Encoder is a precision measuring device that combines mechanical and electronic closely. It converts a mechanical geometric displacement into an electronic signal (electronic pulse or data string) through photoelectric or electromagnetic principles. This kind of electronic signal usually needs to be connected to the control system, and the control system can obtain the measured data after calculation for the next step.

According to the working principle, encoders can be divided into two types: incremental encoder and absolute encoder. The incremental encoder converts the displacement into a periodic electric signal, and then converts this electric signal into a counting pulse, and the number of pulses is used to indicate the magnitude of the displacement. Each position of the absolute encoder corresponds to a certain digital code, so its indication is only related to the start and end positions of the measurement without being in relationship during measurement.

According to the working principle of detection, it can be divided into photoelectric encoder and electromagnetic encoder.

Photoelectric encoder converts the mechanical geometric displacement of the output shaft into pulse or digital by photoelectric conversion.

Electromagnetic encoder converts the changing magnetic field signal into the change of the resistance value through the magnetoresistance effect. Under the action of the applied electric potential, the changed resistance value is converted into the change of the voltage, which is processed by the subsequent signal processing circuit to simulate the voltage signal Converted into a digital signal that can be recognized by the computer to realize the encoding function of the magnetic rotary encoder.

Although the photoelectric encoder occupies a large share of the current encoders on the market, the magnetic encoder has a high speed, good ease of use, high shock resistance, easy adjustment, installation and maintenance, and its low cost, becomes a better choice for ordinary precision applications.