Incremental rotary encoder/or absolute encoder/pull encoder

Absolute encoder is determined by mechanical position of the uniqueness of each position, it does not need memory, don't need to find a reference point, and don't always count, when you need to know, when to go to read it. In this way, the anti-interference characteristics of the encoder, the reliability of data greatly improved.

As a result of absolute encoder in the positioning obviously better than the incremental encoder, has been increasingly used in industrial control positioning. Absolute encoder because of its high precision, output figures, such as still using parallel output, the output signal must ensure that every connection is very good, for more complex conditions and isolation, connecting cable some more, thus bring many inconvenience and reduce the reliability, therefore, absolute encoder in multibit output type, generally selects the serial output or linear output, the German production of absolute encoder is the most commonly used serial output SSI (synchronous serial output).

The working principle of

By A central shaft of light code disc, on which there are circular and dark scribed line, have read photoelectric emission and receiving devices, obtain four groups of sine wave signal is combined into A, B, C, D, each sine wave 90 degree phase difference (as opposed to A cycle of 360 degrees), will reverse, C, D signal superimposed on A, B two phase, can strengthen stability of signal; Every turn output another Z pulse to represent a zero reference.

Because of A, B two phase difference of 90 degrees, but only through A phase in the former or B phase in the former, with forward and inversion of discriminant encoder, through the zero pulse, encoder zero reference can be obtained.

Encoder code disc material with glass, metal, plastic, glass encoder is in the deposition of thin scribed line on the glass, its thermal stability, high precision, metal encoder directly to scribe lines and impassability, non-friable, but because has certain thickness of metal, precision is limited, its thermal stability is an order of magnitude worse than glass, plastic encoder is economical, its cost is low, but the accuracy and thermal stability, life is less.

Resolution - encoder per 360 degrees offer much or dark scribed line called resolution, also known as the analytical index, or say how many line directly, generally at every turn dividing line 5 ~ 10000.