| 摘要 |
PROBLEM TO BE SOLVED: To prevent the wear of the thrust plate, etc., of a dynamic pressure oil bearing. SOLUTION: A shaft 2 which rotates integrally with a rotary polyhedral mirror 1 fits to a sleeve 3. The bottom end 2a of this shaft 2 is supported on the thrust plate 6. Oil B1 is packed into the microspacing between the shaft 2 and the sleeve 3 and the closed space A1 between the shaft 2 and the thrust plate 6. The dynamic pressure generation grooves 2c on the lower side of two sets of herringbone-shaped dynamic pressure generation grooves 2b, 2c disposed at the shaft 2 have vertically asymmetric groove patterns across the apexes of the herringbones. As a result, the pressure of the oil B1 in the closed space A1 is kept at P0 higher than the pressure of the outdoor air and the buoyancy to float the bottom end 2a of the shaft 2 from the thrust plate 6 may be obtd. |
