Patent ID: 7248185

Claim:
A sensor comprising: at least one rotary magnetic coder comprising a first circular magnetic track formed by a series of generator elements of a variable magnetic field, distributed so as to form N 1 element pairs with a specified period T 1 , and a second circular magnetic track formed by a series of generator elements of a variable magnetic field, distributed so as to form N 2 element pairs with a specified period T 2 , at least one of the magnetic tracks having at least one singular pole P S with at least one pair of singular generator elements with a spacing pitch different from the spacing pitch of the other generator elements of the track, at least two detection cells, each of said cells placed in relation to one said magnetic track and each delivering an electrical signal corresponding to changes in intensity of magnetic field, the detection cells or the magnetic tracks being offset from each other to allow the production of two de-phased digital signals, and logical resources for processing of digital signals delivered by the cells, said logical resources delivering a digital output signal with, a regular coding part S 1 having an alternating succession of high levels and low levels corresponding to a specified cyclic ratio R 1 and an irregular coding part S 2 with at least one high level and one low level corresponding to a specified cyclic ratio R 2 , wherein at least the detection cell located in relation to the magnetic track with a singular pole P S is a single-element detection cell, and the generator elements of the magnetic tracks and the detection cells are arranged in dependence on the logical processing resources, such that the digital output signal has a constant period, both on the regular coding part S 1 and on the irregular coding part S 2 , the regular coding part S 1 and the irregular coding part S 2 having cyclic ratios R 1 , and R 2 that are unbalanced and different from each other.