Back Cavity Resonance for MEMS Acoustic Frequency Response
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Solution Overview
Problem
Acoustic devices with MEMS components often exhibit uneven frequency responses, leading to performance issues due to peaks and dips in their frequency curves, which complicates signal processing and sound production.
Innovation Solution
Incorporating a back cavity structure within the acoustic device, connected to the sound producing components, to resonate and flatten the frequency response by adjusting the acoustic path length to either half or quarter wavelength corresponding to specific frequencies, thereby balancing sound energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a MEMS sound producing component is used in acoustic devices, then the device size is reduced, but the frequency response becomes uneven with peaks and dips
Solution Approach 1:
A back cavity structure is introduced as an intermediary component between the MEMS sound producing component and the external environment. This back cavity acts as a mediator that modifies the acoustic wave properties through resonance, thereby correcting the frequency response unevenness caused by the small device size without increasing the overall device volume significantly.
Solution Approach 2:
The invention changes the acoustic parameters by adjusting the back cavity volume and the length of the air passage connecting the back cavity to the sound producing component. By optimizing these parameters, the resonance frequency of the back cavity is tuned to compensate for the peaks and dips in the frequency response, achieving more uniform sound output across the audible frequency range.
2Manufacturing precision
If the back cavity structure is added to flatten frequency response, then frequency response uniformity is improved, but device complexity increases
Solution Approach 1:
The back cavity structure is merged with the existing holder or housing of the acoustic device, rather than being a completely separate component. The air passage is integrated into the holder structure, combining the functions of structural support and acoustic waveguide into a single integrated design, thereby minimizing the increase in device complexity.
Solution Approach 2:
The back cavity structure serves multiple functions: it acts as a resonance chamber for frequency response correction, provides structural support for the holder, and forms part of the acoustic waveguide system. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device 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
This configuration results in a flatter frequency response, enhancing the acoustic device's performance by reducing extreme peaks and dips, allowing for more consistent sound production across the frequency range.
Implementation Method 1
the back cavity structure is configured to resonate and flatten the frequency response by adjusting the acoustic path length to either half or quarter wavelength corresponding to specific frequencies
Data Source
AI summary
An acoustic device includes a first sound producing component and a back cavity structure. The first sound producing component has a first front side and a first back side, wherein the first sound producing component is a high frequency sound unit, and the first front side faces a sound propagating opening of the acoustic device. The back cavity structure is connected to the first back side of the first sound producing component. The first sound producing component produces a first acoustic wave from the first front side towards the sound propagating opening, and the first sound producing component produces a second acoustic wave from the first back side towards a back cavity of the back cavity structure. The back cavity structure is configured to flatten a peak or a dip of a frequency response of the first sound producing component.