Assembly having flux-directing return yoke for magneto-optical drive

A magnetic bias field generating apparatus for directing a magnetic field through a region of space, said apparatus comprising:

• a winding for carrying an electrical current;
• a return yoke having a body portion and a tip having a predetermined thickness, said winding being wound about said body portion, and said tip having an extension that extends beyond said body portion to overlap a surface of said winding;
• a first plate disposed on one side of said winding, said first plate having a plurality of fingers extending about said winding;
• a second plate disposed on another side of said winding, said vertical fingers formed without adding vertical height beyond said first and second plates;
• a first pole piece in magnetic flux communication with said first plate;
• and
• a second pole piece in magnetic flux communication with said second plate, a first end portion of said second pole piece opposing a first end portion of said first pole piece across a region of space to be subjected to a magnetic field so that when said winding is connected to a source of power, said tip receives lines of magnetic flux that are channeled through said body portion and directed across the end portions of the pole pieces while said fingers radiate thermal energy thereby produced.

In combination with a magneto-optical disc drive, a bias coil field generator for producing a magnetic field in a data storage area of an optical disc disposed in the disc drive, said bias coil field generator comprising:

• a first plate, a second plate, and a bias coil winding caged therebetween, at least one of said first plate and said second plate having a heat-radiating finger directed generally toward the other of said first plate and said second plate while contained therebetween to maintain a minimum height defined by said first plate and said second plate;
• an elongated return yoke disposed in said winding, said return yoke having a body portion, a tip that projects beyond said winding, and two thin end extensions extending from said tip, said extensions having a predetermined thickness and overlapping a portion of said winding;
• and
• a first pole piece and a second pole piece, said pole pieces and said return yoke being disclosed in a magnetic circuit, respective end is of said pole pieces forming an opening therebetween so that said magnetic circuit traverses said opening to thereby allow an information storage area of an optical disc residing in said opening to be exposed to a magnetic field when said winding is connected to a source of power, said tip thereby receiving lines of magnetic flux that are channeled through said body portion and directed across said ends of the pole pieces while said heat radiating finger radiates resulting thermal energy.