Optical disc having protective cover
US4672600A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 4, 1986 |
| Grant date | Jun 9, 1987 |
| Priority date | — |
| Expiry date | Mar 4, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B27/19
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical disc assembly has an optical disc and a protective cover. The optical disc has a surface adapted to have optically recorded thereon data consisting of a series of laser ablated pits recorded as a series of concentric data tracks. The pits have small size and high surface density. The protective cover has a permanent optical recording at one surface thereof consisting of a series of visible marks. The marks are an order of magnitude larger than the pits and have a much lower surface density. Memory data is recorded on the optical disc and positional data, comprising a map of the memory data surface, is recorded on the cover. This allows the use of separate positional data and memory data monitoring channels which facilitates the recording of a blank optical disc and subsequent memory data access.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.