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Application of infrared body sensing sensor in smart lighting

With the upgrading and iteration of artificial intelligence, 5G, Internet of Things and other technologies, intelligence has become the general trend of the lighting industry. In the future, the function of intelligent lighting products is not only "lighting", but will become an important role for people to create a quality of life.

Intelligent lighting can be easily associated with various types of sensors, so as to realize a variety of automatic control functions such as light control and infrared control. For example, the automatic switch of LED street lights can be easily realized with a photosensitive sensor; Community night walkways and courtyard lighting, infrared pyroelectric body sensor can be used to collect human activity information, automatically open and close lighting fixtures.

Infrared pyroelectric body sensing sensors work by detecting infrared rays emitted by the human body. The main principle is: the infrared rays emitted by the human body about 10 μm are enhanced by Fresnel lenses and concentrated on the pyroelectric element PIR (passive infrared) detector, when the person is active, the emission position of infrared radiation will change, the element will lose the charge balance, pyroelectric effect occurs to release charge outward, infrared sensor will pass through the Fresnel lens infrared radiation energy change into electrical signals, that is, thermoelectric conversion.

When the human body enters the detection area, through the Fresnel lens, the pyroelectric infrared sensor senses the difference between the human body temperature and the background temperature, and the signal is collected and compared with the existing detection data in the system to determine whether someone and other infrared sources enter the detection area.

Passive infrared sensors have a key element - Fresnel lenses. Fresnel lenses have two functions: one is focusing, that is, pyroluminous infrared signals are refracted on POR; The second is to divide the detection area into several bright and dark areas, so that moving objects/people entering the detection area can produce a changing pyroelectric infrared signal on the PIR in the form of temperature changes.

It is also generally matched to a low-noise amplifier, which compensates for the gain and increases its sensitivity when the ambient temperature on the detector rises, especially close to the normal body temperature (37°C). The output signal can be used to drive electronic switches to enable switching control of LED lighting circuits.