Absolute encoder optical disks have lots of lines, each line in turn to 2, 4, 8, 16 ... Arrangement, so that in every position of the encoder, by reading each line in an earlier column, dark, get a set from zero to 2 of 2 n-1 only 2 binary coding (gray code), this is called the n-bit absolute encoder. This encoder is determined by the mechanical position of the encoder, it is not affected by power outages, interference effects.
Absolute encoder up to the mechanical position of the uniqueness of each location, without memory, without points of reference, and do not have to count, when it needs to know the location, location when reading it. So, coding anti-interference, reliability of data greatly improves.
Because of the absolute encoder position is obviously superior incremental encoders, has been increasingly applied in industrial location. Absolute type coding device for its high precision, output bit number more, as still with parallel output, its each a bit output signal must ensure connection is good, for more complex workers condition also to isolation, connection cable core number more, which brings many inconvenience and reduced reliability, so, absolute coding device in more bit number output type, General are selection serial output or total line output.