| 摘要 |
PURPOSE:To suppress the temp. rise in the polygonal scanner and to improve the reliability thereof by providing an insertion shaft part on a pedestal to be inserted into a stationary shaft formed to a cylindrical shape and forming this pedestal of a blank material having the better thermal conductivity than the thermal conductivity of the stationary shaft. CONSTITUTION:The stationary shaft 23 is a cylindrical member having grooves 23a for generating a dynamic pressure formed at equal intervals in the outer peripheral surface part and consists of a stainless steel or ceramics. The stationary shaft pedestal 22 consists of a flat plate part 22a fixed to a housing and the insertion shaft part 22b inserted into the stationary shaft 23. The flat plate part 22a and insertion shaft part 22b consist of a blank material having the better thermal conductivity than the thermal conductivity of the cylindrical stationary shaft 23, for example, aluminum or its alloy, brass, iron or ceramics. Namely, the stationary shaft pedestal 22 is so formed as to rapidly radiate the heat around the stationary shaft 23. A heat radiating fin 21a to assist the heat radiation is formed in the housing 21 as well. The heat from a rotating body, etc., is rapidly radiated to the outside in this way without impairing the bearing characteristics of the dynamic pressure air bearing, by which the abnormal temp. rise is prevented and the reliability is enhanced. |
