Dual Backplate Microphone Membrane Positioning via Bias Voltage
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Solution Overview
Problem
Dual backplate microphones face challenges in achieving precise membrane positioning between the two backplates due to limitations in manufacturing precision, affecting their performance and accuracy.
Innovation Solution
A method and system that utilize adjustable bias voltages applied to the membrane and backplates, controlled by a unit comprising analog and logic circuitry, to correct and optimize the membrane's position between the backplates, allowing for precise positioning and adjustment after manufacturing, using voltage pumps and capacitance measurements to achieve electro-mechanical equilibrium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manufacturing precision is improved to achieve accurate membrane positioning, then microphone performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by positioning the membrane between the backplates with approximate alignment during manufacturing, then using post-manufacturing voltage adjustment to achieve precise positioning. This allows the membrane to be roughly positioned during assembly and then finely adjusted electrically, avoiding the need for extremely precise mechanical manufacturing while achieving the desired positioning accuracy.
Solution Approach 2:
The patent changes physical parameters by applying different voltages to the membrane after manufacturing to adjust its position. By varying the voltage applied to the membrane, the electrostatic force changes, which adjusts the membrane's equilibrium position between the backplates, thereby achieving precise positioning without requiring high manufacturing precision.
2Manufacturing precision
If manufacturing precision is increased to ensure accurate membrane positioning, then microphone performance increases, but production time and cost increase
Solution Approach 1:
The membrane is preliminarily positioned during manufacturing without requiring high precision, allowing faster production. The fine-tuning of membrane position is deferred to a post-manufacturing step using voltage adjustment, which does not require additional manufacturing time but achieves the required positioning accuracy.
Solution Approach 2:
The patent replaces mechanical positioning adjustments with an electrical system. Instead of using mechanical means to precisely position the membrane during manufacturing, an electrical field is used to adjust the membrane position after manufacturing, thereby increasing manufacturing efficiency while maintaining positioning accuracy.
3Device complexity
If the membrane position is fixed during manufacturing, then device simplicity is maintained, but positioning accuracy is insufficient
Solution Approach 1:
The patent makes the membrane positioning dynamic by allowing adjustment of the membrane position through voltage changes after manufacturing. The membrane position is not fixed mechanically but can be dynamically adjusted by changing the applied voltage, enabling precise positioning while maintaining a simple mechanical structure.
Solution Approach 2:
The patent introduces voltage as an intermediary to adjust membrane position. By applying different voltages to the membrane, the electrostatic force acts as a mediator to shift the membrane to the desired position between the backplates, achieving accurate positioning without complex mechanical adjustment mechanisms.
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 significantly increases the precision of membrane positioning, leading to improved acoustic symmetry, enhanced sound pressure handling, and reduced harmonic distortion in dual backplate microphones.
Implementation Method 1
if a bias voltage is applied between the membrane and one of the backplates a capacitor formed by the membrane and the respective backplate is charged. Accordingly, electrostatic force acts between the membrane and the backplate
Data Source
AI summary
A microphone includes two backplates. A membrane is located between the two backplates. A voltage source applies a first bias voltage to the membrane and the first backplate and applies a second bias voltage to the membrane and the second backplate. A control unit adjusts the first and the second bias voltage. A method to center the membrane in a final electro-mechanic equilibrium position between the two backplates in a microphone is also disclosed.