Sheet post-processing apparatus

Abstract

A sheet post-processing apparatus comprises a pair of alignment plates for aligning the plurality of sheets conveyed from an image forming apparatus at the two lateral sides, the pair of alignment plates being movable by a predetermined distance in a direction perpendicular to the direction of conveyance of the sheets, and a stapler also movable along the leading edge of the aligned plurality of sheets. The stapler moves according to the alignment position of the sheets and staples the sheets at a plurality of positions corresponding to the alignment position. As the stapled bundles of sheets are sequentially discharged, they are stacked on a delivery tray in a zigzag manner.

1 . A sheet post-processing apparatus for aligning a plurality of sheets conveyed from an image forming apparatus and stapling and delivering them, said apparatus comprising: 
 a processing tray capable of carrying a plurality of sheets conveyed from the image forming apparatus;    alignment means including a pair of alignment plates for aligning the plurality of sheets carried by the processing tray at the two lateral sides running in the direction of conveyance of the plurality of sheets, the pair of alignment plates being movable between a first alignment position and a second alignment position displaced from the first alignment position by a predetermined distance in a direction perpendicular to the direction of conveyance; and    staple means including a stapler movable along the leading edge of the plurality of sheets aligned by the alignment means in the direction of conveyance and adapted to move the stapler according to the change of alignment position in order to staple the conveyed sheets at a plurality of positions;    the sheets stapled at the first alignment position and those stapled at the second alignment position being sequentially discharged and led to a delivery tray so as to shift the staple positions of the bundles of sheets stacked on the delivery tray in a zigzag manner.    
     
     
         2 . The apparatus according to  claim 1 , wherein 
 the staple positions and the gap separating the staples are held same among the bundles of sheets when the bundles of sheets stapled by the staple means have the same size.    
     
     
         3 . The apparatus according to  claim 2 , wherein, 
 when the gap separating the staples of each bundle of sheets stapled by the staple means is L 1 , the positional shift L 2  of an upper bundle of sheets stacked on the delivery tray from a lower bundle of sheets stacked on the delivery tray is defined by L 2 <L 1 /2.    
     
     
         4 . A sheet post-processing apparatus for aligning a plurality of sheets conveyed from an image forming apparatus and stapling and delivering them, said apparatus comprising: 
 a processing tray capable of carrying a plurality of sheets conveyed from the image forming apparatus;    alignment means including a pair of alignment plates for aligning the plurality of sheets carried by the processing tray at the two lateral sides running in the direction of conveyance of the plurality of sheets, the pair of alignment plates being capable of reciprocating between a first alignment position and a second alignment position displaced from the first alignment position by a predetermined distance in a direction perpendicular to the direction of conveyance;    a stapler movable along the leading edge of the plurality of sheets aligned by the alignment means in the conveyance direction;    a control section for controlling the staple so as to cyclically move it along the staple positions according to the change of alignment position of the alignment means, the control section moving the stapler in the first direction when the alignment means is at the first alignment position and causing it to staple the sheets at a plurality of positions along the moving route, the control section moving the stapler in the direction opposite to the first direction when the alignment means is at the second alignment position and causing it to staple the sheets at a plurality of positions along the moving route; and    a delivery section for leading the sheets stapled at the first alignment position and those stapled at the second alignment position to a delivery tray;    the staple positions of the bundles of sheets stacked on the delivery tray being shifted in a zigzag manner.    
     
     
         5 . The apparatus according to  claim 4 , wherein 
 the control means controls the position of the staple according to the alignment position in such a way that it moves the stapler in the first direction at the first alignment position and operates the stapler to staple the sheets at a first position and at a second position located along the moving direction but    it moves the stapler to a third position separated from the second position by a predetermined distance in the first direction when the alignment means is driven to move to the second alignment position and    it moves the stapler in the direction opposite to the first direction at the second alignment position and operates the stapler to staple the sheets at a third position and at fourth position located along the moving direction, while    it moves the stapler to the first position separated from the fourth position by a predetermined distance when the alignment means is driven to return to the first alignment position.    
     
     
         6 . The apparatus according to  claim 4 , wherein 
 when the gap separating the staples of each bundle of sheets stapled by the staple means at the first and second alignment positions is L 1 , the predetermined distance L 2  by which the stapler is moved according to the move of alignment position of the alignment means is defined by L 2 <L 1 /2.    
     
     
         7 . The apparatus according to  claim 4 , wherein 
 the alignment means includes a second alignment means for aligning the plurality of sheets at the leading edge thereof in the direction of conveyance in addition to the pair of alignment plates for aligning the plurality of sheets carried by the processing tray from the two lateral sides running in the direction of conveyance of the plurality of sheets.    
     
     
         8 . The apparatus according to  claim 4 , wherein 
 the second alignment means is arranged at the stapler and includes a stopper for receiving the leading edge of the sheets in the direction of conveyance.