Magnetic field detection sensor exhibiting a monotonous decrease in impedance from zero magnetic field
View Patent ↗A magnetic field detection sensor includes a magneto-impedance element and detects an external magnetic field from an output obtained by applying alternating current to the magneto-impedance element using a magneto-impedance effect. The magneto-impedance element includes a non-magnetic board and a magnetic film formed on a surface of the non-magnetic board, a longitudinal direction of the magnetic film is set as a detection direction of the external magnetic field, and magnetic anisotropy is provided such that a magnetization easy axis of the magnetic film is the same as the detection direction of the external magnetic field. The magnetic field detection sensor further includes a magnetic field generating portion which generates a magnetic field in a thickness direction of the magnetic film.
1. A magnetic field detection sensor comprising:
a magneto-impedance element and which detects an external magnetic field from an output obtained by applying alternating current to the magneto-impedance element using a magneto-impedance effect,
wherein the magneto-impedance element comprises a non-magnetic board and a magnetic film formed on a surface of a one side of the non-magnetic board, a longitudinal direction of the magnetic film is set as a detection direction of the external magnetic field, and magnetic anisotropy is provided such that a magnetization easy axis of the magnetic film is the same as the detection direction of the external magnetic field, and
wherein said magnetic field detection sensor further comprises a magnetic field generating portion arranged facing another side of the non-magnetic board opposite the one side on which the magnetic film is formed and which generates a magnetic field in a thickness direction of the magnetic film and sharpens a single and only peak of an impedance characteristic in a zero magnetic field; and
a bus bar comprising a metal plate member where current flows on a plane orthogonal to the thickness direction of the magnetic film in a current direction orthogonal to the detection direction of the external magnetic field,
wherein the magneto-impedance element is attached to one surface of the bus bar, and
wherein the magnetic field generating portion comprises a magnet and is attached to the other surface of the bus bar with a predetermined distance away from the magneto-impedance element in the current direction.
2. The magnetic field detection sensor according to claim 1 , further comprising:
a printed circuit board,
wherein the magneto-impedance element is attached to one surface of the bus bar through the printed circuit board.
3. The magnetic field detection sensor according to claim 2 , wherein the surface of the non-magnetic board on which the magnetic film is formed is opposite to a surface thereof where the printed circuit board is provided.
4. The magnetic field detection sensor according to claim 1 , wherein the impedance characteristic with a predetermined inclination is secured in a vicinity of the peak where the impedance characteristic monotonously decreases with the peak occurring at a zero magnetic field.
5. The magnetic field detection sensor according to claim 1 , wherein the magnetic field generating portion generates the magnetic field that sharpens the peak of an impedance characteristic in a zero magnetic field without shifting the peak.
6. A magnetic field detection sensor which comprises a magneto-impedance element and which detects an external magnetic field from an output obtained by applying alternating current to the magneto-impedance element using a magneto-impedance effect,
wherein the magneto-impedance element comprises a non-magnetic board and a magnetic film formed on a surface of the non-magnetic board, a longitudinal direction of the magnetic film is set as a detection direction of the external magnetic field, and magnetic anisotropy is provided such that a magnetization easy axis of the magnetic film is the same as the detection direction of the external magnetic field,
wherein the magnetic field detection sensor further comprises a magnetic field generating portion which generates a magnetic field in a thickness direction of the magnetic film and sharpens a peak of an impedance characteristic in a zero magnetic field,
wherein the magnetic field detection sensor further comprises a bus bar comprising a metal plate member where current flows on a plane orthogonal to the thickness direction of the magnetic film in a current direction orthogonal to the detection direction of the external magnetic field,
wherein the magneto-impedance element is attached to one surface of the bus bar, and
wherein the magnetic field generating portion comprises a magnet and is attached to the other surface of the bus bar with a predetermined distance away from the magneto-impedance element in the current direction.
7. The magnetic field detection sensor according to claim 6 , further comprising:
a printed circuit board,
wherein the magneto-impedance element is attached to one surface of the bus bar through the printed circuit board.
8. The magnetic field detection sensor according to claim 7 , wherein the surface of the non-magnetic board on which the magnetic film is formed is opposite to a surface thereof where the printed circuit board is provided.