A proximity detector is a device which can detect objects in close proximity to itself. These devices can be installed on stationary and moving objects, and may be used in a variety of ways. The sophistication of a proximity detector varies, and the more sophisticated it is, the more expensive it tends to be. Such devices are available from a variety of sources, including electronics stores, robotics manufacturers, and stores which stock safety equipment.
Proximity detectors can operate in several different ways. One technique involves generating a constant beam of infrared light and measuring the reflection of the light to check for movement and objects in close proximity. Another method is to use sound, in a sonar system which bounces sound waves off objects to find out where they are. Proximity detectors can also rely on changes in capacitance caused by mutual capacitance, or can operate with magnetic detectors.
One common use of a proximity detector is in a collision avoidance system. Such systems are used to sound an alert or to take an action if a collision appears likely. They can be installed on boats, cars, and other vehicles, and they are also used by robots to ensure that they will not bump into things as they move around. The most basic system will simply activate an alarm if something gets too close, while more advanced systems can take evasive maneuvers to prevent a crash.
Another use of a proximity detector is in a security system which is designed to alert people to the presence of intruders. These systems take note when bodies are where they are not supposed to be, and they can send a signal, activate an alarm, or activate things like protective doors which will close to secure the area. A proximity detector can also be used to turn on lights, which may be done for security, safety, and convenience; when someone arrives home at night, for example, it can help to have a porch light come on.
People can also build their own proximity detectors. Such projects are popular in electronics classes for students who want to learn more about the details of building electronic components from the ground up and among people who are trying to refine the details of a specific project they are working on. These individuals may find it more convenient to build a proximity detector than to adapt an existing piece of equipment which may not be quite suited to their specific needs.