Dual-Movable-Element Capacitive Electromechanical Design for Pull-In Stability
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Solution Overview
Problem
Existing capacitive detection microphones suffer from energy loss due to deformation of the piston, transmission device, and frame, leading to reduced sensitivity and resonance frequency, and are prone to the 'pull-in' collapse phenomenon, which limits the bias voltage that can be applied.
Innovation Solution
An electromechanical system with two movable elements connected to capacitive measurement or actuation means through rotatable pivot hinges and transmission devices, minimizing energy loss by eliminating deformation in the transmission path and using elastic means to counteract the pull-in effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single movable element is used with capacitive detection means, then the structure is simple, but energy loss occurs due to deformation of the piston, transmission device, and frame, reducing sensitivity and resonance frequency
Solution Approach 1:
The single movable element is divided into two separate movable elements (first movable element and second movable element), each connected to its own capacitive detection means. This segmentation eliminates the energy loss associated with deformation of a single large movable element and its transmission path, as each element has a reduced mass and smaller deformation characteristics, thereby improving sensitivity and resonance frequency while maintaining structural simplicity through symmetry.
2Measurement precision
If bias voltage is increased to improve sensitivity, then the pull-in collapse phenomenon occurs, limiting the maximum applicable voltage
Solution Approach 1:
The two movable elements are positioned symmetrically on opposite sides of the fixed electrode, creating a balanced configuration where the electrostatic forces on each element counterbalance each other. This symmetric arrangement allows higher bias voltages to be applied without causing pull-in collapse, as the force distribution remains stable even at elevated voltage levels, thereby improving sensitivity while maintaining reliability.
3Strength
If the movable element mass is increased to improve rigidity, then the resonance frequency decreases, reducing performance
Solution Approach 1:
The mass is distributed across two separate movable elements rather than concentrated in a single element. Each element has reduced mass compared to a single large element, which maintains high resonance frequency. The combined rigidity of the two elements provides sufficient structural strength, achieving an optimal balance between rigidity and resonance frequency that improves overall performance.
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 system achieves improved sensitivity and resonance frequency by distributing energy efficiently between two movable electrodes, reducing overall dimensions, and maintaining a stable bias voltage without increasing mass, thus enhancing performance.
Implementation Method 1
The electrostatic force, which tends to bring the movable electrode closer to the fixed electrode (or to one of the fixed electrodes) and which depends on the square of the bias voltage
Implementation Method 2
The transmission device is mounted so as to be rotatably movable relative to the frame by means of several pivot hinges
Data Source
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AI summary
The invention relates to an electromechanical system (2) comprising: - a frame (10); - a first element (13a) that is movable relative to the frame (10); and - capacitive measurement or actuation means (15') comprising: - a first electrode (151) movable relative to the frame (10); and - at least one electrode fixed relative to the frame (10) and separated from the first movable electrode (151) by a first dielectric medium; - a first movement transmission device (14a) connecting the first movable element (13a) to the first movable electrode (151), the first transmission device (14a) being rotatably movable relative to the frame (10) by means of a plurality of first pivot hinges (16a); - a second element (13b) movable relative to the frame (10), the second movable element (13b) being connected to the capacitive measurement or actuation means (15').