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Proximity sensors detect distance between objects. They use sound, electromagnetic radiation, and changes in electric or magnetic fields. They are used in navigation, touch screens, security systems, and electronic equipment.
A proximity sensor is a device used to determine the relative distance of another object. There are many different types of these sensors and they can be used for many purposes. Long-range sensors are commonly used in navigation to determine if there are other vessels or obstacles nearby. Short-range sensors can be used to warn that an object is too close to the sensor. Versions of these sensors are also used in various types of electronic equipment and security systems.
There are several ways a proximity sensor can determine where an object is relative to the location of the sensor. One way is to make the sound and track the time it takes for the sound to bounce off another object and return. Navigation and audible distance (SONAR) is an example of this type of proximity sensor and is often used to determine how close water vessels are to each other. Electromagnetic radiation, such as radio range and bearing (RADAR) can also be used to determine how close an object is to the sensor based on how long it takes for it to hit the object and then return to the source.
A change in the sensor’s electric or magnetic field can also be used to determine proximity. A proximity sensor sensitive to this type of change, such as an eddy current sensor, is often used in touch screens. It can determine that a person’s finger or a stylus made of a conductive material has touched the screen because it conducts a small amount of electricity to the screen. Photo sensors, which detect changes in the light reaching the proximity sensor, are also often used to determine short-range proximity.
There are many applications for technologies that use proximity sensors. The first use of this type of technology was to track the movements of large objects, such as boats or planes. In 2011, many private vehicles are equipped with proximity sensors, especially in the rear of the vehicle, to alert the driver that the vehicle is approaching another object. Homes and some appliances also use proximity sensors that determine if doors and windows are closed. Electronics have proximity sensors on touch screens or, in the case of many cell phones, to determine when the screen is close to a person’s face.
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