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What is a electret microphone?
Abstract：A electret microphone monomer, also known as a electret microphone monomer, is a capacitive microphone with a built-in permanent charge. The following is a detailed introduction to the electret microphone monomer:
A electret microphone monomer, also known as a electret microphone monomer, is a capacitive microphone with a built-in permanent charge. The following is a detailed introduction to the electret microphone monomer:
First, the working principle
The working principle of electret microphones is based on the capacitive principle. It consists of a vibrating film coated with metal on one side (electret vibrating film) and a metal electrode (back pole) with a number of small holes and attached to the electret film. The electret surface is opposite to the vibrating film, and there is a small air gap in the middle, forming a dielectric capacitor with the air gap and electret as the insulating medium, and the metal layer on the back pole and the vibrating film as the two electrodes. There is a free charge distributed on the electret, when the sound wave makes the vibration film vibrate, it will change the capacitance of the capacitor, and then generate the corresponding alternating electric field at the output end of the capacitor, this alternating electric field acts on the input resistance of the impedance converter or preamplifier, and forms the electrical signal corresponding to the acoustic signal, completing the acoustoelectric conversion.
Second, structural characteristics
Electret microphone is mainly composed of diaphragm, electret, back plate and impedance converter. Among them, the diaphragm is a key component of acoustoelectric conversion, it is an extremely thin plastic film, on one side of the evaporation of a layer of metal film, and through high voltage electric field electret treatment, so that both sides are respectively stationed with opposite charges. The back plate is a metal electrode with a number of small holes that form a capacitor with the diaphragm. Impedance converters typically use field-effect tubes (FETs), which convert a high-impedance output signal to a low-impedance one in order to match it with an audio amplifier.
3. Performance parameters
The performance parameters of electret microphone include output impedance, sensitivity, frequency response, signal-to-noise ratio (S/N), directivity and so on. These parameters are affected by many factors such as diaphragm material, tension, electret surface charge density, back plate aperture and number, impedance converter performance, etc. For example, the sensitivity is proportional to the electret surface charge density, but inversely proportional to the membrane tension; The frequency response is affected by the diaphragm tension, the aperture and number of the back plate and the volume of the back cavity.
Fourth, the production process
The production process of electret microphone monomer includes material preparation, vibration film production, back plate processing, assembly, testing and debugging, and packaging. Among them, the production of vibrating film and the processing of the back plate are the key links, which need to strictly control the size and accuracy. The assembly link needs to pay special attention to the distance and position relationship between the diaphragm and the back plate to ensure the stable performance of the microphone. The test and debugging step is used to detect the microphone's sensitivity and frequency response and other performance parameters, and make necessary adjustments.
5. Application fields
Electret microphones are widely used in consumer electronics, communication, computer and other fields because of their small size, simple structure, good electroacoustic performance and low price. For example, it can be used as a built-in microphone for mobile phones, a recording device for computers, a microphone for headphones, and so on. In addition, electret microphones can also be used in scientific research fields such as gas analysis and determination of pollutant concentrations in the atmosphere.
In summary, electret microphone monomer is a capacitive microphone with excellent performance and wide application. Through strict control of production process and performance parameters, electret microphone monomer can be produced to meet the needs of various applications.
First, the working principle
The working principle of electret microphones is based on the capacitive principle. It consists of a vibrating film coated with metal on one side (electret vibrating film) and a metal electrode (back pole) with a number of small holes and attached to the electret film. The electret surface is opposite to the vibrating film, and there is a small air gap in the middle, forming a dielectric capacitor with the air gap and electret as the insulating medium, and the metal layer on the back pole and the vibrating film as the two electrodes. There is a free charge distributed on the electret, when the sound wave makes the vibration film vibrate, it will change the capacitance of the capacitor, and then generate the corresponding alternating electric field at the output end of the capacitor, this alternating electric field acts on the input resistance of the impedance converter or preamplifier, and forms the electrical signal corresponding to the acoustic signal, completing the acoustoelectric conversion.
Second, structural characteristics
Electret microphone is mainly composed of diaphragm, electret, back plate and impedance converter. Among them, the diaphragm is a key component of acoustoelectric conversion, it is an extremely thin plastic film, on one side of the evaporation of a layer of metal film, and through high voltage electric field electret treatment, so that both sides are respectively stationed with opposite charges. The back plate is a metal electrode with a number of small holes that form a capacitor with the diaphragm. Impedance converters typically use field-effect tubes (FETs), which convert a high-impedance output signal to a low-impedance one in order to match it with an audio amplifier.
3. Performance parameters
The performance parameters of electret microphone include output impedance, sensitivity, frequency response, signal-to-noise ratio (S/N), directivity and so on. These parameters are affected by many factors such as diaphragm material, tension, electret surface charge density, back plate aperture and number, impedance converter performance, etc. For example, the sensitivity is proportional to the electret surface charge density, but inversely proportional to the membrane tension; The frequency response is affected by the diaphragm tension, the aperture and number of the back plate and the volume of the back cavity.
Fourth, the production process
The production process of electret microphone monomer includes material preparation, vibration film production, back plate processing, assembly, testing and debugging, and packaging. Among them, the production of vibrating film and the processing of the back plate are the key links, which need to strictly control the size and accuracy. The assembly link needs to pay special attention to the distance and position relationship between the diaphragm and the back plate to ensure the stable performance of the microphone. The test and debugging step is used to detect the microphone's sensitivity and frequency response and other performance parameters, and make necessary adjustments.
5. Application fields
Electret microphones are widely used in consumer electronics, communication, computer and other fields because of their small size, simple structure, good electroacoustic performance and low price. For example, it can be used as a built-in microphone for mobile phones, a recording device for computers, a microphone for headphones, and so on. In addition, electret microphones can also be used in scientific research fields such as gas analysis and determination of pollutant concentrations in the atmosphere.
In summary, electret microphone monomer is a capacitive microphone with excellent performance and wide application. Through strict control of production process and performance parameters, electret microphone monomer can be produced to meet the needs of various applications.
