Principle of Ultrasonic Humidifier

　　The principle of the ultrasonic humidifier is to use overfrequency oscillation (the oscillation frequency is 1.7MHz, and there are also 2.4MHz), and by using the high-frequency resonance of the atomizing sheet, the water droplets are broken into tiny floating particles of about 5 microns, which are used in the fan or the fan. In a natural state, stay away from the water surface, so that the suspended water mist is continuously generated, and finally the effect of moisturizing the air is achieved. Because 1.7MHz exceeds the human ear hearing, so the ultrasonic humidifier is derived from it.

　　1. Power supply

　　The power supply part is generally two-way input, one is to supply power to the fan, and the other is to supply power to the vibration board. If the vibration board has the same voltage as the fan, it can be used as one channel. If the power supply board uses a transformer, after step-down, rectification and filtering, the oscillation circuit and the fan are powered. This is relatively simple and simple compared to the switching power supply circuit, but the transformer is also too bulky, especially for mini humidifiers. It can be said to be a burden, but the circuit design of switching power supply is sometimes a little more complicated, depending on the actual situation.

　　2. Power switch

　　The function of the power switch here is to turn on the power. If the potentiometer adjusts the fog volume, the starting position of the potentiometer is the position where the power is turned on. When the potentiometer turns on the power, it also starts to adjust the humidification volume, but if the PWM signal is used to control If so, this connection position can be directly short-circuited.

　　3. Water level detection

　　Most of the water level detection now uses a magnetic reed switch and a magnetic ring to detect whether there is water shortage. A reed switch is a magnetic sensitive switch, usually made of two soft magnetic materials. Simply put, the two reeds are not in contact when there is no external magnetic field, and will close once they encounter a sufficient magnetic field. Therefore, when there is no water shortage, the magnetic ring is floated by the water, the magnetic field closes the magnetic reed switch, the control board detects that the signal changes, the oscillation circuit starts to work, the green indicator lights up, and the humidification is turned on at the same time; Cause the magnetic ring to be far away from the reed switch. At this time, the contact of the reed switch is opened, the humidifier stops humidifying and disconnects all outputs, and the red shows the water shortage state at this time. There is also a water surface probe to detect water shortage, which is less used.

　　4. Fog volume control

　　There are generally two ways to adjust the fog volume: PWM signal and potentiometer. If it is a potentiometer adjustment, many humidifiers are basically realized by adjusting the bias of the oscillator tube, and the PWM signal is a signal input, whether it is a potentiometer or PWM adjustment, in the final analysis, it is adjusted by adjusting The size of the voltage input is adjusted by the principle of voltage division. Generally, the mechanical humidifier is adjusted by a potentiometer, while the electronic humidifier is controlled by a PWM signal.

　　5. Working status display

　　Here, the red and green two-color lights are used to indicate the two states of humidification and water shortage without humidification. When there is water shortage, the female-yellow switch contacts are released, and the red LED lights up at the same time, indicating that there is water shortage at this time; when there is no water shortage, the female-yellow switch The contacts are closed, and the green LED lights up at the same time, indicating that there is no shortage of water at this time. You can also use a digital screen to display different working states.

　　6. Fan output control

　　The fan voltage is generally 12V, 24V, 36V, etc. The shock board breaks up the water droplets into tiny particles and continuously blows them away through the fan, so that water mist is continuously formed. When the water shortage is detected, the fan is also turned off at the same time. fan also

　　You can see the specific oscillator board circuit on the control board.

　　7. Atomizing tablets

　　The atomizing sheet is a special object made of a ceramic material, which can disperse water droplets into water mist through high-frequency oscillation. It is generally round, and the two wires are shielded.

　　Now the development of humidifiers is becoming more and more mature, and the vibration plate is also becoming more modular, and some vibration plates also have their own anti-dry function. Generally, only control circuit, power supply circuit and display circuit need to be designed, and the functions are more and more complicated. Some humidifiers also have UV lamp sterilization function, automatic temperature and humidity control function, negative ion function, etc.

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