A toner container includes containing chambers, a shaft member, rotary members, and stirring members. The containing chambers are arrayed in a first direction and partitioned from each other. The containing chambers contain respective toners of different colors. The shaft member extends in the first direction, passes through the containing chambers, and is rotatable about a rotational axis extending in the first direction. The rotary members are disposed in the respective containing chambers and each have a through-hole extending in the first direction. The rotary members are rotatable in response to rotation of the shaft member in an inserted state of the shaft member in the through-holes. The stirring members are supported by the respective rotary members and each extend in a second direction intersecting the first direction. The stirring members are pivotable in response to rotation of the respective rotary members. The stirring members have different pivoting positions upon pivoting.

An image forming unit of an image forming apparatus includes a developing device and a toner replenishing unit that replenishes the developing device with toner. The toner replenishing unit includes an upper toner container, a lower toner container, a toner conveyance unit, and a replenishment control unit. The upper toner container and the lower toner container are disposed adjacently to each other in a vertical direction in an apparatus body. When the upper toner container becomes empty, the replenishment control unit controls the toner replenishing unit so as to replenish the developing device with the toner from the lower toner container.

An electrophotographic image forming apparatus includes a latent image bearer to rotate and bear a latent image, a charging device to charge the a latent image bearer, a developing device to develop the latent image with developer including toner and use a developing voltage including an AC component, and a lubricant applicator to apply lubricant onto a surface of the latent image bearer. An amount of the lubricant applied by the lubricant applicator onto the latent image bearer per centimeter in an axial direction of the latent image bearer is equal to or greater than 0.845 mg for a running distance of 1.0 kilometer of the latent image bearer, and a difference between a largest value and a smallest value of the developing voltage is in a range of 200 V to 400 V.

An image forming unit of an image forming apparatus includes a developing device and a toner replenishing unit that replenishes the developing device with toner. The toner replenishing unit includes an upper toner container, a lower toner container, a toner conveyance unit, and a replenishment control unit. The upper toner container and the lower toner container are disposed in a staggered manner in an apparatus body. When the upper toner container becomes empty, the replenishment control unit controls the toner replenishing unit so as to replenish the developing device with the toner from the lower toner container.

An image forming unit of an image forming apparatus includes a developing device and a toner replenishing unit that replenishes the developing device with toner. The toner replenishing unit includes an upper toner container, a lower toner container, a toner conveyance unit, and a replenishment control unit. The upper toner container and the lower toner container are disposed adjacently to each other in a vertical direction in an apparatus body. When the upper toner container becomes empty, the replenishment control unit controls the toner replenishing unit so as to replenish the developing device with the toner from the lower toner container.

A charge roller includes, in a surface thereof, recesses that have sizes that are equivalent to or larger than a volume average particle diameter of a toner accommodated in a developing unit and that are capable of collecting the toner retransferred to a photosensitive drum.

A toner container includes containing chambers, a shaft member, rotary members, and stirring members. The containing chambers are arrayed in a first direction and partitioned from each other. The containing chambers contain respective toners of different colors. The shaft member extends in the first direction, passes through the containing chambers, and is rotatable about a rotational axis extending in the first direction. The rotary members are disposed in the respective containing chambers and each have a through-hole extending in the first direction. The rotary members are rotatable in response to rotation of the shaft member in an inserted state of the shaft member in the through-holes. The stirring members are supported by the respective rotary members and each extend in a second direction intersecting the first direction. The stirring members are pivotable in response to rotation of the respective rotary members. The stirring members have different pivoting positions upon pivoting.

A color toner printer system that is configured to both over print in a single pass and under print in a single pass, and that is configured to switch between over and under printing, the system comprising: a color toner printer comprising at least four toner printing cartridge slots, a front slot, a second slot, a third slot, and a rear slot, which are configured to matingly engage with at least four toner printing cartridges comprising three color toner printing cartridges and a non-standard toner printing cartridge; and a raster image processor software. The color toner printer is configured to over print when the non-standard toner printing cartridge is in said rear slot, and to under print when the non-standard toner printing cartridge is in said front slot. The RIP software is configured to (1) remap the color toner printer to reflect an actual placement of the at least four toner printing cartridges and (2) allows said color toner printer to under print in a single pass or over print in a single pass.

The image-forming apparatus includes multiple developing units that form images using multiple color developers, an image carrier that, in color displacement detection, carries the developers transferred thereon at mutually different image-carrying positions, an optical sensor that projects a light to the image carrier and receives a reflected light from the image carrier, and an acquirer that acquires, in response to output from the optical sensor, passage times at which the developers on the image carrier respectively pass a detection position. The optical sensor receives a diffusively reflected light from a non-transferred area of the image carrier on which the developers are not transferred. The acquirer acquires the passage times of all the developers, in response to changes in the output from the optical sensor at an output level higher than that corresponding to a diffusively reflected light from the developers on the image carrier.

An image forming apparatus according to an embodiment includes an image forming unit, a heating unit, a fan, a guide, and a control unit. The image forming unit forms an image on a recording medium. The heating unit is disposed on a downstream side of the image forming unit in a transport direction of the recording medium. The heating unit is driven with at least two temperatures, a first temperature and a second temperature lower than the first temperature. The fan generates wind. The guide guides the wind generated from the fan to the heating unit. The control unit controls the fan and the guide when the control unit controls the heating unit by switching between driving the heating unit at the first temperature and at the second temperature.