Piezoelectric MEMS Microphone Diaphragm Limit Element
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Solution Overview
Problem
Piezoelectric MEMS microphones suffer from instability due to irreversible damage and breakage of diaphragm sheets under impact forces during reliability tests, such as dropping and blowing tests, limited by the strength of the piezoelectric diaphragm.
Innovation Solution
A piezoelectric MEMS microphone design featuring a base with a cavity, a support column, a piezoelectric diaphragm with breathable seams, a limit element with through holes, and restraining elements that control and protect the diaphragm sheets from excessive deformation, including a gasket and blocking boards to prevent breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the piezoelectric diaphragm is made with multiple diaphragm sheets for improved performance, then the frequency response and sensitivity are enhanced, but the diaphragm becomes more vulnerable to impact forces and prone to breakage
Solution Approach 1:
The patent introduces a protective cavity structure positioned below the diaphragm sheets that acts as a cushioning mechanism. When impact forces occur during dropping or blowing tests, the cavity absorbs and distributes the mechanical stress, preventing direct transmission to the fragile diaphragm sheets and avoiding irreversible damage while maintaining the multi-sheet structure for improved frequency response
Solution Approach 2:
The cavity serves as an intermediary protective element between the external environment and the piezoelectric diaphragm. It mediates the impact forces by providing a buffer zone that reduces the direct mechanical load on the diaphragm sheets, thereby protecting the sensitive measurement components while allowing the diaphragm to maintain its multi-sheet configuration for enhanced measurement precision
2Speed
If the diaphragm sheets are made thinner to reduce mass and improve response, then the sensitivity and frequency response are improved, but the strength against impact forces is reduced
Solution Approach 1:
The protective cavity is positioned to receive and absorb impact forces before they can reach the thin diaphragm sheets. This beforehand cushioning allows the diaphragm to be made thinner for improved response speed while the cavity provides the necessary strength protection during impact events
Solution Approach 2:
The patent segments the protective function from the diaphragm structure itself by introducing a separate cavity element. This segmentation allows the diaphragm sheets to be optimized for sensitivity and response speed independently, while the cavity provides the strength and impact resistance, enabling each component to be optimized for its specific function
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 design effectively prevents diaphragm sheet breakage, enhancing the stability and sensitivity of the piezoelectric MEMS microphone while maintaining performance by controlling deformation and reducing noise.
Implementation Method 1
a piezoelectric diaphragm arranged on the base, including a plurality of diaphragm sheets each having a fixing end connected with the support column and a free end suspended above the cavity
Data Source
AI summary
The invention provides a piezoelectric micro-electromechanical systems (MEMS) microphone having a base with a cavity, a piezoelectric diaphragm, and a limit element. The base has a ring base, and a support column. The piezoelectric diaphragm includes diaphragm sheets. Each diaphragm sheet have a fixing end connected with the support column and a free end suspended above the cavity. The limit element includes a limit part arranged apart from the piezoelectric diaphragm to limit the free ends in vibration directions of the diaphragm sheets, and an edge fixing plate connected with the outer edge of the limit part and arranged on the ring base. When the diaphragm sheets greatly deform upwards under impact force, deformation of the diaphragm sheets can be controlled, and the diaphragm sheets are protected to prevent the diaphragm sheets from breaking, thereby improving the stability of the piezoelectric MEMS microphone.