Feasibility study of a high capacity 2-inch-data-disk-system

Basic studies were performed on the head/medium interface and transducing system of projected high-capacity 2" data disk systems with a formatted storage capacity of 1.44 MB (equal to that of 2HD 3.5" mini-floppy disk drives), and with roughly double the unformatted capacity of existing 2" data disk systems, with the following conclusions: (1) Upon comparing fixed-pad, moving-pad and negative-pressure-plate interfaces, it was found that a negative-pressure-plate assembly is best suited for use over an expanded disk area. (2) Through use of the negative-pressure-plate method, it was possible to increase the number of tracks to 90 using a single side of the disk, with the same track pitch (100 pm) as in current systems. (3) By optimizing the transducing system (gap depth and number of coil windings) in accordance with a minimum recording wavelength of 0.69 pm, it was found that pre-erase type ferrite heads could provide adequate performance. (4) In using an enlarged portion of the disk, it becomes necessary to switch between different equalization characteristics at a disk radial position nearly midway between the innermost and outermost tracks. This switching can be accomplished simply by changing the parameters of the equalization circuit used in existing systems. (5) Drawing on the above results, we developed a prototype high-capacity 2" data disk system which preserves compatibility with systems currently in use. The prototype was found to provide performance (error rates, environmental conditions, durability) comparable to that of current systems.