Bone Conduction Transducer Low Frequency Efficiency
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Solution Overview
Problem
Bone-conduction transducers (BCTs) suffer inefficiency at audio frequencies below their resonant frequency, limiting sound volume and increasing electrical power consumption.
Innovation Solution
A BCT design with magnets mounted on the diaphragm and constructed from high permeability steel, including a yoke with a SPCD layer, increases magnetic flux and vibrating mass, shifting the resonant frequency to lower frequencies and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional BCT design is used, then the device is simple to manufacture, but efficiency at low frequencies deteriorates
Solution Approach 1:
The patent applies composite materials by combining high permeability steel (SPCD) with traditional transducer components. The SPCD layer is integrated into the yoke structure to enhance magnetic flux density, specifically improving low-frequency efficiency while maintaining manufacturing feasibility through layered construction methods.
Solution Approach 2:
The patent changes material parameters by substituting traditional materials with high permeability steel (SPCD) having specific magnetic properties. This parameter change increases magnetic flux density and shifts resonant frequency to lower ranges, directly addressing the low-frequency efficiency problem.
2Reliability
If magnetic flux is increased to improve efficiency, then low frequency performance improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by adding high permeability steel specifically to the yoke structure where magnetic flux pathways exist. This localized material enhancement targets the specific area needed for improved magnetic flux density without unnecessarily complicating the entire device structure.
Solution Approach 2:
The integration of SPCD layer into the yoke creates a composite structure that combines the mechanical properties of the original yoke material with the enhanced magnetic properties of high permeability steel, achieving improved efficiency with controlled 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 improved design results in increased sound sensitivity and volume, reducing power consumption while maintaining efficient magnetic flux pathways, achieving a 5-decibel increase in sound output with the same power input.
Implementation Method 1
constructed from high permeability steel in order to increase the magnetic flux driving the BCT
Implementation Method 2
a metal coil located between the pair of arms... configured to vibrate in response to a signal supplied to the metal coil
Implementation Method 3
The diaphragm is configured to vibrate in response to a signal supplied to the metal coil
Implementation Method 4
a pair of permanent magnets coupled to the diaphragm, the permanent magnets are each located on opposite sides of the metallic post
Implementation Method 5
a pair of springs each having a first end and second end. The first end of each spring is attached to one of the respective arms
Data Source
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AI summary
A bone conduction transducer includes a yoke having a pair of arms, a layer of high permeability steel on a surface of the yoke between the arms, a metal coil, a metallic post that extends into a center portion of the metal coil, a diaphragm, an anvil attached to a surface of the diaphragm, a pair of permanent magnets attached to an opposite surface of the diaphragm, and a pair of springs. A first end of each spring is attached to a respective one of the arms of the yoke, and a second end of each spring is coupled to the diaphragm. The diaphragm is configured to vibrate in response to a signal supplied to the metal coil. The diaphragm, anvil, and/or metallic post could be formed from a high permeability steel.