sensors\types of sensors\working principle\Transducers\Actuators\proximity switches(sensors).

Sensor\types of sensors\working principle\Transducers\Actuators\proximity switches(sensors).

what is sensors?

A sensor is a device which converts a physical event into an electrical signal.or Sensors are sophisticated devices that are frequently used to detect and respond to electrical or optical signals.

working principle

Every sensor has different principle of operation, based on the type of physical quantity it is measuring. The idea is to create a change in the property/properties of sensor (such as resistance, density, shape, temperature etc) as a function of the physical quantity under measurement.

classification of the sensors

 they are divided into two part Active and Passive sensor.

1. active sensor-Active sensors have its own source of light or illumination. In particular, it actively sends a pulse and measures the backscatter reflected back to the sensor.EX- The radar is an active sensor,observation of the Earth's surface and atmosphere etc.
2. passive sensor-passive sensors measure reflected sunlight emitted from the sun. When the sun shines, passive sensors measure this energy.EX-: Photographic, thermal, electric field sensing, chemical, infrared and seismic.

Transducers

A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another.

Actuators

An actuator is a part of a device or machine which convert physical moments into electrical energy. 

Limit switch

limit switch is a switch operated by the motion of a machine part of or presence of an object.

working principle

• They are used for controlling machinery ,as a part of the control system ,as a safety interlock, or to convert object passing a point. A limit switch is an electromechanical device that consists of an actuator mechnecilly linked to a set of a contacts. when an object comes into contacts with the device operate the contacts to make a break and electrical connection.
• limit switches are used in variety of applications and environment because of their ruggedness, installation and reliability of operation they can determine the presence or absence, passing ,positioning and end of travel of an object.

applications

it is Industrial control component manufactured with a variety of operator types including liver, roller plunger,whisker type etc.

what is proximity switches(sensors)?

proximity switch open or closed and electrical circuit when sensor detect object within a certain distance.

different type of proximity switches(sensors)

inductive switches

• An inductive sensor is a device that uses the principle of electromagnetic induction to detect or measure objects. An inductor develops a magnetic field when a current flows through it; alternatively, a current will flow through a circuit containing an inductor when the magnetic field through it changes.An inductive sensor is a device that uses the principle of electromagnetic induction to detect or measure objects. An inductor develops a magnetic field when a current flows through it; alternatively, a current will flow through a circuit containing an inductor when the magnetic field through it changes.  
• This effect can be used to detect metallic objects that interact with a magnetic field.
• Non-metallic substances such as liquids or some kinds of dirt do not interact with the magnetic field, so an inductive sensor can operate in wet or dirty conditions. 

working principle

• The inductive sensor based on faradays law of induction the temporal variations of the magnetic flux through a circuit will induced voltage  e 

 which follows

• The coil may have a ferromagnetic core to make the magnetic field more intense and to increase the sensitivity of the device “high magnetic permeability core, such as a ferrite ceramic rod or coil form.
•  A coil with no ferromagnetic core ("air core") can also be used, especially if the oscillator coil must cover a large area. 
• Another form of inductive sensor uses one coil to produce a changing magnetic field, and a second coil (or other device) to sense the changes in the magnetic field produced by an object, for example, due to eddy currents induced in a metal object. 

Applications-electromagnetic waves measurement ,space magnetometer ,detect the metal position etc.

Capacitive sensor (switches)

In electrical engineering, capacitive sensing (sometimes capacitance sensing) is a technology, based on capacitive coupling, that can detect and measure anything that is conductive or has a dielectric different from air.

Working principle

Capacitance is the ability of an insulator to store an electric charge, and capacitive proximity sensing is based upon the principle of dielectric capacitance. A capacitor is composed of two plates separated by an insulator, also known as a dielectric.

Applications

·       Many types of sensors use capacitive sensing, it is detect and measure proximity, pressure, position and displacement, force, humidity, fluid level, and acceleration

·       Human interface devices based on capacitive sensing, such as trackpads can replace the computer mouse. Digital audio players, mobile phones, and tablet computers use capacitive sensing touchscreens as input devices. Capacitive sensors can also replace mechanical buttons.

capacitive sensors

 Optical sensors-An optical sensor converts light rays into electronic signals. It measures the physical quantity of light and then translates it into a form that is readable by an instrument.

Working principle

The operating principle is the transmitting and receiving of light in an optical sensor, the object to be detected reflects or interrupts a light beam sent out by an emitting diode. Depending on the type of device, the interruption or reflection of the light beam is evaluated. 

Applications

it's use in computer mouse, Xerox machine ,photo diode, phototransistor etc

EX-Adjustable range reflective type photoelectric sensor

Employing the optical triangulation method, it reliably senses an object at a given distance, irrespective of its reflectivity, by measuring the angle of the received beam. It contains an emitting lens and a receiving lens. The beam from the emitting lens falls on the sensing object and, after being reflected, is guided by the receiving lens onto a 2-segment diode. Here, the sensing object distance is determined by taking the position at which the upper and lower segments of the 2-segment photodiode generate equal output voltages as the reference. This method, besides being suitable for long distance, is also good for high accuracy position alignment. Further, the equal output voltages are obtained by adjusting the position of the receiving lens.

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