ELECTROSTATIC ENCODER

PURPOSE:To approximate a wave which is obtained from a detecting circuit to a sine wave by performing processing which decreases the largest higher harmonic component among higher harmonics in an electric signal obtained by a detecting circuit to zero. CONSTITUTION:A slider 2 is held on a scale 1 movably in parallel and patterns 3 and 4 are formed on the scale 1 and slider 2 in a lattice shape. A positive and a negative voltage are impressed to the pattern 3 on the scale 1 alternately and the electrostatic capacity by the electrostatic coupling between the patterns 3 and 4 is detected by a detecting circuit 6 and converted into an electric signal to find the relative displacement of the slider 2 from the scale 1. Then when the largest higher harmonic component except the fundamental wave in the electric signal obtained by the detecting circuit 6 is of (m)th order, the pitch of the pattern 4 on the slider 2 is given a period having a position difference (pi/m) from a period which is twice as large as the pitch of the pattern 3 on the scale 1.