . The sheet conveyance apparatus according to  claim 5 , wherein the controller is configured to separate the obliquely conveying roller from the sheet when the controller causes the second conveyance roller to convey the sheet. 
     
     
         7 . The sheet conveyance apparatus according to  claim 6 , wherein the obliquely conveying roller further includes
 a driving roller configured to rotate, and   a driven roller, the driving roller being configured to drive the driven roller, the driving roller and the driven roller being configured to form a nip and convey a sheet while nipping the sheet in the nip, and 
 wherein the controller is configured to remove the nip by separating the driven roller from the driving roller when the controller causes the second conveyance roller to convey the sheet. 
     
     
         8 . The sheet conveyance apparatus according to  claim 5 , wherein in a period of time from when the abutment operation is started until when the sheet downstream-edge detection portion detects the edge portion of the sheet on the downstream side, if the position of the side edge portion of the sheet detected by the sheet side-edge detection portion is within the predetermined range, the controller determines that the abutment operation has been completed. 
     
     
         9 . The sheet conveyance apparatus according to  claim 8 , further comprising:
 a first tray to which a sheet is discharged; and   a second tray to which a sheet is discharged and which is different from the first tray,   wherein a sheet on which the controller has determined that the abutment operation has been completed is discharged to the first tray, and   wherein a sheet that has reached the second conveyance roller in a state where the controller has determined that the abutment operation has not been completed on the sheet is discharged to the second tray.   
     
     
         10 . The sheet conveyance apparatus according to  claim 1 , further comprising an image forming portion configured to form an image on a sheet.