Microphone Airtight Back Chamber Pneumatic Vibration Cancellation
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Solution Overview
Problem
Dynamic microphones are sensitive to low frequency vibrations, which can be transmitted through the outer casing and interfere with sound reception, despite the use of shock absorbing seats.
Innovation Solution
An airtight back chamber is created using a shock absorber and an airtight member within the microphone, generating a pneumatic wave that offsets mechanical vibrations through a damping material, allowing the waves to cancel each other out at the sound receiving module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shock absorbing seats are used to suspend the capsule, then the capsule is protected from mechanical vibration, but low frequency vibration (50-300 Hz) still passes through the outer casing and interferes with sound reception
Solution Approach 1:
The patent introduces a pneumatic wave generation mechanism within the back chamber that creates air pressure variations to counteract mechanical vibrations. The airtight back chamber with its specific volume and the pneumatic wave generator work together to generate counter-vibrations that cancel out the harmful low frequency mechanical vibrations (50-300 Hz) before they reach the capsule, thereby resolving the contradiction between vibration protection and sound reception quality.
Solution Approach 2:
The patent replaces the purely mechanical shock absorbing seats with a combined system that includes a pneumatic wave generation mechanism. Instead of relying solely on mechanical damping materials that allow vibrations to pass through, the system generates active pneumatic waves that actively counteract the mechanical vibrations, providing superior protection against low frequency vibrations while maintaining sound reception quality.
2Object-affected harmful factors
If an airtight back chamber is created with specific volume to generate pneumatic waves, then destructive interference is achieved, but the device structure becomes more complex
Solution Approach 1:
The airtight back chamber serves multiple functions: it acts as a vibration isolation chamber, a pneumatic wave generation chamber, and a structural support element. The shock absorber serves both as a mechanical cushioning element and as part of the airtight sealing system. By making these components multi-functional, the patent reduces the need for additional separate elements, thereby managing structural complexity while achieving effective noise cancellation through destructive interference.
Solution Approach 2:
The patent merges the shock absorber and airtight member into a unified assembly that simultaneously provides mechanical vibration damping and pneumatic wave generation capabilities. The airtight back chamber is integrated into the existing microphone structure rather than being a separate addition. This merging of functions and components reduces overall structural complexity while maintaining the effectiveness of the noise cancellation system.
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
This design effectively reduces noise interference by creating destructive interference between pneumatic and mechanical waves, enhancing acoustic compliance and directivity in low frequency ranges.
Implementation Method 1
The airtight back chamber is configured to generate a pneumatic wave when a mechanical vibration wave is transmitted to the outer casing
Implementation Method 2
the pneumatic wave and the mechanical vibration wave can offset each other when the pneumatic wave and the mechanical vibration wave are transmitted to the sound receiving module
Implementation Method 3
The damping material closes the through hole in the carrier and is configured to change the phase of the pneumatic wave when the pneumatic wave passes therethrough
Implementation Method 4
The damping material closes the through hole in the carrier and is configured to change the phase of the pneumatic wave
Data Source
AI summary
A microphone includes an outer casing, a carrier disposed in the outer casing, and a sound receiving module connected to the carrier. The carrier has a through hole opposite to the sound receiving module. An airtight unit includes a shock absorber and an airtight member cooperating with the outer casing and the carrier to define an airtight back chamber configured to generate a pneumatic wave when a mechanical vibration wave is transmitted to the outer casing. A damping material closes the through hole and is configured to change the phase of the pneumatic wave when the latter passes therethrough such that the pneumatic wave and the mechanical vibration wave can offset each other when they are transmitted to the sound receiving module.