Masakazu Nishikawa

Magnetic duplication for precise servo writing on magnetic disks

A servo pattern of a 20 Gbit/in/sup 2/ level was directly duplicated on hard disks by using a magnetic duplication method, and the accuracy of the signal and the following performance on the duplicated servo pattern were evaluated. The phase servo pattern was composed of straight lines and was lithographically formed on a mastering disk. The period accuracy of the readback signal was very high. The repeatable position error for adjacent tracks in a prototype drive was measured, and the difference between two adjacent RPE trajectories was sufficiently small. The magnetic duplication method showed the possibility of precise servo-track writing for high-density hard disk drives.

Readback properties of novel magnetic contact duplication of high recording density floppy disk

We observed the readback signal from a floppy disk (FD) media prepared by a novel magnetic contact duplicated method. The signal amplitude, PW50, and CNR were nearly same as that using the traditional method. It was confirmed that this technique has a high potential to write servo signals in high Hc media.

Possibility of 3 Gbits/in/sup 2/ floppy disk

We tried to realize Gbits/in/sup 2/ class Floppy Disk with a magnetic layer prepared by sputtering (SP-FD). The heat-durable undercoat and the underlayers made magnetic layer have Gbits/in/sup 2/ properties, with higher S/N and narrower PW50 In comparison with those of 3.1 Gbits/in/sup 2/ HD. Heat durable substrate, fine protrusions and aerodynamics consideration allowed to achieve stable and nonaggressive contacts and good durability after running for more than 250 hours at three different environment conditions. We can conclude that the SP-FD has the potential of 3 Gbits/in/sup 2/ FD.