Patent ID: 7331247

Claim:
A relative rotational position detection apparatus for detecting a relative rotational position between first and second shafts rotatable relative to each other, the relative rotational position detection apparatus comprising: a first magnetic body section provided to rotate in intercoupled relation to rotation of the first shaft; a second magnetic body section provided to rotate in intercoupled relation to rotation of the second shaft, wherein said first magnetic body section and said second magnetic body section form at least two ring-shaped variable magnetic coupling sections opposed to each other via a gap, and a plurality of magnetic coupling boundary sections that form magnetic couplings, the magnetic coupling in each of the magnetic coupling boundary sections varying in response to variation of the relative rotational position between said first shaft and said second shaft, and variation of the magnetic coupling differing in phase between the boundary sections; and a coil section including detecting coils each provided in corresponding relation to one of the magnetic coupling boundary sections, wherein the first and second magnetic body sections each include magnetic teeth that differ in length, and wherein opposing teeth of the first and second magnetic body sections form the magnetic coupling boundary sections.