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Proximity sensor
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<h2 id="use-with-smartphones-and-tablet-computers">Use with smartphones and tablet computers</h2> <p>Proximity sensors are commonly used on <a href="/facts/Mobile_device/cNS1Rhvg">mobile devices</a>.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> When the target is within nominal range, the device <a href="/facts/Lock_screen/jlS2PYce">lock screen</a> user interface will appear, thus emerging from what is known as <a href="/facts/Sleep_mode/lj6HSbyU">sleep mode</a>. Once the <a href="/facts/Machine/wTCxFRfs">device</a> 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 a <a href="/facts/Telephone_call/4wUtUXpY">telephone call</a>, proximity sensors play a role in detecting (and skipping) accidental touchscreen taps when mobiles are held to the ear.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p><p>Proximity <a href="/facts/Sensor/RN8SXbjs">sensors</a> can be used to recognise air gestures and hover-manipulations. An array of proximity sensing elements can replace <a href="/facts/Vision_camera/cxQ5Y2PK">vision-camera</a> or <a href="/facts/Depth_camera/MSySNrR1">depth camera</a> based solutions for <a href="/facts/Gesture_recognition/jly3YdnY">hand gesture detection</a>. </p> <h2 id="types-of-sensors">Types of sensors</h2> <ul><li><a href="/facts/Capacitive_sensing/KqI9zuD4">Capacitive</a></li> <li><a href="/facts/Capacitive_displacement_sensor/llHy3L2P">Capacitive displacement sensor</a></li> <li><a href="/facts/Doppler_effect/bzrK1BKf">Doppler effect</a> (sensor based on <a href="/facts/Doppler_effect/bzrK1BKf">doppler effect</a>)</li> <li><a href="/facts/Inductive_sensor/IrqGAK55">Inductive</a></li> <li><a href="/facts/Magnetic/eo75vApl">Magnetic</a>, including <a href="/facts/Magnetic_proximity_fuse/65hN6bA5">magnetic proximity fuse</a></li> <li>Optical <ul><li><a href="/facts/Photoelectric_sensor/Kvzf7YbQ">Photoelectric</a></li> <li><a href="/facts/Photocell/7cSkXS6s">Photocell</a> (reflective)</li> <li><a href="/facts/Laser_rangefinder/XlejNw9I">Laser rangefinder</a></li> <li>Passive (such as <a href="/facts/Charge-coupled_device/l6xffIcz">charge-coupled devices</a>)</li> <li>Passive thermal <a href="/facts/Infrared/44XdJNcc">infrared</a></li></ul></li> <li><a href="/facts/Radar/jk9BTbFA">Radar</a></li> <li>Reflection of ionizing radiation</li> <li><a href="/facts/Sonar/0Rg2G40e">Sonar</a> (typically active or passive)</li> <li><a href="/facts/Ultrasonic_sensor/6Ala5r9z">Ultrasonic sensor</a></li> <li><a href="/facts/Optical_fiber/5ruuIFbj">Fiber optics</a> sensor</li> <li><a href="/facts/Hall_effect_sensor/bITzh0dk">Hall effect sensor</a></li></ul> <h2 id="applications">Applications</h2> <ul><li><a href="/facts/Parking_sensors/kSJo9MHe">Parking sensors</a>, systems mounted on car bumpers that sense distance to nearby cars for parking</li> <li><a href="/facts/Inductive_sensor/IrqGAK55">Inductive sensors</a></li> <li><a href="/facts/Ground_proximity_warning_system/tG8SNSuw">Ground proximity warning system</a> for aviation safety</li> <li>Vibration measurements of rotating shafts in machinery</li> <li>Top <a href="/facts/Dead_centre_(engineering)/2rj7bHWc">dead centre</a> (TDC)/<a href="/facts/Camshaft/qS8BWXVr">camshaft</a> sensor in <a href="/facts/Reciprocating_engine/ItLAxmW3">reciprocating engines</a>.</li> <li>Sheet break sensing in paper machine.</li> <li><a href="/facts/Anti-aircraft_warfare/fHtGQpLy">Anti-aircraft warfare</a></li> <li><a href="/facts/Roller_coaster/Khc6UWax">Roller coasters</a></li> <li><a href="/facts/Conveyor_system/m5SqfJcI">Conveyor systems</a></li> <li><a href="/facts/Bottling_line/VcNWsRuI">Beverage</a> and <a href="/facts/Canning/3v7LsDuY">food can</a> making lines</li> <li><a href="/facts/Mobile_device/cNS1Rhvg">Mobile devices</a> <ul><li><a href="/facts/Touch_screen/zpSKDFpe">Touch screens</a> that come in close proximity to the face<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a></li> <li>Attenuating radio power in close proximity to the body, in order to reduce <a href="/facts/Mobile_phone_radiation_and_health/VyGtge7s">radiation exposure</a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a></li></ul></li> <li><a href="/facts/Automatic_faucet/wcl1Q8mz">Automatic faucets</a></li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Motion_detector/DqDHAPT6">Motion detector</a></li> <li><a href="/facts/Occupancy_sensor/PnHS3vlU">Occupancy sensor</a></li> <li><a href="/facts/Range_imaging/MSySNrR1">Range imaging</a></li> <li><a href="/facts/Time_of_flight_detector/DE8hXxHa">Time of flight detector</a></li></ul> Wikimedia Commons has media related to Proximity sensors. <h2 id="references">References</h2> <ol> <li id="fn:1"><p>O'Brien, Daniel J. (2021-03-22). "A guide for incorporating e-teaching of physics in a post-COVID world". American Journal of Physics. 89 (4): 403–412. doi:10.1119/10.0002437. ISSN 0002-9505. S2CID 221139614. <a href="https://aapt.scitation.org/doi/10.1119/10.0002437" target="_blank">https://aapt.scitation.org/doi/10.1119/10.0002437</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Proximity sensor on Android smartphones". TheCodeArtist. <a href="http://thecodeartist.blogspot.com/2011/01/proximity-sensor-on-android-gingerbread.html" target="_blank">http://thecodeartist.blogspot.com/2011/01/proximity-sensor-on-android-gingerbread.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Proximity sensor on Android smartphones". TheCodeArtist. <a href="http://thecodeartist.blogspot.com/2011/01/proximity-sensor-on-android-gingerbread.html" target="_blank">http://thecodeartist.blogspot.com/2011/01/proximity-sensor-on-android-gingerbread.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Phillips, Jon. "Can a $100 iPad Case Improve 3G Data Power? Lab Test!". Wired. <a href="https://www.wired.com/gadgetlab/2011/12/pong-ipad-case-investigation/all" target="_blank">https://www.wired.com/gadgetlab/2011/12/pong-ipad-case-investigation/all</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> </ol>