Abstract: The improved optical deflector includes a polygonal mirror to be rotated for deflecting an incident light beam for scanning purposes and a motor for rotating the polygonal mirror, and the rotating shaft of the motor is provided with a reference seat on which the polygonal mirror is to be mounted in close contact; the rotor of the motor is solely composed of a rotor magnet that is mounted on the rotating shaft, with the polygonal mirror being disposed between the reference seat of the rotating shaft and the rotor magnet; the rotor magnet is held in close contact with a plane of the polygonal mirror which is perpendicular to the rotating center axis thereof. Even if the optical deflecting element such as a polygonal mirror is rotated at high speed, the runout of the rotor of the motor is suppressed to a minimum without causing a deviation of the scanning light beam, thereby insuring efficient rotation of the deflecting element.

Abstract: The improved optical deflector including a rotating shaft that is supported freely rotatable around the body of a motor, as well as an optical deflecting element and a magnet that are both fitted around the rotating shaft is further provided with a turbulence forming member in the neighborhood of the rotating element which is composed of the rotating shaft, the optical deflecting element and the magnet. The air stream generated by the rotation of the optical deflecting element is transformed to turbulences so as to block the development of a "negative" pressure in the space between a stator coil base (fixed member) and the magnet (rotating member). Therefore, the grease can be prevented from splashing in the optical deflector that uses ball bearings; in the case where the optical deflector is of a type that uses a dynamic pressure spindle, the galling of the spindle can be prevented.

Abstract: An optical scanner that includes: a rotating polygon mirror for scanning by deflecting a light beam for writing a latent image on a photosensitive body in a predetermined direction; a rotating shaft that is inserted into a hole arranged on the rotating polygon mirror; and a filling agent containing particulates for filling a gap at a fitted portion between the rotating polygon mirror and the rotating shaft. The gap can be removed by filling the particulates at the fitted portion, thus ensuring stable high-speed rotation of the rotating polygon mirror free from dynamic balance errors.