Infrared sensor detection wavelength range is 8 ~ 14μm, the human body's infrared peak wavelength of about 10μm, just within the range. Intelligent IR Illuminator The sensor contains two thermocouples in series or in parallel. And the two polarizations are exactly the opposite direction, Intelligent IR Illuminator the ambient background radiation has almost the same effect on the two pyroelectrics, so that the discharge effect is canceled each other, so the detector no signal output, once the human body into the detection area, Human body infrared radiation through the part of the mirror and focus, so the pyroelectric element to receive, but the two pyroelectrics received different heat, pyroelectric is also different, can not offset, the signal processing and alarm.
1. Intelligent infrared light control switch structure and working principle
The main components of the intelligent infrared light control switch device are passive infrared detection device and switch delay circuit. Among them, Intelligent IR Illuminator the passive infrared detection device's main role is to detect the existence of the human body, which issued a control pulse current to control the working state of the switch circuit; switch circuit is the main role of control lamp switch, open the length of time by the adjustable delay circuit The
Passive infrared detection circuit: sensor BH detection of human hair issued by the trace of infrared, sensor BH internal pyroelectric induction to the temperature changes, as a strong dielectric pyrolysis element spontaneous polarization, and the release of charge, in parallel components (resistance) There is an electrical signal change. BH internal set by the field effect transistor amplification, can output a certain amplitude of the electrical pulse, the pulse frequency is generally between 0.5-1HZ (which is the most sensitive BH frequency range).
The signal processing circuit is composed of resistors R1, R2, R3, R4, R5, R6, R7, RP1, capacitors C1, C2, C4, C5, transistors Q1, Q2, manifold IC1, IC2. Point pulse through the C1 coupling into the preamplifier tube Q1 pre-placed, pre-placed signal from the Q1 collector, straight
High stability amplification, and then coupled to the op amp IC1 ③ feet, two low noise,
Output voltage from pin 1 of IC1. Intelligent IR Illuminator IC2 shifter constitutes a voltage comparator, RP is the reference voltage divider. When the IC1 ⑥ pin output voltage is higher than the IC3 reference voltage, IC2 also output amplified high pulse, the R6 current limit after the transistor Q2 conduction. Capacitors C2 and C5 form a low-pass filter to eliminate the interference pulse. PTC is a thermistor with a positive temperature coefficient. Since the sensor BH is only sensitive to relative heat, the difference between the heat (constant) and the temperature (variable) is significantly reduced in the summer due to the high temperature. Intelligent IR Illuminator The sensitivity of the relative decline, while the PTC resistance characteristics is increased with the temperature of its resistance becomes larger, resulting in reduced feedback, relatively improve the gain of the op amp circuit, thus compensating the BH on the temperature rise and the sensitivity of the defect The
(2) the working principle of passive infrared detection device Any temperature exceeds the absolute 0 ℃ objects can produce heat radiation, and the temperature below 1725 ℃ objects generated by the thermal radiation spectrum concentrated in the infrared light area, so all the natural objects can Radiant infrared heat. And any object due to their physical and chemical properties of different, Intelligent IR Illuminator different temperature generated by the infrared radiation wavelength and distance are not the same, people are warm animals, infrared radiation is also the most stable, the infrared light wavelength of radiation 3 ~ 50μm, Of which 8 ~ 14μm accounted for 46%, the peak wavelength in the
We are called passive infrared, that is, the detector itself does not emit any energy and only 9.5μm.