Static Eliminator for MEMS Microphones Using Non-Grounded Conductive Layer
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Solution Overview
Problem
The sensitivity of MEMS microphones varies due to changes in the retained charge amount caused by the application of ions from a static eliminator, leading to instability in electric charges on electretized dielectric films.
Innovation Solution
A static eliminator design where the conductive substance beneath the electretized dielectric film is maintained in a non-grounded state to prevent the formation of a loop circuit and subsequent ion pull-in, reducing the change in retained charge amount and microphone sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ions are applied from an ionizer to an electretized dielectric film to eliminate electric charges, then static elimination effect is achieved, but the retained charge amount changes causing microphone sensitivity variation
Solution Approach 1:
The patent introduces a conductive substance as an intermediary between the ionizer and the electretized dielectric film. This conductive substance serves as a mediator that receives ions from the ionizer while preventing direct ion interaction with the dielectric film, thereby eliminating static charges without causing charge escape from the electretized film and maintaining microphone sensitivity stability
Solution Approach 2:
The patent extracts the harmful effect of direct ion application to the dielectric film by removing the ionizer's direct contact with the film. The conductive substance is positioned to intercept ions before they reach the dielectric film, separating the ionization function from the charge elimination function to prevent sensitivity variation
2Ease of operation
If a conductive substance is placed below the electretized dielectric film, then ion application path is provided, but loop circuit formation causes increased charge escape
Solution Approach 1:
The patent extracts the problematic loop circuit configuration by removing the direct electrical connection between the conductive substance and ground. By eliminating the ground connection, the loop circuit cannot form, preventing the pathway that would enable charge escape from the dielectric film while still allowing ion application to occur
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 approach effectively reduces the variation in retained charge amount and microphone sensitivity while maintaining the static elimination effect, preventing charge escape and ensuring stable microphone performance.
Implementation Method 1
an ionizer comprising a power source and an electrode which applies ions to an electretized dielectric film to eliminate electric charges formed on the electretized dielectric film
Implementation Method 2
The electret film is produced by injecting electric charges into a dielectric film and fixing the thus-injected electric charges. An electric field formed by the injected charges causes a potential difference across electrodes of the condenser.
Data Source
AI summary
The static eliminator includes an ionizer including a power source and an electrode which applies ions to an electretized dielectric film to eliminate electric charges formed on the electretized dielectric film. The electrified substance is in an electrically non-grounded state when the electric charges on the electretized dielectric film are eliminated.