Hidden patterns on a data storage medium
US8144558B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 14, 2005 |
| Grant date | Mar 27, 2012 |
| Priority date | — |
| Expiry date | Sep 27, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/2537
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus and method for providing hidden data to a data storage medium. The hidden data are written by selectively adjusting at least one access parameter of the medium, and preferably by selectively adjusting multiple such parameters. The presence of the hidden data is preferably undetectable to the human eye during unaided visual inspection of the medium, but is revealed by a surface plot of at least a portion of the medium. The surface plot preferably provides a human detectable image of the hidden data to authenticate the medium as an authorized copy. The medium preferably comprises a pre-recorded or recordable optical disc, or a glass master from which such discs are formed. The adjusted access parameter(s) preferably include adjustments in motor velocity, data bit rate, latency time, adjusted symbol length, illegal symbol length, localized reflectivity of the medium, variations in pre-groove amplitude, error rates, and/or localized induced errors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.