What is the working principle of an electric encoder?

Photoelectric encoderIt is a sensor that converts the displacement (analog) of mechanical rotation into a digital electrical signal. Optical encoders can be divided into two types based on their structure: encoder disc and pulse disc. The encoder is composed of a light source, a encoder connected to the rotating shaft, a narrow slit, and a photosensitive element. When the light beam from the light source (often using light-emitting diodes) is projected onto the code wheel through a condenser lens, the code wheel is rotated, and the light beam passes through the code wheel to form an anglecodeThen, it is injected into a group of photosensitive elements (mostly silicon photovoltaic cells or phototransistors) through a narrow slit. The arrangement of photosensitive elements corresponds one-to-one with the code track, ensuring that each code track has one photosensitive element responsible for receiving the transmitted light signal. When the optical encoder rotates to different positions, the signal output by the photosensitive element group reflects the angular displacement of the encoder.

Pulse disc encoderThere are two equal angular gaps on the disk, with outer ring A as the incremental code track and inner ring B as the directional code track. The distance between adjacent gaps on the inner and outer rings is offset by half the width of the gap. In addition, there is also a gap at a certain radial position outside the inner and outer rings, indicating the zero position of the code disk. Every time the code disk rotates, the photosensitive element corresponding to the zero position generates a pulse, which is called the "zero position pulse". Install light sources andPhotosensitive elementThere are two slits on the light barrier board, which are four times the distance between two adjacent slits on the code wheel, and two sets of corresponding photosensitive elements (called cos and sin elements) are set up to correspond to two signals (the quarter spacing difference ensures that the phase difference between the two signals is 9o, making it easy to distinguish directions). When the code wheel rotates with the tested work axis, there is a change in the brightness of the light every time it passes through a gap, and an electrical signal change is generated through the photosensitive element. Therefore, the number of gaps on each code track will be equal to the number of pulses output by the photosensitive element per rotation. Using a counter to recordNumber of pulsesIt can reflect the angle of rotation of the code wheel.