Infrared light is invisible and imperceptible to the human eye. The appearance of the common infrared LED lamp beads is similar to that of ordinary LED lamp beads. Reducing the pulse duty cycle can also greatly increase the emission distance of low-power IR LEDs. The power of the common infrared light-emitting diode is divided into three categories: low power (1mW~10mW), medium power (20mW~50mW) and high power (50mW~100mW or more). When applying infrared light-emitting diodes of different powers, they should be equipped with drive tubes of corresponding powers. To make the infrared light-emitting diode form a modulated light, only a certain frequency of impulse voltage is added to the drive tube.
When the infrared light-emitting diode emits infrared rays to control the controlled device, there are corresponding infrared photoelectric conversion elements in the controlled device, such as infrared receiving diode, phototransistor, etc.
There are two methods of infrared emission and reception, one is direct and the other is reflective. Direct beam means that the light-emitting tube and the receiving tube are placed opposite each other at both ends of the emitting and controlled objects, with a certain distance between them; Reflective means that the light-emitting tube and the receiving tube are juxtaposed together, and the receiving tube is always without light, and only when the infrared light emitted by the light-emitting tube encounters the reflector, the receiving tube receives the reflected infrared rays before working.