An agitating screw at a first communication port delivering a developer from a collecting chamber to a developing chamber is formed to be a multiple-threaded screw. The use of the multiple-threaded screw makes it possible to increase a developer surface level at the first communication port. If the developer surface level becomes too high within the collecting chamber, an image defect caused by entrainment of the developer by the developing sleeve may occur. Then, an arrangement is made such that the developer surface level does not become so high that may cause the entrainment of the developer by accelerating delivery of the developer at the first communication port. Thus, the use of the multiple-threaded screw makes it possible to accelerate the delivery of the developer and to reduce an image defect otherwise caused by the entrainment of the developer.

An image forming apparatus includes a first image forming unit that forms a yellow image by an electrostatic charge image developing yellow toner; a second image forming unit that forms a magenta image by an electrostatic charge image developing magenta toner; a transfer unit that transfers the yellow image and the magenta image to a recording medium; and a fixing unit that fixes the yellow image and the magenta image to the recording medium, wherein a maximum absorption wavelength λmax (M) of the electrostatic charge image developing magenta toner at a wavelength of 360 nm to 760 nm is from 530 nm to 580 nm, and when an absorbance of the maximum absorption wavelength λmax (M) is standardized to 1, an absorbance at a wavelength of 450 nm is 0.20 or less and an absorbance at a wavelength of 400 nm is 0.10 or less.

A developer supply container 1 includes a cylindrical portion 2k capable of accommodating a developer; a second discharge opening 4a, provided on the cylindrical portion 2k, for permitting discharge of the developer; a storage portion 4d provided in the cylindrical portion 2k and capable of storing a predetermined amount of the developer through the second discharge opening 4a; a pump portion 3a having a changeable inside volume of cylindrical portion 2k in a longitudinal direction of the supply container 1 to apply a pressure at least to the second discharge opening 4a; a fluid communication path 20a providing fluid communication between the pump portion 3a and the storage portion 4d; and a partition 20 provided in a connecting portion between the pump portion 3a and the fluid communication path 20a for suppressing flow of the air which is produced by pump portion 3a and which is directed to toward cylindrical portion 2k at least in a discharging operation.

A recovery container includes: a container body that is attachable to and detachable from an attachment target and capable of accommodating a powder, a first insertion portion that is provided at the container body, is capable of protruding from one of two wall portions of the container body at opposite sides in a direction intersecting an attachment direction of the container body, and is to be inserted into a first opening provided in a portion of the attachment target facing the one of the two wall portions by movement in a protruding direction of the first insertion portion; a second insertion portion that is provided at the container body, is capable of protruding from other of the two wall portions to a side opposite to the first insertion portion, and is to be inserted into a second opening provided in a portion of the attachment target facing the other of the two wall portions by movement in a protruding direction of the second insertion portion; and a third insertion portion that is provided at the container body, is capable of protruding from the other of the two wall portions to a side same as the second insertion portion, and is to be inserted into a third opening provided in a portion of the attachment target facing the other of the two wall portions by movement in a protruding direction of the third insertion portion.

A magnetic one-component developer includes magnetic toner particles containing a binder resin and a magnetic powder, and silica particles having a compression and aggregation degree of 60% or more and 95% or less and a particle compression ratio of 0.20 or more and 0.40 or less.

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.

A developing device includes a developer carrier that opposes an image carrier and rotates while carrying developer on a surface thereof; and a container that supports the developer carrier in a rotatable manner and contains the developer, the developer containing toner, first carrier subjected to frictional charging together with the toner, and second carrier having a diameter greater than a diameter of the first carrier and an electrical resistance lower than an electrical resistance of the first carrier.

An electrostatic charge image developing toner includes toner mother particles that contain a polyester resin which is a polycondensate of a polycarboxylic acid compound and a polyol compound; a graft polymer which includes a polyolefin chain and a vinyl resin chain; a coloring agent; and polyethylene wax, provided that the polyol compound includes a polyol compound having a bisphenol structure in an amount of 0 mol % to 5 mol %, wherein a normal temperature and normal humidity aggregation degree of the toner mother particles is from 70% to 97%.

An image forming apparatus is disclosed. The image forming apparatus includes a print engine to perform a printing job using toner filled in a toner cartridge, a communicator to communicate with a memory chip attached to a toner refill apparatus which refills the toner cartridge with toner, a memory to store group information corresponding to a plurality of image forming apparatuses for sharing the toner refill apparatus, and a processor to determine whether or not the toner refill apparatus is usable based on information stored in a memory chip of the toner refill apparatus and group information stored in the memory.

An image forming apparatus may include a photosensitive member, a developing device including a developing roller, pressing members configured to engage with the developing device and springs configured to urge the pressing members. In some examples, each of the pressing members may be configured to contact and move the developing device between various positions based on the urging of the springs. Additionally or alternatively, various ends of a contact surface of the developing roller configured to contact developer may be disposed relative to an axis line of the developing roller and pressing surfaces of the pressing members.