Image forming apparatus and power transmission mechanism

An image forming apparatus comprising a sheet transport device that transports a sheet through a nip, which is formed between a pressing member and a drive member, by applying a rotational force to the drive member via a power transmission mechanism,

• the power transmission mechanism including:
• a first rotational shaft connected to the drive member;
• a second rotational shaft connected to a drive source;
• a first rotation transmitting member attached to one of the first rotational shaft and the second rotational shaft;
• a second rotation transmitting member attached to the other of the first rotational shaft and the second rotational shaft;
• a holding member including a first contact part and a second contact part that are disposed on opposite sides of the second rotation transmitting member along an axial direction of the second rotation transmitting member, sandwiching the second rotation transmitting member loosely from both of the sides;
• and
• a rotational move member configured to switch to a power non-transmission state by moving the holding member rotationally to a first position in coniunction with an opening operation of an opening/closing member of an apparatus housing, and switch to a power transmission state by moving the holding member rotationally to a second position in coniunction with a closing operation of the opening/closing member,
• the power non-transmission state being a state in which power is not transmitted between the first rotational shaft and the second rotational shaft, and the power transmission state being a state in which power is transmitted between the first rotational shaft and the second rotational shaft,
• the rotational move member moving the holding member rotationally to the first position by causing the first contact part to contact and move the second rotation transmitting member toward a first direction, and moving the holding member rotationally to the second position by causing the second contact part to contact and move the second rotation transmitting member toward a second direction;
• when view from a direction of the supporting axis of the holding member,
• positions of the first contact part and the second contact part and a position of the supporting axis of the holding member are determined such that distances between tracks, which are drawn by contact points between the second rotation transmitting member and the first contact part and the second contact part from the start to the end of switching between the power transmission state and the power non-transmission state, and the center axis of the rotational shaft to which the second rotation transmitting member is attached are within a predetermined range.

A power transmission mechanism comprising:

• a first rotational shaft connected to the drive member;
• a second rotational shaft connected to a drive source;
• a first rotation transmitting member attached to one of the first rotational shaft and the second rotational shaft;
• a second rotation transmitting member attached to the other of the first rotational shaft and the second rotational shaft;
• a holding member including a first contact part and a second contact part that are disposed on opposite sides of the second rotation transmitting member along an axial direction of the second rotation transmitting member, sandwiching the second rotation transmitting member loosely from both of the sides;
• and
• a rotational move member configured to switch between a power transmission state in which power is transmitted between the first rotational shaft and the second rotational shaft, and a power non-transmission state in which power is not transmitted between the first rotational shaft and the second rotational shaft, by moving the holding member rotationally and causing one of the first contact part and the second contact part to contact and move the second rotation transmitting member to a first position or to a second position,
• an outer circumferential face of each of the first contact part and the second contact part is, at least in a range to contact the second rotation transmitting member between a start and an end of switching between the power transmission state and the power non-transmission state while the holding member moves rotationally, in a shape of a side face of a cylinder whose center axis is parallel to the supporting axis of the holding member.

A power transmission mechanism comprising:

• a first rotational shaft connected to the drive member;
• a second rotational shaft connected to a drive source;
• a first rotation transmitting member attached to one of the first rotational shaft and the second rotational shaft;
• a second rotation transmitting member attached to the other of the first rotational shaft and the second rotational shaft;
• a holding member including a first contact part and a second contact part that are disposed on opposite sides of the second rotation transmitting member along an axial direction of the second rotation transmitting member, sandwiching the second rotation transmitting member loosely from both of the sides:
• a rotational move member configured to switch between a power transmission state in which power is transmitted between the first rotational shaft and the second rotational shaft, and a power non-transmission state in which power is not transmitted between the first rotational shaft and the second rotational shaft, by moving the holding member rotationally and causing one of the first contact part and the second contact part to contact and move the second rotation transmitting member to a first position or to a second position;
• wherein when viewed from a direction of the supporting axis of the holding member, positions of the first contact part and the second contact part and a position of the supporting axis of the holding member are determined such that distances between tracks, which are drawn by contact points between the second rotation transmitting member and the first contact part and the second contact part from the start to the end of switching between the power transmission state and the power non-transmission state, and the center axis of the rotational shaft to which the second rotation transmitting member is attached are within a predetermined range.