Loudspeaker Enclosure with Convex Membrane for Diffraction Reduction
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Solution Overview
Problem
Conventional loudspeakers face limitations in achieving spatially coherent sound due to interference between primary and secondary acoustic sources caused by diffraction phenomena, which affect the quality of timbre and stereophonic image.
Innovation Solution
The acoustic enclosure design features a convex movable membrane with a surrounding surface shaped to minimize diffraction, including a spherical zone and annular intervals, where the loudspeakers are arranged to form a continuous spherical surface, and the membranes are metallic to reduce diffraction and enhance spatial coherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional loudspeaker enclosures are used with flat or simple curved surfaces, then manufacturing is easier and structure is simpler, but diffraction phenomena occur causing interference between primary and secondary acoustic sources, degrading spatial coherence and timbre quality
Solution Approach 1:
The enclosure employs a spherical geometry where the loudspeaker membrane forms a continuous spherical surface with the enclosure body. This spherical curvature eliminates sharp edges and corners that cause diffraction, allowing acoustic waves to propagate without interference patterns. The continuous curved surface ensures that primary and secondary acoustic sources do not create harmful diffraction effects, thereby improving spatial coherence and timbre quality.
2Object-affected harmful factors
If the loudspeaker membrane curvature is made analogous to the enclosure curvature, then diffraction phenomena are reduced, but manufacturing precision requirements increase to ensure proper alignment and continuity
Solution Approach 1:
The loudspeaker membrane is merged with the enclosure to form a continuous spherical surface. The membrane and enclosure are designed as integrated components where the membrane's outer surface and the enclosure's inner surface are coplanar and continuous. This merging eliminates gaps, seams, and alignment issues that would otherwise require high manufacturing precision, while still achieving the diffraction-reducing effect of a continuous curved surface.
3Reliability
If a continuous spherical surface is formed between the membrane and enclosure, then spatial coherence and stereophonic image quality are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The enclosure adopts a spherical geometry that naturally provides continuous curvature without complex additional structures. The spherical shape is inherently simple to manufacture using rotational molding or similar processes, while effectively eliminating diffraction from edges and corners. This geometric choice achieves spatial coherence improvement without significantly increasing device complexity.
Solution Approach 2:
The enclosure uses a homogeneous spherical surface throughout, with the loudspeaker membrane matching the enclosure's curvature and material properties. This homogeneity ensures uniform acoustic radiation in all directions, improving spatial coherence and stereophonic image quality. The uniform structure also simplifies manufacturing compared to asymmetric or multi-component designs.
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 significantly reduces diffraction phenomena, leading to improved spatial coherence and a wider, deeper stereophonic image with linear amplitude and phase response across audible frequencies.
Implementation Method 1
the phenomena of interference between the acoustic radiation of loudspeakers constituting primary acoustic sources, and the acoustic radiation of secondary acoustic sources created by diffraction phenomena
Data Source
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AI summary
Loudspeaker enclosure comprising at least one loudspeaker having a convex mobile membrane, and a member surrounding the mobile membrane and comprising an external surface bounded by an internal edge (Γ′) situated facing the mobile membrane, which comprises a peripheral edge (Γ) situated facing the internal edge of the member and forming a closed loop. The mobile membrane and the member have a suitable shape such that, over a continuous portion (Γ″) of the peripheral edge (Γ) representing at least 25% of the length of the peripheral edge, for any first point (M) on the continuous portion and any second point (M′) situated on the internal edge at a location such that the distance between the first point (M) and second point (M′) is minimal, the mobile membrane has, at the first point, a first tangent plane, essentially coincident with a second tangent plane at the second point.