Generally, the signal obtained from the photoelectric detection device of the encoder is low in level and irregular in waveform, and cannot be directly used for control, signal processing and long-distance transmission, so it is necessary to amplify and shape the signal in the encoder. The processed output signal is generally similar to sine wave or rectangular wave. Because the rectangular wave output signal is easy to be digitally processed, it is widely used in control system. The signal output of incremental photoelectric encoder includes open collector output, voltage output, line drive output and push-pull output.