Servo Motor: Servo Motor Structure

Servo motors are equipped with a rotation detector (encoder) on the rear shaft side of the motor to detect the position and speed of the rotor, which enables high resolution, high response positioning operation.

An encoder is a sensor used to detect the rotation speed and position of a motor.
The light from the light emitting diode (LED) is read by the photodetector through the position detection pattern on the slit disk. The photodetector integrates several dozen phototransistors. The patterns for absolute position detection are all different depending on the rotation angle of the encoder.
The encoder is equipped with a CPU to analyze patterns for absolute position detection. This present position data is transferred to the servo driver via serial communication.