Dynamic Measurement of a Head-Disk Spacing Variation for High Density FDD

A head-disk interface (HDI) analyzer for high-density floppy disk drives (FDDs) was improved. This equipment consists of a high-shutter-speed camera and a highly sensitive image processor. It makes possible the evaluation of dynamic spacing fluctuation by analysis of interference fringe patterns on both sides of a floppy disk (FD). With this equipment, the dynamic motions of an up-head slider and FD were observed. Moreover, it was shown that the surface roughness of the FD affects the head contact and that a smoother disk surface causes larger fluctuations in spacing. This result indicates that a surface of appropriate roughness is required of FDs so as to maintain reliability in high-density FDDs.