Undulating Loudspeaker Diaphragm for Bandwidth Extension
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Solution Overview
Problem
Conventional compression drivers face limitations in simultaneously extending high frequency bandwidth and increasing low frequency output due to the phase plug to diaphragm spacing, which restricts diaphragm displacement and leads to mechanical failure or distortion.
Innovation Solution
A diaphragm formed in a closed loop with a central void, featuring radial and circumferential modulations that protrude axially, increasing axial stiffness while allowing circumferential stretch, enabling larger diaphragm areas for extended frequency bandwidths without structural resonances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the phase plug to diaphragm spacing is reduced to extend high frequency bandwidth, then high frequency output is improved, but maximum diaphragm displacement is limited causing mechanical failure or distortion
Solution Approach 1:
The diaphragm transitions from a conventional flat planar structure to a three-dimensional undulating structure with radial and circumferential modulations. This dimensional change allows the diaphragm to accommodate larger excursions without contacting the phase plug, resolving the contradiction between high frequency bandwidth extension and diaphragm displacement limits.
Solution Approach 2:
The diaphragm geometry parameters are changed by introducing radial and circumferential modulations that create an undulating surface. This parameter change increases the effective displacement space while maintaining the same phase plug spacing, allowing both high frequency extension and reliable operation.
2Power
If the diaphragm size and radiating area are increased to improve low frequency output, then low frequency performance is improved, but non-pistonic vibrational modes occur causing response irregularities
Solution Approach 1:
The undulating three-dimensional structure with radial and circumferential modulations suppresses non-pistonic vibrational modes that plague conventional flat diaphragms. This allows the diaphragm to be enlarged for better low frequency output while maintaining response regularity through the stabilizing effect of the modulated geometry.
Solution Approach 2:
By changing the geometric parameters of the diaphragm surface through radial and circumferential modulations, the vibrational characteristics are altered to eliminate non-pistonic modes. This enables larger diaphragm areas to be used without the response irregularities that would normally occur.
3Area of moving object
If the diaphragm is made larger to increase radiating area, then low frequency output is improved, but the frequency of non-pistonic modes decreases limiting the usable bandwidth
Solution Approach 1:
The transition to a three-dimensional undulating diaphragm structure with radial and circumferential modulations fundamentally changes the vibrational mode frequencies. This allows larger radiating areas to be used while maintaining high frequency bandwidth because the modulated geometry pushes non-pistonic modes to higher frequencies where they do not interfere with the usable audio range.
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 diaphragm design achieves high and low frequency bandwidth extension by controlling vibrational modes, allowing larger diaphragm sizes for improved acoustic output and stability, while minimizing the risk of mechanical failure.
Implementation Method 1
a region, between the inner and outer edges of the diaphragm, which is configured for coupling to a coil for driving the diaphragm in the said direction
Data Source
Figure 1
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Figure 4
AI summary
A diaphragm for a loudspeaker, wherein the diaphragm is formed generally in a closed loop around a central void, the loop lying in a plane, the diaphragm having an axis in a direction orthogonal to the plane along which axis the diaphragm is arranged to be driven in use, the diaphragm having inner and outer circumferential edges which are adapted, in use, to be fixed in position, wherein a substantial portion of the diaphragm between the inner and outer edges is shaped in the direction of the said axis so as to protrude from the general plane of the diaphragm in either or both directions along the axis, and wherein said shaped portion when viewed along the direction of the axis comprises at least one series of curves extending radially across substantially all of the driven area of the diaphragm.