A developer container includes a body, an agitating bar, and an agitating film. The body includes a bottom plate; a first side wall; a second side wall facing the first side wall; a developer chamber defined by the bottom plate, the first side wall, and the second side wall, the developer chamber storing developer; and an opening formed in the bottom plate to allow the developer chamber to communicate with an outside of the developer chamber and allow the developer to be supplied from the developer chamber to the outside of the developer chamber. The agitating bar is configured to rotate to agitate the developer stored in the developer chamber. The agitating film is attached to the agitating bar and configured to, when rotation of the agitating bar stops, stop in a state where the agitating film abuts the first side wall and the second side wall.

A developing device includes a rotatable sleeve for carrying a developer including a magnetic material to develop a latent image on an image bearing member; a developer chamber; and a rotatable stirring member provided inside the chamber to stir the developer while being in contact with at least a part of an inner surface of the chamber; a magnet generating a magnetic field in at lease a part of a contact region between the stirring member and the inner surface, wherein a magnetic flux density of the magnetic field at a first position in the contact region generated by the magnet is different from that in a second position which is adjacent to the first position in a rotational axis direction of the sleeve.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.

A powder container includes a powder storage configured to store powder and having side walls with through-holes; a hollow member including a hollow part; held parts disposed at both ends of the hollow member in an axial direction of the hollow member; a coil configured to be held by the hollow member; holders configured to hold the held parts of the hollow member; and a piercing shaft configured to be inserted into the hollow part of the hollow member from outside of the powder container through one of the through-holes.

A powder container includes a rotator and a coil disposed adjacent to the rotator. The rotator is configured to rotate in a predetermined direction. The coil is configured to be rotated by contact with the rotator and divided into a plurality of divided coil portions along a rotation center of the coil in an axial direction of the coil. A plurality of coil centers of the plurality of divided coil portions is eccentric relative to the rotation center.

A developing apparatus includes: a housing that accommodates developer and has a plurality of constituent parts; a vibrator that vibrates parts, which are two or more of the plurality of the constituent parts and to which scattered toner may adhere, as vibrated portions; an adjuster provided for at least one of the vibrated portions and the vibrator so as to adjust and match natural frequencies of the two or more of the vibrated portions; and a hardware processor that controls the vibrator.

A developing apparatus includes: a housing that accommodates developer and has a plurality of constituent parts; a vibrator that vibrates parts, which are two or more of the plurality of the constituent parts and to which scattered toner may adhere, as vibrated portions; an adjuster provided for at least one of the vibrated portions and the vibrator so as to adjust and match natural frequencies of the two or more of the vibrated portions; and a hardware processor that controls the vibrator.

A stirring/conveying member has a rotary shaft rotatably supported in a powder container, a first helical blade formed on the circumferential surface of the rotary shaft and conveying powder in the axial direction by the rotation of the rotary shaft, and a second helical blade formed on the circumferential surface of the rotary shaft to overlap the forming region of the first helical blade, spiraling in the opposite phase to the first helical blade, and having a smaller radial height than the first helical blade. The first helical blade crosses the second helical blade at least at one place in one turn about the rotary shaft. At least one of the radial heights of the first and second helical blades equals zero at the intersection of the first and second helical blades.

An image forming apparatus includes a rear-side frame member that is disposed on the rear side of an image forming apparatus body so as to extend in a vertical or substantially vertical direction; and a drive unit that includes a drive part. The drive unit is detachably disposed on an inner surface of the rear-side frame member such that the drive part faces outward from the image forming apparatus body.

A developing apparatus includes a partition member disposed in a first chamber above a discharge space communicated to the discharge port positioned downstream of a return conveyance portion in the first direction, and configured to divide a space within a first chamber in a gravity direction. The partition member is configured to extend from a wall portion on a downstream side of a developer container to a position corresponding to a downstream end of a return conveyance portion or to a position further upstream beyond the position corresponding to the downstream end of the return conveyance portion in the first direction. A surface, opposed to a first conveyance screw, of the partition member is positioned downward in the gravity direction than an upper end of a first communication port and upward in the gravity direction than the first conveyance screw.