Patent ID: 6317391
Filing Date: 2001-11-13
Classification: G11B,H02K

Abstract:
An optical disc system of the type having a focusing mechanism and a tracking mechanism, the mechanisms being controlled by a feedback loop, the system further having a laser light source, and a magnetomotive field generator for subjecting a magneto-optical storage medium to a magnetic field, wherein the focusing mechanism focuses light emitted by the light source onto the medium to effect writing of information thereon, said system comprising:an electronic circuit for generating a servo error signal, said error signal being communicated in the feedback loop for effecting corrections of said focusing mechanism and said tracking mechanism;a laser driver for energizing the laser light source;a bias coil assembly disposed in conjunction with the magnetomotive field generator, said bias coil assembly including a wire coil wrapped around a center bar contained by a bias coil housing, said bias coil assembly being positionable above the storage medium so that the entire medium may be within the magnetic field thereby allowing writing of information to all portions of the medium;a bias coil driver switchably connected to said bias coil assembly for supplying an electric current thereto;a current monitoring circuit connected to said bias coil driver having an output responsive to said electric current;a controller including a microprocessor connected to said output of said current monitoring circuit and connected to said laser driver said controller thereby enabling said laser driver when said output of said current monitoring circuit exceeds a predetermined magnitude so that information processed through said focusing mechanism is written onto the medium when the electric current flowing in said bias coil exceeds a threshold wherein said microprocessor samples said output of said current monitoring circuit during an interval when said output of said current monitoring circuit is less than said predetermined magnitude, and predicts a time when said output of said current monitoring circuit exceeds a predetermined magnitude.