Abstract: A developing apparatus includes a first locking means for locking a first supplying lid disposed at a first supplying opening in a closing position, a second locking element for locking a second supplying lid of a second supplying opening in a closing position, and a lock release element for releasing only the second locking element when a detachable developer cartridge is used. The second locking element includes a concave portion formed on a peripheral wall of the second supplying opening and a lock piece disposed in the concave portion, and a hole formed at an edge of the second supplying lid. The lock piece engages the hole when the second supplying lid is closed, thereby the lid is locked. The lock release element includes a lid having a opening disposed at an upper surface of the developing apparatus and a hole disposed at the lock piece, and the detachable developer cartridge comprises a pair of lock release pieces.

Abstract: The developing device, which is capable of mixing developers with magnetic toners and capable of providing the developers having a uniform magnetic toner density to a photoconductor for a copying machine, the device having a developing tank which contains a roller composed of a sleeve and a magnetic body with the magnetic body being disposed inside of the sleeve concentrically and rotatably with respect to each other, the device also having a magnetic toner supply tank disposed adjacent to the developing tank for supplying the magnetic toners to the developing tank through a toner supply port, the developing device includes a unit coupled to the developing tank for controlling an amount of the developers to be supplied to the sleeve, and a unit disposed between the toner supply port and the control unit for scraping the developers from the sleeve.