Lens, optical head, optical information writing/reading apparatus and optical information recording medium writing/reading method
US6995909B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 5, 2000 |
| Grant date | Feb 7, 2006 |
| Priority date | — |
| Expiry date | Feb 26, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/13727
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Conventional lenses for DVD/CD compatible writing/reading are liable to CD jitter deterioration due to phase shifts in a central area.Setting a corresponding base material thickness of an intermediate area of the circumference A2 to greater than 1.2 mm which is the base material thickness of the CD, that is, converging luminous flux that has passed through the intermediate area of the circumference A2 onto a farther place than the information recording surface of the base material thickness of the CD makes it possible to reduce jitter deterioration due to phase shifts. Further, it makes possible to provide a system with higher precision and higher reliability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.