Image forming apparatus that supplies sheet on which image is formed to ring bookbinding apparatus

An image forming system comprising:

• an image forming unit configured to form an image onto a sheet;
• a bookbinding unit configured to bind a book by attaching a ring to a punch hole of a sheet bundle that consists of a plurality of sheets on which images are formed;
• a buffer unit configured to perform a buffering process to convey a predetermined number of sheets in piles so that sheets for a next sheet bundle are not ejected onto a sheet bundle that is being processed by said bookbinding unit;
• a determination unit configured to determine whether a sheet is a type that is prohibited from performing the buffering process by said buffer unit;
• and
• a control unit configured to adjust an ejection order so that the sheet of the type that is prohibited from performing the buffering process is not ejected within the predetermined number of sheets from the first sheet of sheets that constitute the sheet bundle, when said determination unit determines that the sheet is the type that is prohibited from performing the buffering process.

A control method for an image forming system comprising:

• an image forming step of forming an image onto a sheet;
• a bookbinding step of binding a book by attaching a ring to a punch hole of a sheet bundle that consists of a plurality of sheets on which images are formed;
• a buffering step of performing a buffering process to convey a predetermined number of sheets in piles so that sheets for a next sheet bundle are not ejected onto a sheet bundle that is being processed in said bookbinding step;
• a determination step of determining whether a sheet is a type that is prohibited from performing the buffering process in said buffering step;
• and
• a control step of adjusting an ejection order so that the sheet of the type that is prohibited from performing the buffering process is not ejected within the predetermined number of sheets from the first sheet of sheets that constitute the sheet bundle, when it is determines that the sheet is the that is prohibited from performing the buffering process in said determination step.