A developing unit includes a developer bearing member that rotates and bears a developer including a toner and a carrier. A controller switches between a first mode and a second mode based on information which influences a toner charging amount. In the first mode, the developer bearing member rotates during a predetermined operation period from a command of an image forming operation until start of forming the electrostatic latent image. Meanwhile, in the second mode, a total number of rotations of the developer bearing member during the predetermined operation period is smaller than that in the first mode.

An image forming device includes a communication device, an image forming unit, a transfer unit, a transmitting unit, and a processor. The communication device communicates includes a wireless tag. The image forming unit forms a developer image on a surface of a photoreceptor. The transfer unit transfers the developer image to a medium provided with the wireless tag communicating with the communication device. The transmitting unit transmits the medium to the transfer unit. The processor controls an operation of the transmitting unit so as to transmit the medium at a first timing when communication with the wireless tag by the communication device is normally executed and controls the operation of the transmitting unit so as to transmit the medium at a second timing different from the first timing when the communication with the wireless tag by the communication device is not normally ended.

An image forming apparatus includes an image bearing member, a developing device configured to develop an electrostatic image formed on the image bearing member into a toner image, and an exchangeable developer container configured to supply the developer into the developing device. A content sensor detects information relating to a toner content in the developing device, and an exchange detecting portion detects an exchanging operation of the developer container. A controller controls a supplying operation for supplying the developer from the developer container to the developing device on the basis of a detection result of the content sensor and executes a developer supplying mode for supplying developer prohibiting an image forming operation. The controller controls the supplying operation so as to permit the image forming operation without executing the developer supplying mode until an amount of formed images reaches a predetermined level.

What is provided is an image forming apparatus in which longitudinal end portions of a developer bearing region or longitudinal end portions of an opening are respectively located outside longitudinal end portions of a transfer bias applicable region.

A method of controlling toner development during a life of an imaging unit in an image forming device by determining whether an end of life of the imaging unit has been reached and upon a positive determination, performing at least one of incrementally lowering a target toner mass to be measured by a toner patch sensor and incrementally reducing the magnitude of voltage biases applied to at least one of the magnetic roll and the charging roll of the imaging forming device. Performing the acts of incrementally lowering and reducing are repeated until the imaging unit is replaced. The method reduces the risk of damage to the image forming device due to carrier bead development while allowing for printing to occur.

A method of controlling toner development during a life of an imaging unit in an image forming device by determining whether an end of life of the imaging unit has been reached and upon a positive determination, performing at least one of incrementally lowering a target toner mass to be measured by a toner patch sensor and incrementally reducing the magnitude of voltage biases applied to at least one of the magnetic roll and the charging roll of the imaging forming device. Performing the acts of incrementally lowering and reducing are repeated until the imaging unit is replaced. The method reduces the risk of damage to the image forming device due to carrier bead development while allowing for printing to occur.

A developing device includes a developing roller and a conveyor roller. The developing roller includes a first magnet. The conveyor roller includes a second magnet. The first magnet includes a first magnetic pole and a second magnetic pole. The second magnet includes a third magnetic pole and a fourth magnetic pole. The first and fourth magnetic poles are magnetic poles having the same polarity. One of the second and third magnetic poles is a magnetic pole having the same polarity as the first magnetic pole. The other of the second and third magnetic poles is a magnetic pole having a polarity different from the first magnetic pole. The developer is transferred from the conveyor roller to the developing roller by the third and second magnetic poles. The developer is transferred from the developing roller to the conveyor roller by the first and fourth magnetic poles.

A developing device includes a developing roller, a conveyor roller, a developer stirring unit and a development bias applying unit. The developing roller is arranged to face a photoconductive drum at a predetermined developing position and supplies the toner. The conveyor roller is arranged to face the developing roller at a predetermined facing position and supplies the developer to the developing roller. The development bias applying unit applies development biases to the first sleeve of the developing roller and the second sleeve of the conveyor roller during a developing operation of developing the electrostatic latent image on the photoconductive drum with the toner. The development bias applying unit applies the development biases such that a shifting electric field to move the toner on the first sleeve of the developing roller toward the second sleeve of the conveyor roller is formed at the facing position during the developing operation.

A developing device for developing an electrostatic latent image on an image carrier by using developer includes a developing bias output unit configured to output a developing bias generated by superimposing an AC bias on a DC bias, a developing sleeve supplied with the developing bias output from the developing bias output unit, and a prevention bias generator unit configured to generate a prevention bias by holding a peak value of the developing bias of the superimposed AC bias and DC bias, with the prevention bias suppressing scattering of developer carried by the developing sleeve. In addition, an electrode is disposed at a position opposing the developing sleeve and configured to output the prevention bias.

There are provided a developing device including a developing roller to develop an image carrier by use of a two-component developer and a developing bias power source, and an image forming apparatus using the developing device. The developing device further includes a variable resistance unit provided on a bias apply path to apply a bias from the developing power source to the developing roller, and a resistance controller to control a resistance value of the variable resistance unit based on a charge amount signal indicating a toner's charge amount in a developer layer on the developing roller. The resistance controller provides a low mode to lower the resistance of the variable resistance unit and a high mode to enhance the resistance. The low mode is set if the toner charge amount is low, and the high mode is set if the toner charge amount is high.