Heat-assisted magnetic recording disk drive (HAMR) with thermal sensor and laser power prediction
US8842507B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 22, 2013 |
| Grant date | Sep 23, 2014 |
| Priority date | — |
| Expiry date | Oct 22, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2005/0021
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A thermally-assisted magnetic recording (HAMR) disk drive uses a thermal sensor to accurately monitor laser power during writing. The disk drive controller, or a separate processor, computes a prediction of the laser power from a history of laser power settings. This predicted value is compared with the measured value from the thermal sensor. If the difference is too large or too small, indicating that the laser power is too high or too low, an error signal is sent to the disk drive controller. The disk drive controller may adjust the laser power setting and initiate a re-write of the data. The predicted laser power is calculated from a convolution of a sequence of current and prior laser power settings with a sequence of coefficients. A calibration process generates the sequence of coefficients when the disk drive is idle or just after it is powered on.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.