FIELD: physics.
SUBSTANCE: present invention discloses a developing device, a developing cartridge and an electrophotographic image forming apparatus used with said developing device or said developing cartridge. The disclosed developing device used with the electrophotographic image forming apparatus includes a driving shaft rotated by an electric motor and having a rotating force applying portion, and a movable member. The developing device is mountable on the movable member and is movable in a direction substantially perpendicular to an axial direction of the driving shaft in response to movement of the movable member in one direction with said developing device mounted on the movable member. The driving shaft is not movable in a direction substantially perpendicular to the axial direction thereof, and the developing device comprises: i) a developing roller which can rotate about an axis, the roller being able to come into contact with and separate from the drum in response to movement of the movable member; and ii) a coupling member for transmitting a rotating force to the roller. The coupling member includes a rotating force receiving portion which can be engaged with the rotating force applying portion to receive a rotating force from the driving shaft, and a rotating force transmitting portion for transmitting the rotating force received through the rotating force receiving portion to the roller. The coupling member is capable of taking a rotational force transmitting angular position for transmitting the rotational force for rotating the roller to said roller, a pre-engagement angular position which is taken before said coupling member is engaged with the rotating force applying portion and in which said coupling member is inclined away from the rotational force transmitting angular position, and a disengaging angular position which is taken by said coupling member to disengage from the driving shaft and in which said coupling member is inclined away from the rotational force transmitting angular position in a direction opposite to said pre-engagement angular position. In response to movement of the developing device when the movable member moves in said one direction, said coupling member moves from the pre-engagement angular position to the rotational force transmitting angular position, and when the movable member makes a further movement in said one direction, in response to the further movement, the coupling member is moved from the rotational force transmitting angular position to said disengaging angular position to disengage the coupling member from the driving shaft, and wherein the roller is contacted with the drum in response to the movement of the developing device in a state where the roller is being rotated through engagement between the coupling member and the rotating force applying portion.
EFFECT: high accuracy, preventing non-uniform rotation of the developing roller.
46 cl, 31 dwg
