Driving mechanism and image forming apparatus comprising the same

A driving mechanism, comprising:

• a looped metallic transmission belt that is disposed in a state of having a predetermined tensile force;
• a rotational driving unit that can output a rotational driving force;
• a bearing portion;
• a first shaft member that is rotatably supported by the bearing portion about a first rotational axis;
• a second shaft member, of which one end is rotatably supported so as to be rotatable about a second rotational axis;
• and
• a pulley that is in contact with an inner surface of the transmission belt, is connected to the second shaft member, and is rotatable about the second rotational axis;
• wherein
• the first shaft member comprises:
• a rotatably supported portion that is disposed at one end, is directly or indirectly connected to the rotational driving unit, and is rotatably supported by the bearing portion so as to be rotatable about the first rotational axis that is parallel with the second rotational axis;
• and
• an extended portion that is disposed at another end so as to be continuous with the rotatably supported portion, and includes a contact portion that is in contact with an inner surface of the transmission belt, in which a portion between the contact portion and the rotatably supported portion is flexurally deformed due to a tensile force applied to the contact portion by the transmission belt, the extended portion being rotatable about a diagonal rotational axis that is inclined at a predetermined angle relative to the first rotational axis, and wherein
• the pulley comprises an inclined outer surface that is inclined at a predetermined angle relative to the second rotational axis, such that a portion that is most separated from the first shaft member in a portion in contact with the transmission belt is substantially parallel with the extended portion.