The copy protection of optical discs
CA 2513634 C · Owner: Rovi Europe Limited · Inventors: Kovner, Victor; Selve, Philippe Marcel Henri; Heylen, Richard A. A.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The present invention relates to a method of copy protecting optical discs such as CD-ROMs. Instead of encoding data onto the CD-ROMs in a manner which ensures balanced dc content, for copy protection the digital data is encoded and recorded onto the optical disc such that it is arranged to give some of the recorded digital data unbalanced dc content. Thus for example, the DSV , value of the encoded data may be changed rapidly in less than (100) frames to (Figure 9). For an area of digital data on the optical disc in which the DSV has been caused to rise steeply (Figure 10a) heavy distortions in audio arise , (Figure 10c) during an attempt to copy an audio track including the single …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed January 23, 2004 and granted April 9, 2013. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 23, 2024.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 23, 2026.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.