Sheet conveyance apparatus having mechanism for flexibly controlling interval between sheets and image forming apparatus

An image forming apparatus, comprising:

• a sheet conveyance apparatus including:
• a sheet conveyance path;
• a first conveyance mechanism located upstream in the sheet conveyance path;
• a first drive mechanism configured to drive the first conveyance mechanism to convey a sheet forward and backward;
• a second conveyance mechanism located downstream in the sheet conveyance path;
• a second drive mechanism configured to drive the second conveyance mechanism;
• a first intermediate conveyance mechanism located between the first and second conveyance mechanisms in the sheet conveyance path;
• a first drive transmission mechanism configured to intermittently transmit drive force from the first drive mechanism to the first intermediate conveyance mechanism in a backward direction, when the first conveyance mechanism is being driven backward by the first drive mechanism;
• and
• a second drive transmission mechanism configured to intermittently transmit drive force from the second drive mechanism to the first intermediate conveyance mechanism so that the first intermediate conveyance mechanism drives the sheet backward while the first drive mechanism drives the first conveyance mechanism forward.