ELEC 255 Lecture Notes - Lecture 1: Rotary Encoder, Linear Encoder, Photodetector
Document Summary
An encoder is a sensor of mechanical motion that generates digital signals in response to motion. As an electro-mechanical device, an encoder is able to provide motion control system users with information concerning position, velocity and direction. There are two different types of encoders: linear - a linear encoder responds to motion along a path, rotary - a rotary encoder responds to rotational motion. Incremental rotary encoders utilize a transparent disk which contains opaque sections that are equally spaced to determine movement. A light emitting diode is used to pass through the glass disk and is detected by a photo detector. This causes the encoder to generate a train of equally spaced pulses as it rotates. The output of incremental rotary encoders is measured in pulses per revolution which is used to keep track of position or determine speed. Incremental rotary encoders are not as accurate as absolute rotary encoders due to the possibility of interference or a misread.
