Up to now, highly dense magnets prepared from Nd-Fe-B melt-spun powder by powder compacting press or injection molding have not been used in solid magnet rotors composed of a ring-shaped bonded magnet, a magnetic core, and a rotating shaft. We developed new techniques for using a highly dense Nd-Fe-B bonded magnet in a solid rotor by substituting an epoxy-resin-bonded dust core for the laminated steel core used previously for a solid rotor. The techniques enabled us to join an Nd-Fe-B bonded magnet, an iron-dust core, and a rotating shaft without bonding layers. Using these techniques, we made solid rotors containing a highly dense ring-shaped Nd-Fe-B epoxy-resin-bonded magnet whose output power was less than 20 W. This paper reports the newly developed technique, the mechanism of adhesion, and the magnetic properties of the solid magnet rotor prepared by using our techniques.

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The recording capacity of GIGAMO media was enlarged from 1.3 GB to 2.3 GB for 3.5 inch Magneto-Optical (MO) disks while maintaining downward compatibility. For the new GIGAMO technology, a land and groove recording method was applied in addition to magnetically induced super resolution (MSR) media. Furthermore, a novel address format suitable for the land and groove recording method was adopted. The specifications of the new GIGAMO media were examined to satisfy requirements for practical use with respect to margins. Durability of more than 10⁶ rewritings and an enough lifetime were confirmed.

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