Oldham coupling and image forming apparatus

An Oldham coupling comprising:

• a first hub;
• a second hub;
• an intermediate member configured to transmit a driving force at positioned between the first hub and the second hub;
• a recessed portion provided in one of an end surface of the first hub in a rotational axis direction of the Oldham coupling and an end surface of the intermediate member in a rotational axis direction of the Oldham coupling, being recessed in the rotational axis direction, and extending in a first direction orthogonal to the rotational axis direction, and the first recessed portion includes a first inner wall on one side in a second direction orthogonal to the rotational axis direction and to the first direction, and a second inner wall provided on the other side in the second direction and extending parallel to the first inner wall,
• a protruded portion provided in the other of the end surface of the first hub in a rotational axis direction of the Oldham coupling and the end surface of the intermediate member in a rotational axis direction of the Oldham coupling, the protruded portion protruding in the rotational axis direction, being fitted to the first recessed portion, and configured to transmit a driving force between the intermediate member and the first hub, and the protruded portion includes
• a first edge portion configured to contact with the first inner wall in a state the Oldham coupling rotates in a first rotational direction,
• a second edge portion configured to contact with the second inner wall in a state the Oldham coupling rotates in the first rotational direction,
• a third edge portion configured to contact with the first inner wall in a state the Oldham coupling rotates in a second rotational direction opposite to the first rotational direction, and
• a fourth edge portion configured to contact with the second inner wall in a state the Oldham coupling rotates in the second rotational direction,
• wherein in a state the first edge portion is in contact with the first inner wall and the second edge portion is in contact with the second inner wall, the third edge portion is separated from the first inner wall and the fourth edge portion is separated from the second inner wall,
• wherein in a state the third edge portion is in contact with the first inner wall and the fourth edge portion is in contact with the second inner wall, the first edge portion is separated from the first inner wall and the second edge portion is separated from the second inner wall,
• wherein in a state the Oldham coupling rotates with rotation of a motor in the second rotational direction, a portion of the first edge portion that is farthest from a first rotation center that is a rotation center of the first hub in the first direction is to be located closer to the second inner wall than the first rotation center in the second direction, and a portion of the second edge portion that is farthest from the first rotation center in the first direction is to be located closer to the first inner wall than the first rotation center in the second direction, and
• wherein in a state the Oldham coupling rotates with rotation of the motor in the first rotational direction, a portion of the third edge portion that is farthest from the first rotation center in the first direction is to be located closer to the second inner wall than the first rotation center in the second direction, and a portion of the fourth edge portion that is farthest from the first rotation center in the first direction is to be located closer to the first inner wall than the first rotation center in the second direction.