Patent ID: 8743434

Claim:
An image forming apparatus comprising: an image forming unit that forms multiple primary-color toner images of different primary colors on a surface of a single image carrier or forms primary-color toner images of different primary colors individually on surfaces of a plurality of image carriers; a transfer unit that brings a contact member into contact with any one of the single image carrier and the plurality of image carriers to create a transfer nip to transfer the multiple primary-color toner images formed on the single image carrier or the primary-color toner images individually formed on the surfaces of the plurality of image carriers on any one of a surface of the contact member and a recording sheet held on the surface of the contact member, thereby obtaining a toner image including a combined-color; and a control unit that controls driving operations of the image forming unit and the transfer unit and performs predetermined computations, wherein the control unit includes: an area searching unit that searches an image represented by an image information for a suitable color measurement area suitable for color measurement; a color measuring unit that performs color measurement on the combined-color toner image formed on the one of the contact member and the recording sheet based on the image information; and a deposition-amount detecting unit that measures a toner deposition amount per unit area on each of the primary-color toner images formed by the image forming unit, and the control unit is configured to perform, if the area searching unit has successfully found the suitable color measurement area, a color-reproduction-accuracy increasing process of adjusting a control parameter for the image forming unit so as to reduce a difference between a result of color measurement performed by the color measuring unit and a desired color to thereby increase combined-color reproduction accuracy, while, if the area searching unit has failed to find the suitable color measurement area, to perform a deposition-amount stabilizing process of causing the image forming unit to form a plurality of test primary-color toner images and adjusting a control parameter for the image forming unit so as to reduce a difference between a toner deposition amount on each of the test primary-color toner images measured by the deposition-amount detecting unit and a corresponding target deposition amount to thereby stabilize the toner deposition amount.