Introduction
is an active infrared detector infrared beam blocked type of alarm, an infrared light emitting diode in the transmitter power of the excitation, emits a modulated infrared beam (the wavelength of this beam is between about 0.8 to 0.95 microns), through the action of the optical system into a parallel light emitting go out. This beam is received by the receiver, the receiver converts the infrared photosensor signal into an optical signal, after the alarm control circuit for processing. Infrared rays emitted by the transmitter reach the receiver through prevention region, constitute a warning line. Under normal circumstances, the receiver the received optical signal is a stable, when the invasion was the cordon, the infrared beam is blocked, the infrared signal received by the receiver changes, this change extraction, suitably amplified and processed, the controller of the alarm signal is issued. Currently there are two such probe beam, three-beam as well as multi-beam infrared fences. General application to the perimeter against the majority, the biggest advantage is to prevent range, can reach more than ten times the passive infrared detection range.
active infrared detector: using active IR mode, the detector in order to achieve the security alarm function. Active infrared detector consists of an infrared transmitter, an infrared receiver and the alarm controller. They were placed received, the originator of the optical system is generally used in an optical lens, serves to focus the beam into an infrared beam parallel finer effect, so that the energy can be focused infrared light transmission. Infrared light is invisible to the human eye spectral range, it was through this invisible blockade, must wholly or partly block the infrared beam. End of the output intensity of the received electrical signal will thus produce a change, alarm controller to initiate an alarm signal.
device selection principles
to select points probably including the following:
1) number of beams;
2) Detection method; < / p>
3) the operating voltage;
4) detection range;
5) the reaction rate;
1. According to the site to prevent the minimum and maximum temperature and duration, select the appropriate operating temperature with active infrared intrusion detectors; in order to ensure the normal operation of the detector if the ambient temperature is too low can use special heaters.
2. Active infrared intrusion detectors fog seriously affected, with automatic gain selection device shall function when used outdoors (such as the device automatically adjusts the sensitivity of climate changes); In addition, the actual alert distance detection range of the selected device 20 leave % or more margin to reduce false alarms caused by climate change system.
3. Be sure to use a dual beam or 3-beam active infrared intrusion detectors in outdoor use, in order to reduce the birds, leaves and other false alarms caused by the system.
4. Active infrared intrusion detectors in the near infrared light emitting diode at wavelengths 0.85μm and 0.95μm, respectively. The former red exposure phenomenon, its good concealment than the latter.
5. Foggy area, a large outdoor environment dirty sand area should not use active infrared intrusion detector.
6. Or in the open area in the wall, using active infrared intrusion detectors on the roof, choose devices with lightning protection function.
7. In case of off the wall, and the distance and near, the choice of the reflection device, in order to reduce the number of probes used.
8. Outdoor active infrared intrusion detectors use the maximum beam distance should be more than six times the detection range specified by the manufacturer.
Construction installation points
mounted1 active infrared detectors should meet GB 10408.4-2000 intrusion detector Part 4 : active infrared detectors required standards and product specification.
2 active infrared detectors should be installed in the standard reference map "smart home control system design and construction Atlas" 03X602 content.
Application
1, a small supermarket, convenience store guests and export
on the inside and out of doorways indoor short-range one pair (≤10 m) Active Infrared intrusion detectors, when the guests in and out of active infrared detectors will issue a "warning" signal, the "alarm" signal linkage ding-dong doorbell, so small supermarket, convenience store salesperson is a hint, but also reflects the shuttle for guests the ceremony, enlivened the atmosphere of a small supermarket, convenience store.
2, the inlet windows prevent
is mounted on the outside of the window outdoor double-beam active infrared intrusion detectors, typically mounted on the exterior wall window, along the window near, more suitable for such installation on the second floor above the windows to protect against intruders to climb, but it does not affect the window installation requirements (refer to the external window, and the window for translation within the window does not affect).
inside the installation chamber double-beam active infrared intrusion detectors. Installed in the interior side of the window wall, along the top of the window frame, the sash from 80 to 100 mm along the better. But do not have an impact (refer to internal windows, windows and exterior window of the translation does not affect) on the window. After
3, with active instead of passive infrared intrusion detectors infrared intrusion detectors
is installed in a computer room passive infrared intrusion detectors, since the air conditioner starts spaced frequent false alarms, change with active infrared intrusion detectors after eliminating the phenomenon of false alarms.
closed doors: Active dual beam infrared detector two pairs, a pair of 150 mm from the ground, the other pair of ground 700 to 800 mm. Sealed windows: two for the two-beam active infrared detector, a pair of 100 mm from the lower window edge and the other of 600 mm from the lower window edge.
4, residential quarters and border guard units
Because active infrared intrusion detector with good performance, easy installation, low cost, etc., so in recent years has been widely installed in selected organs , fence factories, residential quarters, etc., and the fence to be on the perimeter intrusion prevention. Detector selection principle is based on the wall, the straight length between two inflection fence select effective detection distance of the active infrared detectors, the detector is mounted on the wall, the upper or outer side fences, and to make the perimeter to be protected is not blind spot detection. However, due to active infrared detectors susceptible to environmental factors, such as climate, so some very important occasions, such as troops, military warehouses, airports, prisons, homes, etc. important not to choose to install active infrared detectors, and use other detection techniques , or multiple detection techniques, and even the installation of fences.