Condenser Microphone Grounding via High-Frequency Choke Coil
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Solution Overview
Problem
Condenser microphones are susceptible to noise from high-frequency electromagnetic noise, and existing methods to prevent this can lead to electric shocks when the grounding pin detaches, as they allow phantom power to pass through the microphone case.
Innovation Solution
A condenser microphone design where the grounding pin of the output connector is directly connected to the microphone case and also to the electronic circuit's ground via a high-frequency choke coil, preventing electromagnetic noise entry and ensuring the microphone case's potential remains stable even if the pin detaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the grounding first pin is coupled directly to the microphone case to prevent electromagnetic wave entry, then noise from electromagnetic waves is prevented, but the microphone case may reach high potential (30 V or higher) if the pin detaches, causing electric shock
Solution Approach 1:
A high-frequency choke coil is introduced as an intermediary component between the grounding first pin and the microphone case. This choke coil allows the grounding function to be maintained while blocking high-frequency electromagnetic waves. The choke coil acts as a frequency-selective element that permits DC and low-frequency signals to pass while impeding high-frequency noise, thus preventing both electromagnetic wave entry and potential electric shock risks.
2Object-affected harmful factors
If the grounding first pin is coupled directly to the microphone case, then electromagnetic wave entry is prevented, but phantom power current passes through the microphone case
Solution Approach 1:
The high-frequency choke coil changes the electrical parameters at different frequencies. At DC and low frequencies (phantom power range), the choke coil has low impedance, allowing current to pass through. At high frequencies (electromagnetic noise range), the choke coil presents high impedance, blocking the noise. This frequency-dependent parameter change enables the simultaneous transmission of phantom power and blocking of electromagnetic waves.
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
Effectively blocks high-frequency electromagnetic noise from entering the electronic circuit and prevents electric shocks by ensuring the microphone case's potential remains stable, even if the grounding pin becomes detached.
Implementation Method 1
a ground pin included in the output connector is connected directly to the microphone case and is also connected to a ground of the electronic circuit via a high-frequency choke coil
Implementation Method 2
the grounding first pin is coupled directly to the microphone case and is also coupled to a ground of the electronic circuit via a high-frequency choke coil
Data Source
AI summary
The present invention prevents the occurrence of noise caused by an external electromagnetic wave. The present invention also prevents a high voltage from appearing in the microphone case, thus avoiding the possibility of an electric shock. A condenser microphone includes a conductive microphone case 10 containing an electronic circuit 20 for a condenser microphone unit and a 3-pin type output connector 30 attached to the microphone case 10 and to which a microphone cable 40 from an external apparatus including a polarization power source is connected. A first pin for grounding included in the output connector 30 is connected directly to the microphone case 10 and is also connected to a ground of the electronic circuit 20 via a high-frequency choke coil 31.