# US 11,442,120 B2 · Magnetic sensor with compensation coil for cancelling magnetic flux applied to a magneto-sensitive element

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,442,120 B2
- Document ID: US11442120B2
- Status: Granted
- Kind: B2
- Application number: 16/981,146
- Filed: 2019-03-11
- Published: 2021-04-22
- Granted: 2022-09-13
- Earliest claimed: 2018-03-29
- Assignees: TDK Corporation
- Applicants: TDK Corporation
- Inventors: Takeo Gokita
- Web page: https://patentgrep.com/patent/US11442120B2

## CPC

- G01R 33/09: Magnetoresistive devices
- G01R 33/0011: {comprising means, e.g. flux concentrators, flux guides, for guiding or concentrating the magnetic flux, e.g. to the magnetic sensor}
- G01R 33/025: Compensating stray fields {(G01R33/0017 takes precedence)}
- G01R 15/185: {with compensation or feedback windings or interacting coils, e.g. 0-flux sensors (using galvano-magnetic field sensors G01R15/20; conversion of DC into AC using transductors G01R19/20)}
- G01R 33/0017: {Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields}
- G01R 33/0076: {Protection, e.g. with housings against stray fields}
- H10N 50/10: Magnetoresistive devices
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR

## Abstract

An object of the present invention is to provide a magnetic sensor capable of detecting a magnetic field to be measured through closed loop control even when the magnetic field is weak. A magnetic sensor includes magnetic layers 41 and 42 opposed to each other through a magnetic gap G1, a magneto-sensitive element R1 disposed on a magnetic path formed by the magnetic gap G1, and a compensation coil 60 generating canceling magnetic flux ϕ4 to cancel magnetic flux ϕ2 applied to the magneto-sensitive element R1. According to the present invention, magnetic flux ϕ2 flowing in the magnetic layers 41 and 42 each functioning as a yoke is applied to the magneto-sensitive element R1, so that even when a magnetic field to be measured is weak, it can be detected. In addition, closed loop control can be performed due to the presence of the compensation coil 60 that cancels magnetic flux ϕ2.

## Claims

### Claim 1

A magnetic sensor comprising:
first and second magnetic layers opposed to each other through a first magnetic gap;
a first magneto-sensitive element disposed on a magnetic path formed by the first magnetic gap; and
a compensation coil for canceling magnetic flux to be applied to the first magneto-sensitive element,
wherein the first magnetic layer is disposed at a position overlapping an inner diameter area of the compensation coil in a plan view,
wherein the second magnetic layer is disposed at a position overlapping an outside area of the compensation coil in a plan view,
wherein the magnetic sensor further comprises
an external magnetic member that collects external magnetic flux to be measured in the first magnetic layer.
a third magnetic layer opposed to the first magnetic layer through a second magnetic gap; and
a second magneto-sensitive element disposed on a magnetic path formed by the second magnetic gap,
wherein the compensation coil cancels magnetic flux to be applied to the second magneto-sensitive element,
wherein the third magnetic layer is disposed at a position overlapping the outside area of the compensation coil in a plan view,
wherein the first to third magnetic layers, the first and second magneto-sensitive elements, and the compensation coil are all provided on a sensor substrate, and
wherein the first and second magneto-sensitive elements are formed between the compensation coil and the first to third magnetic layers in a lamination direction on the sensor substrate.

### Claim 2

A magnetic sensor comprising:
first and second magnetic layers opposed to each other through a first magnetic gap;
a first magneto-sensitive element disposed on a magnetic path formed by the first magnetic gap; and
a compensation coil for canceling magnetic flux to be applied to the first magneto-sensitive element,
wherein the first magnetic layer is disposed at a position overlapping an inner diameter area of the compensation coil in a plan view,
wherein the second magnetic layer is disposed at a position overlapping an outside area of the compensation coil in a plan view,
wherein the magnetic sensor further comprises
an external magnetic member that collects external magnetic flux to be measured in the first magnetic layer.
a third magnetic layer opposed to the first magnetic layer through a second magnetic gap; and
a second magneto-sensitive element disposed on a magnetic path formed by the second magnetic gap,
wherein the compensation coil cancels magnetic flux to be applied to the second magneto-sensitive element,
wherein the third magnetic layer is disposed at a position overlapping the outside area of the compensation coil in a plan view,
wherein the first to third magnetic layers, the first and second magneto-sensitive elements, and the compensation coil are all provided on a sensor substrate, and
wherein the first and second magneto-sensitive elements are formed between the compensation coil and the first to third magnetic layers in a lamination direction on the sensor substrate.