Body of revolution it was formed

摘要

PROBLEM TO BE SOLVED: To provide a rotation angle detection device for precisely detecting a rotation angle of a rotor between two grooves by multiply forming an excitation coil and changing an area where eddy currents are generated.;SOLUTION: The rotation angle detection device includes: a disc-shaped rotor 20; an excitation coil for generating eddy currents by applying alternate magnetic fields to a disc face of the rotor 20; and a detection coil for detecting a magnetic field generated due to the eddy currents generated on the disc face of the rotor 20. A plurality of grooves D are formed on the disc face of the rotor 20 with angular intervals in a rotation direction of the rotor, and the presence/absence of the grooves D is detected based on the change in the magnetic field detected via the detection coil so that a rotation angle between the two grooves D of the rotor 20 can be calculated. The excitation coil is configured by arranging a plurality of coils with different diameters to be individually conducted on a concentric circle in order to vary the area of the eddy currents generated in the rotor 20.;COPYRIGHT: (C)2012,JPO&INPIT