Side-by-Side Movable Electrodes for Low-Loss Capacitive Detection
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Solution Overview
Problem
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 the pull-in phenomenon limits the bias voltage.
Innovation Solution
An electromechanical system with a frame, a first movable element, capacitive measurement means, and a rotatable transmission device connected via pivot hinges, featuring two movable electrodes separated by dielectric media, and a compact design that minimizes energy loss and pull-in effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the piston, transmission device, and frame are reinforced to reduce deformation, then energy loss is reduced, but the mass of movable parts increases and resonance frequency decreases
Solution Approach 1:
The system is divided into two separate movable elements (first movable element in contact with acoustic pressure and second movable element for capacitive detection), each with its own transmission device. This segmentation allows each element to be optimized independently - the first element can be lightweight for high resonance frequency while the second element with its transmission device can be designed to minimize energy loss through deformation.
Solution Approach 2:
The detection function is extracted from the piston structure itself and placed in a separate second movable element. This allows the first movable element (piston) to remain lightweight and highly responsive to acoustic pressure changes, while the second movable element and its transmission device handle the capacitive detection, minimizing the impact of mass on resonance frequency.
2Device complexity
If a single movable element is used, then the structure is simplified, but energy loss due to deformation increases
Solution Approach 1:
The single movable element is segmented into two distinct movable elements: the first movable element that directly responds to acoustic pressure and the second movable element that interfaces with the capacitive detection system. This segmentation allows the detection function to be separated from the acoustic response function, reducing energy loss through deformation in the transmission path.
3Measurement precision
If high bias voltage is applied to the capacitive detection means, then measurement sensitivity is improved, but the pull-in phenomenon occurs
Solution Approach 1:
The second movable element acts as an intermediary between the acoustic pressure input and the capacitive detection system. It transmits the mechanical displacement from the first movable element to the capacitive sensors with minimal deformation, allowing for reduced bias voltage in the capacitive detection means while maintaining measurement sensitivity, thereby avoiding the pull-in phenomenon.
4Loss of energy
If the transmission device is made more rigid to reduce deformation, then energy loss is reduced, but the device complexity and mass increase
Solution Approach 1:
The transmission function is segmented into two separate transmission devices: one connecting the first movable element to the frame, and another connecting the second movable element to the capacitive detection means. This allows each transmission device to be optimized for its specific function with appropriate rigidity, reducing overall device complexity while minimizing energy loss through deformation in the critical detection path.
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
Enhances sensitivity and resonance frequency while reducing energy loss and pull-in issues, maintaining a compact size and efficient signal detection.
Implementation Method 1
The electrodes form the plates of a capacitor whose capacitance varies as a function of the displacement of the piston 13
Implementation Method 2
This pull-in phenomenon is caused by the electrostatic force, which tends to bring the movable electrode closer to the fixed electrode (or to one of the fixed electrodes)
Data Source
AI summary
An electromechanical system includes a frame; a first element movable relative to the frame; a capacitive measurement or actuation system including a first electrode movable relative to the frame; and at least one electrode fixed relative to the frame and separated from the first movable electrode by a first dielectric medium; a first movement transmission device connecting the first movable element to the first movable electrode, the first transmission device being rotatably movable relative to the frame by a plurality of first pivot hinges; a second element movable relative to the frame, the second movable element being connected to the capacitive measurement or actuation system, the first movable element being disposed between the capacitive measurement or actuation system and the second movable element.