Electromagnetic Microphone Structure to Eliminate Back Plate Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional microphones, including MEMS microphones, suffer from high impedance, high noise, and absorption issues due to the use of flexible membranes and fixed back plates, leading to reduced reliability.
Innovation Solution
An electromagnetic microphone design that eliminates the back plate and utilizes an anisotropic magnetic field generated by a magnetic component on a membrane, integrated with a coil and circuit board, to convert sound waves into electrical signals through electromagnetic induction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitance technology with flexible membrane and fixed back plate is used, then acoustic-electric conversion is achieved, but high impedance and high noise occur leading to reduced reliability
Solution Approach 1:
The patent removes the fixed back plate from the traditional capacitor microphone structure, extracting the source of absorption problems and impedance issues. By eliminating the back plate, the system avoids the harmful interactions between the membrane and back plate that cause high impedance and noise, while maintaining acoustic-electric conversion functionality through the electromagnetic transducer.
Solution Approach 2:
The patent replaces the capacitive detection mechanism (mechanical-electrical conversion through capacitance change) with an electromagnetic transducer system. The electromagnetic transducer uses a magnetic component and coil to convert membrane vibration directly into electrical signals through electromagnetic induction, avoiding the high impedance and noise problems inherent in capacitive technology.
2Reliability
If absorption between membrane and back plate occurs, then structural simplicity is maintained, but reliability deteriorates
Solution Approach 1:
The fixed back plate is completely removed from the structure, eliminating the absorption interface between membrane and back plate. The back cavity is left open, allowing sound waves to pass through without being absorbed by a back plate, thereby preventing the harmful absorption effect while maintaining structural simplicity.
3Measurement precision
If anisotropic magnetic field is generated by magnetic component, then sensitivity is improved, but device complexity increases
Solution Approach 1:
The magnetic component is designed to generate an anisotropic magnetic field with specific directional properties localized at the membrane position. This localized anisotropic field configuration optimizes the interaction with the coil for detecting membrane vibration in the specific direction of sound wave propagation, improving sensitivity without requiring complex global magnetic field arrangements.
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 enhances reliability and sensitivity by reducing stiffness and improving stability through closed-loop force feedback control, while maintaining acoustic-electric conversion efficiency.
Implementation Method 1
the magnetic component and the coil interact to generate electrical signal
Data Source
AI summary
The present disclosure discloses an electromagnetic microphone including: a housing; a circuit board; and a sound transducer, including: a substrate including a back cavity, a vibrator mounted on a side of the substrate away from the circuit board and covering the back cavity, including: a membrane; and a magnetic component mounted on the membrane and configured to generate magnetic field; a coil located within the magnetic field of the magnetic component; a sound hole penetrated on the housing or the circuit board is configured to communicate with the back cavity; when external sound wave transmitted from the sound hole and the back cavity acts on the membrane, the magnetic component and the coil interact to generate electrical signal. The electromagnetic microphone in the present disclosure has higher sensitivity, reliability and stability.