Proximity sensors detect objects without coming into contact with them by emitting a high-intensity infrared beam. Some proximity sensors detect reflected light from an object, while others use two infrared beams and report any disruptions in the signal. More complex proximity sensors create two sensing zones that determine where objects can and cannot be detected, which is useful for sensors that need to ignore background objects.
Proximity sensors appear in consumer electronics, particularly mobile phones. The sensors are designed to detect the presence of a human ear for two reasons: to disable the touch screen during a phone call when a cheek or ear might inadvertently activate it and to turn off the LCD backlight and reduce power consumption. However, these sensors require a lot of energy, draining the battery, and can become inaccurate because of differences in skin color, temperature and hair.
Proximity sensors were invented in 1958. Initially, usage was limited to the chemical industry, but people began to realize the potential these sensors, had and the design was modified and improved. Proximity sensors are durable with a very long shelf life. The companies VariKont and Pepperl+Fuchs have since introduced a much more rugged proximity sensor that is waterproof, heat resistant and weather resistant.