 Proximity switches open or close an electrical circuit when they make contact with or come within a certain distance of an object. electrical circuit  Most commonly used in manufacturing equipment, robotics, and security systems  Proximity switches and sensors use a reed switch and a permanent magnet.

Normally Open

Normally Close

 Infrared proximity switch  Acoustic proximity sensor  Inductive proximity switch  Capacitive proximity switch

 work by sending out beams of invisible infrared light.  A photodetector on the proximity switch detects any reflections of this light.

Infrared proximity switch

 are similar in principle to infrared models, but use sound instead of light.  They use a transducer to transmit inaudible sound waves at various frequencies in a preset sequence,transducer  measure the time it takes for sound pulses to "echo" and use this measurement to calculate distance, just like sonar.sonar

 distance to objects by generating magnetic fields.  They are similar in principle to metal detectors.metal detectors  The chief disadvantage of inductive proximity switches is that they can only detect metallic objects.

Inductive Proximity Switch

 sense distance to objects by detecting changes in capacitance around it.capacitance  These proximity switches have the disadvantage of being more sensitive to objects that conduct electricity than to objects that do not.

Capacitive Proximity Switch

 gives a switched output on detecting something coming into proximity.

 The AD7150 is an ultra-low-power, 2- channel, capacitance converter designed for highly sensitive proximity sensing applications.  It provides a complete signal processing solution for proximity sensors offering important features such as Electromagnetic Compatibility, adaptive environmental calibration, small package, low power consumption and fast response time.

Intelligent sensor families deliver high sensitivity, low power, low cost and small size with robustness.

The MPR08X Proximity Sensing Controllers from Freescale Semiconductor

 support multiple electrodes, controlling several different applications from one sensor.  By multiplexing the electrodes, a single sensor becomes an extension for detection at multiple points.

 Additionally, Freescale's Proximity Sensing Software solution transforms any RS08, S08 or V1 ColdFire® MCUs into a proximity capacitive-touch sensor controller.  A software, GUI and hardware solution can get a sensing application up and running very quickly.

 A mobile communication terminal having a function of detecting a proximity touch and a display controlling method therein are disclosed.

It switch off screen using proximity sensor detection.

 The tweak uses the HD2’s proximity sensor to turn of the screen when a finger or any object is detected in front of it.  After proximity detected – screen switched off and proximity sensor don’t used until screen will be switched on again manually.

Freescale's MC33794 Proximity Sensor

 The MC33794 proximity sensor relies on interruption of an electric field, using a low frequency sine wave with very low harmonic content whose frequency is adjustable by an external resistor.