Perpendicular magnetic recording floppy disk drive

A perpendicular magnetic recording floppy disk drive, small in size but large in capacity, has been experimentally developed, employing a ring-shaped head and a Co-Cr sputtered disk. A three megabytes per surface capacity, at a 50 kFRPI linear density and a 144 TPI track density, has been accommodated on a 3.5"-diameter disk. The head has a 0.4 μm recording/ reproducing gap and a 2.0 μm tunnel erasing gap. The disk consists of 0.5μm thick Co-Cr films sputtered on both sides of polyester substrate. The design concept, specifications, and some performance data for the disk are described.