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.

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.

Provided is an electrophotographic developer set having a toner and a powder adhesive, wherein the toner comprises a thermoplastic resin A; the powder adhesive comprises a thermoplastic resin B and a wax A; the wax A has two or more ester groups in the molecule; the thermoplastic resin B has an ester group; and in a viscoelasticity measurement, with Gt′(100) (Pa) being a storage elastic modulus at 100° C. of the toner, and Gb′(100) (Pa) being a storage elastic modulus at 100° C. of the powder adhesive, Gb′(100) is 1.00×10.sup.5 Pa or less, and Gt′(100)/Gb′(100) is 1.20 or more, as well as a method for producing a bonded product using the above electrophotographic developer set.

An image forming apparatus includes process units and developer cartridges; a process unit supporting member; a cartridge supporting member; and a moving mechanism. Each developer cartridge includes a transporting member configured to transport developer to a corresponding process unit. The moving mechanism is configured to move each transporting member between a communicated position, in which developer is transported to the corresponding process unit, and an interrupted position, in which transporting of developer to the corresponding process unit is interrupted. The transporting member positioned in the interrupted position allows the cartridge supporting member to move from an attached position to a withdrawn position and allows the process unit supporting member to be withdrawn, and the transporting member positioned in the communicated position prevents the cartridge supporting member from moving from the attached position to the withdrawn position and prevents the process unit supporting member from being withdrawn.

An image forming apparatus, having first, second, and third photosensitive drums, a first developing cartridge including a first developing roller, a second developing cartridge including a second developing roller, a third developing cartridge including a third developing roller, an exposure device, a conveyer, and a moving mechanism, is provided. The first developing roller, the second developing roller, and the third developing roller are arranged in the recited order from upstream to downstream in a moving direction for the sheet to be conveyed. When the second developing roller is at the separated position thereof, the second developing cartridge coincides with a light path of the laser beam for scanning the first photosensitive drum. When the third developing roller is at the separated position thereof, the third developing cartridge coincides with a light path of the laser beam for scanning the second photosensitive drum.

An image forming apparatus includes a first photosensitive drum, a first developing unit including a first developing roller configured to contact the first photosensitive drum, a second photosensitive drum, and a second developing unit including a second developing roller configured to contact the second photosensitive drum. The image forming apparatus includes a first movement mechanism configured to move the first developing unit so that the first developing unit is located at a first contact position and a first separation position, and a second movement mechanism configured to move the second developing unit so that the second developing unit is located at a second contact position, a second separation position, and an intermediate position between the second contact position and the second separation position.

An image forming apparatus includes: a first developing roller movable between a first contact position and a first separated position; a second developing roller movable between a second contact position and a second separated position; and a controller. When a sheet interval is shorter than a first interval and is longer than or equal to a second interval, the controller maintains the first developing roller at the first contact position even after the completion of its development for a preceding sheet, controls the first developing roller to start development for a subsequent sheet, moves the second developing roller to the second separated position after the completion of its development for the preceding sheet, moves the second developing roller again to the second contact position, and controls the second developing roller to start development for the subsequent sheet after the second developing roller is moved again to the second contact position.

An image forming apparatus includes: a first gear train including a first clutch; a second gear train including a second clutch; a third gear train including a third clutch; a fourth gear train including a fourth clutch; a motor including an output shaft; an output gear rotatable with the output shaft; a fifth gear train connected to the first and second clutches; and a sixth gear train connected to the third and fourth clutches. The first clutch engages transmission of a driving force to a first developing unit, the second clutch engages transmission of a driving force to a second developing unit, the third clutch engages transmission of a driving force to a third developing unit, and the fourth clutch engages transmission of a driving force to a fourth developing unit. The fifth and sixth gear trains are connected to the output gear independently from each other.

An image forming apparatus performs primary transfer of single-color toner image onto an intermediate transfer belt and performs secondary transfer of the toner image onto a sheet, and includes: single image forming unit forming the single-color toner image; single toner supply bottle containing replenishment toner; and first and second support members supporting the belt. The image forming unit is closer to the first member than the second member in a belt rotation direction. The bottle includes: single bottle body; and supply unit near one end of the body in the rotation direction. The other end is (i) closer to the second member than the one end is in the rotation direction and (ii) distant from the image forming unit in a support member direction from the first member toward the second member by one to three times a length of the image forming unit in the support member direction.

A toner set includes a plurality of toners, wherein the toner set includes a first toner containing a yellow colorant and a second toner containing a cyan colorant, the first toner and the second toner each contain a binder resin containing a vinyl-based resin and a crystalline resin, and a release agent containing a hydrocarbon wax, a content of the vinyl-based resin with respect to a total mass of the binder resin is 50% by mass or more, the first toner contains the crystalline resin having a moiety having a crystal structure and a crystal nucleating agent moiety having a crystal nucleating agent, and the second toner contains the cyan colorant that is a compound represented by general formula (1).

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