Patent ID: 7184185

Claim:
An image-forming device comprising: a polygon mirror rotatable about a rotational axis extending in a subscanning direction, the polygon mirror having a plurality of reflecting surfaces; a plurality of light sources that is aligned in the subscanning direction and irradiates a plurality of light beams onto one of the reflecting surfaces of the polygon mirror so as to be obliquely incident thereon; a plurality of optical reflecting systems each including at least one optical reflecting element, the optical reflecting systems being disposed in one-to-one correspondence with the light sources, thereby defining a plurality of optical paths for the light beams, each optical reflecting system receiving a light beam reflected off the one of the reflecting surfaces of the polygon mirror; a plurality of image-carrying portions on which the light beams traveling along corresponding optical paths form latent images by scanning the respective image-carrying portions; and one or a plurality of mixture preventing elements, each preventing a corresponding light beam from mixing in optical paths for another light beams.