Rotary encoder
A rotary encoder is a device that can keep track of how much something has turned. This is called its angular position. That information is useful to know how far a motor has turned, for example.
Rotary encoders are often used in manufacturing and robotics. This is because they need things to be measured and controlled very accurately.
Basic types
Absolute
An absolute encoder always keeps track of what value its on, even if it isn't powered.
Incremental
An incremental encoder only keeps track of changes. It gives off signals if it is turned one way or another.
Rotary Encoder Media
A Gray code absolute rotary encoder with 13 tracks. At the top, the housing, interrupter disk, and light source can be seen; at the bottom the sensing element and support components.
Hall effect quadrature encoder, sensing gear teeth on the driveshaft of a robot vehicle.
Rotary encoder for angle-measuring devices marked in 3-bit binary. The inner ring corresponds to Contact 1 in the table. Black sectors are "on". Zero degrees is on the right-hand side, with angle increasing counterclockwise.
Rotary encoder for angle-measuring devices marked in 3-bit binary-reflected Gray code (BRGC). The inner ring corresponds to Contact 1 in the table. Black sectors are "on". Zero degrees is on the right-hand side, with angle increasing counter-clockwise.
Encoder ROD 420. HEIDENHAIN.
Two square waves in quadrature. The direction of rotation is indicated by the sign of the A-B phase angle which, in this case, is negative because A trails B.
Conceptual drawing of a rotary incremental encoder sensor mechanism, with the corresponding logic states of the A and B signals
Rotary (Angle) Pulse Encoder Operation & Teardown
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