The working principle of the incremental encoder ！

The optical encoder has a shaft, on which a ring through dark engraved lines, optoelectronic transmitting and receiving device to read, get a sine wave signals into four groups a, B, C, D, each sine wave phase difference of 90 degrees (with respect to a cycle of 360 degrees), the C, D inverted signal, superimposed on a, B on the two-phase, can enhance stabilization signal; other each turn a Z-phase pulse output to represent the zero reference position. Since the A, B two-phase difference of 90 degrees, the first phase A or B by comparing the first phase, in order to determine the encoder forward and reverse, the zero pulse can be obtained encoder zero reference position. Encoder code disc material glass, metal, plastic, glass code discs are deposited thin engraved lines on the glass, good thermal stability, high accuracy, metal code disc directly
Nowhere to pass and score line, not brittle, but because the metal has a certain thickness, there are restrictions precision, thermal stability is necessary an order of magnitude worse than glass, plastic code disc is a economical, low cost, but the accuracy , thermal stability, life are to be worse. Resolution - 360 degrees per encoder rotation through or how much dark groove called the resolution, also known as analytic indexing, or direct say how much wire, usually 5 degrees per rpm to 10,000 lines. Signal output: sine wave signal output is (current or voltage), square wave (TTL, HTL), open collector (PNP, NPN), push-pull many forms, as long TTL differential drive (symmetric A, A-; B, B-; Z, Z -), HTL, also known as push-pull, push-pull output encoder signal receiving device interface should correspond with the encoder. Signal connection - module encoder pulse signal typically connected counter, PLC, computer, PLC and computer are connected to high-speed and low-speed module module of the points, with a high switching frequency is low. Such as single-phase connection, for uni-directional counting, one-way speed.
A.B two coupled for forward and reverse counting, and speed to determine the pros and cons.
A, B, Z-phase coupling for position measurement with a reference bit correction.
A, A-, B, B-, Z, Z- connection, since the connection with symmetrical negative signals, the contribution of the current cable for the electromagnetic field is 0, the minimum attenuation, the optimum interference can transmit greater distances. For TTL signal output with symmetric negative encoder signal transmission distance up to 150 meters. For HTL with symmetrical negative signal output from the encoder, the signal transmission distance up to 300 meters.

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