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Proximity sensor

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About proximity sensor

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Optical proximity sensor in a 2016Samsung smartphone. A proximity sensor is a standard feature of most smartphones, disabling the touchscreen when positioned near an ear during phone calls; more recent (late 2019-early 2020) smartphones with OLED displays may have the sensor mounted under the display.

Smartphone optical proximity sensor without the phone's casing. The sensor itself is the black object on top of the yellow block below it; this block is actually aprinted circuit board serving as aninterposer.

Aproximity sensor (often simplyprox) is asensor able to detect the presence of nearby objects without any physical contact.

A proximity sensor often emits anelectromagnetic field or a beam ofelectromagnetic radiation (infrared, for instance), and looks for changes in thefield or returnsignal. The object being sensed is often referred to as the proximity sensor's target. Different proximity sensor targets demand different sensors. For example, acapacitive proximity sensor orphotoelectric sensor might be suitable for a plastic target; aninductive proximity sensor always requires a metal target.^{[citation needed]}

Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between the sensor and the sensed object.

Proximity sensors are also used in machine vibration monitoring to measure the variation in distance between a shaft and its support bearing. This is common in large steamturbines,compressors, and motors that use sleeve-typebearings.

A proximity sensor adjusted to a very short range is often used as atouch switch.

Use with smartphones and tablet computers

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Proximity sensors are commonly used onmobile devices.^[1] When the target is within nominal range, the devicelock screen user interface will appear, thus emerging from what is known assleep mode. Once thedevice has awoken from sleep mode, if the proximity sensor's target is still for an extended period of time, the sensor will then ignore it, and the device will eventually revert into sleep mode. For example, during atelephone call, proximity sensors play a role in detecting (and skipping) accidental touchscreen taps when mobiles are held to the ear.^[2]

Proximitysensors can be used to recognise air gestures and hover-manipulations. An array of proximity sensing elements can replacevision-camera ordepth camera based solutions forhand gesture detection.