Sheet processing apparatus

Abstract

A sheet processing apparatus includes a processing tray; a conveyance roller for conveying a sheet towards a downstream side in a sheet conveyance direction; a pinch roller for moving between a first position away from the conveyance roller and a second position close to the conveyance roller, and to sandwich the sheet with the conveyance roller at the second position when the sheet is conveyed by the conveyance roller. The apparatus further includes an extruding member for extruding an upstream end of the sheet from the upstream side towards the downstream side to convey the sheet placed on the processing tray. The apparatus additionally includes a controller for conveying the sheet with the extruding member after the sheet is conveyed by the pinch roller and the conveyance roller when the sheet on the processing tray is conveyed to the downstream side in the sheet conveyance direction.

What is claimed is: 
     
         1 . A sheet processing apparatus, comprising:
 a processing tray configured to stack a sheet;   a conveyance roller, arranged on a downstream side in a sheet conveyance direction with respect to the processing tray, configured to convey the sheet towards the downstream side in the sheet conveyance direction;   a pinch roller configured to move between a first position distal from the conveyance roller and a second position proximate to the conveyance roller, and to sandwich the sheet with the conveyance roller at the second position when the sheet is conveyed by the conveyance roller;   an extruder configured to extrude an end of an upstream sheet in the sheet conveyance direction from an upstream side towards the downstream side in the sheet conveyance direction to convey the sheet placed on the processing tray; and   a controller configured to control the conveyance roller, the pinch roller and the extruder to move the pinch roller to the second position when the sheet placed on the processing tray is conveyed to the downstream side in the sheet conveyance direction, move the pinch roller to the first position from the second position after the sheet is conveyed by the pinch roller and the conveyance roller, and then convey the sheet with the extruder.   
     
     
         2 . The sheet processing apparatus according to  claim 1 , wherein
 the controller is configured to apply a force towards the second position to the pinch roller when the sheet is conveyed by the pinch roller and the conveyance roller.   
     
     
         3 . The sheet processing apparatus according to  claim 1 , wherein
 the controller is configured to switch a selection between a roller discharge process for conveying the sheet only with the pinch roller and the conveyance roller and a combined discharge process for conveying the sheet with the pinch roller, the conveyance roller and the extruder, and   the controller is configured to switch the selection based on whether a number of sheets is less than a predetermined value.   
     
     
         4 . The sheet processing apparatus according to  claim 2 , wherein
 the controller is configured to switch a selection between a roller discharge process for conveying the sheet only with the pinch roller and the conveyance roller and a combined discharge process for conveying the sheet with the pinch roller, the conveyance roller and the extruder, and   the controller is configured to switch the selection based on whether a number of sheets is less than a predetermined value.   
     
     
         5 . The sheet processing apparatus according to  claim 3 , wherein
 the controller is configured to switch a selection between the roller discharge process or the combined discharge process and an extrusion discharge process for conveying the sheet only by the extruder, based on whether a sheet size is less than a threshold value.   
     
     
         6 . The sheet processing apparatus according to  claim 1 , wherein
 the controller is configured to drive the conveyance roller to rotate in the sheet conveyance direction prior to conveyance of the sheet by the extruder.   
     
     
         7 . The sheet processing apparatus according to  claim 2 , wherein
 the controller is configured to drive the conveyance roller to rotate in the sheet conveyance direction prior to conveyance of the sheet by the extruder.   
     
     
         8 . The sheet processing apparatus according to  claim 1 ,
 wherein the conveyance roller is configured to convey the sheet in the conveyance direction along a conveyance path,   wherein the conveyance path includes a first conveyance path, a second conveyance path, and a third conveyance path, the first and second conveyance paths being bifurcated from the first conveyance path.   
     
     
         9 . The sheet processing apparatus according to  claim 7 ,
 wherein the first conveyance path is arranged to guide the sheet to a standby section, the second conveyance path is configured to guide the sheet to a discharger, and the third conveyance oath is arranged to guide the sheet to the processing tray.   
     
     
         10 . The sheet processing apparatus according to  claim 1 , wherein the first position is a standby position and the second position is a rotational position. 
     
     
         11 . A sheet processing method, comprising:
 arranging a conveyance roller on a downstream side in a sheet conveyance direction with respect to a processing tray in which a sheet is stacked,   causing the conveyance roller to convey the sheet towards the downstream side in the sheet conveyance direction;   providing a pinch roller to move between a first position distal from the conveyance roller and a second position proximate to the conveyance roller, and to sandwich the sheet with the conveyance roller at the second posit ion when the sheet is conveyed by the conveyance roller;   causing an extruder to extrude an end of an upstream sheet in the sheet conveyance direction from an upstream side towards the downstream side in the sheet conveyance direction to convey the sheet placed on the processing tray; and   controlling, by a controller, the conveyance roller, the pinch roller and the extruder to move the pinch roller to the second position when the sheet placed on the processing tray is conveyed to the downstream side in the sheet conveyance direction, move the pinch roller to the first position from the second position after the sheet is conveyed by the pinch roller and the conveyance roller, and then convey the sheet with the extruder.   
     
     
         12 . The sheet processing method according to  claim 11 , further comprising:
 applying a force towards the second position to the pinch roller when the sheet is conveyed by the pinch roller and the conveyance roller.   
     
     
         13 . The sheet processing method according to  claim 11 , further comprising:
 switching a selection between a roller discharge process for conveying the sheet only with the pinch roller and the conveyance roller and a combined discharge process for conveying the sheet with the pinch roller, the conveyance roller and the extruder,   wherein the switching is performed based on whether a number of sheets is less than a predetermined value.   
     
     
         14 . The sheet processing method according to  claim 12 , further comprising:
 switching a selection between a roller discharge process for conveying the sheet only with the pinch roller and the conveyance roller and a combined discharge process for conveying the sheet with the pinch roller, the conveyance roller and the extruder,   wherein the switching is performed based on whether a number of sheets is less than a predetermined value.   
     
     
         15 . The sheet processing method according to  claim 13 , further comprising:
 switching a selection between the roller discharge process or the combined discharge process and an extrusion discharge process for conveying the sheet only by the extruder, based on whether a sheet size is less than a threshold value.   
     
     
         16 . The sheet processing method according to  claim 11 , further comprising:
 driving the conveyance roller to rotate in the sheet conveyance direction prior to conveyance of the sheet by the extruder.   
     
     
         17 . The sheet processing method according to  claim 12 , further comprising:
 driving the conveyance roller to rotate in the sheet conveyance direction prior to conveyance of the sheet by the extruder.   
     
     
         18 . The sheet processing method according to  claim 11 , further comprising:
 conveying, by the conveyance roller, the sheet in the conveyance direction along a conveyance path,   wherein the conveyance path includes a first conveyance path, a second conveyance path, and a third conveyance path, the first and second conveyance paths being bifurcated from the first conveyance path.