Patent ID: 7206537

Claim:
An image forming apparatus, comprising: a plurality of image bearing members having open end portions in an axial direction of the image bearing members and configured to bear toner images on surfaces of the image bearing members; a plurality of motors configured to rotate the plurality of image bearing members; an image receiving member configured to receive and overlay the toner images from the plurality of image bearing members facing a surface of the image receiving member, and move the overlaid toner images in a moving direction of the image receiving member; a plurality of position sensors configured to determine a rotational position of the plurality of image bearing members based on a primary reception time of a signal that comes immediately after a preceding signal when the plurality of position sensors receive the preceding signal at a start of a mark detecting operation; a plurality of motor controllers configured to control the motor based on a recognition result obtained by the position sensor and make the rotational position of a rotating member consistent with a target position at a predetermined time during the mark detecting operation performed by a mark sensor; a storing mechanism configured to store relative relationship data specifying a relative relationship of the rotational positions between the plurality of image bearing members to have a minimal degree of color displacements between the toner images overlaid on the surface of the image receiving member; and a control mechanism configured to control at least one of the plurality of motor controllers, and make relative relationships of the plurality of image bearing members have relative relationships based on the relative relationship data specifying the relative relationship stored in the storing mechanism after the rotational positions of the plurality of respective image bearing members are determined.