Magnetic balance type current sensor
View Patent ↗A magnetic balance type current sensor includes a magnetic balance type current sensor including a magnetoresistance effect element whose characteristic changes owing to an induction magnetic field from a current to be measured flowing through a conductor, a feedback coil configured to be disposed in the vicinity of the magnetoresistance effect element and generate a cancelling magnetic field cancelling out the induction magnetic field, a magnetic shield configured to attenuate the induction magnetic field and enhance the cancelling magnetic field, and a hard bias layer configured to be provided on or above the magnetic shield.
1. A magnetic balance type current sensor comprising:
a magnetoresistance effect element whose characteristics change depending on an induction magnetic field from a current to be measured flowing through a conductor;
a feedback coil disposed in a vicinity of the magnetoresistance effect element and configured to generate a cancelling magnetic field cancelling the induction magnetic field;
a magnetic shield configured to attenuate the induction magnetic field and enhance the cancelling magnetic field; and
a hard bias layer provided on or above the magnetic shield
wherein the feedback coil is disposed between the magnetic shield and the magnetoresistance effect element, and the magnetic shield is disposed between the feedback coil and the conductor.
2. The magnetic balance type current sensor according to claim 1 , wherein the hard bias layer is disposed in both end portions of the magnetic shield in a direction perpendicular to a direction of the induction magnetic field or a direction of the cancelling magnetic field in planar view, the hard bias layer including a pattern extending in the direction of the induction magnetic field or the direction of the cancelling magnetic field.
3. The magnetic balance type current sensor according to claim 1 , further comprising:
a nonmagnetic layer provided between the magnetic shield and the hard bias layer.
4. The magnetic balance type current sensor according to claim 1 , wherein the magnetoresistance effect element is a spin-valve-type GMR element or a spin-valve-type TMR element.
5. The magnetic balance type current sensor according to claim 1 , wherein the magnetic shield is formed of a high magnetic permeability material selected from a group consisting of an amorphous magnetic material, a permalloy-based magnetic material, and an iron-based microcrystalline material.
6. The magnetic balance type current sensor according to claim 1 , wherein the hard bias layer is formed of a hard magnetic material.