Patent ID: 7333758

Claim:
An image forming apparatus operable to select a first printing mode using a single color of toner or a second printing mode using at least two colors of toner, comprising a plurality of cartridges including: a first cartridge containing toner used in at least the first printing mode and second cartridges each containing toner used only in the second printing mode, each of the cartridges comprising an image former including a photo conductor adapted such that an electrostatic latent image is formed thereon and a developing member operable to develop the latent image as a visible toner image, an intermediate transfer belt, adapted such that the toner image is transferred thereon; a first transfer member, operable to bring the intermediate transfer belt into contact with the photo conductor in the first cartridge; a second transfer member, operable to bring the intermediate transfer belt into contact with the photo conductor in each of the second cartridges while the second printing mode is selected; a registration mark former, operable to form registration marks on the intermediate transfer belt when an adjustment mode is effected, each of the registration marks being indicative of a reference position of the toner image formed by the image former in each of the cartridges; a registration sensor, operable to detect a position of each of the registration marks; and a controller, operable to control the registration mark former to adjust a positional relationship between the registration marks associated with the first cartridge and one of the second cartridges based on the detected position, wherein the adjustment mode includes a first adjustment mode, in which the registration marks associated with the first cartridge and one of the second cartridges are formed; and a second adjustment mode, in which the registration marks associated with all of the cartridges are formed.