Patent ID: 8823367

Claim:
A rotation angle detection apparatus comprising: a detection target; an incremental detection unit; an absolute position detection unit, wherein the detection target has an incremental disk and an absolute position encoding disk, the incremental disk being coaxially mounted on a rotation shaft of a measurement target and having an n-time repetitive regular pattern, and the absolute position encoding disk being mounted coaxial to the incremental disk and having an irregular cyclic code comprising a binary random number sequence having an n-bit maximum length, the incremental detection unit is placed opposite to the incremental disk, and the absolute position detection unit is placed opposite to the absolute position encoding disk; a memory that stores a plurality of correction parameters respectively corresponding to a plurality of detection targets, wherein each detection target of the plurality of detection targets has a different repetitive data size n and a different curvature; and a calculating unit for calculating a rotation angle of the measurement target, wherein the calculating unit uses a selected correction parameter from the plurality of stored correction parameters, wherein the selected correction parameter is selected according to the repetitive data size n, and wherein the calculating unit bases the calculating of the rotation angle of the measurement target on detection data obtained by the incremental detection unit and detection data obtained by the absolute position detection unit.