Method for producing copy protected recorded videotape having uncopyable vertical synchronizing signal partition
US5179452A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 29, 1988 |
| Grant date | Jan 12, 1993 |
| Priority date | — |
| Expiry date | Jul 29, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91314
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A copy protection arrangement for pre-recorded videotape cassettes. The invention includes both a method of protecting and a protected videotape cassette. Copy protection is provided by recording on at least a portion of the original videotape a composite synchronizing signal including a vertical synchronizing pulse having a pulse width in the range of 1-20 micro-seconds and a pulse height discernible by a vertical synchronizing signal separating circuit of the television receiver. All other vertical synchronizing pulse in the vertical synchronizing signal partition, all the equalizing pulses in a equalizing signal partition following the vertical synchronizing signal partition and at least a part of the horizontal synchronizing pulses in a horizontal synchronizing signal partition following the equalizing signal partition in the composite synchronizing signal having respective pulse height less than a predetermined pedestal level of the synchronizing signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.