In-field soft magnetic distortion hardware compensation

Patent metadata

Field	Value
Publication number	US-11313935-B2
Application number	US-202016793994-A
Country	US
Kind code	B2
Filing date	Feb 18, 2020
Priority date	Sep 9, 2019
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

A method for calibrating a magnetometer of an electronic device can include detecting a change in a magnetism of the electronic device, collecting a first magnetic field data from the magnetometer at sampling frequency of at least 1 hertz, generating an elliptical calibration model based at least partially on the collected first magnetic field data, collecting a second magnetic field data from the magnetometer, and fitting the collected second magnetic field data to a sphere using the elliptical calibration model.

First claim

What is claimed is:

1. A method of calibrating a magnetometer of an electronic device, comprising:
detecting a change in a magnetism of the electronic device;
collecting a first magnetic field data from the magnetometer at a sampling frequency of at least 1 hertz (Hz);
generating an elliptical calibration model based at least partially on the collected first magnetic field data;
collecting a second magnetic field data from the magnetometer; and
fitting the collected second magnetic field data to a sphere using the elliptical calibration model to calibrate the magnetometer of the electronic device.

2. The method of claim 1 , wherein collecting the first magnetic field data comprises collecting magnetic field data for at least 2 minutes.

3. The method of claim 1 , wherein the electronic device is moved about an axis while collecting the first magnetic field data.

4. The method of claim 1 , further comprising determining a strength and a direction of Earth's magnetic field based at least partially on the sphere.

5. The method of claim 1 , wherein detecting the change in the magnetism comprises detecting a change in a component attached to the electronic device.

6. A method of calibrating a magnetometer of an electronic device, comprising:
detecting a change in a magnetism of the electronic device;
collecting magnetic field data from the magnetometer;
generating an elliptical calibration model based at least partially on detecting the change; and
fitting the collected magnetic field data to a sphere using the elliptical calibration model to calibrate the magnetometer of the electronic device.

7. The method of claim 6 , wherein detecting the change in the magnetism comprises detecting when a component is removably attached to the electronic device.

8. The method of claim 7 , wherein collecting magnetic field data further comprises compensating for movement of the component relative to the electronic device while collecting magnetic field data.

9. The method of claim 7 , wherein the component comprises at least one of a securement band or a case.

10. The method of claim 6 , wherein the change in the magnetism comprises a change in a soft magnetism of the electronic device.

11. The method of claim 6 , wherein detecting the change in the magnetism comprises receiving a response to a prompt.

12. The method of claim 6 , wherein collecting magnetic field data comprises collecting magnetic field data in a background.

13. The method of claim 6 , wherein collecting magnetic field data comprises prompting a user to perform a data collection procedure.

14. The method of claim 6 , wherein collecting magnetic field data comprises collecting magnetic field data from the magnetometer at a sampling frequency of at least 1 Hz.

15. The method of claim 6 , wherein the electronic device comprises a smartwatch.

16. A wearable electronic device, comprising:
a housing defining an internal volume;
a component attachment feature;
a magnetometer disposed in the internal volume; and
a distortion shield component disposed in the internal volume between the magnetometer and the component attachment feature,
wherein the wearable electronic device is configured to collect magnetic field data and fit the magnetic field data to a sphere using an elliptical calibration model to calibrate the magnetometer of the wearable electronic device.

17. The wearable electronic device of claim 16 , wherein the wearable electronic device comprises a smartwatch.

18. The wearable electronic device of claim 17 , wherein the component attachment feature is configured to removably engage a securement band.

19. The wearable electronic device of claim 16 , wherein the distortion shield comprises:
a polymer material; and

a magnetic powder disposed in the polymer material.

20. The wearable electronic device of claim 16 , wherein:
the component attachment feature is disposed on an exterior surface defined by the housing; and
the magnetometer is disposed adjacent to an interior surface of the housing opposite the component attachment feature.

Assignees

• Apple Inc

Inventors

• Dervisoglu Gunes
• Guichet Christopher D
• Howell Adam S
• Wiens Alexander J
• Balcells Christopher E
• Wang Erik L
• Beard Jonathan M
• Tan Tang Y
• Lao Theodore
• Bushnell Tyler S
• Pham Hung A

Classifications

• G01R33/0047

  Housings or packaging of magnetic sensors (packaging of semiconductor devices H10W99/00); Holders · CPC title

• G01R35/005 Primary

  Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references (G01R33/0035, G01R35/002 take precedence) · CPC title

• G01R33/0206

  Three-component magnetometers · CPC title

• G01R33/0017

  Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields · CPC title

• G01R33/0035 Primary

  Calibration of single magnetic sensors, e.g. integrated calibration · CPC title