Method and system for accurate self-servowriting with normalization in a disk drive
US6469859B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 24, 1998 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Nov 24, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B21/10
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An accurate and time-efficient method and system for self-servowriting wherein at least one reference value used to position the transducer is updated for some, but not all, of the tracks to be written. The reference value(s) is dependent upon a predefined indicium of transducer position, such as the amplitude of the readback signal obtained from a written track when the transducer is positioned on the track. In a first embodiment, updating of the reference value(s) is performed at every Nth track written, where N is a fixed number or range of numbers determined by an expected track-to-track variation of the indicium. The servowriting system may be designed to dynamically increase or decrease N during servowriting in response to actual variations in the indicium. According to a second embodiment, updating is only performed when needed, e.g. when the variation of the measured indicium between two written tracks (not necessarily adjacent tracks) exceeds a predefined threshold value. For systems employing dual-element heads, servowriting accuracy is enhanced by performing a read head adjustment prior to updating of the reference values.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.