Patent ID: 7292806

Claim:
An image forming apparatus for forming monochromatic images only with toner of a specific color, said apparatus comprising: a latent image carrier capable of carrying thereon an electrostatic latent image; a developing unit having a plurality of cartridges each of which is freely mounted to and removed from said developing unit and contains the toner of the specific color; and a controller which performs a printing operation to selectively position one of the cartridges mounted to said developing unit at a development position and to develop the electrostatic latent image on said latent image carrier using the toner in the cartridge positioned at the development position, wherein said controller conducts a print preparatory operation only on a priority cartridge, the print preparatory operation conducted on the cartridge prior to the printing operation in order to enable the printing operation by means of the cartridge, one of the cartridges mounted to said developing unit defined as the priority cartridge.