Extended Gap Motor Design for Loudspeaker Distortion Control
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Solution Overview
Problem
Dual-coil/dual magnetic gap designs in loudspeakers experience extreme distortion and heat-related efficiency losses due to large coil excursions, particularly when using thin magnets that reduce the distance between magnetic gaps, necessitating a design that allows for extended motor excursion without distortion and effective heat dissipation.
Innovation Solution
A dual-coil or multi-coil driver configuration with a magnet assembly featuring a spacer member to elongate the permanent magnet, increasing the separation between magnetic gaps and reducing heat concentration, thereby allowing greater excursion without distortion and improving heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dual-coil/dual magnetic gap designs are used to increase power handling, then power handling capability is improved, but extreme distortion occurs due to large coil excursions
Solution Approach 1:
The magnetic assembly is segmented into multiple magnetic gaps with separate voice coils, allowing each coil to operate independently in its own gap. This segmentation enables extended motor excursion capability while maintaining signal integrity and reducing distortion, as each coil portion remains within its designated magnetic gap during operation.
Solution Approach 2:
The patent extends the motor structure axially by adding multiple magnetic gaps along the axis, transforming a single-gap design into a multi-gap configuration. This dimensional extension allows the voice coil to traverse a longer axial distance without leaving the magnetic field, enabling large excursions for high output and deep bass while preventing distortion.
2Length of stationary object
If thin magnets are used to reduce the distance between magnetic gaps, then device compactness is improved, but heat concentration increases causing efficiency losses
Solution Approach 1:
The magnetic assembly is divided into multiple magnetic gaps with spacing between them, creating discrete thermal zones. This segmentation allows heat generated in each gap to dissipate independently rather than concentrating in a single region, reducing overall heat concentration and improving efficiency even with compact magnet thickness.
Solution Approach 2:
Spacing structures or air gaps are introduced as intermediaries between adjacent magnets, providing thermal isolation and heat dissipation pathways. These intermediary elements prevent direct thermal coupling between magnets, allowing compact axial arrangement while managing heat concentration and improving efficiency.
3Length of moving object
If extended motor excursion is achieved through multiple magnetic gaps, then excursion range is improved, but device complexity increases
Solution Approach 1:
The magnetic assembly uses identical or similar magnetic gap structures repeated along the axis, allowing a single design template to be replicated. This universal approach extends the motor excursion range through multiple gaps while minimizing complexity by using standardized components and configurations throughout the assembly.
Solution Approach 2:
The patent resolves complexity by extending the simple single-gap structure into the axial dimension, creating multiple gaps in series. This dimensional transition maintains the simplicity of individual gap design while achieving extended excursion through replication along the axis, avoiding the need for complex three-dimensional magnetic configurations.
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
The solution enables loudspeakers to achieve increased excursion without distortion and reduces heat-related issues, enhancing power handling and efficiency by increasing the axial dimension of the magnet assembly and using a spacer to dissipate heat effectively.
Implementation Method 1
The magnetic assembly establishes a magnetic circuit in which most of the magnetic flux is directed into an annular (circular or ring-shaped) air gap (or 'magnetic gap'), with the lines of magnetic flux having a significant radial component relative to the axis of symmetry.
Implementation Method 2
Due to the Lorenz force acting on the coil material positioned in the permanent magnetic field, the alternating current corresponding to electrical signals conveying audio signals actuates the voice coil to reciprocate back and forth in the air gap
Data Source
AI summary
An electromagnetic transducer includes an electromagnetic dual-coil or multi-coil driver having at least one spacer member placed between at least two permanent magnets. The inclusion of at least one spacer member increases the axial dimension of the magnetic assembly of the driver so that the magnetic gaps in a dual-coil or multi-coil driver are moved farther apart than would occur with a corresponding electromagnetic driver using a permanent magnet instead of two permanent magnets separated by a spacer member.