16-03-2011, 03:43 PM
Presented by:
Pooja S Kulkarni
[attachment=10329]
Sensors
List of sensors:
Photo sensors
Motion sensors
Pressure sensors
Temperature sensors
Proximity switches
Passive sensors:
Infrared Radiation:
Infrared radiation exists in the electromagnetic spectrum at a wavelength that is longer than visible light.
Objects that generate heat also generate infrared radiation and can be detected.
Radiation is strongest at a wavelength of 9.4um.
Passive sensors:
Pyroelectric Sensors:
◦ The pyroelectric sensor is made of a crystalline material that generates a surface electric charge when exposed to heat in the form of infrared radiation.
◦ When the amount of radiation striking the crystal changes, the amount of charge also changes and can then be measured with a sensitive FET device built into the sensor.
Active Sensors:
Inductive Proximity Sensors
Inductive proximity sensors operate under the electrical principle of inductance.
An inductive proximity sensor has four components; The coil, oscillator, detection circuit and output circuit.
Capacitive Proximity Sensors
Capacitive proximity sensors are similar to inductive proximity sensors.
The main difference between the two types is that capacitive proximity sensors produce an electrostatic field instead of an electromagnetic field.
Capacitive proximity switches will sense metal as well as nonmetallic materials such as paper, glass, liquids, and cloth.
Photo sensors:
These sensors use light sensitive elements to detect objects and are made up of an emitter (light source) and a receiver. Four types of photoelectric sensors are available.
Direct Reflection –
◦ emitter and receiver are housed together and use the light reflected directly off the object for detection.
◦ In the use of these photocells, it is important to bear in mind the color and the type of surface of the object.
Reflection with Reflector –
emitter and receiver are housed together and requires a reflector.
An object is detected when it interrupts the light beam between the sensor and reflector.
These photocells allow longer sensing distances, as the rays emitted are almost totally reflected towards the receiver.
Polarized Reflection with Reflector - similar to Reflection with Reflector, these photocells use an anti-reflex device.
Thru Beam - emitter and receiver are housed separately and detect an object when it interrupts the light beam between the emitter
and receiver. These photocells allow for the longest distances.
Pooja S Kulkarni
[attachment=10329]
Sensors
List of sensors:
Photo sensors
Motion sensors
Pressure sensors
Temperature sensors
Proximity switches
Passive sensors:
Infrared Radiation:
Infrared radiation exists in the electromagnetic spectrum at a wavelength that is longer than visible light.
Objects that generate heat also generate infrared radiation and can be detected.
Radiation is strongest at a wavelength of 9.4um.
Passive sensors:
Pyroelectric Sensors:
◦ The pyroelectric sensor is made of a crystalline material that generates a surface electric charge when exposed to heat in the form of infrared radiation.
◦ When the amount of radiation striking the crystal changes, the amount of charge also changes and can then be measured with a sensitive FET device built into the sensor.
Active Sensors:
Inductive Proximity Sensors
Inductive proximity sensors operate under the electrical principle of inductance.
An inductive proximity sensor has four components; The coil, oscillator, detection circuit and output circuit.
Capacitive Proximity Sensors
Capacitive proximity sensors are similar to inductive proximity sensors.
The main difference between the two types is that capacitive proximity sensors produce an electrostatic field instead of an electromagnetic field.
Capacitive proximity switches will sense metal as well as nonmetallic materials such as paper, glass, liquids, and cloth.
Photo sensors:
These sensors use light sensitive elements to detect objects and are made up of an emitter (light source) and a receiver. Four types of photoelectric sensors are available.
Direct Reflection –
◦ emitter and receiver are housed together and use the light reflected directly off the object for detection.
◦ In the use of these photocells, it is important to bear in mind the color and the type of surface of the object.
Reflection with Reflector –
emitter and receiver are housed together and requires a reflector.
An object is detected when it interrupts the light beam between the sensor and reflector.
These photocells allow longer sensing distances, as the rays emitted are almost totally reflected towards the receiver.
Polarized Reflection with Reflector - similar to Reflection with Reflector, these photocells use an anti-reflex device.
Thru Beam - emitter and receiver are housed separately and detect an object when it interrupts the light beam between the emitter
and receiver. These photocells allow for the longest distances.