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Infrared emitter receiver tube is a semiconductor device that converts infrared light signals into electrical signals. Its core component is a PN junction made of a special material. Compared with ordinary diodes, it has undergone significant structural changes. In order to receive more and larger areas of incident light, the PN junction area of the infrared emitter receiver tube is made as large as possible, and the electrode area is minimized as much as possible. Moreover, the junction depth of the PN junction is very shallow, generally less than 1 micron. Infrared emission and reception tubes operate under the action of reverse voltage. When there is no light, the reverse current is very small (usually less than 0.1 microamperes), which is called dark current. When exposed to infrared light, infrared photons carrying energy enter the PN junction and transfer the energy to the bound electrons on the covalent bond, causing some electrons to break free from the covalent bond and generate electron hole pairs (referred to as photo generated carriers). They participate in drift motion under the action of reverse voltage, causing a significant increase in reverse current. The greater the intensity of light, the greater the reverse current. This characteristic is called "photoconductivity". The current generated by an infrared emitter receiver tube under normal illumination is called photocurrent. If a load is connected to the external circuit, an electrical signal is obtained on the load, and this electrical signal changes accordingly with the variation of light.

Classification: There are two types of infrared emitting and receiving tubes, one is a photodiode, and the other is a phototransistor. Photodiodes convert light signals into electrical signals, while phototransistors amplify current while converting light signals into electrical signals. Therefore, phototransistors are also divided into two types, namely NPN type and PNP type.

Function: The infrared emitter receiver tube is used for photoelectric conversion and has a wide range of applications in light control, infrared remote control, light detection, fiber optic communication, photoelectric coupling, and other fields. How to choose an infrared receiver: The most important parameter of infrared is the amplification factor of the photoelectric signal, generally ranging from 1000-1300, 1300-1800, 1800-2500, which determines the sensitivity.

Infrared tube is a general term for the combination of infrared emitting tube and photosensitive receiving tube, or infrared receiving tube, or infrared receiving head when used together. The wavelength range of infrared in the spectrum from 0.76 to 400 microns is called infrared, which is invisible light. All substances above absolute zero (-273.15 ℃) can produce infrared radiation. Modern physics refers to it as thermal radiation. Medical infrared can be divided into two categories: near-infrared and far-infrared.

There are three commonly used bands for infrared emission and reception tubes in the LED packaging industry, as follows: 850NM, 875NM, and 940NM. There are also significant differences in the products used based on the characteristics of wavelength. The 850NM wavelength is mainly used for infrared monitoring equipment, the 875NM wavelength is mainly used for medical equipment, and the 940NM wavelength is mainly used for infrared control equipment. EG: Infrared remote control, photoelectric switch, photoelectric counting device, etc. The polarity of the tube cannot be mistaken, usually the longer pin is the positive pole and the other pin is the negative pole. If it cannot be identified from the length of the pin (such as a pin that has been shortened), it can be determined by measuring its forward and reverse resistance. When the forward resistance is measured to be low, the pin connected to the black probe is the positive terminal. By measuring the forward and reverse resistance of infrared light-emitting diodes, one can largely infer their performance. Taking the R × 1k range of a 500 type multimeter as an example, if the measured forward resistance value is greater than 20k Ω, there is suspicion of aging; If it is close to zero, it should be scrapped. If the reverse resistance is only a few thousand ohms, or even close to zero, the tube will undoubtedly break; The larger its reverse resistance, the smaller its leakage current and the better its quality.

It is a PN junction with photosensitive characteristics, belonging to a phototransistor, with unidirectional conductivity, so a reverse voltage needs to be applied during operation. When there is no light, there is a small saturation reverse leakage current (dark current). At this time, the photosensitive tube is not conducting. When illuminated, the saturated reverse leakage current immediately increases, forming a photocurrent that increases within a certain range with changes in incident light intensity. The function is similar to that of a photosensitive receiver tube, but it is not affected by visible light interference and belongs to a photodiode that only responds to infrared radiation. It is the function of amplifying signals based on infrared receivers, similar to the amplification effect of transistors.