Patent ID: 8614729
Filing Date: 2013-12-24
Classification: H04N

Abstract:
1. An image forming apparatus, comprising: a plurality of image forming units for forming a toner image, each image forming unit including: a phase difference detection unit for detecting a rotational phase difference of another rotating polygon mirror with respect to a rotational phase of the rotating polygon mirror set as a reference out of the rotating polygon mirrors provided in the respective image forming units using signals output by the optical sensors; a correction control unit for performing a phase correction process of changing a drive frequency of the driver for driving and rotating the rotating polygon mirror having a rotational phase difference judged not to coincide by a predetermined correction amount and driving the driver for a period corresponding to a specified clock number by a drive clock signal of the changed drive frequency if the rotational phase difference detected by the phase difference detection unit does not coincide with a reference rotational phase difference; and a correction amount adjusting unit for reducing the predetermined correction amount by a predetermined specified amount and causing the correction control unit to perform the phase correction process again if the rotational phase difference detected by the phase difference detection unit after the phase correction process is performed by the correction control unit does not coincide with the reference rotational phase difference; wherein the predetermined specified amount is an amount to reduce the predetermined correction amount by at least three-fourths, and the correction amount adjusting unit causes the correction control unit to perform the phase correction process again by using the reduced correction amount.