Patent ID: 7348691

Claim:
Apparatus for levitating a magnetic element, comprising: at least three magnets defining a common plane and arranged to generate a static magnetic field providing a position-dependent potential energy of interaction with a magnetic element located above the plane, the static magnetic field defining an elongated equilibrium location wherein the potential energy decreases for displacements of the magnetic element away from the equilibrium location along an unstable axis substantially orthogonal to the longitudinal axis of the elongated equilibrium location and increases for displacements of the magnetic element away from the equilibrium location in any direction along the longitudinal axis; a position sensor generating a feedback signal indicative of the location of the magnetic element on the unstable axis; an electromagnet configured to generate a control magnetic field upon the passage of an electrical current through the electromagnet, the control magnetic field having a gradient with respect to displacements along the unstable axis at the equilibrium location; and a controller connected to receive the feedback signal and to control the electrical current in the electromagnet to prevent the magnetic element from leaving a vicinity of the equilibrium location.