Optical head
US8068403B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 2006 |
| Grant date | Nov 29, 2011 |
| Priority date | — |
| Expiry date | Sep 6, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0013
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
To provide an optical head to produce good servo and read signals by reducing the influence of interference by light reflected from a non-read layer of a multilayer optical disc.The head includes: a first optical system for converging light from a light source on a first or second storage layer; a second optical system for receiving and transmitting light reflected from the first layer and stray light reflected from the second layer when the light is converged on the first layer; a photodetector; and a calculator. The photosensitive areas of the photodetector output signals representing intensities of the light incident there through the second system. The reflected and stray light incident on the second system interfere with each other, and the first and second groups of areas are arranged so as to be equally affected by a variation in intensity caused by the interference. The calculator calculates the difference between sum of a first group of signals supplied from a first group of areas and that of a second group of signals supplied from a second group of areas, thereby generating a focus error signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.