Abstract: A movable table unit provided here has a simple structure but can increase the precision of detecting the displacement of a movable table, and comprises a quadrangle frame-shaped stationary base a movable table disposed inside the stationary base, spring members interposed between the movable table and the stationary base, and a piezoelectric element fixed to either the stationary base or the movable table and capable of expanding/contracting in the axis direction to exert either an expansion or contraction force on the other, to allow the movable table to move relative to the stationary base. A strain gauge is mounted in a strain occurrence site where strain occurs as the movable table moves, so that the amount of travel of the movable table is detected on the basis of the value detected by the strain gauge.

Abstract: A movable table unit provided here has a simple structure but can increase the precision of detecting the displacement of a movable table, and comprises a ring-shaped stationary base 1, a movable table 2 disposed inside the stationary base, spring members 3a to 3d interposed between the movable table and the stationary base, and a piezoelectric element 4 fixed to either the stationary base 1 or the movable table 2 and capable of expanding/contracting in the axis direction to exert either an expansion or contraction force on the other, to allow the movable table 2 to move relative to the stationary base 1.

Abstract: Onto a long rectangular board like base board, first Hall IC's are mounted at specified equal pitches in the longitudinal direction, and second Hall IC's are mounted at the equal pitches from a position shifted by a phase difference of 90 degrees in the longitudinal direction relative to this first Hall IC, and a single rectangular board like field magnet (12) having a length of a half of the equal pitch is mounted, opposite to the first Hall IC's and the second hole IC's, and consequently, a linear encoding device is provided, by which a long positional measurement can be performed, and further, which has a simple arrangement.