Analysis of LED lighting fixtures and sensor technology 3

Combination of infrared sensor and LED lighting fixtures

Infrared sensors work by detecting the infrared radiation emitted by the human body. The main principle is that the infrared radiation emitted by the human body at around 10um is enhanced by a Fresnel filter lens and then directed to the pyroelectric element PIR. When a person is active, the emission position of the infrared radiation will change, causing the element to lose charge balance and release electricity outward through the pyroelectric effect. The infrared sensor (PIR) converts the change in infrared radiation energy transmitted through the Fresnel filter lens into an electrical signal, known as thermoelectric conversion. When there is no human movement in the detection area of the passive infrared detector,diode  the infrared sensor only senses the background temperature. When a human enters the detection area, the difference between the human body temperature and the background temperature is sensed by the pyroelectric infrared sensor through a Fresnel lens. After the signal is collected, it is compared with the existing detection data in the system to determine whether there is really a human or other infrared source entering the detection area.diode

Passive infrared sensors have three key components: Fresnel filter lens, pyroelectric infrared sensor (PIR), and matching low-noise amplifier. The Fresnel lens has two functions: one is the focusing effect, which refracts the pyroelectric infrared signal onto the PIR; the other is to divide the detection area into several bright and dark areas, diode so that moving objects (people) entering the detection area can generate a changing pyroelectric infrared signal on the PIR in the form of temperature changes. Generally, a low-noise amplifier is also matched. When the ambient temperature on the detector rises, especially when it approaches normal human body temperature (37 ℃), the sensitivity of the sensor decreases. It compensates for the gain and increases its sensitivity.diode