Sheet binding device, sheet processing apparatus, image forming apparatus, image forming system, and sheet binding method

A crimp-binding type of sheet binding device comprising:

• a pair of toothing crimping members;
• and
• a movable-crimping-member moving unit that moves a movable crimping member which is one of the pair of crimping members and is movably installed, wherein
• the sheet binding device binds a sheet bundle by causing the movable-crimping-member moving unit to move the movable crimping member thereby holding the sheet bundle between the pair of crimping members, and
• the movable-crimping-member moving unit includes:
• a link mechanism that includes a first link member having one end rotatably connected to the movable crimping member, a second link member having one end rotatably connected to a fixed member fixed to a device body, and a connecting part that rotatably connects the other end of the first link member and the other end of the second link member;
• a connecting member having one end rotatably connected to the connecting part of the link mechanism, and capable of moving between a first position causing the link mechanism to be extended and a second position retracted from the first position and causing the link mechanism to be more flexed than in the first position;
• and
• a connecting-member moving unit that includes a rotary member capable of rotating on a displaceable rotating shaft, and reciprocates the connecting member between the first position and the second position by rotation of the rotary member in one direction.