Brief Introduction of Safety Products (3)

(2) Security line-controlled intrusion detectors — use intrusion detectors to arm and form an invisible security line, and an alarm can occur when someone passes through. Common ones are: active infrared, passive infrared, laser, microwave, and induction.

Active infrared intrusion detector

It is composed of active infrared light transmitter and receiver. Infrared light is in the invisible spectrum range of human eyes. After the light beam is focused, an infrared light beam is formed between the transceivers. Someone passes this invisible blockade line, and it will inevitably block the infrared light beam in whole or in part. The receiving end will automatically recognize whether an alarm occurs due to changes in the infrared beam. If small animals, leaves, dust, rain, snow, fog are blocked, the alarm should not be given. If people or objects of considerable volume are blocked, an alarm will occur. It is used to block doors and windows in factory warehouses, block passages in shopping malls, block exits in parking lots, and block balconies at home. Due to the narrow beam, the installation of the transceiver should be firm and reliable, and should not be affected by ground vibration, and the displacement will cause false alarms. The optical system should be kept clean and pay attention to maintenance.

Laser Intrusion Detector

The structure is the same as active infrared, the main difference is the light source. The infrared laser beam is narrow and difficult to diverge, and can form a blockade of thousands of kilometers. When using the appropriate reflector in the exhibition hall, a set of devices can be used to form a four-wall circuit blockade, which makes the prevention more stringent. Although there are many advantages, due to the thin beam, the most feared displacement of the mirror is, so it must be adjusted frequently during use to ensure the actual effect. Because it is too professional, it is not suitable for home application.

Reflective passive infrared intrusion detector

Install the pyroelectric device in the middle of the front of a cylinder, and install the reflector at the bottom of the cylinder. Passive infrared radiates anything at room temperature. The higher the temperature, the stronger the infrared radiation. Humans are constant temperature animals, and infrared radiation is also the most stable. The reason we are called passive infrared is that the detector itself does not emit any energy but only passively receives infrared rays from the environment. The detector has been adapted to the environment within a few seconds after installation. Once infrared radiation from the human body comes in, it is focused by the optical system to cause heat The discharge device generates a sudden electrical signal, and an alarm is issued. The warning line formed by passive infrared intrusion detectors can generally reach tens of meters. It is easier to install than active infrared, but do not face heat and strong light sources, especially air conditioning and heating. Otherwise, the constantly changing hot air flow will cause false alarms.

Transceiver split microwave (microwave wall) intrusion detector

Microwaves are electromagnetic waves that are invisible to the human eye. Separate the two ends of the transceiver on the ground where the cordon is needed, and an invisible wall is formed in the middle. The wall can be up to one meter thick and two meters high. People walking through it will absorb or reflect microwaves, causing a huge change in the received microwave energy at the receiving end and causing an alarm. It is used to block passages, counters and shelves in shopping malls and weapon and ammunition depots. It is very effective to block the gate and the crossing rivers and lakes in the villa area, and block the balcony and external windows in the residence. But in outdoor applications, we must pay attention to the dog or animals larger than the dog crossing the blockade to avoid false alarms.

Inductive intrusion detector

Inductive intrusion detectors are used to block fish ponds and warehouses, and can form loop warning lines, which are very effective and convenient to use.