Calibration of a focus sum threshold in a focus servo system
US6813226B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 10, 2001 |
| Grant date | Nov 2, 2004 |
| Priority date | — |
| Expiry date | Jan 16, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0948
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A determination of a focus sum threshold in a tracking and focus servo system of an optical disk drive is presented. The focus sum threshold can be determined by moving an optical pick-up unit sinusoidally through a focus position, for example by moving the optical pick-up unit between its closest position to an optical media and its farthest position from the optical media. While moving the optical pick-up unit, a sum signal is monitored. In some embodiments, the sum signal is the sum of signals from a plurality of detectors in the optical pick-up unit. The focus sum threshold is set to a fraction of a peak value of the sum signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.