Method and apparatus for ramp loading in a hard disk drive using pulse width modulation
US6631045B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 29, 1999 |
| Grant date | Oct 7, 2003 |
| Priority date | — |
| Expiry date | Oct 29, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B21/22
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus to control application of a drive current to a voice coil in a hard disk drive system modulates a periodic waveform between either a reference level and a signal associated with a stored back electromotive force (BEMF) in the voice coil. The drive current is applied to the voice coil during periods of time when the periodic waveform is modulated by the signal associated with the stored BEMF. The amplitude and duration of the drive current correspondingly decreases as the BEMF in the voice coil decreases. Thus, the voice coil is controlled based on its BEMF and is provided with decreasing power to move a head mechanism to or from a ramp assembly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.