US Patent 7260342 Image-forming apparatus

An image-forming apparatus that includes a drum cartridge, a developer cartridge, a coupling mechanism for interlocking the drum cartridge and the developer cartridge, a releasing cam for releasing the interlock provided by the coupling mechanism, and a toner accommodating chamber for accommodating toner. When the amount of toner accommodated in the toner accommodating chamber is greater than or equal to a prescribed amount, the drum cartridge and the developer cartridge are interlocked by the coupling mechanism. When the amount of toner drops below the prescribed amount so that the chamber is empty, the releasing cam releases the interlock provided by the coupling mechanism.