Process and system for optical recording and reading on a mobile data carrier
US4669077A · kind A · utility
12Cited by
6References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 30, 1985 |
| Grant date | May 26, 1987 |
| Priority date | — |
| Expiry date | Aug 30, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0948
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A process and device for focussing a light energy beam on a data carrier comprising sites fromed of virgin areas free from any data recording provided along tracks and serving as reference plane for said focussing. In a preferred variation, these areas are preceded by flags associated with a specific code. Control is achieved by measuring the deviation between the plane of focussing of a beam into a spot scanning the tracks and the reference plane formed by the surface of the virgin areas. Between two passages of these areas of the measurements are stored. The focussing error signal is obtained by filtering these measurements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.