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Proximity sensor

About proximity sensor

A proximity sensor (often simply prox) is a sensor able to detect the presence of nearby objects without any physical contact.

A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensor's target. Different proximity sensor targets demand different sensors. For example, a capacitive proximity sensor or photoelectric sensor might be suitable for a plastic target; an inductive proximity sensor always requires a metal target.

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 steam turbines, compressors, and motors that use sleeve-type bearings.

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

Use with smartphones and tablet computers

Proximity sensors are commonly used on mobile devices. When the target is within nominal range, the device lock screen user interface will appear, thus emerging from what is known as sleep mode. Once the device 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 telephone call, proximity sensors play a role in detecting (and skipping) accidental touchscreen taps when mobiles are held to the ear.

Proximity sensors can be used to recognise air gestures and hover-manipulations. An array of proximity sensing elements can replace vision-camera or depth camera based solutions for hand gesture detection.

File:BlackBerry Leap-sensores array infrared proximity-dark red PNr°0725.jpg|The pulsing proximity sensor of a BlackBerry Leap File:BlackBerry Leap-sensores array infrared proximity-I6400 VNr°0004.webm|Video of the pulsing proximity sensor of a BlackBerry Leap

Types of sensors

Capacitive
Capacitive displacement sensor
Doppler effect
Inductive
Magnetic, including magnetic proximity fuse
Optical
- Photoelectric
- Photocell (reflective)
- Laser rangefinder
- Passive (such as charge-coupled devices)
- Passive thermal infrared
Radar
Reflection of ionizing radiation
Sonar (active or passive)
Ultrasonic sensor
Fiber optics sensor
Hall effect sensor

Applications

Proximity sensor installed on the front of an iPhone 5 next to the earpiece automatically turning off the touchscreen when the sensor comes within a predefined range of an object (such as a human ear) when using the handset

Parking sensors, systems mounted on car bumpers that sense distance to nearby cars for parking
Inductive sensors
Ground proximity warning system for aviation safety
Vibration measurements of rotating shafts in machinery
Top dead centre (TDC)/camshaft sensor in reciprocating engines.
Sheet break sensing in paper machine.
Anti-aircraft warfare
Roller coasters
Conveyor systems
Beverage and food can making lines
Mobile devices
- Touch screens that come in close proximity to the face
- Attenuating radio power in close proximity to the body, in order to reduce radiation exposure
Automatic faucets

References

O'Brien, Daniel J.. (2021-03-22). "A guide for incorporating e-teaching of physics in a post-COVID world". American Journal of Physics.
"Proximity sensor on Android smartphones". TheCodeArtist.
Phillips, Jon. "Can a $100 iPad Case Improve 3G Data Power? Lab Test!".

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

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