Error checking method and apparatus for digital data in optical recording systems
US4145758A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 25, 1977 |
| Grant date | Mar 20, 1979 |
| Priority date | — |
| Expiry date | Oct 25, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An error checking method and apparatus for recording digital data in an optical recording medium. Digital data are written onto the medium by a modulated laser whose beam is detected by a first photodetector means which measures laser output directed toward the recording medium. A second photodetector means measures light scattering from the medium, while a third photodetector detects and measures light transmitted through the recording layer of the medium serving to confirm recording of the data. Amounts of transmitted light or scattered light from the medium are correlated to the laser output and to expected values of light for detecting errors in recording immediately after the time of recording. Reversal processing of the recording medium eliminates a large fraction of potential errors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.