Polygonal Membrane Transducer with Offset Suspension
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Solution Overview
Problem
Existing electrodynamic acoustic transducers face challenges in achieving optimal sound power and sound quality due to the limitations in membrane compliance and design, particularly in micro speakers used in mobile devices, where the membrane area is small and back volume is limited.
Innovation Solution
The design introduces a variation in the distance between points on the polygonal membrane along the loop axis, making the membrane softer in corner and longitudinal regions by adjusting the positions of the outer annular portion, allowing for improved sound power and sound quality without increasing the overall height, and incorporating a magnet system that generates a strong magnetic field only in the longitudinal sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the membrane outer annular portion is positioned in a single plane perpendicular to the loop axis, then the transducer height is reduced, but the membrane compliance and sound power are insufficient
Solution Approach 1:
The patent positions the outer annular portion of the membrane in two different planes along the loop axis direction, creating a stepped or offset configuration. This dimensional change in the z-direction (along loop axis) allows the membrane to achieve greater compliance and sound power output without increasing the overall transducer height, as the offset is distributed along the axis rather than expanding the height envelope.
Solution Approach 2:
The patent applies different positioning strategies to different regions of the membrane: the outer annular portion is positioned at different heights in different radial directions (corner regions vs. longitudinal side regions). This local differentiation optimizes compliance in specific areas where it is most needed for sound power generation, while maintaining compact overall dimensions.
2Adaptability or versatility
If the membrane outer annular portion is offset along the loop axis, then the membrane compliance is improved, but the transducer height increases
Solution Approach 1:
The patent utilizes the loop axis direction (z-dimension) to create offset positioning of the outer annular portion, transforming a height-increasing problem into a compliance-enhancing solution. By distributing the offset along the loop axis rather than expanding the height envelope, the membrane achieves greater compliance while maintaining compact transducer dimensions.
Solution Approach 2:
The offset positioning of the outer annular portion creates a dynamic membrane structure that can adapt its compliance characteristics. The membrane can flex and deform more effectively in the offset regions, enhancing its ability to convert coil movement into sound waves with improved compliance and sound power output.
3Force
If the magnet system generates strong magnetic field in all regions, then the drive force is maximized, but the magnetic field in corner regions causes unwanted effects
Solution Approach 1:
The patent applies magnetic field generation selectively to different regions: the magnet system is positioned to generate strong magnetic fields primarily in the longitudinal side regions where the membrane has good compliance, while avoiding or reducing magnetic field generation in corner regions. This local differentiation maximizes drive force in beneficial areas while eliminating harmful effects in problematic corner regions.
Solution Approach 2:
The patent segments the magnetic field generation function by using separate magnet arrangements for different regions. The magnet system is divided into regions that generate strong fields (longitudinal sides) and regions that avoid strong fields (corners), allowing independent optimization of drive force and harmful effect reduction in different spatial zones.
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 design enhances sound pressure and sound quality by making the membrane softer in critical regions, allowing for better adaptation to the transducer's characteristics and increasing sound pressure by up to 0.5 dB without increasing the transducer's height, while maintaining compactness suitable for micro speakers in mobile devices.
Implementation Method 1
a magnet system, which is fixed to the frame or the housing and which is designed to generate a magnetic field transverse to a longitudinal extension of the coil wire and transverse to the loop axis
Implementation Method 2
a compliant membrane, which converts the movement of the coil into sound waves
Data Source
AI summary
An electrodynamic acoustic transducer is disclosed, which comprises a frame and/or a housing, at least one coil and a magnet system, which is fixed to the frame and/or the housing and which is designed to generate a magnetic field through the coil. Furthermore, the electrodynamic acoustic transducer comprises a polygonal membrane, which in an inner portion is fixed to the at least one coil and which in an outer annular portion is fixed to the frame or the housing. A first distance between the outer annular portion and the inner portion at a longitudinal side of the polygonal membrane is smaller or greater than a second distance between the outer annular portion and the inner portion at a corner of the polygonal membrane.