Why Passive Infrared Detector Stands Out in the Security Industry？

I wonder if you have ever encountered such a situation in your daily life. When you walk into some dark corridors at night, sometimes the lights will light up automatically, and sometimes you need to cough heavily or stamp your feet before the lights will light up. This situation is determined by the different sensor selections of corridor lights, but in general, the voice-activated sensors triggered by sound are slightly inferior to the automatic sensing infrared sensors.

From the application perspective, voice-activated sensors need to make certain noises, which may affect the rest of residents, and are easily disturbed by external sounds, often misoperate, have a short lifespan, and have limited load products. In order to cope with this dilemma, passive infrared motion detector technology has been adopted in most corridors. What is passive infrared motion detector technology? If we only talk about passive infrared motion detector itself, in the field of chemistry, it refers to Polyisocyanurate Foam; in the field of biology, it is a database that integrates public resources on protein function prediction data, with the purpose of supporting genome/proteome research; and in the security industry, it is the abbreviation of Passive Infrared, that is, passive infrared technology.
The full name of PIR is Passive Infrared Detector, which is a passive infrared detector or body sensor. Sometimes it is called passive infrared motion detector. In the security industry, detectors are mostly called Detectors. As we all know, at room temperature, any object has radiation. As a warm-blooded animal, human infrared radiation is also the most stable. The reason why we call infrared motion sensors is that the detectors themselves do not emit any energy but only passively receive and detect infrared radiation from the environment. After the detector is installed, it will adapt to the environment for a few seconds. When no one or animals enter the detection area, the infrared radiation on the scene is stable. Once human infrared radiation comes in, the pyroelectric device will generate a sudden electrical signal after being focused by the optical system, and then the subsequent linkage will be carried out.

What should be paid attention to when applying passive infrared motion detector technology?

The first thing to note is that infrared light has poor penetration. There should be no tall objects in the prevention area, otherwise the alarm will not be triggered if someone walks in the shadow part. Do not face heat sources and strong light sources, especially air conditioners and heaters, otherwise the constantly changing hot air flow will cause false alarms. Secondly, since the passive infrared detector is a weak signal detection device, some details must be paid attention to during installation, such as height, sensitivity, etc.
At the same time, it should be noted that it should not face glass doors and windows. There will be two problems when the passive infrared detector faces glass doors and windows. One is white light interference. Although infrared motion sensor has a strong suppression function for white light, it is not 100% suppression after all. Therefore, it is necessary to avoid facing glass doors and windows to avoid interference from strong light. The second is to avoid complex environmental interference outside the doors and windows, such as crowd flow, vehicles, etc. Finally, it is also necessary to pay attention to not facing hot and cold vents or hot and cold sources. The sensing effect of passive infrared detectors is closely related to temperature changes. Hot and cold vents and hot and cold sources may cause false alarms of detectors. For some low-performance detectors, air convection through doors and windows may sometimes cause false alarms.

What applications of passive infrared motion detector technology have been implemented?

At present, in addition to the induction lights commonly seen in corridors, passive infrared motion detector human infrared sensing is mostly used for perimeter alarms. Since passive infrared detectors (passive infrared motion detector) vary in structure, warning range and detection distance, they can be roughly divided into single-beam and multi-beam types. Single-beam passive infrared motion detector uses a reflective focusing optical system, which uses a curved reflector to focus the infrared radiation from the target on the infrared sensor. The field of view of this type of detector is narrow, generally below 5°, but the effective distance is far, up to 100 meters. Therefore, it is also called a linear long-distance control type passive infrared detector, which is suitable for protecting narrow corridors, passages, and blocking doors, windows and walls.

The multi-beam type uses a lens focusing optical system, most of which use infrared plastic lenses - Fresnel lenses with multi-layer beam structures. This lens is made of polyolefin plastic in one molding, and several small lenses are arranged on an arc surface. The warning range is in multiple single beam states in different directions, forming a three-dimensional fan-shaped heat-sensitive area, which can constitute a three-dimensional warning. At the same time, because the warning field of view of the multi-beam passive infrared motion detector is much larger than that of the single-beam type, the horizontal field of view can be greater than 90°, and the vertical field of view can reach a maximum of 90°, but the effective distance is relatively short. All lenses focus on the pyroelectric device set inside, so the sensitivity is high, and an alarm will be triggered as long as someone walks in the lens field of view.
In addition to perimeter alarms, this technology has also been added to many home anti-theft devices, such as the EZVIZ video lock. After implanting this technology, it can achieve 24-hour automatic sensing. When there is an abnormal movement at the door of the house, it can capture and record in real time, and push abnormal messages to the user's mobile phone, 24-hour online protection, truly realizing active defense. Although due to the Fresnel lens, missed reports may occur, but the passive infrared detector lens independently developed by EZVIZ adopts a unique texture design and is specially used in smart home entry scenarios, making the detection sensitivity higher, which can better reduce missed reports of sensing events and enhance the reliability of detection. Based on the passive infrared detector algorithm and passive infrared motion detector lens independently developed by EZVIZ, the detection sensitivity can be dynamically adjusted, which is more applicable to home entry scenarios of different types of households. The trigger time and sensitivity can be adjusted and set autonomously through the EZVIZ Cloud Video App, making the detection sensitivity higher, which can better reduce the missed reports of sensing events and enhance the reliability of detection.

Conclusion: With the continuous upgrading of criminal methods, people's requirements for residential safety technology prevention are getting higher and higher. Relying on traditional security measures can no longer meet people's safety needs, and passive infrared detector human infrared sensing will turn passive into active, "super double" the safety of people's lives and property.

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