An image forming apparatus includes a rotatable image bearing member and a rotatable developing member to carry developer made up of toner particles and carrier particles adhered to surfaces of the toner particles. Where a pressing force pressing the developing member against the image bearing member is F1, a total number of the carrier particles interposed between the toner particles and the image bearing member is N1, and an adhesion Ft between a carrier particle and a toner particle, measured when the carrier particle is pressed against the toner particle with F1/N1 that is a pressing force per unit carrier particle, and an adhesion Fdr1 between the carrier particle and the image bearing member, measured when the carrier particle is pressed against the image bearing member with F1/N1, satisfy Ft≤Fdr1.

A powder container includes a discharge port, and a container identifier shape portion provided on a front end surface of the powder container in an insertion direction and that functions to identify a type of the powder container, the insertion direction being a direction in which the container body is inserted. The powder container further includes a driven portion that interlocks with a first main-body interlocking portion of the image forming apparatus at the time of setting in the main body of the image forming apparatus, and an identifier opening group that starts to interlock with a second main-body interlocking portion of the image forming apparatus after the driven portion starts to interlock with the first main-body interlocking portion. A position of the identifier opening group relative to the driven portion in the circumferential direction varies depending on a type of the powder container to be identified.

A controller is configured to execute a larger gamut technology mode in which the controller performs image formation by controlling a ratio of a rotation speed of a development roller to a rotation speed of a photosensitive drum such that the ratio becomes a second speed ratio higher than a first speed ratio in a normal mode. The controller is configured to, when the controller executes the larger gamut technology mode, control transfer voltage based on a humidity around an image forming apparatus.

An embodiment of the present disclosure provides a developing cartridge, including: a developing cartridge frame having an internal space for accommodating a developing agent; a developing roller rotatably mounted on the developing cartridge frame and configured to supply the developing agent to a photosensitive drum; a drive end cover mounted on a drive end of the developing cartridge frame; and a drive force receiving member rotatably mounted on a drive end of the developing cartridge frame; where the drive force receiving member includes a drive force receiving part that extends out of the drive end cover and receives a rotational drive force. A driving end separation force receiving member is provided on an outer circumference of the drive force receiving part. The driving end separation force receiving member is configured to receive a separating force that separates the developing roller from the photosensitive drum.

A developing cartridge includes a frame rotatably supporting a developing roller. The developing cartridge also includes a first supporting member attached to a first end of the frame, with the first supporting member being movable relative to the frame. The developing cartridge further includes a second supporting member attached to a second end of the frame, with the second supporting member being movable relative to the frame and the first supporting member.

A developing cartridge includes: a casing configured to store developer; a developing roller configured to rotate about a first axis extending in a first direction; a shaft provided at one end of the casing in the first direction; and an electrode configured to rotate about the shaft and supply power to the developing roller. The shaft extends in the first direction and has a peripheral surface. The electrode has a first protrusion configured to rotate together with the electrode, the first protrusion extending along a portion of the peripheral surface of the shaft.

A developing roller is located nearer a first end than a second end in a first direction. A first boss extends in a second direction and is movable together with a housing. The first boss bears the weight of a developer cartridge when the first boss is supported by a support surface of a first side plate of a drum unit, and is located away from the developing roller in the first direction and the third direction. A first pressure receiving surface is located farther away from the developing roller than the first boss in the third direction. The pressure receiving member receives a pressing force in the third direction from a pressing member of the first side plate of the drum unit. The first boss is located away from the developing roller in the first direction by a first distance. The first pressure receiving surface is located away from the developing roller in the first direction by the first distance or by a second distance smaller than the first distance.

A developing cartridge includes a casing and a developing roller. The casing has an accommodation chamber, first and second ribs, a handle, and first and second pressure members. The accommodation chamber has one end portion and another end portion in a first direction, and an outer surface. The developing roller is positioned at one side of the accommodation chamber in a second direction. The ribs, the handle, and the pressure members are positioned at another side of the accommodation chamber in the second direction. The ribs and the pressure members are positioned at the outer surface. The handle is positioned between the first rib and the second rib in the first direction. The first pressure member is positioned between the handle and the first rib in the first direction. The second pressure member is positioned between the handle and the second rib in the first direction.

Provided is a developing device including: a toner; and a developer carrying member. The developer carrying member includes an electroconductive substrate and a surface layer on the substrate, the surface layer being a single layer and including a matrix containing a crosslinked urethane resin as a binder, wherein E1≥200 MPa and 10 MPa≤E2≤100 MPa, where E1 is an elastic modulus of the matrix in a first region from an outer surface of the surface layer to a depth of 0.1 and E2 is an elastic modulus of the matrix in a second region from a depth of 1.0 to 1.1 μm from the outer surface. The toner includes a toner particle containing a binder resin and a colorant and having a Martens hardness of 85 to 1,100 MPa when measured under a condition of a maximum load of 2.0×10.sup.−4 N.

A color measurement device includes a conveying roller unit that conveys a sheet in a conveying direction, a color sensor that is movable in a direction orthogonal to the conveying direction and measures a color of an image formed on the sheet, a white reference plate having a reference surface for measurement by the color sensor for calibration of the color sensor, lifting rollers that move with the color sensor and retain the sheet, and slid-on members that protrude to a level higher than the reference surface in a perpendicular direction to the reference surface. When the color sensor moves such that at least part of the lifting rollers overlaps the white reference plate as viewed from the perpendicular direction, the lifting rollers are brought into contact with the slid-on members, whereby a space is formed between the lifting rollers and the reference surface.