Photoelectric measurement of degree and sense of motion - using stationary and moving illuminated grids and three transducers producing signals with phases of 0, 90 and minus 90 degrees

摘要

The photoelectric arrangement determines both degree and sense of movement of an object connected to a first grid w.r.t. a second grid. It uses a light source illuminating both grids and three photoelectric transducers producing periodic output signals with three difference phases. A circuit forms difference signals for evaluation from the transducer outputs. Smaller phase differences than currently used are employed to minimise measurement errors. Phase angle of - phi/2, o and phi/2 radians are used. The two differences between the - phi/2 and o, and the o and + phi/2 radian phase angle signals are formed.