8.22 OPTICAL MOTOR SHAFT ENCODER

8.22.1 Incremental Rotation Encoder

An incremental rotatory encoder is a system, which records increments or decrements of one step in the angle when a shaft rotates to the next step angle. Figure 8.50 shows a circular disc with the two tracks and a hole. The disc has a hole for marking the origin(0° angle). The disc has two tracks, a and c for noting the movements stepwise. Figure 8.51 shows three interface circuits. There are three LED-phototransistor pairs, one pair is for the hole and two are for the a and c tracks. The disc attaches to the shaft.

Figure 8.50. Circular Disc with a Hole with the Disc Attached to a Shaft in a Six-Bit Incremental Rotation Encoder (incremental angle encoder)