Why not use active infrared sensors as human presence sensors?
The working principle of active infrared sensors is to determine the position and shape of objects by emitting infrared rays and then reflecting them back from the objects. However, the human body is a very complex object, and the infrared rays reflected by it will also be affected by many factors, such as the posture of the human body, the color and texture of the clothes, etc.
Therefore, using active infrared sensors to determine the presence of the human body is not a very accurate method. Secondly, active infrared sensors still have some limitations.
First, active infrared sensors are easily interfered with. For example, external light sources such as indoor lights and sunlight will affect the reflection of infrared rays, thereby affecting the judgment of the sensor. Secondly, active infrared sensors require power support, so they need to replace batteries or connect to power regularly, which will bring certain inconveniences to some devices that are used for a long time.
In fact, we already have better ways to determine the presence of the human body, such as radar technology, ultrasonic technology, etc. These technologies can not only accurately determine the presence of the human body, but also have the advantages of strong anti-interference ability and no need for power support, making them more suitable as human presence sensors.
Although active infrared sensors can determine the position and shape of objects, their limitations such as being easily interfered with by external sources and requiring power support limit their application in human presence sensors. Better methods such as radar technology and ultrasonic technology have become the preferred choice for human presence sensors.
