An image forming apparatus includes a developer container to and from which a replenishment container is attachable and detachable, the developer container including an accommodating portion, and a supporting portion, wherein the developer container includes a projection portion that is provided at one end portion thereof in the rotation axis direction of the developer bearing member and projects toward the supporting portion more than a center portion of the developer container in a crossing direction crossing the rotation axis direction, the projection portion communicates with the accommodating portion and includes, at a distal end portion thereof, an attachment portion configured such that the replenishment container is attachable thereto in a state of being exposed to the outside of the apparatus, and a replenishment port for replenishing the accommodating portion with developer from the replenishment container is defined in the attachment portion.

A powder container case includes a first member, a second member, a main joint, and an additional joint. The first member and the second member are joined to form an edge portion of a case opening. The main joint is disposed between the first member and the second member, and has an end portion at the edge portion of the case opening. The additional joint is disposed adjacent to the end portion of the main joint.

A photosensitive member unit includes a photosensitive member, a transfer roller, a mounting portion capable of mounting a development unit including a development roller, a first gear and a second gear each provided at one end of the photosensitive member in an axial direction of the photosensitive member, and a third gear provided at one end of the transfer roller in an axial direction of the photosensitive member and configured to engage with the second gear. The first gear, the second gear, and the third gear are helical gears. A direction in which helical teeth of the first gear are inclined is opposite to a direction in which helical teeth of the second gear are inclined, and the direction in which the helical teeth of the first gear are inclined matches a direction in which helical teeth of the third gear are inclined.

An image forming apparatus includes an image bearing member, a developing device including a developer container and a developer carrying member, a mounting portion, a moving mechanism, a cover member, a wall member, a first seal member, a second seal member, and a fan. The developing device is in a separated position, neither the first seal member or the second seal member contacts the wall member. When the developing device is in a developing position, both the first seal member and the second seal member contact the wall member. When the developing device is in the developing position, a space for permitting passing of an airflow by the fan is formed along a mounting direction by the cover member, the wall member, the first seal member, and the second seal member.

A cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, the cartridge includes (i) a rotatable developing roller for developing a latent image formed on a photosensitive member; (ii) a first drive transmission member capable of receiving a rotational force originated by the main assembly; (iii) a second drive transmission member capable of coupling with the first drive transmission member and capable of transmitting the rotational force received by the first drive transmission member to the developing roller; and (iv) a coupling disconnection member including a force receiving portion capable of receiving the force originated by the main assembly, and an urging portion capable of urging at least one of the first drive transmission member and the second drive transmission member by the force received by the force receiving portion to separate one of the first drive transmission member and the second drive transmission member from the other, thereby disconnecting the coupling.

An image forming apparatus includes: a first guide that is provided in an apparatus housing and configured to suspend and hold a first unit including an image holder so that the first unit is movable in an insertion and removal direction; a second guide that is provided in the apparatus housing and configured to suspend and hold a second unit including a developer holder so that the second unit is movable in an insertion and removal direction; and a pedestal that is disposed on a front side in the insertion and removal direction with respect to the first guide and the second guide, supports, from below in a gravity direction, the first unit and the second unit while the first unit and the second unit are inserted into the apparatus housing, and does not contact with the first unit and the second unit located in the apparatus housing.

An apparatus includes a developer container to and from which a replenishment container is attachable and detachable and which includes an accommodating portion and a replenishment port, a transfer portion configured to transfer a developer image on an image bearing member onto a recording material, a supporting tray including a supporting surface configured to support the recording material thereon, and a discharge portion configured to discharge the recording material, onto which the developer image has been transferred, on the supporting surface, wherein the supporting surface has an opening portion opening such that the replenishment port is exposed through the supporting surface, and wherein an opening/closing member configured to be movable between a closed position where the opening/closing member covers the replenishment port and serves as a part of the supporting surface and an open position where the replenishment port is exposed is provided.

An image forming apparatus includes a photoconductive body, a light source, a deflector to deflect a light beam from the light source, a scanning optical system to image the deflected light beam onto the photoconductive body, a developing unit to supply developer to the photoconductive body, an optical sensor to detect the deflected light beam, a moving mechanism to move the developing unit to a first position and to a second position, and a controller configured to start driving the deflector, when the developing unit is in the second position, the light source to emit the light beam, thereby obtaining a detection signal of the light beam from the optical sensor, and after obtaining the detection signal of the light beam from the optical sensor, control the moving mechanism to move the developing unit to the first position.

A first development chamber accommodates an agitator. A second development chamber accommodates a development roller and a supply roller. The second development chamber is located above the first development chamber. A toner cartridge contains toner to be supplied to the first development chamber. A transfer device is located above a photosensitive drum in a state where a drum unit is attached to a main housing. The transfer device transfers toner on the photosensitive drum to a sheet. An agitator includes a shaft and a blade. The shaft is rotatably supported by a development housing. The blade is rotatable together with the shaft. The blade has a first end fixed to the shaft and a second end located away from the first end. The agitator is configured such that, when rotated, the second end of the blade reaches a height of an opening in the development housing in a vertical direction.

An image forming apparatus includes a heating device including a heater, a developing device, and an airflow generation device. The heater includes a base, a heat generator, an electrode portion, and conductive portions. The conductive portions are disposed on one side and another side in a longitudinal direction in a heat generation region and spaced apart in a lateral direction intersecting the longitudinal direction. A maximum total value among total values of squares of current flowing in the conductive portions at longitudinal positions on the one side is larger than that on said another side. The developing device includes a rotating member and sliding portions. A sliding portion having highest temperature in operation is disposed on one side of the developing device being same as the one side of the heater in the longitudinal direction. The airflow generation device generates an airflow toward the one side of the developing device.