In an image forming apparatus, a shortest distance at which a developer container is closest to an image bearing member and which is disposed downstream of a first magnetic pole and upstream of second magnetic pole of a magnet fixed within a developer bearing member is 2.5 mm or less, and a position at which a magnetic flux density in a normal direction of the developer bearing member is zeroed and which is disposed downstream of the first magnetic pole and upstream of the second magnetic pole in the rotation direction of the developer bearing member on the developer bearing member is positioned upstream of the position at which the developer container is closest to the image bearing member and which is disposed downstream of the first magnetic pole and upstream of the second magnetic pole.

A developing device includes a latent image carrier to form an electrostatic latent image is formed on a surface of the latent image carrier, a developing agent carrier to carry a developing agent including toner on a surface of the developing agent carrier, the developing agent carrier facing the latent image carrier, and a roll-shaped member facing the developing agent carrier to form a first gap and facing the latent image carrier to form a second gap, to form a suction air flow through the first gap and the second gap, to suction toner particles scattered to the first gap between the roll-shaped member and the developing agent carrier and the second gap between the roll-shaped member and the latent image carrier.

A developing device includes a developing roller to rotate in a predetermined direction of rotation and opposed to or in contact with an image bearer to form a development range, a cover to cover the developing roller downstream from the development range in the predetermined direction of rotation, a sheet member cantilevered by the cover to contact the developing roller with a flat face of the sheet member while trailing along the predetermined direction of rotation at a position downstream from the development range. The cover includes a large gap portion to form a first gap in a first predetermined range in the predetermined direction of rotation and a small gap portion disposed adjacent to and downstream from the large gap portion in the predetermined direction of rotation to form a second gap smaller than the first gap in a second predetermined range in the predetermined direction of rotation.

A developing device includes a housing, a developer holding device, and a directing device. The housing includes a container portion containing developer and has a developing opening. The developing device has a through portion disposed at a portion of the housing including a downstream edge portion at a downstream portion of the developing opening in a direction in which the developer holding device is rotated. The through portion has an inlet, an outlet, and a passage that connects the inlet and the outlet to each other so as to allow part of an airflow generated by rotation of the developer holding device to be introduced thereinto and flow therethrough. The directing device extends from a portion of the housing opposite to the developing opening with the inlet of the through portion interposed therebetween toward the developer holding device so as to direct the part of the airflow toward the inlet.

A molding device for molding a magnet roll with a profiled cross-section comprises a heating and kneading unit that supplies, to a cylindrical metal mold, a kneaded material obtained by heating and kneading a raw mixture including ferromagnetic particles and thermoplastic resin, an extrusion molding unit that molds the supplied kneaded material by the metal mold, and a magnetic field generating unit disposed at an end portion of the metal mold in a lengthwise direction that generates a magnetic field inside the metal mold, and the metal mold has a profiled C-shaped cross-section at an inlet for the kneaded material and a profiled cross-section at an outlet for the kneaded material more complex than the inlet.

A developing device includes a housing including a development opening and a containing unit that contains a developer, a developer carrier that rotates to pass through the development opening while holding the developer in the containing unit of the housing, an inlet portion of a flow path located in the housing at a portion including a downstream edge portion of the development opening on a downstream side in a rotation direction of the developer carrier, the inlet portion taking in part of an airflow caused by a rotation of the developer carrier to allow the part of the airflow to flow over an outer surface of the housing, and a guide member extending toward the developer carrier from a portion of the housing on a side of the inlet portion opposite to the development opening to guide the part of the airflow to the inlet portion.

An image forming apparatus includes an image bearing member configured to rotate, and a developing apparatus. The developing apparatus includes a developer container including a partition wall parting a storage space for storing developer into a first storage space and a second storage space and an opening, and a developer bearing member disposed such that a part of the developer bearing member is exposed out of the opening of the developer container. The developer can be collected in the second storage space from the developer bearing member without passing through the first storage space. A distance between the developer container and the image bearing member at a closest position where the developer container is closest to the image bearing member in an area downstream of the opening of the developer container in a rotation direction of the developer bearing member is 2.5 mm or less.

A developing device includes a housing, a developer holding device, and a directing device. The housing includes a container portion containing developer and has a developing opening. The developing device has a through portion disposed at a portion of the housing including a downstream edge portion at a downstream portion of the developing opening in a direction in which the developer holding device is rotated. The through portion has an inlet, an outlet, and a passage that connects the inlet and the outlet to each other so as to allow part of an airflow generated by rotation of the developer holding device to be introduced thereinto and flow therethrough. The directing device extends from a portion of the housing opposite to the developing opening with the inlet of the through portion interposed therebetween toward the developer holding device so as to direct the part of the airflow toward the inlet.

A developing device includes a developer bearer opposed to an image bearer, configured to bear developer and rotate in a direction of rotation of the developer bearer, and configured to develop a latent image on the image bearer and a casing opposed to the developer bearer at a position downstream from an opposed position, at which the developer bearer is opposed to the image bearer, in the direction of rotation of the developer bearer. A casing gap between the developer bearer and the casing continuously decreases or increases from a first end of the developing device to a second end of the developing device across a center of the developing device in a longitudinal direction of the developing device.

A development device includes components such as a housing, a magnetic roll in the housing that moves marking material in the housing, a donor roll in the housing that is positioned to receive the marking material from the magnetic roll, a manifold in the housing, etc. The manifold has a manifold opening positioned to create airflow from the surface of the donor roll. Further, such structures include a seal over the manifold opening. The seal is a component that has a planar linear surface with seal openings that are aligned with the manifold opening. The edge of the housing adjacent the manifold opening is a first distance from the magnetic roll and the edge of the seal is a second, closer distance from the magnetic roll.