US3555174A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synchronizing circuit for secam switch
Assignee: Telefunken Patentverwertungs GmbH
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Filing: 1967-10-31
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Granted: 1971-01-12
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Expires: 1987-10-31
Abstract
Abstract The present invention relates to a color television receiver according to the SECAM principle, and to a circuit for synchronizing a line frequency switch in such a receiver. The synchronizing voltage is derived from the color carrier gated during the horizontal retrace. The mean frequency of the carrier is changed from line to line. The gated color carrier is passed to a frequency dependent circuit, e.g. a frequency discriminator or a resonant circuit tuned to one of the mean carrier frequencies. At the output terminals of the frequency dependent circuit there is delivered a voltage with half the line frequency which voltage is used for synchronizing the line frequency switch.
Inventors
- 👤 Walter Bruch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:30
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/44; H04N9/455; H04N9/465; H04N9/47
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
156 words
In a color television receiver adapted to receive a color television signal of the SECAM III b type including two color signals alternately transmitted in line sequence by a color carrier frequency modulated by said color signals, the mean frequency of said carrier being changed from line to line between two different values, and said carrier being transmitted unmodulated with its mean frequency during the horizontal blanking periods, the improvement comprising: a gate means fed with said carrier and being conductive only during the horizontal blanking periods, a frequency dependent circuit means fed with the output of said gate means for producing an output voltage indicating the frequency of said carrier, filter means tuned to one half of the line frequency fed with the output of said frequency dependent circuit means, and a half line frequency operated SECAM switch means, the synchronizing input of said switch means being connected to the output of said filter means.
Claim 2
Dependent Claim
156 words
In a color television receiver adapted to receive a color television signal of the SECAM III b type including two color signals alternately transmitted in line sequence by a color carrier frequency modulated by said color signals, the mean frequency of said carrier being changed from line to line between two different values, and said carrier being transmitted unmodulated with its mean frequency during the horizontal blanking periods, the improvement comprising: a gate means fed with said carrier and being conductive only during the horizontal blanking periods, a frequency dependent circuit means fed with the output of said gate means for producing an output voltage indicating the frequency of said carrier, filter means tuned to one half of the line frequency fed with the output of said frequency dependent circuit means, and a half line frequency operated SECAM switch means, the synchronizing input of said switch means being connected to the output of said filter means.
Claim 3
Dependent Claim
27 words
A color television receiver according to claim 1, wherein said frequency dependent circuit means includes a resonant circuit tuned to one of the two mean carrier frequencies.
Claim 4
Dependent Claim
18 words
A color television receiver according to claim 1, wherein said frequency dependent circuit means is a frequency discriminator.
Claim 5
Dependent Claim
37 words
A color television receiver according to claim 1 wherein said filter means is an oscillator oscillating with one half of the line frequency, said oscillator being synchronized by the output voltage of said frequency dependent circuit means.
Claim 6
Dependent Claim
48 words
In a color television receiver according to claim 3, a local reference carrier generator synchronized by received color synchronizing signals, and means for changing the frequency discriminator into a phase discriminator and feeding the reference carrier of constant phase and frequency to the phase discriminator (PAL/SECAM multistandard receiver).
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) | 1974-01-11 | 1974-07-13 | 1975-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-11 | 1978-07-13 | 1979-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-11 | 1982-07-13 | 1983-01-12 | $7700.00 | Window Closed / Lapsed |