Patent ID: 7209273
Filing Date: 2007-04-24
Classification: H04N

Abstract:
1. An image forming apparatus which comprises: image forming units of a plurality of colors, each of which has an image carrier and a light beam scanning unit for deflecting an emitted laser beam using a rotating polygonal mirror to form an electrostatic latent image on the image carrier, and forms a color image by overlapping images formed by the image forming units; a first control device which performs velocity control of rotation of the rotating polygonal mirror in a first image forming unit of the image forming units, for starting forming an image first; a second control device which controls rotation of the rotating polygonal mirror in a second image forming unit by performing velocity control and phase control; and a control signal generation device which, when a rotational velocity of the rotating polygonal mirror in the first image forming unit reaches a predetermined velocity, generates a rotation reference signal based on driving information of the rotating polygonal mirror in the first image forming unit or detection information of the laser beam deflected by the rotating polygonal mirror, wherein the second control device starts, based on the rotation reference signal generated by the control signal generation device, phase control to lock a rotational phase of the rotating polygonal mirror in the second image forming unit with a rotational phase of the rotating polygonal mirror in the first image forming unit.