Planetary gear unit and image forming apparatus including same

An image forming apparatus comprising:

• an image carrier;
• a drive unit to rotatively drive the image carrier;
• a planetary gear unit coupled to both the image carrier and the drive unit to transmit torque from the drive unit reduced by the planetary gear unit to the image carrier, the planetary gear unit comprising:
• a sun gear rotatable by the torque;
• an outer gear disposed coaxially with the sun gear;
• multiple planetary gears disposed within the outer gear at equal intervals along an inner circumference of the outer gear to engage both the sun gear and the outer gear, respectively;
• a carrier pin to rotatably support each of the multiple planetary gears, at least a first end of the carrier pin being constructed of a circular portion and a linear portion in cross-section to form a first supported part;
• and
• a carrier rotatable coaxially with both the sun gear and the outer gear to support both ends of the carrier pin, the carrier having a first support part that engages or is fitted with the first supported part to support the first supported part, the first support part being formed to position the circular portion of the first supported part downstream from the linear portion in a direction of rotation of the carrier;
• and
• an image forming unit to form an image on the image carrier.