Rectangular Cross-Section Coil for Electrodynamic Transducer
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Solution Overview
Problem
Existing electrodynamic acoustic transducers face limitations in design freedom due to circular or oval coil shapes, leading to inefficient magnetic flux, shape changes, and poor power weight ratios, which affect sound quality and efficiency.
Innovation Solution
The use of a coil with a rectangular cross-section and conductive layers, where the angle between the longer side and the loop axis is between 80° to 100°, allowing for sharp corners and improved magnetic field alignment, along with a method of manufacturing involving cutting metallic foil, forming insulation layers, and mechanically connecting conductive layers with adhesives to enhance design flexibility and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wound coil with circular or oval shape is used, then the coil can be manufactured using conventional winding processes, but the magnetic flux efficiency is reduced due to large corner radii and inability to form sharp corners
Solution Approach 1:
The coil is divided into multiple straight sections connected at sharp corners, formed by folding a flat conductor sheet into a polygonal shape. This segmentation allows each section to be optimally aligned with magnetic field lines while maintaining sharp corners for efficient flux utilization.
Solution Approach 2:
The coil geometry transitions from traditional circular/oval cross-section to a flat polygonal configuration with sharp corners. This dimensional change enables the coil to be formed by folding a flat conductor sheet, achieving sharp corners and improved magnetic flux alignment that cannot be obtained through conventional winding processes.
2Power
If the coil angle is optimized to 90 degrees for maximum magnetic flux, then sound pressure level is improved, but manufacturing precision requirements increase due to the need for sharp corners and flat geometry
Solution Approach 1:
The conductor is prepared as a flat sheet with pre-defined fold lines and corner positions before assembly. This preliminary preparation ensures that when the conductor is folded into the final polygonal shape, the corners are sharp and the geometry is precise, meeting the stringent requirements for optimal magnetic flux alignment.
Solution Approach 2:
A flat conductor sheet serves as an intermediary form that can be easily manipulated and folded into the precise polygonal geometry. This intermediate state allows for accurate positioning of corners and sides before the final coil assembly, facilitating manufacturing precision without directly forming the complex 3D shape.
3Device complexity
If conventional wire winding is used, then the coil structure is simple, but the fill factor is low resulting in poor power weight ratio and increased device volume
Solution Approach 1:
The coil is constructed from a thin flat conductor sheet that is folded into a polygonal shape, replacing the traditional thick wire winding. This thin-film approach significantly increases the fill factor by reducing the space occupied by insulation and wire diameter, thereby improving the power weight ratio while maintaining structural integrity.
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 approach enables the creation of coils with high fill factors, reduced shape changes, and improved sound pressure levels, resulting in more efficient and compact electrodynamic acoustic transducers with enhanced sound quality and power weight ratios.
Implementation Method 1
The magnet system is designed to generate a magnetic field transverse to the conductor in the loop section
Data Source
AI summary
A method for manufacturing an electrodynamic acoustic transducer is disclosed. The electrodynamic acoustic transducer comprises a frame and/or a housing, a membrane, at least one coil and a magnet system, wherein the coil, in a cross sectional view with a coil axis being part of the sectional plane, comprises a plurality of conductive layers formed by an electrical conductor of the coil. The electrical conductor has a rectangular cross section in said cross sectional view, wherein a longer side of the rectangular cross section is substantially perpendicular to the loop axis. According to this method, a stack of conductive layers is made from the electrical conductor by stacking of separate pieces of the electrical conductor and electrically connecting the stacked separate pieces and/or by folding of the electrical conductor.