Saddle-stitch book binding system

A saddle-stitch book binding system, comprising:

• a conveying device for conveying sheets of paper along a conveying path;
• a cut paper supply device, or a folding device, or a cutter, connected to an upstream end of the conveying path;
• a collator arranged on an intermediate portion of the conveying path;
• a saddle stitching device connected to a downstream end of the conveying path;
• and
• a controller for integrally controlling the cut paper supply device, or the folding device, or the cutter, and the conveying device, the collator, and the saddle stitching device,
• wherein the collator is switchable between
• a non-operating mode,
• a first operating mode in which the collator operates as a collator, and
• a second operating mode in which the collator operates as an additional sheet supplying device, and
• wherein the cut paper supply device, or the folding device, or the cutter, that is connected to the upstream end of the conveying path, is stopped when the collator is operating in the first operating mode.