An image forming apparatus includes a latent image bearer, an electrostatic latent image forming device, a potential sensor, a toner image forming device, a toner adhesion amount detector, and circuitry. The circuitry controls the electrostatic latent image forming device to create an adjustment pattern on the latent image bearer when the image forming apparatus is not printing, controls the potential sensor to detect an electric potential of the adjustment pattern, controls the electrostatic latent image forming device and the toner image forming device to create a test toner image during a printing period, controls the toner adhesion amount detector to detect a toner adhesion amount of the test toner image, and adjusts at least one image forming condition of the electrostatic latent image forming device and the toner image forming device based on the electric potential of the adjustment pattern and the toner adhesion amount of the test toner image.

An image forming apparatus for developing an image with developer includes a development part, a transfer part, and a fuser the medium. The developer is configured with a plurality of particles, an average circularity degree of the developer is ranged within 0.955 to 0.970, and a peeling rate (%) of the external additive by a following equation is 30.6% or less,
peeling rate (%)=[1(X/Y)]100(1) wherein X is an amount (weight %) of the external additive included in the developer after ultrasonic waves are applied, and Y is an amount (weight %) of the external additive included in the developer before the ultrasonic waves are applied.

Provided here are toner sets and image forming apparatus and methods for the formation of a bright image with excellent brightness and concealability. A toner set according to an embodiment comprises a first toner which is stored in a first container and comprises a plurality of first toner particles containing a first bright pigment and a first binder resin, and a second toner which is stored in a second container and comprises a plurality of second toner particles containing a second bright pigment and a second binder resin, wherein the second toner has a larger volume average particle diameter than the first toner.

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.

An image forming apparatus includes an intermediate transferor to rotate in a predetermined rotation direction, a plurality of image bearers disposed along the intermediate transferor to bear latent images, a plurality of developing devices to develop the latent images, a plurality of developer containers to contain developers, and a plurality of conveyance paths each corresponding to a respective one of the plurality of developing devices and a respective one of the plurality of developer containers to supply the developers to the plurality of developing devices respectively. An arrangement of the plurality of developing devices in the predetermined rotation direction is configured to be changed without changing an arrangement of the plurality of developer containers. A layout of the plurality of conveyance paths is configured to be changed without changing connections between a supply source and a supply destination of the plurality of conveyance paths.

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.

An electrostatic charge image developing toner includes a toner particle, a polishing agent particle, and a fatty acid metal salt particle, wherein a rate of the fatty acid metal salt particles strongly attached to the surface of the toner particles is equal to or greater than 50% by number with respect to the fatty acid metal salt particles attached to the surface of the toner particles.

An image forming apparatus executes reverse charging, toner-supply suspension, second exposure, and second charging, while a photosensitive member rotates at least a full turn. In the reverse charging, a charger charges a portion of a circumferential surface of the photosensitive member to a specified polarity. In the toner-supply suspension, before the portion, which has been charged to the second polarity in the reverse charging, of the circumferential surface of the photosensitive member passes a position at which the developer from the developing unit is configured to initially adhered to the circumferential surface, a developing unit stops supplying developer to the circumferential surface. In the second exposure, an exposure device exposes the portion, which has been charged to the specified polarity in the reverse charging, of the circumferential surface. In the second charging the charger charges the portion, which has been exposed in the second exposure, of the circumferential surface.

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.

An image forming system includes an image forming unit that forms an image on a recording medium by using a color toner, an applying unit that applies a crimping toner having pressure-responsiveness onto at least a portion of a surface of the recording medium on which the image is formed, a heating unit that heats the crimping toner applied to the recording medium, and a pressurizing unit that pressurizes, in a thickness direction, a stacked body in which the recording medium is folded with the heated crimping toner interposed or a stacked body in which the recording medium and another medium are stacked with the heated crimping toner interposed, in which a volume average particle diameter of the crimping toner is more than a volume average particle diameter of the color toner.