KWS Concepts – Passive infrared sensors
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Passive infrared sensors
Passive infrared sensors
How do passive infrared sensors work?
A passive infrared sensor (PIR sensor) reacts exclusively to changes in the infrared heat radiation hitting the sensor. In order to detect movements of objects, these must themselves emit heat. This means that mainly people and animals are detected. The sensor itself does not emit anything, in contrast to e.g. a laser scanner. This is often very important for monitoring paintings and other art objects to avoid damage. A movement of living beings behind a wall and glass can not be detected. If you combine several sensors to an array, you can monitor whole rooms, but also form surveillance curtains with appropriate lenses.
It is important that the FOV (Field Of View) does not become too large even after several meters distance from the sensor. Passive infrared curtains are used when there is no possibility of capacitive monitoring. Through the software used, each sensor in the array can be evaluated and thus specifically adapted to the object to be monitored.
The passive infrared sensor monitors valuable very flexible.
Passive infrared sensor array
In the example, the array has a lens that can monitor a room. The fields in the figure represent the FOV (Field Of View). If the array has many sensors, the surveillance fields will be smaller. The direction of movement of the person can be recognized: up, down, left, right and also diagonally. There are also lenses that can set up a surveillance curtain. The alarm criteria for all FOVs are then defined in the configuration software.
Here the person is in the “red” alarm area.
