Magnetic encoder

A magnetic encoder comprising:

• a disk shaped, rotary encoder element (2) including one or more magnetized elements that in use is fixed to a backing member (12), the one or more elements together defining first and second tracks (3, 4) of encoder regions in which the first track (3) is located concentrically around the second track (4), each region comprising a magnetic pole, the poles along each track (3, 4) being arranged as an alternating pattern of North and South poles, the poles of the first track (3) extending to the edge of the encoder element (2) to give a perimeter that at least partially extends around a circular path of radius r, and
• at least one sensor (5, 6) fixed in a location relative to which the location of the magnetized elements of the tracks (3, 4) are to be determined;
• wherein the magnetic encoder includes at least one feature for simultaneously providing a location for a mechanical fixing (13) that secures the magnetized elements relative to the moving part and that contributes to a periodic variation along the first track (3) of the magnetic field emitted by the first track (3) that is detected by the sensing elements associated with the first track (3) which at least partially cancels out a corresponding periodic variation in field from the other tracks that is also detected by the sensing elements associated with the first track (3), the at least one feature comprising an outermost edge of the poles of the first track (3) that each extends in a straight line forming a chord to the path r.