Variable-Directivity MEMS Microphone With Integrated Signal Processing
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Solution Overview
Problem
Existing MEMS microphones require multiple devices to achieve variable directivity, increasing costs and device volume.
Innovation Solution
A variable-directivity MEMS microphone with an acoustic cavity containing a first and second acoustic transducer, pre-amplifiers, and a signal processing chip that generates directional output signals through phase delay and arithmetic operations on electric signals, allowing for omnidirectional, splayed, or cardioid directivity switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple microphones are provided to achieve variable directivity, then directivity switching capability is improved, but device volume and cost increase
Solution Approach 1:
The patent combines multiple microphones (first and second acoustic transducers) into a single integrated structure within one acoustic cavity, sharing common components such as the substrate, cover, and signal processing chip. This merging approach maintains the ability to achieve multiple directivity patterns while reducing the overall device volume compared to using separate microphone modules.
Solution Approach 2:
The signal processing chip serves multiple functions: it processes signals from both acoustic transducers, performs phase delay operations, executes arithmetic operations (addition/subtraction), and generates different directivity patterns (omnidirectional, splayed, cardioid). This multi-functionality eliminates the need for separate processing circuits for each microphone, reducing device volume.
2Adaptability or versatility
If multiple microphones are provided to achieve variable directivity, then directivity switching capability is improved, but cost increases
Solution Approach 1:
By integrating multiple microphones and their processing circuits into a single device structure with shared components (substrate, cover, signal processing chip), the patent reduces the total component count and assembly complexity, thereby lowering manufacturing costs compared to using separate microphone modules.
Solution Approach 2:
The signal processing chip performs all necessary signal processing functions for both microphones, including phase delay, arithmetic operations, and directivity pattern generation. This universal processing approach eliminates the need for separate processing circuits for each microphone, reducing overall device cost.
3Volume of moving object
If a single microphone is used to reduce device volume, then directivity switching capability deteriorates
Solution Approach 1:
The patent employs dynamic signal processing techniques including phase delay (controlled by adjustable resistors and capacitors) and arithmetic operations (addition/subtraction) to dynamically change the directivity pattern of the microphone. The phase delayer and adder-subtractor circuits can be adjusted to produce different directivity patterns (omnidirectional, splayed, cardioid) from a single microphone structure.
Solution Approach 2:
The patent changes signal processing parameters (phase delay amount, arithmetic operation type) to achieve different directivity patterns. By adjusting the phase delay parameter and selecting different arithmetic operations on the signals from the acoustic transducers, the system can switch between omnidirectional, splayed, and cardioid directivity patterns using a single microphone.
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
Enables a single microphone to provide multiple directivity outputs, reducing device volume and improving reliability by processing electric signals to generate directional output signals, thus eliminating the need for multiple microphones.
Implementation Method 1
a first acoustic transducer for detecting an acoustic signal and converting the acoustic signal into a first acoustic conversion signal
Implementation Method 2
a second acoustic transducer for detecting an acoustic signal and converting the detection acoustic signal into a second acoustic conversion signal
Data Source
AI summary
The invention relates to a variable-directivity MEMS microphone. The microphone comprises an acoustic cavity. The following components are provided inside the acoustic cavity: a first acoustic transducer for detecting an acoustic signal and converting the acoustic signal into a first acoustic conversion signal; a first pre-amplifier, connected to the first acoustic transducer, and configured for outputting a first electric signal; a second acoustic transducer for detecting an acoustic signal and converting the acoustic signal into a second acoustic conversion signal; a second pre-amplifier, connected to the second acoustic transducer, and configured for outputting a second electric signal; and a signal processing chip, connected to the first pre-amplifier and the second pre-amplifier, and configured for generating a directional output signal by performing an arithmetic operation on the first electric signal and the second electric signal under the action of a switching control signal.