Runout Characteristics of Flexible Disks by a New Head-Pad Combination Model

Runout (dynamic deflection) of both a Co-Cr/permalloy flexible disk A, and a commercialized particulate flexible disk B, both with diameter 3.5", was studied using a disk drive with two pairs of pads arranged in series relative to the disk rotating direction, and with a photometric positioning sensor in place of a single-pole miniature head. In the drive, the radial position of the sensor over the disk was varied between 30 and 37 mm at disk revolution rates ranging from 400 to 1200 rpm, to evaluate the effect of the pad configuration on the runout characteristics. The runout of disk A was suppressed to between 15 and 30 ¿m, while that of disk B was almost unchanged at more than 60 ¿m. Stable read/write characteristics of disk A were observed in the high-density region near 70 kfci under a head pressure of 1 gf and runout of about 20 ¿m.