When a toner cartridge [A] is placed, the shutter [C] on the cartridge opens and then the toner transport port [B] also opens. When a toner cartridge [A] is removed, the shutter [C] on the cartridge closes and the toner transport port [B] also closes.
Each toner cartridge has a toner supply motor [D] that drives the agitator [E] and toner transport coils [F].