System for obtaining optimum focusing position in optical disc system
US5142520A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 1989 |
| Grant date | Aug 25, 1992 |
| Priority date | — |
| Expiry date | Jun 28, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0908
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system for obtaining an optimum focusing position in an optical disc system. An optical beam is impinged onto a track of an optical disc, and a reflection signal having information regarding an intensity of an optical beam reflected by an optical disc is obtained. A predetermined frequency component, the frequency component being generated by a modulation caused by an existence of a pit on a track of the optical disc in a reflecting signal, is extracted from the reflection signal. Then a focus position in which a maximum intensity of the extracted frequency component is obtained is searched by changing the focus position of the optical beam. Further, the above system is incorporated in a focus servo control system for maintaining an optimum focusing position in an optical disc system during reading and writing operations, to determine an optimum offset value which is to be adjusted to compensate an error arisen from a construction of the focus servo control system, during an offset adjusting operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.