Sheet finisher, image forming apparatus using the same, and sheet finishing method

An image forming apparatus comprising:

• a read unit configured to read an original document and to generate image data;
• an image forming unit configured to print the image data to sheets;
• a fold unit configured to fold a sheet bundle of the printed sheets to form a fold line;
• a placement table on which the sheet bundle transported from the fold unit is placed;
• a band-like elastic member that is extended to face the fold line of the placed sheet bundle and is longer than the length of the fold line;
• and
• a roller unit that includes a reinforce roller and moves the reinforce roller along a direction of the fold line while pressing it to the fold line through the intervening elastic member, a circumferential surface of the reinforce roller being provided with a pinion, and a surface of the elastic member which comes in contact with the reinforce roller being provided with a rack.

A sheet finishing method, comprising:

• folding a sheet bundle to form a fold line;
• placing the sheet bundle of which the fold line is formed on a placement table after transporting the sheet bundle to the placement table;
• and
• reinforcing the fold line by moving a reinforce roller along a direction of the fold line while pressing it to the fold line through the intervening a band-like elastic member, the elastic member being extended to face the fold line of the placed sheet bundle and is longer than a length of the fold line, a circumferential surface of the reinforce roller being provided with a pinion, and a surface of the elastic member which comes in contact with the reinforce roller being provided with a rack.