According to the present invention, there is provided a carrier core material that is formed of ferrite particles in which 48 to 52 mass % of Fe, 16 to 22 mass % of Mn, 1.0 to 3.5 mass % of Mg and 0.05 to 0.5 mass % of Ca are included, and when an electrical resistance value with an applied voltage of 500 V in an environment (in an L/L environment) in which the temperature is 10° C. and the relative humidity is 35% is R.sub.L (Ω.Math.cm), and an electrical resistance value with an applied voltage of 500 V in an environment (in an H/H environment) in which the temperature is 30° C. and the relative humidity is 70% is R.sub.H (Ω.Math.cm), formula (1) below is satisfied.
0.1≤(log R.sub.L−log R.sub.H)≤0.3  (1)

An image forming apparatus includes: an image carrier body to be transported; an image forming unit that forms an image on the image carrier body; a change roller that is in contact with an inner peripheral surface of the image carrier body so as to be rotatable around a rotation axis and that is capable of changing an angle of the rotation axis with respect to a width direction of the image carrier body; a flywheel provided at the change roller; and a driving mechanism that applies a driving force for changing an angle of the rotation axis with respect to the width direction to an applied portion that moves together with the change roller. A direction of the driving force applied to the applied portion by the driving mechanism is opposite to a direction in which the applied portion moves due to gravity acting on the flywheel.

An example device can include a reserve print materials container, an access port coupled to the reserve print materials container to receive, from a replenishment device, print materials directly to the reserve print materials container in-situ, and a main print materials container coupled to the reserve print materials container to receive print materials from the reserve print materials container.

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.

The image forming apparatus includes a drum cartridge having a photosensitive drum and a drum drive input member; a developing cartridge configured to be movably mounted to the drum cartridge, the developing cartridge comprising a developing roller disposed so as to face the photosensitive drum and a developing drive input member; a drum drive transmission member configured to engage with the drum drive input member and configured to transmit drum driving force to the drum drive input member while permitting a positional gap of the drum drive input member within a predetermined range; and a developing drive transmission member configured to engage with the developing drive input member and configured to transmit developing driving force to the developing drive input member while permitting a positional gap of the developing drive input member within a predetermined range.

A toner is provided. The toner comprises a maleic-acid-modified polyolefin having a polypropylene block in a main chain and having a weight average molecular weight of 60,000 or more.

According to examples, a toner refill apparatus may include a chamber to house a toner, in which the chamber may include an insertion section, the insertion section to be inserted into a refill port of a toner cartridge and including a discharge opening, the refill port including an electrical circuit component. The apparatus may also include a valve mechanism positioned at the discharge opening to control output of the toner from the chamber through the discharge opening, in which an actuator may engage the valve mechanism and may controllably open the valve mechanism. The apparatus may further include an electronic chip to be in electrical communication the electrical circuit component, in which a controller may activate the actuator based on a detection that the electronic chip is in contact with the electrical circuit component.

The image forming apparatus includes a drum cartridge having a photosensitive drum and a drum drive input member; a developing cartridge configured to be movably mounted to the drum cartridge, the developing cartridge comprising a developing roller disposed so as to face the photosensitive drum and a developing drive input member; a drum drive transmission member configured to engage with the drum drive input member and configured to transmit drum driving force to the drum drive input member while permitting a positional gap of the drum drive input member within a predetermined range; and a developing drive transmission member configured to engage with the developing drive input member and configured to transmit developing driving force to the developing drive input member while permitting a positional gap of the developing drive input member within a predetermined range.

A toner is comprised of toner particles and external additive adhering to the surface of the toner particles. The toner particles are formed from a binder resin, an ester wax, and a colorant. The external additive comprises a titanium oxide and silica. A first adhesive strength between the external additive and the toner base particles is in a range of 90 to 100% when measured as a ratio of X-ray spectroscopic intensity of titanium for toner particles before and after a washing process, and a second adhesive strength between the external additive and the toner base particles is in a range of 50 to 80% when measured as a ratio of X-ray spectroscopic intensity of silicon measured for toner before and after another washing process.

Provided is a method of operating an image forming apparatus. The method includes: calculating a remaining lifespan of at least one component consumed through an image forming job in the image forming apparatus; determining whether to proceed with a refill operation to refill a toner in a cartridge of the image forming apparatus, based on the remaining lifespan of the at least one component; and displaying guide information to guide the refill operation based on a result of the determining.