proximity switch(English:proximity sensor) also calledproximity sensor, which is a device that can detect the presence of nearby objects without contactsensor.

Proximity sensors typically emitelectromagnetic fieldorElectromagnetic radiationbundle (e.g.infrared) and observeelectric fieldOr the change of the return signal to realize the function. The object that can be detected is called the target of the proximity switch. Different types of proximity switches have different goals, such asCapacitive Proximity SwitchorPhotoelectric switchpossible detectionplastictarget, andInductive proximityswitchCan only detect metal targets.

Sensors have a "nominal range" defined by their design, the maximum distance they can detect. Some sensors have the ability to adjust within the nominal range and to report the detection distance classification.

Therefore, the proximity switch has no mechanical parts, and there is no physical contact between the sensor and the object being sensed, resulting in high reliability and long service life.

Smartphones or similar mobile devices are often equipped with proximity switches. The device can wake up from sleep mode when a target is present within the nominal range. If the proximity sensor's target persists, the device can also ignore it and go back to sleep. A common design is that when using a smartphone to make a call, the proximity switch will detect the presence of the target and treat it as if it is placed in the ear, at which point the touchscreen will be temporarily turned off to avoid accidental operation.^[1]Proximity sensors are also used for vibration monitoring of some mechanical devices.

Proximity switches tuned to ultra-short distances can also be used as atact switch.

Proximity switch application

• Reversing radar,installed atcarbumpersystem that senses the distance to nearby vehicles for parking
• ground approach warning system
• Vibration measurement of rotating shafts in mechanical installations^[2]
• reciprocating enginein the upperstop(TDC)/camshaftsensor
• Paper Break Sensing in Paper Machines
• anti-aircraft gun
• roller coaster
• Conveyor system
• mobile device
  • Close when close to facetouch screen
  • Decrease radio power when close to body to cutradiation exposure^[3]
• automatic faucet

 

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