To provide a dynamic pressure bearing made of ceramics capable of preventing vibration and seizure from occurring during the rotation.
This dynamic pressure bearing 3 comprises a cylindrical bearing 5 and a main shaft 9 inserted in a through hole 7 in the axial direction of the bearing 5. The main shaft 9 is fixed so as not to be rotated and its bearing 5 side is rotated. The main shaft 9 is eccentrically disposed in the through hole 7. Accordingly, by the principle of the dynamic pressure bearing, the bearing 5 is rotated at high speeds in non-contact with the main shaft 9. The bearing 5 and the main shaft 9 are made of aluminum ceramics, and the surface roughnesses Sm of the rotating surfaces 5a and 9a thereof are set within the range of 5 to 50 μm.
YOGO TETSUJI
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