In the range of alert, why is the passive infrared detector in the mobile when the alarm signal can occur?
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Author:cj36
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Published time: 2017-05-13
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In nature, any object above the absolute temperature (-273 degrees) will produce infrared spectra, different temperature objects, the release of infrared energy wavelength is not the same, so the infrared wavelength and temperature are related.
There are two key originals in the passive infrared detector, one is the pyroelectric infrared sensor (PIR), which converts the infrared signal between wavelengths from 8 to 12um into electrical signals and can convert the natural white light The signal has a suppression effect, so in the passive infrared detector warning area, when no human body movement, the pyroelectric infrared sensor sensor is only the background temperature, when the human body into the warning area through the Fresnel lens, pyroelectric infrared Sensor sensor is the difference between the temperature of the human body and the background temperature of the signal, so the infrared detector infrared detection of the basic concept is to move the object and the background object temperature difference. Another device is the Fresnel lens, Fresnel lens in two forms, namely, refraction and reflection. Fresnel lens has two roles: one is the focus of the effect, that is, the thermal release of the infrared signal refraction (reflection) on the PIR, the second role is to guard the area of a number of clear areas and dark areas, so that into the alert The moving object in the zone can change the pyroelectric infrared signal on the PIR in the form of temperature changes so that the PIR can produce a changed electrical signal.
In nature, any object above the absolute temperature (-273 degrees) will produce infrared spectra, different temperature objects, the release of infrared energy wavelength is not the same, so the infrared wavelength and temperature are related.
There are two key originals in the passive infrared detector, one is the pyroelectric infrared sensor (PIR), which converts the infrared signal between wavelengths from 8 to 12um into electrical signals and can convert the natural white light The signal has a suppression effect, so in the passive infrared detector warning area, when no human body movement, the pyroelectric infrared sensor sensor is only the background temperature, when the human body into the warning area through the Fresnel lens, pyroelectric infrared Sensor sensor is the difference between the temperature of the human body and the background temperature of the signal, so the infrared detector infrared detection of the basic concept is to move the object and the background object temperature difference. Another device is the Fresnel lens, Fresnel lens in two forms, namely, refraction and reflection. Fresnel lens has two roles: one is the focus of the effect, that is, the thermal release of the infrared signal refraction (reflection) on the PIR, the second role is to guard the area of a number of clear areas and dark areas, so that into the alert The moving object in the zone can change the pyroelectric infrared signal on the PIR in the form of temperature changes so that the PIR can produce a changed electrical signal.