A developer conveyor includes a shaft; a first blade helically wound around the shaft in a first direction, a second blade disposed away from an end of the first blade with a gap in a longitudinal axial direction of the developer conveyor and helically wound around the shaft in a second direction opposite the first direction, and a third blade helically wound around the shaft in the first direction at least at a position where the gap is formed.

A developing device includes a developer carrier that carries a developer to be supplied to an image carrier that forms an electrostatic latent image, a supply unit that supplies the developer containing toner and a carrier to the developer carrier by transporting the developer while agitating the developer along a circulation path formed through rotation of each of plural rotary members, and a delivery unit that receives a collected developer, which is the developer collected from the developer carrier, transports the collected developer by another rotary member different from the plural rotary members of the supply unit, and delivers the collected developer to the circulation path of the supply unit.

A developing device includes a rotating member that delivers developer to a latent image on an image carrier while rotating; a supplying member provided in a supply path extending in an axial direction of the rotating member; a stirring member including a stirring shaft extending in the axial direction and provided in a stirring path extending in the axial direction and arranged side by side with the supply path in a direction intersecting the axial direction, the stirring member stirring the developer while rotating by causing the developer to circulate between the supply path and the stirring path; and a preliminary member provided in a preliminary stirring path into which toner is supplied from an outside and provided by extending an end of the stirring path that is on a side where the developer delivered from the supply member is received by the stirring member, the preliminary member including an extension shaft as an extension of the stirring shaft and a helical transporting blade provided on the extension shaft, the transporting blade being divided into a first transporting blade and a second transporting blade provided across the first transporting blade from the stirring shaft, the preliminary member transporting the toner into the stirring path while rotating.

A transporting member includes a rotating shaft and plural helical blades that helically extend around the rotating shaft and that transport a transport object in a direction of the rotating shaft as the rotating shaft rotates, each helical blade including a downstream side surface at a downstream side in a transporting direction and an upstream side surface at a side opposite to the downstream side surface. A portion of at least one of the helical blades has a gap that enables the transport object to move in the direction of the rotating shaft, and the at least one of the helical blades includes an upstream section that extends upstream in a rotating-shaft rotation direction, in which the rotating shaft rotates, from the gap. The upstream section includes a portion in which an inclination angle of the downstream side surface is less than an inclination angle of the upstream side surface.

A feeding screw for feeding a developer includes a rotation shaft, and first, second, and third blade portions helically formed on the outer peripheral surface of the rotation shaft to feed the developer in one direction. The first blade portion and the second blade portion overlap with each other, the second blade portion and the third blade portion do not overlap with each other, and the third blade portion and the first blade portion overlap with each other, all with respect to the rotational axis direction of the feeding screw. A gap is provided between a downstream end of the second blade and an upstream end of the third blade portion in the one direction, and the gap is disposed within a region where the first blade portion is formed with respect to the rotational axis direction of the feeding screw.

A developing device includes a rotating member that delivers developer to a latent image on an image carrier while rotating; a supplying member provided in a supply path extending in an axial direction of the rotating member; a stirring member including a stirring shaft extending in the axial direction and provided in a stirring path extending in the axial direction and arranged side by side with the supply path in a direction intersecting the axial direction, the stirring member stirring the developer while rotating by causing the developer to circulate between the supply path and the stirring path; and a preliminary member provided in a preliminary stirring path into which toner is supplied from an outside and provided by extending an end of the stirring path that is on a side where the developer delivered from the supply member is received by the stirring member, the preliminary member including an extension shaft as an extension of the stirring shaft and a helical transporting blade provided on the extension shaft, the transporting blade being divided into a first transporting blade and a second transporting blade provided across the first transporting blade from the stirring shaft, the preliminary member transporting the toner into the stirring path while rotating.

A developing device includes a developer bearer rotatable in a rotation direction and forming a developing range, a holder, and an entrance seal. The holder has a facing face facing the developer bearer upstream from the developing range in the rotation direction, a support face defining a part of an outer face of the developing device, and a relay face extending from one end of the support face to one end of the relay face connected to the facing face to form an acute tip portion closer to the developing range than the one end. The entrance seal has a free end projecting from the one end as a cantilever, and a length of the entrance seal from a tip of the free end of the entrance seal to the one end is shorter than a length of the relay face from the acute tip portion to the one end.

A developing device is provided which includes: a developing roller in contact with or facing an image bearer; a supply roller to supply toner to the developing roller; a casing; a first conveyer disposed within the casing and above the supply roller to supply toner stored in the developing device to the supply roller, while forming a first conveyance path; a second conveyer disposed within the casing with an upper end thereof positioned below that of the first conveyer, while forming a second conveyance path forming a toner circulation path together with the first conveyance path; a partition wall separating the first conveyance path and the second conveyance path in a longitudinal direction within a range excluding both longitudinal end portions; and a toner supply port, at a ceiling of the casing above the second conveyance path, through which toner is supplied to an inside of the developing device.

A developing apparatus includes: a developer carrying body that carries a developer and is rotationally driven; a developer stirring member that is rotationally driven and thereby stirs the developer and conveys the developer to the developer carrying body; and a developer recovery member that is rotationally driven and thereby returns and recovers the developer stripped from the developer carrying body after development of the electrostatic latent image, to the developer stirring member, wherein a driving speed of the developer stirring member and a driving speed of the developer recovery member are independently controllable from each other.

A developing apparatus includes a developer bearing member configured to bear and convey a developer containing toner and carrier, a first conveyance screw arranged in a first chamber to convey the developer, a second conveyance screw arranged in the second chamber to convey the developer, and a permeability sensor configured to detect a permeability of the developer. A detection portion of the sensor is arranged below a rotational axis of the second conveyance screw, and a rib portion is formed so as to protrude in a radial direction from a rotation shaft of the second conveyance screw for supplying the developer toward the detection portion.