Optical deflector of air bearing type

摘要

An optical deflector of an air bearing type has a fixed shaft; a rotary shaft having a hollow portion fitted onto the fixed shaft; a support device disposed between an end portion of the fixed shaft and an end portion of the hollow portion opposite thereto and supporting the rotary shaft in an axial direction thereof; a radial air bearing formed between an inner circumferential face of the hollow portion and an outer circumferential face of the fixed shaft; a polygon mirror fixed to the rotary shaft; a driving device for rotating the rotary shaft; a device for deflecting light irradiated onto the polygon mirror by rotating the rotary shaft through the driving device; a device for forming a flange for fixing the polygon mirror thereto integrally with the rotary shaft; and a device for setting an upper end portion of the support device on a fixed shaft side thereof to be lower than an upper end face of the polygon mirror. The support device has a first magnet directly attached onto an end face of the fixed shaft, a second magnet opposite to the first magnet and attached to the hollow portion of the rotary shaft, and a third magnet opposite to the second magnet and attached to a casing for covering the polygon mirror. Magnetic poles of the first, second and third magnets are opposite to each other to generate magnetic repulsive force.