Optical disc system including current monitoring circuit assembly having controller with improved optics module and laser driver and method for operating same

A magneto-optical disc system of the type having a laser light source, a magnetomotive field generator for subjecting a magneto-optical storage medium to a magnetic field, and a mechanism for focusing light emitted by the light source onto the medium to effect writing of information thereon, said system comprising:

• an optics module for processing light produced by the laser light source;
• a laser driver for energizing the laser light source, said laser driver being positioned in close proximity to said optics module and the laser light source to reduce noise in signals associated with said laser driver;
• 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;
• 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 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.

A magneto-optical disc system of the type having a laser light source, a magnetomotive field generator for subjecting a magneto-optical storage medium to a magnetic field, and a mechanism for focusing light emitted by the light source onto the medium to effect writing of information thereon, said system comprising:

• an optics module for processing light produced by the laser light source;
• a laser driver for energizing the laser light source, said laser driver being positioned in close proximity to said optics module and the laser light source to reduce noise in signals associated with said laser driver;
• 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;
• a controller 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 is written onto the medium when the electric current flowing in said bias coil exceeds a threshold wherein said current monitoring circuit includes a resistor divider, and an analog-to-digital convertor coupled to said divider.

A method for writing information onto a magneto-optical storage medium, said method comprising the steps of:

• providing a magnetomotive field generator for subiecting a region of space to a magnetic field, said generator being responsive to an electric current flowing therethrough;
• disposing a magneto-optical storage medium in said region of space;
• conducting said electric current through said generator;
• monitoring a magnitude of the conducted electric current;
• providing an optics module for controlling and processing an energy beam from a source of radiant energy;
• and
• impinging the energy beam on the storage medium for writing information thereon when the monitored magnitude exceeds a predetermined level, said impinging step being controlled by a source driver for energizing the source of the radiant energy, said source driver being positioned in close proximity to said optics module and the source of radiant energy to reduce noise in signals associated with said laser driver wherein said step of monitoring is performed by sampling during a ramp-up of said current, and further includes predicting a time at which said predetermined level will be exceeded.

An optical disc system for writing information onto a storage medium, the system being of the type having a focusing mechanism and a tracking mechanism, wherein the mechanisms are controlled by a feedback loop, said system comprising:

• an electronic circuit for generating a servo error signal;
• a laser light source;
• an optics module for processing light produced by said laser light source;
• a laser driver for energizing said laser light source, said laser driver being positioned in close proximity to said optics module and said laser light source to reduce noise in signals associated with said laser driver;
• a magnetomotive field generator for subjecting the medium to a magnetic field;
• 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;
• a controller connected to said output of said current monitoring circuit and connected to said laser driver, said controller enabling said laser driver when said output of said current monitoring circuit exceeds a predetermined magnitude so that information is written onto the medium when the magnetic field coil exceeds a predetermined threshold wherein said controller includes a microprocessor and said laser light source is controlled by digital signal processor firmware shown in Appendix B hereto.