Encoder disk/wheel refers to a digital encoder that measures angular displacement. It is a kind of grating. There are one or more light-transmitting gratings on the code wheel. There is a photosensitive element behind each grating, and the grating code is rotated as the motor rotates. The disk continuously passes through the continuous light-emitting photocell, and the light passing through the grating is received by the photosensitive element and generates a pulsed electrical signal. If the code number of the photoelectric encoder is 1 and the number of pulses measured in time t is N, then the rotational speed n=60N/(t*1). The greater the number of codes on the code disc, the higher the measurement accuracy.