Digital compact disc player security system reproducing method and apparatus
US6304971A · kind A · utility
Inventors
Key dates
| Filing date | Aug 16, 1999 |
| Grant date | Oct 16, 2001 |
| Priority date | — |
| Expiry date | Aug 16, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/261
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A security system for preventing disc players from being used with unauthorized software is disclosed. The security code is stored through modulating an offset of the physical position of a plurality of data bits from a nominal track position. A two part optical read head provides an RF signal corresponding to the presence of a physical offset modulation. The RF signal is present when there is a physical offset of the data bits defining a first logical state and the absence of the RF signal defines a second logical state. A digital security code is encoded and decoded in this manner. A system for encoding a security code through modulating the physical offset of a plurality of data bits from a nominal track position is also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.