Focus servo controller with collision avoidance and method therefor
US6985412B1 · kind B1 · utility
2Cited by
8References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 16, 2000 |
| Grant date | Jan 10, 2006 |
| Priority date | — |
| Expiry date | May 16, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0946
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Two sum output signals from two sets of the photodetector elements located symmetrically each other with respect to a light-receiving center of the photodetector of the optical pickup are amplified individually by two amplifiers. A focus error signal is generated in accordance with a difference between respective output levels of the two amplified signals. The gains of the two amplifiers are adjusted in accordance with the focus error signal. A predetermined bias voltage is applied to the focus error signal line in the focus servo control means in accordance with the focus error signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.