Nonlinear Suspension Flexures for Vibration Isolation in Tissue Conduction Audio
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Solution Overview
Problem
Conventional tissue conduction audio systems in wearable devices experience degraded audio quality due to unwanted vibrations transferred to the user's cartilage and bone, leading to an uncomfortable user experience and sub-optimal audio quality.
Innovation Solution
A vibration isolation system incorporating nonlinear suspension components with flexures that have an asymmetric spring rate when unloaded and a symmetric spring rate when preloaded, effectively isolating vibrations from the transducer and reducing their transfer to the user's cartilage and bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional suspension components are used in tissue conduction audio systems, then the transducer can present audio to the user, but unwanted vibrations are transferred to the user's cartilage and bone, degrading audio quality and comfort
Solution Approach 1:
The patent applies asymmetry by designing flexures with asymmetric cross-sections (e.g., L-shaped, T-shaped, or Z-shaped profiles) that exhibit different stiffness characteristics in different directions. This asymmetric geometry allows the suspension component to preferentially isolate unwanted vibrations while maintaining necessary mechanical compliance for audio presentation, thereby reducing vibration transfer to the user without compromising audio quality
Solution Approach 2:
The patent implements dynamics by using nonlinear suspension components whose stiffness characteristics change with displacement and loading conditions. The flexures are designed to have position-dependent spring rates, being softer in certain displacement ranges to isolate vibrations and stiffer in others to maintain structural integrity, enabling adaptive vibration isolation that preserves audio fidelity while protecting the user from uncomfortable vibrations
2Stability of the object's composition
If pre-loading force is applied to keep mechanical and acoustic components in contact with the wearer, then component contact is maintained, but the operating state of the component changes, degrading audio quality
Solution Approach 1:
The patent applies parameter changes by designing flexures with nonlinear force-displacement characteristics where the stiffness parameter varies with the applied load and displacement. The asymmetric spring rate profile allows the component to maintain stable contact under pre-loading while exhibiting softened stiffness in the operational range, preventing degradation of audio quality despite the necessary pre-load for component contact
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 vibration isolation system enhances the user's audio experience by minimizing the transfer of unwanted vibrations, maintaining low-frequency extension and improving audio quality in wearable devices like VR/AR headsets.
Implementation Method 1
a nonlinear suspension component with flexures configured to be displaced while bearing a load
Implementation Method 2
The plurality of flexures includes at least one set of flexures that have a symmetric spring rate over displacement while in a target position and an asymmetric spring rate while in a resting position
Implementation Method 3
A vibration isolation system to damp vibrations from a transducer configured to present audio to a user
Data Source
AI summary
A tissue conduction audio system includes a transducer that produces vibrations as it presents audio to a user. A vibration isolation system isolates the vibrations produced by the transducer. The vibration isolation system includes a suspension component with flexures that are configured to have an asymmetric spring rate when at rest and a symmetric spring rate when the transducer is in use and/or at a target position.