How does incremental encoder measure the angle of motor?！

How does incremental encoder measure the angle of motor?

Incremental photoelectric encoder is mounted on the motor.The motor speed, position are feedback to the servo drive or PLC, then PLC make controlle.
Incremental photoelectric encoder is characterized by each generating an output pulse signal corresponds to an incremental displacement, but not
By the output pulse distinguish increment in which position. It is capable of generating a pulse signal equivalent displacement increment, and its role
Is to provide a continuous or discrete amount of displacement and the displacement of incremental change (velocity) sensing method, it is relatively certain
The relative position of the incremental basis points, can not directly detect the absolute position information of the shaft. In general, incremental photoelectric series
Encoder output A, B two mutual difference pulse signal (the so-called two quadrature output signals) 90 ° electrical angle, which can be square
It will determine the direction of rotation. As well as a reference phase Z Zero flag (indicating) pulse signals per rotation encoder
Week issued only a flag signal. Flag pulse is usually used to indicate the machine position or accumulation cleared.
Incremental photoelectric encoder consists of a light source, encoder, detection grating, photoelectric detection devices and conversion circuit, as
Figure 1-1. Engraved with the code disk pitch equal radial translucent gap between two adjacent light transmissive slits on behalf of an incremental Week
Period; engraved on the detector grating A, B groups and the light-transmissive code wheel corresponding gap for passing or blocking the light source and the photodetector
Light between devices. Pitch and pitch their code on the disk equal and the two light-transmitting slit shifted 1/4 pitch, so
Photodetector output signal of the electrical angle of 90 ° difference in phase. When tested with the axis of rotation encoder detecting the grating
Do not move, through a chink of light through to the photodetector devices, optoelectronic detection device outputs a code wheel and detection gratings on
Of phase two approximately sinusoidal electrical angle 90 ° of the electrical signals converted signal processing circuit, can
Obtain angular velocity information or the measured shaft. Incremental photoelectric encoder output signal waveform shown in Figure 1-2.
Advantage of incremental optical encoders are: the principle of simple structure, easy to implement; average long mechanical life, can reach tens of thousands
Hour or more; high resolution; strong anti-interference ability, long distance signal transmission, high reliability. The disadvantage is that it can not
Direct readout of absolute position information of the rotation axis.

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