Compound Loudspeaker Flexible Seal for Turbulent Airflow
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Solution Overview
Problem
Compound loudspeakers experience audible turbulent airflow due to air pressure differentials between the interior and exterior of the cabinet, particularly when operated at low frequencies, causing undesirable noise.
Innovation Solution
A flexible annular seal is introduced between the high frequency and low frequency diaphragms, comprising ring-shaped regions joined by a semi-circular flexible region, which allows for sufficient axial motion of the low frequency diaphragm while minimizing discontinuity and preventing air passage, thus reducing turbulent airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between the high frequency diaphragm and low frequency diaphragm is made narrow to prevent diffraction, then the high frequency response is improved, but air pressure differential forces air through the gap causing audible turbulent airflow at low frequencies
Solution Approach 1:
A flexible seal is introduced as an intermediary element between the high frequency diaphragm assembly and the low frequency diaphragm. This seal acts as a mediator that blocks the harmful air flow path through the gap while preserving the narrow gap dimensions needed for high frequency performance. The seal is specifically designed to be flexible enough to allow diaphragm motion while maintaining the air barrier function.
Solution Approach 2:
The invention employs a flexible seal in the form of a thin membrane or film structure that can deform with diaphragm motion. This flexible shell configuration allows the seal to adapt to the dynamic movement of the low frequency diaphragm during sound generation, particularly during large excursions at low frequencies, while continuously blocking the gap to prevent turbulent air flow.
2Object-generated harmful factors
If the gap is made wide to allow air passage, then turbulent airflow is reduced, but diffraction from the gap degrades the high frequency response
Solution Approach 1:
The flexible seal serves as an intermediary that resolves the contradiction by providing an air barrier without requiring a wide gap. Instead of allowing air passage through a wide gap or blocking it with a rigid structure that would cause diffraction, the flexible seal blocks air flow through the narrow gap while its flexibility prevents it from acting as a rigid discontinuity that would degrade high frequency response.
3Object-generated harmful factors
If a rigid seal is used to block air passage, then turbulent airflow is prevented, but the seal restricts the axial motion of the low frequency diaphragm
Solution Approach 1:
The invention uses a flexible seal membrane that can deform axially to accommodate the large excursions of the low frequency diaphragm. This flexible structure allows the diaphragm to move freely through its required axial range while the seal maintains its air-blocking function. The flexibility of the thin film structure is key to resolving the contradiction between sealing effectiveness and diaphragm motion freedom.
Solution Approach 2:
The seal is designed as a dynamic component that adapts its configuration in response to diaphragm motion. During large excursions of the low frequency diaphragm, the flexible seal deforms to accommodate the motion while maintaining the air barrier. This dynamic behavior allows the seal to function effectively across the full range of diaphragm operation without restricting axial motion.
4Object-generated harmful factors
If the seal is made with large radial width to ensure complete sealing, then air passage is blocked, but the discontinuity increases affecting high frequency performance
Solution Approach 1:
The flexible seal is designed as a thin film structure with minimal radial width that extends across the gap. This thin membrane configuration provides effective air blocking with minimal radial dimension, thereby reducing the discontinuity that would otherwise degrade high frequency response. The flexibility of the thin film allows it to maintain sealing effectiveness despite its small radial width.
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 seal effectively prevents air from passing through the gap between the diaphragms, maintaining high frequency response and ensuring sufficient sound-generating motion of the low frequency diaphragm without compromising the performance of the high frequency diaphragm, thereby eliminating audible turbulent airflow.
Implementation Method 1
A compound loudspeaker is disclosed in which a seal is provided in a gap between an acoustically radiating high frequency diaphragm and an acoustically radiating low frequency diaphragm to prevent or hinder passage of air through the gap
Implementation Method 2
The seal preferably is flexible. For example, the seal may be attached directly or indirectly to one or both of the first and second diaphragms and arranged to flex in response to sound-generating motions of the diaphragm(s) in use
Data Source
Figure 1
Figure 2(a)~3
Figure 4(a)~4(b)
AI summary
A compound loudspeaker comprises an acoustically radiating first diaphragm and an acoustically radiating second diaphragm. The first and second diaphragms are substantially coaxial and at least part of the second diaphragm is situated radially outwards of the first diaphragm. There is a gap situated between the first and second diaphragms, and a seal is provided in the gap, thereby preventing or hindering the passage of air through the gap. By providing the seal, the invention solves the problem of audible turbulent airflow through the gap.