Focusing error detector and optical data detecting device incorporating the focusing error detector
US4812638A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 28, 1987 |
| Grant date | Mar 14, 1989 |
| Priority date | — |
| Expiry date | Jul 28, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/13922
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A focusing error detector comprises a light source, a collimator lens for making parallel the pencil of rays emitted by the light source, an objective lens which focuses the parallel pencil of rays to form a beam spot on a data-recording disc with data tracks and guide tracks formed thereon and which receives the pencil of rays reflected from the data-recording disc, an optical system for forming a beam spot from the reflected pencil of rays incident to the objective lens, and an optical detector having a plurality of divided optical sensor blocks for receiving the formed beam spot so as to detect the focusing error of the beam spot formed on the data-recording disc on the basis of the configuration of the received beam spot.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.