Apparatus for detecting a focus error and a tracking error of an optical head
US5559767A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 27, 1994 |
| Grant date | Sep 24, 1996 |
| Priority date | — |
| Expiry date | Dec 27, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1378
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical composite unit is provided to receive a light focused by a focusing lens for receiving a light reflected from an optical disc. The optical composite unit comprises a cylindrical lens and side-wedge prisms or side-cylindrical lenses which are provided on both sides of the cylindrical lens. The cylindrical lens has a height including a diameter of the focused light and a width narrower than the diameter, and an axis which is rotated by 45.degree. relative to a long axis of a cylindrical beam formed by the cylindrical lens. The side-wedge prisms or side-cylindrical lenses form side beams separated from the cylindrical beam. The cylindrical beam is for detecting a focus error, and the side beams are for detecting a tracking error.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.