Enhanced method and system of unloading magnetic heads
US5969899A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Apr 2, 1997 |
| Grant date | Oct 19, 1999 |
| Priority date | — |
| Expiry date | Apr 2, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/6005
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An enhanced method and system for unloading magnetic heads are disclosed. The system limits the maximum and minimum speed of the actuator while unloading the heads during a power failure. A BEMF control circuit monitors the velocity of the actuator using the BEMF of the actuator as a gauge of the velocity. The BEMF control circuit uses a sense resistor to remove the inherent resistive component of the actuator from its BEMF measurement. If the velocity of the actuator increases above a safe level the BEMF control circuit decreases actuator current to prevent further acceleration. If the velocity of the actuator decreases below a safe level the BEMF control circuit increases the actuator current to accelerate the actuator to a safe level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.