Patent ID: 6847309

Claim:
An encoder for a position sensor, the encoder being of the type comprising a multipole magnetic ring provided on its circumference with alternating north poles and south poles for traveling past a measurement cell that delivers a periodic signal corresponding to variation in the intensity of the magnetic field delivered by the poles, at least one of said poles of a determined sign being an “irregular” pole and comprising between the two opposite-sign poles adjacent thereto, firstly a spacing that is different from the spacing pitch between the other poles, and secondly means for correcting the value of its magnetic field so that the magnetic signal delivered by the passage of the poles adjacent to said irregular pole is symmetrical about the null value of the magnetic field; wherein the correction means are made by defining at least the area of the irregular pole which is surrounded by a link pole between the adjacent poles and of the same sign as the adjacent poles, so that the component of the magnetic signal that is perpendicular to the surface of the encoder and that is generated during the passage of the poles adjacent to said irregular pole does not include a point of inflection.