Abstract: A toner cartridge stored in a developer casing includes a biasing force generating device, an actuating rod that switches the biasing device between an active state and a non-active state by one movement of a release member. A developer casing swings by the movement of the actuating rod and presses a developing roller with appropriate pressure to a photosensitive drum. There is a lock member that is restrained from moving by the movement of the actuating rod. The structure recited is capable of inserting and fixing the developer casing to an image forming device. Also, by one restore movement of the release member, the photosensitive drum and the developing roller are separated and the lock is released, thereby enabling removal/exchange of the developer casing.

Abstract: A toner cartridge stored in a developer casing comprises a biasing force generating means 7, an actuating rod 11 that switches the biasing means 7 between an active state and a non-active state by one movement of a release member 13, a developer casing that swings by the movement of the actuating rod and presses a developing roller with appropriate pressure to a photosensitive drum, and a lock member 15 that is restrained from moving by the movement of the actuating rod; the above-mentioned members capable of inserting and fixing the developer casing to an image forming device, and by one restore movement of the release member 13, the photosensitive drum and the developing roller are separated and the lock is released, thereby enabling removal/exchange of the developer casing (toner cartridge).