Patent ID: 8346504

Claim:
A method for monitoring and eliminating sensor faults in a sensor ( 3 ) for detecting movement of an encoder with at least two sensor elements ( 6 , 7 ), wherein the sensor elements are arranged in a way offset relative to each other in a direction of movement of the encoder, the method comprising: converting output signals (S 1 , S 2 ) at outlets of the sensor elements ( 6 , 7 ) to a sensor output signal (S 5 ) that describes movement of the encoder; monitoring the output signals (S 1 , S 2 ) at least indirectly including producing at least two intermediate signals (S 1 *, S 2 *) in a computing stage ( 15 ) such that a frequency of the two intermediate signal depends on frequencies of the output signals (S 1 , S 2 ) produced by the at least two separate sensor elements ( 6 , 7 ), and the test circuit ( 14 ) tests the two intermediate signals (S 1 *, S 2 *) with regard to deviations, which are due to errors of the element output signals (S 1 ,S 2 ) and; and disabling or correcting the sensor output signal (S 5 ) when errors of the output signals ( 6 , 7 ) are detected wherein upon failure of the test circuit ( 14 ) to detect an edge of one of the two intermediate signals (S 1 *, S 2 *), the edges of the other of the two intermediate signals (S 1 *, S 2 *) are disabled until an edge of the one the two intermediate signals (S 1 *, S 2 *) appears again so that no edge is active in this period for producing the sensor output signal (S 5 ).