Apparatus for discriminating optical recording media of different thicknesses from each other and reproducing information therefrom
US6201777A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 17, 1999 |
| Grant date | Mar 13, 2001 |
| Priority date | — |
| Expiry date | Feb 17, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0006
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus for discriminating optical disks has an optical pickup provided with an objective lens having an effective numerical aperture of 0.55 to 0.65, which can compatibly reproduce information from a CD and an SD. The apparatus discriminates presence/absence of waveforms of two focus error signals detected when the effective numerical aperture of the objective lens is set at 0.55 to 0.65 and 0.20 to 0.45 respectively in a process of performing focus servo control, thereby discriminating various types of optical disks from each other. Thus, optical disks having different substrate thicknesses, different track pitches, different minimum pit lengths and different reflectivity can be quickly and simply discriminated from each other.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.