Image forming apparatus that adopts image density control with density sensors

An image forming apparatus comprising:

• a plurality of image carriers each configured to have a toner image formed thereon while rotating;
• a transfer member configured to be conveyed in a conveying direction while being in contact with said plurality of rotating image carriers;
• a plurality of transfer units configured to transfer the toner images formed on said plurality of image carriers in a superposed manner on a surface of said transfer member;
• a correction unit configured to form toner images for detection on said image carriers, and correct image forming conditions based on an amount of toner by reading the toner images for detection transferred to said transfer member by said plurality of transfer units;
• a first reading unit configured to be disposed upstream of said plurality of transfer units in the conveying direction of said transfer member, and read the surface of said transfer member being conveyed in the conveying direction;
• a plurality of second reading units configured to be disposed downstream of respective ones of said plurality of transfer units in the conveying direction of said transfer member, and read the surface of said transfer member being conveyed in the conveying direction;
• a storage unit configured to store outputs from said first reading unit as a first profile, and store outputs from said plurality of second reading units as a second profile;
• and
• a toner density calculation unit configured to calculate toner densities of the toner images for detection based on the first profile and the second profile stored in said storage unit,
• wherein said correction unit corrects image forming conditions based on the toner densities calculated by said toner density calculation unit.