Folding apparatus

Abstract

According to one embodiment, a folding apparatus includes a first fold reinforcing roller and a second fold reinforcing roller. The first and second fold reinforcing rollers are moved along a fold line of the sheet bundle while applying pressure to reinforce the fold line. The first fold reinforcing roller includes a first large diameter portion and a first small diameter portion. The first small diameter portion has a smaller diameter than the first large diameter portion. The second fold reinforcing roller includes a second large diameter portion and a second small diameter portion. The second large diameter portion faces the first small diameter portion. The second small diameter portion faces the first large diameter portion. The second small diameter portion has a smaller diameter than the second large diameter portion.

What is claimed is: 
     
         1 . A folding apparatus, comprising:
 a first fold reinforcing roller and a second fold reinforcing roller that move along a fold line of a sheet bundle while applying pressure to the fold line to reinforce the fold line,   wherein the first fold reinforcing roller includes:
 a first large diameter portion; and 
 a first small diameter portion having a diameter smaller than a diameter of the first large diameter portion, and 
   the second fold reinforcing roller includes:
 a second large diameter portion facing the first small diameter portion of the first fold reinforcing roller; and 
 a second small diameter portion facing the first large diameter portion of the first fold reinforcing roller and having a diameter smaller than a diameter of the second large diameter portion. 
   
     
     
         2 . The folding apparatus according to  claim 1 ,
 wherein the first fold reinforcing roller further includes a first intermediate portion positioned between the first large diameter portion and the first small diameter portion, and   the second fold reinforcing roller further includes a second intermediate portion positioned between the second large diameter portion and the second small diameter portion and facing the first intermediate portion.   
     
     
         3 . The folding apparatus according to  claim 1 ,
 wherein the diameter of the first large diameter portion is at least about equal to the diameter of the second large diameter portion.   
     
     
         4 . The folding apparatus according to  claim 1 , further comprising:
 a flexible member disposed between the sheet bundle, which is conveyed between the first fold reinforcing roller and the second fold reinforcing roller and the first fold reinforcing roller, and having flexibility.   
     
     
         5 . The folding apparatus according to  claim 1 , further comprising:
 a center folding roller that folds a center of the sheet bundle to form the fold line and conveying the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller.   
     
     
         6 . The folding apparatus according to  claim 5 ,
 wherein the center folding roller determines an advancing position of the fold line of the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller.   
     
     
         7 . The folding apparatus according to  claim 6 , further comprising:
 a controller that controls the advancing position of the fold line of the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller according to a number of sheets in the sheet bundle conveyed between the first fold reinforcing roller and the second fold reinforcing roller.   
     
     
         8 . The folding apparatus according to  claim 7 ,
 wherein the first fold reinforcing roller and the second fold reinforcing roller further include:
 a first region disposed upstream in an advancing direction via a stepped portion, in the advancing direction of the sheet bundle conveyed between the first fold reinforcing roller and the second fold reinforcing roller; and 
 a second region disposed downstream in the advancing direction via the stepped portion. 
   
     
     
         9 . The folding apparatus according to  claim 8 ,
 wherein, when the number of sheets is greater than a predetermined number of sheets, the controller aligns the advancing position of the fold line in the sheet bundle with the second region.   
     
     
         10 . The folding apparatus according to  claim 8 ,
 wherein, when the number of sheets is less than a predetermined number of sheets, the controller aligns the advancing position of the fold line of the sheet bundle with the first region.   
     
     
         11 . A folding method for an image forming apparatus, comprising:
 moving a first fold reinforcing roller and a second fold reinforcing roller along a fold line of a sheet bundle while applying pressure to the fold line to reinforce the fold line; wherein   the first fold reinforcing roller includes:
 a first large diameter portion; and 
 a first small diameter portion having a diameter smaller than a diameter of the first large diameter portion, and 
   the second fold reinforcing roller includes:
 a second large diameter portion facing the first small diameter portion of the first fold reinforcing roller; and 
 a second small diameter portion facing the first large diameter portion of the first fold reinforcing roller and having a diameter smaller than a diameter of the second large diameter portion. 
   
     
     
         12 . The folding method according to  claim 11 , further comprising:
 folding a center of the sheet bundle by a center folding roller to form the fold line; and   conveying the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller.   
     
     
         13 . The folding method according to  claim 12 , further comprising:
 determining an advancing position of the fold line of the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller by the center folding roller.   
     
     
         14 . The folding method according to  claim 13 , further comprising:
 controlling the advancing position of the fold line of the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller according to a number of sheets in the sheet bundle conveyed between the first fold reinforcing roller and the second fold reinforcing roller.   
     
     
         15 . An image forming apparatus, comprising:
 an image forming component; and   a folding apparatus, comprising:
 a first fold reinforcing roller and a second fold reinforcing roller that move along a fold line of a sheet bundle while applying pressure to the fold line to reinforce the fold line, 
   wherein the first fold reinforcing roller includes:
 a first large diameter portion; and 
 a first small diameter portion having a diameter smaller than a diameter of the first large diameter portion, and 
   the second fold reinforcing roller includes:
 a second large diameter portion facing the first small diameter portion of the first fold reinforcing roller; and 
 a second small diameter portion facing the first large diameter portion of the first fold reinforcing roller and having a diameter smaller than a diameter of the second large diameter portion. 
   
     
     
         16 . The image forming apparatus according to  claim 15 ,
 wherein the first fold reinforcing roller further includes a first intermediate portion positioned between the first large diameter portion and the first small diameter portion, and   the second fold reinforcing roller further includes a second intermediate portion positioned between the second large diameter portion and the second small diameter portion and facing the first intermediate portion.   
     
     
         17 . The image forming apparatus according to  claim 15 ,
 wherein the diameter of the first large diameter portion is at least about equal to the diameter of the second large diameter portion.   
     
     
         18 . The image forming apparatus according to  claim 15 , further comprising:
 a flexible member disposed between the sheet bundle, which is conveyed between the first fold reinforcing roller and the second fold reinforcing roller and the first fold reinforcing roller, and having flexibility.   
     
     
         19 . The image forming apparatus according to  claim 15 , further comprising:
 a center folding roller that folds a center of the sheet bundle to form the fold line and conveying the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller.   
     
     
         20 . The image forming apparatus according to  claim 19 ,
 wherein the center folding roller determines an advancing position of the fold line of the sheet bundle between the first fold reinforcing roller and the second fold reinforcing roller.