Patent ID: 6837840

Claim:
A sheet processing apparatus for folding a sheet bundle at a predetermined position, comprising: pressing means for pressing a predetermined position of said sheet bundle to fold the sheet bundle; and paired rotating bodies for folding the sheet bundle supplied by the pressing means, said paired rotating bodies having nip portions contacting the sheet bundle, said nip portions having a high friction coefficient region and a low friction coefficient region less than the high friction coefficient region in friction coefficient, which are made of different materials, each of said paired rotating bodies being formed of one roller having a circular portion forming the nip portion and two non-circular portions, said circular portion having said high and low friction coefficient portions and being located between the two non-circular portions in one roller, said high friction coefficient portion being sandwiched between two low friction coefficient portions in one circular portion so that a pulling force of the rotating bodies to pull the sheet bundle pressed into the nip portions of the rotating bodies by the pressing means has an amount which does not separate a sheet of said sheet bundle contacting the rotating bodies from subsequent sheets in the sheet bundle when pulling the sheet bundle.