Directional MEMS Microphone Using Phase Delay for Noise Reduction
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Solution Overview
Problem
Existing MEMS microphones require two microphones and a digital signal processor to achieve directional properties, increasing cost and power consumption.
Innovation Solution
A directional MEMS microphone design using a single MEMS microphone with a phase delay controller and filter to generate and delay sound signals, allowing for directional properties without a separate digital signal processor, and an operating method that synthesizes antiphase sound signals to produce an output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two MEMS microphones and a digital signal processor are used to implement directional property, then directional recognition capability is improved, but cost and power consumption increase
Solution Approach 1:
The patent combines the functions of two separate MEMS microphones and a digital signal processor into a single integrated MEMS microphone device. The first and second sound signal generators are integrated within one microphone housing, with their outputs combined through a summing circuit to produce the directional effect, eliminating the need for separate processing hardware.
Solution Approach 2:
The patent introduces a phase delay circuit as an intermediary component between the second sound signal generator and the summing circuit. This phase delay circuit processes the second sound signal to create the necessary phase difference that enables directional recognition, replacing the need for complex digital signal processing while maintaining the directional effect.
2Measurement precision
If two MEMS microphones and a digital signal processor are used to implement directional property, then directional recognition capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple discrete components (two MEMS microphones, phase processing circuitry, and signal combining logic) into a single integrated device. The first and second sound signal generators are housed together with their output combining circuitry, reducing the component count from three separate devices to one unified microphone assembly.
Solution Approach 2:
The patent replaces the digital signal processor (electronic/digital system) with an analog phase delay circuit and summing circuit. This substitution eliminates the need for complex digital processing hardware while achieving the same directional recognition function through analog signal manipulation.
3Measurement precision
If phase delay is applied to rear sound signal based on distance between sound holes, then directional accuracy is improved, but device complexity increases
Solution Approach 1:
The patent adjusts the phase delay parameter of the second sound signal based on the physical distance between the front sound hole and rear sound hole. By changing the phase delay parameter to match the spatial separation, the system achieves accurate directional recognition without requiring complex adaptive control mechanisms.
Solution Approach 2:
The patent pre-calculates and sets the phase delay value based on the fixed distance between sound holes during device manufacturing. This preliminary configuration eliminates the need for real-time measurement and adjustment during operation, simplifying the control mechanism while maintaining directional accuracy.
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
Reduces cost and power consumption while improving telephone speech quality and voice recognition efficiency by eliminating the need for additional hardware and effectively removing noise.
Implementation Method 1
First and second MEMS dies are disposed on the board in the space of the case and convert sound sources coming through the respective holes into electric signals
Implementation Method 2
A filter is disposed in the space of the case with a bottom of which faces the rear sound hole and parts of both sides of which are bonded to the board so as to delay a phase of the rear sound coming through the rear sound hole
Data Source
AI summary
A directional microphone and an operating method thereof include a first signal generator generating a first sound signal corresponding to a front sound coming through a front sound hole of the directional microphone. A second signal generator generates a second sound signal corresponding to a rear sound coming through a rear sound hole of the directional microphone. A phase delay controller delays a phase of the rear sound coming through the rear sound hole, and a signal processor synthesizes the first sound signal and the second sound signal.