Tamagawa Seiki Incremental Rotary Encoder

Incremental encoders generate pulses in a frequency proportional to the rotational speed. The encoders can be used for speed control, position control, or as a rotation indicator or a pulse generator of servo motors mounted in machine tools, robots, or measuring equipment. Optical incremental encoders are composed of rotor plate, fixed slit, light emitting diodes, photo transistors, etc. as shown in Figure 1.The fixed slit is designed to have 90 degree phase difference to the slit on the rotor plate. Output signals are two signals with 90 degrees difference; A-phase signal and B-phase signal, and the rotational direction can be detected with them. There are encoders which output the additional Z-phase signal as the origin signal. When controlling positions with an incremental encoder, the Z signal which shows the origin is used.