Types of Infrared Motion Detectors

Infrared motion sensors are common in many home security systems and other everyday places such as stores. Infrared motion detectors are relatively inexpensive and effective in an enclosed environment. They work by measuring the radiation emitted from the surroundings and anything crossing in front of the sensors.

Types

Infrared detectors most commonly found are referred to as PID (passive infrared detection) sensors. Consumer sensors include ceiling detectors, pet-proof sensors and general area sensors.

Another type of sensor is an infrared point sensor. This sensor has dual emitters and receivers and is capable of detecting combustible gases in an area. These are most useful in small, confined areas where dangerous gas levels may be present.

Function

A PID works by measuring drastic changes in ambient radiation. The detector is aimed in the room and measures the ambient radiation coming from it, and if there is a change in the levels it reads, it will trigger an alarm. Humans and animals release drastically different amounts of radiation than inanimate objects like walls, doors and plants, which makes these sensors ideal for home security.

Benefits

Basic home security systems usually include magnetic door and window contacts and motion sensors. Using motion sensors in a home security system allows for a customized home security system. The perimeter can be secured while people are in the house, and the motion sensors can be activated while the house is empty, helping to ensure that the house is secured, inside and out.

Other Uses

Many stores will have a motion activated alarm that will alert people working in the store that there is a customer; this is an example of motion sensor technology. A beam will be transmitted from an emitter to a receiver. If the beam is broken by someone or something crossing in front of it, it will set off the alarm.

Also commonly found in stores, motion activated automatic doors use infrared detectors. Automatic door sensors are most like home security sensors, and they operate with the same technology.

Motion sensing lights are also commonly used for home security and detection and use infrared radiation detection to trigger an outside light.

Considerations

Motion sensors can be circumvented in home security, or alarms can be triggered inadvertently. Motion sensors can be set off by household pets that cross the location of the beams; however, there are types of sensors that have a different threshold setting to be "pet-proof." The motion sensors also detect drastic changes in the sensing area, and minor changes will not set off the alarm.

Infrared radiation can also not be viewed through glass. This makes the infrared detectors ideal for homes, because they will not be tripped by anything outside of the house.

References

• How Sensors Work
• PIR Sensors
• Point Source Detector