Magnetically coupled apparatus for inverting a bias field for magneto-optic recording and erasing

摘要

A bias-field apparatus for a magneto-optical system having a magneto-optical recording element which includes a conductive substrate and which moves through a magnetic field created by the bias-field device so that information is selectively recorded on or erased from the recording element, the device comprises a support member; a magnet mounted for rotation in the support member such that, when the recording element rotates, the conductive substrate creates a magnetic coupling with the magnet for causing the magnet to rotate; and (c) a ferromagnetic element enclosing a portion of said magnet and having a plurality of spatially separated pole teeth, each of said pole teeth having an operably connected coil disposed thereon that releases said magnet for rotation caused by the conductive substrate when the coil is energized, and prevents rotation when said coil is de-energized for permitting said magnet to be selectively rotated.