Method of effecting erasure of optical information media including varying duty cycle, laser power and focus offset
US4949329A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 1988 |
| Grant date | Aug 14, 1990 |
| Priority date | — |
| Expiry date | Apr 27, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0055
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Provided is a process for the erasure of information recorded in an optical information medium. The erasure is effected by irradiating the medium with a laser beam, with the duty cycle, laser power and focus offset having been adjusted from that used during writing such that upon the irradiation complete and clean erasure of the information is effected. It is preferred that the focus offset and laser power are adjusted the minimal amount possible and that the duty cycle is the parameter of the three for which the greatest adjustment is made. Control and adjustment of the three parameters in accordance with the present invention permits one to realize more accurate, efficient and clean erasure, even bit-by-bit erasure if desired, than has heretofore been possible.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.