| 摘要 |
A coarse and fine adjustment device employs an assembly of three concentric shafts-a fine adjustment shaft, a drive shaft for moving an object supporting table, and a coarse adjustment shaft. A predetermined number of planetary balls are held by retaining surfaces provided by the respective shafts. The fine adjustment shaft is formed with an annular V-shaped groove. The balls are retained in the groove in engagement with the inclined surfaces thereof by inclined surfaces respectively provided on opposite sides of the balls by the drive and coarse adjustment shafts. The angle of engagement of the retaining surface provided by the drive shaft differs from the angle of engagement of the retaining surface of the coarse adjustment shaft.
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