Wearable Audio Nulling Magnet for Magnetometer Interference
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Solution Overview
Problem
Wearable audio devices, such as earbuds, face interference from strong magnetic fields generated by their own magnets, which overwhelm the magnetometer and prevent it from accurately detecting the Earth's magnetic field, essential for orientation tracking.
Innovation Solution
Incorporating a nulling magnet that produces a magnetic field to reduce the strength of the transducer magnetic field at the magnetometer, ensuring it operates within its linear range by aligning and symmetrically positioning the transducer magnet, nulling magnet, and magnetometer along a common axis, and using magnetic shields to further minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the magnetometer is positioned close to the transducer magnet to reduce device size, then the wearable audio device can be made smaller, but the strong transducer magnetic field overwhelms the magnetometer and prevents it from accurately detecting the Earth's magnetic field
Solution Approach 1:
A magnetic shield (intermediary component) is introduced between the transducer magnet and the magnetometer. This shield comprises magnetic material that redirects the transducer's magnetic field lines, preventing them from reaching the magnetometer. The shield acts as a mediator that allows the magnetometer to be positioned close to the transducer magnet for compact device size while still protecting the magnetometer from the overwhelming magnetic field, thus maintaining accurate detection of the Earth's magnetic field.
2Volume of moving object
If the transducer magnet is positioned close to the magnetometer to reduce device volume, then the device can be made more compact, but the magnetic field strength from the transducer magnet becomes much greater than the Earth's magnetic field, causing the magnetometer to malfunction
Solution Approach 1:
The magnetic shield serves as an intermediary barrier positioned between the transducer magnet and the magnetometer. It redirects the magnetic field lines of the transducer magnet, creating a protected zone around the magnetometer where the Earth's magnetic field can be detected accurately. This allows the harmful magnetic field interference to be contained while maintaining the compact device volume.
Solution Approach 2:
The magnetic shield creates a localized protected region around the magnetometer where the magnetic field environment is different from the surrounding area. Inside this localized zone, the transducer's magnetic field is redirected away, allowing the magnetometer to operate in a controlled magnetic environment despite the close proximity of the transducer magnet.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows the magnetometer to accurately detect the Earth's magnetic field, enhancing the accuracy of orientation tracking and preventing stray magnetic fields from disrupting its operation.
Implementation Method 1
A magnetic field sensor outside of the magnetic structure is constructed and arranged to sense the Earth's magnetic field. A nulling magnet is coupled to or proximate the outside of the magnetic structure and is constructed and arranged to produce a nulling magnetic field that reduces the strength of the transducer magnetic field at the magnetic field sensor.
Implementation Method 2
a magnetic structure such as a cup that guides the transducer magnetic field, wherein the transducer magnet is on an inside of the magnetic structure, and the magnetic structure has an outside.
Data Source
AI summary
A wearable audio device with an electro-acoustic transducer that is configured to create audio output. The transducer has a transducer magnet that produces a transducer magnetic field having a magnetic field strength, and a magnetic structure such as a cup that guides the transducer magnetic field. The transducer magnet is on the inside of the magnetic structure. There is a magnetic field sensor outside of the magnetic structure; the magnetic field sensor is constructed and arranged to sense the Earth's magnetic field. A nulling magnet is coupled to or proximate the outside of the magnetic structure and is constructed and arranged to produce a nulling magnetic field that reduces the strength of the transducer magnetic field at the magnetic field sensor.