Differential Electroacoustic Converter for Common-Mode Noise Rejection
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Solution Overview
Problem
Audio devices are susceptible to common mode noise during acoustic signal to electrical signal conversion, leading to contamination of signal quality, especially in noisy environments.
Innovation Solution
An electroacoustic converter with differential amplifier configuration, featuring capacitive sensing membranes with spacers at reentrant and tip vertices, producing capacitance variations of opposite polarities that are amplified to reject common mode noise, ensuring superior sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic signal to electrical signal conversion is performed using conventional methods, then the conversion process is simple, but the device is susceptible to common mode noise and signal quality is contaminated
Solution Approach 1:
The patent divides the electroacoustic conversion process into two separate conversion paths. Instead of using a single converter, it employs two independent electroacoustic converters, each converting acoustic signals to electrical signals through separate capacitance variations. This segmentation allows the system to process differential signals and reject common mode noise, thereby improving signal quality while maintaining reasonable device complexity.
Solution Approach 2:
The patent introduces a differential amplifier as an intermediary component between the two electroacoustic converters and the output. This differential amplifier processes the two electrical signals by amplifying their difference while rejecting common mode components, effectively eliminating noise contamination. The intermediary plays a crucial role in transforming the segmented signals into a clean differential output.
2Reliability
If differential amplifier configuration is used to reject common mode noise, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of two electroacoustic converters and a differential amplifier into a unified differential conversion system. By combining these components, the system achieves noise rejection capability while presenting a compact integrated solution. The merging of multiple functional elements into a cohesive system reduces the perceived complexity compared to separate independent components.
Solution Approach 2:
The patent utilizes parameter changes in the capacitance variations of the two electroacoustic converters. By ensuring that the capacitance variations occur in opposite polarities, the system creates differential signals that can be processed by the differential amplifier. This parameter change strategy enables noise rejection without requiring complex filtering or processing circuits.
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 solution effectively suppresses common mode noise, enhancing signal-to-noise ratio and maintaining superior sound quality even in noisy environments by converting differential capacitance variations into single-ended signals.
Implementation Method 1
A first polarity of a first capacitance variation corresponding to the first output terminal is opposite to a second polarity of a second capacitance variation corresponding to the second output terminal. The first capacitance variation and the second capacitance variation are associated with a magnitude of acoustic pressure.
Implementation Method 2
The upper electrode or a layer of the lower electrode has permanent electric charges.
Data Source
AI summary
An audio device includes an electroacoustic convertor and a differential amplifier. The electroacoustic convertor has a first output terminal and a second output terminal. A first polarity of a first capacitance variation corresponding to the first output terminal is opposite to a second polarity of a second capacitance variation corresponding to the second output terminal. The first capacitance variation and the second capacitance variation are associated with a magnitude of acoustic pressure. The differential amplifier has a first input terminal coupled to the first output terminal and a second input terminal coupled to the second output terminal.