Loudspeaker Spider M/W Profiles to Reduce Stiffness Nonlinearity
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Solution Overview
Problem
Existing loudspeaker spiders exhibit non-linear stiffness, leading to distortion in sound pressure, fatigue, and difficulty in achieving target stiffness/excursion profiles, while also being complex and costly to manufacture.
Innovation Solution
A spider design with radially extending legs featuring an 'm' or 'w' shaped profile, comprising convex and concave curves, which facilitates a target stiffness/excursion curve, improves radial stiffness, and reduces axial extent, while using materials like thermoplastic polymers for enhanced fatigue performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impregnated cloth fibres are used for the spider, then the spider provides necessary mechanical support and suspension, but the spider exhibits strong stiffness non-linearities leading to distortion in radiated sound pressure
Solution Approach 1:
The patent changes the material parameter from impregnated cloth fibres to a thermoplastic polymer composition, which provides linear elastic behavior and consistent stiffness characteristics, eliminating the distortion problems associated with fibrous materials
Solution Approach 2:
The patent uses a composite material system consisting of a thermoplastic polymer matrix with reinforcing fibres embedded within it, combining the structural support capabilities of fibres with the linear elastic properties of the polymer matrix to achieve both mechanical strength and stiffness consistency
2Reliability
If a complex spider form with individual legs is used, then the spider provides improved radial stiffness and target stiffness/excursion curve, but the spider becomes difficult and expensive to manufacture
Solution Approach 1:
The patent merges the spider structure with the chassis as integral components, eliminating the need for separate spider parts and complex assembly processes while maintaining the required radial stiffness and stiffness/excursion characteristics through the unified thermoplastic polymer construction
Solution Approach 2:
The patent changes the manufacturing approach by using thermoplastic polymer materials that can be molded into complex shapes with integrated features, allowing the production of spiders with precise geometric profiles and internal structures through conventional molding processes rather than complex assembly operations
3Volume of moving object
If the spider axial extent is reduced for compact size, then the loudspeaker enclosure size is reduced, but the spider may have reduced ability to provide axial restoring force
Solution Approach 1:
The patent employs a composite material system with thermoplastic polymer matrix and reinforcing fibres that provides high axial stiffness and restoring force in a compact configuration, allowing the spider to deliver sufficient axial force while maintaining reduced axial extent for compact loudspeaker design
Solution Approach 2:
The patent applies local quality by concentrating the reinforcing fibres in specific regions of the spider where axial load bearing is most critical, while maintaining the overall compact geometry, thus achieving high axial restoring force in a space-efficient manner
4Force
If traditional spider materials are used, then the spider provides necessary suspension and restoring force, but the spider exhibits fatigue and eventual failure under repetitive diaphragm movement cycles
Solution Approach 1:
The patent changes the material parameters by selecting a thermoplastic polymer composition with superior fatigue resistance properties, which can withstand the repetitive cyclic loading from diaphragm movement without degradation, thereby maintaining consistent restoring force and preventing failure over the product lifetime
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 spider design achieves reduced non-linearity, improved radial stiffness, increased fatigue life, and compact size, while maintaining sound quality and reducing unwanted vibration transmission.
Implementation Method 1
The spider provides an axial force that acts to restore the diaphragm/voice coil to a neutral position and a radial force that acts to centre the voice coil within a voice coil gap
Implementation Method 2
it would be advantageous to provide a spider that controls and/or reduces unwanted vibration and/or reduces the transmission of unwanted vibration between elements of the loudspeaker assembly
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A loudspeaker (1) comprising a diaphragm (2), a voice coil (10) mounted on the diaphragm (2) to move with the diaphragm (2), a chassis (4), and a spider (20) is disclosed. The spider (20) extends across a gap between the chassis (4) and the voice coil (10) and comprises a plurality of legs (36), each leg (36) extending radially across at least a portion of the gap. The diaphragm (2) is configured to move from a neutral position to an extended position. When the diaphragm (2) is in the neutral position the cross-sectional shape of each leg (36) follows a line which varies in height with respect to a reference plane, said line comprising first, second and third curves, the second curve being located in between the first and third curves. Either the first and third curves are convex and the second curve is concave, or the first and third curves are concave and the second curve is convex. Thus, the spider (20) may have legs (36) having an 'm' or 'w' shaped profile in at least one region of the leg (36).