Zero-power control type vibration eliminating apparatus

Claim 1

A vibration eliminating apparatus comprising: a table upon which equipment to be isolated for vibration is supported; magnetic members fixed to said table; acceleration sensors fixed to said table; control magnets for suspending said magnetic members with magnetic forces; displacement sensors for measuring gaps between said control magnets and said magnetic members; means for exciting said control magnets; compensating means for controlling exciting currents flowing through said control magnets by applying an output from said displacement sensors to said exciting means, said compensating means including a first variable gain circuit through which the output of each of said displacement sensors is applied, each of said control magnets comprising a permanent magnet for generating a bias magnetic flux and an electromagnet for generating a control magnetic flux to form a magnetic circuit; means for feeding back integrated values of the exciting currents of said electromagnets to said exciting means; and a second variable gain circuit through which the output of each of said acceleration sensors is supplied to said exciting means, gains of said first and second variable gain circuits being changeable in an interlocking relationship with each other.