Patent ID: 8229310

Claim:
An image forming device provided with a full-color image formation mode to form a color image using a plurality of color photoconductor drums and a monochrome image formation mode to form a monochrome image using a single photoconductor drum, the image forming device comprising: a driving unit to drive rotation of an intermediate transfer belt or a transfer transport belt; a control unit to change rotational speeds of the plurality of color photoconductor drums in a transition from the full-color image formation mode to the monochrome image formation mode to make a torque to the driving unit in the full-color image formation mode equal to a torque to the driving unit in the monochrome image formation mode; and a separator unit to separate the plurality of color photoconductor drums from the intermediate transfer belt or the transfer transport belt after the rotational speeds of the plurality of color photoconductor drums are changed by the control unit.