Patent ID: 8280267

Claim:
An image forming apparatus comprising: a first image forming unit for forming a first developer image using first developer; a second image forming unit for forming a second developer image using second developer; a transfer unit disposed to contact with at least one of the first image forming unit and the second image forming unit for transferring at least one of the first developer image and the second developer image; a separation contacting unit for moving at least one of the first image forming unit and the second image forming unit to a first position contacting with the transfer unit and to a second position away from the transfer unit; a density measurement unit for measuring a first image density of the first developer image when the first image forming unit is situated at the first position and the second image forming unit is situated at the second position, and for measuring a second image density of the first developer image when the first image forming unit and the second image forming unit are situated at the first position; and a control unit for controlling the first image forming unit, the second image forming unit, the density measurement unit, and the separation contacting unit, said control unit including a density calculation unit for calculating a difference between the first image density and the second image density and a density correction unit for correcting a density of the first developer image according to the difference.