Patent ID: 7050948

Claim:
A method for the highly precise determination of the position of a mark pattern in a measured signal obtained by optical sensors for the detection of marks on a scale, wherein data supplied by the optical sensors with a minimized or extinguished measured signal are recorded and stored as a dark curve, the data of a normalized measured signal are recorded and stored as a reference curve, the data of the current measurement are recorded and are stored as a characteristic curve, and then the characteristic curve is purged of errors caused by the measuring instrument by comparison with the dark curve and/or the reference curve and/or is normalized, and the thus-treated characteristic curve is stored as the target curve, is hereby characterized in that marks are used for the labeling of the scale and the measured signal is evaluated by determining the points of intersection of the target curve with the intensity levels determined by the intensity values for intensity values of the target curve that can be given in advance, and forming a mean value representing the position of a mark pattern from the determined points of intersection or combining the determined intersection points into groups and then forming a mean value representing the position of a mark pattern for each group from the intersection points belonging thereto.