The working principle and characteristics of infrared detectors!
2023-11-05 01:09:19
The human body has a constant body temperature, generally around 37 degrees, and emits infrared light with a specific wavelength of about 10 μm. A passive infrared detector works by detecting infrared radiation emitted by a human body at about 10 μm. The 10 μm or so infrared emitted by the human body is enhanced by the Fresnel filter and collected on the infrared sensor. Infrared sensors usually use pyroelectric elements, which lose their charge balance when they receive a change in human infrared radiation temperature, and release charge outward. The subsequent circuit can generate an alarm signal after detection and processing.
1. Passive infrared detectors are aimed at detecting human radiation, so pyroelectric elements must be very sensitive to infrared radiation having a wavelength of about 10 μm. ,
2. In order to be sensitive only to the infrared radiation of the human body, a special Fresnel filter is usually covered on its radiation surface, so that the interference of the environment is obviously controlled.
3. Its sensor contains two pyroelectric elements connected in series or in parallel with each other. In addition, the two polarization directions produced are exactly the opposite. The ambient background radiation has almost the same effect on the two pyroelectric elements, causing them to cancel each other's charge generation effect. Thus, the detector has no signal output.
4. Once the person invades the detection area, the infrared radiation of the human body is partially focused by the mirror, and is received by the pyroelectric element. However, the heat received by the two pyroelectric elements is different, and the pyroelectricity can not be cancelled by the signal processing.
Passive infrared depth detector advantages and disadvantages
Advantages: Does not emit any type of radiation itself, the device power consumption is very small, better concealment, and low prices.
Disadvantages: easy to be interfered by various heat sources and sunlight sources; passive infrared penetrating power is poor, human body's infrared radiation is easily shielded, is not easily received by the detector, is susceptible to interference by radio frequency radiation, and when the ambient temperature and human body temperature are close, the detection and The sensitivity has decreased significantly, sometimes causing short-term failure.
1. Passive infrared detectors are aimed at detecting human radiation, so pyroelectric elements must be very sensitive to infrared radiation having a wavelength of about 10 μm. ,
2. In order to be sensitive only to the infrared radiation of the human body, a special Fresnel filter is usually covered on its radiation surface, so that the interference of the environment is obviously controlled.
3. Its sensor contains two pyroelectric elements connected in series or in parallel with each other. In addition, the two polarization directions produced are exactly the opposite. The ambient background radiation has almost the same effect on the two pyroelectric elements, causing them to cancel each other's charge generation effect. Thus, the detector has no signal output.
4. Once the person invades the detection area, the infrared radiation of the human body is partially focused by the mirror, and is received by the pyroelectric element. However, the heat received by the two pyroelectric elements is different, and the pyroelectricity can not be cancelled by the signal processing.
Passive infrared depth detector advantages and disadvantages
Advantages: Does not emit any type of radiation itself, the device power consumption is very small, better concealment, and low prices.
Disadvantages: easy to be interfered by various heat sources and sunlight sources; passive infrared penetrating power is poor, human body's infrared radiation is easily shielded, is not easily received by the detector, is susceptible to interference by radio frequency radiation, and when the ambient temperature and human body temperature are close, the detection and The sensitivity has decreased significantly, sometimes causing short-term failure.
Optical Filter,Color Glass Filter,Colored Glass Bandpass Filter,Infrared Glass Filter
China Star Optics Technology Co.,Ltd. , https://www.opticsrealpoo.com