Patent US3740470A successfully refreshed from Google Patents.
US3740470A
Expired / Lapsed
US
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Noise suppression circuit
Assignee: GTE Sylvania Inc
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Filing: 1971-12-30
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Granted: 1973-06-19
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Expires: 1991-12-30
Abstract
Abstract A noise suppression circuit for television receivers suitable for implementation in integrated circuit form on a monolithic semiconductor chip is shown. Noise pulses of an amplitude greater than the synchronizing pulse amplitude are detected and a signal indicative of the presence of the noize pulses is used to turn on a transistor connected between an amplifier and a source of reference potential to suppress the noise pulses. First and second current sources where the second current source provides a larger current than the first current source are connected in series with the transistor to prevent the transistor from remaining saturated and thereby improperly suppressing synchronizing pulses.
Inventors
- 👤 D Rhee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 19:23
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/345; H04; H04N; H04N5/00; H04N5/14; H04N5/21; H04N5/213
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
188 words
In a television receiver having a signal processing channel for processing a received television signal to provide a composite video signal including video information and synchronizing information in the form of pulses, a noise suppression circuit having an input connected to receive said composite video signal and an output comprising: amplifying means for amplifying said composite video signal; noise detecting means for providing a signal indicative of noise signals having amplitudes greater than the synchronizing pulses; means connecting said amplifying means and said noise detecting means to said input for coupling said composite video signal thereto; a transistor having an output electrode connected to said amplifying means, an input electrode connected to said noise detecting means, and a reference electrode, said transistor being operable to switch to a conducting condition in response to the signal from said noise detecting means to suppress noise signals in said composite video signal; a first current source connected to said reference electrode of said transistor; and a second current source connected to said output electrode of said transistor for providing a current larger than the current provided by said first current source.
Claim 2
Dependent Claim
188 words
In a television receiver having a signal processing channel for processing a received television signal to provide a composite video signal including video information and synchronizing information in the form of pulses, a noise suppression circuit having an input connected to receive said composite video signal and an output comprising: amplifying means for amplifying said composite video signal; noise detecting means for providing a signal indicative of noise signals having amplitudes greater than the synchronizing pulses; means connecting said amplifying means and said noise detecting means to said input for coupling said composite video signal thereto; a transistor having an output electrode connected to said amplifying means, an input electrode connected to said noise detecting means, and a reference electrode, said transistor being operable to switch to a conducting condition in response to the signal from said noise detecting means to suppress noise signals in said composite video signal; a first current source connected to said reference electrode of said transistor; and a second current source connected to said output electrode of said transistor for providing a current larger than the current provided by said first current source.
Claim 3
Dependent Claim
39 words
A noise suppression circuit as defined in claim 1 including a coupling capacitor connected between said reference electrode of said transistor and a source of reference potential for ac coupling said reference electrode to the source of reference potential.
Claim 4
Dependent Claim
28 words
A noise suppression circuit as defined in claim 2 wherein said first current source is connected in parallel with said coupling capacitor for rapidly discharging said coupling capacitor.
Claim 5
Dependent Claim
27 words
A noise suppression circuit as defined in claim 1 wherein said first and second current sources each include a transistor biased to provide a substantially constant current.
Claim 6
Dependent Claim
51 words
A noise suppression circuit as defined in claim 4 wherein said second current source includes a second transistor connected in parallel with the first-named transistor of said second current source for switching to a conducting condition when the voltage of the output electrode of said first-named transistor drops a predetermined amount.
Claim 7
Dependent Claim
224 words
In a television receiver having a signal processing channel for processing a received television signal to provide a composite video signal including video information and synchronizing information in the form of pulses and a synchronizing channel connected to said signal processing channel for receiving at least the synchronizing pulses of said composite video signal for synchronizing the operation of a display device with the received television signal, said synchronizing channel including a noise suppression circuit connected between said signal processing channel and a synchronizing pulse separator, said noise suppression circuit comprising: a first transistor means connected between said signal processing channel and said synchronizing pulse separator for coupling the synchronizing pulses therethrough; a second transistor means for detecting noise signals in said composite video signal having amplitudes greater than the synchronizing pulses and for providing a signal indicative thereof; a transistor having an input electrode connected to said second transistor means, an output electrode connected to said first transistor means, and a reference electrode for suppressing noise signals at said output electrode in response to detection of the noise signals by saId second transistor means; a first current source connected to said reference electrode of said transistor; and a second current source connected to said outPut electrode of said transistor for providing a current larger than the current provided by said first current source.
Claim 8
Dependent Claim
224 words
In a television receiver having a signal processing channel for processing a received television signal to provide a composite video signal including video information and synchronizing information in the form of pulses and a synchronizing channel connected to said signal processing channel for receiving at least the synchronizing pulses of said composite video signal for synchronizing the operation of a display device with the received television signal, said synchronizing channel including a noise suppression circuit connected between said signal processing channel and a synchronizing pulse separator, said noise suppression circuit comprising: a first transistor means connected between said signal processing channel and said synchronizing pulse separator for coupling the synchronizing pulses therethrough; a second transistor means for detecting noise signals in said composite video signal having amplitudes greater than the synchronizing pulses and for providing a signal indicative thereof; a transistor having an input electrode connected to said second transistor means, an output electrode connected to said first transistor means, and a reference electrode for suppressing noise signals at said output electrode in response to detection of the noise signals by saId second transistor means; a first current source connected to said reference electrode of said transistor; and a second current source connected to said outPut electrode of said transistor for providing a current larger than the current provided by said first current source.
Claim 9
Dependent Claim
38 words
A noise suppression circuit as defined in claim 6 including a coupling capacitor connected between said referrence electrode of said transistor and a source of reference potential for ac coupling said reference electrode to source of reference potential.
Claim 10
Dependent Claim
28 words
A noise suppression circuit as defined in claim 7 wherein said first current source is connected in parallel with said coupling capacitor for rapidly discharging said coupling capacitor.
Claim 11
Dependent Claim
27 words
A noise suppression circuit as defined in claim 8 wherein said first and second current sources each include a transistor biased to provide a substantially constant current.
Claim 12
Dependent Claim
57 words
A noise suppression circuit as defined in claim 8 wherein said second current source includes a second transistor biased to provide a substantially constant current and a third transistor connected in parallel with said second transistor for switching to a conducting condition when the voltage of the output electrode of said first-named transistor drops a predetermined amount.
Claim 13
Dependent Claim
50 words
A noise suppression circuit as defined in claim 6 wherein said first transistor means includes a first transistor amplifier connected between said signal processing channel and said output electrode of said transistor and a second transistor amplifier connected between said output electrode of said transistor and said synchronizing pulse separator.
Claim 14
Dependent Claim
37 words
A noise suppression circuit as defined in claim 6 wherein said second transistor means includes a second transistor biased to be nonconductive at the amplitude of the synchronizing pulses and conductive at a predetermined greater signal amplitude.
References Cited (Backward Citations)
US3579251A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |