Information reproducing method and information reproducing apparatus of multilayer optical disk
US7123565B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 20, 2003 |
| Grant date | Oct 17, 2006 |
| Priority date | — |
| Expiry date | Jun 4, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
When reproducing a multilayer optical disk using a high-numerical-aperture objective, the period of time required before the disk is reproduced is reduced by discriminating recording layers. A spherical aberration signal is detected as a differential signal between focus position fluctuation signals respectively in a central section and in a peripheral section of a reproduced flux of light. A recording layer is discriminated using a quantity of correction of spherical aberration at a zero-crossing point of a level or a spherical aberration signal associated with the differential signal. After adding the spherical aberration for the correction of the discriminated layer, residual spherical aberration is corrected by feedback control using a residual spherical aberration signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.