Sheet binding apparatus, sheet post processing apparatus having the sheet binding apparatus and image forming system having the sheet binding apparatus

A sheet binding apparatus configured to bind sheets, comprising:

• a first binding portion and a second binding portion each having a surface to be engaged with each other with sheets therebetween, each of the surfaces being provided with a plurality of tops and bottoms;
• a moving means configured to move the first binding portion toward the second binding portion fixed and to bring the first binding portion and the second binding portion into pressure contact with the sheets between the first binding portion and the second binding portion to bind the sheets with pressure and to move the first binding portion away from the second binding portion after binding the sheets with pressure;
• and
• a peeling member configured to apply peeling force in a direction opposite to a pressure direction for the pressure contact with the sheets to peel off a bound portion of the sheets from the plurality of tops and bottoms of the surfaces when the first binding portion is moved away from the second binding portion by the moving means after binding the sheets with processing,
• wherein the peeling member includes an inclined surface, which when the first binding portion is moved away from the second binding portion, abuts against the sheets contacting with the plurality of tops and bottoms of the surface of the first binding portion, and
• a distance between one end of the inclined surface in a longitudinal direction of the first binding portion and the second binding portion in a moving direction that the moving means moves the first binding portion toward the second binding portion is different from a distance between another end of the inclined surface in the longitudinal direction and the second binding portion in the moving direction.