An image forming apparatus is configured to determine that a toner container was replaced during power off in a case where identification information acquired from a toner container and identification information stored in a nonvolatile memory do not match each other when power is turned on. In a case where the replaced toner container does not satisfy a replacement condition and does not contain a black toner, the image forming apparatus permits the execution of printing in a monochrome print mode, and suspends the execution of printing in the color print mode.

A method for estimating an amount of toner in a reservoir of an image forming device according to one example embodiment includes rotating a shaft positioned in the reservoir. By rotating the shaft, a first magnet and a second magnet having a variable angular offset between them are rotated around an axis of rotation of the shaft. The first magnet and the second magnet are continually sensed at a point in their rotational paths. An amount of angular offset between the first magnet and the second magnet is continually determined from the sensing. An estimate of the amount of toner remaining in the reservoir is continually updated based on a predetermined correlation between the determined amount of angular offset between the first magnet and the second magnet and the amount of toner remaining in the reservoir.

A powder detector includes a driver to drive a motor, a stirrer to stir powder in a vessel, a vibration plate disposed in the vessel and vibrated by a flip of the stirrer rotated by the motor, and circuitry. The circuitry detects a vibration of the vibration plate, estimates an amount of powder based on a detection result of the vibration, and causes the driver to drive the motor from a starting point, so as to move the stirrer to a preset halt position. The starting point is a rotation angle of the motor on detection of the vibration.

A toner container according to one example embodiment includes a housing having a reservoir for storing toner. A rotatable shaft is positioned within the reservoir and has an axis of rotation. A first magnet is rotatable with the shaft around the axis of rotation. An arm connected to the shaft leads the first magnet around the axis of rotation in an operative rotational direction of the shaft. A second magnet connected to the shaft trails the first magnet around the axis of rotation in the operative rotational direction. The arm is operatively connected to the second magnet such that an angular offset between the first magnet and the second magnet increases as an angular offset between the first magnet and the arm increases and the angular offset between the first magnet and the second magnet decreases as the angular offset between the first magnet and the arm decreases.

An image forming apparatus includes a main housing, an intermediate transfer belt, a development device, a toner box, and a pipe. The development device includes a development housing having an inlet through which toner is received, and a development roller rotatable about a development axis. The development device is detachably attachable to the main housing. The toner box is detachably attachable to the main housing and contains toner therein. The pipe has a pipe opening through which toner is provided to the development device. The development device is positioned below the intermediate transfer belt. The toner box is positioned above the intermediate transfer belt. In a state where the development device is attached to the main housing, the inlet of the development housing is opposed to the pipe opening and is configured to receive toner delivered by the pipe.

An image bearing member unit and a developing unit are respectively configured to be attachable to and detachable from an apparatus main body of an image forming apparatus, the image bearing member unit has a first memory that stores information related to a toner amount during a toner supply in accordance with a drive amount of the image bearing member, the developing unit has a second memory that stores information related to a toner amount during the toner supply in accordance with a use amount of the developing unit, and a control device controls, during the toner supply, the toner supply with a toner amount based on the information stored in the first memory and the information stored in the second memory.

A toner level detection assembly for an electrophotographic image forming device according to one example embodiment includes a rotatable shaft is positioned within a toner reservoir. A magnet is connected to the shaft and is rotatable with the shaft around an axis of rotation of the shaft. The magnet is pivotable independent of the shaft about a pivot axis that is spaced radially from the axis of rotation such that a radial distance of the magnet from the axis of rotation varies as the magnet pivots about the pivot axis. A first magnetic sensor is positioned to sense the magnet within a first range of radial distances from the axis of rotation. A second magnetic sensor is positioned to sense the magnet within a second range of radial distances from the axis of rotation.

An image forming apparatus includes a rotatable image bearing member, a developing device including a developing carrying member and configured to develop an electrostatic image formed on the image bearing member with developer, an electrostatic capacity detecting portion configured to detect information on electrostatic capacity between the developer carrying member and the image bearing member, and a toner content detecting portion configured to detect information on a toner content of the developer accommodated in a developing container. On the basis of the detected electrostatic capacity and the detected toner content, a controller controls a driving speed at which the developer carrying member is rotationally driven.

A powder detector includes a driver to drive a motor, a stirrer to stir powder in a vessel, a vibration plate disposed in the vessel and vibrated by a flip of the stirrer rotated by the motor, and circuitry. The circuitry detects a vibration of the vibration plate, estimates an amount of powder based on a detection result of the vibration, and causes the driver to drive the motor from a starting point, so as to move the stirrer to a preset halt position. The starting point is a rotation angle of the motor on detection of the vibration.

Provided is an image forming apparatus, which is configured to determine that a toner container was replaced during power off in a case where identification information acquired from a toner container and identification information stored in a nonvolatile memory do not match each other when power is turned on. In a case where the replaced toner container does not satisfy a replacement condition and does not contain a black toner, the image forming apparatus permits the execution of printing in a monochrome print mode, and suspends the execution of printing in the color print mode.