Actuator and position-detecting method therefor

Abstract

In an actuator, an electric power supply to a position-detecting detector for an object to be driven can be carried out in a timely manner during a power failure to thereby suppress an electric power consumption in the position-detecting detector, whereby duration time of a power-failure compensation battery can be prolonged, and a variety of detectors can be selected and utilized without limitation in accordance with a use environment and usefulness. During the power failure, a switching meansestablishes a linking state in which an input shaftof a reduction mechanismand a manual inputting meansare linked to each other. When the linking state is detected by a detecting means, an electric power is fed from a batteryto a rotation detector by a control section, so that the control sectioncan obtain a displacement of the object to be driven, based on a signal output from the rotation detector. In a state in which the input shaftof the reduction mechanismcan be manually rotated, the electric power is fed to the rotation detector. Thus, a useless consumption of the electric power of the batterycan be suppressed, and it is possible to suitably obtain the displacement of the object to be driven without an interruption even if the power failure happens.