Image forming apparatus with multiple light sources timing control

摘要

An image forming apparatus includes first and second photosensitive members; first and second light sources; a rotatable polygonal mirror; a first signal output portion; and a second signal output portion. The first light source emits the light at timing on the basis of the first signal, and the second light source emits the light at timing on the basis of the second signal so that latent images are formed on the first and second photosensitive members, respectively, and then are developed with developers to form developer images on the first and second photosensitive members, respectively, and then an image is formed by superposing the developer images. Before output of a second signal from the second signal output portion is started, the first light source emits the light on the basis of a first signal to start formation of the latent image on the first photosensitive member.

主权项

1. An image forming apparatus for starting image formation on the basis of a print command, comprising:
first and second light sources each for emitting light according to image data; a rotatable polygonal mirror including a plurality of reflecting facets, wherein said rotatable polygonal mirror deflects the light emitted from said first light source toward a first photosensitive member and deflects the light emitted from said second light source toward a second photosensitive member; a first signal output unit for outputting a first signal by receiving, in a predetermined position, the light emitted from said first light source and deflected by said rotatable polygonal mirror; and a second signal output unit for outputting a second signal at timing on the basis of the first signal and a correction value, wherein the correction value is set for each reflecting facet of said rotatable polygonal mirror, wherein said first light source emits the light according to the image data based on a time when the first signal is outputted and said second light source emits the light according to the image data based on a time when the second signal is outputted so that latent images are formed on the first and second photosensitive members, respectively, wherein said second signal output unit starts the output of the second signal after a lapse of a predetermined period from start of the output of the first signal by said first signal output unit after said image forming apparatus receives the print command, and wherein after said image forming apparatus receives the print command and before the output of the second signal is started, said first light source starts light emission according to the image data.