At an end, in a longitudinal direction, of an opening in a container containing a magnetic developer, an overlap portion is provided in which a developer bearing member, a regulating member, a sealing member, and the container are arranged so as to sequentially contact one another in a direction orthogonal to a rotation axis direction. A magnetic field generating member provided inside the developer bearing member has a first area where a value of a magnetic flux density is a predetermined value in the rotation axis direction and a second area including a local minimum portion in which the value is a minimum value, within a range from an end of the second area connected to the first area to an outer end of the overlap portion in the rotation axis direction.

An injection inlet for injecting elastomer into a gap between frames and a seal member, a storage portion in which the elastomer flowing out of the injection inlet is stored, and a protruding portion that protrudes toward a conveyance path of a recording medium to which a developer image is transferred, are provided in the frames, and the protruding portion protrudes toward the conveyance path further than the storage portion exposed to the conveyance path.

A process cartridge includes a photosensitive member and a developing unit. The developing unit includes a frame to store toner, a developing roller to carry the toner, a side seal to contact an end portion of the developing roller and prevent the toner from leaking out, and a sealing sheet to contact a center portion of the developing roller and prevent the toner from leaking out. A toner receiving portion of the frame includes an opening facing the developing roller and is disposed on an upstream side of the side seal and a downstream side of a contact portion where the developing roller contacts the photosensitive member, and moreover is disposed at a position overlapping with the side seal. The developing unit includes a blocking member to block at least a part of the opening, and the blocking member is disposed between the opening and the developing roller.

A toner sealing system is described including a seal having first and second alignment features. The seal is selectably installable on one of a first toner container of a first type and a second toner container of a second type. The first alignment feature is matable with a first corresponding alignment feature on the first toner container when the seal is installed on the first toner container for aligning the seal to the first toner container. The second alignment feature is matable with a second corresponding alignment feature on the second toner container when the seal is installed on the second toner container for aligning the seal to the second toner container. Embodiments include those wherein the first alignment feature does not align the seal to the second toner container, and the second alignment feature does not align the seal to the first toner container.

A developing device includes a developing container, a developer carrier, a seal member, and a pair of pressing members. The developing container has an opening. The seal member includes a contact end part that makes contact with an entire region of an outer circumferential surface of the developer carrier in its rotary shaft direction and is one of end edges of the seal member in a longitudinal direction thereof on a side near the developer carrier and an interposed end part that is interposed between each of both end parts of the developer carder and a corresponding one of the pressing members and is an end edge of the seal member orthogonal to the contact end part, and a chamfered shape is formed at a corner between the contact end part and the interposed end part.

A regulation member includes an opposed surface and a contact surface in a portion corresponding to an image forming area. The opposed surface is opposed to a developer bearing member. The contact surface protrudes from the opposed surface and has a height different from that of the opposed surface. An end seal seals a gap between a frame body, the developer bearing member, and the regulation member. The regulation member further includes an area not having the contact surface between the image forming area and a sealing area in which the regulation member and the end seal overlap. In the sealing area, a step between the opposed surface and the contact surface has a height of greater than or equal to 0 mm and not greater than 0.10 mm.

A powder container includes a discharge port, and a container identifier shape portion provided on a front end surface of the powder container in an insertion direction and that functions to identify a type of the powder container, the insertion direction being a direction in which the container body is inserted. The powder container further includes a driven portion that interlocks with a first main-body interlocking portion of the image forming apparatus at the time of setting in the main body of the image forming apparatus, and an identifier opening group that starts to interlock with a second main-body interlocking portion of the image forming apparatus after the driven portion starts to interlock with the first main-body interlocking portion. A position of the identifier opening group relative to the driven portion in the circumferential direction varies depending on a type of the powder container to be identified.

An inner resistive film is applied to a conductive substrate. Ductile particles are disposed substantially uniformly throughout the inner resistive film. An outer resistive film is applied to the inner resistive film.

A seal member 14 which seals a gap among a rotating body 9 provided in an opening of a frame body 13, a blade 18a, and the frame body 13 in an end region in an axial direction of the rotating body 9, the seal member 14 including: a first seal portion 14b which comes into contact with the rotating body 9; a second seal portion 14e which comes into contact with the blade 18a; and a third seal portion 14f which is constituted by a surface formed in a stair shape and sequentially arranged between the first seal portion 14b and the second seal portion 14e and which is capable of reducing a gap formed between the rotating body 9 and the blade 18a due to rotation of the rotating body 9.

A process cartridge includes a photosensitive member and a developing unit. The developing unit includes a frame to store toner, a developing roller to carry the toner, a side seal to contact an end portion of the developing roller and prevent the toner from leaking out, and a sealing sheet to contact a center portion of the developing roller and prevent the toner from leaking out. A toner receiving portion of the frame includes an opening facing the developing roller and is disposed on an upstream side of the side seal and a downstream side of a contact portion where the developing roller contacts the photosensitive member, and moreover is disposed at a position overlapping with the side seal. The developing unit includes a blocking member to block at least a part of the opening, and the blocking member is disposed between the opening and the developing roller.