| 摘要 |
PURPOSE: To maintain a vibration resistance even in low speeds by arranging a radial dynamic pressure air bearing formed with the outer cylindrical surface of a rotating shaft and the inner cylindrical surface of a fixed cylinder on the radial outer peripheral side of a motor so as to increase the supporting force of a rotating body in radial direction. CONSTITUTION: Because a radial dynamic pressure air bearing 23 formed with the outer cylindrical surface 12 of a rotating shaft 13 and the inner cylindrical surface 5 of a fixed cylinder 6 is arranged on the radial outer side of a motor 19, the shaft diameter of the radial dynamic pressure air shaft 23 is increased so as to increase the peripheral speed of a baring surface. By this, unless a bearing clearance is reduced more than that required, air pressure in the bearing clearance can be increased. A vibration resistance can be maintained even at low speeds by increasing a supporting force of a rotating body 11 in radial direction. Also, because air remains in a clearance with a thrust dynamic pressure air bearing 27 with large plane area (a clearance between the thrust surface 25 of a cover 2 and a thrust plate 14) due to viscosity of air in its clearance, a higher vibration resistance can be maintained. |
