An image forming system includes a toner container and an image forming apparatus to which the toner container is mountable. The toner container includes a projection that includes an inner peripheral surface centered on a central axis of the toner container. When the toner container is oriented in a predetermined direction, the projection has a downward guide surface facing downward and an upward guide surface facing upward. When the toner container is moved downward in a direction of the central axis toward a mounting portion of the image forming apparatus, (i) the downward guide surface is configured to guide a guided member of the image forming apparatus so that the guided member is rotated in a rotational direction about the central axis, and (ii) the upward guide surface is configured to guide the guided member so that the guided member is moved up after the guided member is rotated in the rotational direction by the downward guide surface.

An image forming apparatus includes: a body comprising a developing device, and a mounting unit from which a toner refill cartridge is detachable and which is connected to the developing device and delivers toner accommodated in the toner refill cartridge to the developing device. The body includes a housing having a communication hole so that the toner refill cartridge is mounted on the mounting unit from outside the image forming apparatus. The image forming apparatus includes a drive unit to provide a driving force to the toner refill cartridge so that toner is supplied from the toner refill cartridge to the developing device: a detecting unit to acquire a detected value corresponding to an amount of toner in the toner refill cartridge; and a controller to control an operation of the drive unit based on the detected value.

An image forming system includes a toner container and an image forming apparatus to which the toner container is mountable. The toner container includes a projection that includes an inner peripheral surface centered on a central axis of the toner container. When the toner container is oriented in a predetermined direction, the projection has a downward guide surface facing downward and an upward guide surface facing upward. When the toner container is moved downward in a direction of the central axis toward a mounting portion of the image forming apparatus, (i) the downward guide surface is configured to guide a guided member of the image forming apparatus so that the guided member is rotated in a rotational direction about the central axis, and (ii) the upward guide surface is configured to guide the guided member so that the guided member is moved up after the guided member is rotated in the rotational direction by the downward guide surface.

An image forming apparatus, to which a supply container storing a developer is detachably attachable, includes a photosensitive member that rotates, an optical box and a circuit board to supply power, a developer bearing member supplying the developer, and a developer container stores the developer borne by the developer bearing member, including a supply unit for receiving the developer to be supplied from the supply container. The optical box irradiates the photosensitive member with light and forms an electrostatic latent image on the photosensitive member with the developer. The supply unit includes a lever portion to rotate a shutter portion to close and open the opening, when viewed in a vertical direction, the lever portion is position overlapping the circuit board when the shutter portion closes the opening and the lever does not interfere with the circuit board when the lever portion rotates the shutter portion to open the opening.

An attachment for an image forming apparatus includes a projection having an inner peripheral surface centered on a central axis and projecting in a direction of the central axis outside the inner peripheral surface in a radial direction of an imaginary circle centered on the central axis.

An image forming apparatus, to which a supply container storing a developer is detachably attachable and which forms an image on a recording material, includes a photosensitive member that rotates, an optical box, a developer bearing member, and a developer container including a supply port for receiving the developer to be supplied from the supply container. The optical box irradiates the photosensitive member with light and forms an electrostatic latent image on the photosensitive member. The developer bearing member bears the developer and develops the electrostatic latent image by supplying the developer to the photosensitive member. The developer container stores the developer to be borne by the developer bearing member. When viewed in a rotation axial direction of the photosensitive member, a region where the optical box is located and at least a part of a region where the supply port is located overlap each other in a horizontal direction.

A developing device includes an accommodating portion for accommodating toner, a developing roller and a stirring member. The developing device is for use with an image forming apparatus and detachably mounts a replenishing container for replenishing the toner. The accommodating portion includes a receiving opening through which the toner replenished from the accommodating portion is received in the accommodating portion, the receiving opening being provide on a first end side of the accommodating portion with respect to a rotational axis direction of the developing roller. An opening area of the receiving opening when the developing device is viewed in the rotational direction is wider than the opening area of the receiving opening when viewed in a direction perpendicular to the rotational axis direction.

A development unit includes a development housing configured to store toner and a development roller rotatable about a development axis extending in a first direction. The development roller supplies the toner in the development housing to a photosensitive drum. The development housing includes a reception port and a slope. The reception port receives toner from a toner container configured to store the toner to be supplied to the development housing. The reception port is located away from the development roller in a second direction crossing the first direction. The slope is located below the reception port in the development housing. The slope includes a first slope portion and a second slope portion. The first slope portion is inclined downward away from the reception port in the first direction. The second slope portion is inclined downward toward the development roller in the second direction.

A first cover is pivotable between a first cover closed position and a first cover open position about a first pivot axis located at a pivotal end. A process cartridge includes a reception port configured to receive toner from a toner container. A cover main body includes a first portion and a second portion. The first portion extends in a vertical direction in a state where the first cover is located at the first cover closed position. The second portion is connected to an upper end of first portion and extends in a second direction in a state where the first cover is located at the first cover closed position. At least part of the first cover faces the reception port in a state where the process cartridge is attached to a main housing and the first cover is located at the first cover closed position.

A toner cartridge includes: a body to contain toner and including a toner outlet to discharge the toner to the outside; an agitating member to rotate about a central axis of the body and agitate the toner contained in the body; a shutter member to move along the central axis with respect to the body, and having an open position to open the toner outlet and a blocked position to block the toner outlet; a driving force receiver exposed to the outside through the toner outlet when the shutter member is in the blocked position, and to rotate by receiving a driving force from the outside; and a driving shaft to transmit a rotational force of the driving force receiver to the agitating member.