A developing device includes a developer container, a developer carrier, and first and second members for stirring/conveying. The developing container has a first partition wall between first and second chambers, communication portions through which those chambers communicate at opposite ends of the first partition wall, a developer supply port, and a developer discharge portion. The first member stirs and conveys developer in the first chamber in a first direction. The second member stirs and conveys developer in the second chamber in a second direction and includes a regulating portion and a discharging blade. The developer container includes a second partition wall between the first chamber and the regulating portion. The second partition wall is lower than the first partition wall, and an upper end part of the second partition wall is between upper and lower end parts of the rotary shaft of the second stirring/conveying member.

A developing device includes a developer cartridge and a developing unit. The developer cartridge, in some instances, may include a shutter. This shutter may have a wall for closing a developer supply hole, and be movable, with respect to a developer cartridge casing, between an open position where the supply hole is opened by the wall and a closed position where the supply hole is closed by the wall. The shutter may further include a protrusion that is movable with respect to the wall of the shutter between a first position and a second position in an axial direction. The protrusion, in the first position, is engageable with a developing unit and, in the second position, would be disengaged from the developing unit.

An image forming apparatus measures, using a toner concentration sensor installed in a developing apparatus of the image forming apparatus, a toner concentration of a developer stored in the developing apparatus to obtain an output waveform. The image forming apparatus calculates, based on the output waveform, a first characteristic value corresponding to a volume of the developer. Based on a result of comparing the first characteristic value with a reference value calculated from a reference output waveform obtained in an initial state of the developing apparatus, the image forming apparatus determines whether to execute a discharge mode for discharging the developer from the developing apparatus and to control an amount of the developer. The image forming apparatus discharges, according to a result of the determining, a portion of the developer from the developing apparatus by controlling a driving speed of the developing apparatus when the discharge mode is executed.

A developing device includes: a rotating member that passes a developer while rotating to an image holding body on which a latent image is formed; a housing in which a circulation path through which the developer to be supplied to the rotating member circulates and a branch path that is branched from the circulation path and through which a part of the developer is transported are formed; and a wall portion that forms the branch path at a part of the housing and in which an output port from which the developer is output to an outside and an exhaust port from which air in the branch path is output to the outside above the output port are formed.

A developing device includes a developer cartridge and a developing unit. The developer cartridge, in some instances, may include a shutter. This shutter may have a wall for closing a developer supply hole, and be movable, with respect to a developer cartridge casing, between an open position where the supply hole is opened by the wall and a closed position where the supply hole is closed by the wall. The shutter may further include a protrusion that is movable with respect to the wall of the shutter between a first position and a second position in an axial direction. The protrusion, in the first position, is engageable with a developing unit and, in the second position, would be disengaged from the developing unit.

A developing device includes a developer container including first and second chambers, first and second communication portions to permit the developer to communicate with the first and second chambers, first and second screws provided in the first and second chambers, respectively, and a developer discharging portion. The developer discharging portion is provided in a passage continuous with the first chamber and downstream of the first communication portion. In the developing device, a discharging method includes a step for inserting a shielding member into the second communication portion via an inserting opening of the developer container, and a step for discharging the developer from the developing device via the developer discharging portion, by rotating the first and second screws in a same direction as a direction of rotating during a developing operation in a state where the shielding member is inserted into the second communication portion.

An image formation apparatus according to an embodiment may include: an image formation section to form an image with a developer; an entire area printing rate calculator configured to calculate an entire area printing rate, which is, a printing rate of an entirety of an image formation area; a divided area printing rate calculator configured to calculate each divided area printing rate, which is, a printing rate of each of plural divided areas, divided in a main scanning direction, of the image formation area; and a deteriorated developer discarding operation execution section configured, when the entire area printing rate is equal to or lower than an entire area printing rate threshold, to perform a deteriorated developer discarding operation to discard the developer in any one of the divided areas in which the divided area printing rate is equal to or lower than a divided area printing rate threshold thereof.

A developer container includes: a containing unit that contains developer; a transport unit that transports the developer; and a receiving unit that receives a driving force transmitted from a transmitting unit of a body of an image forming apparatus and transmits the driving force to the transport unit. The developer container is removably attachable to the body of the image forming apparatus. The developer container includes a first rotation stopping portion and a second rotation stopping portion that is farther from the receiving unit than the first rotation stopping portion. When the developer container is attached to the body of the image forming apparatus, the first rotation stopping portion comes into contact with a first rotation stopper portion provided on the body of the image forming apparatus, and the second rotation stopping portion comes into contact with a second rotation stopper portion provided on the body of the image forming apparatus. A spatial allowance between the first rotation stopping portion and the first rotation stopper portion is less than a spatial allowance between the second rotation stopping portion and the second rotation stopper portion.

In an image forming apparatus, a calibration controller controls an exposure device to form a toner patch image for calibration in a non-printable area outside a printable area in a main scanning direction, and executes at least one of density adjustment and gradation adjustment based on a density measurement value of the toner patch image. A toner refresh controller controls the exposure device to form a toner band for toner refresh in accordance with a coverage rate. Further, when the length of the toner band to be formed in the non-printable area exceeds a predetermined threshold value, the toner refresh controller forms at least a part of the toner band to be formed in the non-printable area in parallel with a subsequent page image.

Examples disclosed herein relate to magnetic carrier bead separation in dual-component printing. The present disclosure relates generally to a device, method, and system for magnetic carrier bead separation. In an example, a printing device includes a developer sump to hold a plurality of carrier beads. The example device also includes a roller to move a subset of the plurality of carrier beads from an attachment point on the roller to a release point through a rotation of the roller, wherein the subset of the plurality of carrier beads return towards the developer sump after they are released at the release point. The device includes a magnetic separator located between the release point and the attachment point that guides a magnetized carrier bead of the plurality of carrier beads away from the developer sump and the roller.