PURPOSE: To determine an absolute position of a mechanism by using only a small motion of an actuator at the time of start, by using a position encoder being inexpensive and consisting of a simple constitution, combining increment and discrete encoders.
CONSTITUTION: An absolute position of a mechanism is determined by using a combination of signals from an increment encoder 32 and a discrete encoder 34 which is incorporated in a module 10. The increment encoder 32 generates a pulse for showing an increment rotation of a motor driving shaft 24 to an actuator, and an index pulse at every rotation of the motor driving shaft 24. The discrete encoder 34 is contained in a small-sized housing attached easily to the end part of the increment encoder 32, constituted of a pair of gears for executing a precession, which are driven by the motor shaft 24, and each gear generates a mark pulse at every one rotation. In this way, an angular displacement of the gear for executing the precession to the index pulse is measured, and extending over a motion range of a servo-control member, a special rotational position in a range of a rotation of the motor is determined.
KIISU UIRIAMUSON
RANDEII ANDORIYUU
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