Abstract: There is provided an actuator in which an worm is rotationally driven by an electric motor, and in which an angular velocity of the electric motor is repeatedly fluctuated so that the rotation of the worm is carried out as if the worm is oscillated in the rotational direction thereof, to thereby decrease contact friction of the worm against a worm wheel, resulting in an improvement of an efficiency of force transmission of the worm gear mechanism.

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 means 40 establishes a linking state in which an input shaft 11 of a reduction mechanism 10 and a manual inputting means 30 are linked to each other. When the linking state is detected by a detecting means, an electric power is fed from a battery 80 to a rotation detector by a control section 70, so that the control section 70 can obtain a displacement of the object to be driven, based on a signal output from the rotation detector.

Abstract: There is provided an actuator in which an worm is rotationally driven by an electric motor, and in which an angular velocity of the electric motor is repeatedly fluctuated so that the rotation of the worm is carried out as if the worm is oscillated in the rotational direction thereof, to thereby decrease contact friction of the worm against a worm wheel, resulting in an improvement of an efficiency of force transmission of the worm gear mechanism.

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 means 40 establishes a linking state in which an input shaft 11 of a reduction mechanism 10 and a manual inputting means 30 are linked to each other. When the linking state is detected by a detecting means, an electric power is fed from a battery 80 to a rotation detector by a control section 70, so that the control section 70 can obtain a displacement of the object to be driven, based on a signal output from the rotation detector.