What is a rotary encoder?

Optical encoder classification and selection

As a class of sensor, rotary encoder used to detect the mechanical movement speed, position, angle, distance, or count. In addition to applications in industrial machinery, many motor control such as servo motors, BLDC servo motor must configure encoder for the motor controller as commutation, speed and position detection. So it is a very wide range of applications. According to the detection principle, the encoder can be divided into optical, magnetic, inductive and capacitive. Method according to its scale and the signal output form, divided into incremental encoder and absolute encoder.

  1. Incremental encoder features:

Incremental encoder shaft rotates, there is a corresponding pulse output, the count starting point arbitrarily set, enabling multi-turn infinite accumulation and measurements. Revolution of the encoder shaft fixed pulse is output, the number of pulses by the encoder determines the number of grating lines. Need to improve the resolution, a phase difference of 90 degrees can be used, A, B two frequency signals or replace resolution encoder.

  1. Absolute encoder features:

Absolute encoders have code to output correspond to position, usually binary or BCD code. By changing the size of the code number can determine positive and negative direction and displacement position, absolute zero code can also be used to blackout position memory. Absolute encoder routine measurement range is 0-360 degrees.

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