The encoder is a transducer of position and speed which converts the angular or linear motion of a shaft (or axle) into a series of electrical digital pulses. 

These electrical pulses are employed to control the motion of the mechanical shaft (that has generated them) as well as its displacement speed by operating on actuation devices of any type.

The encoder is formed by:

• Mechanical interface
• Code wheel (or magnetic actuator or linear scale)
• Optoelectronic receiver or magnetic sensors
• Electronic interface

Encoders use different technologies to detect the motion: 

• Photoelectrical or optical scanning (for rotary or linear products)
• Magnetic field variation (for rotary or linear products)
• Potentiometric (for rotary or linear products)
• Magnetostrictive (for linear products)
• Energy Harvesting (for rotary products)

 

Section of optical encoder	Section of magnetic encoder

Main applications of rotary and linear transducers are: machine-tools, material processing machinery, robots, motor feedback systems, measure and motion control devices.