US3609221A
Expired / Lapsed
US
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Video signal identification circuit
Assignee: US Philips Corp
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Filing: 1969-07-09
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Granted: 1971-09-28
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Expires: 1989-07-09
Abstract
Abstract A video signal identification circuit provides a control signal to indicate the absence of either line or field pulse synchronizing signals within a video signal. The line and field pulse groups are separated from the input video signal and selected portions of the field pulse group are suppressed. The remaining line and field pulses are then used as a input to a monostable sawtooth generator which has a natural period exceeding a line period. The output of the sawtooth generator provides an input to a threshold circuit which outputs the control signal in response to the predetermined input signal.
Inventors
- 👤 Erich Langer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:08
CPC Classifications
B; B23; B23K; B23K9/00; B23K9/12; B23K9/124; B23K9/125; H; H04; H04N; H04N5/00; H04N5/44; H04N5/50; H04N5/505
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
136 words
A video signal identification circuit for providing a first output signal when both line pulses and field pulses are present in a video signal and a second output signal when either line pulses or field pulses are absence from a video signal comprising, means to separate line pulse groups and field pulse groups from a video signal, means responsive to an initial field pulse for suppressing subsequent field pulses within a field pulse group, a monostable sawtooth generator having a natural period exceeding one line period responsive to said line pulse group and the field pulses not suppressed, and a threshold circuit coupled to said generator for producing an output signal having a first value when said generator input exceeds a predetermined signal level and a second value for signal levels below said predetermineD signal levels.
Claim 2
Dependent Claim
136 words
A video signal identification circuit for providing a first output signal when both line pulses and field pulses are present in a video signal and a second output signal when either line pulses or field pulses are absence from a video signal comprising, means to separate line pulse groups and field pulse groups from a video signal, means responsive to an initial field pulse for suppressing subsequent field pulses within a field pulse group, a monostable sawtooth generator having a natural period exceeding one line period responsive to said line pulse group and the field pulses not suppressed, and a threshold circuit coupled to said generator for producing an output signal having a first value when said generator input exceeds a predetermined signal level and a second value for signal levels below said predetermineD signal levels.
Claim 3
Dependent Claim
21 words
The video signal identification circuit as claimed in claim 1 wherein said monostable sawtooth generator has a signal dependent charge voltage.
Claim 4
Dependent Claim
45 words
The video signal identification circuit as claimed in claim 1 further comprising a monostable multivibrator which has a natural period in the order of half the period of time between field pulse groups and means by which to connect said multivibrator to said threshold circuit.
Claim 5
Dependent Claim
36 words
The video signal identification circuit as claimed in claim 3 wherein said means by which to connect said multivibrator to said threshold circuit comprises a control stage adapted to invert output signals from said threshold circuit.
Claim 6
Dependent Claim
38 words
The video signal identification circuit as claimed in claim 3 further comprising means by which to feedback signals from said multivibrator to said monostable sawtooth generator whereby the mean value of the output from said generator is changed.
Claim 7
Dependent Claim
21 words
The video signal identification circuit as claimed in claim 5 wherein said means by which to feedback signals comprises a diode.
Claim 8
Dependent Claim
21 words
The video signal identification circuit as claimed in claim 5 wherein said monostable sawtooth generator comprises a signal dependent charge voltage.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |