Asymmetric Docking Magnet for Wearable Audio Magnetometer Interference
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Solution Overview
Problem
Wearable audio devices, such as earbuds, face interference from strong magnetic fields generated by docking or parking magnets, which overwhelm the magnetometer and prevent it from accurately detecting the Earth's magnetic field, leading to improper orientation tracking and audio output issues.
Innovation Solution
Incorporating a docking or parking magnet with opposed sides, where the flux of the magnetic field from one side is stronger than the other, and positioning it closer to the magnetometer, along with using a Halbach array configuration to minimize interference, allowing the magnetometer to operate within its linear range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a docking or parking magnet is placed close to the magnetometer to enable docking functionality, then the docking capability is improved, but the magnetic field from the magnet overwhelms the magnetometer and prevents it from detecting the Earth's magnetic field properly
Solution Approach 1:
The docking magnet is designed with non-uniform magnetic flux distribution across its surface, creating regions of different magnetic field strengths. This allows the magnet to provide sufficient magnetic attraction for docking while limiting the magnetic field strength at the magnetometer's location to prevent overwhelming the sensor.
Solution Approach 2:
The magnet exhibits asymmetric magnetic flux distribution, with higher flux density on one side and lower flux density on the opposite side. This asymmetric configuration enables the magnet to maintain strong docking capability in one direction while minimizing interference with the magnetometer positioned on the low-flux side.
2Volume of moving object
If the wearable audio device is made small to improve comfort and wearability, then the device size is reduced, but the magnetometer is forced closer to other magnets, increasing magnetic interference
Solution Approach 1:
By creating localized variations in magnetic flux density within the docking magnet, the design allows small device dimensions while maintaining acceptable magnetic interference levels at the magnetometer's location. The low-flux region provides a protected zone for the magnetometer.
Solution Approach 2:
The design converts the potentially harmful strong magnetic field into a beneficial configuration by directing the high flux density away from the magnetometer and toward the docking interface, thereby transforming magnetic interference into useful docking force.
3Reliability
If a strong magnetic field is generated by the docking magnet to improve docking reliability, then the docking strength is increased, but the magnetic field overwhelms the magnetometer and causes it to malfunction
Solution Approach 1:
The docking magnet implements spatially varying magnetic flux density, with high flux regions positioned to maximize docking reliability and low flux regions positioned to protect the magnetometer. This local differentiation allows simultaneous achievement of strong docking and proper sensor operation.
Solution Approach 2:
The asymmetric flux distribution creates a directional magnetic field pattern where the strong magnetic attraction is concentrated at the docking interface while the magnetometer operates in a region of reduced magnetic field strength, resolving the conflict between docking reliability and sensor functionality.
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 reduces the combined magnetic field strength at the magnetometer to a level where it can accurately detect the Earth's magnetic field, improving orientation tracking and preventing interference with the transducer magnet, thus enhancing the stability and accuracy of the wearable audio device's operation.
Implementation Method 1
The docking or parking magnet produces a magnetic field having a flux from a first side of the magnet with a greater magnitude than a flux from a second side of the magnet
Implementation Method 2
The Halbach array may comprise a discrete array comprising at least three permanent magnets arranged side-by-side and with the north poles of three adjacent magnets all pointing in different directions
Implementation Method 3
Magnetometers need to accurately detect the Earth's magnetic field
Implementation Method 4
The magnetic device may comprise a transducer magnet of an electro-acoustic transducer that is adapted to create an audio output
Data Source
AI summary
A wearable audio device including a magnetic device and a docking or parking magnet that has opposed first and second sides and produces a magnetic field, wherein the flux of the magnetic field from the first side has a greater magnitude than the flux of the magnetic field from the second side, and wherein the second side is closer to the magnetic device than is the first side.