| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized movement mechanism showing a higher accuracy and smaller oscillation than that of the prior art in regard to a motion of long stroke and a height measurement instrument using the movement mechanism.SOLUTION: This movement mechanism includes a movement shaft 1 of column having a central axis 10 in a Z direction that is movably held in the Z-direction and two retention mechanisms 2 and 3 spaced apart in the Z-direction. Each of the retention mechanisms 2 and 3 respectively has three ball bearings 4, 5, 6 and 7, 8 each of which fixes a mandrel 11 at its center, and holds a plurality of balls 14 between an inner ring 12 and an outer ring 13 so that the outer ring 13 is rotatable. A central axis 20 of the mandrel 11 is perpendicular to the central axis 10, the first ball bearings 4 and 7 are set in such a way that the outer ring 13 is contacted with the outer peripheral surface of the movement shaft 1 so as to press against its contact points 21 and 22 in a -X direction. |
