AMT Magnetic Structure With Embedded Magnets and No Pole Pieces
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Solution Overview
Problem
Existing air motion transformer (AMT) transducers face challenges in creating a strong enough magnetic field to drive diaphragm layers due to the large magnetic gap dictated by the diaphragm structure, which is exacerbated by the use of permanent magnets that decay rapidly with distance, and the placement of pole pieces obstructs acoustic transparency and diminishes high-frequency response.
Innovation Solution
A novel magnetic structure for AMT transducers is introduced, where multiple magnets are distributed within the diaphragm assembly, eliminating the need for additional pole pieces and optimizing magnetic flux direction to the diaphragm layers, thereby enhancing magnetic field strength and reducing stray fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pole pieces are placed in front of and behind the diaphragm to direct magnetic flux, then magnetic field strength is improved, but acoustic transparency is reduced and high-frequency response is diminished
Solution Approach 1:
The invention extracts and removes the pole pieces from the magnetic circuit design. By using permanent magnets with optimized geometry and positioning them to directly face the diaphragm, the patent eliminates the need for separate pole pieces, thereby removing the acoustic obstructions they caused while maintaining magnetic field strength through direct flux paths.
Solution Approach 2:
The invention merges the functions of the magnets and pole pieces into a single integrated magnetic structure. The permanent magnets are positioned and shaped to directly provide both the magnetic field generation and the flux directioning that were previously separate functions, eliminating the need for additional pole piece components.
2Strength
If permanent magnets are used to create magnetic field, then magnetic field is produced, but field strength decays rapidly with distance according to inverse cube law
Solution Approach 1:
The invention applies local quality by positioning multiple permanent magnets at specific locations around the diaphragm perimeter rather than using a single large magnet. This distributed arrangement creates localized strong magnetic fields at each magnet position, ensuring adequate field strength across the entire diaphragm surface despite the rapid decay with distance.
Solution Approach 2:
The invention segments the magnetic field generation into multiple discrete permanent magnets distributed around the diaphragm. This segmentation allows each magnet to operate within an optimal distance from portions of the diaphragm, compensating for the inverse cube law decay by having multiple sources rather than relying on a single distant source.
3Length of moving object
If large magnetic gap is used to accommodate diaphragm structure, then diaphragm movement is enabled, but magnetic field strength is reduced due to distance from permanent magnets
Solution Approach 1:
The invention segments the magnetic field generation into multiple discrete permanent magnets distributed around the diaphragm perimeter. This segmentation allows each magnet to operate within an optimal distance from portions of the diaphragm, compensating for the inverse cube law decay by having multiple sources rather than relying on a single distant source.
Solution Approach 2:
The invention transitions from a single-plane magnetic arrangement to a three-dimensional distributed magnetic structure. By positioning magnets at various locations around the diaphragm perimeter and optimizing their spatial arrangement, the patent creates a volumetric magnetic field that maintains strength across the larger magnetic gap required for diaphragm movement.
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 results in an ironless motor design that improves efficiency, reduces transducer size, and minimizes acoustic obstructions, leading to superior sound quality and reduced material usage.
Implementation Method 1
The electrical conductors bonded onto the membrane substrate are arranged such that the path of charged particles moving through the conductive traces is substantially perpendicular to the magnetic field created by the motor structure, all the while the current in adjacent layers is flowing in opposite directions. The resulting Lorentz force causes the adjacent diaphragm layers to either move toward or away from each other
Implementation Method 2
a magnetic structure for an air motion transformer (AMT) electroacoustic transducer comprises at least one magnet positioned at least partially within the diaphragm assembly
Data Source
AI summary
There is provided a magnetic structure for an air motion transformer (AMT) electroacoustic transducer comprising a diaphragm assembly (7), wherein the magnetic structure comprises at least one magnet (6) positioned at least partially within the diaphragm assembly (7).