Abstract
Accurate servo track writer (STW) is indispensable for hard disk drives (HDDs) with high track density. We have developed a prototype of the Hybrid-type STW, which consists of two writing stages. In the first stage, master patterns are written on one surface of the master disk prior to drive assembly. In the second stage, the master disk is assembled with several raw disks in a HDD, and the servo patterns are written on the disks on the basis of the master patterns. This paper describes the design of servo system for the Hybrid-type STW and experimental results using a 2.5 type HDD. One of our results is that in comparison with the conventional STW, the Hybrid-type STW can suppress low frequency vibrations of ball bearings and reduce the maximum value of repeatable runout (RRO).
