A developer cartridge is described. The developer cartridge detachably mountable on a tandem type photosensitive unit slidable to a drawn-out position and a mounted position with respect to an image forming apparatus body may include a casing; a developer carrier rotatably supported on one end portion of the casing for carrying a developer; a pair of upright portions arranged on another end portion of the casing at an interval from each other in the axial direction of the developer carrier to extend from another end portion of the casing in a detaching direction for the developer cartridge; and an elastically deformable coupling portion extending in the axial direction of the developer carrier for coupling the upright portions with each other.

An image forming apparatus is used, which includes a developer bearing member that transports developer to an electrostatic latent image formed on an image bearing member, a supply roller including a foam elastic member that supplies the developer to the developer bearing member, a power source device that applies a developing voltage to the developer bearing member and applies a supply voltage to the supply roller; a power source control unit that controls supply of the developer from the supply roller to the developer bearing member by controlling the developing voltage and the supply voltage; and an image control unit that controls formation of the electrostatic latent image based on image information. The image control unit controls, based on a first value, a change amount of the supply voltage in a period during which image formation is performed.

An image forming apparatus includes a conveyer roller exposed to an attachment space and a drive force transmission mechanism for transmitting a drive force from a drive source. The drive force transmission mechanism includes a plate driving gear exposed to the attachment space, a transmission gear train transmitting a drive force to the conveyer roller and to the plate driving gear, and a switching mechanism. The switching mechanism includes a driven gear transmitting the drive force to the transmission gear train, a pendulum gear revolvable between a coupled position in which the pendulum gear is engaged with the driven gear and an uncoupled position in which the pendulum gear is separated from the driven gear, and a transmission switch movable between a first position for holding the pendulum gear in the uncoupled position and a second position for allowing the pendulum gear to revolve between the coupled and uncoupled positions.

A developing unit includes a developing container, a developing sleeve, a developer regulating member, and a magnetic field generating portion. The magnetic field generating portion includes a drawing-up pole and a cut pole. In addition, in a peak-to-peak area, the magnetic field generating portion includes at least one of an Fr flat area in which Fr is substantially constant and an Fr attenuation area in which Fr attenuates toward the cut pole side from the drawing-up pole side, and is configured that F is oriented toward the same direction as a direction of rotation of the developing sleeve in the entire peak-to-peak area.

An image forming apparatus includes a conveyer roller exposed to an attachment space and a drive force transmission mechanism for transmitting a drive force from a drive source. The drive force transmission mechanism includes a plate driving gear exposed to the attachment space, a transmission gear train transmitting a drive force to the conveyer roller and to the plate driving gear, and a switching mechanism. The switching mechanism includes a driven gear transmitting the drive force to the transmission gear train, a pendulum gear revolvable between a coupled position in which the pendulum gear is engaged with the driven gear and an uncoupled position in which the pendulum gear is separated from the driven gear, and a transmission switch movable between a first position for holding the pendulum gear in the uncoupled position and a second position for allowing the pendulum gear to revolve between the coupled and uncoupled positions.

A power supply device according to the present disclosure includes an AC voltage output circuit and a DC voltage output circuit. The DC voltage output circuit includes a first voltage dividing resistor provided between a power supply line of a voltage output portion and a ground potential, a second voltage dividing resistor provided between the first voltage dividing resistor and the ground potential, a capacitor provided in parallel with the second voltage dividing resistor, and an operational amplifier. An output of the AC voltage output circuit is connected to the voltage output portion of the DC voltage output circuit. A cutoff frequency of a low-pass filter circuit constituted of the first voltage dividing resistor, the second voltage dividing resistor, and the capacitor is set to be lower than a frequency of the AC voltage output from the AC voltage output circuit.

A developing device includes a development roll that rotates while holding a developer, an image holding body that is disposed to face the development roll and that rotates, and a developer discharging duct through which the developer is sucked from an image holding body side and the developer is discharged to another place, in which the developer discharging duct includes a duct front wall that is disposed on the image holding body side and that has suction ports for sucking the developer, which are formed in end portions of the duct front wall on both sides in an intersection direction intersecting a rotation movement direction of the development roll, a duct rear wall that is positioned on a side opposite to the image holding body with respect to the duct front wall, and two duct side walls that are positioned at the end portions on both sides in the intersection direction, a discharge port for discharging the developer is formed in one duct side wall of the two duct side walls, at a position adjacent to the duct rear wall, and a side intake port for sucking air is formed in one duct side wall of the two duct side walls.

An image forming apparatus includes a developing device that develops an electrostatic latent image into a toner image and a cooling unit that cools the developing device with a cooling fluid. The cooling unit has a cooling pipe formed of a metal pipe and having an inner space of the pipe as a flow passage for the cooling fluid and a heat-dissipating member disposed between the cooling pipe and the developing device and contacting the cooling pipe and the developing device to conduct heat between the cooling pipe and the developing device. A part of the heat-dissipating member in contact with the cooling pipe is elastically deformable.

An electrostatic charge image developing carrier includes magnetic particles and a resin coating layer that coats the magnetic particles, in which the resin coating layer contains inorganic particles, and in a case where an element ratio of metals and metalloids, that constitute the inorganic particles, is analyzed by X-ray photoelectron spectroscopy in a depth direction, and the element ratio at 0 seconds of etching is defined as A and the element ratio at 300 seconds of etching is defined as B, a value of BA is 0.5 atm % or more and 3.0 atm % or less.