If you have a burglar alarm with motion sensors, you may have noticed that the motion sensors cannot "see" you when you are outside looking through a window. That is because glass is not very transparent to infrared energy. This, by the way, is the basis of a greenhouse. Light passes through the glass into the greenhouse and heats things up inside the greenhouse. The glass is then opaque to the infrared energy. these heated things are emitting, so the heat is trapped inside the greenhouse. It makes sense that a motion detector sensitive to infrared energy cannot see through glass windows. The PIR motion sensor module senses occupants in any given room and sends a signal to the modular room control system. The system consists of a contact door device and a room controller to determine if there are occupants in the room. This capability can provide enhanced security and energy conservation, aiding in the overall business or household operation.
PIR (Passive Infrared Radiation) sensors perceive motion by detecting the heat generated by a moving human body. Passive means the device simply responds to the radiation received rather than actively sending a signal or scanning an area. Through refinement of the incoming heat signal, PIR motion sensor module is a very sophisticated device with many uses.
A Fresnel lens, which consists of a series of concentric grooves on a transparent surface, enables a wider field of detection and breaks the incoming radiation into zones. By activating more area of the pyroelectric material, the Fresnel lens increases the sensitivity of PIR sensors. The detection of heat change from one zone to the next ensures that the source of the heat is moving. The signal generated from the PIR sensors is sent to a comparator that checks for established patterns that are to be ignored.
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