Optical pickup apparatus for accurate detection of a tracking error signal
US6128259A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 12, 1998 |
| Grant date | Oct 3, 2000 |
| Priority date | — |
| Expiry date | Mar 12, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0908
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In order to accurately detect a tracking error signal, the position of a sub-beam Bs1 with a lower shading rate is located at a position ahead of the position of a main beam Bm in the recording direction of an optical disk, and the position of a sub-beam Bs2 with a higher shading rate is located at a position behind the position of the main beam Bm in the recording direction of the optical disk. Therefore, the unequal amount of optical information created by the different shading rates is counterbalanced by the fact that the portions of the optical disk where the sub-beams Bs1 and Bs2 are directed have different reflective rates. Accordingly, the amount of optical information from each sub-beam received by the tracking error signal photo detector is made equal, and the tracking error signal can be accurately detected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.