| 摘要 |
PURPOSE:To correct the axial center of a rotary shaft with high accuracy, by dividing a fixed magnetic pole into an even number of magnetic pole pieces to separate them into groups and detecting the change in capacity generated at lach group through the rotary shaft. CONSTITUTION:Magnetic pole pieces U1-U4, L1-L4 are arranged to the peripheral surface of a rotary shaft 2q at predetermined intervals to form electrostatic capacities C1-C4 between the magnetic poles opposed to each other and, when the center of the rotary shaft 21 composed of a dielectric body moves in an x-direction, displacement is detected on the basis of the change quantities of the capacities C1, C2. A bridge circuit is formed of two reference capacities C0 and the capacities C1, C2 and equilibrium is lost by the displacement of the axial center of the rotary shaft 21 to obtain the displacement signal 25a in the x-direction. In the same way, the displacement signal 29a in a y-direction is obtained. A control signal is outputted from a control circuit 31 by discriminating the displacement quantities in both directions to control coils K(K1-K4) and magnetic attraction force is changed to correct the displacement of the axial center of the rotary shaft 21.
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