Ultrasonic humidifier principle detailed explanation
The humidifier is a kind of electric appliance that can make the air moist. According to the humidification principle, it is generally divided into three categories: hot humidification type, fan humidification type and ultrasonic humidification type; it is divided into household and commercial according to the purpose. ,industrial use.
Ultrasonic humidifier principle
The principle of ultrasonic humidifier is to use over-frequency oscillation (oscillation frequency is 1.7MHz, also has 2.4MHz), by using the high-frequency resonance of the atomizing sheet, the water droplets are broken into tiny floating particles of about 5 microns, in the role of the fan or In the natural state, it is far away from the water surface, which continuously produces suspended water mist, and finally achieves the effect of air humidification. Since 1.7 MHz exceeds human ear hearing, the ultrasonic humidifier is thus derived.
Ultrasonic humidifier generally has the following components: power supply, power switch, water level detection, fog control, working status display, fan output control, atomizer, etc.
1, power supply
The power supply part is generally two-way input. One way is to supply power to the fan. One way is to supply power to the shock board. If the shock board and the fan voltage are the same, you can do it all the way. If the power board uses a transformer, it supplies power to the oscillating circuit and the fan after step-down, rectification, and filtering. This relative switching power supply circuit is simple and simple, but the transformer is too bulky, especially for the mini humidifier. It can be said that it is a burden, but the use of switching power supply circuit design is sometimes more complicated, depending on the actual situation.
2, power switch
Here, the power switch function is to turn on the power. If the potentiometer adjusts the amount of fog, the position at which the potentiometer starts is the position where the power is turned on. When the rotary potentiometer turns on the power, it also starts to adjust the amount of humidification, but if it is controlled by PWM signal If this, the connection position can be directly shorted.
3, water level detection
Water level detection is now mostly used with a reed switch and a magnetic ring to detect the lack of water. The reed switch is a magnetically 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 when a sufficient magnetic field is encountered. Therefore, when there is no shortage of water, the magnetic ring is floated by the water, the magnetic field causes the reed switch to close, the control board detects a change in the signal, the oscillating circuit starts to work, the green indicator light illuminates, and at the same time, humidification is turned on; when the water is deficient, the water surface drops. The magnetic ring is moved away from the reed switch. At this time, the reed switch contact is opened, the humidifier stops humidifying and disconnects all outputs, and the red color indicates a water shortage state. Another is the surface probe to detect water shortage, which is less of an application.
4, fog control
The fog amount adjustment is generally regulated in two ways: the PWM signal and the potentiometer. If the potentiometer is adjusted, many humidifiers are basically realized by adjusting the bias of the oscillating tube, and the PWM signal is for a signal input, whether it is potentiometer or PWM regulation, in fact, it is basically adjusted. The voltage input size is adjusted by the partial pressure principle. In general, a mechanical humidifier is regulated by a potentiometer, while an electronic humidifier is controlled by a PWM signal.
5, work status display
Here, the red and green two-color lights are used to indicate the humidification and the lack of water and humidification. When the water is short, the female yellow switch contacts are released, and the red LED lights up, indicating that the water is lacking at this time; when there is no water shortage, the female yellow switch The contacts are closed and the green LED lights up, indicating that there is no water shortage at this time. It is also possible to display different working states using a digital screen or the like.
6, fan output control
The fan voltage is generally 12V, 24V, 36V, etc. The shock plate breaks up the water droplets into tiny particles and is continuously blown away by the fan. This continuously forms a water mist. When the water shortage is detected, the fan is also turned off. The fan can also be on the control board to see the specific oscillating board circuit.
The atomizing sheet is made of a ceramic material, which can be used to break the water droplets into a special object by means of high frequency oscillation, which is generally circular, and the two wires are shielded.
Nowadays, the development of humidifiers is becoming more and more mature, and the shock plate is also becoming more modular. Some shock plates also have anti-dry function. Generally only need to design control circuit, power supply circuit, display circuit, and the function is more and more complicated, some humidifiers also have UV lamp sterilization function, with temperature, humidity automatic control function, with negative ion function, etc.
1 When a large amount of negative ions are released during humidification and atomization, electrostatic effects are generated by particles such as dust floating in the air to precipitate, and the air can be purified while humidifying the air;
2 The dry environment is prone to respiratory diseases, and humid air can reduce the incidence of diseases.