Optical disc drive apparatus
US7639588B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 31, 2007 |
| Grant date | Dec 29, 2009 |
| Priority date | — |
| Expiry date | Jun 18, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The amount of reflected light from an adjacent layer in a multilayer optical disc is reduced by means of a combination of half-wave plates having different optical axes and a flat mirror. The polarization direction of the reflected light from a target layer is changed without changing the polarization direction of reflected light from the adjacent layer so as to detect a signal from the target layer alone. Because no stray light is introduced into the tracking error signal or focus signal, the laser light irradiated position can be controlled with high accuracy. This makes it possible to accurately determine the laser irradiated position during reading and writing, thereby enhancing signal quality. Because no reflected light from the adjacent layer is introduced into the data signal, a data signal with reduced error can be obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.