As technology advances and becomes less intrusive, our computers and phones offer a wider variety of features-;and the lighting industry has followed suit. Motion light sensors do more with less effort, and they provide high security without using as much energy as other security measures. The technology is far from new, as infrared detectors have fulfilled many other purposes before being used in lighting and home security. In this article, we will explain how an Indoor Motion Sensor Light Fixture works.

The Function of a Motion Sensor Light

The method by which these lights detect motion and elicit a response is dependent upon whether the light has a PIR, or passive infrared detector. “Passive” indicates that the sensor receives infrared energy rather than emitting it; a PIR picks up infrared energy (heat) emitted by a person or object. Temperature differences are detected by the PID, and those differences are what triggers the response.

The Parts of a Motion Sensor

A passive motion sensor is made of a PCB (printed circuit board) containing a pyroelectric sensor chip. The board is mounted in a structure placed in an unobstructed location, and it serves as a decoder which interprets the signals received by the chip. The sensor chip responds to temperature shifts, and when it exceeds a predetermined limit, the chip will activate the light as intended.

A small window within the housing allows infrared energy to reach the sensor, and if a person or animal enters the area, the shifting temperature is detected. The window lets light through while protecting the sensor from dust and debris, while preventing false responses. Choosing the right location for an Indoor Motion Sensor Light Fixture is important; if it’s placed near a heat or cold source, false responses can result.


Motion sensor lights, as their name implies, trigger a response upon the detection of motion. They are versatile, and can be installed on walls, ceilings and doorways either indoors or outdoors. Some are called occupancy sensor lights, and work to keep lights off in unoccupied spaces. When a person enters the room, the lights are turned on, and are turned off when the person leaves. These motion lights are an easy and low-maintenance way to cut down on monthly utility bills.

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