Multi-Magnet Acoustic Transducer Layout for Membrane Stiffness
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Solution Overview
Problem
Existing electrodynamic acoustic transducers face limitations in overall performance, including deformation of the rigid membrane, reduced frequency response, and inefficient cooling, due to the design of the magnet and coil arrangement.
Innovation Solution
The design incorporates a magnet system with center magnets of different orientations and an outer magnet circuit, along with a coil arrangement that forms ribs on the membrane, enhancing stiffness and cooling while reducing magnetic strayfields, and includes a control circuit to actively counteract rocking movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single center magnet design is used, then the structure is simple, but the magnetic field utilization is insufficient and stray fields are high
Solution Approach 1:
The single center magnet is divided into multiple center magnets (first, second, third, and fourth center magnets) with alternating magnetic polarities. This segmentation allows for better magnetic field control and reduced stray fields while maintaining manufacturing feasibility through modular assembly.
Solution Approach 2:
The magnet system uses asymmetric arrangement of magnets with different polarities (N and S poles) in specific positions. The first and third center magnets have one polarity while the second and fourth have opposite polarity, creating an asymmetric but optimized magnetic field distribution that reduces stray fields.
2Weight of moving object
If the membrane is made lightweight for better frequency response, then the frequency response improves, but the membrane deforms more during excursion
Solution Approach 1:
Voice coils are added in the radial direction (perpendicular to the traditional axial arrangement), creating a three-dimensional stiffening structure. This dimensional addition provides structural support without increasing the membrane's areal density, allowing lightweight construction while maintaining stiffness.
Solution Approach 2:
The membrane system combines lightweight membrane material with the stiffening effect of voice coils formed in radial direction, creating a composite structure that achieves both low weight and high structural stability during excursion.
3Device complexity
If voice coils are arranged only axially, then the drive function is simple, but the cooling surface area is insufficient
Solution Approach 1:
Voice coils are arranged in both axial and radial directions, transforming the cooling surface from a one-dimensional axial arrangement to a two-dimensional distributed structure. This increases the effective cooling surface area while maintaining a compact overall structure.
Solution Approach 2:
The voice coils serve dual functions: providing electromagnetic drive force in the axial direction and increasing cooling surface area through their radial arrangement. This multi-functionality eliminates the need for separate cooling structures.
4Loss of energy
If multiple center magnets with different orientations are used, then magnetic field utilization improves, but the magnet system complexity increases
Solution Approach 1:
The magnet system is segmented into four distinct center magnets with alternating polarities, allowing independent optimization of each magnet's position and orientation to improve overall magnetic field utilization while maintaining a systematic and manufacturable structure.
Solution Approach 2:
Each center magnet position is assigned a specific magnetic polarity (N or S) optimized for its location, creating local magnetic field quality variations that collectively improve overall magnetic field utilization and reduce stray fields throughout the air gap.
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 improves the acoustic performance by reducing deformation, increasing output power, and actively preventing rocking, leading to enhanced efficiency, sensitivity, and frequency response.
Implementation Method 1
the magnet system is designed to generate a magnetic field transverse to the conductors of the voice coils in the loop sections
Implementation Method 2
a magnet system and a coil arrangement... the magnet system is designed to generate a magnetic field transverse to the conductors of the voice coils
Data Source
AI summary
An electrodynamic acoustic transducer (1) is disclosed, which comprises a frame and/or a housing (2), a membrane (3), a magnet system (6) with a plurality of center magnets (7a . . . 7d, 7, 7′) having different magnetic orientations (M1 . . . M4) and a coil arrangement (10) with a plurality of voice coils (11a . . . 11d), which are movably arranged relative to the magnet system (6) in an excursion direction (z). The ratioAg·hmAm·wg=lg·htp·hmAm·wgis below 1, wherein wg denotes the mean width of all airgaps (E) within the magnet system (6), Ag denotes the sum of all airgap areas within the magnet system (6), hm denotes the mean height of the center magnets (7a . . . 7d, 7, 7′) and Am denotes the total area of the center magnets (7a . . . 7d, 7, 7′). Moreover, the invention relates to an electroacoustic system (19), which comprises an electrodynamic acoustic transducer (1) of the above kind and a control circuit (CC) connected to the coil arrangement (10).