Patent ID: 6630659
Filing Date: 2003-10-07
Classification: G01D

Abstract:
A position transducer comprising:an encoder disc rigidly connected to a rotor of an electric motor rotatable about an axis, the encoder disc having an annular track for directly indicating an angular position of the encoder disc; detector means comprising at least two detector groups, each of the at least two detector groups arranged to read the annular track at a reading place and to produce position signals directly indicating the position of the encoder disc, the reading places of the at least two detector groups being substantially symmetrically oriented around the axis of the encoder disc; calculating means connected to each of the at least two detector groups for receiving the position signals and for independently of each other calculating values of the angular position of the encoder disc from the position signals received from each of the at least two detector groups; and adding or averaging means connected to the calculation means for adding or averaging the values of the angular position to give a corrected value indicating the angular position of the encoder disc whereby, through the adding or averaging operation, position misreadings caused by radial movements of the encoder disc are canceled out of the corrected value.