ROTATION ANGLE DETECTION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive small-sized rotation angle detection device capable of measuring the rotation angle in the range of 360 degrees. SOLUTION: A permanent magnet 2 is mounted on a rotating shaft 3, and generates a main magnetic field MF. A coil 5 generates an auxiliary magnetic field SF. The main magnetic field MF is rotated relative to the auxiliary magnetic field SF following rotation of the rotating shaft 3. Two magnetic resistance sensors are arranged in a sensor unit 4 so as to output electric signals having the phase difference of 45 degrees mutually. The main magnetic field operates both magnetic resistance sensors of the sensor unit 4 in a saturated region regardless of the rotation angle of the rotating shaft 3. Each magnetic resistance sensor outputs an electric signal of a level corresponding to the direction of the magnetic field regardless of the intensity of the magnetic field in the saturated region. A composite magnetic field formed by the main magnetic field and the auxiliary magnetic field forms the saturated region at the angle at which one magnetic resistance sensor outputs the maximum level, and forms an unsaturated region at the opposite angle by 180 degrees. The level of an electric signal outputted from each magnetic resistance sensor in the unsaturated region is lower than the level outputted in the saturated region. COPYRIGHT: (C)2005,JPO&NCIPI