Magnetic sensor system
View Patent ↗A magnetic sensor system includes a magnetic field generation unit for generating a target magnetic field and a magnetic sensor for detecting the target magnetic field, and is selectable between an operating state and a non-operating state. The magnetic sensor has a magnetic detection element including a magnetic layer whose magnetization direction varies according to the direction of the target magnetic field in a reference position. When in the operating state, the direction of the target magnetic field in the reference position varies when viewed from the magnetic sensor. When in the non-operating state, the direction of the target magnetic field in the reference position does not vary when viewed from the magnetic sensor and the magnetization direction of the magnetic layer is pinned in a first direction. The magnetic layer has an induced magnetic anisotropy that is imparted in advance to the magnetic layer.
1. A magnetic sensor system comprising:
a magnetic field generation unit for generating a magnetic field to be detected; and
a magnetic sensor for detecting the magnetic field,
the magnetic sensor system being selectable between an operating state and a non-operating state, wherein
the magnetic sensor has a magnetic detection element, and generates a detected value having a correspondence relationship with an angle that a direction of the magnetic field in a reference position forms with respect to a reference direction,
the magnetic detection element includes a magnetic layer whose magnetization direction varies according to the direction of the magnetic field in the reference position,
when the magnetic sensor system is in the operating state, the direction of the magnetic field in the reference position varies when viewed from the magnetic sensor,
when the magnetic sensor system is in the non-operating state, the direction of the magnetic field in the reference position does not vary when viewed from the magnetic sensor and is pinned in firs direction, and consequently the magnetization direction of the magnetic layer is pinned in the first direction,
the magnetic layer has an induced magnetic anisotropy that is imparted in advance to the magnetic layer, the induced magnetic anisotropy being oriented to reduce error caused by a posteriori induced magnetic anisotropy resulting from the magnetic field generation unit, and
an easy axis of magnetization resulting from the induced magnetic anisotropy imparted to the magnetic layer is oriented in a direction that forms an angle in the range of 0° to 15° with respect to the first direction.
2. The magnetic sensor system according to claim 1 , wherein
when the magnetic sensor system is in the operating state, the magnetic field generation unit and the magnetic sensor are in a varying relative positional relationship with each other, and
when the magnetic sensor system is in the non-operating state, the magnetic field generation unit and the magnetic sensor are in a fixed relative positional relationship with each other.
3. The magnetic sensor system according to claim 1 , wherein the magnetic sensor makes a correction of an error that occurs in the detected value due to the induced magnetic anisotropy imparted to the magnetic layer.
4. The magnetic sensor system according to claim 3 , wherein the correction of the error is implemented by a shape magnetic anisotropy imparted to the magnetic layer.
5. The magnetic sensor system according to claim 4 , wherein an easy axis of magnetization resulting from the shape magnetic anisotropy is oriented in a direction that forms an angle in the range of 75° to 90° with respect to both of the first direction and the direction of the easy axis of magnetization resulting from the induced magnetic anisotropy.
6. The magnetic sensor system according to claim 3 , wherein the magnetic sensor includes an arithmetic circuit for making the correction of the error.