The working principle of passive infrared detectors and common false positive solutions!

As the earliest type of security equipment, infrared detectors are also widely used in various aspects. According to their different performances, infrared detectors can be divided into active infrared detectors and passive infrared detectors. Give everyone the science of passive infrared detectors and common false alarms.

First, the principle of passive infrared detector

In nature, any object above the absolute temperature (-273 degrees) will produce an infrared spectrum. In the passive infrared warning zone, when no object moves, the pyroelectric infrared sensor only senses the background temperature when moving the object. Entering the warning zone, through the Fresnel lens, the pyroelectric infrared sensor senses the difference between the temperature of the moving object and the background temperature, and the alarm signal sent after the infrared signal change is converted into an electrical signal. The passive infrared detector itself does not emit in the infrared spectrum.

After understanding the working principle of the passive infrared detector, let's take a look at what causes some false alarms that often occur.

First, the false alarm caused by equipment failure

1. Damaged faults. Including all failures and sudden failures of performance. Such failures are usually caused by damage to components or poor manufacturing processes (such as soldering, false soldering, etc.).

2. Drift failure. It refers to the fault caused by the parameter of the component and the excessive drift of the power supply voltage. For example, if the temperature is too high, it will cause a change in the resistance value. At this time, the device behaves as good or bad.

Second, false alarms caused by environmental changes

1. The infrared detector is not installed securely and often moves to cause false alarms;

2. A false alarm is caused by the temperature change of the air conditioner and the ventilation fan;

3. When the temperature difference between indoor and outdoor is large, the wind blows the curtain to cause false alarm;

4, multiple detectors simultaneously transmit signals, which can cause false negatives or interference (only wireless type);

5. The alarm system causes false alarms to other wireless infrared detectors. The device behaves as good or bad (only wireless).

Like the above factors that cause false alarms, we also need to have a corresponding solution.

1. Install an infrared detector according to the installation requirements of the manual;

2. Avoid areas with strong temperature difference and air convection;

3. Close the doors and windows or bind the curtains;

4. Reduce the cross-detection range of the prevention area and avoid transmitting the alarm signal at the same time;

5, the code is fast and accurate, to prevent mis-recording information.

After understanding the above knowledge, is there any more understanding of our infrared detectors? Shanghai Keou Security is a manufacturer specializing in the manufacture of alarm security products. The design, production and sales of products are carried out simultaneously. It is also expected that more and more people will understand the security of the passengers.