Sheet post-processing apparatus

Abstract

In an apparatus that performs saddle-stitching processing of a sheet pack, a pair of folding rollers is arranged in such a manner that large-diameter parts and small-diameter parts are alternately formed and that the large-diameter parts are abutted against the small-diameter parts at a facing part symmetrically about the center of a transport passage.

1 . A sheet post-processing apparatus comprising:
 a stitching processing unit configured to stitch a sheet pack transported in a transport passage, at predetermined plural positions in along a straight line orthogonal to the direction of the transport with a stitching needle;   a pair of folding rollers arranged on a stage following the stitching processing unit in the transport passage, in which large-diameter parts and small-diameter parts of the respective folding rollers are alternately formed symmetrically about the center of the transport passage, and in which facing parts are arranged at the central part in the transport passage so that the small-diameter parts are abutted against the large-diameter parts; and   a folding unit having a paper folding plate configured to push the sheet pack into an abutting part of the pair of folding rollers.   
     
     
         2 . The sheet post-processing apparatus according to  claim 1 , wherein the width of the large-diameter parts and the small-diameter parts of the folding rollers arranged at the central part of the transport passage is set to be smaller than a minimum width of the sheet pack transported in the transport passage. 
     
     
         3 . The sheet post-processing apparatus according to  claim 1 , wherein the total of the large-diameter part and the small-diameter part formed on each of the folding rollers is three or more. 
     
     
         4 . The sheet post-processing apparatus according to  claim 2 , wherein the total of the large-diameter part and the small-diameter part formed on each of the folding rollers is three or more. 
     
     
         5 . The sheet post-processing apparatus according to  claim 1 , wherein the difference in diameter between the large-diameter part and the small-diameter part formed on each of the folding rollers is 2 mm. 
     
     
         6 . The sheet post-processing apparatus according to  claim 2 , wherein the difference in diameter between the large-diameter part and the small-diameter part formed on each of the folding rollers is 2 mm.