SHWETA JINDAL

B.tech3rd year (EI)

BTBTN12410

Roll no. - 7733

INTRODUCTION

TYPES OF PROXIMITY SENSOR

CONSTRUCTION

WORKING

APPLICATIONS

ADVANTAGE

DISADVANTAGE

CONCLUSION

REFRENCES

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.

INDUCTIVE PROXIMITY SENSOR

CAPACITIVE PROXIMITY SENSOR

ULTRASONIC PROXIMITY SENSOR

OPTICAL PROXIMITY SENSOR

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

The Main Components Of The Inductive ProximitySensor Are. Coil, Oscillator, Detector And The OutputCircuit

The Operating Distance Of The Sensor Depends OnThe Actuator's Shape And Size And Is Strictly LinkedTo The Nature Of The Material

The Coil Generates The High Frequency MagneticField In Front Of The Face. When The Metallic TargetComes In This Magnetic Field It Absorbs Some Of TheEnergy

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.

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.

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.

The Main Components Of The Capacitive ProximitySensor Are Plate, Oscillator, Threshold Detector And TheOutput Circuit.

The Plate Inside The Sensor Acts As One Plate Of TheCapacitor And The Target Acts As Another Plate And TheAir Acts As The Dielectric Between The Plates.

The Capacitive Sensor Can Detect Any Targets WhoseDielectric Constant Is More Than Air

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.

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.

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.

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.

ADVANTAGES

They Are Useful And Can Help Many SecurityProblems.

DISADVANTGES

They Can Easily Be Set Off And Cause Problems.

They Are Expensive Than Inductive And CapacitiveProximity Sensor

APPLICATION

Optical proximity sensors mostly apply inautomobile/process eng. For distancemeasurement, level sensing etc.

Ultrasonic Sensor Are Some Type Used In PlaceOf Optical Sensors . Instead Of Using An LightBeam , A High Frequency Sound Wave Is Used.

This Sound Wave Is Above Normal HearingFrequencies And Are Called UltrasonicFrequencies Around 40 KHz Are Common.

The Ultrasonic Sensor Can Measure Distances InCentimeters And Inches. It Provides GoodReadings In Sensing Large-sized Objects WithHard Surfaces.

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).

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.

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.

The global market for these proximity sensors isexpected to grow at a steady rate. Majorindustries using proximity sensors are machinetools, woodworking machines, packagingmachines and other types of machinery.

Further applications of are automatic door unitssuch as garage doors or doors inside buildings,elevator doors or doors inside railway coaches.

The building and automotive sector are furtherindustries using high volumes of proximitysensors.

http://literature.rockwellautomation.com/idc/groups/literature/documents/ca/c116-ca502_-en-p.pdfhttp://en.wikipedia.org/wiki/Proximity_sensorhttp://www.fargocontrols.com/sensors.htmlhttp://www.autonics.co.in/products/products_2.php?big=01&mid=01/01http://www.ia.omron.com/support/guide/41/overview.htmlhttp://www.sensorcentral.com/photoelectric/proximity01.phphttp://www.engineershandbook.com/Components/proximitysensors.htm