Photoelectric rotary encoder

which is also called photoelectric angel-position sensor

is a kind of digital angle-measuring device combining optics

mechanics and electronics. Owing to its simple structure

high resolution

and high accuracy

the photoelectric rotary encoders have been used generally in the systems of fine angel-position measurement

digital control and digital display. The domestic and foreign development in photoelectric rotary encoders are mainly introduced

and its working principle

developing history are described briefly as well. Some key technologies of photoelectric encoders and its developing trends are summarized at last.