Raised Curved Loudspeaker Cone Protrusions for Resonant Mode Breakup
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Solution Overview
Problem
Conventional loudspeaker cones suffer from 'cone break-up' behavior, leading to non-pistonical flexing and bending, which causes distortion and deviations from a flat frequency response due to strong resonant modes, and stiffening the cone with exotic materials is economically unreasonable.
Innovation Solution
Incorporating specially contoured protrusions on the loudspeaker cone that are convex on one surface and concave on the other, resembling turbine blades, to disperse resonant modes and increase stiffness without adding mass, using a laminated foam core structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cone is stiffened using exotic materials, then the resonant modes occur at higher frequencies, but the manufacturing cost increases significantly
Solution Approach 1:
The cone surface is segmented into multiple regions by adding raised protrusions that divide the continuous surface into distinct zones. This segmentation creates multiple reflection paths for sound waves, disrupting resonant modes and allowing the use of simpler, less expensive materials while maintaining acoustic performance.
Solution Approach 2:
Raised curved protrusions are added to the cone surface, creating non-planar geometric features. These curved surfaces disrupt the consistent path lengths of sound wave reflections, breaking up resonant modes and reducing the need for expensive exotic materials to achieve the desired acoustic characteristics.
2Weight of moving object
If the cone is made thinner to reduce mass, then the efficiency increases, but the cone becomes more susceptible to resonant mode break-up
Solution Approach 1:
Curved protrusions are introduced on the thin cone surface to disrupt resonant mode paths. The curvature creates varying reflection angles and path lengths, preventing the development of strong resonant modes even in thin, low-mass cones, thereby maintaining reliability without sacrificing weight reduction.
Solution Approach 2:
The solution moves from a two-dimensional flat cone surface to a three-dimensional textured surface with raised protrusions. This dimensional change adds geometric complexity that disrupts resonant modes, allowing thin cones to maintain control over resonant behavior while keeping mass low for improved efficiency.
3Ease of manufacture
If conventional smooth cone surfaces are used, then the manufacturing is simple, but strong resonant modes cause distortion and frequency response deviations
Solution Approach 1:
The smooth cone surface is divided into multiple segments by raised protrusions, creating a textured surface that disrupts resonant mode paths. This segmentation can be achieved through relatively simple molding or forming processes, maintaining manufacturing ease while eliminating the harmful resonant distortion associated with smooth surfaces.
Solution Approach 2:
The surface geometry parameter is changed from smooth to textured with raised protrusions. This parameter change disrupts the consistent path lengths of sound wave reflections, breaking up resonant modes and reducing distortion, while the protrusions can be integrated into standard manufacturing processes without significantly increasing complexity.
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 protrusions disrupt consistent path lengths, creating many weak modes instead of a few strong ones, resulting in a smoother and more controlled frequency response, particularly in the higher frequency range.
Implementation Method 1
the protrusions disrupt consistent path lengths, creating many weak modes instead of a few strong ones, resulting in a smoother and more controlled frequency response
Data Source
AI summary
A loudspeaker transducer diaphragm or cone (e.g., 201, 301 or 401) is configured with arcuate protrusions that project distally from the main forward or distal surface 230 to provide stiffening and a break-up of resonant vibration modes when the loudspeaker is in use. The protrusions (e.g., 210, 310 or 410) are convex on one surface 230 and concave on the opposite surface 234, so their average thickness is similar to the frustoconical areas of the cone, i.e. they are shell-like in nature rather than solid mounds or walls. The protrusions 210 are generally curved as they run radially from the inner opening 204 to the outer peripheral edge to encourage modal break-up (suppressing strong vibrational modes, e.g., as in region 155).