Patent ID: 6236625
Filing Date: 2001-05-22
Classification: G11B

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, the 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 disposed in the magnetomotive field generator;a bias coil driver switchably connected to said bias coil for supplying an electric current thereto;a current monitoring circuit connected to said bias coil driver having an output responsive to said electric current; anda 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.