CPC G03G 15/5025 (2013.01) [G03G 15/01 (2013.01)] | 17 Claims |
1. A control device for controlling a rotation of a plurality of rotatable image bearers corresponding to different colors respectively, the control device comprising circuitry configured to:
receive a density of a toner image formed on each of the plurality of image bearers, the density detected by a toner density sensor;
receive a rotation phase of each of the plurality of image bearers relative to a rotation origin of the each of the plurality of the image bearers, the rotation phase detected by a rotation-phase detector;
determine a first density unevenness of the toner image occurring according to a rotation of a first image bearer for a first color among the plurality of rotatable image bearers, based on the rotation phase of the first image bearer relative to the rotation origin and a variation in the density of the toner image formed on the first image bearer;
determine a second density unevenness of the toner image occurring according to a rotation of a second image bearer for a second color among the plurality of image bearers, based on the rotation phase of the second image bearer relative to the rotation origin and a variation in the density of the toner image formed on the second image bearer;
correct the rotation phase of the first image bearer based on the first density unevenness and a rotation speed of the first image bearer;
correct the rotation phase of the second image bearer based on the second density unevenness and a rotation speed of the second image bearer;
control the rotation speeds of the first image bearer and the second image bearer to be a specified rotation speed; and
start detecting the rotation phase of each of the plurality of image bearers after a difference between each of the rotation speeds of the first image bearer and the second image bearer and the specified rotation speed falls within a specified range.
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