Abstract
The accuracy of reference position signals in hard disk drives is discussed. Servo patterns, which are used for reference position signals, are written by a manufacturing-equipment called servo track writer (STW). Recently, various methods for STWs are investigated to achieve narrower track widths and more accurate track shapes. One method is based on semi-closed head-positioning control, and another is on full-closed one. In this paper, positioning disturbances caused by disk flutter are modeled in order to analyze writing accuracies with bank-write method. In bank write condition, vector locus diagram is useful to evaluate servo pattern accuracies, especially, by the STWs based on full-closed head-positioning control.
