Patent ID: 7693460

Claim:
An image forming apparatus which is operative in a monochrome mode in which a monochrome image is formed from a black developing agent image and in a color mode in which a color image is formed by superposing images of developing agents of different colors including black and non-black colors, the apparatus comprising: photosensitive members provided for the respective colors; developing rollers respectively provided in association with the photosensitive members in such a manner as to be brought into and out of contact with the corresponding photosensitive members, and adapted to supply the developing agents to the corresponding photosensitive members in contact with the corresponding photosensitive members to develop electrostatic latent images respectively formed on the photosensitive members into the developing agent images; a transfer belt disposed in opposed relation to the respective photosensitive members, and adapted to transfer the developing agent images respectively carried on the photosensitive members onto a transfer object; recovery members respectively provided in association with the photosensitive members, and adapted to recover parts of the developing agents remaining on the corresponding photosensitive members after the developing agent images are transferred onto the transfer object; a cleaning member which removes the developing agents from the transfer belt; a switching mechanism which selectively shifts the developing rollers among an all-color non-contact state in which all the photosensitive members are kept apart from the corresponding developing rollers, a black contact state in which the photosensitive member for black is kept in contact with the corresponding developing roller and the other photosensitive members are kept apart from the corresponding developing rollers, and an all-color contact state in which all the photosensitive members are kept in contact with the corresponding developing rollers; and a control section which, when an operation mode of the apparatus is shifted from the color mode to the monochrome mode, causes the switching mechanism to shift the developing rollers from the all-color contact state to the all-color non-contact state to perform a transferring process to once transfer the developing agents recovered on the respective recovery members onto the corresponding photosensitive members and further transfer the developing agents from the photosensitive members onto the transfer belt.