Patent US4308556A successfully refreshed from Google Patents.
US4308556A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Television video signal scrambling system
Assignee: Faurecia Clarion Electronics Co Ltd
•
Filing: 1980-03-07
•
Granted: 1981-12-29
•
Expires: 2000-03-07
Abstract
Abstract A video signal scrambling system for use with a pay television system in which video signals are scrambled so that only specified subscribers can receive the program. Inversion of the video signal level for scrambling is performed only when the average gradation of the video signals varies relatively largely so that flickering is eliminated from the reproduced picture.
Inventors
- 👤 Hiroshi Osaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:42
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/171; H04N7/1716
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
84 words
A video signal scrambling system for use with a television broadcasting system in which a broadcasting station inverts at least a portion of the video signals with an encoder and transmits the signals while only specified subscribers restore the received video signals through decoders to receive a television program, said scrambling system being characterized by the provision of an apparatus for detecting change in average gradation of said video signals, the output of said detecting apparatus controlling the action for scrambling said video signals.
Claim 2
Dependent Claim
84 words
A video signal scrambling system for use with a television broadcasting system in which a broadcasting station inverts at least a portion of the video signals with an encoder and transmits the signals while only specified subscribers restore the received video signals through decoders to receive a television program, said scrambling system being characterized by the provision of an apparatus for detecting change in average gradation of said video signals, the output of said detecting apparatus controlling the action for scrambling said video signals.
Claim 3
Dependent Claim
78 words
A video signal scrambling system as set forth in claim 1, characterized in that said detecting apparatus comprises a low-pass filter, a differentiation circuit, and a comparator, said differentiation circuit applying a signal corresponding to the rate of change in output of said low-pass filter to said comparator, and said comparator comparing the output of said differentiation circuit with a predetermined reference signal and providing an output when the signal from said differentiation circuit exceeds said reference signal.
References Cited (Backward Citations)
US4022972A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-28 | 1985-06-29 | 1985-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-28 | 1989-06-29 | 1989-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-28 | 1993-06-29 | 1993-12-29 | $7700.00 | Window Closed / Lapsed |