Small size magnetic encoder unit with low power consumption
A magnetic encoder unit with a small size and low power consumption is provided which can detect an angle in not more than one-turn and an amount of multi-turn. The magnetic encoder unit includes a permanent magnet 2 magnetized in a direction perpendicular to a rotation axis of a rotating member 1 and fixed to the rotating member 1 , a magnetic field detecting element 4 fixed to a fixed member 3 so as to be opposite to the permanent magnet 2 with a gap therebetween, and a signal processing circuit 5 processing a signal from the magnetic field detecting element 4 . Here, multi-turn detecting means including a multi-turn magnetic field detecting element 6 and a multi-turn signal processing circuit 7 detecting an amount of multi-turn from a signal of the multi-turn magnetic field detecting element 6 is added thereto.
1. A magnetic encoder unit comprising:
a permanent magnet magnetized in a direction perpendicular to a rotation axis of a rotating member and fixed to the rotating member,
a magnetic field detecting element fixed to a fixed member so as to be opposite to the permanent magnet with a gap therebetween, and
a signal processing circuit processing a signal from the magnetic field detecting element, wherein
the magnetic field detecting element includes at least two one-turn magnetic field detecting elements detecting an angle in not more than one-turn and at least two multi-turn magnetic field detecting elements detecting an amount of multi-turn, and
the signal processing circuit includes a one-turn signal processing circuit generating a not more than one-turn angle signal from detection signals from the one-turn magnetic field detecting elements and a multi-turn signal processing circuit generating a multi-turn signal from detection signals of the multi-turn magnetic field detecting elements.
2. The magnetic encoder unit according to claim 1 , wherein
the permanent magnet has a ring shape,
a ring-shaped magnetic yoke is formed around the permanent magnet, and
the fixed member is disposed inside the rotating member.
3. The magnetic encoder unit according to claim 2 , wherein
the fixed member has a ring shape and is formed of a ferromagnetic substance.
4. The magnetic encoder unit according to claim 1 , wherein
the multi-turn magnetic field detecting elements are one of a magnetic resistance element and a hall element.
5. The magnetic encoder unit according to claim 1 , wherein
the multi-turn magnetic field detecting elements are disposed in the circumferential direction of the permanent magnet.
6. The magnetic encoder unit according to claim 1 , wherein the multi-turn magnetic field detecting elements are disposed on the side surface of the permanent magnet with a gap therebetween in the axis direction of the rotating member.