What's difference between wide angle PIR and curtain PIR ?
PIR-based motion detectors are widely used in burglar alarm system. PIR based motion detectors include wide-angle PIR-based motion detector, curtain PIR based motion detector, Direction Recognition Curtain PIR-based Motion Detector, etc. what’s difference between them ?
Firstly, all above motion detectors are PIR based, all of them with the same function of detection of temperature changes.
The working theory: In nature, any objects that with the above absolute degree temperature (-273 degree) are emitting infrared wave, different temperature objects, emitting infrared wave length are different, so infrared length is related to the temperature.
There are two important components for PIR-based motion detectors, one is PIR element sensor, it can convert 9-12um infrared wave to electronic signal, it's anti-white light interference of nature, so when without human movement, PIR only detects the background temperature. When human enter into detection space, through fresnel lens, PIR can detect the difference of human temperature and background temperature.
The other component is fresnel lens, there are two kinds of fresnel lens; refractive type and reflective types. The function for fresnel lens are focusing the infrared ware and reflect the infrared wave to PIR element sensor, the second function is can distribute detection area to dark district and white district, when moving object enter into the detection area, PIR sensor can discriminate the temperature changes easily.
The major difference between wide angel PIR based motion detector and curtain PIR based motion detector is the detection angle and width.
Wide-angle PIR-based Motion detector with wide angle of 100-120 degree, vertical 60 degree, 8-12s meter conical detection space (area). It’s used in interior movement detection.
Curtain PIR-based motion detector using special fresnel lens to create a very slim detection space (like 15 degree). Curtain PIR-based motion detectors are installed in front of window, only protection of window, people still can move inside of house and will not cause the alarm.
Direction recognition curtain PIR is a curtain PIR-based motion detector add direction recognition. When people directly walk forward to one of direction, the Direction Recognition Curtain PIR will not be triggered. it will be triggered only when movement is detected in contrary direction.
The advantage of this is when you installed direction recognition curtain PIR on the door of balcony, when house owner go to balcony, if it’s within preset time (this time can be set on detector), then back to house from that door, the detector will not be triggered. If people want to get into the balcony from outside, then alarm will be triggered.
Ceiling PIR Motion detectors mount on the ceiling of floor with the 360 degree detection angle.
Tags: PIR motion sensor