Bone Conduction Speaker Case Vibration Control
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Solution Overview
Problem
Bone conduction speakers experience sound leakage due to mechanical vibrations causing surrounding air to vibrate, and existing solutions do not effectively address this issue while maintaining sound quality.
Innovation Solution
The design of a bone conduction speaker with a simplified structure and compact size, featuring a case with increased stiffness, a vibration transmission sheet with adjustable stiffness, and an earphone fixing component, which collectively reduce sound leakage and enhance sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the bone conduction speaker uses a simple structure and compact size, then the device complexity is reduced, but sound leakage increases due to mechanical vibrations driving surrounding air
Solution Approach 1:
The patent converts the harmful sound leakage caused by mechanical vibrations into a beneficial effect by designing the case to vibrate in a controlled manner. The case vibrations, which initially cause sound leakage, are harnessed to transmit sound through bone conduction while the front and back surfaces work together to cancel out unwanted sound radiation, transforming the harmful vibration into useful sound transmission.
Solution Approach 2:
The patent employs asymmetric design in the case structure where the front surface and back surface have different configurations and stiffness characteristics. This asymmetry allows the front surface to effectively transmit vibrations to the user's bone while the back surface is optimized to minimize sound radiation outward, creating a directional sound transmission pattern that reduces overall sound leakage.
2Object-generated harmful factors
If the case stiffness is increased to reduce sound leakage, then sound leakage is reduced, but the sound quality may be affected due to altered vibration characteristics
Solution Approach 1:
The patent applies local quality by creating regions of different stiffness within the case structure. The front surface is designed with specific stiffness characteristics optimized for bone conduction transmission, while the back surface has different stiffness properties optimized for minimizing sound radiation. This localized differentiation allows each surface to perform its specific function optimally without compromising overall sound quality.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the stiffness, mass, and geometric dimensions of the case components to optimize both sound leakage reduction and sound quality. By carefully controlling physical parameters such as thickness, material properties, and structural geometry, the case can achieve the desired vibration characteristics that simultaneously reduce sound leakage and maintain high-fidelity sound transmission.
3Reliability
If the vibration transmission sheet has adjustable stiffness, then the sound quality can be optimized, but the device complexity increases
Solution Approach 1:
The patent implements dynamics by designing the vibration transmission sheet with adjustable stiffness characteristics. This allows the sheet to adapt its mechanical properties based on operating conditions, enabling optimization of sound quality across different frequency ranges and usage scenarios. The adjustable stiffness provides dynamic control over vibration transmission characteristics without requiring complex active control systems.
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 proposed solution significantly reduces sound leakage and improves sound quality by ensuring consistent vibration across the case components, canceling out sound leakage and maintaining effective sound transmission.
Implementation Method 1
The magnetic circuit component (1710) is connected to the case (1750) through the second element (1740), and the elastic modulus of the first element is greater than the elastic modulus of the second element
Implementation Method 2
Bone conduction speakers can convert an electrical signal into a mechanical vibration signal, and transmit the mechanical vibration signal into a human auditory nerve through human tissues and bones
Data Source
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AI summary
A bone conduction speaker is provided herein. The bone conduction speaker may include a magnetic circuit component for providing a magnetic field, a vibration component located in the magnetic field, and a case. At least a part of the vibration component may convert an electrical signal into a mechanical vibration signal. The case may include a case panel facing a human body side and a case back opposite to the case panel, and accommodate the vibration component that causes the case panel and the case back to vibrate. A vibration of the case panel may have a first phase, and a vibration of the case back may have a second phase. When frequencies of the vibration of the case panel and the case back are within 2000 Hz to 3000 Hz, an absolute value of a difference between the first and the second phase(s) may be less than 60 degrees.