Electronic Devices With Magnetic Sensors

• US 20140062469A1
• Filed: 03/07/2013
• Published: 03/06/2014
• Est. Priority Date: 08/28/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Lee, Chiajen, Arnold, Shawn Xavier, Yang, Henry H.
• Granted Patent: US 9,664,747 B2
• Time in Patent Office: Days
• US Class Current: 324/247
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence
• CPC Class Codes: G01R 33/0206 Three-component magnetometers

Abstract

Electronic devices may be provided with magnetic sensors for detecting the Earth'"'"'s magnetic field. The magnetic sensors may include thin magnetic sensors located in magnetically quiet regions of the device. The magnetic sensors may be attached to a device housing or a component such as a battery or a cover structure for a battery. The device may include unidirectional magnetic sensors aligned in three orthogonal directions or sensors with two or three magnetic sensor elements aligned in orthogonal directions. Magnetic field data from the three orthogonally aligned sensors or sensor elements may be combined to form directional compass data for the device. Each magnetic sensor may include one or more magnetic sensor elements for detecting the magnetic field and one or more shielded reference sensor elements for detecting environmental changes that can affect the magnetic sensor element. Reference sensor elements may be shared elements for multiple magnetic sensors elements.

Claims

1. An electronic device, comprising:

a housing;

first, second and third unidirectional magnetic sensors in the housing that are configured to detect respective first, second, and third orthogonal components of a magnetic field; and

circuitry coupled to the first, second, and third unidirectional magnetic sensors that is configured to combine magnetic field data gathered using the first, second, and third unidirectional magnetic sensors to form compass data.

2. The electronic device defined in claim 1 wherein the first, second, and third unidirectional magnetic sensors are attached to the housing.

3. The electronic device defined in claim 2 wherein the housing comprises a rear housing portion and a sidewall portion, wherein the first unidirectional magnetic sensor is attached to the rear housing portion, and wherein the second unidirectional magnetic sensor is attached to the sidewall portion.

4. The electronic device defined in claim 3 wherein the third unidirectional magnetic sensor is attached to the rear housing portion and wherein the third unidirectional magnetic sensor is orthogonal to the first unidirectional magnetic sensor.

5. The electronic device defined in claim 4 wherein each of the unidirectional magnetic sensors extends a maximum distance from the housing that is smaller than 150 microns.

6. The electronic device defined in claim 1 wherein electronic components in the housing generate local magnetic fields having first, second, and third orthogonal components and wherein the first unidirectional magnetic sensor is located in a region within the housing at which the first orthogonal component of the local magnetic fields is smaller than the orthogonal second and third components of the local magnetic fields.

7. The electronic device defined in claim 1, further comprising a battery, wherein the first, second, and third unidirectional magnetic sensors are attached to the battery.

8. An electronic device, comprising:

a housing;

an electronic component in the housing;

a structure that at least partially covers that electronic component; and

first, second and third unidirectional magnetic sensors attached to the structure, wherein the first, second, and third unidirectional magnetic sensors each have an elongated dimension and wherein the elongated dimension of each unidirectional magnetic sensor is orthogonal to the elongated dimension of each other unidirectional magnetic sensor.

9. The electronic device defined in claim 8 wherein the electronic component comprises a battery.

10. The electronic device defined in claim 9 wherein the structure comprises a top portion and a folded sidewall portion that is perpendicular to the top portion, wherein the first unidirectional magnetic sensor is attached to the top portion, and wherein the second unidirectional magnetic sensor is attached to the perpendicular sidewall portion.

11. The electronic device defined in claim 10 wherein the structure comprises an additional sidewall portion that is perpendicular to the folded sidewall portion and the top portion and wherein the third unidirectional magnetic sensor is attached to the additional sidewall portion.

12. A magnetic sensor, comprising:

a substrate;

a magnetic sensor element on the substrate having a material that responds to a magnetic field; and

a reference magnetic sensor element on the substrate having a shield that prevents magnetic material in the reference magnetic sensor from being exposed to the magnetic field.

13. The magnetic sensor defined in claim 12, further comprising:

additional substrate material that encapsulates the substrate.

14. The magnetic sensor defined in claim 13, further comprising conductive traces in the additional substrate material.

15. The magnetic sensor defined in claim 12, further comprising:

circuitry on the substrate that is configured to modify magnetic field signals from the magnetic sensor element using magnetic field signals from the reference magnetic sensor element.

16. The magnetic sensor defined in claim 12, further comprising:

an additional magnetic sensor element on the substrate, wherein the magnetic field has a first component that is oriented in a first direction and a second component that is oriented in a second direction that is orthogonal to the first direction, wherein the magnetic sensor element is configured to detect the first component of the magnetic field, and wherein the additional magnetic sensor element is configured to detect the orthogonal second component of the magnetic field.

17. The magnetic sensor defined in claim 16, further comprising:

circuitry on the substrate that is configured to modify magnetic field signals from the magnetic sensor element using magnetic field signals from the reference magnetic sensor element and to modify magnetic field signals from the additional magnetic sensor element using the magnetic field signals from the reference magnetic sensor element.

18. The magnetic sensor defined in claim 16, further comprising:

an additional reference magnetic sensor element on the substrate.

19. The magnetic sensor defined in claim 12 wherein the magnetic sensor has a maximum height along a direction that is perpendicular to a surface of the substrate and passes through the substrate and the magnetic sensor element and wherein the maximum height is less than 150 microns.

20. The magnetic sensor defined in claim 12 wherein the magnetic sensor element includes a portion that is interleaved with a portion of the reference magnetic sensor element on a surface of the substrate.

21. The magnetic sensor defined in claim 12 wherein the magnetic sensor element and the reference magnetic sensor element are at least partially embedded in the substrate.

22. The magnetic sensor defined in claim 21 wherein the shield includes a first portion on a first surface of the substrate, a second portion on an opposing second surface of the substrate, and vertical portions that extend through the substrate from the first surface to the opposing second surface.

23. A magnetic sensor, comprising:

a substrate;

first, second, and third magnetic sensor elements on the substrate, wherein the first magnetic sensor element is configured to detect a first component of a magnetic field, wherein the second magnetic sensor element is configured to detect a second component of the magnetic field that is orthogonal to the first component, and wherein the third magnetic sensor element is configured to detect a third component of the magnetic field that is orthogonal to the first and second components; and

additional substrate material that encapsulates the substrate.

24. The magnetic sensor defined in claim 23, further comprising conductive traces in the additional substrate material that are coupled to circuitry in the substrate.

25. The magnetic sensor defined in claim 24 wherein the magnetic sensor has a thickness in a dimension that is perpendicular to a surface of the additional substrate material and that extends through the substrate, through the first magnetic sensor element, and through the additional substrate material and wherein the thickness is smaller than 200 microns.