A developing cartridge is provided. The developing cartridge includes a housing which accommodates developer therein, a receiving member provided which couples with a force output member of an image forming apparatus to receive a driving force, a developing roller which rotates by the driving force received by the receiving member; a detectable rotary member having a first detectable portion and a second detectable portion and rotates by the driving force from a first rotational position where the first detectable portion is detected by a detection member provided in the image forming apparatus to a second rotational position where the second detectable portion is detected by the detection member, and a cut-off mechanism which cuts off a transmission of the driving force from the receiving member to the detectable rotary member in a state where the detectable rotary member is positioned in the second rational position.

An image forming apparatus includes an apparatus body and a unit detachably mounted to the apparatus body and comprising a unit body, a cam, a first movement member, and a second movement member. The unit includes a first contact portion, an urging portion, and a second contact portion. The second movement member is attachable to the first movement member in a first manner or a second manner. A detection pattern of a detection signal differs between a state in which the second movement member is in contact with the first contact portion and a state in which the second movement member is in contact with the second contact portion, and differs between a state in which the second movement member is attached in the first manner and a state in which the second movement member is attached in the second manner.

An image formation apparatus includes: a replaceable part attached to an image formation device and including an information storage unit having unique identification information stored therein; an error detector which detects an occurrence of an anomaly; an error code storage unit having a first error code and a second error code stored therein, each code indicating a content of error display concerning the anomaly; and a controller which determines whether the replaceable part is of a first type or a second type based on the identification information. The controller outputs a first notification signal indicating a content corresponding to the anomaly of the first error code if the replaceable part is of the first type when the error detector detects the anomaly, and outputs a second notification signal indicating a content corresponding to the anomaly of the second error code if the part is of the second type.

A developing cartridge may include a rotary gear rotatable about one axis and a detection gear rotatable about another axis. The detection gear is configured to be not rotatable with the rotary gear in a case where the rotary gear rotates from a first rotational position to a second rotational position, while being configured to be rotatable with the rotary gear in a case where the rotary gear rotates from the second rotational position to a third rotational position.

A developing cartridge may include a rotary gear rotatable about one axis and a detection gear rotatable about another axis. The detection gear is configured to be not rotatable with the rotary gear in a case where the rotary gear rotates from a first rotational position to a second rotational position, while being configured to be rotatable with the rotary gear in a case where the rotary gear rotates from the second rotational position to a third rotational position.

A developing cartridge includes: a casing; a developing roller; a developing electrode; a gear; a rack gear including a protrusion; and a cam having first and second cam surfaces. The rack gear meshes with the gear and is movable in a direction from one end toward another end of the casing. The cam is movable from a first position to a second position. The first cam surface of the cam at the first position contacts the protrusion, and causes the cam to move to the second position as the rack gear moves in the direction in a state where the first cam surface is in contact with the protrusion. A second cam surface moves the developing electrode in a direction away from the cam different from moving directions of the rack gear and the cam while contacting the developing electrode as the cam moves to the second position.

A developing cartridge includes: a casing; a developing roller; a developing electrode; a gear; a rack gear including a protrusion; and a cam having first and second cam surfaces. The rack gear meshes with the gear and is movable in a direction from one end toward another end of the casing. The cam is movable from a first position to a second position. The first cam surface of the cam at the first position contacts the protrusion, and causes the cam to move to the second position as the rack gear moves in the direction in a state where the first cam surface is in contact with the protrusion. A second cam surface moves the developing electrode in a direction away from the cam different from moving directions of the rack gear and the cam while contacting the developing electrode as the cam moves to the second position.

An image forming apparatus of the present disclosure includes a developing device and a toner storage container. The toner storage container is detachable and attachable with respect to an apparatus main body. The toner storage container includes a supply screw which conveys toner by rotating forward, and a first engagement unit coupled via a gear train to a rotation shaft of the supply screw. The apparatus main body includes a second engagement unit which engages with the first engagement unit to restrain detachment/attachment of the toner storage container by engaging with the first engagement unit. In a case where an amount of toner in the toner storage unit has become equal to or less than a predetermined amount, a control unit makes the supply screw rotate backward to thereby release engagement between the first and second engagement units.

An image forming apparatus includes a replenishment empty history recording portion, a post-empty attachment detecting portion, and an image creation restricting portion. The replenishment empty history recording portion records replenishment empty history information to a storage device in correspondence with one of the plurality of developer containers in which a replenishment empty state was detected in a first attachment portion. The post-empty attachment detecting portion detects whether or not a second attachment portion is in a post-empty container attached state where the developer container corresponding to the replenishment empty history information recorded in the storage device is attached to the second attachment portion. The image creation restricting portion, upon detection of the replenishment empty state, restricts an operation of an image creating device, and upon detection that the second attachment portion is in the post-empty container attached state, releases a restriction on the operation of the image creating device.

An image forming apparatus of the present disclosure includes a developing device and a toner storage container. The toner storage container is detachable and attachable with respect to an apparatus main body. The toner storage container includes a supply screw which conveys toner by rotating forward, and a first engagement unit coupled via a gear train to a rotation shaft of the supply screw. The apparatus main body includes a second engagement unit which engages with the first engagement unit to restrain detachment/attachment of the toner storage container by engaging with the first engagement unit. In a case where an amount of toner in the toner storage unit has become equal to or less than a predetermined amount, a control unit makes the supply screw rotate backward to thereby release engagement between the first and second engagement units.