Speaker Cover Design for Cavity Resonance Control
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Solution Overview
Problem
Current loudspeakers face issues with cavity resonance frequencies affecting acoustic output, particularly in large venues, where these frequencies can cause nulls in the frequency response and reduce acoustic energy output, especially for low-frequency drivers.
Innovation Solution
A cover is designed to partially extend over the diaphragm of low-frequency drivers, adjusting the cavity resonance frequency to a value outside the usable passband, and an adaptable semi-flexible material is used to conform to various diffraction slot profiles, allowing for a compact design and customizable radiation patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the cavity resonance frequency is lowered to improve low-frequency acoustic output, then the acoustic energy output is improved, but the cavity resonance creates nulls in the frequency response and adverse effects
Solution Approach 1:
The patent applies this principle by using the cover to raise the cavity resonance frequency from a harmful low frequency (within the passband) to a beneficial high frequency (above the passband). The cover transforms the adverse cavity resonance effect into a non-interfering condition, allowing the low-frequency drivers to operate without resonance nulls in their operating range while maintaining compact speaker design.
2Manufacturing precision
If the cover extends further over the diaphragm to increase cavity resonance frequency, then the cavity resonance frequency is raised above the passband, but voice coil rubbing occurs
Solution Approach 1:
The patent applies this principle by precisely controlling the extent to which the cover extends over the diaphragm. By adjusting this geometric parameter, the design achieves the optimal balance where the cavity resonance frequency is raised above the passband (improving frequency response) while the extension remains limited to no more than one-third of the diaphragm's cross-sectional area (preventing voice coil rubbing and maintaining reliability).
3Volume of moving object
If low-frequency drivers are positioned close to high-frequency drivers to achieve compact design, then the speaker size is reduced, but cavity resonance effects are exacerbated
Solution Approach 1:
The patent applies this principle by using the cover to transform the harmful cavity resonance effect into a non-problematic condition. By raising the cavity resonance frequency above the passband, the cover allows compact speaker design with close positioning of low and high-frequency drivers without suffering from resonance nulls in the operating frequency range.
4Manufacturing precision
If the cover extends over more than one third of the diaphragm cross-sectional area to further control cavity resonance, then the cavity resonance frequency increases, but voice coil rubbing is caused
Solution Approach 1:
The patent applies this principle by establishing a precise quantitative limit for the cover extension parameter. The cover extends over no more than one-third of the diaphragm's cross-sectional area, which is the optimal parameter value that achieves sufficient cavity resonance frequency elevation while preventing voice coil rubbing and maintaining reliable driver operation.
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 solution enhances the acoustic output by eliminating adverse effects of cavity resonance, enabling a mechanically compact design with improved frequency response and radiation control, while streamlining manufacturing through adaptable components.
Implementation Method 1
The cover is configured to partially extend over the diaphragm to affect an associated cavity resonance frequency of an air cavity adjacent to the diaphragm
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3D
AI summary
The technology described in the document can be embodied in a speaker that includes a housing, at least one electro-acoustic driver including a diaphragm, and a cover secured to one or more of the housing and driver. The cover is configured to partially extend over the diaphragm to affect an associated cavity resonance frequency of an air cavity adjacent to the diaphragm.