Speaker with Asymmetric Magnet Height for Flux Density
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Solution Overview
Problem
Conventional speakers have an unsatisfactory electromechanical coupling factor due to the elongated path distance of magnetic lines of force, which is constrained by the enclosure size and magnetic pole height, limiting design needs.
Innovation Solution
The speaker design features a voice coil positioned between two magnets with a height difference, where the magnetic polarities of the magnets are opposite, and the voice coil is wider than the magnetic gap, allowing for increased magnetic flux density by shortening the path distance of magnetic lines of force from the N pole to the S pole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the two magnets are set at the same height to fit the enclosure size, then the enclosure size constraint is satisfied, but the path distance for magnetic lines of force transmission is elongated, resulting in unsatisfactory electromechanical coupling factor
Solution Approach 1:
The patent applies asymmetry by setting the first and second magnets at different heights rather than the conventional same height arrangement. The first magnet has a first height and the second magnet has a second height that is different from the first height, creating an asymmetric magnetic circuit structure. This asymmetric arrangement shortens the magnetic path length from the N pole to the S pole, thereby improving the electromechanical coupling factor while still fitting within the enclosure constraints.
2Reliability
If the voice coil effective width is increased to cover more magnetic flux, then the magnetic flux density improves, but the magnetic gap between magnets must be precisely controlled
Solution Approach 1:
The patent applies parameter changes by specifying that the voice coil effective width is greater than the magnetic gap between the first and second magnets. This parameter relationship ensures that the voice coil can effectively utilize the magnetic flux between the magnets. The asymmetric height design also changes the magnetic field distribution parameters, allowing the voice coil to operate in an optimized magnetic environment that improves flux density without requiring extremely tight gap tolerances.
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 enhances the magnetic flux density around the voice coil, increasing the BL value of the electromechanical coupling factor, thereby meeting design requirements and improving sound generation efficiency.
Implementation Method 1
A speaker is a device that conducts electrical power through a voice coil and then cause induction with respect to a magnet such that the voice coil vibrates
Implementation Method 2
The value of electromechanical coupling factor BL is determined according to the magnetic flux density at the site where the voice coil is located
Data Source
AI summary
A speaker includes a vibration diaphragm, a voice coil, a first magnet, and a second magnet. Each of the first and second magnets includes an end adjacent to the voice coil and an end distant from the voice coil, of which magnetic polarities are opposite to each other. The ends of the first magnet and the second magnet that are adjacent to the voice coil are of opposite magnetic polarities. The voice coil is partly aligned with a gap between the first magnet and the second magnet. A portion of the voice coil is located between the end surfaces of the first and second magnets that exhibit a height difference. Due to the height difference, a path of the magnetic lines of force is shortened and the magnetic flux density in an area around the voice coil is thus increased, thereby increasing the BL value of electromechanical coupling factor.