Capacitive Transducer Stoppers for Diaphragm Anti-Sticking
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Solution Overview
Problem
Conventional capacitive acoustic sensors face issues with diaphragm sticking due to inappropriate spacing and length of stoppers, which affects both anti-sticking and anti-breaking properties, leading to reduced performance and reliability.
Innovation Solution
The capacitive transducer incorporates stoppers of varying protruding lengths strategically positioned on the back plate to match displacement patterns of the diaphragm, with shorter stoppers at regions of large displacement for anti-sticking and longer stoppers at regions of small displacement for anti-breaking, thereby optimizing the contact surface area and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stoppers are made thin to reduce contact surface area and prevent sticking, then anti-sticking property is improved, but anti-breaking property deteriorates because the stoppers cannot provide sufficient support to prevent diaphragm deformation
Solution Approach 1:
The patent applies local quality by making stoppers have non-uniform thickness distribution, with thicker regions at the base and thinner regions at the tip. This allows the stopper to provide sufficient support (thick base) while maintaining small contact area (thin tip), simultaneously improving both anti-breaking and anti-sticking properties
Solution Approach 2:
The patent changes the geometric parameters of the stopper by varying its thickness along the height. The stopper thickness transitions from thicker at the base to thinner at the tip, optimizing the balance between mechanical support capability and contact surface area to resolve the contradiction between anti-breaking and anti-sticking properties
2Reliability
If spacing between stoppers is reduced to cover more diaphragm surface, then anti-sticking property is improved, but total contact surface area increases causing the diaphragm to stick
Solution Approach 1:
The patent uses local quality by making individual stoppers thinner at their tips to reduce contact surface area, allowing increased stopper density without proportionally increasing total contact area. This enables better coverage while maintaining low sticking risk
Solution Approach 2:
The patent segments the stopper structure into multiple small stoppers distributed across the diaphragm surface rather than using fewer large stoppers. This segmentation allows increased spatial coverage while keeping each stopper's contact area small, resolving the contradiction between coverage and total contact area
3Strength
If stoppers are made long to improve anti-breaking property, then anti-breaking property is improved, but anti-sticking property deteriorates because longer stoppers increase contact surface area
Solution Approach 1:
The patent applies local quality by making stoppers thicker at the base (where structural support is needed for anti-breaking) and thinner at the tip (where contact surface area affects sticking). This non-uniform thickness allows long stoppers to provide support without proportionally increasing contact area
Solution Approach 2:
The patent changes the thickness parameter of stoppers along their length, creating a gradient from thick base to thin tip. This parameter variation allows the stoppers to be long enough for anti-breaking support while keeping tip contact area small for anti-sticking 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
This configuration enhances the diaphragm's anti-sticking and anti-breaking properties, preventing sticking and breaking, while maintaining a wide dynamic range and improving the signal-to-noise ratio, thus enhancing the overall performance of the capacitive transducer.
Implementation Method 1
Acoustic vibrations may be detected by detecting the change in capacitance when the diaphragm vibrates because the oscillation of the oscillating electrode plate changes the size of the gap between the oscillating electrode plate and the opposing electrode.
Implementation Method 2
The diaphragm is formed from a thin-film about 1 μm thick; therefore, the diaphragm will make minute oscillations in response to the acoustic pressure impinging thereon.
Implementation Method 3
When the diaphragm 11 flexes greatly and comes in contact with the fixed electrode plate 12, the diaphragm adheres to the fixed electrode plate 12 and no longer returns to its original position... This phenomenon is called 'sticking'.
Data Source
AI summary
A capacitive transducer has a back plate including a fixed electrode, a diaphragm facing the back plate with an air gap interposed therebetween, the diaphragm acting as a movable electrode, at least a first stopper of a first protruding length, and a second stopper of a second protruding length. The first and second stoppers protrude from at least either the surface on the back plate near the air gap or the surface on the diaphragm near the air gap. The first stopper is provided at a position corresponding to a first position on the diaphragm. The second the stopper is provided at a position corresponding to a second position on the diaphragm. An amount of displacement of the diaphragm at the first position is greater than an amount of displacement of the diaphragm at the second position. The protruding length of the first stopper is shorter than the protruding length of the second stopper.