Reference
The article explains how motion sensors detect IR radiation emitted by human bodies using a built-in IR probe and Fresnel lens, breaking down its impact on pyroelectric elements and detailing relevant communication protocols and API descriptions.
Principle
Generally, human beings maintain a constant temperature of 37℃ so they emit infrared rays of specified 10UM wavelength. The built-in IR probe of the motion sensor is able to detect the IR radiation emitted by the human body. The IR radiation will be focused on the pyroelectric part after being collected by a Fresnel lens. Next, the charge balance of the pyroelectric element will be broke when it feels the change of the temperature of the infrared radiation, and then it will release charge to produce electrical signal.
Other Supplementary Information
When people enter the detecting zone of the motion sensor, it outputs a switch signal (High Level). The motion sensor can sense the moving objects within 7m in 100° sensing angle. Please kindly note that there would be 2.3 to 3s delay.
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