An imaging system includes a rotatable image carrier; a rotatable developer carrier, a storage container, and an air flow generator. The developer carrier transfers toner to the image carrier at a developing region located between the image carrier and the developer carrier. The storage container stores the developer carrier. The air flow generator is separated from the storage container by a gap, and rotates in a rotational direction that is opposite to a rotational direction of the developer carrier, to channel an air flow through the gap when the air flow generator rotates.

An imaging system includes a developing chamber, a first conveyance path, a second conveyance path, a first air passage and a second air passage. A developing roller located in the developing chamber carries a developer to a developing region where the developing roller is closest to an image carrier. A first stirring-conveying portion is located in the first conveyance path adjacent the developing roller to supply the developer to the developing roller. A second stirring-conveying portion is located in the second conveyance path adjacent the first conveyance path to circulate the developer between the second conveyance path and the first conveyance path. The first air passage has an inlet coupled to the developing chamber and an outlet coupled to the second conveyance path, and the second air passage has an inlet coupled to the second conveyance path and an outlet coupled to the developing chamber.

An image forming apparatus includes a photosensitive member, a charging member, an exposure unit, a developing unit including a developing member, a motor, a contact and separation unit, a controller, an acquiring portion for acquiring information on a switching time which is a time required for switching a state of the developing member from a separated state to a contact state by executing a contact operation by the contact and separation unit, and a setting portion for setting, on the basis of the information on the switching time acquired by the acquiring portion, a start timing which is a timing when the contact operation by the contact and separation unit is started in a preparation operation and which is a timing before a region on the photosensitive member exposed to light in a light emission period reaches a developing position.

A photosensitive drum is rotatably supported in a main body. A developing cartridge is detachably mountable on the main body in a state where the photosensitive drum is supported in the main body. The developing cartridge includes a developing device and a frame. The developing device includes a developing roller disposed in confrontation with the photosensitive drum to supply developer to the photosensitive drum when the developing cartridge is mounted in the main body, and a developer-accommodating portion configured to accommodate developer. The frame includes a waste-developer-accommodating portion configured to accommodate waste developer and supports the developing device that is movable relative to the frame. The frame is disposed on an opposite side of the developing roller from the photosensitive drum. An urging member is disposed between the frame and the developing device to urge the developing roller toward the photosensitive drum.

An imaging system includes: a housing including a developing chamber, a developing roller located in the developing chamber to transport a developer and spaced apart from the housing; a conveyance path extending along at least part of a periphery of the developing roller in order to form a flow of air including the developer; and a control member. The developing roller includes a peeling pole at a fixed position with respect to the housing, to discharge the developer. The control member is located along the conveyance path in proximity to the peeling pole of the developing roller, to reduce a flow rate of the air flowing through the conveyance path.

A toner includes a crystalline polyester resin and an amorphous polyester resin. A ratio of the storage modulus of the toner G′ (T.sub.O) at a temperature T.sub.O to the storage modulus of the toner G′ (T.sub.O+3) at a temperature T.sub.O+3 is greater than or equal to 10, in a case where the temperature T.sub.O is within a range from 50° C. to 65° C.

A controller is configured to, when forming an image on one sheet, in a case where a length of one sheet in a conveyance direction is larger than a first length, drive a moving mechanism to move a plurality of developing rollers from a separation position to a contact position, temporarily stop driving of the moving mechanism, and then, at a first timing, again drive the moving mechanism to move the plurality of developing rollers from the contact position to the separation position; and in a case where the length of the one sheet in the conveyance direction is smaller than or equal to the first length, drive the moving mechanism to move the plurality of developing rollers from the separation position to the contact position and then to move the plurality of developing rollers from the contact position to the separation position without stopping driving of the moving mechanism.

A developing device includes a developing unit including a developer bearing member and a developing frame member configured to support the developer bearing member. The developing unit is supported to be pivotable about a first shaft and a second shaft. A biasing member configured to bias the first shaft is provided.

An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference in density information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

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.