Nowadays, there are many products involving infrared rays, and infrared receiver tubes are basically used. Infrared rays are invisible and intangible light with the naked eye. The wavelength is between microwave and visible light. Many people are very curious about it. It is magical to people. My life has brought many surprises. The copier makes work more convenient, the car wiper makes the field of vision clearer and so on.

　　 1. The structure of the infrared receiving tube

The structure of the infrared receiver tube is actually very simple. It mainly includes two parts. First, high-speed and high-sensitivity light-emitting point diodes; second, standard plastic tubes; the former is directly placed in the latter for good protection effect.

　　 2. Types of infrared receiver tubes

　　 There are two types of infrared receivers, one is a photodiode and the other is a phototransistor. Among them, the phototransistor is divided into two types, namely NPN type and PNP type.

　　 3. The working principle of infrared receiver tube

In order for the infrared receiving tube to receive incident light in a larger area, the PN junction area of the die is relatively large, and the electrode area is relatively small. When there is infrared light, the infrared photons carrying energy will enter the PN junction. Then, the energy is transferred to the bound electrons on the covalent bond, so that part of the electrons break free from the covalent bond, thereby generating electron-hole pairs.

　　 If it is a reverse voltage effect, the electron-hole pair will drift and move, which will increase the reverse current significantly. The greater the intensity of light, the greater the reverse current. If a load is connected to the external circuit, the load can obtain a signal, and the signal will change with the change of light.