Patent ID: 7984898

Claim:
In an image-forming system, a bookbinding method for collating printed sheets into bundles and binding together the sheet edges along the bundle spine portion, the bookbinding method comprising: an image-forming step of sequentially forming, based on predetermined image data, images onto a series of sheets; a fold-process step of folding sheets on which images have been formed in said image-forming step; a stacking step of collating into bundles sheets on which images have been formed in said image-forming step and/or sheets folded in said fold-process step; a bookbinding step of binding together spine-portion edges of sheet bundles collated in said stacking step; and a trimming step of trimming true at least the fore-edge of the sheet bundles bound in said bookbinding step; wherein in said image-forming step, on at least a single sheet of the sequential series of sheets on which images are formed, a foldout-image area is preestablished along the sheet's fore-edge portion, and imaging is carried out on the foldout-image area; in said fold-process step, the foldout-image area is fold-processed along a folding-back fold location; and in said trim-finishing step, said fold location is cut to thereby isolate the foldout-image area, tucked into the sheet bundle.