A developing device includes a casing to contain developer, a developer bearer, an upper and lower developer conveyors to convey the developer to one side in an axial direction of rotation shafts thereof, a communicating portion disposed on a first end side on which an input gear is disposed, to fall the developer from the upper developer conveyor to the lower developer conveyor, bearings to receive end portions the upper and lower developer conveyors, and first and second end seals to seal gaps in the bearings on the upper and lower developer conveyors, respectively. The first end seals and the second end are disposed on the first end side and a second end side, respectively. A sliding friction between the rotation shaft and at least one of the first end seals is smaller than a sliding friction between the rotation shaft and the second end seal.

An image forming apparatus that continuously carries out image formation on a plurality of recording materials includes an image bearing member and a developing device configured to develop an electrostatic latent image on the image bearing member. A first feeding screw is provided in a developing chamber and includes a first screw portion, a second screw portion and a third screw portion. Each of the second and third screw portions are provided with a blade portion formed helically on an outer peripheral surface of a rotation shaft of the first feeding screw, and the first screw portion is not provided with the blade portion. Based on information on the relative humidity in the developing container and on the amount of toner consumed with the image formation on a plurality of recording materials, a controller controls a driving speed for rotationally driving the first feeding screw by a driving device.

A developing apparatus includes a developer container, a conveyance portion, a density detection unit, and a projected portion. The conveyance portion includes a shaft portion and a conveying blade. The projected portion is projected from the shaft portion in a radial direction of the shaft portion such that a position of the projected portion overlaps with a detection surface of the density detection unit in an axial direction of the shaft portion. The projected portion is shaped such that a part between both end portions of the projected portion in the axial direction is positioned upstream in a direction of rotation of the conveyance portion than the both end portions.

A developing device is equipped with a developing roller rotationally driven for developing an electrostatic latent image formed on a surface of an image supporting body with toner, a screw rotationally driven of which a ratio of number of rotations to number of rotations of the developing roller being rotationally driven is constant, and a processor. The processor is configured to detect toner density in developer by using a sensor installed facing the screw, during rotationally drive of the screw, and detect information indicating a rotational position of the developing roller, based on ripples which occur in the toner density detected.

A developing device includes a developer bearer, a magnetic field generator, a casing having an opening, a developer conveyor to rotate inside a developer containing compartment below the developer bearer, and a developer regulator. A side wall of the casing defines a bottom end of the opening, and the developer regulator is disposed on the side wall. The side wall includes an upper end face facing the developer bearer below an axis of the developer bearer and a curved inner face along an orbit of rotation of the developer conveyor, extending from below the developer conveyor toward the upper end face. On a virtual plane perpendicular to the axis of the developer bearer, an intersection between a tangent line to an upper end of the curved inner face and the surface of the developer bearer is in a range from a tangential magnetic-flux peak and a closest approach point.

A developing device has a developer container, a first stirring/transporting member, a second stirring/transporting member, a developer carrying member, a developer supply port, a developer discharge port, a regulating portion, and a height adjustment opening. The developer container has a partition partitioning between first and second transport chambers, and communication portions through which the first and second transport chambers mutually communicate. The first and second stirring/transporting members stir and transport developer in the first and second transport chambers in opposite directions respectively. The regulating portion regulates movement of the developer toward a developer discharge port. The height adjustment opening is formed in the partition, and when the height of the developer in the second transport chamber is equal to or higher than a predetermined height, part of the developer passes through the height adjustment opening and moves to the first transport chamber.

A waste toner collecting device includes an intermediate collection box, a conveying path, a conveying screw, an exhaust path and a floating toner collection chamber. The conveying path is provided in the intermediate collection box. The conveying screw is rotatable in the conveying path. Through the exhaust path, air containing a floating toner is sucked and passed. The floating toner collection chamber is provided on a part of the exhaust path in the intermediate collection box. The floating toner collection chamber has a discharge opening opened to an inside of the intermediate collection box and a discharge door. Rotation of the conveying screw in a normal direction turns the discharge door into a storage position where the discharge opening is closed. Rotation of the conveying screw in a reverse direction turns the discharge door into a discharge position where the discharge opening is opened.

A developing device has a developer container, first and second stirring members, and a developer carrying member. The developer container has a plurality of transport chambers including first and second transport chambers, a communication portion through which the first and second transport chambers mutually communicate in opposite end parts thereof in their longitudinal direction, a developer supply port, and a developer discharge port arranged in a downstream-side end part of the second transport chamber. The second stirring member has a second transport blade, a regulating portion formed on the downstream side of the second transport blade, a discharge blade formed on the downstream side of the regulating portion and discharging developer through the developer discharge port, and a disk formed at a position facing the downstream-side communication portion on the upstream side of the regulating portion and radially protruding over the entire circumference of a rotary shaft.

A developing device includes a developer bearer disposed facing a latent image bearer in a developing range to transport developer by rotation, a support to support the developer bearer and including a holder mount, a rod-shaped developer regulator disposed facing a surface of the developer bearer across a gap, and a holder secured to the holder mount of the support to hold the rod-shaped developer regulator. The rod-shaped developer regulator extends in an axial direction of the developer bearer.

A developing device includes a rotatable developer carrying member, first and second chambers, a first rotatable feeding member, a second rotatable feeding member, a first communication port, a second communication port, and a toner content detecting portion including a planar detecting surface including at least a planar coil. The detecting surface is provided in a region of the first communication port sandwiched between rotational axes of the first and second rotatable feeding members and is disposed at a position such that the developer is fed toward both sides of the toner content detecting portion in a direction in which the detecting surface crosses the first direction.