Patent ID: 6198563
Filing Date: 2001-03-06
Classification: B41J,G02B

Abstract:
An optical scanning apparatus comprising:a light source unit configured to emit a light beam for optical scanning;an image-forming lens configured to produce a line image, elongated in a main-scanning direction, of the light beam from said light source unit;a beam deflector configured to cause the line image to be reflected by its deflecting and reflecting surface so as to produce a deflected light beam deflected at a constant angular velocity;a reflective optical system including a plurality of reflecting mirrors configured to reflect the deflected light beam incident on said reflective optical system a plurality of times; whereinreflecting surfaces of the plurality of reflecting mirrors are tilted with respect to a system axis of said optical scanning apparatus;said reflective optical system includes an image-forming mirror configured to converge the deflected light beam to form a beam spot configured to scan a scanned surface at a constant velocity wherein the number of reflections of the deflected light beam performed by said image-forming mirror is more than 1; andsaid image-forming mirror has a normal toroidal configuration obtained by rotating a curve drawn with a first radius on a sub-scanning plane, around an axis residing on the sub-scanning plane and parallel with sub-scanning direction, maintaining a second radius.