Patent ID: 8115479

Claim:
A rotation-angle-detecting apparatus comprising a magnet rotor having 4 or more magnetic poles on the surface, and first and second sensor devices for detecting the direction of magnetic flux from said magnet rotor; said first sensor device containing sensor bridges X 01 and Y 01 , in which the magnetization directions of pinned layers are perpendicular to each other; said second sensor device containing sensor bridges X 02 and Y 02 , in which the magnetization directions of pinned layers are perpendicular to each other; each sensor bridge X 01 , Y 01 , X 02 , Y 02 being a full bridge of spin-valve, giant-magnetoresistive devices each having a pinned layer and a free layer, the magnetization direction of said pinned layer being fixed, and the magnetization direction of said free layer rotating depending on a magnetic field direction; adjacent spin-valve, giant-magnetoresistive devices in said full bridge having pinned layers whose magnetization directions are antiparallel; said sensor bridges Y 01 and Y 02 being arranged such that the magnetization directions of their pinned layers are along the circumferential direction of said magnet rotor; said sensor bridges X 01 and X 02 being arranged such that the magnetization directions of their pinned layers have a phase difference of 90° or 90° ±180n° by electric angle, wherein n is an integer; and voltage being applied to said full bridges to obtain differential outputs each corresponding to an angle between the magnetization direction of said pinned layer and the magnetization direction of said free layer, and an angle signal being obtained based on said differential outputs.