Version 0.6, November 3, 1999, Copyright, Hugh Jack 1993-1999
· An incremental encoder will produce a set of output pulses, and a direction as it is rotated.
· The encoder contains an optical disk with fine windows etched into it. As the encoder shaft is rotated, the etched disk inside rotates. As it rotates various optical sensors are turned on and off.
absolute - the same shaft position will always give the same position reading
relative/incremental - these just indicate movement, and they require that other circuits or programs be used to track position
· How the openings are etched onto the disk determine whether it is absolute or relative.
· In actual encoders there can be thousands of divisions per rotation.
· With an absolute encoder the output is a binary or gray code number.
· A quadrature pulse counter uses two pulses out of phase and deduces distance and direction.
