| 摘要 |
PURPOSE:To improve an accuracy in position control by building an axially symmetric thrust generator in an air bearing. CONSTITUTION:A moving element 1 of a drive mechanism for manufacture of semiconductor and other purposes is movable axially of a guide shaft 2 with a circular section, a bearing housing 7 of said element is fitted with a plurality of coils 5a-5c so that said coils are wound around the shaft 2, and an air intake 6 is also formed therein. If compressed air is injected from said air intake 6, pressure is generated between the housing 7 and shaft 2 and the whole moving element 1 comes free of said shaft 2. Then, if a sinusoidal current with phases deviated 60 deg. from each other are caused to flow through the coils 5a-5c, a shifting field is generated in said coils and an induced current flows through the shaft 2; then, the moving element 1 moves axially. In this case, a generated heat of coil when moving, is cooled by an airflow in the air bearing so that the coil is protected from damage. Further, a stage 10 is placed on an upper face of the housing 7 and an electrostatic chuck 11 for absorption of a wafer 12 is put thereon.
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