Measuring position of movable body - using two sinusoidal signals with phase difference of 90 deg. derived from measuring elements

摘要

A number of wave signals corresp. to the amt. of movement of the body is periodically picked-up from a number of measuring elements. These wave siganls are multiplied by sine and consine coeffts. based on the phase differences between the wave signals A num of the values of the products multiplied by the sine coeffts. and a sum of values of the products multiplied by the cosine coeffts. are formed so that both sinusoidal signals can be produced from the sums. The positioning measuring appts. pref. consists of a cylindrical housing (10) open only at its lower side and of metal, e.g. aluminium. A bead-shaped bearing (100) mainly of copper is located in the centre of the upper surface for a rotatable metal shaft (102). A rotor (103) is fixed at right angles to the latter. A circular, multiple magnet (1) is fixed at the outer circumference of the rotor. A circuit plate (104) faces in rotor in parallel. An arrangement (21) of Hall elements detects magnetic flux in a direction vertical to the circuit plate. ADVANTAGE - Higher accuracy.