Patent ID: 7136600

Claim:
An image forming apparatus, comprising: a plurality of photoconductive elements arranged in a preselected direction; a plurality of developing means each for forming a toner image on a particular one of said photoconductive elements; a transfer belt for conveying along said photoconductive elements a transfer medium to which said toner images are to be transferred; a plurality of transferring means for transferring said toner images from said photoconductive elements to said transfer medium; and a controller that controls at least one development clutch, which connects said plurality of developing means to a system that transmits power of an electric motor, to be turned on to start driving all of said plurality of developing means at a predetermined timing, wherein the predetermined timing is after said photoconductive elements and said transfer belt have been driven, but before a developing timing of the photoconductive element which the transfer medium reaches first by a sum of a period of time necessary for said photoconductive element to move from a nip position for development to a contact position with said transfer belt and a period of time of coupling of at least one development clutch.