Living in a hotel feels not as comfortable as in your own home, but some humanized designs are better, such as lights inside the wardrobe, and the door can be opened automatically. This time, I will talk about why the wardrobe lights can achieve "closed door off, open door bright"? The common implementation methods are as follows:

　　1. Mechanical switch

　　This method is the same as we usually use the switch to control the light on and off, but some methods are adopted to make the opening and closing of the cabinet door link the switch, so as to achieve the effect of controlling the light on and off of the wardrobe. To accomplish this task, usually use a special switch - micro switch, the micro switch is closed by lightly touching the complete open.

　　Why can the wardrobe lights realize automatic control on and off?

　　This method is less costly to implement, but as the mechanical structure is continuously used, aging will occur, and the possibility of "failure" is getting higher and higher. Now this kind of solution is relatively rare.

　　Interested friends can also look at a video I once posted - how to make a cabinet light that can be switched on and off automatically. After reading it, it should be clear how to use the micro switch to automatically control the wardrobe light.

　　2. Passive infrared sensor

　　This method uses the infrared light emitted by the human body to be different from the surrounding environment, and controls the light on and off by sensing the changes in the infrared light.

　　Objects around us emit infrared rays. Why do you say that? Scientific research shows that as long as the temperature of an object is higher than absolute zero ( -273 ℃), it will continuously emit infrared radiation. The higher the temperature, the greater the infrared radiation energy emitted. Under normal circumstances, the temperature of the human body is higher than the temperature of the surrounding environment, the emitted infrared radiation is larger, and the infrared spectrum is different from the surrounding environment, so you will see that some thermal imaging instruments generally show that the human body is relatively "red" , Using this difference in infrared light can judge the arrival and departure of people, and the current infrared sensor switches are also based on this principle.

　　The induction lamp in this way usually has a white hemispherical object. This is a Fresnel lens, which is the main component of infrared sensing. The function of the Fresnel lens is to enhance the focused infrared, which makes the infrared sensor more sensitive. .

　　Infrared induction is now a more widely used solution. For example, in some public areas, corridors, corridors, etc., infrared induction switches can be installed to control electrical appliances to achieve energy-saving effects. If you use this scheme at home, you don't have to " touch the dark " to find a switch when you get up and move around at night .

　　3. Active sensing

　　The infrared sensor mentioned above is a passive sensor. It is not a source of emission, but a source of reception. Another way is proactive. The sensor switch itself is both a transmitting source and a receiving source. Its principle is this: if the sound, light and other signals emitted by oneself can be reflected back, it proves that there is an obstruction in front; if the reflection does not come back, it proves that there is no object in front. The more commonly used is also the infrared transmitter and receiver module, which generally has two diodes, one for transmitting and one for receiving. This kind of module generally only receives the infrared frequency band emitted by itself, not the infrared emitted by other objects (in special cases, it will be interfered by other light sources).

　　The transmitting and receiving ends of this active induction switch are aligned with the cabinet door from the inside. Normally, when the cabinet door is closed, the emitted sound and light can be reflected back, but not when it is opened. In this way, it is possible to control the off and on of the light by judging whether the receiving end has received a signal.

　　The above are several ways to realize automatic control of wardrobe lights that I have summarized .