US Patent 6909280 Inductive position detector

The invention relates to an inductive position detector (1) comprising a first member (9) having a longitudinal axis and an element of magnetic material extending in the direction of the longitudinal axis and having a periodically varying dimension in a direction perpendicular to the longitudinal axis, and a second member (10) movable relatively to the first member along the longitudinal axis and comprising means to induce a magnetic field in the element. The position detector analyses characteristic variations in the magnetic field to determine the position of the first member relative to the second member.