Patent ID: 7215904

Claim:
An image forming apparatus group for controlling first and second image forming apparatuses having different process speeds, said image forming apparatus group comprising: an image bearing member; a developer carrying member configured and positioned to develop an electrostatic latent image formed on said image bearing member using a developer and to receive a voltage comprising an A.C. voltage; and a developer container configured to contain the developer, wherein a cartridge including said developer carrying member and said developer container is provided detachably and commonly mountable to a main body of the first image forming apparatus and a main body of the second image forming apparatus, and wherein said image forming apparatus group increases the difference between a peak-to-peak voltage of the A.C. voltage in the main body of the first image forming apparatus, and a peak-to-peak voltage of the A.C. voltage in the main body of the second image forming apparatus as an amount of consumption of developer in the cartridge increases.