Drive transmitter and image forming apparatus incorporating the drive transmitter

An image forming apparatus comprising:

• a plurality of image forming units, each integrally including at least one of an image bearer, a developing roller, a charger, and a cleaning device;
• an intermediate transfer body;
• a drive source including an output gear and configured to apply a driving force;
• a drive rotary body including
• a cylindrical body with one end open and an opposite end closed,
• an internal tooth part mounted on an inner circumferential surface of the drive rotary body and directly meshed with the output gear of the drive source, and
• an external tooth part mounted on an outer circumferential surface of the drive rotary body;
• a drive transmitting member including an external tooth part and a pulley, the external tooth part of the drive transmitting member being meshed with the external tooth part of the drive rotary body;
• a first belt;
• a first drive output member including a first pulley to stretch the first belt between the first pulley and the pulley of the drive transmitting member, the first drive output member being configured to be drivingly connected to a first developing roller;
• a second drive output member including an external tooth part meshed with the external tooth part of the drive rotary body, and a second pulley, the second drive output member being configured to be drivingly connected to a second developing roller;
• a second belt;
• and
• a third drive output member including a third pulley to stretch the second belt between the third pulley and the second pulley of the second drive output member, the third drive output member being configured to be drivingly connected to a third developing roller,
• the first belt and the second belt being disposed near the drive rotary body.