Optical Microphone Dual Light Source Differential Measurement
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Solution Overview
Problem
Conventional optical microphones face challenges in achieving optimal acoustic-optical conversion performance, which is essential for enhancing user experience.
Innovation Solution
The optical microphone incorporates a dual light source configuration with a MEMS module, two photoelectric modules, and an ASIC module, featuring a flexible membrane and gratings to facilitate differential measurement, improving signal conversion through refractive and reflective mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light source is used in the optical microphone, then the device complexity is low, but the acoustic-optical conversion performance is insufficient
Solution Approach 1:
The patent divides the single light detection function into two separate photoelectric modules, each with its own light source. This segmentation allows independent optimization of each module's performance while enabling differential measurement techniques that improve overall acoustic-optical conversion accuracy and signal-to-noise ratio.
Solution Approach 2:
The patent combines two photoelectric modules with dual light sources into a single integrated optical measurement system. This merging enables differential measurement where the outputs of both modules are processed together, improving acoustic-optical conversion performance through noise cancellation and enhanced signal detection while maintaining a unified device architecture.
2Measurement precision
If gratings are placed close to the flexible membrane for compact design, then the device complexity is reduced, but the light diffraction and measurement precision are affected
Solution Approach 1:
The patent employs asymmetric positioning of the gratings relative to the flexible membrane, with each grating placed at an optimized distance and angle. This asymmetric arrangement allows the gratings to be positioned at optimal locations for light diffraction measurement precision while maintaining a compact overall structure, rather than using symmetric placement that would compromise either precision or compactness.
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 microphone's performance by creating differential signals, leading to improved acoustic-optical signal conversion and electrical signal generation, thereby addressing the limitations of conventional microphones.
Implementation Method 1
A part of light emitted by the light source of one photoelectric module of the two photoelectric modules is diffracted by one grating of the two gratings adjacent to the photoelectric module
Implementation Method 2
reflected back to the light detector of the one photoelectric module through the flexible membrane
Implementation Method 3
When the light emitted by the light source is vertically irradiated on the lens, the light is refracted by the lens and then obliquely irradiated to the grating. When the light reflected by the grating or the flexible membrane is obliquely irradiated to the lens, the reflected light is refracted by the lens and then vertically irradiated on the light detector
Implementation Method 4
The photoelectric module then converts intensity and phase signals of the reflected light into electrical signals and transmits the electrical signals to the ASIC module
Data Source
AI summary
An optical microphone with a dual light source is provided. The optical microphone includes: a housing including an inner cavity and a sound inlet communicating the inner cavity with the outside; a MEMS module disposed in the inner cavity and including a flexible membrane and two gratings; two photoelectric modules, one being disposed in a front cavity and the other in a rear cavity, and each of the photoelectric modules including a light source and a light detector; and an ASIC module disposed in the rear cavity and electrically connected to the photoelectric modules. The optical microphone provides differential measurement, such that the output signal change on one of the two sides of the flexible membrane is positive and the output signal change on another side of the flexible membrane is negative. Therefore, a differential measurement structure is formed to improve the performance of the microphone.