Patent ID: 7064537

Claim:
A rotation angle detecting device comprising: a rotating shaft; a fixed portion where a plurality of GMR devices are provided; a rotating portion for forming a magnetic field and rotating facing said fixed portion; and a Wheatstone bridge circuit formed by connecting said GMR devices; wherein, with the center of said rotating shaft as the point of origin, and imaginary axial lines perpendicularly intersecting at this point of origin as the X axis and Y axis, each of four blocks sectioned by said X axis and Y axis have provided therein a pair of GMR devices disposed parallel to said X axis or Y axis, and such that the GMR devices provided in one block are symmetrical across the point of origin with the GMR devices provided in another block facing the block across the point of origin; and wherein said Wheatstone bridge circuit has a resistance formed by serially connecting a GMR device provided at a position closer to said point of origin than the other GMR device within said one block and a GMR device provided at a position closer to said point of origin than the other GMR device within said other block, and a resistance formed by serially connecting a GMR device provided at a position farther from said point of origin than the other GMR device within said one block and a GMR device provided at a position farther from said point of origin than the other GMR device within said other block, with said resistances connected in parallel.