PROBLEM TO BE SOLVED: To efficiently reduce bulging of a booklet with required-minimum energy consumption without causing wrinkles or tearing or the like on a spine, a binding part, or inside the fold or the like of a saddle-stitched booklet. SOLUTION: A booklet processor is configured as follows. A transfer roller Rer is located on an upstream side in a booklet transfer direction of a pressing and clamping member 350. The pressing and clamping member 350 and a spine forming roller 360 are arranged on a downstream side in that order. The booklet processor is configured to add a feed amount of deformation for forming a spine SA2 at the booklet tip and a reverse-rotation amount of the transfer roller Rer, which becomes a center pushing-out amount, for canceling a surplus length generated inside a booklet. The saddle-stitched booklet is transferred up to a position, incremented with respect to a stop position being a target, and stopped there. Pressing force of the transfer roller Rer is reduced. After the transfer roller Rer is returned by reversely rotating it by the reverse-rotation amount becoming the center pushing-out amount, the pressing and clamping member 350 is pressed so as to press and clamp the saddle-stitched booklet and to allow the spine forming roller 360 to execute spine formation. COPYRIGHT: (C)2012,JPO&INPIT
