Single-Element MEMS Microphone with Segmented Electrodes for Directional Sound
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Solution Overview
Problem
Current directional MEMS microphones require multiple digital MEMS microphones and a DSP chip, making them costly and impractical for vehicle applications, where a single-element directional microphone with improved noise resistance is needed.
Innovation Solution
A single-element microphone design featuring a plurality of vibration membrane electrodes and fixing membrane electrodes forming unit capacitors, with specific patterns and phases to enhance directivity, allowing for directional sound reception without the need for multiple microphones or a DSP chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple digital MEMS microphones and a DSP chip are arranged in an array type to apply beam forming technique, then directivity is improved, but manufacturing cost increases excessively
Solution Approach 1:
The single microphone element is segmented into multiple vibration membrane electrodes (first, second, third, and fourth electrodes) arranged in specific spatial positions. Each electrode functions as an independent sensing unit, allowing directional sound detection through differential capacitance measurement without requiring multiple complete microphone assemblies or complex DSP processing.
Solution Approach 2:
The invention transitions from a single-point sensing approach to a distributed spatial arrangement of multiple vibration membrane electrodes within a single microphone element. By positioning electrodes at different locations (front, rear, left, right sides) and utilizing their differential responses to sound waves from different directions, the system achieves beam-forming capability in a single element without requiring multiple stacked microphones.
2Object-affected harmful factors
If multiple digital MEMS microphones are used to achieve directional sound reception, then noise resistance is improved, but device complexity increases
Solution Approach 1:
Multiple vibration membrane electrodes that would traditionally require separate microphone assemblies are merged into a single integrated microphone element. The first and second vibration membrane electrodes are positioned on opposite sides of the acoustic cavity, as are the third and fourth electrodes. This merging allows the system to achieve noise rejection through differential measurement while maintaining a compact single-element structure.
Solution Approach 2:
Different regions of the acoustic cavity are assigned different sensing functions through strategically positioned vibration membrane electrodes. The front and rear electrodes (first and second) are optimized for detecting sounds from the front direction, while the left and right electrodes (third and fourth) provide additional directional information. This local differentiation enables the system to identify and suppress noise from unwanted directions while amplifying signals from the desired direction.
3Device complexity
If a single element directional microphone is designed, then manufacturing cost is reduced, but achieving directivity becomes more difficult
Solution Approach 1:
The vibration membrane electrodes are positioned asymmetrically within the acoustic cavity to create directional sensitivity. The first and second vibration membrane electrodes are positioned at the front and rear sides, while the third and fourth electrodes are positioned at the left and right sides. This asymmetric spatial arrangement, combined with differential capacitance measurement, enables the single element to detect the direction of incoming sound waves without requiring complex processing.
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 design achieves directivity in a single element, reducing manufacturing costs and improving noise resistance in noisy environments, such as those found in vehicles, by effectively combining unit output signals to maximize signal amplitude from the desired sound direction.
Implementation Method 1
a plurality of vibration membrane electrodes and a plurality of fixing membrane electrodes which respectively face the plurality of vibration membrane electrodes and form a plurality of unit capacitors along with the facing vibration membrane electrodes
Data Source
AI summary
A microphone includes a plurality of vibration membrane electrodes, and a plurality of fixing membrane electrodes that respectively faces the plurality of vibration membrane electrodes and forms a plurality of unit capacitors along with the facing vibration membrane electrodes, wherein the plurality of unit capacitors generates a plurality of unit output signals according to inputs of a power source and a sound source, and outputs a signal combining the plurality of unit output signals as an output signal corresponding to the sound source.