Patent ID: 8400096
Filing Date: 2013-03-19
Classification: G01D,H02K

Abstract:
1. A magnetic encoder characterized in comprising: a multipole magnet having a circular multipole magnetized surface in which magnetic N poles and S poles are formed in alternating fashion at equiangular intervals in a circumferential direction; and first to fourth magnetic detection units arranged in different angular positions in the circumferential direction of said multipole magnetized surface in order to detect changes in the magnetic field accompanying said rotation of the multipole magnet, wherein said first magnetic detection unit has an A-phase first magnetic detection element and a B-phase first magnetic detection element that are adjacently arranged so that sensing surfaces thereof face said multipole magnetized surface across a fixed gap, and output a sinusoidal A-phase signal and B-phase signal, respectively, which differ in phase by 90°, in accompaniment with the rotation of said multipole magnet; said second magnetic detection unit has an A-phase second magnetic detection element and a B-phase second magnetic detection element that are adjacently arranged so that sensing surfaces thereof face said multipole magnetized surface across a fixed gap, and output a sinusoidal A-phase signal and B-phase signal, respectively, which differ in phase by 90°, in accompaniment with the rotation of said multipole magnet; said third magnetic detection unit has an A-phase third magnetic detection element and a B-phase third magnetic detection element that are adjacently arranged so that sensing surfaces thereof face said multipole magnetized surface across a fixed gap, and output an A-phase reverse signal, which is the reverse phase of the A-phase signal, and B-phase reverse signal, which is the reverse phase of the B-phase signal, respectively, in accompaniment with the rotation of said multipole magnet; said fourth magnetic detection unit has an A-phase fourth magnetic detection element and a B-phase fourth magnetic detection element that are adjacently arranged so that sensing surfaces thereof face said multipole magnetized surface across a fixed gap, and output an A-phase reverse signal, which is the reverse phase of the A-phase signal, and B-phase reverse signal, which is the reverse phase of the B-phase signal, respectively, in accompaniment with the rotation of said multipole magnet; said A-phase second magnetic detection element and said B-phase second magnetic detection element of said second magnetic detection unit are arranged in an angular position about 180° apart from said A-phase first magnetic detection element and said B-phase first magnetic detection element of said first magnetic detection unit in terms of mechanical angle about a center of rotation of said multipole magnet; and said A-phase fourth magnetic detection element and said B-phase fourth magnetic detection element of said fourth magnetic detection unit are arranged in an angular position about 180° apart from said A-phase third magnetic detection element and said B-phase third magnetic detection element of said third magnetic detection unit in terms of mechanical angle about the center of rotation of said multipole magnet.