Encoders, at present, have been widely used for factory automations, measurements, office automation devices, medical equipment, aviation and universal fields. Various kinds of encoders (FA-CODER® as trade mark) from small to high absolution are available to meet all of the requirements. As a result of this, a maximum of resolution for encoder is one arc sec. High performance encoders supported by these high disk producing techniques are available.
Their resolution is determined with the rotation angle by one pulse.Also according to the resolution, the positioning accuracy of motors is determined.If the resolution is 0.36 degrees, one rotation (360 degrees) of a motor can be divided into 1000 pieces.
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.
Absolute encoders output the absolute value of rotation angles.The encoders are used for position control of servo motors mounted on machine tools or robots.As shown in Figure 2, rotation slits are lined from the center on concentric circles. Slits indicates binary code strings of 2 pulses/rev from the center.Multi-turn absolute encoders memorize the rotation quantity data over one rotation.
Copyright ©Tamagawa seiki Co,.Ltd,.All Rights Reserved.