Proximity Sensor Detects An Object When The Object Approaches Within The Detection Range And Boundary Of The Sensor. Proximity Sensor Includes All The Sensor That Perform Non Contact Detection In Comparison To Sensors Such As Limit Switch, That Detect The Object By Physically Contacting Them. It 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 or photoelectric sensor might be suitable for a plastic target; an inductive proximity sensor always requires a metal target. The maximum distance that this sensor can detect is defined "nominal range". Some sensors have adjustments of the nominal range or means to report a graduated detection distance. Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object. Proximity sensors are commonly used on smart phones to detect (and skip) accidental touch screen taps when held to the ear during a call.[1] They 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 change in the sensor's electric or magnetic field can also be used to determine proximity.

1. SHWETA JINDAL
B.tech3rd year (EI)
BTBTN12410
Roll no. - 7733

2. INTRODUCTION
TYPES OF PROXIMITY SENSOR
CONSTRUCTION
WORKING
APPLICATIONS
ADVANTAGE
DISADVANTAGE
CONCLUSION
REFRENCES

3. A Proximity Sensor Detects An Object When The
Object Approaches Within The Detection Range And
Boundary Of The Sensor.
Proximity Sensor Includes All The Sensor That Perform
Non Contact Detection In Comparison To Sensors Such
As Limit Switch ,That Detect The Object By Physically
Contacting Them.

4.  INDUCTIVE PROXIMITY SENSOR
 CAPACITIVE PROXIMITY SENSOR
 ULTRASONIC PROXIMITY SENSOR
 OPTICAL PROXIMITY SENSOR

5.  An Inductive proximity sensor is an electronic
proximity sensor , which detect metallic object
without touching them.
 Their operating principle is based on a coil and
high frequency oscillator that creates a field in
the close surrounding of the sensing surface .
 The operating distance of the sensor depends on
the coil’s size as well as the target ‘s shape, size
and material

6.  The Main Components Of The Inductive Proximity
Sensor Are. Coil, Oscillator, Detector And The Output
Circuit
 The Operating Distance Of The Sensor Depends On
The Actuator's Shape And Size And Is Strictly Linked
To The Nature Of The Material
 The Coil Generates The High Frequency Magnetic
Field In Front Of The Face. When The Metallic Target
Comes In This Magnetic Field It Absorbs Some Of The
Energy

7.  Hence the oscillator field is affected. The rise or
fall of such oscillation is identified by a threshold
circuit..that changes the output of the sensor.

8. ADVANTAGES
 they are very accurate compared to other
technologies.
 Have high switching rate.
 Can work in harsh environmental conditions.
DISADVANTAGES
 It can detect only metallic target.
 Operating range may be limited.

10.  Capacitive Sensor Are Used For Non Contact
Detection Of Metallic Object And Non Metallic
Object(liquid, Plastic, Wooden Material Etc.)
 Capacitive Proximity Sensors Use The Variation Of
Capacitance Between The Sensor And Object Being
Detected.
 Capacitance Methods Are Very Sensitive ,
Distance Down To One Micro Inch Can Be Measured.

11.  The Main Components Of The Capacitive Proximity
Sensor Are Plate, Oscillator, Threshold Detector And The
Output Circuit.
 The Plate Inside The Sensor Acts As One Plate Of The
Capacitor And The Target Acts As Another Plate And The
Air Acts As The Dielectric Between The Plates.
 The Capacitive Sensor Can Detect Any Targets Whose
Dielectric Constant Is More Than Air

12. Cont..
 As the object comes close to the plate of the
capacitor the capacitance increases and as the
object moves away the capacitance decreases
 an electronic circuit inside the sensor begins to
oscillate. The rise or the fall of such oscillation is
identified by a threshold circuit and based on
that output switches.

13. ADVANTAGES
 It can detect both metallic and non metallic
targets.
 Good stability
 High Speed
 Capacitive sensors are good in terms of power
usage
 Low cost
DISADVANTAGES
 They are affected by temperature and humidity
 Difficulties in designing
 Capacitive proximity sensors are not as accurate
compare to inductive sensors.

15.  The Proximity Of The Object Is Detected By The Action
Of The Travelling Light Move.
 These Sensors Use Light Sensitive Elements To Detect
Objects And Are Made Up Of An Transmitter (Light
Source) And A Receiver
 The Object Within The Range Of The Sensor Can Detect
The Presence.

16.  The Light Emitted By The Transmitter Focuses On The
Object Which Reflects To Be Received By The Receiver
Photo Diode.
 The Reflected Waves Travel Back And Received By The
Solid State Photo Diode, Through The Receiver Lens.

17. ADVANTAGES
 They Are Useful And Can Help Many Security
Problems.
DISADVANTGES
 They Can Easily Be Set Off And Cause Problems.
 They Are Expensive Than Inductive And Capacitive
Proximity Sensor
APPLICATION
 Optical proximity sensors mostly apply in
automobile/process eng. For distance
measurement, level sensing etc.

18.  Ultrasonic Sensor Are Some Type Used In Place
Of Optical Sensors . Instead Of Using An Light
Beam , A High Frequency Sound Wave Is Used.
 This Sound Wave Is Above Normal Hearing
Frequencies And Are Called Ultrasonic
Frequencies Around 40 KHz Are Common.
 The Ultrasonic Sensor Can Measure Distances In
Centimeters And Inches. It Provides Good
Readings In Sensing Large-sized Objects With
Hard Surfaces.

19.  The ultrasonic sensor sends out sound and receives
it back using the receiver. Together, the ultrasonic
sensor's sender and receiver look like a pair of eyes,
but it is not a sight sensor. Instead, those "eyes" are
really more like a speaker and a microphone (a sound
sensor).

21. CONT.
 The Emitter And Detector Are 2 Separate Units. The
Emitter Emits The Light Which Is Detected By The
Detector. A Target Is Detected When It Passes In-between
The Emitter And Detector.

22. ADVANTAGES
 Ultrasonic proximity sensors are not affected
by atmospheric dust, snow, rain..etc
 Can work in adverse conditions
 Sensing distance is more compared to
inductive or capacitive proximity sensors
DISADVANTAGES
 Ultrasonic sensors Has More Difficulties
Reading Reflections From Soft, Curved, Thin
Or Small Objects.

23.  The global market for these proximity sensors is
expected to grow at a steady rate. Major
industries using proximity sensors are machine
tools, woodworking machines, packaging
machines and other types of machinery.
 Further applications of are automatic door units
such as garage doors or doors inside buildings,
elevator doors or doors inside railway coaches.
 The building and automotive sector are further
industries using high volumes of proximity
sensors.

24. http://literature.rockwellautomation.com/idc/groups/l
iterature/documents/ca/c116-ca502_-en-p.pdf
http://en.wikipedia.org/wiki/Proximity_sensor
http://www.fargocontrols.com/sensors.html
http://www.autonics.co.in/products/products_2.php?b
ig=01&mid=01/01
http://www.ia.omron.com/support/guide/41/overview
.html
http://www.sensorcentral.com/photoelectric/proximity
01.php
http://www.engineershandbook.com/Components/pro
ximitysensors.htm