Fundamentals of Industrial Encoder Sensing Technologies！

Encoders are used to determine the position, velocity and direction of a motor shaft or other mechanical motion. They provide information required for the precise control of a variety of applications, such as positioning a rotary table, pick and place, machine assembly, packaging, robotics and more. Regardless of type, all encoders provide a method of orientation detection that’s used as a reference point for position control. An encoder (for industrial controls) is a special sensor that captures position information and relays that data to other devices. The position information can be determined using one of three technologies: optical, magnetic or capacitive. Optical encoders are the most accurate of the standard styles of encoders. When choosing an optical encoder, it’s important that the encoder has extra protections built in to prevent contamination from dust, vibration and other conditions common to industrial environments.
Magnetic encoders are more rugged than optical encoders and often used in environments in which dirt, steam, vibration and other factors could interfere with optical encoder performance. Magnetic encoders cannot achieve the resolution or accuracy of optical encoders.
Capacitive encoders are relative newcomers as an industrial sensing technology.
These encoders are as rugged as magnetic encoders but also do not achieve the high resolutions of optical encoders.Regardless of the sensing technology an encoder employs, the encoder’s electronics sense movement and translate that motion into industry-standard electrical signals (see “Electrical Outputs” below).
Light duty, medium duty, and heavy duty are terms to differentiate encoders by indicating how much load may be applied to the shaft. A light duty encoder may only handle 10N (2.25 lbf) radial force on the shaft. In contrast, a heavy duty encoder may handle 100N (22.5 lbf) of radial force on the shaft. Environmental ratings also become more robust as the duty increases. Light duty encoders are typically IP40 and IP50 (dust proof); whereas medium duty and heavy duty encoders can be rated as high as IP65 (splash proof).

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