Recife Distance Hold
Recife Distance Hold Concept understanding The active infrared radiation intrusion detector consists of an active infrared transmitter and an active infrared receiver. When the infrared beam between the transmitter and the receiver is completely blocked or blocked by a given percentage, the...
Recife Distance Hold
The active infrared radiation intrusion detector consists of an active infrared transmitter and an active infrared receiver. When the infrared beam between the transmitter and the receiver is completely blocked or blocked by a given percentage, the device can generate an alarm state, which is called active infrared. Intrusion detector.
Photoelectric sensors in active infrared receivers usually use photodiodes, phototransistors, silicon photocells, silicon avalanche diodes, etc. According to GBl0408.4-2000 "Intrusion Detectors Part 4: Active Infrared Detectors", "Probe When the detector is operated at the detection distance specified by the manufacturer, the detector should generate an alarm condition when the radiation signal is completely or shaded by a given percentage for more than 40 ms. Why does a range have to be given? The reason is that different locations are used. Different minimum blackout times can be set (adjusted), which is beneficial for reducing false alarms in the system.
The infrared beam emitted by the active infrared transmitter is divergence angle. It is specified in the GBl0408.4-2000 standard: “In indoor use, the transmitter and receiver are correctly installed and aligned, and work at the detection distance specified by the manufacturer. Radiation energy is 75%. The receiver should not generate an alarm condition when it is permanently obstructed." For outdoor use, the sensitivity of the infrared beam is reduced due to the effects of temperature and sunlight. In order to reduce the false alarm caused by this, the axis of the transmitter and the receiver should be coincident during installation and use.
Active infrared transmitters usually use infrared light emitting diodes as the light source. Its main advantages are small size, light weight, long life, AC and DC can be used, and can be directly driven by transistors and integrated circuits. Most active infrared intrusion detectors use complementary self-excited multivibrator circuits as the driving power source, and they are directly added to the ends of the infrared light emitting diodes so that they emit pulsed light beams with high duty ratios. The power consumption of the power supply is reduced, and the anti-interference ability of the active infrared intrusion detector is enhanced.