Proximity sensors can detect objects without physical contact by emitting electromagnetic fields or beams and detecting changes in the fields. They have no moving parts so they are reliable with long lifespans. Proximity sensors are used to detect vibrations in machines and as touch switches. The main types are capacitive, inductive, radar, sonar, magnetic, photocell, and infrared proximity sensors. Capacitive sensors detect changes in capacitance from objects. Inductive sensors induce eddy currents in metals using magnetic fields. Radar and sonar use radio waves and ultrasound. Magnetic sensors detect disturbances in magnetic fields. Photocell and infrared sensors use light. Proximity sensors are used for applications like presence detection, object counting, and

1. Proximity Sensors
PRESENTED BY: 17BEE001
17BEE006
17BEE019
17BEE049

2. Introduction
 A proximity sensor 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.
 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.

3. Features
 Proximity Sensors detect an object without touching it, and they therefore do not cause abrasion or damage
to the object.
 No contacts are used for output, so the Sensor has a longer service life (excluding sensors that use
magnets). Proximity Sensors use semiconductor outputs, so there are no contacts to affect the service life.
 Unlike optical detection methods, Proximity Sensors are suitable for use in locations where water or oil is
used.
 Proximity Sensors provide high-speed response, compared with switches that require physical contact.
 Proximity Sensors can be used in a wide temperature ranging from -40 to 200°C.
 Proximity Sensors are not affected by colours.
 Unlike switches, which rely on physical contact, Proximity Sensors are affected by ambient temperatures,
surrounding objects, and other Sensors. Both Inductive and Capacitive Proximity Sensors are affected by
interaction with other Sensors.
 There are Two-wire Sensors. The power line and signal line are combined.

4. Types of Proximity Sensors
Capacitive Proximity Sensor
 As the name suggests, capacitive proximity sensors
operate by noting a change in the capacitance read by
the sensor.
 The way a capacitive proximity sensor works is that one
of the conductive elements or plates is inside the sensor
which is connected to an oscillator circuit that generates
an electric field itself while the other one is the object to
be sensed. The air gap between the plates serves as the
dielectric medium.
Inductive Proximity Sensor
 Inductive sensors operate on the basis of Faraday’s
Law. One way to state Faraday’s Law is that
whenever a conductor is placed in a oscillating
magnetic field an emf is induced in a conductor. This
is applied in inductive proximity sensors in the
following way: The sensor itself contains an oscillator
circuit and a coil from which an electromagnetic
field radiates out and induces eddy currents in any
nearby metallic objects. The eddy currents have the
effect of attenuating the oscillations from the
amplifier. This reduction in oscillations is registered
as the presence of a metallic object.

5. Types of Proximity Sensors
Radar proximity sensor
 The sensors emit fan-shaped beams of
high frequency radio waves to avoid false
alerts.
 It has a Sensing area upto 15m
 Used in Cars
Sonar proximity sensor
 An Sonar Proximity sensor uses Ultrasonic
Sound waves sent by a transducer at High
Frequency to measure the distance to an
object.
 It offers excellent non-contact range
detection with high accuracy and stable
readings in an easy-to-use package from 2
cm to 400 cm or 1” to 13 feet.

6. Types of Proximity Sensors
Magnetic proximity sensor
Magnetic sensors detect changes and
disturbances in a magnetic field like flux,
strength and direction. From established
knowledge about the existing magnetic field
and the data collected from sensors regarding
changes and alterations, many things can be
known. Rotation, angles, direction, presence and
electric current all can be monitored. Magnetic
sensors are divided into two groups, those that
measure the complete magnetic field and those
that measure vector components of the field.
The vector components are the individual points
of magnetic field. The techniques used to create
these sensors involve various combinations of
physics and electronics.
Photocell proximity sensor
Photocells and motion sensors are electronic
devices you can use to manage indoor or
outdoor lighting. These sensors improve the
security and safety of your home, automatically
turning on lights when it gets dark or they
detect motion. They also save energy by turning
themselves off when extra light is unnecessary.

7. Types of Proximity Sensors
Infrared proximity sensor
An infrared sensor is an electronic instrument that is used to sense certain characteristics of its
surroundings. It does this by either emitting or detecting infrared radiation. Infrared sensors are also
capable of measuring the heat being emitted by an object and detecting motion.
Features : Applications:
 Ambient light protected IR receiver - Proximity sensor
 3 pin easy interface connectors - Line Follower
 Indicator LED & Power LED - Wall Follower
 Distance 2cm to 30cm
 Can differentiate between dark and light colours.