Patent ID: 8494387

Claim:
A color-image forming apparatus including a plurality of photosensitive members corresponding to individual colors, the photosensitive members being disposed along a moving direction of a transfer member to which images are to be transferred and rotating at a peripheral speed lower than the transfer member, and developers being brought into contact with and separated from the photosensitive members, the individual photosensitive members being brought into contact with the transfer member and the individual developers being brought into contact with the photosensitive members so that toner images are transferred to the transfer member in sequence, thereby performing image formation of an input job, the developers being separated from the photosensitive members along with completion of transfer of the toner images, the color-image forming apparatus comprising: a control unit configured, during forming of a toner image on the transfer member with a first photosensitive member, to increase the peripheral speed of a second photosensitive member that is not forming the toner image on the transfer member when full color image forming is started or before full color image forming is ended so that a load generated on the transfer member during forming of the toner image on the transfer member with part of the photosensitive members is at least similar in magnitude to a reference load generated between all the photosensitive members and the transfer member while all the photosensitive members, with which the developers are in contact, are forming toner images on the transfer member, wherein the load is at least similar in magnitude to the reference load so as to prevent driving torque fluctuations of the transfer member regardless of whether toner is supplied to a nip portion between the plurality of photosensitive members and the transfer member.