Method and apparatus for disabling anti-copy protection system in video signals
US5194965A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 13, 1990 |
| Grant date | Mar 16, 1993 |
| Priority date | — |
| Expiry date | Nov 13, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91314
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for disabling the effect of copy-protect signals placed in a recording video signals which is based on differences in the characteristics of television and VCR circuitry. Copy-protect signals include pseudo-sync pulses and/or added AGC pulses in the blanking interval of a video signal. The specific method described includes altering the level of the video signal during the vertical blanking interval, e.g., level-shifting, so as to render the copy-protect signals ineffective to prevent unauthorized copying by a VCR. A circuit for achieving the method includes a sync separator for detecting the vertical blanking interval, pulse generating circuits for producing pulses of predetermined widths during this interval, and a summing circuit for summing the predetermined pulses with copy-protect signals thereby to shift their level. An alternative method includes increasing the effective frequency of the copy-protect signals during the vertical blanking interval so as to achieve attenuation and/or low-pass filtering in the VCR circuitry to thereby render the signals ineffective in preventing copying. A circuit for achieving this method includes pulse narrowing and/or …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.