Antivibration actuator

Abstract

An antivibration actuator which alleviates vibration applied to a machinery or a building accommodating the machinery to protect the machinery and building from earthquake or other external perturbing vibration. A signal from a sensor disposed on a vibrated body can be inputted thereto through a control device and a waveform opposite to that of a vibration transmitted to the vibrated body is generated in order to reduce the vibration transmitted to the vibrated body. In particular, it is so constructed that it includes a coil member including a holding plate and flat coils disposed on a front and a rear surface of the holding plate and secured to a fixed member disposed independently from the vibrated body; a movable member including a pair yokes and a plurality of permanent magnets disposed on said yokes opposite to the flat coils through magnetic air gaps and magnetized in a thickness direction so that opposite poles appear alternately in a longitudinal direction. The movable member is movable in the longitudinal direction. Further, the movable member is joined with the vibrated body, and the flat coils generate a magnetic field in a direction opposite to that of the magnetic field generated by the permanent magnets by making a control current, based on the signal coming from the sensor, flow therethrough. In this way, a compact antivibration actuator having a simple construction, good response characteristics and high reliability can be obtained.