US 6,639,616 B2 · Image forming apparatus and image forming method featuring image formation in two, different-speed modes

Abstract

An image forming apparatus is provided with photosensitive drums for forming latent images by irradiation of light reflected by a polygon mirror and a fixing device for fixing toner images corresponding to the latent images on a sheet material. Deterioration of an image to be formed is prevented if reflective surfaces of a reflective polyhedron are thinned out in reducing a process speed of image formation. This apparatus is further provided with a control unit for, if the number of surfaces of the polygon mirror is m (where m is an integer of three or more), performing a control for selecting n such that m/(n+1) is not an integer as a relation between m and n and performing a control for making n surfaces unused as a reflective surface of light among continuous n+1 surfaces of the reflective polyhedron in decelerating the image forming process.

Claims8

Dependent claims

An image forming apparatus comprising:

a movable image bearing member;
a light source;
a rotatable reflective polyhedron for reflecting light from said light source and performing light scanning of said image bearing member, wherein a plurality of light scannings are performed for a plurality of colors, respectively, in accordance with the following modes:
a first mode for forming an image on said image bearing member at a first speed;
and
a second mode for forming an image on said image bearing member at a second speed, which is 1/(n+1) of the first speed,
wherein at the time of performing the second mode, in each of said plurality of light scannings, when it is assumed that the number of reflective surfaces of said reflective polyhedron is m, m/(n+1) is not an integer (provided that m is an integer of three or more and n is a natural number.).

4 more elements

Dependencies are inferred from the claim text.

Image forming apparatus and image forming method featuring image formation in two, different-speed modes

Life of this patent

Image forming apparatus and image forming method featuring image formation in two, different-speed modes

Life of this patent

Abstract

Claims8