Optical absolute angle encoder - has multiple track code, e.g. Gray code, adjacent to analogue code, and photocell array sensing both scales

摘要

The angle encoder has a multiple track code, e.g. a Gray code, immediately adjacent to an analogue code of scale strips inclined w.r.t. the radius, and a photocell array arranged radially to sense both scales. A square wave generator is operated at a frequency fs/2a, where fs is the shift frequency of the CCD array and a the number of pixels per binary track. The CCD video signal is serially fed into a further shift register and the binary signal read out at the parallel outputs after n steps, where n is the number of binary bits. ADVANTAGE - Reduced number of binary tracks for required resolution. Simplified coding and adjustment.