Optical disc readout apparatus for different types of optical discs
US5856965A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 7, 1996 |
| Grant date | Jan 5, 1999 |
| Priority date | — |
| Expiry date | May 7, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2020/10879
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical disc readout apparatus having an optical system which guides a laser beam onto a signal recording surface of a loaded disc through an objective lens and guides a reflected laser beam onto a photo detector. An effective numerical aperture of the objective lens is adjusted according to the thickness between a substrate surface of the loaded disc and the signal recording surface, and the laser spot with a diameter suitable to a recording density of the loaded disc is focused on the signal recording surface. Therefore, the data recorded in a plurality of optical discs with different thickness or recording densities can be read out.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.