Opto-electronic bachometer and position detector of an electric motor
 A device for determining the rotational speed and position of a rotor of an electric motor having at least one signal track arranged on the rotor includes at least one sensor located at a stator-side of the electric motor for scanning the signal track, and an evaluation circuit connected to the sensor, the sensor being sensitive to given stimuli of the signal track for alternatively adopting one of three different states which individually produce levels of different magnitude; the evaluation circuit including detectors responsive in accordance with the levels, for cutting off levels of given magnitude so that a recognition of the rotor position is derivable from a first and a second one of the three states, and the rotational speed is derivable from the third one of the three states. 
Heidelberger Druckmaschinen AG
H G G
H02P G01P G01P
inventional inventional inventional
Jurgen Helmut
Maass Meyer