Patent ID: 6934061

Claim:
An optical scanner comprising a plurality of optical scanning systems with different scanned planes, and a light deflector used in common between said plurality of optical scanning systems, each optical scanning system including a light source for emitting a light beam, a focusing lens for guiding the light beam emitted from the light source onto the light deflector, and a scan lens for focusing the light beam deflected by the light deflector onto the associated scanned plane, wherein: said plurality of optical scanning systems comprises at least a pair of optical scanning systems arranged on both sides of the light deflector so that a first fast scan direction of one optical scanning system in which a first light beam deflected from the light deflector scans is parallel to a second fast scan direction of the other optical scanning system in which a second light beam deflected from the light deflector scans; a first reference reflecting position of said one optical scanning system located on the light deflector and a second reference reflecting position of said other optical scanning system located on the light deflector are asymmetric with respect to a reference plane that contains a rotational axis of the light deflector and extends parallel to the first and second fast scan directions; and the scan lens of said one optical scanning system and the scan lens of said other optical scanning system are arranged to be symmetric with respect to a line passing through a rotational center of the light deflector and extending parallel to the scanned planes.