Patent ID: 8836326
Filing Date: 2014-09-16
Classification: G01D,H02K

Abstract:
1. A rotation angle detection device that detects a rotation angle of a rotor, comprising: a multi-polar magnet that rotates with rotation of the rotor, and that has at least one magnetic pole having a first magnetic force and at least one magnetic pole having a second magnetic force; first, second and third magnetic sensors that respectively output first, second and third sinusoidal output signals having a predetermined phase difference with rotation of the multi-polar magnet; a zero-crossing detecting unit that detects timing of a zero-crossing of an output signal of at least one of the first, second and third magnetic sensors; and a magnetic pole identifying unit that, when the timing of the zero-crossing of the output signal of the one of the magnetic sensors has been detected by the zero-crossing detecting unit, identifies a magnetic pole, sensed by the first magnetic sensor, based on output signals of the other two magnetic sensors, wherein an arrangement pattern of the at least one magnetic pole having the first magnetic force and the at least one magnetic pole having the second magnetic force and the phase difference are set such that, when the timing of the zero-crossing of the output signal of the one of the magnetic sensors has been detected by the zero-crossing detecting unit, a combination of values of the output signals of the other two magnetic sensors differs among the magnetic poles sensed by the first magnetic sensor.