Composite Loudspeaker Cone with Balsa Wood Core
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Solution Overview
Problem
Conventional loudspeaker cones face challenges in maintaining phase coherency and faithfully reproducing sound, especially in higher frequency ranges, due to material properties that suppress percussive sounds and lead to distortion.
Innovation Solution
A composite loudspeaker cone design featuring a first layer of carbon fiber impregnated with epoxy, an interstitial balsawood layer with a Young's modulus greater than 0.2 GPa and density below 600 Kg/m3, and a second layer of carbon fiber, constructed using a method involving mold application and pressure curing, to extend the pistonic frequency range without overly damping percussive sounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If non-resonant material is used in the loudspeaker cone, then the pistonic frequency range is extended, but percussive sounds are overly suppressed
Solution Approach 1:
The patent applies composite materials by combining carbon fiber with balsa wood core to create a loudspeaker cone that achieves both extended pistonic frequency range and preserved percussive sound reproduction. The carbon fiber provides damping characteristics for extended pistonic range while the balsa wood core maintains structural integrity and percussive response, resolving the contradiction between these two opposing requirements.
Solution Approach 2:
The patent applies local quality by using different materials in different regions of the cone - carbon fiber layers at the outer surfaces for damping and balsa wood at the core for structural support and percussive response. This spatial differentiation of material properties allows the cone to simultaneously achieve extended pistonic range and preserved percussive sound reproduction.
2Reliability
If conventional materials are used in the loudspeaker cone, then percussive sounds are reproduced, but phase coherency is lost at higher frequencies
Solution Approach 1:
The patent uses composite materials combining carbon fiber and balsa wood to achieve both percussive sound reproduction and phase coherency at higher frequencies. The carbon fiber provides the necessary damping to maintain phase coherency while the balsa wood core preserves percussive response, eliminating the trade-off present in conventional single-material cones.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the density and Young's modulus of the balsa wood core, specifying density below 600 kg/m³ and Young's modulus greater than 0.2 GPa. These parameter specifications optimize the balance between maintaining phase coherency through damping and preserving percussive sound reproduction through structural integrity.
3Strength
If dense material is used in the loudspeaker cone, then structural integrity is improved, but responsiveness to magnetic field fluctuation is reduced
Solution Approach 1:
The patent applies composite materials by using lightweight balsa wood (density below 600 kg/m³) as the core with carbon fiber reinforcement. This combination provides sufficient structural integrity through the carbon fiber layers while maintaining low overall density for high responsiveness to magnetic field fluctuations, resolving the contradiction between strength and speed.
Solution Approach 2:
The patent applies local quality by placing carbon fiber layers at strategic locations (outer surfaces) where structural integrity is most needed, while keeping the core material (balsa wood) lightweight for responsiveness. This spatial distribution of material properties optimizes both structural strength and magnetic field responsiveness.
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 composite cone design supports pistonic operation over a wide audio range, attenuates housing reflections, and maintains faithful sound reproduction by extending the pistonic region while minimizing damping of percussive sounds.
Implementation Method 1
Loudspeaker cones may be made from non-resonant material, i.e., materials that exhibit well-damped characteristics, in order to suppress lower frequency breakup modes and/or extend the pistonic frequency range.
Implementation Method 2
A mechanical property that may be used to characterize a material for a composite loudspeaker is the density of the material, where less dense materials tend to act with less inertia and as such are more responsive to fluctuation in the magnetic field
Implementation Method 3
interposing a first layer of carbon fiber impregnated with epoxy between a first mold member and an interstitial member
Data Source
AI summary
Composite loudspeaker cones that include an interstitial layer of material having a core density below 600 kg/m3 and a Young's modulus greater than 0.2 GPa, such as balsa wood, interposed between a first carbon fiber layer and a second carbon fiber layer and method of making same.