Optical incremental encoder！

Incremental value rotary encoders, also known as circular gratings, disc pulse code discs, are known from these names. They are circular gratings. They are rotated by the light and shade of the light flux to produce pulses, which are counted by an external device (Or minus) the number of pulses to measure the angle of rotation. For example, the circle grating engraved with 360 times a week, each groove is generated by a pulse equivalent to 1 degree, the measured pulse total increase of 30, is the positive turn 30 degrees.

There are two (or four) optical eyes that actually read these lines, and each of the two eyelets outputs an A-phase to B-phase to determine from which direction the reticle is coming from. A is ahead of B, Or B ahead of A, like the person's left and right eyes, so as to know the direction of rotation of the encoder, so that the pulse count is increased or decreased to obtain the true rotation angle.

In actual use, the position of phase A and phase B differ by 1/4 pulse period, so that a quarter-cycle difference comes from the positive direction, and 3/4 from the opposite direction, which can be used to judge the direction of rotation. If a pulse cycle of 360 degrees "phase" angle, so that 1/4 is 90 degrees phase difference, and 3/4 is 270 degrees phase difference. In addition, there is a separate scribe line on each revolution of the rotary encoder, which corresponds to zero, also known as Z-phase, for reading the starting point of the week.

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