The incremental rotary encoder converts the timing and phase relationship of its angle code disk through two internal photosensitive receivers, After connecting the digital circuit, especially the single chip microcomputer, the incremental rotary encoder has the advantages of cheaper and simpler than the absolute rotary encoder in angle measurement and angular velocity measurement.

Photoelectric encoder is a sensor that converts the mechanical geometric displacement on the output shaft into pulse or digital quantity through photoelectric conversion. This is the most widely used sensor at present. The photoelectric encoder is composed of grating disk and photoelectric detection device. The grating disk is divided into several rectangular holes on a circular plate with a certain diameter. Since the photoelectric code disk is coaxial with the motor, when the motor rotates, the grating disk rotates at the same speed as the motor, and several pulse signals are detected and output by the detection device composed of electronic components such as light-emitting diodes; The current motor speed can be reflected by calculating the number of output pulses of the photoelectric encoder per second. In addition, in order to judge the rotation direction, the code wheel can also provide a phase difference of 90. Two pulse signals.