PURPOSE: To improve detection accuracy for a reference position by eliminating a distortion in magnetic field intensity generated on a magnetized surface of a magnetized body.
CONSTITUTION: A magnetized surface 4A where different magnetic poles are alternately magnetized is provided in the outer periphery of an upper disk 3A, while a reference position 5 where a magnetizing interval is made longer is provided on the magnetized surface 4A. A lower disk 3B is joined to the upper disk 3A, while a magnetized surface 4B where different magnetic poles from those on the upper disk 3A are magnetized is provided in the outer periphery of the lower disk 3B. A position sensor 6 comprises MR elements, while the MR elements are placed in the vicinity of a joining face between the upper disk 3A and the lower disk 3B. A signal processing circuit 7 shapes a waveform of an output signal from the position sensor 6, generating a reference position signal.
NATSUME TETSUSHI
MAKINO YASUAKI
