US Patent 7590380 Bookbinding apparatus and bookbinding method

When printing is interrupted, the selection between the use of a sheet bundle stacked on an accumulating tray and no use thereof is appropriately made. A bookbinding system includes a bookbinding apparatus having the accumulating tray for stacking a plurality of printed sheets thereon as the sheet bundle. When an interrupting factor is generated for interrupting a printing job, the printing is interrupted. Upon restarting the printing after the interrupting factor is cancelled, the printing apparatus determines whether the sheet bundle stacked on the accumulating tray is used for forming a bound book or not.