Drive transmission device and image forming apparatus

A drive transmission device comprising:

• a driving-side coupling;
• a driven-side coupling;
• and
• an intermediary transmission member provided between said driving-side coupling and said driven-side coupling and configured to transmit a rotational driving force from said driving-side coupling to said driven-side coupling,
• wherein said driving-side coupling and said intermediary transmission member engage with each other so as to be movable relative to each other in a first direction perpendicular to a rotation shaft of said driving-side coupling,
• wherein said driven-side coupling and said intermediary transmission member engage with each other so as to be movable relative to each other in a second direction crossing the first direction and perpendicular to a rotation shaft of said driven-side coupling, and
• wherein said intermediary transmission member includes (i) two engaging portions engaging with one of said driving-side coupling and said driven-side coupling and (ii) holding portions engaging with holes provided in the other one of said driving-side coupling and said driven-side coupling, the two engaging portions being arranged on a straight line across a rotational center of the intermediate transmission member and transmitting a rotational driving force only in one direction, each holding portion extending in the first direction to prevent said intermediary transmission member from disengaging from the other one of said driving-side coupling and said driven-side coupling.

An image forming apparatus for forming an image on a sheet, comprising:

• a unit including a driven-side coupling and detachably mountable to said image forming apparatus;
• a driving-side coupling;
• and
• an intermediary transmission member provided between said driving-side coupling and said driven-side coupling and configured to transmit a rotational driving force from said driving-side coupling to said driven-side coupling, said intermediary transmission member including;
• (i) two projected portions projecting in an axial direction of said intermediary transmission member, the projecting portions opposing each other with respect to an axis which is a rotation center of said intermediary transmission member and each of the two projected portions including a contact portion;
• and
• (ii) a plurality of holding portions,
• wherein said driving-side coupling and said intermediary transmission member engage with each other so as to be movable relative to each other in a first direction perpendicular to an axis which is a rotation center of said driving-side coupling,
• wherein said driven-side coupling and said intermediary transmission member engage with each other so as to be movable relative to each other in a second direction crossing the first direction and perpendicular to an axis which is a rotation center of said driven-side coupling,
• wherein one of said driving-side coupling and said driven-side coupling is a holding-side coupling that holds said intermediary transmission member, the other one of said driving-side coupling and said driven-side coupling is a non-holding side coupling, the holding-side coupling includes a plurality of holes, each holding portion of the plurality of holding portions engages with a hole of the plurality of holes so as to prevent said intermediary transmission member from disengaging from the holding-side coupling,
• wherein, when said driving-side coupling rotates in one direction, each contact portion of the two projected portions contacts a portion of said non-holding-side coupling that opposes the contact portion with respect to a rotational direction, and
• wherein, when said intermediary transmission member engages with said non-holding-side coupling in a manner that forms a deviation angle between said rotation center of said driving-side coupling and said rotation center of said driven-side coupling, each of the two projected portions moves away from said non-holding-side coupling after engaging with said non-holding-side coupling.

An image forming apparatus for forming an image on a sheet, comprising:

• a unit including a driven-side coupling and detachably mountable to said image forming apparatus;
• a driving-side coupling;
• and
• an intermediary transmission member provided between said driving-side coupling and said driven-side coupling and configured to transmit a rotational driving force from said driving-side coupling to said driven-side coupling,
• wherein said driving-side coupling and said intermediary transmission member engage with each other so as to be movable relative to each other in a first direction perpendicular to a rotation shaft of said driving-side coupling,
• wherein said driven-side coupling and said intermediary transmission member engage with each other so as to be movable relative to each other in a second direction crossing the first direction and perpendicular to a rotation shaft of said driven-side coupling, and
• wherein said intermediary transmission member includes (i) two engaging portions engaging with one of said driving-side coupling and said driven-side coupling and (ii) holding portions engaging with holes provided in the other one of said driving-side coupling and said driven-side coupling, the two engaging portions being arranged on a straight line across a rotational center of the intermediate transmission member and transmitting a rotational driving force only in one direction, each holding portion extending in the first direction to prevent said intermediary transmission member from disengaging from the other one of said driving-side coupling and said driven-side coupling.