Patent ID: 8219004

Claim:
An image forming apparatus comprising: a black-color-purposed photoconductor for forming a black-color image; a plurality of full-color-purposed photoconductors for forming a full-color image together with the black-color-purposed photoconductor; a first drive section for driving to rotate the black-color-purposed photoconductor; a second drive section for driving to rotate the plurality of full-color-purposed photoconductors; a drive control section for controlling the first and the second drive sections, wherein each photoconductor constituting the black-color-purposed photoconductor and the plurality of full-color-purposed photoconductors is engaged to the first drive section or the second drive section with rotational phases thereof being matched with one another; the drive control section controls the first and the second drive sections so that the first drive section is activated to make the black-color-purposed photoconductor start rotating by a predetermined delay time after the second drive section is activated to make the plurality of full-color-purposed photoconductors start rotating; and the predetermined delay time is a predetermined time based on a time difference which is measured between a start time of the first drive section and that of the second drive section when the first and the second drive sections are activated at a target speed for forming the full-color image.