Patent ID: 7158160

Claim:
An image forming apparatus comprising: an optical beam scanning device forming the plurality of latent images; and an image writing control unit; wherein said optical beam scanning device forms one of the plurality of latent images, which are to be formed, with a plurality of light beams while forming the other latent images respectively by one light beam and includes: a plurality of light sources; a pre-deflection optical unit for providing predetermined characteristics for the plurality of light beams from the plurality of light sources; one light-deflection unit for deflecting, in a predetermined direction, light beam bundles from said pre-deflection unit, which light beam bundles form the plurality of latent images with one surface or an integrally processed surface; a post-deflection optical unit for causing the plurality of light beams deflection-scanned with the light-deflection unit to image on corresponding respective scanned surfaces, so that the plurality of latent images are formed; a horizontal synchronization unit which is on a position of an upstream side of scanning lines by a light beam, which light beam forms a latent image formed by the plurality of light beams, among the plurality of light beams passed through a part of the post-deflection optical unit and detects that the each light beam forming the latent image formed by the plurality of light beams reaches a predetermined position; and in an image forming mode, after said horizontal synchronization unit detects that, one of the plurality of light beams forming the latent image formed by the plurality of light beams reaches a predetermined position, said image writing control unit performs on-off control of said respective light sources for the detected light beam and for the each light beam forming one latent image by the one light beam in accordance with image data after a predetermined time period defined by a registration correction information at that time elapses.